Monocarboxylate transporter 1 deficiency impacts CD8⁺ T lymphocytes proliferation and recruitment to adipose tissue during obesity

Lactate sits at the crossroad of metabolism, immunity, and inflammation. The expression of cellular lactate transporter MCT1 (known as Slc16a1) increases during immune cell activation to cope with the metabolic reprogramming. We investigated the impact of MCT1 deficiency on CD8⁺ T cell function during obesity-related inflammatory conditions. The absence of MCT1 impaired CD8⁺ T cell proliferation with a shift of ATP production to mitochondrial oxidative phosphorylation. In Slc16a1^f/fTcell^cre mice fed a high-fat diet, a reduction in the number of CD8⁺ T cells, which infiltrated epididymal visceral adipose tissue (epiWAT) or subcutaneous adipose tissue, was observed. Adipose tissue weight and adipocyte area were significantly reduced together with downregulation of adipogenic genes only in the epiWAT. Our findings highlight a distinct effect of MCT1 deficiency in CD8 + T cells in the crosstalk with adipocytes and reinforce the concept that targeting immunometabolic reprogramming in lymphocyte could impact the immune-adipose tissue axis in obesity.