The pathogenesis of pulmonary hypertension (PH), a cardiopulmonary disorder associated with significant morbidity and mortality, involves endothelial dysfunction with increased production of vasoconstrictors, e.g. endothelin-1 (ET-1). Although existing PH therapies are designed to attenuate these derangements, the poor outcomes in PH indicate an urgent need for novel therapeutic strategies. Recent studies indicate that stimulating peroxisome proliferator-activated receptor gamma (PPARg) with thiazolidinedione (TZD) ligands attenuates PH in several experimental models, whereas reduced PPARg is associated with PH. Preliminary and published data demonstrate that PPARg ligands attenuate hypoxia-induced ET-1 levels and PH in part by suppressing NF-kB activation. Our preliminary data also indicate that hypoxia reduces miR-98 levels to increase ET-1 expression and that PPARg activation restores miR-98 levels to reduce ET-1 expression. Therefore, we hypothesize that PPARg reduces ET-1 in PH by attenuating NF-kB and enhancing miR-98 levels. Aim 1 will determine if PPARg activation attenuates hypoxia-induced ET-1 expression and PH by inhibiting NF-kB. Aim 2 will determine if PPARg regulates miR-98 to modulate hypoxia-induced ET-1 levels. Each aim will employ a combination of complementary in vitro and in vivo models. In vivo studies will examine mouse models of PH caused by treatment with hypoxia VEGFR antagonist wherein selected animals are treated with PPARg ligands or miR-98 mimic. Alterations in ET-1 and miR-98 levels will be determined in whole lung, in laser capture microscopy-selected vascular profiles, and in isolated lung microvascular endothelial cells using qRT-PCR, Western blotting, or immunostaining. PH will be assessed by measurements of pulmonary vascular remodeling and right ventricular systolic pressure and hypertrophy. In vitro studies will employ human pulmonary artery endothelial cells treated with hypoxia to examine PPARg-mediated regulation of NF-kB and miR-98 in enhanced expression of ET-1 and cell proliferation. Gain and loss of PPARg, NF-kB, and miR-98 strategies will be used to determine if the observed effects of TZD ligands are PPARg receptor-dependent and if NF-kB and miR-98 are critical mediators of hypoxic ET-1 induction. The results of these pre-clinical studies will: a) clarify molecular mechanisms by which PPARg regulates ET-1, and b) inform future clinical trials examining PPARg as a novel therapeutic target in PH.
|Program type||Scientist Development Grant|
|Effective start/end date||01/01/2013 → 12/31/2016|