NKT Cell Hyporesponsiveness Leads to Unrestrained Accumulation of Marginal Zone B Cells in Hypercholesterolemic Apolipoprotein E-Deficient Mice [IMMUNE REGULATION]

Recently, the role of B cells in atherosclerosis has gained more attention but studies have mainly focused on B1 and follicular B cell subsets. Therefore, the contribution of marginal zone (MZ) B cells in experimental atherosclerosis remains elusive. In the current study, we examined the MZ B cell compartment in atherosclerotic apoE-deficient (apoE^–/–) mice and found that hypercholesterolemia in these mice was associated with an increased number and percentage of MZ B cells. This aberrant accumulation of MZ B cells was not associated with alterations in their development or increased proliferation but was due to decreased apoptotic cell death. This decrease in MZ B cell death in apoE^–/– mice was associated with the reduced capacity of invariant NKT (iNKT) cells to produce IFN- and IL-4 after activation. Lowering cholesterol plasma levels with ezetimibe in apoE^–/– mice reversed iNKT function and MZ B cell accumulation. To elucidate the mechanism whereby iNKT cells control MZ B cell accumulation in apoE^–/– mice, we performed an adoptive transfer of iNKT cells and found that only wild-type iNKT cells but not IFN-^–/– iNKT cells reversed MZ B cell accumulation in apoE^–/– recipient mice. Our findings reveal that lipid changes associated with atherosclerotic disease induce decreased production of IFN- by iNKT, which in turn leads to aberrant accumulation of MZ B cells. This study further extends the importance of iNKT cells in regulating MZ B cell compartment.

http://ift.tt/2fkwann