IDO2 and rheumatoid arthritis: Ameliorate RA symptoms↓ Histological scores in arthritic mice, as well as reduces IgG2a antibodiesSuppress T cell proliferation and relative frequencies of CD4 T cells, CD8 T cells, and B cell subsets↑ The frequency of CD4+-Foxp3+ Treg cells and indoleamine-2,3-dioxygenase expression by CD11b+ dendritic cells, NF-κB, Nrf-2, and heme oxygenase-1