Temporal metabolic and transcriptomic characteristics crossing islets and liver reveal dynamic pathophysiology in diet-induced diabetes.

To investigate the molecular mechanisms underlying islet dysfunction and insulin resistance in diet-induced diabetes, we conducted temporal RNA sequencing of tissues responsible for insulin secretion (islets) and action (liver) every 4 weeks in mice on high-fat (HFD) or chow diet for 24 weeks, linking to longitudinal profile of metabolic characteristics. The diverse responses of α, ß, and δ cells to glucose and palmitate indicated HFD-induced dynamic deterioration of islet function from dysregulation to failure. Insulin resistance developed with variable time course in different tissues. Weighted gene co-expression network analysis and Ingenuity Pathway Analysis implicated islets and liver jointly programmed ß-cell compensatory adaption via cell proliferation at early phase and irreversible islet dysfunction by inappropriate immune response at later stage, and identified interconnected molecules including growth differentiation factor 15. Frequencies of T cell subpopulation showed an early decrement in Tregs followed by increases in Th1 and Th17 cells during progression to diabetes.

Elevation of serum uric acid and incidence of type 2 diabetes: A systematic review and meta-analysis.

OBJECTIVE: Recently, several cohort studies suggested a positive relationship between serum uric acid (SUA) and type 2 diabetes mellitus (T2DM), which is inconsistent with the results of functional research. Our aim was to further evaluate this correlation by conducting a systematic review. METHODS: Computerized literature searches of the Medline database, EMBASE database, and PubMed were used to evaluate the relationship between SUA and T2DM in cohort studies. Cochran's Q and I2 statistics were used to evaluate heterogeneity among studies, and pooled relative risk (RR) and odds ratio (OR) with 95% confidence intervals (CIs) were calculated using random-effects and fixed-effects models. The summary RR and OR of per 1 mg/ml-SUA increase were calculated separately because of their different epidemiological implications and calculation methods. Additionally, sensitivity analysis, stratified analysis, meta-regression, and multiple meta-regression were applied to investigate the heterogeneity among studies. RESULTS: A total of 970 articles were retrieved from the searches. Sixteen publications of cohort studies containing 61,714 participants were included. The pooled RR was 1.131 (95% CI: 1.084-1.179) with significant heterogeneity among studies (I2  = 51.9%, P = 0.018). Adjusted RR to evaluate the stability of the relationship between SUA and T2DM in the sensitivity analysis was similar (RR = 1.140, 95% CI: 1.087-1.197), with statistically significant heterogeneity (I2  = 54.5%, P = 0.015). Stratified analysis and meta-regression showed that the positive relationship remained irrespective of age, sex, region, and adjustment for confounding factors including body mass index, fasting blood glucose, systolic blood pressure, diastolic blood pressure, alcohol consumption, smoking, blood cholesterol, waist circumference, fatty liver, and drugs affecting SUA. CONCLUSION: Although SUA is independently associated with development of T2DM, insulin resistance increased as the baseline SUA concentration increased; thus, the correlation between SUA and T2DM requires further evaluation and the baseline insulin resistance status should also be considered.

FTO Inhibits Insulin Secretion and Promotes NF-κB Activation through Positively Regulating ROS Production in Pancreatic ß cells.

FTO (Fat mass and obesity-associated) is associated with increased risk of obesity and type 2 diabetes incurrence. Pancreas islet ß cells dysfunction and insulin resistance are major causes of type 2 diabetes. However, whether FTO plays an important functional role in pancreatic ß cells as well as the related molecular mechanism is still unclear. In the present study, the tissue expression profile of FTO was firstly determined using quantitative PCR and western blot. FTO is widely expressed in various tissues and presented with relative high expression in pancreas tissue, especially in endocrine pancreas. FTO overexpression in MIN6 cells achieved by lentivirus delivery significantly inhibits insulin secretion in the presence of glucose stimulus as well as KCl. FTO silence has no effect on insulin secretion of MIN6 cells. However, FTO overexpression doesn't affect the transcription of insulin gene. Furthermore, reactive oxygen species (ROS) production and NF-κB activation are significantly promoted by FTO overexpression. Inhibition of intracellular ROS production by N-acetyl-L-cysteine (NAC) can alleviate NF-κB activation and restore the insulin secretion mediated by FTO overexpression. A whole transcript-microarray is employed to analyze the differential gene expression mediated by FTO overexpression. The genes which are modulated by FTO are involved in many important biological pathways such as G-protein coupled receptor signaling and NF-κB signaling. Therefore, our study indicates that FTO may contribute to pancreas islet ß cells dysfunction and the inhibition of FTO activity is a potential target for the treatment of diabetes.

[Homing of CFSE-labeled antigen-specific CD4(+)CD25(+) regulatory T cells in islets transplantation].

AIM: To observe the distribution and proliferation of the antigen-specific CD4(+)CD25(+) regulatory T (Treg ) cells and investigate the potential mechanism of antigen-specific CD4(+)CD25(+) regulatory T cells on the suppression of rejection for allogenetic islet transplantation in vivo. METHODS: Antigen-specific CD4(+)CD25(+) Treg cells were generated by the addition of multiple intravenous injections of ICR mice splenocytes in vivo. After labeled by CFSE, 8x10(5) antigen-specific Treg cells were injected via tail vein with islets transplantation. Homing and distribution of antigen-specific CD4(+)CD25(+) Treg cells were investigated by flow cytometric analysis and immunofluorescence. RESULTS: In vivo, the mean survival time of recipients with islets and antigen-specific CD4(+)CD25(+) Treg cells were (34.57+/-17.15) days, whereas transplanted islets without Treg treatment survived (10.6+/-1.82) days in control mice. The transferred antigen-specific CD4(+)CD25(+) Treg cells were mainly resident in pancreatic node and mesenteric node. CONCLUSION: Allogeneic antigen-specific CD4(+)CD25(+) Treg cells prolong islet graft survival, and draining lymphoid tissue play a key role in the immune response.

Effect of taurine-conjugated ursodeoxycholic acid on endoplasmic reticulum stress and apoptosis induced by advanced glycation end products in cultured mouse podocytes.

BACKGROUND: Activations of death receptors and mitochondrial damage are well-described common apoptotic pathways. Recently, a novel pathway via endoplasmic reticulum (ER) stress has been reported. METHODS: We assessed the role of tauroursodeoxycholic acid (TUDCA) in inhibition of ER stress and its protective effect on advanced glycation end products (AGEs)-induced apoptosis in murine podocytes. Podocytes were incubated with increasing doses of AGEs for variable time periods. Apoptosis was quantitatively determined by flow cytometry detecting propidium iodide expression and annexin V binding simultaneously. Level of glucose-regulated protein 78 (ER stress marker) expression was determined by Western blot. Intracellular calcium concentration ([Ca(2+)](i)) was recorded by a laser confocal microscope and the Ca(2+) indicator Fluo-3 labeling. RESULTS: AGEs induced podocyte apoptosis and increased the expression of glucose-regulated protein 78 in a dose- and time-dependent manner as compared with bovine serum albumin. These changes were accompanied by a rapid rise in [Ca(2+)](i) of podocytes. TUDCA was capable of abolishing AGEs-induced expression of glucose-regulated protein 78 and subsequently inhibited apoptosis in a dose-dependent manner. CONCLUSION: We propose that ER stress plays an important role in AGEs-induced apoptosis and that TUDCA prevents apoptosis by blocking an ER stress-mediated apoptotic pathway. This novel mechanism of TUDCA action suggests new intervention methods for AGEs-induced apoptosis of mouse podocytes in diabetic nephropathy.

Chronic activation of neutral ceramidase protects beta-cells against cytokine-induced apoptosis.

AIM: To investigate the activity and expression of neutral ceramidase (N-CDase) in the insulin-secreting cell line INS-1 and its role in the cellular response to cytokines. METHODS: HPLC, Western blotting, and quantitative real-time PCR were performed to detect the activity and expression of N-CDase in INS-1 cells treated with a cytokine mixture (5 ng/mL interleukin-1beta, 10 ng/mL TNF-alpha, and 50 ng/mL interferon-gamma). The expression and activity of N-CDase in the INS-1 cells were specifically inhibited using N-CDase-siRNA transfection. Annexin V-fluorescein- isothiocyanate/propidium iodide flow cytometry was used to assess apoptosis in the INS-1 cells. RESULTS: The INS-1 cells exhibited some basal N-CDase activity, and cytokines induced a time-dependent delay in the activation of NCDase. As a result, the activation of N-CDase was first detectable at 8 h after stimulation. It peaked at 16 h and remained elevated at 24 h. Cytokines also upregulated the mRNA and protein expression of N-CDase in the INS-1 cells. Furthermore, when N-CDase activity was inhibited by RNA interference, cytokine-induced apoptosis in the INS-1 cells was markedly increased. CONCLUSION: The N-CDase pathway is active in INS-1 cells, and the chronic activation of N-CDase is involved in the pathological response of beta-cells to cytokines, potentially providing protection against cytokine toxicity.

Reversal of hyperglycemia in diabetic rats by portal vein transplantation of islet-like cells generated from bone marrow mesenchymal stem cells.

AIM: To study the capacity of bone marrow mesenchymal stem cells (BM-MSCs) trans-differentiating into islet-like cells and to observe the effect of portal vein transplantation of islet-like cells in the treatment of streptozotocin-induced diabetic rat. METHODS: BM-MSCs were isolated from SD rats and induced to differentiate into islet-like cells under defined conditions. Differentiation was evaluated with electron microscopy, RT-PCR, immunofluorescence and flow cytometry. Insulin release after glucose challenge was tested with ELISA. Then allogeneic islet-like cells were transplanted into diabetic rats via portal vein. Blood glucose levels were monitored and islet hormones were detected in the liver and pancreas of the recipient by immunohistochemistry. RESULTS: BM-MSCs were spheroid adherent monolayers with high CD90, CD29 and very low CD45 expression. Typical islet-like cells clusters were formed after induction. Electron microscopy revealed that secretory granules were densely packed within the cytoplasm of the differentiated cells. The spheroid cells expressed islet related genes and hormones. The insulin-positive cells accounted for 19.8% and mean fluorescence intensity increased by 2.6 fold after induction. The cells secreted a small amount of insulin that was increased 1.5 fold after glucose challenge. After transplantation, islet-like cells could locate in the liver expressing islet hormones and lower the glucose levels of diabetic rats during d 6 to d 20. CONCLUSION: Rat BM-MSCs could be transdifferentiated into islet-like cells in vitro. Portal vein transplantation of islet-like cells could alleviate the hyperglycemia of diabetic rats.

Relationship between co-stimulatory molecule B7-H3 expression and gastric carcinoma histology and prognosis.

AIM: To investigate the expression of co-stimulatory molecule B7-H3 in gastric carcinoma and adenoma tissue as well as normal gastric tissue and to explore the relationship between B7-H3 expression and pathological features and prognosis of gastric carcinoma. METHODS: B7-H3 expression was detected in 102 samples of human gastric carcinoma and 10 samples of gastric adenoma and 10 samples of normal gastric tissue by immunohistochemical assay. Correlation between the expression of B7-H3 and the patients' age, sex, gastric carcinoma locus, tumor size, tissue type, tumor infiltration depth, differentiation degree, lymph node metastasis, and survival time was analyzed. RESULTS: B7-H3 was expressed in all gastric adenoma samples and in 58.8% samples of gastric carcinoma. B7-H3 expression in gastric carcinoma samples was not related with the patients' age, sex, lymph node metastasis, and tumor size (P>0.05), but with the survival time, infiltration depth of tumor and tissue type. CONCLUSION: Detection of B7-H3 expression in gastric carcinoma tissue is beneficial to the judgment of the prognosis of gastric carcinoma patients and the choice of treatment.