Rheumatoid arthritis (RA) is an autoimmune disease characterized by complex pathogenesis, with its development closely linked to immune dysregulation. Regulatory T cells (Tregs), as specialized immunomodulatory cells, play a pivotal role in negatively regulating immune responses and maintaining autoimmune tolerance. In recent years, extensive research has focused on the relationship between Tregs and RA pathogenesis, with the functional role of CD8⁺ Tregs as a critical area of investigation. This review summarizes the alterations in CD8⁺ Tregs during RA progression and their potential mechanisms of action. By elucidating the diversity of CD8⁺ Treg subsets and their intricate roles in modulating immune responses, this analysis provides novel insights and therapeutic strategies for RA diagnosis and treatment.
Arthritis, Rheumatoid/pathology* ; Humans ; T-Lymphocytes, Regulatory/immunology* ; CD8-Positive T-Lymphocytes/immunology* ; Animals

OBJECTIVE: To elucidate the role and underlying mechanism of ubiquitin-specific protease 35 (USP35) in ferroptosis of rheumatoid arthritis-fibroblast like synoviocytes (RA-FLS), thereby enhancing our comprehension of the pathogenesis of RA and identifying potential therapeutic targets for its treatment. METHODS: (1) RA-FLS were cultured in vitro and transduced with lentiviral vectors to establish stable cell lines: A USP35-knockdown line (short hairpin ribonucleic acid of USP35, shUSP35) and its control (negtive control of short hairpin ribonucleic acid, shNC), as well as a overexpression of USP35 line (USP35 OE) and its control (Vector). To investigate the role of USP35 in ferroptosis regulation, a ferroptosis model was induced in RA-FLS by treatment with 1 μmol/L Erastin. The cells were divided into six groups: shNC, shNC + Erastin, shUSP35 + Erastin, Vector, Vector + Erastin, and USP35 OE + Erastin. (2) Cell viability was detected using the cell counting kit-8 (CCK-8). (3) Reactive oxygen species (ROS), malondialdehyde (MDA), glutathione/glutathione disulfide (GSH/GSSG) ratios, and Ferrous ion (Fe²⁺) levels were measured using specific assay kits to evaluate oxidative stress, lipid peroxidation, and glutathione redox status in the cells. (4) Protein expression levels of solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) were detected using Western blotting to investigate their potential involvement in USP35-mediated ferroptosis regulation. RESULTS: (1) Compared with the shNC +Erastin group, the cell viability of the shUSP35+Erastin group was significantly decreased (P < 0.001), while it was notably increased in the USP35 OE+Erastin group compared with the Vector+Erastin group (P < 0.001). These findings indicated that USP35 could alleviate the inhibitory effect of Erastin on RA-FLS cell viability. (2) In comparison to the shNC+Erastin group, the levels of ROS (P < 0.001), MDA (P < 0.05), and Fe²⁺ (P < 0.001) were significantly elevated, and the GSH/GSSG ratio was increased (P < 0.05) in the shUSP35+Erastin group. Conversely, the levels of ROS (P < 0.001), MDA (P < 0.05), and Fe²⁺ (P < 0.05) were significantly decreased, and the GSH/GSSG ratio was decreased (P < 0.05) in the USP35 OE+Erastin group compared with the Vector+Erastin group. These results suggested that USP35 could inhibit Erastin-induced oxidative stress and lipid peroxidation in RA-FLS. (3) In Erastin-induced RA-FLS, the expression of USP35 was positively correlated with the protein levels of SLC7A11 and GPX4, indicating a potential mechanism by which USP35 regulated ferroptosis in these cells. CONCLUSION USP35 inhibits ferroptosis in RA-FLS, potentially through the increased expression of SLC7A11 and GPX4.
Ferroptosis ; Humans ; Arthritis, Rheumatoid/metabolism* ; Synoviocytes/pathology* ; Reactive Oxygen Species/metabolism* ; Ubiquitin-Specific Proteases/metabolism* ; Fibroblasts/pathology* ; Cell Survival ; Piperazines/pharmacology* ; Endopeptidases/metabolism* ; Cells, Cultured ; Cell Line ; Amino Acid Transport System y+

The prevalence of rheumatoid arthritis (RA) has sharply increased in recent years, posing a serious threat to human health. RA is characterized as a chronic, multisystem disease with morning stiffness and symmetric small joint pain. However, its fundamental processes are poorly understood. With the advancements in molecular biology techniques, a growing body of research indicates that numerous non-coding RNAs (ncRNAs) are essential for the pathogenesis of RA. These ncRNAs not only contribute to the onset of RA but also play a role in the pathological processes of RA development, including synovial immune inflammation and bone destruction. Chinese medicine (single compounds, single herbs, and compound formulae, as well as non-drug therapies such as acupuncture and moxibustion), offer significant benefits for treating RA. This study examined the role of 3 different ncRNA types (circular RNA, long ncRNA, and microRNA) as biomarkers in RA diagnosis, as well as their regulatory roles in rheumatoid arthritis fibroblast-like synoviocytes functions such as inflammatory response, proliferation, cell cycle, apoptosis, and invasion. Additionally, the study explored the mechanisms by which Chinese medicine regulates these ncRNAs, with the goal of offering innovative strategies for RA treatment.
Arthritis, Rheumatoid/pathology* ; Humans ; RNA, Untranslated/metabolism* ; Medicine, Chinese Traditional ; Synoviocytes/metabolism* ; RNA, Circular ; Biomarkers/metabolism* ; Apoptosis/genetics*

OBJECTIVES: To investigate the role of the BNIP3-PI3K/Akt signaling pathway in mediating the inhibitory effect of Buyang Huanwu Decoction (BYHWT) on mitochondrial autophagy in human synovial fibroblasts from rheumatoid arthritis patients (FLS-RA) cultured under a hypoxic condition. METHODS: Forty normal Wistar rats were randomized into two groups (n=20) for daily gavage of BYHWT or distilled water for 7 days to prepare BYHWT-medicated or control sera. FLS-RA were cultured in routine condition or exposed to hypoxia (10% O₂) for 24 h wigh subsequent treatment with IL-1β, followed by treatment with diluted BYHWT-medicated serum (5%, 10% and 20%) or control serum. AnnexinV-APC/7-AAD double staining and T-AOC kit were used for detecting apoptosis and total antioxidant capacity of the cells, and the changes in ROS, ATP level, mitochondrial membrane potential and Ca²⁺ homeostasis were analyzed. The changes in mRNA and protein expressions of BNIP3, PI3K and AKT and mRNA expressions of LC3, Beclin-1 and P62 were detected using RT-qPCR and Western blotting. RESULTS: Treatment with BYHWT-medicated serum dose-dependently lowered apoptosis rate of IL-1β-induced FLS-RA with hypoxic exposure. The treatment significantly decreased T-AOC concentration, increased ROS production, autophagosome formation and ATPase levels, and lowered mitochondrial membrane potential and Ca²⁺ level in the cells. In IL-1β-induced FLS-RA with hypoxic exposure, treatment with BYHWT-medicated serum significantly increased BNIP3 protein expression, decreased the protein expressions of PI3K and AKT, increased the mRNA expressions of BNIP3 and P62, and lowered the mRNA expressions of PI3K, AKT, LC3 and Beclin-1 without significantly affecting Beclin-1 protein expression. The cells treated with 5% and 10% BYHWT-medicated serum showed no significant changes in LC3 expression. CONCLUSIONS BYHWT inhibits mitochondrial autophagy in IL-1β-induced FLS-RA with hypoxic exposure possibly by inhibiting BNIP3-mediated PI3K/AKT signaling pathway.
Drugs, Chinese Herbal/pharmacology* ; Arthritis, Rheumatoid/pathology* ; Animals ; Signal Transduction/drug effects* ; Proto-Oncogene Proteins c-akt/metabolism* ; Autophagy/drug effects* ; Humans ; Fibroblasts/cytology* ; Rats, Wistar ; Membrane Proteins/metabolism* ; Rats ; Phosphatidylinositol 3-Kinases/metabolism* ; Mitochondria/metabolism* ; Cells, Cultured ; Proto-Oncogene Proteins/metabolism* ; Apoptosis/drug effects* ; Cell Hypoxia ; Synovial Membrane/cytology* ; Male ; Mitochondrial Proteins

OBJECTIVES: To investigate the regulatory effect of LINC00837/miR-671-5p/SERPINE2 functional axis on pathological processes of fibroblast-like synovial cells (FLS) in rheumatoid arthritis (RA). METHODS: RA-FLS were transfected with a LINC00837 overexpression plasmid (pcDNA3.1-LINC00837), a LINC00837 interference plasmid (siRNA-LINC00837), or their respective negative control plasmids (pcDNA3.1-NC and siRNA-NC). Dual luciferase was used to verify the targeting relationship between LINC00837 and miR-671-5p and between miR-671-5p and SERPINE2. RT-qPCR was used to detect the expression levels of LINC00837, miR-671-5p and SERPINE2 in normal FLS or the transfected cells, whose proliferation and migration abilities were assessed using Edu assay and scratch healing assay and by detecting the expression levels of Ki-67, PCNA, E-cadherin and N-cadherin with Western blotting. The changes in cellular secretion of the inflammatory cytokines (TNF‑α, IL-17, IL-4 and IL-10) were examined using ELISA. RESULTS: Dual luciferase reporter gene assay showed that LINC00837 was capable of binding to the 3'-UTR of miR-671-5p, and the latter bound to the 3-UTR of SERPINE2 at specific binding sites between them. Compared with normal FLS, RA-FLS showed significantly increased expressions of LINC00837 and SERPINE2, lowered miR-671-5p expression and enhanced proliferation and migration abilities with increased expressions of pro-inflammatory cytokines and reduced expressions of anti-inflammatory cytokines. Transfection of RA-FLS with pcDNA-LINC00837 further enhanced cell proliferation and migration and the changes in the inflammatory cytokines, while transfection with si-LINC00837 produced the opposite changes. CONCLUSIONS RA-FLS have a LINC00837/miR-671-5p/SERPINE2 functional axis, which regulates cell proliferation, migration and secretion of inflammatory factors, and interventions targeting LINC00837 may provide a potential strategy to regulate the pathological processes in RA-FLS.
Arthritis, Rheumatoid/metabolism* ; MicroRNAs/metabolism* ; Humans ; Cell Proliferation ; Cell Movement ; Synovial Membrane/pathology* ; RNA, Long Noncoding/genetics* ; Fibroblasts/metabolism* ; Synoviocytes/metabolism* ; Cells, Cultured ; Transfection

OBJECTIVES: To investigate the effect of Qianggu Kangshu Formula (QGKSF) for alleviating osteoclast differentiation in rheumatoid arthritis and the underlying mechanism. METHODS: RAW264.7 cells cultured under hypoxic conditions were treated with RANKL to induce osteoclast differentiation and incubated with normal rat serum or sera from rats medicated with methotrexate (MTX) or QGKSF at low and high doses. Cell viability, TRAP-positive multinucleated cells and F-actin ring formation in the treated cells were assessed with CCK-8 assay, TRAP staining and Phalloidin staining, respectively. Autophagy and autophagosomes in the cells were observed with MDC staining and transmission electron microscopy. ELISA was used to measure IL-6 and TNF-α levels in the culture supernatant, and the expressions of HIF-1α, BNIP3, Bcl-2, Beclin1, LC3-I, LC3-II, P62 and TRAP mRNAs and proteins were analyzed using RT-qPCR and Western blotting. RESULTS: In hypoxia- and RANKL-induced RAW264.7 cells treated with normal rat serum, significant increments of TRAP-positive cells and F-actin ring formation were observed with an enhanced autophagic fluorescence intensity and increased autophagosomes. Treatment of the induced cells with rat sera medicated with MTX and low- and high-dose QGKSF obviously reduced the TRAP-positive cells, F-actin rings and autophagosomes as well as the autophagic fluorescence intensity. RANKL treatment significantly increased IL-6 and TNF-α levels in RAW264.7 cells, which were obviously decreased by treatment with MTX- and QGKSF-medicated sera. RANKL also significantly increased the mRNA and protein expression levels of HIF-1α, BNIP3, Bcl-2, Beclin1, LC3 and TRAP and lowered P62 expressions, and these changes were effectively reversed by treatment with MTX- and QGKSF-medicated sera. CONCLUSIONS QGKSF attenuates RANKL-induced osteoclast differentiation in hypoxic RAW264.7 cells by inhibiting the HIF-1α/BNIP3 autophagy signaling pathway, suggesting its potential for treatment of bone destruction in rheumatoid arthritis.
Animals ; Drugs, Chinese Herbal/pharmacology* ; Osteoclasts/drug effects* ; Autophagy/drug effects* ; Mice ; Signal Transduction/drug effects* ; Rats ; Cell Differentiation/drug effects* ; Arthritis, Rheumatoid/pathology* ; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism* ; RAW 264.7 Cells ; Membrane Proteins/metabolism* ; Mitochondrial Proteins

Cellular immune responses as well as generalized and periarticular bone loss are the key pathogenic features of rheumatoid arthritis (RA). Under the pathological conditions of RA, dysregulated inflammation and immune processes tightly interact with skeletal system, resulting in pathological bone damage via inhibition of bone formation or induction of bone resorption. Single-cell omics technologies are revolutionary tools in the field of modern biological research.They enable the display of the state and function of cells in various environments from a single-cell resolution, thus making it conducive to identify the dysregulated molecular mechanisms of bone destruction in RA as well as the discovery of potential therapeutic targets and biomarkers. Here, we summarize the latest findings of single-cell omics technologies in osteoimmunology research in RA. These results suggest that single-cell omics have made significant contributions to transcriptomics and dynamics of specific cells involved in bone remodeling, providing a new direction for our understanding of cellular heterogeneity in the study of osteoimmunology in RA.
Humans ; Osteoclasts/physiology* ; Arthritis, Rheumatoid/pathology* ; Inflammation/pathology* ; Bone and Bones/pathology* ; Bone Resorption/pathology*

Interleukin (IL)-36 is a family of cytokines that belongs to the larger IL-1 superfamily. IL-36 agonist/antagonist binds to the interleukin-36 receptor involving in physiological inflammation regulation and pathogenesis of many inflammatory diseases. In inflammatory joint diseases, the expression of IL-36 changes, and some studies have initially explored the role of IL-36 in these diseases. In psoriatic arthritis, IL-36 signal mediates plasma cell and fibroblast-like synoviocyte crosstalk presenting IL-36 agonist/antagonist imbalance. In rheumatoid arthritis, IL-36 agonists induce fibroblast-like synoviocyte to produce pro-inflammatory factors, while IL-36 antagonist deficiency leads to lesion progression. In osteoarthritis, IL-36 agonists induce chondrocytes to produce catabolic enzymes and pro-inflammatory factors. This article reviews the expression and function of IL-36 in different inflammatory joint diseases to provide a reference for revealing their pathogenic mechanisms and discovering therapeutic targets.
Humans ; Interleukins ; Arthritis, Rheumatoid ; Osteoarthritis/pathology* ; Arthritis, Psoriatic/metabolism* ; Cytokines

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease caused by inflammatory cells. Various inflammatory cells involved in RA include fibroblast-like synoviocytes, macrophages, CD4⁺T-lymphocytes, B lymphocytes, osteoclasts and chondrocytes. The close interaction between various inflammatory cells leads to imbalance of immune response and disorder of the expression of mRNA in inflammatory cells. It helps to drive production of pro-inflammatory cytokines and stimulate specific antigen-specific T- and B-lymphocytes to produce autoantibodies which is an important pathogenic factor for RA. Competing endogenous RNA (ceRNA) can regulate the expression of mRNA by competitively binding to miRNA. The related ceRNA network is a new regulatory mechanism for RNA interaction. It has been found to be involved in the regulation of abnormal biological processes such as proliferation, apoptosis, invasion and release of inflammatory factors of RA inflammatory cells. Understanding the ceRNA network in 6 kinds of RA common inflammatory cells provides a new idea for further elucidating the pathogenesis of RA, and provides a theoretical basis for the discovery of new biomarkers and effective therapeutic targets.
Humans ; Arthritis, Rheumatoid/genetics* ; MicroRNAs/metabolism* ; Synoviocytes/pathology* ; Cytokines/metabolism* ; RNA, Messenger/metabolism* ; Fibroblasts/pathology* ; Cell Proliferation

OBJECTIVE: To investigate the therapeutic mechanism of emodin in the treatment of rheumatoid arthritis (RA) using a network pharmacology-based method and validate this mechanism in a fibroblast-like synovial cell line. METHODS: The PubChem, Targetnet, SwissTargetPrediction, Genecards, OMIM, and DisGeNET databases were searched to obtain emodin targets and RA-related genes. A protein-protein interaction (PPI) network was constructed, and GO and KEGG pathway enrichment analyses were carried out to analyze the intersection genes. AutoDock4.2.6 software was used to simulate molecular docking between emodin and its candidate targets. In a cultured fibroblast-like synovial cell line (MH7A), the effects of different concentrations of emodin on proliferation of tumor necrosis factor-α (TNF-α)-induced cells were investigated using CCK-8 assay, cell scratch experiment and flow cytometry; the changes in the expressions of nuclear factor-κB (NF-κB) pathway proteins were detected using Western blotting, and the mRNA expressions of the hub genes were examined with RT-qPCR. RESULTS: We identified 32 intersection genes of emodin and RA, and the key targets including CAPS3, ESR1, and MAPK14 involved mainly the NF-κB signaling pathway. Cell scratch experiment and flow cytometry demonstrated a strong inhibitory effect of emodin on MH7A cell proliferation. Treatment with TNF-α significantly increased the cellular expressions of the NF-κB pathway proteins, which were obviously lowered by treatment with 80 μmol/L emodin. The results of RT-qPCR showed that TNF-α treatment obviously up-regulated the expressions of the hub genes COX2 and P38MAPK, and emodin treatment significantly down-regulated the expressions of MAPK and PTGS2 and up-regulated the expression of CASP3. CONCLUSION The therapeutic effect of emodin on RA is mediated mainly through regulation of cell proliferation, apoptosis, and the NF-κB pathway.
Arthritis, Rheumatoid/pathology* ; Emodin/pharmacology* ; Humans ; Molecular Docking Simulation ; NF-kappa B/metabolism* ; Network Pharmacology ; Tumor Necrosis Factor-alpha/pharmacology*