title: Cardiac myofibroblast differentiation is attenuated by alpha(3) integrin blockade: potential role in post-MI remodeling.
abstract: Cardiac fibroblasts and myofibroblasts are responsible for post-MI remodeling which occurs via regulation of extracellular matrix (ECM). Accelerated post-MI remodeling leads to excessive ECM deposition and fibrosis, contributing to impaired contractile function, arrhythmias, and heart failure. We have previously reported that type VI collagen induces myofibroblast differentiation in cultured cardiac fibroblasts, and that type VI collagen and myofibroblast content were both elevated in the myocardium 20 weeks post-MI. The purpose of this study was to determine the expression patterns of type VI collagen and myofibroblast content in early post-myocardial infarction (MI) remodeling to gain insight into whether type VI collagen induces in vivo myofibroblast differentiation via specific matrix-receptor interactions. Adult male Sprague-Dawley rats were anesthetized and left coronary arteries were permanently ligated. Histological tissue sections and whole tissue protein lysates were obtained from infarcted and non-infarcted areas of MI hearts and sham operated controls. At 3 days post-MI, we observed a significant increase in alpha(3) integrin expression (2.02+/-0.18 fold); at 7 days post-infarction both type VI collagen (2.27+/-0.18 fold) and myofibroblast (4.65+/-0.6 fold) content increased. By 14 days myofibroblast content returned to sham control levels, although type VI collagen (2.42+/-0.11 fold) was still elevated. In vitro cross-linking confirmed that the alpha(3) integrin interacts with type VI collagen, and alpha(3) integrin function blocking antibodies inhibited the differentiation of isolated cardiac fibroblasts. Collectively, our in vitro results indicate that the alpha(3) integrin receptor interacts with type VI collagen to promote myofibroblast differentiation, and that this interaction may impact in vivo post-MI remodeling.
authors.affiliation: Department of Integrative Medical Sciences, Northeastern Ohio Universities College of Medicine, Rootstown, OH, USA.
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Bryant
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Shamhart
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Luther
authors.forename: Erik R
authors.initials: ER
authors.lastname: Olson
authors.forename: John C
authors.initials: JC
authors.lastname: Koshy
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Costic
authors.forename: Monica V
authors.initials: MV
authors.lastname: Mohile
authors.forename: Michelle
authors.initials: M
authors.lastname: Dockry
authors.forename: Kathleen J
authors.initials: KJ
authors.lastname: Doane
authors.forename: J Gary
authors.initials: JG
authors.lastname: Meszaros
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D024142:Collagen Type VI / Q000378:metabolism* / Q000502:physiology; D005347:Fibroblasts / Q000166:cytology*; D015151:Immunoblotting; D039422:Integrin alpha3 / Q000378:metabolism*; D008297:Male; D009203:Myocardial Infarction / Q000378:metabolism*; D009206:Myocardium / Q000166:cytology*; D011485:Protein Binding; D051381:Rats
chemical_list: D024142:Collagen Type VI; D039422:Integrin alpha3