TLR4 and pulmonary arterial hypertension: Although the inhibition of HMGB1 reduces the right ventricular systolic pressure and pulmonary vascular remodeling in an adult rat model of hypoxia-induced pulmonary arterial hypertension (PAH) by blocking the interaction between HMGB1 and the TLR4 adaptor MD2, little is known about the effects of HMGB1-mediated inflammation on pulmonary vasculature in developing animals 33.