[Junren Bufei Yixin Granules attenuates hypoxic pulmonary hypertension via PTBP1/PKM2 signaling pathway]

This study is aimed to investigate the therapeutic effects of Junren Bufei Yixin Granules(JRBF) on hypoxic pulmonary hypertension(HPH) and explore the therapeutic mechanism through the polypyrimidine tract-binding protein 1(PTBP1)/pyruvate kinase isozyme type M2(PKM2) signaling pathway. Sixty SPF-grade C57BL/6 male mice were randomized into normal, model, sildenafil, and low/medium/high-dose JRBF groups. HPH was induced by hypoxic exposure(10% O_2, 8 h/day) for 4 weeks. The right ventricular systolic pressure(RVSP) was measured by right cardiac catheterization. Echocardiography was employed record the pulmonary artery acceleration time(PAAT), pulmonary ejection time(PET), tricuspid annular plane systolic excursion(TAPSE), and right ventricular anterior wall thickness at diastole(RVAWd). The histopathological changes were observed by hematoxylin-eosin(HE) and Masson staining. Western blot was employed to measure the expression levels of PTBP1, PKM2, and PKM1 in the lung tissue. The immunofluorescence assay was employed to detect the co-localization of PTBP1 with the marker alpha-smooth muscle actin(α-SMA) of pulmonary arterial smooth muscle cells(PASMCs). The lactate assay kit was used to measure the lactate levels in the serum and lung tissue. In the cell experiments, the hypoxia model was established by exposing human pulmonary artery smooth muscle cells(hPASMCs) to 1% O_2 for 48 h. The optimal(10%) JRBF concentration for intervention was determined by the cell-counting kit-8(CCK-8). The cell proliferation(EdU), migration(Transwell), PTBP1/PKM2/PKM1, and lactate production were analyzed. The results showed that JRBF significantly reduced the RVSP, improved the PAAT/PET ratio and TAPSE, and attenuated pulmonary arteriolar remodeling and myocardial fibrosis. Furthermore, JRBF suppressed PTBP1 and PKM2 expression and reduced the lactate accumulation in the lung tissue and PASMCs. The cell experiment results showed that the 10% JRBF-containing serum inhibited the proliferation and migration of hPASMCs, while decreasing the PTBP1/PKM2 expression and lactate production. In conclusion, JRBF mitigates HPH progression by suppressing the PTBP1/PKM2 axis and restoring the glycolytic flux.