BTN2A2-Ig protein inhibits the differentiation of pathogenic Th17 cells and attenuates EAE in mice

Pathogenic Th17 cells play a key role in the pathogenesis of many autoimmune diseases. Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS). Experimental autoimmune encephalomyelitis (EAE) is the commonly used animal model for human MS and is characterized by autoreactive CD4⁺T cells attacking autoantigens in the CNS and causing myelin sheath damage. Although the recombinant BTN2A2-IgG2aFc (BTN2A2-Ig) fusion protein has been shown to inhibit T cell functions in vitro, it's unclear whether BTN2A2-Ig affects pathogenic Th17 cells and EAE development. We show here that BTN2A2-Ig protein attenuates established EAE, as compared with control Ig protein treatment. This is associated with reduced activation and proliferation of T cells in BTN2A2-Ig-treated EAE mice. Furthermore, BTN2A2-Ig protein inhibits the differentiation of CD4 naïve T cells into pathogenic Th17 cells and reduces the expression levels of Th1/Th17 cytokines and the Th1/Th17 pathway related genes and proteins but increases the expression levels of Th2-related genes and proteins. Our studies not only provide new insights into the mechanisms by which BTN2A2-Ig affects T cells, but also have the potential to provide a new strategy to treat MS and other autoimmune diseases.