Mitochondrial DNA haplogroups participate in osteoarthritis: current evidence based on a meta-analysis

Next-Level Prediction of Structural Progression in Knee Osteoarthritis: A Perspective

Osteoarthritis (OA) is a prevalent and disabling chronic disease, with knee OA being the most common form, affecting approximately 73% of individuals over 55 years. Traditional clinical assessments often fail to predict knee structural progression accurately, highlighting the need for improved prognostic methods. This perspective explores the complexity of stratifying knee OA patients based on rapid structural progression. It underscores the importance of such early identification to enable timely and personalized intervention and optimize disease-modifying OA drug clinical trial design, as many trial participants show minimal progression, complicating the assessment of treatment efficacy. We highlight the potential of machine learning (ML) and deep learning (DL) in overcoming this prognostic challenge, as these methodologies enhance classification/stratification capabilities by leveraging multidimensional data and capturing the intricate relationships between diverse features. These include panels of biochemical markers and imaging markers, such as those from magnetic resonance imaging (MRI), as integrating MRI data into ML/DL prognostic models enhances such prediction performance. These automated ML/DL models will offer a transformative approach to stratifying knee OA patients and represent a paradigm shift in disease management. Ultimately, ML/DL applications will not only improve patient outcomes but will also promote innovation in OA research, clinical practice, and therapeutics.

The Interplay of Aging and PANoptosis in Osteoarthritis Pathogenesis: Implications for Novel Therapeutic Strategies

Osteoarthritis (OA) is a common degenerative joint disease characterized by the progressive degradation of articular cartilage, synovial inflammation, and subchondral bone remodeling. This review explores the interplay between aging, PANoptosis, and inflammation in OA progression. Age-related cellular and immune dysfunctions, including cellular senescence, senescence-associated secretory phenotypes (SASPs), and immunosenescence, significantly contribute to joint degeneration. In OA, dysregulated apoptosis, necroptosis, and pyroptosis, particularly in chondrocytes, exacerbate cartilage damage. Apoptosis, mediated by the JNK pathway, reduces chondrocyte density, while necroptosis and pyroptosis, involving RIPK-1/RIPK-3 and the NLRP3 inflammasome, respectively, amplify inflammation and cartilage destruction. Inflammatory cytokines and damage-associated molecular patterns (DAMPs) further enhance these PANoptotic pathways. Current therapeutic strategies primarily focus on anti-inflammatory agents such as non-steroidal anti-inflammatory drugs (NSAIDs) and corticosteroids, with growing interest in anti-senescence drugs targeting cellular senescence and SASP. Additionally, exploring PANoptosis mechanisms offers potential for innovative OA treatments.

ASA VI controls osteoarthritis in mice by maintaining mitochondrial homeostasis through Sirtuin 3

OBJECTIVE

The aim of this study was to investigate whether ASA VI controls osteoarthritis (OA) by regulating mitochondrial function.

METHODS

Primary chondrocytes were isolated and cultured from rat knee joints. The chondrocytes were treated with ASA VI and interleukin-1β (IL-1β) to simulate the inflammatory environment of OA. Cell viability, apoptosis, inflammatory cytokine levels, and extracellular matrix (ECM) component levels were assessed. Mitochondrial function, including ATP levels, mitochondrial membrane potential, reactive oxygen species (ROS) levels, and mitochondrial DNA content, was evaluated. The expression of Sirtuin 3 (Sirt3), a key regulator of mitochondrial homeostasis, was examined. Additionally, a rat OA model was established by destabilizing the medial meniscus, and the effects of ASA VI on cartilage degeneration were assessed.

RESULTS

ASA VI treatment improved cell viability, reduced apoptosis, and decreased IL-6 and TNF-α levels in IL-1β-induced chondrocytes. ASA VI also upregulated Collagen II and Aggrecan expression, while downregulating ADAMTS5 and MMP-13 expression. Furthermore, ASA VI mitigated IL-1β-induced mitochondrial dysfunction by increasing ATP levels, restoring mitochondrial membrane potential, reducing ROS production, and preserving mitochondrial DNA content. These effects were accompanied by the activation of Sirt3. In the rat OA model, ASA VI treatment increased Sirt3 expression and alleviated cartilage degeneration.

CONCLUSION

ASA VI exerts chondroprotective and anti-inflammatory effects on IL-1β-induced chondrocytes by improving mitochondrial function through Sirt3 activation. ASA VI also attenuates cartilage degeneration in a rat OA model. These findings suggest that ASA VI may be a potential therapeutic agent for the treatment of osteoarthritis by targeting mitochondrial dysfunction.

A nomogram prediction of coronary artery dilation in Kawasaki diseases based on mtDNA copy number

Objective

The level of mitochondrial DNA copy number (mtDNA-CN) in peripheral blood cells had been identified to be involved in several immune and cardiovascular diseases. Thus, the aim of this study is to evaluate the levels of mtDNA-CN in Kawasaki disease (KD) and to construct a nomogram prediction for coronary artery lesions in children with KD.

Methods

One hundred and forty-four children with KD diagnosed from March 2020 to March 2022 were involved in the study. The clinical features and laboratory test parameters of these children were assessed between the KD and normal groups. Univariable and multivariable analyses were performed sequentially to identify the essential risk factors. Subsequently, a nomogram prediction was constructed.

Results

A total of 274 children were included in the analysis. Of these, 144 (52.6%) represented the KD group. Peripheral blood DNA mtDNA qPCR showed that the -log value of mtDNA-CN in the KD group (6.67 ± 0.34) was significantly higher than that in the healthy group (6.40 ± 0.18) (P<0.001). The area under the ROC curve for mtDNA-CN in distinguishing KD was 0.757. MtDNA-CN (OR = 13.203, P = 0.009, 95% CI 1.888-92.305), RBC (OR = 5.135, P = 0.014, 95% CI 1.394-18.919), and PA (OR = 0.959, P = 0.014, 95% CI 0.927-0.991) were identified as independent risk factors for coronary artery dilation in children with KD. Finally, the nomogram predictive was established based on the results of multivariable analysis, demonstrating the satisfied prediction and calibration values.

Conclusion

The results of this study revealed that mtDNA-CN could be used as a biomarker in predicting the development of KD. Furthermore, the higher the mtDNA-CN was significantly associated with coronary artery dilation in KD.

Mitochondrial Role on Cellular Apoptosis, Autophagy, and Senescence during Osteoarthritis Pathogenesis

Authors have demonstrated that apoptosis activation is a pathway related to cartilage degradation characteristics of the OA process. Autophagy is an adaptive response to protect cells from various environmental changes, and defects in autophagy are linked to cell death. In this sense, decreased autophagy of chondrocytes has been observed in OA articular cartilage. The aim of this work was to study the role of OA mitochondria in apoptosis, autophagy, and senescence, using OA and Normal (N) transmitochondrial cybrids. Results: OA cybrids incubated with menadione showed a higher percentage of late apoptosis and necrosis than N cybrids. Stimulation of cybrids with staurosporine and IL-1β showed that OA cybrids were more susceptible to undergoing apoptosis than N cybrids. An analysis of the antioxidant response using menadione on gene expression revealed a lower expression of nuclear factor erythroid 2-like 2 and superoxide dismutase 2 in OA than N cybrids. Activation of microtubule-associated protein 1A/1B-light chain 3 was reduced in OA compared to N cybrids. However, the percentage of senescent cells was higher in OA than N cybrids. Conclusion: This work suggests that mitochondria from OA patients could be involved in the apoptosis, autophagy, and senescence of chondrocytes described in OA cartilage.

Mitonuclear epistasis involving TP63 and haplogroup Uk: Risk of rapid progression of knee OA in patients from the OAI

OBJECTIVE

To investigate genetic interactions between mitochondrial deoxyribonucleic acid (mtDNA) haplogroups and nuclear single nucleotide polymorphisms (nSNPs) to analyze their impact on the development of the rapid progression of knee osteoarthritis (OA).

DESIGN

A total of 1095 subjects from the Osteoarthritis Initiative, with a follow-up time of at least 48-months, were included. Appropriate statistical approaches were performed, including generalized estimating equations adjusting for age, gender, body mass index, contralateral knee OA, Western Ontario and McMaster Universities Osteoarthritis Index pain, previous injury in target knee and the presence of the mtDNA variant m.16519C. Additional genomic data consisted in the genotyping of Caucasian mtDNA haplogroups and eight nSNPs previously associated with the risk of knee OA in robust genome-wide association studies.

RESULTS

The simultaneous presence of the G allele of rs12107036 at TP63 and the haplogroup Uk significantly increases the risk of a rapid progression of knee OA (odds ratio = 1.670; 95% confidence interval [CI]: 1.031-2.706; adjusted p-value = 0.027). The assessment of the population attributable fraction showed that the highest proportion of rapid progressors was under the simultaneous presence of the G allele of rs12107036 and the haplogroup Uk (23.4%) (95%CI: 7.89-38.9; p-value < 0.05). The area under the curve of the cross-validation model (0.730) was very similar to the obtained for the predictive model (0.735). A nomogram was constructed to help clinicians to perform clinical trials or epidemiologic studies.

CONCLUSIONS

This study demonstrates the existence of a mitonuclear epistasis in OA, providing new mechanisms by which nuclear and mitochondrial variation influence the susceptibility to develop different OA phenotypes.

Association between mtDNA haplogroups and skeletal fluorosis in Han population residing in drinking water endemic fluorosis area of northern China

To investigate the association between mtDNA genetic information and the risk of SF, individuals were conducted in the drinking water endemic fluorosis area in northern China, sequenced the whole genome of mtDNA, identified the SNPs and SNVs, analyzed the haplogroups, and diagnosed SF, and then, the effect of mtDNA genetic information on the risk of SF was evaluated. We find that, D5 haplogroup and its specific SNPs reduced the risk, while the D4 haplogroup and its specific SNPs increased the risk of SF. The number of SNVs in coding regions of mitochondrial respiratory chain (MRC) is different between the controls and cases. This suggests that D5 haplogroup may play a protective role in the risk of SF, while the opposite is observed for the D4 haplogroup, this may relate to their specific SNPs. And SNVs that encode the MRC complex may also be associated with the risk of SF.

Mitochondrial DNA in Human Diversity and Health: From the Golden Age to the Omics Era

Mitochondrial DNA (mtDNA) is a small fraction of our hereditary material. However, this molecule has had an overwhelming presence in scientific research for decades until the arrival of high-throughput studies. Several appealing properties justify the application of mtDNA to understand how human populations are-from a genetic perspective-and how individuals exhibit phenotypes of biomedical importance. Here, I review the basics of mitochondrial studies with a focus on the dawn of the field, analysis methods and the connection between two sides of mitochondrial genetics: anthropological and biomedical. The particularities of mtDNA, with respect to inheritance pattern, evolutionary rate and dependence on the nuclear genome, explain the challenges of associating mtDNA composition and diseases. Finally, I consider the relevance of this single locus in the context of omics research. The present work may serve as a tribute to a tool that has provided important insights into the past and present of humankind.

The Role of Genetics and Epigenetic Regulation in the Pathogenesis of Osteoarthritis

Osteoarthritis (OA) is progressive disease characterised by cartilage degradation, subchondral bone remodelling and inflammation of the synovium. The disease is associated with obesity, mechanical load and age. However, multiple pro-inflammatory immune mediators regulate the expression of metalloproteinases, which take part in cartilage degradation. Furthermore, genetic factors also contribute to OA susceptibility. Recent studies have highlighted that epigenetic mechanisms may regulate the expression of OA-associated genes. This review aims to present the mechanisms of OA pathogenesis and summarise current evidence regarding the role of genetics and epigenetics in this process.

A meta-analysis and a functional study support the influence of mtDNA variant m.16519C on the risk of rapid progression of knee osteoarthritis

OBJECTIVES

To identify mitochondrial DNA (mtDNA) genetic variants associated with the risk of rapid progression of knee osteoarthritis (OA) and to characterise their functional significance using a cellular model of transmitochondrial cybrids.

METHODS

Three prospective cohorts contributed participants. The osteoarthritis initiative (OAI) included 1095 subjects, the Cohort Hip and Cohort Knee included 373 and 326 came from the PROspective Cohort of Osteoarthritis from A Coruña. mtDNA variants were screened in an initial subset of 450 subjects from the OAI by in-depth sequencing of mtDNA. A meta-analysis of the three cohorts was performed. A model of cybrids was constructed to study the functional consequences of harbouring the risk mtDNA variant by assessing: mtDNA copy number, mitochondrial biosynthesis, mitochondrial fission and fusion, mitochondrial reactive oxygen species (ROS), oxidative stress, autophagy and a whole transcriptome analysis by RNA-sequencing.

RESULTS

mtDNA variant m.16519C is over-represented in rapid progressors (combined OR 1.546; 95% CI 1.163 to 2.054; p=0.0027). Cybrids with this variant show increased mtDNA copy number and decreased mitochondrial biosynthesis; they produce higher amounts of mitochondrial ROS, are less resistant to oxidative stress, show a lower expression of the mitochondrial fission-related gene fission mitochondrial 1 and an impairment of autophagic flux. In addition, its presence modulates the transcriptome of cybrids, especially in terms of inflammation, where interleukin 6 emerges as one of the most differentially expressed genes.

CONCLUSIONS

The presence of the mtDNA variant m.16519C increases the risk of rapid progression of knee OA. Among the most modulated biological processes associated with this variant, inflammation and negative regulation of cellular process stand out. The design of therapies based on the maintenance of mitochondrial function is recommended.

Single nucleotide polymorphism genes and mitochondrial DNA haplogroups as biomarkers for early prediction of knee osteoarthritis structural progressors: use of supervised machine learning classifiers

BACKGROUND

Knee osteoarthritis is the most prevalent chronic musculoskeletal debilitating disease. Current treatments are only symptomatic, and to improve this, we need a robust prediction model to stratify patients at an early stage according to the risk of joint structure disease progression. Some genetic factors, including single nucleotide polymorphism (SNP) genes and mitochondrial (mt)DNA haplogroups/clusters, have been linked to this disease. For the first time, we aim to determine, by using machine learning, whether some SNP genes and mtDNA haplogroups/clusters alone or combined could predict early knee osteoarthritis structural progressors.

METHODS

Participants (901) were first classified for the probability of being structural progressors. Genotyping included SNP genes TP63, FTO, GNL3, DUS4L, GDF5, SUPT3H, MCF2L, and TGFA; mtDNA haplogroups H, J, T, Uk, and others; and clusters HV, TJ, KU, and C-others. They were considered for prediction with major risk factors of osteoarthritis, namely, age and body mass index (BMI). Seven supervised machine learning methodologies were evaluated. The support vector machine was used to generate gender-based models. The best input combination was assessed using sensitivity and synergy analyses. Validation was performed using tenfold cross-validation and an external cohort (TASOAC).

RESULTS

From 277 models, two were defined. Both used age and BMI in addition for the first one of the SNP genes TP63, DUS4L, GDF5, and FTO with an accuracy of 85.0%; the second profits from the association of mtDNA haplogroups and SNP genes FTO and SUPT3H with 82.5% accuracy. The highest impact was associated with the haplogroup H, the presence of CT alleles for rs8044769 at FTO, and the absence of AA for rs10948172 at SUPT3H. Validation accuracy with the cross-validation (about 95%) and the external cohort (90.5%, 85.7%, respectively) was excellent for both models.

CONCLUSIONS

This study introduces a novel source of decision support in precision medicine in which, for the first time, two models were developed consisting of (i) age, BMI, TP63, DUS4L, GDF5, and FTO and (ii) the optimum one as it has one less variable: age, BMI, mtDNA haplogroup, FTO, and SUPT3H. Such a framework is translational and would benefit patients at risk of structural progressive knee osteoarthritis.

The Role of Mitochondrial Metabolism, AMPK-SIRT Mediated Pathway, LncRNA and MicroRNA in Osteoarthritis

Osteoarthritis (OA) is the most common joint disease characterized by degeneration of articular cartilage and causes severe joint pain, physical disability, and impaired quality of life. Recently, it was found that mitochondria not only act as a powerhouse of cells that provide energy for cellular metabolism, but are also involved in crucial pathways responsible for maintaining chondrocyte physiology. Therefore, a growing amount of evidence emphasizes that impairment of mitochondrial function is associated with OA pathogenesis; however, the exact mechanism is not well known. Moreover, the AMP-activated protein kinase (AMPK)–Sirtuin (SIRT) signaling pathway, long non-coding RNA (lncRNA), and microRNA (miRNA) are important for regulating the physiological and pathological processes of chondrocytes, indicating that these may be targets for OA treatment. In this review, we first focus on the importance of mitochondria metabolic dysregulation related to OA. Then, we show recent evidence on the AMPK-SIRT mediated pathway associated with OA pathogenesis and potential treatment options. Finally, we discuss current research into the effects of lncRNA and miRNA on OA progression or inhibition.

mtDNA haplogroup A enhances the effect of obesity on the risk of knee OA in a Mexican population

To evaluate the influence of mitochondrial DNA haplogroups on the risk of knee OA in terms of their interaction with obesity, in a population from Mexico. Samples were obtained from (n = 353) knee OA patients (KL grade ≥ I) and (n = 364) healthy controls (KL grade = 0) from Mexico city and Torreon (Mexico). Both Caucasian and Amerindian mtDNA haplogroups were assigned by single base extension assay. A set of clinical and demographic variables, including obesity status, were considered to perform appropriate statistical approaches, including chi-square contingency tables, regression models and interaction analyses. To ensure the robustness of the predictive model, a statistical cross-validation strategy of B = 1000 iterations was used. All the analyses were performed using boot, GmAMisc and epiR package from R software v4.0.2 and SPSS software v24. The frequency distribution of the mtDNA haplogroups between OA patients and healthy controls for obese and non-obese groups showed the haplogroup A as significantly over-represented in knee OA patients within the obese group (OR 2.23; 95% CI 1.22–4.05; p-value = 0.008). The subsequent logistic regression analysis, including as covariate the interaction between obesity and mtDNA haplogroup A, supported the significant association of this interaction (OR 2.57; 95% CI 1.24–5.32; p-value = 0.011). The statistical cross-validation strategy confirmed the robustness of the regression model. The data presented here indicate a link between obesity in knee OA patients and mtDNA haplogroup A.

Genetic biomarkers in osteoarthritis: a quick overview

Osteoarthritis (OA) is a chronic musculoskeletal disease with a polygenic and heterogeneous nature. In addition, when clinical manifestations appear, the evolution of the disease is usually already irreversible. Therefore, the efforts on OA research are focused mainly on the discovery of therapeutic targets and reliable biomarkers that permit the early identification of different OA-related parameters such as diagnosis, prognosis, or phenotype identification. To date, potential candidate protein biomarkers have been associated with different aspects of the disease; however, there is currently no gold standard. In this sense, genomic data could act as complementary biomarkers of diagnosis and prognosis or even help to identify therapeutic targets of the disease. In this review, we will describe the most recent advances in genetic biomarkers in OA over the past three years.

Role of Mitochondria in Physiology of Chondrocytes and Diseases of Osteoarthritis and Rheumatoid Arthritis

PURPOSE OF REVIEW

Mitochondria are recognized to be one of the most important organelles in chondrocytes for their role in triphosphate (ATP) generation through aerobic phosphorylation. Mitochondria also participate in many intracellular processes involving modulating reactive oxygen species (ROS), responding to instantaneous hypoxia stress, regulating cytoplasmic transport of calcium ion, and directing mitophagy to maintain the homeostasis of individual chondrocytes.

DESIGNS

To summarize the specific role of mitochondria in chondrocytes, we screened related papers in PubMed database and the search strategy is ((mitochondria) AND (chondrocyte)) AND (English [Language]). The articles published in the past 5 years were included and 130 papers were studied.

RESULTS

In recent years, the integrity of mitochondrial structure has been regarded as a prerequisite for normal chondrocyte survival and defect in mitochondrial function has been found in cartilage-related diseases, such as osteoarthritis (OA) and rheumatoid arthritis (RA). However, the understanding of mitochondria in cartilage is still largely limited. The mechanism on how the changes in mitochondrial structure and function directly lead to the occurrence and development of cartilage-related diseases remains to be elusive.

CONCLUSION

This review aims to summarize the role of mitochondria in chondrocytes under the physiological and pathological changes from ATP generation, calcium homeostasis, redox regulation, mitophagy modulation, mitochondria biogenesis to immune response activation. The enhanced understanding of molecular mechanisms in mitochondria might offer some new cues for cartilage remodeling and pathological intervention.

Mitochondrial DNA from osteoarthritic patients drives functional impairment of mitochondrial activity: a study on transmitochondrial cybrids

With the redefinition of osteoarthritis (OA) and the understanding that the joint behaves as an organ, OA is now considered a systemic illness with a low grade of chronic inflammation. Mitochondrial dysfunction is well documented in OA and has the capacity to alter chondrocyte and synoviocyte function. Transmitochondrial cybrids are suggested as a useful cellular model to study mitochondrial biology in vitro, as they carry different mitochondrial variants with the same nuclear background. The aim of this work was to study mitochondrial and metabolic function of cybrids with mitochondrial DNA from healthy (N) and OA donors. In this work, the authors demonstrate that cybrids from OA patients behave differently from cybrids from N donors in several mitochondrial parameters. Furthermore, OA cybrids behave similarly to OA chondrocytes. These results enhance our understanding of the role of mitochondria in the degeneration process of OA and present cybrids as a useful model to study OA pathogenesis.

Relationship Between the Dynamics of Telomere Loss in Peripheral Blood Leukocytes From Knee Osteoarthritis Patients and Mitochondrial DNA Haplogroups

OBJECTIVE

To evaluate the evolution of telomere length from peripheral blood leukocytes (PBLs) in subjects from the Osteoarthritis Initiative (OAI) cohort in relation to the incidence of osteoarthritis (OA), and to explore its possible interactive influence with the mitochondrial DNA (mtDNA) haplogroup.

METHODS

Dynamics of telomere sequence loss were quantified in PBLs from initially healthy individuals (without symptoms or radiological signs), 78 carrying the mtDNA cluster HV, and 47 with cluster JT, from the OAI, during a 72-month follow-up period. The incidence of knee OA during this period (n = 39) was radiographically established when Kellgren-Lawrence (KL) score increased from < 2 at recruitment, to ≥ 2 at the end of 72 months of follow-up. Multivariate analysis using binary logistic regression was performed to assess PBL telomere loss and mtDNA haplogroups as associated risk factors of incidence of knee OA.

RESULTS

Carriers of cluster HV showed knee OA incidence twice that of the JT carriers (n = 30 vs 9). The rate of PBL telomere loss was higher in cluster HV carriers and in individuals with incident knee OA. Multivariate analysis showed that the dynamics of PBL telomere shortening can be a consistent risk marker of knee OA incidence. Subjects with nonincident knee OA showed a slower telomere loss than those with incident knee OA; the difference was more significant in carriers of cluster JT than in HV.

CONCLUSION

An increased rate of telomere loss in PBLs may reflect a systemic accelerated senescence phenotype that could be potentiated by the mitochondrial function, increasing the susceptibility of developing knee OA.

Role of mitochondria in mediating chondrocyte response to mechanical stimuli

As the most common form of arthritis, osteoarthritis (OA) has become a major cause of severe joint pain, physical disability, and quality of life impairment in the affected population. To date, precise pathogenesis of OA has not been fully clarified, which leads to significant obstacles in developing efficacious treatments such as failures in finding disease-modifying OA drugs (DMOADs) in the last decades. Given that diarthrodial joints primarily display the weight-bearing and movement-supporting function, it is not surprising that mechanical stress represents one of the major risk factors for OA. However, the inner connection between mechanical stress and OA onset/progression has yet to be explored. Mitochondrion, a widespread organelle involved in complex biological regulation processes such as adenosine triphosphate (ATP) synthesis and cellular metabolism, is believed to have a controlling role in the survival and function implement of chondrocytes, the singular cell type within cartilage. Mitochondrial dysfunction has also been observed in osteoarthritic chondrocytes. In this review, we systemically summarize mitochondrial alterations in chondrocytes during OA progression and discuss our recent progress in understanding the potential role of mitochondria in mediating mechanical stress-associated osteoarthritic alterations of chondrocytes. In particular, we propose the potential signaling pathways that may regulate this process, which provide new views and therapeutic targets for the prevention and treatment of mechanical stress-associated OA.

Potential role of mitochondria in synoviocytes

Synoviocytes are located in the synovium lining layer, which is composed of macrophage-like synoviocytes (MLS) and fibroblast-like synoviocytes (FLS) with different characteristics. Mitochondria, which exist in most cells, are two membrane-covered organelles. In addition to providing the necessary ATP for synoviocytes, mitochondria are involved in the regulation of redox homeostasis and the integration of synoviocytes death signals. In recent years, mitochondrial dysfunction has been found in rheumatoid arthritis (RA) and osteoarthritis (OA). Interestingly, recent studies have started uncovering that mitochondria that were previously reported to play a role in chondrocytes or immune cells, but not known to have pronounced roles in synoviocytes, can actually play crucial roles in the regulation of the pathological properties of the synoviocytes. The purpose of this review is to summarize our current understanding of the key role of mitochondria in synoviocytes, including mitochondrial dysfunction in synoviocytes can induce and aggravate inflammatory responses and changes in mitochondrial structure and function with the involvement of multiple cytokines, signal pathway, and hypoxic state of synovial tissue alter the response of synoviocytes to apoptotic stimulation. Also, mitochondrial abnormalities in synoviocytes promote the synoviocytes invasion and proliferation.