The Nitric Oxide Pathway in Pulmonary Vascular Disease

Enhanced Cardiomyocyte Function in Hypertensive Rats With Diastolic Dysfunction and Human Heart Failure Patients After Acute Treatment With Soluble Guanylyl Cyclase (sGC) Activator

Aims

Our aim was to investigate the effect of nitric oxide (NO)-independent activation of soluble guanylyl cyclase (sGC) on cardiomyocyte function in a hypertensive animal model with diastolic dysfunction and in biopsies from human heart failure with preserved ejection fraction (HFpEF).

Methods

Dahl salt-sensitive (DSS) rats and control rats were fed a high-salt diet for 10 weeks and then acutely treated in vivo with the sGC activator BAY 58-2667 (cinaciguat) for 30 min. Single skinned cardiomyocyte passive stiffness (F_passive) was determined in rats and human myocardium biopsies before and after acute treatment. Titin phosphorylation, activation of the NO/sGC/cyclic guanosine monophosphate (cGMP)/protein kinase G (PKG) cascade, as well as hypertrophic pathways including NO/sGC/cGMP/PKG, PKA, calcium–calmodulin kinase II (CaMKII), extracellular signal-regulated kinase 2 (ERK2), and PKC were assessed. In addition, we explored the contribution of pro-inflammatory cytokines and oxidative stress levels to the modulation of cardiomyocyte function. Immunohistochemistry and electron microscopy were used to assess the translocation of sGC and connexin 43 proteins in the rat model before and after treatment.

Results

High cardiomyocyte F_passive was found in rats and human myocardial biopsies compared to control groups, which was attributed to hypophosphorylation of total titin and to deranged site-specific phosphorylation of elastic titin regions. This was accompanied by lower levels of PKG and PKA activity, along with dysregulation of hypertrophic pathway markers such as CaMKII, PKC, and ERK2. Furthermore, DSS rats and human myocardium biopsies showed higher pro-inflammatory cytokines and oxidative stress compared to controls. DSS animals benefited from treatment with the sGC activator, as F_passive, titin phosphorylation, PKG and the hypertrophic pathway kinases, pro-inflammatory cytokines, and oxidative stress markers all significantly improved to the level observed in controls. Immunohistochemistry and electron microscopy revealed a translocation of sGC protein toward the intercalated disc and t-tubuli following treatment in both control and DSS samples. This translocation was confirmed by staining for the gap junction protein connexin 43 at the intercalated disk. DSS rats showed a disrupted connexin 43 pattern, and sGC activator was able to partially reduce disruption and increase expression of connexin 43. In human HFpEF biopsies, the high F_passive, reduced titin phosphorylation, dysregulation of the NO–sGC–cGMP–PKG pathway and PKA activity level, and activity of kinases involved in hypertrophic pathways CaMKII, PKC, and ERK2 were all significantly improved by sGC treatment and accompanied by a reduction in pro-inflammatory cytokines and oxidative stress markers.

Conclusion

Our data show that sGC activator improves cardiomyocyte function, reduces inflammation and oxidative stress, improves sGC–PKG signaling, and normalizes hypertrophic kinases, indicating that it is a potential treatment option for HFpEF patients and perhaps also for cases with increased hypertrophic signaling.

Comparison of inhaled nitric oxide with aerosolized prostacyclin or analogues for the postoperative management of pulmonary hypertension: a systematic review and meta-analysis

Background: This study aims to compare the effectiveness of inhaled prostacyclin or its analoguesversus nitric oxide (NO) in treating pulmonary hypertension (PH) after cardiac or pulmonary surgery remains unclear.Methods: PubMed, Cochrane, and Embase databases were searched for literature published prior to December 2019 using the following keywords: inhaled, nitric oxide, prostacyclin, iloprost, treprostinil, epoprostenol, Tyvaso, flolan, and pulmonary hypertension. Randomized controlled trials and multiple-armed prospective studies that evaluated inhaled NO versus prostacyclin (or analogues) in patients for perioperative and/or postoperative PH after either cardiac or pulmonary surgery were included. Retrospective studies, reviews, letters, comments, editorials, and case reports were excluded.Results: Seven studies with a total of 195 patients were included. No difference in the improvement of mean pulmonary arterial pressure (pooled difference in mean change= -0.10, 95% CI: -3.98 to 3.78, p = .959) or pulmonary vascular resistance (pooled standardized difference in mean change= -0.27, 95% CI: -0.60 to 0.05, p = .099) were found between the two treatments. Similarly, no difference was found in other outcomes between the two treatments or subgroup analysis.Conclusions: Inhaled prostacyclin (or analogues) was comparable to inhaled NO in treating PH after cardiac or pulmonary surgery.Key messagesThis study compared the efficacy of inhaled prostacyclin or its analogues versus inhaled NO to treat PH after surgery. The two types of agent exhibited similar efficacy in managing MPAP, PVR, heart rate, and cardiac output was observed.Inhaled prostacyclin may serve as an alternative treatment option for PH after cardiac or pulmonary surgery.

Oxidative Stress in Pulmonary Fibrosis

Oxidative stress has been linked to various disease states as well as physiological aging. The lungs are uniquely exposed to a highly oxidizing environment and have evolved several mechanisms to attenuate oxidative stress. Idiopathic pulmonary fibrosis (IPF) is a progressive age-related disorder that leads to architectural remodeling, impaired gas exchange, respiratory failure, and death. In this article, we discuss cellular sources of oxidant production, and antioxidant defenses, both enzymatic and nonenzymatic. We outline the current understanding of the pathogenesis of IPF and how oxidative stress contributes to fibrosis. Further, we link oxidative stress to the biology of aging that involves DNA damage responses, loss of proteostasis, and mitochondrial dysfunction. We discuss the recent findings on the role of reactive oxygen species (ROS) in specific fibrotic processes such as macrophage polarization and immunosenescence, alveolar epithelial cell apoptosis and senescence, myofibroblast differentiation and senescence, and alterations in the acellular extracellular matrix. Finally, we provide an overview of the current preclinical studies and clinical trials targeting oxidative stress in fibrosis and potential new strategies for future therapeutic interventions. © 2020 American Physiological Society. Compr Physiol 10:509-547, 2020.

Stretch-activated Piezo1 Channel in Endothelial Cells Relaxes Mouse Intrapulmonary Arteries

In intrapulmonary arteries (IPA), endothelial cells (EC) respond to mechanical stimuli by releasing vasoactive factors to set the vascular tone. Piezo1, a stretch-activated, calcium-permeable channel, is a sensor of mechanical stress in EC. The present study was undertaken to investigate the implication of Piezo1 in the endothelium-dependent regulation of IPA tone and potential involvement of Piezo1 in pulmonary hypertension, the main disease of this circulation. IPA tone was quantified by means of a myograph in control Piezo1^+/+ mice and in mice lacking endothelial Piezo1 (EC-Piezo1^-/-). Endothelial intracellular calcium concentration ([Ca²⁺]_i) and nitric oxide (NO) production were measured, in mouse or human EC, with Fluo-4 or DAF-FM probe, respectively. Immunofluorescent labeling and patch-clamp experiments revealed the presence of Piezo1 channels in EC. Yoda1, a Piezo1 agonist, induced an endothelium-dependent relaxation that was significantly reduced in pulmonary arteries in EC-Piezo1^-/- compared with Piezo1^+/+ mice. Yoda1 as well as mechanical stimulation (by osmotic stress) increased [Ca²⁺]_i in mouse or human EC. Consequently, both stimuli increased the production of NO. NO and [Ca²⁺]_i increases were reduced in EC from Piezo1^-/- mice or in the presence of Piezo1 inhibitors. Furthermore, deletion of Piezo1 increased α-adrenergic agonist-mediated contraction. Finally, in chronically hypoxic mice, a model of pulmonary hypertension, Piezo1 still mediated arterial relaxation, and deletion of this channel did not impair the development of the disease. The present study thus demonstrates that endothelial Piezo1 contributes to intrapulmonary vascular relaxation by controlling endothelial [Ca²⁺]_i and NO production and that this effect is still present in pulmonary hypertension.

Senescence Marker Protein 30 Deficiency Exacerbates Pulmonary Hypertension in Hypoxia-Exposed Mice

Pulmonary arterial hypertension is a fatal disease caused by pulmonary arterial vasoconstriction and organic stenosis due to the proliferation of pulmonary smooth muscle cells and endothelial cells. Endothelial dysfunction, including impaired nitric oxide (NO) bioavailability, plays a crucial role in the pathogenesis of pulmonary hypertension, and endothelial nitric oxide synthase (eNOS) is an important modulator of pulmonary vasodilatation. Although senescence marker protein (SMP) 30 is known as an anti-aging protein, the role of SMP30 in pulmonary vessels is still unclear. In this study, we examined the role of SMP30 in pulmonary vasculature using SMP30-deficient mice.We used female SMP30-deficient mice and wild-type littermate (WT) mice at the age of 12 to 18 weeks. The WT and SMP30-deficient mice were exposed to normoxia or hypoxia (10% oxygen for 4 weeks). In normoxia, the right ventricular systolic pressure (RVSP) was not different between the WT and SMP30-deficient mice, but in hypoxia, the RVSP was significantly higher in the SMP30-deficient mice compared to the WT mice (P < 0.05). The hypoxia-induced increases in right ventricular hypertrophy and medial smooth muscle area of the pulmonary artery were comparable between the WT and the SMP30-deficient mice. Western blotting showed that eNOS phosphorylation in lung tissue was reduced in the SMP30-deficient mice compared to the WT mice in normoxia. However, in hypoxic conditions, eNOS phosphorylation was reduced in both the WT and SMP30-deficient mice with no differences in Akt phosphorylation.Our study demonstrated that SMP30 is involved in the development of hypoxia-induced pulmonary hypertension by impairment of eNOS activity.

miR-1 induces endothelial dysfunction in rat pulmonary arteries

Endothelial dysfunction plays a central role in the pathophysiology of pulmonary arterial hypertension (PAH). MicroRNAs (miRNAs) are small single-strand and non-coding RNAs that negatively regulate gene function by binding to the 3'-untranslated region (3'-UTR) of specific mRNAs. microRNA-1 (miR-1) is upregulated in plasma from idiopathic PAH patients and in lungs from an experimental model of PAH. However, the role of miRNA-1 on endothelial dysfunction is unknown. The aim of this study was to analyze the effects of miR-1 on endothelial function in rat pulmonary arteries (PA). Endothelial function was studied in PA from PAH or healthy animals and mounted in a wire myograph. Some PA from control animals were transfected with miR-1 or scramble miR. Superoxide anion production by miR-1 was quantified by dihydroethidium (DHE) fluorescence in rat PA smooth muscle cells (PASMC). Bioinformatic analysis identified superoxide dismutase-1 (SOD1), connexin-43 (Cx43), caveolin 2 (CAV2) and Krüppel-like factor 4 (KLF4) as potential targets of miR-1. The expression of SOD1, Cx43, CAV2, and KLF4 was determined by qRT-PCR and western blot in PASMC. PA incubated with miR-1 presented decreased endothelium-dependent relaxation to acetylcholine. We also found an increase in the production of O₂^- and decreased expression of SOD1, Cx43, CAV2, and KLF4 in PASMC induced by miR-1, which may contribute to endothelial dysfunction. In conclusion, these data indicate that miR-1 induces endothelial dysfunction, suggesting a pathophysiological role in PAH.

Endothelial dysfunction: from the particular to the general. Return to the «Old Paradigm»?

The vascular endothelium is a heterogeneous structure with diverse functions, being an active metabolic system. Endothelial cells mediate inflammatory and immune processes, regulate leukocyte adhesion, permeability and vascular tone, participate in the hemostasis system, stimulate the processes of angiogenesis. Endothelial dysfunction can initiate individual disorders, but more often it is a universal link in the pathogenesis of many diseases. Currently, endothelial dysfunction is presented as an imbalance between the production of vasodilating, angioprotective, antiproliferative factors, on the one hand, and vasoconstrictive, prothrombotic, proliferative factors, on the other hand. The manifestations of endothelial dysfunction, the direction and severity of these changes may vary depending on the disease. The review provides examples of combined endothelial disorders in the most studied and common diseases (essential hypertension, type 2 diabetes, systemic diseases of the connective tissue, atherosclerosis, and malignant tumors). Despite the presence of rare cases of isolated endothelial dysfunction, it can be argued that in the absolute majority of diseases, endothelial dysfunction has combined type of violations. The allocation of individual endothelial disorder spectra, typical for a specific disease, is problematic, due to the universality and nonspecificity of the manifestations of endothelial dysfunction. These conclusions allow us to return to the origins of this problem, considering endothelial dysfunction as a holistic concept, not limited to a certain range of its disorders.

A focus on riociguat in the treatment of pulmonary arterial hypertension

Current treatment of pulmonary arterial hypertension (PAH) targets three signalling pathways: the nitric oxide (NO) pathway, the endothelin pathway and the prostacyclin pathway. Riociguat is a soluble guanylate cyclase stimulator, acting via the NO pathway in a new way: unlike other common drugs targeting this pathway (eg tadalafil and sildenafil), riociguat acts independently of endogenous NO. This MiniReview focuses on PAH treatment with riociguat and on its advantages and disadvantages compared with other drugs targeting the NO pathway. In the PATENT-1 trial (NCT00810693), riociguat improved significantly the 6-minute walking distance in patients suffering from PAH, with a mean difference (MD) of 36 m compared with a placebo group. The results are comparable to those found for its competitors tadalafil (MD of 33 m) and sildenafil (MD of 50 m) in the PHIRST-1 trial (NCT00125918) and the SUPER-1 trial (NCT00644605). No obvious advantages were found regarding pharmacokinetic features and adverse events. In the RESPITE study (NCT02007629), patients with PAH with insufficient response to treatment with tadalafil or sildenafil were switched to riociguat. These results indicate that riociguat might be superior regarding efficacy to PDE-5 inhibitors in a patient group, where endogenous NO production might be insufficient. This finding was further examined in the REPLACE study (NCT02891850). Moreover, riociguat has shown promising anti-proliferative, anti-inflammatory and anti-fibrotic effects in animal models. Further investigations are needed to determine whether this applies also to human beings. Taken together, riociguat induces vasodilation of the pulmonary arteries and leads to an improvement in the ability to carry out physical activity.

Fumarase Overexpression Abolishes Hypertension Attributable to endothelial NO synthase Haploinsufficiency in Dahl Salt-Sensitive Rats

Human blood pressure salt sensitivity is associated with changes in urinary metabolites related to fumarase (Fh) and nitric oxide (NO) metabolism, and fumarase promotes NO production through an arginine regeneration pathway. We examined the role of the fumarase-NO pathway in the development of hypertension using genetically engineered rat models. Dahl salt-sensitive (SS) rats with heterozygous mutation of eNOS (endothelial NO synthase or Nos3; SS-Nos3^+/-) were bred with SS rats with a hemizygous Fh transgene. SS-Nos3^+/- rats without the Fh transgene (SS-Nos3^+/-/Fh^0/0) developed substantial hypertension with a mean arterial pressure of 134.2±3.7 mm Hg on a 0.4% NaCl diet and 178.0±3.5 mm Hg after 14 days on a 4% NaCl diet. Mean arterial pressure decreased remarkably to 123.1±1.4 mm Hg on 0.4% NaCl, and 143.3±1.5 mm Hg on 4% NaCl in SS-Nos3^+/- rats with a Fh transgene (SS-Nos3^+/-/Fh^0/1), and proteinuria, renal fibrosis, and tubular casts were attenuated in SS-Nos3^+/-/Fh^0/1 rats compared with SS-Nos3^+/-/Fh^0/0 rats. eNOS protein abundance decreased in rats with the Nos3 heterozygous mutation, which was not influenced by Fh overexpression in rats on the 0.4% NaCl diet. However, the decrease in NO metabolite in the renal outer medulla of SS-Nos3^+/-/Fh^0/0 rats on the 0.4% NaCl diet was reversed in SS-Nos3^+/-/Fh^0/1 rats, and levels of L-arginine, but not the other 12 amino acids analyzed, were significantly higher in SS-Nos3^+/-/Fh^0/1 rats than in SS-Nos3^+/+/Fh^0/0 rats. In conclusion, fumarase has potent effects in restoring NO production and blunting the development of hypertension attributable to eNOS haploinsufficiency.

Activation of Kv 7 channels as a novel mechanism for NO/cGMP-induced pulmonary vasodilation

BACKGROUND AND PURPOSE

The NO/cGMP pathway represents a major physiological signalling controlling tone in pulmonary arteries (PA), and drugs activating this pathway are used to treat pulmonary arterial hypertension. K_v channels expressed in PA smooth muscle cells (PASMCs) are key determinants of vascular tone. We aimed to analyse the contribution of K_v 1.5 and K_v 7 channels in the electrophysiological and vasodilating effects evoked by NO donors and the GC stimulator riociguat in PA.

EXPERIMENTAL APPROACH

K_v currents were recorded in isolated rat PASMCs using the patch-clamp technique. Vascular reactivity was assessed in a wire myograph.

KEY RESULTS

The NO donors diethylamine NONOate diethylammonium (DEA-NO) and sodium nitroprusside hyperpolarized the membrane potential and induced a bimodal effect on K_v currents (augmenting the current between -40 and -10 mV and decreasing it at more depolarized potentials). The hyperpolarization and the enhancement of the current were suppressed by K_v 7 channel inhibitors and by the GC inhibitor ODQ but preserved when K_v 1.5 channels were inhibited. Additionally, DEA-NO enhanced K_v 7.5 currents in COS7 cells expressing the KCNQ5 gene. Riociguat increased K_v currents at all potentials ≥-40 mV and induced membrane hyperpolarization. Both effects were prevented by K_v 7 inhibition. Likewise, PA relaxation induced by NO donors and riociguat was attenuated by K_v 7 inhibitors.

CONCLUSIONS AND IMPLICATIONS

NO donors and riociguat enhance K_v 7 currents, leading to PASMC hyperpolarization. This mechanism contributes to NO/cGMP-induced PA vasodilation. Our study identifies K_v 7 channels as a novel mechanism of action of vasodilator drugs used in the treatment of pulmonary arterial hypertension.

A Phase I Study to Show the Relative Bioavailability and Bioequivalence of Fixed-Dose Combinations of Ambrisentan and Tadalafil in Healthy Subjects

PURPOSE

Pulmonary arterial hypertension (PAH) is a life-threatening disease that typically causes shortness of breath and exercise intolerance. Combination therapy with ambrisentan and tadalafil has proven to be more effective at preventing clinical failure events in patients with PAH than either drug alone. The aim of this study was to evaluate the bioequivalence of an ambrisentan/tadalafil fixed-dose combination (FDC) compared with co-administration of the 2 monotherapies.

METHODS

This 3-part, randomized, single-dose, open-label crossover study was conducted in healthy volunteers. The first part of the study consisted of a 5-way crossover that compared the relative bioavailability of 4 FDC formulations (10-mg ambrisentan + 40-mg tadalafil) with co-administered reference monotherapies. One formulation was selected and its relative bioavailability was assessed when produced in 3 different granulation sizes during the second part of the study. In the third part of the study, the bioequivalence of the candidate FDC with the reference monotherapies was evaluated for the 10-mg/40-mg dose strength, in addition to 2 other dose strengths (5 mg/20 mg and 5 mg/40 mg). For all parts of the study, blood samples were taken at regular intervals after each dose, ambrisentan and tadalafil concentrations determined, and pharmacokinetic (PK) parameters (C_max, AUC_0-∞, and AUC_0-t) obtained. Test/reference ratios of the geometric means of PK parameters were used to evaluate bioequivalence. Safety and tolerability were assessed by recording adverse events and monitoring vital signs, ECGs, and clinical laboratory data.

FINDINGS

Of the 174 subjects screened for eligibility, 112 were allocated to a randomized treatment sequence across all study parts, and 100 completed their full assigned treatments. All 4 FDC formulations tested during part 1 of the study yielded PK parameters similar those of the reference treatments. In part 2, granulation size was found to not affect the relative bioavailability of the selected formulation. In part 3, the selected FDC was found to be bioequivalent to co-administration of the monotherapies in both the fasted and fed states. The FDC was also found to be bioequivalent to the reference treatments at the 2 additional dose strengths. All but one of the adverse events was mild to moderate in intensity, and no serious adverse events were reported.

IMPLICATIONS

An ambrisentan/tadalafil FDC was bioequivalent to concurrently administered monotherapies and therefore represents a viable alternative treatment to co-administration. Use of an FDC is likely to be associated with reduced costs and improved patient compliance. ClinicalTrials.gov identifier: NCT02688387.

Ameliorative effects of Annona muricata Linn. (Annonaceae) against potassium dichromate-induced hypertension in vivo: involvement of Kim-1/p38 MAPK/Nrf2 signaling

Background Recently, the incidences of hypertension and environmental pollution have increased significantly. This study investigates the antihypertensive effect of Annona muricata extract against K2Cr2O7-induced hypertension. Methods Fifty rats were used for this study, which were divided into five groups of 10 rats each. Rats in Group A received normal saline, and those in Groups B, C, D, and E were treated with A. muricata extract alone at 250 mg/kg, K2Cr2O7 at 30 mg/kg, pretreated with the extract at 250 mg/kg, and pretreated with gallic acid at 60 mg/kg for 14 days, respectively, and thereafter administered with a single intraperitoneal injection of K2Cr2O7 at 30 mg/kg. Results Administration of K2Cr2O7 significantly increased systolic, diastolic, and mean arterial pressure and caused prolonged QT and QTc intervals. Further, pretreatment with the extract at 250 mg/kg and gallic acid at 60 mg/kg significantly reduced high blood pressure to near-normal values. K2Cr2O7 intoxication led to significant increases in serum advanced oxidative protein products, myeloperoxidase, and xanthine oxidase, while serum nitric oxide (NO) also reduced significantly. Immunohistochemistry of the renal kidney injury molecule (Kim-1) and p38 MAPK showed increased expressions following the administration of K2Cr2O7 together with the downregulation of nuclear factor erythroid 2-related factor 2 (Nrf2). Pretreatment with the extract at 250 mg/kg and gallic acid at 60 mg/kg also increased the expressions of Nrf2 and downregulated Kim-1 and p38. Conclusion Together, we found that pretreatment with the extract at 250 mg/kg and gallic acid at 60 mg/kg normalized the blood pressure, reduced the markers of oxidative stress, and improved the antioxidant defense system and serum NO bioavailability.

Sulodexide promotes arterial relaxation via endothelium-dependent nitric oxide-mediated pathway

Sulodexide (SDX) is a highly purified glycosaminoglycan with antithrombotic and profibrinolytic properties and reported benefits in thrombotic and atherosclerotic vascular disorders. However, the effects of SDX on vascular function are unclear. We tested whether SDX affects vascular relaxation and examined the potential underlying mechanisms. Isolated segments of male rat abdominal aorta and mesenteric artery were suspended in a tissue bath, and the changes in arterial contraction/relaxation were measured. The α-adrenergic receptor agonist phenylephrine (Phe) (10^-9-10^-5 M) caused concentration-dependent aortic and mesenteric artery contraction that was reduced in tissues pretreated with SDX (1 mg/ml). In aortic and mesenteric arterial segments precontracted with submaximal concentration of Phe (3 × 10^-7-6 × 10^-7 M), SDX (0.001-1 mg/ml) caused concentration-dependent relaxation. To test the role of endothelium, SDX-induced relaxation was compared with that of acetylcholine (ACh), a known activator of endothelium-dependent relaxation. In Phe precontracted aorta, ACh relaxation was abolished and SDX relaxation was significantly inhibited by endothelium removal or the nitric oxide synthase (NOS) inhibitor N_ω-nitro-l-arginine methyl ester (L-NAME), suggesting a role of NO. In mesenteric artery, ACh relaxation was abolished by endothelium removal, partially blocked by L-NAME, and completely blocked by a mixture of indomethacin, a cyclooxygenase inhibitor and blocker of the PGI₂-cAMP pathway, and tetraethylammonium, a blocker of K⁺ channels and EDHF-dependent hyperpolarization pathway. In comparison, SDX relaxation of mesenteric artery was almost completely inhibited by endothelium removal or NOS inhibitor L-NAME. SDX enhanced vascular relaxation and increased nitrate/nitrite production in response to all ACh concentrations in the aorta, but only to low ACh concentrations (<10^-7 M) in mesenteric artery. SDX did not affect aortic or mesenteric artery endothelium-independent relaxation to the NO donor sodium nitroprusside. Thus, SDX promotes arterial relaxation via a mechanism involving endothelium-dependent NO production; an effect that could enhance vasodilation and decrease vasoconstriction in vascular disorders.

Semaphorin 3A Is Effective in Reducing Both Inflammation and Angiogenesis in a Mouse Model of Bronchial Asthma

Semaphorin 3A (sema3A) belongs to the sub-family of the immune semaphorins that function as regulators of immune-mediated inflammation. Sema3A is a membrane associated molecule on T regulatory cells and on B regulatory cells. Being transiently ligated to the cell surface of these cells it is suggested to be a useful marker for evaluating their functional status. In earlier studies, we found that reduced sema3A concentration in the serum of asthma patients as well as reduced expression by Treg cells correlates with asthma disease severity. Stimulation of Treg cells with recombinant sema3A induced a significant increase in FoxP3 and IL-10 expression. To find out if sema3A can be of benefit to asthma patients, we evaluated the effect of sema3A injection in a mouse model of asthma. BALB\c-mice were sensitized using ovalbumin (OVA) + adjuvant for 15 days followed by OVA aerosol inhalation over five consecutive days. Four hours following air ways sensitization on each of the above days- 15 of these mice were injected intraperitoneally with 50 μg per mouse of recombinant human sema3A-FR and the remaining 15 mice were injected with a similarly purified vehicle. Five days later the mice were sacrificed, broncheo-alveolar lavage (BAL) was collected and formalin-fixed lung biopsies taken and analyzed. In sema3A treated mice, only 20% of the bronchioles and arterioles were infiltrated by inflammatory cells as compared to 90% in the control group (p = 0.0079). In addition, eosinophil infiltration was also significantly increased in the control group as compared with the sema3A treated mice. In sema3A treated mice we noticed only a small number of mononuclear and neutrophil cells in the BAL while in the control mice, the BAL was enriched with mononuclear and neutrophil cells. Finally, in the control mice, angiogenesis was significantly increased in comparison with sema3A treated mice as evidenced by the reduced concentration of microvessels in the lungs of sema3A treated mice. To conclude, we find that in this asthma model, sema3A functions as a potent suppressor of asthma related inflammation that has the potential to be further developed as a new therapeutic for the treatment of asthma.

TMPRSS2-ERG activates NO-cGMP signaling in prostate cancer cells

The aberrant activation of the ERG oncogenic pathway due to the TMPRSS2-ERG gene fusion is the major event that contributes to prostate cancer (PCa) development. However, the critical downstream effectors that can be therapeutically targeted remain to be identified. In this study, we have found that the expression of the α1 and β1 subunits of soluble guanylyl cyclase (sGC) was directly and specifically regulated by ERG in vitro and in vivo and was significantly associated with TMPRSS2-ERG fusion in clinical PCa cohorts. sGC is the major mediator of nitric oxide (NO)-cGMP signaling in cells that, upon NO binding, catalyzes the synthesis of cGMP and subsequently activates protein kinase G (PKG). We showed that cGMP synthesis was significantly elevated by ERG in PCa cells, leading to increased PKG activity and cell proliferation. Importantly, we also demonstrated that sGC inhibitor treatment repressed tumor growth in TMPRSS2-ERG-positive PCa xenograft models and can act in synergy with a potent AR antagonist, enzalutamide. This study strongly suggests that targeting NO-cGMP signaling pathways may be a novel therapeutic strategy to treat PCa with TMPRSS2-ERG gene fusion.

Protective effect of atorvastatin on oxidative stress in streptozotocin-induced diabetic rats independently their lipid-lowering effects

In the present study, we investigate the effects of atorvastatin on the lipid profile, oxidative stress, and liver enzyme markers, and its protective activity against diabetic complications, in streptozotocin (STZ)-induced diabetic rats. Fasting blood glucose (FBG), triglyceride (TG), total cholesterol (TC), and high-density lipoprotein (HDL) levels, as well as alanine aminotransferase (ALT) and aspartate aminotransferase (AST) enzyme activities, were measured 7 weeks after the administration of STZ and atorvastatin. Thiobarbituric acid reactive substances (TBARS), non-protein associated sulfhydryl (NP-SH), total sulfhydryl (T-SH), and nitric oxide (NO) levels were measured to evaluate oxidative stress. Atorvastatin was found to inhibit ALT and AST activities and to reduce FBG levels in rats with STZ-induced diabetes. Moreover, atorvastatin treatment significantly reduced lipid peroxidation in kidney, heart, and eye tissues (P < 0.001, for all), and resulted in a significant increase in NP-SH levels in brain tissues (P < 0.001). Total NO and nitrate levels increased significantly after atorvastatin treatment (P < 0.01). Our results revealed that atorvastatin has a protective effect against STZ-induced oxidative damage by reducing TBARS levels and increasing NP-SH levels, has a hepatoprotective effect by decreasing ALT and AST activities. It also shows the antihyperglycemic activity by lowering FBG levels.

Gene polymorphism associated with endothelial nitric oxide synthase (4VNTR, G894T, C786T) and unexplained recurrent spontaneous abortion risk: A meta-analysis

To evaluate the association between endothelial nitric oxide synthase gene polymorphisms (4VNTR A/B, G894T, C786T) and risk of URSA.Related case-control studies were collected by computers. A meta-analysis was conducted using Stata 12.0 software to assess the strength of association.Altogether 37 articles were examining the relationship between endothelial nitric oxide synthase gene polymorphisms and URSA, among which sixteen (16) studies were related to 4VNTR, twelve (12) to G894T, and nine (9) to C786T, the study suggested that 4VNTR A/B polymorphism was closely connected with URSA risk under all gene models except for recessive model (AA vs. BB + AB). The integrated result which indicated the association between G894T gene mutation and URSA risk had been shown under homozygote (TT vs. GG; OR 1.585, 95%CI 1.175-2.138) and recessive models (TT vs. TG + GG; OR 1.530, 95%CI 1.142-2.052). Considering heterogeneity in the remaining gene models, subgroup analysis was performed on ethnicity, and the results showed that it was the dominant (TT + TG vs. GG; OR 1.585, 95%CI 1.175-2.138) and additive models (T vs. G; OR 1.727, 95%CI 1.372-2.175) of G894T in Asians and the heterozygote model (TG vs. GG; OR 1.015, 95%CI 0.846-1.217) in Caucasians that were associated with URSA (P < .05). Besides C786T gene was significantly connected with URSA under all models except for additive model (T vs. C).It is of great guiding significance for screening out and preventing URSA among high-risk women via testing on 4VNTR A/B, G894T, C786T eNOS under gene models mentioned above which are closely associated with URSA.

Impact of nitrate therapy on the expression of caveolin-1 and its phosphorylated isoform in lungs in the model of monocrotaline induced pulmonary hypertension

Aim: Nitric oxide signalling pathway showed to be one of the crucial factors in the treatment and pathogenesis of pulmonary arterial hypertension. The aim of this study was to determine the effect of administration of inorganic nitrate, NaNO3, on the expression of caveolin-1 and its phosphorylated isoform (pTyr14Cav-1) in lungs in the experimental model of monocrotaline induced pulmonary hypertension.

Methods: 10 weeks old male Wistar rats were subcutaneously injected with 60 mg/kg dose of monocrotaline (MCT) or vehicle (CON). Twelve days after the injection, part of the MCT group was receiving 0.3 mM NaNO3 (MCT+N0.3) daily in the drinking water and rest was receiving 0.08% NaCl solution. Four weeks after MCT administration, the rats were sacrificed in CO2. Protein expression in lungs was determined by western blot.

Results: We observed a significant decrease in the caveolin-1 expression and a significant shift towards the expression of pTyr14Cav-1 in the group treated with nitrate (p < 0.05).

Conclusion: NaNO3 administration affected the expression of caveolin-1 and the ratio of its active (phosphorylated) isoform increased.

Oxymatrine prevents the development of monocrotaline-induced pulmonary hypertension via regulation of the NG, NG-dimethyl-L-arginine metabolism pathways in rats

The purpose of this study was to investigate the potential effect of oxymatrine in monocrotaline-induced pulmonary hypertension and its possible influence on the N^G,N^G-dimethyl-L-arginine (ADMA) metabolism pathway. Pulmonary hypertension was induced in rats by a single-dose injection of monocrotaline (60 mg/kg). Daily oral administration of oxymatrine (25, 50 and 100 mg/kg) was started on the day following the monocrotaline injection for 28 days. Oxymatrine (50 and 100 mg/kg) significantly attenuated monocrotaline-induced lung and right ventricular hypertrophy, right ventricular systolic pressure elevation, and right ventricular dysfunction. Oxymatrine also reduced the thickening of monocrotaline-induced pulmonary arterial medial wall. Meanwhile, oxymatrine normalized the level of pulmonary asymmetric ADMA and attenuated the upregulated expression of protein arginine methyltransferase 1 (PRMT1). Oxymatrine had no effect on the expression of protein arginine methyltransferase 2 (PRMT2) and N^G,N^G-Dimethylarginine dimethylaminohydrolase 1 (DDAH1), which were upregulated in monocrotaline-induced pulmonary arterial hypertensive rats. However, the expression of the protein N^G,N^G-Dimethylarginine dimethylaminohydrolase 2 (DDAH2) did not differ among all groups (all P﹥0.05). These results suggest that oxymatrine may offer protective effects on the development of pulmonary hypertension by ameliorating pulmonary remodeling and modulating the ADMA metabolism pathway.

Nanotherapeutics for Treatment of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a devastating and fatal chronic lung disease. While current pharmacotherapies have improved patient quality of life, PAH drugs suffer from limitations in the form of short-term pharmacokinetics, instability, and poor organ specificity. Traditionally, nanotechnology-based delivery strategies have proven advantageous at increasing both circulation lifetimes of chemotherapeutics and accumulation in tumors due to enhanced permeability through fenestrated vasculature. Importantly, increased nanoparticle (NP) accumulation in diseased tissues has been observed pre-clinically in pathologies characterized by endothelial dysfunction and remodeled vasculature, including myocardial infarction and heart failure. Recently, this phenomenon has also been observed in preclinical models of PAH, leading to the exploration of NP-based drug delivery as a therapeutic modality in PAH. Herein, we discussed the advantages of NPs for efficacious treatment of PAH, including heightened therapeutic delivery to diseased lungs for increased drug bioavailability, as well as highlighted innovative nanotherapeutic approaches for PAH.