Dyslipidemia-associated alterations in B cell subpopulation frequency and phenotype during experimental atherosclerosis

Lymphocytes, the cellular effectors of adaptive immunity, are involved in the chronic inflammatory process known as atherosclerosis. Proatherogenic and atheroprotective properties have been ascribed to B cells. However, information regarding the role of B cells during atherosclerosis is scarce. Both the frequency and the phenotype of B cell subpopulations were studied by flow cytometry in wild type and apolipoprotein-E-deficient (apoE−/−) mice fed a high-fat (HFD) or control diet. Whereas the proportion of follicular cells was decreased, transitional 1-like cells were increased in mice with advanced atherosclerotic lesions (apoE−/− HFD). B cells in atherosclerotic mice were more activated, indicated by their higher surface expression of CD80, CD86, CD40 and CD95 and increased serum IgG1 levels. In the aorta, a decreased frequency of B cells was observed in mice with advanced atherosclerosis. Low expression of CD19 was observed on B cells from the spleen, aorta and lymph nodes of apoE−/− HFD mice. This alteration correlated with serum levels of IgG1 and cholesterol. A reduction in CD19 expression was induced in splenic cells from young apoE−/− mice cultured with lipemic serum. These results show that mice with advanced atherosclerosis display a variety of alterations in the frequency and phenotype of B lymphocytes, most of which are associated with dyslipidemia.