The association between declining lung function and stroke risk: insights from an observational study and Mendelian randomization

Background

Stroke, prevalent globally, particularly impacts low- and middle-income countries. Decreased lung function is one of the risk factors for stroke, and there is a lack of sufficient research on the association between the two, especially based on evidence from representative large samples. We aimed to explore the association between lung function and stroke incidence.

Methods

We collected data from 13,371 participants from the 2007-2012 U.S. national cross-sectional study and 11,192 participants from the Chinese national cohort study during the 2011-2018 follow-up period. Multivariate logistic regression and Cox proportional hazards regression were used to assess cross-sectional and longitudinal associations of peak expiratory flow with stroke risks. Additionally, we used publicly available GWAS data from a European population to conduct Mendelian randomization analysis, further exploring the potential causal relationship.

Results

The results of the cross-sectional study suggest that a decline in peak expiratory flow may be associated with an increased risk of stroke. The cohort study revealed that, compared to the first tertile group, the risk of stroke incidence in the second and third tertile groups of PEF decreased by 19% (hazard ratio (HR) = 0.810, 95%CI = 0.684-0.960) and 21.4% (HR = 0.786, 95%CI = 0.647-0.956), respectively. Mendelian randomization analysis clarified that higher PEF levels are significantly associated with a reduced risk of stroke (OR = 0.852, 95%CI = 0.727-0.997).

Conclusion

Decreased lung function is a risk factor for stroke. As a simple and accurate indicator of lung function, PEF can be used to monitor lung function in community populations and patients for primary stroke prevention.

Recombinant hirudin attenuates pulmonary hypertension and thrombosis in acute pulmonary embolism rat model

Background

Acute pulmonary embolism (APE) is classified as a subset of diseases that are characterized by lung obstruction due to various types of emboli. Current clinical APE treatment using anticoagulants is frequently accompanied by high risk of bleeding complications. Recombinant hirudin (R-hirudin) has been found to have antithrombotic properties. However, the specific impact of R-hirudin on APE remains unknown.

Methods

Sprague-Dawley (SD) rats were randomly assigned to five groups, with thrombi injections to establish APE models. Control and APE group rats were subcutaneously injected with equal amounts of dimethyl sulfoxide (DMSO). The APE+R-hirudin low-dose, middle-dose, and high-dose groups received subcutaneous injections of hirudin at doses of 0.25 mg/kg, 0.5 mg/kg, and 1.0 mg/kg, respectively. Each group was subdivided into time points of 2 h, 6 h, 1 d, and 4 d, with five animals per point. Subsequently, all rats were euthanized, and serum and lung tissues were collected. Following the assessment of right ventricular pressure (RVP) and mean pulmonary artery pressure (mPAP), blood gas analysis, enzyme-linked immunosorbnent assay (ELISA), pulmonary artery vascular testing, hematoxylin-eosin (HE) staining, Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining, immunohistochemistry, and Western blot experiments were conducted.

Results

R-hirudin treatment caused a significant reduction of mPAP, RVP, and Malondialdehyde (MDA) content, as well as H2O2 and myeloperoxidase (MPO) activity, while increasing pressure of oxygen (PaO2) and Superoxide Dismutase (SOD) activity. R-hirudin also decreased wall area ratio and wall thickness to diameter ratio in APE rat pulmonary arteries. Serum levels of endothelin-1 (ET-1) and thromboxaneB2 (TXB2) decreased, while prostaglandin (6-K-PGF1α) and NO levels increased. Moreover, R-hirudin ameliorated histopathological injuries and reduced apoptotic cells and Matrix metalloproteinase-9 (MMP9), vascular cell adhesion molecule-1 (VCAM-1), p-Extracellular signal-regulated kinase (ERK)1/2/ERK1/2, and p-P65/P65 expression in lung tissues.

Conclusion

R-hirudin attenuated pulmonary hypertension and thrombosis in APE rats, suggesting its potential as a novel treatment strategy for APE.

Pulmonary hypertension: An unexplored risk factor for stroke in patients with atrial fibrillation

BACKGROUND

Atrial fibrillation (Afib) is one of the most common and significant risk factors for stroke, with the CHADsVAsc score used as the tool for stroke risk assessment. Pulmonary hypertension (PH) has not been studied as an independent risk factor for stroke in individuals with Afib.

METHODS

In this retrospective case-control study, National Inpatient Sample Database was used to sample individuals with atrial fibrillation, and baseline demographics and comorbidities were collected using ICD-10 codes. Patients with missing data, age under 18, history of thromboembolic diseases, or stroke were excluded. Greedy propensity matching using R was performed to match patients with and without PH on age, race, gender, and 19 other comorbidities, including anticoagulation use. Binary logistic regression was performed after matching to assess whether PH was an independent risk factor for stroke. A p-value of <0.05 was considered statistically significant.

RESULTS

Of the 2,421,545 patients included in the study, 158,545 (6.5%) had PH. PH patients were more likely to be elderly, females, and smokers. Comorbidities were more common in the PH group. Patients with PH were more likely to have an ischemic stroke (3.6% vs. 2.9%, p<0.001), hemorrhagic stroke (2.2% vs. 0.7%, p<0.001), and transient ischemic attack (TIA) (2.3% vs. 0.7%, p<0.001). After matching, the presence of PH was associated with increased ischemic stroke (OR: 1.2 [1.1-1.2]; p<0.001), hemorrhagic stroke (OR: 2.4 [2.1-2.6]; p<0.001) and TIA (OR: 2.2 [2.0-2.4]; p<0.001). PH patients also had increased length of stay (β = 0.8; p<0.001) mortality (OR: 1.1 [1.0-1.2]; p<0.001).

CONCLUSION

Apart from demonstrating the deleterious effect of PH on mortality and length of hospital stay, this study is the first to report on such a large scale that PH independently increases the incidence of all types of strokes in patients with Afib.

Higher circulating Trimethylamine N-oxide levels are associated with worse severity and prognosis in pulmonary hypertension: a cohort study

BACKGROUND

Trimethylamine N-oxide (TMAO), the gut microbiota-dependent metabolite, is a potential biomarker in several cardiovascular diseases. However, no study has investigated its value in pulmonary hypertension (PH). Therefore, this study aimed to explore the association between plasma TMAO levels and prognosis in patients with PH.

METHODS

Inpatients with idiopathic/heritable pulmonary arterial hypertension (IPAH/HPAH), PAH associated with congenital heart disease (CHD-PAH), and chronic thromboembolic pulmonary hypertension (CTEPH) at Fuwai Hospital were enrolled after excluding those with relative comorbidities. The endpoint was defined as a composite outcome including death, rehospitalisation due to heart failure, and at least 15% decreased 6-min walk distance from the baseline. Fasting blood samples were collected to measure plasma levels of TMAO and other clinical indicators. The associations between TMAO levels with disease severity and patients' prognosis were investigated.

RESULTS

In total, 163 patients with PH were included, with a mean follow-up duration of 1.3 years. After adjusting for confounding factors, elevated TMAO levels were still associated with severe disease conditions. TMAO levels dynamically decreased in stable and improved patients after treatment [ΔTMAO = - 0.2 (- 1.6, 0.7) μmol/L, P = 0.006]. Moreover, high plasma TMAO levels predicted a poor prognosis in the PH cohort (P < 0.001), and the association remained significant after adjusting the confounders, including treatment, risk stratification, and PH subtypes.

CONCLUSION

Elevated plasma TMAO levels were associated with severe disease conditions and poor prognosis in patients with PH, indicating its potential biomarker role in PH.

Senescence Alterations in Pulmonary Hypertension

Cellular senescence is the arrest of normal cell division and is commonly associated with aging. The interest in the role of cellular senescence in lung diseases derives from the observation of markers of senescence in chronic obstructive pulmonary disease (COPD), pulmonary fibrosis (IPF), and pulmonary hypertension (PH). Accumulation of senescent cells and the senescence-associated secretory phenotype in the lung of aged patients may lead to mild persistent inflammation, which results in tissue damage. Oxidative stress due to environmental exposures such as cigarette smoke also promotes cellular senescence, together with additional forms of cellular stress such as mitochondrial dysfunction and endoplasmic reticulum stress. Growing recent evidence indicate that senescent cell phenotypes are observed in pulmonary artery smooth muscle cells and endothelial cells of patients with PH, contributing to pulmonary artery remodeling and PH development. In this review, we analyze the role of different senescence cell phenotypes contributing to the pulmonary artery remodeling process in different PH clinical entities. Different molecular pathway activation and cellular functions derived from senescence activation will be analyzed and discussed as promising targets to develop future senotherapies as promising treatments to attenuate pulmonary artery remodeling in PH.

Genetic biosensors for imaging nitric oxide in single cells

Over the last decades a broad collection of sophisticated fluorescent protein-based probes was engineered with the aim to specifically monitor nitric oxide (NO), one of the most important signaling molecules in biology. Here we report and discuss the characteristics and fields of applications of currently available genetically encoded fluorescent sensors for the detection of NO and its metabolites in different cell types.

LONG ABSTRACT

Because of its radical nature and short half-life, real-time imaging of NO on the level of single cells is challenging. Herein we review state-of-the-art genetically encoded fluorescent sensors for NO and its byproducts such as peroxynitrite, nitrite and nitrate. Such probes enable the real-time visualization of NO signals directly or indirectly on the level of single cells and cellular organelles and, hence, extend our understanding of the spatiotemporal dynamics of NO formation, diffusion and degradation. Here, we discuss the significance of NO detection in individual cells and on subcellular level with genetic biosensors. Currently available genetically encoded fluorescent probes for NO and nitrogen species are critically discussed in order to provide insights in the functionality and applicability of these promising tools. As an outlook we provide ideas for novel approaches for the design and application of improved NO probes and fluorescence imaging protocols.

The role of platelets in the development and progression of pulmonary arterial hypertension

Pulmonary arterial hypertension is a multifactorial disease characterized by vasoconstriction, vascular remodeling, inflammation and thrombosis. Although an increasing number of research confirmed that pulmonary artery endothelial cells, pulmonary artery smooth muscle cells as well as platelets have a role in the pulmonary arterial hypertension pathogenesis, it is still unclear what integrates these factors. In this paper, we review the evidence that platelets through releasing a large variety of chemokines could actively impact the pulmonary arterial hypertension pathogenesis and development. A recent publication revealed that not only an excess of platelet derived cytokines, but also a deficiency may be associated with pulmonary arterial hypertension development and progression. Hence, a simple platelet blockade may not be a correct action to treat pulmonary arterial hypertension. Our review aims to analyse the interactions between the platelets and different types of cells involved in pulmonary arterial hypertension pathogenesis. This knowledge could help to find novel therapeutic options and improve prognosis in this devastating disease.

Platelet and coagulation disorders in newly diagnosed patients with pulmonary arterial hypertension

There is a complex and not fully elucidated association between pulmonary arterial hypertension (PAH) and coagulation disorders. The goal of this study was to evaluate platelet function, coagulation and fibrinolysis in PAH patients at diagnosis, before PAH-specific treatment initiation. We enrolled 20 healthy controls and 30 PAH patients (20 with connective tissue disease (CTD-PAH) and 10 idiopathic (iPAH)). None of the participants was on any antiplatelet or anticoagulation therapy. Blood samples from PAH patients were collected during the initial right heart catheterization. All subjects were assessed with platelet function analyzer-100 (PFA-100), epinephrine (Epi) and ADP-induced light transmission aggregometry (LTA), thromboelastometry (ROTEM) and endogenous thrombin potential (ETP). Our results showed that Epi and ADP-LTA values were significantly lower in newly diagnosed PAH patients compared to controls. Disaggregation was present in 73% of patients, a characteristic not seen in healthy individuals. In ROTEM assay, CT and CFT measurements were significantly higher and a angle lower compared to controls. ETP testing revealed significantly reduced outcomes in AUC, Cmax and Tmax. When CTD-PAH and iPAH patient groups were compared, iPAH ADP-LTA values were significantly decreased compared to CTD-PAH. In conclusion, newly diagnosed PAH patients presented with decreased platelet aggregation, clot propagation and thrombin generation, along with delayed initiation of the coagulation process. These hemostatic deficits could indicate an "exhaustion" of the coagulation process that could be caused by endothelial dysfunction and chronic activation of the procoagulant pathways. Further studies are warranted to confirm these laboratory findings and assess their potential clinical significance.

3,7-Bis(2-hydroxyethyl)icaritin, a potent inhibitor of phosphodiesterase-5, prevents monocrotaline-induced pulmonary arterial hypertension via NO/cGMP activation in rats

Pulmonary arterial hypertension (PAH) is a chronic progressive disease which leads to elevated pulmonary arterial pressure and right heart failure. 3,7-Bis(2-hydroxyethyl)icaritin (ICT), an icariin derivatives, was reported to have potent inhibitory activity on phosphodiesterase type 5 (PDE5) which plays a crucial role in the pathogenesis of PAH. The present study was designed to investigate the effects of ICT on monocrotaline (MCT)-induced PAH rat model and reveal the underlying mechanism. MCT-induced PAH rat models were established with intragastric administration of ICT (10, 20, 40 mg/kg/d), Icariin (ICA) (40 mg/kg/d) and Sildenafil (25 mg/kg/d). The mean pulmonary arterial pressure (mPAP) and right ventricle hypertrophy index (RVHI) were measured. Pulmonary artery remodeling was assessed by H&E staining. Blood and lung tissue were collected to evaluate the level of endothelin 1 (ET-1), nitric oxide (NO), and cyclic guanosine monophosphate (cGMP). The expressions endothelial nitric oxide synthase (eNOS) and PDE5A in lung tissues were determined by Western blot analysis. The results showed that ICT reduced RVHI and mPAP, and reversed lung vascular remodeling in rats with MCT-induced PAH. ICT also reversed MCT-induced ET-1 elevation, NO and cGMP reduction in serum or lung tissue. Moreover, ICT administration significantly induced eNOS activation and PDE5A inhibition. ICT with lower dose had better effects than ICA. In summary, ICT is more effective in preventing MCT-induced PAH in rats via NO/cGMP activation compared with ICA. These findings demonstrate a novel mechanism of the action of ICT that may have value in prevention of PAH.

Liposomal Aerosols of Nitric Oxide (NO) Donor as a Long-Acting Substitute for the Ultra-Short-Acting Inhaled NO in the Treatment of PAH

PURPOSE

This study seeks to develop a liposomal formulation of diethylenetriamine NONOate (DN), a long acting nitric oxide (NO) donor, with a goal to replace inhaled NO (iNO) in the treatment of pulmonary arterial hypertension (PAH).

METHODS

Liposomal formulations were prepared by a lipid film hydration method and modified with a cell penetrating peptide, CAR. The particles were characterized for size, polydispersity index (PDI), zeta potential, entrapment efficiency, storage and nebulization stability, and in-vitro release profiles. The cellular uptake and transport were assessed in rat alveolar macrophages (NR8383) and transforming growth factor β (TGF-β) activated rat pulmonary arterial smooth muscle cells (PASMCs). The fraction of the formulation that enters the systemic circulation, after intratracheal administration, was determined in an Isolated Perfused Rat Lung (IPRL) model. The safety of the formulations were assessed using an MTT assay and by measuring injury markers in the bronchoalveolar lavage (BAL) fluid; the pharmacological efficacy was evaluated by monitoring the changes in the mean pulmonary arterial (mPAP) and systemic pressure (mSAP) in a monocrotaline (MCT) induced-PAH rat model

RESULTS

Liposome size, zeta potential, and entrapment efficiency were 171 ± 4 nm, -37 ± 3 mV, and 46 ± 5%, respectively. The liposomes released 70 ± 5% of the drug in 8 h and were stable when stored at 4°C. CAR-conjugated-liposomes were taken up more efficiently by PASMCs than liposomes-without-CAR; the uptake of the formulations by rat alveolar macrophages was minimal. DN-liposomes did not increase lung weight, protein quantity, and levels of injury markers in the BAL fluid. Intratracheal CAR-liposomes reduced the entry of liposomes from the lung to blood; the formulations produced a 40% reduction in mPAP for 180 minutes.

CONCLUSION

This study establishes the proof-of-concept that peptide modified liposomal formulations of long-acting NO donor can be an alternative to short-acting iNO.

Calorie Restriction Attenuates Monocrotaline-induced Pulmonary Arterial Hypertension in Rats

Calorie restriction (CR) is one of the most effective nonpharmacological interventions protecting against cardiovascular disease, such as hypertension in the systemic circulation. However, whether CR could attenuate pulmonary arterial hypertension (PAH) is largely unknown. The PAH model was developed by subjecting the rats to a single subcutaneous injection of monocrotaline. CR lowered mean pulmonary arterial pressure (mPAP) and reduced vascular remodeling and right ventricular hypertrophy in PAH rats. Meanwhile, CR attenuated endothelial dysfunction as evidenced by increased relaxation in response to acetylcholine. The beneficial effects of CR were associated with restored sirtuin-1 (SIRT1) expression and endothelial nitric oxide synthase (eNOS) phosphorylation and reduced eNOS acetylation in pulmonary arteries of PAH rats. To further clarify the role of SIRT1 in the protective effects of CR, adenoviral vectors for overexpression of SIRT1 were administered intratracheally at 1 day before monocrotaline injection. Overexpression of SIRT1 exhibited similar beneficial effects on mPAP and endothelial function, and increased eNOS phosphorylation and reduced eNOS acetylation in the absence of CR. Moreover, SIRT1 overexpression attenuated the increase in mPAP in hypoxia-induced PAH animals. Overall, the present data demonstrate that CR may serve as an effective treatment of PAH, and targeting the SIRT1/eNOS pathway may improve treatment of PAH.

Influence of food patterns on endothelial biomarkers: a systematic review

The purpose of this study was to conduct a systematic review on the association of food patterns (FPs) and endothelial biomarkers. An electronic literature search from 1990 to 2012 was conducted and reference lists and experts were consulted. Studies without dietary intervention and without language restrictions were considered. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were employed. Methodological quality was assessed by Strengthening the Reporting of Observational Studies in Epidemiology guidelines. A total of 546 references were identified, of which 8 were finally included. Several FPs were identified. Healthy FPs (abundant in fruits and vegetables) had a beneficial impact on endothelial function as estimated by circulating levels of biomarkers such as C-reactive protein, soluble intercellular adhesion molecule 1, soluble vascular adhesion molecule 1, and E-selectin molecules. Westernized patterns (higher intakes of processed meats, sweets, fried foods, and refined grains) were positively associated with inflammation molecules and atherogenic promoters. The study of FPs in relation to endothelial function contributes to the development of dietary recommendations for improved cardiovascular health and therefore a better lifestyle.

Time lasting S-nitrosoglutathione polymeric nanoparticles delay cellular protein S-nitrosation

Physiological S-nitrosothiols (RSNO), such as S-nitrosoglutathione (GSNO), can be used as nitric oxide (NO) donor for the treatment of vascular diseases. However, despite a half-life measured in hours, the stability of RSNO, limited by enzymatic and non-enzymatic degradations, is too low for clinical application. So, to provide a long-lasting effect and to deliver appropriate NO concentrations to target tissues, RSNO have to be protected. RSNO encapsulation is an interesting response to overcome degradation and provide protection. However, RSNO such as GSNO raise difficulties for encapsulation due to its hydrophilic nature and the instability of the S-NO bound during the formulation process. To our knowledge, the present study is the first description of the direct encapsulation of GSNO within polymeric nanoparticles (NP). The GSNO-loaded NP (GSNO-NP) formulated by a double emulsion process, presented a mean diameter of 289 ± 7 nm. They were positively charged (+40 mV) due to the methacrylic acid and ethylacrylate polymer (Eudragit® RL) used and encapsulated GSNO with a satisfactory efficiency (i.e. 54% or 40 mM GSNO loaded in the NP). In phosphate buffer (37 °C; pH 7.4), GSNO-NP released 100% of encapsulated GSNO within 3h and remained stable still 6h. However, in contact with smooth muscle cells, maximum protein nitrosation (a marker of NO bioavailability) was delayed from 1h for free GSNO to 18h for GSNO-NP. Therefore, protection and sustained release of NO were achieved by the association of a NO donor with a drug delivery system (such as polymeric NP), providing opportunities for vascular diseases treatment.

Thrombosis, platelets, microparticles and PAH: more than a clot

Pulmonary arterial hypertension (PAH) is a progressive disease that involves pathological remodeling, vasoconstriction and thrombosis. Alterations in hemostasis, coagulation and platelet activation are consistently observed in PAH patients. Microparticles derived from platelets, inflammatory cells and the endothelium are an increasingly well-recognized signal in a variety of cardiovascular diseases, including PAH. This review will focus on the roles of coagulation, thrombosis, platelet activation and microparticles in the pathology and progression of PAH.

Development of vascular smooth muscle contractility by endothelium-derived transforming growth factor β proteins

It is well established that the release of vasodilators and vasoconstrictors from vascular endothelium regulates vascular smooth muscle contraction. In this report, we investigate the role of the endothelium in the development and maintenance of constitutive vascular contractility. For that purpose, contractile activity of cultured bovine aortic smooth muscle cells (BASMCs) embedded in collagen gels was monitored by changes in gel diameter. After culturing for 5 days, ATP- and high KCl solution-induced contractions were significantly enhanced in the gels that were overlaid with bovine aortic endothelial cells (BAECs) or were cultured with conditioned medium of cultured BAECs. ATP-induced Ca(2+) transients, recorded in BASMCs cultured with conditioned medium of BAECs, were markedly augmented, but high KCl-induced Ca(2+) transients were not affected. BASMCs in control gels were spindle shaped, and those in endothelium-treated gels were more elongated and interconnected. The endothelial conditioned medium also strongly affected the intracellular distribution of actin fibers. Conditioned medium of BAECs contained TGFβ1 and TGFβ2. The TGFβ receptor antagonist SB431542 as well as simultaneous treatment with TGFβ1 and TGFβ2 neutralizing antibodies completely reversed the above effects of endothelial conditioned medium on BASMCs. BAECs medium induced phosphorylation of Smad2 and increased ATP-induced phosphorylation of myosin light chain in BASMCs. The present results indicate that the release of TGFβ1 and TGFβ2 from vascular endothelium affects the contractility of vascular smooth muscle cells by altering their morphology and agonist-induced Ca(2+) mobilization.

Nitric oxide deficiency in pulmonary hypertension: Pathobiology and implications for therapy

Nitric oxide (NO) is a diffusible gas with diverse roles in human physiology and disease. Significant progress in the understanding of its biological effects has taken place in recent years. This has led to a better understanding of the pathobiology of pulmonary hypertension (PH) and the development of new therapies. This article provides an overview of the NO physiology and its role in the pathobiology of lung diseases, particularly PH. We also discuss current and emerging specific treatments that target NO signaling pathways in PH.

A nanoparticle delivery vehicle for S-nitroso-N-acetyl cysteine: sustained vascular response

Interest in the development of nitric oxide (NO) based therapeutics has grown exponentially due to its well elucidated and established biological functions. In line with this surge, S-nitroso thiol (RSNO) therapeutics are also receiving more attention in recent years both as potential stable sources of NO as well as for their ability to serve as S-nitrosating agents; S-nitrosation of protein thiols is implicated in many physiological processes. We describe two hydrogel based RSNO containing nanoparticle platforms. In one platform the SNO groups are covalently attached to the particles (SNO-np) and the other contains S-nitroso-N-acetyl cysteine encapsulated within the particles (NAC-SNO-np). Both platforms function as vehicles for sustained activity as trans-S-nitrosating agents. NAC-SNO-np exhibited higher efficiency for generating GSNO from GSH and maintained higher levels of GSNO concentration for longer time (24 h) as compared to SNO-np as well as a previously characterized nitric oxide releasing platform, NO-np (nitric oxide releasing nanoparticles). In vivo, intravenous infusion of the NAC-SNO-np and NO-np resulted in sustained decreases in mean arterial pressure, though NAC-SNO-np induced longer vasodilatory effects as compared to the NO-np. Serum chemistries following infusion demonstrated no toxicity in both treatment groups. Together, these data suggest that the NAC-SNO-np represents a novel means to both study the biologic effects of nitrosothiols and effectively capitalize on its therapeutic potential.