Hyperglycemia-induced Oxidative Stress Research Articles

Abstract 15377: Investigating the Role of Breast Cancer Susceptibility Gene 2 in High Glucose-Induced Endothelial Dysfunction

Introduction and Hypothesis: Mutations in the breast cancer susceptibility gene 2 (BRCA2) impair DNA damage repair which can eventually culminate in cancer, inflammation and/or apoptosis. Hyperglycemia-induced oxidative stress triggers DNA damage, inflammation and apoptosis, which are common contributors to endothelial dysfunction in diabetes. Here, we assessed the hypothesis that BRCA2 plays critical role in hyperglycemia-induced endothelial dysfunction. Methods and Results: Human umbilical vein endothelial cells (HUVECs) were exposed to high- (HG; 25 mM) or normal glucose (NG; 5 mM) and BRCA2 expression was measured. Our data showed significant BRCA2 upregulation in HG-treated HUVECs. Next, we successfully silenced BRCA2 in HUVECs, and measured the expression levels of p53 and p21 in HG- and NG-treated BRCA2-silenced HUVECs. We observed a significant upregulation of p53 and p21 in BRCA2-deficient HUVECs, which was further augmented by HG. Next, we measured the migratory and angiogenic potential of control and BRCA2-seilenced HUVECs under NG and HG. Our preliminary data showed that HG and loss of BRCA2 together inhibited the migratory capacity and angiogenic potential of HUVECs. To understand the mechanism behind the effect of HG on BRCA2-deficient ECs, we measured expression levels of endothelial nitric oxide synthase (eNOS). Both expression and activation of eNOS was reduced in HG-treated BRCA2-deficient HUVECs. To understand the effect of loss of BRCA2 on overall endothelial transcriptome and to understand mechanisms, we performed RNA sequencing on scrambled control- and siBRCA2-transfected HUVECs. Interestingly, a total of 3150 genes were differentially expressed in BRCA2-deficient HUVECs compared to the control group. Conclusion: Collectively, these findings reveal a novel role for BRCA2 as a regulator of endothelial function in context of HG treatment in vitro . Our RNA sequencing data shows theimportance of BRCA2 in regulating endothelial transcriptome and overall endothelial function. Further studies are underway; however, these results may provide important implications concerning the susceptibility of BRCA2 mutation carriers to HG-induced endothelial dysfunction as well as other CVDs.

NADPH Oxidase Mediates Oxidative Stress and Ventricular Remodeling through SIRT3/FOXO3a Pathway in Diabetic Mice.

Oxidative stress and mitochondrial dysfunction are important mechanisms of ventricular remodeling, predisposed to the development of diabetic cardiomyopathy (DCM) in type 2 diabetes mellitus. In this study, we have successfully established a model of type 2 diabetes using a high-fat diet (HFD) in combination with streptozotocin (STZ). The mice were divided into three groups of six at random: control, diabetes, and diabetes with apocynin and the H9c2 cell line was used as an in vitro model for investigation. We examined the molecular mechanisms of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation on mitochondrial dysfunction and ventricular remodeling in the diabetic mouse model. Hyperglycemia-induced oxidative stress led to a reduced expression of sirtuin 3 (SIRT3), thereby promoting forkhead box class O 3a (FOXO3a) acetylation in ventricular tissue and H9c2 cells. Reactive oxygen species (ROS) overproduction promoted ventricular structural modeling and conduction defects. These alterations were mitigated by inhibiting NADPH oxidase with the pharmaceutical drug apocynin (APO). Apocynin improved SIRT3 and Mn-SOD expression in H9c2 cells transfected with SIRT3 siRNA. In our diabetic mouse model, apocynin improved myocardial mitochondrial function and ROS overproduction through the recovery of the SIRT3/FOXO3a pathway, thereby reducing ventricular remodeling and the incidence of DCM.

Dairy Milk Casein and Whey Proteins Differentially Alter the Postprandial Lipidome in Persons with Prediabetes: A Comparative Lipidomics Study.

Dairy milk, likely through its bioactive proteins, has been reported to attenuate postprandial hyperglycemia-induced oxidative stress responses implicated in cardiovascular diseases (CVDs). However, how its major proteins, whey and casein, alter metabolic excursions of the lipidome in persons with prediabetes is unclear. Therefore, the objective of this study was to examine whey or casein protein ingestion on glucose-induced alternations in lipidomic responses in adults (17 males and 6 females) with prediabetes. In this clinical study, participants consumed glucose alone, glucose + nonfat milk (NFM), or glucose with either whey (WHEY) or casein (CASEIN) protein, and plasma samples were collected at multiple time points. Lipidomics data from plasma samples was acquired using an ultra-high-performance liquid chromatography-high-resolution mass spectrometry-based platform. Our results indicated that glucose ingestion alone induced the largest number of changes in plasma lipids. WHEY showed an earlier and stronger impact to maintain the stability of the lipidome compared with CASEIN. WHEY protected against glucose-induced changes in glycerophospholipid and sphingolipid (SP) metabolism, while ether lipid metabolism and SP metabolism were the pathways most greatly impacted in CASEIN. Meanwhile, the decreased acyl carnitines and fatty acid (FA) 16:0 levels could attenuate lipid peroxidation after protein intervention to protect insulin secretory capacity. Diabetes-associated lipids, the increased phosphatidylethanolamine (PE) 34:2 and decreased phosphatidylcholine (PC) 34:3 in the NFM-T90min, elevated PC 35:4 and decreased CE 18:1 to a CE 18:2 ratio in the WHEY-T180min, decreased lysophosphatidylcholine (LPC) 22:6 and LPC 22:0/0:0 in the CASEIN-T90min, and decreased PE 36:1 in the CASEIN-T180min, indicating a decreased risk for prediabetes. Collectively, our study suggested that dairy milk proteins are responsible for the protective effect of non-fat milk on glucose-induced changes in the lipidome, which may potentially influence long-term CVD risk.

Antioxidant Effects of DPP-4 Inhibitors in Early Stages of Experimental Diabetic Retinopathy.

Hyperglycemia-induced oxidative stress plays a key role in the impairment of the retinal neurovascular unit, an early event in the pathogenesis of DR. The aim of this study was to assess the antioxidant properties of topical administration (eye drops) of sitagliptin in the diabetic retina. For this purpose, db/db mice received sitagliptin or vehicle eye drops twice per day for two weeks. Age-matched db/+ mice were used as the control group. We evaluated retinal mRNA (RT-PCR) and protein levels (Western blotting and immunohistochemistry) of different components from both the antioxidant system (NRF2, CAT, GPX, GR, CuZnSOD, and MnSOD) and the prooxidant machinery (PKC and TXNIP). We also studied superoxide levels (dihydroethidium staining) and oxidative damage to DNA/RNA (8-hydroxyguanosine immunostaining) and proteins (nitrotyrosine immunostaining). Finally, NF-кB translocation and IL-1β production were assessed through Western blotting and/or immunohistochemistry. We found that sitagliptin protected against diabetes-induced oxidative stress by reducing superoxide, TXNIP, PKC, and DNA/RNA/protein oxidative damage, and it prevented the downregulation of NRF2 and antioxidant enzymes, with the exception of catalase. Sitagliptin also exerted anti-inflammatory effects, avoiding both NF-кB translocation and IL-1β production. Sitagliptin prevents the diabetes-induced imbalance between ROS production and antioxidant defenses that occurs in diabetic retinas.

412-P: Acute Hyperglycemia-Induced Endoplasmic Reticulum and Oxidative Stress Increases Monocyte Cholesterol Content and Cytokine Secretion

Background: Cardiovascular disease (CVD) is an inflammatory disorder enhanced by diabetes. The mechanisms by which recurrent acute hyperglycemia promotes inflammation and CVD are unclear. We showed that acute hyperglycemia mediates increased monocyte cholesterol uptake and cytokine release, but the underlying signaling pathways are unknown. We hypothesized that acute hyperglycemia-induced oxidative and ER stress in circulating monocytes increases cholesterol uptake and a pro-inflammatory phenotype. Methods: Circulating monocytes from 35 healthy subjects were isolated and exposed to euglycemic (5mM) or hyperglycemic (16.7 mM) conditions with or without inhibitors of ER stress (4 phenyl butyric acid) or oxidative stress (N-Acetyl cysteine) for 2 or 6 hrs to assess changes in LDL or oxLDL uptake and cytokine (TNF-α, IL1-β) release. Results: We found that acute hyperglycemia-induced ER and oxidative stress increased total and free cholesterol content via enhanced LDL (18% and 26%, p<0.05) and oxLDL (56% and 30%, p<0.05) uptake as a result of enhanced CD36 and LDL receptor expression. Conversely, inhibiting monocyte oxidative stress or ER stress attenuated monocyte LDL and oxLDL uptake. Finally, blocking monocyte ER stress decreased acute hyperglycemia-induced monocyte TNF-α (87% and 40%, p<0.05) and IL1-β (41% and 44%, p<0.05) secretion after 2 and 6 hrs. Conclusion: Recurrent acute hyperglycemia promotes inflammation by increasing monocyte ER and oxidative stress, which accelerates cholesterol uptake, cholesterol deposition, and cytokine secretion. Future studies are needed to test if acute hyperglycemia-induced monocyte cholesterol deposition is a mechanism to contribute to increased CVD in diabetes. Disclosure R.Zhang: Research Support; American Heart Association. J.Oh: None. G.A.Kutz: None. M.Bambouskova: None. A.S.Dusso: None. C.Bernal-mizrachi: None.

463-P: Effects of Imeglimin, a New Oral Hyperglycemic Agent, on High Glucose and Low Glucose–Induced Cell Death and Mitochondrial Dysfunction in Schwann Cells

It is known that hyperglycemia-induced oxidative stress is a major cause of the pathogenesis of diabetic neuropathy, and hyperglycemia-induced mitochondrial ROS production is considered as one pivotal mechanism of increased oxidative stress. On the other hand, imeglimin is a new class of oral hypoglycemic agents called “glymines” containing tetrahydrotriazines, which targets mitochondrial dysfunction. We investigated the effects of imeglimin on cell death and mitochondrial dysfunction induced by high glucose and low glucose in Schwann cells. Immortalized adult mouse Schwann (IMS32) cells were cultured for 1 hour in the medium with normal glucose concentration of 5.5 mM, low glucose of 2.5 mM, and high glucose of 25 mM. Compared to normal glucose, not only high glucose but also low glucose decreased cell viability of IMS32 cells and increased mitochondrial oxidative stress. Mitochondrial membrane potential was also decreased either by high glucose or low glucose. In addition, mitochondrial oxygen consumption rate (OCR) was increased by low glucose as well as high glucose. Mitochondria isolated from IMS32 cells exposed to high glucose and low glucose for 1 hour exhibited increased activity of complex I. The expression of complex I protein was unchanged by high glucose for 1 hour. Imeglimin ameliorated the decrease in cell viability and improved the mitochondrial dysfunctions via inhibiting the increase of mitochondrial oxidative stress, OCR and the activity of complex I caused by high glucose and low glucose. These results indicate that hyperglycemia and hypoglycemia induce mitochondrial dysfunction in nerves, and that imeglimin may prevent against diabetic neuropathy by attenuation mitochondrial dysfunction and cell death in Schwann cells. Disclosure T. Himeno: None. J. Nakamura: None. H. Kamiya: Research Support; Abbott Japan Co., Ltd., Eli Lilly and Company, Japan Tobacco Inc., Kissei Pharmaceutical Co., Ltd., Kowa Company, Ltd., Merck & Co., Inc., Mitsubishi Tanabe Pharma Corporation, Novo Nordisk, Ono Pharmaceutical Co., Ltd., Sanwa Kagaku Kenkyusho, Sumitomo Dainippon Pharma Co., Ltd., Taiho Pharmaceutical Co. Ltd., Takeda Pharmaceutical Company Limited, Terumo Corporation. Speaker's Bureau; Astellas Pharma Inc., AstraZeneca, Boehringer Ingelheim International GmbH, Daiichi Sankyo, Eli Lilly and Company, Kissei Pharmaceutical Co., Ltd., Kowa Company, Ltd., Merck & Co., Inc., Mitsubishi Tanabe Pharma Corporation, Novartis Pharma K.K., Novo Nordisk, Ono Pharmaceutical Co., Ltd., Sanofi K.K., Sanwa Kagaku Kenkyusho, Sumitomo Dainippon Pharma Co., Ltd., Taisho Pharmaceutical Holdings Co., Ltd. K. Sango: None. K. Kato: None.

“EVALUATION OF HYPERGLYCEMIA INDUCED OXIDATIVE STRESS IN TYPE-2 DIABETIC PATIENT”

Background: Diabetes mellitus (DM) is one of the main chronic health conditions of the 21st century. The diabetes prevalence is rising worldwide due to growth in population, aging, urbanization, and the obesity increase due to physical inactivity. DM is a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion and insulin action or both. Prediabetes or impaired glucose in fasting is halfway between normal glucose levels and diabetes diagnostic levels. Aims and objectives: To evaluate the hyperglycemia-induced oxidative stress status in diabetes mellitus type-2. Methods: The prospective case-control study was conducted at the Index medical college, Malwanchal University, Indore, M.P. on 400 patients of Type 2 DM attending OPD who were 30- 70 years of age. Patients with chronic diseases like Chronic Kidney Disease, COPD, cancer, Metabolic disorders like Hypothyroidism, Infectious diseases like TB, HIV, Hepatitis, Pregnant and breast feeding women, etc, were excluded from the study. Results: 64.0% were male and the rest were female studied patients. 29.3% of cases were having a family history of diabetes and 16.3% of cases were parental and statistically insignicant distribution in both groups (P>0.05). The duration of diabetes was 13.94±5.45 years and 89.7% of cases were uncontrolled diabetes, of which 59.7% cases were on the oral glycaemic drug and the rests were on insulin treatment. The blood sugar level (fasting, post- prandial, and HbA1c) were signicantly higher in the case group in comparison to the control group (P<0.001). Conclusion: In our study, the levels of oxidative stress were higher in T2DM individuals compared to controls. These ndings demonstrate a signicant relationship between acute glucose swings and activation of oxidative stress.

Randomized Clinical Trial of How Long-Term Glutathione Supplementation Offers Protection from Oxidative Damage and Improves HbA1c in Elderly Type 2 Diabetic Patients.

Complications in type 2 diabetes (T2D) arise from hyperglycemia-induced oxidative stress. Here, we examined the effectiveness of supplementation with the endogenous antioxidant glutathione (GSH) during anti-diabetic treatment. A total of 104 non-diabetic and 250 diabetic individuals on anti-diabetic therapy, of either sex and aged between 30 and 78 years, were recruited. A total of 125 diabetic patients were additionally given 500 mg oral GSH supplementation daily for a period of six months. Fasting and PP glucose, insulin, HbA1c, GSH, oxidized glutathione (GSSG), and 8-hydroxy-2-deoxy guanosine (8-OHdG) were measured upon recruitment and after three and six months of supplementation. Statistical significance and effect size were assessed longitudinally across all arms. Blood GSH increased (Cohen’s d = 1.01) and 8-OHdG decreased (Cohen’s d = −1.07) significantly within three months (p < 0.001) in diabetic individuals. A post hoc sub-group analysis showed that HbA1c (Cohen’s d = −0.41; p < 0.05) and fasting insulin levels (Cohen’s d = 0.56; p < 0.05) changed significantly in diabetic individuals above 55 years. GSH supplementation caused a significant increase in blood GSH and helped maintain the baseline HbA1c overall. These results suggest GSH supplementation is of considerable benefit to patients above 55 years, not only supporting decreased glycated hemoglobin (HbA1c) and 8-OHdG but also increasing fasting insulin. The clinical implication of our study is that the oral administration of GSH potentially complements anti-diabetic therapy in achieving better glycemic targets, especially in the elderly population.

Diabetes Mellitus Alters the Immuno-Expression of Neuronal Nitric Oxide Synthase in the Rat Pancreas.

Nitric oxide is generated from nitric oxide synthase following hyperglycemia-induced oxidative stress during the course of diabetes mellitus (DM). We examined the temporal immuno-expression of neuronal nitric oxide synthase (nNOS) in the pancreas of diabetic and non-diabetic rats using immunohistochemical, immunofluorescence and western blot techniques 12 h, 24 h, 1 week, 2 weeks, 1, 8 and 15 months after induction of DM. nNOS co-localized with pancreatic beta cells but disappears 12 h after the onset of DM. In contrast, the nNOS content of pancreatic nerves increased significantly (p < 0.001) 24 h after the induction of DM, and decreased sharply thereafter. However, nNOS-positive ganglion cells were observed even 15 months post-diabetes. ROS increased by more than 100% two months after the onset of DM compared to non-diabetic control but was significantly (p < 0.000001) reduced at 9 months after the induction of DM. The pancreatic content of GSH increased significantly (p < 0.02) after 9 months of DM. Although, TBARS content was significantly (p < 0.009; p < 0.002) lower in aged (9 months) non-diabetic and DM rats, TBARS rate was markedly (p < 0.02) higher 9 months after the induction of DM when compared to younger age group. In conclusion, nNOS is present in pancreatic beta cell, but disappears 12 h after the onset of diabetes. In contrast, the tissue level of nNOS of pancreatic nerves increased in the first week of diabetes, followed by a sharp reduction. nNOS may play important roles in the metabolism of pancreatic beta cell.

Centaurium erythraea methanol extract improves the functionality of diabetic liver and kidney by mitigating hyperglycemia-induced oxidative stress

• Persistent oxidative stress leads to the development of diabetic complications. • Centaurium erythraea extract (CEE) reduced protein glycosylation in diabetic liver and kidney. • CEE reduced lipid peroxidation, DNA damage, and protein glutathionylation in diabetic liver and kidney. • CEE improved liver and kidney function by boosting the endogenous antioxidant system. The use of medicinal herbs can mitigate oxidative stress-induced diabetic complications and organ failure. This study investigated hepato- and reno-protective effects of methanol extract of Centaurium erythraea Rafn (CEE) in STZ-diabetic rats pre-treated (2 weeks) and/or post-treated (4 weeks) with CEE (orally, 100 mg/kg/day). Both CEE treatments markedly improved liver and kidney functionality in diabetic rats observed as reduced aspartate and alanine aminotransferase activities and decreased creatinine and blood urea nitrogen levels. CEE pre-treatment reduced the level of glycosylated proteins in diabetic liver more efficiently than post-treatment. Lowered levels of lipid peroxidation, DNA damage and protein glutathionylation, elevated ratio of reduced to oxidized glutathione, and mitigated disturbance of antioxidant enzyme activities reflected the antioxidant effect of CEE in diabetic liver and kidney. Although CEE pre-treatment was more effective, the obtained results indicate that both treatments protect the liver and kidney from oxidative damage by boosting the endogenous antioxidant defense system.

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

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

Hyperglycemia-induced oxidative stress promotes tumor metastasis by upregulating vWF expression in endothelial cells through the transcription factor GATA1.

Diabetes mellitus (DM) characterized by hyperglycemia is a chronic metabolic disorder that leads to many symptoms and vascular complications. Despite the close association between DM and cancer progression, the response and role of endothelial cells (ECs) under diabetic conditions in tumor metastasis remain to be elucidated. In this study, we sought to determine whether and how ECs under diabetic conditions contribute to tumor metastasis. We have taken advantage of syngeneic mouse tumor models of Lewis lung carcinoma (LLC) and melanoma (B16F10) cells and a streptozotocin (STZ)-induced hyperglycemia model. We demonstrated that hyperglycemia increased the metastasis of LLC and B16F10 cells in an experimental metastasis model with an intravenous injection of the tumor cells. We also found that hyperglycemia promoted lung metastasis of tumor cells by increasing the adhesiveness of ECs to facilitate the adhesion of tumor cells to ECs rather than affecting the metastatic behavior of tumor cells themselves. From the analysis of gene expression in primary lung ECs from STZ-treated mice, we identified that vWF promoted the adhesion of tumor cells to ECs and the transendothelial migration of tumor cells. Mechanistically, hyperglycemia-induced oxidative stress in ECs, and increased oxidative stress enhanced vWF expression in ECs through an increase in the transcription factor GATA1. These results provide evidence for the role of vWF in ECs in promoting hyperglycemia-induced tumor metastasis and potential therapeutic targets for the regulation of vWF expression in ECs and hyperglycemia-induced tumor metastasis.

Antioxidant effect of enamel matrix derivative for early phase of periodontal tissue regeneration in diabetes.

Diabetes involves metabolic disorders in various tissues via hyperglycemia-induced oxidative stress. This study aimed to investigate the antioxidative effect of enamel matrix derivative (EMD) on periodontal regeneration in diabetes. Twenty-two rats were equally divided into streptozotocin (STZ)-induced diabetes or control group. Two months after induction of hyperglycemia, systemic oxidative stress was measured using urinary 8-hydroxy-2'-deoxyguanosine. EMD or saline was applied into the intrabony defects created in the bilateral maxillary molar. mRNA expressions of inflammatory and oxidative stress markers were quantified (n=6). Histometric analyses and immunohistochemistry of superoxide dismutase-1 (SOD-1) were performed 7 days postoperatively (n=5). For in vitro experiments, the bone marrow-derived mesenchymal stem cells were isolated from rat femur and cultured in a high glucose (HG) or control medium. Reactive oxygen species (ROS) measurement and alizarin red staining were performed with/without EMD. Systemic oxidative stress was significantly higher in the diabetic group. The connective tissue attachment and cementum formation were significantly increased at EMD-treated sites in both diabetic and non-diabetic groups. The expression of nicotinamide adenine dinucleotide phosphate oxidase two and four was significantly lower at EMD-treated sites than at EMD-untreated sites in both diabetic and non-diabetic rats. Immunohistochemistry showed significantly higher SOD-1 expression at the EMD-treated site. In vitro, HG culture had significantly higher ROS production compared with control, which was downregulated by EMD. EMD treatment significantly recovered the impaired calcification in HG. EMD promoted early-phase wound healing and periodontal tissue regeneration in the surgically created bony defect of STZ-induced diabetic rat by suppressing hyperglycemia-induced oxidative stress.

Impaired dental implant osseointegration in rat with streptozotocin-induced diabetes.

Few studies have reported on the impact of oxidative stress on the dental implant failure. The aim of this study was to investigate the impact of hyperglycemia-induced oxidative stress on dental implant osseointegration in diabetes mellitus (DM). Acid-treated titanium implants were bilaterally placed in the maxillary alveolar ridge of streptozotocin-induced diabetic (DM group) and control rats after extraction of first molars. Histological analysis and micro-push-out test were performed 4weeks after surgery. Oxidative stress and osteogenic markers in the surrounding bone were quantified by real-time polymerase chain reaction. In the in vitro study, rat bone marrow-derived mesenchymal stem cells (BMMSCs) were cultured on acid-treated titanium discs in a high-glucose (HG) or normal environment. Intracellular reactive oxygen species (ROS), cell proliferation, alkaline phosphatase (ALP) activity, and extracellular calcification were evaluated following antioxidant treatment with N-acetyl-L-cysteine (NAC). The implant survival rate was 92.9% and 75.0% in control and DM group, respectively. Bone-implant contact and push-out loads were significantly lower in the DM group. Expression of superoxide dismutase 1 at the mRNA level and on immunohistochemistry was significantly lower in the DM group. In vitro experiments revealed that the HG condition significantly increased ROS expression and suppressed the proliferation and extracellular calcification of BMMSCs, while NAC treatment significantly restored ROS expression, cell proliferation, and calcification. The ALP activity of both groups was not significantly different. In diabetes, high-glucose-induced oxidative stress downregulates proliferation and calcification of BMMSCs, impairing osseointegration and leading to implant failure.

The possible role of ursolic acid in Covid-19: A real game changer.

Ursolic acid (UA) is a pentacyclic terpenoid is usually found in the fruit peels and stem bark as secondary metabolites. UA has antiviral, antibacterial, and antiparasitic properties. UA has a wide spectrum of pharmacological activities against different infections. Because of the greatest antiviral and anti-inflammatory properties of UA, so it could be a plausible therapeutic herbal medicine in Covid-19 treatment. Covid-19 is a recent worldwide virulent disease pandemic due to severe acute respiratory coronavirus disease 2 (SARS-CoV-2). The pathogenesis of SARS-CoV-2 infection is related to the direct cytopathic effect and exaggerated immune response by which acute lung injury (ALI) and/or acute respiratory distress syndrome might be developed in critical cases. UA may inhibit main protease of SARS-CoV-2, and inhibits the interface flanked by SARS-CoV-2 viral proteins and its entry point commonly recognized as angiotensin converting enzyme 2 (ACE2). In addition, UA attenuates SARS-CoV-2-induced inflammatory reactions and oxidative stress.Therefore, UA could avert SARS-CoV-2 infection from causing ALI. This opinion proposed that UA might be a potential candidate therapy against Covid-19 and can mitigate post-Covid-19 complications such as lung fibrosis. In this regards, forthcoming studies are reasonable to substantiate the therapeutic role of UA in Covid-19. However, taken into account that Covid-19 is yet to be investigating for further evaluations, therefore, clinical trials are recommended regarding use and dose of UA in Covid-19 treatment, as well as secondary effects.

Assessment of In Vitro Tests as Predictors of the Antioxidant Effects of Insulin, Metformin, and Taurine in the Brain of Diabetic Rats.

Hyperglycemia-induced oxidative stress is an intrinsic feature of diabetes mellitus and a recognized causative factor of complications associated with the disease. As a result, compounds possessing antioxidant properties are commonly investigated as possible ways of minimizing and even preventing diabetes-related oxidative stress. On these premises, the present study was carried out to investigate the antioxidant properties of metformin (MET), a common oral hypoglycemic agent, of taurine (TAU), a sulfonic acid compound with known antioxidant benefits in diabetes, and of insulin (INS), a standard antidiabetic serving as a reference compound, by using in vitro and in vivo tests. A battery of seven in vitro tests was used to assess antioxidant/antiradical activity. The addition of a treatment compound led to a meanpercentage decrease of values for free radical/lipid peroxidation (LPO) that ranged from very high (82%) with INS to moderate (43%) with MET) and to low (31%) with TAU. Combining MET with TAU leads to an improvement of the effect seen with MET alone (46%). By contrast, under the same conditions, N-acetylcysteine, a known antioxidant, was more potent (92%) than any of the test compounds. In vivo studies were conducted using rats made diabetic with streptozotocin and treated with daily doses of INS, MET, TAU, and MET-TAU for 6weeks. Among the test compounds, the greatest hypoglycemic effect was attained with INS (>90% decrease), followed by MET (~70% decrease), with TAU providing only a modest effect (-30% decrease). Unexpectedly, however, all three compounds reduced the diabetic values for brain LPO, nitric oxide, antioxidant enzymes, glutathione, and glutathione-related enzymes to values that varied in extent within a narrow range (<12% from one another). On the other hand, pairing MET with TAU led to a small enhancement (<10%) of the effects seen with MET alone. In short, while in vitro tests for antioxidant/antiradical activity suggest marked differences in potency for INS, MET, and TAU as a result of different structures, changes in the values of indices of oxidative stress affected by these compounds in the brain of diabetic rats varied within a rather narrow range. Also, the present results suggest that although hyperglycemia is an important determinant of the oxidative stress of diabetes, other factors may be involved since a weak hypoglycemic like TAU demonstrated in vivo antioxidant actions that were comparable to those of more potent hypoglycemic agents like INS and MET.

Ang-(1-7) exerts anti-inflammatory and antioxidant activities on high glucose-induced injury by prohibiting NF-κB-IL-1β and activating HO-1 pathways in HUVECs

Previous reports have suggested that Ang-(1-7) may have a protective effect in endothelial cells against high glucose (HG)-induced cell injury thanks to a modulatory mechanism in the NF-κB signaling pathway. In this study, we have examined whether NF-κB-IL-1β and Heme oxygenase-1 (HO-1) pathways contribute to the protection of Ang-(1-7) against hyperglycemia-induced inflammation and oxidative stress in human umbilical vein endothelial cells (HUVECs). Our results indicate that time-varying exposures of HUVECs, from 1 h to 24 h, to high glucose concentrations result in an increased expression of phosphorylated (p)-p65 and HO-1 in a time-dependent manner. As an inhibitor of NF-κB, pyrrolidinedithiocarbamic acid (PDTC) suppressed IL-1β production induced by HG. Of note, HUVECs previously treated with Ang-(1-7) (2 μM) for 30 min before being exposed to HG concentrations significantly ameliorated the HG-increased in p-p65 and IL-1β expression; whereas obviously up-regulated the level of HO-1, along with inhibition of oxidative stress, inflammation, and the HG-induced cytotoxicity. Importantly, when HUVECs were previously treated either with PDTC or IL-1Ra for 30 min before being exposed to HG, it significantly prevented damages caused by high glucose concentrations mentioned above, while the treatment of HO-1 inhibitor Sn-protoporphyrin (SnPP) before exposure to both HG and Ang-(1-7) significantly blocked the protective effect exerted by Ang-(1-7) on endothelial cells against injuries induced by HG mentioned above. To conclude, the data of this study showed that activation and inhibition of the NF-κB-IL-1β pathway and HO-1 pathway may constitute an important defense mechanism against endothelial cell damage caused by HG concentrations. We additionally gave new evidence showing that exogenous Ang-(1-7) exerts a protective effect on HUVECs against the HG-induced cell injury via the inhibition and the activation of the NF-κB-IL-1β pathway and the HO-1 pathway, respectively.

Betulinic acid accelerates diabetic wound healing by modulating hyperglycemia-induced oxidative stress, inflammation and glucose intolerance.

BackgroundDiabetes significantly delays wound healing through oxidative stress, inflammation and impaired re-epithelialization that lead to defective regulation of the healing process, although the related mechanism remains unclear. Here, we aim to investigate the potential role and mechanism for the beneficial effect of betulinic acid (BA) on diabetic wound healing.MethodsThe molecular effect of BA on hyperglycemia-mediated gene expression, oxidative stress, inflammation and glucose uptake was evaluated in endothelial, fibroblast and muscle cells. Burn injury was introduced to streptozotocin-induced diabetic rats and BA administration through either an intraperitoneal (IP) or topical (TOP) technique was used for wound treatment. Glucose tolerance was evaluated in both muscle tissue and fibroblasts, while oxidative stress and inflammation were determined in both the circulatory system and in wound tissues. The effect of BA on the wound healing process was also evaluated.ResultsBA treatment reversed hyperglycemia-induced glucose transporter type 4 (GLUT4) suppression in both muscle and fibroblast cells. This treatment also partly reversed hyperglycemia-mediated suppression of endothelial nitric oxide synthase (eNOS), nuclear factor erythroid 2-related factor 2 (Nrf2) signaling and nuclear factor NFκB p65 subunit (NFκB p65) activation in endothelial cells. An in vivo rat study showed that BA administration ameliorated diabetes-mediated glucose intolerance and partly attenuated diabetes-mediated oxidative stress and inflammation in both the circulatory system and wound tissues. BA administration by both IP and TOP techniques significantly accelerated diabetic wound healing, while BA administration by either IP or TOP methods alone had a significantly lower effect.ConclusionsBA treatment ameliorates hyperglycemia-mediated glucose intolerance, endothelial dysfunction, oxidative stress and inflammation. Administration of BA by both IP and TOP techniques was found to significantly accelerate diabetic wound healing, indicating that BA could be a potential therapeutic candidate for diabetic wound healing.

Stevioside Attenuates Insulin Resistance in Skeletal Muscle by Facilitating IR/IRS-1/Akt/GLUT 4 Signaling Pathways: An In Vivo and In Silico Approach.

Type-2 diabetes mellitus (T2DM), the leading global health burden of this century majorly develops due to obesity and hyperglycemia-induced oxidative stress in skeletal muscles. Hence, developing novel drugs that ameliorate these pathological events is an immediate priority. The study was designed to analyze the possible role of Stevioside, a characteristic sugar from leaves of Stevia rebaudiana (Bertoni) on insulin signaling molecules in gastrocnemius muscle of obesity and hyperglycemia-induced T2DM rats. Adult male Wistar rats rendered diabetic by administration of high fat diet (HFD) and sucrose for 60 days were orally administered with SIT (20 mg/kg/day) for 45 days. Various parameters were estimated including fasting blood glucose (FBG), serum lipid profile, oxidative stress markers, antioxidant enzymes and expression of insulin signaling molecules in diabetic gastrocnemius muscle. Stevioside treatment improved glucose and insulin tolerances in diabetic rats and restored their elevated levels of FBG, serum insulin and lipid profile to normalcy. In diabetic gastrocnemius muscles, Setvioside normalized the altered levels of lipid peroxidase (LPO), hydrogen peroxide (H2O2) and hydroxyl radical (OH*), antioxidant enzymes (CAT, SOD, GPx and GSH) and molecules of insulin signaling including insulin receptor (IR), insulin receptor substrate-1 (IRS-1) and Akt mRNA levels. Furthermore, Stevioside enhanced glucose uptake (GU) and oxidation in diabetic muscles by augmenting glucose transporter 4 (GLUT 4) synthesis very effectively in a similar way to metformin. Results of molecular docking analysis evidenced the higher binding affinity with IRS-1 and GLUT 4. Stevioside effectively inhibits oxidative stress and promotes glucose uptake in diabetic gastrocnemius muscles by activating IR/IRS-1/Akt/GLUT 4 pathway. The results of the in silico investigation matched those of the in vivo study. Hence, Stevioside could be considered as a promising phytomedicine to treat T2DM.

Burdock Fructooligosaccharide Attenuates High Glucose-Induced Apoptosis and Oxidative Stress Injury in Renal Tubular Epithelial Cells.

Hyperglycemia-induced apoptosis and oxidative stress injury are thought to play important roles in the pathogenesis of diabetic nephropathy (DN). Attenuating high glucose (HG)-induced renal tubular epithelial cell injury has become a potential approach to ameliorate DN. In recent years, burdock fructooligosaccharide (BFO), a water-soluble inulin-type fructooligosaccharide extracted from burdock root, has been shown to have a wide range of pharmacological activities, including antiviral, anti-inflammatory, and hypolipidemic activities. However, the role and mechanism of BFO in rat renal tubular epithelial cells (NRK-52E cells) have rarely been investigated. The present study investigated the protective effect of BFO on HG-induced damage in NRK-52E cells. BFO could protect NRK-52E cells against the reduced cell viability and significantly increased apoptosis rate induced by HG. These anti-oxidative stress effects of BFO were related to the significant inhibition of the production of reactive oxygen species, stabilization of mitochondrial membrane potential, and increased antioxidant (superoxide dismutase and catalase) activities. Furthermore, BFO increased the expression of Nrf2, HO-1, and Bcl-2 and decreased the expression of Bax. In conclusion, these findings suggest that BFO protects NRK-52E cells against HG-induced damage by inhibiting apoptosis and oxidative stress through the Nrf2/HO-1 signaling pathway.