Targeting mitochondrial fission-autophagy axis in rheumatoid arthritis: leflunomide promote apoptosis of fibroblast-like synoviocytes.

Histamine releasing factor/translationally controlled tumor protein (HRF/TCTP) stimulates cancer progression and allergic responses, but the role of HRF/TCTP in rheumatoid arthritis (RA) remains undefined. In this study, we explored the pathogenic significance of HRF/TCTP and evaluated the therapeutic effects of HRF/TCTP blockade in RA. HRF/TCTP transgenic (TG) and knockdown (KD) mice with collagen-induced arthritis (CIA) were used to determine the experimental phenotypes of RA. HRF/TCTP levels in the sera of RA patients were measured and compared to those from patients with osteoarthritis (OA), ankylosing spondylitis, Behçet’s disease, and healthy controls. HRF/TCTP expression was also assessed in the synovium and fibroblast-like synoviocytes (FLSs) obtained from RA or OA patients. Finally, we assessed the effects of HRF/TCTP and dimerized HRF/TCTP-binding peptide-2 (dTBP2), an HRF/TCTP inhibitor, in RA-FLSs and CIA mice. Our clinical, radiological, histological, and biochemical analyses indicate that inflammatory responses and joint destruction were increased in HRF/TCTP TG mice and decreased in KD mice compared to wild-type littermates. HRF/TCTP levels in the sera, synovial fluid, synovium, and FLSs were higher in patients with RA than in control groups. Serum levels of HRF/TCTP correlated well with RA disease activity. The tumor-like aggressiveness of RA-FLSs was exacerbated by HRF/TCTP stimulation and ameliorated by dTBP2 treatment. dTBP2 exerted protective and therapeutic effects in CIA mice and had no detrimental effects in a murine tuberculosis model. Our results indicate that HRF/TCTP is a novel biomarker and therapeutic target for the diagnosis and treatment of RA.

Background: Aralia echinocaulis has therapeutic effects on rheumatoid arthritis (RA), with total polysaccharide and glycoside (TPGs) as main active components. RA pathogenesis involves gut microbiota dysbiosis and immune-metabolic crosstalk, but the role of microbiota-derived succinate in RA remains unclear. Objective: This study explored the role of succinate-GPR91 signaling in intestinal dendritic cells (DCs) in the context of RA and the therapeutic mechanism of A. echinocaulis TPGs. Methods: Collagen-induced arthritis (CIA) mice were treated with TPGs or exogenous succinate. Paw edema, inflammation, gut succinate levels, the Th17/regulatory T (Treg) balance, and DC activation via succinate-GPR91 were detected, and GPR91-targeting siRNA and CD4+ T-cell coculture assays for verification. Results: TPGs alleviated symptoms in CIA mice and restored the Th17/Treg balance by reducing intestinal succinate levels. Succinate activated DCs via GPR91 to promote Th17 differentiation, while TPGs suppressed DC maturation and Th17-driven inflammation, supporting the involvement of a gut-centric immunometabolic axis in RA. Conclusions: TPGs ameliorate RA by targeting the succinate-GPR91-Th17 pathway, identifying succinate as a novel RA target and TPGs as a potential microbiota-modulating agent.

Fibroblast-like synoviocytes (FLS) contribute significantly to the pathogenesis of rheumatoid arthritis (RA), particularly through their roles in synovitis and joint destruction. The microRNAs (miRNAs) are short non-coding RNA that regulate gene expression post-transcriptionally. Although more than 2000 human miRNAs are registered, comprehensive analyses of miRNA expression in FLS are limited. Herein, we investigated the relationship between miRNAs and FLS. Next-generation sequencing (small RNA-seq) was performed on primary cultured FLS derived from patients with RA to analyze the mature miRNA expression pattern. To assess inflammation-induced changes in miRNA levels, FLS were cultured with cytokines and evaluated by RT-qPCR. MiRNA mimics were transfected into FLS and an immortalized synovial fibroblast cell line (MH7A cells), and validated using conventional RNA-seq. Out of 2861 mature miRNAs, 297 mature miRNAs were detected and intronic miRNAs were predominated. Notably, hsa-miR-21-5p was abundantly expressed and its expression was enhanced by IL-6 stimulation. The induction of miR-21-5p mimic decreased the expression of Programmed Cell Death 4 (PDCD4) and Osteoprotegerin (OPG), while upregulating Semaphorin 5A (SEMA5A). MiR-21-5p mimic led to enhanced cell proliferation. These data suggest that hsa-miR-21-5p in FLS may exacerbate the pathophysiology of rheumatoid synovitis by promoting FLS proliferation, highlighting its potential as a therapeutic target in RA.

Objective To clarify the role of glucocerebrosidase (GBA) and Ceramide (Cer) in rheumatoid arthritis (RA). Methods GBA-expressing lentivirus were constructed and injected into collagen-induced arthritis (CIA) mice, and compared with CIA mice injected with empty vector. The severity of arthritis and inflammatory mediators were evaluated. Fibroblast-like synoviocytes (FLS) from RA patients were transfected with GBA-expressing lentivirus, or pretreated with C6-Cer. The migration and invasion of FLS, the production of inflammatory cytokines, and the relevant signaling pathways were assessed. Results In CIA mice, GBA markedly improved arthritis compared to that in the CIA mice, with increased content of proteoglycan and integral cartilage surfaces and tidemarks. The circulating inflammatory mediators, including interleukin (IL)-1β, IL-6, IL-18, and matrix metalloproteinase (MMP)-1, were significantly reduced in CIA mice with GBA overexpression compared to those in CIA mice. GBA and C6-Cer treatment inhibited migration and invasion of FLS, and suppressed production of inflammatory cytokines and activation of the MAPK pathways. Conclusion GBA/Cer exhibited a protective role in CIA mice and RA FLS. These results highlight the potential of targeting GBA/Cer as a therapeutic strategy in RA and warrant further investigation.

Isorhapontigenin suppresses inflammation, proliferation and aggressiveness of rheumatoid arthritis fibroblast-like synoviocytes by targeting farnesyl diphosphate synthase.

Chitosan/siRNA Nanoparticle–mediated TNF-α Knockdown in Peritoneal Macrophages for Anti-inflammatory Treatment in a Murine Arthritis Model

Schisandrin treatment suppresses the proliferation, migration, invasion, and inflammatory responses of fibroblast-like synoviocytes from rheumatoid arthritis patients and attenuates synovial inflammation and joint destruction in CIA mice.

We aimed to define the importance of transient receptor potential canonical 6 (TRPC6) expression and function in fibroblast-like synoviocytes (FLSs) and to investigate the contribution of TRPC6 in the model of rheumatoid arthritis (RA). We compared TRPC6 expression levels in FLSs from RA patients (RA-FLSs), and in FLSs from osteoarthritis (OA) patients (OA-FLSs). By using vitro functional assays which united with small interfering RNA-induced knockdown and functional modulation of TRPC6 in RA-FLSs. Finally, we confirmed the effectiveness of regulating TRPC6 in a collagen induced arthritis (CIA) mice model. We found that FLSs expressed the TRPC6 as their major Transient receptor potential canonical channel. Both mRNA and protein expression of TRPC6 were found somewhat higher levels in RA-FLSs than in OA-FLSs. Moreover, inhibiting expression of TRPC6 in vitro reduced proliferation of, as well as inflammatory mediator and protease production by, RA-FLSs, whereas opening native TRPC6 enhanced both proliferation and inflammatory mediator of RA-FLSs. Additionally, a TRPC6 deficiency in mice blunted the development of experimental RA, CIA models, reduced joint and bone damage, and inhibited FLS invasiveness and proliferation. Our results demonstrated a critical role of TRPC6 in regulating FLSs mediated inflammation. Therefore, TRPC6 represents potential therapeutic targets in RA.

SAT0007 BLOCKING HISTAMINE-RELEASING FACTOR/TRANSLATIONALLY CONTROLLED TUMOR PROTEIN (HRF/TCTP) ATTENUATES AGGRESSIVENESS OF FIBROBLAST-LIKE SYNOVIOCYTES AND AMELIORATES COLLAGEN-INDUCED ARTHRITIS IN RHEUMATOID ARTHRITIS

Guizhi Shaoyao Zhimu Decoction alleviates rheumatoid arthritis by inhibiting inflammation by targeting SLPI.

The role of liver X receptors (LXR) in rheumatoid arthritis (RA) remains controversial. We studied the effect of LXR agonists on fibroblast-like synoviocytes (FLS) from RA patients and the K/BxN arthritis model in LXRα and β double-deficient (Nr1h2/3-/-) mice. Two synthetic LXR agonists, GW3965 and T0901317, were used to activate LXRs and investigate their effects on cell growth, proliferation and matrix metalloproteinases, and chemokine production in cultured FLS from RA patients. The murine model K/BxN serum transfer of inflammatory arthritis in Nr1h2/3-/- animals was used to investigate the role of LXRs on joint inflammation in vivo. LXR agonists inhibited the FLS proliferative capacity in response to TNF, the chemokine-induced migration, the collagenase activity in FLS supernatant and FLS CXCL12 production. In the K/BxN mouse model, Nr1h2/3-/- animals showed aggravated arthritis, histological inflammation, and joint destruction, as well as an increase in synovial metalloproteases and expression of proinflammatory mediators such as IL-1β and CCL2 in joints compared with wild type animals. Taken together, these data underscore the importance of LXRs in modulating the joint inflammatory response and highlight them as potential therapeutic targets in RA.

The aberrant expression of omentin-1 had been reported in type 2 diabetes and cardiovascular disease. Here, we investigated the expression and role of omentin-1 in rheumatoid arthritis (RA). The expression of omentin-1 in RA and in the normal population was detected by ELISA and immunohistochemistry, and collagen-induced arthritis (CIA) mice were used to detect the role of omentin-1 in RA. We found that the expression of omentin-1 was elevated in serum of RA patients compared with healthy controls (p=0.004), and in the RA disease activity group compared with the disease remission group (p<0.001). In addition, the level of omentin-1 in RA patients was positively correlated with CRP (r=0.427, p=0.002), ESR (r=0.454, p<0.001) and DAS28 (r=0.496, p<0.001; r=0.661, p<0.001, respectively). Multivariable analysis showed that omentin-1 alone was associated with disease activity state (OR=1.018, p=0.004). Immunohistochemical results showed that omentin-1 was increased in the synovium of RA and CIA mice. Omentin-1 injection resulted in an earlier onset of arthritis, an aggravated arthritic progression, more severe synovial hyperplasia and bone erosion in CIA mice. Moreover, omentin-1 treatment markedly enhanced IL-6, TNF-α, MMP-3, MMP-13 and RANKL in the joint tissue of CIA mice. Our results suggested that omentin-1 was up-regulated in RA and can exacerbate synovitis and joint destruction which may provide new insight into the pathogenesis of RA.

Quercetin-mediated SIRT1 activation attenuates collagen-induced mice arthritis

Anacardic acid suppresses fibroblast-like synoviocyte proliferation and invasion and ameliorates collagen-induced arthritis in a mouse model

Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes mild to severe joint inflammation. During RA pathogenesis, fibroblast-like synoviocytes (FLS) acquire a tumor-like phenotype and mediate cartilage destruction both directly and indirectly by producing proinflammatory cytokines and matrix metalloproteinases (MMPs). Kruppel-like factor (KLF) 4, a member of the KLF family, plays significant roles in cell survival, proliferation, and differentiation. A recent study reported increased expression of KLF4 in synovial tissue from RA patients. However, its precise role in RA in different models, including mouse autoimmune disease models, remains unclear. In this study, we examined the role of KLF4 during development of autoimmune arthritis in mouse models. To do this, we used KLF4 knockout mice rendered by ribonucleic acid (RNA)-guided endonuclease (RGEN) and performed collagen antibody-induced arthritis (CAIA). We found that deletion of KLF4 reduces inflammation induced by CAIA. In addition, we assessed collagen-induced arthritis (CIA) in control mice and KLF4-overexpressing mice generated by a minicircle vector treatment. Severity of CIA in mice overexpressing KLF4 was greater than that in mice injected with control vector. Finally, we verified the inflammatory roles of KLF4 in CIA by treating Kenpaullone which is used as KLF4 inhibitor. Next, we focused on human/mouse FLS to discover the cellular process involved in RA pathogenesis including proliferation, apoptosis, and inflammation including MMPs. In FLS, KLF4 upregulated expression of mRNA encoding proinflammatory cytokines interleukin (IL)-1β and IL-6. KLF4 also regulated expression of matrix metallopeptidase 13 in the synovium. We found that blockade of KLF4 in FLS increased apoptosis and suppressed proliferation followed by downregulation of antiapoptotic factor BCL2. Our results indicate that KLF4 plays a crucial role in pathogenesis of inflammatory arthritis in vivo, by regulating apoptosis, MMP expression, and cytokine expression by FLS. Thus, KLF4 might be a novel transcription factor for generating RA by modulating cellular process of FLS.