Effects of oral and subcutaneous administration of HSP60 on myeloid-derived suppressor cells and atherosclerosis in ApoE-/- mice.

HSP60 has been proved to be closely related to atherosclerosis due to its antigenicity. To determine this antigenicity effect, the ApoE-/- mice were fed with western-type diet and HSP60 was administrated orally or subcutaneously (SC) for potential vaccine against atherosclerosis. Here, we observed the ApoE-/- mice with oral HSP60 administration group showed a significant reduction in plaque size at the aortic root; accompanied by increased MSDCs (CD11b+ Gr1+ ) in peripheral blood and spleen which was mostly composed of M-MDSCs (CD11b+ LY6G- LY6Chigh ), and increased plasma IL-10 and splenic Foxp3, Arg1, iNOS mRNA as well as decreased plasma IFN-γ and splenic T-bet mRNA compared to control group. Surprisingly, ApoE-/- mice with subcutaneous HSP60 administration group showed contrary results and their MDSCs were mostly composed of G-MDSCs (CD11b+ LY6G+ LY6Clow ). As expected, both PBS-oral and PBS-SC groups showed no significant effects on both the immune response and atherosclerotic plaque formation. In contrast, subcutaneous administration of HSP60 causes the opposite response. Thus, we propose the proper method for administering HSP60 as a new immunologic agent for prevention and treatment of atherosclerosis.