Effect of PRDX6 gene polymorphism on susceptibility to chronic obstructive pulmonary disease in the Chinese Han population.

BACKGROUND: To explore the relationship of peroxiredoxin6 (PRDX6) tag-single nucleotide polymorphisms (SNPs) with susceptibility to chronic obstructive pulmonary disease (COPD) in the Chinese Han population. METHODS: A total of 502 patients with COPD and 481 healthy controls from nine hospitals in China were enrolled in this study. The PRDX6 tag-SNPs were identified by linkage disequilibrium (LD) analysis in 30 healthy controls. The associations between identified tag-SNPs and COPD risk were further evaluated. RESULTS: Four PRDX6 tag-SNPs, including rs7314, rs34619706, rs33951697, and rs4382766, were identified in 30 healthy controls. Moreover, in the allele model, there was no statistical difference in locus in PRDX6 between patients with COPD and healthy controls (P > 0.05). However, in the recessive model, rs33951697 locus in PRDX6 gene carrier with T/T had an increased risk of COPD (odds ratio [OR] = 2.59, 95% CI = 1.06-6.33, P = 0.028). Furthermore, in the relevance analysis between genetic polymorphisms and smoking behavior and lung function indexes, we found that the number of smoked cigarettes per day and FEV1/FVC differed among different genotypes of PRDX6, rs4382766, and rs7314 (P < 0.05). CONCLUSION: PRDX6 gene polymorphism with smoking status may contribute to the etiology of COPD in the Chinese Han population.

Airway delivery of Streptococcus salivarius is sufficient to induce experimental pulmonary hypertension in rats.

BACKGROUND AND PURPOSE: The causal relationship between altered host microbiome composition, especially the respiratory tract microbiome, and the occurrence of pulmonary hypertension (PH) has not yet been studied. An increased abundance of airway streptococci is seen in patients with PH compared with healthy individuals. This study aimed to determine the causal link between elevated airway exposure to Streptococcus and PH. EXPERIMENTAL APPROACH: The dose-, time- and bacterium-specific effects of Streptococcus salivarius (S. salivarius), a selective streptococci, on PH pathogenesis were investigated in a rat model established by intratracheal instillation. KEY RESULTS: Exposure to S. salivarius successfully induced typical PH characteristics, such as elevated right ventricular systolic pressure (RVSP), right ventricular hypertrophy (Fulton's index) and pulmonary vascular remodelling, in a dose- and time-dependent manner. Moreover, the S. salivarius-induced characteristics were absent in either the inactivated S. salivarius (inactivated bacteria control) treatment group or the Bacillus subtilis (active bacteria control) treatment group. Notably, S. salivarius-induced PH is characterized by elevated inflammatory infiltration in the lungs, in a pattern different from the classic hypoxia-induced PH model. Moreover, in comparison with the SU5416/hypoxia-induced PH model (SuHx-PH), S. salivarius-induced PH causes similar histological changes (pulmonary vascular remodelling) but less severe haemodynamic changes (RVSP, Fulton's index). S. salivarius-induced PH is also associated with altered gut microbiome composition, suggesting potential communication of the lung-gut axis. CONCLUSION AND IMPLICATIONS: This study provides the first evidence that the delivery of S. salivarius in the respiratory tract could cause experimental PH in rats.

Prediction and prognosis of adverse maternal and foetal/neonatal outcomes in pulmonary hypertension: an observational study and nomogram construction.

BACKGROUND: Pregnant women with pulmonary hypertension (PH) have higher mortality rates and poor foetal/neonatal outcomes. Tools to assess these risk factors are not well established. METHODS: Predictive and prognostic nomograms were constructed using data from a "Development" cohort of 420 pregnant patients with PH, recorded between January 2009 and December 2018. Logistic regression analysis established models to predict the probability of adverse maternal and foetal/neonatal events and overall survival by Cox analysis. An independent "Validation" cohort comprised data of 273 consecutive patients assessed from January 2019 until May 2022. Nomogram performance was evaluated internally and implemented with online software to increase the ease of use. RESULTS: Type I respiratory failure, New York Heart Association functional class, N-terminal pro-brain natriuretic peptide [Formula: see text] 1400 ng/L, arrhythmia, and eclampsia with pre-existing hypertension were independent risk factors for maternal mortality or heart failure. Type I respiratory failure, arrhythmia, general anaesthesia for caesarean section, New York Heart Association functional class, and N-terminal pro-brain natriuretic peptide [Formula: see text] 1400 ng/L were independent predictors of pulmonary hypertension survival during pregnancy. For foetal/neonatal adverse clinical events, type I respiratory failure, arrhythmia, general anaesthesia for caesarean section, parity, platelet count, fibrinogen, and left ventricular systolic diameter were important predictors. Nomogram application for the Development and Validation cohorts showed good discrimination and calibration; decision curve analysis demonstrated their clinical utility. CONCLUSIONS: The nomogram and its online software can be used to analyse individual mortality, heart failure risk, overall survival prediction, and adverse foetal/neonatal clinical events, which may be useful to facilitate early intervention and better survival rates.

Identification of genetic variants of the IL-22 gene in association with an altered risk of COPD susceptibility.

The incidence of chronic obstructive pulmonary disease (COPD) is related to the interaction between environmental exposure and genetic factors. Far more than 15% of smokers eventually develop COPD. In addition to smoking, genetic susceptibility may be another factor in the development of COPD. IL-22 and its receptors are increased in human and experimental COPD and contribute to pathogenesis. Here, we conducted a case-control study to evaluate the association between IL-22 tag-single nucleotide polymorphisms (SNPs) and COPD risk. Four tag-SNPs (rs2227478, rs2227481, rs2227484 and rs2227485) were identified according to linkage disequilibrium (LD) analysis in 30 healthy controls. A total of 513 COPD cases and 504 controls were recruited to perform an association study between these four tag-SNPs and COPD risk. We found that the "C" allele of rs2227478T>C and the "T" allele of rs2227481C>T were obviously related to decreased COPD susceptibility. Genetic model analysis showed that rs2227478T>C and rs2227481C>T were significantly associated with a decreased risk of COPD under dominant models after adjusting for the above factors. In the recessive model, rs2227485T>C was obviously associated with decreased COPD risk. Our data showed that only rs2227485T>C was associated with a decreased COPD risk after Bonferroni correction. The eQTL analysis showed that rs2227485T>C was significantly associated with IL-22 expression. The pGL4-rs2227485-C gene reporter had a higher promoter activity than pGL4-rs2227485-T. In our study, rs2227485T>C, located in the promoter region of IL-22, was associated with a decreased risk of COPD and increased IL-22 promoter activity, suggesting that this variant might modulate COPD susceptibility.

Combined intermittent and sustained hypoxia is a novel and deleterious cardio-metabolic phenotype.

STUDY OBJECTIVES: Chronic obstructive pulmonary disease and obstructive sleep apnea overlap syndrome is associated with excess mortality, and outcomes are related to the degree of hypoxemia. People at high altitudes are susceptible to periodic breathing, and hypoxia at altitude is associated with cardio-metabolic dysfunction. Hypoxemia in these scenarios may be described as superimposed sustained hypoxia (SH) plus intermittent hypoxia (IH), or overlap hypoxia (OH), the effects of which have not been investigated. We aimed to characterize the cardio-metabolic consequences of OH in mice. METHODS: C57BL/6J mice were subjected to either SH (FiO2 = 0.10), IH (FiO2 = 0.21 for 12 h, and FiO2 oscillating between 0.21 and 0.06, 60 times/hour, for 12 h), OH (FiO2 = 0.13 for 12 h, and FiO2 oscillating between 0.13 and 0.06, 60 times/hour, for 12 h), or room air (RA), n = 8/group. Blood pressure and intraperitoneal glucose tolerance test were measured serially, and right ventricular systolic pressure (RVSP) was assessed. RESULTS: Systolic blood pressure transiently increased in IH and OH relative to SH and RA. RVSP did not increase in IH, but increased in SH and OH by 52% (p < .001) and 20% (p = .001). Glucose disposal worsened in IH and improved in SH, with no change in OH. Serum low- and very-low-density lipoproteins increased in OH and SH, but not in IH. Hepatic oxidative stress increased in all hypoxic groups, with the highest increase in OH. CONCLUSIONS: OH may represent a unique and deleterious cardio-metabolic stimulus, causing systemic and pulmonary hypertension, and without protective metabolic effects characteristic of SH.

Heterozygous Tropomodulin 3 mice have improved lung vascularization after chronic hypoxia.

The molecular mechanisms leading to high-altitude pulmonary hypertension (HAPH) remains poorly understood. We previously analyzed the whole genome sequence of Kyrgyz highland population and identified eight genomic intervals having a potential role in HAPH. Tropomodulin 3 gene (TMOD3), which encodes a protein that binds and caps the pointed ends of actin filaments and inhibits cell migration, was one of the top candidates. Here we systematically sought additional evidence to validate the functional role of TMOD3. In-silico analysis reveals that some of the SNPs in HAPH associated genomic intervals were positioned in a regulatory region that could result in alternative splicing of TMOD3. In order to functionally validate the role of TMOD3 in HAPH, we exposed Tmod3-/+ mice to 4 weeks of constant hypoxia, i.e. 10% O2 and analyzed both functional (hemodynamic measurements) and structural (angiography) parameters related to HAPH. The hemodynamic measurements, such as right ventricular systolic pressure, a surrogate measure for pulmonary arterial systolic pressure, and right ventricular contractility (RV- ± dP/dt), increases with hypoxia did not separate between Tmod3-/+ and control mice. Remarkably, there was a significant increase in the number of lung vascular branches and total length of pulmonary vascular branches (P < 0.001) in Tmod3-/+ after 4 weeks of constant hypoxia as compared with controls. Notably, the Tmod3-/+ endothelial cells migration was also significantly higher than that from the wild-type littermates. Our results indicate that, under chronic hypoxia, lower levels of Tmod3 play an important role in the maintenance or neo-vascularization of pulmonary arteries.

TRPC6, a therapeutic target for pulmonary hypertension.

Idiopathic pulmonary arterial hypertension (PAH) is a fatal and progressive disease. Sustained vasoconstriction due to pulmonary arterial smooth muscle cell (PASMC) contraction and concentric arterial remodeling due partially to PASMC proliferation are the major causes for increased pulmonary vascular resistance and increased pulmonary arterial pressure in patients with precapillary pulmonary hypertension (PH) including PAH and PH due to respiratory diseases or hypoxemia. We and others observed upregulation of TRPC6 channels in PASMCs from patients with PAH. A rise in cytosolic Ca2+ concentration ([Ca2+]cyt) in PASMC triggers PASMC contraction and vasoconstriction, while Ca2+-dependent activation of PI3K/AKT/mTOR pathway is a pivotal signaling cascade for cell proliferation and gene expression. Despite evidence supporting a pathological role of TRPC6, no selective and orally bioavailable TRPC6 antagonist has yet been developed and tested for treatment of PAH or PH. In this study, we sought to investigate whether block of receptor-operated Ca2+ channels using a nonselective blocker of cation channels, 2-aminoethyl diphenylborinate (2-APB, administered intraperitoneally) and a selective blocker of TRPC6, BI-749327 (administered orally) can reverse established PH in mice. The results from the study show that intrapulmonary application of 2-APB (40 µM) or BI-749327 (3-10 µM) significantly and reversibly inhibited acute alveolar hypoxia-induced pulmonary vasoconstriction. Intraperitoneal injection of 2-APB (1 mg/kg per day) significantly attenuated the development of PH and partially reversed established PH in mice. Oral gavage of BI-749327 (30 mg/kg, every day, for 2 wk) reversed established PH by ∼50% via regression of pulmonary vascular remodeling. Furthermore, 2-APB and BI-749327 both significantly inhibited PDGF- and serum-mediated phosphorylation of AKT and mTOR in PASMC. In summary, the receptor-operated and mechanosensitive TRPC6 channel is a good target for developing novel treatment for PAH/PH. BI-749327, a selective TRPC6 blocker, is potentially a novel and effective drug for treating PAH and PH due to respiratory diseases or hypoxemia.

Mouse model of experimental pulmonary hypertension: Lung angiogram and right heart catheterization.

Pulmonary arterial hypertension is a progressive and fatal disease and rodents with experimental pulmonary hypertension (PH) are often used to study pathogenic mechanisms, identify therapeutic targets, and develop novel drugs for treatment. Here we describe a hands-on set of experimental approaches including ex vivo lung angiography and histology and in vivo right heart catheterization (RHC) to phenotypically characterize pulmonary hemodynamics and lung vascular structure in normal mice and mice with experimental PH. We utilized Microfil polymer as contrast in our ex vivo lung angiogram to quantitatively examine pulmonary vascular remodeling in mice with experimental PH, and lung histology to estimate pulmonary artery wall thickness. The peripheral lung vascular images were selected to determine the total length of lung vascular branches, the number of branches and the number of junctions in a given area (mm-2). We found that the three parameters determined by angiogram were not significantly different among the apical, middle, and basal regions of the mouse lung from normal mice, and were not influenced by gender (no significant difference between female and male mice). We conducted RHC in mice to measure right ventricular systolic pressure, a surrogate measure for pulmonary artery systolic pressure and right ventricle (RV) contractility (RV ± dP/dtmax) to estimate RV function. RHC, a short time (4-6 min) procedure, did not alter the lung angiography measurements. In summary, utilizing ex vivo angiogram to determine peripheral vascular structure and density in the mouse lung and utilizing in vivo RHC to measure pulmonary hemodynamics are reliable readouts to phenotype normal mice and mice with experimental PH. Lung angiogram and RHC are also reliable approaches to examine pharmacological effects of new drugs on pulmonary vascular remodeling and hemodynamics.

Upregulation of Calcium Homeostasis Modulators in Contractile-To-Proliferative Phenotypical Transition of Pulmonary Arterial Smooth Muscle Cells.

Excessive pulmonary artery (PA) smooth muscle cell (PASMC) proliferation and migration are implicated in the development of pathogenic pulmonary vascular remodeling characterized by concentric arterial wall thickening and arteriole muscularization in patients with pulmonary arterial hypertension (PAH). Pulmonary artery smooth muscle cell contractile-to-proliferative phenotypical transition is a process that promotes pulmonary vascular remodeling. A rise in cytosolic Ca2+ concentration [(Ca2+) cyt ] in PASMCs is a trigger for pulmonary vasoconstriction and a stimulus for pulmonary vascular remodeling. Here, we report that the calcium homeostasis modulator (CALHM), a Ca2+ (and ATP) channel that is allosterically regulated by voltage and extracellular Ca2+, is upregulated during the PASMC contractile-to-proliferative phenotypical transition. Protein expression of CALHM1/2 in primary cultured PASMCs in media containing serum and growth factors (proliferative PASMC) was significantly greater than in freshly isolated PA (contractile PASMC) from the same rat. Upregulated CALHM1/2 in proliferative PASMCs were associated with an increased ratio of pAKT/AKT and pmTOR/mTOR and an increased expression of the cell proliferation marker PCNA, whereas serum starvation and rapamycin significantly downregulated CALHM1/2. Furthermore, CALHM1/2 were upregulated in freshly isolated PA from rats with monocrotaline (MCT)-induced PH and in primary cultured PASMC from patients with PAH in comparison to normal controls. Intraperitoneal injection of CGP 37157 (0.6 mg/kg, q8H), a non-selective blocker of CALHM channels, partially reversed established experimental PH. These data suggest that CALHM upregulation is involved in PASMC contractile-to-proliferative phenotypical transition. Ca2+ influx through upregulated CALHM1/2 may play an important role in the transition of sustained vasoconstriction to excessive vascular remodeling in PAH or precapillary PH. Calcium homeostasis modulator could potentially be a target to develop novel therapies for PAH.

Halofuginone, a promising drug for treatment of pulmonary hypertension.

BACKGROUND AND PURPOSE: Halofuginone is a febrifugine derivative originally isolated from Chinese traditional herb Chang Shan that exhibits anti-hypertrophic, anti-fibrotic and anti-proliferative effects. We sought to investigate whether halofuginone induced pulmonary vasodilation and attenuates chronic hypoxia-induced pulmonary hypertension (HPH). EXPERIMENTAL APPROACH: Patch-clamp experiments were conducted to examine the activity of voltage-dependent Ca2+ channels (VDCCs) in pulmonary artery smooth muscle cells (PASMCs). Digital fluorescence microscopy was used to measure intracellular Ca2+ concentration in PASMCs. Isolated perfused and ventilated mouse lungs were used to measure pulmonary artery pressure (PAP). Mice exposed to hypoxia (10% O2 ) for 4 weeks were used as model of HPH for in vivo experiments. KEY RESULTS: Halofuginone increased voltage-gated K+ (Kv ) currents in PASMCs and K+ currents through KCNA5 channels in HEK cells transfected with KCNA5 gene. HF (0.03-1 µM) inhibited receptor-operated Ca2+ entry in HEK cells transfected with calcium-sensing receptor gene and attenuated store-operated Ca2+ entry in PASMCs. Acute (3-5 min) intrapulmonary application of halofuginone significantly and reversibly inhibited alveolar hypoxia-induced pulmonary vasoconstriction dose-dependently (0.1-10 µM). Intraperitoneal administration of halofuginone (0.3 mg·kg-1 , for 2 weeks) partly reversed established PH in mice. CONCLUSION AND IMPLICATIONS: Halofuginone is a potent pulmonary vasodilator by activating Kv channels and blocking VDCC and receptor-operated and store-operated Ca2+ channels in PASMCs. The therapeutic effect of halofuginone on experimental PH is probably due to combination of its vasodilator effects, via inhibition of excitation-contraction coupling and anti-proliferative effects, via inhibition of the PI3K/Akt/mTOR signalling pathway.

Hypoxia-induced pulmonary hypertension-Utilizing experiments of nature.

An increase in pulmonary artery pressure is a common observation in adult mammals exposed to global alveolar hypoxia. It is considered a maladaptive response that places an increased workload on the right ventricle. The mechanisms initiating and maintaining the elevated pressure are of considerable interest in understanding pulmonary vascular homeostasis. There is an expectation that identifying the key molecules in the integrated vascular response to hypoxia will inform potential drug targets. One strategy is to take advantage of experiments of nature, specifically, to understand the genetic basis for the inter-individual variation in the pulmonary vascular response to acute and chronic hypoxia. To date, detailed phenotyping of highlanders has focused on haematocrit and oxygen saturation rather than cardiovascular phenotypes. This review explores what we can learn from those studies with respect to the pulmonary circulation. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.1/issuetoc.

Exosomal miR-107 antagonizes profibrotic phenotypes of pericytes by targeting a pathway involving HIF-1α/Notch1/PDGFRß/YAP1/Twist1 axis in vitro.

Microvascular pericytes have been demonstrated as an origin for myofibroblasts that produce excessive extracellular matrix (ECM) proteins such as α-smooth muscle actin (α-SMA) and type I collagen (ColIA1) and contribute to pulmonary fibrosis (PF). However, the signaling mechanism responsible for ECM production within pericytes is poorly understood. In this study, we examined exosomal miR-107 in the fibrotic phenotypes of pericytes and the pathogenesis of PF. Using RT-qPCR, MiR-107 level was compared between clinical or bleomycin-induced PF and normal pulmonary tissues. Exosomes were isolated from cultured microvascular endothelial cells (ECs) derived from either normal or PF tissues, characterized using dynamic light scattering, transmission electron microscopy, flow cytometry, Western blot, and immunofluorescence, and then applied to pericytes. The effects of exosomes or different fibrosis-related signaling molecules were examined by Western blot, and the potential regulations between the signaling molecules were identified using bioinformatic analysis and assessed by electrophoretic mobility shift assay, chromatin immunoprecipitation, luciferase assay, and RNA binding protein immunoprecipitation. MiR-107 was downregulated in clinical or experimental PF tissues and also in exosomes from PF-derived ECs. EC-derived exosomal miR-107 essentially controlled the miR-107 level and inhibited α-SMA and ColIA1 expression in pericytes. The antifibrosis effect of miR-107 was mediated through the suppression of a pathway involving HIF-1α/Notch1/PDGFRß/YAP1/Twist1, where miR-107 directly targeted HIF-1α mRNA, whereas the latter directly activated the transcriptions of both Notch1 and PDGFRß. Functionally, targeting miR-107 promoted and targeting HIF-1α abolished the fibrotic phenotypes of pericytes. Exosomal miR-107 produced by pulmonary vascular ECs may alleviate pericyte-induced fibrosis by inhibiting a signaling pathway involving HIF-1α/Notch1/PDGFRß/YAP1/Twist1.NEW & NOTEWORTHY This work reveals a novel mechanism by which pulmonary vascular endothelial cells, via regulating the transdifferentiation of microvascular pericytes into myofibroblasts, contribute to the pathogenesis of pulmonary fibrosis. Since targeting the formation of myofibroblasts may prevent the development and benefit the treatment of pulmonary fibrosis, this study provides not only mechanistic understanding but also promising therapeutic targets for pulmonary fibrosis.

Revisiting the mechanism of hypoxic pulmonary vasoconstriction using isolated perfused/ventilated mouse lung.

Hypoxic Pulmonary Vasoconstriction (HPV) is an important physiological mechanism of the lungs that matches perfusion to ventilation thus maximizing O2 saturation of the venous blood within the lungs. This study emphasizes on principal pathways in the initiation and modulation of hypoxic pulmonary vasoconstriction with a primary focus on the role of Ca2+ signaling and Ca2+ influx pathways in hypoxic pulmonary vasoconstriction. We used an ex vivo model, isolated perfused/ventilated mouse lung to evaluate hypoxic pulmonary vasoconstriction. Alveolar hypoxia (utilizing a mini ventilator) rapidly and reversibly increased pulmonary arterial pressure due to hypoxic pulmonary vasoconstriction in the isolated perfused/ventilated lung. By applying specific inhibitors for different membrane receptors and ion channels through intrapulmonary perfusion solution in isolated lung, we were able to define the targeted receptors and channels that regulate hypoxic pulmonary vasoconstriction. We show that extracellular Ca2+ or Ca2+ influx through various Ca2+-permeable channels in the plasma membrane is required for hypoxic pulmonary vasoconstriction. Removal of extracellular Ca2+ abolished hypoxic pulmonary vasoconstriction, while blockade of L-type voltage-dependent Ca2+ channels (with nifedipine), non-selective cation channels (with 30 µM SKF-96365), and TRPC6/TRPV1 channels (with 1 µM SAR-7334 and 30 µM capsazepine, respectively) significantly and reversibly inhibited hypoxic pulmonary vasoconstriction. Furthermore, blockers of Ca2+-sensing receptors (by 30 µM NPS2143, an allosteric Ca2+-sensing receptors inhibitor) and Notch (by 30 µM DAPT, a γ-secretase inhibitor) also attenuated hypoxic pulmonary vasoconstriction. These data indicate that Ca2+ influx in pulmonary arterial smooth muscle cells through voltage-dependent, receptor-operated, and store-operated Ca2+ entry pathways all contribute to initiation of hypoxic pulmonary vasoconstriction. The extracellular Ca2+-mediated activation of Ca2+-sensing receptors and the cell-cell interaction via Notch ligands and receptors contribute to the regulation of hypoxic pulmonary vasoconstriction.

Chronic Hypoxia Decreases Endothelial Connexin 40, Attenuates Endothelium-Dependent Hyperpolarization-Mediated Relaxation in Small Distal Pulmonary Arteries, and Leads to Pulmonary Hypertension.

Background Abnormal endothelial function in the lungs is implicated in the development of pulmonary hypertension; however, there is little information about the difference of endothelial function between small distal pulmonary artery (PA) and large proximal PA and their contribution to the development of pulmonary hypertension. Herein, we investigate endothelium-dependent relaxation in different orders of PAs and examine the molecular mechanisms by which chronic hypoxia attenuates endothelium-dependent pulmonary vasodilation, leading to pulmonary hypertension. Methods and Results Endothelium-dependent relaxation in large proximal PAs (second order) was primarily caused by releasing NO from the endothelium, whereas endothelium-dependent hyperpolarization (EDH)-mediated vasodilation was prominent in small distal PAs (fourth-fifth order). Chronic hypoxia abolished EDH-mediated relaxation in small distal PAs without affecting smooth muscle-dependent relaxation. RNA-sequencing data revealed that, among genes related to EDH, the levels of Cx37, Cx40, Cx43, and IK were altered in mouse pulmonary endothelial cells isolated from chronically hypoxic mice in comparison to mouse pulmonary endothelial cells from normoxic control mice. The protein levels were significantly lower for connexin 40 (Cx40) and higher for connexin 37 in mouse pulmonary endothelial cells from hypoxic mice than normoxic mice. Cx40 knockout mice exhibited significant attenuation of EDH-mediated relaxation and marked increase in right ventricular systolic pressure. Interestingly, chronic hypoxia led to a further increase in right ventricular systolic pressure in Cx40 knockout mice without altering EDH-mediated relaxation. Furthermore, overexpression of Cx40 significantly decreased right ventricular systolic pressure in chronically hypoxic mice. Conclusions These data suggest that chronic hypoxia-induced downregulation of endothelial Cx40 results in impaired EDH-mediated relaxation in small distal PAs and contributes to the development of pulmonary hypertension.

Endothelial platelet-derived growth factor-mediated activation of smooth muscle platelet-derived growth factor receptors in pulmonary arterial hypertension.

Platelet-derived growth factor is one of the major growth factors found in human and mammalian serum and tissues. Abnormal activation of platelet-derived growth factor signaling pathway through platelet-derived growth factor receptors may contribute to the development and progression of pulmonary vascular remodeling and obliterative vascular lesions in patients with pulmonary arterial hypertension. In this study, we examined the expression of platelet-derived growth factor receptor isoforms in pulmonary arterial smooth muscle and pulmonary arterial endothelial cells and investigated whether platelet-derived growth factor secreted from pulmonary arterial smooth muscle cell or pulmonary arterial endothelial cell promotes pulmonary arterial smooth muscle cell proliferation. Our results showed that the protein expression of platelet-derived growth factor receptor α and platelet-derived growth factor receptor ß in pulmonary arterial smooth muscle cell was upregulated in patients with idiopathic pulmonary arterial hypertension compared to normal subjects. Platelet-derived growth factor activated platelet-derived growth factor receptor α and platelet-derived growth factor receptor ß in pulmonary arterial smooth muscle cell, as determined by phosphorylation of platelet-derived growth factor receptor α and platelet-derived growth factor receptor ß. The platelet-derived growth factor-mediated activation of platelet-derived growth factor receptor α/platelet-derived growth factor receptor ß was enhanced in idiopathic pulmonary arterial hypertension-pulmonary arterial smooth muscle cell compared to normal cells. Expression level of platelet-derived growth factor-AA and platelet-derived growth factor-BB was greater in the conditioned media collected from idiopathic pulmonary arterial hypertension-pulmonary arterial endothelial cell than from normal pulmonary arterial endothelial cell. Furthermore, incubation of idiopathic pulmonary arterial hypertension-pulmonary arterial smooth muscle cell with conditioned culture media from normal pulmonary arterial endothelial cell induced more platelet-derived growth factor receptor α activation than in normal pulmonary arterial smooth muscle cell. Accordingly, the conditioned media from idiopathic pulmonary arterial hypertension-pulmonary arterial endothelial cell resulted in more pulmonary arterial smooth muscle cell proliferation than the media from normal pulmonary arterial endothelial cell. These data indicate that (a) the expression and activity of platelet-derived growth factor receptor are increased in idiopathic pulmonary arterial hypertension-pulmonary arterial smooth muscle cell compared to normal pulmonary arterial smooth muscle cell, and (b) pulmonary arterial endothelial cell from idiopathic pulmonary arterial hypertension patients secretes higher level of platelet-derived growth factor than pulmonary arterial endothelial cell from normal subjects. The enhanced secretion (and production) of platelet-derived growth factor from idiopathic pulmonary arterial hypertension-pulmonary arterial endothelial cell and upregulated platelet-derived growth factor receptor expression (and function) in idiopathic pulmonary arterial hypertension-pulmonary arterial smooth muscle cell may contribute to enhancing platelet-derived growth factor/platelet-derived growth factor receptor-associated pulmonary vascular remodeling in pulmonary arterial hypertension.

TRPV1 genetic polymorphisms and risk of COPD or COPD combined with PH in the Han Chinese population.

COPD is a common chronic disease with genetic predisposition. TRPV1 is mainly expressed in peripheral neuron which widely exists in entire respiratory tract. In present study, we aimed to study the relationship between single nucleotide polymorphisms (SNPs) of transient receptor potential vanilloid-1 (TRPV1) and the risk of chronic obstructive pulmonary disease (COPD) or COPD combined with pulmonary hypertension (PH) in Chinese Han population. A total of 1019 individuals, including 506 healthy volunteers and 513 COPD patients (150 patients combined with PH among them) were recruited in this study. Genomic DNA were extracted and sequenced. Genotype and allele frequencies of the TRPV1 SNPs among COPD, COPD combined with PH and control groups were compared. Then, the association of TRPV1 SNPs and smoking status were analyzed. Genotype frequencies of SNP rs3744683 had a significant difference in COPD patients with PH patients compared with control (p = 0.006) or COPD patients without PH patients (p = 0.016). Likewise, SNP rs3744683 was remarkedly associated with the risk of COPD (p = 0.004) in current-smoker groups which phenomenon was not observed in nonsmoker or former-smoker groups. Compared with the control group, there was a significant difference for the distribution of SNP rs4790521 alleles in the COPD group (p = 0.041). For further, logical regression analysis showed that SNP rs3744683 genotype of "TC" was a protective factor for PH in COPD patients compared with the genotype of "TT" (OR = 0.364, 95%CI = 0.159-0.829, p = 0.016). Our findings firstly revealed the relevance between TRPV1 SNPs and the risk for COPD/COPD combined with PH.

MDM2-Mediated Ubiquitination of Angiotensin-Converting Enzyme 2 Contributes to the Development of Pulmonary Arterial Hypertension.

BACKGROUND: Angiotensin-converting enzyme 2 (ACE2) converts angiotensin II, a potent vasoconstrictor, to angiotensin-(1-7) and is also a membrane protein that enables coronavirus disease 2019 (COVID-19) infectivity. AMP-activated protein kinase (AMPK) phosphorylation of ACE2 enhances ACE2 stability. This mode of posttranslational modification of ACE2 in vascular endothelial cells is causative of a pulmonary hypertension (PH)-protective phenotype. The oncoprotein MDM2 (murine double minute 2) is an E3 ligase that ubiquitinates its substrates to cause their degradation. In this study, we investigated whether MDM2 is involved in the posttranslational modification of ACE2 through its ubiquitination of ACE2, and whether an AMPK and MDM2 crosstalk regulates the pathogenesis of PH. METHODS: Bioinformatic analyses were used to explore E3 ligase that ubiquitinates ACE2. Cultured endothelial cells, mouse models, and specimens from patients with idiopathic pulmonary arterial hypertension were used to investigate the crosstalk between AMPK and MDM2 in regulating ACE2 phosphorylation and ubiquitination in the context of PH. RESULTS: Levels of MDM2 were increased and those of ACE2 decreased in lung tissues or pulmonary arterial endothelial cells from patients with idiopathic pulmonary arterial hypertension and rodent models of experimental PH. MDM2 inhibition by JNJ-165 reversed the SU5416/hypoxia-induced PH in C57BL/6 mice. ACE2-S680L mice (dephosphorylation at S680) showed PH susceptibility, and ectopic expression of ACE2-S680L/K788R (deubiquitination at K788) reduced experimental PH. Moreover, ACE2-K788R overexpression in mice with endothelial cell-specific AMPKα2 knockout mitigated PH. CONCLUSIONS: Maladapted posttranslational modification (phosphorylation and ubiquitination) of ACE2 at Ser-680 and Lys-788 is involved in the pathogenesis of pulmonary arterial hypertension and experimental PH. Thus, a combined intervention of AMPK and MDM2 in the pulmonary endothelium might be therapeutically effective in PH treatment.

Two-stage study of lung cancer risk modification by a functional variant in the 3'-untranslated region of SMAD5 based on the bone morphogenetic protein pathway.

Increasing evidence supports a key role for the bone morphogenetic protein (BMP) signaling pathway in lung vasculogenesis and angiogenesis. Genetic variations in BMP genes have been found to be correlated with cancer risk. In particular, the mutation in the 3'-untranslated region of BMPs may significantly affect gene function, leading to cancer susceptibility. The aim of the present study was to determine whether genetic variations in the components of the BMP family are associated with lung cancer risk. A total of 314 tag single-nucleotide polymorphisms were identified in 18 genes, which are considered to either compose or regulate BMPs, and their association with lung cancer risk was evaluated in a two-stage case-control study with 4,680 cases and controls. A consistently significant association of SMAD5 rs12719482 with elevated lung cancer risk was observed in the three types of sources of populations (adjusted additive model in the combined population: Odds ratio=1.32, 95% confidence interval: 1.16-1.51). The lung cancer risk statistically significantly increased with the increasing number of variant alleles of SMAD5 rs12719482 in a dose-dependent pattern (P for trend=4.9×10-5). Consistent evidence was identified for a significant interaction between the rs12719482 and cigarette smoking, performed as either a continuous or discrete variable. These findings indicated that SMAD5 rs12719482 may be a possible candidate marker for susceptibility to lung cancer in the Chinese population.

The effects of CXCL10 polymorphisms on COPD susceptibility.

The polymorphisms of cytokine genes has been reported to modulate the individual's susceptibility to environmental stimuli in COPD development. C-X-C motif chemokine 10 (CXCL10) mediates recruitment inflammatory cells such as monocytes. Therefore, it may play a key role in COPD. Here, a case-control study was conducted to evaluate the association between CXCL10 tag-SNPs and COPD risk. Four tag-SNPs including rs4256246, rs4508917, rs56061981, and rs56316945 were identified based on the linkage disequilibrium (LD) analysis in 30 healthy controls. The associations between these four tag-SNPs and COPD risk were further evaluated in 480 COPD cases and 488 controls. We found that the "T" allele of rs56061981 was significantly associated with reducing risk of COPD, while "G" allele of rs56316945 was significantly associated with increasing risk of COPD. SNP rs56316945 was significantly associated with increasing risk of COPD under different models except recessive model after adjusting the sex, age, pack year, and biomass. SNP rs56061981 was significantly associated with decreasing COPD risk under different models except recessive model after adjusting the sex, age, pack year, and biomass. Stratified analysis of smoking status and biomass with SNPs supported rs56061981 may interact with biomass and smoking thus modulate COPD susceptibility and rs56216945 was apparently associated with the severity of pulmonary function of COPD patients. This study suggests that rs56061981 and rs56216945 in CXCL10 gene promoter contribute COPD susceptibility.