title: Phage display identification of age-associated TNFalpha-mediated cardiac oxidative induction.
abstract: Age-associated alterations in the actions of tumor necrosis factor-alpha (TNFalpha) in the heart with impaired cardioprotective pathways and enhanced apoptotic induction may contribute to the increased severity of cardiovascular pathology in older persons. To identify the molecular events mediating these changes in the microvasculature of the aging rodent heart, the biochemical properties of in vivo phage-display cyclic peptide cardiac biopanning were studied. Analysis of individual amino acid positions revealed that the center of the peptide motif (amino acid position 4) had a significantly higher frequency of aromatic amino acid side chains in phage homing to the old hearts compared with young controls (18 mo old, 11% vs. 3 mo old, 3%, P < 0.05). This subset of phage motifs revealed an age-associated homology with oxidoreductase enzymes (homology: 18 mo, 7/7; 3 mo, 0/2), suggesting the substrates and/or binding sites of these enzymes are increased in the aging hearts. Immunostaining for the oxidoreductase substrate 4-hydroxy-2-nonenal (HNE), a cardiotoxic lipid peroxidation product, demonstrated a twofold higher density of HNE(+) cells in PBS-treated hearts of old mice (18 mo) compared with young controls (3 mo) (18 mo, 3.2 +/- 2.8 vs. 3 mo, 1.0 +/- 0.9 cells/HPF, P < 0.05). Moreover, intracardiac injection of TNFalpha resulted in a significantly greater increase in HNE staining in the old hearts (18 mo, 16.9 +/- 13.8 vs. 3 mo, 9.1 +/- 6.0 cells/HPF, P < 0.05). Overall, these studies demonstrate that aging-associated alterations in TNFalpha-mediated pathways with induction of reactive oxidative species and changes in vascular surface binding sites may contribute mechanistically to the increased cardiovascular pathology of the aging heart.
authors.affiliation: Department of Medicine, Weill Medical College of Cornell University, New York, New York 10021, USA. jme2002@med.cornell.edu
authors.forename: Jay M
authors.initials: JM
authors.lastname: Edelberg
authors.forename: Alvin
authors.initials: A
authors.lastname: Wong
authors.forename: Jacquelyne M
authors.initials: JM
authors.lastname: Holm
authors.forename: Munira
authors.initials: M
authors.lastname: Xaymardan
authors.forename: Inga
authors.initials: I
authors.lastname: Duignan
authors.forename: Andrew
authors.initials: A
authors.lastname: Chin
authors.forename: Jorge R
authors.initials: JR
authors.lastname: Kizer
authors.forename: Dongqing
authors.initials: D
authors.lastname: Cai
mesh_terms: D000375:Aging / Q000502:physiology*; D020816:Amino Acid Motifs; D000818:Animals; D007150:Immunohistochemistry / Q000379:methods; D007526:Isoelectric Point; D015227:Lipid Peroxidation; D051379:Mice; D008810:Mice, Inbred C57BL; D009206:Myocardium / Q000737:chemistry / Q000473:pathology; D018384:Oxidative Stress / Q000502:physiology*; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D017382:Reactive Oxygen Species / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
chemical_list: D019151:Peptide Library; D010455:Peptides; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha