Serum IL-35 is decreased in overweight patients with rheumatoid arthritis: its correlation with Th1/Th2/Th17-related cytokines

BACKGROUND: Obesity is correlated with worse drug responses and high disease activity in patients with rheumatoid arthritis (RA). Interleukin (IL)-35 is a novel anti-inflammatory cytokine that mainly produced by regulatory T (Treg). This study was performed to analyze whether IL-35 was correlated with obesity in RA and investigate the correlation between other Th1/Th2/Th17-related cytokines and obesity in RA. RESULTS: The serum IL-35 level was analyzed in RA (n = 81) and healthy donors (n = 53) by ELISA assay, and was compared between three groups (body mass index (BMI) < 18.5,≥18.5 to 25, > 25). Serum cytokines including IL-2, IL-4, IL-10, IL-17, INF-γ, TNF-α levels were measured using Flowcytometry assay. Clinical information was extracted from medical records. Serum IL-35 level in overweight patients were significantly decreased than those in lean patients. Furthermore, Th1/Th2/Th17-related cytokines from overweight patients with RA showed the characteristic immunological features. Serum IL-6, IL-17 and TNF-α levels were positively correlated with BMI. However, serum IL-2, IL-4, IL-10 and IFN-γ concentrations were not correlated with BMI. CONCLUSIONS: Quantitative changes in serum IL-35 level were characteristic in overweight patients with RA. These findings indicate that IL-35 plays an important role in the development of RA and may prove to be a potential biomarker of active RA. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12865-021-00431-x.