Search Results (43)

This review summarizes innovative co-formulation strategies for non-marketed dry powder inhalers (DPIs), enabling the simultaneous pulmonary delivery of multiple active pharmaceutical ingredients (APIs). Key approaches include co-amorphous systems (COAMS) and co-crystals, which combine two APIs into a single particle, improving aerodynamic properties, solubility, dissolution, and patient compliance while reducing manufacturing complexity. Core–shell microparticles, produced via spray drying, allow spatial separation and controlled release of APIs, minimizing drug–drug interactions and enabling tailored pharmacokinetics. Co-spray drying of dual APIs can yield particles with superior aerosolization and stability, though examples remain limited. Nanoparticle-based systems offer enhanced lung deposition and cellular uptake but face challenges in device compatibility, scalability, and regulatory approval. Each technology presents unique advantages and limitations regarding manufacturability, dose flexibility, and clinical translation. This review also highlights advances in in vitro toxicity testing, including air–liquid interface cultures, organoids, lung-on-chip models, and precision-cut lung slices, which are increasingly important as alternatives to animal studies. The importance of using an aerosol exposure system for the testing is highlighted. Ultimately, the choice of co-formulation platform should balance scientific innovation with practical considerations of manufacturing and regulatory requirements to maximize therapeutic benefit and commercial viability for future DPI combination products. Full article

Background: The multifactorial pathogenesis of bronchopulmonary dysplasia (BPD) includes prematurity, inflammation, and oxidative stress. Photobiomodulation therapy (PBMT) using near-infrared (NIR) laser sources was found to have anti-inflammatory effects in several respiratory disorders. Our aim was to evaluate whether PBMT could reduce inflammation in an in vitro model of BPD. Materials and Methods: Precision-cut lung slices (PCLSs) from premature rabbits were exposed to lipopolysaccharide (LPS) and treated with three PBMT protocols (A, B, and C) differing for the treatment parameter such as fluence (energy delivered per unit area, laser A: 7.09, laser B: 7.41, laser C: 7.01 J/cm²) and exposure time (25, 20, 12 s, respectively). The expression level of TNFα and IL-6 was measured by reverse transcription quantitative polymerase chain reaction (RT-qPCR) after 2 or 6 h from PBMT. Results: PBMT protocols A and B reduced IL-6 and TNFα mRNA at both timepoints, although the effect was less pronounced after 6 h than after 2 h. Furthermore, protocol A, which involved intermediate fluence and longer laser exposure, was more effective than protocol B. Conclusions: PBMT with NIR laser sources has an effective anti-inflammatory effect in an in vitro model of BPD, such as PCLSs from premature rabbits pretreated with LPS. These encouraging results support the planning of further studies in animal models of BPD and help identify the most effective PBMT protocol to use. Full article

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract disease in young children, yet determinants of disease severity in otherwise healthy infants remain poorly understood. RSV disease severity has been linked to temporal differences in airway epithelial type I/III IFN and inflammatory responses, with defective viral genomes (DVGs) acting as potent inducers of type I/III IFNs. Additionally, an increased abundance of nontypeable Haemophilus influenzae (NTHi) is associated with more severe RSV disease, although the mechanisms underlying this association and the impacts of NTHi on DVG replication and DVG-driven host responses remain unclear. To address this knowledge gap, we modeled a clinically relevant but underexplored scenario of simultaneous transmission by performing concurrent RSV–NTHi co-infection experiments. Co-infection reduced titers of RSV but not of NTHi. Mechanistically, extracellular NTHi inhibited RSV particle binding to host cells. Using A549 cells and human precision-cut lung slices, we found that NTHi alone was a weak inducer of type I/III IFNs but a strong inducer of pro-inflammatory cytokines. Accordingly, RSV–NTHi co-infection suppressed DVG replication and DVG-driven IFN responses while enhancing inflammatory signaling, potentially driven by increased cell-associated NTHi. Together, these findings provide a mechanistic basis for how NTHi exacerbates RSV disease severity through dysregulated host immune responses rather than increased viral burden. Full article

Influenza A virus remains a major global health threat, causing annual epidemics and occasional pandemics. Programmed cell death, including apoptosis, pyroptosis, and necroptosis, with emerging evidence for ferroptosis, plays a dual role in influenza pathogenesis, both limiting viral replication and contributing to immunopathology. Most mechanistic insights have been derived from murine genetic models, which have been invaluable for establishing causal roles of these pathways. However, murine models and cancer-derived cell lines differ significantly from human physiology. This review systematically compares influenza-induced programmed cell death across human-relevant platforms, including primary cells, immortalized non-cancerous lines, co-cultures, organoids, and precision-cut lung slices. The increasing complexity of these models reveals distinct aspects of pathway activation, bystander effects, cell-type vulnerability, and spatial dynamics. We highlight critical divergences between model systems, identify gaps in comparative analyses across viral strains and experimental platforms, and outline future directions leveraging advanced model systems, multi-omics, and functional genomics to enhance translational relevance and guide the development of host-directed therapies. Full article

Aspergillus fumigatus is an opportunistic filamentous fungus that primarily affects the respiratory tract of the human body. Depending on its host’s immune response, the pathogen can cause invasive pulmonary aspergillosis (IPA). Biofilm formation by A. fumigatus increases virulence and resistance against antifungals and immune response and is one important factor in IPA development. Here, two human-like models, precision cut lung slices (PCLS) and a biofilm co-culture model, have been developed to test the anti-biofilm activity of voriconazole, amphotericin B, as well as luliconazole against A. fumigatus. In both assays, metabolically active A. fumigatus biofilms were examined at different biofilm developmental stages using an XTT assay. A decrease in the metabolic activity of the fungal biofilms was detected for each of the tested agents in both assays. Significant anti-biofilm effects exist against early-stage biofilm in the co-culture model. In the PCLS assay, amphotericin B showed the strongest inhibition after 24 h. In conclusion, the applied PCLS ex vivo model can be used to study the property and activity of certain antifungal compounds against Aspergillus biofilm. With its close resemblance to human conditions, the PCLS model has the potential for improving the current understanding of biofilm treatments in laboratory settings. Full article

Background/Objectives: Pulmonary hypertension is a progressive disease leading to right heart failure. One treatment strategy is to induce vasodilation via the nitric oxide–soluble guanylate cyclase–cyclic guanosine monophosphate (NO–sGC–cGMP) signaling pathway. There are currently two soluble guanylate cyclase stimulators on the market: Riociguat and vericiguat, with vericiguat having a longer half-life and needing to be taken only once a day. This study investigated whether the pharmacological differences between the drugs affect pulmonary vessels and airways. Methods: The effects of vericiguat and riociguat on pulmonary arteries, veins, and airways were studied using rat precision-cut lung slices (PCLS). Vessels were pretreated with endothelin-1 and airways with serotonin. In isolated perfused lungs (IPL), the effects of sGC stimulation on pulmonary artery pressure (PAP), airway resistance, inflammatory cytokine, and chemokine release were quantified. Results: Riociguat and vericiguat caused pulmonary artery dilation in PCLS. During IPL, riociguat was more effective than vericiguat in reducing PAP with a statistically significant reduction of 10%. Both drugs were potent bronchodilators in preconstricted airways (p < 0.001). Only vericiguat reduced airway resistance during IPL, as shown here for the first time. Both drugs significantly reduced IL-6 and IL-1ß levels, while riociguat also reduced VEGF-A and KC-GRO levels. Conclusions: Riociguat and vericiguat had three main effects in the two rat ex-vivo models: They dilated the pulmonary arteries, induced bronchodilation, and reduced inflammation. These properties could make sGC stimulators useful for treating diseases associated with endothelial dysfunction. In the future, vericiguat may provide an alternative treatment to induce bronchodilation in respiratory diseases. Full article

Cellular metabolism must adapt rapidly to environmental alterations and adjust nutrient uptake. Low glucose availability activates the AMP-dependent kinase (AMPK) pathway. We demonstrate that activation of AMPK or the downstream Unc-51-like autophagy-activating kinase (ULK1) inhibits receptor-mediated endocytosis. Beyond limiting dextran uptake, this activation prevents endocytic uptake of human pathogenic enveloped and non-enveloped, positive- and negative-stranded RNA viruses, such as yellow fever, dengue, tick-borne encephalitis, chikungunya, polio, rubella, rabies lyssavirus, and SARS-CoV-2, not only in mammalian and insect cells but also in precision-cut lung slices and neuronal organoids. ULK1 activation inhibited enveloped viruses but not EV71. However, receptor presentation at the cytoplasmic membrane remained unaffected, indicating that receptor binding was unchanged, while later stages of endocytosis were targeted via two distinct pathways. Drug-induced activation of the AMPK pathway reduced early endocytic factor TXNIP by suppressing translation. In contrast, the amounts of Rab5 and the late endosomal marker Rab7 decreased due to translation inactivation and ULK1-dependent proteasome activation within minutes. Furthermore, activation of AMPK hindered the late replication steps of SARS-CoV-2 by reducing viral RNAs and proteins and the endo-lysosomal markers LAMP1 and GRP78, suggesting a reduction in early and late endosomes and lysosomes. Inhibition of the PI3K and mTORC2 pathways, which sense amino acid and growth factor availability, promotes AMPK activity and blocks viral entry. Our results indicate that AMPK and ULK1 emerge as restriction factors of cellular endocytosis, impeding the receptor-mediated endocytic entry of enveloped and non-enveloped RNA viruses. Full article

Particulate matter (PM) is a major component of ambient air pollution. PM exposure is linked to numerous adverse health effects, including chronic lung diseases. Air quality guidelines designed to regulate levels of ambient PM are currently based on the mass concentration of different particle sizes, independent of their origin and chemical composition. The objective of this study was to assess the relative hazardous effects of carbonaceous particles (soot), ammonium nitrate, ammonium sulfate, and copper oxide (CuO), which are standard components of ambient air, reflecting contributions from primary combustion, secondary inorganic constituents, and non-exhaust emissions (NEE) from vehicular traffic. Human epithelial cells representing bronchial (BEAS-2B) and alveolar locations (H441 and A549) in the airways, human lung fibroblasts (HFL-1), and rat precision-cut lung slices (PCLS) were exposed in submerged cultures to different concentrations of particles for 5–72 h. Following exposure, cell viability, metabolic activity, reactive oxygen species (ROS) formation, and inflammatory responses were analyzed. CuO and, to a lesser extent, soot reduced cell viability in a dose-dependent manner, increased ROS formation, and induced inflammatory responses. Ammonium nitrate and ammonium sulfate did not elicit any significant cytotoxic responses but induced immunomodulatory alterations at very high concentrations. Our findings demonstrate that secondary inorganic components of PM have a lower hazard cytotoxicity compared with combustion-derived and indicative NEE components, and alveolar epithelial cells are more sensitive to PM exposure. This information should help to inform which sources of PM to target and feed into improved, targeted air quality guidelines. Full article

Asthma is a major non-communicable disease whose pathogenesis is still not fully elucidated. One of the asthma research models is precision-cut lung slices (PCLSs), and among the therapeutic options, miRNA molecules are of great interest. The aim of our study was to investigate whether inhibition of miR-223-3p and miR328a-3p affects the inflammatory response in PCLSs derived from a rat with HDM-induced allergic inflammation and a control rat. We generated rat PCLSs and transfected them with miR-223-3p and miR-328a-3p inhibitors. RNA was isolated from PCLSs and analyzed by qPCR. We also examined the proteins in the culture medium using the Magnetic Luminex Assay. The comparison between miRNA-transfected PCLSs and non-transfected controls showed significant differences in the expression of several genes associated with allergic inflammation, including Il-33, Ccl5, Prg2 and Tslp, in both the rat with allergic inflammation and the control rat. In the culture medium, we found no significant differences in protein levels between rat with allergic inflammation and the control. Our study highlighted some important issues: the need to extend the model by including more biological replicates, the need to standardize culture conditions, and the need to consider co-transfection with several miRNA inhibitors when modifying miRNAs expression in the PCLS model. Full article

There is increased interest in developing non-animal test systems for inhalation exposure safety assessments. However, defined methodologies are absent for predicting local respiratory effects from inhalation exposure to irritants. The current study introduces a concept for applying in vitro and in silico methods for inhalation exposure safety assessment. Three in vitro systems, representing the upper (MucilAir™—nasal epithelial tissue) and lower (A549 cells and human precision-cut lung slices) human respiratory regions, were exposed to six respiratory irritants. These irritant exposures were conducted as liquid droplets, aerosol, or vapors, and samples were collected over 24 h. Cytotoxicity, cytokine release, epithelial resistance, oxidative stress, and mitochondrial membrane potential were measured. To determine the human relevance of in vitro exposures, airway surface depositions were predicted by simulating airborne concentrations equivalent to the Cramer class III inhalation threshold of toxicological concern limit of 0.47 mg/person/day using an in silico model. A > 100-fold margin of exposure was calculated comparing lowest concentrations showing in vitro effects to in silico simulated values. While further studies are needed, this manuscript presents a basic requirement for employing non-animal methods to inform inhalation exposure safety assessments by combining in vitro and in silico assays. Full article

Human precision-cut lung slices (hPCLS) prepared from fibrotic lungs recapitulate the pathophysiological hallmarks of fibrosis. These hallmark features can also be induced by treating non-fibrotic hPCLS with a fibrotic cocktail (FC). As a result, the fibrotic and fibrosis-induced hPCLS are rapidly emerging as preferred models for disease modeling and drug discovery. However, current hPCLS models are limited by tissue viability in culture, as they are usually only viable for one week after harvesting. Here, we demonstrate that the fibrotic hPCLS can be cryopreserved, stored for months, and then thawed on demand without loss of hPCLS viability or protein content for 14 days post-thawing. Cryopreservation also preserves the pro-fibrotic potential of non-fibrotic hPCLS. Specifically, when we treated the thawed non-fibrotic hPCLS with an FC, we observed significant pro-fibrotic cytokine secretion and elevated tissue stiffness. These pro-fibrotic changes were inhibited by the small-molecule tyrosine kinase inhibitor, Nintedanib. Taken together, our work indicates that a feasible solution to prolong the pre-clinical utility of fibrotic and fibrosis-induced hPCLS is cryopreservation. We anticipate that cryopreserved hPCLS will serve as an advantageous predictive model for the evaluation of pro-fibrotic pathways during acute and chronic toxicity testing. Full article

Recent studies have emphasized the critical role of alteration in cellular plasticity in the development of fibrotic disorders, particularly pulmonary fibrosis, prompting further investigation into molecular mechanisms and therapeutic approaches. In this context, Precision Cut Lung Slices (PCLSs) emerge as a valuable ex vivo research tool. The process of PCLSs generation preserves most features of the naïve lung tissue, such as its architecture and complex cellular composition. We previously stimulated normal lung PCLSs with two different stimuli (fibrotic cocktail, composed by platelet lysate and TGFβ, or neutrophil extracellular traps) and we observed a significant elevation of Epithelial–Mesenchymal Transition (EMT) markers from 24 h to 72 h of culture. The aim of our work was to exploit this PCLSs based ex vivo model of EMT, to evaluate the effect of imatinib, an old tyrosine kinase inhibitor with reported anti-remodeling activities in vitro and in animal models. Imatinib treatment significantly decreased α-SMA and collagen expression already starting from 24 h on stimulated PCLS. Imatinib showed a significant toxicity on unstimulated cells (3-fold increase in ACTA2 expression levels at 24 h, 1.5-fold increase in COL1A1 expression levels at 24 h, 2-fold increase in COL3A1 expression levels at 72 h). Further evaluations on specific cell lines pointed out that drug effects were mainly directed towards A549 and LFs. In conclusion, our model confirms the anti-remodeling activity of imatinib but suggests that its direct delivery to alveolar epithelial cells as recently attempted by inhalatory preparation of the drug might be associated with a non-negligible epithelial cell toxicity. Full article

Streptococcus suis is a porcine and zoonotic pathogen in the upper respiratory tract, expressing different capsular serotypes and virulence-associated factors. Given its genomic and phenotypic diversity, the virulence potential of S. suis cannot be attributed to a single factor. Since strong inflammatory response is a hallmark of S. suis infection, the objective of this study was to investigate the differences in transcriptional host responses to two serotype 2 and one serotype 9 strains. Both serotypes are frequently found in clinical isolates. We infected porcine precision-cut lung slices (PCLSs) with two serotype 2 strains of high (strain S10) and low (strain T15) virulence, and a serotype 9 strain 8067 of moderate virulence. We observed higher expression of inflammation-related genes during early infection with strains T15 and 8067, in contrast to infection with strain 10, whose expression peaked late. In addition, bacterial gene expression from infected PCLSs revealed differences, mainly of metabolism-related and certain virulence-associated bacterial genes amongst these strains. We conclude that the strain- and time-dependent induction of genes involved in innate immune response might reflect clinical outcomes of infection in vivo, implying rapid control of infection with less virulent strains compared to the highly virulent strain S10. Full article

Background: Donor lungs are often discarded, with gastric aspiration accounting for ~9% of lungs unsuitable for transplantation. To increase the donor pool, it is important to understand the pathophysiology of aspiration-induced lung damage (AILD) and to assess its treatment. Methods: Precision-cut lung slices (PCLS) were prepared from murine lungs and exposed to acid—pH 1.5 to 5.5—for 15 min. We also investigated whether acid-exposed slices (pH 3.5) could affect unexposed slices. In addition, we investigated whether dexamethasone (0.5 or 1 μM) could mitigate and treat the damage in each group. In each experiment (n = 3), we analyzed cell viability (ATP/protein content) and markers of inflammation (IL-1β, IL-6, TNF-𝛼, TRAIL). Results: PCLS subjected to pH 1.5–3.5 had a significantly reduced amount of ATP, albeit no increase in inflammation markers. There was no interaction of secretions from acid-exposed slices on unexposed slices. Dexamethasone had no beneficial effects in either group. Conclusion: Direct exposure to acid in the PCLS leads to a decrease in cell viability. Acid-exposed slices had no effect on the cell viability of unexposed slices. Treatment with dexamethasone offered no mitigation. More studies have to be performed to elucidate the pathophysiology of AILD and the possible treatment of aspiration-induced injury. Full article

Respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infections in the elderly and in children, associated with pediatric hospitalizations. Recently, first vaccines have been approved for people over 60 years of age applied by intramuscular injection. However, a vaccination route via mucosal application holds great potential in the protection against respiratory pathogens like RSV. Mucosal vaccines induce local immune responses, resulting in a fast and efficient elimination of respiratory viruses after natural infection. Therefore, a low-energy electron irradiated RSV (LEEI-RSV) formulated with phosphatidylcholine-liposomes (PC-LEEI-RSV) was tested ex vivo in precision cut lung slices (PCLSs) for adverse effects. The immunogenicity and protective efficacy in vivo were analyzed in an RSV challenge model after intranasal vaccination using a homologous prime-boost immunization regimen. No side effects of PC-LEEI-RSV in PCLS and an efficient antibody induction in vivo could be observed. In contrast to unformulated LEEI-RSV, the mucosal vaccination of mice with PC formulated LEEI-RSV showed a statistically significant reduction in viral load after challenge. These results are a proof-of-principle for the use of LEEI-inactivated viruses formulated with liposomes to be administered intranasally to induce a mucosal immunity that could also be adapted for other respiratory viruses. Full article