Inhibition of JNK phosphorylation by a novel curcumin analog prevents high glucose-induced inflammation and apoptosis in cardiomyocytes and the development of diabetic cardiomyopathy

Curcumin and dietary polyphenol research: beyond drug discovery

Numerous natural products available over the counter are commonly consumed by healthy, sub-healthy or ill people for the treatment and prevention of various chronic diseases. Among them, a few dietary polyphenols, including the curry compound curcumin, have been attracting the most attention from biomedical researchers and drug developers. Unlike many so-called "good drug candidates", curcumin and several other dietary polyphenols do not have a single known therapeutic target or defined receptor. In addition, the bioavailability of these polyphenols is usually very low due to their poor absorption in the gut. These recently debated features have created enormous difficulties for drug developers. In this review, I do not discuss how to develop curcumin, other dietary polyphenols or their derivatives into pharmaceutical agents. Instead, I comment on how curcumin and dietary polyphenol research has enriched our knowledge of insulin signaling, including the presentation of my perspectives on how these studies will add to our understanding of the famous hepatic insulin function paradox.

Activation of adenosine A2b receptor attenuates high glucose-induced apoptosis in H9C2 cells via PI3K/Akt signaling

High glucose plays a vital role in apoptosis in H9C2 cells. However, the exact molecular mechanism remains unclear. In this study, we aimed to evaluate the cardio-protective role of A2b receptor in high glucose-induced cardiomyocyte apoptosis via PI3K/Akt pathway. Adenosine A2b receptor agonist (Bay506583), antagonist (MRS1754), and Akt inhibitor (LY294002) were applied respectively to H9C2 cells before exposed to high glucose for 12 h. Apoptosis of H9C2 cells was determined by TUNEL assay and the apoptosis rate by flow cytometry. The protein level of adenosine A2b receptor, p-Akt, total Akt, cleaved capase-3, cleaved capase-9, bax, and bcl-2 was measured by western blotting. The results demonstrated that apoptosis of H9C2 cardiomyocytes triggered by high-glucose treatment was time-dependent. The protein level of A2b receptor and activated Akt was both decreased in cardiomyocyte with high-glucose treatment. Moreover, we found that high glucose-induced apoptosis in H9C2 cells could be attenuated by administration of adenosine A2b receptor agonist Bay606583. This effect could be reversed by Akt inhibitor LY294002. In conclusion, activation of A2b receptor could prevent high glucose-induced apoptosis of H9C2 cells in vitro to a certain extent by activating PI3K/Akt signaling. In conclusion, these results suggested that activation of A2b receptor could be a novel therapeutic approach to high glucose-induced cardiomyocyte injury.

CFTR ameliorates high glucose-induced oxidative stress and inflammation by mediating the NF-κB and MAPK signaling pathways in endothelial cells

Diabetic cardiovascular diseases are characterized by progressive hyperglycemia, which results in excessive production of oxidative stress and pro-inflammatory cytokines. Cystic fibrosis (CF) is characterized by chronic inflammation due to mutations in CF transmembrane conductance regulator (CFTR). However, little information is available about the role of CFTR in hyperglycemia‑induced endothelial cell oxidative stress and inflammation. In the present study, a high glucose‑treatment was applied in human umbilical vein endothelial cells with CFTR overexpression or inhibition, and the oxidative and inflammatory characteristics were measured. It was shown that CFTR protein and mRNA expression were reduced by glucose in a concentration‑dependent manner. Overexpression of CFRT via adenoviral infection significantly inhibited the production of reactive oxygen species and inflammatory biomediators induced by high glucose. Conversely, pharmacological inhibition of CFTR led to the opposite effects. Mechanistically, nuclear factor‑κB (NF‑κB) and mitogen‑activated protein kinase (MAPK) signaling were activated following high glucose treatment, which were inhibited by CFTR overexpression and enhanced by CFTR inhibition. The pro‑inflammatory effect of CFTR inhibition was abolished by pharmacological inhibition of the NF‑κB or MAPK pathways. Moreover, inhibition of MAPK abrogated CFTR inhibition‑induced NF‑κB nuclear translocation, whereas NF‑κB inhibitor produced no effects on MAPK activation. Additionally, antioxidant treatment inhibited the high glucose‑induced decrease in CFTR expression and the increase in inflammatory responses. Collectively, these findings revealed that CFTR attenuates high glucose‑induced endothelial cell oxidative stress and inflammation through inactivation of NF‑κB and MAPK signaling, indicating that elevation of CFRT expression may be a novel strategy in preventing endothelial dysfunction in diabetes.

Ginkgo biloba Leaf Extract Protects against Myocardial Injury via Attenuation of Endoplasmic Reticulum Stress in Streptozotocin-Induced Diabetic ApoE-/- Mice

Diabetes was induced in high-fat diet-fed ApoE^−/− mice via administration of low-dose streptozotocin (STZ) for five days. Mice were then treated with GBE (200 or 400 mg/kg) by gastric gavage daily for 12 weeks. Mice in the untreated diabetic group received saline instead, and nondiabetic C57BL/6J mice served as controls. Collagen І and ІІІ mRNA expression was measured by real-time PCR. TNF-α, IL-1β mRNA levels, and NF-κB expression were determined to analyze intramyocardial inflammation. Hallmarks of endoplasmic reticulum stress- (ERS-) related apoptosis pathways, including phosphorylated c-Jun N-terminal kinase (p-JNK), C/EBP homologous protein (CHOP), caspase-12, and cleaved caspase-3, were analyzed by Western blotting. Diabetic ApoE^−/− myocardial injury was associated with increased cardiomyocyte apoptosis (increased expression of p-JNK, CHOP, caspase-12, and cleaved caspase-3), interstitial fibrosis (increased mRNA levels of collagen І and ІІІ), and inflammation (increased mRNA levels of TNF-α and IL-1β, and NF-κB expression). GBE at 200 and 400 mg/kg/day significantly attenuated cardiomyocyte apoptosis, collagen deposition, and inflammation in diabetic mice via inhibition of the p-JNK, CHOP, and caspase-12 pathways. Serum levels of the proinflammatory cytokines (IL-6, IL-1β, and TNF-α), blood glucose, and lipid profiles were also regulated by GBE treatment. GBE might be beneficial in the treatment of diabetic myocardial injury.

Therapeutic Potential of Polyphenols in Cardiac Fibrosis

Cardiac fibrosis, in response to injury and stress, is central to a broad constellation of cardiovascular diseases. Fibrosis decreases myocardial wall compliance due to extracellular matrix (ECM) accumulation, leading to impaired systolic and diastolic function and causing arrhythmogenesis. Although some conventional drugs, such as β-blockers and renin-angiotensin-aldosterone system (RAAS) inhibitors, have been shown to alleviate cardiac fibrosis in clinical trials, these traditional therapies do not tend to target all the fibrosis-associated mechanisms, and do not hamper the progression of cardiac fibrosis in patients with heart failure. Polyphenols are present in vegetables, fruits, and beverages and had been proposed as attenuators of cardiac fibrosis in different models of cardiovascular diseases. Together with results found in the literature, we can show that some polyphenols exert anti-fibrotic and myocardial protective effects by mediating inflammation, oxidative stress, and fibrotic molecular signals. This review considers an overview of the mechanisms of cardiac fibrosis, illustrates their involvement in different animal models of cardiac fibrosis treated with some polyphenols and projects the future direction and therapeutic potential of polyphenols on cardiac fibrosis.

SP600125 suppresses Keap1 expression and results in NRF2-mediated prevention of diabetic nephropathy

c-Jun N-terminal kinase (JNK) contributes to the pathogenesis of diabetic nephropathy (DN). The JNK inhibitor SP600125 was reported to ameliorate DN. However, the mechanism remained unclear. We previously reported that SP600125 activated nuclear factor erythroid 2-related factor 2 (NRF2), a governor of the cellular antioxidant defense system, in the aortas of the diabetic mice. Given the critical role of NRF2 in preventing DN, the present study aimed to test whether or not NRF2 is required for SP600125's protection against DN. To test the role of NRF2 in SP600125's effect, streptozotocin-induced C57BL/6 wild-type (WT) and Nrf2-knockout (KO) diabetic mice were treated in the presence or absence of SP600125, for 24 weeks. To explore the mechanism by which SP600125 activates NRF2, mouse mesangial cells (MMCs) were treated with high glucose (HG), in the presence or absence of either SP600125 or JNK siRNA. SP600125 significantly attenuated the diabetes-induced renal oxidative stress, inflammation, fibrosis, pathological change and dysfunction in the WT, but not the Nrf2 KO mice. SP600125 inactivated JNK, inhibited kelch-like ECH-associated protein 1 expression, preserved NRF2 protein and facilitated its nuclear translocation in the kidneys of the WT mice, the effects of which were similarly produced by either SP600125 or JNK siRNA in HG-treated MMCs. Further, both SP600125 and JNK siRNA alleviated HG-induced mesangial oxidative stress and expression of inflammatory and fibrotic genes. The present study demonstrates that NRF2 is required for SP600125's protection against DN. SP600125 activates NRF2 possibly via inhibition of JNK-induced Keap1 expression.

An Aza resveratrol-chalcone derivative 6b protects mice against diabetic cardiomyopathy by alleviating inflammation and oxidative stress

Inflammation and oxidative stress play a crucial role in the development of diabetic cardiomyopathy (DCM). We previously had synthesized an Aza resveratrol–chalcone derivative 6b, of which effectively suppressing lipopolysaccharide (LPS)‐induced inflammatory response in macrophages. This study aimed to investigate the potential protective effect of 6b on DCM and underlying mechanism. In H9c2 myocardial cells, 6b potently decreased high glucose (HG)‐induced cell fibrosis, hypertrophy and apoptosis, alleviating inflammatory response and oxidant stress. In STZ‐induced type 1 diabetic mice (STZ‐DM1), orally administration with 6b for 16 weeks significantly attenuated cardiac hypertrophy, apoptosis and fibrosis. The expression of inflammatory cytokines and oxidative stress biomarkers was also suppressed by 6b distinctly, without affecting blood glucose and body weight. The anti‐inflammatory and antioxidative activities of 6b were mechanistic associated with nuclear factor‐kappa B (NF‐κB) nucleus entry blockage and Nrf2 activation both in vitro and in vivo. The results indicated that 6b can be a promising cardioprotective agent in treatment of DCM via inhibiting inflammation and alleviating oxidative stress. This study also validated the important role of NF‐κB and Nrf2 taken in the pathogenesis of DCM, which could be therapeutic targets for diabetic comorbidities.

Puerarin ameliorates allodynia and hyperalgesia in rats with peripheral nerve injury

Puerarin is a major active ingredient of the traditional Chinese plant medicine, Radix Puerariae, and commonly used in the treatment of myocardial and cerebral ischemia. However, the effects of puerarin on neuropathic pain are still unclear. In this study, a neuropathic pain animal model was created by partial sciatic nerve ligation. Puerarin (30 or 60 mg/kg) was intraperitoneally injected once a day for 7 days. Mechanical allodynia and thermal hyperalgesia were examined at 1 day after model establishment. Mechanical threshold and paw withdrawal latency markedly increased in a dose-dependent manner in puerarin-treated rats, especially at 7 days after model establishment. At 7 days after model establishment, quantitative real-time reverse transcriptase-polymerase chain reaction results showed that puerarin administration reversed mRNA expression of transient receptor potential vanilloid 1 (Trpv1) and transient receptor potential ankyrin 1 (Trpa1) in a dose-dependent manner in dorsal root ganglion neurons after peripheral nerve injury. These results suggest that puerarin dose-dependently ameliorates neuropathic pain by suppressing Trpv1 and Trpa1 up-regulation in dorsal root ganglion of neuropathic pain rats.

Exacerbation of diabetic cardiac hypertrophy in OVE26 mice by angiotensin II is associated with JNK/c-Jun/miR-221-mediated autophagy inhibition

Both diabetes and angiotensin II (Ang II) excess trigger cardiac remodeling and dysfunction, and diabetic cardiomyopathy. We hypothesized that cardiac hypertrophy associated with the development of diabetic cardiomyopathy is worsened by increased Ang II. Male type 1 diabetic OVE26 and wild-type mice were given Ang II (sc., 1.15 mg/kg, twice a day) for 14 days. Diabetes-induced cardiac dysfunction and hypertrophy was exacerbated by Ang II treatment as determined by echocardiography, wheat germ agglutinin staining and atrial natriuretic peptide. Ang II treatment dramatically exacerbated diabetes-caused decreased LC3-II, a marker of autophagy, and increased p62, an indicator of cytosolic protein clearance. Ang II treatment also augmented diabetes-associated increased phosphorylated levels of c-Jun, JNK, mTOR, and miR-221, and decreased of p27 expression, a direct target of miR-221. Chromatin immunoprecipitation assay showed that Ang II elevated c-Jun binding to the promoter of miR-221 in diabetic mice. These results suggest that Ang II accelerates cardiac hypertrophy in the early stage of murine diabetes, probably through activation of the JKN/c-Jun/miR-221 axis and inhibition of downstream autophagy. Therefore, inhibition of Ang II or miR-221 in diabetic individuals may be a potential approach for delaying the onset and/or reducing the severity of diabetic cardiomyopathy.

Astragaloside IV protects against the pathological cardiac hypertrophy in mice

Although pathologic hypertrophic hearts currently maintain output, sustained cardiac hypertrophy could predispose a patient to arrhythmia and sudden death, and also cause heart failure. Thus, finding effective treatment and exploring the underlying molecular mechanisms of cardiac hypertrophy is urgently necessary. Astragaloside IV (AST-IV) is the main active component, extracted from the traditional Chinese medicinal herb Astragalus membranaceus. Previous studies have indicated that AST-IV has various bioactivities, such as anti-cancer, anti-oxidative stress and anti-inflammation. In the present study, we aimed to explore the effects of AST-IV on cardiac hypertrophy induced by aortic banding (AB) surgery in mice, and to reveal the underlying signaling mechanisms. The suppressor of IKKε (SIKE) is a negative regulator of the interferon pathway, which could be enhanced by AST-IV to ameliorate pathological cardiac hypertrophy in mice through inactivating TANK-binding kinase 1 (TBK1)/PI3K/AKT signaling pathway. AST-IV attenuated cardiac hypertrophy, collagen accumulation and abnormal cardiac functions. In addition, AB-induced apoptosis and inflammation in the heart tissue samples of mice, which were attenuated by AST-IV administration through inhibiting SIKE expression levels. Together, the findings above indicated that AST-IV might be a potential candidate to prevent cardiac hypertrophy via elevating SIKE to suppress TBK1/PI3K/AKT activity.

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.

11β-HSD1 inhibition ameliorates diabetes-induced cardiomyocyte hypertrophy and cardiac fibrosis through modulation of EGFR activity

11β-HSD1 has been recognized as a potential therapeutic target for type 2 diabetes. Recent studies have shown that hyperglycemia leads to activation of 11β-HSD1, increasing the intracellular glucocorticoid levels. Excess glucocorticoids may lead to the clinical manifestations of cardiac injury. Therefore, the aim of this study is to investigate whether 11β-HSD1 activation contributes to the development of diabetic cardiomyopathy. To investigate the role of 11β-HSD1, we administered a selective 11β-HSD1 inhibitor in type 1 and type 2 murine models of diabetes and in cultured cardiomyocytes. Our results show that diabetes increases cortisone levels in heart tissues. 11β-HSD1 inhibitor decreased cortisone levels and ameliorated all structural and functional features of diabetic cardiomyopathy including fibrosis and hypertrophy. We also show that high levels of glucose caused cardiomyocyte hypertrophy and increased matrix protein deposition in culture. Importantly, inhibition of 11β-HSD1 attenuated these changes. Moreover, we show that 11β-HSD1 activation mediates these changes through modulating EGFR phosphorylation and activity. Our findings demonstrate that 11β-HSD1 contributes to the development of diabetic cardiomyopathy through activation of glucocorticoid and EGFR signaling pathway. These results suggest that inhibition of 11β-HSD1 might be a therapeutic strategy for diabetic cardiomyopathy, which is independent of its effects on glucose homeostasis.

Klotho protects the heart from hyperglycemia-induced injury by inactivating ROS and NF-κB-mediated inflammation both in vitro and in vivo

Cardiac inflammation and oxidative stress play a key role in the pathogenesis of diabetic cardiomyopathy (DCM). The anti-aging protein Klotho has been found to protect cells from inflammation and oxidative stress. The current study aimed to explore the cardioprotective effects of Klotho on DCM and the underlying mechanisms. H9c2 cells and neonatal cardiomyocytes were incubated with 33mM glucose in the presence or absence of Klotho. Klotho pretreatment effectively inhibited high glucose-induced inflammation, ROS generation, apoptosis, mitochondrial dysfunction, fibrosis and hypertrophy in both H9c2 cells and neonatal cardiomyocytes. In STZ-induced type 1 diabetic mice, intraperitoneal injection of Klotho at 0.01mg/kg per 48h for 3months completely suppressed cardiac inflammatory cytokines and oxidative stress and prevented cardiac cell death and remodeling, which subsequently improved cardiac dysfunction without affecting hyperglycemia. This study revealed that Klotho may exert its protective effects by augmenting nuclear factor erythroid 2-related factor 2 (Nrf2) expression and inactivating nuclear factor κB (NF-κB) activation both in vitro and in vivo. Thus, this work demonstrated for the first time that the anti-aging protein Klotho may be a potential therapeutic agent to treat DCM by inhibiting oxidative stress and inflammation. We also demonstrated the critical roles of the Nrf2 and NF-κB pathways in diabetes-stimulated cardiac injuries and indicated that they may be key therapeutic targets for diabetic complications.

SIRT1 Activation by Resveratrol Alleviates Cardiac Dysfunction via Mitochondrial Regulation in Diabetic Cardiomyopathy Mice

BACKGROUND

Diabetic cardiomyopathy (DCM) is a major threat for diabetic patients. Silent information regulator 1 (SIRT1) has a regulatory effect on mitochondrial dynamics, which is associated with DCM pathological changes. Our study aims to investigate whether resveratrol, a SRIT1 activator, could exert a protective effect against DCM.

METHODS AND RESULTS

Cardiac-specific SIRT1 knockout (SIRT1KO) mice were generated using Cre-loxP system. SIRT1KO mice displayed symptoms of DCM, including cardiac hypertrophy and dysfunction, insulin resistance, and abnormal glucose metabolism. DCM and SIRT1KO hearts showed impaired mitochondrial biogenesis and function, while SIRT1 activation by resveratrol reversed this in DCM mice. High glucose caused increased apoptosis, impaired mitochondrial biogenesis, and function in cardiomyocytes, which was alleviated by resveratrol. SIRT1 deletion by both SIRT1KO and shRNA abolished the beneficial effects of resveratrol. Furthermore, the function of SIRT1 is mediated via the deacetylation effect on peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), thus inducing increased expression of nuclear respiratory factor 1 (NRF-1), NRF-2, estrogen-related receptor-α (ERR-α), and mitochondrial transcription factor A (TFAM).

CONCLUSIONS

Cardiac deletion of SIRT1 caused phenotypes resembling DCM. Activation of SIRT1 by resveratrol ameliorated cardiac injuries in DCM through PGC-1α-mediated mitochondrial regulation. Collectively, SIRT1 may serve as a potential therapeutic target for DCM.

SIRT1 activation inhibits hyperglycemia-induced apoptosis by reducing oxidative stress and mitochondrial dysfunction in human endothelial cells

Sustained hyperglycemic stimulation of vascular cells is involved in the pathogenesis of diabetes mellitus‑induced cardiovascular complications. Silent information regulator T1 (SIRT1), a mammalian sirtuin, has been previously recognized to protect endothelial cells against hyperglycemia‑induced oxidative stress. In the present study, human umbilical vein endothelial cells (HUV‑EC‑C) were treated with D‑glucose, and the levels of oxidative stress, mitochondrial dysfunction, the rate of apoptosis and SIRT1 activity were measured. The effect of manipulated SIRT1 activity on hyperglycemia‑induced oxidative stress, mitochondrial dysfunction and apoptosis was then assessed using the SIRT1 activator, resveratrol (RSV), and the SIRT1 inhibitor, sirtinol. The present study confirmed that hyperglycemia promotes oxidative stress and mitochondrial dysfunction in HUV‑EC‑C cells. The accumulation of reactive oxygen species, the swelling of mitochondria, the ratio of adenosine 5'‑diphosphate to adenosine 5'‑triphosphate and localized mitochondrial superoxide levels were all increased following D‑glucose treatment, whereas the mitochondrial membrane potential was significantly reduced by >50 mg/ml D‑glucose treatment. In addition, hyperglycemia was confirmed to induce apoptosis in HUV‑EC‑C cells. Furthermore, the results confirmed the prevention and aggravation of hyperglycemia‑induced apoptosis by RSV treatment and sirtinol treatment, via the amelioration and enhancement of oxidative stress and mitochondrial dysfunction in HUV‑EC‑C cells, respectively. In conclusion, the present study revealed that hyperglycemia promotes oxidative stress, mitochondrial dysfunction and apoptosis in HUV‑EC‑C cells, and manipulation of SIRT1 activity regulated hyperglycemia‑induced mitochondrial dysfunction and apoptosis in HUV‑EC‑C cells. The data revealed the protective effect of SIRT1 against hyperglycemia‑induced apoptosis via the alleviation of mitochondrial dysfunction and oxidative stress.

"mTOR Signaling Pathway": A Potential Target of Curcumin in the Treatment of Spinal Cord Injury

The purpose of this review is to discuss the possibility of the treatment of spinal cord injury (SCI) with curcumin via regulating the mTOR signaling pathway, which may provide another strong support for curcumin to be a promising medicine applied to the treatment of SCI. Curcumin is termed as a multifunctional targeting therapy drug that regulates the mTOR signaling pathway in the treatment of numerous diseases. Previous research has already revealed that mTOR signaling pathway plays a vital role in prognosis, which involves the axon regeneration and autophagy. This review discusses a potential mechanism that curcumin suppresses the activation of this pathway and ameliorates the microenvironment of axons regeneration which would provide a new way that induces autophagy appropriately.

Acute ethanol exposure-induced autophagy-mediated cardiac injury via activation of the ROS-JNK-Bcl-2 pathway

Binge drinking is associated with increased cardiac autophagy, and often triggers heart injury. Given the essential role of autophagy in various cardiac diseases, this study was designed to investigate the role of autophagy in ethanol-induced cardiac injury and the underlying mechanism. Our study showed that ethanol exposure enhanced the levels of LC3-II and LC3-II positive puncta and promoted cardiomyocyte apoptosis in vivo and in vitro. In addition, we found that ethanol induced autophagy and cardiac injury largely via the sequential triggering of reactive oxygen species (ROS) accumulation, activation of c-Jun NH2-terminal kinase (JNK), phosphorylation of Bcl-2, and dissociation of the Beclin 1/Bcl-2 complex. By contrast, inhibition of ethanol-induced autophagic flux with pharmacologic agents in the hearts of mice and cultured cells significantly alleviated ethanol-induced cardiomyocyte apoptosis and heart injury. Elimination of ROS with the antioxidant N-acetyl cysteine (NAC) or inhibition of JNK with the JNK inhibitor SP600125 reduced ethanol-induced autophagy and subsequent autophagy-mediated apoptosis. Moreover, metallothionein (MT), which can scavenge reactive oxygen and nitrogen species, also attenuated ethanol-induced autophagy and cell apoptosis in MT-TG mice. In conclusion, our findings suggest that acute ethanol exposure induced autophagy-mediated heart toxicity and injury mainly through the ROS-JNK-Bcl-2 signaling pathway.

Curcumin as a potential protective compound against cardiac diseases

Curcumin, which was first used 3000 years ago as an anti-inflammatory agent, is a well-known bioactive compound derived from the active ingredient of turmeric (Curcuma longa). Previous research has demonstrated that curcumin has immense therapeutic potential in a variety of diseases via anti-oxidative, anti-apoptotic, and anti-inflammatory pathways. Cardiac diseases are the leading cause of mortality worldwide and cause considerable harm to human beings. Numerous studies have suggested that curcumin exerts a protective role in the human body whereas its actions in cardiac diseases remain elusive and poorly understood. On the basis of the current evidence, we first give a brief introduction of cardiac diseases and curcumin, especially regarding the effects of curcumin in embryonic heart development. Secondly, we analyze the basic roles of curcumin in pathways that are dysregulated in cardiac diseases, including oxidative stress, apoptosis, and inflammation. Thirdly, actions of curcumin in different cardiac diseases will be discussed, as will relevant clinical trials. Eventually, we would like to discuss the existing controversial opinions and provide a detailed analysis followed by the remaining obstacles, advancement, and further prospects of the clinical application of curcumin. The information compiled here may serve as a comprehensive reference of the protective effects of curcumin in the heart, which is significant to the further research and design of curcumin analogs as therapeutic options for cardiac diseases.

Troxerutin protects against diabetic cardiomyopathy through NF‑κB/AKT/IRS1 in a rat model of type 2 diabetes

Troxerutin is a bioflavonoid, which can be used to treat venous disorders, thrombosis and cerebrovascular diseases. Recent studies have demonstrated that it may also be used to prevent edemas. However, it is not known whether troxerutin protects against the cardiomyopathic complications of diabetes. In the present study, a rat model of type 2 diabetes was used to investigate the potential for troxerutin to protect against diabetic cardiomyopathy, through changes to nuclear factor‑κB (NF‑κB) expression. Troxerutin administration significantly reduced heart rate, blood pressure, blood glucose and plasma triglyceride levels across all measured time points. Furthermore, troxerutin significantly reduced reactive oxygen species levels, NF‑κB protein expression, and suppressed the phosphorylated forms of AKT, insulin receptor substrate 1 (IRS1) and c‑Jun N‑terminal kinase (JNK). These results suggested that troxerutin protects against cardiomyopathy via alterations in NF‑κB, AKT and IRS1 signaling, in a rat model of type 2 diabetes.

An overview of the inflammatory signalling mechanisms in the myocardium underlying the development of diabetic cardiomyopathy

Heart failure is a highly morbid and mortal clinical condition that represents the last stage of most cardiovascular disorders. Diabetes is strongly associated with an increased incidence of heart failure and directly promotes cardiac hypertrophy, fibrosis, and apoptosis. These changes, in turn, contribute to the development of ventricular dysfunction. The clinical condition associated with the spectrum of cardiac abnormalities induced by diabetes is termed diabetic cardiomyopathy. Myocardial inflammation has recently emerged as a pathophysiological process contributing to cardiac hypertrophy, fibrosis, and dysfunction in cardiac diseases. Myocardial inflammation is also implicated in the development of diabetic cardiomyopathy. Several molecular mechanisms link diabetes to myocardial inflammation. The NF-κB signalling pathway and the renin-angiotensin-aldosterone system are strongly activated in the diabetic heart, thereby promoting myocardial inflammation. Advanced glycation end-products and damage-associated molecular pattern molecules also represent strong triggers for inflammation. The mediators resulting from this inflammatory process modulate specific intracellular signalling mechanisms in cardiac cells that promote the development of diabetic cardiomyopathy. This review article will provide an overview of the signalling molecular mechanisms linking diabetic cardiomyopathy to myocardial inflammation.

Synthesis and Evaluation of Anti-inflammatory N-Substituted 3,5-Bis(2-(trifluoromethyl)benzylidene)piperidin-4-ones

A total of 24 N-substituted 3,5-bis(2-(trifluoromethyl)benzylidene)piperidin-4-one derivatives were synthesized via aldol condensation, and their anti-inflammatory activities were evaluated. These compounds were found to have no significant cytotoxicity against mouse bone marrow cells in vitro. However, some compounds, such as c6 (N-(3-methylbenzoyl)-3,5-bis-(2-(trifluoromethyl)benzylidene)piperidin-4-one) and c10 (N-(2-chlorobenzoyl)-3,5-bis-(2-(trifluoromethyl)benzylidene)piperidin-4-one), displayed potent anti-inflammatory activity by inhibiting lipopolysaccharide (LPS)-stimulated tumor necrosis factor (TNF)-α, interleukin-6 (IL-6), IL-1β, prostaglandin E2 (PGE2), and nitric oxide (NO) production in RAW 264.7 cells. Treatment with c6 or c10 at 2.5 or 10 mg kg^-1 significantly decreased the paw edema induced by carrageenan in rats, and the anti-inflammatory effects of these compounds were found to be better than those of celecoxib or indomethacin as well as their parent compound C66 (2,6-bis-(2-(trifluoromethyl)benzylidene)cyclohexanone). Pharmacokinetic analysis indicated that c6 has better bioavailability than curcumin. Therefore, these compounds may be valuable leads for the development of new anti-inflammatory drugs.

Antioxidative Effects of Natural Products on Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM) is a common and severe complication of diabetes and results in high mortality. It is therefore imperative to develop novel therapeutics for the prevention or inhibition of the progression of DCM. Oxidative stress is a key mechanism by which diabetes induces DCM. Hence, targeting of oxidative stress-related processes in DCM could be a promising therapeutic strategy. To date, a number of studies have shown beneficial effects of several natural products on the attenuation of DCM via an antioxidative mechanism of action. The aim of the present review is to provide a comprehensive and concise overview of the previously reported antioxidant natural products in the inhibition of DCM progression. Clinical trials of the antioxidative natural products in the management of DCM are included. In addition, discussion and perspectives are further provided in the present review.

Signaling Pathways in Cardiac Myocyte Apoptosis

Cardiovascular diseases, the number 1 cause of death worldwide, are frequently associated with apoptotic death of cardiac myocytes. Since cardiomyocyte apoptosis is a highly regulated process, pharmacological intervention of apoptosis pathways may represent a promising therapeutic strategy for a number of cardiovascular diseases and disorders including myocardial infarction, ischemia/reperfusion injury, chemotherapy cardiotoxicity, and end-stage heart failure. Despite rapid growth of our knowledge in apoptosis signaling pathways, a clinically applicable treatment targeting this cellular process is currently unavailable. To help identify potential innovative directions for future research, it is necessary to have a full understanding of the apoptotic pathways currently known to be functional in cardiac myocytes. Here, we summarize recent progress in the regulation of cardiomyocyte apoptosis by multiple signaling molecules and pathways, with a focus on the involvement of these pathways in the pathogenesis of heart disease. In addition, we provide an update regarding bench to bedside translation of this knowledge and discuss unanswered questions that need further investigation.

Endoplasmic reticulum stress-induced neuronal inflammatory response and apoptosis likely plays a key role in the development of diabetic encephalopathy

We assumed that diabetic encephalopathy (DEP) may be induced by endoplasmic reticulum (ER)-mediated inflammation and apoptosis in central nervous system. To test this notion, here we investigated the neuronal ER stress and associated inflammation and apoptosis in a type 2 diabetes model induced with high-fat diet/streptozotocin in Sprague-Dawley rats. Elevated expressions of ER stress markers, including glucose-regulated protein 78 (GRP78), activating transcription factor-6 (ATF-6), X-box binding protein-1 (XBP-1), and C/EBP homologous protein, and phosphor-Jun N-terminal kinase (p-JNK) were evident in the hippocampus CA1 of diabetic rats. These changes were also accompanied with the activation of NF-κB and the increased levels of inflammatory cytokines, tumor necrosis factor-α (TNF-α) and Interleukin-6 (IL-6). Mechanistic study with in vitro cultured hippocampus neurons exposed to high glucose (HG), which induced a diabetes-like effects, shown by increased ER stress, JNK and NF-κB activation, and inflammatory response. Inhibition of ER stress by 4-phenylbutyrate (4-PBA) or blockade of JNK activity by specific inhibitor or transfection of DN-JNK attenuated HG-induced inflammation and associated apoptosis. To validate the in vitro finding, in vivo application of 4-PBA resulted in a significant reduction of diabetes-induced neuronal ER stress, inflammation and cell death, leading to the prevention of DEP. These results suggest that diabetes-induced neuronal ER stress plays the critical role for diabetes-induced neuronal inflammation and cell death, leading to the development of DEP.

Atorvastatin Alleviates Experimental Diabetic Cardiomyopathy by Regulating the GSK-3β-PP2Ac-NF-κB Signaling Axis

Recent studies reported that atorvastatin (ATOR) alleviated progression of experimental diabetic cardiomyopathy (DCM), possibly by protecting against apoptosis. However, the underlying mechanisms of this protective effect remain unclear. Therefore, our study investigated the role of the glycogen synthase kinase (GSK)-3β-protein phosphatase 2A(PP2A)-NF-κB signaling pathway in the anti-apoptotic and cardioprotective effects of ATOR on cardiomyocytes cultured in high glucose (HG) and in DCM. Our results showed that, in HG-cultured cardiomyocytes, phosphorylation of GSK-3β was decreased, while that of the PP2A catalytic subunit C (PP2Ac) and IKK/IкBα was increased, followed by NF-кB nuclear translocation and apoptosis. IKK/IкBα phosphorylation and NF-кB nuclear translocation were also increased by treatment of cells with okadaic acid (OA), a selective PP2A inhibitor, or by silencing PP2Ac expression. The opposite results were obtained by silencing GSK-3β expression, which resulted in PP2Ac activation. Furthermore, IKK/IкBα phosphorylation and NF-кB nuclear translocation were markedly inhibited and apoptosis attenuated in cells treated with ATOR. These effects occurred through inactivation of GSK-3β and subsequent activation of PP2Ac. They were abolished by treatment of cells with OA or PP2Ac siRNA. In mice with type 1 diabetes mellitus, treatment with ATOR, at 10 mg-kg⁻¹-d⁻¹, significantly suppressed GSK-3β activation, IKK/IкBα phosphorylation, NF-кB nuclear translocation and caspase-3 activation, while also activating PP2Ac. Finally, improvements in histological abnormalities, fibrosis, apoptosis and cardiac dysfunction were observed in diabetic mice treated with ATOR. These findings demonstrated that ATOR protected against HG-induced apoptosis in cardiomyocytes and alleviated experimental DCM by regulating the GSK-3β-PP2A-NF-κB signaling pathway.

11β-Hydroxysteroid Dehydrogenase Type 1(11β-HSD1) mediates insulin resistance through JNK activation in adipocytes

Glucocorticoids are used to treat a number of human diseases but often lead to insulin resistance and metabolic syndrome. 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) is a key enzyme that catalyzes the intracellular conversion of cortisone to physiologically active cortisol. Despite the known role of 11β-HSD1 and active glucocorticoid in causing insulin resistance, the molecular mechanisms by which insulin resistance is induced remain elusive. The aim of this study is to identify these mechanisms in high fat diet (HFD) experimental models. Mice on a HFD were treated with 11β-HSD1 inhibitor as well as a JNK inhibitor. We then treated 3T3-L1-derived adipocytes with prednisone, a synthetic glucocorticoid, and cells with 11β-HSD1 overexpression to study insulin resistance. Our results show that 11β-HSD1 and JNK inhibition mitigated insulin resistance in HFD mice. Prednisone stimulation or overexpression of 11β-HSD1 also caused JNK activation in cultured adipocytes. Inhibition of 11β-HSD1 blocked the activation of JNK in adipose tissue of HFD mice as well as in cultured adipocytes. Furthermore, prednisone significantly impaired the insulin signaling pathway, and these effects were reversed by 11β-HSD1 and JNK inhibition. Our study demonstrates that glucocorticoid-induced insulin resistance was dependent on 11β-HSD1, resulting in the critical activation of JNK signaling in adipocytes.

Effects of curcumin in experimental diabetic nephropathy

Diabetic nephropathy (DN) is currently well established as the most common cause of end-stage renal disease in most parts of the world. Notwithstanding the expanding basic and clinical research in this field, the pathogenesis remains far from clear and hence the treatment of DN remains suboptimal. There is a critical need for the development of newer therapeutic strategies including alternative and complementary therapies. One of the natural products that was extensively studied in cancer and other chronic disease states such as diabetes is curcumin, an active ingredient in turmeric, a spice extensively used in India. In this manuscript, we present a critical review of the experimental and clinical evidence that supports the use of curcumin and its analogs in DN as well as the various proposed mechanisms for its biological actions in health and disease states.

Rosmarinic Acid suppressed high glucose-induced apoptosis in H9c2 cells by ameliorating the mitochondrial function and activating STAT3

Mitochondrial injury characterized by intracellular reactive oxygen species (ROS) accumulation plays a critical role in hyperglycemia-induced myocardium dysfunction. Previous studies have demonstrated that Rosmarinic Acid (RA) treatment and activating Signal transducer and activator of transcription 3 (STAT3) signaling pathway have protective effects on mitochondrial dysfunction in cardiomyocyte, but there is little data regarding cardiomyocyte under condition of high-glucose. The present study was undertaken to determine the relationship between RA and STAT3 activation, as well as their effects on high glucose-induced mitochondrial injury and apoptosis in H9c2 cardiomyocyte. Our results revealed that RA pretreatment suppressed high glucose-induced apoptosis in H9c2 cells. Moreover, the effect of RA on apoptosis was related with improved mitochondrial function, which was demonstrated by that RA attenuated high glucose-induced ROS generation, inhibited mitochondrial permeability transition pore (MPTP) activation, suppressed cytochrome c release and caspase-3 activation. In addition, the phosphorylation of STAT3 in H9c2 cells was inhibited under condition of high-glucose, but RA improved STAT3 phosphorylation. Importantly, inhibition of STAT3 expression by using STAT3-siRNA partly suppressed the effect of RA on high glucose-induced apoptosis. Taken together, pretreatment with RA suppressed high glucose-induced apoptosis in cardiomyocyte by ameliorating mitochondrial function and activating STAT3.

C66 ameliorates diabetic nephropathy in mice by both upregulating NRF2 function via increase in miR-200a and inhibiting miR-21

AIMS/HYPOTHESIS

Diabetic nephropathy is the leading cause of end-stage renal disease. Previously we reported that C66, a novel analogue of curcumin with a very high bioavailability, ameliorated diabetic nephropathy in mice, with little known about the mechanism. The present study aimed to define the mechanism by which C66 ameliorates diabetic nephropathy.

METHODS

Our aim was to discover whether C66 acts through the activation of nuclear factor (erythroid-derived 2)-like 2 (NFE2L2 or NRF2), which governs the antioxidant response. Streptozotocin-induced Nrf2 (also known as Nfe2l2)-knockout and wild-type (WT) diabetic mice were treated with C66. To determine whether the actions of C66 on NRF2 are mediated by microRNA (miR)-200a, WT diabetic mice were treated with C66 in the presence or absence of an in vivo miR-200a inhibitor (locked nucleic acid-modified anti-miR-200a [LNA-200a]) for 6 months. To determine whether miR-21 downregulation provided an NRF2-independent basis for C66 protection, Nrf2-knockout diabetic mice were treated with either C66 or an inhibitor of miR-21 (locked nucleic acid-modified anti-miR-21 [LNA-21]).

RESULTS

Deletion of Nrf2 partially abolished diabetic nephropathy protection by C66, confirming the requirement of NRF2 for this protection. Diabetic mice, but not C66-treated diabetic mice, developed significant albuminuria, renal oxidative damage and fibrosis. C66 upregulated renal miR-200a, inhibited kelch-like ECH-associated protein 1 and induced NRF2 function, effects that were prevented by LNA-200a. However, LNA-200a only partially reduced the protection afforded by C66, suggesting the existence of miR-200a/NRF2-independent mechanisms for C66 protection. C66 was also found to inhibit diabetes induction of miR-21. Both C66 and LNA-21 produced similar reductions in miR-21, albuminuria and renal fibrosis.

CONCLUSIONS/INTERPRETATION

The present study indicates that in addition to upregulating NRF2 by increasing miR-200a, C66 also protects against diabetic nephropathy by inhibiting miR-21.

The Role of p38 MAPK in the Development of Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM) is a major complication of diabetes that contributes to an increase in mortality. A number of mechanisms potentially explain the development of DCM including oxidative stress, inflammation and extracellular fibrosis. Mitogen-activated protein kinase (MAPK)-mediated signaling pathways are common among these pathogenic responses. Among the diverse array of kinases, extensive attention has been given to p38 MAPK due to its capacity for promoting or inhibiting the translation of target genes. Growing evidence has indicated that p38 MAPK is aberrantly expressed in the cardiovascular system, including the heart, under both experimental and clinical diabetic conditions and, furthermore, inhibition of p38 MAPK activation in transgenic animal model or with its pharmacologic inhibitor significantly prevents the development of DCM, implicating p38 MAPK as a novel diagnostic indicator and therapeutic target for DCM. This review summarizes our current knowledge base to provide an overview of the impact of p38 MAPK signaling in diabetes-induced cardiac remodeling and dysfunction.

Wogonin attenuates diabetic cardiomyopathy through its anti-inflammatory and anti-oxidative properties

Among diabetic cardiovascular complications cardiomyopathy is major event which if not well controlled culminates in cardiac failure. Wogonin from the root of Scutellaria baicalensis Georgi has shown specific anti-diabetes bioactivity. However, its effect on diabetic complications remains unclear. The main purpose of this study is to investigate the potential effects of wogonin on diabetic cardiomyopathy and to figure out its underlying mechanism. We found that wogonin administration suppressed hyperglycemia, improved cardiac function, and mitigated cardiac fibrosis in STZ-induced diabetic mice. Wogonin supplementation also attenuated diabetic-induced cardiomyocyte apoptosis and necrosis. In addition, wogonin treatment exhibited the properties of anti-oxidative stress and anti-inflammation in STZ diabetic mice, evidenced by improved activities of anti-oxidases including SOD1/2 and CAT, decreased ROS and MDA production, suppressed expression of inflammation factors such as IL-1β, IL-6, TNFα, and PAI-1, and inhibited NF-κB signaling. These results suggested that wogonin potentially mitigate hyperglycemia-related cardiomyocyte impairment through inhibiting inflammation and oxidative stress.

Cannabinoid receptors are involved in the protective effect of a novel curcumin derivative C66 against CCl4-induced liver fibrosis

Liver fibrosis is one of the major causes of morbidity and mortality worldwide and lacks efficient therapy. Recent studies suggest the curcumin protects liver from fibrosis. However, curcumin itself is in low bioavailable concentration when administered orally, and the protective mechanism remains poorly understood. The current study aimed to investigate whether a more stable derivative of curcumin, C66, protects against CCl4-inudced liver fibrosis and examine the underlying mechanism involving cannabinoid receptor (CB receptor). At a dose lower than curcumin itself, C66 displayed a superior anti-fibrotic effect. C66 significantly reduced collagen deposition, pro-inflammatory cytokine expression, and liver enzyme activities. Mechanistic study revealed that C66 treatment decreased CCl4-induced cannabinoid receptor 1 (CB1 receptor) expression and increased cannabinoid receptor 2 (CB2 receptor) expression, along with an inhibition of JNK/NF-κB-mediated inflammatory signaling. In conclusion, this curcumin derivative attenuates liver fibrosis likely involving a CB/JNK/NF-κB-mediated pathway.

Nobiletin attenuates cardiac dysfunction, oxidative stress, and inflammatory in streptozotocin: induced diabetic cardiomyopathy

Diabetic cardiomyopathy, characterized by the presence of diastolic and/or systolic myocardial dysfunction, is one of the major causes of heart failure. Nobiletin, which is extracted from the fruit peel of citrus, is reported to possess anti-inflammatory, anti-oxidative, and hypolipidemic properties. The purpose of this study was to investigate whether nobiletin exerts the therapeutic effect on streptozotocin-induced diabetic cardiomyopathy (DCM) in mice. 80 experimental male C57BL mice were randomly assigned into four groups: sham + vehicle (VEH/SH), sham + nobiletin (NOB/SH), DCM + vehicle (VEH/DM), and DCM + nobiletin (NOB/DM). Nobiletin treatment ameliorated cardiac dysfunction in the DCM group, as shown by the result of echocardiography and hemodynamic measurements. Nobiletin treatment also blunted the mRNA expression of NADPH oxidase isoforms p67(phox), p22(phox), and p91(phox), and abated oxidative stress. Although administration of diabetic mice with nobiletin did not significantly effect the level of blood glucose, it decreased the TGF-β1, CTGF, fibronectin, and collagen Iα expressions and blunted cardiac fibrosis. In addition, nobiletin inhibited the activation of c-Jun NH2-terminal kinase (JNK), P38, and NF-κB in the cardiac tissue of diabetic mice. Collectively, our study indicates that treatment with nobiletin mitigates cardiac dysfunction and interstitial fibrosis, and these beneficial of nobiletin may belong to the suppression of JNK, P38, and NF-κB signaling pathways.

High glucose induced-macrophage activation through TGF-β-activated kinase 1 signaling pathway

OBJECTIVE AND DESIGN

Transforming growth factor-β-activated kinase 1 (TAK1) plays a pivotal role in innate immune responses and kidney disease, and is critically involved in macrophage activation. However, there is a paucity of data to explore the role of high glucose (HG) in the regulation of TAK1 signaling and its functional role in macrophage activation. We assume that TAK1 signaling in hyperglycemic condition could be a key factor leading to macrophage activation and inflammation response.

METHODS

Mice macrophages were seeded on a 96-well cell culture plate; cell viability was tested after treatment with different concentration of TAK1 inhibitors. Cells were divided into groups (OZ300; MC; NC; HG; HG + OZ30, 100, 300 nM) and treated for given time course. Monocyte chemotactic protein1(MCP-1) and tumor necrosis factor-α (TNF-α) mRNA levels were evaluated by qRT-PCR. Flow cytometry and confocal microscopy are used to analyse the activated macrophage induced by HG. Expression levels of p-TAK1, TAB 1, p-JNK, p-p38MAPK, NF-κBpp65 were detected by western blot. Nuclear translocation of NF-κBp65 was assessed by confocal microscopy.

RESULTS

Our data revealed that high glucose not only significantly increased macrophage activation and subsequently abnormal high-expression of MCP-1 and TNF-α, but likewise remarkably enhanced TAK1 activation, MAPK phosphorylation, NF-κB expression in macrophages. Furthermore, pharmacological inhibition of TAK1 attenuated high glucose-triggered signal pathways, macrophage activation and inflammatory cytokines in a simulated diabetic environment.

CONCLUSION

Our findings suggested that high glucose activated macrophages mainly in TAK1/MAPKs and TAK1/NF-κB-dependent manners, which lead to the polarization of macrophages towards a pro-inflammatory phenotype, and finally lead to diabetic nephropathy. In sum, the study raises novel data about the molecular mechanisms involved in the high glucose-mediated inflammatory response in macrophages.

Diabetic cardiomyopathy: role of the E3 ubiquitin ligase

Diabetic cardiomyopathy (DCM) is the leading cause of mortality in diabetes. As the number of cases of diabetes continues to rise, it is urgent to develop new strategies to protect against DCM, which is characterized by cardiac hypertrophy, increased apoptosis, fibrosis, and altered insulin metabolism. The E3 ubiquitin ligases (E3s), one component of the ubiquitin-proteasome system, play vital roles in all of the features of DCM listed above. They also modulate the activity of several transcription factors involved in the pathogenesis of DCM. In addition, the E3s degrade both insulin receptor and insulin receptor substrates and also regulate insulin gene transcription, leading to insulin resistance and insulin deficiency. Therefore, the E3s may be a driving force for DCM. This review summarizes currently available studies to analyze the roles of the E3s in DCM, enriches our knowledge of how DCM develops, and provides a novel strategy to protect heart from diabetes.

Mark4 promotes oxidative stress and inflammation via binding to PPARγ and activating NF-κB pathway in mice adipocytes

MAP/Microtubule affinity-regulating kinase 4 (Mark4) plays an important role in the regulation of microtubule organization, adipogenesis and apoptosis. However, the role of Mark4 plays in oxidative stress and inflammation are poorly understood. In this study, we found Mark4 was induced by high fat diet (HFD) while PPARγ was elevated significantly in mice adipocytes. Further analyses revealed Mark4 impaired mitochondrial oxidative respiration and increased reactive oxygen species (ROS) production. At same time, the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) were greatly reduced. By treating cells with H₂O₂ and vitamin E (VE), Mark4 accentuated oxidative stress along with increased mRNA level of inflammatory factor interleukin-6 (IL-6) and decreased leptin mRNA. Furthermore, we found PPARγ bind to Mark4 promoter region and inhibited Mark4 expression. We showed PPARγ interacted with Mark4 and inhibited the stimulating effect of Mark4 on oxidative stress and inflammation. Finally, we demonstrated that the IKKα/NF-κB signal pathway was involved in Mark4 induced oxidative stress and inflammation, while PTDC, a special inhibitor of NF-κB signal pathway, reduced oxidative stress and inflammation. Thus, our study indicated that Mark4 was a potential drug target for treating metabolic diseases.

The Protective Effect of Low-Dose Ethanol on Myocardial Fibrosis through Downregulating the JNK Signaling Pathway in Diabetic Rats

Objective. To investigate the effects of low dose ethanol feeding in diabetic rats and analyze its underlying mechanisms. Methods. Male Sprague-Dawley rats were divided into 4 groups: control (Con), diabetes at 4 weeks (DM4W), diabetes at 8 weeks (DM8W), and EtOH + DM8W. After 8 weeks, hemodynamic parameters were recorded and heart weight/body weight (H/B) and hydroxyproline (Hp) content in myocardium were measured. Morphology of collagen in myocardial tissue was observed with Masson's trichrome staining method and collagen volume fraction (CVF) was analysed. The mRNA expression of ALDH2 was assessed with Real-Time PCR. The protein expressions of p-JNK and JNK were evaluated using western blot. Results. In contrast to Con group, there was no difference in hemodynamic parameters in DM4W group, but mean arterial pressure and heart rate were decreased in DM8W group, and the ratios of H/B, Hp, and CVF were markedly increased. ALDH2 mRNA expression was decreased, while the ratio of p-JNK/JNK were increased. Compared with DM8W group, the above indexes were improved in EtOH + DM8W group. Conclusion. With low dose ethanol intervention, enhanced ALDH2 expression can antagonize the happening of myocardial fibrosis in diabetic rats, which may be relevant with downregulating the JNK pathway.

Curcumin Protects Neonatal Rat Cardiomyocytes against High Glucose-Induced Apoptosis via PI3K/Akt Signalling Pathway

The function of curcumin on NADPH oxidase-related ROS production and cardiac apoptosis, together with the modulation of protein signalling pathways, was investigated in cardiomyocytes. Primary cultures of neonatal rat cardiomyocytes were exposed to 30 mmol/L high glucose with or without curcumin. Cell viability, apoptosis, superoxide formation, the expression of NADPH oxidase subunits, and potential regulatory molecules, Akt and GSK-3β, were assessed in cardiomyocytes. Cardiomyocytes exposure to high glucose led to an increase in both cell apoptosis and intracellular ROS levels, which were strongly prevented by curcumin treatment (10 μM). In addition, treatment with curcumin remarkably suppressed the increased activity of Rac1, as well as the enhanced expression of gp91(phox) and p47(phox) induced by high glucose. Lipid peroxidation and SOD were reversed in the presence of curcumin. Furthermore, curcumin treatment markedly inhibited the reduced Bcl-2/Bax ratio elicited by high glucose exposure. Moreover, curcumin significantly increased Akt and GSK-3β phosphorylation in cardiomyocytes treated with high glucose. In addition, LY294002 blocked the effects of curcumin on cardiomyocytes exposure to high glucose. In conclusion, these results demonstrated that curcumin attenuated high glucose-induced cardiomyocyte apoptosis by inhibiting NADPH-mediated oxidative stress and this protective effect is most likely mediated by PI3K/Akt-related signalling pathway.

Curcumin alleviates lung injury in diabetic rats by inhibiting nuclear factor-κB pathway

Curcumin is a polyphenolic compound that is extracted from Curcuma longa. It has broad anti-inflammation and anti-tumor activities. Curcumin was previously reported to exert beneficial effects on diabetes. However, the effect of curcumin on diabetes-induced lung injury is not yet clear. In this study, the effects of curcumin on lung injury induced by diabetes was explored using quantitative real time polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA), immunohistochemistry and electrophoretic mobility shift assay. The results of this study showed that curcumin reduced oxidative stress level, inhibited the synthesis of nitric oxide and prostaglandin E2, and reduced inflammatory responses in the lungs of diabetic rats, thereby alleviating diabetes-induced lung injury. Further study of the mechanism revealed that curcumin inhibited the activation of nuclear factor (NF)-κB which is a key player in inflammatory responses. In summary, our study demonstrated that curcumin inhibited the activation of NF-κB in the lungs of diabetic rats, thus reducing pulmonary inflammatory responses and oxidative stress, and ultimately relieving diabetes-induced lung injury. This study suggests that curcumin may be a promising agent to alleviate diabetic lung injury and also provides theoretical foundation for the development of diabetes therapy.

Cardiac H2S Generation Is Reduced in Ageing Diabetic Mice

Aims. To examine whether hydrogen sulfide (H₂S) generation changed in ageing diabetic mouse hearts. Results. Compared to mice that were fed tap water only, mice that were fed 30% fructose solution for 15 months exhibited typical characteristics of a severe diabetic phenotype with cardiac hypertrophy, fibrosis, and dysfunction. H₂S levels in plasma, heart tissues, and urine were significantly reduced in these mice as compared to those in controls. The expression of the H₂S-generating enzymes, cystathionine γ-lyase and 3-mercaptopyruvate sulfurtransferase, was significantly decreased in the hearts of fructose-fed mice, whereas cystathionine-β-synthase levels were significantly increased. Conclusion. Our results suggest that this ageing diabetic mouse model developed diabetic cardiomyopathy and that H₂S levels were reduced in the diabetic heart due to alterations in three H₂S-producing enzymes, which may be involved in the pathogenesis of diabetic cardiomyopathy.

Postprandial Dysmetabolism and Oxidative Stress in Type 2 Diabetes: Pathogenetic Mechanisms and Therapeutic Strategies

Postprandial dysmetabolism in type 2 diabetes (T2D) is known to impact the progression and evolution of this complex disease process. However, the underlying pathogenetic mechanisms still require full elucidation to provide guidance for disease prevention and treatment. This review focuses on the marked redox changes and inflammatory stimuli provoked by the spike in blood glucose and lipids in T2D individuals after meals. All the causes of exacerbated postprandial oxidative stress in T2D were analyzed, also considering the consequence of enhanced inflammation on vascular damage. Based on this in-depth analysis, current strategies of prevention and pharmacologic management of T2D were critically reexamined with particular emphasis on their potential redox-related rationale.