Hyperglycemia-induced Oxidative Stress Research Articles

Nimbidiol protects from renal injury by alleviating redox imbalance in diabetic mice.

Chronic hyperglycemia-induced oxidative stress plays a crucial role in the development of diabetic nephropathy (DN). Moreover, adverse extracellular matrix (ECM) accumulation elevates renal resistive index leading to progressive worsening of the pathology in DN. Nimbidiol is an alpha-glucosidase inhibitor, isolated from the medicinal plant, 'neem' (Azadirachta indica) and reported as a promising anti-diabetic compound. Previously, a myriad of studies demonstrated an anti-oxidative property of a broad-spectrum neem-extracts in various diseases including diabetes. Our recent study has shown that Nimbidiol protects diabetic mice from fibrotic renal dysfunction in part by mitigating adverse ECM accumulation. However, the precise mechanism remains poorly understood. The present study aimed to investigate whether Nimbidiol ameliorates renal injury by reducing oxidative stress in type-1 diabetes. To test the hypothesis, wild-type (C57BL/6J) and diabetic Akita (C57BL/6-Ins2Akita/J) mice aged 10-14weeks were used to treat with saline or Nimbidiol (400μgkg-1 day-1) for 8weeks. Diabetic mice showed elevated blood pressure, increased renal resistive index, and decreased renal vasculature compared to wild-type control. In diabetic kidney, reactive oxygen species and the expression levels of 4HNE, p22phox, Nox4, and ROMO1 were increased while GSH: GSSG, and the expression levels of SOD-1, SOD-2, and catalase were decreased. Further, eNOS, ACE2, Sirt1 and IL-10 were found to be downregulated while iNOS and IL-17 were upregulated in diabetic kidney. The changes were accompanied by elevated expression of the renal injury markers viz., lipocalin-2 and KIM-1 in diabetic kidney. Moreover, an upregulation of p-NF-κB and a downregulation of IkBα were observed in diabetic kidney compared to the control. Nimbidiol ameliorated these pathological changes in diabetic mice. Altogether, the data of our study suggest that oxidative stress largely contributes to the diabetic renal injury, and Nimbidiol mitigates redox imbalance and thereby protects kidney in part by inhibiting NF-κB signaling pathway in type-1 diabetes.

Microalgal Macular Pigment Alleviated the Pathogenic Process in the Streptozotocin-induced Diabetic ApoE-deficient Mice

Type 2 diabetes mellitus (T2DM) is one of the fastest growing epidemics in human history and characteristic is insulin resistance (IR), and endocrine disorder that promoted to decline in insulin production and inhibit cellular effects. Patients with T2DM would lead to many complications such as diabetic retinopathy, diabetic nephropathy, diabetic neuropathy, diabetic foot, atherosclerosis, vascular inflammation, and hepatogenous diabetes due to hyperglycemia. Even after using medical treatment and lifestyle modifications, it is still hard to achieve the goal of reducing blood glucose to an optimal level. Microalga Chlorella sp., a unicellular green alga that has been used as a health food and nutritional product in the last few decades. Macular pigment (MP) produced by Chlorella sp. consists of rich lutein and zeaxanthin, which are regarded as the antioxidants to hyperglycemia-induced oxidative stress. MP is widely used in eye health care, however, few studies focused on scientifically exploring the protection mechanism of MP on diabetes mellitus. Therefore, this study aimed to explore MP extracted from Chlorella on reducing retinopathy and atherosclerosis damages in the diabetic apolipoprotein E deficient mice (ApoE−/−) with high-fat diet feeding and streptozotocin treatment. The results show that MP supplement could significantly reduce glucose tolerance, IR, inflammatory cytokines TNF-α and IL-6 levels, and the serum level of disease markers, i.e., triglyceride (TG), total cholesterol (TCHO), glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), total protein (TP), albumin (ALB), and blood urea nitrogen (BUN) in the diabetic ApoE−/− mice. In addition, the expression levels of cellular antioxidant enzymes were significantly increased and the adhesion factors as well as MAPK pathway proteins in renal tissues were significantly reduced after MP supplementation. The pathological changes of pancreatic islet morphology, hepatic lipid accumulation, outer nuclear layer and aortic plaque of the diabetic ApoE−/− mice were significantly alleviated by MP supplement. At present, most MP products are derived from marigold, Calendula offcinalis, in the market. However, microalgae cultivation includes the advantages on no seasonal limit, no competition, high yield and carbon reduction compared with other plants. In summary, the microalgal MP improved IR, ameliorated atherosclerosis, and alleviated retinopathy in the diabetic ApoE−/− mice. Consequently, the microalgal MP is potentially to be a healthy food ingredient for the biological effcacy of scavenging free radicals and stabilizing blood glucose. This work was supported by the grants of NSTC 110-2312-B-A49-001-MY3, NSTC 112-2811-B-A49 -501, NSTC 112-2811-B-A49 -503, NSTC 112-2321-B-A49 -018 and NSTC 112-2321-B-A49-005, from the National Science and Technology Council (NSTC), Taiwan. This work was also financially supported by the “Center for Intelligent Drug Systems and Smart Bio-devices (IDS2B)” from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project of the National Yang Ming Chiao Tung University and Ministry of Education (MOE), Taiwan. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The role of vascular adhesion protein-1 in diabetes and diabetic complications.

Vascular adhesion protein-1 (VAP-1) plays a dual role with its adhesive and enzymatic properties, facilitating leukocyte migration to sites of inflammation and catalyzing the breakdown of primary amines into harmful by-products, which are linked to diabetic complications. Present in various tissues, VAP-1 also circulates in a soluble form in the bloodstream. Diabetes is associated with several complications such as cardiovascular disease, retinopathy, nephropathy, and neuropathy, significantly contributing to disability and mortality. These complications arise from hyperglycemia-induced oxidative stress, inflammation, and the formation of advanced glycation end-products (AGEs). Earlier research, including our own from the 1990s and early 2000s, has underscored the critical role of VAP-1 in these pathological processes, prompting extensive investigation into its contribution to diabetic complications. In this review, we examine the involvement of VAP-1 in diabetes and its complications, alongside its link to other conditions related to diabetes, such as cancer and metabolic dysfunction-associated fatty liver disease. We also explore the utility of soluble VAP-1 as a biomarker for diabetes, its complications, and other related conditions. Since the inhibition of VAP-1 to treat diabetic complications is a novel and promising treatment option, further studies are needed to translate the beneficial effect of VAP-1 inhibitors observed in animal studies to clinical trials recruiting human subjects. Besides, future studies should focus on using serum sVAP-1 levels for risk assessment in diabetic patients, identifying those who need intensive glycemic control, and determining the patient population that would benefit most from VAP-1 inhibitor therapies.

Relation of Serum Bilirubin in Physiological Range with Spot Urine Albumin to Creatinine Ratio and eGFR Among Diabetic Patients with or without Nephropathy

Recent studies have suggested a potential role of bilirubin as an antioxidant to protect diabetic patients from hyperglycemia-induced oxidative stress thereby preventing diabetic complications. Diabetic nephropathy is a serious microvascular complication which is determined by increased urinary albumin to creatinine ratio and reduced eGFR. The present work aimed to study the relation of the simple biochemical parameter of serum bilirubin level with the estimated glomerular filtration rate (eGFR) and spot urine albumin to creatinine ratio in diabetic patients with or without nephropathy. This cross sectional study was done in the department of Biochemistry and Molecular Biology, Bangladesh Institute of Research and Rehabilitation in Diabetes, Endocrine and Metabolic Disorders (BIRDEM) Academy from July 2017 to June 2018. We have taken 63 diabetic patients without nephropathy and 63 diabetic patients with nephropathy.Data about clinical and biochemical parameters (blood pressure, BMI, fasting serum glucose, estimated GFR, serum bilirubin and spot urine ACR etc.) were measured by appropriate methods. We used student’s t test and Pearson’s correlation coefficient to detect the relationship of serum bilirubin with other variables All statistical tests were considered at 5% level of significance. We found diabetic patients with nephropathy have significantly lower serum bilirubin (p<0.001) than diabetic patients without nephropathy (0.46±0.18 and 0.64± 0.21 mg/d respectively). Pearson’s correlation test showed that serum bilirubin positively correlated with eGFR (r=0.312, p=0.013) in diabetic patients with nephropathy. This study concluded that low serum bilirubin level is associated with eGFR in diabetic patients with nephropathy.
 Bangladesh J Med Biochem 2019; 12(2): 16-22

C2CD4B Evokes Oxidative Stress and Vascular Dysfunction via a PI3K/Akt/PKCα-Signaling Pathway.

High glucose-induced endothelial dysfunction is an important pathological feature of diabetic vasculopathy. While genome-wide studies have identified an association between type 2 diabetes mellitus (T2DM) and increased expression of a C2 calcium-dependent domain containing 4B (C2CD4B), no study has yet explored the possible direct effect of C2CD4B on vascular function. Vascular reactivity studies were conducted using a pressure myograph, and nitric oxide and oxidative stress were assessed through difluorofluorescein diacetate and dihydroethidium, respectively. We demonstrate that high glucose upregulated both mRNA and protein expression of C2CD4B in mice mesenteric arteries in a time-dependent manner. Notably, the inhibition of C2CD4B expression by genetic knockdown efficiently prevented hyperglycemia-induced oxidative stress, endothelial dysfunction, and loss of nitric oxide (NO) bioavailability. Recombinant C2CD4B evoked endothelial dysfunction of mice mesenteric arteries, an effect associated with increased reactive oxygen species (ROS) and decreased NO production. In isolated human umbilical vein endothelial cells (HUVECs), C2CD4B increased phosphorylation of endothelial nitric oxide synthase (eNOS) at the inhibitory site Thr495 and reduced eNOS dimerization. Pharmacological inhibitors of phosphoinositide 3-kinase (PI3K), Akt, and PKCα effectively attenuated oxidative stress, NO reduction, impairment of endothelial function, and eNOS uncoupling induced by C2CD4B. These data demonstrate, for the first time, that C2CD4B exerts a direct effect on vascular endothelium via a phosphoinositide 3-kinase (PI3K)/Akt/PKCα-signaling pathway, providing a new perspective on C2CD4B as a promising therapeutic target for the prevention of oxidative stress in diabetes-induced endothelial dysfunction.

UCP2-SIRT3 Signaling Relieved Hyperglycemia-Induced Oxidative Stress and Senescence in Diabetic Retinopathy.

Diabetic retinopathy (DR) is one of the most common reasons for blindness. uncoupling protein 2 (UCP2), an uncoupling protein located in mitochondria, has been reported to be related to metabolic and vascular diseases. This research aimed to illustrate the function and mechanism of UCP2 in the pathogenesis of DR. Human epiretinal membranes were collected to investigate the expression of UCP2 by quantitative real-time polymerase chain reaction (qRT-PCR) and immunofluorescence. Primary human retinal microvascular endothelial cells (HRECs) were cultured in high glucose (HG) to establish an in vitro cell model for DR. Flow cytometry analysis was used to measure intracellular reactive oxygen species (ROS). Senescence levels were evaluated by the senescence-associated beta-galactosidase (SA-β-gal) assay, the expression of senescence marker P21, and cell-cycle analysis. Adenovirus-mediated UCP2 overexpression or knockdown and specific inhibitors were administered to investigate the underlying regulatory mechanism. Proliferative fibrovascular membranes from patients with DR illustrated the downregulation of UCP2 and sirtuin 3 (SIRT3) by qRT-PCR and immunofluorescence. Persistent hyperglycemia-induced UCP2 downregulation in the progress of DR and adenovirus-mediated UCP2 overexpression protected endothelial cells from hyperglycemia-induced oxidative stress and senescence. Under hyperglycemic conditions, UCP2 overexpression attenuated NAD+ downregulation; hence, it promoted the expression and activity of SIRT3, an NAD+-dependent deacetylase regulating mitochondrial function. 3-TYP, a selective SIRT3 inhibitor, abolished the UCP2-mediated protective effect against oxidative stress and senescence. UCP2 overexpression relieved oxidative stress and senescence based on a novel mechanism whereby UCP2 can regulate the NAD+-SIRT3 axis. Targeting oxidative stress and senescence amelioration, UCP2-SIRT3 signaling may serve as a method for the prevention and treatment of DR and other diabetic vascular diseases.

The Effects of Resveratrol Supplementation on the Quality of Life of Diabetic Patients with Neuropathy: Small Randomized Clinical Trial

The diabetic neuropathy complication exerts a considerable decline in the level of patient’s well-being. The main approaches to hamper the progression of diabetic complications and improve patient’s life quality are controlling the glycemic levels and amelioration of the hyperglycemia-induced neuroinflammation, oxidative stress and pain. Supplementation of appropriate anti-inflammatory and anti-oxidants such as resveratrol may therefore be effective in the management of diabetic complications. The aim of this trial was to assess resveratrol’s impact on improving life quality of patients with the neuropathic complication of diabetes. Sixty-one patients with diabetic neuropathy were recruited in this double-blinded placebo-controlled trial. Patients were randomized into the resveratrol (n=31) group; who received a 500mg resveratrol capsule once daily concomitantly with the conventional hypoglycemic agents for three months, and the placebo (n=30) group. From each group 25 patients completed the study. The quality of life (QoL) of the patients was estimated utilizing RAND 36-item survey questionnaire. Fasting blood glucose levels were analyzed at the baseline and on the last day of the 3rd month. There was a significant decrement (p< 0.001) in the fasting serum glucose level of the patients supplemented with resveratrol at the end of the 3rd month, in comparison with the patient using the placebo. There was also a significant improvement in patient’s severity of pain (p<0.001) as shown in the bodily pain score of the RAND 36 scale and a remarkable (p < 0.05) improvement in physical functioning, physical health, social functioning, emotional well-being, energy/fatigue, and health change subscales of the questionnaire. The study concluded that resveratrol is the polyphenol that has a positive effect on reducing pain associated with diabetic neuropathy and improving the overall QoL of the patient.

Effects of hyperglycemia on the TGF-β pathway in trabecular meshwork cells

BackgroundHyperglycemia, which can lead to apoptosis, hypertrophy, fibrosis, and induces hyperinflammation in diabetic vascular complications due to oxidative stress. In order to elucidate the potential dual roles and regulatory signal transduction of TGF-β1 and TGF-β2 in human trabecular meshwork cells (HTMCs), we established an oxidative cell model in HTMCs using 5.5, 25, 50, and 100 mM d-glucose-supplemented media and characterized the TGF-β-related oxidative stress pathway. MethodsFurther analysis was conducted to investigate oxidative damage and protein alterations in the HTMC caused by the signal transduction. This was done through a series of qualitative cell function studies, such as cell viability/apoptosis analysis, intracellular reactive oxygen species (ROS) detection, analysis of calcium release concentration, immunoblot analysis to detect the related protein expression alteration, and analysis of cell fibrosis to study the effect of different severities of hyperglycemia. Also, we illustrated the role of TGF-β1/2 in oxidative stress-induced injury by shRNA-mediated knockdown or stimulation with recombinant human TGF-β1 protein (rhTGF-β1). ResultsResults from the protein expression analysis showed that p-JNK, p-p38, p-AKT, and related SMAD family members were upregulated in HTMCs under hyperglycemia. In the cell functional assays, HTMCs treated with rhTGFβ-1 (1 ng/mL) under hyperglycemic conditions showed higher proliferation rates and lower ROS and calcium levels. ConclusionsTo summarize, mechanistic analyses in HTMCs showed that hyperglycemia-induced oxidative stress activated TGF-β1 along with its associated pathway. General Significance: While at low concentrations, TGF-β1 protects cells from antioxidation, whereas at high concentrations, it accumulates in the extracellular matrix, causing further HTMC dysfunction.

Current advancement in the preclinical models used for the assessment of diabetic neuropathy.

Diabetic neuropathy is one of the prevalent and debilitating microvascular complications of diabetes mellitus, affecting a significant portion of the global population. Relational preclinical animal models are essential to understand its pathophysiology and develop effective treatments. This abstract provides an overview of current knowledge and advancements in such models. Various animal models have been developed to mimic the multifaceted aspects of human diabetic neuropathy, including both type 1 and type 2 diabetes. These models involve rodents (rats and mice) and larger animals like rabbits and dogs. Induction of diabetic neuropathy in these models is achieved through chemical, genetic, or dietary interventions, such as diabetogenic agents, genetic modifications, or high-fat diets. Preclinical animal models have greatly contributed to studying the intricate molecular and cellular mechanisms underlying diabetic neuropathy. They have shed light on hyperglycemia-induced oxidative stress, neuroinflammation, mitochondrial dysfunction, and altered neurotrophic factor signaling. Additionally, these models have allowed for the investigation of morphological changes, functional alterations, and behavioral manifestations associated with diabetic neuropathy. These models have also been crucial for evaluating the efficacy and safety of potential therapeutic interventions. Novel pharmacological agents, gene therapies, stem cell-based approaches, exercise, dietary modifications, and neurostimulation techniques have been tested using these models. However, limitations and challenges remain, including physiological differences between humans and animals, complex neuropathy phenotypes, and the need for translational validation. In conclusion, preclinical animal models have played a vital role in advancing our understanding and management of diabetic neuropathy. They have enhanced our knowledge of disease mechanisms, facilitated the development of novel treatments, and provided a platform for translational research. Ongoing efforts to refine and validate these models are crucial for future treatment developments for this debilitating condition.

Nephroprotective Effects of Mycophenolate Mofetil and Glibenclamide on Streptozotocin-induced Diabetic Renal Injury in Rats: An Experimental Study.

Diabetic renal injury is a microvascular complication associated with inflammation and oxidative stress, culminating in renal dysfunction. Conventionally, it is treated with hypoglycemic agents to address metabolic perturbations. However, the way to mitigate immunological, inflammation, and oxidative stress have seldom been studied. Hence, in the present study, the nephroprotective role of immunosuppressive and anti-inflammatory drugs, mycophenolate mofetil (MMF) in combination with the oral hypoglycemic agent glibenclamide, on streptozotocin (STZ)- induced diabetic renal damage was studied. Bodyweight, fasting blood glucose, and glycosylated hemoglobin levels were altered in the diabetic rats. Furthermore, renal injury was indicated by abnormal levels of urinary protein and creatinine and serum markers of renal function in diabetic rats. Hyperglycemia-induced oxidative stress and inflammation were also observed in the diabetic rats. The combination of MMF and glibenclamide treatment significantly attenuated the abnormal effects of hyperglycemia, oxidative stress, and inflammation-induced renal injury in diabetic rats. Histopathological studies confirmed the nephroprotective role of MMF and glibenclamide by reversing renal injury in diabetic rats. The present study suggests that MMF and glibenclamide have a protective role in STZ-induced diabetic renal damage.

Fucoidan from Sargassum wightii reduces oxidative stress through upregulating Nrf2/HO-1 signaling pathway in alloxan-induced diabetic cardiomyopathy rats.

Diabetic cardiomyopathy (DCM) is a form of cardiac dysfunction caused by diabetes, increasing heart failure and death. Studies shown that hyperglycemia-induced oxidative stress significantly affects heart structure and functional changes during diabetic cardiomyopathy. Fucoidans are sulfated polysaccharide derived from naturally available seaweeds and reported for various biological functions such as antioxidant, anti-diabetic, and anti-inflammatory. However, the therapeutic potential of Indian seaweeds against DCM remains largely unexplored. Therefore, the current study aimed to work on the cardioprotective effect of extracted fucoidan from Sargassum wightii (SwF) in alloxan-induced DCM. Diabetes (DM) was induced with alloxan monohydrate (150mg/kg-1) dissolved in Nacl (0.9%) overnight-fasted rats. Group III, IV rats were DM induced, followed by treated with SwF (150mg/kg-1) and (300mg/kg-1). Group V and VI were non-diabetic rats and received SwF (150mg/kg-1) and (300mg/kg-1). SwF reduced classical progressive DM complications such as hyperglycemia, polydipsia, polyphagia, and polyurea in alloxan-induced diabetic rats. Biochemical analysis showed that SwF decreased blood glucose, cardiac markers enzymes, and lipid peroxidation levels compared to diabetic rats. SwF administration significantly increased Nrf2, HO-1, SOD, Catalase, and NQO1 gene expression. In addition, SwF-treated rats showed reduced heart tissue damage with increased Nrf2 and HO-1 protein expression. The current research concludes that targeting oxidative stress with SwF provided an effective role inthe prevention of DCM. Thus, fucoidan could be used to develop functional food ingredients for DCM.

Exploring the Complex Connection Between Diabetes and Cardiovascular Disease: Analyzing Approaches to Mitigate Cardiovascular Risk in Patients With Diabetes.

Cardiovascular disease (CVD) is the primary cause of morbidity and mortality in individuals diagnosed with diabetes mellitus. This narrative review offers a comprehensive examination of the complex correlation between diabetes and cardiovascular complications. The objective of this review is to analyze the most recent evidence on preventive measures and treatment options for mitigating cardiovascular risk in patients with diabetes, by synthesizing existing literature. Insulin resistance plays a crucial role in connecting diabetes and CVD, leading to the development of dyslipidemia and atherogenesis. As a result, the risk of cardiovascular events in individuals with diabetes is significantly elevated. Moreover, the presence of hyperglycemia-induced oxidative stress and inflammation serves to intensify endothelial dysfunction and vascular damage, thereby exacerbating the risk of cardiovascular complications. The interaction between diabetes and CVDfrequently speeds up the development of atherosclerotic plaque, making the plaquemore prone to rupture. This can lead to severe cardiovascular events such as myocardial infarction and stroke. It is crucial to comprehend the intricate relationship between diabetes and CVD in order to formulate effective strategies aimed at enhancing patient outcomes and mitigating the burden associated with these interconnected chronic conditions. Healthcare practitioners can enhance the quality of life and reduce mortality rates associated with CVDin diabetic patients by thoroughly examining evidence-based preventive measures and treatment options. This approach allows them to make informed decisions when managing cardiovascular risk. In summary, this narrative review provides a valuable resource for healthcare professionals and researchers, presenting a comprehensive analysis of the complex relationship between diabetes and CVD. By providing a comprehensive analysis of the latest evidence and elucidating the underlying mechanisms, this review seeks to establish a foundation for the development of innovative strategies in diabetes management. These strategies have the potential to significantly improve cardiovascular outcomes and enhance overall patient care.

Omega-3 Polyunsaturated Fatty Acids and Their Anti-Oxidant, Anti-Inflammatory and Neuroprotective Effects in Diabetic Retinopathy: A Narrative Review.

Diabetic retinopathy (DR) is a common microvascular complication of type 2 Diabetes Mellitus (T2DM) that can have vision-threatening consequences, particularly if it advances to the proliferative stage and is left untreated. Owing to the central role of hyperglycemia-induced oxidative stress, multiple anti-oxidants have been investigated for their therapeutic value. However, there is a lack of substantial data to support the use of any of the compounds tested so far. Omega-3 polyunsaturated fatty acids (PUFAs), namely docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), have received much acclaim for their positive impact on cardiovascular health outcomes. The anti-oxidative, anti-inflammatory and neuroprotective properties of PUFAs also make them promising therapeutic and preventive agents for DR. The current evidence is derived mainly from in vitro and animal studies and provides some insight into the underlying mechanisms involved. These fatty acids are capable of direct anti-oxidative and anti-inflammatory effects. They also concomitantly promote intrinsic defense mechanisms and recovery, particularly of photoreceptor neurons. Hence, dietary supplementation with PUFAs, mainly from marine sources, can halt and reverse the retinal damage seen in DR. Furthermore, clinical trials have reported improved vision and quality of life in DR patients after supplementation. However, a major limitation of these trials is the use of nutraceutical formulations in which omega-3 PUFAs are combined with other anti-oxidant compounds, thereby preventing the evaluation of omega-3 as standalone treatment. Although the results of experimental studies to date have been promising, more clinical trials are required to determine the full extent of benefits in patients with DR.

TRIM25 inhibition attenuates inflammation, senescence, and oxidative stress in microvascular endothelial cells induced by hyperglycemia.

This work aimed to assess the possible role of TRIM25 in regulating hyperglycemia-induced inflammation, senescence, and oxidative stress in retinal microvascular endothelial cells, all of which exert critical roles in the pathological process of diabetic retinopathy. The effects of TRIM25 were investigated using streptozotocin-induced diabetic mice, human primary retinal microvascular endothelial cells cultured in high glucose, and adenoviruses for TRIM25 knockdown and overexpression. TRIM25 expression was evaluated by western blot and immunofluorescence staining. Inflammatory cytokines were detected by western blot and quantitative real-time PCR. Cellular senescence level was assessed by detecting senescent marker p21 and senescence-associated-β-galactosidase activity. The oxidative stress state was accessed by detecting reactive oxygen species and mitochondrial superoxide dismutase. TRIM25 expression is elevated in the endothelial cells of the retinal fibrovascular membrane from diabetic patients compared with that of the macular epiretinal membrane from non-diabetic patients. Moreover, we have also observed a significant increase in TRIM25 expression in diabetic mouse retina and retinal microvascular endothelial cells under hyperglycemia. TRIM25 knockdown suppressed hyperglycemia-induced inflammation, senescence, and oxidative stress in human primary retinal microvascular endothelial cells while TRIM25 overexpression further aggregates those injuries. Further investigation revealed that TRIM25 promoted the inflammatory responses mediated by the TNF-α/NF-κB pathway and TRIM25 knockdown improved cellular senescence by increasing SIRT3. However, TRIM25 knockdown alleviated the oxidative stress independent of both SIRT3 and mitochondrial biogenesis. Our study proposed TRIM25 as a potential therapeutic target for the protection of microvascular function during the progression of diabetic retinopathy.

Reduction of high glucose-induced oxidative injury in human retinal pigment epithelial cells by sarsasapogenin through inhibition of ROS generation and inactivation of NF-κB/NLRP3 inflammasome pathway.

Hyperglycemia-induced accumulation of reactive oxygen species (ROS) is a major risk factor for diabetic retinopathy (DR). Sarsasapogenin is a natural steroidal saponin that is known to have excellent antidiabetic effects and improve diabetic complications, but its potential efficacy and mechanism for DR are unknown. The current study was designed to explore whether sarsasapogenin inhibits hyperglycemia-induced oxidative stress in human retinal pigment epithelial (RPE) ARPE-19 cells and to elucidate the molecular mechanisms. To mimic hyperglycemic conditions, ARPE-19 cells were cultured in medium containing high glucose (HG). The suppressive effects of sarsasapogenin on HG-induced cell viability reduction, apoptosis and ROS production were investigated. In addition, the relevance of the nuclear factor-kappa B (NF-κB)/NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome signaling pathway was explored to investigate the mechanism of antioxidant and anti-inflammatory activity of sarsasapogenin. Sarsasapogenin significantly alleviated cytotoxicity and apoptosis in HG-treated ARPE-19 cells through inhibition of intracellular ROS generation. Sarsasapogenin also effectively attenuated HG-induced excess accumulation of mitochondrial superoxide, reduction of glutathione content, and inactivation of manganese superoxide dismutase and glutathione peroxidase. The HG condition markedly increased the expression and maturation of interleukin (IL)-1β and IL-18 through the activation of the NF-kB signaling pathway, whereas sarsasapogenin reversed these effects. Moreover, although the expression of NLRP3 inflammasome multiprotein complex molecules was increased in ARPE-19 cells cultured under HG conditions, their levels remained similar to the control group in the presence of sarsasapogenin. Sarsasapogenin could protect RPE cells from HG-induced injury by inhibiting ROS generation and NF-κB/NLRP3 inflammasome pathway, suggesting its potential as a therapeutic agent to improve the symptoms of DR.

Menthol confers neuroprotection through Nrf2/ARE pathway in diabetic encephalopathy

Background: Chronic, long-standing hyperglycemia in diabetes results in diabetic encephalopathy (DE). It is hallmarked by cognitive dysfunction accelerated by hyperglycemia-induced oxidative stress. Objective: This study explored the neuroprotective potency of menthol in experimental diabetes.Methodology: Streptozotocin at a dose of 40 mg/kg body weight was injected into eighteen male Sprague- Dawley rats intraperitoneally to induce diabetes. The animals were kept without treatment for a period of 30 days for the development of DE. The cognitive deficit was confirmed by the Morris water maze test. Menthol (50 mg/kg body weight) was administered orally for 60 days. The behavioral test was conducted after 60 days of treatment. Results obtained were compared to diabetic rats fed with metformin (100 mg/kg body weight). Animals were then sacrificed to get blood and brain tissue for various biochemical examinations.Results:Treatment with menthol improved cognitive performance in diabetic rats. In addition, menthol significantly decreased fasting blood glucose, HbA1c, renal toxicity markers, and lipid peroxidation products. Menthol enhances the levels of plasma insulin and antioxidant enzymes. It also upregulated the mRNA expression of Bcl-2, Nrf2, Glo-1, and γ-GCS while diminishing the expression of Bax, cytochrome c, and caspase-3. Conclusion:Menthol promotes neuroprotection by abating cognitive deficits, attenuating hyperglycemia, regulating oxidative stress, and curtailing apoptosis through Nrf2/ARE signaling. Keywords: Diabetic encephalopathy, Menthol, apoptosis, Nrf2/ARE pathway

Therapeutic Potential of Dillenia indica L. in Attenuating Hyperglycemia-Induced Oxidative Stress and Apoptosis in Alloxan-Administered Diabetic Mice.

Hyperglycemia-induced oxidative stress accelerates the process of apoptosis in tissues. Dilleniaindica (DI) is a medicinal plant, and its fruit contains many therapeutic properties. The therapeutic activity of the Methanolic Fruit Extract (MFE) of DI in attenuating oxidative stress and apoptosis in the liver and kidney tissues of alloxan-induced diabetic mice was analyzed in the present study. High-Performance Thin Layer Chromatography (HPTLC) profiling of MFE was conducted. GLUT4 protein expression analysis and lipid peroxidation assays were conducted to check for MFE effect by administering in diabetic mice. An ultrastructural study was conducted for both the tissues. In apoptotic studies, the TUNEL assay and apoptotic protein expression analysis was conducted. High-Performance Thin Layer Chromatography (HPTLC) profiling of MFE showed the presence of two crucial antioxidants, ascorbic acid, and naringenin. In GLUT-4 protein expression analysis, MFE suppresses hyperglycemia by upregulating GLUT4 protein expression. Lipid peroxidation assay showed a decrease in malondialdehyde (MDA) upon MFE administration in diabetic mice. An ultrastructural study was conducted, and MFE was found to restore cellular alterations in diabetic tissues. In apoptotic studies, the TUNEL assay shows that MFE treatment showed fewer apoptotic cells than the diabetic group. The study also observed decreased caspase 3 protein expression and increased Bcl-2 protein expression. Therefore, it is inferred from the study that MFE can exert a protective effect by suppressing hyperglycemia and modulating oxidative stress and apoptosis in alloxan-administered diabetic mice.

Co-administration of metformin and vitamin C or E in improves diabetes prognosis in streptozotocin-induced diabetes rats

The prevalence of diabetes mellitus has increased astronomically in recent years. This has resulted in increased disease adjusted life years (DALYs), mortality and decrease in life expectancy. Some of the fall outs of diabetic disease in patients include hyperlipidaemia, oxidative stress, renal and hepatic dysfunction. This study investigated the combined effects of metformin with either vitamin C or E on hyperglycemia-induced hyperlipidemia, oxidative stress, renal and hepatic dysfunction. Diabetes mellitus was induced in the animals fasted overnight with a single dose of streptozotocin (40 mg/kg, intraperitoneal). Animals with fasting blood glucose (FBG) levels >200 mg/dl after 48 hours of streptozotocin administration were marked diabetic and were randomly grouped into 6 groups of 5 diabetic rats each. Treatments were administered orally once daily for two weeks. FBG levels, and other parameters were determined. The results showed that the various treatments significantly and comparably reduced the FBG levels on both day 7 (p<0.05, P<0.01) and day 14 (p<0.001). All the treatments significantly reduced hyperglycemia-induced increase in the levels of triglyceride (TG), total cholesterol (TC), alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine and malondialdehyde (MDA). The antioxidant enzyme activity of superoxide dismutase (SOD), glutathione reductase (GSH), and catalase (CAT) was enhanced by the combined effects of metformin and vitamin C or E. Vitamin E and combination of metformin and vitamin E did not prevent diabetes induced-weight loss throughout the study compared to diabetic control. The findings have demonstrated that metformin and vitamin C co-administration exhibits synergistic effects on blood glucose lowering effect, antioxidant activity and potential advantage of preventing multi-organ damaging effects of type 2 diabetes.

Effectiveness of analog of Humanin in ameliorating streptozotocin-induced diabetic nephropathy in Sprague Dawley rats

Diabetes mellitus (DM) is associated with numerous complications, including nephropathy, which principally occur due to hyperglycemia-induced oxidative stress and inflammation. Humanin (HN), a novel peptide generated from mitochondria, has anti-oxidant and anti-inflammatory potential as observed in different disease models. However, role of HN in diabetic nephropathy (DN) has not yet been explored. This study aimed to evaluate biochemical and molecular aspects of the effects of HN analog, Humanin-glycine ([S14G]-humanin) on streptozotocin (STZ)-induced rat model of DN. Ninety Sprague Dawley (SD) rats were randomly segregated into three groups – A (control), B (disease control) and C (treatment). DM type-I was induced in group B and C via single intra-peritoneal dose of STZ (45 mg/Kg). Seven days following STZ injection, rats were deemed diabetic if their blood glucose level was > 250 mg/dL. Subsequently, diabetic rats in group C were injected with [S14G]-humanin intra-peritoneally (0.4 mg/Kg/day) for sixteen weeks. Biochemical analysis revealed that diabetic rats had markedly elevated levels of serum glucose, creatinine, BUN, TNF-α, and kidney tissue SOD. Whereas, significant decline was detected in serum insulin and albumin levels. All these parameters were significantly reversed in group C after administering [S14G]-humanin. Moreover, qRT-PCR analysis displayed up-regulation of pro-inflammatory (IL-18, IL-6, IL-1α, IL-1β, TNF-α) and down-regulation of anti-inflammatory cytokines (IL-10, IL-1RN, IL-4) in diabetic rats (group B). [S14G]-humanin treatment significantly reversed the expression of IL-18 and IL-1α, however, change in relative expression of IL-6, IL-1β, TNF-α and anti-inflammatory cytokines was insignificant (group C). Conclusively, the findings of this study depicted potential therapeutic role of [S14G]-humanin in pre-clinical rodent model of DN.

Vaccinium as Potential Therapy for Diabetes and Microvascular Complications

Diabetes mellitus is one of the most critical global health concerns, with a fast-growing prevalence. The incidence of diabetic vascular complications is also rapidly increasing, exacerbating the burden on individuals with diabetes and the consumption of public medical resources. Despite the overall improvements in the prevention, diagnosis, and treatment of diabetic microvascular complications in recent years, safe and effective alternative or adjunctive therapies are urgently needed. The mechanisms underlying diabetic vascular complications are complex, with hyperglycemia-induced oxidative stress and inflammation being the leading causes. Therefore, glycemic control, antioxidation, and anti-inflammation are considered the main targets for the treatment of diabetes and its vascular comorbidities. Vaccinium L. (Ericaceae) is a genus of plants enriched with polyphenolic compounds in their leaves and fruits. Vaccinium and its extracts have demonstrated good bioactivity in reducing blood glucose, oxidative stress, and inflammation, making them excellent candidates for the management of diabetes and diabetic vascular complications. Here, we review recent preclinical and clinical studies on the potential effect of Vaccinium on ameliorating diabetes and diabetic complications, particularly diabetic kidney disease and diabetic retinopathy.