OBJECTIVETo observe the effect of 1,25(OH)2D3 on thyroid inflammation and Th1/Th2 cells in rats with experimental autoimmune thyroiditis (EAT).

METHODSForty-eight female Wistar rats were randomly divided into 4 groups, namely the prevention group treated with 1, 25-(OH)2D3 from 0 to the 6th week (n=10), treatment group with 1,25(OH)2D3 treatment from the 2nd to the 8th week (n=10) after immune sensitization, positive control group (n=12) and the negative control group (n=16). All the rats were challenged with porcine thyroglobulin for immune sensitization until the 6th or 8th week except for those in the negative control group. In the prevention group and treatment group, the rats received 1,25(OH)2D3 at 5 microg/kg by intraperitoneal injection every other day, while those in the positive and negative control groups were given peanut oil instead. The thyroid pathologies, serum autoantibody level and cytokine levels were examined after the treatments.

RESULTSThe thyroid gland remained structurally intact in the negative control group. In the positive control group, the thyroid showed obvious inflammatory change with structural disruption and even disappearance of the thyroid follicle. The structure of the thyroid gland follicles was intact in the prevention group and treatment group. No significant differences were found in the autoantibody and cytokine levels between the prevention group and negative control group (P>0.05). Compared with the positive control groups, the autoantibody and IFN-gamma and IL-12 levels decreased significantly in the treatment group, but the levels of IL-4 and IL-10 were markedly increased (P<0.05).

CONCLUSION1,25(OH)2D3 given before the establishment of the EAT model helps maintain structural integrity of the thyroid gland and normal levels of the antibodies and cytokines in rats. 1,25(OH)2D3 can ameliorate the pathological changes of the thyroid gland and correct the cytokine disequilibrium in rats with EAT.