Hypoxic Pulmonary Hypertension In Rats Research Articles

Tibetan Mesenchymal Stem Cell-derived Exosomes Alleviate Pulmonary Vascular Remodeling in Hypoxic Pulmonary Hypertension Rats.

Hypoxic pulmonary hypertension (HPH) is characterized by progressive pulmonary vasoconstriction, vascular remodeling, and right ventricular hypertrophy, causing right heart failure. This study aimed to investigate the therapeutic effects of exosomes from Tibetan umbilical cord mesenchymal stem cells on HPH via the TGF-β1/Smad2/3 pathway, comparing them with exosomes from Han Chinese individuals. An HPH rat model was established in vivo, and a hypoxia-induced injury in the rat pulmonary artery smooth muscle cells (rPASMCs) was simulated in vitro. Exosomes from human umbilical cord mesenchymal stem cells were administered to HPH model rats or added to cultured rPASMCs. The therapeutic effects of Tibetan-mesenchymal stem cell-derived exosomes (Tibetan-MSC-exo) and Han-mesenchymal stem cell-derived exosomes (Han-MSC-exo) on HPH were investigated through immunohistochemistry, Western blotting, EdU, and Transwell assays. The results showed that Tibetan-MSC-exo significantly attenuated pulmonary vascular remodeling and right ventricular hypertrophy in HPH rats compared with Han-MSC-exo. Tibetan-MSC-exo demonstrated better inhibition of hypoxia-induced rPASMCs proliferation and migration. Transcriptome sequencing revealed upregulated genes (Nbl1, Id2, Smad6, and Ltbp1) related to the TGFβ pathway. Nbl1 knockdown enhanced hypoxia-induced rPASMCs proliferation and migration, reversing Tibetan-MSC-exo-induced downregulation of TGFβ1 and p-Smad2/3. Furthermore, TGFβ1 overexpression hindered the therapeutic effects of Tibetan-MSC-exo and Han-MSC-exo on hypoxic injury. These findings suggest that Tibetan-MSC-exo favors HPH treatment better than Han-MSC-exo, possibly through the modulation of the TGFβ1/Smad2/3 pathway via Nbl1.

Fermented Cordyceps Powder Attenuates Inflammation and Pulmonary Arterioles Remodeling by Inhibiting p38 MAPK/NF-κB Signaling Pathway in Hypoxic Pulmonary Hypertension Rats

Background Pulmonary hypertension (PH) is a pulmonary vascular disease caused by a variety of causes and has a poor prognosis. Hypoxic pulmonary hypertension (HPH) is one of the types of PH. Cordyceps sinensis could treat a variety of lung diseases; its pharmacological active ingredients mainly include cordycepin, nucleosides, cordyceps polysaccharides, sterols, and amino acids. Fermented cordyceps powder (FCP) is an alternative to C. sinensis. In order to investigate the effect of FCP on HPH in rats, we established the HPH rat model. Materials and Methods Forty-two male Sprague–Dawley (SD) rats were randomly divided into a control group, hypoxia group, hypoxia + FCP (0.1 g.kg−1.d−1), hypoxia + FCP (0.2 g.kg−1.d−1), hypoxia + FCP (0.4 g.kg−1.d−1), and hypoxia + sildenafil (30 mg.kg−1.d−1) group. Except for the control group, the other five groups of rats were fed in the hypobaric chamber. The corresponding dose was given by intragastric administration, once a day, for 28 days. The mean pulmonary arterial pressure (mPAP) and right ventricle hypertrophy index (RVHI) were measured; hematological parameters white blood cells (WBC), neutrophils (Neu), Lymphocytes (Lym), monocytes (Mon), red blood cells (RBC), hemoglobin (HGB), hematocrit (HCT), and platelets (PLT) levels were detected; serum levels of interleukin-1β (IL-1β) and interleukin-6 (IL-6) were determined by enzyme-linked immunosorbent assay (ELISA); the morphological changes of pulmonary arterioles were observed by hematoxylin and eosin (H&E) staining, and the vascular remodeling indexes, vessel wall thickness as a percentage of vascular outer diameter (WT%), vascular wall area as a percentage of total vessel area (WA%), and lumen area as a percentage of the total vascular area (LA%) were calculated; the protein expression levels of IL-1β, IL-6, p-p38, p38, p-IκBα, IκBα, p-p65, and p65 were determined by western blotting. Results FCP could significantly downregulate mPAP, improve pulmonary arteriole remodeling, and reduce the serum levels of IL-1β and IL-6 in HPH rats. In addition, FCP downregulated the protein levels of IL-1β, IL-6, p-p38, p-IκBα, and p-p65. Conclusion FCP could alleviate mPAP and vascular remodeling in HPH rats. Its mechanism could be through inhibiting the p38 mitogen-activated protein kinase (MAPK)/nuclear factor-kappa B (NF-κB) signaling pathway and by downregulating the expression of inflammatory factors. Our study might provide a research basis for the therapeutic potential of FCP in HPH.

Preventive effect of LCZ696 on hypoxic pulmonary hypertension in rats via regulating the PI3K/AKT signaling pathway

Hypoxic pulmonary hypertension (HPH) is a devastating disease worldwide; however, effective therapeutic drugs are lacking. This study investigated the effects and underlying mechanisms of LCZ696 treatment on hypoxia-induced pulmonary hypertension. Male Sprague-Dawley (SD) rats were kept in a hypobaric chamber with an oxygen concentration of 5% for 4 weeks. Rats were treated with either LCZ696 (18 mg/kg, 36 mg/kg, and 72 mg/kg) or sildenafil. The mean pulmonary artery pressure (mPAP), right ventricle hypertrophy index (RVHI), and lung system index were measured. Hematoxylin-eosin (HE) staining, Masson staining, and immunofluorescence staining were used for histological analysis. Enzyme linked immunosorbent assay (ELISA) kits were used to determine the concentrations of inflammatory and hypoxia-related factors. Western blotting was used to examine the expression of apoptotic and PI3K/AKT signaling pathway proteins in rat lung tissue. Hypoxia increased mPAP, RVHI, and lung system index and induced pulmonary vascular remodeling, pulmonary arteriomyosis, and pulmonary artery fibrosis. LCZ696 treatment reduced the increase in mPAP, RVHI, and the lung system index and ameliorated the induced pathological changes. Hypoxia upregulated expression of NF-kB, TNF-α, IL-6, HIF-1α, and Vascular endothelial growth factor (VEGF), decreased the ratio of Bax/Bcl-2, and activated the PI3K/AKT signaling pathway in lung tissue, and these effects were partially reversed by treatment with LCZ696. These results demonstrated that LCZ696 can ameliorate hypoxia-induced HPH by suppressing apoptosis, inhibiting the inflammatory response, and inhibiting the PI3K/AKT signaling pathway. It provides a reference for clinical rational drug use and lays a foundation for the study of HPH therapeutic drugs.

PDK1 upregulates PINK1-mediated pulmonary endothelial cell mitophagy during hypoxia-induced pulmonary vascular remodeling.

Hypoxic pulmonary hypertension (HPH) is a complication of lung diseases with pulmonary vascular remodeling, although the underlying molecular mechanisms have not been fully elucidated. This study investigated the underlying molecular events by using a rat HPH model and primary pulmonary microvascular endothelial cells (PMVECs). This study first established a rat HPH model and cultured PMVECs for transmission electron microscopic analysis and manipulation of 3-phosphoinositide-dependent protein kinase 1 (PDK1) or phosphatase and tensin homolog-induced kinase 1 (PINK1) expression in vitro. After that, the cell viability was assessed and the expression of different proteins was assayed using cell viability and western blot assays, respectively. Reactive oxygen species production, apoptosis, NLR family pyrin domain containing 3 (NLRP3) expression, and the levels of interleukin (IL)-1β, IL-6, and IL-8 were also assessed, while the interaction of PDK1 and PINK1 was determined using co-immunoprecipitation/western blot assays. Hypoxia induced mitophagy in the PMVECs and upregulated PINK1/Parkin expression, whereas knockdown of PINK1 expression under hypoxic conditions inhibited cell proliferation but induced endothelial cell apoptosis in vitro, decreased reactive oxygen species production and NLRP3 expression, and reduced the levels of inflammatory factors in PMVECs. However, hypoxia induced PDK1 expression, whereas knockdown of PDK1 downregulated PINK1 expression. Furthermore, treatment of the model rats with the PDK1 inhibitor dichloroacetate (DCA) was able to decrease PINK1 expression. In addition, the PDK1 and PINK1 proteins could interact with each other in the mitochondria of PMVECs to regulate the cell viability. This study revealed that PDK1 induced PMVEC proliferation but inhibited their apoptosis to participate in pulmonary vascular remodeling, ultimately leading to HPH through regulation of PINK1-mediated mitophagy signaling. Therefore, PINK1 is a novel therapeutic target for the control of HPH.

Weighted gene co-expression network analysis reveals the hub genes associated with pulmonary hypertension.

Pulmonary hypertension (PH) is a cardiopulmonary vascular disease that acutely endangers human health and can be fatal. It progresses rapidly and has a high mortality rate. Its pathophysiology is complicated and still not completely elucidated; therefore, achieving treatment breakthroughs are difficult. In this study, data from 58 normal controls and 135 patients with PH were extracted from the GSE24988, GSE113439, and GSE117261 datasets in the Gene Expression Omnibus (GEO) database and screened for differentially expressed genes (DEGs). In addition, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed. Weighted gene co-expression network analysis (WGCNA) was used to identify the key modules and hub genes associated with PH. Eight PH-associated hub genes were identified. Furthermore, correlation analysis between immune cell infiltration and hub genes was performed, and the receiver operating characteristic (ROC) curves showed that TARDBP had the best diagnostic efficacy. Moreover, a rat hypoxic pulmonary hypertension (HPH) model was generated, and the expression of hub genes in the lungs and pulmonary arteries of HPH rats was verified using western blotting assays. Our results showed that mTOR, PSMD2, RBM8A, SMARCA4, TARDBP, and UBXN7 were highly expressed in the lungs. In addition, EFTUD2, mTOR, RBM8A, SMARCA4, TARDBP, and UBXN7 were significantly upregulated, whereas DDB1 was significantly downregulated in the pulmonary arteries of HPH rats compared with those of controls. In conclusion, we identified PH hub genes with diagnostic and predictive value by performing WGCNA on data from the GEO database. Furthermore, we provided novel insights of PH that might be utilized to evaluate potential biomarker genes and therapeutic targets.

Histone lactylation driven by mROS-mediated glycolytic shift promotes hypoxic pulmonary hypertension.

Increased mitochondrial reactive oxygen species (mROS) and glycolysis have been established in pulmonary hypertension (PH). However, the effect of elevated mROS on glycolytic shift and how increased glycolysis promotes hypoxic pulmonary artery smooth muscle cell (PASMC) proliferation and vascular remodeling remain elusive. Here, we reported that hypoxia-induced mROS inhibit HIF-1α hydroxylation and further trigger PASMC glycolytic switch through the upregulated HIF-1α/PDK1&PDK2/p-PDH-E1α axis, which facilitates lactate accumulation and histone lactylation. Through H3K18la and HIF-1α ChIP-seq analysis, we found that the enhanced histone lactylation of HIF-1α targets, such as Bmp5, Trpc5, and Kit, promotes PASMC proliferation. Knockdown of Pdk1&2 blunts lactate production, histone lactylation marks, and PASMC proliferation. Moreover, pharmacological intervention with lactate dehydrogenase inhibitor diminishes histone lactylation and ameliorates PASMC proliferation and vascular remodeling in hypoxic PH rats. Taken together, this study provides proof of concept for anti-remodeling therapy through lactate manipulation.

Mice lacking 1,4,5-triphosphate inositol type III receptor demonstrate inhibition of hypoxic pulmonary hypertension

Hypoxic pulmonary hypertension (HPH) is a respiratory disease characterized by increased pulmonary vascular resistance and pulmonary arterial pressure. Persistent hypoxia alters the metabolic and transport functions of endothelial cells and promotes thrombosis and inflammation. Type 3 inositol-1,4,5-trisphosphate receptor (IP3R3) controls the release of calcium ions from the endoplasmic reticulum to the cytoplasm and mitochondria and is involved in cell proliferation, migration, and protein synthesis. In this study, we investigated the role and function of IP3R3 in HPH. The results showed that the expression level of IP3R3 was increased in pulmonary artery endothelial cells (PAECs) in a rat HPH model. The pulmonary artery pressure indices of IP3R3(−/−) mice with persistent hypoxia were significantly lower than those of HPH mice. The expression level of IP3R3 was significantly increased in hypoxia-treated PAECs. Knockdown of IP3R3 significantly inhibited the proliferation, migration and mesenchymal transition of PAECs induced by hypoxia. In conclusion, knockdown of IP3R3 can inhibit hypoxia-induced dysfunctions in PAECs, thus enabling IP3R3(−/−) mice to avoid HPH development. IP3R3 plays a key role in HPH and can be used as a potential target for the prevention and treatment of HPH.

Effect of Ligusticum Chuanxiong on Hypoxic Pulmonary Hypertension in Rats and Its Mechanism

Objective: To explore the mechanism of Chuanxiong in alleviating hypoxic pulmonary hypertension in rats by inhibiting pulmonary vascular remodeling. Methods: Thirty healthy and clean male SD rats weighing (180 - 220) g were randomly divided into three groups (n = 10): normoxia group (n), hypoxia group (H) and Chuanxiong group (L). Group N was fed in normoxic environment, and the other two groups were fed in hypoxic (9% 11% O2) environment for 4 weeks, 8 h/D, 6 days a week. Rats in group L were gavaged with Ligusticum chuanxiong solution diluted with normal saline at the concentration of 300 mg/kg, and rats in group H were gavaged with equal volume of normal saline. After 4 weeks, the mean pulmonary artery pressure was measured. After pulmonary perfusion, the right ventricular free wall and left ventricle plus ventricular septum were taken to measure the right ventricular hypertrophy index. The changes of pulmonary morphology and ultrastructure were observed under light microscope. Results: Compared with group n, the average pulmonary artery pressure and right ventricular hypertrophy index in the other two groups increased, and the thickening of pulmonary vascular wall was obvious under microscope (P < 0.01); compared with group H, the above changes in group L were reduced (P < 0.05). Conclusion: Ligusticum chuanxiong can relieve pulmonary artery pressure in rats by inhibiting pulmonary vascular remodeling.

Proteomic analysis reveals that Xbp1s promotes hypoxic pulmonary hypertension through the p-JNK MAPK pathway.

Hypoxic pulmonary hypertension (HPH) is characterized by elevated pulmonary artery resistance and vascular remodeling. Endoplasmic reticulum stress (ERS) is reported to be involved in HPH, but the underlying mechanisms remain uncertain. We found that Xbp1s, a potent transcription factor during ERS, was elevated in hypoxic-cultured rat PASMCs and lung tissues from HPH rats. Our in vitro experiments demonstrated that overexpressing Xbp1s can promote proliferation, cell viability, and migration and inhibit the apoptosis of PASMCs, while silencing Xbp1s led to the opposite. Through data-independent acquisition (DIA) mass spectrometry, we identified extensive proteomic alterations regulated by hypoxia and Xbp1s. Further validation revealed that p-JNK, rather than p-ERK or p-p38, was the downstream effector of Xbp1s. p-JNK inhibition reversed the biological effects of Xbp1s overexpression in vitro. In the animal HPH model, rats were randomly assigned to five groups: normoxia, hypoxia, hypoxia+AAV-CTL (control), hypoxia+AAV-Xbp1s (prevention), and hypoxia+AAV-Xbp1s (therapy). Adeno-associated virus (AAV) serotype 1-mediated Xbp1s knockdown in the prevention and therapy groups significantly reduced right ventricular systolic pressure, total pulmonary resistance, right ventricular hypertrophy, and the medial wall thickness of muscularized distal pulmonary arterioles; AAV-Xbp1s also decreased proliferating cell nuclear antigenexpression and increased apoptosis in pulmonary arterioles. Collectively, our findings demonstrated that the Xbp1s-p-JNK pathway is important in hypoxic vascular remodeling and that targeting this pathway could be an effective strategy to prevent and alleviate HPH development.

The m6A methyltransferase METTL3 promotes hypoxic pulmonary arterial hypertension via targeting PTEN

Abstract Background N6-methyladenosine (m6A) is the most prevalent internal RNA modification in mammal mRNAs. Accumulating evidence has indicated the crucial role of m6A modification in cardiovascular diseases including cardiac hypertrophy, heart failure, ischemic heart disease, vascular calcification, restenosis, and aortic aneurysm. However, the role of m6A methylation in the occurrence and development of hypoxic pulmonary hypertension (HPH) remains largely unknown. Purpose The present study aims to explore the role of key transferase METTL3, in the development of HPH. Methods Hypoxic rat models and pulmonary artery smooth muscle cells (PASMCs) and were used to research the METTL3-mediated m6A in HPH in vivo and in vitro. CCK-8, EdU, PCNA, transwell and TUNEL assay were performed to evaluate the proliferation, migration and apoptosis rates of PASMCs. m6A RNA Methylation Quantification Kit and m6A-qPCR were utilized to measure the total m6A level and m6A-PTEN mRNA expression. RNA immunoprecipitation and RNA pull down were used to detect the interaction between METTL3 and PTEN mRNA. The half-life of mRNA was detected through actinomycin D assay. Results Both METTL3 mRNA and protein were found abnormally upregulated in pulmonary arteries of HPH rats and hypoxia induced PASMCs. Furthermore, downregulation of METTL3 attenuated PASMCs proliferation and migration exposed to hypoxia. In addition, m6A binding protein YTHDF2 was found significantly increased in HPH group in vivo and in vitro. Mechanistically, YTHDF2 recognized METTL3 mediated m6A-PTEN mRNA and promoted the degradation of PTEN. Decreased PTEN led to over-proliferation of PASMCs through activation of PI3K/Akt signaling pathway. Conclusion METTL3/YTHDF2/PTEN axis exerts a significant role in hypoxia induced PASMCs proliferation, providing a novel therapeutic target for HPH. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): National Natural Science Foundation of China Figure 1

MicroRNA-137 Inhibited Hypoxia-Induced Proliferation of Pulmonary Artery Smooth Muscle Cells by Targeting Calpain-2.

The proliferation of pulmonary artery smooth muscle cells (PASMCs) is an important cause of pulmonary vascular remodeling in pulmonary hypertension (PH). It has been reported that miR-137 inhibits the proliferation of tumor cells. However, whether miR-137 is involved in PH remains unclear. In this study, male Sprague-Dawley rats were subjected to 10% O2 for 3 weeks to establish PH, and rat primary PASMCs were treated with hypoxia (3% O2) for 48 h to induce cell proliferation. The effect of miR-137 on PASMC proliferation and calpain-2 expression was assessed by transfecting miR-137 mimic and inhibitor. The effect of calpain-2 on PASMC proliferation was assessed by transfecting calpain-2 siRNA. The present study found for the first time that miR-137 was downregulated in pulmonary arteries of hypoxic PH rats and in hypoxia-treated PASMCs. miR-137 mimic inhibited hypoxia-induced PASMC proliferation and upregulation of calpain-2 expression in PASMCs. Furthermore, miR-137 inhibitor induced the proliferation of PASMCs under normoxia, and knockdown of calpain-2 mRNA by siRNA significantly inhibited hypoxia-induced proliferation of PASMCs. Our study demonstrated that hypoxia-induced downregulation of miR-137 expression promoted the proliferation of PASMCs by targeting calpain-2, thereby potentially resulting in pulmonary vascular remodeling in hypoxic PH.

Differences in the microcirculation disturbance in the right and left ventricles of neonatal rats with hypoxic pulmonary hypertension

Microcirculation disturbance is a crucial pathological basis of heart damage; however, microcirculation alterations induced by hypoxic pulmonary hypertension (HPH) remain unknown, and the left ventricle (LV) in HPH is conventionally ignored. Herein, we investigated the changes in the cardiac structure, function and microcirculation after HPH and further compared the differences between the right ventricle (RV) and LV. Using a neonatal rat model of HPH, we found RV myocardial hypertrophy, dysfunction and poor myocardial perfusion in HPH rats. Additionally, RV microcirculation disturbance manifested as the abnormal expression of endothelin-1/eNOS and increased expression of intercellular cell adhesion molecule-1 (ICAM-1) or E-selectin 3 days after hypoxia, followed by vascular inflammation, coronary arterial remodeling and microvascular sparseness. Impairment in LV vasodilation was detected in rats after 3 days of hypoxia; however, no obvious microvascular rarefaction or inflammatory reaction was observed in the LV. In conclusion, our results suggest that HPH mainly triggers RV microcirculation disturbances, causing low myocardial perfusion damage and cardiac dysfunction. Despite the differences in the RV and LV, their impaired microvascular function, mediated by endothelial cells, occurs almost simultaneously after HPH, earlier than cardiac functional or structural abnormalities.

Echinacoside prevents hypoxic pulmonary hypertension by regulating the pulmonary artery function

Hypoxic pulmonary hypertension (HPH) is a progressive and irreversible disease that reduces survival. Echinacoside is a phenylethanoid glycoside from Tibetan herbs known for its vasorelaxant effect and for inhibiting the proliferation of rat pulmonary arterial smooth muscle cells. This study aimed to investigate the effect of echinacoside on HPH. Sprague Dawley rats were housed in a hypobaric hypoxia chamber (4500 m) for 28 days to obtain the HPH model. Echinacoside (3.75, 7.5, 15, 30 and 40 mg/kg) was administered by intraperitoneal injection from the 1st to the 28th day. The mean pulmonary artery pressure (mPAP), right ventricular hypertrophy index, hemoglobin, hematocrit, red blood cell concentration and morphological change of pulmonary arteries were evaluated. Vascular perfusion assay was used to assess the pulmonary artery function. Echinacoside reduced mPAP, hemoglobin, hematocrit, right ventricular hypertrophy index and mean wall thickness% of pulmonary arteries in HPH rats. It significantly increased maximum vasoconstriction percentage of pulmonary arteries induced by noradrenaline in a dose-dependent manner. In addition, it improved the responsiveness of pulmonary arteries to acetylcholine and sodium nitroprusside. Therefore, Echinacoside might be an effective treatment against HPH, since it regulated pulmonary artery endothelium and smooth muscle layer function and improved the remodeling of pulmonary artery.

Reversal of Hypoxic Pulmonary Hypertension by Hypoxia-Inducible Overexpression of Angiotensin-(1-7) in Pulmonary Endothelial Cells

Hypoxia-induced pulmonary vascular constriction and structure remodeling are the main causes of hypoxic pulmonary hypertension. In the present study, an adeno-associated virus vector, containing Tie2 promoter and hypoxia response elements, was designed and named HTSFcAng(1-7). Its targeting, hypoxic inducibility, and vascular relaxation were examined in vitro, and its therapeutic effects on hypobaric hypoxia-induced pulmonary hypertension were examined in rats. Transfection of HTSFcAng(1-7) specifically increased the expression of angiotensin-(1-7) in endothelial cells in normoxia. Hypoxia increased the expression of angiotensin-(1-7) in HTSFcAng(1-7)-transfected endothelial cells. The condition medium from HTSFcAng(1-7)-transfected endothelial cells inhibited the hypoxia-induced proliferation of pulmonary artery smooth muscle cells, relaxed the pulmonary artery rings, totally inhibited hypoxia-induced early contraction, enhanced maximum relaxation, and reversed phase II constriction to sustained relaxation. In hypoxic pulmonary hypertension rats, treatment with HTSFcAng(1-7) by nasal drip adeno-associated virus significantly reversed hypoxia-induced hemodynamic changes and pulmonary artery-wall remodeling, accompanied by the concomitant overexpression of angiotensin-(1-7), mainly in the endothelial cells in the lung. Therefore, hypoxia-inducible overexpression of angiotensin-(1-7) in pulmonary endothelial cells may be a potential strategy for the gene therapy of hypoxic pulmonary hypertension.

The effect of activated κ-opioid receptor (κ-OR) on the role of calcium sensing receptor (CaSR) in preventing hypoxic pulmonary hypertension development

κ-opioid receptor (κ-OR) plays a key role in preventing hypoxic pulmonary hypertension (HPH) development after activated by exogenous agonist U50,488H. Calcium sensing receptor (CaSR) activation induces HPH by promoting vasoconstriction and vascular remodeling. The activated κ-OR is reported to inhibit the expression of CaSR in pulmonary artery smooth muscle cells (PASMCs). Thus, in this study, we aimed to explore the effect of activated κ-OR on the role of CaSR in preventing HPH development. An HPH rat model was constructed using Sprague-Dawley rats. Changes in mean pulmonary arterial pressure (mPAP) and right ventricular pressure (RVP) mediated by κ-OR agonist U50,488H and CaSR inhibitor NPS2143 were observed. The effects of CaSR agonist spermine and inhibitor NPS2143 on pulmonary artery tension were tested. The expression and localization of κ-OR and CaSR were measured in isolated PASMCs. A cell-counting kit-8 assay was performed to evaluate the effect of spermine in PASMC proliferation. Expression of proliferating cell nuclear antigen (PCNA), Erk, and p-Erk was evaluated by western blot analysis. Results showed that κ-OR and CaSR were co-expressed and colocalized in PASMCs under normoxic and hypoxic conditions. Interactions between κ-OR and CaSR were also observed. Spermine improved vasoconstriction in the pulmonary artery in HPH rats, which was abolished by U50,488H. RVP and mPAP were significantly increased in HPH rats under CaSR stimulation, but were significantly reduced when the rats were pretreated with U50,488H and NPS2143 (P < 0.01). Spermine treatment significantly promoted PASMC proliferation, which was significantly inhibited by U50,488H, p38 inhibitor SB203580, JNK inhibitor SP600125, Erk inhibitor SCH772984, and MEK inhibitor U0126, especially Erk inhibitor (P < 0.01). Spermine significantly increased PCNA and P-Erk expression in hypoxic conditions, which was inhibited by U50,488H and NPS2143. κ-OR stimulation prevented HPH development via the CaSR/MAPK signaling pathway.

Protective effects of resveratrol and SR1001 on hypoxia-induced pulmonary hypertension in rats

ABSTRACT Hypoxic pulmonary hypertension (HPH) is a fatal disease with limited therapeutic strategies. Combination therapy is regarded as the standard of care in PH and becoming widely used in clinical practice. However, many PH patients treated with combinations of available clinical drugs still have a poor prognosis. Therefore, identifying innovative therapeutic strategies is essential for PH. This study is designed to examine the effects of combined prevention with resveratrol and SR1001 on HPH in rats. The effects of combined prevention with resveratrol and SR1001 and each mono-prevention on the development of HPH, Th17 cells differentiation, expression of guanine nucleotide exchange factor-H1 (GEF-H1), Ras homolog gene family member A (RhoA) and Phosphorylated myosin phosphatase target subunit (MYPT1) were examined. HPH and RV hypertrophy occurred in rats exposed to hypoxia. Compared with normoxia group, the hypoxia group showed significantly increased ratio of Th17 cells. After treatment with resveratrol, HPH rats showed an obvious reduction of Th17 cells. SR1001 significantly reduced the increased p-MYPY1, RhoA, and GEF-H1 expression in the hypoxic rats. The mono-prevention with resveratrol or SR1001 significantly inhibited the Th17 cells differentiation, p-STAT3, p-MYPY1, RhoA, and GEF-H1 protein expression, which was further inhibited by their combination prevention. The combination of resveratrol and SR1001 has a synergistic interaction, suggesting that combined use of these pharmacological targets may be an alternative to exert further beneficial effects on HPH.

5-Aza-2′-deoxycytidine, a DNA methylation inhibitor, attenuates hypoxic pulmonary hypertension via demethylation of the PTEN promoter

Phosphatase and tensin homolog (PTEN) plays an important role in the pathogenesis of hypoxic pulmonary hypertension (HPH). A decrease in PTEN expression is associated with the hypermethylation of its promoter. However, whether the demethylation of the PTEN gene could attenuate HPH remains unknown. 5-Aza-2′-deoxycytidine (5-Aza-dC) is a DNA methyltransferase (DNMT) inhibitor. The present study was designed to investigate the effects and mechanisms of 5-Aza-dC on HPH. The proliferation, migration and apoptosis of rat pulmonary artery smooth muscle cells (PASMCs) induced by hypoxia and treated with 5-Aza-dC were detected. The expression of PTEN and DNMTs and the PTEN methylation status of PASMCs were detected. SD rats were randomly divided into normal group, hypoxia group and hypoxia + 5-Aza-dC group. The expression of PTEN was decreased, the expression of DNMTs was increased, and the methylation status of PTEN was increased in hypoxia-induced PASMCs. However, 5-Aza-dC can rescue the decreased PTEN, inhibit DNMT levels in a dose-dependent manner and suppress PTEN methylation. Furthermore, the demethylation of PTEN, which was induced by 5-Aza-dC, inhibited the proliferation, migration and promoted apoptosis in PASMCs. In vivo studies further demonstrated that the expression of PTEN, mean pulmonary artery pressure and right ventricular hypertrophy index in HPH rats was attenuated by 5-Aza-dC. 5-Aza-dC also suppressed the expression of DNMTs and PTEN methylation in the lungs of HPH rats. These results indicated that PTEN promoter methylation status is involved in HPH. 5-Aza-dC, as a DNMT inhibitor, has the potential to attenuate HPH via demethylation of the PTEN promoter.

Effect of Rho kinase inhibitor fasudil on the expression ET-1 and NO in rats with hypoxic pulmonary hypertension.

This study aims to study the effect of Rho kinase inhibitor fasudil on the expression endothelin-1 (ET-1) and nitric oxide (NO) in rats with hypoxic pulmonary hypertension (HPH). Twenty-four male SD rats were randomly divided into three groups: control group, model group (HPH group) and HPH+fasudil group. The rat HPH model was established by intermittent hypoxia (IH) at atmospheric pressure. Mean pulmonary artery pressure (mPAP), right ventricular hypertrophy index (RVHI), ET-1 and NO levels, and pulmonary vascular structural changes were observed in all groups. MPAP, RVHI and ET-1 levels were significantly higher in HPH group than in control group, while NO was significantly lower than in control group. In addition, mPAP, RVHI and ET-1 were significantly lower in the HPH+fasudil group than in the HPH group. In the HPH group, ET-1 level was significantly and positively correlated with mPAP and RVHI, NO was negatively correlated with mPAP and RVHI levels, and ET-1 level was significantly and negatively correlated with NO level. In the HPH group, pulmonary arteriolar walls were generally thickened, and lumen stenosis was obvious; while after fasudil treatment, pulmonary arteriolar wall thickening and stenosis degree were significantly reduced. Fasudil can significantly reduce ET-l level and increase NO level in HPH rats, suppressing the development of pulmonary arterial hypertension.

Hypoxia is involved in hypoxic pulmonary hypertension through inhibiting the activation of FGF2 by miR-203.

The aim of this study was to investigate whether hypoxia in vivo can induce hypoxic pulmonary hypertension by inhibiting the activation of FGF2 by miR-203. We established a rat model of hypoxic pulmonary hypertension (HPH), and measured the right ventricular systolic pressure (RVSP) and right ventricular hypertrophy (right ventricular hypertrophy index). The ventricular hypertrophy index (RVHI) was calculated and HE staining of the lung tissue of HPH rats was performed. We extracted pulmonary arterial smooth muscle cells (PASMCs) from rats and identified them by immunofluorescence assay. The expression of miR-203 in hypoxic PASMCs was detected by quantitative Real time-polymerase chain reaction (qRT-PCR). The proliferation and migration of PASMCs were detected by EDU (5-Ethynyl-2'-deoxyuridine), cell counting kit-8 (CCK-8) and scratch assay, respectively. Dual Luciferase reporting assay and Western blot were used to detect the binding of miR-203 and FGF2. The results of qRT-PCR showed that miR-203 expression in rat PASMCs was significantly lower than that in normoxia control group at 24 h and 48 h after hypoxic treatment. EDU, CCK8 and scratch test results showed that proliferation and migration ability of PASMCs were weakened after overexpression of miR-203, and vice versa. Dual Luciferase reporter gene assays and Western blot experiments showed that miR-203 could target and combine with FGF2 to inhibit its expression. In vivo experiments showed that low expression of FGF2 could lead to decreased RVSP and RVHI, decreased FGF2 protein levels, and decreased WT% and (PM+FM)% in hypoxia-treated rats. Hypoxia in vivo is involved in the development of HPH by inhibiting the activation of FGF2 by miR-203. Meanwhile, specific inhibition of FGF2 can reduce hypoxia-induced pulmonary hypertension and improve pulmonary vascular remodeling.

SETD3 negatively regulates VEGF expression during hypoxic pulmonary hypertension in rats.

Angiogenesis and activation of vascular endothelial growth factor (VEGF) signaling are tightly regulated under the condition of hypoxic pulmonary hypertension (HPH); therefore, deciphering the regulatory mechanisms associated with VEGF is important. SET domain-containing 3 (SETD3) and VEGF expression in lung tissue during hypoxia exposure and lentivirus. SETD3 treatments were detected by real-time PCR and Western blot analysis. Remodeling of pulmonary vasculature and hypertrophy of the RV were evaluated. The effects of SETD3 over-expression on the interaction between SETD3 and forkhead box protein M1 (FoxM1) at the VEGF promoter and downstream of the VEGF signal pathway during chronic hypoxia were detected. SETD3 lentiviral vector treatment not only inhibited the increase in VEGF expression but also significantly relieved pulmonary vasculature remodeling and hypertrophy of the RV during HPH. The functional interplay between SETD3 and FoxM1 on chromatin may negatively regulate VEGF expression under HPH through the VEGF receptor-extracellular signal-regulated kinase-hypoxia-induced factor-1 signal pathway. SETD3-mediated transcriptional modification of VEGF may be a potential target to inhibit the development of HPH.