The Deficiency of Indoleamine 2,3-Dioxygenase Aggravates the CCl4-Induced Liver Fibrosis in Mice

In the present study, we examined the role of indoleamine 2, 3-dioxygenase (IDO) in the development of CCl4 -induced hepatic fibrosis. The liver fibrosis induced by repetitive administration with CCl4 was aggravated in IDO-KO mice compared to WT mice. In IDO-KO mice treated with CCl4 , the number of several inflammatory cells and the expression of proinflammatory cytokines increased in the liver. In the results, activated hepatic stellate cells (HSCs) and fibrogenic factors on HSCs increased after repetitive CCl4 administration in IDO-KO mice compared to WT mice. Moreover, the treatment with L-tryptophan aggravated the CCl4 -induced hepatic fibrosis in WT mice. Our findings demonstrated that the IDO deficiency enhanced the inflammation in the liver and aggravated liver fibrosis in repetitive CCl4 -treated mice.