Carbon monoxide reverses established pulmonary hypertension

[Effect of asiaticoside on systolic blood pressure and relaxation of isolated thoracic aorta of rats]

OBJECTIVE

To investigate the effect of asiaticoside on blood pressure and relaxation of thoracic aorta in rats and explore the underlying mechanism.

METHODS

SD rats treated with 50 and 100 mg/kg asiaticoside by daily gavage for 2 weeks were monitored for systolic blood pressure changes, and histological changes of the thoracic aorta were evaluated using HE staining. In isolated rat endothelium-intact and endothelium-denuded thoracic aorta rings, the effects of asiaticoside on relaxation of the aortic rings were tested at baseline and following norepinephrine (NE)- and KCl-induced constriction. The vascular relaxation effect of asiaticoside was further observed in NE-stimulated endothelium-intact rat aortic rings pretreated with L-nitroarginine methyl ester, indomethacin, zinc protoporphyrin Ⅸ, tetraethyl ammonium chloride, glibenclamide, barium chloride, Iberiotoxin, 4-aminopyridine, or TASK-1-IN-1. The aortic rings were treated with KCl and NE followed by increasing concentrations of CaCl2 to investigate the effect of asiaticoside on vasoconstriction induced by external calcium influx and internal calcium release.

RESULTS

Asiaticoside at 50 and 100 mg/kg significantly lowered systolic blood pressure in rats without affecting the thoracic aorta histomorphology. While not obviously affecting resting aortic rings with intact endothelium, asiaticoside at 100 mg/kg induced significant relaxation of the rings constricted by KCl and NE, but its effects differed between endothelium-intact and endothelium-denuded rings. In endothelium-intact aortic rings pretreated with indomethacin, ZnPP Ⅸ, barium chloride, glyburide, TASK-1-IN-1 and 4-aminopyridine, asiaticoside did not produce significant effect on NE-induced vasoconstriction, and tetraethylammonium, Iberiotoxin and L-nitroarginine methyl ester all inhibited the relaxation effect of asiaticoside. In KCland NE-treated rings, asiaticoside obviously inhibited CaCl2-induced vascular contraction.

CONCLUSION

Asiaticoside induces thoracic aorta relaxation by mediating high-conductance calcium-activated potassium channel opening, promoting nitric oxide release from endothelial cells and regulating Ca2+ influx and outflow, thereby reducing systolic blood pressure in rats.

Interleukin-6 and pulmonary hypertension: from physiopathology to therapy

Pulmonary hypertension (PH) is a progressive, pulmonary vascular disease with high morbidity and mortality. Unfortunately, the pathogenesis of PH is complex and remains unclear. Existing studies have suggested that inflammatory factors are key factors in PH. Interleukin-6 (IL-6) is a multifunctional cytokine that plays a crucial role in the regulation of the immune system. Current studies reveal that IL-6 is elevated in the serum of patients with PH and it is negatively correlated with lung function in those patients. Since IL-6 is one of the most important mediators in the pathogenesis of inflammation in PH, signaling mechanisms targeting IL-6 may become therapeutic targets for this disease. In this review, we detailed the potential role of IL-6 in accelerating PH process and the specific mechanisms and signaling pathways. We also summarized the current drugs targeting these inflammatory pathways to treat PH. We hope that this study will provide a more theoretical basis for targeted treatment in patients with PH in the future.

Influence of cigarettes on myocardial injury in healthy population after exposure to high altitude over 5000 m

BACKGROUND

Myocardial injury (MI) is a severe complication once subjected to hypoxic condition at high altitude. Little evidence exists about the association of cigarettes and MI at high altitude, especially over 5000 m. In the present study, we intend to explore the influence of cigarettes on MI in healthy population after travelling to this extreme environment.

METHODS

Physical examination was performed in population at Pamirs plateau during November and December 2020. All participants were divided into cigarette group or control group. MI was diagnosed based on lactate dehydrogenase (LDH), creatine kinase (CK), creatine kinase isoenzymes (CK-MB) and aspartate amino transferase (AST).

RESULTS

311 people were included, 58 of whom developed MI, accounting for 18.6 %. Participants in cigarette group were all male, and younger than those in control group. There was longer exposure time in cigarette group. Compared with control group, red blood cell counting, hemoglobin (HGB) and hematocrit in cigarette group were significantly increased, while heart rate was significantly decreased. Cigarettes were found to significantly upregulate the level of CK-MB and LDH. After adjustment with age, sex, body mass index, altitude and exposure time as covariables, 108 male participants remained in each group, showing that none of clinical indexes had significant difference between the two groups. Logistic regression analysis revealed that female sex and oxygen saturation (SO₂) were independent risk factors for MI in non-smokers while HGB was independent risk factor in smokers. By using Spearman correlation analysis, four myocardial enzymes were not relevant with the level of SO₂ in non-smokers. For smokers, HGB was found to be in significant positive correlation with LDH.

CONCLUSION

Our study suggested that exposure to high altitude over 5000 m could abrogate the impact of cigarettes on MI in healthy population. The independent factors affecting the occurrence of MI were distinctive depending on current smoking status.

Effects of combination of obesity, diabetes, and hypoxia on inflammatory regulating genes and cytokines in rat pancreatic tissues and serum

Background

Obesity and diabetes are becoming increasingly prevalent around the world. Inflammation, oxidative stress, insulin resistance, and glucose intolerance are linked to both obesity and type 2 diabetes, and these disorders are becoming major public health issues globally.

Methods

This study evaluated the effects of obesity, diabetes, and hypoxia on the levels of pro- and anti-inflammatory cytokines in rats. We divided 120 Wistar rats in two groups, male and female, each including six subgroups: control (CTRL), obese (high-fat diet (HFD)), diabetic (streptozotocin (STZ)-treated), hypoxic (HYX), obese + diabetic (HFD/STZ), and obese + diabetic + hypoxic (HFD/STZ/HYX). We examined the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL10, and leptin in pancreatic tissues and serum.

Results

No significant difference was observed in serum levels of cholesterol, triglycerides, and low-density lipoprotein (LDL) between HYX and CTRL in either sex. However, they were significantly increased, whereas high-density lipoprotein (HDL) was significantly decreased in HFD, STZ, HFD/STZ, and HFD/STZ/HPX compared with CTRL in both sexes. The expression of Tnf-α, Il6, and Lep was significantly upregulated in all subgroups compared with CTRL in both sexes. STZ and HYX showed no significant differences in the expression of these genes between sexes, whereas Tnf-α and Il6 were upregulated in male HFD, HFD/STZ, and HFD/STZ/HYX compared with females. Protein levels showed similar patterns. Combination subgroups, either in the absence or presence of hypoxia, frequently exhibited severe necrosis of endocrine components in pancreatic lobules. The combination of obesity, diabetes, and hypoxia was associated with inflammation, which was verified at the histopathological level.

Controlled therapeutic delivery of CO from carbon monoxide-releasing molecules (CORMs)

Carbon monoxide (CO) has been regarded as a "silent killer" for its toxicity toward biological systems. However, a low concentration of endogenously produced CO has shown a number of therapeutic benefits such as anti-inflammatory, anti-proliferative, anti-apoptosis, and cytoprotective activities. Carbon monoxide-releasing molecules (CORMs) have been developed as alternatives to direct CO inhalation, which requires a specialized setting for strict dose control. CORMs are efficient CO donors, with central transition metals (such as ruthenium, iron, cobalt, and manganese) surrounded by CO as a ligand. CORMs can stably store and subsequently release their CO payload in the presence of certain triggers including solvent, light, temperature, and ligand substitution. However, CORMs require appropriate delivery strategies to improve short CO release half-life and target specificity. Herein, we highlighted the therapeutic potential of inhalation and CORMs-delivered CO. The applications of conjugate and nanocarrier systems for controlling CO release and improving therapeutic efficacy of CORMs are also described in detail. The review concludes with some of the hurdles that limit clinical translation of CORMs. Keeping in mind the tremendous potential and growing interest in CORMs, this review would be helpful for designing controlled CO release systems for clinical applications.

NO, CO and H2S: A Trinacrium of Bioactive Gases in the Brain

Oxygen and carbon dioxide are time honored gases that have direct bearing on almost all life forms, but over the past thirty years, and in large part due to the Nobel Prize Award in Medicine for the elucidation of nitric oxide (NO) as a bioactive gas, the research and medical communities now recognize other gases as critical for survival. In addition to NO, hydrogen sulfide (H₂S) and carbon monoxide (CO) have emerged as a triumvirate or Trinacrium of gases with analogous importance and that serve important homeostatic functions. Perhaps, one of the most intriguing aspects of these gases is the functional interaction between them, which is intimately linked by the enzyme systems that produce them. Despite the need to better understand NO, H₂S and CO biology, the notion that these are environmental pollutants remains ever present. For this reason, incorporating the concept of hormesis becomes imperative and must be included in discussions when considering developing new therapeutics that involve these gases. While there is now an enormous literature base for each of these gasotransmitters, we provide here an overview of their respective physiologic roles in the brain.

An evolutionary machine learning for pulmonary hypertension animal model from arterial blood gas analysis

Pulmonary hypertension (PH) is a rare and fatal condition that leads to right heart failure and death. The pathophysiology of PH and potential therapeutic approaches are yet unknown. PH animal models' development and proper evaluation are critical to PH research. This work presents an effective analysis technology for PH from arterial blood gas analysis utilizing an evolutionary kernel extreme learning machine with multiple strategies integrated slime mould algorithm (MSSMA). In MSSMA, two efficient bee-foraging learning operators are added to the original slime mould algorithm, ensuring a suitable trade-off between intensity and diversity. The proposed MSSMA is evaluated on thirty IEEE benchmarks and the statistical results show that the search performance of the MSSMA is significantly improved. The MSSMA is utilised to develop a kernel extreme learning machine (MSSMA-KELM) on PH from arterial blood gas analysis. Comprehensively, the proposed MSSMA-KELM can be used as an effective analysis technology for PH from arterial Blood gas analysis with an accuracy of 93.31%, Matthews coefficient of 90.13%, Sensitivity of 91.12%, and Specificity of 90.73%. MSSMA-KELM can be treated as an effective approach for evaluating mouse PH models.

Carbon Monoxide and Nitric Oxide as Examples of the Youngest Class of Transmitters

The year 2021 is the 100th anniversary of the confirmation of the neurotransmission phenomenon by Otto Loewi. Over the course of the hundred years, about 100 neurotransmitters belonging to many chemical groups have been discovered. In order to celebrate the 100th anniversary of the confirmation of neurotransmitters, we present an overview of the first two endogenous gaseous transmitters i.e., nitric oxide, and carbon monoxide, which are often termed as gasotransmitters.

Gaseous Mediators as a Key Molecular Targets for the Development of Gastrointestinal-Safe Anti-Inflammatory Pharmacology

Non-steroidal anti-inflammatory drugs (NSAIDs) represent one of the most widely used classes of drugs and play a pivotal role in the therapy of numerous inflammatory diseases. However, the adverse effects of these drugs, especially when applied chronically, frequently affect gastrointestinal (GI) tract, resulting in ulceration and bleeding, which constitutes a significant limitation in clinical practice. On the other hand, it has been recently discovered that gaseous mediators nitric oxide (NO), hydrogen sulfide (H2S) and carbon monoxide (CO) contribute to many physiological processes in the GI tract, including the maintenance of GI mucosal barrier integrity. Therefore, based on the possible therapeutic properties of NO, H2S and CO, a novel NSAIDs with ability to release one or more of those gaseous messengers have been synthesized. Until now, both preclinical and clinical studies have shown promising effects with respect to the anti-inflammatory potency as well as GI-safety of these novel NSAIDs. This review provides an overview of the gaseous mediators-based NSAIDs along with their mechanisms of action, with special emphasis on possible implications for GI mucosal defense mechanisms.

Carbon Monoxide Releasing Molecule-3 Enhances Osteogenic Differentiation of Human Periodontal Ligament Stem Cells by Carbon Monoxide Release

Purpose

Limited intrinsic regeneration capacity following bone destruction remains a significant medical problem. Multiple regulatory effects of carbon monoxide releasing molecule-3 (CORM-3) have been reported. The aim of this study was to investigate the effect of CORM-3 on the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) during osteogenesis.

Patients and Methods

hPDLSCs obtained from healthy periodontal ligament tissues were cultured and identified with specific surface antigens by flow cytometry. Effect of CORM-3 on the proliferation of hPDLSCs was determined by CCK-8 assay. Alizarin red staining and alkaline phosphatase (ALP) activity were used to assess the osteogenic differentiation of hPDLSCs. Real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis were used to detect the expression of the indicated genes. Critical-sized skull defect was made in Balb/c-nude mice, microcomputed tomography (Micro-CT) and Masson trichrome staining were used to assess the new bone regeneration in mice.

Results

CORM-3 (400 μmol/l) significantly promoted the proliferation of hPDLSCs. CORM-3 pretreatment not only notably enhanced the mRNA and protein expression of osteo-specific marker OPN, Runx2 and ALP, but also increased mineral deposition and ALP activity by the release of CO on day 3, 7 and 14 (P<0.05). Degassed CORM-3 did not show the same effect as CORM-3. In animal model, application of CORM-3 with hPDLSCs transplantation highly increased new bone formation in skull defect region.

Conclusion

CORM-3 promoted osteogenic differentiation of hPDLSCs, and increased hPDLSCs-induced new bone formation in mice with critical-sized skull defect, which suggests an efficient and promising strategy in the treatment of disease with bone defect.

Regulation of Endothelial and Vascular Functions by Carbon Monoxide via Crosstalk With Nitric Oxide

Carbon monoxide (CO), generated by heme oxygenase (HO), has been considered a signaling molecule in both the cardiovascular and central nervous systems. The biological function of the HO/CO axis is mostly related to other gaseous molecules, including nitric oxide (NO), which is synthesized by nitric oxide synthase (NOS). Healthy blood vessels are essential for the maintenance of tissue homeostasis and whole-body metabolism; however, decreased or impaired vascular function is a high-risk factor of cardiovascular and neuronal diseases. Accumulating evidence supports that the interplay between CO and NO plays a crucial role in vascular homeostasis and regeneration by improving endothelial function. Moreover, endothelial cells communicate with neighboring cells, such as, smooth muscle cells, immune cells, pericytes, and astrocytes in the periphery and neuronal vascular systems. Endogenous CO could mediate the cell-cell communication and improve the physiological functions of the cardiovascular and neurovascular systems via crosstalk with NO. Thus, a forward, positive feedback circuit between HO/CO and NOS/NO pathways can maintain cardiovascular and neurovascular homeostasis and prevent various human diseases. We discussed the crucial role of CO-NO crosstalk in the cardiovascular and neurovascular systems.

Expression of heme oxygenase-1 in type II pneumocytes protects against heatstroke-induced lung damage

Heatstroke (HS) is an acute clinical disease characterized by abnormal hyperthermia and multi-organ dysfunction. Heme oxygenase (HO)-1, also called heat shock protein (HSP)32, is induced by hyperthermia and also plays protective roles in many lung disease models. Based on this phenomenon, we investigated the protective role of endogenous HO-1 in heat-induced lung damage in rats. Male Sprague-Dawley (SD) rats were separated into three groups: (a) normothermic sham, (b) HS, and (c) SnPP (inhibitor of HO-1) pretreatment rats. In the HS group, rats were killed at various time points (1, 3, 6, and 12 h after heat exposure) in order to analyze messenger ribonucleic acid (mRNA) and protein levels. Lung sections were examined for tissue damage and localization of HO-1 using immunofluorescence double labeling. We found that HS induced lung pathology (congested and thickened lung septa). The level of HO-1 mRNA was increased at 1 h, and the protein level peaked at 6 h after heat exposure. Pretreatment with SnPP (tin-protoporphyrin IX, 30 mg/kg, intraperitoneal injection for 1 h before heat exposure) aggravated the lung damage. Furthermore, we demonstrated HO-1 expression in lung type II pneumocytes. Our results suggest that endogenous HO-1 is protective against HS-induced lung damage. Induction of HO-1 may be a potential therapeutic strategy for treating heat-related diseases.

Targeting Heme Oxygenase-1 in the Arterial Response to Injury and Disease

Heme oxygenase-1 (HO-1) catalyzes the degradation of heme into carbon monoxide (CO), iron, and biliverdin, which is rapidly metabolized to bilirubin. The activation of vascular smooth muscle cells (SMCs) plays a critical role in mediating the aberrant arterial response to injury and a number of vascular diseases. Pharmacological induction or gene transfer of HO-1 improves arterial remodeling in animal models of post-angioplasty restenosis, vascular access failure, atherosclerosis, transplant arteriosclerosis, vein grafting, and pulmonary arterial hypertension, whereas genetic loss of HO-1 exacerbates the remodeling response. The vasoprotection evoked by HO-1 is largely ascribed to the generation of CO and/or the bile pigments, biliverdin and bilirubin, which exert potent antioxidant and anti-inflammatory effects. In addition, these molecules inhibit vascular SMC proliferation, migration, apoptosis, and phenotypic switching. Several therapeutic strategies are currently being pursued that may allow for the targeting of HO-1 in arterial remodeling in various pathologies, including the use of gene delivery approaches, the development of novel inducers of the enzyme, and the administration of unique formulations of CO and bilirubin.

Carbon monoxide: An emerging therapy for acute kidney injury

Treating acute kidney injury (AKI) represents an important unmet medical need both in terms of the seriousness of this medical problem and the number of patients. There is also a large untapped market opportunity in treating AKI. Over the years, there has been much effort in search of therapeutics with minimal success. However, over the same time period, new understanding of the underlying pathobiology and molecular mechanisms of kidney injury have undoubtedly helped the search for new therapeutics. Along this line, carbon monoxide (CO) has emerged as a promising therapeutic agent because of its demonstrated cytoprotective, and immunomodulatory effects. CO has also been shown to sensitize cancer, but not normal cells, to chemotherapy. This is particularly important in treating cisplatin-induced AKI, a common clinical problem that develops in patients receiving cisplatin therapies for a number of different solid organ malignancies. This review will examine and make the case that CO be developed into a therapeutic agent against AKI.

Perinatal cardiopulmonary adaptation to the thin air of the Alto Andino by a native Altiplano dweller, the llama

Most mammals have a poor tolerance to hypoxia, and prolonged O₂ restriction can lead to organ injury, particularly during fetal and early postnatal life. Nevertheless, the llama (Lama Glama) has evolved efficient mechanisms to adapt to acute and chronic perinatal hypoxia. One striking adaptation is the marked peripheral vasoconstriction measured in the llama fetus in response to acute hypoxia, which allows efficient redistribution of cardiac output toward the fetal heart and adrenal glands. This strong peripheral vasoconstrictor tone is triggered by a carotid body reflex and critically depends on α-adrenergic signaling. A second adaptation is the ability of the llama fetus to protect its brain against hypoxic damage. During hypoxia, in the llama fetus there is no significant increase in brain blood flow. Instead, there is a fall in brain O₂ consumption and temperature, together with a decrease of Na⁺-K⁺-ATPase activity and Na⁺ channels expression, protecting against seizures and neuronal death. Finally, the newborn llama does not develop pulmonary hypertension in response to chronic hypoxia. In addition to maintaining basal pulmonary arterial pressure at normal levels the pulmonary arterial pressor response to acute hypoxia is lower in highland than in lowland llamas. The protection against hypoxic pulmonary arterial hypertension and pulmonary contractile hyperreactivity is partly due to increased hemoxygenase-carbon monoxide signaling and decreased Ca²⁺ sensitization in the newborn llama pulmonary vasculature. These three striking physiological adaptations of the llama allow this species to live and thrive under the chronic influence of the hypobaric hypoxia of life at high altitude.

Effect of p53 activation on experimental right ventricular hypertrophy

The leading cause of death in Pulmonary Arterial Hypertension (PAH) is right ventricular (RV) failure. The tumor suppressor p53 has been associated with left ventricular hypertrophy (LVH) and remodeling but its role in RV hypertrophy (RVH) is unclear. The purpose of this study was to determine whether pharmacological activation of p53 by Quinacrine affects RV remodeling and function in the pulmonary artery banding (PAB) model of compensated RVH in mice. The effects of p53 activation on cellular functions were studied in isolated cardiomyocytes, cardiac fibroblasts and endothelial cells (ECs). The expression of p53 was examined both on human RV tissues from patients with compensated and decompensated RVH and in mouse RV tissues early and late after the PAB. As compared to control human RVs, there was no change in p53 expression in compensated RVH, while a marked upregulation was found in decompensated RVH. Similarly, in comparison to SHAM-operated mice, unaltered RV p53 expression 7 days after PAB, was markedly induced 21 days after the PAB. Quinacrine induced p53 accumulation did not further deteriorate RV function at day 7 after PAB. Quinacrine administration did not increase EC death, neither diminished EC number and capillary density in RV tissues. No major impact on the expression of markers of sarcomere organization, fatty acid and mitochondrial metabolism and respiration was noted in Quinacrine-treated PAB mice. p53 accumulation modulated the expression of Heme Oxygenase 1 (HO-1) and Glucose Transporter (Glut1) in mouse RVs and in adult cardiomyocytes. We conclude that early p53 activation in PAB-induced RVH does not cause substantial detrimental effects on right ventricular remodeling and function.

Near-Infrared Light Responsive Nanoreactor for Simultaneous Tumor Photothermal Therapy and Carbon Monoxide-Mediated Anti-Inflammation

Photothermal therapy (PTT) is an effective treatment modality with high selectivity for tumor suppression. However, the inflammatory responses caused by PTT may lead to adverse reactions including tumor recurrence and therapeutic resistance, which are regarded as major problems for PTT. Here, a near-infrared (NIR) light-responsive nanoreactor (P@DW/BC) is fabricated to simultaneously realize tumor PTT and carbon monoxide (CO)-mediated anti-inflammatory therapy. Defective tungsten oxide (WO₃) nanosheets (DW NSs) are decorated with bicarbonate (BC) via ferric ion-mediated coordination and then modified with polyethylene glycol (PEG) on the surface to fabricate PEG@DW/BC or P@DW/BC nanosheets. Upon 808 nm NIR laser irradiation, the DW content in P@DW/BC can serve as not only a photothermal agent to realize photothermal conversion but also a photocatalyst to convert carbon dioxide (CO₂) to CO. In particular, the generated heat can also trigger the decomposition of BC to produce CO₂ near the NSs, thus enhancing the photocatalytic CO generation. Benefiting from the efficient hyperthermia and CO generation under single NIR laser irradiation, P@DW/BC can realize effective thermal ablation of tumor and simultaneous inhibition of PTT-induced inflammation.

Neonatal comorbidities and gasotransmitters

Hydrogen sulfide, nitric oxide, and carbon monoxide are endogenously produced gases that regulate various signaling pathways. The role of these transmitters is complex as constitutive production of these molecules may have anti-inflammatory, anti-microbial, and/or vasodilatory effects whereas induced production or formation of secondary metabolites may lead to cellular death. Given this fine line between friend and foe, therapeutic attenuation of these molecules' production has involved both inhibition of endogenous formation and therapeutic supplementation. All three gases have been implicated as regulators of critical aspects of neonatal physiology, and in turn, comorbidities including necrotizing enterocolitis, hypoxic ischemic encephalopathy, and pulmonary hypertension. In this review, we present current perspectives on these associations, highlight areas where insights remain sparse, and identify areas for potential for future investigations.

Bioluminescence imaging of carbon monoxide in living cells based on a selective deiodination reaction

Modification of a heavy iodine atom for d-Luciferin was explored as a “turn-on” transduction scheme for CO detection. This new probe could image exogenous and endogenous CO in the luciferase-transfected cancer cells.

Carbon monoxide: An emerging therapy for acute kidney injury

Treating acute kidney injury (AKI) represents an important unmet medical need both in terms of the seriousness of this medical problem and the number of patients. There is also a large untapped market opportunity in treating AKI. Over the years, there has been much effort in search of therapeutics with minimal success. However, over the same time period, new understanding of the underlying pathobiology and molecular mechanisms of kidney injury have undoubtedly helped the search for new therapeutics. Along this line, carbon monoxide (CO) has emerged as a promising therapeutic agent because of its demonstrated cytoprotective, and immunomodulatory effects. CO has also been shown to sensitize cancer, but not normal cells, to chemotherapy. This is particularly important in treating cisplatin-induced AKI, a common clinical problem that develops in patients receiving cisplatin therapies for a number of different solid organ malignancies. This review will examine and make the case that CO be developed into a therapeutic agent against AKI.

Emerging Delivery Strategies of Carbon Monoxide for Therapeutic Applications: from CO Gas to CO Releasing Nanomaterials

Carbon monoxide (CO) therapy has emerged as a hot topic under exploration in the field of gas therapy as it shows the promise of treating various diseases. Due to the gaseous property and the high affinity for human hemoglobin, the main challenges of administrating medicinal CO are the lack of target selectivity as well as the toxic profile at relatively high concentrations. Although abundant CO releasing molecules (CORMs) with the capacity to deliver CO in biological systems have been developed, several disadvantages related to CORMs, including random diffusion, poor solubility, potential toxicity, and lack of on-demand CO release in deep tissue, still confine their practical use. Recently, the advent of versatile nanomedicine has provided a promising chance for improving the properties of naked CORMs and simultaneously realizing the therapeutic applications of CO. This review presents a brief summarization of the emerging delivery strategies of CO based on nanomaterials for therapeutic application. First, an introduction covering the therapeutic roles of CO and several frequently used CORMs is provided. Then, recent advancements in the synthesis and application of versatile CO releasing nanomaterials are elaborated. Finally, the current challenges and future directions of these important delivery strategies are proposed.

HO-1 and CD39: It Takes Two to Protect the Realm

Cellular protective mechanisms exist to ensure survival of the cells and are a fundamental feature of all cells that is necessary for adapting to changes in the environment. Indeed, evolution has ensured that each cell is equipped with multiple overlapping families of genes that safeguard against pathogens, injury, stress, and dysfunctional metabolic processes. Two of the better-known enzymatic systems, conserved through all species, include the heme oxygenases (HO-1/HO-2), and the ectonucleotidases (CD39/73). Each of these systems generates critical bioactive products that regulate the cellular response to a stressor. Absence of these molecules results in the cell being extremely predisposed to collapse and, in most cases, results in the death of the cell. Recent reports have begun to link these two metabolic pathways, and what were once exclusively stand-alone are now being found to be intimately interrelated and do so through their innate ability to generate bioactive products including adenosine, carbon monoxide, and bilirubin. These simple small molecules elicit profound cellular physiologic responses that impact a number of innate immune responses, and participate in the regulation of inflammation and tissue repair. Collectively these enzymes are linked not only because of the mitochondria being the source of their substrates, but perhaps more importantly, because of the impact of their products on specific cellular responses. This review will provide a synopsis of the current state of the field regarding how these systems are linked and how they are now being leveraged as therapeutic modalities in the clinic.

Carbon monoxide-releasing molecule-3 (CORM-3) offers protection in an in vitro model of compartment syndrome

OBJECTIVE

Limb compartment syndrome (CS), a complication of trauma, results in muscle necrosis and cell death; ischemia and inflammation contribute to microvascular dysfunction and parenchymal injury. Carbon monoxide-releasing molecule-3 (CORM-3) has been shown to protect microvascular perfusion and reduce inflammation in animal models of CS. The purpose of the study was to test the effect of CORM-3 in human in vitro CS model, allowing exploration of the mechanism(s) of CO protection and potential development of pharmacologic treatment.

METHODS

Confluent human vascular endothelial cells (HUVECs) were stimulated for 6 h with serum isolated from patients with CS. Intracellular oxidative stress (production of reactive oxygen species (ROS)) apoptosis, transendothelial resistance (TEER), polymorphonuclear leukocyte (PMN) activation and transmigration across the monolayer in response to the CS stimulus were assessed. All experiments were performed in the presence of CORM-3 (100 μM) or its inactive form, iCORM-3.

RESULTS

CS serum induced a significant increase in ROS, apoptosis and endothelial monolayer breakdown; it also increased PMN superoxide production, leukocyte rolling and adhesion/transmigration. CORM-3 completely prevented CS-induced ROS production, apoptosis, PMN adhesion, rolling and transmigration, while improving monolayer integrity.

CONCLUSION

CORM-3 offers potent anti-oxidant and anti-inflammatory effects, and may have a potential application to patients at risk of developing CS.

A phase I trial of low-dose inhaled carbon monoxide in sepsis-induced ARDS

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a prevalent disease with significant mortality for which no effective pharmacologic therapy exists. Low-dose inhaled carbon monoxide (iCO) confers cytoprotection in preclinical models of sepsis and ARDS.

METHODS

We conducted a phase I dose escalation trial to assess feasibility and safety of low-dose iCO administration in patients with sepsis-induced ARDS. Twelve participants were randomized to iCO or placebo air 2:1 in two cohorts. Four subjects each were administered iCO (100 ppm in cohort 1 or 200 ppm in cohort 2) or placebo for 90 minutes for up to 5 consecutive days. Primary outcomes included the incidence of carboxyhemoglobin (COHb) level ≥10%, prespecified administration-associated adverse events (AEs), and severe adverse events (SAEs). Secondary endpoints included the accuracy of the Coburn-Forster-Kane (CFK) equation to predict COHb levels, biomarker levels, and clinical outcomes.

RESULTS

No participants exceeded a COHb level of 10%, and there were no administration-associated AEs or study-related SAEs. CO-treated participants had a significant increase in COHb (3.48% ± 0.7% [cohort 1]; 4.9% ± 0.28% [cohort 2]) compared with placebo-treated subjects (1.97% ± 0.39%). The CFK equation was highly accurate at predicting COHb levels, particularly in cohort 2 (R2 = 0.9205; P < 0.0001). Circulating mitochondrial DNA levels were reduced in iCO-treated participants compared with placebo-treated subjects.

CONCLUSION

Precise administration of low-dose iCO is feasible, well-tolerated, and appears to be safe in patients with sepsis-induced ARDS. Excellent agreement between predicted and observed COHb should ensure that COHb levels remain in the target range during future efficacy trials.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02425579.

FUNDING

NIH grants P01HL108801, KL2TR002385, K08HL130557, and K08GM102695.

Beneficial Effect of Ocimum sanctum (Linn) against Monocrotaline-Induced Pulmonary Hypertension in Rats

Background: The study was designed to explore any beneficial effect of Ocimum sanctum (Linn) (OS) in experimental pulmonary hypertension (PH) in rats. OS is commonly known as “holy basil” and “Tulsi” and is used in the Indian System of Medicine as antidiabetic, antioxidant, hepatoprotective, adaptogenic, and cardioprotective. Methods: Monocrotaline (MCT) administration caused development of PH in rats after 28 days and rats were observed for 42 days. Treatments (sildenafil; 175 µg/kg, OS; 200 mg/kg) were started from day 29 after the development of PH and continued for 14 days. Parameters to assess the disease development and effectiveness of interventions were echocardiography, right and left ventricular systolic pressures, and right ventricular end diastolic pressure, percentage medial wall thickness (%MWT) of pulmonary artery, oxidative stress markers in lung tissue, NADPH oxidase (Nox-1) protein expression in lung, and mRNA expression of Bcl2 and Bax in right ventricular tissue. Results: OS (200 mg/kg) treatment ameliorated increased lung weight to body weight ratio, right ventricular hypertrophy, increased RVSP, and RVoTD/AoD ratio. Moreover, OS treatment decreases Nox-1 expression and increases expression of Bcl2/Bax ratio caused by MCT. Conclusion: The present study demonstrates that OS has therapeutic ability against MCT-induced PH in rat which are attributed to its antioxidant effect. The effect of OS was comparable with sildenafil.

Use of gasotransmitters for the controlled release of polymer-based nitric oxide carriers in medical applications

Nitric Oxide (NO) is a small molecule gasotransmitter synthesized by nitric oxide synthase in almost all types of mammalian cells. NO is synthesized by NO synthase by conversion of l-arginine to l-citrulline in the human body. NO then stimulates soluble guanylate cyclase, from which various physiological functions are mediated in a concentration-dependent manner. High concentrations of NO induce apoptosis or antibacterial responses whereas low NO circulation leads to angiogenesis. The bidirectional effect of NO has attracted considerable attention, and efforts to deliver NO in a controlled manner, especially through polymeric carriers, has been the topic of much research. This naturally produced signaling molecule has stood out as a potentially more potent therapeutic agent compared to exogenously synthesized drugs. In this review, we will focus on past efforts of using the controlled release of NO via polymer-based materials to derive specific therapeutic results. We have also added studies and our future suggestions on co-delivery methods with other gasotransmitters as a step towards developing multifunctional carriers.

Carbon monoxide protects the kidney through the central circadian clock and CD39

Ischemia reperfusion injury (IRI) is the predominant tissue insult associated with organ transplantation. Treatment with carbon monoxide (CO) modulates the innate immune response associated with IRI and accelerates tissue recovery. The mechanism has been primarily descriptive and ascribed to the ability of CO to influence inflammation, cell death, and repair. In a model of bilateral kidney IRI in mice, we elucidate an intricate relationship between CO and purinergic signaling involving increased CD39 ectonucleotidase expression, decreased expression of Adora1, with concomitant increased expression of Adora2a/2b. This response is linked to a >20-fold increase in expression of the circadian rhythm protein Period 2 (Per2) and a fivefold increase in serum erythropoietin (EPO), both of which contribute to abrogation of kidney IRI. CO is ineffective against IRI in Cd39^-/- and Per2^-/- mice or in the presence of a neutralizing antibody to EPO. Collectively, these data elucidate a cellular signaling mechanism whereby CO modulates purinergic responses and circadian rhythm to protect against injury. Moreover, these effects involve CD39- and adenosinergic-dependent stabilization of Per2. As CO also increases serum EPO levels in human volunteers, these findings continue to support therapeutic use of CO to treat IRI in association with organ transplantation, stroke, and myocardial infarction.

Gaseous Signaling Molecules in Cardiovascular Function: From Mechanisms to Clinical Translation

Carbon monoxide (CO), hydrogen sulfide (H₂S), and nitric oxide (NO) constitute endogenous gaseous molecules produced by specific enzymes. These gases are chemically simple, but exert multiple effects and act through shared molecular targets to control both physiology and pathophysiology in the cardiovascular system (CVS). The gases act via direct and/or indirect interactions with each other in proteins such as heme-containing enzymes, the mitochondrial respiratory complex, and ion channels, among others. Studies of the major impacts of CO, H₂S, and NO on the CVS have revealed their involvement in controlling blood pressure and in reducing cardiac reperfusion injuries, although their functional roles are not limited to these conditions. In this review, the basic aspects of CO, H₂S, and NO, including their production and effects on enzymes, mitochondrial respiration and biogenesis, and ion channels are briefly addressed to provide insight into their biology with respect to the CVS. Finally, potential therapeutic applications of CO, H₂S, and NO with the CVS are addressed, based on the use of exogenous donors and different types of delivery systems.

Protection against monocrotaline-induced pulmonary arterial hypertension and caveolin-1 downregulation by fluvastatin in rats

Statins are Hydroxymethylglutaryl-coenzyme A reductase inhibitors, which are typically used to lower blood cholesterol. Additional beneficial effects, including improvement to pulmonary arterial hypertension (PAH), have also been confirmed. However, the mechanisms underlying this improvement have not yet been clarified. The present study was conducted to determine if fluvastatin was protective against experimental PAH development and to investigate the potential effects of fluvastatin on caveolin‑1 (cav‑1) expression. Rats were randomized to either receive a single subcutaneous injection of monocrotaline (MCT; 60 mg/kg; MCT group) or a single subcutaneous injection of MCT (60 mg/kg) followed by an oral gavage of fluvastatin (10 mg/kg) once daily until day 42 (M + F group). Rats in the MCT group received an equivalent volume of saline following the MCT injection. Six additional rats were given an equivalent volume of saline throughout as a control measure. PAH associated variables and cav‑1 protein expression were measured in each group at various times during the experimental period. Hemodynamic and morphometric analysis revealed that M + F rats developed moderate, delayed PAH. Cav‑1 western blot analysis demonstrated that cav‑1 expression was not significantly different in fluvastatin treated rats; however, MCT injured rats given saline had markedly reduced cav‑1 expression. It was concluded that fluvastatin may protect against PAH development and ameliorate MCT induced inhibition of cav‑1 expression in rats.

Carbon monoxide in lung cell physiology and disease

Carbon monoxide (CO) is an endogenously produced gas that has gained recognition as a biological signal transduction effector with properties similar, but not identical, to that of nitric oxide (NO). CO, which binds primarily to heme iron, may activate the hemoprotein guanylate cyclase, although with lower potency than NO. Furthermore, CO can modulate the activities of several cellular signaling molecules such as p38 MAPK, ERK1/2, JNK, Akt, NF-κB, and others. Emerging studies suggest that mitochondria, the energy-generating organelle of cells, represent a key target of CO action in eukaryotes. Dose-dependent modulation of mitochondrial function by CO can result in alteration of mitochondrial membrane potential, mitochondrial reactive oxygen species production, release of proapoptotic and proinflammatory mediators, as well as the inhibition of respiration at high concentration. CO, through modulation of signaling pathways, can impact key biological processes including autophagy, mitochondrial biogenesis, programmed cell death (apoptosis), cellular proliferation, inflammation, and innate immune responses. Inhaled CO is widely known as an inhalation hazard due to its rapid complexation with hemoglobin, resulting in impaired oxygen delivery to tissues and hypoxemia. Despite systemic and cellular toxicity at high concentrations, CO has demonstrated cyto- and tissue-protective effects at low concentration in animal models of organ injury and disease. These include models of acute lung injury (e.g., hyperoxia, hypoxia, ischemia-reperfusion, mechanical ventilation, bleomycin) and sepsis. The success of CO as a candidate therapeutic in preclinical models suggests potential clinical application in inflammatory and proliferative disorders, which is currently under evaluation in clinical trials.

Delivery of Antioxidant and Anti-inflammatory Agents for Tissue Engineered Vascular Grafts

The treatment of patients with severe coronary and peripheral artery disease represents a significant clinical need, especially for those patients that require a bypass graft and do not have viable veins for autologous grafting. Tissue engineering is being investigated to generate an alternative graft. While tissue engineering requires surgical intervention, the release of pharmacological agents is also an important part of many tissue engineering strategies. Delivery of these agents offers the potential to overcome the major concerns for graft patency and viability. These concerns are related to an extended inflammatory response and its impact on vascular cells such as endothelial cells. This review discusses the drugs that have been released from vascular tissue engineering scaffolds and some of the non-traditional ways that the drugs are presented to the cells. The impact of antioxidant compounds and gasotransmitters, such as nitric oxide and carbon monoxide, are discussed in detail. The application of tissue engineering and drug delivery principles to biodegradable stents is also briefly discussed. Overall, there are scaffold-based drug delivery techniques that have shown promise for vascular tissue engineering, but much of this work is in the early stages and there are still opportunities to incorporate additional drugs to modulate the inflammatory process.

Carbon Monoxide and Its Controlled Release: Therapeutic Application, Detection, and Development of Carbon Monoxide Releasing Molecules (CORMs)

Carbon monoxide (CO) is attracting increasing attention because of its role as a gasotransmitter with cytoprotective and homeostatic properties. Carbon monoxide releasing molecules (CORMs) are spatially and temporally controlled CO releasers that exhibit superior and more effective pharmaceutical traits than gaseous CO because of their chemistry and structure. Experimental and preclinical research in animal models has shown the therapeutic potential of inhaled CO and CORMs, and the biological effects of CO and CORMs have also been observed in preclinical trials via the genetic modulation of heme oxygenase-1 (HO-1). In this review, we describe the pharmaceutical use of CO and CORMs, methods of detecting CO release, and developments in CORM design and synthesis. Many valuable clinical CORMs formulated using macromolecules and nanomaterials are also described.

Anesthesia-Related Carbon Monoxide Exposure: Toxicity and Potential Therapy

Exposure to carbon monoxide (CO) during general anesthesia can result from volatile anesthetic degradation by carbon dioxide absorbents and rebreathing of endogenously produced CO. Although adherence to the Anesthesia Patient Safety Foundation guidelines reduces the risk of CO poisoning, patients may still experience subtoxic CO exposure during low-flow anesthesia. The consequences of such exposures are relatively unknown. In contrast to the widely recognized toxicity of high CO concentrations, the biologic activity of low concentration CO has recently been shown to be cytoprotective. As such, low-dose CO is being explored as a novel treatment for a variety of different diseases. Here, we review the concept of anesthesia-related CO exposure, identify the sources of production, detail the mechanisms of overt CO toxicity, highlight the cellular effects of low-dose CO, and discuss the potential therapeutic role for CO as part of routine anesthetic management.

The role of carbon monoxide and heme oxygenase in the prevention of sickle cell disease vaso-occlusive crises

Sickle Cell Disease (SCD) is a painful, lifelong hemoglobinopathy inherited as a missense point mutation in the hemoglobin (Hb) beta-globin gene. This disease has significant impact on quality of life and mortality, thus a substantial medical need exists to reduce the vaso-occlusive crises which underlie the pathophysiology of the disease. The concept that a gaseous molecule may exert biological function has been well known for over one hundred years. Carbon monoxide (CO), although studied in SCD for over 50 years, has recently emerged as a powerful cytoprotective biological response modifier capable of regulating a host of physiologic and therapeutic processes that, at low concentrations, exerts key physiological functions in various models of tissue inflammation and injury. CO is physiologically generated by the metabolism of heme by the heme oxygenase enzymes and is measurable in blood. A substantial amount of preclinical and clinical data with CO have been generated, which provide compelling support for CO as a potential therapeutic in a number of pathological conditions. Data underlying the therapeutic mechanisms of CO, including in SCD, have been generated by a plethora of in vitro and preclinical studies including multiple SCD mouse models. These data show CO to have key signaling impacts on a host of metallo-enzymes as well as key modulating genes that in sum, result in significant anti-inflammatory, anti-oxidant and anti-apoptotic effects as well as vasodilation and anti-adhesion of cells to the endothelium resulting in preservation of vascular flow. CO may also have a role as an anti-polymerization HbS agent. In addition, considerable scientific data in the non-SCD literature provide evidence for a beneficial impact of CO on cerebrovascular complications, suggesting that in SCD, CO could potentially limit these highly problematic neurologic outcomes. Research is needed and hopefully forthcoming, to carefully elucidate the safety and benefits of this potential therapy across the age spectrum of patients impacted by the host of pathophysiological complications of this devastating disease.

Ultraviolet-A1 irradiation therapy for systemic lupus erythematosus

Systemic lupus erythematosus (lupus, SLE) is a chronic autoimmune disease characterized by the production of autoantibodies, which bind to antigens and are deposited within tissues to fix complement, resulting in widespread systemic inflammation. The studies presented herein are consistent with hyperpolarized, adenosine triphosphate (ATP)-deficient mitochondria being central to the disease process. These hyperpolarized mitochondria resist the depolarization required for activation-induced apoptosis. The mitochondrial ATP deficits add to this resistance to apoptosis and also reduce the macrophage energy that is needed to clear apoptotic bodies. In both cases, necrosis, the alternative pathway of cell death, results. Intracellular constituents spill into the blood and tissues, eliciting inflammatory responses directed at their removal. What results is “autoimmunity.” Ultraviolet (UV)-A1 photons have the capacity to remediate this aberrancy. Exogenous exposure to low-dose, full-body, UV-A1 radiation generates singlet oxygen. Singlet oxygen has two major palliative actions in patients with lupus and the UV-A1 photons themselves have several more. Singlet oxygen depolarizes the hyperpolarized mitochondrion, triggering non-ATP-dependent apoptosis that deters necrosis. Next, singlet oxygen activates the gene encoding heme oxygenase (HO-1), a major governor of systemic homeostasis. HO-1 catalyzes the degradation of the oxidant heme into biliverdin (converted to bilirubin), Fe, and carbon monoxide (CO), the first three of these exerting powerful antioxidant effects, and in conjunction with a fourth, CO, protecting against injury to the coronary arteries, the central nervous system, and the lungs. The UV-A1 photons themselves directly attenuate disease in lupus by reducing B cell activity, preventing the suppression of cell-mediated immunity, slowing an epigenetic progression toward SLE, and ameliorating discoid and subacute cutaneous lupus. Finally, a combination of these mechanisms reduces levels of anticardiolipin antibodies and protects during lupus pregnancy. Capping all of this is that UV-A1 irradiation is an essentially innocuous, highly manageable, and comfortable therapeutic agency.

Heme Oxygenase-1 and Carbon Monoxide in the Heart: The Balancing Act Between Danger Signaling and Pro-Survival

Understanding the processes governing the ability of the heart to repair and regenerate after injury is crucial for developing translational medical solutions. New avenues of exploration include cardiac cell therapy and cellular reprogramming targeting cell death and regeneration. An attractive possibility is the exploitation of cytoprotective genes that exist solely for self-preservation processes and serve to promote and support cell survival. Although the antioxidant and heat-shock proteins are included in this category, one enzyme that has received a great deal of attention as a master protective sentinel is heme oxygenase-1 (HO-1), the rate-limiting step in the catabolism of heme into the bioactive signaling molecules carbon monoxide, biliverdin, and iron. The remarkable cardioprotective effects ascribed to heme oxygenase-1 are best evidenced by its ability to regulate inflammatory processes, cellular signaling, and mitochondrial function ultimately mitigating myocardial tissue injury and the progression of vascular-proliferative disease. We discuss here new insights into the role of heme oxygenase-1 and heme on cardiovascular health, and importantly, how they might be leveraged to promote heart repair after injury.

Carbon Monoxide-Releasing Molecule-401 Suppresses Polymorphonuclear Leukocyte Migratory Potential by Modulating F-Actin Dynamics

Carbon monoxide-releasing molecules (CORMs) suppress inflammation by reducing polymorphonuclear leukocyte (PMN) recruitment to the affected organs. We investigated modulation of PMN-endothelial cell adhesive interactions by water-soluble CORM-401 using an experimental model of endotoxemia in vitro. Human umbilical vein endothelial cells (HUVEC) grown on laminar-flow perfusion channels were stimulated with 1 μg/mL lipopolysaccharide for 6 hours and perfused with 100 μmol/L CORM-401 (or inactive compound iCORM-401)-pretreated PMN for 5 minutes in the presence of 1.0 dyn/cm² shear stress.

HUVEC

PMN co-cultures were perfused for additional 15 minutes with PMN-free medium containing CORM-401/inactive CORM-401. The experiments were videorecorded (phase-contrast microscopy), and PMN adhesion/migration were assessed off-line. In parallel, CORM-401-dependent modulation of PMN chemotaxis, F-actin expression/distribution, and actin-regulating pathways [eg, p21-activated protein kinases (PAK1/2) and extracellular signal-regulated kinase (ERK)/C-Jun N-terminal kinase (JNK) mitogen-activated protein kinases (MAPK)] were assessed in response to N-formyl-methionyl-leucyl-phenylalanine (fMLP) stimulation. Pretreating PMN with CORM-401 did not suppress PMN adhesion to HUVEC, but significantly reduced PMN transendothelial migration (P < 0.0001) and fMLP-induced PMN chemotaxis (ie, migration directionality and velocity). These changes were associated with CORM-401-dependent suppression of F-actin levels/cellular distribution and fMLP-induced phosphorylation of PAK1/2 and ERK/JNK MAPK (P < 0.05). CORM-401 had no effect on p38 MAPK activation. In summary, this study demonstrates, for the first time, CORM-401-dependent suppression of neutrophil migratory potential associated with modulation of PAK1/2 and ERK/JNK MAPK signaling and F-actin dynamics.

Biological signaling by carbon monoxide and carbon monoxide-releasing molecules

Carbon monoxide (CO) is continuously produced in mammalian cells during the degradation of heme. It is a stable gaseous molecule that reacts selectively with transition metals in a specific redox state, and these characteristics restrict the interaction of CO with defined biological targets that transduce its signaling activity. Because of the high affinity of CO for ferrous heme, these targets can be grouped into heme-containing proteins, representing a large variety of sensors and enzymes with a series of diverse function in the cell and the organism. Despite this notion, progress in identifying which of these targets are selective for CO has been slow and even the significance of elevated carbonmonoxy hemoglobin, a classical marker used to diagnose CO poisoning, is not well understood. This is also due to the lack of technologies capable of assessing in a comprehensive fashion the distribution and local levels of CO between the blood circulation, the tissue, and the mitochondria, one of the cellular compartments where CO exerts its signaling or detrimental effects. Nevertheless, the use of CO gas and CO-releasing molecules as pharmacological approaches in models of disease has provided new important information about the signaling properties of CO. In this review we will analyze the most salient effects of CO in biology and discuss how the binding of CO with key ferrous hemoproteins serves as a posttranslational modification that regulates important processes as diverse as aerobic metabolism, oxidative stress, and mitochondrial bioenergetics.

Beneficial effects of aqueous extract of stem bark of Terminalia arjuna (Roxb.), An ayurvedic drug in experimental pulmonary hypertension

ETHNOPHARMACOLOGICAL RELEVANCE

The stem bark of Terminalia arjuna (Roxb.) is widely used in Ayurveda in various cardiovascular diseases. Many animal and clinical studies have validated its anti-ischemic, antihypertensive, antihypertrophic and antioxidant effects. Pulmonary hypertension (PH) is a fatal disease which causes right ventricular hypertrophy and right heart failure. Pulmonary vascular smooth muscle hypertrophy and increased oxidative stress are major pathological features of PH. As available limited therapeutic options fail to reduce the mortality associated with PH, alternative areas of therapy are worth exploring for potential drugs, which might be beneficial in PH.

AIM OF THE STUDY

The effect of a standardised aqueous extract of the stem bark of Terminalia arjuna (Roxb.) in preventing monocrotaline (MCT)-induced PH in rat was investigated.

MATERIALS AND METHODS

The study was approved by Institutional Animal Ethics Committe. Male Wistar rats (150-200g) were randomly distributed into five groups; Control, MCT (50mg/kg subcutaneously once), sildenafil (175µg/kg/day three days after MCT for 25 days), and Arjuna extract (TA125 and TA250 mg/kg/day orally after MCT for 25 days). PH was confirmed by right ventricular weight to left ventricular plus septum weight (Fulton index), right ventricular systolic pressure (RVSP), echocardiography, percentage medial wall thickness of pulmonary arteries (%MWT). Oxidative stress in lung was assessed by super oxide dismutase (SOD), catalase, reduced glutathione (GSH) and thiobarbituric acid reactive substance (TBARS). The protein expressions of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX-1) in lung and gene expression of Bcl2 and Bax in heart were analyzed by Western blot and RT PCR respectively.

RESULTS

MCT caused right ventricular hypertrophy (0.58±0.05 vs 0.31±0.05; P<0.001 vs. control) and increase in RVSP (33.5±1.5 vs 22.3±4.7mm of Hg; P<0.001). Both sildenafil and Arjuna prevented hypertrophy and RVSP. Pulmonary artery acceleration time to ejection time ratio in echocardiography was decreased in PH rats (0.49±0.05 vs 0.32±0.06; P<0.001) which was prevented by sildenafil (0.44±0.06; P<0.01) and TA250 (0.45±0.06; P<0.01). % MWT of pulmonary arteries was increased in PH and was prevented by TA250. Increase in TBARS (132.7±18.4 vs 18.8±1.6nmol/mg protein; P<0.001) and decrease in SOD (58.4±14.1 vs 117.4±26.9U/mg protein; P<0.001) and catalase (0.30±0.05 vs 0.75±0.31U/mg protein; P<0.001) were observed in lung tissue of PH rats, which were prevented by sildenafil and both the doses of Arjuna extract. Protein expression of NOX1 was significantly increased in lung and gene expression of Bcl2/Bax ratio was significantly decreased in right ventricle in MCT-induced PH, both were significantly prevented by Arjuna and sildenafil.

CONCLUSIONS

Aqueous extract of Terminalia arjuna prevented MCT-induced pulmonary hypertension which may be attributed to its antioxidant as well as its effects on pulmonary arteriolar wall thickening.

Gasotransmitter delivery via self-assembling peptides: Treating diseases with natural signaling gases

Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂S) are powerful signaling molecules that play a variety of roles in mammalian biology. Collectively called gasotransmitters, these gases have wide-ranging therapeutic potential, but their clinical use is limited by their gaseous nature, extensive reactivity, short half-life, and systemic toxicity. Strategies for gasotransmitter delivery with control over the duration and location of release are therefore vital for developing effective therapies. An attractive strategy for gasotransmitter delivery is though injectable or implantable gels, which can ideally deliver their payload over a controllable duration and then degrade into benign metabolites. Self-assembling peptide-based gels are well-suited to this purpose due to their tunable mechanical properties, easy chemical modification, and inherent biodegradability. In this review we illustrate the biological roles of NO, CO, and H₂S, discuss their therapeutic potential, and highlight recent efforts toward their controlled delivery with a focus on peptide-based delivery systems.

Nonmetallic carbon monoxide releasing molecules (CORMs)

Recent progress on nonmetallic carbon monoxide releasing molecules (CORMs) is reviewed.

Involvement of CapG in proliferation and apoptosis of pulmonary arterial smooth muscle cells and in hypoxia-induced pulmonary hypertension rat model

PURPOSE

Actin-binding protein capping protein gelsolin-like (CapG) was preferentially expressed in human pulmonary arterial smooth muscle cells (PASMCs) under hypoxia, and reduced CapG expression was accompanied by impaired migration ability in vitro. We intended to investigate the effects of CapG on rat PASMCs and hypoxia-induced pulmonary hypertension (HPH) rat model.

MATERIALS AND METHODS

We investigated the effect of RNA interference-medicated down-regulation of CapG expression in rat PASMCs as well as in HPH rat model. The proliferation, apoptosis and cell cycle of PASMCs were evaluated. The HPH rat model was established by intratracheal instillation of lentiviral vector and subsequent hypoxia exposure for four weeks. Right ventricular systolic pressure, right ventricular hypertrophy and the percentage of medial wall thickness were measured to evaluate the development of HPH.

RESULTS

Knock-down CapG in PASMCs resulted in decreased proliferation, increased apoptosis and induced cell cycle inhibition. Down-regulation of CapG expression locally could attenuate pulmonary hypertension, pulmonary vascular remodeling and right ventricular hypertrophy in HPH rat model.

CONCLUSIONS

Our study indicated that CapG participated in the pathogenesis of pulmonary vascular remodeling in HPH rats, which was probably mediated by promoting the proliferation and inhibiting the apoptosis of PASMCs. We proposed CapG modulating protective effects of pulmonary hypertension.

My Continuing Evolution as a Surgeon-Scientist: A Decade after the Jacobson Promising Investigator Award

THE SECOND JOAN L AND JULIUS H JACOBSON PROMISING INVESTIGATOR AWARDEE, EDITH TZENG MD, FACS: In 2005, the Surgical Research Committee of the American College of Surgeons was tasked with selecting the recipient of a newly established award, "The Joan L and Julius H Jacobson Promising Investigator Award." According to the Jacobsons, the award funded by Dr Jacobson should be given at least once every 2 years to a surgeon investigator at "the tipping point," who can demonstrate that his or her research shows the promise of leading to a significant contribution to the practice of surgery and patient safety. Every year, the Surgical Research Committee receives many excellent nominations and has the difficult task of selecting one awardee. The first awardee was Michael Longaker MD, FACS, who 10 years later reflected on the award and the impact it had on his career.¹ This year, Edith Tzeng, MD, FACS, the second Jacobson awardee, reflects on her 10-year journey after receiving the award. Dr Tzeng is now a national and international figure in the field of vascular surgery and has studied the effect of nitric oxide and carbon monoxide on intimal hyperplasia. Kamal MF Itani, MD, FACS and Leigh Neumayer, MD, FACS, on behalf of the Surgical Research Committee of the American College of Surgeons.

Heme Oxygenases in Cardiovascular Health and Disease

Heme oxygenases are composed of two isozymes, Hmox1 and Hmox2, that catalyze the degradation of heme to carbon monoxide (CO), ferrous iron, and biliverdin, the latter of which is subsequently converted to bilirubin. While initially considered to be waste products, CO and biliverdin/bilirubin have been shown over the last 20 years to modulate key cellular processes, such as inflammation, cell proliferation, and apoptosis, as well as antioxidant defense. This shift in paradigm has led to the importance of heme oxygenases and their products in cell physiology now being well accepted. The identification of the two human cases thus far of heme oxygenase deficiency and the generation of mice deficient in Hmox1 or Hmox2 have reiterated a role for these enzymes in both normal cell function and disease pathogenesis, especially in the context of cardiovascular disease. This review covers the current knowledge on the function of both Hmox1 and Hmox2 at both a cellular and tissue level in the cardiovascular system. Initially, the roles of heme oxygenases in vascular health and the regulation of processes central to vascular diseases are outlined, followed by an evaluation of the role(s) of Hmox1 and Hmox2 in various diseases such as atherosclerosis, intimal hyperplasia, myocardial infarction, and angiogenesis. Finally, the therapeutic potential of heme oxygenases and their products are examined in a cardiovascular disease context, with a focus on how the knowledge we have gained on these enzymes may be capitalized in future clinical studies.

2-AMINOETHYLDIPHENYLBORINATE MODIFIES THE PULMONARY CIRCULATION IN PULMONARY HYPERTENSIVE NEWBORN LAMBS WITH PARTIAL GESTATION AT HIGH ALTITUDE

Calcium signaling through store operated channels (SOC) is involved in hypoxic pulmonary hypertension. We determined whether a treatment with 2-aminoethyldiphenylborinate (2-APB), a compound with SOC blocker activity, reduces pulmonary hypertension and vascular remodeling. Twelve newborn lambs exposed to perinatal chronic hypoxia were studied, 6 of them received a 2-APB treatment and the other 6 received vehicle treatment, for 10 days in both cases. Throughout this period, we recorded cardiopulmonary variables and on day 11 we evaluated the response to an acute hypoxic challenge. Additionally, we assessed the vasoconstrictor and vasodilator function in isolated pulmonary arteries as well as their remodeling in lung slices. 2-APB reduced pulmonary arterial pressure at the third and tenth days, cardiac output between the fourth and eighth days, and pulmonary vascular resistance at the tenth day of treatment. The pulmonary vasoconstrictor response to acute hypoxia was reduced by the end of treatment. 2-APB also decreased maximal vasoconstrictor response to the thromboxane mimetic U46619 and endothelin-1 and increased maximal relaxation to 8-Br-cGMP. The maximal relaxation and potency to phosphodiesterase-5 and Rho-kinase inhibition with sildenafil and fasudil respectively, were also increased. Finally, 2-APB reduced the medial and adventitial layers' thickness, the expression of α-actin and the percentage of Ki67+ nuclei of small pulmonary arteries. Taken together, our results indicate that 2-APB reduces pulmonary hypertension, vasoconstrictor responses and pathological remodeling in pulmonary hypertensive lambs. We conclude that SOC targeting may be a useful strategy for the treatment of neonatal pulmonary hypertension, however, further testing of specific blockers is needed.

Association between smoking and the risk of acute mountain sickness: a meta-analysis of observational studies

BACKGROUND

People rapidly ascending to high altitudes (>2500 m) may suffer from acute mountain sickness (AMS). The association between smoking and AMS risk remains unclear. Therefore, we performed a meta-analysis to evaluate the association between smoking and AMS risk.

METHODS

The association between smoking and AMS risk was determined according to predefined criteria established by our team. Meta-analysis was conducted according to the PRISMA guidelines. We included all relevant studies listed in the PubMed and Embase databases as of September 2015 in this meta-analysis and performed systemic searches using the terms "smoking", "acute mountain sickness" and "risk factor". The included studies were required to provide clear explanations regarding their definitions of smoking, the final altitudes reached by their participants and the diagnostic criteria used to diagnose AMS. Odds ratios (ORs) were used to evaluate the association between smoking and AMS risk across the studies, and the Q statistic was used to test OR heterogeneity, which was considered significant when P < 0.05. We also computed 95% confidence intervals (CIs). Data extracted from the articles were analyzed with Review Manager 5.3 (Cochrane Collaboration, Oxford, UK).

RESULTS

We used seven case-control studies including 694 smoking patients and 1986 non-smoking controls to analyze the association between smoking and AMS risk. We observed a significant association between AMS and smoking (OR = 0.71, 95% CI 0.52-0.96, P = 0.03).

CONCLUSIONS

We determined that smoking may protect against AMS development. However, we do not advise smoking to prevent AMS. More studies are necessary to confirm the role of smoking in AMS risk.

Pretreatment of human cerebrovascular endothelial cells with CO-releasing molecule-3 interferes with JNK/AP-1 signaling and suppresses LPS-induced proadhesive phenotype

OBJECTIVE

Exogenously administered CO interferes with PMN recruitment to the inflamed organs. The mechanisms of CO-dependent modulation of vascular proadhesive phenotype, a key step in PMN recruitment, are unclear.

METHODS

We assessed the effects/mechanisms of CO liberated from a water-soluble CORM-3 on modulation of the proadhesive phenotype in hCMEC/D3 in an in vitro model of endotoxemia. To this end, hCMEC/D3 were stimulated with LPS (1 μg/mL) for six hours. In some experiments hCMEC/D3 were pretreated with CORM-3 (200 μmol/L) before LPS-stimulation. PMN rolling/adhesion to hCMEC/D3 were assessed under conditions of laminar shear stress (0.7 dyn/cm(2) ). In parallel, expression of adhesion molecules E-selectin, ICAM-1, and VCAM-1 (qPCR), activation of transcription factors, NF-κB and AP-1 (ELISA), and MAPK-signaling (expression/phosphorylation of p38, ERK1/2, and JNK1/2; western blot) were assessed.

RESULTS

The obtained results indicate that CORM-3 pretreatment reduces PMN rolling/adhesion to LPS-stimulated hCMEC/D3 (p < 0.05). Decreased PMN rolling/adhesion to hCMEC/D3 was associated with CORM-3-dependent inhibition of MAPK JNK1/2 activation (Tyr-phosphorylation), inhibition of transcription factor, AP-1 (c-Jun phosphorylation), and subsequent suppression of VCAM-1 expression (p < 0.05).

CONCLUSIONS

These findings indicate that CORM-3 pretreatment interferes with JNK/AP-1 signaling and suppresses LPS-induced upregulation of the proadhesive phenotype in hCMEC/D3.

Macromolecular and Inorganic Nanomaterials Scaffolds for Carbon Monoxide Delivery: Recent Developments and Future Trends

Carbon monoxide (CO) is as an important biological gasomediator. It plays significant roles in anti-inflammatory, antihypertensive, and antiapoptotic pathways. Preclinical evidence in animal models has proven the beneficial effects of controlled CO gas administration. However, the medical use of CO gas has been hindered due to its administration. Indeed, its toxicity at high concentrations and the challenging delivery to specific target sites are the limiting factors. To overcome these problems, a wide range of CO-releasing molecules have been designed, and some have emerged as potential therapeutic agents. Despite some successes, these small CO-releasing molecules have limited stability in biologic media resulting in an unspecific release of CO, which could result in side effects. CO-releasing macromolecular and inorganic nanomaterial scaffolds have emerged as promising carriers due to their ability to encapsulate and deliver high amounts of CO-releasing molecules. Furthermore, polymer architecture could be designed for the controlled release of CO under specific stimuli. After highlighting some recent developments in the design of CO-releasing scaffolds, this review will discuss strategies and possible future directions of CO releasing macromolecules and inorganic nanomaterials for potential therapeutic applications.