Depletion of L2pB1 cells increases abdominal inflammation, blood lipids, and glucose intolerance in DIO mice

Abstract

L2pB1 cells are a subset of B-1 B lymphocytes expressing programmed death ligand 2 (PD-L2) on their surface. They constitute 30-50% of B lymphocytes in the mouse peritoneal cavity and contribute to the production of natural IgM antibody. Previous studies have indicated a protective role of B-1 B cells in attenuating atherosclerosis and insulin resistance. We report that L2pB1 cells possess a unique IgM antibody specificity for phosphorylcholine (PC) and phosphatidylcholine (PtC) IgM enabling them to perform PC- and PtC-specific phagocytosis of PtC-nanoparticles. Here we demonstrate that induced depletion of L2pB1 in a transgenic mouse model with L2pB1-specific diphtheria toxin receptor (DTR) expression increases abdominal inflammation in the peritoneal cavity as well as the visceral adipose tissue in diet-induced obese (DIO) mice. L2pB1-depleted DIO mice also display increased triglycerides and blood glucose levels per gram of body weight relative to PBS-injected control DIO mice. Our results suggest that L2pB1 cells may play a role in anti-inflammatory regulation in DIO. Further investigation is required to discover how L2pB1 cells protect from obesity-induced inflammation and whether L2pB1 cells can provide cellular therapy to control chronic inflammation in obese patients.