Ghrelin Improves Glucolipotoxicity-Induced Pancreatic ß-Cellular Dysfunction and Apoptosis by Inhibiting Endoplasmic Reticulum Stress-Induced IRE1/JNK Pathway.

BACKGROUND: Glucose and fatty acid overload-induced glucolipid toxicity of pancreatic ß-cells is associated with the development of diabetes. Endoplasmic reticulum stress (ERS) plays an essential role in this process. Ghrelin, a peptide secreted by the pancreas, negatively correlates with oxidative stress. The study aimed to investigate ghrelin's role in glycolipid-induced ß-cell dysfunction and its possible mechanism. METHODS: Mouse insulinoma ß-cell, NIT-1 cells, were stimulated with high fat and high glucose to induce glucolipid toxicity. High fat and high glucose-induced NIT-1 cells were treated with acylated ghrelin (AG) or [d-Lys3]-growth hormone releasing peptide (GHRP)-6. Flow cytometry and Cell Counting Kit-8 (CCK-8) assay were performed to assess apoptosis and cell viability. The protein expression related to apoptosis, inositol-requiring kinase 1 (IRE1)/c-Jun N-terminal kinase (JNK) signaling, and ERS were investigated using western blot. Enzyme-linked immunosorbent assay (ELISA) was adopted to examine insulin's synthesis and secretion levels. RESULTS: Ghrelin treatment improved cell viability while inhibiting cell glucolipotoxicity-induced NIT-1 cell apoptosis. Ghrelin can promote the synthesis and secretion of insulin in NIT-1 cells. Mechanistically, ghrelin attenuates ERS and inhibits the IRE1/JNK signaling pathway in NIT-1 cells induced by glucolipotoxicity. CONCLUSION: Ghrelin improves ß-cellular dysfunction induced by glucolipotoxicity by inhibiting the IRE1/JNK pathway induced by ERS. It could be an effective treatment for ß-cellular dysfunction.

Involvement of RAGE, MAPK and NF-κB pathways in AGEs-induced MMP-9 activation in HaCaT keratinocytes.

Advanced glycation end products (AGEs) exert divergent effects on the pathogenesis of diabetes complications. Excessive expression of matrix metalloproteinases-9 (MMP-9) is deleterious to the cutaneous wound-healing process in the context of diabetes. However, the effect of AGEs on MMP-9 induction in skin cells and the exact molecular mechanisms involved are still poorly understood. In this study, we investigated the effect of AGEs on the production of MMP-9 in HaCaT keratinocytes and characterized the signal transduction pathways activated by AGEs that are involved in MMP-9 regulation. We showed that AGE-BSA increased MMP-9 expression in HaCaT cells at both the protein and mRNA levels. The stimulatory effect of AGE-BSA on MMP-9 was attenuated by inhibitors of extracellular-signal-regulated kinase (ERK1/2, U0126), p38 mitogen-activated protein kinase (MAPK, SB203580) and NF-κB, but not c-Jun N-terminal kinase. Furthermore, receptor for advanced glycation end products (RAGE) was expressed in keratinocytes, and incubation with AGE-BSA resulted in a significant upregulation of RAGE expression in a dose-dependent manner. Silencing of the RAGE gene prevented AGE-BSA-induced MMP-9 activation and the phosphorylation of ERK1/2 and p38 MAPK. We also observed the involvement of NF-κB in AGE-BSA-induced MMP-9 activation, which was not blocked by U0126 and SB203580. These results suggest that AGEs may play an important role in the impairment of diabetic wound healing by upregulating MMP-9 expression in keratinocytes via the RAGE, ERK1/2 and p38 MAPK pathways; activation of NF-κB is also involved in this process. These pathways may represent potential targets for drug interventions to improve diabetic wound healing, a process in which MMP-9 plays a critical role.

[Effects of angiotensin II type 1 receptor blocker on triglyceride metabolism in the liver: experiment with Zucker fatty rats].

OBJECTIVE: To investigate the effects of angiotensin receptor blocker (ARB) on triglyceride (TG) medoxomil metabolism and mechanism thereof. METHODS: Zucker fatty (ZF) rats and Zucker lean (ZL) rats were fed with water containing 0.01% olmesartan , a highly specific ARB for 4 weeks. Frequently sampled intravenous glucose tolerance test was conducted to calculate the area under the glucose (AUCG), insulin sensitivity index (SI), glucose effectiveness (SG), Blood glucose, TC, TG, nonesterified fatty acid (NEFA), and HDL-C were measured with standard assay kit. Triton WR-1339 technique was used to detect the TG secretion rate (TGSR). After TGSR and FS-IVGTT the levers were collected. The total cholesterol (TC) of the liver was detected, and Sudan IV staining was used to detect the triglyceride in the liver. Enzymatic method was used to measure the TG and TC in the liver extract. RESULTS: The blood pressure of both groups was lowered in both strains to the same extent after olmesartan taking. The SI value of the ZF rats was (0.31 +/- 0.22) microU x ml(-1) x min(-1) x 10(-4) significantly lower than that of the ZL rats (3.54 +/- 0.30) microU x ml(-1) x min(-1) x 10(-4), P < 0.01). Bergman's minimal model showed that the SG value of the ZF rats was (1.35 +/- 0.51) min(-1) x 10(-2), significantly lower than that of the ZL rats (3.40 +/- 0.14 min(-1) x 10(-2), P < 0.01). The plasma glucose levels of the ZF rats was (11.4 +/- 2.6) mmol/L, significantly higher than that of the L rats [(9.2 +/- 0.6) mmol/L, P < 0.01]. Olmesartan treatment substantially elevated both the baseline SI and SG levels of the ZF rats. The TG of the ZF rats was 6 times as high as that of the ZL rats. The plasma NEFA level after olmesartan treatment of the ZF rats was Olmesartan treatment, significantly lower than that before treatment [(2.70 +/- 0.69) mEq/L, P < 0.01], however, the plasma TG level of the ZF rats after the treatment was not significantly different from that before treatment (P > 0.05). The TGSR rate of the ZF rats was almost 6 times that of the ZL rats. Olmesartan treatment lowered the TG overproduction by half (0.56 +/- 0.08) mg x min(-1) x 100 g(-1) BW vs (0.30 +/- 0.07) mg x min(-1) x 100 g(-1) BW, (P < 0.01). The liver TG content of the ZF rats was 10 times that of the ZL rats. Olmesartan treatment lowered the liver TG content from (22.7 +/- 4.2) mg/g to (12.8 +/- 1.7) mg/g (P < 0.01) without affecting the cholesterol content. Pathology showed that the fatty liver developed in the ZF rats was significantly ameliorated by olmesartan treatment. Olmesartan treatment had no significant effect on TG metabolism or insulin sensitivity in the ZL rats. CONCLUSION: ARB improves the overproduction and accumulation of TG in the liver associated with insulin resistance, and does so through mechanisms independent of its hypotensive action.

The effects of protein intake on albuminuria in different estimated glomerular filtration rate: A population-based study.

BACKGROUND: Chronic kidney disease (CKD) is a serious condition associated with early mortality, decreased quality of life, and increased health-care expenditures. METHODS: Data from the National Health and Nutrition Examination Survey (NHANES) collected from 1999 to 2012 were used. Subjects were divided into 4 estimated glomerular filtration rate (eGFR) categories: stage 1: eGFR≥90mL/min/1.73m2, stage 2: eGFR 60-89, stage 3: eGFR 30-59, and stage 4/5: eGFR<30, and 3 age strata (<45y, 45-64, 65+). Associations between protein intake and albuminuria were determined. RESULTS: A total of 45,259 subjects were included. Despite decreasing protein intake, there was a significant increase in the prevalence of albuminuria with decreasing levels of eGFR. Multivariable analysis showed that albuminuria was associated with daily protein intake in patients ≥65years old with stage 1 disease, and that diabetes was associated with albuminuria in patients ≥65years old with stage 2 and 3 diseases. Overall, albuminuria in patients with stage 1 disease was associated with hours of sitting per day and blood glucose level. CONCLUSION: Albuminuria was associated with daily protein intake in patients of 45-64years old with stage 1 CKD disease, and was associated with hours of sitting per day and blood glucose level. These data further support the importance of lifestyle changes in the management of CKD, especially in patients with early-stage disease.

Serum uric acid is associated with incident chronic kidney disease in middle-aged populations: a meta-analysis of 15 cohort studies.

BACKGROUND: Mounting evidence indicates that elevated serum uric acid may increase the incidence of chronic kidney disease (CKD). Our goal was to systematically evaluate longitudinal cohort studies for the association of serum uric acid levels and incident CKD. METHODS: We searched electronic databases and the reference lists of relevant articles. The primary outcome was incident CKD, which was defined as an eGFR less than 60 mL/min/1.73 m2 at the follow-up examination. Study-specific risk estimates were combined using random-effects models. The included studies were stratified into subgroups, and meta-regression analyses were performed. RESULTS: Fifteen unique cohorts with a total of 99,205 individuals and 3,492 incident CKD cases were included. The relative risk of CKD was 1.22 (95% CI 1.16-1.28, I2 = 65.9%) per 1 mg/dL serum uric level increment. This positive association was consistently observed in subgroups stratified according to most of the study-level characteristics. The observed positive association was more pronounced among group with a mean age <60 years (RR 1.26, 95% CI 1.21-1.31), and low-level heterogeneity was observed in the findings for this age group (I2 = 46.4%, P = 0.022). However, no association was observed among studies with a mean age≥60 years (RR 1.04, 95% CI 0.96-1.13), and no evidence of heterogeneity was evident among the studies (I2 = 0%, P = 0.409). This mean age-related difference in the association between serum uric acid levels and CKD was significant (P = 0.004). The sensitivity analysis results were consistent when the analyses were restricted to studies that controlled for proteinuria and metabolic syndrome. CONCLUSIONS: Our meta-analysis demonstrated a positive association between serum uric acid levels and risk of CKD in middle-aged patients independent of established metabolic risk factors. Future randomized, high-quality clinical trials are warranted to determine whether lowering uric acid levels is beneficial in CKD.

Hemoglobin A(1c) proportion, mortality rate, and risk factors for death in diabetic patients with severe hypoglycemia: a multicenter retrospective survey over ten years.

OBJECTIVE: To investigate the HbA(1c) proportion and mortality rate across diabetic patients with severe hypoglycemia and the risk factors for death. METHODS: All the diabetic patients with severe hypoglycemia were divided into HbA(1c)<6.5% group and HbA(1c)≥6.5% group. The proportion of HbA(1c), mortality rate and the risk factors for death were analyzed. Common causes for severe hypoglycemia were also analyzed. RESULTS: The percentages of HbA(1c) in the HbA(1c)<6.5% and HbA(1c)≥6.5% groups were 51.2% and 48.8%, respectively. The mortality rates were not significantly different between the 2 groups (5.3% vs. 5.1%, χ(2)=0.01, p=0.17). Binary logistic regression analysis revealed that in both groups, creatinine, aspartate aminotransferase, and uric acid levels were the risk factors for death. In the HbA(1c)<6.5% and HbA(1c)≥6.5% groups, 65.0% and 64.2% showed common causes of severe hypoglycemia, respectively. CONCLUSIONS: With respect to severe hypoglycemia, equal attention should be paid to patients with an HbA(1c) level of ≥6.5% and those with an HbA(1c) level of <6.5%. The mortality rate is approximately 5% in severe hypoglycemia no matter how the HbA(1c) level is. Creatinine, aspartate aminotransferase, and uric acid are the main risk factors in both groups. Two-thirds of severe hypoglycemia cases could be prevented.