Search Results (255)

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

Metabolic dysfunction-associated steatotic liver disease (MASLD) has emerged as the most prevalent chronic hepatopathy and a leading precursor of hepatocellular carcinoma (HCC) worldwide. Initially attributed to insulin resistance (IR)-driven metabolic imbalance, recent insights highlight a multifactorial pathogenesis involving oxidative stress (OS), chronic inflammation, and immune dysregulation. The hepatic accumulation of free fatty acids (FFAs) initiates mitochondrial dysfunction and excessive reactive oxygen species (ROS) production, culminating in lipotoxic intermediates and mitochondrial DNA damage. These damage-associated molecular patterns (DAMPs), together with gut-derived pathogen-associated molecular patterns (PAMPs), activate innate immune cells and amplify cytokine-mediated inflammation. Kupffer cell activation further exacerbates OS, while ROS-induced transcriptional pathways perpetuate inflammatory gene expression. Traditional immunity refers to the well-established dichotomy of innate and adaptive immune responses, where innate immunity provides immediate but non-specific defense, and adaptive immunity offers long-lasting, antigen-specific protection. However, a paradigm shift has occurred with the recognition of trained immunity (TI)—an adaptive-like memory response within innate immune cells that enables enhanced responses upon re-exposure to stimuli. Following non-specific antigenic stimulation, TI induces durable epigenetic and metabolic reprogramming, leading to heightened inflammatory responses and altered functional phenotypes. These rewired cells acquire the capacity to produce lipid mediators, cytokines, and matrix-modifying enzymes, reinforcing hepatic inflammation and fibrogenesis. In this context, the concept of immunometabolism has gained prominence, linking metabolic rewiring with immune dysfunction. This literature review provides an up-to-date synthesis of emerging evidence on immunometabolism and trained immunity as pathogenic drivers in MASLD. We discuss their roles in the transition from hepatic steatosis to steatohepatitis, fibrosis, and cirrhosis, and explore their contribution to the initiation and progression of MASLD-related HCC. Understanding these processes may reveal novel immunometabolic targets for therapeutic intervention. Full article

Cholangiopathies, a diverse group of diseases affecting the biliary tract, are characterized by the activation of cholangiocytes, fibrosis, and inflammation. Recent research has identified extracellular vesicles (EVs) as crucial mediators of communication within the hepatobiliary system. This review aims to explore the impact of EVs on cholangiocyte behavior and their role in disease development. EVs originating from cholangiocytes, hepatocytes, and immune cells carry a variety of molecules, including non-coding RNAs, proteins, and lipids, which influence immune responses, fibrosis, and epithelial repair. Specifically, EVs released by activated or senescent cholangiocytes can worsen inflammation and fibrosis by delivering molecules such as lncRNA H19, miR-21, and damage-associated molecular patterns (DAMPs) to hepatic stellate and immune cells. Additionally, the polarity and content of EVs are influenced by specific subcellular domains of cholangiocytes, indicating distinct signaling functions. In conditions such as primary sclerosing cholangitis (PSC), cholangiocarcinoma (CCA), and biliary atresia, EVs play a role in disease progression and offer potential as non-invasive biomarkers and therapeutic targets. This review underscores the importance of in-depth profiling and validation of EVs to fully utilize their diagnostic and therapeutic capabilities. Overall, EV-mediated signaling is a critical mechanism in cholangiopathies, providing a new avenue for understanding disease progression and developing precision medicine approaches. Full article

S100 proteins, a family of Ca²⁺-binding proteins, play numerous roles in cellular processes such as proliferation, differentiation, and apoptosis. Recent evidence has highlighted their critical involvement in neuroinflammation, a pathological hallmark of various neurodegenerative disorders including Alzheimer’s disease, multiple sclerosis, and Parkinson’s disease. Among these proteins, S100B and S100A8/A9 are particularly implicated in modulating inflammatory responses in the CNS. Acting as DAMPs, they interact with pattern recognition receptors like RAGE and TLRs, triggering pro-inflammatory signaling cascades and glial activation. While low concentrations of S100 proteins may support neuroprotective functions, increased levels are often associated with exacerbated inflammation and neuronal damage. This review explores the dualistic nature of S100 proteins in neuroinflammatory processes, their molecular interactions, and their potential as biomarkers and therapeutic targets in neurodegenerative disease management. Full article

In acute lymphoblastic leukemia (ALL), neutropenia and fever of unknown origin may occur, indicating the use of antimicrobials to control a probable infection. However, in 60–70% of cases there is no obvious infectious focus so treatment is empirical, increasing the risk of developing systemic inflammatory response syndrome (SIRS). The construction of a prognostic model of fever and development of SIRS based on the identification of endogenous molecules, called alarmins or damage-associated molecular patterns (DAMPs) and inflammatory cytokines, can help identify children with ALL and fever or SIRS and who do not have an infection. A cohort of 30 children with recently diagnosed ALL and absence of infectious microorganisms before starting the remission induction phase was studied. Two groups were identified: (1) a group with SIRS (fever, tachycardia, tachypnea, and leukopenia, without focus of infection) and (2) a group without SIRS. The DAMPs, namely HMGB1 and S100A8 proteins, were quantified by ELISA and inflammatory mediators were determined by multiple protein analysis. The medians of DAMPs and inflammatory mediators in children with SIRS were higher than in children who did not have SIRS, and the delta values of the biomarkers studied in patients with and without SIRS showed important differences, with statistically higher medians in patients with SIRS compared to those without SIRS. HMGB1 together with IL-1β, IL-8, IL-10, and MCP-1 can serve as biomarkers to identify children with ALL and fever or SIRS who should not receive antimicrobial treatment because the origin of their fever is not due to an infectious agent. Full article

The Gliomas account for 81% of all malignant central nervous system tumors and are classified by WHO into four grades of malignancy. Glioblastoma multiforme (GBM), the most common grade IV glioma, exhibits an extremely aggressive phenotype and a dismal five-year survival rate of only 6%, underscoring the urgent need for novel therapeutic approaches. Immunotherapy has emerged as a promising strategy, and photodynamic therapy (PDT) in particular has attracted attention for its dual cytotoxic and immunostimulatory effects. In GBM models, PDT induces immunogenic cell death characterized by the release of damage-associated molecular patterns (DAMPs), which promote antigen presentation and activate T cell responses. Additionally, PDT transiently increases blood–brain barrier permeability, facilitating immune cell infiltration into the tumor microenvironment, and enhances clearance of waste products via stimulation of meningeal lymphatic vessels. Importantly, PDT can reprogram or inactivate immunosuppressive tumor-associated macrophages, thereby counteracting the pro-tumoral microenvironment. Despite these encouraging findings, further preclinical and clinical studies are required to elucidate PDT’s underlying immunological mechanisms fully and to optimize treatment regimens that maximize its efficacy as part of integrated immunotherapeutic strategies against GBM. Full article

Post-traumatic stress disorder (PTSD) has traditionally been viewed as a psychiatric disorder of fear, memory, and emotional regulation. However, growing evidence implicates systemic and neuroinflammation as key contributors. Individuals with PTSD often exhibit elevated blood levels of pro-inflammatory cytokines such as IL-1β, IL-6, TNF-α, and C-reactive protein, indicating immune dysregulation. Dysfunctions in the hypothalamic–pituitary–adrenal (HPA) axis marked by reduced cortisol levels impair the body’s ability to regulate inflammation, allowing persistent immune activation. Circulating cytokines cross a weakened blood–brain barrier and activate microglia, which release additional inflammatory mediators. This neuroinflammatory loop can damage brain circuits critical to emotion processing including the hippocampus, amygdala, and prefrontal cortex, and disrupt neurotransmitter systems like serotonin and glutamate, potentially explaining PTSD symptoms such as hyperarousal and persistent fear memories. Rodent models of PTSD show similar inflammatory profiles, reinforcing the role of neuroinflammation in disease pathology. Bromo-epi-androsterone (BEA), a synthetic analog of dehydroepiandrosterone (DHEA), has shown potent anti-inflammatory effects in clinical trials, significantly reducing IL-1β, IL-6, and TNF-α. By modulating immune activity, BEA represents a promising candidate for mitigating neuroinflammation and its downstream effects in PTSD. These findings support the rationale for initiating clinical trials of BEA as a novel therapeutic intervention for PTSD. Full article

Background: Cancer stem cells (CSCs) are a subpopulation of cancer cells known for their self-renewal capacity, tumorigenicity, and resistance to treatment. Toll-like receptor 3 (TLR3) plays a complex role in cancer, exhibiting both pro-apoptotic and pro-tumorigenic effects. This study investigates the pro-tumorigenic role of TLR3, specifically its impact on CSCs in head and neck cancer. Methods: We have investigated Detroit 562, FaDu and SQ20B cell lines, the latter being stably transfected with a plasmid containing inducible shRNA for TLR3, by cultivating them to form tumor spheres in order to study CSCs. Results: Our findings demonstrate that TLR3 activation promotes stemness in head and neck cancer cell lines. This is evidenced by increased tumor sphere formation, promotion of epithelial-to-mesenchymal transition (EMT), upregulated stemness gene expression, and elevated aldehyde dehydrogenase (ALDH) activity. Conditional TLR3 knockdown abolished tumor sphere formation, confirming its important role. Furthermore, TLR3 activation triggers the secretion of damage-associated molecular patterns (DAMPs) into the tumor microenvironment, leading to increased cancer cell migration. This was inhibited by DAMP inhibitors. In patient tissue samples, we observed co-localization of TLR3 with stemness markers CD133 and ALDH1, as well as with heat shock protein 70 (HSP70) and receptor for advanced glycation end products (RAGE). We then explored potential CSC-targeted therapies, initially combining the apoptosis inducer poly (I:C) with DAMP inhibitors and γ-irradiation. While this combination proved effective in adherent cells, it failed to eliminate tumor spheres. Nevertheless, we discovered that proton radiotherapy, particularly when combined with aspirin (HMGB1 inhibitor) and poly (I:C), effectively eliminates CSCs. Conclusions: This novel combination holds promise for the development of new therapeutic strategies for head and neck cancers, particularly given the promising results of proton therapy in treating this disease. Full article

Background: Ischemia–reperfusion injury (IRI) is a key contributor to graft dysfunction in kidney transplantation. Cell-free mitochondrial DNA (mtDNA) is increasingly recognized as a damage-associated molecular pattern (DAMP) and biomarker in IRI, but its prognostic role in living donor kidney transplantation (LDKT) remains unclear. Methods: This post hoc analysis of the VAPOR-1 study evaluated urinary mtDNA (UmtDNA) in 57 LDKT recipients. MtDNA levels (ND1, ND6, and D-loop) were measured at five early timepoints post-transplantation using qPCR. Associations between early UmtDNA and long-term graft function, defined by estimated glomerular filtration rate (eGFR) at 1, 12, and 24 months, were analyzed. Results: Higher UmtDNA levels in the first urine after reperfusion were significantly associated with improved eGFR at 12 months and a positive change in eGFR between month 1 and 24. These associations were not attributable to urine creatinine levels or mitochondrial copy number. Conclusions: In this LDKT cohort, elevated early UmtDNA may reflect a well-functioning graft capable of clearing systemic mtDNA rather than ongoing tubular injury. These findings suggest that the biological interpretation of mtDNA as a biomarker is context-dependent and call for careful reconsideration of its role in early transplant monitoring. Full article

Preterm premature rupture of membranes (pPROM) is a leading cause of preterm birth (PTB) and is increasingly recognized for its association with neurodevelopmental disorders (NDDs). The disruption of fetal membrane integrity introduces potential infection and inflammation into the intrauterine environment, triggering immune responses that may affect fetal development. Placental inflammation plays a pivotal role in mediating these effects, exposing the fetus to cytokines, oxidative stress, and potential microbial insults that contribute to adverse neurodevelopmental outcomes. This review examines the current evidence of the mechanistic pathways linking pPROM-induced placental inflammation to NDDs, emphasizing the roles of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) in the inflammatory responses. We discuss how these immune activations lead to immune cell recruitment and excessive (or uncontrolled) production of inflammatory mediators, leading to an overall inflammatory imbalance that has been linked to disrupted fetal brain development in animal models. Animal models provide critical insights into how both sterile and pathogenic placental inflammation alter fetal neurodevelopment, while human studies, though limited, highlight promising biomarkers and potential therapeutic targets. This review identifies critical knowledge gaps and outlines future directions to mitigate the impact of placental inflammation on long-term infant health. Full article

Systemic sclerosis (SSc) is an autoimmune fibrotic disorder affecting the skin and internal organs, categorized as either limited cutaneous SSc, where distal areas of skin are involved, or diffuse cutaneous SSc, where more extensive proximal skin involvement is seen. Vascular remodelling and internal organ involvement are frequent complications in both subsets. Multiple pathogenic mechanisms have been demonstrated, including production of disease-specific autoantibodies, endothelial cell damage at an early stage, infiltration of involved tissues by immune cells, as well as environmental factors triggering the onset such as solvents and viruses. Although not strongly familial, susceptibility to SSc is associated with multiple single nucleotide polymorphisms in immunoregulatory genes relevant to antigen presentation, T cell signalling and adaptive immunity, as well as innate immunity. In addition, several lines of evidence demonstrate abnormalities within the epithelial cell layer in SSc. Macroscopically, the SSc epidermis is pigmented, thickened and stiff and strongly promotes myofibroblasts in co-culture. Moreover, multiple activating factors and pathways have been implicated in the disease epidermis, including wound healing responses, induction of damage associated molecular patterns (DAMPS) and the release of pro-fibrotic growth factors and cytokines. Similar to SSc, data from studies of cutaneous wound healing indicate a major role for epidermal keratinocytes in regulating local fibroblast responses during repair of the wound defect. Since the epithelium is strongly exposed to environmental factors and richly populated with protective immune cells, it is possible that disease-initiating mechanisms in SSc involve dysregulated immunity and tissue repair within this cell layer. Treatments designed to restore epithelial homeostasis or else disrupt epithelial–fibroblast cross-talk could be of benefit in this severe and resistant disease. Accordingly, single cell analysis has confirmed an active signature in SSc keratinocytes, which was partially reversed following a period of JAK inhibitor therapy. Full article

Neutrophils are essential components of innate immunity, executing a range of effector functions including phagocytosis, degranulation, and the release of neutrophil extracellular traps (NETs). A key hallmark of NET formation is the presence of citrullinated histone H3 (CitH3), produced by peptidylarginine deiminases (PAD2 and PAD4) to facilitate chromatin decondensation. While NETs play critical antimicrobial roles, excessive or dysregulated NET formation, termed NETosis, can drive tissue injury, chronic inflammation, and organ dysfunction across a wide spectrum of diseases. Beyond its structural role within NETs, CitH3 acts as a damage-associated molecular pattern (DAMP), amplifying immune activation and pathological inflammation. Elevated CitH3 levels have been identified as biomarkers in sepsis, viral infections, ischemia–reperfusion injury, organ transplantation, diabetic wounds, autoimmune diseases, and cancer. Despite increasing recognition of CitH3’s pathogenic contributions, its therapeutic potential remains largely untapped. This review summarizes recent advances in understanding the role of CitH3 in NETosis and immune dysfunction, highlights emerging strategies targeting CitH3 therapeutically, and identifies critical knowledge gaps. Collectively, these insights position CitH3 as a promising druggable biomarker for the diagnosis, prognosis, and treatment of acute and chronic inflammatory diseases. Full article

Sepsis is a life-threatening syndrome characterized by a dysregulated immune response to infection, frequently leading to multiorgan failure and high mortality. Inflammasomes—cytosolic multiprotein complexes of the innate immune system—serve as critical platforms for sensing pathogen- and damage-associated molecular patterns (PAMPs and DAMPs). Key sensors such as NLRP3, AIM2, and IFI16 initiate caspase-1 activation, IL-1β and IL-18 maturation, and gasdermin D–mediated pyroptosis. In sepsis, excessive inflammasome activation drives oxidative stress, endothelial dysfunction, immunothrombosis, and immune exhaustion. This maladaptive cascade is further aggravated by the release of DAMPs and procoagulant factors, compromising vascular integrity and immune homeostasis. Prolonged activation contributes to immunoparalysis, lymphopenia, and increased susceptibility to secondary infections. Inflammasome signaling also intersects with necroptosis and ferroptosis, amplifying systemic inflammation and tissue injury. Additionally, various pathogens exploit immune evasion strategies to modulate inflammasome responses and enhance virulence. Therapeutic interventions under investigation include selective NLRP3 inhibitors, IL-1 blockers, gasdermin D antagonists, and extracorporeal cytokine hemoadsorption. Emerging approaches emphasize biomarker-guided immunomodulation to achieve personalized therapy. While preclinical studies have shown promising results, clinical translation remains limited. Targeting inflammasomes may offer a path toward precision immunotherapy in sepsis, with potential to reduce organ dysfunction and improve survival. Full article

Guanylate-binding proteins (GBPs), encompassing GBP1 through GBP7 in humans, are interferon-inducible large GTPases of the dynamin superfamily, renowned for their pivotal roles in cell-autonomous immunity against intracellular pathogens such as viruses, bacteria, and protozoa. By recognizing pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs), GBPs orchestrate lysosomal targeting, regulate inflammatory cascades, and modulate apoptosis to protect host tissues from immune-mediated damage. Beyond their foundational roles in immunity, GBPs exhibit context-dependent effects in human cancer, promoting malignancy in some tumors through enhanced immune signaling, inhibition of apoptosis, and resistance to therapies, or suppressing tumor growth through immune activation and cell cycle regulation. This comprehensive review explores the structural intricacies, immune functions, and multifaceted contributions of human GBPs to cancer, delving into their molecular mechanisms, prognostic potential, and therapeutic implications. We incorporate the latest insights to highlight how understanding GBP regulation could reshape cancer treatment strategies. Full article

Foxtail millet (Setaria italica L.), a representative C4 species, is recognized for its efficient nutrient utilization and robust abiotic stress responses. However, the molecular mechanisms mediating its tolerance to biotic stresses are poorly understood. In this study, we investigated the root transcriptomic response of foxtail millet to the damage-associated molecular pattern (DAMP), the plant elicitor peptide 1 (Pep1). Transcriptome analysis of Pep1-treated roots identified 401 differentially expressed genes (DEGs), comprising 144 up-regulated and 257 down-regulated genes. Gene Ontology (GO) enrichment analysis revealed a significant enrichment of ‘peroxidase activity’. This finding was corroborated by DAB staining, which confirmed H₂O₂ accumulation, along with elevated malondialdehyde (MDA) levels, collectively indicating oxidative stress. Notably, Pep1 treatment also resulted in a marked up-regulation of the pathogenesis-related protein 1 (PR1) gene in leaves, suggesting the activation of systemic acquired resistance. Together, these results demonstrate that Pep1 triggers substantial transcriptional reprogramming in roots, induces oxidative stress, and activates systemic defense signaling in foxtail millet. Full article