A novel atherogenic epitope from Mycobacterium tuberculosis heat shock protein 65 enhances atherosclerosis in rabbit and LDL receptor-deficient mice.

Previous studies have established that Mycobacterium tuberculosis heat shock protein 65 (mHSP65) plays an important role in immune-associated diseases as an autoimmune factor. Some overlapping epitopes of mHSP65 may serve as initiators of both atherosclerosis and other autoimmune-associated diseases. In the present study, atherosclerosis was significantly enhanced in high-cholesterol diet (HCD)-fed New Zealand white rabbits immunized with mHSP65(91-105) compared with PBS-immunized or BSA-immunized rabbits. Immunizing wild-type C57BL/6J mice with mHSP65(91-105) induced the aortic endothelial injury. Although western blot demonstrated that specific antibodies against mHSP65(91-105) can cross-react with recombinant human heat shock protein 60, specific antibodies against mHSP65(91-105) had no direct effects on HUVECs in vitro. Laser scanning confocal microscopy showed that mHSP65(91-105) localized in the cytoplasm of HUVECs, even when HUVECs were heat shocked at 42°C. mHSP65(91-105)-specific splenic cells secreted more IFN-γ than controls. Also, adoptive transfer of mHSP65(91-105)-specific splenic cells can accelerate atherosclerosis in ldlr( -/- ) mice. We can conclude that the (auto)immune response to mHSP65(91-105) accelerates atherosclerosis in animal models, and that the response of Th1 plays an important role in this progress.