Suppression of tissue inhibitors of metalloproteinases may reverse severe pulmonary arterial hypertension

Natural Products for the Treatment of Pulmonary Hypertension: Mechanism, Progress, and Future Opportunities

Pulmonary hypertension (PH) is a lethal disease due to the remodeling of pulmonary vessels. Its pathophysiological characteristics include increased pulmonary arterial pressure and pulmonary vascular resistance, leading to right heart failure and death. The pathological mechanism of PH is complex and includes inflammation, oxidative stress, vasoconstriction/diastolic imbalance, genetic factors, and ion channel abnormalities. Currently, many clinical drugs for the treatment of PH mainly play their role by relaxing pulmonary arteries, and the treatment effect is limited. Recent studies have shown that various natural products have unique therapeutic advantages for PH with complex pathological mechanisms owing to their multitarget characteristics and low toxicity. This review summarizes the main natural products and their pharmacological mechanisms in PH treatment to provide a useful reference for future research and development of new anti-PH drugs and their mechanisms.

Activation of extracellular signal-regulated kinase 1/2 and Sp1 may contribute to the expression of tissue inhibitor of metalloproteinases-1 induced by transforming growth factor-β1 in human pulmonary arterial smooth muscle cells

BACKGROUND AIMS

Tissue inhibitor of metalloproteinases-1 (TIMP-1) plays an important role in the development of pulmonary arterial hypertension. However, the molecular regulatory mechanisms of TIMP-1 in the pulmonary arteries are not fully understood, especially in human pulmonary arterial smooth muscle cells (HPASMCs). We investigated the signaling pathway involved in the regulation of TIMP-1 in HPASMCs induced by transforming growth factor (TGF)-β1.

METHODS

Cultured HPASMCs were incubated with different concentrations of TGF-β1 (0-40 ng/mL) for 24 h or with 10 ng/mL TGF-β1 for different times (1-48 h).

RESULTS

Western blot, real-time polymerase chain reaction and enzyme-linked immunosorbent assay analyses showed that TGF-β1 enhanced the expression and secretion of TIMP-1 in a time-dependent and dose-dependent fashion. TGF-β1 could phosphorylate two of the three mitogen-activated protein kinases-extracellular signal-regulated kinase 1/2 (ERK1/2) and p38, but not c-Jun NH2-terminal kinase. Of these kinases, only the inhibition of ERK1/2 by U0126, which was a specific inhibitor of mitogen-activated protein kinase/ERK1/2, effectively blocked the TGF-β1-induced expression of TIMP-1. Mithramycin, an inhibitor of Sp1 transcription factor, also significantly inhibited the expression of TIMP-1. Additionally, electrophoretic mobility shift assay showed that TGF-β1 could up-regulate the DNA-binding activity of Sp1 and that U0126 and mithramycin could effectively inhibit these events.

CONCLUSIONS

TGF-β1 could stimulate the expression and secretion of TIMP-1 in HPASMCs in a time-dependent and dose-dependent fashion, and ERK1/2 and Sp1 signaling pathways might be involved in these activities.

Involvement of matrix metalloproteinase-2 in medial hypertrophy of pulmonary arterioles in broiler chickens with pulmonary arterial hypertension

Medial hypertrophy of pulmonary arterioles during pulmonary arterial hypertension (PAH) in humans is associated with enhanced proliferation of smooth muscle cells (SMCs). Elevated matrix metalloproteinase (MMP)-2 has been found in pulmonary artery SMCs (PA-SMCs) in humans with idiopathic PAH, leading to the hypothesis that MMP-2 contributes to the proliferation and migration of vascular SMCs in the pathogenesis of PAH. Rapidly growing meat-type (broiler) chickens provide a model of spontaneous PAH. The present study was conducted to determine whether MMP-2 is involved in the medial hypertrophy of pulmonary arterioles in this model. Cultured PA-SMCs from normal birds were used to evaluate the effect of MMPs on cell proliferation. Gelatin zymography showed that endothelin (ET)-1-induced proliferation of PA-SMCs was concomitant with increased pro- and active MMP-2 production. Reverse transcription PCR demonstrated upregulation of MMP-2 mRNA. However, PA-SMC proliferation was inhibited by the MMP inhibitors doxycycline and cis-9-octadecenoyl-N-hydroxylamide. In vivo experiments revealed a significant increase of MMP-2 expression in hypertrophied pulmonary arterioles of PAH broiler chickens, which was positively correlated with wall thickness and medial hypertrophy. MMP-2 may contribute to medial hypertrophy in pulmonary arterioles during PAH in broiler chickens by enhancing the proliferation of vascular SMCs.