Involvement of Cardiotrophin-1 in Cardiac Myocyte-Nonmyocyte Interactions During Hypertrophy of Rat Cardiac Myocytes In Vitro

Background—The mechanism responsible for cardiac hypertrophy is currently conceptualized as having 2 components, mediated by cardiac myocytes and nonmyocytes, respectively. The interaction between myocytes and nonmyocytes via growth factors and/or cytokines plays an important role in the development of cardiac hypertrophy. We found that cardiac myocytes showed hypertrophic changes when cocultured with cardiac nonmyocytes. Cardiotrophin-1 (CT-1), a new member of the interleukin-6 family of cytokines, was identified by its ability to induce hypertrophic response in cardiac myocytes. In this study, we used the in vitro coculture system to examine how CT-1 is involved in the interaction between cardiac myocytes and nonmyocytes during the hypertrophy process. Methods and Results—RNase protection assay revealed that CT-1 mRNA levels were 3.5 times higher in cultured cardiac nonmyocytes than in cultured cardiac myocytes. We developed anti–CT-1 antibodies and found that they significantly inhibited the increased ...