Cardiac fibroblasts produce leukemia inhibitory factor and endothelin, which combine to induce cardiac myocyte hypertrophy in vitro

Abstract

Cardiac fibroblasts in culture produce factor(s) that induce hypertrophy of neonatal rat ventricular myocytes in vitro. As in vivo, the myocyte hypertrophy response in culture is characterized by an increase in cell size and contractile protein content, and by the activation of embryonic genes, including the gene for atrial natriuretic peptide. The purpose of this study was to identify the factor(s) produced by fibroblasts that induce myocyte hypertrophy. The fibroblast hypertrophy activity was inhibited using a combination of the endothelin A receptor blocker BQ-123 and an antibody to leukemia inhibitory factor. The individual antagonists each caused a partial inhibition. The mRNAs for both leukemia inhibitory factor and endothelin were detected by RT-PCR analysis and the concentration of both proteins was determined to be approximately 200 pmol/L in the conditioned medium using immunoassays. Purified leukemia inhibitory factor and endothelin each induced distinctive morphological changes in the myocytes. Their combination generated a different morphology similar to that induced by fibroblast conditioned medium. Each factor also induced atrial natriuretic peptide production, but both were required for the myocytes to produce the levels measured after exposure to fibroblast conditioned medium. These results show that hypertrophy activity produced by cardiac fibroblasts in culture is a result of leukemia inhibitory factor and endothelin.

Development and Validation of Real-Time Quantitative Reverse Transcriptase–Polymerase Chain Reaction for Monitoring Gene Expression in Cardiac Myocytesin Vitro

“…Figures 3a-3d show relative fold induction (⌬⌬CT analysis) of the ANF mRNA in response to the various treatments. The doses of each agent required for induction of ANF mRNA correlate very well with the doses which cause morphological responses (6,11).…”

“…The cells were cultured in 96-well plates precoated with 4% fetal calf serum as previously described (6). The cells were plated in serum-free F12/ DME supplemented with 10 g/ml transferrin, 1 g/ml insulin, 1 g/ml aprotinin, 2 mM glutamine, 100 U/ml penicillin G, and 100 g/mL streptomycin at a density of 1.5 ϫ 10 4 cells/well.…”

TGF-β1, Released by Myofibroblasts, Differentially Regulates Transcription and Function of Sodium and Potassium Channels in Adult Rat Ventricular Myocytes

“…[4], [5] Neonatal rat fibroblast also release significant amounts of IGF-1, endothelin A and leukemia inhibitory factor proteins, which are some of the proteins responsible for hypertrophy in cardiac myocytes and increased collagen synthesis in fibroblasts due to FCM. [6], [7].…”

Role of interleukin‐6 in cardiomyocyte/cardiac fibroblast interactions during myocyte hypertrophy and fibroblast proliferation

“…Among these, cytokines of the IL‐6 family are of particular interest given recent reports of their ability to promote cross‐talk between cardiomyocytes and fibroblasts. Indeed, using CM/CF coculture models, it has been demonstrated that leukemia inhibitory factor (LIF), which is synthesized by both CMs and CFs (Matsui et al, 1996; Kuwahara et al, 1998), is able to modulate myocyte growth in a paracrine fashion (King et al, 1996). Kuwahara et al (1999) also suggested that CT‐1 is significantly involved in the hypertrophic changes to CMs in coculture with NCMs.…”