Role of thioredoxin-interacting protein in mediating endothelial dysfunction in hypertension.

Excessive oxidative stress is a major causative factor of endothelial dysfunction in hypertension. As an endogenous pro-oxidant, thioredoxin-interacting protein (TXNIP) contributes to oxidative damage in various tissues. The present study aimed to investigate the role of TXNIP in mediating endothelial dysfunction in hypertension. In vivo, an experimental model of acquired hypertension was established with two-kidney, one-clip (2K1C) surgery. The expression of TXNIP in the vascular endothelial cells of multiple vessels was significantly increased in hypertensive rats compared with sham-operated rats. Resveratrol, a TXNIP inhibitor, suppressed vascular oxidative damage and increased the expression and activity of eNOS in the aorta of hypertensive rats. Notably, impaired endothelium-dependent vasodilation was effectively improved by TXNIP inhibition in hypertensive rats. In vitro, we observed that Ang II increased the expression of TXNIP in primary human aortic endothelial cells (HAECs) and that TXNIP knockdown by RNA interference alleviated cellular oxidative stress damage and mitigated the impaired eNOS activation and intracellular nitric oxide (NO) production observed in Ang II-treated HAECs. However, inhibiting thioredoxin (TRX) with PX-12 completely blunted the protective effect of silencing TXNIP. In addition, TXNIP knockdown facilitated TRX expression and promoted TRX nuclear translocation to further activate AP1 and REF1. TRX overexpression exhibited favorable effects on eNOS/NO homeostasis in Ang II-treated HAECs. Thus, TXNIP contributes to oxidative stress and endothelial dysfunction in hypertension, and these effects are dependent on the antioxidant capacity of TRX, suggesting that targeting TXNIP may be a novel strategy for antihypertensive therapy.

Chemerin Regulates the Proliferation and Migration of Pulmonary Arterial Smooth Muscle Cells via the ERK1/2 Signaling Pathway.

Pulmonary arterial hypertension (PAH) is an incurable disease with high mortality. Chemerin has been found to be associated with pulmonary hypertension (PH). However, the specific role of chemerin in mediating PH development remains unclear. This study aimed to elucidate the regulatory effects and the underlying mechanism of chemerin on PH and to investigate the expression levels of chemerin protein in plasma in PAH patients. In vivo, two animal models of PH were established in rats by monocrotaline (MCT) injection and hypoxia. We found that the expression levels of chemerin and its receptor, chemokine-like receptor 1 (CMKLR1), were significantly upregulated in the lungs of PH rats. Primary cultured pulmonary arterial smooth muscle cells [(PASMCs) (isolated from pulmonary arteries of normal healthy rats)] were exposed to hypoxia or treated with recombinant human chemerin, we found that CMKLR1 expression was upregulated in PASMCs in response to hypoxia or chemerin stimulation, whereas the exogenous chemerin significantly promoted the migration and proliferation of PASMCs. Notably, the regulatory effects of chemerin on PASMCs were blunted by PD98059 (a selective ERK1/2 inhibitor). Using enzyme linked immunosorbent assay (ELISA), we found that the protein level of chemerin was also markedly increased in plasma from idiopathic pulmonary arterial hypertension (IPAH) patients compared to that from healthy controls. Moreover, the diagnostic value of chemerin expression in IPAH patients was determined through receiver operating characteristic (ROC) curve analysis and the result revealed that area under ROC curve (AUC) for plasma chemerin was 0.949. Taken together, these results suggest that chemerin exacerbates PH progression by promoting the proliferation and migration of PASMCs via the ERK1/2 signaling pathway, and chemerin is associated with pulmonary hypertension.

Leonurine Attenuates Myocardial Fibrosis Through Upregulation of miR-29a-3p in Mice Post-myocardial Infarction.

ABSTRACT: Myocardial fibrosis (MF) is a pathological process that accelerates cardiac remodeling in myocardial infarction (MI), and miR-29 has become one of the foci of research into MF. As an alkaloid extracted from Herba leonuri, leonurine (LE) has been found to be an effective natural active ingredient for inhibiting fibrosis in many preclinical experiments. However, whether LE protects against MF after MI through modifying miR-29 remains unclear. The present study aimed to investigate the therapeutic effects of LE on MF, and to elucidate the underlying mechanisms involved. A mouse model of MI was established, followed by administration of LE for 4 weeks. We found that LE effectively improved cardiac function, and attenuated fibrosis and cardiac remodeling in mice post-MI. In vitro, LE simultaneously inhibited proliferation and migration of neonatal mouse cardiac fibroblasts (CFs) exposed to angiotensin II (Ang II), and the activation of collagen synthesis and myofibroblast generation was markedly suppressed by LE. Notably, we found that all mature miR-29 family members were downregulated in the myocardial tissues of mice post-MI, whereas LE significantly upregulated miR-29a-3p expression, and such upregulation was also detected in LE-treated CFs under Ang II stimulation. Knockdown of miR-29a-3p by a specific miRNA inhibitor upregulated the protein levels of TGF-ß, collagen III, and collagen I in CFs, and completely reversed the antifibrotic effects of LE on CFs. Our study suggests that LE exerts cardioprotective effects against MF, possibly through the upregulation of miR-29a-3p.