The Role of Peroxisome Proliferator-Activated Receptor γ in Mediating Cardioprotection Against Ischemia/Reperfusion Injury

Effect of Cold Adaptation on the State of Cardiovascular System and Cardiac Tolerance to Ischemia/Reperfusion Injury

Despite the unconditional success achieved in the treatment and prevention of AMI over the past 40 years, mortality in this disease remains high. Hence, it is necessary to develop novel drugs with mechanism of action different from those currently used in clinical practices. Studying the molecular mechanisms involved in the cardioprotective effect of adapting to cold could contribute to the development of drugs that increase cardiac tolerance to the impact of ischemia/reperfusion. An analysis of the published data shows that the long-term human stay in the Far North contributes to the occurrence of cardiovascular diseases. At the same time, chronic and continuous exposure to cold increases tolerance of the rat heart to ischemia/ reperfusion. It has been demonstrated that the cardioprotective effect of cold adaptation depends on the activation of ROS production, stimulation of the β2-adrenergic receptor and protein kinase C, MPT pore closing, and KATP channel.

CB2 Cannabinoid Receptor as a Potential Target in Myocardial Infarction: Exploration of Molecular Pathogenesis and Therapeutic Strategies

The lipid endocannabinoid system has recently emerged as a novel therapeutic target for several inflammatory and tissue-damaging diseases, including those affecting the cardiovascular system. The primary targets of cannabinoids are cannabinoid type 1 (CB1) and 2 (CB2) receptors. The CB2 receptor is expressed in the cardiomyocytes. While the pathological changes in the myocardium upregulate the CB2 receptor, genetic deletion of the receptor aggravates the changes. The CB2 receptor plays a crucial role in attenuating the advancement of myocardial infarction (MI)-associated pathological changes in the myocardium. Activation of CB2 receptors exerts cardioprotection in MI via numerous molecular pathways. For instance, delta-9-tetrahydrocannabinol attenuated the progression of MI via modulation of the CB2 receptor-dependent anti-inflammatory mechanisms, including suppression of pro-inflammatory cytokines like IL-6, TNF-α, and IL-1β. Through similar mechanisms, natural and synthetic CB2 receptor ligands repair myocardial tissue damage. This review aims to offer an in-depth discussion on the ameliorative potential of CB2 receptors in myocardial injuries induced by a variety of pathogenic mechanisms. Further, the modulation of autophagy, TGF-β/Smad3 signaling, MPTP opening, and ROS production are discussed. The molecular correlation of CB2 receptors with cardiac injury markers, such as troponin I, LDH1, and CK-MB, is explored. Special attention has been paid to novel insights into the potential therapeutic implications of CB2 receptor activation in MI.

Didymin Alleviates Cerebral Ischemia-Reperfusion Injury by Activating the PPAR Signaling Pathway

PURPOSE

Cerebral ischemia-reperfusion (IR) injury is a severe secondary injury induced by reperfusion after stroke. Didymin has been reported to have a protective effect on intracerebral hemorrhage. However, the underlying mechanism of didymin on regulating cerebral IR injury remains largely unknown.

MATERIALS AND METHODS

A rat cerebral IR model and oxygen-glucose deprivation/reperfusion (OGD/R) model in PC12 cells were established. Hematoxylin and eosin (H&E) was used to detect the pathological changes in brain tissues, and TUNEL staining was performed to detect apoptosis of brain tissues. MTT and flow cytometry were used to measure the viability and apoptosis of PC12 cells. QRT-PCR and western blot were used to detect inflammation cytokines in PC12 cells. Western blot was used to measure the expression of PPAR-γ, RXRA, Bax, c-caspase-3, and Bcl-2.

RESULTS

Didymin pretreatment decreased apoptotic rates, reduced levels of Bax and c-caspase-3, and increased Bcl-2 level in vivo and in vitro. Additionally, didymin pretreatment increased viability and decreased the inflammation levels [interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and monocyte chemotactic protein (MCP)-1] of OGD/R treated PC12 cells. Moreover, didymin activated the peroxisome proliferator-activated receptors (PPAR) signaling pathway and increased the expression of PPAR-γ and RXRA in OGD/R treated PC12 cells. Inhibition of PPAR-γ eliminated the protective effect of didymin on OGD/R treated cells.

CONCLUSION

Didymin protected neuron cells against IR injury in vitro and in vivo by activation of the PPAR pathway. Didymin may be a candidate drug for IR treatment.

Role of Oxidative Stress in Cardiac Dysfunction and Subcellular Defects Due to Ischemia-Reperfusion Injury

Ischemia-reperfusion (I/R) injury is well-known to be associated with impaired cardiac function, massive arrhythmias, marked alterations in cardiac metabolism and irreversible ultrastructural changes in the heart. Two major mechanisms namely oxidative stress and intracellular Ca²⁺-overload are considered to explain I/R-induced injury to the heart. However, it is becoming apparent that oxidative stress is the most critical pathogenic factor because it produces myocardial abnormalities directly or indirectly for the occurrence of cardiac damage. Furthermore, I/R injury has been shown to generate oxidative stress by promoting the formation of different reactive oxygen species due to defects in mitochondrial function and depressions in both endogenous antioxidant levels as well as regulatory antioxidative defense systems. It has also been demonstrated to adversely affect a wide variety of metabolic pathways and targets in cardiomyocytes, various resident structures in myocardial interstitium, as well as circulating neutrophils and leukocytes. These I/R-induced alterations in addition to myocardial inflammation may cause cell death, fibrosis, inflammation, Ca²⁺-handling abnormalities, activation of proteases and phospholipases, as well as subcellular remodeling and depletion of energy stores in the heart. Analysis of results from isolated hearts perfused with or without some antioxidant treatments before subjecting to I/R injury has indicated that cardiac dysfunction is associated with the development of oxidative stress, intracellular Ca²⁺-overload and protease activation. In addition, changes in the sarcolemma and sarcoplasmic reticulum Ca²⁺-handling, mitochondrial oxidative phosphorylation as well as myofibrillar Ca²⁺-ATPase activities in I/R hearts were attenuated by pretreatment with antioxidants. The I/R-induced alterations in cardiac function were simulated upon perfusing the hearts with oxyradical generating system or oxidant. These observations support the view that oxidative stress may be intimately involved in inducing intracellular Ca²⁺-overload, protease activation, subcellular remodeling, and cardiac dysfunction as a consequence of I/R injury to the heart.

Untangling the Cooperative Role of Nuclear Receptors in Cardiovascular Physiology and Disease

The heart is the first organ to acquire its physiological function during development, enabling it to supply the organism with oxygen and nutrients. Given this early commitment, cardiomyocytes were traditionally considered transcriptionally stable cells fully committed to contractile function. However, growing evidence suggests that the maintenance of cardiac function in health and disease depends on transcriptional and epigenetic regulation. Several studies have revealed that the complex transcriptional alterations underlying cardiovascular disease (CVD) manifestations such as myocardial infarction and hypertrophy is mediated by cardiac retinoid X receptors (RXR) and their partners. RXRs are members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors and drive essential biological processes such as ion handling, mitochondrial biogenesis, and glucose and lipid metabolism. RXRs are thus attractive molecular targets for the development of effective pharmacological strategies for CVD treatment and prevention. In this review, we summarize current knowledge of RXR partnership biology in cardiac homeostasis and disease, providing an up-to-date view of the molecular mechanisms and cellular pathways that sustain cardiomyocyte physiology.

Interaction of Obesity and Hypertension on Cardiac Metabolic Remodeling and Survival Following Myocardial Infarction

Background

Obesity and hypertension are risk factors for myocardial infarction (MI); however, their potential interactions on post‐MI outcomes are unclear. We examined interactions of obesity and hypertensionon post‐MI function, remodeling, metabolic changes, and recovery.

Methods and Results

Male and female C57BL/6J mice were provided standard chow or high‐fat/fructose diet for 8 weeks and then infused with angiotensin II for 2 weeks to induce hypertension. MI was then induced by surgical ligation of the left coronary artery for 7 days. Obesity alone did not cause cardiac injury or exacerbate hypertension‐induced cardiac dysfunction. After MI, however, obese‐normotensive mice had lower survival rates compared with chow‐fed mice (56% versus 89% males; 54% versus 75% females), which were further decreased by hypertension (29% males; and 35% females). Surviving obese‐normotensive males displayed less left ventricular dilation and pulmonary congestion compared with chow‐fed males after MI; hypertension reversed left ventricular dilation because of high‐fat/fructose diet and promoted significant pulmonary congestion compared with chow‐fed controls. Obese‐normotensive males displayed higher left ventricular α‐MHC (alpha‐myosin heavy chain) protein, phosphorylated Akt (protein kinase B) and AMPK (adenosine‐monophosphate activated kinase), PPAR‐γ (peroxisome proliferator activated receptor gamma), and plasma adiponectin levels after MI, indicating favorable contractile and metabolic changes. However, these favorable contractile and metabolic changes were attenuated by hypertension. Obese‐hypertensive males also had lower levels of collagen in the infarcted region, indicating decreased ability to promote an adaptive wound healing response to MI.

Conclusions

Obesity reduces post‐MI survival but is associated with improved post‐MI cardiac function and metabolism in surviving normotensive mice. When hypertension accompanies obesity, favorable metabolic pathways associated with obesity are attenuated and post‐MI cardiac function and remodeling are adversely impacted.

Cardioprotective effect of pioglitazone and curcumin against diabetic cardiomyopathy in type 1 diabetes mellitus: impact on CaMKII/NF-κB/TGF-β1 and PPAR-γ signaling pathway

Diabetic cardiomyopathy (DCM) is a leading cause of death in diabetic patients, which is currently without available specific treatment. This study aimed to investigate the potential protective effects of pioglitazone (Pio) and curcumin (Cur) against DCM in type 1 diabetes mellitus (T1DM), with pointing to their role on Ca+2/calmodulin-dependent protein kinase II (CaMKII) and peroxisome proliferator-activated receptor gamma (PPAR-γ) expression. Diabetes was induced in adult male Sprague Dawley rats by administration of single intraperitoneal injection of streptozotocin (STZ) (52.5 mg/kg). Diabetic rats were administered either Pio (20 mg/kg/day) or Cur (100 mg/kg/day) orally for 6 weeks. Treatment with Pio and/or Cur markedly reduced serum cardiac injury markers and lipid profile markers in diabetic animals. Additionally, Pio and/or Cur treatment mitigated oxidative stress and fibrosis in diabetic rats as evident from the significant suppression in myocardial lipid peroxidation and tumor growth factor beta 1 (TGF-β1) level, with concomitant significant elevation in total antioxidant capacity (TAC) and improvement in histopathological architecture of heart tissue. Pio/Cur treatment protocol accomplished its cardioprotective effect by depressing cardiac CaMKII/NF-κB signaling accompanied by enhancement in PPAR-γ expression. Conclusively, these findings demonstrated the therapeutic potential of Pio/Cur regimen in alleviating DCM in T1DM through modulation of CaMKII and PPAR-γ expression. Graphical Abstract.

Propofol ameliorates endotoxin‑induced myocardial cell injury by inhibiting inflammation and apoptosis via the PPARγ/HMGB1/NLRP3 axis

Endotoxin lipopolysaccharide (LPS) is one of the primary causes of myocardial injury. Propofol confers protective effects against LPS‑induced myocardial damage; however, the biological functions and mechanisms underlying propofol are not completely understood. The present study aimed to investigate the effects of propofol on LPS‑induced myocardial injury. Primary neonatal rat cardiomyocytes were treated with LPS to establish a myocardial injury model. LDH release in the culture media was measured using a LDH assay kit. The interactions between NLR family pyrin domain containing 3 (NLRP3), apoptosis‑associated speck‑like protein containing A CARD (ASC) and pro‑caspase‑1 were determined using a co‑immunoprecipitation assay. Cell viability was measured using an MTT assay, and the levels of cell apoptosis were determined using flow cytometry, JC‑1 staining (mitochondrial membrane potential) and caspase‑3 activity assays. The mRNA expression levels of TNF‑α, IL‑6, IL‑1β and IL‑18, and the protein expression levels of NLRP3, ASC, pro‑caspase‑1, caspase‑1 p10, pro‑IL‑1β, IL‑1β, pro‑IL‑18, IL‑18, high mobility group box‑1 (HMGB1) and peroxisome proliferator‑activated receptor γ (PPARγ) were analyzed using reverse transcription‑quantitative PCR and western blotting analyses, respectively. ELISAs were performed to measure the production of inflammatory mediators, including TNF‑α, IL‑6, IL‑1β and IL‑18. The present results demonstrated that pretreatment with propofol significantly attenuated LPS‑induced neonatal rat cardiomyocyte injury in a concentration‑ and time‑dependent manner. Propofol pretreatment also significantly inhibited LPS‑induced cardiomyocyte inflammation and apoptosis. The results suggested that propofol pretreatment inactivated HMGB1‑dependent NLRP3 inflammasome signaling, which involved PPARγ activation. Therefore, the results indicated that propofol reduced endotoxin‑induced cardiomyocyte injury by inhibiting inflammation and apoptosis via the PPARγ/HMGB1/NLRP3 axis, suggesting that propofol may serve as a potential therapeutic agent for septic myocardial damage.

Ficus carica L. Attenuates Denervated Skeletal Muscle Atrophy via PPARα/NF-κB Pathway

Treatment options for denervated skeletal muscle atrophy are limited, in part because the underlying molecular mechanisms are not well understood. Unlike previous transcriptomics studies conducted in rodent models of peripheral nerve injury, in the present study, we performed high-throughput sequencing with denervated atrophic biceps muscle and normal (non-denervated) sternocleidomastoid muscle samples obtained from four brachial plexus injury (BPI) patients. We also investigated whether Ficus carica L. (FCL.) extract can suppress denervated muscle atrophy in a mouse model, along with the mechanism of action. We identified 1471 genes that were differentially expressed between clinical specimens of atrophic and normal muscle, including 771 that were downregulated and 700 that were upregulated. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed that the differentially expressed genes were mainly enriched in the GO terms “structural constituent of muscle,” “Z disc,” “M band,” and “striated muscle contraction,” as well as “Cell adhesion molecules,” “Glycolysis/Gluconeogenesis,” “Peroxisome proliferator-activated receptor alpha (PPARα) signaling pathway,” and “P53 signaling pathway.” In experiments using mice, the reduction in wet weight and myofiber diameter in denervated muscle was improved by FCL. extract compared to saline administration, which was accompanied by downregulation of the proinflammatory cytokines interleukin (IL)-1β and IL-6. Moreover, although both denervated groups showed increased nuclear factor (NF)-κB activation and PPARα expression, the degree of NF-κB activation was lower while PPARα and inhibitor of NF-κB IκBα expression was higher in FCL. extract-treated mice. Thus, FCL. extract suppresses denervation-induced inflammation and attenuates muscle atrophy by enhancing PPARα expression and inhibiting NF-κB activation. These findings suggest that FCL. extract has therapeutic potential for preventing denervation-induced muscle atrophy caused by peripheral nerve injury or disease.

The Role of Natriuretic Peptides in the Regulation of Cardiac Tolerance to Ischemia/Reperfusion and Postinfarction Heart Remodeling

In the past 10 years, mortality from acute myocardial infarction has not decreased despite the widespread introduction of percutaneous coronary intervention. The reason for this situation is the absence in clinical practice of drugs capable of preventing reperfusion injury of the heart with high efficiency. In this regard, noteworthy natriuretic peptides (NPs) which have the infarct-limiting effect, prevent reperfusion cardiac injury, prevent adverse post-infarction remodeling of the heart. Atrial natriuretic peptide does not have the infarct-reducing effect in rats with alloxan-induced diabetes mellitus. NPs have the anti-apoptotic and anti-inflammatory effects. There is indirect evidence that NPs inhibit pyroptosis and autophagy. Published data indicate that NPs inhibit reactive oxygen species production in cardiomyocytes, aorta, heart, kidney and the endothelial cells. NPs can suppress aldosterone, angiotensin II, endothelin-1 synthesize and secretion. NPs inhibit the effects aldosterone, angiotensin II on the post-receptor level through intracellular signaling events. NPs activate guanylyl cyclase, protein kinase G and protein kinase A, and reduce phosphodiesterase 3 activity. NO-synthase and soluble guanylyl cyclase are involved in the cardioprotective effect of NPs. The cardioprotective effect of natriuretic peptides is mediated via activation of kinases (AMPK, PKC, PI3 K, ERK1/2, p70s6 k, Akt) and inhibition of glycogen synthase kinase 3β. The cardioprotective effect of NPs is mediated via sarcolemmal K_ATP channel and mitochondrial K_ATP channel opening. The cardioprotective effect of brain natriuretic peptide is mediated via MPT pore closing. The anti-fibrotic effect of NPs may be mediated through inhibition TGF-β1 expression. Natriuretic peptides can inhibit NF-κB activity and activate GATA. Hemeoxygenase-1 and peroxisome proliferator-activated receptor γ may be involved in the infarct-reducing effect of NPs. NPs exhibit the infarct-limiting effect in patients with acute myocardial infarction. NPs prevent post-infarction remodeling of the heart. To finally resolve the question of the feasibility of using NPs in AMI, a multicenter, randomized, blind, placebo-controlled study is needed to assess the effect of NPs on the mortality of patients after AMI.

Chrysin rescues rat myocardium from ischemia-reperfusion injury via PPAR-γ/Nrf2 activation

Pharmacological strategies aimed at co-activating peroxisome proliferator-activated receptor-gamma (PPAR-γ)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway have shown promising results in alleviating myocardial injury. The aim of the study was to evaluate the role of chrysin, a PPAR-γ agonist, in ischemia-reperfusion (IR)-induced myocardial infarction (MI) in rats and to explore the molecular mechanism driving this activity. To evaluate this hypothesis, chrysin (60 mg/kg, orally), PPAR-γ antagonist (GW9662, 1 mg/kg, intraperitoneally), or both were administered to rats for 28 days. On the 29th day, one-stage ligation of left anterior descending coronary artery for 45 min followed by 60 min of reperfusion was performed. Chrysin significantly decreased infarct size and improved cardiac functions following IR-induced MI. This improvement was corroborated by augmented PPAR-γ/Nrf2 expression as confirmed by immunohistochemistry and western blotting analysis. Chrysin exhibited strong anti-oxidant property as demonstrated by increased GSH and CAT levels and decreased 8-OHdG and TBARS levels. Our findings also imply that chrysin significantly inhibited inflammatory response as validated by decreased NF-κB, IKK-β, CRP, TNF-α and MPO levels. In addition, chrysin decreased TUNEL/DAPI positivity, a marker of apoptotic response and normalized cardiac injury markers. The histopathological and ultrastructural analysis further supported the functional and biochemical outcomes, showing preserved myocardial architecture. Intriguingly, co-administration with GW9662 significantly diminished the cardioprotective effect of chrysin as demonstrated by depressed myocardial function, decreased PPAR-γ/Nrf2 expression and increased oxidative stress. In conclusion, the present study demonstrates that co-activation of PPAR-γ/Nrf2 by chrysin may be crucial for its cardioprotective effect.

PPARγ activation mitigates mechanical allodynia in paclitaxel-induced neuropathic pain via induction of Nrf2/HO-1 signaling pathway

Paclitaxel-induced neuropathic pain (PINP) is a dose-limiting side effect and is refractory to widely used analgesic drugs. Previous studies have demonstrated a protective role of peroxisome proliferator-activated receptor gama (PPARγ) in neuropathic pain. However, whether PPARγ activation could alleviate PINP remains to be elucidated. Our previous study has validated the analgesic effect of oltipraz, an nuclear factor erythroid-2 related factor 2 (Nrf2) activator, in a rat model of PINP. In this study, we tested the hypothesis that rosiglitazone, a selective agonist of PPARγ, could attenuate PINP through induction of Nrf2/heme oxygenase-1 (HO-1) signaling pathway. Paclitaxel was injected intraperitoneally on four alternate days to induce neuropathic pain. Paw withdrawal threshold was used to evaluate mechanical allodynia. Western blot and immunofluorescence were used to examine the expression and distribution of PPARγ, Nrf2 and HO-1 in the spinal cord. Our results showed that rosiglitazone attenuated established PINP and delayed the onset of PINP via activation of PPARγ, which were reversed by PPARγ antagonist GW9662. Moreover, rosiglitazone inhibited downregulation of PPARγ in the spinal cord of PINP rats. Furthermore, the analgesic effect of rosiglitazone against PINP was abolished by trigonelline, an Nrf2 inhibitor. Finally, rosiglitazone significantly increased expression of Nrf2 and HO-1 in the spinal cord of PINP rats. Collectively, these results indicated that PPARγ activation might mitigate PINP through activating spinal Nrf2/HO-1 signaling pathway. Our results may provide an alternative option for PINP patients.

Carbon monoxide-releasing molecule-3: Amelioration of renal ischemia reperfusion injury in a rat model

Purpose

Despite the role of carbon monoxide in ameliorating ischemia-reperfusion injury (IRI), its use in the clinical setting is restricted owing to its toxicity. Herein, we investigated the in vivo effects of carbon monoxide–releasing molecule-3 (CORM-3) on IRI.

Materials and Methods

Fifteen rats were equally and randomly divided into three groups: sham (right nephrectomy), control (right nephrectomy and left renal ischemia), and CORM-3 (right nephrectomy and CORM-3 injection before left renal ischemia). Kidney tissues and blood samples collected from sacrificed rats were evaluated to determine the renoprotective effect and mechanism of CORM-3.

Results

Concentrations of serum creatinine and kidney injury molecule-1 in the CORM-3 group were significantly lower than in the control group after 75 minutes of IRI (1.2 vs. 2.4 mg/dL, p=0.01, and 292 vs. 550 pg/mL, p<0.001, respectively). Furthermore, the CORM-3 group exhibited a higher portion of normal tubules and glomeruli. TUNEL staining revealed fewer apoptotic renal tubular cells in the CORM-3 group than in the control group. The expression of 960 genes in the CORM-3 group was also altered. Pretreatment with CORM-3 before renal IRI produced a significant renoprotective effect. Fifteen of the altered genes were found to be involved in the peroxisome proliferator-activated receptors signaling pathway, and the difference in the expression of these genes between the CORM-3 and control groups was statistically significant (p<0.001).

Conclusions

CORM-3 ameliorates IRI by decreasing apoptosis and may be a novel strategy for protection against renal warm IRI.

Macrophage Activities in Myocardial Infarction and Heart Failure

Heart diseases remain the major cause of death worldwide. Advances in pharmacological and biomedical management have resulted in an increasing proportion of patients surviving acute heart failure (HF). However, many survivors of HF in the early stages end up increasing the disease to chronic HF (CHF). HF is an established frequent complication of myocardial infarction (MI), and numerous influences including persistent myocardial ischemia, shocked myocardium, ventricular remodeling, infarct size, and mechanical impairments, as well as hibernating myocardium trigger the development of left ventricular systolic dysfunction following MI. Macrophage population is active in inflammatory process, yet the clear understanding of the causative roles for these macrophage cells in HF development and progression is actually incomplete. Long ago, it was thought that macrophages are of importance in the heart after MI. Also, though inflammation is as a result of adverse HF in patients, but despite the fact that broad immunosuppression therapeutic target has been used in various clinical trials, no positive results have showed up, but rather, the focus on proinflammatory cytokines has proved more benefits in patients with HF. Therefore, in this review, we discuss the recent findings and new development about macrophage activations in HF, its role in the healthy heart, and some therapeutic targets for myocardial repair. We have a strong believe that there is a need to give maximum attention to cardiac resident macrophages due to the fact that they perform various tasks in wound healing, self-renewal of the heart, and tissue remodeling. Currently, it has been discovered that the study of macrophages goes far beyond its phagocytotic roles. If researchers in future confirm that macrophages play a vital role in the heart, they can be therapeutically targeted for cardiac healing.

Long non-coding RNA NEAT1 modulates hypoxia/reoxygenation-induced cardiomyocyte injury via targeting microRNA-520a

In the present study, a hypoxia/reoxygenation (H/R) model of cardiomyocytes was established to investigate the effects of long non-coding RNA (LncRNA) Nuclear Enriched Abundant Transcript 1 (NEAT1) and microRNA (miR)-520a on H/R-induced cardiomyocyte apoptosis. Flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling staining were used to evaluate cell apoptosis. Luciferase activity assay was used to investigate whether miR-520a targets NEAT1. Results revealed that NEAT1 was significantly upregulated and miR-520a was downregulated in the ischemia/reperfusion myocardium and the cardiomyocytes that received H/R treatment. Further study demonstrated that knockdown of NEAT1 and overexpression of miR-520a serves a protective role against H/R-induced cardiomyocyte apoptosis. miR-520a directly targets NEAT1 and its expression level is negatively correlated with that of NEAT1. The findings suggested that NEAT1 and miR-520a may protect cardiomyocytes from apoptosis through regulating apoptotic proteins B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein, and altering cleaved caspase3 expression levels.

Biochemical targets of drugs mitigating oxidative stress via redox-independent mechanisms

Acute or chronic oxidative stress plays an important role in many pathologies. Two opposite approaches are typically used to prevent the damage induced by reactive oxygen and nitrogen species (RONS), namely treatment either with antioxidants or with weak oxidants that up-regulate endogenous antioxidant mechanisms. This review discusses options for the third pharmacological approach, namely amelioration of oxidative stress by 'redox-inert' compounds, which do not inactivate RONS but either inhibit the basic mechanisms leading to their formation (i.e. inflammation) or help cells to cope with their toxic action. The present study describes biochemical targets of many drugs mitigating acute oxidative stress in animal models of ischemia-reperfusion injury or N-acetyl-p-aminophenol overdose. In addition to the pro-inflammatory molecules, the targets of mitigating drugs include protein kinases and transcription factors involved in regulation of energy metabolism and cell life/death balance, proteins regulating mitochondrial permeability transition, proteins involved in the endoplasmic reticulum stress and unfolded protein response, nuclear receptors such as peroxisome proliferator-activated receptors, and isoprenoid synthesis. The data may help in identification of oxidative stress mitigators that will be effective in human disease on top of the current standard of care.