NADPH oxidase-derived superoxide anion-induced apoptosis is mediated via the JNK-dependent activation of NF-κB in cardiomyocytes exposed to high glucose

Understanding One Half of the Sex Difference Equation: The Modulatory Effects of Testosterone on Diabetic Cardiomyopathy

Diabetes is a prevalent disease, primarily characterized by high blood sugar (hyperglycemia). Significantly higher rates of myocardial dysfunction have been noted in individuals with diabetes, even in those without coronary artery disease or high blood pressure (hypertension). Numerous molecular mechanisms have been identified through which diabetes contributes to the pathology of diabetic cardiomyopathy, which presents as cardiac hypertrophy and fibrosis. At the cellular level, oxidative stress and inflammation in cardiomyocytes are triggered by hyperglycemia. Although males are generally more likely to develop cardiovascular disease than females, diabetic males are less likely to develop diabetic cardiomyopathy than are diabetic females. One reason for these differences may be the higher levels of serum testosterone in males compared with females. Although testosterone appears to protect against cardiomyocyte oxidative stress and exacerbate hypertrophy, its role in inflammation and fibrosis is much less clear. Additional preclinical and clinical studies will be required to delineate testosterone's effect on the diabetic heart.

The Interconnection between Hepatic Insulin Resistance and Metabolic Dysfunction-Associated Steatotic Liver Disease-The Transition from an Adipocentric to Liver-Centric Approach

The central mechanism involved in the pathogenesis of MAFLD is insulin resistance with hyperinsulinemia, which stimulates triglyceride synthesis and accumulation in the liver. On the other side, triglyceride and free fatty acid accumulation in hepatocytes promotes insulin resistance via oxidative stress, endoplasmic reticulum stress, lipotoxicity, and the increased secretion of hepatokines. Cytokines and adipokines cause insulin resistance, thus promoting lipolysis in adipose tissue and ectopic fat deposition in the muscles and liver. Free fatty acids along with cytokines and adipokines contribute to insulin resistance in the liver via the activation of numerous signaling pathways. The secretion of hepatokines, hormone-like proteins, primarily by hepatocytes is disturbed and impairs signaling pathways, causing metabolic dysregulation in the liver. ER stress and unfolded protein response play significant roles in insulin resistance aggravation through the activation of apoptosis, inflammatory response, and insulin signaling impairment mediated via IRE1/PERK/ATF6 signaling pathways and the upregulation of SREBP 1c. Circadian rhythm derangement and biological clock desynchronization are related to metabolic disorders, insulin resistance, and NAFLD, suggesting clock genes as a potential target for new therapeutic strategies. This review aims to summarize the mechanisms of hepatic insulin resistance involved in NAFLD development and progression.

Dual stimulus responsive borosilicate glass (BSG) scaffolds promote diabetic alveolar bone defectsrepair by modulating macrophage phenotype

The regeneration of alveolar bone is still clinical challenge, particularly accompanied with diabetes, causing metabolic disorder with a protracted low-grade inflammatory phenotype. As a result, the anticipated loading of biomaterials is highly suspicious in spontaneous modulation of cells function, which is mostly disturbed by constant inflammation. In this study, we developed glucose and hydrogen peroxide dual-responsive borosilicate glass (BSG) scaffolds loaded with epigallocatechin gallate (EGCG) to synergistically modulate the abnormal inflammation of diabetic alveolar bone defects. It was found that the release of EGCG by BSG could directly regulate the shift of macrophages from M1 to the M2 phenotype by promoting autophagy and lessening the inhibition of autophagic flux. Moreover, EGCG can also indirectly regulate the polarization phenotype of macrophages by reducing the activation of NF-κb in stem cells and restoring its immunoregulatory capacity. Therefore, the addition of EGCG to BSG scaffold in diabetes allows for a more striking modulation of the macrophage phenotype in a timely manner. The altered macrophage phenotype reduces local inflammation and thus increases the ability to repair diabetic alveolar bone, showing promise for the treatment of alveolar defect in diabetic patients.

Puerarin Attenuates High-Glucose and High-Lipid-Induced Inflammatory Injury in H9c2 Cardiomyocytes via CAV3 Protein Upregulation

Background

Inflammation plays a crucial role in the development of diabetic cardiomyopathy (DCM), including inflammation caused by high-glucose and high-lipid (HGHL). Targeting inflammation may provide a useful strategy for preventing and treating DCM. Puerarin has been shown to reduce the inflammation, apoptosis and hypertrophy of cardiomyocytes induced by HGHL, in which this study aims to investigate the underlying mechanisms.

Methods

H9c2 cardiomyocytes cultured with HGHL were used to establish a cell model of DCM. Puerarin was then placed to these cells for 24 hours. The effects of HGHL and puerarin on cell viability and apoptosis were investigated by the Cell Proliferation, Toxicity Assay Kit (CCK-8) and flow cytometry. Morphological changes of cardiomyocytes was observed by HE staining. CAV3 proteins in H9c2 cardiomyocytes were altered by transient transfection of CAV3 siRNA. IL-6 was detected by ELISA. The Western blot was performed to determine the CAV3, Bcl-2, Bax, pro-Caspase-3, cleaved-Caspase-3, NF-κB (p65) and p38MAPK proteins.

Results

Puerarin treatment reversed the cells viability, hypertrophy in morphology, inflammation (showed by p-p38 and p-p65 and IL-6) and apoptosis-related damage (showed by cleaved-Caspase-3/pro-Caspase-3/Bax, Bcl-2 and flow cytometry) of the H9c2 cardiomyocyte caused by HGHL. Puerarin treatment also restored the decrease of CAV3 proteins of the H9c2 cardiomyocyte caused by HGHL. When silenced the expression of CAV3 proteins with SiRNA, puerarin failed to decreased p-p38 and p-p65 and IL-6, and could not reversed cell viability and morphological damage. In contrast to the simple CAV3 silenced group, the CAV3 silenced with NF-κB pathway or p38MAPK pathway inhibitors, significantly downregulated the p-p38, p-p65 and IL-6.

Conclusion

Puerarin upregulated CAV3 protein expression in H9c2 cardiomyocytes and inhibited the NF-κB and p38MAPK pathways, thereby reducing HGHL-induced inflammation and may related to the apoptosis and hypertrophy of cardiomyocytes.

Diabetes as one of the long-term COVID-19 complications: from the potential reason of more diabetic patients' susceptibility to COVID-19 to the possible caution of future global diabetes tsunami

According to recent researches, people with diabetes mellitus (type 1 and 2) have a higher incidence of coronavirus disease 2019 (COVID-19), which is caused by a SARS-CoV-2 infection. In this regard, COVID-19 may make diabetic patients more sensitive to hyperglycemia by modifying the immunological and inflammatory responses and increasing reactive oxygen species (ROS) predisposing the patients to severe COVID-19 and potentially lethal results. Actually, in addition to COVID-19, diabetic patients have been demonstrated to have abnormally high levels of inflammatory cytokines, increased virus entrance, and decreased immune response. On the other hand, during the severe stage of COVID-19, the SARS-CoV-2-infected patients have lymphopenia and inflammatory cytokine storms that cause damage to several body organs such as β cells of the pancreas which may make them as future diabetic candidates. In this line, the nuclear factor kappa B (NF-κB) pathway, which is activated by a number of mediators, plays a substantial part in cytokine storms through various pathways. In this pathway, some polymorphisms also make the individuals more competent to diabetes via infection with SARS-CoV-2. On the other hand, during hospitalization of SARS-CoV-2-infected patients, the use of some drugs may unintentionally lead to diabetes in the future via increasing inflammation and stress oxidative. Thus, in this review, we will first explain why diabetic patients are more susceptible to COVID-19. Second, we will warn about a future global diabetes tsunami via the SARS-CoV-2 as one of its long-term complications.

Taurine alleviates endoplasmic reticulum stress, inflammatory cytokine expression and mitochondrial oxidative stress induced by high glucose in the muscle cells of olive flounder (Paralichthysolivaceus)

The aim of the present study was to evaluate the effects of taurine on endoplasmic reticulum stress, inflammatory cytokine expression and mitochondrial oxidative stress induced by high glucose in primary cultured muscle cells of olive flounder (Paralichthys olivaceus). Three experimental groups were designed as follows: muscle cells of olive flounder incubated with three kinds of medium containing 5 mM glucose (control), 33 mM glucose (HG) or 33 mM glucose + 10 mM taurine (HG + T), respectively. Results showed that taurine addition significantly alleviated the decreased activity of superoxide dismutase (SOD) and the ratio of reduced to oxidized glutathione (GSH/GSSG) induced by high glucose. The increase of cellular reactive oxygen species (ROS), malondialdehyde content and cell apoptosis induced by high glucose were alleviated by taurine. Besides, gene expression of glucose-regulated protein 78, PKR-like ER kinase, tumor necrosis factor-α, interleukin-6, interleukin-1β, interleukin-8, muscle atrophy F-box protein and muscle RING-finger protein 1 were significantly up-regulated in the HG group, and taurine addition decreased the expression of these genes. High glucose led to the swelling of the endoplasmic reticulum (ER). Meanwhile, the nuclear translocation of nuclear factor κB (NF-κB) and the release of cytochrome C from mitochondria induced by high glucose were suppressed by taurine addition. These results demonstrated that taurine alleviated ERS, inflammation and mitochondrial oxidative stress induced by high glucose in olive flounder muscle cells. The ROS production, NF-κB signaling pathway and mitochondria function were the main targets of the biological effects of taurine under high glucose condition.

Pyroptosis-Related Inflammasome Pathway: A New Therapeutic Target for Diabetic Cardiomyopathy

Pyroptosis is a highly specific type of inflammatory programmed cell death that is mediated by Gasdermine (GSDM). It is characterized by inflammasome activation, caspase activation, and cell membrane pore formation. Diabetic cardiomyopathy (DCM) is one of the leading diabetic complications and is a critical cause of fatalities in chronic diabetic patients, it is defined as a clinical condition of abnormal myocardial structure and performance in diabetic patients without other cardiac risk factors, such as hypertension, significant valvular disease, etc. There are no specific drugs in treating DCM despite decades of basic and clinical investigations. Although the relationship between DCM and pyroptosis is not well established yet, current studies provided the impetus for us to clarify the significance of pyroptosis in DCM. In this review, we summarize the recent literature addressing the role of pyroptosis and the inflammasome in the development of DCM and summary the potential use of approaches targeting this pathway which may be future anti-DCM strategies.

NR4A2 alleviates cardiomyocyte loss and myocardial injury in rats by transcriptionally suppressing CCR5 and inducing M2 polarization of macrophages

BACKGROUND

CC chemokine receptor 5 (CCR5) has been demonstrated to be correlated to activation of pro-inflammatory immune cells and tissue injury. This study focused on the role of CCR5 in myocardial injury in rats with diabetic cardiomyopathy (DCM) and the mechanism of action.

METHODS

A rat model of DCM was induced by streptozotocin (STZ). CCR5 was knocked down in rats to determine its role in myocardial injury and immune cell infiltration. The upstream regulators of CCR5 were bioinformatically predicted and the binding between nuclear receptor subfamily 4 group A member 2 (NR4A2) and CCR5 was validated. The portion of M1 and M2 macrophages in tissues was determined by flow cytometry or double-labeling immunofluorescence. Rat bone marrow mononuclear cells (BMMCs) were treated with granulocyte/macrophage colony stimulating factor (GM-CSF/M-CSF) and co-cultured with H9C2 cells for in vitro experiments.

RESULTS

STZ-treated rats had impaired cardiac function and increased levels of creatine kinase-MB, cardiac troponin I and lactate dehydrogenase. CCR5 inhibition significantly alleviated myocardial injury in rats and reduced the portion of M1 macrophages in rat cardiac tissues. NR4A2, which could suppress CCR5 transcription, was poorly expressed in rats with DCM. NR4A2 overexpression played a similar myocardium-protective role in rats. In vitro, overexpression of NR4A2 induced M2 polarization of macrophages, which protected the co-cultured H9C2 cells from high glucose-induced damage, but the protective role was blocked after CCR5 overexpression.

CONCLUSION

This study demonstrated that NR4A2 suppresses CCR5 expression and promotes M2 polarization of macrophages to alleviate cardiomyocyte loss and myocardial injury.

Mechanistic Insight into Oxidative Stress-Triggered Signaling Pathways and Type 2 Diabetes

Oxidative stress (OS) is a metabolic dysfunction mediated by the imbalance between the biochemical processes leading to elevated production of reactive oxygen species (ROS) and the antioxidant defense system of the body. It has a ubiquitous role in the development of numerous noncommunicable maladies including cardiovascular diseases, cancers, neurodegenerative diseases, aging and respiratory diseases. Diseases associated with metabolic dysfunction may be influenced by changes in the redox balance. Lately, there has been increasing awareness and evidence that diabetes mellitus (DM), particularly type 2 diabetes, is significantly modulated by oxidative stress. DM is a state of impaired metabolism characterized by hyperglycemia, resulting from defects in insulin secretion or action, or both. ROS such as hydrogen peroxide and the superoxide anion introduce chemical changes virtually in all cellular components, causing deleterious effects on the islets of β-cells, in turn affecting insulin production. Under hyperglycemic conditions, various signaling pathways such as nuclear factor-κβ (NF-κβ) and protein kinase C (PKC) are also activated by ROS. All of these can be linked to a hindrance in insulin signaling pathways, leading to insulin resistance. Hyperglycemia-induced oxidative stress plays a substantial role in complications including diabetic nephropathy. DM patients are more prone to microvascular as well as atherosclerotic macrovascular diseases. This systemic disease affects most countries around the world, owing to population explosion, aging, urbanization, obesity, lifestyle, etc. However, some modulators, with their free radical scavenging properties, can play a prospective role in overcoming the debilitating effects of OS. This review is a modest approach to summarizing the basics and interlinkages of oxidative stress, its modulators and diabetes mellitus. It may add to the understanding of and insight into the pathophysiology of diabetes and the crucial role of antioxidants to weaken the complications and morbidity resulting from this chronic disease.

Galangin Reverses H2O2-Induced Dermal Fibroblast Senescence via SIRT1-PGC-1α/Nrf2 Signaling

UV radiation and H₂O₂ are the primary factors that cause skin aging. Both trigger oxidative stress and cellular aging. It has been reported that deacetylase silent information regulator 1 (SIRT1), a longevity gene, enhances activation of NF-E2-related factor-2 (Nrf2), as well as its downstream key antioxidant gene hemeoxygenase-1 (HO-1), to protect cells against oxidative damage by deacetylating the transcription coactivator PPARγ coactivator-1α (PGC-1α). Galangin, a flavonoid, possesses anti-oxidative and anti-inflammatory potential. In the present study, we applied Ultraviolet B/H₂O₂-induced human dermal fibroblast damage as an in vitro model and UVB-induced photoaging of C57BL/6J nude mice as an in vivo model to investigate the underlying dermo-protective mechanisms of galangin. Our results indicated that galangin treatment attenuates H₂O₂/UVB-induced cell viability reduction, dermal aging, and SIRT1/PGC-1α/Nrf2 signaling activation. Furthermore, galangin treatment enhanced Nrf2 activation and nuclear accumulation, in addition to inhibiting Nrf2 degradation. Interestingly, upregulation of antioxidant response element luciferase activity following galangin treatment indicated the transcriptional activation of Nrf2. However, knockdown of SIRT1, PGC-1α, or Nrf2 by siRNA reversed the antioxidant and anti-aging effects of galangin. In vivo evidence further showed that galangin treatment, at doses of 12 and 24 mg/kg on the dorsal skin cells of nude mice resulted in considerably reduced UVB-induced epidermal hyperplasia and skin senescence, and promoted SIRT1/PGC-1α/Nrf2 signaling. Furthermore, enhanced nuclear localization of Nrf2 was observed in galangin-treated mice following UVB irradiation. In conclusion, our data indicated that galangin exerts anti-photoaging and antioxidant effects by promoting SIRT1/PGC-1α/Nrf2 signaling. Therefore, galangin is a potentially promising agent for cosmetic skin care products against UV-induced skin aging.

Clues and new evidences in arterial hypertension: unmasking the role of the chloride anion

The present review will focus on the role of chloride anion in cardiovascular disease, with special emphasis in the development of hypertensive disease and vascular inflammation. It is known that acute and chronic overload of sodium chloride increase blood pressure and have pro-inflammatory and pro-fibrotic effects on different target organs, but it is unknown how chloride may influence these processes. Chloride anion is the predominant anion in the extracellular fluid and its intracellular concentration is dynamically regulated. As the queen of the electrolytes, it is of crucial importance to understand the physiological mechanisms that regulate the cellular handling of this anion including the different transporters and cellular chloride channels, which exert a variety of functions, such as regulation of cellular proliferation, differentiation, migration, apoptosis, intracellular pH and cellular redox state. In this article, we will also review the relationship between dietary, serum and intracellular chloride and how these different sources of chloride in the organism are affected in hypertension and their impact on cardiovascular disease. Additionally, we will discuss the approach of potential strategies that affect chloride handling and its potential effect on cardiovascular system, including pharmacological blockade of chloride channels and non-pharmacological interventions by replacing chloride by another anion.

Carboxyl terminus of HSP70-interacting protein attenuates advanced glycation end products-induced cardiac injuries by promoting NFκB proteasomal degradation

Advanced glycation end products (AGEs), which are highly reactive molecules resulting from persistent high-glucose levels, can lead to the generation of oxidative stress and cardiac complications. The carboxyl terminus of HSP70 interacting protein (CHIP) has been demonstrated to have a protective role in several diseases, including cardiac complications; however, the role in preventing AGE-induced cardiac damages remains poorly understood. Here, we found that elevated AGE levels impaired cardiac CHIP expression in streptozotocin-induced diabetes and high-fat diet-administered animals, representing AGE exposure models. We used the TUNEL assay, hematoxylin and eosin, Masson's trichrome staining, and western blotting to prove that cardiac injuries were induced in diabetic animals and AGE-treated cardiac cells. Interestingly, our results collectively indicated that CHIP overexpression significantly rescued the AGE-induced cardiac injuries and promoted cell survival. Moreover, CHIP knockdown-mediated stabilization of nuclear factor κB (NFκB) was attenuated by overexpressing CHIP in the cells. Furthermore, co-immunoprecipitation and immunoblot assay revealed that CHIP promotes the ubiquitination and proteasomal degradation of AGE-induced NFκB. Importantly, fluorescence microscopy, a luciferase reporter assay, electrophoretic mobility shift assay, and subcellular fractionation further demonstrated that CHIP overexpression inhibits AGE-induced NFκB nuclear translocation, reduced its binding ability with the promoter sequences of the receptor of AGE, consequently inhibiting the translocation of the receptor AGE to the cell membrane for its proper function. Overall, our current study findings suggest that CHIP can target NFκB for ubiquitin-mediated proteasomal degradation, and thereby potentially rescue AGE-induced cardiac damages.

Increased Fetal Cardiovascular Disease Risk: Potential Synergy Between Gestational Diabetes Mellitus and Maternal Hypercholesterolemia

Cardiovascular diseases (CVD) remain a major cause of death worldwide. Evidence suggests that the risk for CVD can increase at the fetal stages due to maternal metabolic diseases, such as gestational diabetes mellitus (GDM) and maternal supraphysiological hypercholesterolemia (MSPH). GDM is a hyperglycemic, inflammatory, and insulin-resistant state that increases plasma levels of free fatty acids and triglycerides, impairs endothelial vascular tone regulation, and due to the increased nutrient transport, exposes the fetus to the altered metabolic conditions of the mother. MSPH involves increased levels of cholesterol (mainly as low-density lipoprotein cholesterol) which also causes endothelial dysfunction and alters nutrient transport to the fetus. Despite that an association has already been established between MSPH and increased CVD risk, however, little is known about the cellular processes underlying this relationship. Our knowledge is further obscured when the simultaneous presentation of MSPH and GDM takes place. In this context, GDM and MSPH may substantially increase fetal CVD risk due to synergistic impairment of placental nutrient transport and endothelial dysfunction. More studies on the separate and/or cumulative role of both processes are warranted to suggest specific treatment options.

The Interplay between Insulin Resistance, Inflammation, Oxidative Stress, Base Excision Repair and Metabolic Syndrome in Nonalcoholic Fatty Liver Disease

One of the most common chronic liver disorders, affecting mainly people in Western countries, is nonalcoholic fatty liver disease (NAFLD). Unfortunately, its pathophysiological mechanism is not fully understood, and no dedicated treatment is available. Simple steatosis can lead to nonalcoholic steatohepatitis and even to fibrosis, cancer, and cirrhosis of the liver. NAFLD very often occurs in parallel with type 2 diabetes mellitus and in obese people. Furthermore, it is much more likely to develop in patients with metabolic syndrome (MS), whose criteria include abdominal obesity, elevated blood triacylglycerol level, reduced high-density lipoprotein cholesterol level, increased blood pressure, and high fasting glucose. An important phenomenon in MS is also insulin resistance (IR), which is very common in NAFLD. Liver IR and NAFLD development are linked through an interaction between the accumulation of free fatty acids, hepatic inflammation, and increased oxidative stress. The liver is particularly exposed to elevated levels of reactive oxygen species due to a large number of mitochondria in hepatocytes. In these organelles, the main DNA repair pathway is base excision repair (BER). The present article will illustrate how impairment of BER may be related to the development of NAFLD.

MicroRNA-210 repression facilitates advanced glycation end-product (AGE)-induced cardiac mitochondrial dysfunction and apoptosis via JNK activation

Hyperglycemia results in the formation of reactive oxygen species which in turn causes advanced glycation end products (AGEs) formation, leading to diabetic cardiomyopathy. Our previous study showed that AGE-induced reactive oxygen species-dependent apoptosis is mediated via protein kinase C delta (PKCδ)-enhanced mitochondrial damage in cardiomyocytes. By using microRNA (miRNA) database, miRNA-210 was predicted to target c-Jun N-terminal kinase (JNK), which were previously identified as downstream of PKCδ in regulating mitochondrial function. Therefore, we hypothesized that miR-210 mediates PKCδ-dependent upregulation of JNK to cause cardiac mitochondrial damage and apoptosis following AGE exposure. AGE-exposed cells showed activated cardiac JNK, PKCδ, and apoptosis, which were reversed by treatment with a JNK inhibitor and PKCδ-KD (deficient kinase). Cardiac miR-210 and mitochondrial function were downregulated following AGE exposure. Furthermore, JNK was upregulated and involved in AGE-induced mitochondrial damage. Interestingly, luciferase activity of the miR-210 mimic plus JNK WT-3'-untranslated region overexpressed group was significantly lower than that of miR-210 mimic plus JNK MT-3'UTR group, indicating that JNK is a target of miR-210. Moreover, JNK activation induced by AGEs was reduced by treatment with the miR-210 mimic and reversed by treatment with the miR-210 inhibitor, indicating the regulatory function of miR-210 in JNK activation following AGE exposure. Additionally, JNK-dependent mitochondrial dysfunction and apoptosis were reversed following treatment with the miR-210 mimic, while the miR-210 inhibitor showed no effect on JNK-induced mitochondrial dysfunction and apoptosis in AGE-exposed cardiac cells. Taken together, our study showed that PKCδ-enhanced JNK-dependent mitochondrial damage is mediated through the reduction of miR-210 in cardiomyocytes following AGE exposure.

CHIP-overexpressing Wharton's jelly-derived mesenchymal stem cells attenuate hyperglycemia-induced oxidative stress-mediated kidney injuries in diabetic rats

Accumulating studies have demonstrated the protective roles of mesenchymal stem cells against several disorders. However, one of their crucial limitations is reduced viability under stress conditions, including the hyperglycemia induced by diabetes. The molecular mechanisms involved in diabetes-induced kidney injuries are not fully elucidated. In this study, we found that high glucose (HG) reduced human proximal tubular epithelial cell viability. Further, hyperglycemia induced oxidative stress-mediated apoptosis and fibrosis in HK-2 cells via activation of the mitogen-activated protein kinases (MAPKs) including c-Jun N-terminal kinase JNK and p38 kinase. Carboxyl terminus of HSP70 interacting protein (CHIP) overactivation considerably rescued cell viability under HG stress. Moreover, Western blot analysis, flow cytometry, and MitoSOX staining revealed that hyperglycemia-induced mitochondrial oxidative stress production and apoptosis were attenuated in CHIP-overexpressing Wharton's jelly-derived mesenchymal stem cells (WJMSCs). Co-culture with CHIP-expressing WJMSCs maintained HK-2 cell viability, and inhibited apoptosis and fibrosis by attenuating HG-induced ROS-mediated MAPK activation. CHIP-overexpressing WJMSCs also rescued the decreased kidney weight and hyperglycemia-induced kidney damage observed in streptozotocin-induced diabetic rats. Cumulatively, the current research findings demonstrate that CHIP suppresses hyperglycemia-induced oxidative stress and confers resistance to MAPK-induced apoptosis and fibrosis, and suggests that CHIP protects WJMSCs and the high quality WJMSCs have therapeutic effects against diabetes-induced kidney injuries.

Apocynin attenuates diabetic cardiomyopathy by suppressing ASK1-p38/JNK signaling

Diabetic cardiomyopathy (DCM) significantly increased the morbidity of heart failure in diabetic patients. Long-time oxidative stress is an indisputable contributor for DCM development. Apocynin (APO) has been suggested to be a potential drug against oxidative stress. The study aims to find out the effects of APO on DCM and the related mechanisms. Mice were randomly divided into four groups: control (CON), APO, DCM and DCM + APO. Echocardiography analyses, histological analyses, Western blot and RT-PCR were used to explore the roles and mechanisms of APO in DCM. Isolated neonatal rat cardiomyocytes (NRCMs) and cardiac fibroblasts (CFs) were used for further confirming the APO treatment effects in vitro. Deteriorated cardiac function, enlarged cardiomyocytes, excess cardiac fibrosis and significant cardiac oxidative stress were observed in DCM group. However, APO treatment successfully improved cardiac function, decreased cardiac hypertrophy and fibrosis, and depressed oxidative stress. Mechanistically, APO treatment markedly suppressed apoptosis signal regulating kinase 1(ASK1)-p38/c-jun N-terminal kinase (JNK) signaling and reduced apoptosis. It also inhibited NRCM apoptosis and CF activation via depressing ASK1-p38/JNK signaling in vitro. Moreover, adenovirus-mediated ASK1 overexpression completely removed the protection of APO in vitro. In conclusion, APO treatment could effectively attenuate DCM-associated injuries in vivo and protect against high glucose-induced NRCM and CF injuries in vitro via suppressing ASK1-p38/JNK signaling. APO might be a potential ASK1 inhibitor for treating DCM.

A SGLT2 Inhibitor Dapagliflozin Alleviates Diabetic Cardiomyopathy by Suppressing High Glucose-Induced Oxidative Stress in vivo and in vitro

Diabetic cardiomyopathy (DCM) is a serious complication of diabetes mellitus (DM). One of the hallmarks of the DCM is enhanced oxidative stress in myocardium. The aim of this study was to research the underlying mechanisms involved in the effects of dapagliflozin (Dap) on myocardial oxidative stress both in streptozotocin-induced DCM rats and rat embryonic cardiac myoblasts H9C2 cells exposed to high glucose (33.0 mM). In in vivo studies, diabetic rats were given Dap (1 mg/ kg/ day) by gavage for eight weeks. Dap treatment obviously ameliorated cardiac dysfunction, and improved myocardial fibrosis, apoptosis and oxidase stress. In in vitro studies, Dap also attenuated the enhanced levels of reactive oxygen species and cell death in H9C2 cells incubated with high glucose. Mechanically, Dap administration remarkably reduced the expression of membrane-bound nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits gp91phox and p22phox, suppressed the p67phox subunit translocation to membrane, and decreased the compensatory elevated copper, zinc superoxide dismutase (Cu/Zn-SOD) protein expression and total SOD activity both in vivo and in vitro. Collectively, our results indicated that Dap protects cardiac myocytes from damage caused by hyperglycemia through suppressing NADPH oxidase-mediated oxidative stress.

Therapeutic potential of targeting oxidative stress in diabetic cardiomyopathy

Even in the absence of coronary artery disease and hypertension, diabetes mellitus (DM) may increase the risk for heart failure development. This risk evolves from functional and structural alterations induced by diabetes in the heart, a cardiac entity termed diabetic cardiomyopathy (DbCM). Oxidative stress, defined as the imbalance of reactive oxygen species (ROS) has been increasingly proposed to contribute to the development of DbCM. There are several sources of ROS production including the mitochondria, NAD(P)H oxidase, xanthine oxidase, and uncoupled nitric oxide synthase. Overproduction of ROS in DbCM is thought to be counterbalanced by elevated antioxidant defense enzymes such as catalase and superoxide dismutase. Excess ROS in the cardiomyocyte results in further ROS production, mitochondrial DNA damage, lipid peroxidation, post-translational modifications of proteins and ultimately cell death and cardiac dysfunction. Furthermore, ROS modulates transcription factors responsible for expression of antioxidant enzymes. Lastly, evidence exists that several pharmacological agents may convey cardiovascular benefit by antioxidant mechanisms. As such, increasing our understanding of the pathways that lead to increased ROS production and impaired antioxidant defense may enable the development of therapeutic strategies against the progression of DbCM. Herein, we review the current knowledge about causes and consequences of ROS in DbCM, as well as the therapeutic potential and strategies of targeting oxidative stress in the diabetic heart.

Calcineurin A-α suppression drives nuclear factor-κB-mediated NADPH oxidase-2 upregulation

Calcineurin inhibitors (CNIs) are vital immunosuppressive therapies in the management of inflammatory conditions. A long-term consequence is nephrotoxicity. In the kidneys, the primary, catalytic calcineurin (CnA) isoforms are CnAα and CnAβ. Although the renal phenotype of CnAα-/- mice substantially mirrors CNI-induced nephrotoxicity, the mechanisms downstream of CnAα are poorly understood. Since NADPH oxidase-2 (Nox2)-derived oxidative damage has been implicated in CNI-induced nephrotoxicity, we hypothesized that CnAα inhibition drives Nox2 upregulation and promotes oxidative stress. To test the hypothesis, Nox2 regulation was investigated in kidneys from CnAα-/-, CnAβ-/-, and wild-type (WT) littermate mice. To identify the downstream mediator of CnAα, nuclear factor of activated T cells (NFAT) and NF-κB regulation was examined. To test if Nox2 is transcriptionally regulated via a NF-κB pathway, CnAα-/- and WT renal fibroblasts were treated with the NF-κB inhibitor caffeic acid phenethyl ester. Our findings showed that cyclosporine A treatment induced Nox2 upregulation and oxidative stress. Furthermore, Nox2 upregulation and elevated ROS generation occurred only in CnAα-/- mice. In these mice, NF-κB but not NFAT activity was increased. In CnAα-/- renal fibroblasts, NF-κB inhibition prevented Nox2 upregulation and reactive oxygen species (ROS) generation. In conclusion, these findings indicate that 1) CnAα loss stimulates Nox2 upregulation, 2) NF-κB is a novel CnAα-regulated transcription factor, and 3) NF-κB mediates CnAα-induced Nox2 and ROS regulation. Our results demonstrate that CnAα plays a key role in Nox2 and ROS generation. Furthermore, these novel findings provide evidence of divergent CnA isoform signaling pathways. Finally, this study advocates for CnAα-sparing CNIs, ultimately circumventing the CNI nephrotoxicity.NEW & NOTEWORTHY A long-term consequence of calcineurin inhibitors (CNIs) is oxidative damage and nephrotoxicity. This study indicates that NF-κB is a novel calcineurin-regulated transcription factor that is activated with calcineurin inhibition, thereby driving oxidative damage in CNI nephropathy. These findings provide additional evidence of divergent calcineurin signaling pathways and suggest that selective CNIs could improve the long-term outcomes of patients by mitigating renal side effects.

Bioactive compound from the Tibetan turnip (Brassica rapa L.) elicited anti-hypoxia effects in OGD/R-injured HT22 cells by activating the PI3K/AKT pathway

Cerebral stroke, a common clinical problem, is the predominant cause of disability and death worldwide. Its prevalence increases and infarctions exacerbate with age. A Tibetan plant, Brassica rapa L., possesses multiple medicinal effects, such as anti-altitude sickness, anti-hyperlipidemia and anti-fatigue, as mentioned in the noted ancient Tibet pharmacopeia "The Four Medical Tantras". Our preliminary studies also showed the anti-hypoxia protection mechanism of B. rapa L., implying its possible relationship with anti-ischemic neuroprotection. However, the potential molecular mechanism of the active constituent of turnip against cerebral ischemia/reperfusion remains unclear. In our study, oxidative stress markers, including LDH, ROS, SOD, GPx and CAT were assayed. In controlled in vitro assays, we found that the turnip's active constituent had remarkable anti-hypoxia capability. We further showed the profound effects of the active constituent of turnip on the levels of apoptosis-related proteins, including Bax, Bcl-2 and caspase-3, which contributed to its anti-inflammatory activity. Western blot analysis results also implied that active-constituent pretreatment reversed the diminished expression of the PI3K/Akt/mTOR pathway mediated by oxygen glucose deprivation/reperfusion (OGD/R); further experimental evidence showed that the protective role was limited in the PI3K inhibitor (LY294002) treatment group. Our results demonstrated that the functional monomer of B. rapa L. exerted a neuroprotective effect against OGD/R-induced HT22 cell injury, and its potential mechanism provides a scientific basis for future clinical applications and its use as a functional food.

Natural Antioxidant and Anti-Inflammatory Compounds in Foodstuff or Medicinal Herbs Inducing Heme Oxygenase-1 Expression

Heme oxygenase-1 (HO-1) is an inducible antioxidant enzyme that catalyzes heme group degradation. Decreased level of HO-1 is correlated with disease progression, and HO-1 induction suppresses development of metabolic and neurological disorders. Natural compounds with antioxidant activities have emerged as a rich source of HO-1 inducers with marginal toxicity. Here we discuss the therapeutic role of HO-1 in obesity, hypertension, atherosclerosis, Parkinson's disease and hepatic fibrosis, and present important signaling pathway components that lead to HO-1 expression. We provide an updated, comprehensive list of natural HO-1 inducers in foodstuff and medicinal herbs categorized by their chemical structures. Based on the continued research in HO-1 signaling pathways and rapid development of their natural inducers, HO-1 may serve as a preventive and therapeutic target for metabolic and neurological disorders.

Iron overload is related to elevated blood glucose levels in obese children and aggravates high glucose-induced endothelial cell dysfunction in vitro

INTRODUCTION

This study was performed to investigate the role of iron overload in the early stage of hyperglycemia-induced vascular functional impairment.

RESEARCH DESIGN AND METHODS

A total of 196 obese children were enrolled, and data regarding ferritin levels, blood glucose levels, intima-media thickness of carotid arteries, liver function and fibrosis index, hemoglobin, blood pressure, blood lipids, and inflammation indicators were collected. Ferritin levels were compared with a control group, which consisted of 148 healthy non-obese children who were age-matched and gender-matched. Endothelial cells were cultured in high glucose medium and supplemented with ferric citrate with or without iron remover (deferoxamine), a reducing agent (N-acetyl-cysteine), or a nuclear factor-κB (NF-κB) inhibitor (BAY 11-7082). Apoptosis, oxidative stress, nitric oxide levels, and endothelin content were evaluated. DNA microarray analysis was performed to analyze the expression of genes in the NF-κB signaling pathway.

RESULTS

Obese children have significantly higher ferritin levels compared with the control group. Ferritin level was positively correlated with hemoglobin and was related to metabolic disorders, including impaired glucose tolerance, higher blood pressure, dyslipidemia, and impaired hepatic function. Endothelial cells treated with ferric citrate showed a significantly higher rate of apoptosis, higher levels of oxidative stress, and impaired vasomotor function under high glucose conditions. The above effects were rescued by treatment with an iron remover, reducing agent, or NF-κB inhibitor. Further, detection of phosphorylated-p65 distribution in cells confirmed activation of the NF-κB pathway. DNA microarrays and subsequent gene oncology enrichment analyses revealed the main processes activated in cells.

CONCLUSION

Increased ferritin levels are related to impaired glucose tolerance and other metabolic disorders in obese children. At the cellular level, iron overload aggravated the endothelial cell dysfunction caused by high glucose.

Inhibition of long noncoding RNA MALAT1 suppresses high glucose-induced apoptosis and inflammation in human umbilical vein endothelial cells by suppressing the NF-κB signaling pathway

The study investigated the expression of long noncoding RNA (lncRNA) MALAT1 in high glucose (HG)-induced human vascular endothelial cells (HUVECs) and the role of MALAT1 in the apoptosis of HG-induced HUVECs. The HUVECs were cultured and induced with 25 mmol/L HG. After that, the HUVECs were transfected with MALAT1 siRNA. The expression levels of MALAT1 were detected with qPCR, whereas the expression levels of Bax, Bcl-2, cleaved-caspase-3, cleaved-caspase-9, p-65, and p-p65 were detected using Western blot. The roles of MALAT1 in cell activities, including apoptosis, were evaluated using the CCK-8 assay, TUNEL staining, and flow cytometry. The expression levels of inflammatory factors (TNF-α and IL-6) were measured using ELISA. The expression levels of MALAT1, TNF-α, and IL-6 in HUVECs were increased in the HG environment; however, when MALAT1 was silenced in the HUVECs, cell proliferation increased significantly, the expression levels of TNF-α, IL-6, Bax, cleaved-caspase-3, and cleaved-caspase-9 decreased, and the rate of apoptosis also decreased. Silencing MALAT1 inhibited the expression of p-p65 in HG-induced HUVECs. In conclusion, our study demonstrated that MALAT1 is upregulated in HG-induced HUVECs, and inhibition of MALAT1 inhibits HG-induced apoptosis and inflammation in HUVECs by suppression of the NF-κB signaling pathway.

DUSP19 mediates spinal cord injury-induced apoptosis and inflammation in mouse primary microglia cells via the NF-kB signaling pathway

Objective: Spinal cord injury (SCI) is a common injury that seriously threatens human health. NF-κB may be involved in the secondary injury of SCI that is mediated by inflammation and aggravates damage. Our study was aimed to investigate the role of NF-κB signaling in DUSP19-mediated cleaved Caspase-3 expression and the release of inflammatory factors in vivo and in vitro.Materials and Methods: DUSP19 mRNA expression and the content of IL-6 and IL-8 in patients with traumatic SCI (TSCI) were measured by real-time PCR and ELISA, respectively. The levels of p-NF-κBp65, NF-κBp65 and cleaved Caspase-3 expression and the concentrations of IL-6 and IL-8 were measured by western blotting and ELISA, respectively.Results: Patients with TSCI showed lower DUSP19 expression and higher concentration of IL-6 and IL-8 compared with healthy controls. DUSP19 overexpression inhibited p-NF-κBp65 level, cleaved Caspase-3 expression, and production of IL-8 and IL-6 in the mice induced by TSCI. DUSP19 silencing increased p-NF-κBp65 level, cleaved Caspase-3 expression, and concentration of IL-6 and IL-8 in mouse primary microglia cells. DUSP19 overexpression had an inverse effect. Importantly, DUSP19 silencing and overexpression mediated p-NF-κBp65 level, cleaved Caspase-3 expression, and concentration of IL-6 and IL-8 in mouse primary microglia cells were reversed by NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC) and NF-κB activator 12-myristate 13-acetate (PMA), respectively.Conclusion: These results suggested that DUSP19-mediated SCI-induced apoptosis and inflammation via NF-κB signaling and might therefore serve as a potential therapeutic target for SCI.

Diabetes-Induced NF-κB Dysregulation in Skeletal Stem Cells Prevents Resolution of Inflammation

Type 1 diabetes (T1D) imposes a significant health burden by negatively affecting tissue regeneration during wound healing. The adverse effect of diabetes is attributed to high levels of inflammation, but the cellular mechanisms responsible remain elusive. In this study, we show that intrinsic skeletal stem cells (SSCs), a subset of mesenchymal stem cells, are essential for resolution of inflammation to occur during osseous healing by using genetic approaches to selectively ablate SSCs. T1D caused aberrant nuclear factor-κB (NF-κB) activation in SSCs and substantially enhanced inflammation in vivo. Constitutive or tamoxifen-induced inhibition of NF-κB in SSCs rescued the impact of diabetes on inflammation, SSC expansion, and tissue formation. In contrast, NF-κB inhibition in chondrocytes failed to reverse the effect of T1D. Mechanistically, diabetes caused defective proresolving macrophage (M2) polarization by reducing TGF-β1 expression by SSCs, which was recovered by NF-κB inhibition or exogenous TGF-β1 treatment. These data identify an underlying mechanism for altered healing in T1D and demonstrate that diabetes induces NF-κB hyperactivation in SSCs to disrupt their ability to modulate M2 polarization and resolve inflammation.

LCZ696, an angiotensin receptor-neprilysin inhibitor, ameliorates diabetic cardiomyopathy by inhibiting inflammation, oxidative stress and apoptosis

Diabetic cardiomyopathy, which refers to the destruction of the structure and function of the heart, is the primary cause of heart failure due to diabetes. LCZ696 is the first angiotensin receptor-neprilysin inhibitor (ARNi) to be used clinically. Our study investigated the role played by LCZ696 during diabetic cardiomyopathy and explored the potential mechanisms underlying these effects. Diabetes was induced by injecting streptozotocin intraperitoneally into mice, and the mice were then divided randomly into two groups: one group was treated with LCZ696 (60 mg/kg/d) for 16 weeks, and the other received no treatment. The H9C2 cardiomyoblast cell line was treated with LCZ696 under high-glucose (HG) conditions. The levels of apoptotic (Bax, Bcl-2 and cleaved caspase-3) and pro-inflammatory factors [nuclear factor (NF)-κB, c-Jun N-terminal kinase (JNK) and p38 mitogen-activated kinase (MAPK)] were assessed in heart tissues from diabetic and normal mice and in H9C2 cells. The heart tissue structures and cardiac functions of diabetic mice were compared with those of normal mice, using histological and echocardiographic analyses. The results showed that LCZ696 inhibits the nuclear transfer of NF-κB and JNK/p38MAPK phosphorylation, and mitigates inflammation and apoptosis in diabetic mice and H9C2 cardiomyocytes under HG conditions. The histological and echocardiographic data showed that compared with untreated diabetic mice, diabetic mice treated with LCZ696 exhibited improved ventricular remodeling and cardiac function. LCZ696 also ameliorated oxidative stress in both vivo and vitro. In conclusion, LCZ696 improved diabetic cardiomyopathy by reducing cardiac inflammation, oxidative stress, and apoptosis.

Impact statement

Diabetic cardiomyopathy (DCM) is an important cause of heart failure in patients with diabetes, resulting in increased morbidity and mortality. LCZ696, which was studied here, is a novel drug for the treatment of heart failure. The latest research reports that LCZ696 is more effective for preventing heart failure than valsartan alone. However, little research has been performed examining the effects of LCZ696 on DCM. This study was designed to examine the role played by LCZ696 during DCM and the potential mechanisms underlying these effects, which may provide the basis for a new therapeutic strategy for DCM.

Hydrogen sulfide-mediated regulation of cell death signaling ameliorates adverse cardiac remodeling and diabetic cardiomyopathy

The death of cardiomyocytes is a precursor for the cascade of hypertrophic and fibrotic remodeling that leads to cardiomyopathy. In diabetes mellitus (DM), the metabolic environment of hyperglycemia, hyperlipidemia, and oxidative stress causes cardiomyocyte cell death, leading to diabetic cardiomyopathy (DMCM), an independent cause of heart failure. Understanding the roles of the cell death signaling pathways involved in the development of cardiomyopathies is crucial to the discovery of novel targeted therapeutics and biomarkers for DMCM. Recent evidence suggests that hydrogen sulfide (H2S), an endogenous gaseous molecule, has cardioprotective effects against cell death. However, very little is known about signaling by which H2S and its downstream targets regulate myocardial cell death in the DM heart. This review focuses on H2S in the signaling of apoptotic, autophagic, necroptotic, and pyroptotic cell death in DMCM and other cardiomyopathies, abnormalities in H2S synthesis in DM, and potential H2S-based therapeutic strategies to mitigate myocardial cell death to ameliorate DMCM.

Activation of the PP2A catalytic subunit by ivabradine attenuates the development of diabetic cardiomyopathy

Hyperglycemia-induced apoptosis plays a critical role in the pathogenesis of diabetic cardiomyopathy (DCM). Our previous study demonstrated that ivabradine, a selective I_f current antagonist, significantly attenuated myocardial apoptosis in diabetic mice, but the underlying mechanisms remained unknown. This study investigated the underlying mechanisms by which ivabradine exerts anti-apoptotic effects in experimental DCM. Pretreatment with ivabradine, but not ZD7288 (an established I_f current blocker), profoundly inhibited high glucose-induced apoptosis via inactivation of nuclear factor (NF)-κB signaling in neonatal rat cardiomyocytes. The effect was abolished by transfection of an siRNA targeting protein phosphatase 2A catalytic subunit (PP2Ac). In streptozotocin-induced diabetic mice, ivabradine treatment significantly inhibited left ventricular hyperpolarization-activated cyclic nucleotide-gated channel 2 (HCN2) and HCN4 (major components of the I_f current), activated PP2Ac, and attenuated NF-κB signaling activation and apoptosis, in line with improved histological abnormalities, fibrosis, and cardiac dysfunction without affecting hyperglycemia. These effects were not observed in diabetic mice with virus-mediated knockdown of HCN2 or HCN4 after myocardial injection, but were alleviated by knockdown of PP2Acα. Molecular docking and phosphatase activity assay confirmed direct binding of ivabradine to, and activation of, PP2Ac. In conclusion, ivabradine may directly activate PP2Ac, leading to inhibition of NF-κB signaling activation, myocardial apoptosis, and fibrosis, and eventually improving cardiac function in experimental DCM. Taken together, the present findings suggest that ivabradine may be a promising drug for treatment of DCM.

Envolvimento da inflamação subclínica e do estresse oxidativo na resistência à insulina associada a obesidade

A epidemia global da obesidade é um dos mais importantes problemas de saúde pública. Excessiva adiposidade é um crucial fator de risco no surgimento de várias doenças metabólicas, incluindo hipertensão, diabetes mellitus do tipo 2 e doença do fígado gorduroso não alcoólico.  Essas condições patológicas estão estritamente associadas com a resistência à insulina. Baseado nos esforços das últimas décadas, ocorreu marcante desenvolvimento na investigação sobre resistência à insulina induzida pela obesidade, especialmente em termos do mecanismo envolvido neste processo. Dentre esses, a inflamação subclínica ou crônica de baixo grau na obesidade tem sido o mais aceito. Este estado inflamatório é caracterizado por altos níveis circulantes de citocinas inflamatórias, incluindo TNF alfa e IL beta, e aumentado infiltração de macrófagos em tecidos periféricos. No entanto, recentemente, tem ocorrido grande interesse no papel que o estresse oxidativo desempenha na indução da resistência à insulina. Sob ativação, muitas células imunes geram radicais livres e, da mesma maneira, a síntese de espécies reativas de oxigênio promovem um status inflamatório. Estudos têm mostrado níveis elevados de espécies reativas e estresse oxidativo em indivíduos e animais obesos e/ou resistentes a insulina; isso parece estar associado a redução da função e da atividade e biogênese mitocondrial causada pelo aumento de lipídeos circulantes e maior deposição de gordura ectópica.  Essa revisão discorre sobre o mecanismo fisiopatológico de como a inflamação subclínica induz resistência à insulina na obesidade. Ainda, descreve o papel que o estresse oxidativo desempenha neste processo, bem como a produção de radicais livres na obesidade.

ROS- and HIF1α-dependent IGFBP3 upregulation blocks IGF1 survival signaling and thereby mediates high-glucose-induced cardiomyocyte apoptosis

The prevalence of chronic hyperglycemia and its complications, imposing a critical burden on the worldwide economy and the global healthcare system, is a pressing issue. Mounting evidence indicates that oxidative stress and hypoxia, two noticeable features of hyperglycemia, play a joint crucial role in mediating cellular apoptosis. However, the underlying detailed molecular mechanism remains elusive. Triggered by the observation that insulin-like growth factor (IGF1)-binding protein 3 (IGFBP3) can mediate, in renal cells, high-glucose-induced apoptosis by elevating oxidative stress, we wish to, in this study, know whether or not the similar scenario holds in cardiac cells and, if so, to find its relevant molecular key players, thereby dissecting the underlying molecular pathway. Specifically, we used a combination of three different cellular sources (H9c2 cells, diabetic rats, and neonatal rat ventricular cardiomyocytes) as our model systems of study. We made use of Co-IP assay and western blot analysis in conjunction with loss-of-function reasoning, gain-of-function logic, and inhibitor treatment as our main analytical tools. As a result, briefly, our main findings are that hyperglycemia can induce cardiac IGFBP3 overexpression and secretion, that high levels of IGFBP3 can sequester IGF1 from IGF1 survival pathway, leading to apoptosis, and that IGFBP3 gene upregulation is hypoxia-inducible factor (HIF)1α-dependent and reactive oxygen species dependent. Piecing these findings together allows us to propose the improved molecular regulatory mechanism. In conclusion, we have established the molecular roles of IGFBP3, HIF1, and prolyl hydroxylase domain in connecting oxidative stress with hypoxia and in cellular apoptosis under hyperglycemia.

Toxic effect of high glucose on cardiomyocytes, H9c2 cells: Induction of oxidative stress and ameliorative effect of trolox

Oxidative stress (OS) has been implicated in a variety of pathological conditions, including diabetes mellitus, characterized by hyperglycemia. In the present study, OS induced by hyperglycemia and the effect of trolox, a vitamin E analog, were studied in cardiomyocytes and H9c2 cells exposed to 15 to 33 mM glucose (HG) for 24 to 72 hours in Dulbecco modified Eagle medium. Cells treated wirh 24 or 33 mM glucose for 24 hours or above showed decreased viability and adenosine triphosphate (ATP) content with a concomitant increase in radicals of oxygen species, calcium (Ca²⁺ ), mitochondrial permeability transition, and oxidative markers, confirming that the cells were under stress. However, upon exposure to 15 mM glucose for 24 hours, H9c2 cells maintained homeostasis and ATP generation. Pretreatment of cells with trolox reduced HG-induced OS to control levels. Here, we report that the toxic effect of HG is highly regulated and that OS induction can be prevented with Trolox, a potential inhibitor of membrane damage.

Lysophosphatidylcholine induces cyclooxygenase-2-dependent IL-6 expression in human cardiac fibroblasts

Lysophosphatidylcholine (LysoPC) has been shown to induce the expression of inflammatory proteins, including cyclooxygenase-2 (COX-2) and interleukin-6 (IL-6), associated with cardiac fibrosis. Here, we demonstrated that LysoPC-induced COX-2 and IL-6 expression was inhibited by silencing NADPH oxidase 1, 2, 4, 5; p65; and FoxO1 in human cardiac fibroblasts (HCFs). LysoPC-induced IL-6 expression was attenuated by a COX-2 inhibitor. LysoPC-induced responses were mediated via the NADPH oxidase-derived reactive oxygen species-dependent JNK1/2 phosphorylation pathway, leading to NF-κB and FoxO1 activation. In addition, we demonstrated that both FoxO1 and p65 regulated COX-2 promoter activity stimulated by LysoPC. Overexpression of wild-type FoxO1 and S256D FoxO1 enhanced COX-2 promoter activity and protein expression in HCFs. These results were confirmed by ex vivo studies, where LysoPC-induced COX-2 and IL-6 expression was attenuated by the inhibitors of NADPH oxidase, NF-κB, and FoxO1. Our findings demonstrate that LysoPC-induced COX-2 expression is mediated via NADPH oxidase-derived reactive oxygen species generation linked to the JNK1/2-dependent pathway leading to FoxO1 and NF-κB activation in HCFs. LysoPC-induced COX-2-dependent IL-6 expression provided novel insights into the therapeutic targets of the cardiac fibrotic responses.

Mn Porphyrin-Based Redox-Active Drugs: Differential Effects as Cancer Therapeutics and Protectors of Normal Tissue Against Oxidative Injury

SIGNIFICANCE

After approximatelty three decades of research, two Mn(III) porphyrins (MnPs), MnTE-2-PyP⁵⁺ (BMX-010, AEOL10113) and MnTnBuOE-2-PyP⁵⁺ (BMX-001), have progressed to five clinical trials. In parallel, another similarly potent metal-based superoxide dismutase (SOD) mimic-Mn(II)pentaaza macrocycle, GC4419-has been tested in clinical trial on application, identical to that of MnTnBuOE-2-PyP⁵⁺-radioprotection of normal tissue in head and neck cancer patients. This clearly indicates that Mn complexes that target cellular redox environment have reached sufficient maturity for clinical applications. Recent Advances: While originally developed as SOD mimics, MnPs undergo intricate interactions with numerous redox-sensitive pathways, such as those involving nuclear factor κB (NF-κB) and nuclear factor E2-related factor 2 (Nrf2), thereby impacting cellular transcriptional activity. An increasing amount of data support the notion that MnP/H₂O₂/glutathione (GSH)-driven catalysis of S-glutathionylation of protein cysteine, associated with modification of protein function, is a major action of MnPs on molecular level.

CRITICAL ISSUES

Differential effects of MnPs on normal versus tumor cells/tissues, which support their translation into clinic, arise from differences in their accumulation and redox environment of such tissues. This in turn results in different yields of MnP-driven modifications of proteins. Thus far, direct evidence for such modification of NF-κB, mitogen-activated protein kinases (MAPK), phosphatases, Nrf2, and endogenous antioxidative defenses was provided in tumor, while indirect evidence shows the modification of NF-κB and Nrf2 translational activities by MnPs in normal tissue.

FUTURE DIRECTIONS

Studies that simultaneously explore differential effects in same animal are lacking, while they are essential for understanding of extremely intricate interactions of metal-based drugs with complex cellular networks of normal and cancer cells/tissues.

Inhibition of TRAF3 expression alleviates cardiac ischemia reperfusion (IR) injury: A mechanism involving in apoptosis, inflammation and oxidative stress

Ischemia reperfusion (IR) injury is known as a major issue in cardiac transplantation and various pathogenesis are involved in myocardial IR injury. Here, we show that tumor necrosis factor receptor-associated factor 3 (TRAF3) was increased in hearts of mice with cardiac IR injury and in cardiomyocytes incubated with lipopolysaccharide (LPS) and H₂O₂. Reducing TRAF3 expression in vivo markedly reduced the infacrted area, attenuated the histological changes, improved cardiac dysfunction and injury in mice subjected to IR injury. Functional study further indicated that TRAF3 knockdown inhibited apoptosis in murine hearts of mice with cardiac IR injury and in LPS and H₂O₂-cotreated cardiomyocytes, as evidenced by the decreased expression of cleaved Caspase-3 and poly (ADP-ribose) polymerases (PARP). In addition, inflammatory response and oxidative stress observed in hearts of mice with IR operation were significantly alleviated by TRAF3 knockdown through inhibiting nuclear factor-κB (NF-κB) and xanthine oxidase (XO) signaling pathways, and similar results were detected in LPS and H₂O₂-cotreated cardiomyocytes in vitro. Moreover, the loss of TRAF3 also restrained the phosphorylated c-Jun N-terminal protein kinase (JNK) activation following cardiac IR injury. Importantly, blocking JNK activation, as TRAF3 knockdown, greatly reduced apoptosis, inflammation and reactive oxygen species (ROS) production in LPS and H₂O₂-cotreated cardiomyocytes. In contrast, TRAF3 knockdown-reduced apoptosis, inflammatory response and oxidative stress were significantly rescued by promoting JNK activity in LPS and H₂O₂-cotreated cardiomyocytes. In summary, the results of our study indicated that repressing TRAF3 expression could be served as essential therapeutic target for protection against cardiac IR injury through restraining JNK-meditated apoptosis, inflammation and the production of ROS.

Pkcδ Activation is Involved in ROS-Mediated Mitochondrial Dysfunction and Apoptosis in Cardiomyocytes Exposed to Advanced Glycation End Products (Ages)

Diabetic patients exhibit serum AGE accumulation, which is associated with reactive oxygen species (ROS) production and diabetic cardiomyopathy. ROS-induced PKCδ activation is linked to mitochondrial dysfunction in human cells. However, the role of PKCδ in cardiac and mitochondrial dysfunction caused by AGE in diabetes is still unclear. AGE-BSA-treated cardiac cells showed dose- and time-dependent cell apoptosis, ROS generation, and selective PKCδ activation, which were reversed by NAC and rotenone. Similar tendency was also observed in diabetic and obese animal hearts. Furthermore, enhanced apoptosis and reduced survival signaling by AGE-BSA or PKCδ-WT transfection were reversed by kinase-deficient (KD) of PKCδ transfection or PKCδ inhibitor, respectively, indicating that AGE-BSA-induced cardiomyocyte death is PKCδ-dependent. Increased levels of mitochondrial mass as well as mitochondrial fission by AGE-BSA or PKCδ activator were reduced by rottlerin, siPKCδ or KD transfection, indicating that the AGE-BSA-induced mitochondrial damage is PKCδ-dependent. Using super-resolution microscopy, we confirmed that PKCδ colocalized with mitochondria. Interestingly, the mitochondrial functional analysis by Seahorse XF-24 flux analyzer showed similar results. Our findings indicated that cardiac PKCδ activation mediates AGE-BSA-induced cardiomyocyte apoptosis via ROS production and may play a key role in the development of cardiac mitochondrial dysfunction in rats with diabetes and obesity.

Exendin-4 and Liraglutide Attenuate Glucose Toxicity-Induced Cardiac Injury through mTOR/ULK1-Dependent Autophagy

Mitochondrial injury and defective autophagy are common in diabetic cardiomyopathy. Recent evidence supports benefits of glucagon-like peptide-1 (GLP-1) agonists exendin-4 (Exe) and liraglutide (LIRA) against diabetic cardiomyopathy. This study was designed to examine the effect of Exe and LIRA on glucose-induced cardiomyocyte and mitochondrial injury, oxidative stress, apoptosis, and autophagy change. Cardiomyocytes isolated from adult mice and H9c2 myoblast cells were exposed to high glucose (HG, 33 mM) with or without Exe or LIRA. Cardiac contractile properties were assessed including peak shortening, maximal velocity of shortening/relengthening (±dL/dt), time to PS, and time-to-90% relengthening (TR₉₀). Superoxide levels, apoptotic proteins such as cleaved caspase-3, Bax, and Bcl-2, and autophagy proteins including Atg5, p62, Beclin-1, LC3B, and mTOR/ULK1 were evaluated using Western blot. Mitochondrial membrane potential (MMP) changes were assessed using JC-1, and autophagosomes were determined using GFP-LC3. Cardiomyocyte exposure to HG exhibited prolonged TR₉₀ associated with significantly decreased PS and ±dL/dt, the effects of which were partly restored by GLP-1 agonists, the effects of which were negated by the mTOR activator 3BDO. H9c2 cell exposure to HG showed increased intracellular ROS, apoptosis, MMP loss, dampened autophagy, and elevated p-mTOR and p-ULK1, the effects of which were nullified by the GLP-1 agonists. These results suggested that GLP-1 agonists rescued glucose toxicity likely through induction of mTOR-dependent autophagy.

Spirulina platensis prevents high glucose-induced oxidative stress mitochondrial damage mediated apoptosis in cardiomyoblasts

The current study was undertaken to study the effect of Spirulina platensis (Spirulina) extract on enhanced oxidative stress during high glucose induced cell death in H9c2 cells. H9c2 cultured under high glucose (33 mM) conditions resulted in a noteworthy increase in oxidative stress (free radical species) accompanied by loss of mitochondrial membrane potential, release of cytochrome c, increase in caspase activity and pro-apoptotic protein (Bax). Spirulina extract (1 μg/mL), considerably inhibited increased ROS and RNS levels, reduction in cytochrome c release, raise in mitochondrial membrane potential, decreased the over expression of proapoptotic protein Bax and suppressed the Bax/Bcl2 ratio with induced apoptosis without affecting cell viability. Overall results suggest that Spirulina extract plays preventing role against enhanced oxidative stress during high glucose induced apoptosis in cardiomyoblasts as well as related dysfunction in H9c2 cells.

Phosphene perception is due to the ultra-weak photon emission produced in various parts of the visual system: glutamate in the focus

Phosphenes are experienced sensations of light, when there is no light causing them. The physiological processes underlying this phenomenon are still not well understood. Previously, we proposed a novel biopsychophysical approach concerning the cause of phosphenes based on the assumption that cellular endogenous ultra-weak photon emission (UPE) is the biophysical cause leading to the sensation of phosphenes. Briefly summarized, the visual sensation of light (phosphenes) is likely to be due to the inherent perception of UPE of cells in the visual system. If the intensity of spontaneous or induced photon emission of cells in the visual system exceeds a distinct threshold, it is hypothesized that it can become a conscious light sensation. Discussing several new and previous experiments, we point out that the UPE theory of phosphenes should be really considered as a scientifically appropriate and provable mechanism to explain the physiological basis of phosphenes. In the present paper, we also present our idea that some experiments may support that the cortical phosphene lights are due to the glutamate-related excess UPE in the occipital cortex.

Diallyl trisulfide suppresses doxorubicin-induced cardiomyocyte apoptosis by inhibiting MAPK/NF-κB signaling through attenuation of ROS generation

BACKGROUND

Doxorubicin (Dox) is an effective anticancer agent. However, its effectiveness is limited by its cardiotoxic effects. It has also been reported that the mitogen-activated protein kinase family and NF-κB can be activated by Dox treatment. DATS has been shown to be a potent antioxidant with cardioprotective effects. We investigate whether Dox induces cardiac apoptosis through JNK- and ERK-dependent NF-κB upregulation that can be reduced by DATS treatment.

METHODS AND MATERIAL

H9c2 cells were treated with 0.5-1.5 μM Dox for 24 hours. Dox promoted apoptosis and ROS generation and inhibited viability in a dose-dependent manner. Then, the phosphorylation levels of JNK, ERK, and NF-κB evaluated by western blot were elevated. We used inhibitors of JNK, ERK, and NF-κB to determine which of these proteins were involved in Dox-induced apoptosis. Furthermore, Dox-exposed cells were treated with DATS at doses of 1, 5, and 10 μM, and the data demonstrated that ROS generation and apoptotic proteins were decreased and that ERK and NF-κB were downregulated in a dose-dependent manner. Additionally, six-week-old rats were divided into three groups (n = 6 per group) designed as an eight-week study. Normal, Dox (at dose 3.75 mg/kg by ip) administered with or without DATS (at dose 40 mg/kg by gavage) treatment groups. The results indicate that cardiac dysfunction, apoptosis, and JNK, ERK, and NF-κB activation by Dox were reversed by treatment with DATS.

CONCLUSION

DATS appears to suppress Dox-induced cardiomyocyte apoptosis by inhibiting NADPH oxidase-related ROS production and the downstream JNK/ERK/NF-κB signaling pathway; DATS may possess clinical therapeutic potential by blocking Dox-induced cardiotoxicity.

The etiology of oxidative stress in insulin resistance

Insulin resistance is a prevalent syndrome in developed as well as developing countries. It is the predisposing factor for type 2 diabetes mellitus, the most common end stage development of metabolic syndrome in the United States. Previously, studies investigating type 2 diabetes have focused on beta cell dysfunction in the pancreas and insulin resistance, and developing ways to correct these dysfunctions. However, in recent years, there has been a profound interest in the role that oxidative stress in the peripheral tissues plays to induce insulin resistance. The objective of this review is to focus on the mechanism of oxidative species generation and its direct correlation to insulin resistance, to discuss the role of obesity in the pathophysiology of this phenomenon, and to explore the potential of antioxidants as treatments for metabolic dysfunction.

[Clinical characteristics and prognostic analysis of children with congenital heart disease complicated by postoperative acute kidney injury]

OBJECTIVE

To analyze the perioperative clinical data of children with congenital heart disease complicated by acute kidney injury (AKI) after cardiopulmonary bypass (CPB) surgery, and to explore potential factors influencing the prognosis.

METHODS

A retrospective analysis was performed among 118 children with congenital heart disease who developed AKI within 48 hours after CPB surgery.

RESULTS

In the 118 patients, 18 died after 48 hours of surgery. Compared with the survivors, the dead children had significantly higher incidence of cyanotic disease and Risk Adjustment for Congenital Heart Surgery-1 (RACHS-1) scores before surgery; during surgery, the dead children had significantly longer CPB time and aortic cross-clamping time, a significantly higher proportion of patients receiving crystalloid solution for myocardial protection, and a significantly higher mean blood glucose level. Within 48 hours after surgery, the dead children had significantly higher positive inotropic drug scores, significantly higher creatinine values, a significantly higher incidence of stage 3 AKI, a significantly higher proportion of patients receiving renal replacement the, and significantly higher usage of blood products (P<0.05). The mortality rate of the patients increased with increased intraoperative blood glucose levels (P<0.05). Patients with intraoperative blood glucose levels >8.3 mmol/L had a significantly lower postoperative cumulative survival rate and a significantly shorter mean survival time than those with blood glucose levels ≤ 8.3 mmol/L (P<0.05).

CONCLUSIONS

Intraoperative blood glucose levels are associated with the prognosis in children with congenital heart disease complicated by AKI after CPB surgery. Maintaining good intraoperative blood glucose control can improve the prognosis of the children.

Roles and Mechanisms of Herbal Medicine for Diabetic Cardiomyopathy: Current Status and Perspective

Diabetic cardiomyopathy is one of the major complications among patients with diabetes mellitus. Diabetic cardiomyopathy (DCM) is featured by left ventricular hypertrophy, myocardial fibrosis, and damaged left ventricular systolic and diastolic functions. The pathophysiological mechanisms include metabolic-altered substrate metabolism, dysfunction of microvascular, renin-angiotensin-aldosterone system (RAAS) activation, oxidative stress, cardiomyocyte apoptosis, mitochondrial dysfunction, and impaired Ca²⁺ handling. An array of molecules and signaling pathways such as p38 mitogen-activated protein kinase (p38 MAPK), c-Jun N-terminal kinase (JNK), and extracellular-regulated protein kinases (ERK) take roles in the pathogenesis of DCM. Currently, there was no remarkable effect in the treatment of DCM with application of single Western medicine. The myocardial protection actions of herbs have been gearing much attention. We present a review of the progress research of herbal medicine as a potential therapy for diabetic cardiomyopathy and the underlying mechanisms.

Liver X receptor α is targeted by microRNA-1 to inhibit cardiomyocyte apoptosis through a ROS-mediated mitochondrial pathway

Diabetic cardiomyopathy (DCM) is defined as ventricular dysfunction occurring independently of a recognized cause such as hypertension or coronary artery disease. Liver X receptor α (LXRα), a subtype of ligand-activated transcription factors LXRs, has been considered as a potential pharmacological target in the pathogenesis of cardiovascular and metabolic diseases. However, the potential mechanism of how LXRα is regulated in cardiomyocytes is still unclear. This study investigated the effect of activating LXRα with GW3965 on cardiomyocyte apoptosis and its upstream regulator in glucose-induced H9C2 cells. Our data indicated that GW3965 up-regulated the expression of LXRα, inhibited cardiomyocyte apoptosis, and altered the apoptosis-related proteins in glucose-induced H9C2 cells. In addition, GW3965 restored the mitochondrial membrane potential level and decreased the ROS production induced by glucose. Moreover, LXRα was confirmed as a direct target of microRNA-1 (miR-1) that was involved in cardiomyocyte apoptosis of DCM, and overexpression of miR-1 abrogated the inhibiting effect of GW3965 on glucose-induced apoptosis in H9C2 cells. This study highlights an important role of LXRα in the development of DCM and brings new insights into the complex mechanisms involved in the pathogenesis of DCM.

The effect of Astragalus polysaccharides on attenuation of diabetic cardiomyopathy through inhibiting the extrinsic and intrinsic apoptotic pathways in high glucose -stimulated H9C2 cells

Background

Apoptosis plays a critical role in the progression of diabetic cardiomyopathy (DC). Astragalus polysaccharides (APS), an extract of astragalus membranaceus (AM), is an effective cardioprotectant. Currently, little is known about the detailed mechanisms underlying cardioprotective effects of APS. The aims of this study were to investigate the potential effects and mechanisms of APS on apoptosis employing a model of high glucose induction of apoptosis in H9C2 cells.

Methods

A model of high glucose induction of H9C2 cell apoptosis was adopted in this research. The cell viabilities were analyzed by MTT assay, and the apoptotic response was quantified by flow cytometry. The expression levels of the apoptosis related proteins were determined by Real-time PCR and western blotting.

Results

Incubation of H9C2 cells with various concentrations of glucose (i.e., 5.5, 12.5, 25, 33 and 44 mmol/L) for 24 h revealed that cell viability was reduced by high glucose dose-dependently. Pretreatment of cells with APS could inhibit high glucose-induced H9C2 cell apoptosis by decreasing the expressions of caspases and the release of cytochrome C from mitochondria to cytoplasm. Further experiments also showed that APS could modulate the ratio of Bcl-2 to Bax in mitochondria.

Conclusions

APS decreases high glucose-induced H9C2 cell apoptosis by inhibiting the expression of pro-apoptotic proteins of both the extrinsic and intrinsic pathways and modulating the ratio of Bcl-2 to Bax in mitochondria.

Polydatin reduces Staphylococcus aureus lipoteichoic acid-induced injury by attenuating reactive oxygen species generation and TLR2-NFκB signalling

Staphylococcus aureus (S. aureus) causes severe inflammation in various infectious diseases, leading to high mortality. The clinical application of antibiotics has gained a significant curative effect. However, it has led to the emergence of various resistant bacteria. Therefore, in this study, we investigated the protective effect of polydatin (PD), a traditional Chinese medicine extract, on S. aureus lipoteichoic acid (LTA)-induced injury in vitro and in vivo. First, a significant improvement in the pathological conditions of PD in vivo was observed, suggesting that PD had a certain protective effect on LTA-induced injury in a mouse model. To further explore the underlying mechanisms of this protective effect of PD, LTA-induced murine macrophages were used in this study. The results have shown that PD could reduce the NF-κB p65, and IκBα phosphorylation levels increased by LTA, resulting in a decrease in the transcription of pro-inflammatory factors, such as TNF-α, IL-1β and IL-6. However, LTA can not only activate NF-κB through the recognition of TLR2 but also increase the level of intracellular reactive oxygen species (ROS), thereby activating NF-κB signalling. We also detected high levels of ROS that activate caspases 9 and 3 to induce apoptosis. In addition, using a specific NF-κB inhibitor that could attenuate apoptosis, namely NF-κB p65, acted as a pro-apoptotic transcription factor in LTA-induced murine macrophages. However, PD could inhibit the generation of ROS and NF-κB p65 activation, suggesting that PD suppressed LTA-induced injury by attenuating ROS generation and TLR2-NFκB signalling.

A systems genetics approach identifies Trp53inp2 as a link between cardiomyocyte glucose utilization and hypertrophic response

Cardiac failure has been widely associated with an increase in glucose utilization. The aim of our study was to identify factors that mechanistically bridge this link between hyperglycemia and heart failure. Here, we screened the Hybrid Mouse Diversity Panel (HMDP) for substrate-specific cardiomyocyte candidates based on heart transcriptional profile and circulating nutrients. Next, we utilized an in vitro model of rat cardiomyocytes to demonstrate that the gene expression changes were in direct response to substrate abundance. After overlaying candidates of interest with a separate HMDP study evaluating isoproterenol-induced heart failure, we chose to focus on the gene Trp53inp2 as a cardiomyocyte glucose utilization-specific factor. Trp53inp2 gene knockdown in rat cardiomyocytes reduced expression and protein abundance of key glycolytic enzymes. This resulted in reduction of both glucose uptake and glycogen content in cardiomyocytes stimulated with isoproterenol. Furthermore, this reduction effectively blunted the capacity of glucose and isoprotereonol to synergistically induce hypertrophic gene expression and cell size expansion. We conclude that Trp53inp2 serves as regulator of cardiomyocyte glycolytic activity and can consequently regulate hypertrophic response in the context of elevated glucose content.NEW & NOTEWORTHY Here, we apply a novel method for screening transcripts based on a substrate-specific expression pattern to identify Trp53inp2 as an induced cardiomyocyte glucose utilization factor. We further show that reducing expression of the gene could effectively blunt hypertrophic response in the context of elevated glucose content.