Novel Mechanism of Action for Hydralazine

Associations between HIFs and tumor immune checkpoints: mechanism and therapy

Hypoxia, which activates a variety of signaling pathways to enhance tumor cell growth and metabolism, is among the primary features of tumor cells. Hypoxia-inducible factors (HIFs) have a substantial impact on a variety of facets of tumor biology, such as epithelial-mesenchymal transition, metabolic reprogramming, angiogenesis, and improved radiation resistance. HIFs induce hypoxia-adaptive responses in tumor cells. Many academics have presented preclinical and clinical research targeting HIFs in tumor therapy, highlighting the potential applicability of targeted HIFs. In recent years, the discovery of numerous pharmacological drugs targeting the regulatory mechanisms of HIFs has garnered substantial attention. Additionally, HIF inhibitors have attained positive results when used in conjunction with traditional oncology radiation and/or chemotherapy, as well as with the very promising addition of tumor immunotherapy. Immune checkpoint inhibitors (CPIs), which are employed in a range of cancer treatments over the past decades, are essential in tumor immunotherapy. Nevertheless, the use of immunotherapy has been severely hampered by tumor resistance and treatment-related toxicity. According to research, HIF inhibitors paired with CPIs may be game changers for multiple malignancies, decreasing malignant cell plasticity and cancer therapy resistance, among other things, and opening up substantial new pathways for immunotherapy drug development. The structure, activation mechanisms, and pharmacological sites of action of the HIF family are briefly reviewed in this work. This review further explores the interactions between HIF inhibitors and other tumor immunotherapy components and covers the potential clinical use of HIF inhibitors in combination with CPIs.

Angiogenesis induction as a key step in cardiac tissue Regeneration: From angiogenic agents to biomaterials

Cardiovascular diseases are the leading cause of death worldwide. After myocardial infarction, the vascular supply of the heart is damaged or blocked, leading to the formation of scar tissue, followed by several cardiac dysfunctions or even death. In this regard, induction of angiogenesis is considered as a vital process for supplying nutrients and oxygen to the cells in cardiac tissue engineering. The current review aims to summarize different approaches of angiogenesis induction for effective cardiac tissue repair. Accordingly, a comprehensive classification of induction of pro-angiogenic signaling pathways through using engineered biomaterials, drugs, angiogenic factors, as well as combinatorial approaches is introduced as a potential platform for cardiac regeneration application. The angiogenic induction for cardiac repair can enhance patient treatment outcomes and generate economic prospects for the biomedical industry. The development and commercialization of angiogenesis methods often involves collaboration between academic institutions, research organizations, and biomedical companies.

New Ideas for the Prevention and Treatment of Preeclampsia and Their Molecular Inspirations

Preeclampsia (PE) is a pregnancy-specific disorder affecting 4-10% of all expectant women. It greatly increases the risk of maternal and foetal death. Although the main symptoms generally appear after week 20 of gestation, scientific studies indicate that the mechanism underpinning PE is initiated at the beginning of gestation. It is known that the pathomechanism of preeclampsia is strongly related to inflammation and oxidative stress, which influence placentation and provoke endothelial dysfunction in the mother. However, as of yet, no "key players" regulating all these processes have been discovered. This might be why current therapeutic strategies intended for prevention or treatment are not fully effective, and the only effective method to stop the disease is the premature induction of delivery, mostly by caesarean section. Therefore, there is a need for further research into new pharmacological strategies for the treatment and prevention of preeclampsia. This review presents new preventive methods and therapies for PE not yet recommended by obstetrical and gynaecological societies. As many of these therapies are in preclinical studies or under evaluation in clinical trials, this paper reports the molecular targets of the tested agents or methods.

Harnessing EGLN1 Gene Editing to Amplify HIF-1α and Enhance Human Angiogenic Response

Therapeutic angiogenesis has been the focus of hundreds of clinical trials but approval for human treatment remains elusive. Current strategies often rely on the upregulation of a single proangiogenic factor, which fails to recapitulate the complex response needed in hypoxic tissues. Hypoxic oxygen tensions dramatically decrease the activity of hypoxia inducible factor prolyl hydroxylase 2 (PHD2), the primary oxygen sensing portion of the hypoxia inducible factor 1 alpha (HIF-1α) proangiogenic master regulatory pathway. Repressing PHD2 activity increases intracellular levels of HIF-1α and impacts the expression of hundreds of downstream genes directly associated with angiogenesis, cell survival, and tissue homeostasis. This study explores activating the HIF-1α pathway through Sp Cas9 knockout of the PHD2 encoding gene EGLN1 as an innovative in situ therapeutic angiogenesis strategy for chronic vascular diseases. Our findings demonstrate that even low editing rates of EGLN1 lead to a strong proangiogenic response regarding proangiogenic gene transcription, protein production, and protein secretion. In addition, we show that secreted factors of EGLN1 edited cell cultures may enhance human endothelial cell neovascularization activity in the context of proliferation and motility. Altogether, this study reveals that EGLN1 gene editing shows promise as a potential therapeutic angiogenesis strategy.

Computational screening of FDA-approved drugs to identify potential aromatase receptor inhibitors for polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common cause of infertility without ovulation. Aromatase inhibitors were first proposed as new ovulation-inducing drugs in anovulatory women with an inadequate response to clomiphene. Letrozole is an aromatase inhibitor used as an ovulation inducer in infertile women due to PCOS. However, there is no definitive treatment for women with PCOS and the treatments are mostly symptomatic. In this study, we intend to introduce alternative drugs to letrozole using the library of FDA-approved drugs and evaluate the interaction of these drugs with the aromatase receptor. For this aim, molecular docking was performed to identify interactions of FDA-approved drugs with essential residues in the active site of the aromatase receptor. 1614 FDA-approved drugs were docked with aromatase receptor using AutoDock Vina. Molecular dynamics (MD) simulation study was also performed for 100 ns to verify the stability of the drug-receptor complexes. MMPBSA analysis evaluate the binding energy of selected complexes. Finally, acetaminophen, alendronate, ascorbic acid, aspirin, glutamine, hydralazine, mesalazine and pseudoephedrine drugs showed the best results in interaction with aromatase receptor based on computational studies. These drugs can be introduced as an alternative to letrozole for treating PCOS.Communicated by Ramaswamy H. Sarma.

Loss of Blood-Brain Barrier Integrity in an In Vitro Model Subjected to Intermittent Hypoxia: Is Reversion Possible with a HIF-1α Pathway Inhibitor?

Several sleep-related breathing disorders provoke repeated hypoxia stresses, which potentially lead to neurological diseases, such as cognitive impairment. Nevertheless, consequences of repeated intermittent hypoxia on the blood-brain barrier (BBB) are less recognized. This study compared two methods of intermittent hypoxia induction on the cerebral endothelium of the BBB: one using hydralazine and the other using a hypoxia chamber. These cycles were performed on an endothelial cell and astrocyte coculture model. Na-Fl permeability, tight junction protein, and ABC transporters (P-gp and MRP-1) content were evaluated with or without HIF-1 inhibitors YC-1. Our results demonstrated that hydralazine as well as intermittent physical hypoxia progressively altered BBB integrity, as shown by an increase in Na-Fl permeability. This alteration was accompanied by a decrease in concentration of tight junction proteins ZO-1 and claudin-5. In turn, microvascular endothelial cells up-regulated the expression of P-gp and MRP-1. An alteration was also found under hydralazine after the third cycle. On the other hand, the third intermittent hypoxia exposure showed a preservation of BBB characteristics. Furthermore, inhibition of HIF-1α with YC-1 prevented BBB dysfunction after hydralazine treatment. In the case of physical intermittent hypoxia, we observed an incomplete reversion suggesting that other biological mechanisms may be involved in BBB dysfunction. In conclusion, intermittent hypoxia led to an alteration of the BBB model with an adaptation observed after the third cycle.

Hydralazine Revives Cellular and Ocular Lens Health-Span by Ameliorating the Aging and Oxidative-Dependent Loss of the Nrf2-Activated Cellular Stress Response

A major hallmark of aging-associated diseases is the inability to evoke cellular defense responses. Transcriptional protein Nrf2 (nuclear factor erythroid-derived 2-related factor) plays a pivotal role in the oxidative stress response, cellular homeostasis, and health span. Nrf2's activation has been identified as a therapeutic target to restore antioxidant defense in aging. Here, we demonstrated that FDA-approved drug, hydralazine (Hyd), was a reactivator of the Nrf2/ARE (antioxidant response element) pathway in various ages and types of mouse (m) or human (h) lens epithelial cells (LECs) and mice lenses in-vitro/in-vivo. This led to Hyd-driven abatement of carbonyls, reduced reactive oxygen species (ROS), and reduced 4-HNE/MDA-adducts with cytoprotection, and extended lens healthspan by delaying/preventing lens opacity against aging/oxidative stress. We elucidated that Hyd activated the protective signaling by inducing Nrf2 to traverse from the cytoplasm to the nucleus and potentiated the ARE response by direct interaction of Nrf2 and ARE sequences of the promoter. Loss-of-function study and cotreatment of Hyd and antioxidant, N-acetyl cysteine (NAC) or Peroxiredoxin (Prdx)6, specified that Nrf2/ARE-driven increase in the promoter activity was Hyd-dependent. Our study provides proof-of concept evidence and, thereby, paves the way to repurposing Hyd as a therapeutic agent to delay/prevent aging and oxidative-related disorders.

Potential Impacts of Hydralazine as a Novel Antioxidant on Cardiovascular and Renal Disease-Beyond Vasodilation and Blood Pressure Lowering

Hydralazine is a traditional antihypertensive drug that was developed several decades ago. Its most well-known effect is blood pressure lowering by arterial vasodilation. While mainly used an adjunct treatment for clinical hypertension or chronic heart failure, this old drug has also shown potential as a repurposing drug for the atherosclerosis vascular disease and various kidney diseases. Recent experimental studies suggest that hydralazine exerts antioxidative, anti-apoptotic, and HIF-1α stabilization effects for angiogenesis and vascular protection. Hydralazine also exerts reno-protective effects via its antioxidation, DNA demethylation, and anti-inflammation abilities. The above evidence provides advanced rationales for new applications of this drug beyond blood pressure lowering and arterial vasodilation. Here, we summarized the recent experimental advances in the use of hydralazine for either a vascular disease or kidney diseases, or both. Given the wide populations of people with cardiovascular and/or kidney diseases, future studies are worth validating the potential impacts of hydralazine on the clinical outcomes in selected patients.

Discovery of glyantrypine-family alkaloids as novel antiviral and antiphytopathogenic-fungus agents

BACKGROUND

Plant diseases caused by viruses and fungi have caused great losses to crop quality and yield. The discovery of novel and efficient antiviral and antiphytopathogenic-fungus agents is urgently needed. It is the most important pesticide innovation strategy to find active compounds from natural products. Here, glyantrypine-family alkaloids were taken as the parent structures and a series of their derivatives were designed through molecular splicing, ring expansion, and ring contraction strategies, and synthesized. The anti-tobacco mosaic virus (TMV) activities and antifungal activities of these alkaloids were systematically investigated for the first time.

RESULT

The antiviral activities of compounds 7bb, 7bc, 11c, 18b, 18d, 28d, and 28e are equivalent to or better than that of ribavirin (inhibitory rates 39%, 37%, and 40% at 500 μg mL^-1 for inactivation, curative, and protection activity in vivo, respectively). Compounds 18d and 28d with good antiviral activities were selected for antiviral mode of action studies, which indicated that these alkaloids could achieve good antiviral effects by inhibiting TMV particle extension during assembly. These compounds also exhibited broad-spectrum fungicidal activities.

CONCLUSION

Glyantrypine-family alkaloids and their derivatives were synthesized and evaluated for anti-TMV and fungicidal activities for the first time. Compounds 18d and 28d with excellent antiviral activities and compound 7bc with remarkable fungicidal activity emerged as novel lead compounds. This study lays a foundation for the application of glyantrypine alkaloids in plant protection.

Hydralazine protects the heart against acute ischaemia/reperfusion injury by inhibiting Drp1-mediated mitochondrial fission

AIMS

Genetic and pharmacological inhibition of mitochondrial fission induced by acute myocardial ischaemia/reperfusion injury (IRI) has been shown to reduce myocardial infarct size. The clinically used anti-hypertensive and heart failure medication, hydralazine, is known to have anti-oxidant and anti-apoptotic effects. Here, we investigated whether hydralazine confers acute cardioprotection by inhibiting Drp1-mediated mitochondrial fission.

METHODS AND RESULTS

Pre-treatment with hydralazine was shown to inhibit both mitochondrial fission and mitochondrial membrane depolarisation induced by oxidative stress in HeLa cells. In mouse embryonic fibroblasts (MEFs), pre-treatment with hydralazine attenuated mitochondrial fission and cell death induced by oxidative stress, but this effect was absent in MEFs deficient in the mitochondrial fission protein, Drp1. Molecular docking and surface plasmon resonance studies demonstrated binding of hydralazine to the GTPase domain of the mitochondrial fission protein, Drp1 (KD 8.6±1.0 µM), and inhibition of Drp1 GTPase activity in a dose-dependent manner. In isolated adult murine cardiomyocytes subjected to simulated IRI, hydralazine inhibited mitochondrial fission, preserved mitochondrial fusion events, and reduced cardiomyocyte death (hydralazine 24.7±2.5% vs. control 34.1±1.5%, P=0.0012). In ex vivo perfused murine hearts subjected to acute IRI, pre-treatment with hydralazine reduced myocardial infarct size (as % left ventricle: hydralazine 29.6±6.5% vs. vehicle control 54.1±4.9%, P=0.0083), and in the murine heart subjected to in vivo IRI, the administration of hydralazine at reperfusion, decreased myocardial infarct size (as % area-at-risk: hydralazine 28.9±3.0% vs. vehicle control 58.2±3.8%, P<0.001).

CONCLUSION

We show that, in addition to its antioxidant and anti-apoptotic effects, hydralazine, confers acute cardioprotection by inhibiting IRI-induced mitochondrial fission, raising the possibility of repurposing hydralazine as a novel cardioprotective therapy for improving post-infarction outcomes.

Activity-Based Hydrazine Probes for Protein Profiling of Electrophilic Functionality in Therapeutic Targets

Most known probes for activity-based protein profiling (ABPP) use electrophilic groups that tag a single type of nucleophilic amino acid to identify cases in which its hyper-reactivity underpins function. Much important biochemistry derives from electrophilic enzyme cofactors, transient intermediates, and labile regulatory modifications, but ABPP probes for such species are underdeveloped. Here, we describe a versatile class of probes for this less charted hemisphere of the proteome. The use of an electron-rich hydrazine as the common chemical modifier enables covalent targeting of multiple, pharmacologically important classes of enzymes bearing diverse organic and inorganic cofactors. Probe attachment occurs by both polar and radicaloid mechanisms, can be blocked by molecules that occupy the active sites, and depends on the proper poise of the active site for turnover. These traits will enable the probes to be used to identify specific inhibitors of individual members of these multiple enzyme classes, making them uniquely versatile among known ABPP probes.

Effects of molidustat, a hypoxia-inducible factor prolyl hydroxylase inhibitor, on sodium dynamics in hypertensive subtotally nephrectomized rats

Hypoxia-inducible factor prolyl hydroxylase (HIF-PHD) inhibitors were developed for treatment of renal anemia. Patients applicable for HIF-PHD inhibitor treatment experience complications such as chronic kidney disease, whereby water and electrolyte homeostasis is disrupted. The effects of hypoxia-inducible factor stabilization on salt accumulation in the setting of reduced renal function remain unclear. In the present study, we investigated the effect of a HIF-PHD inhibitor, molidustat, on salt distribution and excretion in rats with subtotal nephrectomy-induced chronic kidney disease. Male Wistar rats were subjected to 5/6 nephrectomy. After confirming blood pressure elevation (>150 mmHg, at 4 weeks after surgery), rats were treated with molidustat. After 1 week of treatment, molidustat did not significantly improve blood cell volume or blood pressure. Distribution of sodium, potassium, and water in skin, carcass, and bone samples was not affected by molidustat. Furthermore, molidustat had no significant effect on urinary sodium excretion or concentration in response to acute oral salt loading (1 g/kg). In conclusion, molidustat did not affect distribution or excretion of salt in rats subjected to a model of nephron loss.

Effect of nitrate treatment on functional capacity and exercise time in patients with heart failure: a systematic review and meta-analysis

Objectives

Heart failure (HF) is a common and potentially fatal condition. In 2015, HF affected approximately 40 million people globally. Evidence showing that the use of nitrates can improve clinical outcomes in patients with HF is limited. This study aimed to assess the effect of nitrates on functional capacity and exercise time in patients with HF.

Methods

PubMed, Cochrane Library, and Embase databases were reviewed for articles on the use of nitrates and other treatments for patients with HF. The primary endpoints were the 6-minute walk test distance, exercise time, and quality of life. Secondary endpoints were all-cause mortality, arrhythmia, hospitalization, and worsening HF. The weighted mean difference, risk ratio, and 95% confidence interval were calculated.

Results

A total of 14 related studies that comprised 26,321 patients were included. No significant differences were found in the 6-minute walk test distance, exercise time, and quality of life between the nitrate and control treatment groups. There were also no differences in all-cause mortality, the incidence of arrhythmia, hospitalization, and worsening HF between these two groups.

Conclusion

Patients with HF who receive nitrate treatment do not have better quality of life or exercise capacity compared with controls.

Protective effect of hydralazine on a cellular model of Parkinson’s disease: a possible role of hypoxia-inducible factor (HIF)-1α

Parkinson’s disease (PD) is a neurodegenerative disease accompanied by a low expression level of cerebral hypoxia-inducible factor (HIF-1α). Hence, activating the hypoxia-signaling pathway may be a favorable therapeutic approach for curing PD. This study explored the efficacy of hydralazine, a well-known antihypertensive agent, for restoring the impaired HIF-1 signaling in PD, with the aid of 6-hydroxydopamine (6-OHDA)-exposed SH-SY5Y cells. The cytotoxicity of hydralazine and 6-OHDA on the SH-SY5Y cells were evaluated by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and apoptosis detection assays. The activities of malondialdehyde, nitric oxide (NO), ferric reducing antioxidant power (FRAP), and superoxide dismutase (SOD) were also measured. Expression levels of HIF-1α and its downstream genes at the protein level were assessed by Western blotting. Hydralazine showed no toxic effects on SH-SY5Y cells, at the concentration of ≤50 μmol/L. Hydralazine decreased the levels of apoptosis, malondialdehyde, and NO, and increased the activities of FRAP and SOD in cells exposed to 6-OHDA. Furthermore, hydralazine up-regulated the protein expression levels of HIF-1α, vascular endothelial growth factor, tyrosine hydroxylase, and dopamine transporter in the cells also exposed to 6-OHDA, by comparison with the cells exposed to 6-OHDA alone. In summary, hydralazine priming could attenuate the deleterious effects of 6-OHDA on SH-SY5Y cells by increasing cellular antioxidant capacity, as well as the protein levels of HIF-1α and its downstream target genes.

Reversal of increased mammary tumorigenesis by valproic acid and hydralazine in offspring of dams fed high fat diet during pregnancy

Maternal or paternal high fat (HF) diet can modify the epigenome in germ cells and fetal somatic cells leading to an increased susceptibility among female offspring of multiple generations to develop breast cancer. We determined if combined treatment with broad spectrum DNA methyltransferase (DNMT) inhibitor hydralazine and histone deacetylase (HDAC) inhibitor valproic acid (VPA) will reverse this increased risk. C57BL/6 mouse dams were fed either a corn oil-based HF or control diet during pregnancy. Starting at age 7 weeks, female offspring were administered 3 doses of 7,12-dimethylbenz[a]anthracene (DMBA) to initiate mammary cancer. After last dose, offspring started receiving VPA/hydralazine administered via drinking water: no adverse health effects were detected. VPA/hydralazine reduced mammary tumor multiplicity and lengthened tumor latency in HF offspring when compared with non-treated HF offspring. The drug combination inhibited DNMT3a protein levels and increased expression of the tumor suppressor gene Cdkn2a/p16 in mammary tumors of HF offspring. In control mice not exposed to HF diet in utero, VPA/hydralazine increased mammary tumor incidence and burden, and elevated expression of the unfolded protein response and autophagy genes, including HIF-1α, NFkB, PERK, and SQSTM1/p62. Expression of these genes was already upregulated in HF offspring prior to VPA/hydralazine treatment. These findings suggest that breast cancer prevention strategies with HDAC/DNMT inhibitors need to be individually tailored.

Hydralazine improves ischemia-induced neovasculogenesis via xanthine-oxidase inhibition in chronic renal insufficiency

Oxidative stress is related to the progression of renal diseases and modulation of oxidative stress can lead to a reduction in vascular events in patients with chronic renal insufficiency (CRI). Indoxyl sulfate (IS) and xanthine oxidase (XO) are related to impaired neovasculogenesis in CRI. Hydralazine is suggested for blood pressure control in CRI. This study aimed to investigate whether hydralazine could improve ischemia-induced neovasculogenesis in CRI animals by reducing reactive oxygen species (ROS) levels. Mice underwent subtotal nephrectomy or sham surgery. Nitrendipine, probenecid, and allopurinol were used to reduce blood pressure, uric acid (UA), and XO activity levels, respectively, for comparison. Blood pressure, XO activity and UA levels that were increased after subtotal nephrectomy were reduced by hydralazine treatment. Allopurinol decreased blood XO activity and UA levels. Only hydralazine and allopurinol increased the number of circulating endothelial progenitor cells (EPCs) and improved neovasculogenesis in CRI mice. IS activated XO mRNA and ROS and inhibited the functions of EPCs and endothelial cells, which could be reversed by hydralazine. However, no additional beneficial effects were observed when XO was inhibited with both hydralazine and siRNA. In conclusion, hydralazine, as a potential XO inhibitor, not only reduced blood pressure and UA levels but also increased the number of circulating EPCs and improved neovasculogenesis in CRI animals. Hydralazine directly inhibited IS-induced ROS and XO activation in EPCs and endothelial cells, and restored their functions in vitro. Future studies should evaluate whether hydralazine could provide additional vascular protection in patients with CRI.

Hydralazine targets cAMP-dependent protein kinase leading to sirtuin1/5 activation and lifespan extension in C. elegans

Therapeutic activation of mitochondrial function has been suggested as an effective strategy to combat aging. Hydralazine is an FDA-approved drug used in the treatment of hypertension, heart failure and cancer. Hydralazine has been recently shown to promote lifespan in C. elegans, rotifer and yeast through a mechanism which has remained elusive. Here we report cAMP-dependent protein kinase (PKA) as the direct target of hydralazine. Using in vitro and in vivo models, we demonstrate a mechanism in which binding and stabilization of a catalytic subunit of PKA by hydralazine lead to improved mitochondrial function and metabolic homeostasis via the SIRT1/SIRT5 axis, which underlies hydralazine's prolongevity and stress resistance benefits. Hydralazine also protects mitochondrial metabolism and function resulting in restoration of health and lifespan in C. elegans under high glucose and other stress conditions. Our data also provide new insights into the mechanism(s) that explain various other known beneficial effects of hydralazine.

Carnosine Supplementation Enhances Post Ischemic Hind Limb Revascularization

High (millimolar) concentrations of the histidine containing dipeptide - carnosine (β-alanine-L-histidine) are present in the skeletal muscle. The dipeptide has been shown to buffer intracellular pH, chelate transition metals, and scavenge lipid peroxidation products; however, its role in protecting against tissue injury remains unclear. In this study, we tested the hypothesis that carnosine protects against post ischemia by augmenting HIF-1α angiogenic signaling by Fe2+ chelation. We found that wild type (WT) C57BL/6 mice, subjected to hind limb ischemia (HLI) and supplemented with carnosine (1g/L) in drinking water, had improved blood flow recovery and limb function, enhanced revascularization and regeneration of myocytes compared with HLI mice placed on water alone. Carnosine supplementation enhanced the bioavailability of carnosine in the ischemic limb, which was accompanied by increased expression of proton-coupled oligopeptide transporters. Consistent with our hypothesis, carnosine supplementation augmented HIF-1α and VEGF expression in the ischemic limb and the mobilization of proangiogenic Flk-1+/Sca-1+ cells into circulation. Pretreatment of murine myoblast (C2C12) cells with octyl-D-carnosine or carnosine enhanced HIF-1α protein expression, VEGF mRNA levels and VEGF release under hypoxic conditions. Similarly pretreatment of WT C57/Bl6 mice with carnosine showed enhanced blood flow in the ischemic limb following HLI surgery. In contrast, pretreatment of hypoxic C2C12 cells with methylcarcinine, a carnosine analog, lacking Fe2+ chelating capacity, had no effect on HIF-1α levels and VEGF release. Collectively, these data suggest that carnosine promotes post ischemic revascularization via augmentation of pro-angiogenic HIF-1α/VEGF signaling, possibly by Fe2+ chelation.

Systemic silencing of PHD2 causes reversible immune regulatory dysfunction

Physiological effects of cellular hypoxia are sensed by prolyl hydroxylase (PHD) enzymes which regulate HIFs. Genetic interventions on HIF/PHD pathways reveal multiple phenotypes that extend the known biology of hypoxia. Recent studies unexpectedly implicate HIF in aspects of multiple immune and inflammatory pathways. However such studies are often limited by systemic lethal effects and/or use tissue-specific recombination systems, which are inherently irreversible, un-physiologically restricted and difficult to time. To study these processes better we developed recombinant mice which express tetracycline-regulated shRNAs broadly targeting the main components of the HIF/PHD pathway, permitting timed bi-directional intervention. We have shown that stabilization of HIF levels in adult mice through PHD2 enzyme silencing by RNA interference, or inducible recombination of floxed alleles, results in multi-lineage leukocytosis and features of autoimmunity. This phenotype was rapidly normalized on re-establishment of the hypoxia-sensing machinery when shRNA expression was discontinued. In both situations these effects were mediated principally through the Hif2a isoform. Assessment of cells bearing regulatory T cell markers from these mice revealed defective function and pro-inflammatory effects in vivo. We believe our findings have shown a new role for the PHD2/Hif2a couple in the reversible regulation of T cell and immune activity.

Local pharmacological induction of angiogenesis: Drugs for cells and cells as drugs

The past decades have seen significant advances in pro-angiogenic strategies based on delivery of molecules and cells for conditions such as coronary artery disease, critical limb ischemia and stroke. Currently, three major strategies are evolving. Firstly, various pharmacological agents (growth factors, interleukins, small molecules, DNA/RNA) are locally applied at the ischemic region. Secondly, preparations of living cells with considerable bandwidth of tissue origin, differentiation state and preconditioning are delivered locally, rarely systemically. Thirdly, based on the notion, that cellular effects can be attributed mostly to factors secreted in situ, the cellular secretome (conditioned media, exosomes) has come into the spotlight. We review these three strategies to achieve (neo)angiogenesis in ischemic tissue with focus on the angiogenic mechanisms they tackle, such as transcription cascades, specific signalling steps and cellular gases. We also include cancer-therapy relevant lymphangiogenesis, and shall seek to explain why there are often conflicting data between in vitro and in vivo. The lion's share of data encompassing all three approaches comes from experimental animal work and we shall highlight common technical obstacles in the delivery of therapeutic molecules, cells, and secretome. This plethora of preclinical data contrasts with a dearth of clinical studies. A lack of adequate delivery vehicles and standardised assessment of clinical outcomes might play a role here, as well as regulatory, IP, and manufacturing constraints of candidate compounds; in addition, completed clinical trials have yet to reveal a successful and efficacious strategy. As the biology of angiogenesis is understood well enough for clinical purposes, it will be a matter of time to achieve success for well-stratified patients, and most probably with a combination of compounds.

Current and upcoming therapies to modulate skin scarring and fibrosis

Skin is the largest organ of the human body. Being the interface between the body and the outer environment, makes it susceptible to physical injury. To maintain life, nature has endowed skin with a fast healing response that invariably ends in the formation of scar at the wounded dermal area. In many cases, skin remodelling may be impaired, leading to local hypertrophic scars or keloids. One should also consider that the scarring process is part of the wound healing response, which always starts with inflammation. Thus, scarring can also be induced in the dermis, in the absence of an actual wound, during chronic inflammatory processes. Considering the significant portion of the population that is subject to abnormal scarring, this review critically discusses the state-of-the-art and upcoming therapies in skin scarring and fibrosis.

Acute Management of Hypertension Following Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is responsible for approximately 15% of strokes annually in the United States, with nearly 1 in 3 of these patients dying without ever leaving the hospital. Because this disproportionate mortality risk has been stagnant for nearly 3 decades, a main area of research has been focused on the optimal strategies to reduce mortality and improve functional outcomes. The acute hypertensive response following ICH has been shown to facilitate ICH expansion and is a strong predictor of mortality. Rapidly reducing blood pressure was once thought to induce cerebral ischemia, though has been found to be safe in certain patient populations. Clinicians must work quickly to determine whether specific patient populations may benefit from acute lowering of systolic blood pressure (SBP) following ICH. This review provides nurses with a summary of the available literature on blood pressure control following ICH. It focuses on intravenous and oral antihypertensive medications available in the United States that may be utilized to acutely lower SBP, as well as medications outside of the antihypertensive class used during the acute setting that may reduce SBP.

Incidence, Course, and Characteristics of Hydralazine-Associated Tachycardia During Phase I Postanesthesia Recovery

PURPOSE

This study aims to characterize the development of tachycardia after intravenous hydralazine administration during Phase I recovery.

DESIGN

Retrospective observational study design.

METHODS

The medical records of 745 adult surgical patients who were administered hydralazine during Phase I recovery between January 1, 2010 and December 31, 2014 were electronically reviewed to characterize episodes of tachycardia.

FINDINGS

Seventy patients (94.0 cases per 1,000 administrations; 95% confidence interval = 74.0 to 117.2) developed tachycardia with a median increase of 23 beats per minute (bpm; interquartile range [IQR] = 15 to 37), a maximum rate of 106 bpm (IQR = 103 to 111; range = 101 to 131), and duration of 28 minutes (IQR = 5 to 86). The median onset of tachycardia was 43 minutes (IQR = 20 to 93), with 40% occurring after the first hour. Tachycardia was associated with female sex (P < .001), younger age (P < .001), and those with lesser comorbidities (P < .009).

CONCLUSIONS

A sizeable proportion of cases of tachycardia associated with hydralazine administration occurred after 1 hour, suggesting that these patients who may not tolerate a faster heart rate warrant longer duration of monitoring.

Mesenchymal Stem Cell Migration during Bone Formation and Bone Diseases Therapy

During bone modeling, remodeling, and bone fracture repair, mesenchymal stem cells (MSCs) differentiate into chondrocyte or osteoblast to comply bone formation and regeneration. As multipotent stem cells, MSCs were used to treat bone diseases during the past several decades. However, most of these implications just focused on promoting MSC differentiation. Furthermore, cell migration is also a key issue for bone formation and bone diseases treatment. Abnormal MSC migration could cause different kinds of bone diseases, including osteoporosis. Additionally, for bone disease treatment, the migration of endogenous or exogenous MSCs to bone injury sites is required. Recently, researchers have paid more and more attention to two critical points. One is how to apply MSC migration to bone disease therapy. The other is how to enhance MSC migration to improve the therapeutic efficacy of bone diseases. Some considerable outcomes showed that enhancing MSC migration might be a novel trick for reversing bone loss and other bone diseases, such as osteoporosis, fracture, and osteoarthritis (OA). Although plenty of challenges need to be conquered, application of endogenous and exogenous MSC migration and developing different strategies to improve therapeutic efficacy through enhancing MSC migration to target tissue might be the trend in the future for bone disease treatment.

Inhibition of prolyl hydroxylase domain proteins selectively enhances venous thrombus neovascularisation

BACKGROUND

Hypoxia within acute venous thrombi is thought to drive resolution through stabilisation of hypoxia inducible factor 1 alpha (HIF1α). Prolyl hydroxylase domain (PHD) isoforms are critical regulators of HIF1α stability. Non-selective inhibition of PHD isoforms with l-mimosine has been shown to increase HIF1α stabilisation and promote thrombus resolution.

OBJECTIVE

The aim of this study was to investigate the therapeutic potential of PHD inhibition in venous thrombus resolution.

METHODS

Thrombosis was induced in the inferior vena cava of mice using a combination of flow restriction and endothelial activation. Gene and protein expression of PHD isoforms in the resolving thrombus was measured by RT-PCR and immunohistochemistry. Thrombus resolution was quantified in mice treated with pan PHD inhibitors AKB-4924 and JNJ-42041935 or inducible all-cell Phd2 knockouts by micro-computed tomography, 3D high frequency ultrasound or endpoint histology.

RESULTS

Resolving venous thrombi demonstrated significant temporal gene expression profiles for PHD2 and PHD3 (P < 0.05), but not for PHD1. PHD isoform protein expression was localised to early and late inflammatory cell infiltrates. Treatment with selective pan PHD inhibitors, AKB-4924 and JNJ-42041935, enhanced thrombus neovascularisation (P < 0.05), but had no significant effect on overall thrombus resolution. Thrombus resolution or its markers, macrophage accumulation and neovascularisation, did not differ significantly in inducible all-cell homozygous Phd2 knockouts compared with littermate controls (P > 0.05).

CONCLUSIONS

This data suggests that PHD-mediated thrombus neovascularisation has a limited role in the resolution of venous thrombi. Directly targeting angiogenesis alone may not be a viable therapeutic strategy to enhance venous thrombus resolution.

Hypoxia leads to decreased autophosphorylation of the MET receptor but promotes its resistance to tyrosine kinase inhibitors

The receptor tyrosine kinase MET and its ligand, the Hepatocyte Growth Factor/Scattor Factor (HGF/SF), are essential to the migration, morphogenesis, and survival of epithelial cells. In addition, dysregulation of MET signaling has been shown to promote tumor progression and invasion in many cancers. Therefore, HGF/SF and MET are major targets for chemotherapies. Improvement of targeted therapies requires a perfect understanding of tumor microenvironment that strongly modifies half-life, bio-accessibility and thus, efficacy of treatments. In particular, hypoxia is a crucial microenvironmental phenomenon promoting invasion and resistance to treatments.

Under hypoxia, MET auto-phosphorylation resulting from ligand stimulation or from receptor overexpression is drastically decreased within minutes of oxygen deprivation but is quickly reversible upon return to normoxia. Besides a decreased phosphorylation of its proximal adaptor GAB1 under hypoxia, activation of the downstream kinases Erk and Akt is maintained, while still being dependent on MET receptor. Consistently, several cellular responses induced by HGF/SF, including motility, morphogenesis, and survival are effectively induced under hypoxia. Interestingly, using a semi-synthetic ligand, we show that HGF/SF binding to MET is strongly impaired during hypoxia but can be quickly restored upon reoxygenation. Finally, we show that two MET-targeting tyrosine kinase inhibitors (TKIs) are less efficient on MET signalling under hypoxia. Like MET loss of phosphorylation, this hypoxia-induced resistance to TKIs is reversible under normoxia. Thus, although hypoxia does not affect downstream signaling or cellular responses induced by MET, it causes immediate resistance to TKIs. These results may prove useful when designing and evaluation of MET-targeted therapies against cancer.

Regulation of hypoxia inducible factor/prolyl hydroxylase binding domain proteins 1 by PPARα and high salt diet

BACKGROUND

Hypoxia inducible factor (HIF)/prolyl hydroxylase domain (PHD)-containing proteins are involved in renal adaptive response to high salt (HS). Peroxisome proliferator activated receptor alpha (PPARα), a transcription factor involved in fatty acid oxidation is implicated in the regulation of renal function. As both HIF-1α/PHD and PPARα contribute to the adaptive changes to altered oxygen tension, this study tested the hypothesis that PHD-induced renal adaptive response to HS is PPARα-dependent.

METHODS

PPARα wild type (WT) and knock out (KO) mice were fed a low salt (LS) (0.03% NaCl) or a HS (8% NaCl) diet for 8 days and treated with hydralazine. PPARα and heme oxygenase (HO)-1 expression were evaluated in the kidney cortex and medulla. A 24-h urinary volume (UV), sodium excretion (UNaV), and nitrite excretion (UNOx V) were also determined.

RESULTS

PHD1 expression was greater in the medulla as compared to the cortex of PPARα WT mice (p<0.05) fed with a LS (0.03% NaCl) diet. The HS diet (8% NaCl) downregulated PHD1 expression in the medulla (p<0.05) but not the cortex of WT mice whereas expression was downregulated in the cortex (p<0.05) and medulla (p<0.05) of KO mice. These changes were accompanied by HS-induced diuresis (p<0.05) and natriuresis (p<0.05) that were greater in WT mice (p<0.05). Similarly, UNOx V, index of renal nitric oxide synthase (NOS) activity or availability and heme oxygenase (HO)-1 expression was greater in WT (p<0.05) but unchanged in KO mice on HS diet. Hydralazine, a PHD inhibitor, did not affect diuresis or natriuresis in LS diet-fed WT or KO mice but both were increased (p<0.05) in HS diet-fed WT mice. Hydralazine also increased UNOx V (p<0.05) with no change in diuresis, natriuresis, or HO-1 expression in KO mice on HS diet.

CONCLUSIONS

These data suggest that HS-induced PPARα-mediated downregulation of PHD1 is a novel pathway for PHD/HIF-1α transcriptional regulation for adaptive responses to promote renal function via downstream signaling involving NOS and HO.

Antihypertensive methyldopa, labetalol, hydralazine, and clonidine reversed tumour necrosis factor-α inhibited endothelial nitric oxide synthase expression in endothelial-trophoblast cellular networks

Medications used to control hypertension in pregnancy also improve trophoblast and endothelial cellular interaction in vitro. Tumour necrosis factor-α (TNF-α) inhibits trophoblast and endothelial cellular interactions and simultaneously decreases endothelial nitric oxide synthase (eNOS) expression. This study investigated whether antihypertensive medications improved these cellular interactions by modulating eNOS and inducible nitric oxide synthase (iNOS) expression. Human uterine myometrial microvascular endothelial cells (UtMVECs) were pre-incubated with (or without) low dose TNF-α (0.5 ng/mL) or TNF-α plus soluble fms-like tyrosine kinase-1 (sFlt-1) (100 ng/mL). The endothelial cells were cultured on Matrigel. After endothelial cellular networks appeared, trophoblast derived HTR-8/SVneo cells were co-cultured in the presence of clinically relevant doses of methyldopa, labetalol, hydralazine or clonidine for 24 hours. Cells were retrieved from the Matrigel to extract mRNA and eNOS and iNOS expression were examined by quantitative PCR. Methyldopa, labetalol, hydralazine and clonidine reversed the inhibitory effect of TNF-α on eNOS mRNA expression. After pre-incubating endothelial cells with TNF-α and sFlt-1, all the medications except methyldopa lost their effect on eNOS mRNA expression. In the absence of TNF-α, antihypertensive medications did not change eNOS expression. The mRNA expression of iNOS was not affected by TNF-α or any medications. This study shows that selected antihypertensive medications used in the treatment of hypertension in pregnancy increase eNOS expression in vitro when induced by the inflammatory TNF-α. The anti-angiogenic molecule sFlt-1 may antagonise the potential benefit of these medications by interfering with the NOS pathway.

The prolyl 4-hydroxylase inhibitor GSK360A decreases post-stroke brain injury and sensory, motor, and cognitive behavioral deficits

There is interest in pharmacologic preconditioning for end-organ protection by targeting the HIF system. This can be accomplished by inhibition of prolyl 4-hydroxylase (PHD). GSK360A is an orally active PHD inhibitor that has been previously shown to protect the failing heart. We hypothesized that PHD inhibition can also protect the brain from injuries and resulting behavioral deficits that can occur as a result of surgery. Thus, our goal was to investigate the effect of pre-stroke surgery brain protection using a verified GSK360A PHD inhibition paradigm on post-stroke surgery outcomes. Vehicle or an established protective dose (30 mg/kg, p.o.) of GSK360A was administered to male Sprague-Dawley rats. Initially, GSK360A pharmacokinetics and organ distribution were determined, and then PHD-HIF pharmacodynamic markers were measured (i.e., to validate the pharmacological effects of the GSK360A administration regimen). Results obtained using this validated PHD dose-regimen indicated significant improvement by GSK360A (30mg/kg); administered at 18 and 5 hours prior to transient middle cerebral artery occlusion (stroke). GSK360A exposure and plasma, kidney and brain HIF-PHD pharmacodynamics endpoints (e.g., erythropoietin; EPO and Vascular Endothelial Growth Factor; VEGF) were measured. GSK360A provided rapid exposure in plasma (7734 ng/ml), kidney (45–52% of plasma level) and brain (1–4% of plasma level), and increased kidney EPO mRNA (80-fold) and brain VEGF mRNA (2-fold). We also observed that GSK360A increased plasma EPO (300-fold) and VEGF (2-fold). Further assessments indicated that GSK360A reduced post-stroke surgery neurological deficits (47–64%), cognitive dysfunction (60–75%) and brain infarction (30%) 4 weeks later. Thus, PHD inhibition using GSK360A pretreatment produced long-term post-stroke brain protection and improved behavioral functioning. These data support PHD inhibition, specifically by GSK360A, as a potential strategy for pre-surgical use to reduce brain injury and functional decline due to surgery-related cerebral injury.

Synthesis of New Substituted 5-amino-8H-phthalazino[1,2-b]quinazolin-8-one Derivatives

A series of novel substituted 5-amino-8 H-phthalazino[1,2- b]quinazolin-8-one derivatives synthesised by condensation of different amines with 5-chloro-8 H-phthalazino[1,2- b]quinazolin-8-one, which was prepared from methyl 2-aminobenzoate by condensation with hydrazine hydrate and then cyclisation with a phthalic anhydride in N,N-dimethylacetamide at refluxing condition. The intermediate and target compounds were obtained in good yields and were easily purified by filtration or recrystallisation.

Combination of Hydralazine and Isosorbide-Dinitrate in the Treatment of Patients with Heart Failure with Reduced Ejection Fraction

The use of direct acting vasodilators (the combination of hydralazine and isosorbide dinitrate -Hy+ISDN-) in heart failure with reduced ejection fraction (HFrEF) is supported by evidence, but rarely used.However, treatment with Hy+ISDN is guideline-recommended for HFrEF patients who cannot receive either angiotensin-converting enzyme inhibitors or angiotensin receptor blockers due to intolerance or contraindication, and in self-identified African-American HFrEF patients who are symptomatic despite optimal neurohumoral therapy.The Hy+ISDN combination has arterial and venous vasodilating properties. It can decrease preload and afterload, decrease left ventricular end-diastolic diameter and the volume of mitral regurgitation, reduce left atrial and left ventricular wall tension, decrease pulmonary artery pressure and pulmonary arterial wedge pressure, increase stroke volume, and improve left ventricular ejection fraction, as well as induce left ventricular reverse remodelling. Furthermore, Hy+ISDN combination has antioxidant property, it affects endothelial dysfunction beneficially and improves NO bioavailability. Because of these benefits, this combination can improve the signs and symptoms of heart failure, exercise capacity and quality of life, and, most importantly, reduce morbidity and mortality in well-defined subgroups of HFrEF patients.Accordingly, this therapeutic option can in many cases play an essential role in the treatment of HFrEF.

Effects of Antihypertensive Agents on Intestinal Contractility in the Spontaneously Hypertensive Rat: Angiotensin Receptor System Downregulation by Losartan

Hypertension is an inflammatory condition controlled by the renin angiotensin system and is linked to kidney disease, diabetes mellitus, and recently to dysfunction of the gut. The aim of this study was to determine what effect antihypertensive drug treatments may have on intestinal function of the spontaneously hypertensive rat (SHR). In the first experiment, SHRs were treated with enalapril, hydralazine, or with no treatment as a control. In the second experiment, SHRs were treated with losartan or with no treatment as a control. All drug treatments led to significant lowering of blood pressure after 16 weeks. At termination, intact tissue sections of the ileum and colon were induced to contract ex vivo by KCl; electrical stimulation; and agonists carbachol, angiotensin II, and prostaglandin E₂ (PGE₂). There were no differences in ileal or colonic contractility due to hydralazine or enalapril compared with no-treatment SHR control. However, for the ileum, the losartan group responded significantly more to KCl and carbachol while responding less to angiotensin II, with no difference for PGE₂ compared with the no-treatment SHR control. In contrast, the colon responded similarly to KCl, electrical stimulation, and PGE₂ but responded significantly less to angiotensin II. These results demonstrate that the ileum responds differently (with KCl and carbachol as agonists) to the colon after losartan treatment, whereas there is a reduced contractile response in both the ileum and colon following losartan treatment. Although there are few well documented major contraindications for angiotensin receptor blockers, the modulation of gut contractility by losartan may have wider implications for bowel health.

Hypoxic Stress Induced by Hydralazine Leads to a Loss of Blood-Brain Barrier Integrity and an Increase in Efflux Transporter Activity

Understanding cellular and molecular mechanisms induced by hypoxic stress is crucial to reduce blood-brain barrier (BBB) disruption in some neurological diseases. Since the brain is a complex organ, it makes the interpretation of in vivo data difficult, so BBB studies are often investigated using in vitro models. However, the investigation of hypoxia in cellular pathways is complex with physical hypoxia because HIF-1α (factor induced by hypoxia) has a short half-life. We had set up an innovative and original method of induction of hypoxic stress by hydralazine that was more reproducible, which allowed us to study its impact on an in vitro BBB model. Our results showed that hydralazine, a mimetic agent of the hypoxia pathway, had the same effect as physical hypoxia, with few cytotoxicity effects on our cells. Hypoxic stress led to an increase of BBB permeability which corresponded to an opening of our BBB model. Study of tight junction proteins revealed that this hypoxic stress decreased ZO-1 but not occludin expression. In contrast, cells established a defence mechanism by increasing expression and activity of their efflux transporters (Pgp and MRP-1). This induction method of hypoxic stress by hydralazine is simple, reproducible, controllable and suitable to understand the cellular and molecular mechanisms involved by hypoxia on the BBB.

Mechanisms of Vascular Smooth Muscle Contraction and the Basis for Pharmacologic Treatment of Smooth Muscle Disorders

The smooth muscle cell directly drives the contraction of the vascular wall and hence regulates the size of the blood vessel lumen. We review here the current understanding of the molecular mechanisms by which agonists, therapeutics, and diseases regulate contractility of the vascular smooth muscle cell and we place this within the context of whole body function. We also discuss the implications for personalized medicine and highlight specific potential target molecules that may provide opportunities for the future development of new therapeutics to regulate vascular function.

Exploiting the Pleiotropic Antioxidant Effects of Established Drugs in Cardiovascular Disease

Cardiovascular disease is a leading cause of death and reduced quality of life worldwide. Arterial vessels are a primary target for endothelial dysfunction and atherosclerosis, which is accompanied or even driven by increased oxidative stress. Recent research in this field identified different sources of reactive oxygen and nitrogen species contributing to the pathogenesis of endothelial dysfunction. According to lessons from the past, improvement of endothelial function and prevention of cardiovascular disease by systemic, unspecific, oral antioxidant therapy are obviously too simplistic an approach. Source- and cell organelle-specific antioxidants as well as activators of intrinsic antioxidant defense systems might be more promising. Since basic research demonstrated the contribution of different inflammatory cells to vascular oxidative stress and clinical trials identified chronic inflammatory disorders as risk factors for cardiovascular events, atherosclerosis and cardiovascular disease are closely associated with inflammation. Therefore, modulation of the inflammatory response is a new and promising approach in the therapy of cardiovascular disease. Classical anti-inflammatory therapeutic compounds, but also established drugs with pleiotropic immunomodulatory abilities, demonstrated protective effects in various models of cardiovascular disease. However, results from ongoing clinical trials are needed to further evaluate the value of immunomodulation for the treatment of cardiovascular disease.

Downregulation of MicroRNA-126 Contributes to the Failing Right Ventricle in Pulmonary Arterial Hypertension

BACKGROUND

Right ventricular (RV) failure is the most important factor of both morbidity and mortality in pulmonary arterial hypertension (PAH). However, the underlying mechanisms resulting in the failed RV in PAH remain unknown. There is growing evidence that angiogenesis and microRNAs are involved in PAH-associated RV failure. We hypothesized that microRNA-126 (miR-126) downregulation decreases microvessel density and promotes the transition from a compensated to a decompensated RV in PAH.

METHODS AND RESULTS

We studied RV free wall tissues from humans with normal RV (n=17), those with compensated RV hypertrophy (n=8), and patients with PAH with decompensated RV failure (n=14). Compared with RV tissues from patients with compensated RV hypertrophy, patients with decompensated RV failure had decreased miR-126 expression (quantitative reverse transcription-polymerase chain reaction; P<0.01) and capillary density (CD31(+) immunofluorescence; P<0.001), whereas left ventricular tissues were not affected. miR-126 downregulation was associated with increased Sprouty-related EVH1 domain-containing protein 1 (SPRED-1), leading to decreased activation of RAF (phosphorylated RAF/RAF) and mitogen-activated protein kinase (MAPK); (phosphorylated MAPK/MAPK), thus inhibiting the vascular endothelial growth factor pathway. In vitro, Matrigel assay showed that miR-126 upregulation increased angiogenesis of primary cultured endothelial cells from patients with decompensated RV failure. Furthermore, in vivo miR-126 upregulation (mimic intravenous injection) improved cardiac vascular density and function of monocrotaline-induced PAH animals.

CONCLUSIONS

RV failure in PAH is associated with a specific molecular signature within the RV, contributing to a decrease in RV vascular density and promoting the progression to RV failure. More importantly, miR-126 upregulation in the RV improves microvessel density and RV function in experimental PAH.

Hydralazine and nitrates alone or combined for the management of chronic heart failure: A systematic review

BACKGROUND

Hydralazine (H) and nitrates (Ns), when combined, reduced morbidity and mortality in some trials of chronic heart failure (CHF). It is unclear whether either agent used alone provides similar benefits. We aimed to evaluate the effects of H and/or N in patients with CHF.

METHODS

A systematic review of randomised trials assessing the effects of H and N in CHF. For meta-analysis, only the endpoints of all-cause mortality and cardiovascular mortality were considered.

RESULTS

In seven trials evaluating H&N in 2626 patients, combination therapy reduced all-cause mortality (OR 0.72; 95% CI 0.55-0.95; p=0.02), and cardiovascular mortality (OR 0.75; 95% CI 0.57-0.99; p=0.04) compared to placebo. However, when compared to angiotensin converting enzyme inhibitors (ACEIs), combination therapy was associated with higher all-cause mortality (OR 1.35; 95% CI 1.03-1.76; p=0.03), and cardiovascular mortality (OR 1.37; 95% CI 1.04-1.81; p=0.03). For N alone, ten trials including 375 patients reported all-cause mortality and showed a trend to harm (13 deaths in those assigned to nitrates and 7 to placebo; OR 2.13; 95% CI 0.88-5.13; p=0.09). For H alone, three trials showed no difference in all-cause mortality compared to placebo (OR 0.96; 95% CI 0.37-2.47; p=0.93), and two trials suggested inferiority to ACEI (OR 2.28; 95% CI 1.03-5.04; p=0.04).

CONCLUSIONS

Compared to placebo, H&N reduces mortality in patients with CHF. Whether race or background therapy influences benefit is uncertain, but on direct comparison H&N appears inferior to ACEI. There is little evidence to support the use of either drug alone in CHF.

Antihelminthic benzimidazoles are novel HIF activators that prevent oxidative neuronal death via binding to tubulin

AIMS

Pharmacological activation of the adaptive response to hypoxia is a therapeutic strategy of growing interest for neurological conditions, including stroke, Huntington's disease, and Parkinson's disease. We screened a drug library with known safety in humans using a hippocampal neuroblast line expressing a reporter of hypoxia-inducible factor (HIF)-dependent transcription.

RESULTS

Our screen identified more than 40 compounds with the ability to induce hypoxia response element-driven luciferase activity as well or better than deferoxamine, a canonical activator of hypoxic adaptation. Among the chemical entities identified, the antihelminthic benzimidazoles represented one pharmacophore that appeared multiple times in our screen. Secondary assays confirmed that antihelminthics stabilized the transcriptional activator HIF-1α and induced expression of a known HIF target gene, p21(cip1/waf1), in post-mitotic cortical neurons. The on-target effect of these agents in stimulating hypoxic signaling was binding to free tubulin. Moreover, antihelminthic benzimidazoles also abrogated oxidative stress-induced death in vitro, and this on-target effect also involves binding to free tubulin.

INNOVATION AND CONCLUSIONS

These studies demonstrate that tubulin-binding drugs can activate a component of the hypoxic adaptive response, specifically the stabilization of HIF-1α and its downstream targets. Tubulin-binding drugs, including antihelminthic benzimidazoles, also abrogate oxidative neuronal death in primary neurons. Given their safety in humans and known ability to penetrate into the central nervous system, antihelminthic benzimidazoles may be considered viable candidates for treating diseases associated with oxidative neuronal death, including stroke.

Induction of Tet3-dependent Epigenetic Remodeling by Low-dose Hydralazine Attenuates Progression of Chronic Kidney Disease

Progression of chronic kidney disease remains a principal problem in clinical nephrology and there is a pressing need for novel therapeutics and biomarkers. Aberrant promoter CpG island methylation and subsequent transcriptional silencing of specific genes have emerged as contributors to progression of chronic kidney disease. Here, we report that transcriptional silencing of the Ras-GTP suppressor RASAL1 contributes causally to progression of kidney fibrosis and we identified that circulating methylated RASAL1 promoter DNA fragments in peripheral blood correspond with levels of intrarenal levels of RASAL1 promoter methylation and degree of fibrosis in kidney biopsies, enabling non-invasive longitudinal analysis of intrarenal CpG island methylation.

Retrospective analysis of patients with hypertensive nephrosclerosis revealed that circulating methylated RASAL1 promoter DNA fragments in peripheral blood decrease with Dihydralazine treatment in patients with hypertensive nephrosclerosis, and provided evidence that low-dose Dihydralazine delays decline of excretory kidney function, whereas Dihydralazine at standard doses had no protective effect. We demonstrate that the protective effect of Dihydralazine is due to induction of endogenous Tet3/Tdg-mediated DNA-de-methylation activity reversing aberrant promoter CpG island methylation, while HIF1α induction at standard doses counterbalances its protective activity. We conclude that RASAL1 promoter methylation is a therapeutic target and a biomarker of renal fibrosis. Our study suggests that therapeutic use of low-dose Dihydralazine in patients with chronic kidney disease and fibrosis deserves further consideration.

•

Aberrant RASAL1 promoter methylation contributes causally to progression of kidney fibrosis.

•

Degree of intrarenal RASAL1 methylation is reflected by levels of circulating methylated RASAL1 promoter fragments.

•

Low-dose Hydralazine induces endogenous Tet3-dependent de-methylation and inhibits progression of kidney fibrosis.

Targeting hypoxia signalling for the treatment of ischaemic and inflammatory diseases

Hypoxia-inducible factors (HIFs) are stabilized during adverse inflammatory processes associated with disorders such as inflammatory bowel disease, pathogen infection and acute lung injury, as well as during ischaemia-reperfusion injury. HIF stabilization and hypoxia-induced changes in gene expression have a profound impact on the inflamed tissue microenvironment and on disease outcomes. Although the mechanism that initiates HIF stabilization may vary, the final molecular steps that control HIF stabilization converge on a set of oxygen-sensing prolyl hydroxylases (PHDs) that mark HIFs for proteasomal degradation. PHDs are therefore promising therapeutic targets. In this Review, we discuss the emerging potential and associated challenges of targeting the PHD-HIF pathway for the treatment of inflammatory and ischaemic diseases.

Strategies to improve homing of mesenchymal stem cells for greater efficacy in stem cell therapy

Stem/progenitor cell-based therapeutic approach in clinical practice has been an elusive dream in medical sciences, and improvement of stem cell homing is one of major challenges in cell therapy programs. Stem/progenitor cells have a homing response to injured tissues/organs, mediated by interactions of chemokine receptors expressed on the cells and chemokines secreted by the injured tissue. For improvement of directed homing of the cells, many techniques have been developed either to engineer stem/progenitor cells with higher amount of chemokine receptors (stem cell-based strategies) or to modulate the target tissues to release higher level of the corresponding chemokines (target tissue-based strategies). This review discusses both of these strategies involved in the improvement of stem cell homing focusing on mesenchymal stem cells as most frequent studied model in cellular therapies.

BIOTRANSFORMATION OF HYDRAZINE DERVATIVES IN THE MECHANISM OF TOXICITY

Hydrazine derivatives are environmental and food pollutants but are also important because of their use in medicine for the treatment of tuberculosis and cancer. However, hydrazines also pose significant health risks to humans as they are mutagenic and carcinogenic. This review examines various metabolic pathways (enzymatic and non-enzymatic) of hydrazines for the formation of reactive species that bind to cellular macromolecules and lead to cellular dysfunction. It is believed that this biotransformation is responsible for the pharmacology and pathophysiology of hydrazine derivatives.