Figure 1.

Potential mechanisms by which CD40 regulates obesity and insulin resistance. (A) In adipose tissue, CD40 expression on CD8⁺ T cells suppresses TCR-induced production of cytokines and chemokines, which are critical factors for Mφ recruitment and activation. How CD40 signaling results in T cell hypo-responsiveness is not yet clear. (B) CD40 is required for Th17 cell differentiation, IgA production by B cell and also for Mφ and DC function in vivo, which are important for mucosal immunity. Deficiency of CD40 might impair mucosal immunity and thereby disrupt the homeostasis of gut flora, affecting nutrient metabolism. Mφ, macrophage. DC, dendritic cell.