Soluble CLEC2 Extracellular Domain Improves Glucose and Lipid Homeostasis by Regulating Liver Kupffer Cell Polarization

• CLEC2, a type II C-type lectin-like receptor, is expressed on a variety of cell types including Kupffer cells.
• Overexpression of CLEC2 ECD in mice improves glucose and lipid parameters and induces markers of alternatively activated Kupffer cells.
• CLEC2 is a promising therapeutic target for the treatment of diabetes and liver diseases.

The polarization of tissue resident macrophages toward the alternatively activated, anti-inflammatory M2 phenotype is believed to positively impact obesity and insulin resistance. Here we show that the soluble form of the extracellular domain (ECD) of C-type lectin-like receptor 2, CLEC2, regulates Kupffer cell polarization in the liver and improves glucose and lipid parameters in diabetic animal models. Over-expression of Fc-CLEC2(ECD) in mice via in vivo gene delivery, or injection of recombinant Fc-CLEC2(ECD) protein, results in a reduction of blood glucose and liver triglyceride levels and improves glucose tolerance. Furthermore, Fc-CLEC2(ECD) treatment improves cytokine profiles and increases both the M2 macrophage population and the genes involved in the oxidation of lipid metabolism in the liver. These data reveal a previously unidentified role for CLEC2 as a regulator of macrophage polarity, and establish CLEC2 as a promising therapeutic target for treatment of diabetes and liver disease.