Proteomic Profile of Unstable Atheroma Plaque: Increased Neutrophil Defensin 1, Clusterin, and Apolipoprotein E Levels in Carotid Secretome

Because
of the clinical significance of carotid atherosclerosis,
the search for novel biomarkers has become a priority. The aim of
the present study was to compare the protein secretion profile of
the carotid atherosclerotic plaque (CAP, n = 12)
and nonatherosclerotic mammary artery (MA, n = 10)
secretomes. We used a nontargeted proteomic approach that incorporated
tandem immunoaffinity depletion, iTRAQ labeling, and nanoflow liquid
chromatography coupled to high-resolution mass spectrometry. In total,
162 proteins were quantified, of which 25 showed statistically significant
differences in secretome levels between carotid atherosclerotic plaque
and nondiseased mammary artery. We found increased levels of neutrophil
defensin 1, apolipoprotein E, clusterin, and zinc-alpha-2-glycoprotein
in CAP secretomes. Results were validated by ELISA assays. Also, differentially
secreted proteins are involved in pathways such as focal adhesion
and leukocyte transendothelial migration. In conclusion, this study
provides a subset of identified proteins that are differently expressed
in secretomes of clinical significance.