D-hormone and the immune system.

D-hormone [1,25(OH)2 D3] is an important immune system regulator that has been shown to inhibit development of autoimmune diseases including experimental inflammatory bowel disease (IBD), rheumatoid arthritis (RA), multiple sclerosis (MS), and type 1 diabetes. Paradoxically, other immune mediated diseases (experimental asthma) and immunity to infectious organisms were not found to be affected by D-hormone treatment. The effectiveness of D-hormone treatment of autoimmune diseases is due to inhibition of the development and function of Th1 cells and the induction of other Th cells including Th2 cells. We report results of microarray analysis of colons from D-hormone treated mice with experimental IBD. Two hundred thirty-nine genes were inhibited and 298 genes were upregulated in the colon by D-hormone treatment of mice with IBD. Of interest was the D-hormone mediated inhibition of 3 tumor necrosis factor-alpha (TNF-alpha, lipopolysaccharide-induced TNF-alpha factor, and TNF receptor) related genes in the colon. It is likely that the effectiveness of D-hormone treatment of experimental autoimmunity is due in part to the inhibition of the TNF family of genes. D-hormone is a selective regulator of the immune system, and the outcome of D-hormone treatment depends on the nature (infectious disease, asthma, autoimmune disease, etc.) of the immune response.