The direct effects of the angiotensin-converting enzyme inhibitors, zofenoprilat and enalaprilat, on isolated human pancreatic islets

Objective: Data from prospective studies suggest a significant reduction in the risk of new diabetes from drug therapies containing angiotensin-converting enzyme (ACE) inhibitors. Since the renin–angiotensin system (RAS) has been found locally in several tissues and cells, including pancreatic islets, we hypothesized that the positive metabolic effects of ACE inhibitors may be due to a beneficial action of these compounds on insulin-secreting β-cells. Design and methods: Isolated human pancreatic islets were studied after 24 h of incubation with 22.2 mmol/l glucose, with or without the presence in the incubation medium of 0.5–6.0 mmol/l zofenoprilat or enalaprilat, ACE inhibitor drugs which differ by the presence of a sulphydryl or a carboxyl group in their structural formula. Functional and molecular studies were then performed to assess insulin secretion, redox balance, mRNA and protein expression. Results: Angiotensinogen, ACE and angiotensin type 1 receptor mRNA expression increased in islets cultured in high glucose; this was similarly prevented by the presence of either ACE inhibitor. As expected, preculture of human islets in high glucose determined a marked reduction in insulin secretion which was associated with enhanced oxidative stress, as shown by increased nitrotyrosine concentrations, and enhanced expression of protein kinase C β and NADPH oxidase. The presence of either of the ACE inhibitors counteracted several of the deleterious effects of high glucose exposure, including reduction of insulin secretion and increased oxidative stress; zofenoprilat showed significantly more marked effects. Conclusions: These results showed that: (a) RAS molecules are present in human islets and their expression is sensitive to glucose concentration, (b) ACE inhibitors, and in particular zofenoprilat, protect human islets from glucotoxicity and (c) the effects of ACE inhibition are associated with decreased oxidative stress. Together, these findings provide evidence that the possible beneficial effects of ACE inhibitors in human diabetes are due, at least in part, to a protective action on pancreatic β-cells.

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Metformin, but not leptin, regulates AMP-activated protein kinase in pancreatic islets: impact on glucose-stimulated insulin secretion

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00532.2003 ◽

2004 ◽

Vol 286 (6) ◽

pp. E1023-E1031 ◽

Cited By ~ 107

Author(s):

Isabelle Leclerc ◽

Wolfram W. Woltersdorf ◽

Gabriela da Silva Xavier ◽

Rebecca L. Rowe ◽

Sarah E. Cross ◽

...

Keyword(s):

Type 2 Diabetes ◽

Insulin Secretion ◽

Protein Kinase ◽

Pancreatic Islets ◽

Human Islets ◽

Β Cells ◽

Min6 Cells ◽

Ampk Activity ◽

Amp Activated Protein Kinase

Metformin, a drug widely used in the treatment of type 2 diabetes, has recently been shown to act on skeletal muscle and liver in part through the activation of AMP-activated protein kinase (AMPK). Whether metformin or the satiety factor leptin, which also stimulates AMPK in muscle, regulates this enzyme in pancreatic islets is unknown. We have recently shown that forced increases in AMPK activity inhibit insulin secretion from MIN6 cells (da Silva Xavier G, Leclerc I, Varadi A, Tsuboi T, Moule SK, and Rutter GA. Biochem J 371: 761–774, 2003). Here, we explore whether 1) glucose, metformin, or leptin regulates AMPK activity in isolated islets from rodent and human and 2) whether changes in AMPK activity modulate insulin secretion from human islets. Increases in glucose concentration from 0 to 3 and from 3 to 17 mM inhibited AMPK activity in primary islets from mouse, rat, and human, confirming previous findings in insulinoma cells. Incubation with metformin (0.2–1 mM) activated AMPK in both human islets and MIN6 β-cells in parallel with an inhibition of insulin secretion, whereas leptin (10–100 nM) was without effect in MIN6 cells. These studies demonstrate that AMPK activity is subject to regulation by both glucose and metformin in pancreatic islets and clonal β-cells. The inhibitory effects of metformin on insulin secretion may therefore need to be considered with respect to the use of this drug for the treatment of type 2 diabetes.

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Protective Effect of Siegesbeckia orientalis on Pancreatic β-Cells under High Glucose-Induced Glucotoxicity

Applied Sciences ◽

10.3390/app112210963 ◽

2021 ◽

Vol 11 (22) ◽

pp. 10963

Author(s):

Chi-Chang Chang ◽

Jer-Yiing Houng ◽

Shih-Wei Wang ◽

Chin-Feng Hsuan ◽

Yung-Chuan Lu ◽

...

Keyword(s):

Oxidative Stress ◽

Antioxidant Enzymes ◽

Insulin Secretion ◽

Protective Effect ◽

Normal Level ◽

High Glucose ◽

Glucose Concentration ◽

Β Cells ◽

Pancreatic Β Cells ◽

Siegesbeckia Orientalis

The glucotoxicity caused by long-term exposure of β-cells to high glucose (HG) conditions may lead to the generation of more reactive oxygen species (ROS), reduce the activity of antioxidant enzymes, cause cell damage and apoptosis, and induce insulin secretion dysfunction. Siegesbeckia orientalis linne is a traditional folk herbal medicine used to treat snake bites, rheumatoid arthritis, allergies, and immune deficiencies. In this study, we evaluated the protective effect of S. orientalis ethanol extract (SOE) on cell death and oxidative stress in RIN-m5f pancreatic β-cells stimulated by two HG concentrations (50–100 mM). In the cell viability assay, SOE could significantly increase the survival rate of pancreatic β-cells under HG-induced conditions. For the oxidative stress induced by HG condition, the treatment of SOE effectively reduced the ROS formation, increased the content of intracellular glutathione, and up-regulated the expression of antioxidant enzymes, catalase, superoxide dismutase, and glutathione peroxidase. As a result, the SOE treatment could decrease the glucotoxicity-mediated oxidative damage on RIN-m5F β-cells. Moreover, SOE had the function of regulating insulin secretion in pancreatic β-cells under different HG-mediated conditions. It could decrease the increasing intracellular insulin secretion under the low glucose concentration to normal level; while increase the decreasing intracellular insulin secretion under the relatively high glucose concentration to normal level. Taken together, this study suggests that SOE has a protective effect on pancreatic β-cells under the HG-stimulated glucotoxic environment.

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Leptin Suppression of Insulin Secretion and Gene Expression in Human Pancreatic Islets: Implications for the Development of Adipogenic Diabetes Mellitus1

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jcem.84.2.5460 ◽

1999 ◽

Vol 84 (2) ◽

pp. 670-676 ◽

Cited By ~ 2

Author(s):

Jochen Seufert ◽

Timothy J. Kieffer ◽

Colin A. Leech ◽

George G. Holz ◽

Wolfgang Moritz ◽

...

Keyword(s):

Gene Expression ◽

Insulin Secretion ◽

Pancreatic Islets ◽

Ribonucleic Acid ◽

Leptin Receptor ◽

Human Islets ◽

Β Cells ◽

Messenger Ribonucleic Acid ◽

Fluorescence Confocal Microscopy ◽

Glucagon Like Peptide 1

Previously we demonstrated the expression of the long form of the leptin receptor in rodent pancreatic β-cells and an inhibition of insulin secretion by leptin via activation of ATP-sensitive potassium channels. Here we examine pancreatic islets isolated from pancreata of human donors for their responses to leptin. The presence of leptin receptors on islet β-cells was demonstrated by double fluorescence confocal microscopy after binding of a fluorescent derivative of human leptin (Cy3-leptin). Leptin (6.25 nm) suppressed insulin secretion of normal islets by 20% at 5.6 mm glucose. Intracellular calcium responses to 16.7 mm glucose were rapidly reduced by leptin. Proinsulin messenger ribonucleic acid expression in islets was inhibited by leptin at 11.1 mm, but not at 5.6 mm glucose. Leptin also reduced proinsulin messenger ribonucleic acid levels that were increased in islets by treatment with 10 nm glucagon-like peptide-1 in the presence of either 5.6 or 11.1 mm glucose. These findings demonstrate direct suppressive effects of leptin on insulin-producingβ -cells in human islets at the levels of both stimulus-secretion coupling and gene expression. The findings also further indicate the existence of an adipoinsular axis in humans in which insulin stimulates leptin production in adipocytes and leptin inhibits the production of insulin in β-cells. We suggest that dysregulation of the adipoinsular axis in obese individuals due to defective leptin reception byβ -cells may result in chronic hyperinsulinemia and may contribute to the pathogenesis of adipogenic diabetes.

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Rosiglitazone prevents the impairment of human islet function induced by fatty acids: evidence for a role of PPARγ2 in the modulation of insulin secretion

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00561.2002 ◽

2004 ◽

Vol 286 (4) ◽

pp. E560-E567 ◽

Cited By ~ 100

Author(s):

R. Lupi ◽

S. Del Guerra ◽

L. Marselli ◽

M. Bugliani ◽

U. Boggi ◽

...

Keyword(s):

Fatty Acids ◽

Insulin Secretion ◽

Mrna Expression ◽

Pancreatic Islets ◽

Human Islets ◽

Acid Mixture ◽

Human Pancreatic Islets ◽

Pparγ Agonist ◽

Pparγ Agonists ◽

Insulin Mrna

Peroxisome proliferator-activated receptors (PPARs) are a subgroup of the superfamily of nuclear receptors, with three distinct main types: α, β and γ (subdivided into γ1 and γ2). Recently, the presence of PPARγ has been reported in human islets. Whether other PPAR types can be found in human islets, how islet PPARγ mRNA expression is regulated by the metabolic milieu, their role in insulin secretion, and the effects of a PPARγ agonist are not known. In this study, human pancreatic islets were prepared by collagenase digestion and density gradient purification from nonobese adult donors. The presence of PPAR mRNAs was assessed by RT-PCR, and the effect was evaluated of exposure for up to 24 h to either 22.2 mmol/l glucose and/or 0.25, 0.5, or 1.0 mmol/l long-chain fatty acid mixture (oleate to palmitate, 2:1). PPARβ and, to a greater extent, total PPARγ and PPARγ2 mRNAs were expressed in human islets, whereas PPARα mRNA was not detected. Compared with human adipose tissue, PPARγ mRNA was expressed at lower levels in the islets, and PPARβ at similar levels. The expression of PPARγ2 mRNA was not affected by exposure to 22.2 mmol/l glucose, whereas it decreased markedly and time dependently after exposure to progressively higher free fatty acids (FFA). This latter effect was not affected by the concomitant presence of high glucose. Exposure to FFA caused inhibition of insulin mRNA expression, glucose-stimulated insulin release, and reduction of islet insulin content. The PPARγ agonists rosiglitazone and 15-deoxy-Δ-12,14prostaglandin J2 prevented the cytostatic effect of FFA as well as the FFA-induced changes of PPAR and insulin mRNA expression. In conclusion, this study shows that PPARγ mRNA is expressed in human pancreatic islets, with predominance of PPARγ2; exposure to FFA downregulates PPARγ2 and insulin mRNA expression and inhibits glucose-stimulated insulin secretion; exposure to PPARγ agonists can prevent these effects.

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SARS-CoV-2 receptor Angiotensin I-Converting Enzyme type 2 (ACE2) is expressed in human pancreatic β-cells and in the human pancreas microvasculature

10.1101/2020.07.23.208041 ◽

2020 ◽

Cited By ~ 5

Author(s):

Daniela Fignani ◽

Giada Licata ◽

Noemi Brusco ◽

Laura Nigi ◽

Giuseppina E. Grieco ◽

...

Keyword(s):

Pancreatic Islets ◽

Human Pancreas ◽

Converting Enzyme ◽

Angiotensin I ◽

Β Cells ◽

Β Cell ◽

Human Pancreatic Islets ◽

Ductal Cells ◽

Angiotensin I Converting Enzyme

AbstractIncreasing evidence demonstrated that the expression of Angiotensin I-Converting Enzyme type 2 (ACE2), is a necessary step for SARS-CoV-2 infection permissiveness. In the light of the recent data highlighting an association between COVID-19 and diabetes, a detailed analysis aimed at evaluating ACE2 expression pattern distribution in human pancreas is still lacking. Here, we took advantage of INNODIA network EUnPOD biobank collection to thoroughly analyse ACE2, both at mRNA and protein level, in multiple human pancreatic tissues and using several methodologies.Using multiple reagents and antibodies, we showed that ACE2 is expressed in human pancreatic islets, where it is preferentially expressed in subsets of insulin producing β-cells. ACE2 is also is highly expressed in pancreas microvasculature pericytes and moderately expressed in rare scattered ductal cells. By using different ACE2 antibodies we showed that a recently described short-ACE2 isoform is also prevalently expressed in human β-cells.Finally, using RT-qPCR, RNA-seq and High-Content imaging screening analysis, we demonstrated that pro-inflammatory cytokines, but not palmitate, increases ACE2 expression in the β-cell line EndoC-βH1 and in primary human pancreatic islets.Taken together, our data indicate a potential link between SARS-CoV-2 and diabetes through putative infection of pancreatic microvasculature and/or ductal cells and/or through direct β-cell virus tropism.

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MicroRNA‑532‑5p regulates oxidative stress and insulin secretion damage in high glucose‑induced pancreatic β cells by downregulating the expression levels of CCND1

Molecular Medicine Reports ◽

10.3892/mmr.2021.12433 ◽

2021 ◽

Vol 24 (5) ◽

Author(s):

Zhibiao Zhong ◽

Weilan Su ◽

Hongmei Chen

Keyword(s):

Oxidative Stress ◽

Insulin Secretion ◽

High Glucose ◽

Β Cells ◽

Pancreatic Β Cells ◽

Expression Levels

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Persistent Infection of Human Pancreatic Islets by Coxsackievirus B Is Associated with Alpha Interferon Synthesis in β Cells

Journal of Virology ◽

10.1128/jvi.74.21.10153-10164.2000 ◽

2000 ◽

Vol 74 (21) ◽

pp. 10153-10164 ◽

Cited By ~ 127

Author(s):

Wassim Chehadeh ◽

Julie Kerr-Conte ◽

François Pattou ◽

Gunar Alm ◽

Jean Lefebvre ◽

...

Keyword(s):

Pancreatic Islets ◽

Islet Cells ◽

Human Islets ◽

Adult Brain ◽

Viral Rna ◽

Alpha Interferon ◽

Β Cells ◽

Human Pancreatic Islets ◽

Reverse Transcription Pcr ◽

Vp1 Capsid Protein

ABSTRACT The interactions of coxsackievirus B3 (CVB3), CVB4E2 (diabetogenic), and CVB4JBV (nondiabetogenic) strains with human pancreatic islets from eight adult brain-dead donors were investigated. Persistent replication of viruses in human islets was proved by detection of viral RNA by in situ hybridization, VP1 capsid protein by immunofluorescence (IF) staining, negative-strand viral RNA by reverse transcription-PCR in extracted RNA from islets, and release of infectious particles up to 30 days after infection without obvious cytolysis. By double IF staining, glucagon-containing α cells and insulin-containing β cells were shown to be susceptible to CVB. The persistence of CVB3 and CVB4 in islet cells was associated with the chronic synthesis of alpha interferon (IFN-α), as evidenced by the detection of IFN-α mRNA and immunoreactive IFN-α with antiviral activity. By double IF staining, IFN-α was detected in insulin-producing β cells only. Experiments with neutralizing anti-coxsackievirus and adenovirus receptor (CAR) antibodies provided evidence that CAR was expressed by α and β cells and that it played a role in the infection of these cells with CVB and the consecutive IFN-α expression in β cells. The viral replication and the expression of IFN-α in islets were not restricted to the CVB4E2 diabetogenic strain and did not depend on the genetic background of the host. The neutralization of endogenous IFN-α significantly enhanced the CVB replication in islet cells and resulted in rapid destruction of islets. Thus, human β cells can harbor a persistent CVB infection, and CVB-induced IFN-α plays a role in the initiation and/or maintenance of chronic CVB infection in human islets.

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