Objective: Over-proliferation of synovium is a key event of invasive pannus formation and cartilage damage in the progression of RA disease. At the same time, ferroptosis may play a pivotal role in maintaining the balance of proliferation and death of synovium. In this study, we firstly evaluated the ferroptosis level in RA fibroblast-like synoviocytes (FLS) and then explored the role of glycine in ferroptosis. Methods: Ferroptosis was evaluated in RA synovium and FLS. The therapeutic effect of glycine on RA was evaluated by clinical and histopathological score and cytokine level in a CIA mouse model. The influence of glycine on ferroptosis was evaluated by mitochondrial morphology observation and membrane potential assay in RA FLS. Methylase expression was detected to explore the mechanism behind the effect of glycine on glutathione peroxidase 4 (GPX4) methylation. Results: Compared with healthy controls, ferroptosis decreased in the RA synovium and FLS, with a decrease in Acyl Coenzyme A Synthetase Long Chain 4 (ACSL4) and an increase in Ferritin heavy chain 1 (FTH1), GPX4 and cystine/glutamate antiporter solute carrier family 7 member 11 (SLC7A11). Although both oxidation and antioxidation levels of lipids were higher in RA FLS than in healthy controls, the increase in antioxidation was slightly higher than oxidation. RNA-seq and verification showed that glycine regulated the ferroptosis pathway through increase S-adenosylmethionine (SAM) concentration and decrease the expression of GPX4 and FTH1 by promoting SAM-mediated GPX4 promoter methylation and reducing FTH1 expression in RA FLS. Conclusions: In summary, we confirmed a decline in ferroptosis in RA and explored that glycine enhanced ferroptosis via SAM-mediated GPX4 promoter methylation and ferritin decrease.

Regulatory T-cell (Treg)/T-helper 17 (T_h17) cell balance plays an important role in the progression of rheumatoid arthritis (RA). Our study explored the protective effect of protectin DX (PDX), which restored Treg/T_h17 cell balance in RA, and the role of the nucleotide-binding domain (NOD)–like receptor protein 3 (NLRP3) inflammasome pathway in this process. Using mass spectrometry, we discovered that level of PDX decreased in active-RA patients and increased in inactive-RA patients compared with HCs, and serum PDX was a potential biomarker in RA activity detection (area under the curve [AUC] = 0.86). In addition, a collagen-induced arthritis (CIA) mice model was constructed and PDX obviously delayed RA progression in the CIA model, upregulating Tregs and anti-inflammatory cytokines while downregulating T_h17 cells and pro-inflammatory cytokines. Moreover, NLRP3 knockout and rescue experiments demonstrated that NLRP3 participated in PDX-mediated Treg/T_h17 cell balance restoration, joint injury amelioration and inflammatory-response attenuation using Nlrp3^−/− mice. Furthermore, microarray and verified experiments confirmed that PDX reduced NLRP3 expression via miRNA-20a (miR-20a). In summary, we confirmed for the first time that PDX could effectively ameliorate CIA progression by restoring Treg/T_h17 cell balance, which was mediated by inhibition of the NLRP3 inflammasome pathway via miR-20a.

Background: Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by inflammation and joint stiffness, finally leading to tissue destruction. Connective tissue growth factor (CTGF) is a critical factor in RA progression, which promotes fibroblast-like synoviocyte (FLS) proliferation, pannus formation, and the damage of cartilage as well as bone. Resolvin D1 (RvD1) can promote inflammation resolution in acute inflammatory diseases, and recently, effects of RvD1 on chronic inflammatory diseases also attracted attention. This study aimed to examine the effect of RvD1 on pannus formation in RA and the underlying mechanism. Methods: Serum levels of RvD1 and CTGF were determined in RA patients and healthy persons by UPLC-MS/MS and ELISA respectively. The levels of CTGF and inflammatory factors were assessed by qRT-PCR and ELISA. MicroRNA expression profile was determined by miRNA microarray. The effects of CTGF, RvD1, and miR-146a-5p on angiogenesis were evaluated with tube formation and chick chorioallantoic membrane (CAM) assays. Collagen-induced arthritis (CIA) mice were constructed to detect the effects of RvD1 and miR146a-5p on RA. STAT3 activation was determined by Western blotting. Results: RvD1 levels decreased while CTGF levels increased in RA patients’ serum, and an inverse correlation of the concentrations of RvD1 and CTGF in the serum of RA patients was synchronously observed. In CIA mice, RvD1 suppressed angiopoiesis and decreased the expression of CTGF. Simultaneously, RvD1 significantly decreased CTGF and pro-inflammation cytokines levels in RA FLS. Furthermore, CTGF suppressed angiopoiesis and RvD1 inhibited the proliferation and migration of RA FLS and angiopoiesis. MiRNA microarray and qRT-PCR results showed that RvD1 upregulated miRNA-146a-5p. The transfection experiments demonstrated that miRNA-146a-5p could decrease inflammatory factors and CTGF levels. Moreover, miRNA-146a-5p decreased the proliferation of FLS and angiogenesis in vivo. MiRNA-146a-5p also suppressed angiogenesis and downregulated the expression of CTGF in CIA mice. Finally, Western blot results revealed that miRNA-146a-5p inhibited the activation of STAT3. Conclusion: RvD1 is prone to alleviate RA progression through the upregulation of miRNA-146a-5p to suppress the expression of CTGF and inflammatory mediators, thereby decreasing pannus formation and cartilage damage.

Objective: Tofacitinib (TOF) is a Janus kinase (JAK) inhibitor used in the treatment of rheumatoid arthritis (RA), but the mechanism of its action remains unclear. In this study, we investigated the influence of TOF on gamma delta regulatory T-cell (γδTreg)/γδT17 cell balance in RA and the role of the nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3) inflammasome in this process.

Background: The specific function of long noncoding RNAs (lncRNAs) in systemic lupus erythematosus (SLE) and the mechanism of their involvement in related pathological changes remain to be elucidated, so, in this study, we analyzed the differences in the expression profiles of lncRNAs and their mechanisms of action in SLE using full high-throughput sequencing, bioinformatics, etc. methods. Methods: We used high-throughput sequencing to detect differences in the expression profiles of lncRNAs, miRNAs, and mRNAs in PBMCs from patients with SLE at the genome-wide level. Next, we predicted target genes of 30 lincRNAs (long intergenic noncoding RNAs) by constructing a coexpression network of differential lincRNAs and mRNAs and identified the role of lincRNAs. Then, we analyzed the coexpression network of 23 optimized lincRNAs and their corresponding 353 miRNAs, evaluated the cis- and trans-effects of these lincRNAs, and performed GO and KEGG analyses of target genes. We also selected 8 lincRNAs and 2 newly discovered lncRNAs for q-PCR validation and lncRNA–miRNA–mRNA analysis. Finally, we also analyzed respectively the relation between lncRNAs and gender bias in SLE patients using RT-qPCR, the relation between Systemic Lupus Erythematosus Disease Activity Index score and the “IFN signature” using ELISA, and the relation between the differential expression of lncRNAs and a change in the number of a cell type of PBMCs in SLE patients using RT-qPCR. Results: The profiles of 1087 lncRNAs, 102 miRNAs, and 4101 mRNAs in PBMCs significantly differed between patients with SLE and healthy controls. The coexpression network analysis showed that the network contained 23 lincRNAs and 353 mRNAs. The evaluation of the cis- and trans-effects showed that the 23 lincRNAs acted on 704 target genes. GO and KEGG analyses of the target genes predicted the biological functions of the 23 lincRNAs. q-PCR validation showed 7 lincRNAs and 2 novel lncRNAs were identical to the sequencing results. The ceRNA network contained 7 validated lincRNAs, 15 miRNAs, and 155 mRNAs. In addition, the differential expression of lncRNAs may be gender dependent in SLE patients, SLE patients also exhibit a robust “IFN signature,” and PBMCs exhibiting differential expression of lncRNAs may be due to a change in the number of a cell type. Conclusion: This work determined specific lncRNAs that play important biological functions in the pathogenesis of lupus and provided a new direction for diagnosis and treatment of disease.