TRAP1 attenuates H9C2 myocardial cell injury induced by extracellular acidification via the inhibition of MPTP opening.

Extracellular acidification leads to cardiac dysfunction in numerous diseases. Mitochondrial dysfunction plays an important role in this process. However, the mechanisms through which extracellular acidification induces mitochondrial dysfunction remain unclear. Tumor necrosis factor receptor­associated protein 1 (TRAP1) maintains mitochondrial function and cell viability in tumor and non­tumor cells. In the present study, extracellular acidification was found to induce H9C2 cell apoptosis, mitochondrial dysfunction and TRAP1 expression. The overexpression of TRAP1 attenuated H9C2 cell injury, while the silencing of TRAP1 exacerbated it. Moreover, mitochondrial permeability transition pore (MPTP) opening, which is associated with the mitochondrial apoptotic pathway and cell death, was also increased in acidic medium. The overexpression of TRAP1 inhibited MPTP opening, while the silencing of TRAP1 promoted it. The protective effect of TRAP1 on cardiomyocytes was abolished by the addition of a specific MPTP opening promoter. Similarly, a specific MPTP opening inhibitor reversed cell injury by silencing TRAP1. Taken together, the findings of the present study demonstrate that TRAP1 attenuates H9C2 cell injury induced by extracellular acidification by inhibiting MPTP opening.

Tumor Necrosis Factor Receptor-Associated Protein 1 Protects against Mitochondrial Injury by Preventing High Glucose-Induced mPTP Opening in Diabetes.

Diabetic kidney disease (DKD) has become the leading cause of end-stage renal disease worldwide. Renal tubular epithelial cell apoptosis and tubular atrophy have been recognized as indicators of the severity and progression of DKD, while the mechanism remains elusive. Tumor necrosis factor receptor-associated protein 1 (TRAP1) plays critical roles in apoptosis. The aim of this study was to investigate the protective role TRAP1 plays in DKD and to study the potential underlying mechanisms. TRAP1 expression was decreased, and mitochondria were injured in NRK-52e cells under high-glucose (HG) conditions. The overexpression of TRAP1 ameliorated HG-induced apoptosis, increased cell viability, maintained mitochondrial morphology, adenosine triphosphate (ATP) levels, and mitochondrial membrane potential (MMP), and buffered oxidative stress, whereas TRAP1 knockdown aggravated these effects. The protective effects of TRAP1 may be exerted via the inhibition of mitochondrial permeability transition pore (mPTP) opening, and the damage caused by TRAP1 knockdown can be partially reversed by treatment with the mPTP opening inhibitor cyclosporin A (CsA). In vivo, TRAP1 expression upregulation by AAV2/9 injection prevented renal dysfunction, ameliorated histopathological changes, maintained mitochondrial morphology and function, and reduced apoptosis and reactive oxygen species (ROS) in STZ-treated DKD rats. Thus, our results suggest that TRAP1 ameliorates diabetes-induced renal injury by preventing abnormal mPTP opening and maintaining mitochondrial structure and function, which may be treated as a potential target for DKD treatment.

Neuroprotective effects of an Nrf2 agonist on high glucose-induced damage in HT22 cells.

BACKGROUND: Oxidative stress is the hallmark of diabetic encephalopathy, which may be caused by hyperglycaemic toxicity. We aimed to discover pharmacologic targets to restore redox homeostasis. We identified the transcription factor Nrf2 as such a target. METHODS: HT22 cells were cultured in 25 or 50 mM D-glucose with various concentrations of sulforaphane (SFN) (from 1.25 to 5.0 µM). Cell viability was tested with the Cell Counting Kit-8 assay. Reactive oxygen species (ROS) production was detected with an inverted fluorescence microscope using the dichlorodihydrofluorescein-diacetate fluorescent probe. The expression of NF-E2-related factor 2 (Nrf2), haem oxygenase-1 (HO-1) and nuclear factor-κB (NF-κB) at the mRNA and protein levels was detected by reverse transcription quantitative polymerase chain reaction and western blotting. RESULT: We found that a high glucose concentration (50 mM) increased the generation of ROS, downregulated the expression of Nrf2/HO-1 and upregulated the expression of NF-κB. Moreover, HT22 cell viability significantly decreased after culture in high-glucose medium for 24, 48 and 72 h, whereas the activation of the Nrf2/HO-1 pathway using a pharmacological Nrf2 activator abrogated this high-glucose-induced toxicity. CONCLUSION: This study suggests that the activation of the Nrf2-ARE signalling pathway might be a therapeutic target for the treatment of diabetic encephalopathy.

Sodium ferulate attenuates high-glucose-induced oxidative injury in HT22 hippocampal cells.

The aim of the present study was to investigate the protective effects of sodium ferulate (SF) on HT22 hippocampal cells under a high glucose concentration. Cells were cultured in normal glucose (25 mM D-glucose) or high glucose (50 mM D-glucose) with various concentrations of SF (50, 100, 250 or 500 µM) for 0, 48 and 72 h. Cell viability was tested using a Cell Counting Kit-8 assay. Reactive oxygen species (ROS) production was detected using flow cytometry. The expression of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and nuclear factor-κB (NF-κB) at the mRNA and protein levels were detected using a reverse transcription-quantitative polymerase chain reaction analysis and western blotting. HT22 hippocampal cell viability was revealed to be substantially decreased following culturing in high glucose medium (50 mM) for 48 and 72 h. The addition of 100 µM SF abrogated this high-glucose-induced toxicity, but higher concentrations of SF (250 and 500 µM) were harmful to the cells. Furthermore, a high glucose concentration increased the generation of ROS, downregulated the expression of Nrf2/HO-1 and upregulated the expression of NF-κB subsequent to culturing for 72 h, whereas the addition of the appropriate concentration of SF attenuated these effects. To the best of our knowledge, the present study is the first to report such results and provide evidence that SF protects HT22 cells from high glucose-induced toxicity by activating the Nrf2/HO-1 pathway and inhibiting the expression of NF-κB, which may be of therapeutic value in diabetic encephalopathy.

Neuroprotective effects of an Nrf2 agonist on high glucose-induced damage in HT22 cells

BACKGROUND: Oxidative stress is the hallmark of diabetic encephalopathy, which may be caused by hyperglycaemic toxicity. We aimed to discover pharmacologic targets to restore redox homeostasis. We identified the transcription factor Nrf2 as such a target. METHODS: HT22 cells were cultured in 25 or 50 mM D-glucose with various concentrations of sulforaphane (SFN) (from 1.25 to 5.0 µM). Cell viability was tested with the Cell Counting Kit-8 assay. Reactive oxygen species (ROS) production was detected with an inverted fluorescence microscope using the dichlorodihydrofluorescein-diacetate fluorescent probe. The expression of NF-E2-related factor 2 (Nrf2), haem oxygenase-1 (HO-1) and nuclear factor-κB (NF-κB) at the mRNA and protein levels was detected by reverse transcription quantitative polymerase chain reaction and western blotting. RESULT: We found that a high glucose concentration (50 mM) increased the generation of ROS, downregulated the expression of Nrf2/HO-1 and upregulated the expression of NF-κB. Moreover, HT22 cell viability significantly decreased after culture in high-glucose medium for 24, 48 and 72 h, whereas the activation of the Nrf2/HO-1 pathway using a pharmacological Nrf2 activator abrogated this high-glucose-induced toxicity. CONCLUSION: This study suggests that the activation of the Nrf2-ARE signalling pathway might be a therapeutic target for the treatment of diabetic encephalopathy.

Effects of intensive glycemic control in ocular complications in patients with type 2 diabetes: a meta-analysis of randomized clinical trials.

Whether intensive glycemic control can reduce incidence of diabetic retinopathy or other diabetes-associated ocular complications remains undefined. In this meta-analysis, we assessed the effects of intensive versus conventional glycemic control in ocular complications in patients with type 2 diabetes. A systematic literature search of PubMed, Web of Knowledge, and Scopus (until December 12, 2013) was conducted. Randomized controlled trials which compared intensive glycemic control with conventional glycemic control in ocular events in patients with type 2 diabetes were included. Random-effects models were used to measure the pooled odds ratio (OR) with 95 % confidence interval (CI). Seven trials involving 32,523 patients were included. Intensive glycemic control reduced the risks of retinal photocoagulation or vitrectomy (OR 0.86; 95 % CI 0.75-0.98), macular edema (OR 0.65; 95 % CI 0.43-0.99), and progression of retinopathy (OR 0.69; 95 % CI 0.55-0.87). No significant risk reduction was shown in incidence of retinopathy (OR 0.67; 95 % CI 0.26-1.73), cataract surgery (OR 0.88; 95 % CI 0.76-1.03), or severe loss of vision or blindness (OR 0.99; 95 % CI 0.86-1.13). Intensive glycemic control reduces the risk of most retinopathy-related events. But no beneficial effect was shown in ocular endpoint as severe loss of vision or blindness.

Cardioprotective effect of sodium ferulate in diabetic rats.

Reactive oxygen species (ROS) play important roles in the occurrence and development in diabetic cardiomyopathy (DC). Ferulic acid is one of the ubiquitous compounds in diet. Sodium ferulate (SF) is its sodium salt. SF has potent free radical scavenging activity and can effectively scavenge ROS. The study investigated the effect of SF on cardioprotection in diabetic rats. The diabetic rats induced by streptozotocin (STZ) were treated with SF (110mg/kg) by gavage per day for 12 weeks. Results showed that the levels of nitric oxide (NO) and superoxide dismutase (SOD) activity in plasma and myocardium in SF-treated group were significantly higher than those in diabetic control group. The levels of malondialdehyde (MDA) in plasma and myocardium in SF-treated group were significantly lower than those in diabetic control group. Expression of connective tissue growth factor (CTGF) in myocardium in SF-treated group was apparently lower than that in diabetic control group. Compared with normal control group, electron micrographs of myocardium in diabetic control group showed apparently abnormality, while that was significantly ameliorated in SF-treated group. The study demonstrated that SF has a cardioprotective effect via increasing SOD activity and NO levels in plasma and myocardium, inhibiting oxidative stress in plasma and myocardium, and inhibiting the expression of CTGF in myocardium in diabetes rats.

Expression of human globular adiponectin-glucagon-like peptide-1 analog fusion protein and its assay of glucose-lowering effect in vivo.

In this study, human globular adiponectin-glucagon-like peptide-1 analog (gAd-GLP-1-A) fusion protein was expressed and its glucose-lowering effect was measured in vivo. We constructed a prokaryotic expression vector PET28a-gAd-GLP-1-A and transformed the vector into Escherichia coli BL21 (DE3). A recombinant fusion protein of about 25KD was expressed from BL21 (DE3) cells after isopropylthio-ß-D-galactoside induction. This protein was N-terminal His-tagged gAd-GLP-1-A fusion protein. Most of the protein was expressed in inclusion body. The fusion protein in inclusion body was purified by using High-Affinity Nickel Iminodiacetic Acid Resin and refolded in urea gradient refolding buffer. The refolded protein was incubated with enterokinase to remove the N-terminal His-tag. The fusion protein without His-tag is gAd-GLP-1-A fusion protein, which exhibited significant glucose-lowering effect in diabetic mice.

Genetic effects of adiponectin on blood lipids and blood pressure.

OBJECTIVE: Results from the published studies on the association of adiponectin gene (ADIPOQ) polymorphisms with blood lipids and blood pressure are conflicting. We investigated the association of three ADIPOQ polymorphisms, +45 T > G (rs2241766), +276 G > T (rs1501299) and -11377 C > G (rs266729), with these traits in this meta-analysis. RESEARCH DESIGN AND METHODS: We included 35 studies in this meta-analysis. Dominant models were used for this meta-analysis. RESULTS: We did not detect a significant association of the -11377 C > G polymorphism with blood lipids or blood pressure (P > 0·05). The association of the +45 T > G polymorphism with blood lipids and blood pressure was, similarly, not significant (P > 0·05). The meta-analysis suggested a significant overall association of the +276 G > T polymorphism with lower levels of total cholesterol: weighted mean difference (WMD) = -0·10, 95% confidence interval (CI, -0·17, -0·03), P = 0·005, P(heterogeneity) = 0·04. This association was marginally significant in East Asians and East Asians with type 2 diabetes: WMD = -0·10, 95% CI (-0·20, 0·00), P = 0·05, P(heterogeneity) = 0·002, and WMD = -0·09, 95% CI (-0·18, -0·00), P = 0·05, P(heterogeneity) = 0·80, respectively. After exclusion of a study that was the source of heterogeneity, the association was significant in overall populations and marginally significant in East Asians: WMD= -0·06, 95% CI (-0·11, -0·01), P = 0·01, P(heterogeneity) = 0·98, and WMD = -0·06, 95% CI (-0·12, 0·00), P = 0·07, P(heterogeneity) = 0·83, respectively. However, none of these associations were significant after Bonferroni correction (significant threshold: P < 0·003). CONCLUSIONS: Our meta-analysis does not suggest any association of the three ADIPOQ polymorphisms with blood lipids and blood pressure.

Effects of peroxisome proliferator activated receptor-gamma 2 gene Pro12Ala polymorphism on fasting blood lipids: a meta-analysis.

OBJECTIVE: Results from the published studies on the association of peroxisome proliferator activated receptor-gamma 2 (PPARγ2) Pro12Ala polymorphism with blood lipids are conflicting. In this meta-analysis, we investigated the association of the Pro12Ala polymorphism with total cholesterol, triglycerides, low density lipoprotein cholesterol, and high-density lipoprotein cholesterol. METHODS: 74 studies with 52,998 subjects were included in this meta-analysis. Dominant model and additive model were used for this meta-analysis. RESULTS: We did not detect significant overall association of the Pro12Ala polymorphism with total cholesterol, low density lipoprotein cholesterol, or high-density lipoprotein cholesterol (P>0.05). Under dominant model, significant association between the PPARγ2 Pro12Ala polymorphism and increased blood TC in male subjects was detected: standardized mean difference=0.10, 95% confidence interval (0.02, 0.22), P=0.02, Pheterogeneity=0.14. We found a marginal association of the Pro12Ala polymorphism with increased HDL-C in healthy subjects under dominant model: standardized mean difference=0.10, 95% confidence interval (-0.00, 0.20), P=0.06, Pheterogeneity=0.96. We also found subjects with genotype AlaAla have lower blood TG than subjects with genotype ProPro in Caucasians: for analysis including the outlier studies: SMD=-0.40, 95% CI (-0.76, -0.05), P=0.02, Pheterogeneity<0.00001, and for analysis excluding the outlier studies: SMD=-0.23, 95% CI (-0.39, -0.06), P=0.006, Pheterogeneity=0.86. CONCLUSIONS: Our meta-analysis suggests that, compared with non-carriers, carriers of Ala allele have significant increased blood TC in male subjects, and marginally significant increased blood HDL-C in healthy subjects. Our meta-analysis also supports that subjects with genotype AlaAla have lower blood TG than subjects with genotype ProPro in Caucasians.

Association of the apolipoprotein A5 gene -1131 T>C polymorphism with fasting blood lipids: a meta-analysis in 37859 subjects.

BACKGROUND: Studies examining the association of apolipoprotein A5 (APOA5) gene -1131 T>C polymorphism with blood lipids produced inconsistent results. In this meta-analysis encompassing all the relevant studies, we aimed to investigate the association of the -1131 T>C polymorphism with fasting blood lipids. METHODS: We limited our analysis to the following four blood lipid variables: total cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C). Subjects were confined to adults who were at least 18 years old. A dominant model was used for this meta-analysis. 37 studies with 37859 subjects were included in this meta-analysis. RESULTS: The results showed that the carriers of -1131C allele have higher blood TC and TG than the non-carriers: standardized mean difference (SMD) = 0.08, 95% confidence interval (CI, 0.05, 0.11), P < 0.00001, P(heterogeneity) = 0.42, and SMD = 0.31, 95% CI (0.27, 0.34), P < 0.00001, P(heterogeneity) = 0.0003, respectively. Significant association between the -1131 T>C polymorphism and lower blood HDL-C was also detected under the dominant model: SMD = -0.17, 95% CI (-0.21, -0.14), P < 0.00001, P(heterogeneity) = 0.003. CONCLUSIONS: Our meta-analysis supports the strong association of the APOA5 -1131 T>C polymorphism with higher levels of TC and TG, and lower levels of HDL-C.

Association between the -634C/G polymorphisms of the vascular endothelial growth factor and retinopathy in type 2 diabetes: a meta-analysis.

AIMS: To investigate the association of vascular endothelial growth factor (VEGF) -634C/G polymorphism with retinopathy in type 2 diabetes. METHODS: 8 studies with 1183 cases and 1057 controls were included. Allelic and genotypic comparisons between cases and controls were evaluated. RESULTS: Our meta-analysis did not suggest a significant association of the -634C/G polymorphism with diabetic retinopathy (DR) and proliferative diabetic retinopathy (PDR) (P>0.05). The pooled odds ratios (ORs) for allelic frequency comparison, recessive model comparison, dominant model comparison, and additive model showed that the -634C/G polymorphism is significantly associated with nonproliferative diabetic retinopathy (NPDR): OR=1.61 [95% confidence interval (CI, 1.23, 2.10)], P=0.0005, P(heterogeneity)=0.38, OR=2.24 [95% CI (1.15, 4.39)], P=0.02, P(heterogeneity)=0.24, OR=1.87 [95% CI (1.01, 3.48)], P=0.05, P(heterogeneity)=0.16, and OR=2.91 [95% CI (1.33, 6.39)], P=0.008, P(heterogeneity)=0.26, respectively. However, in sensitivity analyses, we only detected a marginally significant association of the C allele with NPDR: OR=1.54 [95% CI (1.00, 2.39)], P=0.05, P(heterogeneity)=0.17. CONCLUSIONS: Our meta-analysis does not support the association of the VEGF -634C/G polymorphism with DR and PDR. Significant association between this polymorphism and NPDR was detected in this meta-analysis. However, this association is not robust and could be due to chance.

Association of the fatty acid-binding protein 2 gene Ala54Thr polymorphism with insulin resistance and blood glucose: a meta-analysis in 13451 subjects.

BACKGROUND: The results from the published studies on the association of fatty acid-binding protein 2 (FABP2) Ala54Thr polymorphism with insulin resistance and blood glucose are conflicting. In this meta-analysis, we investigated the association of the FABP2 Ala54Thr polymorphism with insulin resistance and blood glucose. METHODS: We collected data on fasting blood glucose and fasting insulin, 2-h blood glucose (2-h BG) and 2-h insulin (2-h insulin), and homeostasis model assessment insulin resistance index. A dominant model was used for this meta-analysis. RESULTS: Thirty-one studies with 13 451 subjects were included in this meta-analysis. The carriers of Thr54 allele have significantly higher homeostasis model assessment insulin resistance index and marginally higher fasting insulin than the non-carriers: standardized mean difference (SMD) = 0.07, 95% confidence interval (CI, 0.02, 0.12), p = 0.007, p(heterogeneity) = 0.19 and SMD = 0.08, 95% CI (-0.01, 0.17), p = 0.07, p(heterogeneity) < 0.00001, respectively. A borderline significant association between the FABP2 Ala54Thr polymorphism and an increased 2-h BG was also detected under the dominant model: SMD = 0.10, 95% CI (0.00, 0.20), p = 0.05, p(heterogeneity) = 0.09. In addition, a borderline association between this polymorphism and an increased fasting blood glucose in populations of other ethnic origins was detected under the dominant model: SMD = 0.11, 95% CI (-0.00, 0.23), p = 0.06, p(heterogeneity) = 0.03. CONCLUSIONS: Our meta-analysis suggests that the Thr54 allele of the FABP2 Ala54Thr is weakly associated with a higher degree of insulin resistance, higher level of fasting insulin and higher level of 2-h BG. Our meta-analysis also suggests a weak association between this polymorphism and an increased fasting blood glucose in populations of other ethnic origins under the dominant model.

Hypoxia-inducible factor-1alpha gene polymorphisms and cancer risk: a meta-analysis.

BACKGROUND: The results from the published studies on the association between hypoxia-inducible factor -1alpha (HIF-1alpha) polymorphisms and cancer risk are conflicting. In this meta-analysis, we aimed to investigate the association between HIF-1alpha 1772 C/T and 1790 G/A polymorphisms and cancer. METHODS: The meta-analysis for 1772 C/T polymorphism included 4131 cancer cases and 5387 controls, and for 1790 G/A polymorphism included 2058 cancer cases and 3026 controls. Allelic and genotypic comparisons between cases and controls were evaluated. Subgroup analyses by cancer types, ethnicity, and gender were also performed. We included prostate cancer in male subgroup, and female specific cancers in female subgroup. RESULTS: For the 1772 C/T polymorphism, the analysis showed that the T allele and genotype TT were significantly associated with higher cancer risk: odds ratio (OR) = 1.29 [95% confidence interval (CI, 1.01, 1.65)], P = 0.04, P(heterogeneity) < 0.00001, and OR = 2.18 [95% CI (1.32, 3.62)], P = 0.003, P(heterogeneity) = 0.02, respectively. The effect of the genotype TT on cancer especially exists in Caucasians and female subjects: OR = 2.40 [95% CI (1.26, 4.59)], P = 0.008, P(heterogeneity) = 0.02, and OR = 3.60 [95% CI (1.17, 11.11)], P = 0.03, P(heterogeneity) = 0.02, respectively. For the 1790 G/A polymorphism, the pooled ORs for allelic frequency comparison and dominant model comparison suggested a significant association of 1790 G/A polymorphism with a decreased breast cancer risk: OR = 0.28 [95% CI (0.08, 0.90)], P = 0.03, P(heterogeneity) = 0.45, and OR = 0.29 [95% CI (0.09, 0.97)], P = 0.04, P(heterogeneity) = 0.41, respectively. The frequency of the HIF-1alpha 1790 A allele was very low and only two studies were included in the breast cancer subgroup. CONCLUSIONS: Our meta-analysis suggests that the HIF-1alpha 1772 C/T polymorphism is significantly associated with higher cancer risk, and 1790 G/A polymorphism is significantly associated with decreased breast cancer risk. The effect of the 1772 C/T polymorphism on cancer especially exists in Caucasians and female subjects. Only female specific cancers were included in female subgroup, which indicates that the 1772 C/T polymorphism is significantly associated with an increased risk for female specific cancers. The association between the 1790 G/A polymorphism and lower breast cancer risk could be due to chance.

[Evaluation of brain dysfunction in chronic anoxic encephalopathy with evoked potentials].

AIM: To explore the relationship between evoked potentials (EPs) and chronic anoxic brain damage by chronic intermittent hypoxia (CIH), and provide theory evidence for diagnosis and treatment of anoxic encephalopathy. METHODS: BAEP and SLSEP were recorded in rat model with CIH (hypoxia group) and rat with normoxia (normal group). Morris water maze was used to observe learning and memory ability. Immunohistochemical method was used to investigate the expression levels of caspase-3 in brain tissue. RESULTS: The peak latency (PL) of wave I, III, V and the interpeak latency (IPL) of wave III - V, I - V in BAEP in hypoxia group were much longer than that of in normal group (P < 0.05). The PL of wave N1, P1 of SEP in hypoxia group were much longer than that of in normal group (P < 0.05). In the water mase test, the escape latency (EL) of hypoxia group was much longer than normal group (P < 0.01). The number of caspase-3 positive cells in hypoxia group was much larger than that of in normal group (P < 0.05). There was a positive correlation among BAEP, SLSEP, the number of caspase-3 positive neuron and EL of water mase. CONCLUSION: The alteration of BAEP and SLSEP has an apparent correlation with chronic anoxic brain damage. This provides theory evidence for diagnosis and treatment of anoxic encephalopathy.