GRK2 levels in myeloid cells modulate adipose-liver crosstalk in high fat diet-induced obesity

Macrophages are key effector cells in obesity-associated inflammation. G protein-coupled receptor kinase 2 (GRK2) is highly expressed in different immune cell types. Using LysM-GRK2+/− mice, we uncover that a reduction of GRK2 levels in myeloid cells prevents the development of glucose intolerance and hyperglycemia after a high fat diet (HFD) through modulation of the macrophage pro-inflammatory profile. Low levels of myeloid GRK2 confer protection against hepatic insulin resistance, steatosis and inflammation. In adipose tissue, pro-inflammatory cytokines are reduced and insulin signaling is preserved. Macrophages from LysM-GRK2+/− mice secrete less pro-inflammatory cytokines when stimulated with lipopolysaccharide (LPS) and their conditioned media has a reduced pathological influence in cultured adipocytes or naïve bone marrow-derived macrophages. Our data indicate that reducing GRK2 levels in myeloid cells, by attenuating pro-inflammatory features of macrophages, has a relevant impact in adipose-liver crosstalk, thus preventing high fat diet-induced metabolic alterations.
We acknowledge support by Ministerio de Economía y Competitividad (MINECO/FEDER), Spain (grant SAF2017-84125-R to FM and CM and SAF2017-82436R to LB); CIBER de Enfermedades Cardiovasculares (CIBERCV). Instituto de Salud Carlos III, Spain (grant CB16/11/00278 to F.M., CB16/11/00222 to L.B., and, PI15/01114 to Francisco Tinaones (Universidad De Málaga, Spain), co-funded with European FEDER contribution); European Foundation for the Study of Diabetes (EFSD) Novo Nordisk Partnership for Diabetes Research in Europe Grant (to F.M.); and Programa de Actividades en Biomedicina de la Comunidad de Madrid-B2017/BMD-3671-INFLAMUNE to FM and MF.. I.M.-I. was supported by the “MS type I” program (CP16/00163). The authors thank the Metagenomic Platform of the Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición, CIBERobn, Instituto de Salud Carlos III (ISCIII), Spain. We appreciate the help of the CBMSO Facilities, in particular Flow Cytometry, Genomics and Animal Care. We acknowledge Paula Ramos for technical support. We also acknowledge the institutional support to the CBMSO from Fundación Ramón Areces.