CD4⁺ T cells in obesity and obesity-associated diseases

Over the past few decades, obesity has been recognized as low-grade chronic inflammatory disease and was contributed to systemic metabolic diseases such as type 2 diabetes (T2D). Accumulating evidence indicates that adipose tissue (AT) inflammation is a key event in the pathogenesis of obesity and obesity-associated diseases. While AT-resident immune cells play important roles in maintaining AT homeostasis, obesity changes their numbers and activities, which were accompanied by the activation of inflammatory responses. Recent investigations emphasized the contributions of adaptive immune cells, especially CD4⁺ T cells, in controlling immune-AT crosstalk in the progression of obesity and obesity-associated disorders. In this review, we focus on the current understandings of the roles of CD4⁺ T cells in obesity and obesity-associated diseases, and the effects of adipocytes as antigen presenting cells on regulating CD4⁺ T cell activity.