Figure 4.
Schematic representation of amelioration of CIA in C57BL/6 mice by engineered bacteria. The illustration depicts the process of amelioration of CIA in C57BL/6 mice by the engineered BmΔvjbR::tnaA bacterial strain. C57BL/6 mice may harbor a microbiome deficient in production of the metabolite indole. When challenged with the CIA, these mice rapidly develop arthritis due to dysfunctional Tregs and rapid expansion of CD4+ effector T cells. However, when BmΔvjbR::tnaA bacteria are administered to mice bearing CIA, the Treg activity is substantially increased and the pathogenic activity of CD4+ effector T cells is compromised, which results in amelioration of joint inflammation and improved symptoms. This activity is greatly augmented by an ACT of Tregs.