Cardiac Fibroblasts Play Pathogenic Roles in Idiopathic Restrictive Cardiomyopathy

Abstract

Background: Restrictive cardiomyopathy (RCM) is characterized by impaired ventricular relaxation. Although several mutations were reported in some patients, no mutations were identified in cardiomyocyte expressing genes of other patients, indicating that pathological mechanisms underlying RCM could not be determined by cardiomyocytes only. Cardiac fibroblasts (CFs) are a major cell population in the heart; however, the pathological roles of CFs in cardiomyopathy are not fully understood. Methods and Results: This study established 4 primary culture lines of CFs from RCM patients and analyzed their cellular physiology, the effects on the contraction and relaxation ability of healthy cardiomyocytes under co-culture with CFs, and RNA sequencing. Three of four patients had TNNI3 mutations. There were no significant alterations in cell proliferation, apoptosis, migration, activation, and attachment. However, when CFs from RCM patients were co-cultured with healthy cardiomyocytes, the relaxation velocity of cardiomyocytes was significantly impaired both under direct and indirect co-culture conditions. RNA sequencing revealed that gene expression profiles of CFs in RCM were clearly distinct from healthy CFs. The differential expression gene analysis identified that several extracellular matrix components and cytokine expressions were dysregulated in CFs from RCM patients. Conclusions: The comprehensive gene expression patterns were altered in RCM-derived CFs, which deteriorated the relaxation ability of cardiomyocytes. The specific changes in extracellular matrix composition and cytokine secretion from CFs might affect pathological behavior of cardiomyocytes in RCM.

Atomic force microscopy identifies the alteration of rheological properties of the cardiac fibroblasts in idiopathic restrictive cardiomyopathy

“…Three independent primary culture lines of patient-derived CFs (RCM 1, RCM 2, and RCM 3) were obtained at ventricular assist device implantation or heart transplantation, as previously described [ 10 ]. Then, the left ventricular specimens were minced and cultured in a cell culture dish with Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10% fetal bovine serum (FBS) and 1% penicillin/streptomycin.…”

“…Previous studies demonstrate that both cardiomyocytes and CFs play an important role in cardiac function maintenance and development [ 8 , 9 ]. In addition, we have recently demonstrated that CFs derived from patients with RCM could deteriorate diastolic function of healthy cardiomyocytes via paracrine signaling and direct cell–cell contact [ 10 ]. Furthermore, we identified some cytokines and chemokines that might be associated with paracrine CF–cardiomyocyte interactions; however, direct cell–cell interactions are less understood in cardiomyopathies.…”

Restrictive cardiomyopathy: from genetics and clinical overview to animal modeling

“…Fibroblasts were grown in direct and indirect coculture with healthy cardiomyocytes, causing a decrease in relaxation velocity in the cardiomyocytes. Gene expression for ECM components, ITGA11, COL16A1, TGFB1, MMP2, and COL1A1, were upregulated in fibroblasts from the RCM patients, while cytokines FGF5, CXCL12, MMP1, and IL33 were downregulated, suggesting that dysregulation of paracrine factors may be involved with the diastolic dysfunction found in RCM [138].…”

“…Beyond genetic mutations of genes expressed in cardiac myocytes, cardiac fibroblasts and the extracellular matrix (ECM) may be involved with the pathogenesis of RCM [138]. Natural feline RCM is characterized by severe and extensive fibrous thickening of the endocardium and chamber deformity [139].…”

Fibroblast-Cardiomyocyte Interaction in Pediatric Restrictive Cardiomyopathy

“…Tsuru et al show, for the first time, that fibroblast-cardiomyocyte interaction may play an essential role in the pathophysiology of pediatric RCM and that RCM-CF is activated in a way distinct from traditional myofibroblasts. 6 Although the study was conducted thoroughly in vitro and lacked in vivo evaluation, the results provide a novel concept of targeting fibroblast as a possible treatment strategy for RCM. Further research focusing on RCM-CF is warranted.…”