Mechanism of Tetrandrine in Ameliorating Hypoxic Pulmonary Hypertension Vascular Remodeling through Transcriptomics and Metabolomics.

Abstract

Background: Tetrandrine (TET) demonstrates therapeutic potential for hypoxic pulmonary hypertension (HPH); however, its precise pharmacological mechanisms remain unclear. In this study, we aimed to investigate the effects of TET on pulmonary vascular remodeling (PVR) in HPH and elucidate the molecular pathways through which TET ameliorates HPH.

Methods: We established a rat model of HPH and evaluated the therapeutic effects of TET by measuring hemodynamic parameters, assessing right ventricular hypertrophy, and analyzing pathological changes in lung tissue. To explore the molecular mechanisms, we carried out comprehensive analyses using transcriptome and untargeted metabolomics technologies to examine the impact of TET on gene expression and metabolite profiles in the lung tissue of HPH rats. Using data from these multiomics analyses, we performed biochemical assays, immunofluorescence staining, and Western blotting to validate the effects of TET on vasoconstriction and angiogenesis-related factors. These experiments provide further evidence of the anti-HPH and anti-PVR properties of TET.

Results: TET intervention significantly reduced hemodynamic parameters, including mean pulmonary arterial pressure (mPAP) and right ventricular systolic pressure (RVSP), as well as right ventricular hypertrophy indices, such as the right ventricular hypertrophy index (RVHI) and right ventricle-to-body weight ratio (RV/BW), in HPH rats. TET inhibited smooth muscle cell proliferation and alleviated pathological changes in lung tissue. Transcriptome and metabolome analyses revealed that genes affected by TET intervention were enriched in pathways related to PVR, including those involved in endothelial and smooth muscle cell proliferation, angiogenesis, and blood vessel morphogenesis. Metabolites were predominantly associated with the arachidonic acid (AA) metabolism pathway. Differentially expressed genes included Cyp4a1, Cyp4a3, Cyp2u1, and Alox15. Validation experiments demonstrated that TET upregulated ALOX15 protein expression and downregulated CYP4A and CYP2U1 proteins, modulating levels of arachidonate metabolites 20-HETE and 15(S)-HPETE. We further observed that TET reduced the levels of PVR markers, including endothelin-1 (ET-1) secretion, while increasing nitric oxide (NO) release. TEt also decreased the expression of cell proliferation markers PCNA and Ki-67 and elevated the endothelial marker CD31. Moreover, TET intervention suppressed angiogenic and vasoconstrictive factors, such as MMP-9, TGF-β1, IGF2, and PDGF-B, while enhancing levels of FGF9 and NOS3.

Conclusion: Our findings highlight the protective effects of TET on lung tissue in HPH mediated through the regulation of 15(S)-HPETE and 20-HETE within the arachidonic acid metabolism pathway. This regulation inhibits pulmonary angiogenesis and vasoconstriction, ultimately improving PVR in HPH.