title: Humanin, a cytoprotective peptide, is expressed in carotid atherosclerotic [corrected] plaques in humans.
abstract: OBJECTIVE
  The mechanism of atherosclerotic plaque progression leading to instability, rupture, and ischemic manifestation involves oxidative stress and apoptosis. Humanin (HN) is a newly emerging endogenously expressed cytoprotective peptide. Our goal was to determine the presence and localization of HN in carotid atherosclerotic plaques.
  
  
  RESULTS
  Plaque specimens from 34 patients undergoing carotid endarterectomy were classified according to symptomatic history. Immunostaining combined with digital microscopy revealed greater expression of HN in the unstable plaques of symptomatic compared to asymptomatic patients (29.42±2.05 vs. 14.14±2.13% of plaque area, p<0.0001). These data were further confirmed by immunoblot (density of HN/β-actin standard symptomatic vs. asymptomatic 1.32±0.14 vs. 0.79±0.11, p<0.01). TUNEL staining revealed a higher proportion of apoptotic nuclei in the plaques of symptomatic patients compared to asymptomatic (68.25±3.61 vs. 33.46±4.46% of nuclei, p<0.01). Double immunofluorescence labeling revealed co-localization of HN with macrophages (both M1 and M2 polarization), smooth muscle cells, fibroblasts, and dendritic cells as well as with inflammatory markers MMP2 and MMP9.
  
  
  CONCLUSIONS
  The study demonstrates a higher expression of HN in unstable carotid plaques that is localized to multiple cell types within the plaque. These data support the involvement of HN in atherosclerosis, possibly as an endogenous response to the inflammatory and apoptotic processes within the atheromatous plaque.
authors.affiliation: Division of Cardiovascular Diseases, Department of Nephrology and Hypertension, Mayo Clinic College of Medicine, Rochester, Minnesota, United States of America.
authors.forename: David G
authors.initials: DG
authors.lastname: Zacharias
authors.forename: Sung Gyun
authors.initials: SG
authors.lastname: Kim
authors.forename: Alfonso Eirin
authors.initials: AE
authors.lastname: Massat
authors.forename: Adi R
authors.initials: AR
authors.lastname: Bachar
authors.forename: Yun K
authors.initials: YK
authors.lastname: Oh
authors.forename: Joerg
authors.initials: J
authors.lastname: Herrmann
authors.forename: Martin
authors.initials: M
authors.lastname: Rodriguez-Porcel
authors.forename: Pinchas
authors.initials: P
authors.lastname: Cohen
authors.forename: Lilach O
authors.initials: LO
authors.lastname: Lerman
authors.forename: Amir
authors.initials: A
authors.lastname: Lerman
mesh_terms: D000185:Actinin / Q000378:metabolism; D000368:Aged; D017209:Apoptosis; D001119:Arginase / Q000378:metabolism; D015153:Blotting, Western; D002340:Carotid Artery Diseases / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D005260:Female; D006801:Humans; D020287:In Situ Nick-End Labeling; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D014746:Vimentin / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008840:Microfilament Proteins; D014746:Vimentin; C427211:humanin; D000185:Actinin; C020324:fascin; D052247:Nitric Oxide Synthase Type II; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D001119:Arginase