| BackgroundCarotid Atherosclerosis is characterized by thickening and loss of elasticity of carotid arterial walls. The carotid arteries originate bilaterally and travel along the left and the right sides of the neck and are named accordingly. The right carotid artery originates from the innominate artery, and the left originates directly from the aortic arch. Midway along the neck, the arteries enlarge to form the carotid bulbs. From thence they bifurcate into the external carotid artery and internal carotid artery. The carotid sinus and the carotid body are located at the bifurcation. These arteries give blood supply to large portions of the brain. Narrowing of their lumen as a consequence of deposition of atherosclerotic plaques results in cerebrovascular events.Carotid atherosclerosis frequently results in ischemic stroke, the most devastating complication of atherosclerosis. Embolization is considered the most common mechanism causing cerebral ischemic events from atherosclerotic lesions in the carotid bulb.Atherosclerosis is the leading cause of death and disability in the developed world. Also in the developing countries, out of the 50 million deaths that occur globally, about 40 million occur in developing countries alone, and a significant percentage of the deaths results from cardiovascular diseases. The burden of atherosclerosis is also significant in China and other Asian countries with the advent of economic advancement which is associated with changes in life style and eating habits.There are a number of treatment options for managing patients with atherosclerotic narrowing of the carotid arteries. This may depend on the extent of narrowing of the carotid arteries and the manifestation of signs and symptoms. Patients can be managed on pharmacologic therapy, carotid angioplasty and stenting, or carotid endarterectomy.It is pretty obvious from the foregoing that atherosclerosis is a global problem and takes a heavy toll on global resources; both human and material resources. This is partly because there are still knowledge gaps in our understanding of the basic mechanism of atherogenesis. The condition central to the formation of atherogenesis as well as the weights of each of the associated risk factors of atherosclerosis are still in an.intense academic contest. While certain treatment models like statins are universally accepted, used in cardiology practice more like "a sniper fire to shoot down rising hypercholesterolemia," other researchers still question the scientific basis of that practice.The sum of all this is that our journey to understand the basic and central mechanism of atherogenesis is still way ahead, and it is not time yet to take a break. This underscores the need for a relentless effort to get a better understanding of the disease in order to be able to predict with acceptable level of certainty the individuals who are at risk of development of the disease at the early stages. In line with this, the aim of this study was to investigate the global protein expression profile of carotid atherosclerosis using autopsy samples of carotid arteries in people who died suddenly from the complications of atherosclerosis compared to age match individuals who died suddenly due to other causes other than atherosclerotic disease.Objectives1. To do proteome profiling of atherosclerotic and non-atherosclerotic carotid artery samples from autopsy tissues2. To do comparative proteomic analysis to identify differentially expressed proteins in atherosclerosis.Methods:1. Carotid arterytissues Sampledduring autopsy were sorted into atherosclerotic and the non-atherosclerotic age matched cases2. Two dimensional electrophoresis (2DE) was performed to separate proteins based on their isoelectric points in the first dimension electrophoresis using immobilized pH gradient strips (IPG strips). This was followed bya second dimension electrophoresis to separate the proteins based on their molecular weight using sodium dodecyle sulfate polyacrylamide gel electrophoresis (SDS-PAGE).3. Mass spectrophotometry was used to identify the differentially expressed proteins4. Bioinformatics data base search was performed to identify the peptide ringer printsResultsThree replicates each of the 2D images of both the normal and the atherosclerotic tissues were used for the analysis with the Biorad PDQuest software for 2D analysis. A total of 209 protein spots were detected in the atherosclerosis replicate group and 205 spots were detected in the non-atherosclerotic replicate group. The analysis was set to flag protein spots with more than two fold differential protein expression between the two groups with a statistical significance more than 95%.The intragroup match rates among both the atherosclerotic and non-atherosclerotic groups were good with correlation co-efficients of 0.88 and 0.90 respectively, figure 5. Also, the intergroup match rate between the atherosclerotic and the non-atherosclerotic groups was adequate with correlation coefficient of 0.70. A total of 160 spots were matched across all spots in both the atherosclerotic and the non-atherosclerotic images.Forty nine proteins were differentially expressed between the two groups. Out of this number, 23 proteins were down-regulated and 26 were upregulated in the atherosclerotic tissues. Seven proteins were so markedly down-regulated that there were barely detectable in atherosclerotic tissues. At the same time 11 proteins were markedly upregulated and were also barely detectable in the normal tissues.The proteins that were markedlydownregulated ordetectedonly in the normal carotid samples include:Keratin type I cytoskeletal 10,14-3-3 protein theta, Vitronectin,muscular LMNA-interacting protein (MLIP), Cathepsin D, ALB Isoform 2 of Serum albumin and another peptide highly similar to Serum albumin. Proteins that were markedly upregulated or detected only in the atherosclerotic tissues were:Vimentin, Isoform 1 of Serum albumin, MLIP, type I cytoskeletal 9, Complement C3 (Fragment), Peroxiredoxin-2, AMBP Protein, Cathepsin D, Beta-actin-like protein 2, aortic smooth muscle Actin, and MYL9 Myosin regulatory light polypeptide 9.Atherogenesis is acomplex mechanisms that involves an interplay between inflammatory mechanisms, oxidative mechanisms, lipid metabolism, apoptosis, and maintenance of the structural integrity of endothelial cells. How exactly these mechanisms play out in tandem, in other words, the exact sequence of events in atherogenesis, is still a subject of academic debate, more like the dilemma of whether it is the hen that is older than the egg or rather the egg that is older than the hen.It is intriguing that each of the proteins detected in this proteome profiling has been shown in previous studies to be involved in at least one of these contributory mechanisms to atherosclerotic plaque formation.From the literature, ALB Isoform 2 of Serum albumin,14-3-3 protein theta, MYL9 Myosin regulatory light polypeptide 9 are known to participate in apoptosis. Vitronectin, Complement C3, and Vimentin participate in inflammation. Complement C3 is also known to be involved in lipid metabolism and also interact with intermediate filaments that maintain structural integrity of endothelial cells. AMBP Protein, Peroxiredoxin-2 and Cathepsin D have antioxidant properties and also plays a role in oxidative mechanisms.This study has added confirmation to the expression of these proteins in vascular and or atherosclerotic plaques and their possible involvement in the disease. Functional analysis of these finger printed proteins would be necessary to properly align their role in atherosclerosis. We would then be able to tell whether their presence or lack of it is causative of, or, a compensatory response to, atherosclerosis... |
PDF Full Text Request