Search Results (166)

During donation after circulatory death (DCD), circulating levels of mitochondrial damage-associated molecular patterns (mtDAMPs) may increase, thereby exposing donor hearts to mtDAMPs prior to procurement and during machine perfusion. Mitochondrial DNA (mtDNA) is a pro-inflammatory mtDAMP that may stimulate several intracellular cascades including that of toll-like receptor 9 (TLR9). We administered mtDNA or ODN2088 (TLR9 antagonist) to hearts at reperfusion onset using an isolated rat heart model of DCD transplantation to investigate their effects. Four experimental groups were compared: (1) no ischemia; (2) ischemia; (3) ischemia + mtDNA; (4) ischemia + ODN2088. During reperfusion, cardiac power in ischemic hearts was significantly reduced compared to non-ischemic hearts (p < 0.01), and was further decreased with mtDNA (p < 0.05), but remained unchanged with ODN2088. Reduced ventricular recovery in mtDNA-treated hearts likely resulted from lower recovery of oxidative metabolism, demonstrated by reduced oxygen efficiency (p < 0.05) and a strong tendency for increased cytochrome c release (p < 0.06),indicating mitochondrial dysfunction and disruption, respectively. ODN2088 phosphorylated IκBα (NF-κB inhibitor alpha) and appeared to decrease cardiomyocyte death compared to ischemic hearts. Given the detrimental effects of circulating mtDNA on cardiac functional and metabolic recovery, circulating mtDAMPs, and particularly mtDNA, are of clinical relevance as potential therapeutic targets for optimizing graft quality and post-transplant outcomes. Full article

Feline immunodeficiency virus (FIV) is a lentivirus that exhibits significant structural and pathological similarities to human immunodeficiency virus (HIV), establishing it as a valuable model for HIV vaccine development. In this study, artificial intelligence (AI) and immunoinformatics were employed to design a novel multi-epitope DNA vaccine targeting conserved regions of the FIV gag, pol, and env genes. Predicted B-cell and T-cell epitopes were evaluated for their capacity to induce strong immune responses while minimizing allergenic or toxic effects and were linked to the immune adjuvant PADRE. Structural analysis indicated that the vaccine construct is stable, soluble, and biocompatible, with a well-folded tertiary structure that binds Toll-like receptor 9 (TLR9) and elicits robust humoral and cellular immune responses. These findings identify a promising FIV vaccine candidate and provide insights for the development of next-generation HIV vaccines. Full article

The intestinal barrier undergoes profound changes with age, impacting local immunity and systemic health, yet the mechanisms coordinating immune and microbial dynamics across the lifespan remain incompletely understood. Toll-like receptor 4 (TLR4) serves as a key mediator of host–microbiota interactions. This study investigated age-related changes in barrier function and the role of TLR4 using C57BL/6J and TLR4 knockout (TLR4^−/−) mice across key developmental stages: pups (postnatal day 9), adults (2–4 months), middle-aged (7–9 months), and old (16–19 months). Through a multi-layered approach integrating histology, microbiome profiling, short-chain fatty acid (SCFA) analysis, cytokine quantification, ex vivo functional assays, and transcriptomics, we identified a multi-phase process of intestinal remodeling. Pup-P9 mice exhibited immature colonic structure, a simple microbiota dominated by Firmicutes and Proteobacteria, and undetectable acetic acid level. Adults reached peak diversity and SCFA concentrations, marked by a rise in Bacteroidota and the emergence of Akkermansia. In middle and old age, pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) increased, Bacteroidota declined while Firmicutes, Actinobacteria, and Turicibacter expanded, and aged colons showed blunted ex vivo responses to IL-1β. This age-associated functional decline phenotype was absent in TLR4^−/− mice, supporting the involvement of TLR4 signaling. Transcriptomics further revealed biphasic PI3K/Akt activation in both pups-P9 and old mice. Together, these findings suggest a systemic rewiring of host metabolic and immune signaling pathways in response to an aging microbiota, highlighting this dynamic, lifespan-wide microbiota–host signaling axis as a potential intervention target. Full article

Background: Latent tuberculosis infection (LTBI) is the principal reservoir for active tuberculosis, with >85% of cases attributable to reactivation. Bacillus Calmette-Guérin fails to block this transition, leaving a critical gap in prevention. Methods: An immunoinformatics/reverse-vaccinology pipeline was applied to seven dormancy-related antigens retrieved from Mycobrowser. T-cell epitopes were predicted with NetMHCI/IIpan-4.1 and B-cell epitopes with ABCpred; antigenicity, allergenicity, and toxicity were evaluated with VaxiJen, AllerTOP, and ToxinPred. Secondary/tertiary structures were modeled with PSIPRED and AlphaFold-3; docking to Toll-like receptors (TLR) 2/4 and 100 ns molecular dynamics simulations assessed complex stability. Immune responses were simulated with C-ImmSim, and the mRNA sequence was human-codon-optimized using ExpOptimizer. Results: The resulting construct, RP14914P, encodes 14 cytotoxic T lymphocyte, 9 helper T lymphocyte, and 14 B-cell epitopes within an 866-aa, 90.4 kDa polypeptide. Antigenicity score = 0.7797, immunogenicity score = 8.58629. and no toxicity or allergenicity was predicted. Physicochemical analysis: instability index = 28.65, and solubility = 0.513. Estimated population coverage is 82.35% and 99.67% for Human Leukocyte Antigen (HLA)-I and HLA-II globally. Docking energies: −1477.8 kcal/mol (TLR2) and −1480.1 kcal/mol (TLR4). Molecular dynamics trajectories confirm stable binding. Immune simulation predicts potent activation of Natural Killer cells, macrophages, and dendritic cells, Th1 polarization, high interferon-γ/interleukin-2 secretion, and durable memory. Conclusions: In silico analyses predict that RP14914P exhibits favorable immunogenicity, safety, and broad population coverage, suggesting its potential as a promising mRNA vaccine candidate to prevent LTBI reactivation. However, these computational predictions require thorough experimental validation to confirm the vaccine’s immunogenicity and protective efficacy. Full article

This study investigates the genomic basis of immune adaptation in the transparent glass catfish (Kv: Kryptopterus vitreolus), focusing on the loss of the Toll-like receptor 21 (TLR21) gene. Comparative genomic analysis with closely related non-transparent North African catfish (Cg: Clarias gariepinus) revealed 11 TLR genes in the latter, while only 8 TLR genes (KvTLR1, 2, 3, 5, 7, 9, 13, and 20) were retained in the glass catfish, with TLR21 specifically absent. Collinearity analysis confirmed that the genomic region containing TLR21 is conserved across eight siluriform species, with loss exclusively in the glass catfish, supporting its lineage-specific absence. Structural expansion was notable in KvTLR5, KvTLR7, and KvTLR20. Molecular docking indicated that binding stability between CpG oligonucleotides and TLR21 varies significantly, with CpG-B 1681 showing the strongest interaction, which highlights sequence-dependent ligand recognition. Interestingly, absence of the TLR1 gene in another transparent teleost, the X-ray tetra (Pristella maxillaris), suggests that transparent fishes may share an evolutionary trend of lineage-specific TLR gene loss. Together, these findings reveal a distinctive evolutionary trajectory in the innate immune receptor family of transparent fishes and provide new molecular insights into their adaptive immune strategies. These insights will benefit the academic community by improving comparative frameworks for fish innate immunity, and they may inform disease prevention and health management strategies in aquaculture and the ornamental fish trade. Full article

Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) commonly coexists with type 2 diabetes (T2D), but their independent contributions to redox imbalance, inflammation and immune signaling remain uncertain. Objectives: This study aimed to evaluate whether the presence of MASLD alone, and the presence of T2D within MASLD, are independently associated with high-risk profiles of oxidative/antioxidant markers, peripheral blood mononuclear cell (PBMC) gene expression and adipocytokines. Methods: A total of 190 participants were categorized via abdominal ultrasound as controls (n = 46), MASLD (n = 83) or MASLD with T2D (n = 61). Measurements included advanced oxidation protein products (AOPP) and paraoxonase-1 (PON1) activity in serum; messenger ribonucleic acids expression of cluster of differentiation 36 (CD36), Toll-like receptor 9 (TLR9), and glutathione peroxidase-1 in PBMC; and adiponectin, leptin, and resistin in plasma. Biomarker values were adjusted and statistical comparisons among groups were performed using the Quade test. Subsequently, biomarkers were stratified into tertiles to examine associations between high-risk biomarker levels and the presence of MASLD or T2D in patients with MASLD using multivariate binary logistic regression. Results: Multivariate analysis showed that MASLD presence was independently associated with both increased AOPP and decreased resistin levels in the circulation. Furthermore, T2D presence in patients with MASLD was independently associated with increased CD36 and decreased TLR9 gene expression in PBMCs, as well as elevated circulating leptin levels. Conclusions: Collectively, these findings underscore the complex interplay between oxidative stress, insulin resistance, inflammation, and immune signaling in the pathogenesis of MASLD, which are fundamental factors contributing to this condition. Full article

Chronic low-grade inflammation, or “inflammaging,” is a defining feature of aging and a key driver of functional decline. Among innate immune sensors, Toll-like receptors (TLRs) are central mediators linking cellular stress to sterile inflammation, yet their modulation in physiological aging remains largely overlooked. This review bridges that gap by integrating molecular and clinical evidence on age-associated TLR remodeling and summarizing preclinical data on natural compounds that suppress TLR signaling. Across diverse inflammatory models, phytochemicals such as curcumin, quercetin, resveratrol, baicalin, and glycyrrhizin consistently downregulate Toll-like receptor 2- (TLR2-), Toll-like receptor 4- (TLR4-), and Toll-like receptor 9- (TLR9-) dependent myeloid differentiation primary response 88 (MyD88)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)/mitogen-activated protein kinase (MAPK) pathways, lowering interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor- α (TNF-α) while enhancing IL-10. These mechanisms mirror the molecular signature of inflammaging, supporting TLRs as actionable targets for restoring immune balance. Collectively, the evidence positions natural TLR modulators as a promising, yet untapped, avenue for promoting healthy aging and extending healthspan. Full article

Toll-like receptor 9 (TLR9) and Toll-like receptor 3 (TLR3), which are widely expressed in dendritic cells (DCs), function as key pattern recognition receptors (PRRs) in the immune system. Their primary roles involve specifically detecting pathogen-associated molecular patterns (PAMPs): TLR9 recognizes unmethylated CpG motifs predominantly found in bacterial and viral DNA, while TLR3 identifies viral double-stranded RNA (dsRNA), a molecular signature associated with viral replication. Their specific agonists [CpG ODN (a TLR9 agonist) and poly(I:C) (a TLR3 agonist)] can effectively activate DCs and enhance the expression of immune activation-related molecules. In this study, by establishing a mouse primary dendritic cell model and a glioma-bearing mouse model, and employing techniques such as transcriptome sequencing, we found that combined stimulation with CpG ODN and poly(I:C) significantly enhanced the anti-tumor function of DCs: in vitro, DCs subjected to combined stimulation showed upregulation of anti-tumor-related surface markers, enhanced migratory capacity, and a more effective activation of CD8⁺ T cells; in vivo, a DC vaccine loaded with tumor lysate antigen and stimulated with this combined regimen significantly delayed the progression of glioma in tumor-bearing mice. Further investigation revealed that the underlying mechanism for this enhanced effect may involve TLR9 activation promoting TLR3 upregulation through the p38 MAPK-ATF3 signaling axis. Consequently, we designed a sequential stimulation protocol (first CpG ODN then poly(I:C)), which demonstrated a stronger anti-glioma effect compared to simple combined stimulation. This study provides a new strategy for enhancing the immune efficacy of DC vaccines and has potential significance for promoting the clinical translation of DC vaccines. Full article

Particulate matter (PM) exposure is linked to chronic kidney disease; however, its effect on immunoglobulin A (IgA) nephropathy (IgAN) remains unclear. We investigated whether PM exposure exacerbates IgAN in a mouse model. HIGA mice (IgAN model) and BALB/c controls were exposed to PM in a sealed chamber for 13 weeks. Lung Toll-like receptor 9 (TLR9) expression, serum aberrantly glycosylated IgA, A proliferation-inducing ligand (APRIL) levels, mesangial IgA deposition, and kidney pathology were assessed. RNA sequencing of splenic B cells was performed to evaluate immune-related gene expression. PM exposure increased lung TLR9 expression in both strains, particularly around pigment-laden macrophages. HIGA mice showed elevated aberrant IgA and APRIL levels, with aggravated mesangial expansion and IgA deposition. Transcriptomic analysis revealed immune dysregulation in splenic B cells of PM-exposed HIGA mice. Our findings provide experimental evidence that PM exposure aggravates IgAN via TLR9-mediated mucosal immune activation, leading to aberrant IgA glycosylation and mesangial deposition. These findings emphasize that reducing PM exposure may benefit patients with IgAN. Full article

Objectives: This phase Ib study assessed the safety and compatibility of indirect oregovomab immunization and Toll-like-receptor-3 (TLR3) stimulation with immune adjuvant Hiltonol^® (poly-ICLC) and induced clinically relevant CA125-specific anti-tumor immunity in heavily pretreated patients with progressive platinum-resistant ovarian cancer (PROC). Methods: Patients with elevated serum CA125 level >50 U/mL received four intravenous infusions with 2 mg oregovomab followed by 2 mg Hiltonol^® intramuscular 30 min and 48 h post-oregovomab at weeks 0, 3, 6, and 9. At week 12, imaging was performed, and salvage chemotherapy was allowed post-progression per the investigator’s discretion. The Fifth/final oregovomab with Hiltonol^® infusion was given at week 16. Results: Fifteen enrolled patients were analyzed for safety and efficacy. Thirteen (87%) patients completed at least three Hiltonol^® infusions with oregovomab, specifically, two cycles (n = 2), three cycles (n = 2), four cycles (n = 3), and five cycles (n = 8). Adverse events included mild fatigue, flu-like symptoms, chills, axillary pain, and injection site discomfort in 13 (87%) patients. Serious adverse events were reported in seven (47%) patients, including Grade 3 hypertension (n = 2), thrombocytopenia (n = 1), and Grade 3 events attributed to underlying disease (n = 4). Ten (67%) patients had disease progression, three (20%) had stable disease, and two were unevaluable. Early humoral response by week 6 was observed in seven of nine (77%) patients, median progression-free survival was 2.7 months (95% confidence interval [CI]: 2.2, 3.3), and median overall survival was 15.0 months (95% CI: 8.2–23.9). Conclusions: The safety and compatibility of combining oregovomab with Hiltonol^® have been demonstrated in this study. The potential to enhance activity of chemotherapy using oregovomab indirect immunization and Hiltonol^® stimulation is proposed. Full article

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is recognized by pattern recognition receptors (PRRs), which play a vital role in triggering innate immune responses such as the production of type I and III interferons (IFNs). While modest PRR activation helps to defend against SARS-CoV-2, excessive or sustained activation can cause harmful inflammation and contribute to severe Coronavirus Disease 2019 (COVID-19). Altered expression of Toll-like receptors (TLRs), which are among the most important members of the PRR family members, particularly TLRs 2, 3, 4, 7, 8 and 9, has been strongly linked to COVID-19 severity. Furthermore, retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated protein 5 (MDA5), collectively known as RLRs (RIG-I-like receptors), act as sensors that detect SARS-CoV-2 RNA. The expression of these receptors, as well as that of different DNA sensors, varies in patients infected with SARS-CoV-2. Changes in PRR expression, particularly that of TLRs, cyclic GMP-AMP synthase (cGAS), and the stimulator of interferon genes (STING), have also been shown to play a role in the development and persistence of long COVID (LC). However, SARS-CoV-2 has evolved strategies to evade PRR recognition and subsequent signaling pathway activation, contributing to the IFN response dysregulation observed in SARS-CoV-2-infected patients. Nevertheless, PRR agonists and antagonists remain promising therapeutic targets for SARS-CoV-2 infection. This review aims to describe the PRRs involved in recognizing SARS-CoV-2, explore their expression during SARS-CoV-2 infection, and examine their role in determining the severity of both COVID-19 and long-term manifestations of the disease. It also describes the strategies developed by SARS-CoV-2 to evade PRR recognition and activation. Moreover, given the considerable interest in modulating PRR activity as a novel immunotherapy approach, this review will provide a description of PRR agonists and antagonists that have been investigated as antiviral strategies against SARS-CoV-2. This review aims to explore the complex interplay between PRRs and SARS-CoV-2 in depth, considering its implications for prognostic biomarkers, targeted therapeutic strategies and the mechanistic understanding of long LC. Additionally, it outlines future perspectives that could help to address knowledge gaps in PRR-mediated responses during SARS-CoV-2 infection. Full article

Background/Objectives: Fibromyalgia causes chronic long-term pain, with symptoms lasting for months to years. Given the lack of evidence-based methods for diagnosing and assessing fibromyalgia, it ranks among the most difficult chronic pain conditions to treat. Programmed cell death ligand 1 (PD-L1) can inhibit acute and chronic pain transmission by inhibiting neuronal ion channels. Methods: Here, we aimed to explore the analgesic efficacy and mechanism of PD-L1/PD1 in an intermittent cold stress-induced fibromyalgia pain mouse model. Results: Von Frey and Hargreaves tests were performed, showing that the mouse model exhibited mechanical (day 4: 2.08 ± 0.13 g, n = 9) and thermal hyperalgesia (day 4: 3.93 ± 0.45 s, n = 9). Electroacupuncture (EA) or intraventricular PD-L1 injection effectively alleviated the nociceptive response and led to low PD-1 levels in the mouse dorsal root ganglia, spinal cord, thalamus, somatosensory cortex, and cerebellum, as measured through Western blots. In contrast, the pain-related kinase levels increased after fibromyalgia induction; these effects were reversed by EA and PD-L1 via the inhibition of microglia/astrocytes and Toll-like receptor 4. Conclusions: Our results show that EA can treat fibromyalgia pain in mice through effects on the PD-L1/PD1 pathway, indicating its potential as a therapeutic target in fibromyalgia. Full article

The innate immune system protects against infection and cellular damage by recognizing conserved pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Emerging evidence suggests that aberrant epigenetic modifications—such as altered DNA methylation and histone marks—can serve as immunogenic signals that activate pattern recognition receptor (PRR)-mediated immune surveillance. This review explores the concept that epigenetic marks may function as DAMPs or even mimic PAMPs. I highlight how unmethylated CpG motifs, which are typically suppressed using host methylation, are recognized as foreign via Toll-like receptor 9 (TLR9). I also examine how cytosolic DNA sensors, including cGAS, detect mislocalized or hypomethylated self-DNA resulting from genomic instability. In addition, I discuss how extracellular histones and nucleosomes released during cell death or stress can act as DAMPs that engage TLRs and activate inflammasomes. In the context of cancer, I review how epigenetic dysregulation can induce a “viral mimicry” state, where reactivation of endogenous retroelements produces double-stranded RNA sensed by RIG-I and MDA5, triggering type I interferon responses. Finally, I address open questions and future directions, including how immune recognition of epigenetic alterations might be leveraged for cancer immunotherapy or regulated to prevent autoimmunity. By integrating recent findings, this review underscores the emerging concept of the epigenome as a target of innate immune recognition, bridging the fields of immunology, epigenetics, and cancer biology. Full article

Diabetic cardiomyopathy (DCM) is a common and clinically relevant complication of diabetes mellitus, defined by myocardial dysfunction in the absence of overt coronary artery disease or systemic hypertension. Recent studies have identified proprotein convertase subtilisin/kexin type 9 (PCSK9) as a pivotal mediator in the pathogenesis of DCM. PCSK9 contributes not only to dyslipidemia via degradation of LDLR and consequent elevation of circulating LDL-C, but also to metabolic derangements and inflammation through interactions with receptors such as CD36 and Toll-like receptor 4 (TLR4). In DCM, PCSK9 has been shown to exacerbate inflammation and pyroptosis and is closely linked to impaired autophagic function. Elevated circulating PCSK9 has emerged as a potential biomarker for cardiovascular events in patients with type 2 diabetes mellitus (T2DM). At the same time, long-term administration of PCSK9 inhibitors (PCSK9i) has not been associated with a significant increase in incident diabetes. Furthermore, PCSK9 loss-of-function mutations have been linked to a modestly heightened risk of T2DM, underscoring its complex involvement in cardiometabolic regulation and disease. This review synthesizes current insights into the mechanistic and therapeutic roles of PCSK9 in DCM, aiming to inform precision cardiovascular risk management strategies in T2DM populations. Full article

Systemic lupus erythematosus (SLE) is characterized by autoimmune dysregulation, elevated autoantibody production, and persistent inflammation, predisposing patients to atherosclerosis (AS). Atherogenesis is dependent on lipid homeostasis and inflammatory processes, with the formation of lipid-laden, macrophage-derived foam cells (MDFC) essential for atherosclerotic lesion progression. Elevated cholesterol levels within lipid rafts trigger heightened pro-inflammatory responses in macrophages via Toll-like receptor 9 (TLR9). Artesunate (ART), an artemisinin derivative sourced from Artemisia annua, exhibits therapeutic potential in modulating inflammation and autoimmune conditions. Nonetheless, its impact and mechanisms in SLE-associated AS (SLE-AS) remain largely unexplored. Our investigation demonstrated that ART could effectively ameliorate lupus-like symptoms and atherosclerotic plaque development in SLE-AS mice. Moreover, ART enhanced cholesterol efflux from MDFC by upregulating ABCA1, ABCG1, and SR-B1 both in vivo and in vitro. Moreover, ART reduced cholesterol accumulation in bone marrow-derived macrophages (BMDMs), thereby diminishing TLR9 recruitment to lipid rafts. ART also suppressed TLR9 expression and its downstream effectors in the kidney and aorta of SLE-AS mice, attenuating the TLR9-mediated inflammatory cascade in CPG2395 (ODN2395)-stimulated macrophages. Through bioinformatics analysis and experimental validation, PPARγ was identified as a pivotal downstream mediator of ART in macrophages. Depleting PPARγ levels reduced the expression of ABCA1, ABCG1, and SR-B1 in macrophages, consequently impeding cholesterol efflux. In conclusion, these findings suggest that ART ameliorates SLE-AS by restoring cholesterol homeostasis through the PPARγ-ABCA1/ABCG1/SR-B1 pathway and suppressing lipid raft-driven TLR9/MyD88 inflammation. Full article