Rho kinase-1 mediates cardiac fibrosis by regulating fibroblast precursor cell differentiation

• Published in: Cardiovascular research 2009-08, Vol.83 (3), p.511-518
• Main Authors: Haudek, Sandra B., Gupta, Damon, Dewald, Oliver, Schwartz, Robert J., Wei, Lei, Trial, JoAnn, Entman, Mark L.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Cardiac fibroblasts; Cardiology. Vascular system; Cardiomyopathies - enzymology; Cardiomyopathies - pathology; Cardiomyopathies - physiopathology; Cardiomyopathies - prevention & control; Cell differentiation, maturation, development, hematopoiesis; Cell physiology; Cell Transdifferentiation; Cells, Cultured; Chemokine CCL2 - metabolism; Disease Models, Animal; Endothelial transmigration; Fibroblasts - enzymology; Fibroblasts - pathology; Fibrosis; Fundamental and applied biological sciences. Psychology; Humans; Leukocyte Rolling; Leukocytes, Mononuclear - enzymology; Leukocytes, Mononuclear - pathology; Medical sciences; Mice; Mice, Knockout; Molecular and cellular biology; Monocytes; Myocardial Reperfusion Injury - enzymology; Myocardial Reperfusion Injury - pathology; Myocardial Reperfusion Injury - physiopathology; Myocardial Reperfusion Injury - prevention & control; Myocardium - enzymology; Myocardium - pathology; Original; Rho-associated kinase-1; rho-Associated Kinases - deficiency; rho-Associated Kinases - genetics; rho-Associated Kinases - metabolism; RNA Interference; Signal Transduction; Transfection
• ISSN: 0008-6363; 1755-3245
• DOI: 10.1093/cvr/cvp135

Aims Highly proliferative, CD34+/CD45+ fibroblasts derived from monocytic, blood-borne precursor cells play a critical role in the development of fibrosis in a murine ischaemic/reperfusion cardiomyopathy (I/RC) model. The differentiation of human monocytes into fibroblasts in vitro occurs after transendothelial migration (TEM) induced by monocyte chemoattractant protein 1 (MCP-1). Because Rho-associated kinase-1 (ROCK-1) has been implicated in fibrosis and leukocyte TEM, we investigated its involvement in I/RC. Methods and results We subjected mice with genetic deletion of ROCK-1 to I/RC. We found that ROCK-1−/− mice did not develop the fibrosis and cardiac dysfunction characteristic for I/RC: compared with wild-type, ROCK-1−/− hearts showed markedly lower numbers of I/RC-induced α-smooth muscle actin+ fibroblasts and CD34+/CD45+ fibroblast precursors. Isolated cardiac fibroblasts from ROCK-1−/− mice undergoing I/RC were large and slowly proliferating, similar to fibroblasts isolated from sham-treated hearts. We also performed in vitro assays in which human peripheral blood mononuclear cells (PBMC) migrated through endothelial cells in response to MCP-1. Prior to migration, PBMC were incubated with ROCK-1-targeting small interfering RNA to silence ROCK-1 expression. We found that an 80% reduction of ROCK-1 protein did not inhibit TEM, but significantly reduced the amount of mononuclear cells that differentiated into fibroblasts by >20-fold. Conclusion Our data implicate an important role for ROCK-1 in the differentiation, but not in the TEM of monocytes that mature into cardiac fibroblasts. These cells mediate non-adaptive fibrosis.