Whole blood aggregation and coagulation in db/db and ob/ob mouse models of type 2 diabetes

Integrated liver and plasma proteomics in obese mice reveals complex metabolic regulation

Obesity leads to the development of nonalcoholic fatty liver disease (NAFLD) and associated alterations to the plasma proteome. To elucidate the underlying changes associated with obesity, we performed liquid chromatography–tandem mass spectrometry in the liver and plasma of obese leptin-deficient ob/ob mice and integrated these data with publicly available transcriptomic and proteomic datasets of obesity and metabolic diseases in preclinical and clinical cohorts. We quantified 7173 and 555 proteins in the liver and plasma proteomes, respectively. The abundance of proteins related to fatty acid metabolism were increased, alongside peroxisomal proliferation in ob/ob liver. Putatively secreted proteins and the secretory machinery were also dysregulated in the liver, which was mirrored by a substantial alteration of the plasma proteome. Greater than 50% of the plasma proteins were differentially regulated, including NAFLD biomarkers, lipoproteins, the 20S proteasome, and the complement and coagulation cascades of the immune system. Integration of the liver and plasma proteomes identified proteins that were concomitantly regulated in the liver and plasma in obesity, suggesting that the systemic abundance of these plasma proteins is regulated by secretion from the liver. Many of these proteins are systemically regulated during type 2 diabetes and/or NAFLD in humans, indicating the clinical importance of liver–plasma cross talk and the relevance of our investigations in ob/ob mice. Together, these analyses yield a comprehensive insight into obesity and provide an extensive resource for obesity research in a prevailing model organism.

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Proteomics reveals liver-derived proteins systemically dysregulated in obesity.

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Obesity increases hepatic lipid metabolism via peroxisomal biogenesis.

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Obesity dysregulates secretory machinery and secreted proteins within the liver.

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Metabolic and immune proteins dysregulated in plasma of obese mice.

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Comparative proteomics of high-fat diet and monogenic (ob/ob) models of obesity.

Correlation of vascular endothelial function and coagulation factors with renal function and inflammatory factors in patients with diabetic nephropathy

Correlation of vascular endothelial function and coagulation factors with renal function and inflammatory factors in patients with diabetic nephropathy was analyzed. A total of 86 patients diagnosed with diabetes mellitus (DM) and admitted to the 89th Hospital of the People's Liberation Army (Weifang, China) from March 2014 to May 2017 were selected. Among them, 38 patients complicated with nephropathy were divided into the observation group and 48 patients without nephropathy into the control group. The general data of patients were collected, and the relevant biochemical indexes, vascular endothelial function, coagulation factors and renal function indicators and the levels of inflammatory factors were determined. In the observation group, the duration of DM was longer than that in the control group, and the levels of glycated hemoglobin (HbA1c), fasting plasma glucose (FPG) and fasting insulin (FINS), level of fibrinogen (FIB) were higher than those in the control group (p<0.05). Homocysteine (Hcy) and brachial artery blood flow in the observation group were higher than those in the control group. The levels of nitric oxide (NO) and flow-mediated dilation (FMD) were lower than those in the control group (p<0.05). Activated partial thromboplastin time (APTT) in the observation group was shorter than that in the control group (p<0.05). The levels of cystatin-C (Cys-C), serum creatinine (SCr), urea and β2-microglobulin, levels of C-reactive protein (CRP), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in peripheral serum in the observation group were greatly higher than those in the control group (p<0.05). It was concluded via the correlation analysis of vascular endothelial function and coagulation factor with renal function and inflammatory factors that SCr and CRP were negatively correlated with NO, and SCr and CRP were positively correlated with FIB. Serum inflammatory factors, coagulation function and vascular endothelial function are closely related to diabetic nephropathy, which are good reference indexes for the assessment of diabetic nephropathy.

Improving the understanding of plasma kallikrein contribution to arterial thrombus formation using two plant protease inhibitors

The purpose of antithrombotic therapy is the prevention of thrombus formation and/or its extension with a minimum risk of bleeding. The inhibition of a variety of proteolytic processes, particularly those of the coagulation cascade, has been reported as a property of plant protease inhibitors. The role of trypsin inhibitors (TIs) from Delonix regia (Dr) and Acacia schweinfurthii (As), members of the Kunitz family of protease inhibitors, was investigated on blood coagulation, platelet aggregation, and thrombus formation. Different from Acacia schweinfurthii trypsin inhibitor (AsTI), Delonix regia trypsin inhibitor (DrTI) is a potent inhibitor of FXIa with a K_iapp of 1.3 × 10^-9 M. In vitro, both inhibitors at 100 µg corresponding to the concentrations of 21 μM and 15.4 μM of DrTI and AsTI, respectively, increased approximately 2.0 times the activated partial thromboplastin time (aPTT) in human plasma compared to the control, likely due to the inhibition of human plasma kallikrein (huPK) or activated factor XI (FXIa), in the case of DrTI. Investigating in vivo models of arterial thrombus formation and bleeding time, DrTI and AsTI, 1.3 µM and 0.96 µM, respectively, prolonged approximately 50% the time for total carotid artery occlusion in mice compared to the control. In contrast to heparin, the bleeding time in mice treated with the two inhibitors did not differ from that of the control group. DrTI and AsTI inhibited 49.3% and 63.8%, respectively, ex vivo murine platelet aggregation induced by adenosine diphosphate (ADP), indicating that these protein inhibitors prevent arterial thrombus formation possibly by interfering with the plasma kallikrein (PK) proteolytic action on the intrinsic coagulation pathway and its ability to enhance the platelet aggregation activity on the intravascular compartment leading to the improvement of a thrombus.

Enhanced adhesion of blood platelets to intact endothelium of mesenteric vascular bed in mice with streptozotocin-induced diabetes is mediated by an up-regulated endothelial surface deposition of VWF - In vivo study

Numerous in vitro experiments have confirmed that a dysfunctional endothelium is characterized by, inter alia, a higher affinity for binding of platelets and leukocytes. However, there is still no direct evidence for greater interaction between platelets and intact endothelium in in vivo animal models of diabetes. Therefore, the present study examines the pro-adhesive properties of endothelium change in vivo as an effect of streptozotocin (STZ)-induced diabetes and the role of two key platelet receptors: GPIb-IX-V and GPIIb/IIIa. Mice of C57BL strain with streptozotocin-induced diabetes were used in the study. Flow cytometry was used to assess basal activation and reactivity of platelets. Adhesion of platelets to the vascular wall was visualized with the use of intravital microscopy in mesentery. The contribution of GPIIb/IIIa and GPIb-IX-V was evaluated by the injection of Fab fragments of respective antibodies. The integrity of the endothelium and vWf expression were evaluated histochemically. Basal activation and reactivity of platelets in streptozotocin-diabetic mice were elevated. Blood platelets adhered more often to the vascular wall of diabetic mice than nondiabetic animals: 11.9 (6.4; 32.8) plt/min/mm² (median [IQR]) vs 2.7 (1.3; 6.4) plt/min/mm². The injection of anti-GPIbα antibodies decreased the number of adhering platelets from 89.5 (34.0; 113.1) plt/min/mm² (median [IQR]) in mice treated with isotype antibodies to 3.1 (1.7; 5.6) plt/min/mm² in mice treated with blocking antibodies. The effect of GPIIb/IIIa blockage was not significant. Immunohistochemistry revealed a higher expression of vWF in the endothelium of STZ mice, but no substantial changes in endothelial morphology were detected. To conclude, the study shows that the platelets interact more frequently with the mesenteric vascular bed in mice with 1-month STZ-induced diabetes than in healthy mice. These interactions are mediated via platelet GPIb-IX-V and are driven by increased expression of vWF in endothelial cells.

OBESITY AND CRITICAL ILLNESS: INSIGHTS FROM ANIMAL MODELS

Critical illness is a major cause of morbidity and mortality around the world. While obesity is often detrimental in the context of trauma, it is paradoxically associated with improved outcomes in some septic patients. The reasons for these disparate outcomes are not well understood. A number of animal models have been used to study the obese response to various forms of critical illness. Just as there have been many animal models that have attempted to mimic clinical conditions, there are many clinical scenarios that can occur in the highly heterogeneous critically ill patient population that occupies hospitals and intensive care units. This poses a formidable challenge for clinicians and researchers attempting to understand the mechanisms of disease and develop appropriate therapies and treatment algorithms for specific subsets of patients, including the obese. The development of new, and the modification of existing animal models, is important in order to bring effective treatments to a wide range of patients. Not only do experimental variables need to be matched as closely as possible to clinical scenarios, but animal models with pre-existing comorbid conditions need to be studied. This review briefly summarizes animal models of hemorrhage, blunt trauma, traumatic brain injury, and sepsis. It also discusses what has been learned through the use of obese models to study the pathophysiology of critical illness in light of what has been demonstrated in the clinical literature.

Establishment and Characterization of a Newly Established Diabetic Gerbil Line

Objectives

We aimed to selectively breed a spontaneous diabetic gerbil when a sub-line of inbred gerbil showed increased blood glucose levels was found recently. Then we investigated the characteristics including the serum insulin, triglyceride, cholesterol, leptin, adiponectin and explored the underlying molecular mechanism for the diabetic phenotype.

Methods

The spontaneous diabetic line of gerbils was selectively inbreed the sub-line of gerbil by monitoring blood glucose of each animal. The serum insulin, adiponectin, and leptin levels were tested using an ELISA kit. The expression levels of GLUT4, Akt, leptin, adiponectin, and calpain 10 (CAPN10) were tested by western blot and Quantitative Real-time PCR (qPCR) in liver, skeletal muscle, and white adipose.

Results

Our results show that the percentages of animals with FPG≥5.2 (mmol/l), PG2h≥6.8 (mmol/l) and both FPG≥5.2 and PG2h≥6.8 (mmol/l) were increased with the number of breeding generations from F0 (21.33%) to F6 (38.46%). These diabetic gerbils exhibited insulin resistance and leptin resistance as well as decreased adiponectin level in the serum. We also observed decreased expression of adiponectin and increased expression of leptin in the skeletal muscle, respectively.

Conclusions

These results indicate that we have primarily established a spontaneous diabetic gerbil line, and the diabetic phenotypes may have been accounted for by altered expression of leptin and adiponectin.

Blood coagulation and metabolic profiles in middle-aged male and female ob/ob mice

Obese and diabetic states in humans are associated with an increased incidence of thrombotic diseases caused by various coagulation abnormalities. Genetically obese ob/ob mice produce metabolic abnormalities similar to those associated with type 2 diabetes. However, little is known about their coagulation features or sex differences. The present study aimed to determine the effects of obese and diabetic complications on blood coagulation and vascular diseases by exploring correlations between blood coagulation and metabolic profiles in middle-aged male and female ob/ob mice. Plasma levels of plasminogen activator inhibitor 1 (PAI-1) were significantly increased, whereas those that of platelet factor-4 (PF-4) was slightly, but significantly increased in male and female ob/ob mice compared with lean counterparts. Prothrombin time (PT) was significantly shortened in female ob/ob mice and activated partial thrombin time (APTT) significantly differed between male and female ob/ob mice. Plasma levels of antithrombin (AT) were significantly increased in male and female ob/ob mice. None of the other coagulation and fibrinolytic factors examined significantly differed between ob/ob mice and lean counterparts. On the contrary, factors such as body weight and cholesterol levels significantly differed between ob/ob and lean mice, whereas glucose, fructosamine and insulin levels significantly differed only in one sex of each strain. These results provided fundamental information about blood coagulation and metabolic features for exploring the function of altered blood coagulation states in ob/ob mice.

A new in vivo model using a dorsal skinfold chamber to investigate microcirculation and angiogenesis in diabetic wounds

Introduction: Diabetes mellitus describes a dysregulation of glucose metabolism due to improper insulin secretion, reduced insulin efficacy or both. It is a well-known fact that diabetic patients are likely to suffer from impaired wound healing, as diabetes strongly affects tissue angiogenesis. Until now, no satisfying in vivo murine model has been established to analyze the dynamics of angiogenesis during diabetic wound healing. To help understand the pathophysiology of diabetes and its effect on angiogenesis, a novel in vivo murine model was established using the skinfold chamber in mice.

Materials and Methods: Mutant diabetic mice (db; BKS.Cg-m+/+Lepr^db/J), wildtype mice (dock7Lepr^db+/+m) and laboratory BALB/c mice were examined. They were kept in single cages with access to laboratory chow with an 12/12 hour day/night circle. Lesions of the panniculus muscle (Ø 2 mm) were created in the center of the transparent window chamber and the subsequent muscular wound healing was then observed for a period of 22 days. Important analytic parameters included vessel diameter, red blood cell velocity, vascular permeability, and leakage of muscle capillaries and post capillary venules. The key parameters were functional capillary density (FCD) and angiogenesis positive area (APA).

Results: We established a model which allows high resolution in vivo imaging of functional angiogenesis in diabetic wounds. As expected, db mice showed impaired wound closure (day 22) compared to wounds of BALB/c or WT mice (day 15). FCD was lower in diabetic mice compared to WT and BALB/c during the entire observation period. The dynamics of angiogenesis also decreased in db mice, as reflected by the lowest APA levels. Significant variations in the skin buildup were observed, with the greatest skin depth in db mice. Furthermore, in db mice, the dermis:subcutaneous ratio was highly shifted towards the subcutaneous layers as opposed to WT or BALB/c mice.

Conclusion: Using this new in vivo model of the skinfold chamber, it was possible to analyze and quantify microangiopathical changes which are essential for a better understanding of the pathophysiology of disturbed wound healing. Research in microcirculation is important to display perfusion in wounds versus healthy tissue. Using our model, we were able to compare wound healing in diabetic and healthy mice. We were also able to objectively analyze perfusion in wound edges and compare microcirculatory parameters. This model may be well suited to augment different therapeutic options.

Endothelial progenitor cells inhibit platelet function in a P-selectin-dependent manner

Background

The role of endothelial progenitor cells (EPCs) in vascular repair is related to their recruitment at the sites of injury and their interaction with different components of the circulatory system. We have previously shown that EPCs bind and inhibit platelet function and impair thrombus formation via prostacyclin secretion, but the role of EPC binding to platelet P-selectin in this process has not been fully characterized. In the present study, we assessed the impact of EPCs on thrombus formation and we addressed the implication of P-selectin in this process.

Methods

EPCs were generated from human peripheral blood mononuclear cells cultured on fibronectin in conditioned media. The impact of EPCs on platelet aggregation and thrombus formation was investigated in P-selectin deficient (P-sel^−/−) mice and their wild-type (WT) counterparts.

Results

EPCs significantly and dose-dependently impaired collagen-induced whole blood platelet aggregation in WT mice, whereas no effects were observed in P-sel^−/− mice. Moreover, in a ferric chloride-induced arterial thrombosis model, infusion of EPCs significantly reduced thrombus formation in WT, but not in P-sel^−/− mice. Furthermore, the relative mass of thrombi generated in EPC-treated P-sel^−/− mice were significantly larger than those in EPC-treated WT mice, and the number of EPCs recruited within the thrombi and along the arterial wall was reduced in P-sel^−/− mice as compared to WT mice.

Conclusion

This study shows that EPCs impair platelet aggregation and reduce thrombus formation via a cellular mechanism involving binding to platelet P-selectin. These findings add new insights into the role of EPC-platelet interactions in the regulation of thrombotic events during vascular repair.

Zucker Diabetic Fatty rats exhibit hypercoagulability and accelerated thrombus formation in the Arterio-Venous shunt model of thrombosis

INTRODUCTION

Diabetes is a significant risk factor for thrombosis. The present study aimed at assessing coagulability, platelet reactivity, and thrombogenicity of the diabetic female Zucker Diabetic Fatty (ZDF) rat model and its relevance in studying antithrombotic mechanisms.

MATERIALS AND METHODS

The basal coagulant state in ZDF rats was evaluated by clotting times, thromboelastography, and thrombin generation assay. A 14-day treatment with dapagliflozin in ZDF rats was pursued to investigate if glycemic control can improve coagulability. Thrombus formation in the Arterio-Venous (A-V) shunt model and the FeCl3-induced arterial thrombosis model was studied, with the antithrombotic effect of apixaban in the former model further investigated.

RESULTS

ZDF rats exhibited significantly shortened clotting times, enhanced thrombin generation, and decreased fibrinolysis at baseline. Effective glycemic control achieved with dapagliflozin did not improve any of these parameters. ZDF rats displayed accelerated thrombus formation and were amenable to apixaban treatment in the A-V shunt model albeit with less sensitivity than normal rats. ZDF rats exhibited less platelet aggregation in response to ADP, collagen and PAR-4, and attenuated thrombotic response in the FeCl3 model.

CONCLUSIONS

ZDF rats are at a chronic hypercoagulable and hypofibrinolytic state yet with compromised platelet reactivity. They display accelerated and attenuated thrombosis in the A-V shunt and FeCl3 model of thrombosis, respectively. Results shed new light on the pathophysiology of the ZDF rat model and illustrate its potential value in translational research on anticoagulant agents in diabetics. Caution needs to be exerted in utilizing this model in assessing antiplatelet mechanisms in diabetes-associated atherothrombosis.

Attenuation of sepsis-induced organ injury in mice by vitamin C

BACKGROUND

Multiple organ dysfunction syndrome (MODS) is the principal cause of death in patients with sepsis. Recent work supports the notion that parenteral vitamin C (VitC) is protective in sepsis through pleiotropic mechanisms. Whether suboptimal levels of circulating VitC increase susceptibility to sepsis-induced MODS is unknown.

MATERIALS AND METHODS

Unlike mice, humans lack the ability to synthesize VitC because of loss of L-gulono-γ-lactone oxidase (Gulo), the final enzyme in the biosynthesis of VitC. To examine whether physiological levels of VitC are required for defense against a catastrophic infection, we induced sepsis in VitC sufficient and VitC deficient Gulo(-/-) mice by intraperitoneal infusion of a fecal stem solution (FIP). Some VitC deficient Gulo(-/-) mice received a parenteral infusion of ascorbic acid (AscA, 200 mg/kg) 30 minutes after induction of FIP. We used molecular, histological, and biochemical analyses to assess for MODS as well as abnormalities in the coagulation system and circulating blood cells.

RESULTS

FIP produced injury to lungs, kidneys and liver (MODS) in VitC deficient Gulo(-/-) mice. MODS was not evident in FIP-exposed VitC sufficient Gulo(-/-) mice and attenuated in VitC deficient Gulo(-/-) mice infused with AscA. Septic VitC deficient Gulo(-/-) mice developed significant abnormalities in the coagulation system and circulating blood cells. These were attenuated by VitC sufficiency/infusion in septic Gulo(-/-) mice.

CONCLUSIONS

VitC deficient Gulo(-/-) mice were more susceptible to sepsis-induced MODS. VitC sufficiency or parenteral infusion of VitC, following induction of sepsis, normalized physiological functions that attenuated the development of MODS in sepsis.

Chemical composition of hepatic lipids mediates reperfusion injury of the macrosteatotic mouse liver through thromboxane A(2)

BACKGROUND & AIMS

Chemical composition of hepatic lipids is an evolving player in steatotic liver ischemia/reperfusion (I/R) injury. Thromboxane A(2) (TXA(2)) is a vasoactive pro-inflammatory lipid mediator derived from arachidonic acid (AA), an omega-6 fatty acid (Ω-6 FA). Reduced tolerance of the macrosteatotic liver to I/R may be related to increased TXA(2) synthesis due to the predominance of Ω-6 FAs.

METHODS

TXA(2) levels elicited by I/R in ob/ob and wild type mice were assessed by ELISA. Ob/ob mice were fed Ω-3 FAs enriched diet to reduce hepatic synthesis of AA and TXA(2) or treated with selective TXA(2) receptor blocker before I/R.

RESULTS

I/R triggered significantly higher hepatic TXA(2) production in ob/ob than wild type animals. Compared with ob/ob mice on regular diet, Ω-3 FAs supplementation markedly reduced hepatic AA levels before ischemia and consistently blunted hepatic TXA(2) synthesis after reperfusion. Sinusoidal perfusion and hepatocellular damage were significantly ameliorated despite downregulation of heme oxygenase-1. Hepatic transcript and protein levels of IL-1β and neutrophil recruitment were significantly diminished after reperfusion. Moreover, TXA(2) receptor blockage conferred similar protection without modification of the histological pattern of steatosis. A stronger protection was achieved in the steatotic compared with lean animals.

CONCLUSIONS

Enhanced I/R injury in the macrosteatotic liver is explained, at least partially, by TXA(2) mediated microcirculatory failure rather than size-related mechanical compression of the sinusoids by lipid droplets. TXA(2) blockage may be a simple strategy to include steatotic organs and overcome the shortage of donor organs for liver transplantation.

Microvascular responses to cardiovascular risk factors

Hypertension, hypercholesterolemia, diabetes, and obesity are among a growing list of conditions that have been designated as major risk factors for cardiovascular disease (CVD). While CVD risk factors are well known to enhance the development of atherosclerotic lesions in large arteries, there is also evidence that the structure and function of microscopic blood vessels can be profoundly altered by these conditions. The diverse responses of the microvasculature to CVD risk factors include oxidative stress, enhanced leukocyte- and platelet-endothelial cell adhesion, impaired endothelial barrier function, altered capillary proliferation, enhanced thrombosis, and vasomotor dysfunction. Emerging evidence indicates that a low-grade systemic inflammatory response that results from risk factor-induced cell activation and cell-cell interactions may underlie the phenotypic changes induced by risk factor exposure. A consequence of the altered microvascular phenotype and systemic inflammatory response is an enhanced vulnerability of tissues to the deleterious effects of secondary oxidative and inflammatory stresses, such as ischemia and reperfusion. Future efforts to develop therapies that prevent the harmful effects of risk factor-induced inflammation should focus on the microcirculation.

The mannose-binding lectin pathway is a significant contributor to reperfusion injury in the type 2 diabetic heart

The severity of ischaemic heart disease is markedly enhanced in type 2 diabetes. We recently reported that complement activation exacerbates I/R injury in the type 2 diabetic heart. The purpose of this study was to isolate and examine MBL pathway activation following I/R injury in the diabetic heart. ZLC and ZDF rats underwent 30 minutes of left coronary artery occlusion followed by 120 minutes of reperfusion. Two different groups of ZDF rats were treated with either FUT-175, a broad complement inhibitor, or P2D5, a monoclonal antibody raised against rat MBL-A. ZDF rats treated with FUT175 and P2D5 had significantly decreased myocardial infarct size, C3 deposition and neutrophil accumulation compared with untreated ZDF controls. Taken together, these findings indicate that the MBL pathway plays a key role in the severity of complement-mediated I/R injury in the type 2 diabetic heart.

Whole blood aggregation, coagulation, and markers of platelet activation in diet-induced diabetic C57BL/6J mice

AIMS

Type 2 diabetes in humans is associated with hypercoaguability; however, little is known about platelet function in mouse models of type 2 diabetes used to study this disorder. Therefore, the purpose of this study was to examine platelet aggregation, coagulation, and markers of platelet activation in a diet-induced mouse model of type 2 diabetes.

METHODS

Four week old, male, C57BL/6J mice were randomized to a standard chow or high fat (60% beef lard) diet for 4 months. To examine platelet function we measured ADP-induced whole blood aggregometry, whole blood coagulation by thromboelastography, tail bleeding times, platelet microparticle and platelet expression of p-selectin and platelet expression of CD61 by flow cytometry.

RESULTS

Diabetic mice exhibited less aggregation (p<0.05), less coagulation (p<0.01), prolonged tail bleeding times (n.s.), and lower agonist stimulated platelet CD61 expression (p<0.001) compared to non-diabetic mice. There was no difference in platelet microparticle and platelet p-selectin expression.

CONCLUSIONS

Diet-induced type 2 diabetic mouse do not demonstrate the hypercoagulability and platelet activation typically observed in humans with this disorder. More studies are warranted to further explore platelet function in this mouse model; to determine their applicability for studying these alterations in type 2 diabetes.