Gal-3 is required for optimal toll-like receptor (TLR)-4-dependent activation of indoleamine 2,3-dioxygenase-1/kynurenine (IDO-1/KYN) pathway in DCs which promotes expansion of colon-infiltrated T regulatory cells (Tregs), and therefore, suppresses Th1 and Th17 cell-driven chronic colitis. This evidence concerns the gene IDO1 and Chronic colitis.