Fibroblast-activated protein-α (FAP) is a type II integrated serine protease expressed by activated fibroblasts during fibrosis or inflammation. Fibroblast-like synoviocytes (FLSs) in rheumatoid arthritis (RA) synovial sites abundantly and stably overexpress FAP and play important roles in regulating the cellular immune, inflammatory, invasion, migration, proliferation, and angiogenesis responses in the synovial region. Overexpression of FAP is regulated by the initial inflammatory microenvironment of the disease and epigenetic signaling, which promotes RA development by regulating FLSs or affecting the signaling cross-linking FLSs with other cells at the local synovium and inflammatory stimulation. At present, several treatment options targeting FAP are in the process of development. This review discusses the basic features of FAP expressed on the surface of FLSs and its role in RA pathophysiology and advances in targeted therapies.

Introduction Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that may lead to bone erosion and disability. Although there are many biological therapies in RA treatment nowadays, such as etanercept and tofacitinib, there are still a considerable number of patients who cannot achieve clinical deep remission, which makes patients feel pain and stiffness of joints. As a traditional Chinese medicine preparation, Wangbi granule showed a synergistic role with methotrexate in the treatment of RA patients with “kidney deficiency and dampness” or “stasis blocking channels”. Therefore, it is a promising therapeutic strategy for the clinical deep remission of RA. In this study, Wangbi granule will be used as the test drug. The investigators conduct this study to evaluate the efficacy and safety of Wangbi granule in the treatment of patients who have not achieved deep remission despite the use of methotrexate and tofacitinib. Methods and analysis Two parallel randomized, triple-blind, placebo-controlled trials will be conducted. In six study centers, 340 eligible RA patients will be recruited and randomly allocated to either the intervention group or the control group (in a 1:1 ratio). They will receive Wangbi granule or Wangbi placebo 12.0 g each time, three times a day for 12 weeks. The primary outcome is the disease activity score derivative for 28 joints (DAS28). Secondary outcomes are patient-reported outcomes, American College of Rheumatology 50% response criteria (ACR50), fatigue scale-14 (FS-14), visual analogue scale for pain (VAS), health assessment questionnaire disability index (HAQ-DI) and biomarkers such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Expected outcomes The success of this study will provide strong evidence to confirm the efficacy and safety of Wangbi granule in the treatment of RA. Trial registration The trial has been registered in the ClinicalTrials Registry (NCT05540938, Date: 09/15/2022, https://clinicaltrials.gov/ct2/show/NCT05540938)

Objective To investigate the correlation between the triglyceride-glucose (TyG) index and rheumatoid factor levels and the existence of cardiovascular disease in patients in the rheumatoid arthritis population and to analyze their potential value in predicting the risk of cardiovascular disease. Methods Patients with rheumatoid arthritis treated by the Traditional Chinese Medicine Department of Rheumatism of the China-Japan Friendship Hospital from 2019–01 to 2021–12 were included in this retrospective study. Regression analysis was performed with multifactor-corrected multimodal logistic models to observe the correlation between the TyG index and rheumatoid factor and cardiovascular disease risk, construct predictive models and assess the potential predictive value of the variables on cardiovascular disease risk with receiver operating characteristic curves. The results were further corrected by sensitivity analysis and trend tests. Results A total of 418 patients with rheumatoid arthritis were included in the study. In the rheumatoid arthritis population, high rheumatoid factor (OR = 1.002, 95% CI = 1.001–1.002, P < 0.001), high TyG index (OR = 1.057, 95% CI = 1.008–1.109, P = 0.022), advanced age (OR = 1.080, 95% CI = 1.050–1.112, P < 0.001), and low physical activity (OR = 2.848, 95% CI = 1.195–6.785, P = 0.018) were independent risk factors for the existence of cardiovascular disease in patients. The combined coefficient calculated on the basis of the TyG index and rheumatoid factor was used to plot the receiver operating characteristic curve with an area under the curve of 0.791, which can be used to predict the potential risk of cardiovascular disease in patients with rheumatoid arthritis. Further sensitivity analysis found that the marker of focus remained associated with cardiovascular disease risk in a high-physical activity population with rheumatoid arthritis. The final trend test found a linear trend between the TyG index, rheumatoid factor levels and the risk of cardiovascular disease. Conclusion In the rheumatoid arthritis population, the TyG index and rheumatoid factor have some potential predictive value in determining the risk of cardiovascular disease, and the predictive efficacy is better when the two tests are combined.