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The Protective Action of Metformin against Pro-Inflammatory Cytokine-Induced Human Islet Cell Damage and the Mechanisms Involved. Cells 2022; 11:cells11152465. [PMID: 35954309 PMCID: PMC9368307 DOI: 10.3390/cells11152465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 08/04/2022] [Accepted: 08/06/2022] [Indexed: 11/24/2022] Open
Abstract
Metformin, a drug widely used in type 2 diabetes (T2D), has been shown to protect human β-cells exposed to gluco- and/or lipotoxic conditions and those in islets from T2D donors. We assessed whether metformin could relieve the human β-cell stress induced by pro-inflammatory cytokines (which mediate β-cells damage in type 1 diabetes, T1D) and investigated the underlying mechanisms using shotgun proteomics. Human islets were exposed to 50 U/mL interleukin-1β plus 1000 U/mL interferon-γ for 48 h, with or without 2.4 µg/mL metformin. Glucose-stimulated insulin secretion (GSIS) and caspase 3/7 activity were studied, and a shotgun label free proteomics analysis was performed. Metformin prevented the reduction of GSIS and the activation of caspase 3/7 induced by cytokines. Proteomics analysis identified more than 3000 proteins in human islets. Cytokines alone altered the expression of 244 proteins (145 up- and 99 down-regulated), while, in the presence of metformin, cytokine-exposure modified the expression of 231 proteins (128 up- and 103 downregulated). Among the proteins inversely regulated in the two conditions, we found proteins involved in vesicle motility, defense against oxidative stress (including peroxiredoxins), metabolism, protein synthesis, glycolysis and its regulation, and cytoskeletal proteins. Metformin inhibited pathways linked to inflammation, immune reactions, mammalian target of rapamycin (mTOR) signaling, and cell senescence. Some of the changes were confirmed by Western blot. Therefore, metformin prevented part of the deleterious actions of pro-inflammatory cytokines in human β-cells, which was accompanied by islet proteome modifications. This suggests that metformin, besides use in T2D, might be considered for β-cell protection in other types of diabetes, possibly including early T1D.
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Pingitore A, Gonzalez-Abuin N, Ruz-Maldonado I, Huang GC, Frost G, Persaud SJ. Short chain fatty acids stimulate insulin secretion and reduce apoptosis in mouse and human islets in vitro: Role of free fatty acid receptor 2. Diabetes Obes Metab 2019; 21:330-339. [PMID: 30203438 DOI: 10.1111/dom.13529] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/29/2018] [Accepted: 09/05/2018] [Indexed: 12/28/2022]
Abstract
AIMS To evaluate the role of free fatty acid receptor 2 (FFAR2)/G-protein coupled receptor 43 in mediating the effects of the short chain fatty acids (SCFAs) sodium acetate (SA) and sodium propionate (SP) on islet function in vitro, and to identify the intracellular signalling pathways used in SCFA-induced potentiation of glucose-induced insulin secretion. MATERIALS AND METHODS Islets of Langerhans were isolated from wild-type and FFAR2-/- mice and from human donors without diabetes. The effects of SA and SP on dynamic insulin secretion from perifused islets were quantified by radioimmunoassay, signalling downstream of SCFAs was profiled by single-cell calcium microfluorimetry, and measurement of cAMP was performed using a fluorescence assay. Islet apoptosis was induced by exposure to cytokines or sodium palmitate, and the effects of SA and SP in regulating islet apoptosis were assessed by quantification of caspase 3/7 activities. RESULTS Deletion of FFAR2 did not affect islet morphology or insulin content. SA and SP reversibly potentiated insulin secretion from mouse islets in a FFAR2-dependent manner. SCFA-induced potentiation of insulin secretion was coupled to Gq activation of phospholipase C and protein kinase C, with no evidence of Gi-mediated signalling. SA and SP protected human and mouse islets from apoptosis, and these pro-survival properties were dependent on islet expression of FFAR2. CONCLUSION Our results indicate that FFAR2 directly mediates both the stimulatory effects of SA and SP on insulin secretion and their protection against islet apoptosis. We have also shown that SCFA coupling in islets occurs via Gq-coupled intracellular signalling.
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Affiliation(s)
- Attilio Pingitore
- Department of Diabetes, Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Noemi Gonzalez-Abuin
- Division of Human Nutrition, Faculty of Medicine, Imperial College London, London, UK
| | - Inmaculada Ruz-Maldonado
- Department of Diabetes, Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Guo C Huang
- Department of Diabetes, Faculty of Life Sciences and Medicine, King's College London, London, UK
| | - Gary Frost
- Division of Human Nutrition, Faculty of Medicine, Imperial College London, London, UK
| | - Shanta J Persaud
- Department of Diabetes, Faculty of Life Sciences and Medicine, King's College London, London, UK
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Pingitore A, Chambers ES, Hill T, Maldonado IR, Liu B, Bewick G, Morrison DJ, Preston T, Wallis GA, Tedford C, Castañera González R, Huang GC, Choudhary P, Frost G, Persaud SJ. The diet-derived short chain fatty acid propionate improves beta-cell function in humans and stimulates insulin secretion from human islets in vitro. Diabetes Obes Metab 2017; 19:257-265. [PMID: 27761989 DOI: 10.1111/dom.12811] [Citation(s) in RCA: 168] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/13/2016] [Accepted: 10/14/2016] [Indexed: 12/18/2022]
Abstract
AIMS Diet-derived short chain fatty acids (SCFAs) improve glucose homeostasis in vivo, but the role of individual SCFAs and their mechanisms of action have not been defined. This study evaluated the effects of increasing colonic delivery of the SCFA propionate on β-cell function in humans and the direct effects of propionate on isolated human islets in vitro. MATERIALS AND METHODS For 24 weeks human subjects ingested an inulin-propionate ester that delivers propionate to the colon. Acute insulin, GLP-1 and non-esterified fatty acid (NEFA) levels were quantified pre- and post-supplementation in response to a mixed meal test. Expression of the SCFA receptor FFAR2 in human islets was determined by western blotting and immunohistochemistry. Dynamic insulin secretion from perifused human islets was quantified by radioimmunoassay and islet apoptosis was determined by quantification of caspase 3/7 activities. RESULTS Colonic propionate delivery in vivo was associated with improved β-cell function with increased insulin secretion that was independent of changes in GLP-1 levels. Human islet β-cells expressed FFAR2 and propionate potentiated dynamic glucose-stimulated insulin secretion in vitro, an effect that was dependent on signalling via protein kinase C. Propionate also protected human islets from apoptosis induced by the NEFA sodium palmitate and inflammatory cytokines. CONCLUSIONS Our results indicate that propionate has beneficial effects on β-cell function in vivo, and in vitro analyses demonstrated that it has direct effects to potentiate glucose-stimulated insulin release and maintain β-cell mass through inhibition of apoptosis. These observations support ingestion of propiogenic dietary fibres to maintain healthy glucose homeostasis.
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Affiliation(s)
- Attilio Pingitore
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| | - Edward S Chambers
- Faculty of Medicine, Nutrition and Dietetic Research Group, Imperial College London, London, UK
| | - Thomas Hill
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| | - Inmaculada Ruz Maldonado
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| | - Bo Liu
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| | - Gavin Bewick
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| | - Douglas J Morrison
- Stable Isotope Biochemistry Laboratory, Scottish Universities Environmental Research Centre, University of Glasgow, Glasgow, UK
| | - Tom Preston
- Stable Isotope Biochemistry Laboratory, Scottish Universities Environmental Research Centre, University of Glasgow, Glasgow, UK
| | - Gareth A Wallis
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | - Catriona Tedford
- School of Science, University of the West of Scotland, Hamilton, UK
| | - Ramón Castañera González
- Department of General Surgery, Rio Carrión Hospital, University Hospital Complex of Palencia, Palencia, Spain
| | - Guo C Huang
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| | - Pratik Choudhary
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
| | - Gary Frost
- Faculty of Medicine, Nutrition and Dietetic Research Group, Imperial College London, London, UK
| | - Shanta J Persaud
- Division of Diabetes and Nutritional Sciences, Diabetes Research Group, King's College London, London, UK
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