Mitochondrial DNA polymorphisms are associated with susceptibility and phenotype of systemic lupus erythematosus

Role of mitochondrial dysfunction in kidney disease: Insights from the cGAS-STING signaling pathway

ABSTRACT

Over the past decade, mitochondrial dysfunction has been investigated as a key contributor to acute and chronic kidney disease. However, the precise molecular mechanisms linking mitochondrial damage to kidney disease remain elusive. The recent insights into the cyclic guanosine monophosphate-adenosine monophosphate (GMP-AMP) synthetase (cGAS)-stimulator of interferon gene (STING) signaling pathway have revealed its involvement in many renal diseases. One of these findings is that mitochondrial DNA (mtDNA) induces inflammatory responses via the cGAS-STING pathway. Herein, we provide an overview of the mechanisms underlying mtDNA release following mitochondrial damage, focusing specifically on the association between mtDNA release-activated cGAS-STING signaling and the development of kidney diseases. Furthermore, we summarize the latest findings of cGAS-STING signaling pathway in cell, with a particular emphasis on its downstream signaling related to kidney diseases. This review intends to enhance our understanding of the intricate relationship among the cGAS-STING pathway, kidney diseases, and mitochondrial dysfunction.

Advances in the Pathogenesis and Treatment of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a genetically predisposed, female-predominant disease, characterized by multiple organ damage, that in its most severe forms can be life-threatening. The pathogenesis of SLE is complex and involves cells of both innate and adaptive immunity. The distinguishing feature of SLE is the production of autoantibodies, with the formation of immune complexes that precipitate at the vascular level, causing organ damage. Although progress in understanding the pathogenesis of SLE has been slower than in other rheumatic diseases, new knowledge has recently led to the development of effective targeted therapies, that hold out hope for personalized therapy. However, the new drugs available to date are still an adjunct to conventional therapy, which is known to be toxic in the short and long term. The purpose of this review is to summarize recent advances in understanding the pathogenesis of the disease and discuss the results obtained from the use of new targeted drugs, with a look at future therapies that may be used in the absence of the current standard of care or may even cure this serious systemic autoimmune disease.

The role of mitochondria in rheumatic diseases

The mitochondrion is an intracellular organelle thought to originate from endosymbiosis between an ancestral eukaryotic cell and an α-proteobacterium. Mitochondria are the powerhouses of the cell, and can control several important processes within the cell, such as cell death. Conversely, dysregulation of mitochondria possibly contributes to the pathophysiology of several autoimmune diseases. Defects in mitochondria can be caused by mutations in the mitochondrial genome or by chronic exposure to pro-inflammatory cytokines, including type I interferons. Following the release of intact mitochondria or mitochondrial components into the cytosol or the extracellular space, the bacteria-like molecular motifs of mitochondria can elicit pro-inflammatory responses by the innate immune system. Moreover, antibodies can target mitochondria in autoimmune diseases, suggesting an interplay between the adaptive immune system and mitochondria. In this Review, we discuss the roles of mitochondria in rheumatic diseases such as systemic lupus erythematosus, antiphospholipid syndrome and rheumatoid arthritis. An understanding of the different contributions of mitochondria to distinct rheumatic diseases or manifestations could permit the development of novel therapeutic strategies and the use of mitochondria-derived biomarkers to inform pathogenesis.

Mitochondrial impairment and repair in the pathogenesis of systemic lupus erythematosus

Nucleic acid autoantibodies, increase type I interferon (IFN-α) levels, and immune cell hyperactivation are hallmarks of systemic lupus erythematosus (SLE). Notably, immune cell activation requires high level of cellular energy that is predominately generated by the mitochondria. Mitochondrial reactive oxygen species (mROS), the byproduct of mitochondrial energy generation, serves as an essential mediator to control the activation and differentiation of cells and regulate the antigenicity of oxidized nucleoids within the mitochondria. Recently, clinical trials on normalization of mitochondrial redox imbalance by mROS scavengers and those investigating the recovery of defective mitophagy have provided novel insights into SLE prophylaxis and therapy. However, the precise mechanism underlying the role of oxidative stress-related mitochondrial molecules in skewing the cell fate at the molecular level remains unclear. This review outlines distinctive mitochondrial functions and pathways that are involved in immune responses and systematically delineates how mitochondrial dysfunction contributes to SLE pathogenesis. In addition, we provide a comprehensive overview of damaged mitochondrial function and impaired metabolic pathways in adaptive and innate immune cells and lupus-induced organ tissues. Furthermore, we summarize the potential of current mitochondria-targeting drugs for SLE treatment. Developing novel therapeutic approaches to regulate mitochondrial oxidative stress is a promising endeavor in the search for effective treatments for systemic autoimmune diseases, particularly SLE.

Mitochondria in the Pathogenesis of Systemic Lupus Erythematosus

PURPOSE OF REVIEW

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by autoantibody production and inflammation in multiple organs. In this article, we present data on how various mitochondria pathologies are involved in the pathogenesis of the disease including the fact that they serve as a reservoir of autoantigens which contribute to the upending of lymphocyte tolerance.

RECENT FINDINGS

Mitochondrial DNA from various cell sources, including neutrophil extracellular traps, platelets, and red blood cells, elicits the production of type I interferon which contributes to breaking of peripheral tolerance. Mitochondrial DNA also serves as autoantigen targeted by autoantibodies. Mutations of mitochondrial DNA triggered by reactive oxygen species induce T cell cross-reactivity against self-antigens. Selective gene polymorphisms that regulate mitochondrial apoptosis in autoreactive B and T cells represent another key aspect in the induction of autoimmunity. Various mitochondrial abnormalities, including changes in mitochondrial function, oxidative stress, genetic polymorphism, mitochondrial DNA mutations, and apoptosis pathways, are each linked to different aspects of lupus pathogenesis. However, whether targeting these mitochondrial pathologies can be used to harness autoimmunity remains to be explored.

Mitochondrial DNA genetic variants are associated with systemic lupus erythematosus susceptibility, glucocorticoids efficacy, and prognosis

OBJECTIVE

To investigate the associations of mitochondrial DNA (mtDNA) genetic variants with systemic lupus erythematosus (SLE) susceptibility, glucocorticoids (GCs) efficacy, and prognosis.

METHODS

Our study was done in two stages. First, we performed the whole mitochondrial genome sequencing in 100 patients and 100 controls to initially screen potential mtDNA variants associated with disease and glucocorticoids efficacy. Then, we validated the results in an independent set of samples. In total, 605 SLE patients and 604 normal controls were included in our two-stage study. A two-stage efficacy study was conducted in 512 patients treated with GCs for 12 weeks. We also explored the association between mtDNA variants and SLE prognosis.

RESULTS

In the combined sample, four mtDNA variants (A4833G, T5108C, G14569A, CA514-515-) were associated with SLE susceptibility (all P  BH<0.05). We confirmed that T16362C was related to GCs efficacy (P  BH=0.014). Significant associations were detected between T16362C and T16519C and the efficacy of GCs in females with SLE (P  BH<0.05). In the prognosis study, variants A4833G (P  BH=0.003) and G14569A (P  BH=9.744 × 1 0 -4) substantially increased SLE relapse risk. Female patients harbouring variants T5108C and T16362C were more prone to relapse (P  BH<0.05). Haplotype analysis showed that haplogroup G was linked with SLE susceptibility (P  BH=0.001) and prognosis (P  BH=0.013). Moreover, mtDNA variants-environment interactions were observed.

CONCLUSION

We identified novel mtDNA genetic variants that were associated with SLE susceptibility, GCs efficacy, and prognosis. Interactions between mtDNA variants and environmental factors were related to SLE risk and GCs efficacy. Our findings provide important information for future understanding the occurrence and development of SLE.

Abnormal Mitochondrial Physiology in the Pathogenesis of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by abnormalities within the innate and adaptive immune systems. Activation and proliferation of a wide array of immune cells require significant up-regulation in cellular energy metabolism, with the mitochondria playing an essential role in the initiation and maintenance of this response. This article highlights how abnormal mitochondrial function may occur in SLE and focuses on how energy metabolism, oxidative stress, and impaired mitochondrial repair play a role in the pathogenesis of the disease. How this may represent an appealing novel therapeutic target for future drug therapy in SLE also is discussed.

Targeting Mitochondrial-Derived Reactive Oxygen Species in T Cell-Mediated Autoimmune Diseases

Mitochondrial dysfunction resulting in oxidative stress could be associated with tissue and cell damage common in many T cell-mediated autoimmune diseases. Autoreactive CD4 T cell effector subsets (Th1,Th17) driving these diseases require increased glycolytic metabolism to upregulate key transcription factors (TF) like T-bet and RORγt that drive differentiation and proinflammatory responses. However, research in immunometabolism has demonstrated that mitochondrial-derived reactive oxygen species (ROS) act as signaling molecules contributing to T cell fate and function. Eliminating autoreactive T cells by targeting glycolysis or ROS production is a potential strategy to inhibit autoreactive T cell activation without compromising systemic immune function. Additionally, increasing self-tolerance by promoting functional immunosuppressive CD4 T regulatory (Treg) cells is another alternative therapeutic for autoimmune disease. Tregs require increased ROS and oxidative phosphorylation (OxPhos) for Foxp3 TF expression, differentiation, and anti-inflammatory IL-10 cytokine synthesis. Decreasing glycolytic activity or increasing glutathione and superoxide dismutase antioxidant activity can also be beneficial in inhibiting cytotoxic CD8 T cell effector responses. Current treatment options for T cell-mediated autoimmune diseases such as Type 1 diabetes (T1D), multiple sclerosis (MS), rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE) include global immunosuppression, antibodies to deplete immune cells, and anti-cytokine therapy. While effective in diminishing autoreactive T cells, they can also compromise other immune responses resulting in increased susceptibility to other diseases and complications. The impact of mitochondrial-derived ROS and immunometabolism reprogramming in autoreactive T cell differentiation could be a potential target for T cell-mediated autoimmune diseases. Exploiting these pathways may delay autoimmune responses in T1D.

The Role of Mitochondria in Systemic Lupus Erythematosus: A Glimpse of Various Pathogenetic Mechanisms

BACKGROUND

Systemic Lupus Erythematosus (SLE) is a polysystem autoimmune disease that adversely affects human health. Various organs can be affected, including the kidney or brain. Traditional treatment methods for SLE primarily rely on glucocorticoids and immunosuppressors. Unfortunately, these therapeutic agents cannot prevent a high recurrence rate after SLE remission. Therefore, novel therapeutic targets are urgently required.

METHODS

A systematic search of the published literature regarding the abnormal structure and function of mitochondria in SLE and therapies targeting mitochondria was performed in several databases.

RESULTS

Accumulating evidence indicates that mitochondrial dysfunction plays important roles in the pathogenesis of SLE, including influencing mitochondrial DNA damage, mitochondrial dynamics change, abnormal mitochondrial biogenesis and energy metabolism, mitophagy, oxidative stress, inflammatory reactions, apoptosis and NETosis. Further investigation of mitochondrial pathophysiological roles will result in further clarification of SLE. Specific lupus-induced organ damage also exhibits characteristic mitochondrial changes.

CONCLUSION

This review aimed to summarize the current research on the role of mitochondrial dysfunction in SLE, which will necessarily provide potential novel therapeutic targets for SLE.

Carnitine Palmitoyl Transferase Deficiency in a University Immunology Practice

PURPOSE

This report describes the clinical manifestations of 35 patients sent to a University Immunology clinic with a diagnosis of fatigue and exercise intolerance who were identified to have low carnitine palmitoyl transferase activity on muscle biopsies.

RECENT FINDINGS

All of the patients presented with fatigue and exercise intolerance and many had been diagnosed with fibromyalgia. Their symptoms responded to treatment of the metabolic disease. Associated symptoms included bloating, diarrhea, constipation, gastrointestinal reflux symptoms, recurrent infections, arthritis, dyspnea, dry eye, visual loss, and hearing loss. Associated medical conditions included Hashimoto thyroiditis, Sjogren's syndrome, seronegative arthritis, food hypersensitivities, asthma, sleep apnea, and vasculitis. This study identifies clinical features that should alert physicians to the possibility of an underlying metabolic disease. Treatment of the metabolic disease leads to symptomatic improvement.

Immunometabolic disorders in the pathogenesis of systemic lupus erythematosus

Systemic lupus erythematosus is a chronic autoimmune disease connected with complex and unclear disorders of the immune system, which causes inflammation of body tissues and internal organs. It leads to the formation of anti-nuclear antibodies (ANA) and immune complexes. Numerous immune system disorders and dysfunctions in the biochemical processes can occur in the course of the disease, and a wide range of abnormalities associated with cellular respiratory processes and mitochondrial function have been documented. The following paper presents the current understanding of the contribution of these disorders to the pathogenesis of lupus.

Mitochondrial gene polymorphism is associated with gut microbial communities in mice

Gut microbial communities are key mediators of health and disease and have the capacity to drive the pathogenesis of diverse complex diseases including metabolic and chronic inflammatory diseases as well as aging. Host genetics is also a major determinant of disease phenotypes, whereby two different genomes play a role, the nuclear (nDNA)- and mitochondrial genome (mtDNA). We investigated the impact of mutations in mtDNA on the gut microbiota using conplastic mouse strains exhibiting distinct mutations in their mtDNA on an identical nDNA. Each of three strain tested harbors a distinct gut microbiota, ranging from differences at the phylum- to operational taxonomic units level. The C57BL/6J-mt FVB/NJ strain, carrying a mutation in the mitochondrial ATP8 synthase gene, exhibits higher Firmicutes abundance than Bacteroidetes, indicating a possible indicative for metabolic dysfunctions. In line with this, the C57BL/6J-mt FVB/NJ displays a variety of different phenotypes, including increased susceptibility to metabolic-related and inflammatory disorders. Furthermore, we discuss the cross-talk between mitochondrial genome/mitochondria and commensal microbiota in relation to clinical phenotypes. In summary, we demonstrate that mutations in mtDNA lead to significant differences in the composition of gut microbial communities in mice. Such differences may facilitate the emergence of metabolic disease and therefore constitute potential therapeutic targets.

The Effects of Genetic Background of Mouse Models of Cancer: Friend or Foe?

Over the past century, mice have been selectively bred to give rise to the strains used in biomedical research today. Mouse models of cancer allow researchers to control variables of diet, environment, and genetic heterogeneity to better dissect the role of these factors in cancer in humans. Because of the important role of genetic background in cancer, the strain of the mouse can introduce confounding results in studies of mouse models if not properly controlled. Conversely, genetic variation between strains can also provide important new insights into cancer mechanisms. Here, the sources of genetic heterogeneity in mouse models are reviewed, with an explanation of how heterogeneity modifies cancer phenotypes.

Association of mtDNA M/N haplogroups with systemic lupus erythematosus: a case-control study of Han Chinese women

To investigate whether mitochondrial DNA haplogroups M or N are related to occurrence or manifestations of systemic lupus erythematosus (SLE), we collected M/N haplogrouping and clinical characteristics from 868 Han Chinese women with SLE, as well as for 870 age-matched healthy Han Chinese control women. M/N haplogroups were determined in all subjects using allele-specific amplification. The frequency of M haplogroup in all patients was 429 (49.4%) and the frequency of N haplogroup, 439 (50.6%). The corresponding frequencies in controls were 456 (52.4%) and 414 (47.6%) (P = 0.213). Among women older than 50 years at onset age, the N haplogroup was significantly higher in patients than in healthy controls (59.6% vs 41.7%, P = 0.042). The N haplogroup was associated with significantly higher risk for certain SLE characteristics: hematological system damage (OR 2.128, 95%CI 1.610 to 2.813), skin impairment (OR 1.873, 95%CI 1.428 to 2.457), neurological disturbance (OR 3.956, 95%CI 1.874 to 8.352) and alopecia (OR 1.322, 95%CI 1.007 to 1.737 ). Our results suggest that in Han Chinese women, the mtDNA N haplogroup is associated with higher risk of late-onset SLE, skin impairment, neurological disturbance, hematological system damage and alopecia.

The mtDNA nt7778 G/T polymorphism augments formation of lymphocytic foci but does not aggravate cerulein-induced acute pancreatitis in mice

A polymorphism in the ATP synthase 8 (ATP8) gene of the murine mitochondrial genome, G-to-T transversion at position 7778, has been suggested to increase susceptibility to multiple autoimmune diseases, including autoimmune pancreatitis (AIP). The polymorphism also induces mitochondrial reactive oxygen species generation, secretory dysfunction and β-cell mass adaptation. Here, we have used two conplastic mouse strains, C57BL/6N-mtAKR/J (B6-mtAKR; nt7778 G; control) and C57BL/6N-mtFVB/N (B6-mtFVB; nt7778 T), to address the question if the polymorphism also affects the course of cerulein-induced acute pancreatitis in mice. Therefore, two age groups of mice (3 and 12-month-old, respectively) were subjected to up to 7 injections of the secretagogue cerulein (50 µg/kg body weight) at hourly intervals. Disease severity was assessed at time points from 3 hours to 7 days based on pancreatic histopathology, serum levels of α-amylase and activities of myeloperoxidase (MPO) in lung tissue. A comparison of cerulein-induced pancreatic tissue damage and increases of α-amylase and MPO activities showed no differences between the age-matched groups of both strains. Interestingly, histological evaluation of pancreatic tissue of both untreated and cerulein-treated B6-mtAKR and B6-mtFVB mice also revealed the presence of infiltrates of immune cells surrounding ducts and vessels; a finding that is compatible with an early stage of AIP. After recovery from cerulein-induced pancreatitis (day 7 after the injections), 12-month-old B6-mtFVB mice but not B6-mtAKR mice displayed aggravated lymphocytic lesions. A comparison of 12-month-old mice with other age groups of both strains revealed that lymphocytic foci were largely absent in 3-month-old mice, while 24-month-old mice were more affected. Together, our data suggest that the mtDNA nt7778 G/T polymorphism does not aggravate cerulein-induced acute pancreatitis. Autoimmune-like lesions, however, may progress faster if additional tissue damage occurs.

Mitochondrial DNA damage is associated with damage accrual and disease duration in patients with systemic lupus erythematosus

OBJECTIVE

To determine the extent of mitochondrial DNA (mtDNA) damage in systemic lupus erythematosus (SLE) patients compared to healthy subjects and to determine the factors associated with mtDNA damage among SLE patients.

METHODS

A cross-sectional study was performed in 86 SLE patients (per American College of Rheumatology classification criteria) and 86 healthy individuals matched for age and gender. Peripheral blood mononuclear cells (PBMCs) were collected from subjects to assess the relative amounts of mtDNA damage. Quantitative polymerase chain reaction assay was used to measure the frequency of mtDNA lesions and mtDNA abundance. Socioeconomic-demographic features, clinical manifestations, pharmacologic treatment, disease activity, and damage accrual were determined. Statistical analyses were performed using t test, pairwise correlation, and Pearson's chi-square test (or Fisher's exact test) as appropriate.

RESULTS

Among SLE patients, 93.0% were women. The mean (SD) age was 38.0 (10.4) years and the mean (SD) disease duration was 8.7 (7.5) years. SLE patients exhibited increased levels of mtDNA damage as shown by higher levels of mtDNA lesions and decreased mtDNA abundance as compared to healthy individuals. There was a negative correlation between disease damage and mtDNA abundance and a positive correlation between mtDNA lesions and disease duration. No association was found between disease activity and mtDNA damage.

CONCLUSION

PBMCs from SLE patients exhibited more mtDNA damage compared to healthy subjects. Higher levels of mtDNA damage were observed among SLE patients with major organ involvement and damage accrual. These results suggest that mtDNA damage have a potential role in the pathogenesis of SLE.

Leukocyte mitochondrial DNA alteration in systemic lupus erythematosus and its relevance to the susceptibility to lupus nephritis

The role of mitochondrial DNA (mtDNA) alterations in the pathophysiology of systemic lupus erythematosus (SLE) remains unclear. We investigated sequence variations in the D310 region and copy number change of mtDNA in 85 SLE patients and 45 normal subjects. Leukocyte DNA and RNA were extracted from leukocytes of the peripheral venous blood. The D310 sequence variations and copy number of mtDNA, and mRNA expression levels of mtDNA-encoded genes in leukocytes were determined by quantitative real-time polymerase chain reaction (Q-PCR) and PCR-based direct sequencing, respectively. We found that leukocyte mtDNA in SLE patients exhibited higher frequency of D310 heteroplasmy (69.4% vs. 48.9%, p = 0.022) and more D310 variants (2.2 vs. 1.7, p = 0.014) than those found in controls. Among normal controls and patients with low, medium or high SLE disease activity index (SLEDAI), an ever-increasing frequency of D310 heteroplasmy was observed (p = 0.021). Leukocyte mtDNA copy number tended to be low in patients of high SLEDAI group (p = 0.068), especially in those harboring mtDNA with D310 heteroplasmy (p = 0.020). Moreover, the mtDNA copy number was positively correlated with the mRNA level of mtDNA-encoded ND1 (NADH dehydrogenase subunit 1) (p = 0.041) and ATPase 6 (ATP synthase subunit 6) (p = 0.030) genes. Patients with more D310 variants were more susceptible to lupus nephritis (p = 0.035). Taken together, our findings suggest that decrease in the mtDNA copy number and increase in D310 heteroplasmy of mtDNA are related to the development and progression of SLE, and that the patients harboring more D310 variants of mtDNA are more susceptible to lupus nephritis.

Mitochondria DNA polymorphisms are associated with susceptibility to endometriosis

Because energy production involves oxidative phosphorylation, mitochondria are major sources of reactive oxygen species in the cell. Recent findings indicate that mitochondrial DNA (mtDNA) variants may play a role in the etiology of certain autoimmune and chronic inflammatory diseases. The aim of this study was to investigate the possible association between mtDNA polymorphisms and susceptibility to endometriosis. This study included 198 patients with histologically confirmed endometriosis and 167 patients without endometriosis as controls. Common variants of mtDNA at nt10398 (A/G transition), nt13708 (G/A transition), and nt16189 (T/C transition) were detected using polymerase chain reaction. An association study was performed with a chi-square test and logistic regression analysis. The prevalence of the mtDNA nt16189 variant was higher in patients with endometriosis (46.0%, 91 of 198) than in controls (34.7%, 58 of 167) (p=0.030) with odds ratio (OR) of 1.98 (95% confidence interval [CI]: 1.04-3.78). A combination of the 10398 and 16189 variants was also associated with increased risk for endometriosis (OR=1.90, 95% CI: 1.13-3.18, p=0.015). These associations remained significant even after adjusting for age and body mass index. Our data strongly suggest that the mtDNA 16189 variants and the combination of mtDNA 16189 and 10398 variants increase susceptibility to endometriosis.

Can estrogens promote hypertension during systemic lupus erythematosus?

SLE is a chronic autoimmune inflammatory disorder that predominantly affects young women. Based on this observation, it has been speculated that sex steroids, particularly estrogens, contribute to SLE disease progression. Young women with SLE are at an increased risk for the development of hypertension yet the reasons for this are unclear. One potential mechanism for the increased risk of hypertension during SLE is the chronic inflammation caused by immune complex mediated tissue injury. Estrogens are known to have an immunomodulatory role that can lead to the production of characteristic autoantibodies important for immune complex formation. Therefore, it is conceivable that during SLE estrogens contribute to tissue injury, increased inflammation and hypertension. This brief review discusses the increased risk for hypertension during SLE, the role of estrogens in immune system function, evidence for estrogens in SLE, and a possible link between estrogens and SLE hypertension.

Type B coxsackieviruses and their interactions with the innate and adaptive immune systems

Coxsackieviruses are important human pathogens, and their interactions with the innate and adaptive immune systems are of particular interest. Many viruses evade some aspects of the innate response, but coxsackieviruses go a step further by actively inducing, and then exploiting, some features of the host cell response. Furthermore, while most viruses encode proteins that hinder the effector functions of adaptive immunity, coxsackieviruses and their cousins demonstrate a unique capacity to almost completely evade the attention of naive CD8(+) T cells. In this artcle, we discuss the above phenomena, describe the current status of research in the field, and present several testable hypotheses regarding possible links between virus infection, innate immune sensing and disease.

The mtDNA nt7778 G/T polymorphism affects autoimmune diseases and reproductive performance in the mouse

Mitochondria are organelles of all nucleated cells, and variations in mtDNA sequence affect a wide spectrum of human diseases. However, animal models for mtDNA-associated diseases are rare, making it challenging to explore mechanisms underlying the contribution of mitochondria. Here, we identify a polymorphism in the mitochondrial genome, G-to-T at position 7778, which results in an aspartic acid-to-tyrosine (D-Y) substitution in the fifth amino acid of the highly conserved N-terminus of ATP synthase 8 (ATP8). Using a series of conplastic strains we show that this polymorphism increases susceptibility to multiple autoimmune diseases, including collagen-induced arthritis, autoimmune diabetes, nephritis and autoimmune pancreatitis. In addition, it impairs reproductive performance in females, but only in the MRL/MpJ strain. We also demonstrate that the mtAtp8 polymorphism alters mitochondrial performance, increasing H(2)O(2) production and affecting mitochondrial structure. Functional analysis reveals that the polymorphism increase the CD4 T cell adaptive potential to an oxidative phosphorylation impaired condition. Our findings provide direct experimental evidence for the role of mitochondria in autoimmunity and reproduction.