Background Autoimmune thyroid disease (AITD) mainly includes Graves’ disease (GD) and Hashimoto's thyroiditis (HT), which is caused by individual genetics, autoimmune dysfunction, and a variety of external environmental factors. Interleukin (IL)‐38 is involved in a wide range of autoimmune diseases, but little is known about IL‐38 expression in AITD. Methods Fifty patients with GD, 50 with HT, and 50 healthy controls (HC) were enrolled in this study. Basic information of the participants was obtained through a physical examination. Immunological data were obtained by an automatic chemiluminescence immunoanalyzer. C‐reactive protein (CRP) concentrations and the white blood cell count were measured. Serum IL‐38 levels were determined by an enzyme‐linked immunosorbent assay. Results Serum IL‐38 levels were significantly lower in the GD and HT groups than in the HC group (both p < 0.01). Serum CRP concentrations were significantly lower in the HT group than in the HC group (p < 0.05). Receiver operating characteristic curve analysis showed that the area under the curve was 0.7736 (p < 0.01) for IL‐38 and 0.7972 (p < 0.01) for IL‐38 combined with CRP in the GD group. In the HT group, the area under the curve was 0.7276 (p < 0.01) for IL‐38 and 0.7300 for IL‐38 combined with CRP (p < 0.01). Conclusions The results suggest that serum IL‐38 level is a potential new diagnostic biomarker in patients with GD and HT.

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Autoimmune thyroid disease (AITD) is a family of classic autoimmune disorders that mainly consists of Hashimoto's thyroiditis (HT) and Graves' disease (GD). 1 The global prevalence of HT is estimated at 2%. 2 A significant sign of HT is loss of self-tolerance to thyroid antigens. 3 HT is characterized by infiltration of thyroid lymphocytes, circulating thyroid autoantibodies, and apoptosis of thyroid cells leading to the destruction of follicles. 3,4 GD is an organ-specific thyroid autoimmune disease with anti-thyroid stimulating hormone (TSH) receptor (TSH-R) autoantibodies in circulation that can cause hyperthyroidism. Lack of immune tolerance to thyroid antigens, especially TSH-R, is the cause of GD. 5 It is estimated that the incidence of AITD in women is significantly higher than that in men. The prevalence of AITD is 2% in women and 0.2% in men. AITD is most common in adults aged 30-50, and the disease occurrence increases with age. 6,7 Cytokines play a crucial role in the induction and action stages of immune and inflammatory responses. Imbalances between preand anti-inflammatory cytokines may play an important role in the occurrence and development of AITD. Several cytokines, including interleukin (IL)-17, IL-23, IL-28, and IL-29, have been implicated in the pathogenesis of HT. [8][9][10][11][12][13][14] Additionally, IL-6, IL-21, IL-23, and IL-37 are all involved in the occurrence of GD. [15][16][17][18][19] IL-12 family plays a key role in immune responses through their functional, unique structural, and immunological characteristics. 20 IL-12, IL-23, IL-27, IL-35, and the recently discovered IL-39 comprise the IL-12 cytokine family. 21 Wang et al. 22,23 first reported that IL-39 is

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.

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