Rheumatoid arthritis and mitochondrial homeostasis: The crossroads of metabolism and immunity

Links Between Cellular Energy Metabolism and Pain Sensation

One of the functions of organism cells is to maintain energy homeostasis to promote metabolism and adapt to the environment. The 3 major pathways of cellular energy metabolism are glycolysis, the tricarboxylic acid (TCA) cycle, and oxidative phosphorylation (OXPHOS). Neurons, astrocytes, and microglia are crucial in allodynia, hyperalgesia, and sensitization in nociceptive pathways. This review focused on these 3 major cellular energy metabolism pathways, aiming to elucidate the relationship between neurocyte and pain sensation and present the reprogramming of energy metabolism on pain, as well as the cellular and molecular mechanism underlying various forms of pain. The clinical and preclinical drugs involved in pain treatment and molecular mechanisms via cellular energy metabolism were also discussed.

X-chromosome-linked miR-542-5p as a key regulator of sex disparity in rats with adjuvant-induced arthritis by promoting Th17 differentiation

BACKGROUND

Studies have indicated that X-linked microRNAs (miRNAs) play a role in the pathogenesis of rheumatoid arthritis (RA) and its gender-specific differences. However, research on specific miRNAs remains limited. This study aims to investigate the possible role of X-linked miR-542-5p in RA pathogenesis and gender differences.

METHODS

We investigated the impact of miR-542-5p on RA pathogenesis and gender differences by manipulating its expression in various rat models.

RESULTS

Our findings revealed a significant overexpression of miR-542-5p in RA patients compared with healthy individuals, with a notable gender difference among RA patients. In vivo experiments confirmed that upregulation of miR-542-5p could accelerate RA pathogenesis. Further analysis showed that the onset of adjuvant-induced arthritis (AIA) in rats exhibited significant gender differences, with more severe clinical phenotypes found in female rats. This may be attributed to their stronger immune responses and elevated levels of miR-542-5p. Subsequent in vitro and in vivo experiments demonstrated that miR-542-5p contributes to the regulation of gender differences in RA pathogenesis by promoting the differentiation of Th17 cells.

CONCLUSIONS

This study offers new insights into the sex-specific nature of RA, suggesting X-linked miR-542-5p as a potential target for both diagnostic and therapeutic purposes. These findings lay the groundwork for the development of gender-specific therapeutic strategies for RA and underscore the importance of gender consideration in RA research.

Glucose metabolism is controlled by non-coding RNAs in autoimmune diseases; a glimpse into immune system dysregulation

The immune system accidentally targets the body's tissues, causing inflammation and tissue damage, the root causes of autoimmune illnesses. In recent studies, non-coding RNAs have been shown to significantly control gene expression and metabolic pathways linked to autoimmune diseases. This review investigates the effects of non-coding RNA on glucose metabolism, a route frequently dysregulated in autoimmune illnesses such as multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, and diabetes. We review how non-coding RNA affects immune cell activity modulation, glucose absorption, glycolysis, and other metabolic processes critical to immune function. We also investigate the possibility of using non-coding RNA-mediated metabolic pathway targeting as a new therapeutic approach to treat autoimmune disorders. By clarifying the complex interplay of non-coding RNA, glucose metabolism, and immune dysregulation, this study endeavors to enhance comprehension of autoimmune etiology and facilitate the creation of focused therapies.

Regulation of reactive oxygen species and the role of mitochondrial apoptotic-related genes in rheumatoid arthritis

Previous research suggests mitochondrial apoptosis alleviates rheumatoid arthritis (RA), but the role of mitochondrial apoptosis-related genes (MARGs) is unclear. Urgent exploration of RA-related mitochondrial apoptosis biomarkers is needed. Gene Expression Ontology (GEO)-derived RA datasets were used to identify differentially expressed genes (DEGs) compared to normal controls, intersected with MARGs to obtain differentially expressed mitochondrial apoptosis-related genes (DE-MARGs). Three ML algorithms screened diagnostic biomarkers. A nomogram was built and validated by receiver operating characteristic (ROC) analysis. Gene Set Enrichment Analysis (GSEA), regulatory network, and drug prediction explored biomarker mechanisms. Finally, key cells analysis included clustering, type annotation, pseudo-temporal study, and interaction, focusing on validated biomarker expression in those cells. A total of 147 DE-MARGs linked to energy & ROS metabolism were identified. Four validated biomarkers (MRPS10, EEF2, HSPA9, TUFM) formed a new RA diagnostic model. Moreover, GSEA linked them to oxidative phosphorylation. YY1 regulates EEF2, HSPA9, MRPS10; FOXO3 regulates EEF2, TUFM. Drugs like Nonoxynol-9, Nedocromil, Gadobutrol target these biomarkers. In addition, biomarkers are expressed in plasmablasts, with CD74 as a key receptor binding multiple ligands. RA biomarkers (MRPS10, EEF2, HSPA9, TUFM) linked to energy & ROS, progression tied to AMPK/mTOR, CD74-MIF crucial. Study advances RA pathogenesis knowledge, supporting clinical diagnosis.

Important Role of Mitochondrial Dysfunction in Immune Triggering and Inflammatory Response in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease, primarily characterized by chronic symmetric synovial inflammation and erosive bone destruction.Mitochondria, the primary site of cellular energy production, play a crucial role in energy metabolism and possess homeostatic regulation capabilities. Mitochondrial function influences the differentiation, activation, and survival of both immune and non-immune cells involved in RA pathogenesis. If the organism experiences hypoxia, genetic predisposition, and oxidative stress, it leads to mitochondrial dysfunction, which further affects immune cell energy metabolism, synovial cell proliferation, apoptosis, and inflammatory signaling, causing the onset and progression of RA; and, mitochondrial regulation is becoming increasingly important in the treatment of RA.In this review, we examine the structure and function of mitochondria, analyze the potential causes of mitochondrial dysfunction in RA, and focus on the mechanisms by which mitochondrial dysfunction triggers chronic inflammation and immune disorders in RA. We also explore the effects of mitochondrial dysfunction on RA immune cells and osteoblasts, emphasizing its key role in the immune response and inflammatory processes in RA. Furthermore, we discuss potential biological processes that regulate mitochondrial homeostasis, which are of great importance for the prevention and treatment of RA.

The dysregulation of mitochondrial homeostasis-related genes could be involved in the decrease of mtDNA copy number in systemic lupus erythematosus patients

Systemic lupus erythematosus (SLE) is a chronic multifactorial autoimmune disease. It is now widely demonstrated that oxidative stress (OS) plays an important role in the modulation of the pathogenesis of this disease. Mitochondrial DNA (mtDNA) is highly vulnerable to OS and it is known a decrease of mtDNA copy number in SLE patients. However, to date, it has not been investigated if this decrease is associated with a dysregulation of mitochondrial homeostasis genes. Our aim is to evaluate the amount of mtDNA copy number and the expression of the genes more involved in the mitochondrial homeostasis pathways, in peripheral blood mononuclear cells (PBMCs) of SLE patients and healthy controls. We analysed the amount of mtDNA in PBMCs of 72 SLE patients and 61 healthy controls by qPCR. Then, we investigated the expression variability of TFAM and SIRT1 (biogenesis), MFN1 and MFF (fusion/fission) and PRKN2 (mitophagy) genes in a subgroup of SLE patients and healthy controls. Interestingly, we have observed a highly significant decrease in mtDNA copies in SLE patients compared to healthy controls (P < 0.0001). In addition, we have shown that the expression levels of SIRT1, MFN1 and PRKN2 genes were significantly decreased in SLE patients with respect to healthy controls (P = 0.00001 for SIRT1, P = 0.0150 for MFN1 and P = 0.0009 for PRKN2). Lastly, we have reported a positive correlation between PRKN2 expression level and mtDNA copy number (P = 0.019, r = 0.475). In conclusion, our data confirm the impairment of mtDNA copy number in the disease and show for the first time a dysregulation of the mitochondrial homeostasis genes. These results could provide additional support to the important role of mitochondria in SLE development.

WTAP promotes fibroblast-like synoviocyte pyroptosis in Rheumatoid arthritis by upregulating N6-methyladenosine modification of NLRP3

Rheumatoid arthritis (RA) is a chronic condition characterized by inflammation and an abnormal immune response. N6-methyladenosine (m6A) methylation has altered nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain-containing (NLRP) 3. This change is implicated in the regulation of cell pyroptosis and inflammation. WTAP has a crucial role in regulating NLRP3 m6A. In this work, we used a rat model of collagen-induced arthritis (CIA) to investigate the involvement of WTAP in the evolution of inflammation in RA. The purpose of silencing or overexpressing WTAP in RA-fibroblast-like synoviocytes (RA-FLSs) treated with TNF-α was to identify its impact on pyroptosis, NLRP3 inflammasome-related proteins, the secretion of pro-inflammatory cytokines and migration. Bioinformatics techniques were used to pinpoint the exact target controlled by WTAP. To assess WTAP and NLRP3's role in RA-FLSs, we used methylated RNA immunoprecipitation, LDH test, flow cytometry, RT-qPCR, Western blotting, and Transwell. Our results show that WTAP expression is upregulated in both RA rats and cell models. Cell pyroptosis, NLRP3-related pro-inflammatory cytokines, and migration were reduced in TNF-α-treated RA-FLSs when WTAP was knocked down, whereas overexpression of WTAP displayed the opposite effect in RA-FLSs. WTAP mediated m6A modification in the NLRP3 mRNA and enhanced its mRNA stability. These results suggested that WTAP promoted FLSs pyroptosis and related inflammatory response via NLRP3 and identified WTAP as a potential target for treating RA.

Mitochondria: a breakthrough in combating rheumatoid arthritis

As a chronic autoimmune disease with complex aetiology, rheumatoid arthritis (RA) has been demonstrated to be associated with mitochondrial dysfunction since mitochondrial dysfunction can affect the survival, activation, and differentiation of immune and non-immune cells involved in the pathogenesis of RA. Nevertheless, the mechanism behind mitochondrial dysfunction in RA remains uncertain. Accordingly, this review addresses the possible role and mechanisms of mitochondrial dysfunction in RA and discusses the potential and challenges of mitochondria as a potential therapeutic strategy for RA, thereby providing a breakthrough point in the prevention and treatment of RA.

Mammalian STE20-like kinase 1 inhibits synoviocytes activation in rheumatoid arthritis through mitochondrial dysfunction mediated by SIRT3/mTOR axis

BACKGROUND

Mammalian STE20-like kinase 1 (MST1) is involved in the occurrence of cancer and autoimmune diseases by regulating cell proliferation, differentiation, apoptosis and other functions. However, its role and downstream targets in rheumatoid arthritis (RA) remain unclear.

METHODS

The model of RA fibroblast-like synoviocytes (RA-FLSs) overexpressing MST1 was constructed by lentiviral transfection in vitro and analyzed the effects of MST1 on apoptosis, migration, invasion, and inflammation of RA-FLSs. The effect of MST1 on joint synovial membrane inflammation and bone destruction was observed in vivo by establishing a rat model of arthritis with complete Freund's adjuvant.

RESULTS

MST1 is down-regulated in RA-FLSs, and up-regulation of MST1 inhibits the survival, migration, invasion and inflammation of RA-FLSs. Mechanistically, MST1 inhibits SIRT3/mTOR-signaling pathway, inducing decreased mitochondrial autophagy and increased mitochondrial fission, resulting in mitochondrial morphological abnormalities and dysfunction, and ultimately increased apoptosis. We have observed that activation of MST1 alleviates synovial inflammation and bone erosion in vivo.

CONCLUSIONS

MST1 reduces the survival, migration, invasion and inflammation of FLSs by inhibiting the SIRT3/mTOR axis to reduce mitochondrial autophagy and promote mitochondrial division, thereby achieving the potential role of relieving rheumatoid arthritis.

Current situation and trend of non-coding RNA in rheumatoid arthritis: a review and bibliometric analysis

Background

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease that affects multiple joints and has adverse effects on various organs throughout the body, often leading to a poor prognosis. Recent studies have shown significant progress in the research of non-coding RNAs (ncRNAs) in RA. Therefore, this study aims to comprehensively assess the current status and research trends of ncRNAs in RA through a bibliometric analysis.

Methods

This study retrieved articles relevant to ncRNAs and RA from the Science Citation Index Expanded Database of the Web of Science Core Collection between January 1st, 2003, and July 31st, 2023. The relevant articles were screened based on the inclusion criteria. VOSviewer and CiteSpace are utilized for bibliometric and visual analysis.

Results

A total of 1697 publications were included in this study, and there was a noticeable increase in annual publications from January 1st, 2003, to July 31st, 2023. China, the United States, and the United Kingdom were the most productive countries in this field, contributing to 43.81%, 13.09%, and 3.87% of the publications. Anhui Medical University and Lu Qianjin were identified as the most influential institution and author. Frontiers In Immunology stood out as the most prolific journal, while Arthritis & Rheumatology was the most co-cited journal. Additionally, the research related to "circular RNA", "oxidative stress", "proliferation", and "migration" have emerged as new hotspots in the field.

Conclusion

In this study, we have summarized the publication characteristics related to ncRNA and RA and identified the most productive countries, institutions, authors, journals, hot topics, and trends.

Cornerstone Cellular Pathways for Metabolic Disorders and Diabetes Mellitus: Non-Coding RNAs, Wnt Signaling, and AMPK

Metabolic disorders and diabetes (DM) impact more than five hundred million individuals throughout the world and are insidious in onset, chronic in nature, and yield significant disability and death. Current therapies that address nutritional status, weight management, and pharmacological options may delay disability but cannot alter disease course or functional organ loss, such as dementia and degeneration of systemic bodily functions. Underlying these challenges are the onset of aging disorders associated with increased lifespan, telomere dysfunction, and oxidative stress generation that lead to multi-system dysfunction. These significant hurdles point to the urgent need to address underlying disease mechanisms with innovative applications. New treatment strategies involve non-coding RNA pathways with microRNAs (miRNAs) and circular ribonucleic acids (circRNAs), Wnt signaling, and Wnt1 inducible signaling pathway protein 1 (WISP1) that are dependent upon programmed cell death pathways, cellular metabolic pathways with AMP-activated protein kinase (AMPK) and nicotinamide, and growth factor applications. Non-coding RNAs, Wnt signaling, and AMPK are cornerstone mechanisms for overseeing complex metabolic pathways that offer innovative treatment avenues for metabolic disease and DM but will necessitate continued appreciation of the ability of each of these cellular mechanisms to independently and in unison influence clinical outcome.

The impact of aging and oxidative stress in metabolic and nervous system disorders: programmed cell death and molecular signal transduction crosstalk

Life expectancy is increasing throughout the world and coincides with a rise in non-communicable diseases (NCDs), especially for metabolic disease that includes diabetes mellitus (DM) and neurodegenerative disorders. The debilitating effects of metabolic disorders influence the entire body and significantly affect the nervous system impacting greater than one billion people with disability in the peripheral nervous system as well as with cognitive loss, now the seventh leading cause of death worldwide. Metabolic disorders, such as DM, and neurologic disease remain a significant challenge for the treatment and care of individuals since present therapies may limit symptoms but do not halt overall disease progression. These clinical challenges to address the interplay between metabolic and neurodegenerative disorders warrant innovative strategies that can focus upon the underlying mechanisms of aging-related disorders, oxidative stress, cell senescence, and cell death. Programmed cell death pathways that involve autophagy, apoptosis, ferroptosis, and pyroptosis can play a critical role in metabolic and neurodegenerative disorders and oversee processes that include insulin resistance, β-cell function, mitochondrial integrity, reactive oxygen species release, and inflammatory cell activation. The silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), AMP activated protein kinase (AMPK), and Wnt1 inducible signaling pathway protein 1 (WISP1) are novel targets that can oversee programmed cell death pathways tied to β-nicotinamide adenine dinucleotide (NAD+), nicotinamide, apolipoprotein E (APOE), severe acute respiratory syndrome (SARS-CoV-2) exposure with coronavirus disease 2019 (COVID-19), and trophic factors, such as erythropoietin (EPO). The pathways of programmed cell death, SIRT1, AMPK, and WISP1 offer exciting prospects for maintaining metabolic homeostasis and nervous system function that can be compromised during aging-related disorders and lead to cognitive impairment, but these pathways have dual roles in determining the ultimate fate of cells and organ systems that warrant thoughtful insight into complex autofeedback mechanisms.

Role of mitochondrial dysfunction in the pathogenesis of rheumatoid arthritis: Looking closely at fibroblast- like synoviocytes

Rheumatoid arthritis (RA) is a chronic, autoimmune, and inflammatory disease that primarily targets the joints, leading to cartilage and bone destruction.Fibroblast-like synoviocytes (FLS) are specialized cells of the synovial lining in the joint that plays a fundamental role in the development of RA. Particularly, FLS of RA patients (RA-FLS) in the joint exhibit specific characteristics like higher invading and immunogenic properties, hyperproliferation, and reduced apoptotic capacity, suggesting a dysfunctional mitochondrial pool in these cells. Mitochondria are emerging as a potential organelle that can decide cellular immunometabolism, invasion properties, and cell death. Accordingly, multiplestudies established that mitochondria are crucial in establishing RA. However, the underlying mechanism of impaired mitochondrial function in RA remains poorly understood. This review will provide an overview of the mitochondrial role in the progression of RA, specifically in the context of FLS biology. We will also outline how mitochondria-centric therapeutics can be achieved that would yield novel avenues of research in pathological mediation and prevention.

Cognitive Impairment in Multiple Sclerosis

Almost three million individuals suffer from multiple sclerosis (MS) throughout the world, a demyelinating disease in the nervous system with increased prevalence over the last five decades, and is now being recognized as one significant etiology of cognitive loss and dementia. Presently, disease modifying therapies can limit the rate of relapse and potentially reduce brain volume loss in patients with MS, but unfortunately cannot prevent disease progression or the onset of cognitive disability. Innovative strategies are therefore required to address areas of inflammation, immune cell activation, and cell survival that involve novel pathways of programmed cell death, mammalian forkhead transcription factors (FoxOs), the mechanistic target of rapamycin (mTOR), AMP activated protein kinase (AMPK), the silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), and associated pathways with the apolipoprotein E (APOE-ε4) gene and severe acute respiratory syndrome coronavirus (SARS-CoV-2). These pathways are intertwined at multiple levels and can involve metabolic oversight with cellular metabolism dependent upon nicotinamide adenine dinucleotide (NAD+). Insight into the mechanisms of these pathways can provide new avenues of discovery for the therapeutic treatment of dementia and loss in cognition that occurs during MS.

Role of reactive oxygen species and mitochondrial damage in rheumatoid arthritis and targeted drugs

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation, pannus formation, and bone and cartilage damage. It has a high disability rate. The hypoxic microenvironment of RA joints can cause reactive oxygen species (ROS) accumulation and mitochondrial damage, which not only affect the metabolic processes of immune cells and pathological changes in fibroblastic synovial cells but also upregulate the expression of several inflammatory pathways, ultimately promoting inflammation. Additionally, ROS and mitochondrial damage are involved in angiogenesis and bone destruction, thereby accelerating RA progression. In this review, we highlighted the effects of ROS accumulation and mitochondrial damage on inflammatory response, angiogenesis, bone and cartilage damage in RA. Additionally, we summarized therapies that target ROS or mitochondria to relieve RA symptoms and discuss the gaps in research and existing controversies, hoping to provide new ideas for research in this area and insights for targeted drug development in RA.

Identification of copper death-associated molecular clusters and immunological profiles in rheumatoid arthritis

Objective

An analysis of the relationship between rheumatoid arthritis (RA) and copper death-related genes (CRG) was explored based on the GEO dataset.

Methods

Based on the differential gene expression profiles in the GSE93272 dataset, their relationship to CRG and immune signature were analysed. Using 232 RA samples, molecular clusters with CRG were delineated and analysed for expression and immune infiltration. Genes specific to the CRGcluster were identified by the WGCNA algorithm. Four machine learning models were then built and validated after selecting the optimal model to obtain the significant predicted genes, and validated by constructing RA rat models.

Results

The location of the 13 CRGs on the chromosome was determined and, except for GCSH. LIPT1, FDX1, DLD, DBT, LIAS and ATP7A were expressed at significantly higher levels in RA samples than in non-RA, and DLST was significantly lower. RA samples were significantly expressed in immune cells such as B cells memory and differentially expressed genes such as LIPT1 were also strongly associated with the presence of immune infiltration. Two copper death-related molecular clusters were identified in RA samples. A higher level of immune infiltration and expression of CRGcluster C2 was found in the RA population. There were 314 crossover genes between the 2 molecular clusters, which were further divided into two molecular clusters. A significant difference in immune infiltration and expression levels was found between the two. Based on the five genes obtained from the RF model (AUC = 0.843), the Nomogram model, calibration curve and DCA also demonstrated their accuracy in predicting RA subtypes. The expression levels of the five genes were significantly higher in RA samples than in non-RA, and the ROC curves demonstrated their better predictive effect. Identification of predictive genes by RA animal model experiments was also confirmed.

Conclusion

This study provides some insight into the correlation between rheumatoid arthritis and copper mortality, as well as a predictive model that is expected to support the development of targeted treatment options in the future.