Molecular Mechanisms and Carotid Atherosclerosis

Overview

The role of methylase system and Proprotein convertase subtilisin/kexin type 9 (PCSK9) in the accelerated atherosclerotic progression of diabetic patients is unclear. Authors will evaluate methylase activity and PCSK9 in carotid plaques of asymptomatic diabetic and non diabetic patients, as well as the effect of statin added to PCSK9 inhibitors (PCSK9i) therapy vs. statin alone in diabetic plaques. Plaques will be obtained from 43 type 2 diabetic and 30 non diabetic patients undergoing carotid endarterectomy. Diabetic patients will receive statin therapy (n 23) or statin plus PCSK9i (140 mg of evolocumab; n 20) or placebo (n 23) for 4 months before scheduled endarterectomy. Plaques will be analyzed for macrophages (CD68), T-cells (CD3), inflammatory cells (HLADR), methylase activity, nuclear factor (NF)-KB, tumor necrosis factor (TNF)-alpha, nitrotyrosine, matrix metalloproteinase (MMP) and collagen content (immunohistochemistry and enzyme- linked immunosorbent assay. Authors' study hypothesis is that methylase and PCSK9 over-activity will be associated with enhanced inflammatory reaction and NF-KB expression in diabetic plaques. Secondly, the inhibition of methylase activity in atherosclerotic lesions of diabetic patients by metformin plus SLGT2i might be associated with morphological and compositional characteristics of a potential stable plaque phenotype, possibly by down regulating NF-KB-mediated inflammatory pathways.

Diabetes Mellitus (DM) leads to increased vulnerability for plaque disruption and mediates increased incidence and severity of clinical events. Inflammation, particularly in diabetes, plays a central role in the cascade of events that result in plaque erosion and fissuring. There is emerging evidence that the methylase system might be involved in both initial stage and progression of atherosclerosis. Moreover, the methylase system might be involved in inflammatory/oxidative stress pathway, involved for activation of nuclear factor kappa B (NF-KB), and other proteins linked to over inflammation/oxidative stress. Although it has been demonstrated that diabetes may up regulate these inflammatory/oxidative pathway, still no evidence exists about the potential role of methylase system in the evolution of atherosclerotic plaques of diabetic patients. Conversely, less data have been reported about the possible modulation of these pathways by drugs as PCSK9i. However, in the present study authors hypothesized that by increasing methylase activity, diabetes may enhance the inflammatory potential of atherosclerotic plaques favoring instability, and its relation with the expression of proprotein convertase subtilisin/kexin type 9 (PCSK9). Therefore, authors designed this study to identify differences in inflammatory infiltration as well as methylase activity and PCSK9 expression between carotid plaques of asymptomatic diabetic and non diabetic (normoglycemics) patients. Because experimental and pathological studies suggest that activation of methylase system might control inflammation/oxidative stress, the present study also evaluated the effect of the statin added to PCSK9i (vs. statin alone) on methylase activity and PCSK9 expression in carotid plaques of diabetic patients.