title: Regulation of adverse remodelling by osteopontin in a genetic heart failure model.
abstract: OBJECTIVE
  Desmin, the muscle-specific intermediate filament protein, is a major target in dilated cardiomyopathy and heart failure in humans and mice. The hallmarks of desmin-deficient (des(-/-)) mice pathology include pronounced myocardial degeneration, extended fibrosis, and osteopontin (OPN) overexpression. We sought to identify the molecular and cellular events regulating adverse cardiac remodelling in des(-/-) mice and their potential link to OPN.
  
  
  RESULTS
  In situ hybridization, histology, and immunostaining demonstrated that inflammatory cells and not cardiomyocytes were the source of OPN. RNA profile comparison revealed that activation of inflammatory pathways, sustained by innate immunity mechanisms, predominated among all changes occurring in degenerating des(-/-) myocardium. The expression of the most highly up-regulated genes (OPN: 226×, galectin-3: 26×, osteoactivin/Gpnmb/DC-HIL: 160× and metalloprotease-12: 98×) was associated with heart infiltrating macrophages. To evaluate the role of OPN, we generated des(-/-)OPN(-/-) mice and compared their cardiac function and remodelling indices with those of des(-/-). Osteopontin promoted cardiac dysfunction in this model since des(-/-)OPN(-/-) mice showed 53% improvement of left ventricular function, paralleled to an up to 44% reduction in fibrosis. The diminished fibrotic response in the absence of OPN could be partly mediated by a dramatic reduction in myocardial galectin-3 levels, associated with an impaired galectin-3 secretion by OPN-deficient infiltrating macrophages.
  
  
  CONCLUSIONS
  Cardiomyocyte death due to desmin deficiency leads to inflammation and subsequent overexpression of a series of remodelling modulators. Among them, OPN seems to be a major regulator of des(-/-) adverse myocardial remodelling and it functions at least by potentiating galectin-3 up-regulation and secretion.
authors.affiliation: Cell Biology Division, Center of Basic Research I, Biomedical Research Foundation, Academy of Athens, Soranou Efessiou 4, Athens 11527, Greece.
authors.forename: Stelios
authors.initials: S
authors.lastname: Psarras
authors.forename: Manolis
authors.initials: M
authors.lastname: Mavroidis
authors.forename: Despina
authors.initials: D
authors.lastname: Sanoudou
authors.forename: Constantinos H
authors.initials: CH
authors.lastname: Davos
authors.forename: Georgina
authors.initials: G
authors.lastname: Xanthou
authors.forename: Aimilia E
authors.initials: AE
authors.lastname: Varela
authors.forename: Vily
authors.initials: V
authors.lastname: Panoutsakopoulou
authors.forename: Yassemi
authors.initials: Y
authors.lastname: Capetanaki
mesh_terms: D000818:Animals; D002311:Cardiomyopathy, Dilated / Q000378:metabolism / Q000503:physiopathology*; D003893:Desmin / Q000172:deficiency*; D005136:Eye Proteins / Q000378:metabolism; D005355:Fibrosis / Q000503:physiopathology; D037502:Galectin 3 / Q000378:metabolism; D006333:Heart Failure / Q000235:genetics* / Q000503:physiopathology; D053508:Matrix Metalloproteinase 12 / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009205:Myocarditis / Q000473:pathology / Q000503:physiopathology; D009206:Myocardium / Q000473:pathology; D032383:Myocytes, Cardiac / Q000502:physiology*; D053495:Osteopontin / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D015854:Up-Regulation; D016277:Ventricular Function, Left / Q000502:physiology; D020257:Ventricular Remodeling / Q000235:genetics / Q000502:physiology*
chemical_list: D003893:Desmin; D005136:Eye Proteins; D037502:Galectin 3; C445671:Gpnmb protein, mouse; D008562:Membrane Glycoproteins; D053495:Osteopontin; D053508:Matrix Metalloproteinase 12