Oxidative stress and its association with TNF-α-308 G/C and IL-1α-889 C/T gene polymorphisms in patients with diabetes and diabetic nephropathy

Hypoglycaemic Molecules for the Management of Diabetes Mellitus from Marine Sources

Diabetes mellitus (DM) is a chronic metabolic disorder recognized as a major health problem globally. A defective insulin activity contributes to the prevalence and expansion of DM. Treatment of DM is often hampered by limited options of conventional therapies and adverse effects associated with existing procedures. This has led to a spike in the exploration for potential therapeutic agents from various natural resources for clinical applications. The marine environment is a huge store of unexplored diversity of chemicals produced by a multitude of organisms. To date, marine microorganisms, microalgae, macroalgae, corals, sponges, and fishes have been evaluated for their anti-diabetic properties. The structural diversity of bioactive metabolites discovered has shown promising hypoglycaemic potential through in vitro and in vivo screenings via various mechanisms of action, such as PTP1B, α-glucosidase, α-amylase, β-glucosidase, and aldose reductase inhibition as well as PPAR alpha/gamma dual agonists activities. On the other hand, hypoglycaemic effect is also shown to be exerted through the balance of antioxidants and free radicals. This review highlights marine-derived chemicals with hypoglycaemic effects and their respective mechanisms of action in the management of DM in humans.

Association between polymorphisms of cytokine genes and diabetic nephropathy: A comprehensive systematic review and meta-analysis

AIM

Diabetic nephropathy (DN) is one of the microvascular complications of diabetes, leading to renal failure. In this study, we sought to systematically investigate the cytokine gene polymorphisms association with DN.

METHODS

A structured bibliographic search on PubMed, Scopus, and EMBASE databases has been performed to identify related papers. The odds ratio and corresponding 95% confidence intervals (CIs) were calculated to estimate the association.

RESULTS

Overall, the pooled results showed that the dominant models of TNF-α rs1800629, IL-1β rs16944, IL-8 rs4073, and IL-10 rs1800896 were associated with increased susceptibility to DN. Also, the pooled analyses of the mutant allele vs wild allele of TNF-α rs1800629, rs1799964, IL-1β rs16944, and IL-8 rs4073 were associated with increased susceptibility to DN. Rs1800629, rs16944, rs4073, and rs1800896 polymorphisms were significantly associated with DN susceptibility, suggesting its potential use as a genetic risk marker in the population.

Grey Relational Analysis Combined With Network Pharmacology to Identify Antioxidant Components and Uncover Its Mechanism From Moutan Cortex

The present study determines the potential antioxidants in Moutan Cortex (MC) and predicts its targets of anti-oxidative activities. The quantitative analysis and the free radical scavenging assays were conducted to detect the main components in MC and assess its anti-oxidant activities. The grey relational analysis and the network pharmacology approach were employed to predict its key components and targets of anti-oxidant activities. Six main constitutes in MCs were quantified by high performance liquid chromatography (HPLC) and its anti-oxidant activities were evaluated by DPPH and ABTS free radical scavenging methods. Then grey relational analysis was employed to predict the key components acting on anti-oxidative activity based on the chem-bio results. The predicted components and its mechanisms on anti-oxidation were uncovered by network pharmacology approach and cell test, respectively. The content of paeonol and paeoniflorin accounts for more than 80% the whole content of detected components. However, the two main ingredients showed a great variety among MCs. The antioxidant capacities of MCs also showed a great discrepancy based on DPPH and ABTS methods. The key components acting on anti-oxidation were identified to be paeonol, gallic acid and benzoylpaeoniflorin, and their potential therapeutic targets were predicted and verified, respectively. The present results reveal that MC has a significant antioxidant activity and the compounds of paeonol, gallic acid and benzoylpaeoniflorin could be considered as the promising antioxidant candidates with the property of suppressing oxidative stress and apoptosis.

Effects of fermented red bean extract on nephropathy in streptozocin-induced diabetic rats

Background

The antioxidant effects of Bacillus subtilis-fermented red bean (natto-red bean) extract (NRBE) in young (6 weeks old) Sprague–Dawley rats and aged (12 months old) mice had been reported previously.

Objective

To evaluate the antioxidant and anti-inflammatory effects of NRBE in the kidneys of streptozocin-induced diabetic rats.

Design

Normal control rats and diabetic rats were orally gavaged with saline and low-dose NRBE (100 mg/kg body weight [BW]), medium-dose NRBE (200 mg/kg BW), and high-dose NRBE (500 mg/kg BW), for 12 weeks and then sacrificed. Concentration of fasting glucose, adiponectin, renal function markers, antioxidative markers, and pro-inflammatory markers were measured.

Results

Oral administration of 50% ethanolic extract of NRBE with a dosage of 100 mg/kg BW, 200 mg/kg BW, or 500 mg/kg BW could improve the symptoms of kidney enlargement and renal function. Supplementation of NRBE can effectively inhibit the formation of renal reactive oxygen species and advanced-glycation end-products and increase renal glutathione content and serum adiponectin. A low dose of NRBE (100 mg/kg BW) decreased fasting blood sugar and renal interleukin (IL)-6 expression. Serum C-reactive protein, renal tumor necrosis factor-α, and monocyte chemoattractant protein-1 concentrations were decreased, and renal superoxide dismutase activity was increased in the medium-dose NRBE group. Twenty-four hour creatinine clearance and urinary albumin excretion also improved by medium-dose NRBE supplementation. In NRBE, total phenols and flavonoids were 6.3 mg gallic acid equivalent/g and 12.02 mg rutin equivalent/g, respectively, and kampherol was the major active antioxidant compound.

Conclusion

This study demonstrated that appropriate amount of NRBE, 200 mg/kg BW in rats, could prevent diabetic nephropathy by improving antioxidant status and inhibiting inflammation in renal tissue.

Cytokine Polymorphisms and Predisposition to Diabetic Nephropathy: A Meta-Analysis

BACKGROUND

Cytokine polymorphismsmight influence the predisposition to diabetic nephropathy (DN), but the results of already published related studies are still controversial and ambiguous.

OBJECTIVES

The authors designed this meta-analysis to more precisely estimate relationships between TNF-α/IL-1/IL-4/IL-8/IL-18polymorphisms and DN by pooling the results of already published related studies.

METHODS

The authors searched Pubmed, Embase, Web of Science and CNKI for already published studies. Thirty already published studies were pooled and analyzed in this meta-analysis.

RESULTS

The overall pooled meta-analysis results showed that distributions of TNF-α -238 G/A, TNF-α -308 G/A, TNF-α -1031 C/T, IL-1A -889 C/T, IL-1B -511 C/Tand IL-18 -137 G/C polymorphisms among patients and controls differed significantly. Additionally, we also found that distributions of TNF-α -308 G/A, IL-1B -511 C/T and IL-18 -137 G/C polymorphisms among patients and controls from Asians differed significantly, and the distribution of the IL-1B -511 C/T polymorphism among patients and controls from Caucasians also differed significantly.

CONCLUSION

The meta-analysis results demonstrated that TNF-α -238 G/A, TNF-α -308 G/A, TNF-α -1031 C/T, IL-1A -889 C/T, IL-1B -511 C/Tand IL-18 -137 G/Cpolymorphisms might influence predisposition to DN in the overall pooled population. Moreover, TNF-α -308 G/A, IL-1B -511 C/T and IL-18 -137 G/C polymorphisms might influence predisposition to DN in Asians, whereas the IL-1B -511 C/T polymorphism might also influence predisposition to DN in Caucasians.

The role of the TNF-α gene -308 G/A polymorphism in the development of diabetic nephropathy: An updated meta-analysis

BACKGROUND AND AIMS

Several studies have tried to link the relationship of tissue necrosis factor-alpha (TNF-α) -308 G/A polymorphism with the development of diabetic nephropathy (DN). However, these studies failed to reach a consensus due to conflicting results. This meta-analysis was done to thoroughly investigate the correlation between the polymorphism and DN development.

METHODS

To carry out the objective, patients with type 2 diabetes mellitus (T2DM) were used as controls, while patients who developed DN were utilized as cases. Eight studies (i.e., published between 2007 and 2018) were included in the present meta-analysis. Review Manager 5.3 was used to compute for the odds ratios (OR) and 95% confidence interval (CI) of the overall and post-outlier outcomes.

RESULTS

Overall, an association between DN development and the -308 G/A polymorphism was observed. However, Galbraith's plot analysis (as analyzed using Meta-Essentials) led to the removal of two studies, which significantly reduced heterogeneity. Post-outlier outcomes show significant results in the allelic (OR: 1.23; 95% CI: 1.01-1.50; p = 0.04) and co-dominant (OR: 1.60; 95% CI: 1.02-2.51; p = 0.04) models.

CONCLUSION

T2DM individuals with the -308 G/A polymorphism in the TNF-α gene are more likely to develop DN.

Effects of TNF-α-308G/A Polymorphism on the Risk of Diabetic Nephropathy and Diabetic Retinopathy: An Updated Meta-Analysis

Diabetic nephropathy (DN) and diabetic retinopathy (DR) are the major factors of morbidity and mortality in the patients with diabetes mellitus (DM). Growing studies have investigated the relationship between the TNF-α-308G/A polymorphism and the susceptibility to DN and DR, without achieving consensus. Thus, we conducted this meta-analysis to reach more comprehensive conclusions for these issues. Eligible studies were retrieved through electronic databases such as PubMed, Embase, Web of Science and China National Knowledge Infrastructure. Summary of odds ratios (OR) and 95% confidence intervals (CIs) were generated to evaluate the intensity of the associations. Statistical analyses were performed by STATA 11.0 and RevMan 5.2. There are fourteen eligible publications involving nineteen studies in this meta-analysis. TNF-α-308G/A polymorphism was significantly related to increasing risk of DN under recessive model (OR=1.37, 95% CI=1.03-1.83) and homozygous model (OR=1.54, 95% CI=1.15-2.06). Moreover, the similar results were also obtained in Asian groups for DN (recessive: OR=1.69, 95% CI=1.18-2.42; homozygous: OR=1.99, 95% CI=1.38-2.86; respectively), and significant association was also detected between TNF-α-308G/A and DN susceptibility in type 2 DM in recessive model (OR=1.39, 95% CI=1.02-1.89). No significant association was observed between TNF-α-308G/A and DR susceptibility in total analyses and subgroup analyses by ethnicity and type of DM. TNF-α-308G/A polymorphism may enhance the susceptibility to diabetic nephropathy, especially in Asian population and in T2DM patients, but not diabetic retinopathy.

Low methyl-esterified pectin protects pancreatic β-cells against diabetes-induced oxidative and inflammatory stress via galectin-3

Insufficient intake of dietary fibers in Western societies is considered a major contributing factor in the high incidence rates of diabetes. The dietary fiber pectin has been suggested to be beneficial for management of both Diabetes Type 1 and Type 2, but mechanisms and effects of pectin on insulin producing pancreatic β-cells are unknown. Our study aimed to determine the effects of lemon pectins with different degree of methyl-esterification (DM) on β-cells under oxidative (streptozotocin) and inflammatory (cytokine) stress and to elucidate the underlying rescuing mechanisms, including effects on galectin-3. We found that specific pectins had rescuing effects on toxin and cytokine induced stress on β-cells but effects depended on the pectin concentration and DM-value. Protection was more pronounced with low DM5 pectin and was enhanced with higher pectin-concentrations. Our findings show that specific pectins might prevent diabetes by making insulin producing β-cells less susceptible for stress.

Glucose Induces IL-1α-Dependent Inflammation and Extracellular Matrix Proteins Expression and Deposition in Renal Tubular Epithelial Cells in Diabetic Kidney Disease

Diabetes mellitus is linked with metabolic stress that induces cellular damage and can provoke renal inflammation and fibrotic responses that eventually lead to chronic kidney disease. Because the inflammasome, interleukin 1 (IL-1), IL-1α/IL-β, and IL-1R are central elements of kidney inflammation and pharmacological IL-1R antagonist (IL-1Ra) was shown to prevent or even reverse diabetic nephropathy (DN) in animal models, we explored the intrinsic expression of IL-1 molecules in kidney tissue of DN patients as regulators of renal inflammation. We used biopsies taken from DN patients and controls and show a high level of IL-1α expression in renal tubular epithelial cells, whereas both IL-1 agonistic molecules (i.e., IL-1α and IL-1β) were devoid of the glomeruli. Human proximal tubular kidney HK-2 cells exposed to high glucose (HG) gradually increase the expression of IL-1α but not IL-1β and induce the expression and deposition of extracellular matrix (ECM) proteins. We further demonstrate that in vitro ectopic addition of recombinant IL-1α in low glucose concentration leads to a similar effect as in HG, while supplementing excess amounts of IL-1Ra in HG significantly attenuates the ECM protein overexpression and deposition. Accordingly, inhibition of IL-1α cleaving protease calpain, but not caspapse-1, also strongly reduces ECM protein production by HK-2 cells. Collectively, we demonstrate that IL-1α and not IL-1β, released from renal tubular cells is the key inflammatory molecule responsible for the renal inflammation in DN. Our result suggests that the clinical use of IL-1Ra in DN should be promoted over the individual neutralization of IL-1α or IL-1β in order to achieve better blocking of IL-1R signaling.

GSTM1-null allele predicts rapid disease progression in nondialysis patients and mortality among South Indian ESRD patients

Chronic kidney disease (CKD) is one of the main causes of early death in humans worldwide. Glutathione S-Transferases (GSTs) are involved in a series of xenobiotics metabolism and free radical scavenging. The previous studies elucidated the interlink between GST variants and to the development of various diseases. The present case-control study performed to ascertain whether GST polymorphisms are associated with the incidence and advancement of CKD. From the Southern part of India, a total of 392 CKD patients (nondialysis, ND; n = 170, end-stage renal disease, ESRD; n = 222) and 202 healthy individuals were enrolled. Patients were followed-up for 70 months. Serum biochemical parameters were recorded, and the extraction of DNA was done from the patient's blood samples. To genotype study participants, multiplex PCR for GSTM1/T1 was performed. Statistical analysis was carried out to analyze the relationship between gene frequency and sonographic grading, as well as biochemical parameters for disease development. The GSTM1-null genotype showed threefold increased risk (OR = 2.9304; 95% CI 1.8959 to 4.5296; P < 0.0001) to CKD development and twofold increased risk (OR = 1.8379; 95% CI 1.1937 to 2.8299; P = 0.0057) to ESRD progression. During the mean follow-up of 41 months study, multivariate Cox regression analysis revealed that GSTM1-null genotype has 4 times increased the risk for all-cause rapid disease progression to ESRD among ND patients and 3.85-fold increased risk for death among ESRD patients. Survival analysis revealed that patients with GSTM1-present allele showed a significantly diminished risk of mortality compared to patients bearing the GSTM1-null allele among ESRD patients with a hazard ratio of 4.6242 (P < 0.0001). Thus, present data confirm that GSTM1-null genotype increased the risk for all-cause rapid disease progression to ESRD among ND patients. Based on our results, GSTM1-null genotype could be considered as a significant predictor for causing mortality among CKD patients when compared to all other variables.

The association of TNF-α -308G/A and -238G/A polymorphisms with type 2 diabetes mellitus: a meta-analysis

Tumor necrosis factor-α (TNF-α) is involved in insulin resistance and has long been a candidate gene implicated in type 2 diabetes mellitus (T2DM), however the association between TNF-α polymorphisms -308G/A and -238G/A and T2DM remains controversial. The present study sought to verify associations between these polymorphisms and T2DM susceptibility using a meta-analysis approach. A total of 49 case-control studies were selected up to October 2018. Statistical analyses were performed by STATA 15.0 software. The odds ratios (ORs) and 95% confidence intervals were calculated to estimate associations. Meta-analyses revealed significant associations between TNF-α -308G/A and T2DM in the allele model (P=0.000); the dominant model (P=0.000); the recessive model (P=0.001); the overdominant model (P=0.008) and the codominant model (P=0.000). Subgroup analyses also showed associations in the allele model (P=0.006); the dominant model (P=0.004) and the overdominant model (P=0.005) in the Caucasian and in the allele model (P=0.007); the dominant model (P=0.014); the recessive model (P=0.000) and the codominant model (P=0.000) in the Asian. There were no associations between TNF-α -238G/A and T2DM in the overall and subgroup populations. Meta-regression, sensitivity analysis and publication bias analysis confirmed that results and data were statistically robust. Our meta-analysis suggests that TNF-α -308G/A is a risk factor for T2DM in Caucasian and Asian populations. It also indicates that TNF-α -238G/A may not be a risk factor for T2DM. More comprehensive studies will be required to confirm these associations.

Anti-oxidant, anti-apoptotic, anti-hypoxic and anti-inflammatory conditions induced by PTY-2 against STZ-induced stress in islets

The earlier assessment of Pueraria tuberosa (PT) has shown anti-diabetic effects through enhancing incretin action and DPP-IV (Dipeptidyl peptidase-IV) inhibition. The aim of this work was to further explore the protective role of aqueous extract of Pueraria tuberosa tuber (PTY-2) against streptozotocin (STZ) induced islet stress in rats. Diabetes was induced by STZ (65 mg/kg body weight) in charles foster male rats. After 60 days of STZ administration, animals with blood glucose levels > 200 g/dL were considered as diabetic. All the rats were later divided into three groups: Group-1 (STZ untreated normal rats), Group-2 (Diabetic control), and Group-3 (PTY-2 [50 mg/100 g bw treatment for next 10 days to diabetic rats). The rats were then sacrificed after the 10^th day of treatment accordingly. STZ treatment led to an increase in expression of Matrix metalloproteinases-9 (MMP-9), Tumour necrosis factor-α (Tnf-α), Hypoxia inducible factor-α (HIF-1α), Vascular endothelial growth factor (VEGF), Interleukin-6 (IL-6), Protein kinase C-ε (PKC-ε), Nuclear factor kappa-light-chain-enhancer of activated B-cells (NFkB), and Caspase-3. Reverse Transcriptase-PCR (RT-PCR), Immunohistochemistry and Western-Blot analysis showed an increase in the expressions of Superoxide Dismutase (SOD) and Nephrin, and a decrease in the expressions of NFkB, PKC-ε, TNF-α, MMP-9, HIF-1α, VEGF, Caspase-3 and IL-6 after 10 days of PTY-2 treatment. The results showed that PTY-2 favorably changed all the expressions via anti-oxidant, anti-apoptotic, anti-hypoxic and anti-inflammatory pathways, making itself as a protective agent against STZ induced islet stress. Further evaluation of PTY-2 might be helpful in establishing its role in the management of diabetes mellitus.

Biofunctionalization of selenium nanoparticles with a polysaccharide from Rosa roxburghii fruit and their protective effect against H2O2-induced apoptosis in INS-1 cells

Defective glucose-stimulated insulin secretion (GSIS) induced by chronic exposure to reactive oxygen species (ROS) is a hallmark of type 2 diabetes mellitus (T2DM). Therefore, it is of great interest to search for biofunctional agents with antioxidant activity to protect pancreatic islet cells from oxidative damage. In the present study, selenium nanoparticles (SeNPs) functionalized with a novel polysaccharide (RTFP-3) extracted from Rosa roxburghii fruit were first prepared via a facile, single-step and green in situ synthesis method. The in vitro protective effects of RP3-SeNPs on INS-1 cells against H2O2-induced cell apoptosis were investigated. Structural characterization indicated that RTFP-3-functionalized SeNPs (RP3-SeNPs) with an average diameter of 104.5 nm were highly uniform and extremely stable in comparison with bare SeNPs. The results of bioassays revealed that RP3-SeNPs possessed much higher protective and suppressive activities against H2O2-induced apoptosis of INS-1 cells in comparison with their individual components. After treatment with an RP3-SeNPs solution (2 μg mL-1), the cell viability of INS-1 cells reached about 89.34%. Mechanistic studies demonstrated that RP3-SeNPs effectively blocked the overproduction of intracellular ROS, mitochondrial damage, and the activation of caspase-3, caspase-8, and caspase-9 in INS-1 cells, which indicated that RP3-SeNPs functioned via attenuating oxidative stress and downregulating the expression of uncoupling protein-2 (UCP-2). Our findings suggest that RP3-SeNPs can function as a promising candidate to prevent or limit the dysfunction of β-cells.

Characterization and Hypoglycemic Activity of a Rhamnan-Type Sulfated Polysaccharide Derivative

Polysaccharide chromium (III) derivatives are gaining increasing attention in improving type 2 diabetes. In this study, the sulfated polysaccharide from Enteromorpha prolifera (SPE) with 4.8 kDa was prepared by specific enzymatic hydrolysis. The obtained SPE was used to prepare a rhamnan-type sulfated polysaccharide derivative (SPED). Results indicated that O-H, C=O, and S=O were effectively involved in the chelation of SPED (chromium content 20.26%). Acute (half lethal dose > 2.38 g/kg) and sub-acute toxicity showed that SPED had no damaging effects on mice. Anti-diabetic experiment demonstrated that SPED improved glucose metabolism. Moreover, SPED promoted the PI3K/PKB/GSK-3β signaling pathway by regulating mRNA expression of insulin receptors (IR), insulin receptor substrate 2 (IRS-2), phosphatidylinositol 3 kinase (PI3K), protein kinase B (PKB), and glycogen synthase kinase 3β (GSK-3β). In conclusion, the SPED might represent a novel marine-derived candidate against hyperglycemia, which may undergo further pharmaceutical development as a hypoglycemic agent.

Influence of IL-6, IL-10, IFN-γ and TNF-α genetic variants on susceptibility to diabetic kidney disease in type 2 diabetes mellitus patients

BACKGROUND

Data from previous studies on the role of inflammatory cytokines as biomarkers for diabetic kidney disease (DKD) are contradictory. The association of a particular inflammatory cytokine single nucleotide polymorphism (SNP) with susceptibility to DKD has not been consistently replicated. We aimed to investigate the utility of inflammatory cytokines as biomarkers for DKD in type 2 diabetes mellitus (T2DM) patients. Association of inflammatory cytokine gene SNPs with the development of DKD was also explored.

SUBJECTS AND METHODS

One hundred and fifty-nine Kuwaiti subjects were recruited in this study, including 50 T2DM patients without DKD, 67 diabetic DKD patients and 42 healthy subjects. Plasma levels of interleukin-6 (IL-6), IL-10, interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) were measured by enzyme-linked immunosorbent assays. Nine SNPs, including 2 SNPs in IL-6, 3 SNPs in IL-10, 1 SNP in IFN-γ and 3 SNPs in TNF-α, were genotyped using TaqMan SNP genotyping assays.

RESULTS

Diabetic DKD patients showed higher IL-6, IL-10, IFN-γ and TNF-α levels than those without DKD. Diabetic DKD patients had a significantly higher frequency of IL-10 - 1082 A allele than those without DKD (p = 0.001). No significant association of IL-6 - 174/-597 haplotypes with DKD risk was detected (p = 0.188). Distribution of IL-10 - 592/-819/-1082 haplotypes differ significantly between T2DM patients with/without DKD (p = 0.014). Diabetic DKD patients had a significantly lower frequency of IL-10 - 592C/-819C/-1082G haplotype than those without DKD (p = 0.002).

CONCLUSIONS

Although inflammatory cytokine genotypes and, more importantly, haplotypes may have the potential to identify those patients at risk of DKD, hence, improving DKD predisposition prediction, further investigations regarding their real clinical significance is warranted in a large cohort of patients.

The Effects of Coenzyme Q10 Supplementation on Glucose Metabolism, Lipid Profiles, Inflammation, and Oxidative Stress in Patients With Diabetic Nephropathy: A Randomized, Double-Blind, Placebo-Controlled Trial

OBJECTIVE

Data on the effects of coenzyme Q10 (CoQ10) supplementation on glucose metabolism, lipid profiles, inflammation, and oxidative stress in subjects with diabetic nephropathy (DN) are scarce. This research was done to determine the effects of CoQ10 supplementation on metabolic status in subjects with DN.

METHODS

This randomized double-blind placebo-controlled clinical trial was done in 50 subjects with DN. Participants were randomly assigned into two groups to intake either 100 mg/day CoQ10 supplements (n = 25) or placebo (n = 25) for 12 weeks. Fasting blood samples were obtained at first and after 12-week intervention to quantify metabolic profiles.

RESULTS

After 12 weeks of treatment, compared with the placebo, CoQ10 supplementation resulted in significant decreases in serum insulin levels (-3.4 ± 6.8 vs +0.8 ± 6.4 µIU/mL, p = 0.02), homeostasis model of assessment-estimated insulin resistance (-1.0 ± 2.0 vs +0.2 ± 1.8, p = 0.03), homeostasis model of assessment-estimated B cell function (-12.3 ± 26.3 vs +3.5 ± 23.1, p = 0.02) and HbA1c (-1.1 ± 1.0 vs -0.1 ± 0.2%, p < 0.001), and a significant improvement in quantitative insulin sensitivity check index (+0.009 ± 0.01 vs -0.006 ± 0.01, p = 0.01). In addition, CoQ10 supplementation significantly decreased plasma malondialdehyde (MDA) (-0.6 ± 0.5 vs +0.5 ± 1.0 µmol/L, p < 0.001) and advanced glycation end products levels (AGEs) (-316.4 ± 380.9 vs +318.6 ± 732.0 AU, p < 0.001) compared with the placebo. Supplementation with CoQ10had no significant impacts on fasting plasma glucose (FPG), lipid profiles, and matrix metalloproteinase-2 (MMP-2) compared with the placebo.

CONCLUSIONS

Taken together, our study demonstrated that CoQ10 supplementation for 12 weeks among DN patients had favorable effects on glucose metabolism, MDA, and AGEs levels, but unchanged FPG, lipid profiles, and MMP-2 concentrations.

ALA/LA ameliorates glucose toxicity on HK-2 cells by attenuating oxidative stress and apoptosis through the ROS/p38/TGF-β1 pathway

BACKGROUND

Growing evidence indicates that oxidative stress (OS) plays a pivotal role in Diabetic nephropathy (DN). In a previous study we demonstrated that ALA/LA protected HK-2 cells against high glucose-induced cytotoxicity. So we aimed to establish the glucose injury model of HK-2 cells and investigate the beneficial effects of ALA/LA on high glucose-induced excessive production of TGF-β1 and the possible mechanisms mediating the effects.

METHODS

The expression of OS markers in high glucose-induced HK-2 cells treated with ALA/LA., including the antioxidant enzymes and reactive oxygen species (ROS) production, as well as the apoptosis rate were assayed by ELISA and flow cytometry. The p38/transforming growth factor β1 (TGF-β1) signal pathway were measured by real-time RT-PCR and western blot.

RESULTS

The modeling condition of glucose toxicity on HK-2 cells was at the glucose concentration of 40.9 mM. ALA/LA can significantly increase the activities of antioxidant enzymes and decrease ROS production stimulated by high glucose. The study also found that ALA/LA caused a decrease in the apoptosis rate and TGF-β1 level of HK-2 cells under high glucose stress through the ROS/p38 pathway.

CONCLUSIONS

ALA/LA exerts protective effects in vitro through inhibition of ROS generation, down regulation of the activation of the p38MAPK pathway and the expression of TGF-β1 in HK-2 cells.

MiR-30a targets IL-1α and regulates islet functions as an inflammation buffer and response factor

Diabetes is an inflammatory disease. Inflammation plays an important role in islet functions. However, the exact mechanisms by which inflammation affects islet functions remain unclear. In this study, we investigated the regulatory effects of miR-30a on inflammation and islet functions. The results indicate that miR-30a serves as an inflammation-resolving buffer factor by targeting interleukin 1a (IL-1α) in immune cells and in islet cells, which might play an important role in inflammation homeostasis. miR-30a ameliorates islet functions in an inflammatory micro-environment by targeting the IL-1α/nuclear factor kappa B (NFKB) p65 subunit (p65)/p62 (SQSTM1)/insulin axis, which can be developed into a novel antidiabetic approach. miR-30a serves as a promising inflammation-response biomarker in inflammatory diseases and is possibly activated by the toll-like receptor 4 (TLR4)/IL-1α/NFKB pathways. However, the exact molecular mechanisms by which miR-30a regulates inflammation and islet functions as well as the potential applications in transitional medicine require further elucidation.

Serum Interleukin-18 and Its Gene Haplotypes Profile as Predictors in Patients with Diabetic Nephropathy

BACKGROUND:

Diabetic nephropathy (DN) is known as an acute microvascular complexity as a subsequence progression in diabetes mellitus type 1 and 2. Many evidence pointed that the proinflammatory cytokine Interleukin (IL)-18 might be involved in the pathogenesis of DN.

AIM:

The current study aimed to evaluate the association of serum IL-18 and its promoter gene polymorphisms with diabetic nephropathy.

METHODS:

This study included 62 diabetic nephropathy patients (DN group) compared to 52 diabetes mellitus patients (DM group). The two groups were subjected to anthropometry assessment, molecular studies including SNP genotyping by RFLP and finally statistical analysis.

RESULTS:

The assessment of the serum IL-18 level and the frequencies of its allele and haplotype: -137G/C, -607C/A and -656G/T among the DN and DM subjects revealed that -137G allele has significant variation between DN and DM subjects (about 80.8%, P = 0.05) but, no significant variation in -607 or -656 alleles IL-18 gene promoter.

CONCLUSION:

These data confirm the impact of high serum IL-18 and the haplotype of the polymorphism located in the promoter region of the IL-18 gene with the DN.

DNA Demethylation Rescues the Impaired Osteogenic Differentiation Ability of Human Periodontal Ligament Stem Cells in High Glucose

Diabetes mellitus, characterized by abnormally high blood glucose levels, gives rise to impaired bone remodeling. In response to high glucose (HG), the attenuated osteogenic differentiation capacity of human periodontal ligament stem cells (hPDLSCs) is associated with the loss of alveolar bone. Recently, DNA methylation was reported to affect osteogenic differentiation of stem cells in pathological states. However, the intrinsic mechanism linking DNA methylation to osteogenic differentiation ability in the presence of HG is still unclear. In this study, we found that diabetic rats with increased DNA methylation levels in periodontal ligaments exhibited reduced bone mass and density. In vitro application of 5-aza-2′-deoxycytidine (5-aza-dC), a DNA methyltransferase inhibitor, to decrease DNA methylation levels in hPDLSCs, rescued the osteogenic differentiation capacity of hPDLSCs under HG conditions. Moreover, we demonstrated that the canonical Wnt signaling pathway was activated during this process and, under HG circumstances, the 5-aza-dC-rescued osteogenic differentiation capacity was blocked by Dickkopf-1, an effective antagonist of the canonical Wnt signaling pathway. Taken together, these results demonstrate for the first time that suppression of DNA methylation is able to facilitate the osteogenic differentiation capacity of hPDLSCs exposed to HG, through activation of the canonical Wnt signaling pathway.

Association between -308G/A TNFA Polymorphism and Susceptibility to Type 2 Diabetes Mellitus: A Systematic Review

Diabetes mellitus (DM) is considered to be a worldwide epidemic disease and its type 2 form comprises more than 95% of all cases. Tumor necrosis factor-alpha (TNF-α) is a proinflammatory cytokine. Its dysregulation has been implicated in a variety of human diseases, including type 2 diabetes mellitus (T2DM). The control of expression of this cytokine is associated with insulin resistance and has a strong genetic influence. In order to understand this relationship, the literature from all case-control studies since 2000 to date was reviewed. The genotypes frequency results presented in ten publications with different ethnicities were compared. The correlation between the TNFA promoter genotypes and the risk of developing T2DM remains controversial due to the many discrepancies between the different studies available. Ethnic differences may play a role in these conflicting results, since the distribution of TNFA promoter polymorphisms is distinctive between individuals of dissimilar racial origin. Hence, although the relationship between T2DM incidence and presence of polymorphisms at position -308 of the TNFA gene is not entirely clear, the results of these studies suggest the need for further investigation.

Role of upstream stimulatory factor 2 in diabetic nephropathy

Diabetic nephropathy (DN) is the most common cause of end-stage renal disease (ESRD). About 20%-30% of people with type 1 and type 2 diabetes develop DN. DN is characterized by both glomerulosclerosis with thickening of the glomerular basement membrane and mesangial matrix expansion, and tubulointerstitial fibrosis. Hyperglycemia and the activation of the intra-renal renin-angiotensin system (RAS) in diabetes have been suggested to play a critical role in the pathogenesis of DN. However, the mechanisms are not well known. Studies from our laboratory demonstrated that the transcription factor-upstream stimulatory factor 2 (USF2) is an important regulator of DN. Moreover, the renin gene is a downstream target of USF2. Importantly, USF2 transgenic (Tg) mice demonstrate a specific increase in renal renin expression and angiotensin II (AngII) levels in kidney and exhibit increased urinary albumin excretion and extracellular matrix deposition in glomeruli, supporting a role for USF2 in the development of diabetic nephropathy. In this review, we summarize our findings of the mechanisms by which diabetes regulates USF2 in kidney cells and its role in regulation of renal renin-angiotensin system and the development of diabetic nephropathy.