Tempol, a Membrane-Permeable Radical Scavenger, Exhibits Anti-Inflammatory and Cardioprotective Effects in the Cerulein-Induced Pancreatitis Rat Model. Oxid Med Cell Longev. 2016;2016:4139851. [PMID: 26770650 PMCID: PMC4685139 DOI: 10.1155/2016/4139851]

Anti-Necroptotic Effects of Itaconate and its Derivatives

Itaconate is an unsaturated dicarboxylic acid that is derived from the decarboxylation of the Krebs cycle intermediate cis-aconitate and has been shown to exhibit anti-inflammatory and anti-bacterial/viral properties. But the mechanisms underlying itaconate's anti-inflammatory activities are not fully understood. Necroptosis, a lytic form of regulated cell death (RCD), is mediated by receptor-interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain-like protein (MLKL) signaling. It has been involved in the pathogenesis of organ injury in many inflammatory diseases. In this study, we aimed to explore whether itaconate and its derivatives can inhibit necroptosis in murine macrophages, a mouse MPC-5 cell line and a human HT-29 cell line in response to different necroptotic activators. Our results showed that itaconate and its derivatives dose-dependently inhibited necroptosis, among which dimethyl itaconate (DMI) was the most effective one. Mechanistically, itaconate and its derivatives inhibited necroptosis by suppressing the RIPK1/RIPK3/MLKL signaling and the oligomerization of MLKL. Furthermore, DMI promoted the nuclear translocation of Nrf2 that is a critical regulator of intracellular redox homeostasis, and reduced the levels of intracellular reactive oxygen species (ROS) and mitochondrial superoxide (mtROS) that were induced by necroptotic activators. Consistently, DMI prevented the loss of mitochondrial membrane potential induced by the necroptotic activators. In addition, DMI mitigated caerulein-induced acute pancreatitis in mice accompanied by reduced activation of the necroptotic signaling in vivo. Collectively, our study demonstrates that itaconate and its derivatives can inhibit necroptosis by suppressing the RIPK1/RIPK3/MLKL signaling, highlighting their potential applications for treating necroptosis-associated diseases.

ROS-scavenging materials for skin wound healing: advancements and applications

The intricate healing process of skin wounds includes a variety of cellular and molecular events. Wound healing heavily relies on reactive oxygen species (ROS), which are essential for controlling various processes, including inflammation, cell growth, angiogenesis, granulation, and the formation of extracellular matrix. Nevertheless, an overabundance of reactive oxygen species (ROS) caused by extended oxidative pressure may result in the postponement or failure of wound healing. It is crucial to comprehend the function of reactive oxygen species (ROS) and create biomaterials that efficiently eliminate ROS to enhance the healing process of skin wounds. In this study, a thorough examination is presented on the role of reactive oxygen species (ROS) in the process of wound healing, along with an exploration of the existing knowledge regarding biomaterials employed for ROS elimination. In addition, the article covers different techniques and substances used in the management of skin wound. The future prospects and clinical applications of enhanced biomaterials are also emphasized, highlighting the potential of biomaterials that scavenge active oxygen to promote skin repair. This article seeks to enhance the understanding of the complex processes of ROS in the healing of wounds and the application of ROS-scavenging materials. Its objective is to create novel strategies for effective treatment skin wounds.

Emerging ROS-Modulating Technologies for Augmentation of the Wound Healing Process

Reactive oxygen species (ROS) is considered a double-edged sword. The slightly elevated level of ROS helps in wound healing by inhibiting microbial infection. In contrast, excessive ROS levels in the wound site show deleterious effects on wound healing by extending the inflammation phase. Understanding the ROS-mediated molecular and biomolecular mechanisms and their effect on cellular homeostasis and inflammation thus substantially improves the possibility of exogenously augmenting and manipulating wound healing with the emerging antioxidant therapeutics. This review comprehensively delves into the relationship between ROS and critical phases of wound healing and the processes underpinning antioxidant therapies. The manuscript also discusses cutting-edge antioxidant therapeutics that act via ROS scavenging to enhance chronic wound healing.

Comprehensive Mechanism, Novel Markers and Multidisciplinary Treatment of Severe Acute Pancreatitis-Associated Cardiac Injury - A Narrative Review

Acute pancreatitis (AP) is one of the common acute abdominal inflammatory diseases in clinic with acute onset and rapid progress. About 20% of the patients will eventually develop into severe acute pancreatitis (SAP) characterized by a large number of inflammatory cells infiltration, gland flocculus flaky necrosis and hemorrhage, finally inducing systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). Pancreatic enzyme activation, intestinal endotoxemia (IETM), cytokine activation, microcirculation disturbance, autonomic nerve dysfunction and autophagy dysregulation all play an essential role in the occurrence and progression of SAP. Organ dysfunction is the main cause of early death in SAP. Acute kidney injury (AKI) and acute lung injury (ALI) are common, while cardiac injury (CI) is not, but the case fatality risk is high. Many basic studies have observed obvious ultrastructure change of heart in SAP, including myocardial edema, cardiac hypertrophy, myocardial interstitial collagen deposition. Moreover, in clinical practice, patients with SAP often presented various abnormal electrocardiogram (ECG) and cardiac function. Cases complicated with acute myocardial infarction and pericardial tamponade have also been reported and even result in stress cardiomyopathy. Due to the molecular mechanisms underlying SAP-associated cardiac injury (SACI) remain poorly understood, and there is no complete, unified treatment and sovereign remedy at present, this article reviews reports referring to the pathogenesis, potential markers and treatment methods of SACI in recent years, in order to improve the understanding of cardiac injury in severe pancreatitis.

Reactive-oxygen-species-scavenging nanomaterials for resolving inflammation

Reactive oxygen species (ROS) mediate multiple physiological functions; however, the over-accumulation of ROS causes premature aging and/or death and is associated with various inflammatory conditions. Nevertheless, there are limited clinical treatment options that are currently available. The good news is that owing to the considerable advances in nanoscience, multiple types of nanomaterials with unique ROS-scavenging abilities that influence the temporospatial dynamic behaviors of ROS in biological systems have been developed. This has led to the emergence of next-generation nanomaterial-controlled strategies aimed at ameliorating ROS-related inflammatory conditions. Accordingly, herein we reviewed recent progress in research on nanotherapy based on ROS scavenging. The underlying mechanisms of the employed nanomaterials are emphasized. Furthermore, important issues in developing cross-disciplinary nanomedicine-based strategies for ROS-based inflammatory conditions are discussed. Our review of this increasing interdisciplinary field will benefit ongoing studies and clinical applications of nanomedicine based on ROS scavenging.

Abdominal paracentesis drainage attenuates intestinal inflammation in rats with severe acute pancreatitis by inhibiting the HMGB1-mediated TLR4 signaling pathway

BACKGROUND

Our previous studies confirmed that abdominal paracentesis drainage (APD) attenuates intestinal mucosal injury in rats with severe acute pancreatitis (SAP), and improves administration of enteral nutrition in patients with acute pancreatitis (AP). However, the underlying mechanisms of the beneficial effects of APD remain poorly understood.

AIM

To evaluate the effect of APD on intestinal inflammation and accompanying apoptosis induced by SAP in rats, and its potential mechanisms.

METHODS

SAP was induced in male adult Sprague-Dawley rats by 5% sodium taurocholate. Mild AP was induced by intraperitoneal injections of cerulein (20 μg/kg body weight, six consecutive injections). Following SAP induction, a drainage tube connected to a vacuum ball was placed into the lower right abdomen of the rats to build APD. Morphological changes, serum inflammatory mediators, serum and ascites high mobility group box protein 1 (HMGB1), intestinal barrier function indices, apoptosis and associated proteins, and toll-like receptor 4 (TLR4) signaling molecules in intestinal tissue were assessed.

RESULTS

APD significantly alleviated intestinal mucosal injury induced by SAP, as demonstrated by decreased pathological scores, serum levels of D-lactate, diamine oxidase and endotoxin. APD reduced intestinal inflammation and accompanying apoptosis of mucosal cells, and normalized the expression of apoptosis-associated proteins in intestinal tissues. APD significantly suppressed activation of the intestinal TLR4 signaling pathway mediated by HMGB1, thus exerting protective effects against SAP-associated intestinal injury.

CONCLUSION

APD improved intestinal barrier function, intestinal inflammatory response and accompanying mucosal cell apoptosis in SAP rats. The beneficial effects are potentially due to inhibition of HMGB1-mediated TLR4 signaling.

Cardiac indicator CK-MB might be a predictive marker for severity and organ failure development of acute pancreatitis

Background

The prediction of severe acute pancreatitis (SAP) is the key to providing timely and targeted intensive care for acute pancreatitis (AP). The heart is one of multiple organs involved in the early stage of SAP, but the predictive ability of cardiac dysfunction for SAP remains elusive. We sought to determine if the serum levels of three cardiac indicators (CI) including N-terminal pro-brain natriuretic peptide (NT-proBNP), cardiac troponin I (cTNI), and creatine kinase myocardial band (CK-MB) at admission could predict the occurrence of SAP and the development of related organ failure (OF).

Methods

A retrospective, single-center cohort study was conducted on the files of patients presenting to the emergency intensive care unit and medical ward of a regional hospital in Shanghai. Patients diagnosed as having AP and who met the 2012 Atlanta guideline were admitted within 48 hours after disease onset.

Results

Of the 670 AP patients screened, 238 were enrolled into the study and divided into mild acute pancreatitis (MAP) (n=59), moderate severe acute pancreatitis (MSAP) (n=123), and SAP (n=56) groups. No significant difference was found in baseline age, gender, duration from disease onset to admission, comorbidity, or substance abuse. As the levels of three CIs were significantly higher in the SAP group than in the MAP and MSAP groups, the enrolled patients were regrouped into non-SAP and SAP groups for predictive evaluation. Multivariate analysis and nomogram modelling showed that CK-MB, but not cTNI or NT-proBNP predicted the occurrence of SAP [area under curve (AUC) =0.805, confidence interval (CI): 0.794–0.905]. Specifically, 89 patients with OF (Modified Marshall score ≥2) upon admission were selected and CK-MB was shown to predict (AUC =0.805, CI: 0.794–0.905) persistent OF (n=48, duration of OF >48 hours) compared to transient organ failure (TOF) (n=41, duration of OF <48 hours).

Conclusions

CIs including NT-proBNP, cTNI, and CK-MB were elevated in the early stage of AP. CK-MB might be used as an efficient predictive biomarker for SAP occurrence and OF development at admission.

Exposure to Static Magnetic and Electric Fields Treats Type 2 Diabetes

Aberrant redox signaling underlies the pathophysiology of many chronic metabolic diseases, including type 2 diabetes (T2D). Methodologies aimed at rebalancing systemic redox homeostasis have had limited success. A noninvasive, sustained approach would enable the long-term control of redox signaling for the treatment of T2D. We report that static magnetic and electric fields (sBE) noninvasively modulate the systemic GSH-to-GSSG redox couple to promote a healthier systemic redox environment that is reducing. Strikingly, when applied to mouse models of T2D, sBE rapidly ameliorates insulin resistance and glucose intolerance in as few as 3 days with no observed adverse effects. Scavenging paramagnetic byproducts of oxygen metabolism with SOD2 in hepatic mitochondria fully abolishes these insulin sensitizing effects, demonstrating that mitochondrial superoxide mediates induction of these therapeutic changes. Our findings introduce a remarkable redox-modulating phenomenon that exploits endogenous electromagneto-receptive mechanisms for the noninvasive treatment of T2D, and potentially other redox-related diseases.

Abdominal paracentesis drainage ameliorates myocardial injury in severe experimental pancreatitis rats through suppressing oxidative stress

BACKGROUND

Abdominal paracentesis drainage (APD) is a safe and effective strategy for severe acute pancreatitis (SAP) patients. However, the effects of APD treatment on SAP-associated cardiac injury remain unknown.

AIM

To investigate the protective effects of APD on SAP-associated cardiac injury and the underlying mechanisms.

METHODS

SAP was induced by 5% sodium taurocholate retrograde injection in Sprague-Dawley rats. APD was performed by inserting a drainage tube with a vacuum ball into the lower right abdomen of the rats immediately after SAP induction. Morphological staining, serum amylase and inflammatory mediators, serum and ascites high mobility group box (HMGB) 1, cardiac-related enzymes indexes and cardiac function, oxidative stress markers and apoptosis and associated proteins were assessed in the myocardium in SAP rats. Nicotinamide adenine dinucleotide phosphate oxidase activity and mRNA and protein expression were also examined.

RESULTS

APD treatment improved cardiac morphological changes, inhibited cardiac dysfunction, decreased cardiac enzymes and reduced cardiomyocyte apoptosis, proapoptotic Bax and cleaved caspase-3 protein levels. APD significantly decreased serum levels of HMGB1, inhibited nicotinamide adenine dinucleotide phosphate oxidase expression and ultimately alleviated cardiac oxidative injury. Furthermore, the activation of cardiac nicotinamide adenine dinucleotide phosphate oxidase by pancreatitis-associated ascitic fluid intraperitoneal injection was effectively inhibited by adding anti-HMGB1 neutralizing antibody in rats with mild acute pancreatitis.

CONCLUSION

APD treatment could exert cardioprotective effects on SAP-associated cardiac injury through suppressing HMGB1-mediated oxidative stress, which may be a novel mechanism behind the effectiveness of APD on SAP.

Low Serum Irisin Concentration Is Associated with Poor Outcomes in Patients with Acute Pancreatitis, and Irisin Administration Protects Against Experimental Acute Pancreatitis

Aims: Severe acute pancreatitis (AP) is a serious condition without specific treatment. Mitochondrial dysfunction plays a crucial role in the pathogenesis of AP. Irisin, a novel exercise-induced hormone, contributes to many health benefits of physical activity. We and others have shown that irisin protects against ischemia reperfusion-induced organ injury by alleviating mitochondrial damage. However, the role of irisin in AP has not been evaluated. The purpose of this study was to investigate the role of serum irisin levels in patients with AP and the effect of irisin administration in experimental AP. Results: Serum irisin levels were decreased in AP patients, and low serum irisin levels were associated with worse outcomes in these patients. Treatment with exogenous irisin increased survival and mitigated pancreatic injury in experimental AP. The protective effects of irisin in AP were associated with improvement in mitochondrial function and reduction in ER stress. Moreover, irisin upregulated UCP2 expression in the pancreas, and administration of genipin, a specific UCP2 antagonist, abolished irisin's beneficial effects in L-arginine-induced AP. Innovation and Conclusion: Low serum irisin was associated with poor outcomes in AP patients, and irisin administration protected against experimental AP by restoring mitochondrial function via activation of UCP2. Restoration of mitochondrial function by irisin may offer therapeutic potential for patients with AP. Antioxid. Redox Signal. 31, 771-785.

Tempol Alleviates Chronic Intermittent Hypoxia-Induced Pancreatic Injury Through Repressing Inflammation and Apoptosis

Obstructive sleep apnea (OSA) has been demonstrated to be implicated in disorder of insulin secretion and diabetes mellitus. In this study, we aimed to evaluate the protective role of tempol, a powerful antioxidant, in chronic intermittent hypoxia (IH)-induced pancreatic injury. The rat model of OSA was established by IH exposure. The pathological changes, increased blood-glucose level, and raised proinsulin/insulin ratio in pancreatic tissues of rats received IH were effectively relieved by tempol delivery. In addition, the enhanced levels of pro-inflammatory cytokines, TNF-α, IL-1β, IL-6, and inflammatory mediators, PGE2, cyclooxygenase-2 (COX-2), NO, and inducible nitric oxide synthase (iNOS) in pancreatic tissue were suppressed by tempol. Moreover, tempol inhibited IH-induced apoptosis in pancreatic tissue as evidenced by upregulated Bcl-2 level, and downregulated Bax and cleaved caspase-3 levels. Finally, the abnormal activation of mitogen-activated protein kinase (MAPK) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathways induced by IH was restrained by tempol administration. In summary, our study demonstrates that tempol relieves IH-induced pancreatic injury by inhibiting inflammatory response and apoptosis, which provides theoretical basis for tempol as an effective treatment for OSA-induced pancreatic injury.

Murine Models of Acute Pancreatitis: A Critical Appraisal of Clinical Relevance

Acute pancreatitis (AP) is a severe disease associated with high morbidity and mortality. Clinical studies can provide some data concerning the etiology, pathophysiology, and outcomes of this disease. However, the study of early events and new targeted therapies cannot be performed on humans due to ethical reasons. Experimental murine models can be used in the understanding of the pancreatic inflammation, because they are able to closely mimic the main features of human AP, namely their histologic glandular changes and distant organ failure. These models continue to be important research tools for the reproduction of the etiological, environmental, and genetic factors associated with the pathogenesis of this inflammatory pathology and the exploration of novel therapeutic options. This review provides an overview of several murine models of AP. Furthermore, special focus is made on the most frequently carried out models, the protocols used, and their advantages and limitations. Finally, examples are provided of the use of these models to improve knowledge of the mechanisms involved in the pathogenesis, identify new biomarkers of severity, and develop new targeted therapies.

Flavin Oxidase-Induced ROS Generation Modulates PKC Biphasic Effect of Resveratrol on Endothelial Cell Survival

Background: Dietary intake of natural antioxidants is thought to impart protection against oxidative-associated cardiovascular diseases. Despite many in vivo studies and clinical trials, this issue has not been conclusively resolved. Resveratrol (RES) is one of the most extensively studied dietary polyphenolic antioxidants. Paradoxically, we have previously demonstrated that high RES concentrations exert a pro-oxidant effect eventually elevating ROS levels leading to cell death. Here, we further elucidate the molecular determinants underpinning RES-induced oxidative cell death. Methods: Using human umbilical vein endothelial cells (HUVECs), the effect of increasing concentrations of RES on DNA synthesis and apoptosis was studied. In addition, mRNA and protein levels of cell survival or apoptosis genes, as well as protein kinase C (PKC) activity were determined. Results: While high concentrations of RES reduce PKC activity, inhibit DNA synthesis and induce apoptosis, low RES concentrations elicit an opposite effect. This biphasic concentration-dependent effect (BCDE) of RES on PKC activity is mirrored at the molecular level. Indeed, high RES concentrations upregulate the proapoptotic Bax, while downregulating the antiapoptotic Bcl-2, at both mRNA and protein levels. Similarly, high RES concentrations downregulate the cell cycle progression genes, c-myc, ornithine decarboxylase (ODC) and cyclin D1 protein levels, while low RES concentrations display an increasing trend. The BCDE of RES on PKC activity is abrogated by the ROS scavenger Tempol, indicating that this enzyme acts downstream of the RES-elicited ROS signaling. The RES-induced BCDE on HUVEC cell cycle machinery was also blunted by the flavin inhibitor diphenyleneiodonium (DPI), implicating flavin oxidase-generated ROS as the mechanistic link in the cellular response to different RES concentrations. Finally, PKC inhibition abrogates the BCDE elicited by RES on both cell cycle progression and pro-apoptotic gene expression in HUVECs, mechanistically implicating PKC in the cellular response to different RES concentrations. Conclusions: Our results provide new molecular insight into the impact of RES on endothelial function/dysfunction, further confirming that obtaining an optimal benefit of RES is concentration-dependent. Importantly, the BCDE of RES could explain why other studies failed to establish the cardio-protective effects mediated by natural antioxidants, thus providing a guide for future investigation looking at cardio-protection by natural antioxidants.

A Broad-Spectrum ROS-Eliminating Material for Prevention of Inflammation and Drug-Induced Organ Toxicity

Despite the great potential of numerous antioxidants for pharmacotherapy of diseases associated with inflammation and oxidative stress, many challenges remain for their clinical translation. Herein, a superoxidase dismutase/catalase-mimetic material based on Tempol and phenylboronic acid pinacol ester simultaneously conjugated β-cyclodextrin (abbreviated as TPCD), which is capable of eliminating a broad spectrum of reactive oxygen species (ROS), is reported. TPCD can be easily synthesized by sequentially conjugating two functional moieties onto a β-cyclodextrin scaffold. The thus developed pharmacologically active material may be easily produced into antioxidant and anti-inflammatory nanoparticles, with tunable size. TPCD nanoparticles (TPCD NP) effectively protect macrophages from oxidative stress-induced apoptosis in vitro. Consistently, TPCD NP shows superior efficacies in three murine models of inflammatory diseases, with respect to attenuating inflammatory responses and mitigating oxidative stress. TPCD NP can also protect mice from drug-induced organ toxicity. Besides the passive targeting effect, the broad spectrum ROS-scavenging capability contributes to the therapeutic benefits of TPCD NP. Importantly, in vitro and in vivo preliminary experiments demonstrate the good safety profile of TPCD NP. Consequently, TPCD in its native and nanoparticle forms can be further developed as efficacious and safe therapies for treatment of inflammation and oxidative stress-associated diseases.

Adenovirus-mediated overexpression of sST2 attenuates cardiac injury in the rat with severe acute pancreatitis

AIMS

Severe acute pancreatitis (SAP) is a serious disease associated with systematic inflammation and multiple organs dysfunction. Soluble ST2 (sST2), a member of the Toll interleukin (IL)-1 receptor (TIR) superfamily, has been demonstrated to exert immune-regulatory and anti-inflammatory properties in several inflammation-related diseases. In this study, we investigated whether transfer of sST2 gene by adenovirus vector could attenuate sodium taurocholate-induced SAP and associated cardiac injury.

MAIN METHODS

A rat model of SAP was induced by retrograde injection of 5% sodium taurocholate (1 ml/kg) into the biliopancreatic duct. Rats in the treatment groups were intravenously injected with adenovirus expressing sST2 (Ad-sST2, 1 × 10⁹ particles/rat) or green fluorescent protein (Ad-GFP) via the tail vein 48 h before SAP induction. Histological changes in the pancreatic and heart tissues, and parameters for evaluating SAP and associated cardiac injury were determined at 24 h after SAP.

KEY FINDINGS

Sodium taurocholate induced obvious pathological changes in pancreas and elevated serum levels of amylase and lipase. Furthermore, SAP animals exhibited significant cardiac impairment, evidenced by decreased cardiac function, increased myocardial apoptosis and cardiac-related enzymes including creatine kinase isoenzyme, lactate dehydrogenase, and Troponin T. Administration of Ad-sST2 markedly improved the structure of pancreas and heart tissues, and reversed the alterations in serum amylase, lipase and cardiac-related enzymes. In addition, Ad-sST2 treatment downregulated pro-inflammatory cytokines production, demonstrating the anti-inflammatory property of sST2.

SIGNIFICANCE

Our results suggest that administration of Ad-sST2 significantly attenuated the severity of SAP and associated cardiac damage, and the cardioprotective effect is associated with its anti-inflammatory action.

Neuroprotective Effects of Bioactive Compounds and MAPK Pathway Modulation in "Ischemia"-Stressed PC12 Pheochromocytoma Cells

This review surveys the efforts taken to investigate in vitro neuroprotective features of synthetic compounds and cell-released growth factors on PC12 clonal cell line temporarily deprived of oxygen and glucose followed by reoxygenation (OGD/R). These cells have been used previously to mimic some of the properties of in vivo brain ischemia-reperfusion-injury (IRI) and have been instrumental in identifying common mechanisms such as calcium overload, redox potential, lipid peroxidation and MAPKs modulation. In addition, they were useful for establishing the role of certain membrane penetrable cocktails of antioxidants as well as potential growth factors which may act in neuroprotection. Pharmacological mechanisms of neuroprotection addressing modulation of the MAPK cascade and increased redox potential by natural products, drugs and growth factors secreted by stem cells, in either undifferentiated or nerve growth factor-differentiated PC12 cells exposed to ischemic conditions are discussed for future prospects in neuroprotection studies.

Activation of NADPH oxidases leads to DNA damage in esophageal cells

Gastroesophageal reflux disease (GERD) is the strongest known risk factor for esophageal adenocarcinoma. In the center of tumorigenic events caused by GERD is repeated damage of esophageal tissues by the refluxate. In this study, we focused on a genotoxic aspect of exposure of esophageal cells to acidic bile reflux (BA/A). Analyzing cells generated from patients with Barrett's esophagus and human esophageal specimens, we found that BA/A cause significant DNA damage that is mediated by reactive-oxygen species. ROS originate from mitochondria and NADPH oxidases. We specifically identified NOX1 and NOX2 enzymes to be responsible for ROS generation. Inhibition of NOX2 and NOX1 with siRNA or chemical inhibitors significantly suppresses ROS production and DNA damage induced by BA/A. Mechanistically, our data showed that exposure of esophageal cells to acidic bile salts induces phosphorylation of the p47^phox subunit of NOX2 and its translocation to the cellular membrane. This process is mediated by protein kinase C, which is activated by BA/A. Taken together, our studies suggest that inhibition of ROS induced by reflux can be a useful strategy for preventing DNA damage and decreasing the risk of tumorigenic transformation caused by GERD.

Protective Effect of Tempol Against Hypoxia-Induced Oxidative Stress and Apoptosis in H9c2 Cells

Background

Hypoxia-induced oxidant stress and cardiomyocyte apoptosis are considered essential processes in the progression of heart failure. Tempol is a nitroxide compound that scavenges many reactive oxygen species (ROS) and has antioxidant and cardioprotective effects. This study aimed to investigate the protective effect of Tempol against hypoxia-induced oxidative stress and apoptosis in the H9c2 rat cardiomyoblast cell line, in addition to related mechanisms.

Material/Methods

H9c2 cells were pre-treated with Tempol, followed by hypoxia (37°C, 5% CO₂, and 95% N₂) for 24 h. Cell viability was detected using MTT assay. ROS level was evaluated using DCFH-DA. Lactate dehydrogenase (LDH), creatinine kinase (CK), malondialdehyde (MDA), catalase (CAT), and superoxide dismutase (SOD) were evaluated using the relevant kits. Cell apoptosis was determined by Annexin V/7-AAD double labelling. The expression of apoptosis-related molecules was assessed with RT-PCR analysis and Western blotting.

Results

Tempol protected H9c2 cells against hypoxia-induced injury, with characteristics of increased the cell viability and reduced LDH and CK release. Tempol also reduced oxidant stress by inhibiting ROS generation and lipid peroxidation, as well as enhancing antioxidant enzyme activity. Moreover, Tempol pretreatment upregulated the expression of Bcl-2 and downregulated the expression of Bax and caspase-3, thereby reducing hypoxia-induced apoptosis in H9c2 cells.

Conclusions

These results indicate that Tempol reduces the hypoxia-induced oxidant stress and apoptosis in H9c2 cells by scavenging free radicals and modulating the expression of apoptosis-related proteins.

Novel Synthetic PEGylated Conjugate of α-Lipoic Acid and Tempol Reduces Cell Death in a Neuronal PC12 Clonal Line Subjected to Ischemia

α-Lipoic acid (α-LA), a natural thiol antioxidant, and Tempol, a synthetic free radical scavenger, are known to confer neuroprotection following ischemic insults in both in vivo and in vitro models. The aim of this study was to synthesize and characterize a conjugate of α-LA and Tempol linked by polyethylene glycol (PEG) in order to generate a more efficacious neuroprotectant molecule. AD3 (α-Tempol ester-ω-lipo ester PEG) was synthesized, purified, and characterized by flash chromatography and reverse phase high pressure liquid chromatography and by ¹H nuclear magnetic resonance, infrared spectroscopy, and mass spectrometry. AD3 conferred neuroprotection in a PC12 pheochromocytoma cell line of dopaminergic origin, exposed to oxygen and glucose deprivation (OGD) insult measured by LDH release. AD3 exhibited EC₅₀ at 10 μM and showed a 2-3-fold higher efficacy compared to the precursor moieties, indicating an intrinsic potent neuroprotective activity. AD3 attenuated by 25% the intracellular redox potential, by 54% lipid peroxidation and prevented phosphorylation of ERK, JNK, and p38 by 57%, 22%, and 21%, respectively. Cumulatively, these findings indicate that AD3 is a novel conjugate that confers neuroprotection by attenuation of MAPK phosphorylation and by modulation of the redox potential of the cells.