Our present study showed that exogenous HMGB1 stimulated PASMC proliferation in vitro; serum HMGB1 levels were increased in the MCT-induced rat PAH model, and pharmacological inhibition of HMGB1 attenuated pulmonary vascular remodeling and ameliorated pulmonary hypertension, which are consistent with previous studies (28, 34, 35). This evidence concerns the gene HMGB1 and pulmonary arterial hypertension.