In the present study we found that at steady state, diabetic db/db mice have

lower proportions of B-1a cells in the peritoneal cavity. The db/db mice also showed a dampened antibody response when their innate immune system was challenged with a TLR-4 ligand or pneumococcal components, indicating that the B-1 cells in the db/db mice were less responsive in producing protective IgM. In accordance with this, decreased IgM production in response to LPS treatment has been reported previously in a mouse model of type I diabetes [30]. Together, these results indicate that diabetes suppresses innate immune responses AZD0530 concentration challenged with T independent antigens, at least in mice. This inhibitory effect of glucose at high concentrations is not necessarily specific for B-1a or B-1b

cells, as supported by our in-vitro findings in Selleck BMS-777607 sorted B cell subpopulations. The decreased proportion of B-1a cells in the peritoneal cavity of db/db mice was not accompanied with decreased IgM levels at steady state. However, previous studies have shown that B-1 cells in pleural and peritoneal cavities secrete only small amounts of natural antibodies at steady state [31], which corresponds with their low levels of mRNA encoding secreted IgM [32]. Instead, it seems that spleen and bone marrow contain B-1 cells that secrete spontaneously large amounts of IgM that are thought to be a major contributor to circulating levels of IgM [31]. The decrease in proportion of B-1a cells in the diabetic mice was accompanied by an increase in B-2 cells. Therefore, we cannot rule out that the proportion of B-1a cells might be influenced by the high number of B-2 cells. The reason for a concomitant increase in B-2 cells is unclear. By performing in-vitro experiments with isolated B-2 cells, where glucose also had an inhibitory effect on this cell type, we conclude that the high number of B-2 cells in the diabetic mice is not

a direct effect Depsipeptide ic50 of glucose. Hypothetically, there might be a higher antigenic burden in these mice due to an overall effect on the innate immune system. Hyperglycaemia is one of the key factors that contribute to diabetic complications. Prolonged exposure to high glucose have many effects, including release of reactive oxygen species (ROS) and several proinflammatory cytokines [33-35], and therefore have deleterious effects on cells and cellular processes. Here we found that hyperglycaemia affected isolated mouse peritoneal B-1 cells and the production of IgM. Increasing concentrations of glucose resulted in diminished secretion of total IgM and IgM against CuOx-LDL and MDA-LDL. We also found that a high glucose concentration increased apoptosis and cell death and affected the proportion of cells in mitosis in the B-1 cells negatively.