Nicorandil attenuates NF-kappaB activation, adhesion molecule expression, and cytokine production in patients with coronary artery bypass surgery

Overview of pyroptosis mechanism and in-depth analysis of cardiomyocyte pyroptosis mediated by NF-κB pathway in heart failure

The pyroptosis of cardiomyocytes has become an essential topic in heart failure research. The abnormal accumulation of these biological factors, including angiotensin II, advanced glycation end products, and various growth factors (such as connective tissue growth factor, vascular endothelial growth factor, transforming growth factor beta, among others), activates the nuclear factor-κB (NF-κB) signaling pathway in cardiovascular diseases, ultimately leading to pyroptosis of cardiomyocytes. Therefore, exploring the underlying molecular biological mechanisms is essential for developing novel drugs and therapeutic strategies. However, our current understanding of the precise regulatory mechanism of this complex signaling pathway in cardiomyocyte pyroptosis is still limited. Given this, this study reviews the milestone discoveries in the field of pyroptosis research since 1986, analyzes in detail the similarities, differences, and interactions between pyroptosis and other cell death modes (such as apoptosis, necroptosis, autophagy, and ferroptosis), and explores the deep connection between pyroptosis and heart failure. At the same time, it depicts in detail the complete pathway of the activation, transmission, and eventual cardiomyocyte pyroptosis of the NF-κB signaling pathway in the process of heart failure. In addition, the study also systematically summarizes various therapeutic approaches that can inhibit NF-κB to reduce cardiomyocyte pyroptosis, including drugs, natural compounds, small molecule inhibitors, gene editing, and other cutting-edge technologies, aiming to provide solid scientific support and new research perspectives for the prevention and treatment of heart failure.

Therapeutic potential of nicorandil beyond anti-anginal drug: A review on current and future perspectives

Nicorandil (NIC) is a well-known anti-anginal agent, which has been recommended as one of the second-line treatments for chronic stable angina as justified by the European guidelines. It shows an efficacy equivalent to that of classic anti-anginal agents. NIC has also been used clinically in various cardiovascular diseases such as variant or unstable angina and reperfusion-induced damage following coronary angioplasty or thrombolysis. Different mechanisms have been involved in the protective effects of nicorandil in various diseases, including opening of adenosine triphosphate-sensitive potassium (KATP) channel and donation of nitric oxide (NO). In recent years, NIC has been found to show numerous pharmacological activities such as neuroprotective, nephroprotective, hepatoprotective, cardioprotective, and testicular protective effects, among other beneficial effects on the body. The present review dwells on the pharmacological potentials of NIC beyond its anti-anginal action.

KATP channels are regulators of programmed cell death and targets for the creation of novel drugs against ischemia/reperfusion cardiac injury

BACKGROUND

The use of percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI) is associated with a mortality rate of 5%-7%. It is clear that there is an urgent need to develop new drugs that can effectively prevent cardiac reperfusion injury. ATP-sensitive K+ (KATP ) channel openers (KCOs) can be classified as such drugs.

RESULTS

KCOs prevent irreversible ischemia and reperfusion injury of the heart. KATP channel opening promotes inhibition of apoptosis, necroptosis, pyroptosis, and stimulation of autophagy. KCOs prevent the development of cardiac adverse remodeling and improve cardiac contractility in reperfusion. KCOs exhibit antiarrhythmic properties and prevent the appearance of the no-reflow phenomenon in animals with coronary artery occlusion and reperfusion. Diabetes mellitus and a cholesterol-enriched diet abolish the cardioprotective effect of KCOs. Nicorandil, a KCO, attenuates major adverse cardiovascular event and the no-reflow phenomenon, reduces infarct size, and decreases the incidence of ventricular arrhythmias in patients with acute myocardial infarction.

CONCLUSION

The cardioprotective effect of KCOs is mediated by the opening of mitochondrial KATP (mitoKATP ) and sarcolemmal KATP (sarcKATP ) channels, triggered free radicals' production, and kinase activation.

Pharmacological Cardioprotection against Ischemia Reperfusion Injury-The Search for a Clinical Effective Therapy

Pharmacological conditioning aims to protect the heart from myocardial ischemia-reperfusion injury (IRI). Despite extensive research in this area, today, a significant gap remains between experimental findings and clinical practice. This review provides an update on recent developments in pharmacological conditioning in the experimental setting and summarizes the clinical evidence of these cardioprotective strategies in the perioperative setting. We start describing the crucial cellular processes during ischemia and reperfusion that drive acute IRI through changes in critical compounds (∆G_ATP, Na⁺, Ca²⁺, pH, glycogen, succinate, glucose-6-phosphate, mitoHKII, acylcarnitines, BH₄, and NAD⁺). These compounds all precipitate common end-effector mechanisms of IRI, such as reactive oxygen species (ROS) generation, Ca²⁺ overload, and mitochondrial permeability transition pore opening (mPTP). We further discuss novel promising interventions targeting these processes, with emphasis on cardiomyocytes and the endothelium. The limited translatability from basic research to clinical practice is likely due to the lack of comorbidities, comedications, and peri-operative treatments in preclinical animal models, employing only monotherapy/monointervention, and the use of no-flow (always in preclinical models) versus low-flow ischemia (often in humans). Future research should focus on improved matching between preclinical models and clinical reality, and on aligning multitarget therapy with optimized dosing and timing towards the human condition.

Protective or Inhibitory Effect of Pharmacological Therapy on Cardiac Ischemic Preconditioning: A Literature Review

Ischemic preconditioning (IP) is an innate phenomenon, triggered by brief, non-lethal cycles of ischemia/reperfusion applied to a tissue or organ that confers tolerance to a subsequent more prolonged ischemic event. Once started, it can reduce the severity of myocardial ischemia associated with some clinical situations, such as percutaneous coronary intervention (PCI) and intermittent aortic clamping during coronary artery bypass graft surgery (CABG). Although the mechanisms underlying IP have not been completely elucidated, several studies have shown that this phenomenon involves the participation of cell triggers, intracellular signaling pathways, and end-effectors. Understanding this mechanism enables the development of preconditioning mimetic agents. It is known that a range of medications that activate the signaling cascades at different cellular levels can interfere with both the stimulation and the blockade of IP. Investigations of signaling pathways underlying ischemic conditioning have identified a number of therapeutic targets for pharmacological manipulation. This review aims to present and discuss the effects of several medications on myocardial IP.

Nicorandil attenuates ventricular dysfunction and organ injury after cardiopulmonary bypass

BACKGROUND

Nicorandil, an adenosine triphosphate-sensitive potassium channel agonist and nitric oxide donor, is a coronary vasodilator used to treat ischemia-induced chest pain, but it's potential cardioprotective benefits during open heart surgery have not been thoroughly investigated. The study objective was to assess the impact of nicorandil on postoperative ventricular dysfunction and end-organ injury in an established experimental model of open-heart surgery with cardiopulmonary bypass (CPB) and cardioplegic arrest. We hypothesized that nicorandil would attenuate myocardial ischemia-reperfusion (IR) injury, preserve ventricular function, and reduce end-organ injury.

METHODS

Rabbits were cannulated for CPB, followed by 60 min of aortic cross-clamp (ACC) with cold cardioplegic arrest, and 120 min of recovery after ACC removal. Nicorandil (or normal saline vehicle) was given intravenously 5 min before ACC and continued throughout the recovery period. Left ventricular developed pressure (LVDP), systolic contractility (LV + dP/dt), and diastolic relaxation (LV -dP/dt) were continuously recorded, and blood and tissue samples were collected for measurement of oxidant stress (OS), inflammation, apoptosis, and organ injury.

RESULTS

Nicorandil significantly attenuated IR-induced LV dysfunction compared to saline control (R-120: LV + dP/dt: 1596 ± 397 vs. 514 ± 269 mmHg/s, p = 0.010; LV -dP/dt: -1524 ± 432 vs. -432 ± 243 mmHg/s, p < 0.001; LVDP: 55 ± 11 vs. 22 ± 5 mmHg, p = 0.046). Furthermore, nicorandil inhibited IR-induced increases in OS, inflammation, apoptosis, and organ injury.

CONCLUSIONS

Nicorandil exhibits myocardial protection by attenuation of IR-induced LV dysfunction associated with OS, inflammation, apoptosis, and organ injury. Nicorandil should be explored further as a potential therapeutic strategy for limiting global IR injury during open-heart surgery in humans.

Modulating the Bioactivity of Nitric Oxide as a Therapeutic Strategy in Cardiac Surgery

Cardiac surgery, including cardioplegic arrest and extracorporeal circulation, causes endothelial dysfunction, which can lead to no-reflow phenomenon and reduction of myocardial pump function. Nitric oxide (NO) deficiency is involved in this pathologic process, thereby providing a fundamental basis for the use of NO replacement therapy. Presently used drugs and additives to cardioplegic and heart preservation solutions are not able to reliably protect endothelial cells and cardiomyocytes from ischemia-reperfusion injury. This review discusses promising NO-releasing compounds of various chemical classes for cardioplegia and reperfusion, which effectively maintain NO homeostasis under experimental conditions, and presents the mechanisms of their action on the cardiovascular system. Incomplete preclinical studies and a lack of toxicity assessment, however, hinder translation of these drug candidates into the clinic. Perspectives for modulation of endothelial function using NO-mediated mechanisms are discussed. They are based on the cardioprotective potential of targeting vascular gap junctions and endothelial ion channels, intracoronary administration of progenitor cells, and endothelial-specific microRNAs. Some of these strategies may provide important therapeutic benefits for human cardiovascular interventions.

Exogenous NO Therapy for the Treatment and Prevention of Atherosclerosis

Amyl nitrite was introduced in 1867 as the first molecule of a new class of agents for the treatment of angina pectoris. In the following 150 years, the nitric oxide pathway has been the subject of a number of pharmacological approaches, particularly since when this elusive mediator was identified as one of the most important modulators of vascular homeostasis beyond vasomotion, including platelet function, inflammation, and atherogenesis. While having potent antianginal and antiischemic properties, however, nitric oxide donors are also not devoid of side effects, including the induction of tolerance, and, as shown in the last decade, of oxidative stress and endothelial dysfunction. In turn, endothelial dysfunction is itself felt to be involved in all stages of atherogenesis, from the development of fatty streaks to plaque rupture and thrombosis. In the present review, we summarize the agents that act on the nitric oxide pathway, with a particular focus on their potentially beneficial antiatherosclerotic and unwanted pro-atherosclerotic effects.

Nicorandil combats doxorubicin-induced nephrotoxicity via amendment of TLR4/P38 MAPK/NFκ-B signaling pathway

Nicorandil ameliorated doxorubicin-induced nephrotoxicity; this study aimed to show and explain the mechanism of this protection. A precise method was elucidated to study the effect of nicorandil on doxorubicin-induced nephrotoxicity in rats depending on the critical inflammation pathway TLR4/MAPK P38/NFκ-B. Adult male rats were subdivided into four groups. The 1st group was normal control, the 2nd group received nicorandil (3 mg/kg; p.o., for 4 weeks), the 3rd group received doxorubicin (2.6 mg/kg, i.p., twice per week for 4 weeks), and the fourth group was combination of doxorubicin and nicorandil for 4 weeks. Nephrotoxicity was assessed by biochemical tests through measuring Kidney function biomarkers such as [serum levels of urea, creatinine, albumin and total protein] besides renal kidney injury molecule-1 (KIM-1) and cystatin C], oxidative stress parameters such as [renal tissue malondialdehyde (MDA), reduced glutathione (GSH), SOD, catalase and nrf-2], mediators of inflammation such as [Toll like receptor 4 (TLR-4), Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB), p38 MAPK, Interleukin 1 beta (IL-1 β), and Tumor necrosis factor alpha (TNF-α)] and markers of apoptosis [BAX and Bcl-2 in renal tissue]. Finally, our data were supported by histopathology examination. Nicorandil pretreatment resulted in a significant decrease in nephrotoxicity biomarkers, oxidative stress markers, inflammatory mediators and prevented apoptosis through decreasing BAX and increasing Bcl-2 in renal tissues. Nicorandil prevented all the histological alterations caused by doxorubicin. Nicorandil is a promising antidote against doxorubicin-induced nephrotoxicity by neutralizing all toxicity mechanisms caused by doxorubicin through normalizing inflammatory cascade of TLR4/MAPK P38/NFκ-B.

Overexpression of microRNA-146 protects against oxygen-glucose deprivation/recovery-induced cardiomyocyte apoptosis by inhibiting the NF-κB/TNF-α signaling pathway

MicroRNA (miR) has been reported to be associated with ischemia and reperfusion (I/R) and cell apoptosis. Suppression of cell apoptosis may reduce the irreversible damage induced by reperfusion. The aims of the current study were to explore the cytoprotective effects of miR-146 against oxygen-glucose deprivation/recovery (OGD/R)-induced injury in H9c2 rat myocardial cells, as well as the underlying mechanisms. Following stimulation with OGD/R, the cells were transfected with miR-146 mimics or negative controls. The levels of miR-146 were analyzed by reverse transcription-quantitative polymerase chain reaction. Thereafter, cell viability and cell apoptosis were analyzed by MTT assay and terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling assay, respectively. In addition, the levels of tumor necrosis factor (TNF)-α were determined by ELISA and the levels of B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax), Bcl-2 and phosphorylated (p)-nuclear factor (NF)-κB were measured by western blotting. The results demonstrated that overexpression of miR-146 significantly increased cell viability and decreased apoptosis (P<0.05). It was observed that overexpression of miR-146 statistically reduced the levels of Bax, TNF-α and p-NF-κB but markedly upregulated the levels of Bcl-2 (P<0.05). These results indicate that overexpression of miR-146 may protect against OGD/R-induced cardiomyocyte apoptosis. Overexpression of miR-146 may alleviate the irreversible injury associated with reperfusion and the effects may be achieved by inhibiting the NF-κB/TNF-α signaling pathway.

ATP sensitive potassium channel openers: A new class of ocular hypotensive agents

ATP sensitive potassium (K_ATP) channels connect the metabolic and energetic state of cells due to their sensitivity to ATP and ADP concentrations. K_ATP channels have been identified in multiple tissues and organs of the body including heart, pancreas, vascular smooth muscles and skeletal muscles. These channels are obligatory hetero-octamers and contain four sulfonylurea (SUR) and four potassium inward rectifier (K_ir) subunits. Based on the particular type of SUR and K_ir present, there are several tissue specific subtypes of K_ATP channels, each with their own unique set of functions. Recently, K_ATP channels have been reported in human and mouse ocular tissues. In ex vivo and in vivo model systems, K_ATP channel openers showed significant ocular hypotensive properties with no appearance of toxic side effects. Additionally, when used in conjunction with known intraocular pressure lowering drugs, an additive effect on IOP reduction was observed. These K_ATP channel openers have also been reported to protect the retinal ganglion cells during ischemic stress and glutamate induced toxicity suggesting a neuroprotective property for this drug class. Medications that are currently used for treating ocular hypertensive diseases like glaucoma do not directly protect the affected retinal cells, are sometimes ineffective and may show significant side effects. In light of this, K_ATP channel openers with both ocular hypotensive and neuroprotective properties, have the potential to develop into a new class of glaucoma therapeutics.

Nicorandil, a Nitric Oxide Donor and ATP-Sensitive Potassium Channel Opener, Protects Against Dystrophin-Deficient Cardiomyopathy

BACKGROUND

Dystrophin-deficient cardiomyopathy is a growing clinical problem without targeted treatments. We investigated whether nicorandil promotes cardioprotection in human dystrophin-deficient induced pluripotent stem cell (iPSC)-derived cardiomyocytes and the muscular dystrophy mdx mouse heart.

METHODS AND RESULTS

Dystrophin-deficient iPSC-derived cardiomyocytes had decreased levels of endothelial nitric oxide synthase and neuronal nitric oxide synthase. The dystrophin-deficient cardiomyocytes had increased cell injury and death after 2 hours of stress and recovery. This was associated with increased levels of reactive oxygen species and dissipation of the mitochondrial membrane potential. Nicorandil pretreatment was able to abolish these stress-induced changes through a mechanism that involved the nitric oxide-cyclic guanosine monophosphate pathway and mitochondrial adenosine triphosphate-sensitive potassium channels. The increased reactive oxygen species levels in the dystrophin-deficient cardiomyocytes were associated with diminished expression of select antioxidant genes and increased activity of xanthine oxidase. Furthermore, nicorandil was found to improve the restoration of cardiac function after ischemia and reperfusion in the isolated mdx mouse heart.

CONCLUSION

Nicorandil protects against stress-induced cell death in dystrophin-deficient cardiomyocytes and preserves cardiac function in the mdx mouse heart subjected to ischemia and reperfusion injury. This suggests a potential therapeutic role for nicorandil in dystrophin-deficient cardiomyopathy.

Effect of nicorandil in patients with heart failure: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

It is unclear whether nicorandil, a metabolic therapeutic drug, can be applied clinically to therapy of heart failure (HF). This meta-analysis evaluated therapeutic effects of nicorandil on HF patients.

EXPERIMENTAL APPROACH

We performed a systematic review and meta-analysis of published studies evaluating effect of nicorandil on HF patients. Studies were stratified according to controlled versus uncontrolled designs and analyzed using random-effects meta-analysis models.

KEY RESULTS

We identified a total of 20 studies with a total of 1222 patients. In five randomized controlled studies, nicorandil treatment resulted in reduction in all-cause mortality and hospitalization for cardiac causes (HR: 0.35, P < 0.001) and improved cardiac pump function (SMD: 0.31, P = 0.02). In 15 observational studies, nicorandil therapy increases cardiac pump function (SMD: 0.75, P < 0.001), improves NYHA functional class (WMD: -1.33, P < 0.001), decreases PCWP (WMD: -6.86 mm Hg, P < 0.001), and pulmonary arterial pressure (SMD: -0.84, P < 0.001).

CONCLUSIONS AND IMPLICATIONS

The use of nicorandil in HF patients exerts substantial beneficial effects, suggesting that it may be an additional therapeutic agent for HF.

Sodium tanshinone IIA silate inhibits oxygen-glucose deprivation/recovery-induced cardiomyocyte apoptosis via suppression of the NF-κB/TNF-α pathway

BACKGROUND AND PURPOSE

Inhibition of apoptosis may attenuate the irreversible injury associated with reperfusion. In the current study, we focused on the cytoprotective effects and the underlying mechanism of sodium tanshinone IIA silate (STS) against damage induced by oxygen-glucose deprivation/recovery (OGD/R). in H9c2 cardiomyocytes and the underlying mechanisms.

EXPERIMENTAL APPROACH

We used a model of cardiac ischaemia/reperfusion, OGD/R in H9c2 cardiomyocytes, to assess the cardioprotective effects of STS. Apoptosis of cells was measured with Hoechst 33342-based fluorescence microscopy, and annexin V-FITC-based flow cytometry. Caspase-3 and caspase-8 activities and mitochondrial membrane potential were also measured using commercial kits. TNF-α in the cell culture supernatant fractions were measured with sandwich elisa, and protein levels assayed using Western blot.

KEY RESULTS

STS inhibited OGD/R-induced apoptosis by suppressing JNK-mediated activation of NF-κB, TNF-α expression, activation of caspase-3 and caspase-8 and the Bax/Bcl-2 ratio. Additionally, positive feedback between NF-κB and TNF-α and amplification of TNF-α were inhibited, suggesting that STS plays a protective role against apoptosis in cardiomyocytes, even upon activation of pro-inflammatory cytokines. Interestingly, the cytoprotective effects of STS on OGD/R-induced apoptosis and promotion of cell survival were attenuated after inhibition of PI3K.

CONCLUSION AND IMPLICATIONS

The inhibitory effects of STS on TNF-α and positive feedback signalling of the NF-κB/TNF-α pathways may play important roles in myocardial protection against ischaemia/reperfusion. These protective effects of STS are mediated by suppressing JNK activity through activation of the PI3K-Akt pathway.

Ulceration of the nasal dorsum: a rare cause?

INTRODUCTION

Non-healing ulcers can be caused by a number of conditions, including vascular disease, diabetes, malignancy and some infections. Drug-related ulcers are rare, and a high index of clinical suspicion is required for diagnosis, in parallel with exclusion of more sinister underlying causes.

CASE REPORT

We present a patient with a complex medical background, who had a 10-week history of a non-healing ulcer on his nasal bridge. Inflammatory, autoimmune and malignant causes for the ulcer were excluded by histopathology.

CONCLUSION

Nicorandil was deemed to be the most likely cause for the patient's ulcer. Nicorandil is an anti-anginal medication known to cause oral ulceration and skin lesions in the perianal and peristomal regions and around surgical wounds. However, there are no previously reported cases of facial ulcers. The ulcer required surgical debridement and healed completely within six months, following discontinuation of nicorandil. This case highlights the importance of having a high index of clinical suspicion regarding non-healing ulcers, and of considering drugs as an aetiological factor, especially in patients with a complex medical background who are taking numerous medications.

ATP-sensitive potassium (K(ATP)) channel openers diazoxide and nicorandil lower intraocular pressure in vivo

PURPOSE

To evaluate the expression of ATP-sensitive potassium (K(ATP)) channel subunits and study the effect of K(ATP) channel openers diazoxide and nicorandil on intraocular pressure (IOP) in an in vivo mouse model.

METHODS

Expression of K(ATP) channel subunits in normal C57BL/6 mouse eyes was studied by immunohistochemistry and confocal microscopy. Wild-type C57BL/6 mice were treated with K(ATP) channel openers diazoxide (n = 10) and nicorandil (n = 10) for 14 days. Similar treatments with diazoxide were performed on K(ir)6.2((-/-)) mice (n = 10). IOP was recorded with a handheld tonometer 1 hour, 4 hours, and 23 hours following daily treatment. Posttreatment histology was examined by light and transmission electron microscopy.

RESULTS

The K(ATP) channel subunits SUR2B, K(ir)6.1, and K(ir)6.2 were identified in all tissues within mouse eyes. Treatment with diazoxide in wild-type mice decreased IOP by 21.5 ± 3.2% with an absolute IOP reduction of 3.9 ± 0.6 mm Hg (P = 0.002). Nicorandil also decreased IOP (18.9 ± 1.8%) with an absolute IOP reduction of 3.4 ± 0.4 mm Hg (P = 0.002). Treatment with diazoxide in K(ir)6.2((-/-)) mice had no effect on IOP. No morphological abnormalities were observed in diazoxide- or nicorandil-treated eyes.

CONCLUSIONS

K(ATP) channel openers diazoxide and nicorandil are effective regulators of IOP in mouse eyes. K(ir)6.2 appears to be a major K(ATP) channel subunit through which IOP is lowered following treatment with diazoxide.

Nicorandil inhibits hypoxia-induced apoptosis in human pulmonary artery endothelial cells through activation of mitoKATP and regulation of eNOS and the NF-κB pathway

Apoptosis of human pulmonary artery endothelial cells (HPAECs) is the initial step and triggering event for pulmonary hypertension (PH). However, little is known about the actions of nicorandil on HPAECs in vitro. In the present study, we investigated the anti-apoptotic effect of nicorandil on HPAECs exposed to hypoxia, and explored the underlying mechanism(s) of action. Cell viability was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Annexin V and propidium iodide staining, and Hoechst 33342 staining assay were employed to detect apoptosis. In addition, the protein expression of Bax, Bcl-2, caspase-9 and -3, endothelial nitric oxide synthase (eNOS), nuclear factor-κB (NF-κB) and IκBα were determined by western blotting to investigate the possible mechanisms. We found that exposure to hypoxia for 24 h significantly decreased cell viability and increased cell apoptosis. Pretreatment with nicorandil (100 µM) effectively abolished the influence of hypoxia on HPAECs. However, these protective effects of nicorandil were significantly inhibited by an antagonist of mitochondrial adenosine triphosphate-sensitive potassium (mitoKATP) channels, 5-hydroxydecanoate (5-HD, 500 µM), and by an eNOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME, 300 µM). We further observed that nicorandil could upregulate the decreased protein expression of eNOS and IκBα, and downregulate the increased protein expression of NF-κB, induced by hypoxia. In addition, nicorandil inhibited the enhancement of caspase-3 and -9 expression, and the increase in the Bax/Bcl-2 expression ratio, induced by hypoxia. However, these effects were also abolished by 5-HD and L-NAME. Collectively, these findings suggest that nicorandil inhibits hypoxia-induced apoptosis of HPAECs through activation of mitoKATP channels and increased eNOS expression, which in turn inhibits the NF-κB pathway and the mitochondrial apoptotic pathway.

Role of complement and perspectives for intervention in ischemia-reperfusion damage

Reperfusion of an organ following prolonged ischemia instigates the pro-inflammatory and pro-coagulant response of ischemia / reperfusion (IR) injury. IR injury is a wide-spread pathology, observed in many clinically relevant situations, including myocardial infarction, stroke, organ transplantation, sepsis and shock, and cardiovascular surgery on cardiopulmonary bypass. Activation of the classical, alternative, and lectin complement pathways and the generation of the anaphylatoxins C3a and C5a lead to recruitment of polymorphonuclear leukocytes, generation of radical oxygen species, up-regulation of adhesion molecules on the endothelium and platelets, and induction of cytokine release. Generalized or pathway-specific complement inhibition using protein-based drugs or low-molecular-weight inhibitors has been shown to significantly reduce tissue injury and improve outcome in numerous in-vitro, ex-vivo, and in-vivo models. Despite the obvious benefits in experimental research, only few complement inhibitors, including C1-esterase inhibitor, anti-C5 antibody, and soluble complement receptor 1, have made it into clinical trials of IR injury. The results are mixed, and the next objectives should be to combine knowledge and experience obtained in the past from animal models and channel future work to translate this into clinical trials in surgical and interventional reperfusion therapy as well as organ transplantation.

Nicorandil prevents endothelial dysfunction due to antioxidative effects via normalisation of NADPH oxidase and nitric oxide synthase in streptozotocin diabetic rats

Background

Nicorandil, an anti-angina agent, reportedly improves outcomes even in angina patients with diabetes. However, the precise mechanism underlying the beneficial effect of nicorandil on diabetic patients has not been examined. We investigated the protective effect of nicorandil on endothelial function in diabetic rats because endothelial dysfunction is a major risk factor for cardiovascular disease in diabetes.

Methods

Male Sprague-Dawley rats (6 weeks old) were intraperitoneally injected with streptozotocin (STZ, 40 mg/kg, once a day for 3 days) to induce diabetes. Nicorandil (15 mg/kg/day) and tempol (20 mg/kg/day, superoxide dismutase mimetic) were administered in drinking water for one week, starting 3 weeks after STZ injection. Endothelial function was evaluated by measuring flow-mediated dilation (FMD) in the femoral arteries of anaesthetised rats. Cultured human coronary artery endothelial cells (HCAECs) were treated with high glucose (35.6 mM, 24 h) and reactive oxygen species (ROS) production with or without L-NAME (300 μM), apocynin (100 μM) or nicorandil (100 μM) was measured using fluorescent probes.

Results

Endothelial function as evaluated by FMD was significantly reduced in diabetic as compared with normal rats (diabetes, 9.7 ± 1.4%; normal, 19.5 ± 1.7%; n = 6-7). There was a 2.4-fold increase in p47^phox expression, a subunit of NADPH oxidase, and a 1.8-fold increase in total eNOS expression in diabetic rat femoral arteries. Nicorandil and tempol significantly improved FMD in diabetic rats (nicorandil, 17.7 ± 2.6%; tempol, 13.3 ± 1.4%; n = 6). Nicorandil significantly inhibited the increased expressions of p47^phox and total eNOS in diabetic rat femoral arteries. Furthermore, nicorandil significantly inhibited the decreased expression of GTP cyclohydrolase I and the decreased dimer/monomer ratio of eNOS. ROS production in HCAECs was increased by high-glucose treatment, which was prevented by L-NAME and nicorandil suggesting that eNOS itself might serve as a superoxide source under high-glucose conditions and that nicorandil might prevent ROS production from eNOS.

Conclusions

These results suggest that nicorandil improved diabetes-induced endothelial dysfunction through antioxidative effects by inhibiting NADPH oxidase and eNOS uncoupling.

ATP-sensitive potassium (KATP) channel activation decreases intraocular pressure in the anterior chamber of the eye

PURPOSE. ATP-sensitive potassium channel (K(ATP)) openers target key cellular events, many of which have been implicated in glaucoma. The authors sought to determine whether K(ATP) channel openers influence outflow facility in human anterior segment culture and intraocular pressure (IOP) in vivo. METHODS. Anterior segments from human eyes were placed in perfusion organ culture and treated with the K(ATP) channel openers diazoxide, nicorandil, and P1075 or the K(ATP) channel closer glyburide (glibenclamide). The presence, functionality, and specificity of K(ATP) channels were determined by RT-PCR, immunohistochemistry, and inside-out patch clamp in human trabecular meshwork (TM) tissue or primary cultures of normal human trabecular meshwork (NTM) cells. The effect of diazoxide on IOP in anesthetized Brown Norway rats was measured with a rebound tonometer. RESULTS. K(ATP) channel openers increased outflow facility in human anterior segments (0.14 ± 0.02 to 0.26 ± 0.09 μL/min/mm Hg; P < 0.001) compared with fellow control eyes (0.22 ± 0.11 to 0.21 ± 0.11 μL/min/mm Hg; P > 0.5). The effect was reversible, with outflow facility returning to baseline after drug removal. The addition of glyburide inhibited diazoxide from increasing outflow facility. Electrophysiology confirmed the presence and specificity of functional K(ATP) channels. K(ATP) channel subunits K(ir)6.1, K(ir)6.2, SUR2A, and SUR2B were expressed in TM and NTM cells. In vivo, diazoxide significantly lowered IOP in Brown Norway rats. CONCLUSIONS. Functional K(ATP) channels are present in the trabecular meshwork. When activated by K(ATP) channel openers, these channels increase outflow facility through the trabecular outflow pathway in human anterior segment organ culture and decrease IOP in Brown Norway rat eyes.

Chronic lithium administration ameliorates 2,4,6-trinitrobenzene sulfonic acid-induced colitis in rats; potential role for adenosine triphosphate sensitive potassium channels

BACKGROUND AND AIM

Inflammatory bowel disease (IBD) is a multi-factorial disease with an unknown etiology characterized by oxidative stress, leukocyte infiltration and a rise in inflammatory cytokines. This study was conducted to investigate lithium in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced chronic model of experimental IBD, and the contribution of potassium channels as a possible underlying mechanism.

METHODS

Experimental IBD was induced in rats by a single colonic administration of 10 mg of TNBS. Lithium, Glibenclamide (a potassium channel blocker), Lithium + Glibenclamide, Cromakalim or Lithium+Glibenclamide+ Cromakalim were given twice daily for 7 successive days. At the end of the experiment, macroscopic and histopathologic scores, colonic malondialdehyde (MDA), tumor necrosis factor-α (TNF-α) level, and myeloperoxidase (MPO) activity as well as plasma lithium level were assessed.

RESULTS

Both macroscopic and histological features of colonic injury were markedly ameliorated by lithium. Likewise, the elevated amounts of MPO and MDA were diminished as well as those of TNF-α (P < 0.05). Glibenclamide reversed the effect of lithium on these markers, Addition of cromakalim abrogated the effects mediated by glibenclamide and markedly decreased MPO activity, MDA level and TNF-α content (P < 0.0.05). Macroscopic and microscopic scores and biochemical markers were significantly decreased in Cromakalim-treated animals. No significant difference was observed between TNBS and Glibenclamide groups.

CONCLUSION

Lithium exerts prominent anti-inflammatory effects on TNBS-induced colitis in rats. Potassium channels contribute to these beneficial properties.

Suppressive effects of sivelestat on interleukin 8 and TNF-α production from LPS-stimulated granulocytes in whole blood culture

PURPOSE

The goal of the study was to examine the effects of sivelestat sodium hydrate (sivelestat), a neutrophil elastase inhibitor, on production of cytokines in granulocytes and monocytes, using flow cytometry after cytokine staining in whole blood culture.

METHODS

Blood samples were collected from healthy volunteers. Vehicle (control group), lipopolysaccharide (LPS) (LPS group), or LPS + sivelestat (sivelestat group) were added to the whole blood, followed by addition of a protein transport inhibitor in each group. After incubation, staining for cytokines retained in the cells was performed by addition of an anti-interleukin 8 (IL-8) or anti-tumor necrosis factor-α (TNF-α) antibody. The cells were then analyzed using flow cytometry.

RESULTS

Granulocytic production of IL-8 induced by 1 ng/ml LPS was significantly (P < 0.05) inhibited by treatment with 1 μg/ml sivelestat, and upregulation of IL-8 by 10 ng/ml LPS was also significantly (P < 0.05) suppressed by 1 and 10 μg/ml sivelestat. Addition of 10 or 100 μg/ml sivelestat significantly (P < 0.05) inhibited the production of TNF-α from granulocytes induced by 10 ng/ml LPS. Sivelestat did not significantly inhibit LPS-induced monocytic production of TNF-α and IL-8.

CONCLUSION

Suppression of granulocytic production of IL-8 and TNF-α by sivelestat suggests that this drug may be useful for treatment of morbid conditions involving IL-8 and TNF-α at onset.

Nicorandil ulcer: moves beyond the mucosa

The management of wounds is a specialty in its infancy. Success requires more than the use of dressings. All wounds require a diagnosis, a point well illustrated by the management of these cases which depended solely on stopping nicorandil.

Role of nuclear factor kappaB in cardiovascular health and disease

Cardiovascular pathologies are still the primary cause of death worldwide. The molecular mechanisms behind these pathologies have not been fully elucidated. Unravelling them will bring us closer to therapeutic strategies to prevent or treat cardiovascular disease. One of the major transcription factors that has been linked to both cardiovascular health and disease is NF-kappaB (nuclear factor kappaB). The NF-kappaB family controls multiple processes, including immunity, inflammation, cell survival, differentiation and proliferation, and regulates cellular responses to stress, hypoxia, stretch and ischaemia. It is therefore not surprising that NF-kappaB has been shown to influence numerous cardiovascular diseases including atherosclerosis, myocardial ischaemia/reperfusion injury, ischaemic preconditioning, vein graft disease, cardiac hypertrophy and heart failure. The function of NF-kappaB is largely dictated by the genes that it targets for transcription and varies according to stimulus and cell type. Thus NF-kappaB has divergent functions and can protect cardiovascular tissues from injury or contribute to pathogenesis depending on the cellular and physiological context. The present review will focus on recent studies on the function of NF-kappaB in the cardiovascular system.

Patents related to therapeutic activation of K(ATP) and K(2P) potassium channels for neuroprotection: ischemic/hypoxic/anoxic injury and general anesthetics

BACKGROUND

Mechanisms of neuroprotection encompass energy deficits in brain arising from insufficient oxygen and glucose levels following respiratory failure; ischemia or stroke, which produce metabolic stresses that lead to unconsciousness and seizures; and the effects of general anesthetics. Foremost among those K(+) channels viewed as important for neuroprotection are ATP-sensitive (K(ATP)) channels, which belong to the family of inwardly rectifying K(+) channels (K(ir)) and contain a sulfonylurea subunit (SUR1 or SUR2) combined with either K(ir)6.1 (KCNJ8) or K(ir)6.2 (KCNJ11) channel pore-forming alpha-subunits, and various members of the tandem two-pore or background (K(2P)) K(+) channel family, including K(2P)1.1 (KCNK1 or TWIK1), K(2P)2.1 (KCNK2 or TREK/TREK1), K(2P)3.1 (KCNK3 or TASK), K(2P)4.1 (KCNK4 or TRAAK), and K(2P)10.1 (KCNK10 or TREK2).

OBJECTIVES

This review covers patents and patent applications related to inventions of therapeutics, compound screening methods and diagnostics, including K(ATP) channel openers and blockers, as well as K(ATP) and K(2P) nucleic/amino acid sequences and proteins, vectors, transformed cells and transgenic animals. Although the focus of this patent review is on brain and neuroprotection, patents covering inventions of K(ATP) channel openers for cardioprotection, diabetes mellitus and obesity, where relevant, are addressed.

RESULTS/CONCLUSIONS

Overall, an important emerging therapeutic mechanism underlying neuroprotection is activation/opening of K(ATP) and K(2P) channels. To this end substantial progress has been made in identifying and patenting agents that target K(ATP) channels. However, current K(2P) channels patents encompass compound screening and diagnostics methodologies, reflecting an earlier 'discovery' stage (target identification/validation) than K(ATP) in the drug development pipeline; this reveals a wide-open field for the discovery and development of K(2P)-targeting compounds.

Effects of long-term nicorandil administration on endothelial function, inflammation, and oxidative stress in patients without coronary artery disease

Long-term administration of nicorandil has been shown to improve outcomes through cardioprotective effects in patients with coronary artery disease. To identify the mechanisms responsible for these effects, this study examined the impact of long-term nicorandil administration on endothelial function, systemic inflammatory markers, and oxidative stress in patients with cardiovascular risk factors. Fifty-three patients were assigned to receive either nicorandil therapy (15 mg/day; n = 26) (nicorandil group) or usual care (n = 27) (nonnicorandil group). All study participants underwent flow-mediated vasodilatation (FMD) of the brachial artery 1 month before treatment, just before treatment, and at 3, 6, and 12 months following treatment. At identical time points, serum levels of malondialdehyde-modified low-density lipoprotein (MDA-LDL) and high-sensitivity C-reactive protein (hs-CRP) were collected. Compared with the nonnicorandil group, the nicorandil group demonstrated significantly increased FMD at 12 months, a finding not replicated for endothelium-independent vasodilatation with nitroglycerine. Analysis of biochemical markers revealed significantly reduced MAD-LDL levels in the nicorandil group at 12 months, as compared to slightly increased MAD-LDL levels in the nonnicorandil group. Significant reductions in hs-CRP levels were also noted at 6 and 12 months in the nicorandil group, while no change was found in the nonnicorandil group. Results demonstrated that long-term nicorandil therapy is associated with gradual improvements in endothelial function. Our findings also suggest that nicorandil treatment may result in cardiovascular protection through pleiotropic effects including reductions in oxidative injury and systemic inflammation.

Novel bisindolylmaleimide derivative inhibits mitochondrial permeability transition pore and protects the heart from reperfusion injury

Despite major advances in treating patients with coronary heart disease, reperfusion injury is still considered to be a major problem, especially in surgical settings. Here, we demonstrate the protective effects of a novel bisindolylmaleimide derivative, MS1 (2-[1-(3-aminopropyl)indol-3-yl]-3-(indol-3-yl)-N-methylmaleimide), against reperfusion injury of the heart. After anesthesia and artificial ventilation, Wistar rats were subjected to 30 min of left coronary artery occlusion followed by 120 min of reperfusion with or without treating the rats with MS1 (2.25 mumol.L-1.kg-1) before left coronary artery occlusion. Compared with the untreated hearts, MS1 treatment significantly reduced myocardial infarct size (35.1% +/- 3% vs. 75.5% +/- 5%, p < 0.001), reduced prevalence of apoptotic cells (2.6% +/- 0.5% vs. 12.2% +/- 2.1%, p < 0.001), prevented mitochondrial swelling and cytochrome c release, inhibited downregulation of antiapoptotic protein Bcl-2 expression, and suppressed caspase-3 activation. In contrast, pretreatment with atractyloside, a mitochondrial permeability transition pore opener, abolished the protective effects of MS1. In conclusion, MS1 inhibits pathologic opening of permeability transition pores and protects the heart against reperfusion injury and pathologic apoptosis.

Preconditioning in humans

Brief ischemia to the myocardium initiates a cascade of biochemical events in cardiac myocytes that protects the heart muscle during subsequent ischemic insults. This phenomenon is called ischemic preconditioning. If an acute myocardial infarction is preceded by preinfarction angina, it results in smaller infarction size, fewer cardiac arrhythmias, and better-left ventricular function. During coronary intervention, brief balloon inflation protects the heart during subsequent inflations. Patients vary in the degree of preconditioning and those patients who have the ability to demonstrate a significant preconditioning effect will have lesser incidence of subsequent cardiac events. Preconditioning protects the myocardium during coronary artery bypass surgery, particularly in the off-pump procedure, yet the thoracic surgery community has not universally adopted this technique.

Preoperative plasma levels of soluble tumor necrosis factor receptor type I (sTNF-RI) predicts adverse events in cardiac surgery

OBJECTIVE

The objective was to estimate the sTNF-RI preoperative measure in the identification of patients with bad outcome and death.

METHODS

We assessed prospectively sixty-two patients submitted electively to myocardial revascularization with ECC or heart valve surgery. The sTNF-RI levels were determined by the Sandwich-Type ELISA method before anesthetic induction. Clinical, surgical characteristics and sTNF-RI levels were compared among patients with good (group I, n=46) or bad outcome (group II, n=16--length of stay in the ICU for over 72 h or death).

RESULTS

No difference was found between the verified mortality (6.4%) and the predicted by EuroSCORE (3.0%), p=0.48. The sTNF-RI levels were higher in group II (1322) than group I (748) p=0.009 (levels >954, 69% sensitivity and 70% specificity for good outcome, 44% positive predicted value and 85% negative). The sTNF-RI levels were higher in patients who died (1556) versus (759) p=0.029, (levels >1230, 79% sensitivity, 75% specificity, 20% positive predicted value and 98% negative). In the multivariate logistic regression model sTNF-RI (OR=1.002, IC95% 1.000-1.005, p=0.014) and age (OR=1.083, IC95% 1.010-1.161, p=0.025) were independently related to the risk of bad outcome.

CONCLUSIONS

Basal levels of sTNF-RI yield prognostic information in patients who undergo heart surgery.