CD300e as a novel biomarker in obesity: crossatalk between immune system and adipose tissue

Obesity is a multifactorial pathology associated with metabolic dysfunction. Most obese patients (OPs) develop insulin resistance (IR) and have an increased risk of developing type 2 diabetes (T2D). Recently, it has been demonstrated that both T1D and T2D patients are seropositive for the self-antigen CD300e, a surface immune receptor expressed by myeloid cells. We revealed that OPs were also seropositive for CD300e, and the anti-CD300e antibody titre declined after weight loss following bariatric surgery. The improvement of anti-CD300e titre after weight loss correlated positively with the improvement of insulin sensitivity. We aimed to explore the role of CD300e in modulating glycemia by interfering with the signalling cascade triggered by insulin. By using human monocytes, we revealed the activation of CD300e hindered the insulin-stimulated phosphorylation of AKT. In accordance, internalization of glucose was hampered. Next, we revealed that monocytes from OPs expressed significantly more CD300e than monocytes from normal weight subjects, and this positively correlated with their fasting glycemia. ROC curve analysis revealed the serum level of anti-CD300e antibodies before weight loss can predict the beneficial effect of weight loss on the improvement of insulin sensitivity. Our data suggest CD300e might contribute to glycaemic control, by negatively modulating the insulin-triggered pathway and the titre of anti-CD300e antibodies in OPs might become a predictive biomarker for the improvement of insulin sensibility after weight loss.