Conditional Cardiac Overexpression of Endothelin-1 Induces Inflammation and Dilated Cardiomyopathy in Mice

Abstract

Background— Myocardial expression of endothelin-1 (ET-1) and its receptors ET A and ET B is increased in heart failure. However, the role of ET-1 and its signaling pathways in the pathogenesis of myocardial diseases is unclear. Methods and Results— Human ET-1 cDNA was placed downstream of a promoter responsive to a doxycycline (DOX)-regulated transcriptional activator (tTA). This line (ET + ) was bred with one harboring cardiac myocyte-restricted expression of tTA (αMHC-tTA). Myocardial ET-1 peptide levels were significantly increased in binary transgenic (BT, ET + /tTA + ) compared with nonbinary transgenic (NBT, ET + /tTA − ; ET − /tTA + ; ET − /tTA − ) or DOX-treated BT littermates (40.1±4.7 versus 2.6±1.2 fmol/mL, P <0.003). BT mice demonstrated progressive mortality between 5 and 11 weeks after DOX withdrawal, associated with left ventricular dilatation and contractile dysfunction (peak +dP/dT, 4673±468 versus 5585±658 mm Hg/s, P <0.05). An interstitial inflammatory infiltrate, including macrophages and T lymphocytes, was evident in the myocardium of BT mice, associated with sequential increases in nuclear factor-κB translocation and expression of tumor necrosis factor-α, interferon-γ, interleukin-1 and interleukin-6. Significant prolongation of survival was observed with the combined ET A /ET B antagonist LU420627 (n=8, P <0.05) in BT mice but not the ET A -selective antagonist LU135252 (n=5, P =0.9), consistent with an important role for ET B in this model. Conclusions— These are the first data to demonstrate that cardiac overexpression of ET-1 is sufficient to cause increased expression of inflammatory cytokines and an inflammatory cardiomyopathy leading to heart failure and death.