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1.
Trends Immunol ; 40(8): 762-780, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31320280

RESUMO

Amyloid formation contributes to the development of progressive metabolic and neurodegenerative diseases, while also serving functional roles in host defense. Emerging evidence suggests that as amyloidogenic peptides populate distinct aggregation states, they interact with different combinations of pattern recognition receptors (PRRs) to direct the phenotype and function of tissue-resident and infiltrating innate immune cells. We review recent evidence of innate immunomodulation by distinct forms of amyloidogenic peptides produced by mammals (humans, non-human primates), bacteria, and fungi, as well as the corresponding cell-surface and intracellular PRRs in these interactions, in human and mouse models. Our emerging understanding of peptide aggregate-innate immune cell interactions, and the factors regulating the balance between amyloid function and pathogenicity, might aid the development of anti-amyloid and immunomodulating therapies.

2.
J Child Adolesc Psychopharmacol ; 29(8): 615-624, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31170001

RESUMO

Objective: To evaluate the lifetime prevalence of infectious, inflammatory, and autoimmune disorders in a multisite study of probands with childhood-onset obsessive compulsive disorder (OCD) and their first-degree relatives. Methods: Medical questionnaires were completed by 1401 probands and 1045 first-degree relatives in the OCD Collaborative Genetics Association Study. Lifetime prevalence of immune-related diseases was compared with the highest available population estimate and reported as a point estimate with 95% adjusted Wald interval. Worst-episode OCD severity and symptom dimensions were assessed with the Yale-Brown Obsessive Compulsive Scale (YBOCS) and Symptom Checklist (YBOCS-CL). Results: Probands reported higher-than-expected prevalence of scarlet fever (4.0 [3.1-5.2]% vs. 1.0%-2.0%, z = 1.491, p < 0.001, n = 1389), encephalitis or meningitis (1.4 [0.9-2.1]% vs. 0.1%-0.4%, z = 5.913, p < 0.001, n = 1393), rheumatoid arthritis (1.1 [0.6-2.0]% vs. 0.2%-0.4%, z = 3.416, p < 0.001, n = 949) and rheumatic fever (0.6 [0.3-1.2]% vs. 0.1%-0.2%, z = 3.338, p < 0.001, n = 1390), but not systemic lupus erythematosus, diabetes, asthma, multiple sclerosis, psoriasis, or inflammatory bowel disease. First-degree relatives reported similarly elevated rates of scarlet fever, rheumatic fever, and encephalitis or meningitis independent of OCD status. There was no association between worst-episode severity and immune-related comorbidities, although probands reporting frequent ear or throat infections had increased severity of cleaning-/contamination-related symptoms (mean factor score 2.5 ± 0.9 vs. 2.3 ± 1.0, t = 3.183, p = 0.002, n = 822). Conclusion: These data suggest high rates of streptococcal-related and other immune-mediated diseases in patients with childhood-onset OCD and are consistent with epidemiological studies in adults noting familial clustering. Limitations include potential reporting bias and absence of a control group, underscoring the need for further prospective studies characterizing medical and psychiatric disease clusters and their interactions in children. Such studies may ultimately improve our understanding of OCD pathogenesis and aid in the development of adjunctive immune-modulating therapeutic strategies.

3.
Pediatr Rheumatol Online J ; 17(1): 22, 2019 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-31088470

RESUMO

Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease in Canada and is characterized by a clinical syndrome of episodic inflammatory symptoms. Traditionally, the disease is defined by autosomal recessive inheritance of MEFV gene variants, yet FMF also not uncommonly manifests in individuals with only one identified disease-associated allele. Increasing availability and affordability of gene sequencing has led to the identification of multiple MEFV variants; however, they are often of unknown clinical significance. Variants in other genes affecting overlapping or distinct inflammatory signaling pathways - together with gene-environment interactions including epigenetic modulation - likely underlie the significant genetic and phenotypic heterogeneity seen among patients with this disease. We review recent evidence of the expanding spectrum of FMF genotype and phenotype and suggest that current drug funding schemes restricting biologic agents to patients with homozygous mutations have not kept pace with our biological understanding of the disease.


Assuntos
Febre Familiar do Mediterrâneo/genética , Terapia Biológica/métodos , Criança , Febre Familiar do Mediterrâneo/diagnóstico , Febre Familiar do Mediterrâneo/terapia , Genótipo , Humanos , Mutação/genética , Pirina/genética , Pirina/metabolismo
4.
Indian J Psychiatry ; 61(Suppl 1): S119-S130, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30745685

RESUMO

Obsessive-compulsive disorder (OCD) affects 1%-3% of children worldwide and has a profound impact on quality of life for patients and families. Although our understanding of the underlying etiology remains limited, data from neuroimaging and genetic studies as well as the efficacy of serotonergic medications suggest the disorder is associated with the fundamental alterations in the function of cortico-striato-thalamocortical circuits. Significant delays to diagnosis are common, ultimately leading to more severe functional impairment with long-term developmental consequences. The clinical assessment requires a detailed history of specific OCD symptoms as well as psychiatric and medical comorbidities. Standardized assessment tools may aid in evaluating and tracking symptom severity and both individual and family functioning. In the majority of children, an interdisciplinary approach that combines cognitive behavioral therapy with a serotonin reuptake inhibitor leads to meaningful symptom improvement, although some patients experience a chronic, episodic course. There are limited data to guide the management of treatment-refractory illness in children, although atypical antipsychotics and glutamate-modulating agents may be used cautiously as augmenting agents. This review outlines a clinical approach to the diagnosis and management of OCD, highlighting associated challenges, and limitations to our current knowledge.

5.
Pediatr Rheumatol Online J ; 15(1): 61, 2017 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-28784150

RESUMO

BACKGROUND: Because pediatric antineutrophil cytoplasmic antibody-associated vasculitis is rare, management generally relies on adult data. We assessed treatment practices, uptake of existing clinical assessment tools, and interest in pediatric treatment protocols among rheumatologists caring for children with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). METHODS: A needs-assessment survey developed by an international working group of pediatric rheumatologists and two nephrologists was circulated internationally. Data were summarized with descriptive statistics. Pearson's chi-square tests were used in inferential univariate analyses. RESULTS: The 209 respondents from 36 countries had collectively seen ~1600 children with GPA/MPA; 144 had seen more than two in the preceding 5 years. Standardized and validated clinical assessment tools to score disease severity, activity, and damage were used by 59, 63, and 36%, respectively; barriers to use included lack of knowledge and limited perceived utility. Therapy varied significantly: use of rituximab rather than cyclophosphamide was more common among respondents from the USA (OR = 2.7 [1.3-5.5], p = 0.0190, n = 139), those with >5 years of independent practice experience (OR = 3.8 [1.3-12.5], p = 0.0279, n = 137), and those who had seen >10 children with GPA/MPA in their careers (OR = 4.39 [2.1-9.1], p = 0.0011, n = 133). Respondents who had treated >10 patients were also more likely to continue maintenance therapy for at least 24 months (OR = 3.0 [1.4-6.4], p = 0.0161, n = 127). Ninety six percent of respondents believed in a need for pediatric-specific treatment guidelines; 46% supported adaptation of adult guidelines while 69% favoured guidelines providing a limited range of treatment options to allow comparison of effectiveness through a registry. CONCLUSIONS: These data provide a rationale for developing pediatric-specific consensus treatment guidelines for GPA/MPA. While pediatric rheumatologist uptake of existing clinical tools has been limited, guideline uptake may be enhanced if outcomes of consensus-derived treatment options are evaluated within the framework of an international registry.


Assuntos
Vasculite Associada a Anticorpo Anticitoplasma de Neutrófilos/tratamento farmacológico , Conhecimentos, Atitudes e Prática em Saúde , Padrões de Prática Médica/estatística & dados numéricos , Criança , Guias como Assunto , Inquéritos Epidemiológicos , Humanos , Pediatria , Reumatologistas
6.
Diabetologia ; 59(6): 1242-6, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26970755

RESUMO

AIMS/HYPOTHESIS: Islet amyloid, a pathological feature of type 2 diabetes, forms from the aggregation of islet amyloid polypeptide (IAPP), a beta cell peptide that is produced and co-secreted with insulin. Cholesterol regulates amyloid-ß processing, deposition and clearance, promoting amyloidogenesis in the brain. ATP-binding cassette transporter 1 (ABCA1) is a cholesterol efflux transporter that when absent increases and when overexpressed reduces brain amyloid-ß deposition in mouse models of Alzheimer's disease. We examined whether alterations in ABCA1 expression and islet cholesterol content could also modulate islet amyloidogenesis. METHODS: Thioflavin S staining for amyloid was performed in islets isolated from mice with beta cell expression of human IAPP (hIAPP (Tg/o)) and cultured for 8 days following cholesterol loading, microRNA-33 overexpression (to reduce ABCA1 expression) or palmitate treatment in the presence or absence of ABCA1 overexpression or mevastatin treatment (to reduce cholesterol synthesis). hIAPP (Tg/o) mice were crossed with beta cell-specific Abca1-knockout mice (hIAPP (Tg/o) Abca1 (ßKO)) and glucose tolerance and amyloid formation were assessed. RESULTS: Cholesterol loading and microRNA-33-induced reduction in islet ABCA1 expression increased Thioflavin S-positive amyloid in hIAPP (Tg/o) islets. Palmitate treatment also increased amyloid formation and this was reduced by both ABCA1 overexpression and mevastatin treatment. hIAPP (Tg/o) Abca1 (ßKO) mice had increased islet cholesterol, accompanied by fasting hyperglycaemia, glucose intolerance, impaired in vivo insulin secretion and an increased islet proinsulin:insulin ratio. Amyloid area was increased in cultured hIAPP (Tg/o) Abca1 (ßKO) islets compared with hIAPP (Tg/o) controls. CONCLUSIONS/INTERPRETATION: These data suggest that elevations in islet cholesterol may lead to increases in IAPP aggregation and islet amyloid formation, further worsening beta cell function and glucose homeostasis.


Assuntos
Transportador 1 de Cassete de Ligação de ATP/deficiência , Amiloidose/metabolismo , Amiloidose/patologia , Colesterol/metabolismo , Transportador 1 de Cassete de Ligação de ATP/genética , Amiloide/metabolismo , Animais , Humanos , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/metabolismo , Polipeptídeo Amiloide das Ilhotas Pancreáticas/genética , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/patologia , Lovastatina/análogos & derivados , Lovastatina/farmacologia , Masculino , Camundongos , MicroRNAs/genética , MicroRNAs/metabolismo , Palmitatos/farmacologia , Ratos
7.
J Biol Chem ; 291(17): 8908-17, 2016 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-26786104

RESUMO

Aggregation of islet amyloid polypeptide (IAPP) contributes to beta cell dysfunction in type 2 diabetes and islet transplantation. Like other amyloidogenic peptides, human IAPP induces macrophage IL-1ß secretion by stimulating both the synthesis and processing of proIL-1ß, a pro-inflammatory cytokine that (when chronically elevated) impairs beta cell insulin secretion. We sought to determine the specific mechanism of IAPP-induced proIL-1ß synthesis. Soluble IAPP species produced early during IAPP aggregation provided a Toll-like-receptor-2- (TLR2-) dependent stimulus for NF-κB activation in HEK 293 cells and bone marrow-derived macrophages (BMDMs). Non-amyloidogenic rodent IAPP and thioflavin-T-positive fibrillar amyloid produced by human IAPP aggregation failed to activate TLR2. Blockade of TLR6 but not TLR1 prevented hIAPP-induced TLR2 activation, consistent with stimulation of a TLR2/6 heterodimer. TLR2 and its downstream adaptor protein MyD88 were required for IAPP-induced cytokine production by BMDMs, a process that is partially dependent on autoinduction by IL-1. BMDMs treated with soluble but not fibrillar IAPP provided a TLR2-dependent priming stimulus for ATP-induced IL-1ß secretion, whereas late IAPP aggregates induced NLRP3-dependent IL-1ß secretion by LPS-primed macrophages. Moreover, inhibition of TLR2 and depletion of islet macrophages prevented up-regulation of Il1b and Tnf expression in human IAPP-expressing transgenic mouse islets. These data suggest participation by both soluble and fibrillar aggregates in IAPP-induced islet inflammation. IAPP-induced activation of TLR2 and secretion of IL-1 may be important therapeutic targets to prevent amyloid-associated beta cell dysfunction.


Assuntos
Imunidade Inata , Células Secretoras de Insulina/imunologia , Polipeptídeo Amiloide das Ilhotas Pancreáticas/imunologia , Agregação Patológica de Proteínas/imunologia , Animais , Proteínas de Transporte/genética , Proteínas de Transporte/imunologia , Células HEK293 , Humanos , Células Secretoras de Insulina/patologia , Interleucina-1beta/genética , Interleucina-1beta/imunologia , Polipeptídeo Amiloide das Ilhotas Pancreáticas/genética , Lipopolissacarídeos/farmacologia , Camundongos , Camundongos Knockout , Proteína 3 que Contém Domínio de Pirina da Família NLR , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/patologia , Receptores Toll-Like/genética , Receptores Toll-Like/imunologia , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/imunologia
8.
Diabetologia ; 58(3): 575-85, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25491100

RESUMO

AIMS/HYPOTHESIS: Aggregation of islet amyloid polypeptide (IAPP) to form amyloid contributes to beta cell dysfunction in type 2 diabetes. Human but not non-amyloidogenic rodent IAPP induces islet macrophage proIL-1ß synthesis. We evaluated the effect of IL-1 receptor antagonist (IL-1Ra) on islet inflammation and dysfunction in a mouse model of type 2 diabetes with amyloid formation. METHODS: Lean and obese male mice (A/a or A(vy)/A at the agouti locus, respectively) with or without beta cell human IAPP expression (hIAPP(Tg/0)) were treated with PBS or IL-1Ra (50 mg kg(-1) day(-1)) from 16 weeks of age. Intraperitoneal glucose and insulin tolerance tests were performed after 8 weeks. Pancreases were harvested for histology and gene expression analysis. RESULTS: Aggregation of human IAPP was associated with marked upregulation of proinflammatory gene expression in islets of obese hIAPP(Tg/0) mice, together with amyloid deposition and fasting hyperglycaemia. IL-1Ra improved glucose tolerance and reduced plasma proinsulin:insulin in both lean and obese hIAPP(Tg/0) mice with no effect on insulin sensitivity. The severity and prevalence of islet amyloid was reduced by IL-1Ra in lean hIAPP (Tg/0) mice, suggesting a feed-forward mechanism by which islet inflammation promotes islet amyloid at the early stages of disease. IL-1Ra limited Il1a, Il1b, Tnf and Ccl2 expression in islets from obese hIAPP(Tg/0) mice, suggesting an altered islet inflammatory milieu. CONCLUSIONS/INTERPRETATION: These data provide the first in vivo evidence­using a transgenic mouse model with amyloid deposits resembling those found in human islets­that IAPP-induced beta cell dysfunction in type 2 diabetes may be mediated by IL-1. Anti-IL-1 therapies may limit islet inflammation and dysfunction associated with amyloid formation.


Assuntos
Amiloide/metabolismo , Interleucina-1/metabolismo , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Animais , Humanos , Imuno-Histoquímica , Inflamação/metabolismo , Interleucina-1/genética , Polipeptídeo Amiloide das Ilhotas Pancreáticas/genética , Ilhotas Pancreáticas/metabolismo , Masculino , Camundongos , Camundongos Transgênicos
9.
Diabetologia ; 57(8): 1645-54, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24816367

RESUMO

AIMS/HYPOTHESIS: Inflammation contributes to pancreatic beta cell dysfunction in type 2 diabetes. Toll-like receptor (TLR)-2 and -4 ligands are increased systemically in recently diagnosed type 2 diabetes patients, and TLR2- and TLR4-deficient mice are protected from the metabolic consequences of a high-fat diet. Here we investigated the role of macrophages in TLR2/6- and TLR4-mediated effects on islet inflammation and beta cell function. METHODS: Genetic and pharmacological approaches were used to determine the effects of TLR2/6 and TLR4 ligands on mouse islets, human islets and purified rat beta cells. Islet macrophages were depleted and sorted by flow cytometry and the effects of TLR2/6- and TLR4-activated bone-marrow-derived macrophages (BMDMs) on beta cell function were assessed. RESULTS: Macrophages contributed to TLR2/6- and TLR4-induced islet Il1a/IL1A and Il1b/IL1B mRNA expression in mouse and human islets and IL-1ß secretion from human islets. TLR2/6 and TLR4 ligands also reduced insulin gene expression; however, this occurred in a non-beta cell autonomous manner. TLR2/6- and TLR4-activated BMDMs reduced beta cell insulin secretion partly via reducing Ins1, Ins2, and Pdx1 mRNA expression. Antagonism of the IL-1 receptor and neutralisation of IL-6 completely reversed the effects of activated macrophages on beta cell gene expression. CONCLUSIONS/INTERPRETATION: We conclude that islet macrophages are major contributors to islet IL-1ß secretion in response to TLR2/6 and TLR4 ligands. BMDMs stimulated with TLR2/6 and TLR4 ligands reduce insulin secretion from pancreatic beta cells, partly via IL-1ß- and IL-6-mediated decreased insulin gene expression.


Assuntos
Células Secretoras de Insulina/metabolismo , Insulina/genética , Interleucina-1/metabolismo , Interleucina-6/metabolismo , Ilhotas Pancreáticas/metabolismo , Macrófagos/metabolismo , Receptores Toll-Like/metabolismo , Animais , Regulação da Expressão Gênica , Humanos , Insulina/metabolismo , Camundongos Knockout , Ratos , Receptores Toll-Like/genética
10.
J Biol Chem ; 289(17): 11807-15, 2014 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-24627476

RESUMO

Thioredoxin-interacting protein (TXNIP) is up-regulated by glucose and diabetes and plays a critical role in glucotoxicity, inflammation, and beta-cell apoptosis, whereas we have found that TXNIP deficiency protects against diabetes. Interestingly, human islet amyloid polypeptide (IAPP) is also induced by glucose, aggregates into insoluble amyloid fibrils found in islets of most individuals with type 2 diabetes and promotes inflammation and beta-cell cytotoxicity. However, so far no connection between TXNIP and IAPP signaling had been reported. Using TXNIP gain and loss of function experiments, INS-1 beta-cells and beta-cell-specific Txnip knock-out mice, we now found that TXNIP regulates IAPP expression. Promoter analyses and chromatin-immunoprecipitation assays further demonstrated that TXNIP increases IAPP expression at the transcriptional level, and we discovered that TXNIP-induced FoxA2 (forkhead box A2) transcription factor expression was conferring this effect by promoting FoxA2 enrichment at the proximal FoxA2 site in the IAPP promoter. Moreover, we found that TXNIP down-regulates miR-124a expression, a microRNA known to directly target FoxA2. Indeed, miR-124a overexpression led to decreased FoxA2 expression and IAPP promoter occupancy and to a significant reduction in IAPP mRNA and protein expression and also effectively inhibited TXNIP-induced IAPP expression. Thus, our studies have identified a novel TXNIP/miR-124a/FoxA2/IAPP signaling cascade linking the critical beta-cell signaling pathways of TXNIP and IAPP and thereby provide new mechanistic insight into an important aspect of transcriptional regulation and beta-cell biology.


Assuntos
Proteínas de Transporte/fisiologia , Fator 3-beta Nuclear de Hepatócito/fisiologia , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , MicroRNAs/fisiologia , Tiorredoxinas/fisiologia , Animais , Sequência de Bases , Proteínas de Transporte/genética , Linhagem Celular , Regulação para Baixo , Humanos , Camundongos , Camundongos Knockout , Ratos , Tiorredoxinas/genética , Transcrição Genética/fisiologia
11.
Immunol Cell Biol ; 92(4): 314-23, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24492799

RESUMO

The global health and economic burden of type 2 diabetes (T2D) has reached staggering proportions. Current projections estimate that 592 million people will have diabetes by 2035. T2D-which comprises 90% of cases-is a complex disease, in most cases resulting from a combination of predisposing genes and an unhealthy environment. Clinical onset of the disease occurs when pancreatic ß cells fail in the face of insulin resistance. It has long been appreciated that chronic activation of the innate immune system is associated with T2D, and many organs critical to the regulation of glucose homeostasis show signs of a chronic inflammatory process, including the pancreatic islets of Langerhans. Recent clinical trials using IL-1-targeting agents have confirmed that inflammation contributes to ß-cell failure in humans with T2D. However, little is known about the nature of the pro-inflammatory response within the islet, and there is considerable debate about the triggers for islet inflammation, which may be systemically derived and/or tissue-specific. In this review, we present evidence that Toll-like receptors 2 and 4 and the NLRP3 (Nucleotide-binding oligomerization domain, Leucine-rich Repeat and Pyrin domain containing 3) inflammasome are triggers for islet inflammation in T2D and propose that the activation of macrophages by these triggers mediates islet endocrine cell dysfunction. Therapeutically targeting these receptors may improve hyperglycemia and protect the ß cell in T2D.


Assuntos
Proteínas de Transporte/metabolismo , Diabetes Mellitus Tipo 2/imunologia , Diabetes Mellitus Tipo 2/patologia , Inflamação/imunologia , Inflamação/patologia , Ilhotas Pancreáticas/patologia , Receptores Toll-Like/metabolismo , Animais , Diabetes Mellitus Tipo 2/terapia , Humanos , Ilhotas Pancreáticas/imunologia , Macrófagos/patologia
12.
Diabetologia ; 57(3): 447-50, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24362729

RESUMO

Pancreatic beta cell failure dictates the clinical onset of type 2 diabetes, with insulin secretion insufficient to overcome peripheral tissue insulin resistance. Over the past 5-10 years, a convincing case has emerged supporting the contribution of islet inflammation to this beta cell failure. IL-1 is central to this insult, impairing insulin secretion in preclinical and clinical studies. Further, islet-infiltrating macrophages are a major source of IL-1 and other cytokines in response to elevated levels of nutrients (glucose, saturated fatty acids), endocannabinoids and islet amyloid polypeptide (IAPP). In this issue of Diabetologia, Butcher et al have further characterised immune cell subsets present in islets from individuals with type 2 diabetes (DOI: 10.1007/s00125-013-3116-5). Increased numbers of CD45(+) leucocytes were found in these islets compared with islets from healthy controls, with an elevated proportion of CD20(+) B cells within the CD45(+) population. Their data also suggest that absolute numbers of CD3(+) T cells and CD11b(+)CD11c(+) myeloid cells may be increased in islets from individuals with type 2 diabetes. While many aspects of islet inflammation await further exploration, the study from Butcher and colleagues suggests a role for immune cell-mediated inflammation early in disease pathogenesis, and supports the concept that targeting the immune system may slow continued beta cell demise in type 2 diabetes.


Assuntos
Quimiocina CCL2/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Inflamação/metabolismo , Insulina/metabolismo , Ilhotas Pancreáticas/imunologia , Leucócitos/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Humanos , Secreção de Insulina
13.
Diabetes ; 63(1): 12-9, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24357689

RESUMO

ß-Cell replacement by islet transplantation is a potential curative therapy for type 1 diabetes. Despite advancements in islet procurement and immune suppression that have increased islet transplant survival, graft function progressively declines, and many recipients return to insulin dependence within a few years posttransplant. The progressive loss of ß-cell function in islet transplants seems unlikely to be explained by allo- and autoimmune-mediated mechanisms alone and in a number of ways resembles ß-cell failure in type 2 diabetes. That is, both following transplantation and in type 2 diabetes, islets exhibit decreased first-phase glucose-stimulated insulin secretion, impaired proinsulin processing, inflammation, formation of islet amyloid, signs of oxidative and endoplasmic reticulum stress, and ß-cell death. These similarities suggest common mechanisms may underlie loss of insulin production in both type 2 diabetes and islet transplantation and point to the potential for therapeutic approaches used in type 2 diabetes that target the ß-cell, such as incretin-based therapies, as adjuncts for immunosuppression in islet transplantation.


Assuntos
Diabetes Mellitus Tipo 1/cirurgia , Diabetes Mellitus Tipo 2/fisiopatologia , Células Secretoras de Insulina/fisiologia , Transplante das Ilhotas Pancreáticas , Animais , Diabetes Mellitus Tipo 1/patologia , Diabetes Mellitus Tipo 1/fisiopatologia , Diabetes Mellitus Tipo 2/patologia , Diabetes Mellitus Tipo 2/cirurgia , Insulina/metabolismo , Células Secretoras de Insulina/patologia , Células Secretoras de Insulina/transplante
14.
Diabetes ; 63(5): 1698-711, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24222351

RESUMO

Islet amyloid polypeptide (IAPP) aggregates to form amyloid fibrils in patients with type 2 diabetes and acts as a potent stimulus for interleukin (IL)-1ß secretion by bone marrow-derived macrophages. We sought to determine the contribution of resident islet macrophages to IAPP-induced inflammation and ß-cell dysfunction. In cultured islets, macrophages (F4/80(+)CD11b(+)CD11c(+) cells) were required for IAPP-induced mRNA expression of the proinflammatory cytokines IL-1ß, tumor necrosis factor-α, and IL-6 and the anti-inflammatory cytokines IL-10 and IL-1 receptor antagonist. Moreover, IAPP-induced IL-1ß synthesis and caspase-1 activation were detected in macrophages but not other islet cell types. Transgenic mice with ß-cell human IAPP (hIAPP) expression had impaired glucose tolerance, elevated islet Il1b mRNA, and decreased Il10 and Il1rn expression following high-fat feeding. Islet macrophages were the major source of these transcripts and expressed increased cell surface Ly6C and CD11c in hIAPP transgenic mice. Clodronate liposome-mediated depletion of islet macrophages improved glucose tolerance and blocked proinflammatory gene expression in hIAPP-expressing mice, despite increasing the amount of islet amyloid. These data provide the first evidence that IAPP aggregates skew resident islet macrophages toward a proinflammatory phenotype and suggest a mechanism by which anti-inflammatory therapies may protect ß-cells from IAPP-induced islet dysfunction.


Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Células Secretoras de Insulina/metabolismo , Interleucina-1beta/biossíntese , Polipeptídeo Amiloide das Ilhotas Pancreáticas/farmacologia , Ilhotas Pancreáticas/metabolismo , Macrófagos/metabolismo , Animais , Citocinas/biossíntese , Diabetes Mellitus Tipo 2/patologia , Resistência à Insulina/fisiologia , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/patologia , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/patologia , Macrófagos/efeitos dos fármacos , Macrófagos/patologia , Camundongos , Camundongos Transgênicos , Obesidade/metabolismo , Obesidade/patologia
15.
Methods Mol Biol ; 1040: 9-18, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23852593

RESUMO

In addition to several other extracellular substances, phagocytosis of amyloid-forming peptides can perturb cellular homeostasis, leading to activation of the cytoplasmic innate immune receptor NLRP3. Once triggered, NLRP3 forms an inflammasome complex that ultimately cleaves pro-IL-1ß and pro-IL-18 into their mature, secreted forms. Here we describe a protocol by which one type of amyloidogenic peptide, islet amyloid polypeptide (IAPP, otherwise known as amylin) can be prepared and used to stimulate myeloid cells in vitro to engage the NLRP3 inflammasome. Methods for measuring the ensuing inflammasome activation are also described. Although initially soluble, IAPP monomers rapidly aggregate in solution to form oligomers and subsequently insoluble amyloid fibrils. More work is required to examine how this transition influences inflammasome activation for different types of amyloid. The course of amyloid formation and corresponding inflammatory capacity of these pre-fibrillar species following uptake also requires further examination, and we hope that our protocols are useful in these endeavors. While these protocols are restricted to examination of synthetic IAPP, isolation of IAPP aggregates from human and transgenic mouse pancreas will be required to definitively determine the proinflammatory effects of endogenous IAPP oligomers and fibrils.


Assuntos
Proteínas de Transporte/metabolismo , Inflamassomos/metabolismo , Polipeptídeo Amiloide das Ilhotas Pancreáticas/farmacologia , Animais , Caspase 1/metabolismo , Ativação Enzimática , Ensaio de Imunoadsorção Enzimática , Humanos , Interleucina-18/metabolismo , Interleucina-1beta/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , Microscopia de Fluorescência , Proteína 3 que Contém Domínio de Pirina da Família NLR
16.
Diabetes ; 62(8): 2808-20, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23656887

RESUMO

Cellular homeostasis requires intrinsic sensing mechanisms to temper function in the face of prolonged activity. In the pancreatic ß-cell, glucose is likely a physiological trigger that activates an adaptive response to stimulation, thereby maintaining cellular homeostasis. Immediate early genes (IEGs) are activated as a first line of defense in cellular homeostasis and are largely responsible for transmitting an environmental cue to a cellular response. Here we examine the regulation and function of the novel ß-cell IEG, neuronal PAS domain protein 4 (Npas4). Using MIN6 cells, mouse and human islets, as well as in vivo infusions, we demonstrate that Npas4 is expressed within pancreatic islets and is upregulated by ß-cell depolarizing agents. Npas4 tempers ß-cell function through a direct inhibitory interaction with the insulin promoter and by blocking the potentiating effects of GLP-1 without significantly reducing glucose-stimulated secretion. Finally, Npas4 expression is induced by classical endoplasmic reticulum (ER) stressors and can prevent thapsigargin- and palmitate-induced dysfunction and cell death. These results suggest that Npas4 is a key activity-dependent regulator that improves ß-cell efficiency in the face of stress. We posit that Npas4 could be a novel therapeutic target in type 2 diabetes that could both reduce ER stress and cell death and maintain basal cell function.


Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Citoproteção/genética , Células Secretoras de Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Linhagem Celular , Citoproteção/efeitos dos fármacos , Emulsões/farmacologia , Estresse do Retículo Endoplasmático/fisiologia , Peptídeo 1 Semelhante ao Glucagon/farmacologia , Glucose/farmacologia , Humanos , Insulina/genética , Insulina/metabolismo , Células Secretoras de Insulina/efeitos dos fármacos , Ilhotas Pancreáticas/efeitos dos fármacos , Camundongos , Fosfolipídeos/farmacologia , Regiões Promotoras Genéticas , Óleo de Soja/farmacologia , Regulação para Cima/efeitos dos fármacos
17.
Diabetes ; 61(3): 659-64, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22315310

RESUMO

Cellular cholesterol homeostasis is important for normal ß-cell function. Disruption of cholesterol transport by decreased function of the ATP-binding cassette (ABC) transporter ABCA1 results in impaired insulin secretion. Mice lacking ß-cell ABCA1 have increased islet expression of ABCG1, another cholesterol transporter implicated in ß-cell function. To determine whether ABCA1 and ABCG1 have complementary roles in ß-cells, mice lacking ABCG1 and ß-cell ABCA1 were generated and glucose tolerance, islet sterol levels, and ß-cell function were assessed. Lack of both ABCG1 and ß-cell ABCA1 resulted in increased fasting glucose levels and a greater impairment in glucose tolerance compared with either ABCG1 deletion or loss of ABCA1 in ß-cells alone. In addition, glucose-stimulated insulin secretion was decreased and sterol accumulation increased in islets lacking both transporters compared with those isolated from knockout mice with each gene alone. Combined deficiency of ABCA1 and ABCG1 also resulted in significant islet inflammation as indicated by increased expression of interleukin-1ß and macrophage infiltration. Thus, lack of both ABCA1 and ABCG1 induces greater defects in ß-cell function than deficiency of either transporter individually. These data suggest that ABCA1 and ABCG1 each make complimentary and important contributions to ß-cell function by maintaining islet cholesterol homeostasis in vivo.


Assuntos
Transportadores de Cassetes de Ligação de ATP/fisiologia , Colesterol/metabolismo , Homeostase , Inflamação/etiologia , Células Secretoras de Insulina/fisiologia , Ilhotas Pancreáticas/metabolismo , Lipoproteínas/fisiologia , Transportador 1 de Cassete de Ligação de ATP , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Animais , Intolerância à Glucose/etiologia , Interleucina-1beta/genética , Macrófagos/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Fator de Transcrição CHOP/fisiologia
18.
J Immunol ; 187(5): 2755-65, 2011 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-21813778

RESUMO

Islets from patients with type 2 diabetes exhibit ß cell dysfunction, amyloid deposition, macrophage infiltration, and increased expression of proinflammatory cytokines and chemokines. We sought to determine whether human islet amyloid polypeptide (hIAPP), the main component of islet amyloid, might contribute to islet inflammation by recruiting and activating macrophages. Early aggregates of hIAPP, but not nonamyloidogenic rodent islet amyloid polypeptide, caused release of CCL2 and CXCL1 by islets and induced secretion of TNF-α, IL-1α, IL-1ß, CCL2, CCL3, CXCL1, CXCL2, and CXCL10 by C57BL/6 bone marrow-derived macrophages. hIAPP-induced TNF-α secretion was markedly diminished in MyD88-, but not TLR2- or TLR4-deficient macrophages, and in cells treated with the IL-1R antagonist (IL-1Ra) anakinra. To determine the significance of IL-1 signaling in hIAPP-induced pancreatic islet dysfunction, islets from wild-type or hIAPP-expressing transgenic mice were transplanted into diabetic NOD/SCID recipients implanted with mini-osmotic pumps containing IL-1Ra (50 mg/kg/d) or saline. IL-1Ra significantly improved the impairment in glucose tolerance observed in recipients of transgenic grafts 8 wk following transplantation. Islet grafts expressing hIAPP contained amyloid deposits in close association with F4/80-expressing macrophages. Transgenic grafts contained 50% more macrophages than wild-type grafts, an effect that was inhibited by IL-1Ra. Our results suggest that hIAPP-induced islet chemokine secretion promotes macrophage recruitment and that IL-1R/MyD88, but not TLR2 or TLR4 signaling is required for maximal macrophage responsiveness to prefibrillar hIAPP. These data raise the possibility that islet amyloid-induced inflammation contributes to ß cell dysfunction in type 2 diabetes and islet transplantation.


Assuntos
Citocinas/metabolismo , Interleucina-1/antagonistas & inibidores , Polipeptídeo Amiloide das Ilhotas Pancreáticas/imunologia , Transplante das Ilhotas Pancreáticas/imunologia , Ilhotas Pancreáticas/metabolismo , Transdução de Sinais/imunologia , Animais , Diabetes Mellitus Tipo 2/imunologia , Diabetes Mellitus Tipo 2/metabolismo , Humanos , Imuno-Histoquímica , Inflamação/imunologia , Inflamação/metabolismo , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/imunologia , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Camundongos Transgênicos , Reação em Cadeia da Polimerase Via Transcriptase Reversa
19.
Transplantation ; 88(9): 1075-80, 2009 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-19898202

RESUMO

BACKGROUND: Islet transplantation is a promising therapy for type 1 diabetes; however, most islet grafts fail within 5 years. Innate immunity has been suggested to play a role in islet allograft rejection, potentially mediated by toll-like receptors (TLRs), a class of innate immune receptors. Lack of TLR4, in particular, has been reported to improve allograft survival. Therefore, we hypothesized that TLRs may be involved in islet allograft rejection, and that deletion of TLR4 may improve islet graft survival. METHODS: Islets were isolated from C57BL/10ScNJ (Tlr4(-/-)) and C57BL/10 (wild-type [WT]) animals and transplanted into Balb/cJ recipients with streptozotocin-induced diabetes. Blood glucose levels were used to determine graft viability and immunostaining to assess graft morphology and immune cell infiltration. The roles of the TLR4 adaptor molecules MyD88 and TLR adaptor molecule 1 (Ticam-1) were assessed using islets isolated from mice lacking MyD88 (MyD88(-/-)), Ticam-1 (Ticam-1(-/-)), or the combined double knockout (MyD88(-/-)/Ticam-1(-/-)). RESULTS: Contrary to our hypothesis, Tlr4(-/-) and WT islet allografts had similar failure rates; grafts failed at 23.2+/-1.2 and 24.5+/-1.5 days posttransplant, respectively (P=NS). Syngeneic grafts of Tlr4(-/-) and WT islets maintained normoglycemia for up to 10 weeks posttransplant, indicating that failure of Tlr4(-/-) islet allografts could not be attributed to an intrinsic defect in Tlr4(-/-) islets. Similarly, islet allotransplants from MyD88(-/-), Ticam-1(-/-), and MyD88(-/-)/Ticam-1(-/-) donors did not have improved allograft survival compared with WT controls. CONCLUSIONS: These findings indicate that islet allograft rejection in mice is independent of TLR4 and the TLR adaptor molecules MyD88 and Ticam-1, speaking against an essential role for TLR signaling in islet allograft rejection.


Assuntos
Diabetes Mellitus Experimental/cirurgia , Transplante das Ilhotas Pancreáticas/patologia , Transdução de Sinais/fisiologia , Receptores Toll-Like/fisiologia , Animais , Glicemia/metabolismo , Linfócitos T CD8-Positivos/imunologia , Primers do DNA , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Tipo 1/cirurgia , Tolerância Imunológica , Imunidade Inata , Transplante das Ilhotas Pancreáticas/imunologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , RNA/genética , RNA/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Receptores Toll-Like/genética , Receptores Toll-Like/imunologia , Transplante Homólogo/patologia
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