Decreased serum interleukin-41/Metrnl levels in patients with Graves' disease.

Background: Interleukin (IL)-41, also known as Metrnl, is a novel immunomodulatory cytokine, which is involved in the pathogenesis of many inflammatory and metabolic diseases, but its role in thyroid autoimmune diseases is not clear. The aim of this study was to evaluate the serum IL-41 levels in patients with Graves' disease (GD) and its relationship with GD.

Methods: This study included a total of 49 GD patients and 47 age- and sex-matched healthy individuals. All baseline data were obtained by physical examination. Free triiodothyronine 3 (FT3), free triiodothyronine 4 (FT4), thyroid-stimulating hormone (TSH), anti-thyroglobulin antibodies (TgAb), thyroid peroxidase antibody (TPOAb), and thyrotropin receptor antibody (TRAb) levels in plasma of GD patients were measured by chemiluminescence. The high-sensitivity C-reactive protein (CRP) and white blood cell count (WBC) were detected using automated biochemical analyzer. Serum IL-41 levels were measured by enzyme-linked immunosorbent assay.

Results: Serum IL-41 levels in patients with GD were significantly lower than those in healthy controls (201.0 vs. 260.8 pg/mL, p < 0.05). There was a significant positive correlation between IL-41 level and CRP (r = 0.2947, p = 0.0385) and WBC (r = 0.4104, p = 0.0034) in GD patients. CRP was positively correlated with TRAb (r = 0.2874, p = 0.0452) and TSH (r = 0.3651, p = 0.0099) levels in GD patients.

Conclusions: This study demonstrates that GD patients have decreased serum IL-41 levels, and IL-41 plays a potential role in abnormal immune response of GD patients.