Next Article in Journal
2,3-Diphosphoglyceric Acid Alleviating Hypoxic-Ischemic Brain Damage through p38 MAPK Modulation
Next Article in Special Issue
Phenotypic and Genetic Spectrum in 309 Consecutive Pediatric Patients with Inherited Retinal Disease
Previous Article in Journal
Accurate Long-Read RNA Sequencing Analysis Reveals the Key Pathways and Candidate Genes under Drought Stress in the Seed Germination Stage in Faba Bean
Previous Article in Special Issue
Natural Products in the Treatment of Retinopathy of Prematurity: Exploring Therapeutic Potentials
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
IJMS
Volume 25
Issue 16
10.3390/ijms25168876
ijms-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

AAV-NDI1 Therapy Provides Significant Benefit to Murine and Cellular Models of Glaucoma

by
Sophia Millington-Ward
1,*,†,
Arpad Palfi
1,†,
Ciara Shortall
1,
Laura K. Finnegan
1,
Ethan Bargroff
1,
Iris J. M. Post
1,
John Maguire
2,
Mustapha Irnaten
3,
Colm O′Brien
3,
Paul F. Kenna
1,2,
Naomi Chadderton
1 and
G. Jane Farrar
1
1
The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland
2
The Research Foundation, Royal Victoria Eye and Ear Hospital, Dublin 2, D02XK51 Dublin, Ireland
3
UCD Clinical Research Centre, Mater Misericordiae University Hospital, Dublin 7, D07K201 Dublin, Ireland
*
Author to whom correspondence should be addressed.
†
These authors contributed equally.
Int. J. Mol. Sci. 2024, 25(16), 8876; https://doi.org/10.3390/ijms25168876
Submission received: 9 July 2024 / Revised: 2 August 2024 / Accepted: 4 August 2024 / Published: 15 August 2024
(This article belongs to the Special Issue Advances on Retinal Diseases: 2nd Edition)
Browse Figures
Versions Notes

Abstract

:
Glaucoma, a leading cause of blindness, is a multifactorial condition that leads to progressive loss of retinal ganglion cells (RGCs) and vision. Therapeutic interventions based on reducing ocular hypertension are not always successful. Emerging features of glaucoma include mitochondrial dysfunction and oxidative stress. In the current study, NDI1-based gene therapy, which improves mitochondrial function and reduces reactive oxygen species, was delivered intraocularly via an adeno-associated viral vector (AAV). This AAV-NDI1 therapy protected RGCs from cell death in treated (1552.4 ± 994.0 RGCs/mm2) versus control eyes (1184.4 ± 978.4 RGCs/mm2, p < 0.05) in aged DBA/2J mice, a murine model of glaucoma. The photonegative responses (PhNRs) of RGCs were also improved in treated (6.4 ± 3.3 µV) versus control eyes (5.0 ± 3.1 µV, p < 0.05) in these mice. AAV-NDI1 also provided benefits in glaucomatous human lamina cribrosa (LC) cells by significantly increasing basal and maximal oxygen consumption rates and ATP production in these cells. Similarly, NDI1 therapy significantly protected H2O2-insulted primary porcine LC cells from oxidative stress. This study highlights the potential utility of NDI1 therapies and the benefits of improving mitochondrial function in the treatment of glaucoma.

Graphical Abstract

1. Introduction

Glaucoma is a complex group of optic neuropathies and a leading cause of blindness. It is thought to affect in the region of 70–80 million people worldwide, with approximately 10% of patients being blind. Indeed, 2.93% of people in Europe aged between 40 and 80 years have been reported to have glaucoma, rising to 10% of persons over 90 years of age [1,2,3,4]. The condition is classified into open-angle glaucoma, where the anterior chamber remains open, and closed-angle glaucoma, with closure of the drainage angle leading to impairment of the aqueous outflow. It is a multifactorial condition with risk factors, including advanced age, genetics, myopia, and elevated intraocular pressure (IOP), with the greatest being the latter [1]. At present, the only modifiable risk factor is IOP; therefore, current glaucoma treatments are based on lowering IOP with topical eye drops, surgery, or laser therapy. However, the outcomes of these treatments are variable, with some patients not responding and/or suffering from serious side effects, while others present with a normotensive form of glaucoma, where increased IOP is absent [5]. Notably, all glaucoma patients suffer a characteristic progressive loss of the visual field, mainly due to the progressive loss of retinal ganglion cells (RGCs). Pathology occurs in the RGC soma in the inner retina and in RGC axons, which radiate toward and constitute the main component of the optic nerve head (ONH) and optic nerve, which conveys visual information to the brain [6].
The exact mechanism by which RGCs are lost in glaucoma is not yet fully understood, nor is the mechanism by which increased IOP may lead to their death. However, mechanical distortions of the ONH due to increased IOP are thought to lead to remodelling of the extracellular matrix and fibrosis in the LC [7]. This, in turn, may lead to ischaemia-hypoxia damage, blockage of axonal transport, and deprivation of neurotrophic factors, as well as functional changes in astrocytes and microglia, all of which may contribute to RGC death [8,9,10,11,12]. RGCs have high energy demands, making them highly reliant on healthy mitochondrial function. Mitochondrial dysfunction resulting in reduced mitochondrial bioenergetics and increased oxidative stress has been observed in RGCs of glaucoma patients and multiple animal models of glaucoma and is known to contribute to the apoptosis of RGCs [13,14,15,16,17,18,19,20,21,22,23,24].
Oxidative stress and mitochondrial dysfunction have been associated with many other neurodegenerative conditions, including Parkinson’s disease, Alzheimer’s disease, motor neuron disease, and retinal degeneration, such as age-related macular degeneration (AMD) and diabetic retinopathy [25,26,27,28]. In glaucoma, oxidative stress and mitochondrial dysfunction have been reported not only in RGCs [13,14,15,16,17,18,19,20,21,22,23,24,29] but also in the trabecular meshwork (TM) [30,31,32,33,34,35,36,37,38,39,40],the LC [41] and ONH [42,43,44,45,46,47,48]. The TM is a key regulator of IOP and aqueous drainage in the anterior chamber, while the LC is a sieve-like structure at the ONH, through which the RGC axons and retinal blood vessels pass.
Glaucoma is a complex disease with diverse phenotypes; hence, generating appropriate animal and cellular models for this condition is challenging. In vivo models are frequently based on surgically induced increases in IOP [49]. Genetic models of glaucoma offer a more gradual onset and progression and, therefore, may be more representative of the condition. The DBA/2J mouse model [22,50] displays some phenotypic similarities with glaucoma. For example, mice have excessive iris pigment dispersion, which blocks the TM, leading to aqueous humour accumulation, a steady increase in IOP between 6 and 11 months of age, and loss of RGCs [51,52]. Reduced ATP in RGCs is thought to interfere with the transmission of the visual signal along the optic nerve [53,54], which precedes axon structural changes and impairments in anterograde transport [55,56]. Electrophysiological (ERG) decline [57,58], morphological changes in mitochondria [59], and inflammation in RGC compartments [60,61,62,63] have also been demonstrated in DBA/2J mice.
LC cells from glaucoma patients have been used as an in vitro model of the disease and shown to have reduced levels of ATP, as well as reduced oxidative phosphorylation and elevated glycolysis [64]. An elevated number of mitochondria and increased calcium and ROS levels suggest mitochondrial dysfunction [41,65,66]. LC cells experimentally exposed to H2O2 to mimic the oxidative stress environment associated with glaucoma represent another in vitro model for this disease.
NDI1 is a nuclear-encoded complex I equivalent derived from S. cerevisiae. A variety of optimised NDI1 constructs have been shown by us to provide benefits in in vitro and in vivo models of dry AMD, primary fibroblasts from a Leber hereditary optic neuropathy (LHON) patient, and a rotenone-induced murine model of RGC dysfunction [67,68,69,70]. In the current study, an enhanced NDI1 gene (eNdi1) was explored as a gene-independent gene therapy for glaucoma [70]. The therapy is aimed at improving mitochondrial function and decreasing ROS in a variety of glaucoma models: aged DBA/2J mice, primary human glaucomatous LC cells, and primary porcine LC cells insulted with H2O2.

2. Results

It is well established that mitochondrial dysfunction and increased ROS levels are key features of many neurodegenerative disorders, including glaucoma. In the current study, the benefit of eNdi1 constructs delivered via adeno-associated viral vectors (AAV-eNdi1) driven by CMV and CAG promoters was analysed in two in vitro models of glaucoma and in vivo in the DBA/2J murine model of glaucoma. Effects on mitochondrial function and disease progression have been analysed.

2.1. AAV-eNdi1 Provides Benefit in H2O2-Insulted Porcine LC Cells

To determine whether AAV-eNdi1 could rescue cell models of glaucoma, H2O2-insulted primary porcine LC cells (pLC cells) were utilised. pLC cells were transduced with AAV-eNdi1 (MOI = 8 × 103). 48 h post-transduction, cells were insulted with 750 μM H2O2 for 1 h and compared in a mitochondrial stress test to uninsulted control cells and insulted cells that had not received AAV-eNdi1. The basal oxygen consumption rate (OCR, a measure of mitochondrial function) of control pLC cells was considered to be 100%. H2O2 insult significantly reduced basal OCR levels (70.6 ± 37.3% versus 100.0 ± 50.2%), maximal OCR levels (82.7 ± 23.3% versus 118.2 ± 28.3%), and ATP production (48.6 ± 32.4% versus 71.8 ± 37.7%), indicating that oxidative stress significantly reduces mitochondrial function in H2O2-insulted pLC cells. Notably, the basal OCR, maximal OCR, and ATP production levels were significantly higher in H2O2-insulted cells that had received AAV-eNdi1 (123.9 ± 39.4%, 137.5 ± 32.3%, and 81.5 ± 28.1%, respectively), indicating rescue of mitochondrial function in the model (Figure 1A,B).
Elevated ROS can be a hallmark feature of mitochondrial dysfunction and a symptom of glaucoma [71], and the ability of AAV-eNdi1 to reduce ROS levels in the H2O2-insulted pLC model was investigated. Cells were transduced with AAV-eNdi1 (MOI = 2.5 × 103). 24 h post-transduction, cells were insulted with 750 μM H2O2 for 30 min (n = 6), and ROS levels compared to levels in untransduced insulted cells (n = 6) and control cells that had not been transduced or insulted (n = 8). Median CellROX fluorescence levels, indicating relative ROS levels, in control cells were considered to be 100%. Relative ROS levels were significantly higher in H2O2-insulted cells than in control cells (140.5 ± 7.91% versus 100.0 ± 8.05%, respectively); however, these levels were reduced in H2O2-insulted cells that had received AAV-eNdi1 (127.9 ± 4.1%; Figure 1C).
The effects of eNdi1-treatment in the H2O2-insulted pLC model were also analysed by immunocytochemistry. Cells were transfected with eNdi1 (n = 6; Figure 1F,I) or pAAV-MCS (n = 6; Figure 1E,H) plasmid DNA; 48 h later, cells were insulted with 750 μM H2O2 for 1 h, and then fixed. Transfected cells were compared to control pLC cells that had not been transfected or insulted (n = 5; Figure 1D,G). Cells were stained with Phalloidin-iFluor 647 (detecting F-actin) and anti-CPN60 antibody (mitochondrial stress marker, Cy3-labelled secondary antibody), and nuclei were counterstained with DAPI. H2O2 insult resulted in a change in the morphology of the pLC cells, as visualised by F-actin staining (Figure 1D–I). The insulted cells were more spindle-shaped compared to control cells, which displayed more cell spreading, almost filling up the available surface area. The pattern of CPN60 staining was more punctuated in H2O2-insulted cells, while the CPN60 staining intensity was also significantly increased compared to uninsulted control cells (Figure 1 D–I). The relative number of cells with elevated intensity of the CPN60 label was quantified by fluorescence microscopy (Figure 1J) and compared to insulted cells that had been treated with eNdi1; the relative number of untreated control cells was taken to be 100% (± 41.8%). The percentage of cells with elevated levels of CPN60 in H2O2-insulted cells with eNdi1 or without eNdi1 was 205.9 ± 88.2% and 329.4 ± 82.4%, respectively, indicating that eNdi1 significantly reduced mitochondrial stress in insulted cells (p < 0.05). H2O2 insult also resulted in an increased number of apoptotic cell nuclei (identified by DAPI staining; Figure 1D–I), which were also quantified by fluorescence microscopy (Figure 1K). In particular, apoptotic nuclei were 142 ± 49/mm2 and 326.5 ± 100.2/mm2 (p < 0.01) for eNdi1 treated and untreated H2O2-insulted cells, respectively, while they were 117.9 ± 58.5/mm2 in untreated control cells. The total number of nuclei was 703.5 ± 79.8/mm2, 654.3 ± 85.2/mm2, and 739.7 ± 57.5/mm2, respectively, in the above groups of cells and did not differ significantly. As such, eNdi1 treatment provided benefits in three phenotypes; eNdi1 treated cells maintained their spread-out morphology, mitochondrial stress was significantly reduced, and there were fewer apoptotic cells, the latter two quantified by microscopy (Figure 1C–K).
In summary, in the H2O2-insulted pLC model, eNdi1 rescued mitochondrial function, reduced cellular ROS levels, and reduced mitochondrial stress and apoptosis.

2.2. AAV-eNdi1 Provides Benefit in Human Glaucomatous LC Cells

Mitochondrial function was analysed in a second in vitro model for glaucoma in human primary glaucomatous LC cells (Figure 2). LC cells from an unaffected, age-matched person were used as a control. Glaucomatous LC cells were transduced with AAV-eNdi1 (MOI = 8 × 105), and mitochondrial function was assessed 48 h later using a mitochondrial stress test. Treatment of glaucomatous LC cells with AAV-eNdi1 significantly increased the basal oxygen consumption rate (OCR; 136.70 ± 18.63 pmol/min versus 91.90 ± 17.87 pmol/min; p < 0.001) and maximal OCR (284.00 ± 66.47 pmol/min versus 159.30 ± 33.19 pmol/min; p < 0.01), and there was a trend toward increased ATP production levels (69.20 ± 7.35 pmol/min versus 58.55 ± 12.92 pmol/min; p < 0.05). Notably, OCR levels remain high in AAV-eNdi1-treated cells post rotenone insult because, in contrast to endogenous complex I, eNdi1 is insensitive to rotenone, and hence respiration continues in the rotenone-insulted cells (A).

2.3. AAV-eNdi1 Provides Benefit in the DBA/2J Murine Model of Glaucoma

In addition to the in vitro models of glaucoma, H2O2-insulted pLC cells, and human glaucomatous LC cells, the murine DBA/2J mouse model of glaucoma was utilised in the study. This model is late-onset with a variable phenotype; hence, it was necessary to use a large number of mice. Consistent with the literature, pigmentary displacement in the iris was observed in twelve-month-old (aged) DBA/2J mice (Figure 3A–H). In addition, a significant loss of RGCs was observed in aged DBA/2J mice (984.7 ± 867.3; n = 7) compared to two-month-old DBA/2J mice (3050.2 ± 301.3; n = 14) two-month-old C57BL/6J mice (2972.4 ± 234.4 RGCs/mm; n = 9) and twelve-month-old C57BL/6J mice (2647.3 ± 353.9 RGCs/mm; n = 14). Notably, differences in RGC numbers of two-month DBA/2J, two-month C57BL/6J, and twelve-month-old C57BL/6J mice were not significant (Figure 3D,E,I–K).
Evaluation of RGC loss in AAV-eNdi1 treated mice was undertaken as a measure of therapeutic efficacy. Two-month-old DBA/2J mice were intravitreally injected with 4.1 × 107 vg AAV-eNdi1 in one eye, while the contralateral eye received an equal volume of PBS. Ten months post-injection, photonegative responses (PhNRs), representing RGC function, were analysed from photopic single-flash cone responses and compared to PhNRs of age-matched C57BL/6J control mice (Figure 4A–C). AAV-eNdi1-treated eyes displayed significantly improved PhNR infections compared to control PBS-injected eyes (6.4 ± 3.3 µV and 5.0 ± 3.1 µV, respectively, p < 0.05, paired t-test; n = 25). Notably, when the untreated eyes were assigned a value of 100% to normalise for the variable nature of the DBA/2J murine model, PhNRs in treated versus untreated eyes, were 127.0 ± 66.9% and 100 ± 62.1%, respectively (paired Student’s t-test; p < 0.05). Importantly, PhNRs in treated DBA/2J mouse eyes were not significantly different from PhNRs in control C57BL/6J mice (8.6 ± 2.2 µV, n = 9, p = 0.07, Student’s t-test).
In addition, the implicit time of the single-flash cone b-waves was found to be significantly delayed in untreated DBA/2J versus control C57BL/6J mice (Figure 4A,B,D; 60.1 ± 5.2 ms, n = 32, and 51.2 ± 6.6 ms, n = 28, respectively, p < 0.05, Student’s t-test). Notably, this delay was significantly reduced in AAV-eNdi1-treated DBA/2J mice versus untreated DBA/2J mice (58.8 ± 5.5 ms and 60.1 ± 5.2 ms, respectively, n = 28, p < 0.01, paired t-test), although this did not reach levels found in C57BL/6J mice. Implicit times of photopic a-waves did not differ between the treated and untreated DBA/2J mouse eyes.
To determine whether the functional benefits mediated by AAV-eNdi1 in DBA/2J mice (Figure 4A–D) were reflected at the histological level and resulted in RGC preservation, retinal wholemounts were prepared to enable RGC analysis. RGCs were labelled with BRN3A immunocytochemistry and quantified via fluorescence microscopy at twelve-month of age (10 months post-AAV delivery). Representative wholemounts of control PBS-injected and AAV-eNdi1 treated retinas are shown in (Figure 4E,F). RGC numbers in wholemounts were compared in AAV-eNdi1-treated (1552.4 ± 994.0 RGCs/mm2) versus untreated (1184.4 ± 978.4) eyes were significantly higher (n = 37, p < 0.05, paired t-test; Figure 4G).
Complex I and eNdi1 catalyse the oxidation of NADH; hence, the measurement of the NADH oxidation rate in isolated retinal mitochondria enables direct evaluation of complex I and eNdi1 function. By including rotenone in the NADH oxidation rate assay, the NADH oxidation rate arising from eNdi1 activity, which is rotenone-insensitive, can be distinguished from the NADH oxidation rate arising from endogenous complex I activity (which is sensitive to rotenone; Figure 4H). NADH oxidation rate was determined by measuring the rate of decrease in absorbance at 340 nm, which occurs when NADH is oxidised to NAD+ and normalised to total protein [72]. The NADH oxidation activities in mitochondria extracted from treated and untreated DBA/2J retinas were 29.8 ± 4.7 nmol/min/mg and 19.8 ± 7.8 nmol/min/mg, respectively (n = 7, p < 0.05), and in optic nerves were 37.9 ± 15.5 nmol/min/mg and 13.0 +/− 4.5 nmol/min/mg, respectively (n = 4 per group, each sample comprising four pooled optic nerves, p < 0.05). These data indicate that AAV-eNdi1 significantly increases NADH oxidation activity in both the whole retina and optic nerve. This increase is more pronounced in the optic nerve, as post-intravitreal injection AAV-eNdi1 transduces RGCs and the optic nerve efficiently. Hence, in mitochondria from the whole retina, where RGCs are thought to represent only 0.5–1.3% of retinal cells, depending on the mouse strain and age, the overall effect is less pronounced [73].
In conclusion, these data indicate that AAV-eNdi1 provides a functional benefit in DBA/2J mice with an increase in PhNRs and a reduction in the latency of the single-flash b-wave observed. In addition, RGCs were protected, and NADH oxidation rates increased in treated versus untreated DBA/2J mice.

3. Discussion

Glaucoma is a complex and common condition with diverse genetic and phenotypic profiles. Currently, there are thought to be around 170 genetic loci associated with an increased risk of developing primary open-angle glaucoma (POAG) [74,75,76]. In addition, environmental factors such as diet, corticosteroid use, and diabetes mellitus are some risk factors identified to date [77]. Given the complexity of the condition, overarching next-generation therapies aimed at preserving RGCs or lowering IOP via the TM and ciliary body are being considered, with multiple IOP-lowering drugs in use. Potential novel therapies under investigation include those targeting genes involved in decreasing aqueous humour production and increasing its outflow [78] and protective agents, such as growth factors and immunomodulators. Additionally, because apoptosis is considered to be an ultimate driver of RGC cell death in glaucoma [79], anti-apoptotic agents for glaucoma are also being investigated.
For example, AAV-delivered matrix metalloproteinase-3 (MMP-3)-mediated gene therapy has been shown to increase outflow and reduce IOP in a variety of glaucoma models [80]. In addition, sirtuin 1 (SIRT-1), which encodes an NAD+-dependent deacetylase, has been shown to protect RGCs in an optic nerve crush [81,82] and an IOP model of glaucoma [83]. Anti-apoptotic agents such as Xiap have been shown to provide neuroprotection in a number of rodent models [84,85]. Similarly, SIRT-6 overexpression has been shown to be protective in glaucoma models [86], as has Tau protein modulation [87], among others. Oral administration of nicotinamide (vitamin B3), an adenine dinucleotide (NAD+) precursor, as well as AAV-delivered murine nicotinamide nucleotide adenylyltransferase 1 (Nmnat1), which catalyses the synthesis of NAD, have been shown to protect RGCs in the DBA/2J mouse [14]. Typically, these new innovative therapies are still in the early stages of development. However, multiple clinical trials for glaucoma are in progress to analyse the effects of orally delivered nicotinamide [88,89,90]. Due to the patient burden and some nicotinamide-induced liver damage observed during a recent trial [91], gene therapies, such as a therapy expressing, for example, human NMNAT1 (see above), may be a preferable option.
Clearly, many factors may contribute to the development of glaucoma, including environmental and genetic factors. However, while the exact mechanism remains unknown, mitochondrial dysfunction and oxidative stress are typical hallmarks of glaucoma [92,93]. Hence, in the current study, eNdi1 gene therapy aimed at directly improving mitochondrial function, reducing ROS, and preserving RGCs was investigated. eNdi1 gene therapy has previously been shown to boost mitochondrial function and reduce oxidative stress in a range of murine and cellular models of dry AMD and chemically induced models of RGC loss [67,68,70]. Generally, a limitation of gene therapy studies on glaucoma has been that no model recapitulates all aspects of the human condition. While non-human primate (NHP) models of glaucoma, such as the NHP experimental glaucoma (EG) model and laser-induced models, have a similar retinal architecture to the human retina, these models also have limitations, such as late and variable age of onset and phenotypic variability, as well as high cost and ethical considerations [94,95]. To mitigate against this limitation, a variety of different models, all displaying aspects of the condition, were chosen for the current study. Firstly, aged DBA/2J mice, a high-tension model, were utilised. Williams et al. demonstrated mitochondrial abnormalities as an early driver of glaucoma in DBA/2J mice. Genes involved in mitochondrial dysfunction and oxidative phosphorylation pathways were significantly enriched in RGCs from the mice. Indeed, important metabolites that are key to mitochondrial function and protection from ROS, including NAD+ and NADH, were significantly decreased from 4 months of age [14]. Interestingly, mitochondrial dysfunction was observed before degeneration was apparent. It is believed that in this model, elevated IOP leads to an increase in dephosphorylation of mitochondrial dynamin-related protein 1 (Drp1), a fundamental component of mitochondrial fission, leading to an increase in mitochondrial fragmentation and apoptosis of neuronal cells [96,97]. In addition, an increase in apolipoprotein A–I binding protein (AIBP, an important regulator of autophagy) expression has also been observed, resulting in increased mitochondrial fission and reduced ATP production [98]. Similar changes have been observed in multiple other models of glaucoma [99,100,101]. In addition, primary glaucomatous LC cells, a patient-derived model, were used in the current study. These cells have been shown to display reduced mitochondrial function and increased oxidative stress, known markers of glaucoma [64,65,66]. Finally, primary pLC cells insulted with H2O2 were utilised. H2O2 has been shown to induce the expression of profibrotic extracellular matrix genes in LC and TM cells [102,103,104], similar to that observed in glaucoma patients, as well as increase ROS [105,106].
Notably, mitochondrial function was increased, and ROS was reduced in cell models, while the PhNR responses and RGC cell numbers were increased in DBA/2J mice, demonstrating functional and histological rescue by the therapy. Interestingly, the implicit time of the light-adapted single-flash cone b-wave was found to be delayed in aged DBA/2J mice, a finding also reported by Harazny et al. [58], who also found an extremely degraded flicker electroretinography (ERG) response in these mice. The flicker response is known to be driven by the inner retinal cone system, specifically ON and OFF bipolar cells with initial input from cone photoreceptor cells, while the single-flash light-adapted b-wave is resoundingly ON and OFF bipolar cells in origin. AAV-eNdi1 was shown to reduce the time delay of the single-flash light-adapted b-wave in aged DBA/2J mice, indicating that the observed benefit may originate directly from some degree of protection of second-order neurones, or, more probably indirectly, as a result of RGC preservation. Analyses in DBA/2J mice were undertaken at 10 months post-injection. We and others have previously shown that AAV2/2 transduces mainly RGCs following intravitreal injection, and the area of transduction encompasses most of the retina [69,107]. In addition, the expression is known to be maintained for at least 18 months [108].
In conclusion, in the current study, we have shown that eNdi1 directly increases mitochondrial function in cell models of glaucoma. Additionally, we showed that ROS and mitochondrial stress were reduced, while cellular health was improved. RGCs and visual function were increased in the DBA/2J model of glaucoma, a mouse model known to display mitochondrial dysfunction, indicating that directly increasing mitochondrial function can protect mice and provide significant benefits. Of note, a key differentiator between other approaches, such as NMNAT1 and SIRT-1 gene therapies, which also modulate mitochondrial dysfunction, and the therapeutic strategy for glaucoma demonstrated in the current study, is that eNdi1, as a complex I equivalent, directly participates in the electron transport chain. Given the increasing prevalence of glaucoma in the ageing population, it is imperative that novel therapies, such as the current once-off gene therapy, are further developed and commercialised.

4. Materials and Methods

4.1. Study Design

An enhanced NDI1 gene, eNdi1, was delivered via a recombinant AAV or a plasmid to models of glaucoma: DBA/2J mice, LC cells from a glaucoma patient, and porcine LC cells that had been insulted with H2O2. Functional benefit was demonstrated using ERG, and histological benefit was demonstrated by assessing the preservation of RGCs. In addition, increased NADH oxidation rates, reduced cellular ROS, improved OCRs (indicating mitochondrial function), and improved morphological features were assessed.

4.2. Plasmid Constructs and AAV Production

Plasmid constructs eNdi1 (patent no 10220102) and CAG-EGFP have been described previously [109]. CMV and CAG promoter-driven eNdi1 (Figure 5) and CAG-EGFP were packaged into AAV2/2 by helper virus-free triple transfection as previously described [110], generating AAV-eNdi1 and AAV-EGFP. Genomic titres (vg/ml) were determined by RT-qPCR [111].

4.3. LC Cell Characterisation, Cell Culture and Mitochondrial Stress Test

Eyes from a male donor diagnosed with glaucoma (age 86) and a normal female control (age 88) were obtained from the Central Florida (Tampa) Eye Bank for Transplant and Research within 24 h post-mortem. The presence of glaucoma was confirmed based on retrieved medical records and/or confirmation of previous glaucoma diagnosis by family members. The eyes were obtained and managed in compliance with the Declaration of Helsinki for research involving human tissues. The eyes were cut flush with the posterior sclera and imaged from the posterior cut surface. The optic nerves of the specimens were examined, and the specimens were further classified. LC cells were isolated from single ONH explants from human donor eyes as previously described [112]. Cells were characterised for markers including α-SMA stain (expressed by LC cells), GFAP (astrocyte marker), and Iba1 (microglial marker) as previously described [113,114]. The cells were kindly provided by Professor Abbot Clark (Alcon Labs, Fort Worth, TX and Duke University, Durham, NC, USA). Mitochondrial stress tests were performed on a Seahorse XFe96 analyser (Agilent) as follows. 1.5 × 104 human LC cells were seeded into wells of a 96-well Seahorse plate (Agilent). Two days post-seeding, cells were transduced with CAG-driven AAV-eNdi1, MOI = 8 × 105. Two days post-transduction, a mitochondrial stress test was performed (Agilent Technologies, Santa Clara, CA, USA). Injection cycles were 5× for basal OCR, 5× following oligomycin (1.0 μM), 5× following FCCP (1.0 μM), 5× following rotenone (0.5 μM), and 5× following antimycin A (0.5 μM) injections [115,116]. Groups consisted of a minimum of 5 replicate wells, and mitochondrial stress tests were performed 8 times.
Porcine LC cells were isolated from fresh eyes obtained from a local abattoir, as previously described [112]. LC cells (3 × 104 LC cells were seeded into the wells of a 96-well Seahorse plate (Agilent Technologies, Santa Clara. CA, USA). Two days post-seeding, the cells were transduced with CAG-driven AAV-eNdi1, MOI = 8 × 103. Two days post-transduction, cells were insulted with 750 μM H2O2 in a medium at 37 °C for 1 h. Subsequent to insult, cells underwent an Agilent mitochondrial stress test as described above. Groups consisted of a minimum of 5 replicate wells, and mitochondrial stress tests were performed 7 times.

4.4. Cellular ROS Assay

5 × 104 cells primary porcine LC cells were seeded into 96-well culture plates (Sarstedt, Nümbrecht, Germany) and were transduced the following day with CAG-driven AAV-eNdi1 (MOI = 2.5 × 103). Two days post-transduction, cells were insulted with 750 μM H2O2 in a medium for 30 min at 37 °C. Subsequent to insult, a cellular ROS assay was performed using CellROX green (Thermo Fisher, Waltham, MA, USA) and flow cytometry as previously described [67].

4.5. pLC Transfection Immunocytochemistry

2 × 106 pLC cells were transfected (Amaxa biosystems, Nucleofector II/2B) with the Cell Line Nucleofector Kit L, using a 4.5:1 ratio of supplement to Nucleofector solution, and program C-005 with 2µg of AAV-eNdi1 plasmid DNA [70], or pAAV-MCS (Agilent Technologies Inc, Santa Clara, USA; control) as per manufacturer’s instructions. (Lonza Group AG, Basel, Switzerland). Following transfection, 1.5 × 105 LC cells were seeded onto 8-well imaging slides (Milenyi Biotec, Bergisch Gladback, Germany). 48 h post-transfection cells were insulted with 750 μM H2O2 for 1 h at 37 °C, then gently washed in PBS and fixed in 4% paraformaldehyde in PBS at RT for 20 min. Cells were stained for F-actin (Phalloidin-iFluor 647, Abcam, Cambridge, UK) and CPN60 (EnCor Biotechnology, Gainesville, FL, USA), and nuclei were counterstained with DAPI as previously described [67].

4.6. Intravitreal Injection and Electroretinography in Mice

DBA/2J and C57BL/6J mice (Jackson Laboratories, Bar Harbor, ME, USA) were maintained under specific pathogen-free conditions. The injections were performed in strict compliance with the European Union Regulations 2012 (S.I. no. 543 of 2021) and the Association for Research in Vision and Ophthalmology (ARVO) statement for the use of animals. The study was approved by the local Animal Research Ethics Committee of Trinity College Dublin (Ref. no. 140514/240320). Intravitreal injections were performed as previously described [69,70]. Briefly, two-month-old DBA/2J mice were intravitreally injected with 3 μl of PBS containing either 4.1 × 107 vg AAV-eNdi1 (driven from the CMV promoter) or 4.1 × 107 vg AAV-EGFP or PBS only. PhNRs and photopic a- and b-wave implicit times were recorded at 12 months of age, as described previously [69,70,116].

4.7. NADH Oxidation Rate Assay

NADH oxidation rates in retinas from one-year-old DBA/2J mice, intravitreally injected at two months of age with 4.1 × 107 vg AAV-eNdi1 in one eye and an equal volume (3 μl) of PBS in the contralateral eye (n = 7), were compared. Additionally, ONs from similarly treated and untreated eyes (n = 4, where each sample represented 4 pooled ONs) were compared. Retinas and ONs were snap-frozen, and mitochondria were isolated as previously described [69]. NADH oxidation rate was determined by measuring the rate of decrease in absorbance at 340 nm, which occurs when NADH is oxidised to NAD+ and was normalised to total protein [72]. NADH oxidation rates on mitochondria were measured twice per sample, and duplicate readings were averaged as previously described [70,72]. In addition, following the addition of rotenone, 50 μM flavone was added to inhibit NDI1 protein activity to determine background levels of NADH oxidation rate. Total NADH oxidation rates, arising from both complex I and NDI1, were measured before the addition of the complex I inhibitor rotenone, while NADH oxidation rates from NDI1 alone (which is rotenone-insensitive) were measured after the addition of rotenone and before the addition of flavone.

4.8. Retinal Wholemounts and Immunohistochemistry

Mice were sacrificed at 1 year of age, and retinas were fixed in 4% paraformaldehyde. RGCs in whole retinas were stained with anti-BRN3A (Synaptic Systems, Goettingen, Germany) primary antibody and detected with Cy3-conjugated secondary antibody (Jackson ImmunoResearch Laboratories, West Grove, PA, USA), as previously described [70].

4.9. Fluorescence Microscopy

Microscopy was performed using an Olympus IX83 fluorescence microscope system (Mason Technology, Dublin, Ireland), SpectraX LED light source (Lumencor, Beaverton, OR, USA), and an Orca-Flash4.0 LT PLUS/sCMOS camera (Hamamatsu, Tsukuba City, Japan [109]). RGC quantification in retinal wholemounts was performed as described [70]. For the quantification of pLC cells, fluorescence intensity thresholds for CPN60 and DAPI signals were determined experimentally and set to differentiate between high and low label intensities. The same thresholds were used for all samples. The sum of the area of cells with a high-intensity threshold (CPN60) or the number of objects with high and high plus low signal intensities (DAPI) were determined using the Olympus CellSens software (v1.9).

4.10. Statistical Analysis

Statistical analysis was performed using GraphPad Prism (version 9.4; GraphPad Software, Boston, MA, USA). Student’s t-tests or paired Student’s t-tests were used to compare data between the two groups. ANOVA with Šídák’s multiple comparisons test was used to compare data between more than 2 groups. Differences were considered statistically significant at p < 0.05. Error bars represent standard deviations of the mean.

Author Contributions

Conceptualisation, G.J.F., S.M.-W., A.P., C.S. and N.C.; methodology, S.M.-W., A.P., C.S., N.C., G.J.F., C.O., M.I., P.F.K., E.B. and L.K.F.; software, L.K.F., S.M.-W., A.P. and C.S.; validation, S.M.-W., A.P., C.S., N.C., E.B., P.F.K., L.K.F. and I.J.M.P.; formal analysis, S.M.-W., A.P. and L.K.F.; investigation, S.M.-W., A.P., C.S., N.C., P.F.K., E.B., L.K.F. and I.J.M.P.; data curation, S.M.-W., A.P., C.S. and L.K.F.; writing—original draft preparation, S.M.-W.; writing—review and editing, S.M.-W., A.P., C.S., N.C., I.J.M.P., J.M., L.K.F., C.O., M.I., G.J.F. and P.F.K.; visualisation, A.P. and L.K.F.; supervision, G.J.F., S.M.-W., A.P. and N.C.; project administration, G.J.F.; funding acquisition, G.J.F. and S.M.-W. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Science Foundation Ireland (16/IA/4452 and 22/FFP-A/10544), Health Research Board Ireland (HRAPOR-2015-1140), EU Marie Curie Innovative Training Network (StarT 813490), and Fighting Blindness Ireland—Health Research Charities Ireland (MRCG-2016-14).

Institutional Review Board Statement

All animal work was performed in accordance with the European Union (Protection of Animals used for Scientific Purposes) Regulations 2012 (S.I. no. 543 of 2012) and the Association for Research in Vision and Ophthalmology (ARVO) statement for the use of animals, and was reviewed and approved by the animal research ethics committee at Trinity College Dublin. Ref. no. 140514/240320.

Informed Consent Statement

Not applicable.

Data Availability Statement

The datasets used and/or analysed during the current study are available from the corresponding author upon reasonable request.

Acknowledgments

We would like to thank Comparative Medicine for animal husbandry. We thank Abbot Clark (Alcon Labs, Fort Worth, TX and Duke University, Durham, NC, USA) for providing the human LC cells.

Conflicts of Interest

S.M.-W., N.C., P.F.K., and G.J.F. are inventors on patent no 10220102.

References

  1. Quigley, H.A.; Broman, A.T. The number of people with glaucoma worldwide in 2010 and 2020. Br. J. Ophthalmol. 2006, 90, 262–267. [Google Scholar] [CrossRef] [PubMed]
  2. Schuster, A.K.; Erb, C.; Hoffmann, E.M.; Dietlein, T.; Pfeiffer, N. The Diagnosis and Treatment of Glaucoma. Dtsch. Arztebl. Int. 2020, 117, 225–234. [Google Scholar] [CrossRef]
  3. Bourne, R.R.A.; Stevens, G.A.; White, R.A.; Smith, J.L.; Flaxman, S.R.; Price, H.; Jonas, J.B.; Keeffe, J.; Leasher, J.; Naidoo, K.; et al. Causes of vision loss worldwide, 1990–2010: A systematic analysis. Lancet Glob. Health 2013, 6, 339–349. [Google Scholar] [CrossRef] [PubMed]
  4. Tham, Y.C.; Li, X.; Wong, T.Y.; Quigley, H.A.; Aung, T.; Cheng, C.Y. Global prevalence of glaucoma and projections of glaucoma burden through 2040: A systematic review and meta-analysis. Ophthalmology 2014, 121, 2081–2090. [Google Scholar] [CrossRef] [PubMed]
  5. Killer, H.E.; Pircher, A. Normal tension glaucoma: Review of current understanding and mechanisms of the pathogenesis. Eye 2018, 32, 924–930. [Google Scholar] [CrossRef] [PubMed]
  6. Tamm, E.R.; Ethier, C.R.; Lasker, I.R.R.F. initiative on astrocytes and glaucomatous neurodegeneration participants. Biological aspects of axonal damage in glaucoma: A brief review. Exp. Eye Res. 2017, 157, 5–12. [Google Scholar] [CrossRef] [PubMed]
  7. Liu, B.; Kilpatrick, J.I.; Lukasz, B.; Jarvis, S.P.; McDonnell, F.; Wallace, D.M.; Clark, A.F.; O’Brien, C.J. Increased Substrate Stiffness Elicits a Myofibroblastic Phenotype in Human Lamina Cribrosa Cells. Investig. Ophthalmol. Vis. Sci. 2018, 59, 803–814. [Google Scholar] [CrossRef] [PubMed]
  8. Nickells, R.W. From ocular hypertension to ganglion cell death: A theoretical sequence of events leading to glaucoma. Can. J. Ophthalmol. 2007, 42, 278–287. [Google Scholar] [CrossRef]
  9. Hirt, J.; Porter, K.; Dixon, A.; McKinnon, S.; Liton, P.B. Contribution of autophagy to ocular hypertension and neurodegeneration in the DBA/2J spontaneous glaucoma mouse model. Cell Death Discov. 2018, 4, 14. [Google Scholar] [CrossRef]
  10. Crish, S.D.; Sappington, R.M.; Inman, D.M.; Horner, P.J.; Calkins, D.J. Distal axonopathy with structural persistence in glaucomatous neurodegeneration. Proc. Natl. Acad. Sci. USA 2010, 107, 5196–5201. [Google Scholar] [CrossRef]
  11. Rakic, P.; Riley, K.P. Overproduction and elimination of retinal axons in the fetal rhesus monkey. Science 1983, 219, 1441–1444. [Google Scholar] [CrossRef]
  12. Lu, L.J.; Tsai, J.C.; Liu, J. Novel Pharmacologic Candidates for Treatment of Primary Open-Angle Glaucoma. Yale J. Biol. Med. 2017, 90, 111–118. [Google Scholar]
  13. Catalani, E.; Brunetti, K.; Del Quondam, S.; Cervia, D. Targeting mitochondrial dysfunction and oxidative stress to prevent the neurodegeneration of retinal ganglion cells. Antioxidants 2023, 12, 2011. [Google Scholar] [CrossRef]
  14. Williams, P.A.; Harder, J.M.; Foxworth, N.E.; Cochran, K.E.; Philip, V.M.; Porciatti, V.; Smithies, O.; John, S.W. Vitamin B3 modulates mitochondrial vulnerability and prevents glaucoma in aged mice. Science 2017, 355, 756–760. [Google Scholar] [CrossRef] [PubMed]
  15. Chrysostomou, V.; Trounce, I.A.; Crowston, J.G. Mechanisms of retinal ganglion cell injury in aging and glaucoma. Ophthalmic Res. 2010, 44, 173–178. [Google Scholar] [CrossRef]
  16. Kong, G.Y.; Van Bergen, N.J.; Trounce, I.A.; Crowston, J.G. Mitochondrial dysfunction and glaucoma. J. Glaucoma 2009, 18, 93–100. [Google Scholar] [CrossRef] [PubMed]
  17. Sappington, R.M.; Sidorova, T.; Long, D.J.; Calkins, D.J. TRPV1: Contribution to retinal ganglion cell apoptosis and increased intracellular Ca2+ with exposure to hydrostatic pressure. Investig. Ophthalmol. Vis. Sci. 2009, 50, 717–728. [Google Scholar] [CrossRef] [PubMed]
  18. Munemasa, Y.; Kitaoka, Y.; Kuribayashi, J.; Ueno, S. Modulation of mitochondria in the axon and soma of retinal ganglion cells in a rat glaucoma model. J. Neurochem. 2010, 115, 1508–1519. [Google Scholar] [CrossRef]
  19. Lee, S.; Van Bergen, N.J.; Kong, G.Y.; Chrysostomou, V.; Waugh, H.S.; O’Neill, E.C.; Crowston, J.G.; Trounce, I.A. Mitochondrial dysfunction in glaucoma and emerging bioenergetic therapies. Exp. Eye Res. 2011, 93, 204–212. [Google Scholar] [CrossRef] [PubMed]
  20. Kamel, K.; Farrell, M.; O’Brien, C. Mitochondrial dysfunction in ocular disease: Focus on glaucoma. Mitochondrion 2017, 35, 44–53. [Google Scholar] [CrossRef]
  21. Nita, M.; Grzybowski, A. Smoking and Eye Pathologies. A systemic review. Part I. Anterior eye segment pathologies. Curr. Pharm. Des. 2017, 23, 629–638. [Google Scholar]
  22. Libby, R.T.; Anderson, M.G.; Pang, I.-H.; Robinson, Z.H.; Savinova, O.V.; Cosma, I.M.; Snow, A.; Wilson, L.A.; Smith, R.S.; Clar, A.F.; et al. Inherited glaucoma in DBA/2J mice: Pertinent disease features for studying the neurodegeneration. Vis. Neurosci. 2005, 22, 637–648. [Google Scholar] [CrossRef]
  23. Leadsham, J.E.; Sanders, G.; Giannaki, S.; Bastow, E.L.; Hutton, R.; Naeimi, W.R.; Breitenbach, M.; Gourlay, C.W. Loss of cytochrome c oxidase promotes RAS-dependent ROS production from the ER resident NADPH oxidase, Yno1p, in yeast. Cell Metab. 2013, 18, 279–286. [Google Scholar] [CrossRef]
  24. Murphy, R.K.; Ketzler, L.; Rice, R.D.; Johnson, S.M.; Doss, M.S.; Jaccoma, E.H. Oral glucosamine supplements as a possible ocular hypertensive agent. JAMA Ophthalmol. 2013, 131, 955–957. [Google Scholar] [CrossRef] [PubMed]
  25. Kaarniranta, K.; Uusitalo, H.; Blasiak, J.; Felszeghy, S.; Kannan, R.; Kauppinen, A.; Salminen, A.; Sinha, D.; Ferrington, D. Mechanisms of mitochondrial dysfunction and their impact on age-related macular degeneration. Prog. Retin. Eye Res. 2020, 79, 100858. [Google Scholar] [CrossRef] [PubMed]
  26. Miller, D.J.; Cascio, M.A.; Rosca, M.G. Diabetic Retinopathy: The role of mitochondria in the neural retina and microvascular disease. Antioxidants 2020, 9, 905. [Google Scholar] [CrossRef] [PubMed]
  27. Bhatia, S.; Rawal, R.; Sharma, P.; Singh, T.; Singh, M.; Singh, V. Mitochondrial dysfunction in Alzheimer’s disease: Opportunities for drug development. Curr. Neuropharmacol. 2022, 20, 675–692. [Google Scholar] [CrossRef]
  28. Henrich, M.T.; Oertel, W.H.; Surmeier, D.J.; Geibl, F.F. Mitochondrial dysfunction in Parkinson’s disease—A key disease hallmark with therapeutic potential. Mol. Neurodegener. 2023, 18, 83. [Google Scholar] [CrossRef]
  29. Zhang, Z.Q.; Xie, Z.; Chen, S.Y.; Zhang, X. Mitochondrial dysfunction in glaucomatous degeneration. Int. J. Ophthalmol. 2023, 16, 811–823. [Google Scholar] [CrossRef]
  30. Izzotti, A.; Sacca, S.C.; Longobardi, M.; Cartiglia, C. Sensitivity of ocular anterior chamber tissues to oxidative damage and its relevance to the pathogenesis of glaucoma. Investig. Ophthalmol. Vis. Sci. 2009, 50, 5251–5258. [Google Scholar] [CrossRef]
  31. Izzotti, A.; Sacca, S.C.; Longobardi, M.; Cartiglia, C. Mitochondrial damage in the trabecular meshwork of patients with glaucoma. Arch. Ophthalmol. 2010, 128, 724–730. [Google Scholar] [CrossRef] [PubMed]
  32. Sacca, S.C.; Pascotto, A.; Camicione, P.; Capris, P.; Izzotti, A. Oxidative DNA damage in the human trabecular meshwork: Clinical correlation in patients with primary open-angle glaucoma. Arch. Ophthalmol. 2005, 123, 458–463. [Google Scholar] [CrossRef] [PubMed]
  33. Fernandez-Durango, R.; Fernandez-Martinez, A.; Garcia-Feijoo, J.; Castillo, A.; de la Casa, J.M.; Garcia-Bueno, B.; Perez-Nievas, B.G.; Fernandez-Cruz, A.; Leza, J.C. Expression of nitrotyrosine and oxidative consequences in the trabecular meshwork of patients with primary open-angle glaucoma. Investig. Ophthalmol. Vis. Sci. 2008, 49, 2506–2511. [Google Scholar] [CrossRef] [PubMed]
  34. Muenster, S.; Lieb, W.S.; Fabry, G.; Allen, K.N.; Kamat, S.S.; Guy, A.H.; Dordea, A.C.; Teixeira, L.; Tainsh, R.E.; Yu, B.; et al. The ability of nitric oxide to lower intraocular pressure is dependent on guanylyl cyclase. Investig. Ophthalmol. Vis. Sci. 2017, 58, 4826–4835. [Google Scholar] [CrossRef] [PubMed]
  35. Ammar, D.A.; Hamweyah, K.M.; Kahook, M.Y. Antioxidants protect trabecular meshwork cells from hydrogen peroxide-induced cell death. Transl. Vis. Sci. Technol. 2012, 1, 4. [Google Scholar] [CrossRef] [PubMed]
  36. Sacca, S.C.; Izzotti, A.; Rossi, P.; Traverso, C. Glaucomatous outflow pathway and oxidative stress. Exp. Eye Res. 2007, 84, 389–399. [Google Scholar] [CrossRef] [PubMed]
  37. Luna, C.; Li, G.; Qiu, J.; Epstein, D.L.; Gonzalez, P. Role of miR-29b on the regulation of the extracellular matrix in human trabecular meshwork cells under chronic oxidative stress. Mol. Vis. 2009, 15, 2488–2497. [Google Scholar]
  38. Park, C.H.; Kim, J.W. Effect of advanced glycation end products on oxidative stress and senescence of trabecular meshwork cells. Korean J. Ophthalmol. 2012, 26, 123–131. [Google Scholar] [CrossRef] [PubMed]
  39. He, Y.; Ge, J.; Tombran-Tink, J. Mitochondrial defects and dysfunction in calcium regulation in glaucomatous trabecular meshwork cells. Investig. Ophthalmol. Vis. Sci. 2008, 49, 4912–4922. [Google Scholar] [CrossRef]
  40. He, Y.; Leung, K.W.; Zhang, Y.H.; Duan, S.; Zhong, X.F.; Jiang, R.Z.; Peng, Z.; Tombran-Tink, J.; Ge, J. Mitochondrial complex I defect induces ROS release and degeneration in trabecular meshwork cells of POAG patients: Protection by antioxidants. Investig. Ophthalmol. Vis. Sci. 2008, 49, 1447–1458. [Google Scholar] [CrossRef]
  41. McElnea, E.M.; Quill, B.; Docherty, N.G.; Irnaten, M.; Siah, W.F.; Clark, A.F.; O’Brien, C.J.; Wallace, D.M. Oxidative stress, mitochondrial dysfunction and calcium overload in human lamina cribrosa cells from glaucoma donors. Mol. Vis. 2011, 17, 1182–1191. [Google Scholar] [PubMed]
  42. Chidlow, G.; Wood, J.P.M.; Casson, R.J. Investigations into hypoxia and oxidative stress at the optic nerve head in a rat model of glaucoma. Front. Neurosci. 2017, 11, 478. [Google Scholar] [CrossRef] [PubMed]
  43. Tezel, G.; Yang, X.; Luo, C.; Peng, Y.; Sun, S.L.; Sun, D. Mechanisms of immune system activation in glaucoma: Oxidative stress-stimulated antigen presentation by the retina and optic nerve head glia. Investig. Ophthalmol. Vis. Sci. 2007, 48, 705–714. [Google Scholar] [CrossRef] [PubMed]
  44. Feilchenfeld, Z.; Yucel, Y.H.; Gupta, N. Oxidative injury to blood vessels and glia of the pre-laminar optic nerve head in human glaucoma. Exp. Eye Res. 2008, 87, 409–414. [Google Scholar] [CrossRef] [PubMed]
  45. Malone, P.E.; Hernandez, M.R. 4-Hydroxynonenal, a product of oxidative stress, leads to an antioxidant response in optic nerve head astrocytes. Exp. Eye Res. 2007, 84, 444–454. [Google Scholar] [CrossRef] [PubMed]
  46. Ju, W.K.; Kim, K.Y.; Noh, Y.H.; Hoshijima, M.; Lukas, T.J.; Ellisman, M.H.; Weinreb, R.N.; Perkins, G.A. Increased mitochondrial fission and volume density by blocking glutamate excitotoxicity protect glaucomatous optic nerve head astrocytes. Glia 2015, 63, 736–753. [Google Scholar] [CrossRef] [PubMed]
  47. Shim, M.S.; Kim, K.Y.; Bu, J.H.; Nam, H.S.; Jeong, S.W.; Park, T.L.; Ellisman, M.H.; Weinreb, R.N.; Ju, W.K. Elevated intracellular cAMP exacerbates vulnerability to oxidative stress in optic nerve head astrocytes. Cell Death Dis. 2018, 9, 285. [Google Scholar] [CrossRef] [PubMed]
  48. Tribble, J.R.; Vasalauskaite, A.; Redmond, T.; Young, R.D.; Hassan, S.; Fautsch, M.P.; Sengpiel, F.; Williams, P.A.; Morgan, J.E. Midget retinal ganglion cell dendritic and mitochondrial degeneration is an early feature of human glaucoma. Brain Commun. 2019, 1, fcz035. [Google Scholar] [CrossRef] [PubMed]
  49. Ishikawa, M.; Yoshitomi, T.; Zorumski, C.F.; Izumi, y. Experimentally induced mammalian models of glaucoma. Biomed. Res. Int. 2015, 2015, 281214. [Google Scholar] [CrossRef]
  50. Amato, R.; Cammalleri, M.; Melecchi, A.; Bagnoli, P.; Porciatti, V. Natural history of glaucoma progression in the DBA/2J model: Early contribution of müller cell gliosis. Cells 2023, 12, 1272. [Google Scholar] [CrossRef]
  51. Mahesh, N.; Maher, S.; Vittorio, P. IOP-dependent retinal ganglion cell dysfunction in glaucomatous DBA/2J mice. Investig. Ophthalmol. Vis. Sci. 2007, 48, 4573–4579. [Google Scholar]
  52. John, S.W.; Smith, R.S.; Savinova, O.V.; Hawes, N.L.; Chang, B.; Turnbull, D.; Davisson, M.; Roderick, T.H.; Heckenlively, J.R. Essential iris atrophy, pigment dispersion, and glaucoma in DBA/2J mice. Investig. Ophthalmol. Vis. Sci. 1998, 39, 951–962. [Google Scholar]
  53. Baltan, S.; Inman, D.M.; Danilov, C.A.; Morrison, R.S.; Calkins, D.J.; Horner, P.J. Metabolic vulnerability disposes retinal ganglion cell axons to dysfunction in a model of glaucomatous degeneration. J. Neurosci. 2010, 30, 5644–5652. [Google Scholar] [CrossRef]
  54. Wu, J.; Zhang, S.H.; Nickerson, J.M.; Gao, F.J.; Sun, Z.; Chen, X.Y.; Zhang, S.J.; Gao, F.; Chen, J.Y.; Luo, Y.; et al. Cumulative mtDNA damage and mutations contribute to the progressive loss of RGCs in a rat model of glaucoma. Neurobiol. Dis. 2015, 74, 167–179. [Google Scholar] [CrossRef]
  55. Inman, D.M.; Sappington, R.M.; Horner, P.J.; Calkins, D.J. Quantitative correlation of optic Nerve pathology with ocular pressure and corneal thickness in the DBA/2 mouse model of glaucoma. Investig. Ophthalmol. Vis. Sci. 2006, 47, 986–996. [Google Scholar] [CrossRef]
  56. Dengler-Crish, C.M.; Smith, M.A.; Inman, D.M.; Wilson, G.N.; Young, J.W.; Crish, S.D. Anterograde transport blockade precedes deficits in retrograde transport in the visual projection of the DBA/2J mouse model of glaucoma. Front. Neurosci. 2014, 8, 290. [Google Scholar] [CrossRef]
  57. Bayer, A.U.; Neuhardt, T.; May, A.C.; Martus, P.; Maag, K.P.; Brodie, S.; Lütjen-Drecoll, E.; Podos, S.M.; Mittag, T. Retinal morphology and ERG response in the DBA/2NNia mouse model of angle-closure glaucoma. Investig. Ophthalmol. Vis. Sci. 2001, 42, 1258–1265. [Google Scholar]
  58. Harazny, J.; Scholz, M.; Buder, T.; Lausen, B.; Kremers, J. Electrophysiological deficits in the retina of the DBA/2J mouse. Doc. Ophthalmol. 2009, 119, 181–197. [Google Scholar] [CrossRef]
  59. Cwerman-Thibault, H.; Lechauve, C.; Augustin, S.; Roussel, D.; Reboussin, É.; Mohammad, A.; Degardin-Chicaud, J.; Simonutti, M.; Liang, H.; Brignole-Baudouin, F.; et al. Neuroglobin can prevent or reverse glaucomatous progression in DBA/2J mice. Mol. Ther. Methods Clin. Dev. 2017, 5, 200–220. [Google Scholar] [CrossRef] [PubMed]
  60. Wax, M.B.; Tezel, G.; Yang, J.; Peng, G.; Patil, R.V.; Agarwal, N.; Sappington, R.M.; Calkins, D.J. Induced autoimmunity to heat shock proteins elicits glaucomatous loss of retinal ganglion cell neurons via activated T-cell-derived fas-ligand. J. Neurosci. 2008, 28, 12085–12096. [Google Scholar] [CrossRef] [PubMed]
  61. Bosco, A.; Steele, M.R.; Vetter, M.L. Early microglia activation in a mouse model of chronic glaucoma. J. Comp. Neurol. 2011, 519, 599–620. [Google Scholar] [CrossRef] [PubMed]
  62. Bosco, A.; Romero, C.O.; Breen, K.T.; Chagovetz, A.A.; Steele, M.R.; Ambati, B.K.; Vetter, M.L. Neurodegeneration severity can be predicted from early microglia alterations monitored in vivo in a mouse model of chronic glaucoma. Dis. Model. Mech. 2015, 8, 443–455. [Google Scholar] [CrossRef]
  63. Wilson, G.N.; Inman, D.M.; Dengler Crish, C.M.; Smith, M.A.; Crish, S.D. Early pro-inflammatory cytokine elevations in the DBA/2J mouse model of glaucoma. J. Neuroinflam. 2015, 12, 176. [Google Scholar] [CrossRef] [PubMed]
  64. Kamel, K.; O’Brien, C.J.; Zhdanov, A.V.; Papkovsky, D.B.; Clark, A.F.; Stamer, W.D.; Irnaten, M. Reduced Oxidative Phosphorylation and Increased Glycolysis in Human Glaucoma Lamina Cribrosa Cells. Investig. Ophthalmol. Vis. Sci. 2020, 61, 4. [Google Scholar] [CrossRef] [PubMed]
  65. Irnaten, M.; Zhdanov, A.; Brennan, D.; Crotty, T.; Clark, A.; Papkovsky, D.; O’Brien, C. Activation of the NFAT-calcium signaling pathway in human lamina cribrosa cells in glaucoma. Investig. Ophthalmol. Vis. Sci. 2018, 59, 831–842. [Google Scholar] [CrossRef] [PubMed]
  66. McElnea, E.M.; Hughes, E.; McGoldrick, A.; McCann, A.; Quill, B.; Docherty, N.; Irnaten, M.; Farrell, M.; Clark, A.F.; O’Brien, C.J.; et al. Lipofuscin accumulation and autophagy in glaucomatous human lamina cribrosa cells. BMC Ophthalmol. 2014, 14, 153. [Google Scholar] [CrossRef] [PubMed]
  67. Millington-Ward, S.; Chadderton, N.; Finnegan, L.K.; Post, I.J.M.; Carrigan, M.; Gardiner, T.; Peixoto, E.; Maloney, D.; Humphries, M.M.; Stitt, A.; et al. AAV-mediated gene therapy improving mitochondrial function provides benefit in age-related macular degeneration models. Clin. Transl. Med. 2022, 12, e952. [Google Scholar] [CrossRef] [PubMed]
  68. Millington-Ward, S.; Chadderton, N.; Finnegan, L.K.; Post, I.J.M.; Carrigan, M.; Nixon, R.; Humphries, M.M.; Humphries, P.; Kenna, P.F.; Palfi, A.; et al. RPE-directed gene therapy improves mitochondrial function in murine dry AMD models. Int. J. Mol. Sci. 2023, 24, 3847. [Google Scholar] [CrossRef] [PubMed]
  69. Chadderton, N.; Palfi, A.; Millington-Ward, S.; Gobbo, O.; Overlack, N.; Carrigan, M.; O’Reilly, M.; Campbell, M.; Ehrhardt, C.; Wolfrum, U.; et al. Intravitreal delivery of AAV-NDI1 provides functional benefit in a murine model of Leber hereditary optic neuropathy. Eur. J. Hum. Genet. 2013, 21, 62–68. [Google Scholar] [CrossRef]
  70. Chadderton, N.; Palfi, A.; Maloney, D.M.; Carrigan, M.; Finnegan, L.K.; Hanlon, K.S.; Shortall, C.; O’Reilly, M.; Humphries, P.; Cassidy, L.; et al. Optimisation of AAV-NDI1 significantly enhances its therapeutic value for correcting retinal mitochondrial dysfunction. Pharmaceutics 2023, 15, 322. [Google Scholar] [CrossRef]
  71. Palma, F.R.; Gantner, B.N.; Sakiyama, M.J.; Kayzuka, C.; Shukla, S.; Lacchini, R.; Cunniff, B.; Bonini, M.G. ROS production by mitochondria: Function or dysfunction? Oncogene 2024, 43, 295–303. [Google Scholar] [CrossRef] [PubMed]
  72. Spinazzi, M.; Casarin, A.; Pertegato, V.; Salviati, L.; Angelini, C. Assessment of mitochondrial respiratory chain enzymatic activities on tissues and cultured cells. Nat. Protoc. 2012, 7, 1235–1246. [Google Scholar] [CrossRef] [PubMed]
  73. Muthuswamy, A.; Chen, H.; Hu, Y.; Turner, O.C.; Aina, O.H. Mammalian Retinal Cell Quantification. Toxicol. Pathol. 2021, 49, 505–520. [Google Scholar] [CrossRef] [PubMed]
  74. Lo Faro, V.; Bhattacharya, A.; Zhou, W.; Zhou, D.; Wang, Y.; Läll, K.; Kanai, M.; Lopera-Maya, E.; Straub, P.; Pawar, P.; et al. Novel ancestry-specific primary open-angle glaucoma loci and shared biology with vascular mechanisms and cell proliferation. Cell Rep. Med. 2024, 5, 101430. [Google Scholar] [CrossRef] [PubMed]
  75. NEIGHBORHOOD Consortium; ANZRAG Consortium; Biobank Japan Project; FinnGen Study; UK Biobank Eye and Vision Consortium; GIGA Study Group; 23 and Me Research Team. Genome-wide meta-analysis identifies 127 open-angle glaucoma loci with consistent effect across ancestries. Nat. Commun. 2021, 12, 1258. [Google Scholar] [CrossRef] [PubMed]
  76. Yadav, M.; Bhardwaj, A.; Yadav, A.; Dada, R.; Tanwar, M. Molecular genetics of primary open-angle glaucoma. Indian. J. Ophthalmol. 2023, 71, 1739–1756. [Google Scholar] [CrossRef] [PubMed]
  77. Doucette, L.P.; Rasnitsyn, A.; Seifi, M.; Walter, M.A. The interactions of genes, age, and environment in glaucoma pathogenesis. Surv. Ophthalmol. 2015, 60, 310–326. [Google Scholar] [CrossRef] [PubMed]
  78. Sulak, R.; Liu, X.; Smedowski, A. The concept of gene therapy for glaucoma: The dream that has not come true yet. Neural Regen. Res. 2024, 19, 92–99. [Google Scholar] [CrossRef]
  79. Pietrucha-Dutczak, M.; Amadio, M.; Govoni, S.; Lewin-Kowalik, J.; Smedowski, A. The Role of Endogenous Neuroprotective Mechanisms in the Prevention of Retinal Ganglion Cells Degeneration. Front. Neurosci. 2018, 12, 834. [Google Scholar] [CrossRef]
  80. O’Callaghan, J.; Delaney, C.; O’Connor, M.; van Batenburg-Sherwood, J.; Schicht, M.; Lütjen-Drecoll, E.; Hudson, N.; Ni Dhubhghaill, S.; Humphries, P.; Stanley, C.; et al. Matrix metalloproteinase-3 (MMP-3)-mediated gene therapy for glaucoma. Sci. Adv. 2023, 9, eadf6537. [Google Scholar] [CrossRef]
  81. Zuo, L.; Khan, R.S.; Lee, V.; Dine, K.; Wu, W.; Shindler, K.S. SIRT1 promotes RGC survival and delays loss of function following optic nerve crush. Investig. Ophthalmol. Vis. Sci. 2013, 54, 5097–5102. [Google Scholar] [CrossRef]
  82. Ross, A.G.; McDougald, D.S.; Khan, R.S.; Duong, T.T.; Dine, K.E.; Aravand, P.; Bennett, J.; Chavali, V.R.M.; Shindler, K.S. Rescue of retinal ganglion cells in optic nerve injury using cell-selective AAV mediated delivery of SIRT1. Gene Ther. 2021, 28, 256–264. [Google Scholar] [CrossRef]
  83. Yue, J.; Khan, R.S.; Duong, T.T.; Dine, K.E.; Cui, Q.N.; O’Neill, N.; Aravand, P.; Liu, T.; Chaqour, B.; Shindler, K.S.; et al. Cell-specific expression of human SIRT1 by gene therapy reduces retinal ganglion cell loss induced by elevated intraocular pressure. Neurotherapeutics 2023, 20, 896–907. [Google Scholar] [CrossRef]
  84. McKinnon, S.J.; Lehman, D.M.; Tahzib, N.G.; Ransom, N.L.; Reitsamer, H.A.; Liston, P.; LaCasse, E.; Li, Q.; Korneluk, R.G.; Hauswirth, W.W. Baculoviral IAP repeat-containing-4 protects optic nerve axons in a rat glaucoma model. Mol. Ther. 2002, 5, 780–787. [Google Scholar] [CrossRef]
  85. Visuvanathan, S.; Baker, A.N.; Lagali, P.S.; Coupland, S.G.; Miller, G.; Hauswirth, W.W.; Tsilfidis, C. XIAP gene therapy effects on retinal ganglion cell structure and function in a mouse model of glaucoma. Gene Ther. 2022, 29, 147–156. [Google Scholar] [CrossRef] [PubMed]
  86. Xia, F.; Shi, S.; Palacios, E.; Liu, W.; Buscho, S.E.; Li, J.; Huang, S.; Vizzeri, G.; Dong, X.C.; Motamedi, M.; et al. Sirt6 protects retinal ganglion cells and optic nerve from degeneration during aging and glaucoma. Mol. Ther. 2024, 32, 1760–1778. [Google Scholar] [CrossRef]
  87. Thananthirige, K.P.M.; Chitranshi, N.; Basavarajappa, D.; Rajput, R.; Abbasi, M.; Palanivel, V.; Gupta, V.B.; Paulo, J.A.; Koronyo-Hamaoui, M.; Mirzaei, M.; et al. Tau modulation through AAV9 therapy augments Akt/Erk survival signalling in glaucoma mitigating the retinal degenerative phenotype. Acta Neuropathol. Commun. 2024, 12, 89. [Google Scholar] [CrossRef]
  88. Hui, F.; Tang, J.; Williams, P.A.; McGuinness, M.B.; Hadoux, X.; Casson, R.J.; Coote, M.; Trounce, I.A.; Martin, K.R.; van Wijngaarden, P.; et al. Improvement in inner retinal function in glaucoma with nicotinamide (vitamin B3) supplementation: A crossover randomized clinical trial. Clin. Exp. Ophthalmol. 2020, 48, 903–914. [Google Scholar] [CrossRef] [PubMed]
  89. Leung, C.K.S.; Ren, S.T.; Chan, P.P.M.; Wan, K.H.N.; Kam, A.K.W.; Lai, G.W.K.; Chiu, V.S.M.; Ko, M.W.L.; You, C.K.F.; Yu, M.C.Y. Nicotinamide riboside as a neuroprotective therapy for glaucoma: Study protocol for a randomized, double-blind, placebo-control trial. Trials 2022, 23, 45. [Google Scholar] [CrossRef] [PubMed]
  90. De Moraes, C.G.; John, S.W.M.; Williams, P.A.; Blumberg, D.M.; Cioffi, G.A.; Liebmann, J.M. Nicotinamide and pyruvate for neuroenhancement in open-angle glaucoma: A phase 2 randomized clinical trial. JAMA Ophthalmol. 2022, 140, 11–18. [Google Scholar] [CrossRef]
  91. Garg Shukla, A.; Cioffi, G.A.; Liebmann, J.M. Drug-induced liver injury during a glaucoma neuroprotection clinical trial. J. Glaucoma. 2024, 33, e58–e59. [Google Scholar] [CrossRef] [PubMed]
  92. Sanz-Morello, B.; Ahmadi, H.; Vohra, R.; Saruhanian, S.; Freude, K.K.; Hamann, S.; Kolko, M. Oxidative stress in optic neuropathies. Antioxidants 2021, 10, 1538. [Google Scholar] [CrossRef]
  93. Mirra, S.; Marfany, G. mitochondrial gymnastics in retinal cells: A resilience mechanism against oxidative stress and neurodegeneration. Adv. Exp. Med. Biol. 2019, 1185, 513–517. [Google Scholar] [PubMed]
  94. Burgoyne, C.F. The non-human primate experimental glaucoma model. Exp. Eye Res. 2015, 141, 57–73. [Google Scholar] [CrossRef] [PubMed]
  95. Sun, D.; Wang, B.; Yang, Z.; Zhan, Z.; Li, J.; Lan, Y. Protocol for laser-induced chronic ocular hypertension and intracameral injection in nonhuman primates. STAR Protoc. 2022, 3, 101801. [Google Scholar] [CrossRef]
  96. Zhou, X.; Li, F.; Kong, L.; Tomita, H.; Li, C.; Cao, W. Involvement of inflammation, degradation, and apoptosis in a mouse model of glaucoma. J. Biol. Chem. 2005, 280, 31240–31248. [Google Scholar] [CrossRef] [PubMed]
  97. Edwards, G.; Perkins, G.A.; Kim, K.Y.; Kong, Y.; Lee, Y.; Choi, S.H.; Liu, Y.; Skowronska-Krawczyk, D.; Weinreb, R.N.; Zangwill, L.; et al. Loss of AKAP1 triggers Drp1 dephosphorylation-mediated mitochondrial fission and loss in retinal ganglion cells. Cell Death Dis. 2020, 11, 254. [Google Scholar] [CrossRef]
  98. Choi, S.H.; Kim, K.Y.; Perkins, G.A.; Phan, S.; Edwards, G.; Xia, Y.N.; Kim, J.; Skowronska-Krawczyk, D.; Weinreb, R.N.; Ellisman, M.H.; et al. AIBP protects retinal ganglion cells against neuroinflammation and mitochondrial dysfunction in glaucomatous neurodegeneration. Redox Biol. 2020, 37, 101703. [Google Scholar] [CrossRef] [PubMed]
  99. Jassim, A.H.; Inman, D.M.; Mitchell, C.H. Crosstalk between dysfunctional mitochondria and inflammation in glaucomatous neurodegeneration. Front. Pharmacol. 2021, 12, 699623. [Google Scholar] [CrossRef]
  100. Johnson, T.V.; Tomarev, S.I. Rodent models of glaucoma. Brain Res. Bull. 2010, 81, 349–358. [Google Scholar] [CrossRef]
  101. Kimura, A.; Noro, T.; Harada, T. Role of animal models in glaucoma research. Neural Regen. Res. 2020, 15, 1257–1258. [Google Scholar] [CrossRef]
  102. Yu, A.L.; Fuchshofer, R.; Kampik, A.; Welge-Lüssen, U. Effects of oxidative stress in trabecular meshwork cells are reduced by prostaglandin analogues. Investig. Ophthalmol. Vis. Sci. 2008, 49, 4872–4880. [Google Scholar] [CrossRef] [PubMed]
  103. Yu, A.L.; Moriniere, J.; Welge-Lussen, U. TGF-β2- and H2O2-induced biological changes in optic nerve head astrocytes are reduced by the antioxidant alpha-lipoic acid. Ophthalmic Res. 2012, 48, 156–164. [Google Scholar] [CrossRef] [PubMed]
  104. Wallace, D.M.; Clark, A.F.; Lipson, K.E.; Andrews, D.; Crean, J.K.; O’Brien, C.J. Anti-connective tissue growth factor antibody treatment reduces extracellular matrix production in trabecular meshwork and lamina cribrosa cells. Investig. Ophthalmol. Vis. Sci. 2013, 54, 7836–7848. [Google Scholar] [CrossRef] [PubMed]
  105. Tektas, O.Y.; Lutjen-Drecoll, E. Structural changes of the trabecular meshwork in different kinds of glaucoma. Exp. Eye Res. 2009, 88, 769–775. [Google Scholar] [CrossRef] [PubMed]
  106. Browne, J.G.; Ho, S.L.; Kane, R. Connective tissue growth factor is increased in pseudoexfoliation glaucoma. Investig. Ophthalmol. Vis. Sci. 2011, 52, 3660–3666. [Google Scholar] [CrossRef] [PubMed]
  107. Millington-Ward, S.; Chadderton, N.; Berkeley, M.; Finnegan, L.K.; Hanlon, K.S.; Carrigan, M.; Humphries, P.; Kenna, P.F.; Palfi, A.; Farrar, G.J. Novel 199 base pair NEFH promoter drives expression in retinal ganglion cells. Sci. Rep. 2020, 10, 16515. [Google Scholar] [CrossRef]
  108. Leroy, B.; Fischer, M.D.; Flannery, J.G.; MacLaren, R.E.; Dalkara, D.; Scholl, H.P.N.; Chung, D.C.; Spera, C.; Viriato, D.; Banhazi, J. Gene therapy for inherited retinal disease: Long-term durability of effect. Ophthalmic Res. 2023, 66, 179–196. [Google Scholar] [CrossRef]
  109. Palfi, A.; Yesmambetov, A.; Millington-Ward, S.; Shortall, C.; Humphries, P.; Kenna, P.F.; Chadderton, N.; Farrar, G.J. AAV-delivered Tulp1 supplementation therapy targeting photoreceptors provides minimal benefit in Tulp1-/- retinas. Front. Neurosci. 2020, 14, 891. [Google Scholar] [CrossRef]
  110. O’Reilly, M.; Palfi, A.; Chadderton, N.; Millington-Ward, S.; Ader, M.; Cronin, T.; Tuohy, T.; Auricchio, A.; Hildinger, M.; Tivnan, A.; et al. RNA interference-mediated suppression and replacement of human rhodopsin in vivo. Am. J. Hum. Genet. 2007, 81, 127–135. [Google Scholar] [CrossRef]
  111. Rohr, U.P.; Wulf, M.A.; Stahn, S.; Steidl, U.; Haas, R.; Kronenwett, R. Fast and reliable titration of recombinant adeno-associated virus type-2 using quantitative real-time PCR. J. Virol. Methods 2002, 106, 81–88. [Google Scholar] [CrossRef] [PubMed]
  112. Lopez, N.N.; Clark, A.F.; Tovar-Vidales, T. Isolation and characterization of human optic nerve head astrocytes and lamina cribrosa cells. Exp. Eye Res. 2020, 197, 108103. [Google Scholar] [CrossRef] [PubMed]
  113. Irnaten, M.; Barry, R.C.; Wallace, D.M.; Docherty, N.G.; Quill, B.; Clark, A.F.; O’Brien, C.J. Elevated maxi-K+ ion channel current in glaucomatous lamina cribrosa cells. Exp. Eye Res. 2013, 115, 224–229. [Google Scholar] [CrossRef] [PubMed]
  114. Lambert, W.; Agarwal, R.; Howe, W.; Clark, A.F.; Wordinger, R.J. Neurotrophin and neurotrophin receptor expression by cells of the human lamina cribrosa. Investig Ophthalmol. Vis. Sci. 2001, 42, 2315–2323. [Google Scholar]
  115. Seo, B.B.; Kitajima-Ihara, T.; Chan, E.K.; Scheffler, I.E.; Matsuno-Yagi, A.; Yagi, T. Molecular remedy of complex I defects: Rotenone-insensitive internal NADH-quinone oxidoreductase of Saccharomyces cerevisiae mitochondria restores the NADH oxidase activity of complex I-deficient mammalian cells. Proc. Natl. Acad. Sci. USA 1998, 95, 9167–9171. [Google Scholar] [CrossRef]
  116. Finnegan, L.K.; Chadderton, N.; Kenna, P.F.; Palfi, A.; Carty, M.; Bowie, A.G.; Millington-Ward, S.; Farrar, G.J. SARM1 ablation is protective and preserves spatial vision in an in vivo mouse model of retinal ganglion cell degeneration. Int. J. Mol. Sci. 2022, 23, 1606. [Google Scholar] [CrossRef]
Ijms 25 08876 g001
Figure 1. AAV-eNdi1 protects pLC cells from H2O2-insult. (A,B) 3 × 104 pLC cells were seeded into XFe96 Seahorse plates. The following day, cells were transduced with AAV-eNdi1 (MOI = 8 × 103). 48 h post-transduction, transduced (n = 4–5 wells), and untransduced pLC cells (n > 10 wells) were insulted with 750 μM H2O2 for 1 h and subsequently underwent a mitochondrial stress test. The mitochondrial stress test was also performed on pLC cells that had not been insulted (n > 10 wells). Notably, H2O2 insult significantly reduced basal and maximal oxygen consumption rates (OCRs) and ATP production compared to control pLC cells. However, basal and maximal OCRs and ATP production were rescued in AAV-eNdi1-treated cells that received the insult. Statistics were performed on 7–8 replicate mitochondrial stress test assays. (C) 4 × 104 pLC cells were seeded in 48-well plates. The following day, cells were transduced with AAV-eNdi1 (n = 6, MOI = 2.5 × 103). 24 h post-seeding transduced cells and an additional n = 6 wells with untransduced pLC cells were insulted with 750 μM H2O2 for 30 min, after which a ROS (CellROX) assay was performed. Control pLC cells were also assayed (n = 8). The Y-axis represents the median CellROX fluorescence, a marker for ROS, and the levels relative to control pLC cells. (D–K) 2 × 106 pLC cells were transfected with 2 mg eNdi1 plasmid (C,D,G,H) or a control plasmid (AAV-MCS; E,F,I,J). Cells were insulted 48 h post-transfection with 750 μM H2O2 for 1 h, fixed, and stained with Phalloidin-iFluor 647 (F-actin, light blue), anti-CPN60 (mitochondrial stress marker, red) antibody, and DAPI (nuclear stain, dark blue). eNdi1-treated and H2O2-insulted cells (F,I; n = 6) were compared to plasmid AAV-MSC-treated (vehicle control) and H2O2-insulted cells (E,H; n = 6) and control pLC cells that had not been insulted (D,G; n = 5). (J) The relative number of CPN60-positive cells with elevated fluorescence intensity was determined. (K) Cell nuclei/mm2 with high DAPI fluorescence intensity indicating dense nuclei (dark blue, pink, and green) and all cell nuclei/mm2 with DAPI fluorescence (pale blue, pink, and green) were quantified. Scale bars: 50 μm (F) and 100 μm (I). * p < 0.05; ** p < 0.01; *** p < 0.001; **** p < 0.0001 (ANOVA). Error bars represent SD values. In (K), ** refers to the difference between the numbers of dense nuclei.
Figure 1. AAV-eNdi1 protects pLC cells from H2O2-insult. (A,B) 3 × 104 pLC cells were seeded into XFe96 Seahorse plates. The following day, cells were transduced with AAV-eNdi1 (MOI = 8 × 103). 48 h post-transduction, transduced (n = 4–5 wells), and untransduced pLC cells (n > 10 wells) were insulted with 750 μM H2O2 for 1 h and subsequently underwent a mitochondrial stress test. The mitochondrial stress test was also performed on pLC cells that had not been insulted (n > 10 wells). Notably, H2O2 insult significantly reduced basal and maximal oxygen consumption rates (OCRs) and ATP production compared to control pLC cells. However, basal and maximal OCRs and ATP production were rescued in AAV-eNdi1-treated cells that received the insult. Statistics were performed on 7–8 replicate mitochondrial stress test assays. (C) 4 × 104 pLC cells were seeded in 48-well plates. The following day, cells were transduced with AAV-eNdi1 (n = 6, MOI = 2.5 × 103). 24 h post-seeding transduced cells and an additional n = 6 wells with untransduced pLC cells were insulted with 750 μM H2O2 for 30 min, after which a ROS (CellROX) assay was performed. Control pLC cells were also assayed (n = 8). The Y-axis represents the median CellROX fluorescence, a marker for ROS, and the levels relative to control pLC cells. (D–K) 2 × 106 pLC cells were transfected with 2 mg eNdi1 plasmid (C,D,G,H) or a control plasmid (AAV-MCS; E,F,I,J). Cells were insulted 48 h post-transfection with 750 μM H2O2 for 1 h, fixed, and stained with Phalloidin-iFluor 647 (F-actin, light blue), anti-CPN60 (mitochondrial stress marker, red) antibody, and DAPI (nuclear stain, dark blue). eNdi1-treated and H2O2-insulted cells (F,I; n = 6) were compared to plasmid AAV-MSC-treated (vehicle control) and H2O2-insulted cells (E,H; n = 6) and control pLC cells that had not been insulted (D,G; n = 5). (J) The relative number of CPN60-positive cells with elevated fluorescence intensity was determined. (K) Cell nuclei/mm2 with high DAPI fluorescence intensity indicating dense nuclei (dark blue, pink, and green) and all cell nuclei/mm2 with DAPI fluorescence (pale blue, pink, and green) were quantified. Scale bars: 50 μm (F) and 100 μm (I). * p < 0.05; ** p < 0.01; *** p < 0.001; **** p < 0.0001 (ANOVA). Error bars represent SD values. In (K), ** refers to the difference between the numbers of dense nuclei.
Ijms 25 08876 g001
Ijms 25 08876 g002
Figure 2. AAV-eNdi1 rescues mitochondrial function in glaucomatous human lamina cribrosa (LC) cells. 1.5 × 104 human glaucomatous and control primary LC cells were seeded into XFe96 Seahorse plates. The following day, >5 wells were transduced with AAV-eNdi1 (MOI = 8 × 105). (A) 48 h post-transduction, transduced glaucomatous cells (n > 5 wells), untransduced control (n > 10 wells), and glaucomatous patient cells (n > 10 wells) underwent a mitochondrial stress test. (B) Basal and maximal oxygen consumption rates (OCRs) and ATP production were significantly increased in treated glaucomatous cells. Notably, statistics were performed on eight replicate mitochondrial stress test assays performed on a single patient and a control LC line. * p < 0.05, ** p < 0.01 *** p < 0.001. Control and glaucomatous LC cells were compared using paired t-tests. The parameters of treated and untreated glaucomatous and control cells were compared using ANOVA with Šídák’s multiple comparison test. Error bars represent SD values.
Figure 2. AAV-eNdi1 rescues mitochondrial function in glaucomatous human lamina cribrosa (LC) cells. 1.5 × 104 human glaucomatous and control primary LC cells were seeded into XFe96 Seahorse plates. The following day, >5 wells were transduced with AAV-eNdi1 (MOI = 8 × 105). (A) 48 h post-transduction, transduced glaucomatous cells (n > 5 wells), untransduced control (n > 10 wells), and glaucomatous patient cells (n > 10 wells) underwent a mitochondrial stress test. (B) Basal and maximal oxygen consumption rates (OCRs) and ATP production were significantly increased in treated glaucomatous cells. Notably, statistics were performed on eight replicate mitochondrial stress test assays performed on a single patient and a control LC line. * p < 0.05, ** p < 0.01 *** p < 0.001. Control and glaucomatous LC cells were compared using paired t-tests. The parameters of treated and untreated glaucomatous and control cells were compared using ANOVA with Šídák’s multiple comparison test. Error bars represent SD values.
Ijms 25 08876 g002
Ijms 25 08876 g003
Figure 3. Pigmentary dispersal and quantification of retinal ganglion cells in the DBA/2J eye. Eyes from two- and twelve-month-old (2 m and 12 m) DBA/2J and C57BL/6J (wt) mice were enucleated and fixed in 4% paraformaldehyde. The eyes were dissected at the ora serrata, and the lens and retina were removed. Aberrant pigmentary dispersal in the whole eye (A,F), iris (B,G), and RPE (C,H) of DBA/2J versus C57BL/6J (wt) mouse eyes was observed at 12 m. Retina wholemounts from 2 m and 12 m mice were stained with an anti-BRN3A primary antibody (detected with a Cy3-conjugated secondary antibody). The wholemounts were analysed via fluorescence microscopy, and RGC numbers were automatically quantified (n = 9–14; K). No significant difference was found between 2 m C57BL/6J (D,K; n = 9), 12 m C57BL/6J (E,K; n = 14), and 2 m DBA/2J (I,K; n = 14) mice. However, 12 m DBA/2J mice (J,K; n = 7) had significantly fewer RGCs. Scale bars: 2 mm (H) and 0.5 mm (J). **** p < 0.0001. RGC numbers were compared using ANOVA with Šídák’s multiple comparisons test. Error bars represent SD values.
Figure 3. Pigmentary dispersal and quantification of retinal ganglion cells in the DBA/2J eye. Eyes from two- and twelve-month-old (2 m and 12 m) DBA/2J and C57BL/6J (wt) mice were enucleated and fixed in 4% paraformaldehyde. The eyes were dissected at the ora serrata, and the lens and retina were removed. Aberrant pigmentary dispersal in the whole eye (A,F), iris (B,G), and RPE (C,H) of DBA/2J versus C57BL/6J (wt) mouse eyes was observed at 12 m. Retina wholemounts from 2 m and 12 m mice were stained with an anti-BRN3A primary antibody (detected with a Cy3-conjugated secondary antibody). The wholemounts were analysed via fluorescence microscopy, and RGC numbers were automatically quantified (n = 9–14; K). No significant difference was found between 2 m C57BL/6J (D,K; n = 9), 12 m C57BL/6J (E,K; n = 14), and 2 m DBA/2J (I,K; n = 14) mice. However, 12 m DBA/2J mice (J,K; n = 7) had significantly fewer RGCs. Scale bars: 2 mm (H) and 0.5 mm (J). **** p < 0.0001. RGC numbers were compared using ANOVA with Šídák’s multiple comparisons test. Error bars represent SD values.
Ijms 25 08876 g003
Ijms 25 08876 g004
Figure 4. AAV-eNdi1 preserves visual function and RGC number and increases NADH oxidation rates in DBA/2J mice. (A,B) Photopic single-flash cone (SFC) responses. To establish the functional effects of AAV-eNdi1 in vivo, 2-month-old DBA/2J mice were intravitreally injected with 4.1 × 107 vg AAV-eNdi1 in one eye (green), while the contralateral eye received an equal volume of vehicle control (blue). Ten months post-treatment, the amplitude of the photonegative response (PhNR; indicated between the two horizontal dotted lines) of photopic single-flash cone (SFC) responses were measured, and readings from untreated control eyes (A) compared to treated contralateral eyes (B). The latency of the b-wave (ms), indicated by the vertical dotted line, was also determined. The SDs of the SFC responses are represented in pale blue. (C) The bar chart represents individual PhNR amplitudes established per eye (n = 28) and PhNR b-wave latency (D), and wild-type C57BL/6J values (turquoise) are also provided. (C,D) Eyes were subsequently enucleated and fixed in 4% pfa, and wholemounts prepared (n = 37). (E,F) Wholemount retinas were stained with BRN3A immunocytochemistry. (G) Retinal ganglion cells (RGCs) were automatically quantified. (H) NADH oxidation rate assay was performed on retinas (n = 7) and optic nerves (n = 4 per group, each sample comprising four pooled optic nerves). Scale bar (F): 500 µm. * p < 0.05, ** p < 0.01, Student’s paired t-test except for comparisons between C57BL/6J and DBA/2J data (C,D), where Student’s t-tests were used. Error bars represent SD values.
Figure 4. AAV-eNdi1 preserves visual function and RGC number and increases NADH oxidation rates in DBA/2J mice. (A,B) Photopic single-flash cone (SFC) responses. To establish the functional effects of AAV-eNdi1 in vivo, 2-month-old DBA/2J mice were intravitreally injected with 4.1 × 107 vg AAV-eNdi1 in one eye (green), while the contralateral eye received an equal volume of vehicle control (blue). Ten months post-treatment, the amplitude of the photonegative response (PhNR; indicated between the two horizontal dotted lines) of photopic single-flash cone (SFC) responses were measured, and readings from untreated control eyes (A) compared to treated contralateral eyes (B). The latency of the b-wave (ms), indicated by the vertical dotted line, was also determined. The SDs of the SFC responses are represented in pale blue. (C) The bar chart represents individual PhNR amplitudes established per eye (n = 28) and PhNR b-wave latency (D), and wild-type C57BL/6J values (turquoise) are also provided. (C,D) Eyes were subsequently enucleated and fixed in 4% pfa, and wholemounts prepared (n = 37). (E,F) Wholemount retinas were stained with BRN3A immunocytochemistry. (G) Retinal ganglion cells (RGCs) were automatically quantified. (H) NADH oxidation rate assay was performed on retinas (n = 7) and optic nerves (n = 4 per group, each sample comprising four pooled optic nerves). Scale bar (F): 500 µm. * p < 0.05, ** p < 0.01, Student’s paired t-test except for comparisons between C57BL/6J and DBA/2J data (C,D), where Student’s t-tests were used. Error bars represent SD values.
Ijms 25 08876 g004
Ijms 25 08876 g005
Figure 5. (A,B) Diagrammatic representation of AAV-eNdi1. Inverted terminal repeats (ITRs), CAG (A) and CMV (B) promoters, eNdi1, and minimal PolyAs are indicated with the sizes provided.
Figure 5. (A,B) Diagrammatic representation of AAV-eNdi1. Inverted terminal repeats (ITRs), CAG (A) and CMV (B) promoters, eNdi1, and minimal PolyAs are indicated with the sizes provided.
Ijms 25 08876 g005
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Millington-Ward, S.; Palfi, A.; Shortall, C.; Finnegan, L.K.; Bargroff, E.; Post, I.J.M.; Maguire, J.; Irnaten, M.; O′Brien, C.; Kenna, P.F.; et al. AAV-NDI1 Therapy Provides Significant Benefit to Murine and Cellular Models of Glaucoma. Int. J. Mol. Sci. 2024, 25, 8876. https://doi.org/10.3390/ijms25168876

AMA Style

Millington-Ward S, Palfi A, Shortall C, Finnegan LK, Bargroff E, Post IJM, Maguire J, Irnaten M, O′Brien C, Kenna PF, et al. AAV-NDI1 Therapy Provides Significant Benefit to Murine and Cellular Models of Glaucoma. International Journal of Molecular Sciences. 2024; 25(16):8876. https://doi.org/10.3390/ijms25168876

Chicago/Turabian Style

Millington-Ward, Sophia, Arpad Palfi, Ciara Shortall, Laura K. Finnegan, Ethan Bargroff, Iris J. M. Post, John Maguire, Mustapha Irnaten, Colm O′Brien, Paul F. Kenna, and et al. 2024. "AAV-NDI1 Therapy Provides Significant Benefit to Murine and Cellular Models of Glaucoma" International Journal of Molecular Sciences 25, no. 16: 8876. https://doi.org/10.3390/ijms25168876

APA Style

Millington-Ward, S., Palfi, A., Shortall, C., Finnegan, L. K., Bargroff, E., Post, I. J. M., Maguire, J., Irnaten, M., O′Brien, C., Kenna, P. F., Chadderton, N., & Farrar, G. J. (2024). AAV-NDI1 Therapy Provides Significant Benefit to Murine and Cellular Models of Glaucoma. International Journal of Molecular Sciences, 25(16), 8876. https://doi.org/10.3390/ijms25168876

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop