Suramin prevents the development of diabetic kidney disease by inhibiting NLRP3 inflammasome activation in KK-Ay mice

Aims/Introduction Nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasomes produce IL-18 upon being activated by various stimuli via the P2 receptors. Previously, we showed that serum and urine IL-18 levels are positively associated with albuminuria in patients with type 2 diabetes, indicating the involvement of inflammasome activation in the pathogenesis of diabetic kidney disease (DKD). In the present study, we investigated whether the administration of suramin, a nonselective antagonist of the P2 receptors, protects diabetic KK.Cg-A(y)/TaJcl (KK-Ay) mice against DKD progression. Materials and Methods Suramin or saline was administered i.p. to KK-Ay and C57BL/6J mice once every 2 weeks for a period of 8 weeks. Mouse mesangial cells (MMCs) were stimulated with ATP in the presence or absence of suramin. Results Suramin treatment significantly suppressed the increase in the urinary albumin-to-creatinine ratio, glomerular hypertrophy, mesangial matrix expansion, and glomerular fibrosis in KK-Ay mice. Suramin also suppressed the upregulation of NLRP3 inflammasome-related genes and proteins in the renal cortex of KK-Ay mice. P2X4 and P2X7 receptors were significantly upregulated in the isolated glomeruli of KK-Ay mice and mainly distributed in the glomerular mesangial cells of KK-Ay mice. Although neither ATP nor suramin affected NLRP3 expression in MMCs, suramin inhibited ATP-induced NLRP3 complex formation and the downstream expression of caspase-1 and IL-18 in MMCs. Conclusions These results suggest that the NLRP3 inflammasome is activated in a diabetic kidney and that inhibition of the NLRP3 inflammasome with suramin protects against the progression of early stage DKD

Phenotypic change of macrophages in the progression of diabetic nephropathy; sialoadhesin-positive activated macrophages are increased in diabetic kidney

Inflammatory process is involved in pathogenesis of diabetic nephropathy, although the activation and phenotypic change of macrophages in diabetic kidney has remained unclear. Sialoadhesin is a macrophage adhesion molecule containing 17 extracellular immunoglobulin-like domains, and is an I-type lectin which binds to sialic acid ligands expressed on hematopoietic cells. The aim of this study is to clarify the activation and phenotypic change of macrophages in the progression of diabetic nephropathy. We examined the expression of surface markers for pan-macrophages, resident macrophages, sialoadhesin, major histocompatibility complex class II and alpha-smooth muscle actin in the glomeruli of diabetic rats using immunohistochemistry at 0, 1, 4, 12, and 24 weeks after induction of diabetes by streptozotocin. Expression of type IV collagen and the change of mesangial matrix area were also measured. The mechanism for up-regulated expression of sialoadhesin on macrophages was evaluated in vitro. The number of macrophages was increased in diabetic glomeruli at 1 month after induction of diabetes and the increased number was maintained until 6 months. On the other hand, sialoadhesin-positive macrophages were increased during the late stage of diabetes concomitantly with the increase of alpha-smooth muscle actin-positive mesangial cells, mesangial matrix area and type IV collagen. Gene expression of sialoadhesin was induced by stimulation with interleukin (IL)-1 beta and tumor necrosis factor-alpha but not with IL-4, transforming growth factor-beta and high glucose in cultured human macrophages. The present findings suggest that sialoadhesin-positive macrophages may contribute to the progression of diabetic nephropathy

Involvement of MAPKs in ICAM-1 Expression in Glomerular Endothelial Cells in Diabetic Nephropathy

Inflammatory processes are involved in the pathogenesis of diabetic nephropathy. The aim of this study was to clarify the role of mitogen-activated protein kinase (MAPK) pathways for induction of intercellular adhesion molecule-1 (ICAM-1) expression in glomerular endothelial cells under diabetic conditions. We examined the expression of ICAM-1 in the kidneys of experimental diabetic rats. Human glomerular endothelial cells (GE cells) were exposed to normal glucose concentration, high glucose concentration (HG), or high mannitol concentration (HM), and then the expression of the ICAM-1 protein and the phosphorylation of the 3 subfamilies of mitogen-activated protein kinase (MAPK) were determined using Western blot analysis. Next, to evaluate the involvement of MAPKs in HG- or HM-induced ICAM-1 expression, we preincubated GE cells with the inhibitors for ERK, p38 or JNK 1h prior to the application of glucose or mannitol. Expression of ICAM-1 was increased in the glomeruli of diabetic rats. Both HG and HM induced ICAM-1 expression and phosphorylation of ERK1/2, p38 and JNK in GE cells. Expression of ICAM-1 was significantly attenuated by inhibitors of ERK, p38 and JNK. We conclude that activation of ERK1/2, p38 and JNK cascades may be involved in ICAM-1 expression in glomerular endothelial cells under diabetic conditions

Prevalence of albuminuria and renal dysfunction, and related clinical factors in Japanese patients with diabetes: The Japan Diabetes Complication and its Prevention prospective study 5

Aims/Introduction To clarify the prevalence of albuminuria and renal dysfunction, and related factors in Japanese patients with diabetes, we analyzed the baseline data of the Japan Diabetes Complication and its Prevention prospective study. Materials and Methods We used the data of 355 patients with type 1 diabetes and 5,194 patients with type 2 diabetes to evaluate the prevalence of albuminuria and renal dysfunction, and related factors. A binomial logistic regression analysis was used to investigate independent contributing factors for estimated glomerular filtration rate Results The prevalence of microalbuminuria and macroalbuminuria was 15.2% (54/355) and 3.1% (11/355) in type 1 diabetes patients, and 25.0% (1,298/5,194) and 5.1% (265/5,194) in type 2 diabetes patients, respectively. The proportion of renal dysfunction (estimated glomerular filtration rate Conclusions We showed the recent prevalence of albuminuria and renal dysfunction, and related factors in Japanese type 1 and type 2 diabetes patients using the baseline data of the Japan Diabetes Complication and its Prevention prospective study. The current results suggest that renal disease in patients with type 2 diabetes is heterogeneous, and different mechanisms might be involved in albuminuria and deterioration of renal function

Factors Associated with Remission and/or Regression of Microalbuminuria in Type 2 Diabetes Mellitus

The aim of this study was to clarify the factors associated with the remission and/or regression of microalbuminuria in Japanese patients with type 2 diabetes mellitus. We retrospectively analyzed the data of 130 patients with type 2 diabetes mellitus with microalbuminuria for 2-6 years (3.39±1.31 years). Remission was defined as improving from microalbuminuria to normoalbuminuria using the albumin/creatinine ratio (ACR), and regression of microalbuminuria was defined as a decrease in ACR of 50% or more from baseline. Progression of microalbuminuria was defined as progressing from microalbuminuria to overt proteinuria during the follow-up period. Among 130 patients with type 2 diabetes mellitus with microalbuminuria, 57 and 13 patients were defined as having remission and regression, respectively, while 26 patients progressed to overt proteinuria. Sex (female), higher HDL cholesterol and lower HbA1c were determinant factors associated with remission/regression of microalbuminuria by logistic regression analysis. Lower systolic blood pressure (SBP) was also correlated with remission/regression, but not at a significant level. These results suggest that proper control of blood glucose, BP and lipid profiles may be associated with remission and/or regression of type 2 diabetes mellitus with microalbuminuria in clinical practice

Estimation of Time-Course Core Temperature and Water Loss in Realistic Adult and Child Models with Urban Micrometeorology Prediction

Ambient conditions may change rapidly and notably over time in urban areas. Conventional indices, such as the heat index and wet bulb globe temperature, are useful only in stationary ambient conditions. To estimate the risks of heat-related illness, human thermophysiological responses should be followed for ambient conditions in the time domain. We develop a computational method for estimating the time course of core temperature and water loss by combining micrometeorology and human thermal response. We firstly utilize an urban micrometeorology prediction to reproduce the environment surrounding walkers. The temperature elevations and sweating in a standard adult and child are then estimated for meteorological conditions. With the integrated computational method, we estimate the body temperature and thermophysiological responses for an adult and child walking along a street with two routes (sunny and shaded) in Tokyo on 7 August 2015. The difference in the core temperature elevation in the adult between the two routes was 0.11 °C, suggesting the necessity for a micrometeorology simulation. The differences in the computed body core temperatures and water loss of the adult and child were notable, and were mainly characterized by the surface area-to-mass ratio. The computational techniques will be useful for the selection of actions to manage the risk of heat-related illness and for thermal comfort