Activated protein C protects against accelerated atherosclerosis in diabetes by restricting p66shc expression in macrophages
K. Shahzad1, I. Gadi1, S. Nazir1, M. Al-Dabet1, S. Kohli1, S. Ranjan1, F. Bock1,2, B. Isermann1 (1Magdeburg, Germany, 2Nashville, United States)
Vascular wall biology and disorders
Time: 17:15 - 18:15
Objective: Atherosclerosis is two- to four-fold increased in diabetic patients. The mechanisms of accelerated atherosclerosis in diabetes remain poorly defined. As plasma levels of activated protein C (aPC), a protease known for its cytoprotective effects, are reduced in diabetes we hypothesized that aPC protects against diabetes induced atherosclerosis.
Methods: Eight weeks old control (ApoE-/-) mice on a pro-atherogenic background were made diabetic (DM) or fed high fat diet (HFD) for 20 weeks. In subgroup of mice, were either fed chow diet or were given SGLT2 inhibitor to reduce blood lipid and blood glucose level respectively. Supplementary in vitro studies with macrophages were conducted. Atherosclerotic plaques macrophages and smooth muscle cells were isolated by laser capture dissection microscopy.
Results: Diabetic ApoE-/- mcie displayed smaller but less stable plaques with more macrophages and less smooth muscle cells (immunohistochemical analyses) compared to HFD ApoE-/- mice. Expression of p66Shc and CD36 was increased in macrophages, but not in SMCs isolated by laser dissection from plaques of DM ApoE-/- mice as compared to HFD ApoE-/- mice. In vitro glucose induces p66Shc and CD36 expression in macrophages. Glucose induced p66Shc expression remains high even if normoglycemia is restored, suggesting epigenetic control of p66Shc. Bone marrow transplantation from p66Shc-/- into ApoE-/- revealed complete protection from glucose induced atherosclerosis. HFD induced atherosclerotic plaques show regression after restoring blood lipid levels. However hyperglycaemia induced atherosclerotic plaques remains even if normoglycemia is restored, suggesting epigenetic regulation of atherosclerotic plaque in diabetic mice. Treatment with aPC epigenetically reduces p66Shc expression, strongly induces expression of DNMT-1 and decreases plaque size.
Conclusion: These data shows that aPC epigenetically reverses hyperglycemia induced sustained expression of p66Shc and CD36 in atherosclerotic plagues macrophages, identifying a novel mechanism underlying aPC dependent vascular protection. aPC based therapy may be a useful therapeutic adjunct for the treatment of atherosclerosis in diabetic patients.