Vasculopathy in type 2 diabetes mellitus: role of specific angiogenic modulators

Effect of nattokinase on the pathological conditions in streptozotocin induced diabetic rats

Nattokinase (NK), also known as subtilisin NAT (EC 3.4.21.62), is a serine protease produced by Bacillus subtilis natto that has anti-inflammatory and fibrinolytic properties. To study whether NK prevents the progression of pathological changes in diabetes as an inflammatory disease, we examined the effect of NK on pathological conditions in streptozotocin (STZ)-induced diabetic rats using the following parameters: fasting blood glucose (glucose), total plasma protein (TP), creatinine, histopathology of renal corpuscles and tubules, advanced glycation end products (AGEs), and C-reactive protein (CRP). STZ-administered rats were maintained on a basic diet (CE-2) as control, low-NK diet (containing 0.2 mg NK/g diet), and high-NK diet (0.6 mg NK/g diet) for 14 days. High-dose NK significantly inhibited both glycogen deposition in the renal tubules and increase in the circulating AGE levels without downregulating glucose levels. Compared with the control group, the group treated with the high-NK diet presented a significant inhibition of the increase in the circulating CRP level on day 7 after the beginning of the treatment. However, the CRP level in the NK-H group reached the same level as that in the control group on Day 14. AGEs are known to induce CRP expression in hepatocytes, but the increase in CRP levels in our animal model was independent on the circulating AGE levels. In contrast, low-dose NK did not suppress changes in these parameters. Our present study suggests that NK suppresses glycogen deposition in renal tubules in a dose-dependent manner by the downregulation of AGE formation under hyperglycaemia in the rats with STZ-induced short-term diabetes. However, it is unclear whether this downregulation is caused by intact NK or peptides derived from NK during its digestion in the digestive tract.

Hydrocephalus is an independent factor affecting morbidity and mortality of ICH patients: Systematic review and meta-analysis

Background

Despite advances in our knowledge of the causes, preventions, and treatments of stroke, it continues to be a leading cause of death and disability. The most common type of stroke-related morbidity and mortality is intracerebral haemorrhage (ICH). Many prognostication scores include an intraventricular extension (IVH) after ICH because it affects mortality independently. Although it is a direct result of IVH and results in significant damage, hydrocephalus (HC) has never been taken into account when calculating prognostication scores. This study aimed to evaluate the significance of hydrocephalus on the outcomes of ICH patients by meta-analysis.

Methods

Studies that compared the rates of mortality and/or morbidity in patients with ICH, ICH with IVH (ICH ​+ ​IVH), and ICH with IVH and HC (ICH ​+ ​IVH ​+ ​HC) were identified. A meta-analysis was performed by using Mantel-Haezel Risk Ratio at 95% significance.

Results

This meta-analysis included thirteen studies. The findings indicate that ICH ​+ ​IVH ​+ ​HC has higher long-term (90-day) and short-term (30-day) mortality risks than ICH (4.26 and 2.30 higher risks, respectively) and ICH ​+ ​IVH (1.96 and 1.54 higher risks). Patients with ICH ​+ ​IVH ​+ ​HC have lower rates of short-term (3 months) and long-term (6 months) good functional outcomes than those with ICH (0.66 and 0.38 times) or ICH ​+ ​IVH (0.76 and 0.54 times). Confounding variables included vascular comorbidities, haemorrhage volume, midline shift, and an initial GCS score below 8.

Conclusion

Hydrocephalus causes a poorer prognosis in ICH patients. Thus, it is reasonable to suggest the inclusion of hydrocephalus in ICH prognostication scoring systems.

Circulating Angiogenic Factors and Ischemic Diabetic Foot Syndrome Advancement-A Pilot Study

Despite clear evidence of inadequate angiogenesis in ischemic diabetic foot syndrome (DFS) pathogenesis, angiogenic factor level changes in patients with ischemic DFS remain inconsistent. This study aimed to assess circulating angiogenic factors concerning ischemic DFS advancement and describe their relationships with patients' clinical characteristics, microvascular parameters, and diabetic control. The study included 41 patients with ischemic DFS (67.3 (8.84) years; 82.9% males). Angiogenic processes were assessed by identifying circulating concentrations of five pro- and two anti-angiogenic factors. We found that penetrating ulcers were related to a significantly higher FGF-2 level (8.86 (5.29) vs. 5.23 (4.17) pg/mL, p = 0.02). Moreover, plasma FGF-2 showed a significant correlation with the SINBAD score (r = 0.32, p = 0.04), platelet count (r = 0.43, p < 0.01), white cell count (r = 0.42, p < 0.01), and age (r = -0.35, p = 0.03). We did not observe any significant linear relationship between the studied biomarkers and microcirculatory parameters, nor for glycemic control. In a univariate analysis using logistic regression, an increase in plasma FGF-2 was tied to greater odds of high-grade ulcers (OR 1.16; 95% CI 1.02-1.38, p = 0.043). This suggests that circulating FGF-2 may serve as a potential biomarker for predicting DFU advancement and progression. It is necessary to conduct further studies with follow-up observations to confirm this hypothesis.

Dietary Flavonoids Alleviate Inflammation and Vascular Endothelial Barrier Dysfunction Induced by Advanced Glycation End Products In Vitro

The aim of this study was to compare the protective effects of three dietary flavonoids (apigenin-7-O-glucoside (A7G), isorhamnetin-3-O-rutinoside (I3R), and cyanidin-3-O-glucoside (C3G)) on advanced glycation end products (AGEs)-induced inflammation and vascular endothelial dysfunction. Furthermore, the potential mechanisms of varied effects of those three dietary flavonoids were analyzed by molecular docking analysis. Results showed that C3G (40 μM) achieved the best inhibition on inflammatory cytokines (TNF-α, IL-1β, and IL-6) in AGEs-induced RAW264.7 cells, followed by I3R, and A7G was the weakest. The molecular docking results also showed that C3G exhibited the closest binding with the receptor for AGE. However, I3R (40 μM) demonstrated the best effect in improving endothelial dysfunction in AGEs-induced EA.hy926 cells, followed by C3G, and A7G was the weakest, as evidenced by the molecular docking results of flavonoids with profilin-1. This work may provide knowledge and helpful suggestions regarding the benefits of dietary flavonoids in diabetic vascular complications.

Maternal Fatty Acid Metabolism in Pregnancy and Its Consequences in the Feto-Placental Development

During pregnancy, maternal plasma fatty acids are critically required for cell growth and development, cell signaling, and the development of critical structural and functional aspects of the feto-placental unit. In addition, the fatty acids modulate the early stages of placental development by regulating angiogenesis in the first-trimester human placenta. Preferential transport of maternal plasma long-chain polyunsaturated fatty acids during the third trimester is critical for optimal fetal brain development. Maternal status such as obesity, diabetes, and dietary intakes may affect the functional changes in lipid metabolic processes in maternal-fetal lipid transport and metabolism. Fatty acids traverse the placental membranes via several plasma membrane fatty acid transport/binding proteins (FAT, FATP, p-FABPpm, and FFARs) and cytoplasmic fatty acid-binding proteins (FABPs). This review discusses the maternal metabolism of fatty acids and their effects on early placentation, placental fatty acid transport and metabolism, and their roles in feto-placental growth and development. The review also highlights how maternal fat metabolism modulates lipid processing, including transportation, esterification, and oxidation of fatty acids.

Thymidine Phosphorylase Is Increased in COVID-19 Patients in an Acuity-Dependent Manner

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), is a human respiratory disease. Hitherto, there is no effective treatment has been established. Patients with cardiovascular or diabetes comorbidities are a high-risk cohort. COVID-19 is accompanied by excessive systemic thrombotic events, but the mechanism is not yet known. Recent studies have indicated that thymidine phosphorylase (TYMP) plays an important role in platelet activation, thrombosis, and TYMP expression is increased in diabetic patients. By using data provided by the MGH (Massachusetts General Hospital) Emergency Department COVID-19 Cohort with Olink Proteomics, here we show that plasma TYMP level is correlated with the COVID-19 associated thrombotic event, inflammation, and organ damage, as evidenced by the positive correlations with plasma D-dimer, CRP (C reactive protein), and LDH (lactate dehydrogenase), as well as Interferons (IFN). Plasma TYMP is also positively correlated with COVID-19 patients who had respiratory symptoms. TYMP thus could be an acuity marker for COVID-19 diagnosis. Targeting TYMP with tipiracil, a selective TYMP inhibitor, which has been approved by the Food and Drug Administration for clinical use, could be a novel effective medicine for COVID-19.

Targeting Thymidine Phosphorylase With Tipiracil Hydrochloride Attenuates Thrombosis Without Increasing Risk of Bleeding in Mice

OBJECTIVE

Current antiplatelet medications increase the risk of bleeding, which leads to a clear clinical need in developing novel mechanism-based antiplatelet drugs. TYMP (Thymidine phosphorylase), a cytoplasm protein that is highly expressed in platelets, facilitates multiple agonist-induced platelet activation, and enhances thrombosis. Tipiracil hydrochloride (TPI), a selective TYMP inhibitor, has been approved by the Food and Drug Administration for clinical use. We tested the hypothesis that TPI is a safe antithrombotic medication. Approach and Results: By coexpression of TYMP and Lyn, GST (glutathione S-transferase) tagged Lyn-SH3 domain or Lyn-SH2 domain, we showed the direct evidence that TYMP binds to Lyn through both SH3 and SH2 domains, and TPI diminished the binding. TYMP deficiency significantly inhibits thrombosis in vivo in both sexes. Pretreatment of platelets with TPI rapidly inhibited collagen- and ADP-induced platelet aggregation. Under either normal or hyperlipidemic conditions, treating wild-type mice with TPI via intraperitoneal injection, intravenous injection, or gavage feeding dramatically inhibited thrombosis without inducing significant bleeding. Even at high doses, TPI has a lower bleeding side effect compared with aspirin and clopidogrel. Intravenous delivery of TPI alone or combined with tissue plasminogen activator dramatically inhibited thrombosis. Dual administration of a very low dose of aspirin and TPI, which had no antithrombotic effects when used alone, significantly inhibited thrombosis without disturbing hemostasis.

CONCLUSIONS

This study demonstrated that inhibition of TYMP, a cytoplasmic protein, attenuated multiple signaling pathways that mediate platelet activation, aggregation, and thrombosis. TPI can be used as a novel antithrombotic medication without the increase in risk of bleeding.

Maternal dietary fatty acids and their roles in human placental development

Fatty acids are essential for feto-placental growth and development. Maternal fatty acids and their metabolites are involved in every stage of pregnancy by supporting cell growth and development, cell signaling, and modulating other critical aspects of structural and functional processes. Early placentation process is critical for placental growth and function. Several fatty acids modulate angiogenesis as observed by increased tube formation and secretion of angiogenic growth factors in first-trimester human placental trophoblasts. Long-chain fatty acids stimulate angiogenesis in these cells via vascular endothelium growth factor (VEGF), angiopoietin-like protein 4 (ANGPTL4), fatty acid-binding proteins (FABPs), or eicosanoids. Inadequate placental angiogenesis and trophoblast invasion of the maternal decidua and uterine spiral arterioles leads to structural and functional deficiency of placenta, which contributes to preeclampsia, pre-term intrauterine growth restriction, and spontaneous abortion and also affects overall fetal growth and development. During the third trimester of pregnancy, placental preferential transport of maternal plasma long-chain polyunsaturated fatty acids is of critical importance for fetal growth and development. Fatty acids cross the placental microvillous and basal membranes by mainly via plasma membrane fatty acid transport system (FAT, FATP, p-FABPpm, & FFARs) and cytoplasmic FABPs. Besides, a member of the major facilitator superfamily-MFSD2a, present in the placenta is involved in the supply of DHA to the fetus. Maternal factors such as diet, obesity, endocrine, inflammation can modulate the expression and activity of the placental fatty acid transport activity and thereby impact feto-placental growth and development. In this review, we discuss the maternal dietary fatty acids, and placental transport and metabolism, and their roles in placental growth and development.

Pituitary adenylate cyclase-activating polypeptide ameliorates vascular dysfunction induced by hyperglycaemia

BACKGROUND

Short-lasting hyperglycaemia occurs frequently in prediabetes and poorly controlled diabetes mellitus leading to vascular damage. Pituitary adenylate cyclase-activating polypeptide (PACAP) has been shown to play a protective role in vascular complications of diabetes; moreover, antioxidant effects of PACAP were also described. Therefore, we hypothesized that PACAP exerts protective effects in short-term hyperglycaemia-induced vascular dysfunctions.

METHODS

After short-term hyperglycaemia, acetylcholine-induced and sodium nitroprusside-induced vascular relaxation of mouse carotid arteries were tested with a myograph with or without the presence of PACAP or superoxide dismutase. Potential direct antioxidant superoxide-scavenging action of pituitary adenylate cyclase-activating peptide was tested with pyrogallol autoxidation assay; furthermore, the effect of pituitary adenylate cyclase-activating peptide or superoxide dismutase was investigated on hyperglycaemia-associated vascular markers.

RESULTS

PACAP administration resulted in reduced endothelial dysfunction after a 1-h hyperglycaemic episode. PACAP was able to restore acetylcholine-induced relaxation of the vessels and improved sodium nitroprusside-induced relaxation. This effect was comparable to the protective effect of superoxide dismutase, but PACAP was unable to directly scavenge superoxide produced by autoxidation of pyrogallol. Endothelial dysfunction was associated with elevated levels of fibroblast growth factor basic, matrix metalloproteinase 9 and nephroblastoma overexpressed gene proteins. Their release was reduced by PACAP administration.

CONCLUSION

These results suggest a strong protective role of PACAP in the vascular complications of diabetes.

Gangliosides in Diabetic Wound Healing

An organized series of complicated biological and molecular phenomena is required for normal skin wound healing. These processes depend on normal cellular responses to cytokines, growth factors, and other mediators, such as clotting factors, prostaglandins, free radicals, and nitric oxide. In diabetic ulcers, impaired responses to these molecules lead to abnormalities in vascularization, innervation, matrix reconstruction, and reepithelialization of wounds. keratinocyte migration and proliferation on an extracellular matrix is critical in reepithelialization, but the response to growth factors is blunted in diabetes, including the insulin/IGF-1signaling axis. Ganglioside GM3, a sialylated epidermal glycosphingolipid, has been identified as a key mediator of the inhibition of insulin/IGF-1 signaling in response to factors, such as tumor necrosis factor-alpha (TNF-α) and hyperglycemia. Decreased expression of GM3 and the enzyme required for its synthesis, GM3 synthase (GM3S), leads to increased insulin/IGF-1 receptor signaling and accelerated keratinocyte migration, even in the presence of high glucose levels. GM3 depletion in GM3S knockout diabetic mice and diet-induced diabetic mice treated topically with nanoconstruct-mediated GM3S-targeting gene regulation also accelerates wound healing. These recent observations, coupled with evidence that GM3 depletion reverses distal innervation abnormalities in diabetic mice, suggest that GM3-depleting strategies are a promising new approach for human diabetic wounds.

Association of increased levels of MCP-1 and cathepsin-D in young onset type 2 diabetes patients (T2DM-Y) with severity of diabetic retinopathy

AIM

Young onset type 2 diabetes patients (T2DM-Y) have been shown to possess an increased risk of developing microvascular complications particularly diabetic retinopathy. However, the molecular mechanisms are not clearly understood. In this study, we investigated the serum levels of monocyte chemotactic protein 1 (MCP-1) and cathepsin-D in patients with T2DM-Y without and with diabetic retinopathy.

METHODS

In this case-control study, participants comprised individuals with normal glucose tolerance (NGT=40), patients with type 2 diabetes mellitus (T2DM=35), non-proliferative diabetic retinopathy (NPDR=35) and proliferative diabetic retinopathy (PDR=35). Clinical characterization of the study subjects was done by standard procedures and MCP-1 and cathepsin-D were measured by ELISA.

RESULTS

Compared to control individuals, patients with T2DM-Y, NPDR and PDR exhibited significantly (p<0.001) higher levels of MCP-1. Cathepsin-D levels were also significantly (p<0.001) higher in patients with T2DM-Y without and with diabetic retinopathy. Correlation analysis revealed a positive association (p<0.001) between MCP-1 and cathepsin-D levels. There was also a significant negative correlation of MCP1/cathepsin-D with C-peptide levels. The association of increased levels of MCP-1/cathepsin-D in patients with DR persisted even after adjusting for all the confounding factors.

CONCLUSION

As both MCP-1 and cathepsin-D are molecular signatures of cellular senescence, we suggest that these biomarkers might be useful to predict the development of retinopathy in T2DM-Y patients.

Immunomodulatory and antioxidant effects of saffron aqueous extract (Crocus sativus L.) on streptozotocin-induced diabetes in rats

Introduction

Crocus sativus L. (saffron) has many biological effects such as antioxidant property. The present study investigated the immunomodulatory effects of the aqueous saffron extract on streptozotocin (STZ)-induced diabetic rats.

Materials and methods

In this study, the rats were divided into the following groups of 9 animals each: control, untreated diabetic, three saffron extract-treated diabetic groups. Diabetes was induced by STZ in rats. Saffron was administered 3 days after STZ administration; these injections were continued to the end of the study (4 weeks). At the end of the 4-week period, blood was drawn for biochemical assays and the abdominal aorta was removed for detecting the inflammatory cytokines expression.

Results

We found that saffron decreased blood glucose, malondialdehyde, nitric oxide, total lipids, triglycerides, cholesterol levels significantly (p < 0.01) and increased glutathione level, catalase, and superoxide dismutase activities in the saffron-treated diabetic groups compared with the untreated groups, in a dose dependent manner (p < 0.05, p < 0.01, p < 0.001). On the other hand, saffron-treated diabetic rats inhibited the expression of inflammatory cytokines in the abdominal aorta versus the untreated diabetic rats.

Conclusion

Our results validate the use of saffron as a treatment against diabetes mellitus and its vascular complications.

High levels of cathepsin D and cystatin B are associated with increased risk of coronary events

Objective

The majority of acute coronary syndromes are caused by plaque ruptures. Proteases secreted by macrophages play an important role in plaque ruptures by degrading extracellular matrix proteins in the fibrous cap. Matrix metalloproteinases have been shown to be markers for cardiovascular disease whereas the members of the cathepsin protease family are less studied.

Methods

Cathepsin D, cathepsin L and cystatin B were measured in plasma at baseline from 384 individuals who developed coronary events (CEs), and from 409 age-matched and sex-matched controls from the Malmö Diet and Cancer cardiovascular cohort.

Results

Cathepsin D (180 (142–238) vs 163 (128–210), p<0.001), cathepsin L (55 (44–73) vs 52 (43–67), p<0.05) and cystatin B levels (45 (36–57) vs 42 (33–52), p<0.001) were significantly increased in CE cases compared to controls. In addition, increased cathepsin D (220 (165–313) vs 167 (133–211), p<0.001), cathepsin L (61 (46–80) vs 53 (43–68), p<0.05) and cystatin B (46 (38–58) vs 43 (34–54), p<0.05) were associated with prevalent diabetes. Furthermore, cathepsin D and cystatin B were increased in smokers. The HRs for incident CE comparing the highest to the lowest tertile(s) of cathepsin D and cystatin B were 1.34 (95% CI 1.02 to 1.75) and 1.26 (95% CI 1.01 to 1.57), respectively, after adjusting for age, sex, low-density lipoprotein/high-density lipoprotein ratio, triglycerides, body mass index, hypertension and glucose, but these associations did not remain significant after further addition of smoking to the model. In addition, cathepsin D was increased in incident CE cases among smokers after adjusting for cardiovascular risk factors.

Conclusions

The associations of cathepsin D and cystatin B with future CE provide clinical support for a role of these factors in cardiovascular disease, which for cathepsin D may be of particular importance for smokers.

Glypican-5 Increases Susceptibility to Nephrotic Damage in Diabetic Kidney

Type 2 diabetes mellitus is a leading health issue worldwide. Among cases of diabetes mellitus nephropathy (DN), the major complication of type 2 diabetes mellitus, the nephrotic phenotype is often intractable to clinical intervention and demonstrates the rapid decline of renal function to end-stage renal disease. We recently identified the gene for glypican-5 (GPC5), a cell-surface heparan sulfate proteoglycan, as conferring susceptibility for acquired nephrotic syndrome and additionally identified an association through a genome-wide association study between a variant in GPC5 and DN of type 2 diabetes mellitus. In vivo and in vitro data showed a progressive increase of GPC5 in type 2 DN along with severity; the excess was derived from glomerular mesangial cells. In this study, diabetic kidney showed that accumulation of fibroblast growth factor (Fgf)2 strikingly induced progressive proteinuria that was avoided in Gpc5 knockdown mice. The efficacy of Gpc5 inhibition was exerted through expression of the Fgf receptors 3 and 4 provoked in the diabetic kidney attributively. Extraglomerular Fgf2 was pathogenic in DN, and the deterrence of Gpc5 effectively inhibited the glomerular accumulation of Fgf2, the subsequent increase of mesangial extracellular matrix, and the podocytes' small GTPase activity. These findings elucidate the pivotal role of GPC5, identified as a susceptible gene in the genome-wide association study, in hyperglycemia-induced glomerulopathy.

The Role of Oxidized Cholesterol in Diabetes-Induced Lysosomal Dysfunction in the Brain

Abnormalities in lysosomal function have been reported in diabetes, aging, and age-related degenerative diseases. These lysosomal abnormalities are an early manifestation of neurodegenerative diseases and often precede the onset of clinical symptoms such as learning and memory deficits; however, the mechanism underlying lysosomal dysfunction is not known. In the current study, we investigated the mechanism underlying lysosomal dysfunction in the cortex and hippocampi, key structures involved in learning and memory, of a type 2 diabetes (T2D) mouse model, the leptin receptor deficient db/db mouse. We demonstrate for the first time that diabetes leads to destabilization of lysosomes as well as alterations in the protein expression, activity, and/or trafficking of two lysosomal enzymes, hexosaminidase A and cathepsin D, in the hippocampus of db/db mice. Pioglitazone, a thiazolidinedione (TZD) commonly used in the treatment of diabetes due to its ability to improve insulin sensitivity and reverse hyperglycemia, was ineffective in reversing the diabetes-induced changes on lysosomal enzymes. Our previous work revealed that pioglitazone does not reverse hypercholesterolemia; thus, we investigated whether cholesterol plays a role in diabetes-induced lysosomal changes. In vitro, cholesterol promoted the destabilization of lysosomes, suggesting that lysosomal-related changes associated with diabetes are due to elevated levels of cholesterol. Since lysosome dysfunction precedes neurodegeneration, cognitive deficits, and Alzheimer’s disease neuropathology, our results may provide a potential mechanism that links diabetes with complications of the central nervous system.

Thymidine phosphorylase participates in platelet signaling and promotes thrombosis

RATIONALE

Platelets contain abundant thymidine phosphorylase (TYMP), which is highly expressed in diseases with high risk of thrombosis, such as atherosclerosis and type II diabetes mellitus.

OBJECTIVE

To test the hypothesis that TYMP participates in platelet signaling and promotes thrombosis.

METHODS AND RESULTS

By using a ferric chloride (FeCl3)-induced carotid artery injury thrombosis model, we found time to blood flow cessation was significantly prolonged in Tymp(-/-) and Tymp(+/-) mice compared with wild-type mice. Bone marrow transplantation and platelet transfusion studies demonstrated that platelet TYMP was responsible for the antithrombotic phenomenon in the TYMP-deficient mice. Collagen-, collagen-related peptide-, adenosine diphosphate-, or thrombin-induced platelet aggregation were significantly attenuated in Tymp(+/-) and Tymp(-/-) platelets, and in wild type or human platelets pretreated with TYMP inhibitor KIN59. Tymp deficiency also significantly decreased agonist-induced P-selectin expression. TYMP contains an N-terminal SH3 domain-binding proline-rich motif and forms a complex with the tyrosine kinases Lyn, Fyn, and Yes in platelets. TYMP-associated Lyn was inactive in resting platelets, and TYMP trapped and diminished active Lyn after collagen stimulation. Tymp/Lyn double haploinsufficiency diminished the antithrombotic phenotype of Tymp(+/-) mice. TYMP deletion or inhibition of TYMP with KIN59 dramatically increased platelet-endothelial cell adhesion molecule 1 tyrosine phosphorylation and diminished collagen-related peptide- or collagen-induced AKT phosphorylation. In vivo administration of KIN59 significantly inhibited FeCl3-induced carotid artery thrombosis without affecting hemostasis.

CONCLUSIONS

TYMP participates in multiple platelet signaling pathways and regulates platelet activation and thrombosis. Targeting TYMP might be a novel antiplatelet and antithrombosis therapy.

Ganglioside GM3 depletion reverses impaired wound healing in diabetic mice by activating IGF-1 and insulin receptors

Background

Ganglioside GM3 mediates adipocyte insulin resistance, but the role of GM3 in diabetic wound healing, a major cause of morbidity, is unclear.

Purpose

Determine whether GM3 depletion promotes diabetic wound healing and directly activates keratinocyte insulin pathway signaling.

Results

GM3 synthase (GM3S) expression is increased in human diabetic foot skin, ob/ob and diet-induced obese diabetic mouse skin, and mouse keratinocytes exposed to increased glucose. GM3S knockout in diet-induced obese mice prevents the diabetic wound healing defect. Keratinocyte proliferation, migration, and activation of insulin receptor (IR) and insulin growth factor-1 receptor (IGF-1R) are suppressed by excess glucose in wild type cells, but increased in GM3S ^−/− keratinocytes with supplemental glucose. Co-immunoprecipitation of IR, IR substrate-1 (IRS-1), and IGF-1R, and increased IRS-1 and Akt phosphorylation accompany receptor activation. GM3 supplementation or inhibition of IGF-1R or PI3K reverses the increased migration of GM3S^−/− keratinocytes, whereas IR knockdown only partially suppresses migration.

Conclusions

Cutaneous GM3 accumulation may participate in the impaired wound healing of diet-induced diabetes by suppressing keratinocyte insulin/IGF-1 axis signaling. Strategies to deplete GM3S/GM3 may improve diabetic wound healing.

Metabolomics study of type 2 diabetes using ultra-performance LC-ESI/quadrupole-TOF high-definition MS coupled with pattern recognition methods

Type 2 diabetes (T2D), called the burden of the twenty-first century, is growing with an epidemic rate. Here, we explored the differences in metabolite concentrations between T2D patients and healthy volunteers. Metabolomics represents an emerging discipline concerned with comprehensive analysis of small molecule metabolites and provides a powerful approach to discover biomarkers in biological systems. The acquired data were analyzed by ultra-performance liquid chromatography-electrospray ionization/quadrupole time-of-flight high-definition mass spectrometry coupled with pattern recognition approach [principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA)] to identify potential disease-specific biomarkers. PCA showed satisfactory clustering between patients and healthy volunteers. Biomarkers reflected the biochemical events associated with early stages of T2D which were observed in PLS-DA loading plots. These urinary differential metabolites, such as adiponectin, acylcarnitines, citric acid, kynurenic acid, 3-indoxyl sulfate, urate, and glucose, were identified involving several key metabolic pathways such as taurine and hypotaurine metabolism; cysteine and methionine metabolism; valine, leucine, and isoleucine biosynthesis metabolism, etc. Our data suggest that robust metabolomics has the potential as a noninvasive strategy to evaluate the early diagnosis of T2D patients and provides new insight into pathophysiologic mechanisms and may enhance the understanding of its cause of disease.