RESUMEN
Obesity leads to chronic, systemic inflammation and can lead to insulin resistance (IR), ß-cell dysfunction, and ultimately type 2 diabetes (T2D). This chronic inflammatory state contributes to long-term complications of diabetes, including non-alcoholic fatty liver disease (NAFLD), retinopathy, cardiovascular disease, and nephropathy, and may underlie the association of type 2 diabetes with other conditions such as Alzheimer's disease, polycystic ovarian syndrome, gout, and rheumatoid arthritis. Here, we review the current understanding of the mechanisms underlying inflammation in obesity, T2D, and related disorders. We discuss how chronic tissue inflammation results in IR, impaired insulin secretion, glucose intolerance, and T2D and review the effect of inflammation on diabetic complications and on the relationship between T2D and other pathologies. In this context, we discuss current therapeutic options for the treatment of metabolic disease, advances in the clinic and the potential of immune-modulatory approaches.
Asunto(s)
Complicaciones de la Diabetes/inmunología , Diabetes Mellitus Tipo 2/inmunología , Inflamación/inmunología , Obesidad/inmunología , Animales , Humanos , Inmunomodulación , Resistencia a la InsulinaRESUMEN
The deleterious effect of chronic activation of the IL-1ß system on type 2 diabetes and other metabolic diseases is well documented. However, a possible physiological role for IL-1ß in glucose metabolism has remained unexplored. Here we found that feeding induced a physiological increase in the number of peritoneal macrophages that secreted IL-1ß, in a glucose-dependent manner. Subsequently, IL-1ß contributed to the postprandial stimulation of insulin secretion. Accordingly, lack of endogenous IL-1ß signaling in mice during refeeding and obesity diminished the concentration of insulin in plasma. IL-1ß and insulin increased the uptake of glucose into macrophages, and insulin reinforced a pro-inflammatory pattern via the insulin receptor, glucose metabolism, production of reactive oxygen species, and secretion of IL-1ß mediated by the NLRP3 inflammasome. Postprandial inflammation might be limited by normalization of glycemia, since it was prevented by inhibition of the sodium-glucose cotransporter SGLT2. Our findings identify a physiological role for IL-1ß and insulin in the regulation of both metabolism and immunity.
Asunto(s)
Diabetes Mellitus Tipo 2/inmunología , Inflamación/inmunología , Células Secretoras de Insulina/fisiología , Interleucina-1beta/metabolismo , Macrófagos/fisiología , Animales , Células Cultivadas , Glucosa/metabolismo , Humanos , Inflamasomas/metabolismo , Insulina/metabolismo , Interleucina-1beta/genética , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , Periodo Posprandial , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal , Transportador 2 de Sodio-Glucosa/metabolismoRESUMEN
AIMS/HYPOTHESIS: Glutamate-induced cytotoxicity (excitotoxicity) has been detected in pancreatic beta cells. The cystine/glutamate antiporter System xc- exports glutamate to the extracellular space and is therefore implicated as driving excitotoxicity. As of yet, it has not been investigated whether System xc- contributes to pancreatic islet function. METHODS: This study describes the implications of deficiency of System xc- on glucose metabolism in both constitutive and myeloid cell-specific knockout mice using metabolic tests and diet-induced obesity. Pancreatic islets were isolated and analysed for beta cell function, glutathione levels and ER stress. RESULTS: Constitutive System xc- deficiency led to an approximately threefold decrease in glutathione levels in the pancreatic islets as well as cystine shortage characterised by upregulation of Chac1. This shortage further manifested as downregulation of beta cell identity genes and a tonic increase in endoplasmic reticulum stress markers, which resulted in diminished insulin secretion both in vitro and in vivo. Myeloid-specific deletion did not have a significant impact on metabolism or islet function. CONCLUSIONS/INTERPRETATION: These findings suggest that System xc- is required for glutathione maintenance and insulin production in beta cells and that the system is dispensable for islet macrophage function.
Asunto(s)
Cistina , Ácido Glutámico , Ratones , Animales , Cistina/metabolismo , Ácido Glutámico/metabolismo , Secreción de Insulina , Antiportadores/metabolismo , Ratones Noqueados , Glutatión/metabolismoRESUMEN
AIMS/HYPOTHESIS: Colony stimulating factor 1 (CSF1) promotes the proliferation, differentiation and survival of macrophages, which have been implicated in both beneficial and detrimental effects on glucose metabolism. However, the physiological role of CSF1 signalling in glucose homeostasis and the potential therapeutic implications of modulating this pathway are not known. We aimed to study the composition of tissue macrophages (and other immune cells) following CSF1 receptor (CSF1R) inhibition and elucidate the metabolic consequences of CSF1R inhibition. METHODS: We assessed immune cell populations in various organs by flow cytometry, and tissue-specific metabolic effects by hyperinsulinaemic-euglycaemic clamps and insulin secretion assays in mice fed a chow diet containing PLX5622 (a CSF1R inhibitor) or a control diet. RESULTS: CSF1R inhibition depleted macrophages in multiple tissues while simultaneously increasing eosinophils and group 2 innate lymphoid cells. These immunological changes were consistent across different organs and were sex independent and reversible after cessation of the PLX5622. CSF1R inhibition improved hepatic insulin sensitivity but concomitantly impaired insulin secretion. In healthy islets, we found a high frequency of IL-1ß+ islet macrophages. Their depletion by CSF1R inhibition led to downregulation of macrophage-related pathways and mediators of cytokine activity, including Nlrp3, suggesting IL-1ß as a candidate insulin secretagogue. Partial restoration of physiological insulin secretion was achieved by injecting recombinant IL-1ß prior to glucose stimulation in mice lacking macrophages. CONCLUSIONS/INTERPRETATION: Macrophages and macrophage-derived factors, such as IL-1ß, play an important role in physiological insulin secretion. A better understanding of the tissue-specific effects of CSF1R inhibition on immune cells and glucose homeostasis is crucial for the development of targeted immune-modulatory treatments in metabolic disease. DATA AVAILABILITY: The RNA-Seq dataset is available in the Gene Expression Omnibus (GEO) under the accession number GSE189434 ( http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE189434 ).
Asunto(s)
Inmunidad Innata , Linfocitos , Ratones , Animales , Macrófagos/metabolismo , Glucosa/metabolismoRESUMEN
BACKGROUND: Air pollution has emerged as an unexpected risk factor for diabetes. However, the mechanism behind remains ill-defined. So far, the lung has been considered as the main target organ of air pollution. In contrast, the gut has received little scientific attention. Since air pollution particles can reach the gut after mucociliary clearance from the lungs and through contaminated food, our aim was to assess whether exposure deposition of air pollution particles in the lung or the gut drive metabolic dysfunction in mice. METHODS: To study the effects of gut versus lung exposure, we exposed mice on standard diet to diesel exhaust particles (DEP; NIST 1650b), particulate matter (PM; NIST 1649b) or phosphate-buffered saline by either intratracheal instillation (30 µg 2 days/week) or gavage (12 µg 5 days/week) over at least 3 months (total dose of 60 µg/week for both administration routes, equivalent to a daily inhalation exposure in humans of 160 µg/m3 PM2.5) and monitored metabolic parameters and tissue changes. Additionally, we tested the impact of the exposure route in a "prestressed" condition (high-fat diet (HFD) and streptozotocin (STZ)). RESULTS: Mice on standard diet exposed to particulate air pollutants by intratracheal instillation developed lung inflammation. While both lung and gut exposure resulted in increased liver lipids, glucose intolerance and impaired insulin secretion was only observed in mice exposed to particles by gavage. Gavage with DEP created an inflammatory milieu in the gut as shown by up-regulated gene expression of pro-inflammatory cytokines and monocyte/macrophage markers. In contrast, liver and adipose inflammation markers were not increased. Beta-cell secretory capacity was impaired on a functional level, most likely induced by the inflammatory milieu in the gut, and not due to beta-cell loss. The differential metabolic effects of lung and gut exposures were confirmed in a "prestressed" HFD/STZ model. CONCLUSIONS: We conclude that separate lung and gut exposures to air pollution particles lead to distinct metabolic outcomes in mice. Both exposure routes elevate liver lipids, while gut exposure to particulate air pollutants specifically impairs beta-cell secretory capacity, potentially instigated by an inflammatory milieu in the gut.
Asunto(s)
Contaminantes Atmosféricos , Contaminación del Aire , Humanos , Ratones , Animales , Contaminantes Atmosféricos/toxicidad , Contaminantes Atmosféricos/análisis , Pulmón , Material Particulado/toxicidad , Emisiones de Vehículos/toxicidad , LípidosRESUMEN
BACKGROUND: We previously found that air pollution particles reaching the gastrointestinal tract elicit gut inflammation as shown by up-regulated gene expression of pro-inflammatory cytokines and monocyte/macrophage markers. This inflammatory response was associated with beta-cell dysfunction and glucose intolerance. So far, it remains unclear whether gut inflammatory changes upon oral air pollution exposure are causally linked to the development of diabetes. Hence, our aim was to assess the role of immune cells in mediating glucose intolerance instigated by orally administered air pollutants. METHODS: To assess immune-mediated mechanisms underlying air pollution-induced glucose intolerance, we administered diesel exhaust particles (DEP; NIST 1650b, 12 µg five days/week) or phosphate-buffered saline (PBS) via gavage for up to 10 months to wild-type mice and mice with genetic or pharmacological depletion of innate or adaptive immune cells. We performed unbiased RNA-sequencing of intestinal macrophages to elucidate signaling pathways that could be pharmacologically targeted and applied an in vitro approach to confirm these pathways. RESULTS: Oral exposure to air pollution particles induced an interferon and inflammatory signature in colon macrophages together with a decrease of CCR2- anti-inflammatory/resident macrophages. Depletion of macrophages, NLRP3 or IL-1ß protected mice from air pollution-induced glucose intolerance. On the contrary, Rag2-/- mice lacking adaptive immune cells developed pronounced gut inflammation and glucose intolerance upon oral DEP exposure. CONCLUSION: In mice, oral exposure to air pollution particles triggers an immune-mediated response in intestinal macrophages that contributes to the development of a diabetes-like phenotype. These findings point towards new pharmacologic targets in diabetes instigated by air pollution particles.
Asunto(s)
Intolerancia a la Glucosa , Emisiones de Vehículos , Ratones , Animales , Emisiones de Vehículos/toxicidad , Proteína con Dominio Pirina 3 de la Familia NLR/genética , Intolerancia a la Glucosa/inducido químicamente , Inflamación , Inmunidad InnataRESUMEN
AIMS/HYPOTHESIS: Aggregation of the beta cell secretory product human islet amyloid polypeptide (hIAPP) results in islet amyloid deposition, a pathological feature of type 2 diabetes. Amyloid formation is associated with increased levels of islet IL-1ß as well as beta cell dysfunction and death, but the mechanisms that promote amyloid deposition in situ remain unclear. We hypothesised that physiologically relevant concentrations of IL-1ß stimulate beta cell islet amyloid polypeptide (IAPP) release and promote amyloid formation. METHODS: We used a humanised mouse model of endogenous beta cell hIAPP expression to examine whether low (pg/ml) concentrations of IL-1ß promote islet amyloid formation in vitro. Amyloid-forming islets were cultured for 48 h in the presence or absence of IL-1ß with or without an IL-1ß neutralising antibody. Islet morphology was assessed by immunohistochemistry and islet mRNA expression, hormone content and release were also quantified. Cell-free thioflavin T assays were used to monitor hIAPP aggregation kinetics in the presence and absence of IL-1ß. RESULTS: Treatment with a low concentration of IL-1ß (4 pg/ml) for 48 h increased islet amyloid prevalence (93.52 ± 3.89% vs 43.83 ± 9.67% amyloid-containing islets) and amyloid severity (4.45 ± 0.82% vs 2.16 ± 0.50% amyloid area/islet area) in hIAPP-expressing mouse islets in vitro. This effect of IL-1ß was reduced when hIAPP-expressing islets were co-treated with an IL-1ß neutralising antibody. Cell-free hIAPP aggregation assays showed no effect of IL-1ß on hIAPP aggregation in vitro. Low concentration IL-1ß did not increase markers of the unfolded protein response (Atf4, Ddit3) or alter proIAPP processing enzyme gene expression (Pcsk1, Pcsk2, Cpe) in hIAPP-expressing islets. However, release of IAPP and insulin were increased over 48 h in IL-1ß-treated vs control islets (IAPP 0.409 ± 0.082 vs 0.165 ± 0.051 pmol/5 islets; insulin 87.5 ± 8.81 vs 48.3 ± 17.3 pmol/5 islets), and this effect was blocked by co-treatment with IL-1ß neutralising antibody. CONCLUSIONS/INTERPRETATION: Under amyloidogenic conditions, physiologically relevant levels of IL-1ß promote islet amyloid formation by increasing beta cell release of IAPP. Neutralisation of this effect of IL-1ß may decrease the deleterious effects of islet amyloid formation on beta cell function and survival.
Asunto(s)
Interleucina-1beta/farmacología , Amiloidosis/tratamiento farmacológico , Animales , Humanos , Insulina/metabolismo , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , Polipéptido Amiloide de los Islotes Pancreáticos/metabolismo , RatonesRESUMEN
AIMS/HYPOTHESIS: Islet amyloid deposits contribute to beta cell dysfunction and death in most individuals with type 2 diabetes but non-invasive methods to determine the presence of these pathological protein aggregates are currently not available. Therefore, we examined whether florbetapir, a radiopharmaceutical agent used for detection of amyloid-ß deposits in the brain, also allows identification of islet amyloid in the pancreas. METHODS: Saturation binding assays were used to determine the affinity of florbetapir for human islet amyloid polypeptide (hIAPP) aggregates in vitro. Islet amyloid-prone transgenic mice that express hIAPP in their beta cells and amyloid-free non-transgenic control mice were used to examine the ability of florbetapir to detect islet amyloid deposits in vitro, in vivo and ex vivo. Mice or mouse pancreases were subjected to autoradiographic, histochemical and/or positron emission tomography (PET) analyses to assess the utility of florbetapir in identifying islet amyloid. RESULTS: In vitro, florbetapir bound synthetic hIAPP fibrils with a dissociation constant of 7.9 nmol/l. Additionally, florbetapir bound preferentially to amyloid-containing hIAPP transgenic vs amyloid-free non-transgenic mouse pancreas sections in vitro, as determined by autoradiography (16,475 ± 5581 vs 5762 ± 575 density/unit area, p < 0.05). In hIAPP transgenic and non-transgenic mice fed a high-fat diet for 1 year, intravenous administration of florbetapir followed by PET scanning showed that the florbetapir signal was significantly higher in amyloid-laden hIAPP transgenic vs amyloid-free non-transgenic pancreases in vivo during the first 5 min of the scan (36.83 ± 2.22 vs 29.34 ± 2.03 standardised uptake value × min, p < 0.05). Following PET, pancreases were excised and florbetapir uptake was determined ex vivo by γ counting. Pancreatic uptake of florbetapir was significantly correlated with the degree of islet amyloid deposition, the latter assessed by histochemistry (r = 0.74, p < 0.001). CONCLUSIONS/INTERPRETATION: Florbetapir binds to islet amyloid deposits in a specific and quantitative manner. In the future, florbetapir may be useful as a non-invasive tool to identify islet amyloid deposits in humans.
Asunto(s)
Amiloide/química , Compuestos de Anilina/farmacología , Glicoles de Etileno/farmacología , Islotes Pancreáticos/diagnóstico por imagen , Tomografía de Emisión de Positrones , Animales , Composición Corporal , Calorimetría Indirecta , Radioisótopos de Flúor/farmacología , Regulación de la Expresión Génica , Técnica de Clampeo de la Glucosa , Prueba de Tolerancia a la Glucosa , Hipotálamo/metabolismo , Insulina/metabolismo , Resistencia a la Insulina , Ligandos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Reacción en Cadena de la Polimerasa , Proteína Tirosina Fosfatasa no Receptora Tipo 1/metabolismo , Transducción de SeñalRESUMEN
AIMS/HYPOTHESIS: The S20G human islet amyloid polypeptide (hIAPP) substitution is associated with an earlier onset of type 2 diabetes in humans. Studies of synthetic S20G hIAPP in cell-free systems and immortalised beta cells have suggested that this may be due to increased hIAPP amyloidogenicity and cytotoxicity. Thus, using primary islets from mice with endogenous S20G hIAPP expression, we sought to determine whether the S20G gene mutation leads to increased amyloid-induced toxicity, beta cell loss and reduced beta cell function. METHODS: Islets from mice in which mouse Iapp was replaced with human wild-type or S20G hIAPP were isolated and cultured in vitro under amyloid-forming conditions. Levels of insulin and hIAPP mRNA and protein, amyloid deposition and beta cell apoptosis and area, as well as glucose-stimulated insulin and hIAPP secretion, were quantified. RESULTS: Islets expressing S20G hIAPP cultured in 16.7 mmol/l glucose demonstrated increased amyloid deposition and beta cell apoptosis, reduced beta cell area, decreased insulin content and diminished glucose-stimulated insulin secretion, compared with islets expressing wild-type hIAPP. Amyloid deposition and beta cell apoptosis were also increased when S20G islets were cultured in 11.1 mmol/l glucose (the concentration that is thought to be physiological for mouse islets). CONCLUSIONS/INTERPRETATION: S20G hIAPP reduces beta cell number and function, thereby possibly explaining the earlier onset of type 2 diabetes in individuals carrying this gene mutation.
Asunto(s)
Polipéptido Amiloide de los Islotes Pancreáticos/metabolismo , Islotes Pancreáticos/metabolismo , Amiloide/metabolismo , Animales , Apoptosis/efectos de los fármacos , Apoptosis/genética , Femenino , Glucosa/farmacología , Humanos , Técnicas In Vitro , Insulina/metabolismo , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , Polipéptido Amiloide de los Islotes Pancreáticos/química , Polipéptido Amiloide de los Islotes Pancreáticos/genética , Masculino , Ratones , Ratones Endogámicos C57BL , Mutación/genéticaRESUMEN
Deposition of human islet amyloid polypeptide (hIAPP, also known as amylin) as islet amyloid is a characteristic feature of the pancreas in type 2 diabetes, contributing to increased ß-cell apoptosis and reduced ß-cell mass. Matrix metalloproteinase-9 (MMP-9) is active in islets and cleaves hIAPP. We investigated whether hIAPP fragments arising from MMP-9 cleavage retain the potential to aggregate and cause toxicity, and whether overexpressing MMP-9 in amyloid-prone islets reduces amyloid burden and the resulting ß-cell toxicity. Synthetic hIAPP was incubated with MMP-9 and the major hIAPP fragments observed by MS comprised residues 1-15, 1-25, 16-37, 16-25, and 26-37. The fragments 1-15, 1-25, and 26-37 did not form amyloid fibrils in vitro and they were not cytotoxic when incubated with ß cells. Mixtures of these fragments with full-length hIAPP did not modulate the kinetics of fibril formation by full-length hIAPP. In contrast, the 16-37 fragment formed fibrils more rapidly than full-length hIAPP but was less cytotoxic. Co-incubation of MMP-9 and fragment 16-37 ablated amyloidogenicity, suggesting that MMP-9 cleaves hIAPP 16-37 into non-amyloidogenic fragments. Consistent with MMP-9 cleavage resulting in largely non-amyloidogenic degradation products, adenoviral overexpression of MMP-9 in amyloid-prone islets reduced amyloid deposition and ß-cell apoptosis. These findings suggest that increasing islet MMP-9 activity might be a strategy to limit ß-cell loss in type 2 diabetes.
Asunto(s)
Apoptosis/efectos de los fármacos , Diabetes Mellitus Tipo 2/metabolismo , Células Secretoras de Insulina/enzimología , Polipéptido Amiloide de los Islotes Pancreáticos/toxicidad , Metaloproteinasa 9 de la Matriz/metabolismo , Péptidos/toxicidad , Animales , Línea Celular , Supervivencia Celular/efectos de los fármacos , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/patología , Humanos , Células Secretoras de Insulina/patología , Metaloproteinasa 9 de la Matriz/genética , Ratones , Ratones TransgénicosRESUMEN
AIMS/HYPOTHESIS: Amyloid deposition and inflammation are characteristic of islet pathology in type 2 diabetes. The aim of this study was to determine whether islet amyloid formation is required for the development of islet inflammation in vivo. METHODS: Human islet amyloid polypeptide transgenic mice and non-transgenic littermates (the latter incapable of forming islet amyloid) were fed a low-fat (10%) or high-fat (60%) diet for 12 months; high-fat feeding induces islet amyloid formation in transgenic mice. At the conclusion of the study, glycaemia, beta cell function, islet amyloid deposition, markers of islet inflammation and islet macrophage infiltration were measured. RESULTS: Fasting plasma glucose levels did not differ by diet or genotype. Insulin release in response to i.v. glucose was significantly greater in both high vs low fat groups, and significantly lower in both transgenic compared with non-transgenic groups. Only high-fat-fed transgenic mice developed islet amyloid and showed a trend towards reduced beta cell area. Compared with islets from low-fat-fed transgenic or high-fat-fed non-transgenic mice, islets of high-fat-fed transgenic mice displayed a significant increase in the expression of genes encoding chemokines (Ccl2, Cxcl1), macrophage/dendritic cell markers (Emr1, Itgax), NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome components (Nlrp3, Pycard, Casp1) and proinflammatory cytokines (Il1b, Tnf, Il6), as well as increased F4/80 staining, consistent with increased islet inflammation and macrophage infiltration. CONCLUSIONS/INTERPRETATION: Our results indicate that islet amyloid formation is required for the induction of islet inflammation in this long-term high-fat-diet model, and thus could promote beta cell dysfunction in type 2 diabetes via islet inflammation.
Asunto(s)
Amiloide/inmunología , Amiloide/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Polipéptido Amiloide de los Islotes Pancreáticos/metabolismo , Animales , Glucemia/metabolismo , Proteínas de Unión al Calcio , Diabetes Mellitus Tipo 2/sangre , Grasas de la Dieta/efectos adversos , Ayuno/sangre , Genotipo , Humanos , Polipéptido Amiloide de los Islotes Pancreáticos/genética , Masculino , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Ratones , Ratones Transgénicos , Mucinas/genética , Mucinas/metabolismo , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismoRESUMEN
Loss of prolyl endopeptidase-like (PREPL) encoding a serine hydrolase with (thio)esterase activity leads to the recessive metabolic disorder Congenital Myasthenic Syndrome-22 (CMS22). It is characterized by severe neonatal hypotonia, feeding problems, growth retardation, and hyperphagia leading to rapid weight gain later in childhood. The phenotypic similarities with Prader-Willi syndrome (PWS) are striking, suggesting that similar pathways are affected. The aim of this study was to identify changes in the hypothalamic-pituitary axis in mouse models for both disorders and to examine mitochondrial function in skin fibroblasts of patients and knockout cell lines. We have demonstrated that Prepl is downregulated in the brains of neonatal PWS-IC-p/+m mice. In addition, the hypothalamic-pituitary axis is similarly affected in both Prepl-/- and PWS-IC-p/+m mice resulting in defective orexigenic signaling and growth retardation. Furthermore, we demonstrated that mitochondrial function is altered in PREPL knockout HEK293T cells and can be rescued with the supplementation of coenzyme Q10. Finally, PREPL-deficient and PWS patient skin fibroblasts display defective mitochondrial bioenergetics. The mitochondrial dysfunction in PWS fibroblasts can be rescued by overexpression of PREPL. In conclusion, we provide the first molecular parallels between CMS22 and PWS, raising the possibility that PREPL substrates might become therapeutic targets for treating both disorders.
Asunto(s)
Ratones Noqueados , Síndromes Miasténicos Congénitos , Síndrome de Prader-Willi , Prolil Oligopeptidasas , Animales , Humanos , Síndrome de Prader-Willi/metabolismo , Síndrome de Prader-Willi/genética , Síndrome de Prader-Willi/patología , Ratones , Síndromes Miasténicos Congénitos/genética , Síndromes Miasténicos Congénitos/metabolismo , Síndromes Miasténicos Congénitos/patología , Células HEK293 , Prolil Oligopeptidasas/metabolismo , Fibroblastos/metabolismo , Fibroblastos/patología , Mitocondrias/metabolismo , Mitocondrias/patología , Mitocondrias/genética , Redes y Vías Metabólicas/genética , Modelos Animales de Enfermedad , Ubiquinona/análogos & derivados , Ubiquinona/metabolismo , Serina Endopeptidasas/metabolismo , Serina Endopeptidasas/genética , Masculino , FemeninoRESUMEN
The dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin is an attractive therapy for diabetes, as it increases insulin release and may preserve ß-cell mass. However, sitagliptin also increases ß-cell release of human islet amyloid polypeptide (hIAPP), the peptide component of islet amyloid, which is cosecreted with insulin. Thus, sitagliptin treatment may promote islet amyloid formation and its associated ß-cell toxicity. Conversely, metformin treatment decreases islet amyloid formation by decreasing ß-cell secretory demand and could therefore offset sitagliptin's potential proamyloidogenic effects. Sitagliptin treatment has also been reported to be detrimental to the exocrine pancreas. We investigated whether long-term sitagliptin treatment, alone or with metformin, increased islet amyloid deposition and ß-cell toxicity and induced pancreatic ductal proliferation, pancreatitis, and/or pancreatic metaplasia/neoplasia. hIAPP transgenic and nontransgenic littermates were followed for 1 yr on no treatment, sitagliptin, metformin, or the combination. Islet amyloid deposition, ß-cell mass, insulin release, and measures of exocrine pancreas pathology were determined. Relative to untreated mice, sitagliptin treatment did not increase amyloid deposition, despite increasing hIAPP release, and prevented amyloid-induced ß-cell loss. Metformin treatment alone or with sitagliptin decreased islet amyloid deposition to a similar extent vs untreated mice. Ductal proliferation was not altered among treatment groups, and no evidence of pancreatitis, ductal metaplasia, or neoplasia were observed. Therefore, long-term sitagliptin treatment stimulates ß-cell secretion without increasing amyloid formation and protects against amyloid-induced ß-cell loss. This suggests a novel effect of sitagliptin to protect the ß-cell in type 2 diabetes that appears to occur without adverse effects on the exocrine pancreas.
Asunto(s)
Diabetes Mellitus Tipo 2/tratamiento farmacológico , Inhibidores de la Dipeptidil-Peptidasa IV/uso terapéutico , Células Secretoras de Insulina/efectos de los fármacos , Polipéptido Amiloide de los Islotes Pancreáticos/biosíntesis , Placa Amiloide/prevención & control , Pirazinas/uso terapéutico , Triazoles/uso terapéutico , Animales , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patología , Inhibidores de la Dipeptidil-Peptidasa IV/efectos adversos , Quimioterapia Combinada/efectos adversos , Hemicigoto , Humanos , Hipoglucemiantes/efectos adversos , Hipoglucemiantes/uso terapéutico , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patología , Polipéptido Amiloide de los Islotes Pancreáticos/genética , Polipéptido Amiloide de los Islotes Pancreáticos/metabolismo , Masculino , Metformina/efectos adversos , Metformina/uso terapéutico , Ratones , Ratones Transgénicos , Páncreas/efectos de los fármacos , Páncreas/metabolismo , Páncreas/patología , Neoplasias Pancreáticas/inducido químicamente , Pancreatitis/inducido químicamente , Pirazinas/efectos adversos , Distribución Aleatoria , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Fosfato de Sitagliptina , Factores de Tiempo , Triazoles/efectos adversosRESUMEN
System xc-, encoded by Slc7a11, is an antiporter responsible for exporting glutamate while importing cystine, which is essential for protein synthesis and the formation of thiol peptides, such as glutathione. Glutathione acts as a co-factor for enzymes responsible for scavenging reactive oxygen species. Upon exposure to bacterial products, macrophages exhibit a rapid upregulation of system xc-. This study investigates the impact of Slc7a11 deficiency on the functionality of peritoneal and bone marrow-derived macrophages. Our findings reveal that the absence of Slc7a11 results in significantly reduced glutathione levels, compromised mitochondrial flexibility, and hindered cytokine production in bone marrow-derived macrophages. Conversely, system xc- has a lesser impact on peritoneal macrophages in vivo. These results indicate that system xc- is essential for maintaining glutathione levels, mitochondrial functionality, and cytokine production, with a heightened importance under atmospheric oxygen tension.
Asunto(s)
Cistina , Ácido Glutámico , Ácido Glutámico/metabolismo , Cistina/metabolismo , Antiportadores , Macrófagos Peritoneales/metabolismo , Glutatión/metabolismo , Citocinas/metabolismo , Sistema de Transporte de Aminoácidos y+/genética , Sistema de Transporte de Aminoácidos y+/metabolismoRESUMEN
Diabetes mellitus is a disease of the hormone-secreting endocrine pancreas. However, increasing evidence suggests that the exocrine pancreas is also involved in the pathogenesis of diabetes. In this protocol, we describe how to harvest both isolated islets and exocrine tissue from one mouse pancreas, followed by a detailed explanation of how to isolate and analyze immune cells using full-spectrum flow cytometry.
Asunto(s)
Islotes Pancreáticos , Páncreas Exocrino , Ratones , Animales , Citometría de FlujoRESUMEN
Defective insulin processing is associated with obesity and diabetes. Prohormone convertase 1/3 (PC1/3) is an endopeptidase required for the processing of neurotransmitters and hormones. PC1/3 deficiency and genome-wide association studies relate PC1/3 with early onset obesity. Here, we find that deletion of PC1/3 in obesity-related neuronal cells expressing proopiomelanocortin mildly and transiently change body weight and fail to produce a phenotype when targeted to Agouti-related peptide- or nestin-expressing tissues. In contrast, pancreatic ß cell-specific PC1/3 ablation induces hyperphagia with consecutive obesity despite uncontrolled diabetes with glucosuria. Obesity develops not due to impaired pro-islet amyloid polypeptide processing but due to impaired insulin maturation. Proinsulin crosses the blood-brain-barrier but does not induce central satiety. Accordingly, insulin therapy prevents hyperphagia. Further, islet PC1/3 expression levels negatively correlate with body mass index in humans. In this work, we show that impaired PC1/3-mediated proinsulin processing, as observed in human prediabetes, promotes hyperphagic obesity.
Asunto(s)
Diabetes Mellitus , Proinsulina , Estudio de Asociación del Genoma Completo , Humanos , Hiperfagia/genética , Insulina/metabolismo , Obesidad/complicaciones , Obesidad/genética , Obesidad/metabolismo , Proinsulina/genética , Proinsulina/metabolismo , Proproteína Convertasa 1/genéticaRESUMEN
The initial cephalic phase of insulin secretion is mediated through the vagus nerve and is not due to glycemic stimulation of pancreatic ß cells. Recently, IL-1ß was shown to stimulate postprandial insulin secretion. Here, we describe that this incretin-like effect of IL-1ß involves neuronal transmission. Furthermore, we found that cephalic phase insulin release was mediated by IL-1ß originating from microglia. Moreover, IL-1ß activated the vagus nerve to induce insulin secretion and regulated the activity of the hypothalamus in response to cephalic stimulation. Notably, cephalic phase insulin release was impaired in obesity, in both mice and humans, and in mice, this was due to dysregulated IL-1ß signaling. Our findings attribute a regulatory role to IL-1ß in the integration of nutrient-derived sensory information, subsequent neuronally mediated insulin secretion, and the dysregulation of autonomic cephalic phase responses in obesity.
Asunto(s)
Células Secretoras de Insulina , Insulina , Interleucina-1beta , Animales , Glucemia/metabolismo , Insulina/metabolismo , Secreción de Insulina , Células Secretoras de Insulina/metabolismo , Interleucina-1beta/metabolismo , Ratones , Obesidad/metabolismoRESUMEN
The obesity epidemic continues to worsen worldwide. However, the mechanisms initiating glucose dysregulation in obesity remain poorly understood. We assessed the role that colonic macrophage subpopulations play in glucose homeostasis in mice fed a high-fat diet (HFD). Concurrent with glucose intolerance, pro-inflammatory/monocyte-derived colonic macrophages increased in mice fed a HFD. A link between macrophage numbers and glycemia was established by pharmacological dose-dependent ablation of macrophages. In particular, colon-specific macrophage depletion by intrarectal clodronate liposomes improved glucose tolerance, insulin sensitivity, and insulin secretion capacity. Colonic macrophage activation upon HFD was characterized by an interferon response and a change in mitochondrial metabolism, which converged in mTOR as a common regulator. Colon-specific mTOR inhibition reduced pro-inflammatory macrophages and ameliorated insulin secretion capacity, similar to colon-specific macrophage depletion, but did not affect insulin sensitivity. Thus, pharmacological targeting of colonic macrophages could become a potential therapy in obesity to improve glycemic control.
Asunto(s)
Dieta Alta en Grasa , Resistencia a la Insulina , Animales , Glucemia/metabolismo , Colon/metabolismo , Dieta Alta en Grasa/efectos adversos , Control Glucémico , Macrófagos/metabolismo , Ratones , Obesidad/etiología , Obesidad/metabolismo , Serina-Treonina Quinasas TOR/metabolismoRESUMEN
Aging is the prime risk factor for the development of type 2 diabetes. We investigated the role of the interleukin-1 (IL-1) system on insulin secretion in aged mice. During aging, expression of the protective IL-1 receptor antagonist decreased in islets, whereas IL-1beta gene expression increased specifically in the CD45 + islet immune cell fraction. One-year-old mice with a whole-body knockout of IL-1beta had higher insulin secretion in vivo and in isolated islets, along with enhanced proliferation marker Ki67 and elevated size and number of islets. Myeloid cell-specific IL-1beta knockout preserved glucose-stimulated insulin secretion during aging, whereas it declined in control mice. Isolated islets from aged myeloIL-1beta ko mice secreted more insulin along with increased expression of Ins2, Kir6.2, and of the cell-cycle gene E2f1. IL-1beta treatment of isolated islets reduced E2f1, Ins2, and Kir6.2 expression in beta cells. We conclude that IL-1beta contributes the age-associated decline of beta cell function.
RESUMEN
Gestational diabetes mellitus (GDM) is one of the most common diseases associated with pregnancy, however, the underlying mechanisms remain unclear. Based on the well documented role of inflammation in type 2 diabetes, the aim was to investigate the role of inflammation in GDM. We established a mouse model for GDM on the basis of its two major risk factors, obesity and aging. In these GDM mice, we observed increased Interleukin-1ß (IL-1ß) expression in the uterus and the placenta along with elevated circulating IL-1ß concentrations compared to normoglycemic pregnant mice. Treatment with an anti-IL-1ß antibody improved glucose-tolerance of GDM mice without apparent deleterious effects for the fetus. Finally, IL-1ß antagonism showed a tendency for reduced plasma corticosterone concentrations, possibly explaining the metabolic improvement. We conclude that IL-1ß is a causal driver of impaired glucose tolerance in GDM.