The effect of honokiol on pulmonary artery endothelium cell autophagy mediated by cyclophilin A in hypoxic pulmonary arterial hypertension.

Abnormal autophagy plays critical roles in the structure and function of the pulmonary vasculature. Cyclophilin A (CyPA) can be secreted from cells in response to hypoxia and oxidative stress, which are involved in inducing autophagy and regulating the function of endothelial cells in pulmonary arterial hypertension. Honokiol is a small molecule natural compound; it has many bioactivities, such as antitumor, anti-inflammatory, antioxidant and antiangiogenic properties, but how honokiol mediates autophagy in pulmonary arterial hypertension is unclear. Rat' lungs gavaged with honokiol were examined for autophagy via western blot and fluorescence microscopy. In addition, western blot, quantitative RT-PCR and immunofluorescence were employed to test the expression of CyPA and autophagy markers in pulmonary artery endothelial cells (PAECs). Small interfering RNA targeting CyPA (si-CyPA) was used to knockdown the expression of CyPA, and then autophagy was tested with mRFP-GFP-LC3 fluorescence microscopy and western blot. We found that honokiol could reduce the expression of CyPA and autophagy markers in vivo and in vitro. Furthermore, autophagy was also down-regulated by si-CyPA. Taken together, we revealed a novel mechanism by which honokiol regulates autophagy. The results revealed that honokiol can alleviate autophagy and pulmonary arterial hypertension regulated by CyPA in PAECs.

Targeted metabolomics combined with network pharmacology to reveal the protective role of luteolin in pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a progressive disease that significantly endangers human health, where metabolism may drive pathogenesis: a shift from mitochondrial oxidation to glycolysis occurs in diseased pulmonary vessels and the right ventricle. An increase in pulmonary vascular resistance in patients with heart failure with a preserved ejection fraction portends a poor prognosis. Luteolin exists in numerous foods and is marketed as a dietary supplement assisting in many disease treatments. However, little is known about the protective effect of luteolin on metabolism disorders in diseased pulmonary vessels. In this study, we found that luteolin apparently reversed the pulmonary vascular remodeling of PAH rats by inhibiting the abnormal proliferation of pulmonary artery smooth muscle cells (PASMCs). Moreover, network pharmacology and metabolomics results revealed that the arachidonic acid pathway, amino acid pathway and TCA cycle were dysregulated in PAH. A total of 14 differential metabolites were significantly changed during the PAH, including DHA, PGE2, PGD2, LTB4, 12-HETE, 15-HETE, PGF2α, and 8-iso-PGF2α metabolites in the arachidonic acid pathway, and L-asparagine, oxaloacetate, N-acetyl-L-ornithine, butane diacid, ornithine, glutamic acid metabolites in amino acid and TCA pathways. However, treatment with luteolin recovered the LTB4, PGE2, PGD2, 12-HETE, 15-HETE, PGF2α and 8-iso-PGF2α levels close to normal. Meanwhile, we showed that luteolin also downregulated the gene and protein levels of COX 1, 5-LOX, 12-LOX, and 15-LOX in the arachidonic acid pathway. Collectively, this work highlighted the metabolic mechanism of luteolin-protected PAH and showed that luteolin would hold great potential in PAH prevention.