Heparin and related substances for preventing diabetic kidney disease

Heparin impairs skeletal muscle glucose uptake by inhibiting insulin binding to insulin receptor

Aim

Heparin, a widely used antithrombotic drug has many other anticoagulant-independent physiological functions. Here, we elucidate a novel role of heparin in glucose homeostasis, suggesting an approach for developing heparin-targeted therapies for diabetes.

Methods

For serum heparin levels and correlation analysis, 122 volunteer's plasma, DIO (4 weeks HFD) and db/db mice serums were collected and used for spectrophotometric determination. OGTT, ITT, 2-NBDG uptake and muscle GLUT4 immunofluorescence were detected in chronic intraperitoneal injection of heparin or heparinase (16 days) and muscle-specific loss-of-function mice. In 293T cells, the binding of insulin to its receptor was detected by fluorescence resonance energy transfer (FRET), Myc-GLUT4-mCherry plasmid was used in GLUT4 translocation. In vitro, C2C12 cells as mouse myoblast cells were further verified the effects of heparin on glucose homeostasis through 2-NBDG uptake, Western blot and co-immunoprecipitation.

Results

Serum concentrations of heparin are positively associated with blood glucose levels in humans and are significantly increased in diet-induced and db/db obesity mouse models. Consistently, a chronic intraperitoneal injection of heparin results in hyperglycaemia, glucose intolerance and insulin resistance. These effects are independent of heparin's anticoagulant function and associated with decreases in glucose uptake and translocation of glucose transporter type 4 (GLUT4) in skeletal muscle. By using a muscle-specific loss-of-function mouse model, we further demonstrated that muscle GLUT4 is required for the detrimental effects of heparin on glucose homeostasis.

Conclusions

Heparin reduced insulin binding to its receptor by interacting with insulin and inhibited insulin-mediated activation of the PI3K/Akt signalling pathway in skeletal muscle, which leads to impaired glucose uptake and hyperglycaemia.

Lipopolysaccharide-binding protein (LBP) can reverse the amyloid state of fibrin seen or induced in Parkinson's disease

The thrombin-induced polymerisation of fibrinogen to form fibrin is well established as a late stage of blood clotting. It is known that Parkinson's Disease (PD) is accompanied by dysregulation in blood clotting, but it is less widely known as a coagulopathy. In recent work, we showed that the presence of tiny amounts of bacterial lipopolysaccharide (LPS) in healthy individuals could cause clots to adopt an amyloid form, and this could be observed via scanning electron microscopy (SEM) or via the fluorescence of thioflavin-T. This could be prevented by the prior addition of lipopolysaccharide-binding protein (LBP). We had also observed by SEM this unusual clotting in the blood of patients with Parkinson's Disease. We hypothesised, and here show, that this too can be prevented by LBP in the context of PD. This adds further evidence implicating inflammatory microbial cell wall products as an accompaniment to the disease, and may be part of its aetiology. This may lead to novel treatment strategies in PD designed to target microbes and their products.

Protease-activated receptor-1 deficiency protects against streptozotocin-induced diabetic nephropathy in mice

Endogenously administered activated protein C ameliorates diabetic nephropathy (DN) in a protease-activated receptor-1 (PAR-1)-dependent manner, suggesting that PAR-1 activation limits the progression of DN. Activation of PAR-1 in fibroblast-like cells, however, induces proliferation and extracellular matrix production, thereby driving fibrotic disease. Considering the key role of mesangial proliferation and extracellular matrix production during DN, PAR-1 may in fact potentiate diabetes-induced kidney injury. To determine the net effect of PAR-1 in DN, streptozotocin-induced DN was studied in wild type and PAR-1 deficient mice. Subsequent mechanistic insight was obtained by assessing profibrotic responses of mesangial and tubular epithelial cells in vitro, following PAR-1 stimulation and inhibition. Despite having similar glucose levels, PAR-1 deficient mice developed less kidney damage after induction of diabetes, as evidenced by diminished proteinuria, plasma cystatin C levels, expansion of the mesangial area, and tubular atrophy. In vitro, PAR-1 signaling in mesangial cells led to increased proliferation and expression of matrix proteins fibronectin and collagen IV. Conversely, a reduction in both proliferation and fibronectin deposition was observed in diabetic PAR-1 deficient mice. Overall, we show that PAR-1 plays an important role in the development of DN and PAR-1 might therefore be an attractive therapeutic target to pursue in DN.

Elevated expression levels of serum insulin-like growth factor-1, tumor necrosis factor-α and vascular endothelial growth factor 165 might exacerbate type 2 diabetic nephropathy

AIMS/INTRODUCTION

The present study aimed to determine the associations between expressions of insulin-like growth factor-1 (IGF-1), tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor 165 (VEGF₁₆₅ ) in serum, and occurrence and development of type 2 diabetic nephropathy (DN).

MATERIALS AND METHODS

A total of 108 patients diagnosed as DN were randomly selected, including 50 patients in the microalbuminuria group, 44 patients in the macroalbuminuria group and 14 patients in the renal insufficiency group. Meanwhile, 97 healthy people were collected as a normal control group. Urinary albumin (UALB) and urine creatinine (Cr) of all participants were measured for 24 h, with their ratio (UALB/Cr) being calculated. Enzyme-linked immunosorbent assay was used to detect the serum concentrations of IGF-1, TNF-α and VEGF₁₆₅ .

RESULTS

The expressions of serum IGF-1, TNF-α and VEGF₁₆₅ in the type 2 DN patients were significantly higher than those in the control group (all P < 0.05). The expressions of serum IGF-1, TNF-α and VEGF₁₆₅ in the type 2 DN patients were positively correlated with UALB/Cr (all P < 0.05). As type 2 DN worsened, the expressions of serum IGF-1, TNF-α and VEGF₁₆₅ increased, and type 2 DN severity had positive correlations with serum IGF-1, TNF-α and VEGF₁₆₅ concentrations (all P < 0.05). There was a positive association between IGF-1 and TNF-α, IGF-1 and VEGF₁₆₅ , and TNF-α and VEGF₁₆₅ (all P < 0.05). Logistic regression analysis showed that IGF-1 and VEGF₁₆₅ were associated with the progression of DN (both P < 0.05).

CONCLUSIONS

Elevated expression levels of serum IGF-1, TNF-α and VEGF₁₆₅ might exacerbate type 2 DN.

Management of anemia in patients with diabetic kidney disease: A consensus statement

This consensus statement focuses on the window of opportunity, which exists while treating patients with diabetic kidney disease and anemia.

The emerging role of coagulation proteases in kidney disease

A role of coagulation proteases in kidney disease beyond their function in normal haemostasis and thrombosis has long been suspected, and studies performed in the past 15 years have provided novel insights into the mechanisms involved. The expression of protease-activated receptors (PARs) in renal cells provides a molecular link between coagulation proteases and renal cell function and revitalizes research evaluating the role of haemostasis regulators in renal disease. Renal cell-specific expression and activity of coagulation proteases, their regulators and their receptors are dynamically altered during disease processes. Furthermore, renal inflammation and tissue remodelling are not only associated, but are causally linked with altered coagulation activation and protease-dependent signalling. Intriguingly, coagulation proteases signal through more than one receptor or induce formation of receptor complexes in a cell-specific manner, emphasizing context specificity. Understanding these cell-specific signalosomes and their regulation in kidney disease is crucial to unravelling the pathophysiological relevance of coagulation regulators in renal disease. In addition, the clinical availability of small molecule targeted anticoagulants as well as the development of PAR antagonists increases the need for in-depth knowledge of the mechanisms through which coagulation proteases might regulate renal physiology.