Search Results (19)

Renal ischemia–reperfusion injury (IRI) is a leading trigger of acute kidney injury (AKI), a syndrome with high incidence and mortality worldwide. The kidney is among the most energy-demanding organs; its mitochondrial content is second only to the heart, rendering renal function highly contingent on mitochondrial integrity. Accumulating evidence places mitochondria at the center of IRI pathogenesis. During ischemia, ATP depletion, ionic disequilibrium, and Ca²⁺ overload set the stage for injury; upon reperfusion, a burst of mitochondrial reactive oxygen species (mtROS), collapse of the mitochondrial membrane potential (ΔΨm), aberrant opening of the mitochondrial permeability transition pore (mPTP), mitochondrial DNA (mtDNA) damage, and release of mitochondrial damage-associated molecular patterns (mtDAMPs) further amplify inflammation and drive regulated cell-death programs. In recent years, the centrality of mitochondrial bioenergetics, quality control, and immune signaling in IRI-AKI has been increasingly recognized. Building on advances from the past five years, this review synthesizes mechanistic insights into mitochondrial dysfunction in renal IRI and surveys mitochondria-targeted therapeutic strategies—including antioxidant defenses, reinforcement of mitochondrial quality control (biogenesis, dynamics, mitophagy), and modulation of mtDAMP sensing—with the aim of informing future translational efforts in AKI. Full article

Neurons have exceptionally high energy demands, sustained by thousands to millions of mitochondria per cell. Each mitochondrion depends on the integrity of its mitochondrial DNA (mtDNA), which encodes essential electron transport chain (ETC) subunits required for oxidative phosphorylation (OXPHOS). The continuous, high-level ATP production by OXPHOS generates reactive oxygen species (ROS) that pose a significant threat to the nearby mtDNA. To counter these insults, neurons rely on base excision repair (BER), the principal mechanism for removing oxidative and other small, non-bulky base lesions in nuclear and mtDNA. BER involves a coordinated enzymatic pathway that excises damaged bases and restores DNA integrity, helping maintain mitochondrial genome stability, which is vital for neuronal bioenergetics and survival. When mitochondrial BER is impaired, mtDNA becomes unstable, leading to ETC dysfunction and a self-perpetuating cycle of bioenergetic failure, elevated ROS levels, and continued mtDNA damage. Damaged mtDNA fragments can escape into the cytosol or extracellular space, where they act as damage-associated molecular patterns (DAMPs) that activate innate immune pathways and inflammasome complexes. Chronic activation of these pathways drives sustained neuroinflammation, exacerbating mitochondrial dysfunction and neuronal loss, and functionally links genome instability to innate immune signaling in neurodegenerative diseases. This review summarizes recent advancements in understanding how BER preserves mitochondrial genome stability, affects neuronal health when dysfunctional, and contributes to damage-driven neuroinflammation and neurodegenerative disease progression. We also explore emerging therapeutic strategies to enhance mtDNA repair, optimize its mitochondrial environment, and modulate neuroimmune pathways to counteract neurodegeneration. Full article

Chronic binge drinking is common among patients with alcohol-associated steatohepatitis. Therefore, we tested the hypothesis that chronic binge ethanol exposure disrupts mitophagic processing and stimulates release of mitochondrial damage-associated molecular patterns (mtDAMPs), thereby promoting hepatic inflammation and fibrosis after chronic binge ethanol (CBE) exposure in mice using the National Institute of Alcohol Abuse and Alcoholism model. After CBE, hepatic steatosis, liver injury, inflammation, and hepatic stellate cell (HSC) activation occurred. Alda-1, an aldehyde dehydrogenase-2 activator, attenuated these changes. After CBE, mitochondrial depolarization (mtDepo) occurred in ~85% hepatocytes, and mitophagy-associated proteins increased, which Alda-1 blunted. By contrast, transcription factor-EB (master regulator of lysosomal biogenesis) and lysosomal markers decreased, indicating disrupted lysosomal processing. After mitophagy, mitochondrial biogenesis (MB) restores mitochondrial mass and function. After CBE, peroxisome proliferator-activated receptor gamma coactivator-1 alpha (MB regulator), mitochondrial transcription factor-A, oxidative phosphorylation proteins, and fatty acid oxidation all decreased, which Alda-1 largely restored. After CBE, serum mtDAMPs (mitochondrial DNA and cytochrome c) increased 3- to 10-fold. In vitro, mitochondrial DNA stimulated macrophage and HSC activation, which was prevented by toll-like receptor-9 inhibition. In conclusion, CBE increases mtDepo in an acetaldehyde-dependent fashion, leading to mitophagic overburden, disruption of mitochondrial homeostasis, mtDAMP release, and ultimately development of liver inflammation and injury. Full article

Mature erythrocytes are traditionally regarded as anucleate cells lacking nuclear DNA. However, evidence shows they retain residual genetic material, including mitochondrial DNA (mtDNA) and RNA fragments. This review explores the role of such genetic material in cellular function, diagnostics, and erythropoiesis. A comprehensive literature review was conducted, focusing on (i) erythropoiesis, (ii) enucleation of erythroid precursors, (iii) the presence of DNA in red blood cells (RBCs), and (iv) RNA fragments such as messenger RNA (mRNA), microRNA (miRNA), and other non-coding RNAs. Mature RBCs harbor small amounts of DNA and diverse RNA species. Residual DNA can act as damage-associated molecular patterns (DAMPs), triggering immune responses when released under stress or injury. RNA fragments reflect the transcriptional activity of precursor cells and have been linked to potential diagnostic applications. Studies suggest that RBC-derived RNA signatures may serve as non-invasive biomarkers for diseases such as diabetes, cardiovascular conditions, and hematological disorders. These profiles mirror changes in erythropoiesis and provide insights into systemic pathophysiology. Residual genetic material in RBCs extends their role beyond oxygen transport. It contributes to immune modulation and may provide novel diagnostic and therapeutic opportunities, enhancing disease detection and understanding of erythropoiesis. Full article

Background/Objectives: Mitochondrial damage is implicated in metabolic dysfunction and may contribute to inflammation and insulin resistance, key features of type 2 diabetes. This study examined the relationship among inflammatory markers, mtDNA DAMPs, and insulin sensitivity/resistance, and evaluated their response to three dietary interventions in type 2 diabetes. Methods: Data was pooled from two clinical trials involving adults aged 35 to 75 with type 2 diabetes (n = 39). Participants followed one of three 12-week diet interventions aimed at enhancing glucose metabolism without causing weight loss. The sample was 74% female and 64% African American with a mean age of 55.6 ± 7.7 years, and 92.3% (n = 36) had overweight/obesity. Participants were assigned to either a carbohydrate-restricted, low-fat, or fruit-rich Mediterranean diet. Primary outcomes included insulin resistance (HOMA-IR), insulin sensitivity (Matsuda index), mtDNA DAMPs (ND1, ND6), pro/anti-inflammatory cytokines (IFN-γ, IL-10, IL-6, IL-8, TNF-α), CRP, and cortisol. Associations among mtDNA DAMPs, inflammation, and insulin sensitivity/resistance were examined using regression analysis Results: The carbohydrate-restricted diet led to the greatest improvements in insulin sensitivity (72.7%) and reductions in HOMA-IR (41.3%) (p = 0.03). All diets increased mtDNA DAMPs, with most observed in the fruit-rich Mediterranean diet and low-fat diet groups and the smallest in the carbohydrate-restricted group. Total mtDNA DAMPs were associated with lower insulin sensitivity (Matsuda index: β = –0.77; SE = 0.31; p = 0.02), and ND6 mtDNA DAMP levels were associated with greater insulin resistance (HOMA-IR: β = 0.90; SE = 0.40; p = 0.03) and lower insulin sensitivity (Matsuda index: β = –0.86; SE = 0.33; p = 0.01), independent of BMI and race. Proinflammatory cytokines were associated with increased HOMA-IR (β = 0.45; p = 0.007) and reduced Matsuda index (β = –0.43; p = 0.009) and moderated effects of mtDNA DAMPs on insulin sensitivity/resistance. Conclusions: These findings highlight mtDNA DAMPs in metabolic dysfunction in the context of inflammation. 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

Traumatic injury leads to an extension of the half-life of circulating neutrophils. However, how quickly neutrophil apoptosis is delayed post-injury is currently unknown, as are the underlying mechanisms and factors that promote this extension of lifespan. During the ultra-early (≤1 h) and acute (4–12 and 48–72 h) post-injury phases, we collected blood samples from 73 adult trauma patients. Following ex vivo culture, neutrophil apoptosis was measured, alongside caspase-3 activation and expression of the anti-apoptotic protein Mcl-1. To identify factors that may promote neutrophil survival post-trauma, neutrophils from healthy controls (HCs) were cultured with mitochondrial-derived damage-associated molecular patterns (mtDAMPs) or mitochondrial DNA (mtDNA). Accompanied by reduced mitochondrial membrane depolarisation, delayed Mcl-1 turnover, and reduced caspase-3 activation, the ex vivo lifespan of neutrophils from trauma patients was significantly enhanced in a protein synthesis-independent manner within minutes to hours after injury. Neutrophils from HCs exhibited delayed apoptosis when cultured in media supplemented with trauma patient serum, which occurred alongside stabilisation of Mcl-1. Culturing HCs neutrophils with mtDAMPs or mtDNA significantly delayed apoptosis rates, promoted stabilisation of Mcl-1, and reduced caspase-3 activation. The release of mtDAMPs from damaged tissue may drive post-trauma immune dysregulation by promoting the survival of dysfunctional neutrophils. Full article

Pancreatic cancer (PaCa) is among the most aggressive malignancies of the digestive system. Inflammation plays a critical role in tumor growth and dissemination, with soluble cytokines serving as messengers that facilitate interactions between immune and cancer cells. The release of cell-free mitochondrial DNA (cf-mtDNA) into the bloodstream has been identified as a potent proinflammatory trigger, acting as a mitochondrial-derived damage-associated molecular pattern (mtDAMP). Whether a relationship exists between circulating cf-mtDNA (ccf-mtDNA) unloading and inflammation in PaCa remains unclear. In this study, we quantified ccf-mtDNA levels in plasma/serum samples from PaCa patients and healthy controls and examined their association with inflammatory markers. Analyses were conducted on 14 participants: 3 controls (mean age: 52.0 ± 16.0 years, 67% women) and 11 PaCa patients (mean age: 69.1 ± 10.0 years, 27% women). Circulating levels of ccf-mtDNA in PaCa patients did not show differences compared to controls (p = 0.06). In contrast, concentrations of interleukin (IL)-8, IL-17, and interferon-gamma were significantly higher in PaCa patients. Stratification of PaCa patients based on the median ccf-mtDNA concentration revealed significantly higher levels of IL-4, IL-9, monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein 1-beta in those with ccf-mtDNA levels above the median (p < 0.05). Significant positive associations were also observed between levels of ccf-mtDNA and IL-8, fibroblast growth factor, and MCP-1. These results suggest a potential association between elevated ccf-mtDNA levels and increased concentrations of proinflammatory cytokines, especially in PaCa patients with an unfavorable prognosis. Further research with larger cohorts is required to validate these findings and assess the prognostic value of these biomarkers. Full article

Biological aging results from an accumulation of damage in the face of reduced resilience. One major driver of aging is cell senescence, a state in which cells remain viable but lose their proliferative capacity, undergo metabolic alterations, and become resistant to apoptosis. This is accompanied by complex cellular changes that enable the development of a senescence-associated secretory phenotype (SASP). Mitochondria, organelles involved in energy provision and activities essential for regulating cell survival and death, are negatively impacted by aging. The age-associated decline in mitochondrial function is also accompanied by the development of chronic low-grade sterile inflammation. The latter shares some features and mediators with the SASP. Indeed, the unloading of damage-associated molecular patterns (DAMPs) at the extracellular level can trigger sterile inflammatory responses and mitochondria can contribute to the generation of DAMPs with pro-inflammatory properties. The extrusion of mitochondrial DNA (mtDNA) via mitochondrial outer membrane permeabilization under an apoptotic stress triggers senescence programs. Additional pathways can contribute to sterile inflammation. For instance, pyroptosis is a caspase-dependent inducer of systemic inflammation, which is also elicited by mtDNA release and contributes to aging. Herein, we overview the molecular mechanisms that may link mitochondrial dyshomeostasis, pyroptosis, sterile inflammation, and senescence and discuss how these contribute to aging and could be exploited as molecular targets for alleviating the cell damage burden and achieving healthy longevity. Full article

Alterations in cellular signaling, chronic inflammation, and tissue remodeling contribute to hepatocellular carcinoma (HCC) development. The release of damage-associated molecular patterns (DAMPs) upon tissue injury and the ensuing sterile inflammation have also been attributed a role in HCC pathogenesis. Cargoes of extracellular vesicles (EVs) and/or EVs themselves have been listed among circulating DAMPs but only partially investigated in HCC. Mitochondria-derived vesicles (MDVs), a subpopulation of EVs, are another missing link in the comprehension of the molecular mechanisms underlying the onset and progression of HCC biology. EVs have been involved in HCC growth, dissemination, angiogenesis, and immunosurveillance escape. The contribution of MDVs to these processes is presently unclear. Pyroptosis triggers systemic inflammation through caspase-dependent apoptotic cell death and is implicated in tumor immunity. The analysis of this process, together with MDV characterization, may help capture the relationship among HCC development, mitochondrial quality control, and inflammation. The combination of immune checkpoint inhibitors (i.e., atezolizumab and bevacizumab) has been approved as a synergistic first-line systemic treatment for unresectable or advanced HCC. The lack of biomarkers that may allow prediction of treatment response and, therefore, patient selection, is a major unmet need. Herein, we overview the molecular mechanisms linking mitochondrial dysfunction, inflammation, and pyroptosis, and discuss how immunotherapy targets, at least partly, these routes. Full article

Mitochondrial dysfunction and neuroinflammation are implicated in the pathogenesis of most neurodegenerative diseases, such as Alzheimer’s disease (AD). In fact, although a growing number of studies show crosstalk between these two processes, there remain numerous gaps in our knowledge of the mechanisms involved, which requires further clarification. On the one hand, mitochondrial dysfunction may lead to the release of mitochondrial damage-associated molecular patterns (mtDAMPs) which are recognized by microglial immune receptors and contribute to neuroinflammation progression. On the other hand, inflammatory molecules released by glial cells can influence and regulate mitochondrial function. A deeper understanding of these mechanisms may help identify biomarkers and molecular targets useful for the treatment of neurodegenerative diseases. This review of works published in recent years is focused on the description of the mitochondrial contribution to neuroinflammation and neurodegeneration, with particular attention to mitochondrial DNA (mtDNA) and AD. Full article

During ischemia and reperfusion injury (IRI), mitochondria may release mitochondrial DNA (mtDNA). mtDNA can serve as a propagator of further injury but in specific settings has anti-inflammatory capacities as well. Therefore, the aim of this study was to study the perioperative dynamics of plasma mtDNA during living donor kidney transplantation (LDKT) and its potential as a marker of graft outcome. Fifty-six donor–recipient couples from the Volatile Anesthetic Protection of Renal Transplants-1 (VAPOR-1) trial were included. Systemic venous, systemic arterial, and renal venous samples were taken at multiple timepoints during and after LDKT. Levels of mtDNA genes changed over time and between vascular compartments. Several donor, recipient, and transplantation-related variables significantly explained the course of mtDNA genes over time. mtDNA genes predicted 1-month and 24-month estimated glomerular filtration rate (eGFR) and acute rejection episodes in the two-year follow-up period. To conclude, mtDNA is released in plasma during the process of LDKT, either from the kidney or from the whole body in response to transplantation. While circulating mtDNA levels positively and negatively predict post-transplantation outcomes, the exact mechanisms and difference between mtDNA genes are not yet understood and need further exploration. Full article

Mitochondria play a key role in regulating host metabolism, immunity and cellular homeostasis. Remarkably, these organelles are proposed to have evolved from an endosymbiotic association between an alphaproteobacterium and a primitive eukaryotic host cell or an archaeon. This crucial event determined that human cell mitochondria share some features with bacteria, namely cardiolipin, N-formyl peptides, mtDNA and transcription factor A, that can act as mitochondrial-derived damage-associated molecular patterns (DAMPs). The impact of extracellular bacteria on the host act largely through the modulation of mitochondrial activities, and often mitochondria are themselves immunogenic organelles that can trigger protective mechanisms through DAMPs mobilization. In this work, we demonstrate that mesencephalic neurons exposed to an environmental alphaproteobacterium activate innate immunity through toll-like receptor 4 and Nod-like receptor 3. Moreover, we show that mesencephalic neurons increase the expression and aggregation of alpha-synuclein that interacts with mitochondria, leading to their dysfunction. Mitochondrial dynamic alterations also affect mitophagy which favors a positive feedback loop on innate immunity signaling. Our results help to elucidate how bacteria and neuronal mitochondria interact and trigger neuronal damage and neuroinflammation and allow us to discuss the role of bacterial-derived pathogen-associated molecular patterns (PAMPs) in Parkinson’s disease etiology. Full article

Myelodysplastic Syndromes (MDSs) are bone marrow (BM) failure malignancies characterized by constitutive innate immune activation, including NLRP3 inflammasome driven pyroptotic cell death. We recently reported that the danger-associated molecular pattern (DAMP) oxidized mitochondrial DNA (ox-mtDNA) is diagnostically increased in MDS plasma although the functional consequences remain poorly defined. We hypothesized that ox-mtDNA is released into the cytosol, upon NLRP3 inflammasome pyroptotic lysis, where it propagates and further enhances the inflammatory cell death feed-forward loop onto healthy tissues. This activation can be mediated via ox-mtDNA engagement of Toll-like receptor 9 (TLR9), an endosomal DNA sensing pattern recognition receptor known to prime and activate the inflammasome propagating the IFN-induced inflammatory response in neighboring healthy hematopoietic stem and progenitor cells (HSPCs), which presents a potentially targetable axis for the reduction in inflammasome activation in MDS. We found that extracellular ox-mtDNA activates the TLR9-MyD88-inflammasome pathway, demonstrated by increased lysosome formation, IRF7 translocation, and interferon-stimulated gene (ISG) production. Extracellular ox-mtDNA also induces TLR9 redistribution in MDS HSPCs to the cell surface. The effects on NLRP3 inflammasome activation were validated by blocking TLR9 activation via chemical inhibition and CRISPR knockout, demonstrating that TLR9 was necessary for ox-mtDNA-mediated inflammasome activation. Conversely, lentiviral overexpression of TLR9 sensitized cells to ox-mtDNA. Lastly, inhibiting TLR9 restored hematopoietic colony formation in MDS BM. We conclude that MDS HSPCs are primed for inflammasome activation via ox-mtDNA released by pyroptotic cells. Blocking the TLR9/ox-mtDNA axis may prove to be a novel therapeutic strategy for MDS. Full article

The cell-free DNA (cfDNA) levels are known to increase in biological fluids in various pathological conditions. However, the data on circulating cfDNA in severe psychiatric disorders, including schizophrenia, bipolar disorder (BD), and depressive disorders (DDs), is contradictory. This meta-analysis aimed to analyze the concentrations of different cfDNA types in schizophrenia, BD, and DDs compared with healthy donors. The mitochondrial (cf-mtDNA), genomic (cf-gDNA), and total cfDNA concentrations were analyzed separately. The effect size was estimated using the standardized mean difference (SMD). Eight reports for schizophrenia, four for BD, and five for DDs were included in the meta-analysis. However, there were only enough data to analyze the total cfDNA and cf-gDNA in schizophrenia and cf-mtDNA in BD and DDs. It has been shown that the levels of total cfDNA and cf-gDNA in patients with schizophrenia are significantly higher than in healthy donors (SMD values of 0.61 and 0.6, respectively; p < 0.00001). Conversely, the levels of cf-mtDNA in BD and DDs do not differ compared with healthy individuals. Nevertheless, further research is needed in the case of BD and DDs due to the small sample sizes in the BD studies and the significant data heterogeneity in the DD studies. Additionally, further studies are needed on cf-mtDNA in schizophrenia or cf-gDNA and total cfDNA in BD and DDs due to insufficient data. In conclusion, this meta-analysis provides the first evidence of increases in total cfDNA and cf-gDNA in schizophrenia but shows no changes in cf-mtDNA in BD and DDs. Increased circulating cfDNA in schizophrenia may be associated with chronic systemic inflammation, as cfDNA has been found to trigger inflammatory responses. Full article