Pathophysiology Of Diabetic Complications Research Articles

Fasting pancreatic polypeptide predicts incident microvascular and macrovascular complications of type 2 diabetes: An observational study.

Pancreatic polypeptide (PP) is elevated in people with vascular risk factors such as type 2 diabetes or increased visceral fat. We investigated potential relationships between PP and microvascular and macrovascular complications of diabetes. Animal study: Subcutaneous PP infusion for 4weeks in high fat diet mouse model. Retinal mRNA submitted for Ingenuity Pathway Analysis. Human study: fasting PP measured in 1478 participants and vascular complications recorded over median 5.5 (IQR 4.9-5.8) years follow-up. Animal study: The retinal transcriptional response to PP was indicative of cellular stress and damage, and this footprint matched responses described in previously published studies of retinal disease. Of mechanistic importance the transcriptional landscape was consistent with upregulation of folliculin, a recently identified susceptibility gene for diabetic retinopathy. Human study: Adjusting for established risk factors, PP was associated with prevalent and incident clinically significant retinopathy (odds ratio (OR) 1.289 (1.107-1.501) p=0.001; hazard ratio (HR) 1.259 (1.035-1.531) p=0.0213), albuminuria (OR 1.277 (1.124-1.454), p=0.0002; HR 1.608 (1.208-2.141) p=0.0011), and macrovascular disease (OR 1.021 (1.006-1.037) p=0.0068; HR 1.324 (1.089-1.61), p=0.0049), in individuals with type 2 diabetes, and progression to diabetes in non-diabetic individuals (HR 1.402 (1.081-1.818), p=0.0109). Elevated fasting PP is independently associated with vascular complications of diabetes and affects retinal pathways potentially influencing retinal neuronal survival. Our results suggest possible new roles for PP-fold peptides in the pathophysiology of diabetes complications and vascular risk stratification.

Does Sugar Control Arrest Complications in Type 2 Diabetes? Examining the Rigour in Statistical Methods and Causal Inference in Clinical Trials.

BACKGROUND: In contrast to type 1 diabetes mellitus (T1DM), in type 2 (T2DM) the success of intensive glucose normalisation in arresting diabetic complications is marginal and inconsistent across multiple clinical trials. However, glucose regulation still largely remains the main target of treatment for T2DM in clinical practice. OBJECTIVES: We examine the possible causes of inconsistency across studies, the scientific rigour behind the design, conduct and inferences of 6 large institutional clinical trials targeting glucose normalisation and following up for diabetic complications and mortality. STUDY DESIGN: We enumerate the possible flaws in the design, statistical treatment of the results and possible logical traps in making inferences. Further, we evaluate whether the flaws can mislead the conclusions. We also suggest a more sound statistical treatment of the data and interpret results of the trials together in a coherent way. RESULTS: The clinical trials for intensive glucose control suffer from a number of common problems that have not been addressed. The most important being the failure to correct for multiple outcomes. This is recognised by some reviewers but no correction is attempted. The second is the interdependence of the outcomes, owing to which statistics based on the assumption of independence can be misleading. Simulations show that the apparent inconsistency or heterogeneity between trial results can be explained by the violation of assumed independence alone. Further, the problems with placebo control, failure to recognise alternative possibilities, inability to segregate clinical significance from statistical significance and misleading reporting formats point to conformity bias and publication bias. CONCLUSIONS: We find no support for the prevalent belief that glucose normalisation has any benefit in terms of reducing the frequency of any of the complications or mortality. It is time to reconsider the glucocentric line of treatment of T2DM. Rethinking some of the fundamental beliefs about the pathophysiology of diabetic complications and facilitating novel alternative lines of research is the need of the field.

Generation of autoantibodies against glycated fibrinogen: Role in diabetic nephropathy and retinopathy

The process of glycation, characterized by the non-enzymatic reaction between sugars and free amino groups on biomolecules, is a key contributor to the development and progression of both microvascular and macrovascular complications associated with diabetes, particularly due to persistent hyperglycemia. This glycation process gives rise to advanced glycation end products (AGEs), which play a central role in the pathophysiology of diabetes complications, including nephropathy. The d-ribose-mediated glycation of fibrinogen plays a central role in the pathogenesis of diabetes nephropathy (DN) and retinopathy (DR) by the generation and accumulation of advanced glycation end products (AGEs). Glycated fibrinogen with d-ribose (Rb-gly-Fb) induces structural changes that trigger an autoimmune response by generating and exposing neoepitopes on fibrinogen molecules. The present research is designed to investigate the prevalence of autoantibodies against Rb-gly-Fb in individuals with type 2 diabetes mellitus (T2DM), DN & DR. Direct binding ELISA was used to test the binding affinity of autoantibodies from patients' sera against Rb-gly-Fb and competitive ELISA was used to confirm the direct binding findings by checking the bindings of isolated IgG against Rb-gly-Fb and its native conformer. In comparison to healthy subjects, 32% of T2DM, 67% of DN and 57.85% of DR patients' samples demonstrated a strong binding affinity towards Rb-gly-Fb. Both native and Rb-gly-Fb binding by healthy subjects (HS) sera were non-significant (p > 0.05). Furthermore, the early, intermediate, and end products of glycation have been assessed through biochemical and physicochemical analysis. The biochemical markers in the patient groups were also significant (p < 0.05) in comparison to the HS group. This study not only establishes the prevalence of autoantibodies against d-ribose glycated fibrinogen in DN but also highlights the potential of glycated fibrinogen as a biomarker for the detection of DN and/or DR. These insights may open new avenues for research into novel therapeutic strategies and the prevention of diabetes-related nephropathy and retinopathy.

Does Sugar Control Arrest Complications in Type 2 Diabetes? Examining the Rigour in Statistical Methods and Causal Inference in Clinical Trials

BACKGROUND: In contrast to type 1 diabetes mellitus (T1DM), in type 2 (T2DM) the success of intensive glucose normalisation in arresting diabetic complications is marginal and inconsistent across multiple clinical trials. However, glucose regulation still largely remains the main target of treatment for T2DM in clinical practice. OBJECTIVES: We examine the possible causes of inconsistency across studies, the scientific rigour behind the design, conduct and inferences of 6 large institutional clinical trials targeting glucose normalisation and following up for diabetic complications and mortality. STUDY DESIGN: We enumerate the possible flaws in the design, statistical treatment of the results and possible logical traps in making inferences. Further, we evaluate whether the flaws can mislead the conclusions. We also suggest a more sound statistical treatment of the data and interpret results of the trials together in a coherent way. RESULTS: The clinical trials for intensive glucose control suffer from a number of common problems that have not been addressed. The most important being the failure to correct for multiple outcomes. This is recognised by some reviewers but no correction is attempted. The second is the interdependence of the outcomes, owing to which statistics based on the assumption of independence can be misleading. Simulations show that the apparent inconsistency or heterogeneity between trial results can be explained by the violation of assumed independence alone. Further, the problems with placebo control, failure to recognise alternative possibilities, inability to segregate clinical significance from statistical significance and misleading reporting formats point to conformity bias and publication bias. CONCLUSIONS: We find no support for the prevalent belief that glucose normalisation has any benefit in terms of reducing the frequency of any of the complications or mortality. It is time to reconsider the glucocentric line of treatment of T2DM. Rethinking some of the fundamental beliefs about the pathophysiology of diabetic complications and facilitating novel alternative lines of research is the need of the field.

THU336 Correlation Between Dietary Advanced Glycation End-products (Ages) And Skin Ages In Adults With Longstanding T1D

Abstract Disclosure: A.B. Murthy: None. B.E. Gray: None. M. Cote: None. B. Zahedi: None. E.W. Yu: Grant Recipient; Self; Amgen Inc. Background: Advanced glycation end products (AGEs) are involved in the pathophysiology of diabetic complications, and are thought to accrue with aging, hyperglycemia, and through diet. Despite the postulated impact of dietary intake on circulating AGE levels, there is currently no validated methodology for dietary AGE (dAGE) assessment. Thus, we sought to develop a crosswalk algorithm to calculate AGE intake from the commonly utilized Block Food Frequency Questionnaire (FFQ), and to validate our algorithm by correlating dAGE to skin AGE values within a cohort of adults with Type 1 Diabetes (T1D). Methods: We performed preliminary analysis of 50 study participants from the ongoing Type 1 Diabetes Bone Health Connection (T1D BEACON) study evaluating postmenopausal women and men older than 50 years with T1D. Dietary AGE intake was quantified using a novel algorithm we developed to associate items from the 2014 Block FFQ with their AGE content as determined by ELISA in a published data set (Urribarri, et al. 2014). Mean daily dAGE intake (kU/day) was correlated with autoflourescent skin AGE values (AGE Reader, DiagnOptics Technologies) using multivariate linear regression, after adjusting for age and gender. Diabetic characteristics and complications were assessed through questionnaires, physical exams (mTCNS, DPNCheck), chart review, and urine/serum tests. Results: The average age of the T1D cohort was 62.7 ± 6.8 years, 50% were female, the average duration of diabetes was 45 ± 9.4 years, with average A1c of 7.2 ± 1.1. Regarding diabetic complications, 70% had retinopathy, 30% had microalbuminuria (urine albumin-creatinine ratio &amp;gt; 30 mcg/mg), and 33% had neuropathy (mTCNS score &amp;gt; 5). Using our novel algorithm, the mean daily dAGE intake was calculated as 13178 ± 4455 kU/day. Mean daily dAGE intake was significantly higher for men (15279 ± 6337 kU/day) compared to women (11628 ± 3699 kU/day) (p = 0.016). Importantly, dAGEs were significantly correlated with skin AGEs (r = 0.409, p = 0.004), an association that persisted after adjusting for age and gender (p = 0.005). Additionally, dAGEs were correlated with current A1c values (r=0.37, p = 0.009, adj. p = 0.042) and with BMI (r = 0.32, p = 0.024, adj. p = 0.020), even after adjusting for age and gender. No associations were found between dAGEs and retinopathy, microalbuminuria, or neuropathy. Additional analysis of the full planned cohort is ongoing, along with assessments of serum AGE levels. Conclusion: We have developed and validated a novel dietary AGE algorithm that quantifies dAGE intake using the Block FFQ and is correlated with skin AGEs and glycemic control among adults with T1D. If further validated in larger cohorts, we hope this dAGE tool will facilitate future investigation of the impact of dietary AGEs on diabetic complications. Presentation: Thursday, June 15, 2023

OR34-02 Fasting Pancreatic Polypeptide Predicts Incident Microvascular And Macrovascular Complications Of Type 2 Diabetes

Abstract Disclosure: A.H. Sam: None. A.J. Buckley: None. B.Y. Lam: None. P.R. Bech: None. K. Meeran: None. M.T. Barakat: None. S.R. Bloom: None. G.S. Yeo: None. N.G. Lessan: None. K.G. Murphy: None. Background: Pancreatic polypeptide (PP) is elevated in people with Type 2 Diabetes (T2D) or with increased visceral adiposity, risk factors for arterial disease. PP acts at neuropeptide Y (NPY) receptors with effects demonstrated on body composition, arterial tone, and retinal vasculature. Hypothesis: We hypothesised that addition of PP to established factors would enhance estimates of vascular risk in people with T2D. We further hypothesised that PP might have direct effects in glucose sensitive tissues. Methods: Animal study: Continuous subcutaneous PP infusion for four weeks in a high fat diet mouse model; retinal mRNA obtained using Laser Capture Microdissection and submitted for Ingenuity Pathway analysis. Human study: Fasting PP measured at enrolment in 1478 participants (224 normal glucose tolerance, 224 prediabetes, 1030 T2D) recruited at Imperial College London Diabetes Centre Abu Dhabi; microvascular and microvascular complications of diabetes recorded over median 5.5 (IQR 4.9-5.8) years follow-up. Results: Animal study: PP infusion was associated with changes in retinal gene expression potentially influencing neuronal survival including BMP receptors, TWEAK and TNFR1, and inhibition of upstream regulators including DAP3 and ALKBH1, even with unaltered weight, BP and blood glucose compared with pair-fed controls. Human study: In univariate analysis and adjusting for established factors including age, diabetes duration, BMI, sBP, smoking and HbA1c, log2(PP) was significantly associated with incident retinopathy (64 events; univariate: hazard ratio (HR) 1.39 (1.14-1.68) p &amp;lt; 0.001), adjusted: HR 1.26 (1.04-1.53) p=0.021), incident albuminuria (34 events; univariate: HR 1.48 (1.14-1.93) p=0.003, adjusted: HR 1.61 (1.21-2.14) p=0.001, and incident macrovascular disease (74 events; univariate: HR 1.46 (1.22-1.74) p&amp;lt;0.0001, adjusted: HR 1.32 (1.09-1.61), p=0.005), in individuals with T2D. Addition of PP to fully adjusted models resulted in modest improvements in the c-statistic (retinopathy: 0.74 without PP, 0.77 with PP; albuminuria: 0.65 without PP, 0.70 with PP; macrovascular: 0.72 without PP, 0.74 with PP). Adjusting for glycaemic status, BMI, sex, age and family history, PP was associated with increased hazard of progression to T2D in participants not diabetic at enrolment (HR 1.40 (1.08-1.82), p=0.011). Conclusions: Elevated fasting PP predicts incident vascular complications of diabetes, independent of known risk factors. Tonic elevation of PP in the mouse affects retinal gene expression, influencing pathways which may influence neuronal survival. Our results suggest roles for the PP-fold family of peptides in the pathophysiology of diabetic complications and vascular risk stratification. Presentation: Sunday, June 18, 2023

Microglial NLRP3 inflammasome activation mediates diabetes-induced depression-like behavior via triggering neuroinflammation

BackgroundAbundant evidence suggests that the prevalence and risk of depression in people with diabetes is high. However, the pathogenesis of diabetes-related depression remains unclear. Since neuroinflammation is associated with the pathophysiology of diabetic complications and depression, this study aims to elucidate the neuroimmune mechanism of diabetes-related depression. MethodsMale C57BL/6 mice were injected with streptozotocin to establish a diabetes model. After screening, diabetic mice were treated with the NLRP3 inhibitor MCC950. Then, metabolic indicators and depression-like behaviors were evaluated in these mice, as well as their central and peripheral inflammation. To explore the mechanism of high glucose-induced microglial NLRP3 inflammasome activation, we performed in vitro studies focusing on its canonical upstream signal I (TLR4/MyD88/NF-κB) and signal II (ROS/PKR/P2X7R/TXNIP). ResultsDiabetic mice exhibited depression-like behaviors and activation of NLRP3 inflammasome in hippocampus. In vitro high-glucose (50 mM) environment primed microglial NLRP3 inflammasome by promoting NF-κB phosphorylation in a TLR4/MyD88-independent manner. Subsequently, high glucose activated the NLRP3 inflammasome via enhancing intracellular ROS accumulation, upregulating P2X7R, as well as promoting PKR phosphorylation and TXNIP expression, thereby facilitating the production and secretion of IL-1β. Inhibition of NLRP3 with MCC950 significantly restored hyperglycemia-induced depression-like behavior and reversed the increase in IL-1β levels in the hippocampus and serum. ConclusionThe activation of NLRP3 inflammasome, probably mainly in hippocampal microglia, mediates the development of depression-like behaviors in STZ-induced diabetic mice. Targeting the microglial inflammasome is a feasible strategy for the treatment of diabetes-related depression.

Effects of eicosapentaenoic acid supplementation on heat shock protein 27, glycemic status and anthropometric indices in type 2 diabetes patients.

Heat shock proteins (HSP-27) are reported to be involved in the pathophysiology of diabetes complications. The purpose of the current study is to assess the effects of eicosapentaenoic acid (EPA) supplementation on serum HSP-27, glycemic status and anthropometric indices in type 2 diabetes mellitus (T2DM) patients. Thirty-six patients with T2DM were randomly allocated to obtain 2g per day EPA (n = 18) or placebo (n = 18) for 8 weeks in a randomized, double-blind, placebo-controlled clinical trial. Fasting serum levels of HSP 27, fasting blood sugar, hemoglobin A1C, as well as anthropometric indices were measured. EPA supplementation reduces the serum level of HSP 27 in the EPA group compared with the placebo (P < 0.03). Although waist circumference (WC) decreased significantly in the EPA group at the end of the trial (P < 0.02), there was no significant difference in weight, WC, body mass index (BMI), and glycemic markers in both groups after intervention (P > 0.05). We found that EPA supplementation reduces HSP 27 serum level in T2DM patients. However, future large-scale trials are needed.

Rho-kinase inhibition ameliorates non-alcoholic fatty liver disease in type 2 diabetic rats.

Non-alcoholic fatty liver disease (NAFLD) is linked to type 2 diabetes mellitus (T2DM), obesity, and insulin resistance. The Rho/ROCK pathway had been involved in the pathophysiology of diabetic complications. This study was designed to assess the possible protective impacts of the Rho/Rho-associated coiled-coil containing protein kinase (Rho/ROCK) inhibitor fasudil against NAFLD in T2DM rats trying to elucidate the underlying mechanisms. Animals were assigned into control rats, non-treated diabetic rats with NAFLD, and diabetic rats with NAFLD that received fasudil treatment (10 mg/kg per day) for 6 weeks. The anthropometric measures and biochemical analyses were performed to assess metabolic and liver function changes. The inflammatory and oxidative stress markers and the histopathology of rat liver tissues were also investigated. Groups with T2DM showed increased body weight, serum glucose, and insulin resistance. They exhibited disturbed lipid profile, enhancement of inflammatory cytokines, and deterioration of liver function. Fasudil administration reduced body weight, insulin resistance, and raised liver enzymes. It improved the disturbed lipid profile and attenuated liver inflammation. Moreover, it slowed down the progression of high fat diet (HFD)-induced liver injury and reduced the caspase-3 expression. The present study demonstrated beneficial amelioration effect of fasudil on NAFLD in T2DM. The mechanisms underlying these impacts are improving dyslipidemia, attenuating oxidative stress, downregulated inflammation, improving mitochondrial architecture, and inhibiting apoptosis.

Advanced Glycation End Products and Diabetes Mellitus: Mechanisms and Perspectives.

Persistent hyperglycemic state in type 2 diabetes mellitus leads to the initiation and progression of non-enzymatic glycation reaction with proteins and lipids and nucleic acids. Glycation reaction leads to the generation of a heterogeneous group of chemical moieties known as advanced glycated end products (AGEs), which play a central role in the pathophysiology of diabetic complications. The engagement of AGEs with its chief cellular receptor, RAGE, activates a myriad of signaling pathways such as MAPK/ERK, TGF-β, JNK, and NF-κB, leading to enhanced oxidative stress and inflammation. The downstream consequences of the AGEs/RAGE axis involve compromised insulin signaling, perturbation of metabolic homeostasis, RAGE-induced pancreatic beta cell toxicity, and epigenetic modifications. The AGEs/RAGE signaling instigated modulation of gene transcription is profoundly associated with the progression of type 2 diabetes mellitus and pathogenesis of diabetic complications. In this review, we will summarize the exogenous and endogenous sources of AGEs, their role in metabolic dysfunction, and current understandings of AGEs/RAGE signaling cascade. The focus of this review is to recapitulate the role of the AGEs/RAGE axis in the pathogenesis of type 2 diabetes mellitus and its associated complications. Furthermore, we present an overview of future perspectives to offer new therapeutic interventions to intervene with the AGEs/RAGE signaling pathway and to slow down the progression of diabetes-related complications.

Diabetes in Humans Activates Pancreatic Stellate Cells via RAGE in Pancreatic Ductal Adenocarcinoma.

Pancreatic stellate cells (PSCs) mainly consist of cancer-associating fibroblasts in pancreatic ductal adenocarcinoma (PDAC). The receptor for advanced glycation end products (RAGE) is implicated in the pathophysiology of diabetic complications. Here, we studied the implication of RAGE in PSC activation in PDAC. The activation of cultured mouse PSCs was evaluated by qPCR. The induction of epithelial mesenchymal transition (EMT) in PDAC cell lines was assessed under stimulation with culture supernatant from activated PSCs. A total of 155 surgically resected PDAC subjects (83 nondiabetic, 18 with ≦3-years and 54 with >3-years history of diabetes) were clinicopathologically evaluated. A high-fat diet increased the expression of activated markers in cultured PSCs, which was abrogated by RAGE deletion. Culture supernatant from activated PSCs facilitated EMT of PDAC cells with elevation of TGF−β and IL−6, but not from RAGE−deleted PSCs. Diabetic subjects complicated with metabolic syndrome, divided by cluster analysis, showed higher PSC activation and RAGE expression. In such groups, PDAC cells exhibited an EMT nature. The complication of metabolic syndrome with diabetes significantly worsened disease−free survival of PDAC subjects. Thus, RAGE in PSCs can be viewed as a new promoter and a future therapeutic target of PDAC in diabetic subjects with metabolic syndrome.

Development of Novel Indole-Based Bifunctional Aldose Reductase Inhibitors/Antioxidants as Promising Drugs for the Treatment of Diabetic Complications.

Aldose reductase (AR, ALR2), the first enzyme of the polyol pathway, is implicated in the pathophysiology of diabetic complications. Aldose reductase inhibitors (ARIs) thus present a promising therapeutic approach to treat a wide array of diabetic complications. Moreover, a therapeutic potential of ARIs in the treatment of chronic inflammation-related pathologies and several genetic metabolic disorders has been recently indicated. Substituted indoles are an interesting group of compounds with a plethora of biological activities. This article reviews a series of indole-based bifunctional aldose reductase inhibitors/antioxidants (ARIs/AOs) developed during recent years. Experimental results obtained in in vitro, ex vivo, and in vivo models of diabetic complications are presented. Structure–activity relationships with respect to carboxymethyl pharmacophore regioisomerization and core scaffold modification are discussed along with the criteria of ‘drug-likeness”. Novel promising structures of putative multifunctional ARIs/AOs are designed.

1403-P: Glycemic Control Levels Are Not Major Determinants of Accumulation of AGE

Objective: Chronic hyperglycemia increases glycation as well as oxidization, and, thus, facilitates production of advanced glycation end products (AGEs), whose accumulation is involved in the pathophysiology of diabetic complications. Although association between AGE and insulin resistance has been reported thoroughly, association between AGE and insulin secretion has not been well examined, especially in relation with age. Research Design: Among participants of the population-based Iwaki study of Japanese held in 2014, those who attended the Iwaki study consecutively in 2014 and 2015 were enrolled in this study (n=518; model A), and we excluded fasting blood glucose levels &amp;lt;63 and &amp;gt;140 to calculate HOMA-β and IR (n=489; model B). We used skin autofluorescence as AGE, and also measured blood levels of Pentosidine and urine albumin-to-creatinine ratio. Results: 1. AGE levels significantly increased from 1.93±0.52 to 1.97±0.44 (p=0.014) in the 1 year period. 2. Regression analysis showed correlations between ∆AGE (change in AGE in the 1 year period) and age, BUN, FPG and log10uACR in model A, and, age, log10uACR, and log10HOMA-ß in model B. However, these correlations became none-significant after adjustment for multiple factors mentioned above as well as factors representing glucose control levels such as HbA1c, except for age in models A and B, respectively. 3. Subjects were stratified into tertiles (mildly, moderately, rapidly progress) based on their ∆AGE, Logistic analysis revealed the aging is a significant risk for the accumulation of AGE (rapidly progress) (OR: 1.02. 95%CI: 1.01-1.03). ROC analysis showed the age of 60 as an optimal cut-off value for determining the risk subjects for the increase in AGE (OR: 1.74, 95%CI: 1.20-2.51). Conclusions: The accumulation of AGEs may increase with increasing speed, which becomes rapid over the age of 60 independent of glycemic levels, uACR and HOMA-ß, indicating that not glycemic control levels but aging per se is a major contributor for AGE accumulation. Disclosure S. Mizushiri: None. M. Daimon: None. H. Murakami: None. A. Kamba: None. M. Murabayashi: None. Y. Nishiya: None.

Antiglycation Activity of Triazole Schiff's Bases Against Fructosemediated Glycation: In Vitro and In Silico Study.

Advanced glycation end products (AGEs) are known to be involved in the pathophysiology of diabetic complications, neurodegenerative diseases, and aging. Preventing the formation of AGEs can be helpful in the management of these diseases. Two classes of previously synthesized traizole Schiff's bases (4H-1,2,4-triazole-4- Schiff's bases 1-14, and 4H-1,2,4-triazole-3-Schiff's bases 15-23) were evaluated for their in vitro antiglycation activity. In vitro fructose-mediated human serum albumin (HSA) glycation assay was employed to assess the antiglycation activity of triazole Schiff's bases. The active compounds were subjected to cytotoxicity analysis by MTT assay on mouse fibroblast (3T3) cell line. Molecular docking and simulation studies were carried out to evaluate the interactions and stability of compounds with HSA. Anti-hyperglycemic and antioxidant activities of selected non-cytotoxic compounds were evaluated by in vitro α-glucosidase inhibition, and DPPH free radical scavenging assays, respectively. Compound 1 (IC50=47.30±0.38 µM) from 4H-1,2,4-triazole-4-Schiff's bases has exhibited antiglycation activity comparable to standard rutin (IC50=54.5±0.05 µM) along with a stable RMSD profile in MD simulation studies. Compound 1 also exhibited a potent α-glucosidase inhibitory activity, and moderate antioxidant property. Other derivatives showed a weak antiglycation activity with IC50 values between 248.1-637.7 µM. Compounds with potential antiglycation profile were found to be non-cytotoxic in a cellular assay. The study identifies triazole Schiff's bases active against fructose-mediated glycation of HSA, thus indicates their potential against late diabetic complications due to production of advancedend products (AGEs).

3,4-Dihydroxyphenethyl nitrate with nitric oxide releasing, antioxidant, hypoglycemic and hypolipidemic effects

Nitric oxide (NO) dysfunction, oxidative stress, and dyslipidemia are main risk factors associated with the pathophysiology of diabetic complications. In this study, 3,4-dihydroxyphenethyl nitrate (HT-ONO2) was designed, synthesized and evaluated, which incorporated hydroxytyrosol (HT) and nitrate. HT-ONO2 significantly exhibited hypoglycemic activity after oral administration to diabetic mice induced by streptozocin (STZ). HT-ONO2 also potently decreased plasma triglyceride (TG), total cholesterol (TC) in hyperlipidemia mice induced by Triton WR 1339. Meanwhile, HT-ONO2 displayed NO-releasing and antioxidant activity both in diabetic and hyperlipidemia mice and in vitro. Moreover, HT-ONO2 shown definite vasodilation and α-glucosidase inhibition activity in vitro. The results suggested that the hybrid hydroxytyrosol-based nitrate with NO supplement, antioxidant, hypoglycemia and hypolipidemia provided a potential multi-target agent to ameliorate the diabetes mellitus and its complications.

Rupatadine, a dual antagonist of histamine and platelet-activating factor (PAF), attenuates experimentally induced diabetic nephropathy in rats.

The role of histamine and platelet activating factor (PAF) as involved mediators in the pathophysiology of diabetic complications, in particular diabetic nephropathy (DN), has become a new focus of concern. Accordingly, the present study designed to explore the effect of rupatadine (RUP), a dual antagonist of histamine (H1) and PAF, on the progression of experimentally induced DN in rats. Rats were divided into five groups: control, RUP alone, streptozotocin (STZ)-diabetic model, STZ/RUP (3mg/kg/day), and STZ/RUP (6mg/kg/day). Treatment has continued for 4weeks after diabetes confirmation. At the end of the study, serum was collected for measurement of glucose, insulin, urea, creatinine, histamine, and PAF. Renal tissue homogenates were prepared for measuring oxidative stress indices, tumor necrosis factor (TNF-α), cystatin C, and p21. Moreover, immunohistochemical expression of transforming growth factor-β1 (TGF-β1) and p53 along with histological pictures was also conducted. Antagonizing H1 and PAF receptors by RUP ameliorated the experimentally induced DN as evident by decreasing all serum parameters augmented by STZ together with improvement of the histopathological picture. RUP administration also improved oxidative-antioxidative agents with reduction in the anti-inflammatory marker, TNF-α. Additionally, the immunohistochemical expression of the fibrosis marker; TGF-β1, was also decreased. STZ-induced DN showed a p21/p53-dependent induction of premature senescence and RUP administration decreased the expression of p21 and p53 levels in injured renal tissue. RUP represents a novel promising drug to prevent DN complicated diabetes probably via its inhibitory effect on H1 and PAF receptors. The renal protection was also related to the anti-inflammatory and antioxidant roles and PAF-facilitated senescence effect via p21/p53 signaling.

Role of the Nox4/AMPK/mTOR signaling axe in adipose inflammation-induced kidney injury.

Diabetic kidney disease is one of the most serious complications of diabetes worldwide and is the leading cause of end-stage renal disease. While research has primarily focused on hyperglycemia as a key player in the pathophysiology of diabetic complications, recently, increasing evidence have underlined the role of adipose inflammation in modulating the development and/or progression of diabetic kidney disease. This review focuses on how adipose inflammation contribute to diabetic kidney disease. Furthermore, it discusses in detail the underlying mechanisms of adipose inflammation, including pro-inflammatory cytokines, oxidative stress, and AMPK/mTOR signaling pathway and critically describes their role in diabetic kidney disease. This in-depth understanding of adipose inflammation and its impact on diabetic kidney disease highlights the need for novel interventions in the treatment of diabetic complications.

Inhibition effects of quinones on aldose reductase: Antidiabetic properties

Diabetes mellitus is a chronic metabolic disease characterized by abnormal glucose metabolism. Aldose reductase (AR) is the first enzyme in the polyol pathway and converts glucose to sorbitol. It plays a vital role as a glucose reducing agent and is involved in the pathophysiology of diabetic complications. In this study, we purified AR from sheep kidney with a specific activity of 2.00 EU/mg protein and 133.33- fold purification After the purification of the AR enzyme, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed and the molecular weight of the enzyme was found approximately as 38 kDa. The inhibition effects of eight quinones were studied against AR. The quinones were potent inhibitors of AR with Ki values in the range of 0.07–20.04 μM. Anthraquinone showed the best potential inhibitory effects against AR. All compounds exhibited noncompetitive inhibition against AR. These compounds may be selective inhibitors of this enzyme. AR inhibition is an essential strategy for the attenuation and prevention of diabetic complications.

A review of the anti-inflammatory properties of antidiabetic agents providing protective effects against vascular complications in diabetes.

The global prevalence of Type 2 diabetes mellitus and its associated complications are growing rapidly. Although the role of hyperglycemia is well recognized in the pathophysiology of diabetic complications, its exact underlying mechanisms are not fully understood. In this regard, accumulating evidence suggests that the role of inflammation appears pivotal, with studies showing that most diabetic complications are associated with an inflammatory response. Several classes of antidiabetic agents have been introduced for controlling glycemia, with evidence that these pharmacological agents may have modulatory effects on inflammation beyond their glucose-lowering activity. Here we review the latest evidence on the anti-inflammatory effects of commonly used antidiabetic medications and discuss the relevance of these effects on preventing diabetic complications.

Genetically Reduced Chondroitin Sulfate Prevents the Progression of Diabetic Neuropathy

Background: The extracellular matrix is associated with the pathophysiology of diabetic complications; however, the role of chondroitin sulfate (CS) remains unclear. To clarify the effects of CS on diabetic neuropathy (DN), we assessed the effect of genetically reducing CS in mice through disruption of a gene encoding the rate-limiting CS-synthesizing enzyme, i.e., CS N-acetylgalactosaminyltransferase-1 (T1). Methods: T1 knockout (T1KO) mice were generated from the C57BL/6N strain and C57BL/6N were prepared as wild type (WT). Diabetes was induced through streptozotocin injection in 6-week-old male mice. All data were obtained 3 weeks after streptozotocin injection. Results: In the heat radiant test, while thermal nociception in nondiabetic WT and T1KO mice were normal and significantly disrupted in diabetic WT mice, that in diabetic T1KO mice was preserved. The number of plantar peripheral nerve fibers was also significantly decreased in diabetic WT mice; however, that in diabetic T1KO mice were relatively normal. Furthermore, immunohistochemistry revealed loss of calcitonin gene-related peptide-positive neurons in the dorsal root ganglia (DRG) in diabetic WT mice, which contains a cluster of sensory neuron bodies. In contrast, those neurons were protected in diabetic T1KO mice. Hence, nociception and thermoception are preserved in diabetic T1KO mice. To investigate the mechanisms underlying these events, we analyzed gene expression in DRG through real-time polymerase chain reaction and confirmed the suppression of caspase-3 and caspase-9 in diabetic T1KO mice, compared to those in diabetic WT mice. However, levels of Bcl2, TNF-α, MMP9, and reactive oxygen species-related enzymes (HO-1, NOX) did not differ significantly between WT and T1KO diabetic mice. Conclusions: Reduced CS production is suggested to have potentially beneficial effects on preventing DN by suppressing apoptotic signaling and could be a cutting-edge target of clinical application. Disclosure H. Ishiguro: Research Support; Self; MSD K.K., Sanofi K.K., Eli Lilly and Company. T. Ushiki: None. A. Kawasaki: None. K. Cho: None. M. Masuko: None. K. Sango: None. M. Igarashi: None. H. Sone: Research Support; Self; Novo Nordisk Inc., Eli Lilly and Company, MSD K.K., Chugai Pharmaceutical Co., Ltd., Taisho Pharmaceutical Co., Ltd., Takeda Development Center Asia, Pte. Ltd., Daiichi Sankyo Company, Limited, Ono Pharmaceutical Co., Ltd., Kyowa Hakko Kirin Co., Ltd., Sanofi, Kowa Pharmaceuticals America, Inc., Eisai Inc..