Disruption of histamine/H3 receptor signal reduces collagen deposition in cultures scar myofibroblasts.

: A suitable inflammatory signal influences extracellular matrix accumulation and determines the quality of the myocardial infarction scar. The aim of the present study was to determine the influence of mast cell sonicates or histamine on collagen accumulation in heart myofibroblast culture and on the deposition of collagen in the myocardial infarction scar. The histamine receptor involved in the process was investigated. Myocardial infarction was induced by ligation of the left coronary artery. Myofibroblasts were isolated from the scar of myocardial infarction. The effects of mast cell sonicates, histamine and its receptor antagonists, i.e. ketotifen (H1-receptor inhibitor), ranitidine (H2-receptor inhibitor), ciproxifan (H3-receptor inhibitor), JNJ7777120 (H4-receptor inhibitor), imetit (H3 receptor agonist), were investigated. The mast cell sonicates or histamine (10-10 - 10-5M) augmented collagen content in myofibroblast cultures; however, histamine-induced elevation was reduced by ciproxifan (10-5M, 10-6M). Imetit (10-9 - 10-5M) elevated collagen content in the culture. H3 receptor expression on myofibroblasts was confirmed. Our findings indicate that histamine increases the deposition of collagen in cultures of myofibroblasts isolated from the myocardial infarction scar. This effect is dependent on H3 receptor activation.