Genistein Therapy Reverses Lung Inflammation and Fibrosis during Severe Pulmonary Hypertension through Estrogen Receptor Beta

Abstract

Pulmonary Hypertension (PH) is a disease of increasing pulmonary arterial pressure characterized by extensive lung inflammation and fibrosis. We have previously shown that Genistein, a soy isoflavone, can rescue severe PH. Since Genistein is a selective Estrogen Receptor Beta agonist, here we examined whether Genistein can reverse fibrosis and inflammation induced by PH via an Estrogen Receptor Beta dependent mechanism. PH was established by treating male rats with monocrotaline (MCT, 60mg/kg, s.c.). At day 21 when severe PH was established, rats were treated with 10 day Genistein therapy (Gen group), Genistein therapy in the presence of selective Estrogen Receptor β antagonist PHTPP (Gen+PHTPP group), or were left untreated to develop right ventricular failure (RVF group). RVF animals developed severe pulmonary hypertension (RVP=72.96±1.39mmHg vs 31.15±0.56 mmHg in CTRL; RVEF=28.76±0.79% vs 66.22±1.40% in CTRL, all p<.05). Genistein therapy restored these abnormalities (RVEF=65.67±1.08%, RVP = 43.34±4.08 mmHg, p<0.05 vs RVF). Interestingly, in the presence of Estrogen Receptor Beta antagonist PHTPP, Genistein failed to rescue these animals (RVP=61.22±4.40, RVEF=42.27±2.7%, p=n.s. vs RVF). Masson's Trichrome staining revealed extensive lung fibrosis in RVF group, which was also restored with Gen therapy. Again, Gen+PHTPP group showed no reversal of pulmonary fibrosis. Immunoperoxidase staining showed an increase in ED-1 positive cells in the lung of RVF-group indicating increased inflammation. This change was reversed entirely by Genistein therapy. RT PCR also revealed that pro-inflammatory molecules TNFα and IL-1β were both elevated more than 2-fold in the lung of RVF animals and reversed with Genistein therapy (all p<0.05). Interestingly, Gen+PHTPP animals still showed significantly elevated ED-1 positive cells in the lung as well as elevated TNFα and IL1β (all p=n.s. vs RVF). These results suggest that genistein induced reversal of lung inflammation and fibrosis during pulmonary hypertension is mediated through Estrogen Receptor β.