Oral nano-formulation improves pancreatic islets dysfunction via lymphatic transport for antidiabetic treatment

Type 2 diabetes mellitus (T2DM) therapy is facing the challenges of long-term medication and gradual destruction of pancreatic islet β-cells. Therefore, it is timely to develop oral prolonged action formulations to improve compliance, while restoring β-cells survival and function. Herein, we designed a simple nanoparticle with enhanced oral absorption and pancreas accumulation property, which combined apical sodium-dependent bile acid transporter-mediated intestinal uptake and lymphatic transportation. In this system, taurocholic acid (TCA) modified poly(lactic-co-glycolic acid) (PLGA) was employed to achieve pancreas location, hydroxychloroquine (HCQ) was loaded to execute therapeutic efficacy, and 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) was introduced as stabilizer together with synergist (PLGA-TCA/DLPC/HCQ). In vitro and in vivo results have proven that PLGA-TCA/DLPC/HCQ reversed the pancreatic islets damage and dysfunction, thus impeding hyperglycemia progression and restoring systemic glucose homeostasis via only once administration every day. In terms of mechanism PLGA-TCA/DLPC/HCQ ameliorated oxidative stress, remodeled the inflammatory pancreas microenvironment, and activated PI3K/AKT signaling pathway without obvious toxicity. This strategy not only provides an oral delivery platform for increasing absorption and pancreas targetability but also opens a new avenue for thorough T2DM treatment.

Effects of recombinant human syntaxin-4(STX4) on lipopolysaccharide-induced islet β-cell INS-1 injury and underlying mechanism / 中华内分泌代谢杂志

Objective:To explore the effect of recombinant human syntaxin-4(STX4) on lipopolysaccharide(LPS)-induced injury in islet β-cells(INS-1).Methods:Pancreatic islet β-cells(INS-1) were divided into Control (blank control), LPS (LPS treatment), LPS+ NC (transfection of negative control vector, LPS treatment), and LPS+ STX4 (transfection of pcDNA-STX4, LPS treatment) groups. RT-qPCR and Western blot were used to detect STX4 mRNA and protein expression, flow cytometry to detect apoptosis, DCFHDA method to detect reactive oxygen species(ROS) level, xanthine oxidation method to detect superoxide orgotein dismutase(SOD) level, colorimetric method to detect glutathione peroxidase(GSH-Px) level, ammonium molybdate colorimetric method to detect catalase(CAT) level, thiobarbituric acid method to detect malonaldehyde(MDA) level, ELISA method to detect the level of interleukin-1β(IL-1β), tumor necrosis factor-α(TNF-α), and insulin secretion levels under glucose conditions secreted by cells, Western blot method to detect Cleared Caspase-3, Bcl-2 Associated X Protein(Bax), p65 protein expression. After treatment with NF-κB signaling pathway activator, STX4 up-regulated islet β-cell INS-1 was given LPS stimulation, and the same method was used to measure apoptosis, ROS, SOD, GSH-Px, CAT, MDA levels and secreted IL-1β, TNF-α, insulin levels and Cleaved Caspase-3, Bax, p65 protein levels.Results:Compared with the Control group, the expression of STX4 mRNA and protein in islet β cells of the LPS group decreased, the apoptosis rate, ROS level, and MDA levels increased, and the levels of SOD, GSH-Px, and CAT decreased, the levels of IL-1β, TNF-α increased, the level of insulin secreted by the cells decreased, and the expression levels of Cleaved Caspase-3, Bax, and p65 also increased. NF-κB pathway activator treatment reversed the effect of up-regulated STX4 on islet β-cell apoptosis, ROS, SOD, GSH-Px, CAT, MDA levels and secreted IL-1β, TNF-α levels, and Cleaved Caspase-3 , Bax and p65 protein levels.Conclusion:Up-regulation of STX4 alleviated LPS-induced islet β cell oxidative damage, apoptosis and inflammatory factor release. The underlying mechanism might be related to the inhibition of activated NF-κB signaling pathway.

Relationships between islet β-cell function and infection,inflammation and major organ function in multiple organ dysfunction syndrome patients with severe traumatic hemorrhage / 重庆医学

Objective To analyse the relationships between islet β-cell function and infection,inflammation and major organ function in multiple organ dysfunction syndrome (MODS) patients with severe traumatic hemorrhage.Methods A total of 187 cases of MODS patients hospitalized in the 94th Hospital of PLA from January 2013 to January 2016 were selected,and were divided into the MODS survival group (MODS-S group,104 cases) and MODS dead group (MODS-D group).Other 100 healthy subjects were selected as the control group.The fasting blood glucose (GLU0) and insulin (INS0) levels,blood glucose (GLU30) and insulin (INS30) levels after 30 min of glucose loading,and levels of soluble triggering receptor expressedon myeloid cells-1 (sTREM-1),tumor necrosis factor-α (TNF-a),interleukin-6 (IL-6),alanine aminotransferase (ALT),creatinine (Cre) and creatine kinase isoenzyme (CK-MB) in different groups were determined.The insulin-β-cell function was evaluated by homeostasis model assessment of β-cell function (HOMA-β) index and ratio of insulin increment and blood glucose increment after 30 min of glucose loading (ΔINS30/ΔGLU30),and their relationships to other indexes,including sTREM-1,TNF-α,IL-6,GLU0,ALT,Cre and CK-MB,in MODS patients with severe traumatic hemorrhage were analysed.Results The HOMA-β and AINS30/AGLU30 ratio in the MODS-D group were lower than those in the MODS-S group,and levels of sTREM-1,TNF-α,IL-6,ALT,Cre and CK-MB in the MODS-D group were higher than those in the MODS-S group,there were statistically significant differences (P＜0.01).In MODS patients with severe traumatic hemorrhage,HOMA-β and ΔINS30/AGLU30 was both negatively correlated with sTREM-1,TNF-α,IL-6,GLU0,ALT,CreandCK-MB (r=-0.356 4,-0.532 1,-0.345 8,-0.772 1,-0.762 5,-0.684 8,-0.606 4;r=-0.428 5,-0.567 8,-0.487 0,-0.743 6,-0.781 7,-0.717 6,-0.640 1,P＜0.01).Conclusion MODS patients with severe traumatic hemorrhage have islet β-cell dysfunction which may be used as a prognostic and diagnostic indicator.

Relationships between islet β-cell function and infection,inflammation and major organ function in multiple organ dysfunction syndrome patients with severe traumatic hemorrhage / 重庆医学

Objective To analyse the relationships between islet β-cell function and infection,inflammation and major organ function in multiple organ dysfunction syndrome (MODS) patients with severe traumatic hemorrhage.Methods A total of 187 cases of MODS patients hospitalized in the 94th Hospital of PLA from January 2013 to January 2016 were selected,and were divided into the MODS survival group (MODS-S group,104 cases) and MODS dead group (MODS-D group).Other 100 healthy subjects were selected as the control group.The fasting blood glucose (GLU0) and insulin (INS0) levels,blood glucose (GLU30) and insulin (INS30) levels after 30 min of glucose loading,and levels of soluble triggering receptor expressedon myeloid cells-1 (sTREM-1),tumor necrosis factor-α (TNF-a),interleukin-6 (IL-6),alanine aminotransferase (ALT),creatinine (Cre) and creatine kinase isoenzyme (CK-MB) in different groups were determined.The insulin-β-cell function was evaluated by homeostasis model assessment of β-cell function (HOMA-β) index and ratio of insulin increment and blood glucose increment after 30 min of glucose loading (ΔINS30/ΔGLU30),and their relationships to other indexes,including sTREM-1,TNF-α,IL-6,GLU0,ALT,Cre and CK-MB,in MODS patients with severe traumatic hemorrhage were analysed.Results The HOMA-β and AINS30/AGLU30 ratio in the MODS-D group were lower than those in the MODS-S group,and levels of sTREM-1,TNF-α,IL-6,ALT,Cre and CK-MB in the MODS-D group were higher than those in the MODS-S group,there were statistically significant differences (P＜0.01).In MODS patients with severe traumatic hemorrhage,HOMA-β and ΔINS30/AGLU30 was both negatively correlated with sTREM-1,TNF-α,IL-6,GLU0,ALT,CreandCK-MB (r=-0.356 4,-0.532 1,-0.345 8,-0.772 1,-0.762 5,-0.684 8,-0.606 4;r=-0.428 5,-0.567 8,-0.487 0,-0.743 6,-0.781 7,-0.717 6,-0.640 1,P＜0.01).Conclusion MODS patients with severe traumatic hemorrhage have islet β-cell dysfunction which may be used as a prognostic and diagnostic indicator.

Role of NADPH oxidase in high fat-induced injury in MIN6 islet βcells / 中国药理学通报

Aim To explore the role of nicotinamide adenine dinucleotide phosphate ( NADPH ) oxidase in high fat-induced injury in MIN6 isletβ cells. Methods MIN6 islet β cells were exposed to different concen-trations of palmitic acid ( 0. 1 , 0. 3 , 0. 5 , 0. 8 mmol · L-1 ) for 48 h and different time points of 0. 5 mmol· L-1 palmitic acid(24,48,72,96 h). Cell viability was measured by MTT, the protein expression of NADPH oxidase subunits such as p22 phox , p47 phox , p67 phox and gp91 phox and apoptosis related proteins such as Bcl-2 and Bax were determined by Western blot. Results MIN6 islet cells exposed to palmitic acid at 0. 5 mmol ·L-1 for 48 h showed a decrease in their viability and an increase in the expression of NADPH oxidase sub-units(p22phox、p47phox、p67phox and gp91phox) and Bax(P<0. 05 ) , while Bcl-2 expression was significantly re-duced. the pretreat with NADPH oxidase inhibitor di-phenyliodonium( DPI,10 μmol · L-1 ) significantly in-hibited high fat-induced Bcl-2 and Bax expression( P<0. 05 ) . Conclusion Activated NADPH oxidase might play an important role in the treatment of high fat-in-duced injury in MIN6 islet cells.

Effect of intermittent high glucose on INS-1 cell proliferation and the expression of skp2-p27 / 中华内分泌代谢杂志

Objective To investigate the effect of intermittent high glucose on proliferation, apoptosis, and cell cycle progression of INS-1 cells, and the possible intracellular pathways activated by intermittent high glucose. Methods Cell viability was evaluated by cell counting kit, the cell cycle was determined by flow cytometry,Annexin-V/PI double-labeled cell apoptosis detection kit was used to monitor cell apoptosis. Cell cycle related protein Skp2 and p27 expressions were detected by Western blot. Results ( 1 ) Both intermittent and constant high glucose significantly inhibited the growth of INS-1 cells, and the former effect was more significant. ( 2 ) Intermittent and constant high glucose levels significantly increased apoptosis in INS-1 cells, and the former effect was more significant. (3) Intermittent and constant high glucose levels significantly inhibited the cell process, the G0/G1 cell cycle arrest also was induced by intermittent high glucose, resulting in lowered proportion of the G2/M phase and S phase of INS-1 cells. (4) Intermittent and constant high glucose significantly decreased the level of protein Skp2 and increased the level of cell cycle related protein p27. Conclusion Intermittent high glucose levels affect INS-1 cell growth and proliferation, as well as induce cell apoptosis, probably by decreasing the level of protein Skp2 and increasing the level of p27 in the cells, resulting in arrest of progression through the G1 phase to the S phase of INS1 cells, and thus impairment of cell proliferation.

Progress of genome-wide association studies in type 2 diabetes mellitus / 中华内分泌代谢杂志

Genome-wide association studies ( CWAS) use high-throughout genotyping technologies to investigate the relation of hundreds of thousands of gene markers(genotype) with clinical conditions and measurable traits (phenotype). Type 2 diabetes mellitus results from the interaction of environmental factors with genetic variants. Many progresses have been acquired from GWAS. New gene regions have been discovered to be involved in the development and function of islet (3-cells, which provides new strategies for the etiology investigation, prevention, and treatment of type 2 diabetes mellitus.

Liraglutide: A novel therapy for type 2 diabetes——Report of "Diabetes Dialogue" International Forum / 中华内分泌代谢杂志

"Diabetes Dialogue" is an international forum of latest cutting-edge research on diabetes. The major topics in the 5th event in 2008 were the novel targets in the treatment of type 2 diabetes. In particular, the latest developments in incretin-based therapies, especially glucagon-like peptide-1 (GLP-1) -based therapies, and their effects on the β-cells have been provided. Studies suggested that type 2 diabetes is characterized by progressively deteriorated β-cell function with the presence of insulin resistance. Owing to its glucose-dependant glucose lowering effect and the effect on improvement of β-cell function, GLP-1 has become the novel target of therapies. Liraglutide, a GLP-1 analogue developed by Novo Nordisk, is one of the novel therapies in the treatment of type 2 diabetes. Many studies have demonstrated that liraglutide showed both an efficacious and sustained effect on glycemic control and a significant improvement of 13-cell function. As a result, recently the role of GLP-1 or GLP-1 analogue in the management of type 2 diabetes has gained more popularity and liraglutide is considered as a promising drug in the treatment of type 2 diabetes.

Effects of "glucotoxicity", "lipotoxicity" and "glucolipotoxicity" on islet β-cells / 中华内分泌代谢杂志

Glucotoxicity, lipotoxicity and glucolipotoxieity are secondary phenomena following the primary pathogenesis, including the effects of genetic and environmental factors of type 2 diabetes. However, there exist two theories: (1) Lipotoxicity, presents before blood glucose rising, may trigger off a chain reaction which results in hyperglycemia. Hence the term " diabetes mellipidus" was proposed. (2) Hyperglycemia is a prerequisite for lipotoxicity. It seems more appropriate to state that (1) the glucotoxieity and iipotoxicity may present separately or concurrently in type 2 diabetes; (2) The combined glucolipotoxicity should describe the deleterious actions by higher levels of both glucose and free fatty acids on β-cell function, which finally causes progressive deterioration of insulin secretion.

Preservation of β-cell function in type 2 diabetes by GLP-1 based therapy / 中华内分泌代谢杂志

Type 2 diabetes is characterized by deteriorated β-cell function and progressive loss of β-cell mass. Pancreatic islets are a target of high concentrations of glucose, pro-inflammatory cytokines and free fatty acid levels, which are associated with obesity, insulin resistance and β-cell apeptosis. Therapy targeting β-cell dysfunction is crucial in the treatment of type 2 diabetes. GLP-1, one of the incretin hormones, has been demonstrated to improve glycaemic control and β-cell function through its multiple physiological effects. In this review, the mechanisms involved in β-cell dysfunction and β-cell loss are addressed, and the updates in GLP-1 based therapy for the preservation of β-cell mass and β-cell function in type 2 diabetes are also reviewed.

Recent progress in the research of the impact of glucagon-like peptide-1 on islet β-cells / 中华内分泌代谢杂志

Glucagon-like poptide-1 (GLP-1) is an incretin secreted by the enteroendocrine L cells of the gut. Upon the activation of GLP-1 receptor, adenylyl cyclase is activated and cAMP is generated, leading to the activation of protein kinase A and Epac signal pathway. GLP-1 could also activate calcium/calmodulin pathway as well as mitogen-activated protein kinases and phosphatidyl inositol-3 kinase pathway. GLP-1 not only stimulates the phase 1 and phase 2 insulin secretion, but also increases insulin synthesis. GLP-1 also stimulates proliferation and differentiation of islet β-cells, and protects β-cell from apoptosis and modulates endoplasmic reticulum stress response leading to promotion of β-cell adaptation and survival.

Insulin production, insulin secretion and type 2 diabetes:β-cell at the core of the problem / 中华内分泌代谢杂志

Over the past years, type 2 diabetes mellitus (T2DM) has been defined as a disease caused by insulin resistance, as part of the metabolic syndrome. Insulin resistance does exist in T2DM; however, it exists to the same extent in many more persons without diabetes, whether with or without other features of the metabolic syndrome. Therefore, insulin resistance alone can not be the determining pathogenic factor in T2DM.From its earliest stages, including impaired glucose tolerance (IGT) and impaired fasting glucose (IFG), but perhaps even before these measurable changes, at the "prediabetic" period, T2DM shows derangements in the kinetics of insulin release. Its main characteristic is the loss of first-phase insulin response to glucose, with gradual impairment of also second-phase or overall insulin secretion. Loss of first-phase response has metabolic consequences: lack of rapid insulinization of the liver delays the suppression of hepatic glucose output and causes therefore postprandial hyperglycemia. β-Cell mass has been found to be reduced in T2DM in some but not all studies; therefore this necessitates further confirmation. Nevertheless, it is clear that the diabetes-prone β-cell has limited capacity to adapt cell function to increased secretory demand in insulin resistance or caloric load. Furthermore, even mild hyperglycemia dramatically impairs insulin secretion and proinsulin biosynthesis, thus further reducing the availability of insulin for metabolic needs. The transcription factor PDX-1 plays a central role in this context. Therefore, early and effective induction of near-normoglycemia in T2DM is of paramount importance, especially with restoration of first-phase insulin secretion.