title: Increased expression of oxidation-specific epitopes and apoptosis are associated with haptoglobin genotype: possible implications for plaque progression in human atherosclerosis.
abstract: OBJECTIVE
  The purpose of this study was to test the hypothesis that increased oxidative stress is associated with apoptosis in human plaques with the haptoglobin (Hp) 2-2 genotype.
  
  
  BACKGROUND
  Intraplaque hemorrhage releases free hemoglobin (Hb). Impaired Hb clearance induces oxidative stress leading to plaque progression. The binding of Hp to Hb attenuates iron-induced oxidative reactions.
  
  
  METHODS
  Twenty-six human aortic plaques were Hp genotyped. Hp2-2 plaques (n = 13) were compared with control (Hp1-1/2-1) (n = 13). The iron grade was measured by Perl's staining. Immunostaining was used to detect oxidation-specific epitopes (OSEs) reflecting oxidized phospholipids and malondialdehyde-like epitopes. The percentages of apoptotic cells and apoptotic morphological features were quantified. DNA fragmentation and active caspase-3 were measured by in situ end-labeling and immunohistochemistry, respectively.
  
  
  RESULTS
  In Hp2-2 plaques, iron content was increased (1.22 ± 0.15 vs. 0.54 ± 0.08; p < 0.0001) along with expression of oxidized phospholipid- (78.9 ± 5.8 vs. 38.8 ± 3.8; p < 0.0001), and malondialdehyde-like OSEs (93.9 ± 7.9 vs. 54.7 ± 3.9; p < 0.0001). The total percentages of apoptotic cells (11.9 ± 0.44 vs. 3.5 ± 0.28; p < 0.0001), nuclear fragmentation (11.8 ± 0.50 vs. 3.3 ± 0.26; p < 0.0001), nuclear condensation (10.9 ± 0.58 vs. 3.4 ± 0.20; p < 0.0001), chromatin margination (14.2 ± 0.57 vs. 6.5 ± 0.37; p < 0.0001), cytoplasmic blebs (1.6 ± 0.28 vs. 0.8 ± 0.14; p < 0.002), and eosinophilia (10.8 ± 0.74 vs. 4.2 ± 0.27; p < 0.0001) were increased in Hp2-2 plaques. Furthermore, DNA fragmentation (119.9 ± 1.40 vs. 57.5 ± 0.80; p < 0.001), and active caspase-3 density (84.7 ± 7.62 vs. 50.6 ± 7.49; p < 0.004) were increased in Hp2-2 plaques. Logistic regression analysis identified correlation between the percentage of apoptotic cells and the density of OSEs (r = 0.56; p < 0.003).
  
  
  CONCLUSIONS
  These findings provide insights into genetic predisposition to oxidative stress and the relationship between OSEs and macrophage apoptosis that may explain advanced atherosclerosis in human Hp2-2 plaques.
authors: Zena and Michael A. Weiner Cardiovascular Institute, Marie-Josée and Henry R. Kravis Cardiovascular Health Center, Mount Sinai School of Medicine, New York, NY 10029, USA.
authors: K-Raman
authors: KR
authors: Purushothaman
authors: Meerarani
authors: M
authors: Purushothaman
authors: Andrew P
authors: AP
authors: Levy
authors: Patrick A
authors: PA
authors: Lento
authors: Solene
authors: S
authors: Evrard
authors: Jason C
authors: JC
authors: Kovacic
authors: Karen C
authors: KC
authors: Briley-Saebo
authors: Sotirios
authors: S
authors: Tsimikas
authors: Joseph L
authors: JL
authors: Witztum
authors: Prakash
authors: P
authors: Krishnan
authors: Annapoorna
authors: A
authors: Kini
authors: Zahi A
authors: ZA
authors: Fayad
authors: Valentin
authors: V
authors: Fuster
authors: Samin K
authors: SK
authors: Sharma
authors: Pedro R
authors: PR
authors: Moreno
mesh_terms: D000368:Aged; D000483:Alleles; D017209:Apoptosis / Q000502:physiology; D053148:Caspase 3 / Q000378:metabolism; D003324:Coronary Artery Disease / Q000235:genetics* / Q000378:metabolism; D053938:DNA Fragmentation; D018450:Disease Progression; D000939:Epitopes / Q000378:metabolism*; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006242:Haptoglobins / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D007501:Iron / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000235:genetics*; D058226:Plaque, Atherosclerotic / Q000235:genetics* / Q000378:metabolism; D012422:Rupture, Spontaneous
chemical_list: D000939:Epitopes; D006242:Haptoglobins; D007501:Iron; D053148:Caspase 3