T lymphocytes and macrophages appear to play an important role in mediating ß-cell damage and causing Type 1 diabetes. Both activated T cells and macrophages operate and interact through the release of soluble factors called cytokines, which influence the type and magnitude of immune responses. It has been suggested that cytokines such as TNF-α and IL-1α can damage the N-cell directly. In Type 1 diabetes, cytokines are likely to have a critical role in individuals whose immune system is unbalanced allowing the emergence of self-destructive processes. To investigate this possibility, sensitive assays to detect a range of cytokines of potential relevance to the immune pathogenesis of diabetes were establised. Using these, serum levels of IL-1α, IL-1N, TNF-α and IL-6 (macrophage-derived cytokines), IFN-γ and IL-2 (T helper 1 cytokine profile) and IL-4 and IL-10 (T helper 2 profile) have been measured in patients with Type 1 diabetes of different disease duration. Increased levels of TNF-α, IL-1α, IL-2 and IFN-γ were found in recently diagnosed patients with Type 1 diabetes when compared with both disease and metabolic control subjects and with normal controls. The presence of this profile of cytokines implies activation of the TH1 subset of helper cells near to diagnosis of Type 1 diabetes

Orientador: Ricardo de Lima Zollner / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-08T16:26:14Z (GMT). No. of bitstreams: 1 Ferro_KarlaPriscilaVieira_M.pdf: 1249697 bytes, checksum: a31e2763981008c52bfdee0373185f3f (MD5) Previous issue date: 2007 / Resumo: A linhagem de camundongos NOD (non obese diabetic) desenvolve espontaneamente diabetes mellitus tipo 1 (DM-1) com marcante similaridade ao observado em humanos, que se estabelece entre 12ª e 24ª semana de vida, com presença de autoanticorpos específicos contra antígenos pancreáticos. Grande parte das células encontradas são linfócitos T CD4+ e T CD8+ e, embora células NK, linfócitos B, células dendríticas e macrófagos também possam ser identificados nas lesões, o desenvolvimento da doença é primariamente dependente de linfócitos T CD4+ e CD8+ auto-reativos. A diferenciação e funcionamento de células ß são regulados por uma variedade de hormônios e fatores de crescimento, incluindo Nerve Growth Factor (NGF). Sabe-se que células-ß pancreáticas expressam receptores funcionais para NGF e esta neurotrofina induz modificações morfológicas e fisiológicas, incluindo estimulação da secreção de insulina. Estudos de terapias para o DM-1 baseadas na intervenção sobre o sistema imunológico revelam que estas podem ser estratégias promissoras para impedir a instalação e/ou evolução da doença. Neste contexto, investigamos os efeitos da administração de GM1 sobre a incidência do DM-1 e insulite em camundongos NOD, expressão de citocinas, NGF e seu receptor de alta afinidade TrkA. Nossos resultados sugerem que administração de GM1 na dose de 100mg/kg/dia em camundongos NOD fêmeas a partir da 4ª semana de vida é capaz de diminuir o índice de infiltrado inflamatório e conseqüentemente a expressão do diabetes, modulando negativamente o infiltrado inflamatório bem como a expressão gênica de citocinas pró-inflamatórias (IL-12, IFN-?, TNF-a e IL-1ß), além de aumentar a expressão gênica e protéica de NGF e TrkA, que pode atuar como regulador de sobrevivência da célula ß de maneira a inibir a apoptose desta célula / Abstract: The strain of NOD mice (non obese diabetic) spontaneously develops diabetes mellitus type 1 (DM-1) with strong similarity to the observed in humans. In this model, the diabetes manifestation occurs among 12th and 24th weeks of life, with presence of pancreas-specific autoantibodies. Great part of the cells are CD4+ and CD8+T cells, and even so NK cells, lymphocytes B, dendritics cells and macrophages also can be identified in the injuries, the development of the disease is essentially dependent of autoreactive CD4+ and CD8+ T cells. It was demonstrated that ? - pancreatic cells express NGF functional receptors and that this neurotrophin induces morphological and physiological modifications in pancreatic ? cells, including stimulation in insulin secretion. The inquiries of therapies for the DM-1 based on the intervention on the immune system disclose that these can be promising strategies to hinder the installation and/or evolution of the disease. In this context, we investigate the effect of GM1 administration on the incidence of DM-1 and insulitis in NOD mice, cytokines expression, NGF and its high affinity receptor TrkA. Our results suggest that administration of GM1 in the dose of 100mg/kg/dia in female NOD mice from 4ª week of life are capable to reduce the index of inflammatory infiltrated and consequently the expression of diabetes, down-modulating the inflammatory infiltrated as well as the gene expression of pro-inflammatory cytokines (IL-12, IFN-?, TNF-? and IL-1?), besides increasing the gene and protein expression of NGF and TrkA, that can act as regulating of ß cell - survival in way to inhibit apoptosis of this cell / Mestrado / Ciencias Basicas / Mestre em Clinica Medica

Orientador: Ricardo de Lima Zollner / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-21T01:15:46Z (GMT). No. of bitstreams: 1 Silva_LuisGuilhermeStivanin_M.pdf: 3878753 bytes, checksum: bb8270f964b31680efc65e277f167c0a (MD5) Previous issue date: 2012 / Resumo: Empregando as linhagens de camundongos NOD (non-obese diabetic) de desenvolvimento espontâneo do diabetes mellitus tipo 1 e BALB/c como linhagem controle, administrou-se exogenamente gangliosídeo GM1, mistura de gangliosídeos (GGs) (GM1 21%, GD1a 40%, GD1b 16%, GT1b 19%) e solução salina (0,9% NaCl) estéril da 4ª à 28ª semana de vida. Os efeitos da administração dos gangliosídeos sobre a frequência da manifestação do diabetes, índice de insulite, imunofenotipificação e atividade apoptótica de células presentes em ilhotas pancreáticas de NOD foram verificados por meio de análise glicêmica semanal, técnica colorimétrica com Eosina-Hematoxilina, imunofluorescência e TUNEL. A expressão gênica e os níveis séricos de insulina, além das expressões celular protéica e gênica dos fatores de regeneração GLP-1, PDX-1 e Ngn3 nos tecidos pancreáticos de BALB/c e NOD foram analisados por meio de ELISA, imunofluorescência e RT-PCR em tempo real. Após 28 semanas de tratamento, pôde-se verificar que os animais tratados com GM1 reduziram o diabetes de 70% observado nos animais controle salina, para 38%. Os animais tratados com GGs não apresentaram diabetes. O índice de insulite estava diminuído nos animais tratados com GM1 (p=0.09), GGs (p=0.004) e salina não-diabético (ND) (p=0.02) em relação ao grupo salina diabético (DM). O número de células apoptóticas nas ilhotas dos grupos NOD salina ND e NOD DM estava aumentado em relação aos grupos tratados com GM1 e GGs. Os níveis de insulina sérica estavam aumentados nos grupos BALB/c GGs (p=0.01) e BALB/c GM1 (p=0.03) em relação ao grupo BALB/c salina e nos grupos NOD GGs (p=0.008) e NOD salina ND (p=0.01) em relação ao grupo diabético. Por outro lado, os níveis de expressão gênica de insulina no grupo NOD GM1 (p=0.02) estavam aumentados em relação ao grupo salina. Quanto às expressões protéicas de GLP-1, PDX-1 e Ngn3, em ilhotas pancreáticas e tecido acinar, verificamos aumento no grupo NOD tratado com GGs. O conjunto dos resultados demonstra que os gangliosídeos diminuem a manifestação do diabetes espontâneo na linhagem NOD. Hipotetizamos que uma das propriedades dos gangliosídeos estudados é a de estimular a expressão de GLP-1, PDX-1 e Ngn3 em células do tecido acinar e em células da linhagem endócrina nas ilhotas pancreáticas dos animais tratados seja NOD ou BALB/c. Desta forma abrem-se novas frentes de estudos das propriedades antiinflamatórias e possivelmente regenerativas dos gangliosídeos / Abstract: In the present study we evaluate the properties of GM1 and GGs (21% GM1, 40% GD1a 16% GD1b, 19%GT1b) in NOD (non-obese diabetic) mice and BALB/c as a control lineage. Animals of both lineages were treated with GM1, GGs or saline from 4th to the 28th weeks of life. The ganglioside-treated NOD mice demonstrated a decrease in insulitis compared with saline-treated mice: 70% of saline control animals, 38% of GM1 group and 0% of GGs group. GLP-1 gene expression was increased in GM1-treated BALB/c and in GGs-treated NOD groups in comparison to the saline groups. Insulin gene expression was increased only in the GM1-treated NOD group. Serum insulin levels were increased in ganglioside-treated BALB/c and NOD groups. In the islets, the cell co-labeling of Insulin/GLP1 and somatostatin/GLP1 was increased in NOD and BALB/c gangliosides-treated mice compared to saline-treated mice. PDX-1 and Ngn3 protein expression were increased in pancreatic islets and exocrine tissues of GGs treated NOD mice in comparison to the saline treated group. Results suggest that gangliosides have modulatory properties, decreasing the insulitis score, maintaining of insulin levels, increasing GLP-1 protein expression in ? and ? pancreatic cells and retarding diabetes onset in NOD mice. Similarly to observation in neural tissue, the gangliosides studied could contribute to islets survival. We hypothesize that ganglioside play a role stimulating growth factor expression GLP-1, PDX-1 and Ngn3 in the cells from acinar tissue and islets cells / Mestrado / Clinica Medica / Mestre em Clinica Medica

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-10-11T17:48:42Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Chrisjacele Dissertação.pdf: 1102106 bytes, checksum: 157102cd60a6a7f996ddbb9302ae91b9 (MD5) / Made available in DSpace on 2016-10-11T17:48:42Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Chrisjacele Dissertação.pdf: 1102106 bytes, checksum: 157102cd60a6a7f996ddbb9302ae91b9 (MD5) Previous issue date: 2012-02-15 / Facepe / Diabetes mellitus (DM) caracteriza um grupo de doenças metabólicas resultante de defeitos na secreção e/ou ação da insulina que levam à hiperglicemia. As plantas do Gênero Bauhinia, pertencentes à Família das Fabaceae, conhecidas como “pata-de-vaca” são utilizadas pela medicina popular para o tratamento de diabetes em várias regiões do mundo, tais como África, Ásia bem como América Central e do Sul; estudos prévios já demonstraram atividade hipoglicemiante de extrato folhas de Bauhinia monandra. Lectinas são proteínas ou glicoproteínas, de origem não imune, que reconhecem e se ligam a carboidratos de forma especifica e reversível. Uma lectina presente em folhas da B. monandra (BmoLL, B. monandra Leaf Lectin), galactose específica, foi purificada através de cromatografia de afinidade em gel de guar. Apenas uma banda foi revelada por eletroforese em gel de poliacrilamida, PAGE, para proteínas nativas. Os efeitos da ação hipoglicemiante do tratamento de BmoLL purificada em camundongos NOD (NON OBESE DIABETIC), foi avaliado a na utilização de três grupos de animais, cada grupo com (n=4), intraperitonealmente, por 21 dias. O grupo tratado com BmoLL recebeu 60mg/kg/dia, o grupo controle para diabetes não tratado recebeu veículo, água. Grupo controle para valores normoglicêmicos foram camundongos que não desenvolveram diabetes. No grupo tratado os picos hiperglicêmicos foram vistos antes do tratamento, em uma média de glicose (307,50 ± 83,30 mg/dL), equivalente ao grupo diabéticos não tratados 364,5±106,24 mg/dl. No final do tratamento, 21dias, o grupo tratado (137,50 ± 68,26mg/dL) atingiu valores equivalentes ao grupo normoglicêmico (110,50 ± 16,66mg/dL). O controle nos níveis glicêmicos no grupo tratado mostrou apenas diferença estatística significante (p= 0,002) em comparação com o grupo que recebeu apenas veículo. Já o grupo de camundongos não diabéticos, ou seja, normoglicêmicos quando comparado com o grupo tratado não apresentou diferença estatistica significante (p= 0,12) os testes foram realizados pelo teste “t” de “Student”. Observando as consequências secundarias a hiperglicemia apresentadas pelo grupo controle para diabetes não tratado, não foram apresentadas pelo grupo tratado com BmoLL nem pelo grupo controle de níveis normoglicêmicos; conclui-se que a ação do tratamento com BmoLL ao ser capaz de controlar os níveis glicêmicos a valores normais de forma continua minimizou também as complicações secundárias a hiperglicemia, durante todo o período de 21 dias. Necessários estudos posteriores para entendimento dos mecanismos pelos quais a BmoLL tem seu efeito hipoglicemiante. / Diabetes mellitus ( DM ) features a group of metabolic disorders resulting from defects in the secretion and/or insulin action leading to hyperglycemia. The plants of the genus Bauhinia, belonging to the family Fabaceae, known as "paw-of-cow" are used in folk medicine for the treatment of diabetes in many parts of the world such as Africa, Asia and Central and South America; previous studies have demonstrated hypoglycemic activity of leaf extract of Bauhinia monandra. Lectins are proteins or glycoproteins of non- immune origin which recognize and bind carbohydrates specifically and reversibly form. A lectin present in the leaves of B. monandra (BmoLL , B. monandra Leaf Lectin), specifically galactose was purified by affinity chromatography on guar gel. Only one band was revealed by polyacrylamide gel PAGE for native proteins. The effects of treatment with hypoglycemic action BmoLL purified NOD (non obese DIABETIC) was evaluated using the three groups of animals, each group (n=4) intraperitoneally for 21 days. The treated group received 60mg/kg/day BmoLL, the control group received untreated diabetes vehicle, water. Values for the control group were normoglycemic mice did not develop diabetes. In the group treated hyperglycemic peaks were seen before treatment, at an average glucose (307.50 ± 83.30mg/dL), equivalent to the untreated diabetic group 364.5 ± 106.24mg /dl. At the end of treatment, 21 days, the treated group (137.50 ± 68.26mg/dL) achieved equivalent to the normoglycemic group (110.50 ± 16.66mg/dL) values. The control on blood glucose levels in the treated group showed only statistically significant difference (p=0.002) compared with the group that received only vehicle. The group of non-diabetic mice, ie, normoglycemic compared with the treated group showed no statistically significant difference (p=0.12) tests were performed by the "t" of " Student" test. Observing the secondary consequences hyperglycemia presented by the control group to untreated diabetes, were not presented by the group treated with BmoLL nor the normoglycemic control group levels, it is concluded that the action of treatment with BmoLL to be able to control blood glucose levels to normal values continuously also minimized the complications secondary to hyperglycemia during the whole period of 21 days. Required further studies to understand the mechanisms by which BmoLL has its hypoglycemic effect .

Orientador: Ricardo de Lima Zollner / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-24T11:47:48Z (GMT). No. of bitstreams: 1 Figueiredo_Daniellade_M.pdf: 3504963 bytes, checksum: 2a5ced4957aa0233b6b6f5417ad31dc3 (MD5) Previous issue date: 2014 / Resumo: A procura por novos fármacos a partir de plantas medicinais tem motivado a busca alternativa de substâncias com potencial antiinflamatório que possam auxiliar no tratamento das doenças inflamatórias, como no caso do diabetes mellitus tipo1. Como ferramenta para estudar essas substâncias que modulam a inflamação, é comum o uso de animais com propensão a desenvolver a doença, como os camundongos NOD (diabéticos não obesos). Dentre os constituintes das folhas de Passiflora alata Curtis, conhecido popularmente por maracujá doce, os flavonóides são compostos que podem atuar como antioxidantes e antiproliferativos, podendo modular a expressão de substâncias reguladoras do ciclo celular promovendo, desta forma, a sua interrupção em células em proliferação. Como resultados, nós obtivemos no grupo tratado com extrato aquoso das folhas de P. alata, redução na incidência do diabetes, aumento da expressão de insulina e diminuição do infiltrado inflamatório, estresse oxidativo e células CDK6+ em ilhotas pancreáticas. Como neste modelo animal a expressão de CDK6 está presente no infiltrado inflamatório, a sua diminuição no grupo tratado sugere que componentes nas folhas de P. alata possam atuar na inibição do ciclo celular de células inflamatórias ativadas promovendo efeito antiinflamatório e, consequentemente, diminuição na incidência do diabetes tipo 1. Visto os efeitos antiinflamatórios e consequente preservação de células beta, o estudo visa investir no desenvolvimento de novas drogas com potencial de interferir na evolução da doença, atuando desta forma como suporte no tratamento do diabetes autoimune / Abstract: The search for new medicinal drugs from plants has motivated the search for alternative potential anti-inflammatory substances that may assist in the treatment of inflammatory diseases, such as type 1 diabetes mellitus. As a tool to study these substances that modulate inflammation, is common to use animals with a propensity to develop the disease, such as NOD mice (non-obese diabetic). Among the constituents of Passiflora alata Curtis leaves, known popularly as sweet passion fruit, flavonoids are compounds that can act as antioxidants and anti-proliferative, which can modulate the expression of cell cycle regulatory substances promoting in this way, the cell cycle arrest in proliferating cells. As a result, we have obtained in the treated group with P. alata leaves aqueous extract, reduction in the incidence of diabetes, increased expression of insulin and decreased inflammatory infiltrate, oxidative stress and CDK6+ cells in pancreatic islets. As in this animal model the marking of CDK6 is present in the inflammatory infiltrate, the decreased expression of this protein in the treated group suggests that components in the leaves of P. alata may act on cell cycle inhibition of activated inflammatory cells promoting anti-inflammatory effect and reduction in the incidence of type 1 diabetes. Since the anti-inflammatory effects and consequent preservation of beta cells, the study intend to investing in the development of new drugs with the potential to interfere with the course of the disease, acting as a support in the treatment of autoimmune diabetes / Mestrado / Clinica Medica / Mestra em Clínica Médica

Orientador: Ricardo de Lima Zollner / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-26T19:48:10Z (GMT). No. of bitstreams: 1 Schumacher_NayaraSimonGonzalez_M.pdf: 2961311 bytes, checksum: 1493eaa496cbf00c2fc6f8fb35bf45f1 (MD5) Previous issue date: 2015 / Resumo: A linhagem de camundongos NOD (non obese diabetic) é utilizada como modelo experimental de Diabetes mellitus tipo 1 (DM-1), por desenvolver espontaneamente a doença similar ao observado em humanos. São inúmeros os mecanismos propostos para ruptura da tolerância imunológica no DM-1, como a predisposição genética do indivíduo somadas as interferências ambientais como o estresse e a alimentação, parecem contribuir para a ação dos mecanismos auto imunes. As pesquisas por novas substâncias com potencial antiinflamatório presentes nas plantas medicinais, são inspiradas e motivadas pelas propriedades destas e que podem auxiliar no tratamento das doenças inflamatórias, como no caso do DM-1. Relatos da literatura, nem sempre indexada, sugerem que a Eugenia uniflora é um produto natural que contém inúmeros compostos fenólicos em sua composição e o chá de suas folhas tem sido estudado em possuir atividade antiinflamatória, antioxidante e antidiabética, melhorando o controle do diabetes. No presente estudo investigamos quais os melhores solventes (água, etanol e metanol/acetona) para extração de compostos bioativos da folha de pitanga, e avaliamos a atividade antioxidante dos solventes pelas técnicas DPPH, FRAP, ABTS e ORAC, fenóis totais, identificação de taninos hidrolisáveis, composição centesimal e investigação de três compostos fenólicos (ácido elágico, ácido gálico e rutina) nas folhas. Nossos resultados sugerem que o extrato aquoso em comparação com o etanol e metanol/acetona, apresenta atividade antioxidante e fenóis totais superiores, sendo desta forma o extrato aquoso utilizado como tratamento de DM-1 em camundongos NOD. Vimos que seu consumo crônico é capaz de diminuir o índice de infiltrado inflamatório nas ilhotas pancreáticas e consequentemente a diminuição da expressão do diabetes. Além disso, é possível que compostos presentes nas folhas de E. uniflora possuam propriedades antiinflamatórias que preservam as células ? pancreáticas e mantenham os níveis de insulina sérica. Sendo assim, o estudo visa investir no desenvolvimento de novas drogas com potencial de interferir na evolução da doença, atuando desta forma como suporte no tratamento do diabetes autoimune / Abstract: NOD mice (non obese diabetic) is used as an experimental model of type 1 Diabetes mellitus (DM-1) that spontaneously develop the disease with similarities to observed in humans. Several mechanisms are proposed to breakdown immune tolerance in DM-1, such as the genetic predisposition of the individual, together with environmental factors such as stress and diet, favoring the onset of autoimmune mechanisms. The search for new substances with potential anti-inflammatory present in the medicinal plants inspire and motivate research focusing in the treatment of inflammatory diseases, including DM-1. Literature reports, not always indexed, suggest that Eugenia uniflora is a natural product that contains numerous phenolic compounds in its composition and tea from its leaves has been studied in possessing anti-inflammatory, antioxidant and anti-diabetic, improving diabetes control. In the present study we investigated what the best solvents (water, ethanol and methanol/acetone) for the extraction of bioactive compounds of cherry leave, and evaluate the antioxidant activity of solvents for technical DPPH, FRAP, ABTS and ORAC, total phenols, tannins identification hydrolysable, centesimal composition and investigation of three phenolic compounds (ellagic acid, gallic acid and rutin) in the leaves. Our results suggest that the aqueous extract in comparison with ethanol and methanol/acetone features antioxidant activity and higher total phenols, and thus the aqueous extract used as a DM-1 treatment in NOD mice. We have seen that the chronic consumption can reduce the inflammatory infiltrate index in pancreatic islets and consequently the reduction of diabetes expression. Moreover, it is possible that the components present in the E. uniflora leaves have anti-inflammatory properties that preserve the pancreatic ? cells and maintains serum insulin levels. Thus, the study aimed to invest in the development of new drugs with the potential to interfere with the disease, thereby acting as a support in the treatment of autoimmune diabetes / Mestrado / Clinica Medica / Mestra em Ciências

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

<p>The presence of protein amyloid in pancreas and its association to diabetes was first described 100 years ago in 1901, but was not identified as Islet Amyloid Polypeptide (IAPP) until 1986. The aim of the present work was to determine the role of the beta cell hormone, IAPP, in normal pancreatic islet physiology and during early disturbances of islet function.</p><p>Intra-islet peptides, i.e. chromogranin peptides and an extra-islet peptide, i.e. leptin, were studied to identify possible endogenous regulators of IAPP and insulin secretion. Chromogranin-B, but not chromogranin-A or pancreastatin, had the ability to inhibit islet IAPP and insulin release, suggesting that chromogranin-B may serve as an autocrine regulator of IAPP and insulin secretion. </p><p>Leptin had a more potent effect on IAPP secretion than on insulin secretion, which was dissociated from effects on islet glucose metabolism. Glucose oxidation rates were increased at physiological leptin concentrations, whereas higher leptin concentrations showed an inhibitory effect and chronically high leptin concentrations had no effect.</p><p>Female NOD mice were studied to investigate the release of IAPP in the progression to type 1 diabetes. The release of IAPP was lower than that of insulin from immune cell infiltrated islets, indicating preferential insulin release during the early course of the disease. </p><p>IAPP is expressed at an early embryonic stage. The effect of IAPP on cell proliferation in neonatal rat islets was studied in the search for a physiological role of IAPP. IAPP concentrations of (1-1000) nM stimulated neonatal islet cell proliferation mostly in beta cells and to a lesser extent in alpha cells. IAPP did not have any marked effect on the islet cell death frequency. These data indicate a role for IAPP as a potential regulator of beta cell proliferation in neonatal pancreatic islet.</p><p>It is concluded that IAPP may be involved in regulation of pancreatic beta cell function both in fetal and adult life.</p>

The presence of protein amyloid in pancreas and its association to diabetes was first described 100 years ago in 1901, but was not identified as Islet Amyloid Polypeptide (IAPP) until 1986. The aim of the present work was to determine the role of the beta cell hormone, IAPP, in normal pancreatic islet physiology and during early disturbances of islet function. Intra-islet peptides, i.e. chromogranin peptides and an extra-islet peptide, i.e. leptin, were studied to identify possible endogenous regulators of IAPP and insulin secretion. Chromogranin-B, but not chromogranin-A or pancreastatin, had the ability to inhibit islet IAPP and insulin release, suggesting that chromogranin-B may serve as an autocrine regulator of IAPP and insulin secretion. Leptin had a more potent effect on IAPP secretion than on insulin secretion, which was dissociated from effects on islet glucose metabolism. Glucose oxidation rates were increased at physiological leptin concentrations, whereas higher leptin concentrations showed an inhibitory effect and chronically high leptin concentrations had no effect. Female NOD mice were studied to investigate the release of IAPP in the progression to type 1 diabetes. The release of IAPP was lower than that of insulin from immune cell infiltrated islets, indicating preferential insulin release during the early course of the disease. IAPP is expressed at an early embryonic stage. The effect of IAPP on cell proliferation in neonatal rat islets was studied in the search for a physiological role of IAPP. IAPP concentrations of (1-1000) nM stimulated neonatal islet cell proliferation mostly in beta cells and to a lesser extent in alpha cells. IAPP did not have any marked effect on the islet cell death frequency. These data indicate a role for IAPP as a potential regulator of beta cell proliferation in neonatal pancreatic islet. It is concluded that IAPP may be involved in regulation of pancreatic beta cell function both in fetal and adult life.

Type 1 diabetes (T1D) is a chronic autoimmune disease targeted against the pancreatic β-cells. Proinflammatory cytokines are considered to play a major role in the destruction of the insulin-producing β-cells. This thesis studied strategies to counteract proinflammatory cytokines in experimental T1D. Both animal models for T1D as well as β-cell preparations exposed in vitro to putative noxious conditions were examined. In the first study we observed that cytokine treatment of mouse pancreatic islets lacking inducible nitric oxide synthase (iNOS) induced a prolongation of the early stimulatory phase of glucose stimulated insulin secretion. Various experiments led to the conclusion that this prolonged stimulatory effect may involve the DAG/PLD/PKC pathway. Next, we transplanted mouse islets deficient in iNOS to spontaneously diabetic NOD mice. We observed a normalization of hyperglycemia but not a delayed allograft rejection compared to transplanted wild type islets. Thus, absence of iNOS in the graft was not sufficient to prolong allograft survival. In paper III we found that sustained glucose stimulation of rat pancreatic islets was coupled to a decreased conversion of proinsulin to insulin. Islet treatment with IL-1β was also coupled to a decreased proinsulin conversion. Islet proconvertase activity may be a target in islet damage. In paper IV prolactin (PRL) was administered to mice in the multiple low dose streptozotocin model and we observed that PRL enhanced a Th2 response. This may contribute to the protective action by PRL in this model of autoimmune T1D. Finally, by examining β-cells overexpressing Suppressor of cytokine signalling 3 (SOCS-3) it was found that this could inhibit IL-1β induced signalling through the NF-κB and MAPK pathways. SOCS-3 overexpression also inhibited apoptosis induced by cytokines in primary β-cells. Lastly, we demonstrated that SOCS-3 transgenic islets were protected in an allogeneic transplantation model.