Association of serum IL-21 and vitamin D concentrations in Chinese children with autoimmune thyroid disease.

Abstract Background The etiology of Autoimmune thyroid disease (AITD) in pediatric age is multifactorial and mainly implicated with immune disorder. Previous studies have reported that interleukin-21 (IL-21) and vitamin D play crucial roles in autoimmune diseases. We investigated the correlation between IL-21 and 25(OH)D and their potential role in the pathogenesis of AITD. Methods Total of 54 primary Graves disease (GD) patients, 36 Hashimato's thyroditis (HT) cases and 30 healthy subjects from Anhui Medical University from September through November, 2017 to 2019. The serum concentrations of IL-21, 25(OH)D, thyroid-stimulating hormone (TSH), thyroid peroxidase antibody (TPOAb), antibodies against receptor for TSH (TRAb) and thyroglobulin antibody (TGAb) were determined. Results The serum concentration of 25(OH)D was lower while IL-21 was higher in the GD patients and HT patients than in the control patients. Serum 25(OH)D concentration was negatively correlated with TPOAb and TGAb while serum IL-21 concentration was positively correlated with TPOAb, TGAb and TRAb in the HT group. Moreover, the serum concentration of 25(OH)D had a significant negative correlation with serum IL-21 concentration in the HT and GD children before or after treatment. Therefore, we studied the correlation between IL-21 and 25(OH)D, and infer that they play a role in AITD. Moreover, adding Vitamin D could inhibit the expression concentrations of TPOAb, TGAb and IL-21. Conclusion IL-21 and Vitamin D may be involved in the occurrence and development of AITD. Targeting IL-21 and Vitamin D may be a promising therapeutic approach for AITD in the future.