Myocardial hypertrophy in transgenic mice overexpressing human interleukin 1α

Abstract Background: Interleukin (IL)-1 has profound effects on nonimmune cells and organs, including the heart. The effects of IL-1 on transgenic hearts have not yet been described. Methods and Results: We generated transgenic mice overexpressing the human IL-1 gene under control of the cytomegalovirus enhancer/chicken β-actin promoter. Heart weight–body weight ratio increased 1.4- to 2.2-fold in transgenic mice compared with wild-type mice. Lung weight–body weight ratio also increased in transgenic mice, all of which died within 14 days of birth. Light microscopy revealed concentric hypertrophy with cardiomyocyte hypertrophy in all transgenic mice and pulmonary edema in some of them. Electron microscopy showed myofilament loss and an increased number of giant mitochondria, but no sarcomere disarray. Northern blotting showed that gene expression had been reprogrammed in the left ventricle of transgenic mice. Expression of fetal-type genes such as prepro–atrial natriuretic factor and β-myosin heavy chain were increased, but voltage-dependent calcium channel messenger RNA expression was decreased in the left ventricle of transgenic mice compared with that of wild-type mice. Conclusions: IL-1 may cause structural and functional alterations in cardiac myocytes.