La dystrophie musculaire de Duchenne (DMD) est une maladie liée à l'X caractérisée par la détérioration progressive des muscles en raison de l'absence de la protéine dystrophine. Les muscles atteints chez l'homme ou dans des modèles animaux (souris mdx) présentent une fibrose, accumulation excessive de protéines de la matrice extracellulaire. Parmi les facteurs induisant la fibrose se trouvent le Facteur de Croissance de Transformation de type β (TGF-β) et le Facteur de Croissance du Tissu Conjonctif (CTGF). Ce dernier est une cible de la voie de signalisation médiée par TGF-β/SMAD et est responsable des effets profibrotiques de TGF-β. La régulation de l'expression de CTGF médiée par TGF-β dans les cellules musculaires est peu connue. Nous décrivons ici un nouvel élément de liaison SMAD situé dans la région 5’UTR du gène de CTGF, important pour l'expression de CTGF médiée par le TGF-β dans des myoblastes. De plus, nos résultats suggèrent que d'autres sites de liaison du facteur de transcription présents dans le 5’UTR du gène de CTGF sont importants pour cette expression.Par ailleurs, le Facteur de Nécrose Tumorale (TNF) est une cytokine inflammatoire présente dans les muscles atteints de DMD et est responsable de la nécrose du muscle et de l'infiltration de cellules inflammatoires. Nous montrons que l’expression du récepteur soluble TNFRI par électrotransfert (ET) dans le muscle tibialis anterior de la souris atténue l'inflammation, les dommages et la fibrose dans le muscle squelettique des souris mdx, et provoque une augmentation de la force musculaire. Par conséquent, nous proposons l'ET comme thérapie efficace anti-TNF pour le traitement de dystrophies musculaires. / The Duchenne Muscular Dystrophy (DMD) is an X-linked disease characterized by progressive damage in the muscle due to the absence of the dystrophin protein. Fibrosis, the excessive accumulation of extracellular matrix (ECM) proteins, is also present in the muscle of DMD patients and several animal models (such as the mdx mice). Among the factors that induce fibrosis are Transforming Growth Factor type β (TGF-β) and Connective Tissue Growth Factor (CTGF), the latter being a target of the TGF-β/SMAD signaling pathway and is the responsible for the profibrotic effects of TGF-β and are augmented in fibrosis tissues. Little is known about the regulation of the expression of CTGF mediated by TGF-β in muscle cells. In here, we described a novel SMAD Binding Element (SBE) located in the 5’ UTR region of the CTGF gene important for the TGF-β mediated expression of CTGF in myoblasts. In addition, our results suggest that additional transcription factor binding sites present in the 5’ UTR of the CTGF gene are important for this expression. On the other hand, the Tumor Necrosis Factor (TNF) is an inflammatory cytokine that is present in DMD muscles and is responsible for muscle necrosis and inflammatory cell infiltration. In this study, we show that the increased expression of the soluble TNF Receptor I by electrotransfer (ET) in the tibialis anterior muscle attenuates inflammation, damage and fibrosis in the skeletal muscle of the mdx mice. In addition, we found increased muscle strength in the mdx mice. Therefore, we propose that ET could be used as an efficient anti-TNF therapy for treating muscle dystrophies.

L'interleukine-17A (IL-17A) et le facteur de nécrose tumorale alpha (TNF-α) sont des cytokines pro-inflammatoires impliquées dans la pathogénèse de plusieurs maladies articulaires. Au cours de la polyarthrite rhumatoïde (PR), une augmentation de la destruction osseuse ainsi qu'un defaut de réparation sont responsables des dommages articulaires. Cependant au cours de la spondylarthrite ankylosante (AS), une importante ossification ectopique est observée, conduisant à la formation de syndesmophytes, associé à une perte de la masse osseuse systémique. Récemment, l'étude de ces cytokines a conduit à la publication de résultats contradictoires. Notre objectif a donc été d'étudier l'effet de ces deux cytokines sur la différenciation ostéogénique de cellules souches mésenchymateuses humaines isolées (hMSCs) et de fibroblastes de la membrane synoviale (FLS). Tous les modèles de cellules utilisés, ont démontré que l'IL-17A et le TNF-α augmentent de manière synergique l'ostéogénèse. Ceci semble se rapprocher du modèle de l'AS où une formation d'os ectopique est observée dans laquelle l'IL-17A et le TNF-α jouent un rôle majeur. En parallèle, ces deux cytokines stimulent localement les ostéoclastes, entraînant une perte de masse osseuse observée à la fois dans la PR et dans l'ostéoporose. Cibler simultanément l'IL-17A et le TNF-α pourrait conduire à une diminution de l'infiltration de cellules et de la destruction articulaire observée dans la PR et pourrait ainsi réduire les effets des FLS PR sur l'activation de l'ostéoclastogénèse / Interleukin-17A (IL-17A) and tumor necrosis factor alpha (TNF-α) are pro-inflammatory cytokines involved in the pathogenesis of several arthritic diseases. In rheumatoid arthritis (RA), joint damage is a result of an increase in bone destruction and a decrease in bone repair. In contrast, in ankylosing spondylitis (AS), a bone mass loss accompanied by a significant ectopic ossification is observed leading to the formation of syndesmophytes. Recent studies led to contradictory findings regarding the role of IL-17A and TNF-α in arthritic disease. Therefore, our objective was to study the effect of these two cytokines on the osteogenic differentiation of isolated human mesenchymal stem cells (hMSCs) and fibroblasts of the synovial membrane (FLS). In all the cell models used, we demonstrated that Il-17A and TNF α synergistically increase osteogenesis. This seems to approach the model of AS where ectopic bone formation is observed and in which IL-17A and TNF-α both are involved. These cytokines stimulate osteoclasts locally resulting in loss of bone mass observed in both RA and osteoporosis. Thus, targeting IL-17A and TNF-α could lead to a decrease in cell infiltration and joint destruction which is observed in RA and may reduce the effects of RA FLS on the activation of osteoclastogenesis

Orientador: Maria Helena Stangler Kraemer / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-14T09:37:26Z (GMT). No. of bitstreams: 1 Magalhaes_RenataFerreira_D.pdf: 45600840 bytes, checksum: c3be46b9fbfab6e5433e2e91db336bb3 (MD5) Previous issue date: 2009 / Resumo: Psoríase é uma dermatose inflamatória crônica, determinada por desregulação do sistema imune e associada a várias comorbidades. O marcador genético mais associado à psoríase em todas as populações é o HLA-CW06. Polimorfismos na região promotora do TNF-a, especialmente a troca de uma guanina por uma adenina nas posições -238 e -308 estão relacionados à alta produção de TNF-a e risco aumentado para psoríase nas populações caucasóides e não em asiáticos. Com o objetivo de determinar se polimorfismos destes genes podem ser fatores de risco para susceptibilidade ou gravidade da doença em pacientes brasileiros, foi realizado um estudo caso-controle com 69 pacientes com psoríase de início até 40 anos, com acompanhamento por dez anos para caracterização de sua evolução clínica em doença leve (grupo I) e grave (grupo II), e 70 indivíduos sadios. Foi feita a identificação dos alelos HLA classe I e II e SNPs da região promotora do TNF-a -238 e -308. Coletaram-se 10 mL de sangue periférico dos indivíduos e se realizou a extração do DNA através do método salting out. O DNA foi amplificado pela reação em cadeia da polimerase (PCR), com primers sequência-específica. As freqüências alélicas e gênicas foram estimadas por contagem direta e a comparação entre as frequências dos grupos foi efetuada por Teste de Fisher (programa GraphPad InStat 3.05). Dois métodos computacionais foram usados para determinar os haplótipos dos indivíduo: (1) o algoritmo ELB implementado pelo software Arlequin 3.1 e (2) um método de base coalescente implementado pelo software PHASE v2, e as freqüências de cada haplótipo foram comparadas por Teste de Fisher. No grupo II, observou-se maior associação com fatores desencadeantes como estresse, início na adolescência e predominância do sexo masculino. Pode-se sugerir que os alelos HLA-B*37, -Cw*06, -Cw*12 e -DRB1*07 foram associados ao curso mais grave da doença, enquanto - B*57 à doença mais leve. O aielo DRBT04 teve tendência a associação negativa. Ao se comparar o grupo I com o grupo II, o alelo HLA-B*37 pode ser interpretado como fator de mau prognóstico. Não houve diferença estatística entre polimorfismos da região promotora do TNF-a entre pacientes e controles. Este estudo apontou uma alta frequência do genótipo TNF-a -238 G/G {OFt 3,21; Cl:1,06-9,71; p=0,04), assim como do alelo -238 G, no grupo com doença mais grave e, ao contrário, o genótipo -238 G/A com frequência maior no grupo de boa evolução. O haplótipo -238A-308G mostrou frequência reduzida conferindo um efeito protetor. Estes dados não correspondem ao reportado para as populações caucasianas, considerando que a população brasileira é miscigenada. Polimorfismos dos SNPs do TNF-a não parecem ser um fator de susceptibilidade genética mais importante do que o já conhecido HLA-Cw*06 em pacientes brasileiros, mas podem ter relação com as manifestações e evolução da doença. / Abstract: Psoriasis is an erythematous, scaly inflammatory dermatosis with a complex immunologic basis. The strongest genetic marker for psoriasis is HLA-Cw*06. Polymorphisms in the TNF-a promoter region, especially replacement of guanine with adenine in positions -238 and -308 are related to higher TNF-a production and higher risk for psoriasis in Caucasoid populations, not found in Asians. We did a case-control study of 69 patients with psoriasis type I and 70 controls, characterized clinical progression along 10-years of follow-up in mild or severe disease and determined HLA class I, II and TNF-a SNPs -238 and -308 polymorphisms to demonstrate whether these polymorphisms may be genetic risk for susceptibility to psoriasis or severity of the disease in Brazilians. Peripheral blood (10 ml) was collected. Genomic DNA from both psoriasis patients and controls was isolated using a salting out procedure. Polymorphisms were identified by PCR/SSP. Alleles and genotypes frequencies were compared by Fisher's test (GraphPad InStat 3.05 software). Two computational methods were used to determine the haplotypes of each subject, without taking into account any prior information: (1) the ELB algorithm implemented by the ARLEQUIN 3.1 software and (2) a coalescence based method as implemented by the PHASE v2 software. The haplotype frequencies were compared between group pairs by Fisher's test. Severe disease was found more frequently in male patients, associated with environmental factors and onset at adolescence. It may be suggested that alleles HLA- B*37, -Cw*06, -Cw*12 and -DRB1*07 were associated with severe disease course, while -B"57 with mild disease. No statistical difference was found between the patients and controls regarding polymorphisms frequencies in TNF SNPs. This study pointed to a higher TNF-238 G/G genotype frequency (OR 3,21; Cl:1,06-8,71; p=0,04) in the group with severe disease and -238A-308G haplotype was found in reduced frequencies revealing a protective effect. These data do not correspond to those reported for the Caucasian population, considering that Brazilian population is admixed, and this is the first consideration about TNF-a SNPs in psoriasis in this population. Polymorphisms in the TNF-a SNPs do not seem to be a more important genetic risk factor for psoriasis than the already known Cw*06 in Brazilian patients, but these markers may be related to clinical manifestations. / Doutorado / Clinica Medica / Doutor em Clínica Médica

Orientador: Sisi Marcondes Paschoal / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-26T18:31:06Z (GMT). No. of bitstreams: 1 Bonfitto_PedroHenriqueLeite_M.pdf: 791921 bytes, checksum: 967c29bbcdf8e6df7bd3a2d919b84111 (MD5) Previous issue date: 2015 / Resumo: As plaquetas são importantes células na inflamação, entretanto, os trabalhos que estudam as citocinas na reatividade plaquetária são raros. O objetivo do presente trabalho foi estudar os efeitos do fator de necrose tumoral-alfa (TNF-?) em plaquetas. Ensaios de agregação foram realizados incubando-se plaquetas com crescentes concentrações de TNF-? (1 - 3000 pg/ml) por diferentes intervalos de tempo (5 - 60 min), na ausência ou presença do antagonista não seletivo dos receptores TNFR1 e TNFR2, o R7050. Também foi estudado o efeito do TNF-? na viabilidade plaquetária utilizando-se o MTT. O efeito do TNF-? na mobilização de Ca2+ em plaquetas foi investigado através de ensaios de fluorescência utilizando-se o fluo-3-AM; os ensaios de western blotting foram realizados para o estudo da ativação da enzima c-Src e do receptor de fibrinogênio. Finalmente, foram determinados os níveis intraplaquetários de AMPc e GMPc por ELISA. O TNF-? inibiu a agregação plaquetária induzida por ADP ou trombina de forma dependente da concentração da citocina e do tempo de incubação. O efeito inibitório máximo do TNF-? na agregação induzida por ADP (5 ?M) foi obtido com a concentração de 300 pg/ml por um tempo de incubação de 30 min (90 ± 7% de inibição), o qual foi significativamente prevenido pela pré-incubação das plaquetas com o R7050. A viabilidade plaquetária não foi modificada pela incubação por 60 min com o TNF-? (30 e 3000 pg/ml). A incubação de plaquetas com TNF-? (300 pg/ml, 30 min) reduziu em 53% o aumento da concentração de Ca2+ total causado pela adição de trombina (200 mU/ml). A queda da concentração de Ca2+ citosólica plaquetária causada pelo TNF-? foi em decorrência da diminuição em 1,8 e 3,4 vezes da mobilização interna do íon e do influxo do mesmo, respectivamente. O TNF-? reduziu em 60% os níveis de AMPc em plaquetas ativadas com ADP. Por outro lado, o TNF-? aumentou significativamente os níveis de GMPc em plaquetas ativadas por ADP (aumento de 51%). A pré-incubação de plaquetas com o inibidor da guanilil ciclase ODQ não reduziu o efeito inibitório do TNF-? na agregação induzida por ADP. Os ensaios de western blotting mostraram que o TNF-? reduziu significativamente a fosforilação do resíduo de Tyr416 da c-Src em plaquetas ativadas. Da mesma forma, o TNF-? reduziu em 37% a fosforilação do resíduo de Tyr773 da subunidade ?3 da integrina ?IIb?3 (receptor de fibrinogênio) em plaquetas ativadas por ADP. Portanto concluímos que o TNF-? inibe a agregação plaquetária via receptores TNFR1 e/ou TNFR2, sem reduzir a viabilidade das plaquetas. O efeito inibitório do TNF-? na agregação é acompanhado pela redução de Ca2+ citosólico e inibição de c-Src e do receptor de fibrinogênio em plaquetas, sendo estes independentes de AMPc ou GMPc / Abstract: Platelets have been described as important cells in inflammation; however, the effects of cytokines on platelet reactivity are rarely studied. The objective of the present work was to investigate the effects of the tumor necrosis factor-alpha (TNF-?) in platelets. Aggregation assays were carried out incubating platelets with increasing TNF-? concentrations (1 - 3000 pg/ml) for different intervals of times (5 - 60 min), in the absence or in presence of the non-selective antagonist of TNFR1 and TNFR2, R7050. Effect of TNF-? on platelet viability was determined using MTT. The effect of TNF-? on the Ca2+ mobilization in platelets was investigated through fluorescence assays using fluo-3AM and Western blotting assays were carried out to determine the activation of c-Src and the fibrinogen receptor. Finally, the cAMP and cGMP levels in platelets were determined by ELISA. TNF-? dose- and time-dependently inhibited ADP or thrombin-induced platelet aggregation. The inhibitory effect of TNF-? on ADP(5 ?M)-induced platelet aggregation was maximum in a concentration of 300 pg/ml incubated with platelets for 30 min (90 ± 7% of inhibition), which was significantly prevented by the incubation of platelets with R7050. Platelet viability was not modified by TNF-? (30 and 3000 pg/ml) incubated for 5 to 60 min. Incubation of platelets with TNF-? (300 pg/ml, 30 min) reduced the increased total Ca2+ concentration induced by thrombin (200 mU/ml) by 53%. Decreasing Ca2+ internal mobilization (1,8 fold) and decreasing in external Ca2+ influx (3,4 fold) led to a reduction of total cytosolic Ca2+ in TNF-? activated platelets. TNF-? reduced the cAMP levels in ADP-activated platelets by 60%. On the other hand, TNF-? significantly increased cGMP levels in ADP-activated platelets (51% increase). Pre-incubation of platelets with the guanylyl cyclase inhibitor ODQ did not modify the inhibitory effect of TNF-? on ADP-induced platelet aggregation. Western blotting analysis showed that TNF-? significantly reduced phosphorylation on Tyr416 of c-Src in activated platelets. Similarly, TNF-? reduced by 37% the Tyr773 phosphorylation of ?3 subunit of ?IIb?3 integrin (fibrinogen receptor) in ADP-activated platelets. Therefore, our results show that TNF-? inhibits platelet aggregation via TNFR1 and/or TNFR2 receptors, without affecting platelet viability. The inhibitory effect of TNF-? on aggregation is accompanied by a reduction in cytosolic Ca2+ and the inhibition of c-Src and fibrinogen receptor activation, which are cAMP and cGMP-independent effects / Mestrado / Farmacologia / Mestre em Farmacologia

No description available.

Celiaki (glutenintolerans) är en kronisk, autoimmun sjukdom med diffusa symtom. Vid förtäring av glutenhaltig mat uppstår en allergisk reaktion hos glutenintoleranta individer. Gluten kan inte fullständigt brytas ned av kroppens enzymer, vilket betyder att icke nedbrutna peptidfragment (såsom glutamin) absorberas i tarmslemhinnan. Enzymet transglutaminas katalyserar omvandlingen av glutamin till glutamat. Glutenkänsliga T-celler aktiveras av glutamat att utsöndra proinflammatoriska cytokiner såsom interferon-gamma (IFN-γ) och tumörnekrosfaktor-alfa (TNF-⍺). Syftet med studien var att undersöka om gluten- och gliadinstimulering av celler i helsaliv in vitro kan inducera produktion av IFN-γ och TNF-⍺. Pilotstudier med 2 försökspersoner utfördes, där celler i salivprover stimulerades med enzymatiskt nedbrutet gliadin (<40 mg gliadin), samt PHA (5 µg/mL), PMA (50 ng/mL) och LPS (1 µg/mL) 20 timmar vid 37 ˚C. Cytokinproduktionen i salivproverna kvantifierades med ELISA och uppreglering av IFN-γ och TNF-⍺ undersöktes med RT-qPCR. Efter metodutveckling upprepades stimulering och ELISA med salivprov från 12 försökspersoner (6 individer med och utan celiaki). Immunreaktionen som uppstår hos glutenintoleranta individer in vivo kunde inte återskapas i saliv in vitro med den framtagna metoden. Hos övervägande delen av salivproverna var cytokinproduktionen under detektionsgränsen, 4 pg/mL för IFN-γ och 15,6 pg/mL för TNF-⍺. Det finns risk för att outforskade detaljer eller agens saknades från reaktionskedjan och därmed kunde den förväntade immunreaktionen inte återskapas. En annan felkälla kan vara för låg koncentration av immunceller i saliven. / Celiac disease is a chronic, autoimmune disease that has diffuse symptoms. Upon consuming gluten containing food, an allergic reaction occurs in gluten-sensitive individuals. Gluten cannot be fully digested by human enzymes, which leads to non-digested peptide fragments (such as glutamine) to be absorbed in the gastrointestinal wall. The transglutaminase enzyme catalyzes the conversion of glutamine to glutamate. Glutamate activates gluten-specific T-lymphocytes to produce proinflammatory cytokines e.g., interferon-gamma (IFN-γ) and tumor necrosis factor alpha (TNF-⍺). The aim of this study was to investigate whether stimulation of cells in whole saliva in vitro with gluten and gliadin can induce production of IFN-γ and TNF-⍺. Pilot studies were conducted, where cells in saliva from 2 subjects was stimulated with enzymatically digested gliadin (<40 mg gliadin) together with PHA (5 µg/mL), PMA (50 ng/mL) and LPS (1 µg/mL) for 20 hours at 37 ˚C. The production of cytokines was quantified by ELISA, and the upregulation of IFN-γ and TNF-⍺ was analyzed by RT-qPCR. After method development, the stimulations and ELISA quantifications of the proinflammatory cytokines were repeated in saliva samples from 12 subjects (6 individuals with and without celiac disease). The immune reaction that occurs in people with celiac disease could not be recreated in saliva in vitro with the developed method. In most of the samples the production of cytokines was under the detection range, 4 pg/mL for IFN-γ and 15,6 pg/mL for TNF-⍺. There is risk of unstudied details or agents missing from the reaction chain, and therefore the expected immune reaction could not be recreated. Another source of error could be low concentration of immune cells in saliva.

The instructive signals received by T cells during the programming stages of activation will determine the fate of effector and memory populations generated during an immune response. Members of the tumor necrosis factor (TNF) superfamily play an essential role in influencing numerous aspects of T cell adaptive immune responses including cell activation, differentiation, proliferation, survival, and apoptosis. My thesis dissertation describes the involvement of two such members of the TNF superfamily, TNF and FasL, and their influence on the fate of T cells early during responses to viral infections and to the induction of transplantation tolerance. TNF is a pleiotropic pro-inflammatory cytokine that has an immunoregulatory role in limiting the magnitude of T cell responses during a viral infection. Our laboratory discovered that one hallmark of naïve T cells in secondary lymphoid organs is their unique ability to rapidly produce TNF after activation and prior to acquiring other effector functions. I hypothesized that T cell-derived TNF will limit the magnitude of T cell responses. The co-adoptive transfer of wild type (WT) P14 and TNF-deficient P14 TCR transgenic CD8+ T cells, that recognize the GP33 peptide of lymphocytic choriomeningitis virus (LCMV), into either WT or TNF-deficient hosts demonstrated that the donor TNF-deficient P14 TCR transgenic CD8+ T cells accumulate to higher frequencies after LCMV infection. Moreover, these co-adoptive transfer experiments suggested that the effect of T cell-derived TNF is localized in the microenvironment, since the TNF produced by WT P14 TCR transgenic CD8+ T cells did not prevent the accumulation of TNF-deficient P14 TCR transgenic CD8+ T cells. To determine if T cell-produced TNF is acting on professional APC to suppress the generation of virus-specific T cell responses, I performed co-adoptive transfer experiments with WT P14 TCR transgenic CD8+ and TNF-deficient P14 TCR transgenic CD8+ T cells into TNFR1/2 (1 and 2) deficient mice. These experiments demonstrated that the absence of TNFR1/2 signaling pathway in the host cells resulted in a greater accumulation of WT P14 TCR transgenic CD8+ T cells, thereby considerably diminishing the differences between donor WT P14 TCR transgenic CD8+ and donor TNF-deficient P14 TCR transgenic CD8+ T cells. The increased frequency and absolute numbers of WT P14 TCR transgenic CD8+ T cells in TNFR1/R2 deficient recipients suggests that one mechanism for the suppressive effect of T cell-derived TNF on antigen-specific T cells occurs as a result of TNFR signaling in the host cells. However, the donor TNF-deficient P14 TCR transgenic CD8+T cells still accumulated to higher frequency and numbers compared to their donor WT transgenic counterparts. Together, these findings indicate that T cell-produced TNF can function both in an autocrine and a paracrine fashion to limit the magnitude of anti-viral T cell responses. Given the immunoregulatory role of TNF and the ability of peripheral naïve T cells to produce this cytokine, I questioned at what stage of development do T cells become licensed to produce this cytokine. The peripheral naïve T cell pool is comprised of a heterogeneous population of cells at various stages of development, a process that begins in the thymus and is completed after a post-thymic maturation phase in the periphery. I hypothesized that naïve T cells emigrating from the thymus will be competent to produce TNF only after undergoing a maturation process in the periphery. To test this hypothesis, I compared cytokine profiles of CD4+ and CD8+single positive (SP) thymocytes, recent thymic emigrants (RTEs) and mature-naïve (MN) T cells during TCR activation. SP thymocytes exhibited a poor ability to produce TNF when compared to splenic T cells despite expressing similar TCR levels and possessing comparable activation kinetics with respect to the upregulation of CD25 and CD69 following stimulation. The reduced ability of SP thymocytes to produce TNF correlated with a decreased level of detectable TNF message following stimulation when compared to splenic counterparts. Stimulation of SP thymocytes in the context of a splenic environment did not fully enable TNF production, suggesting an intrinsic defect in their ability to produce TNF as opposed to a defect in antigen presentation. Using a thymocyte adoptive transfer model, I demonstrate that the ability of T cells to produce TNF increases progressively with time in the periphery as a function of their maturation state. RTEs identified by the expression of green fluorescent protein (GFP) (NG-BAC transgenic mice), showed a significantly enhanced ability to express TNF relative to SP thymocytes, but not to the extent of MN T cells. Together, these findings suggest that TNF expression by naïve T cells is regulated via a gradual licensing process that requires functional maturation in peripheral lymphoid organs. This highlights the functional heterogeneity of the naïve T cell pool (with respect to varying degrees of TNF production) during early T cell activation that can contribute to the many subsequent events that shape the course of an immune response. The productive activation of naïve T cells requires at least initial two signals; the first being through the TCR and the second is the engagement of co-stimulatory molecules on the surface of the T cells. T cells activated in the absence of co-stimulation become anergic or undergo cell death. Agents that block co-stimulation of antigen-specific T cells are emerging as an alternative to immunosuppressive drugs to prolong allograft survival in transplant recipients. Targeted blockade of CD154-CD40 interactions using a αCD154 monoclonal antibody (MR1) with a simultaneous transfusion of allogeneic splenocytes (donor specific transfusion or DST) efficiently induces tolerance to allografts. This co-stimulation blockade-induced tolerance is characterized by the deletion of host alloreactive T cells within 24 hours of treatment. Toll-like receptor (TLR) agonists abrogate tolerance induced by co-stimulation blockade by impairing the deletion of host alloreactive T cells and resulting in allograft rejection. The goal of my study was to determine the underlying molecular mechanisms that protect host alloreactive T cells from early deletion after exposure to TLR agonists. I hypothesized that TLR ligands administered during co-stimulation blockade regimen differentially regulate the expression of pro- and anti-apoptotic molecules in alloreactive T cells, during the initial stages of activation thereby preventing deletion. To test this hypothesis, I used syngeneic bone marrow chimeric mice containing a trace population of alloreactive KB5 TCR transgenic CD8+ T cells (KB5 Tg CD8+ T cells) that recognize H-2Kb as an alloantigen. I show here that KB5-CD8+ T cells downregulate CD127 (IL-7R!) and become apoptotic as early as 12 hrs after co-stimulation blockade. In contrast, KB5 Tg CD8+ T cells from mice treated with bacterial lipopolysaccaride (LPS) during co-stimulation blockade failed to become apoptotic, although CD127 was downregulated. Examination of the mRNA expression profiles of several apoptotic genes in purified KB5 CD8+ T cells from mice treated with DST+anti-CD154 for 12 hrs revealed a significant upregulation of FasL mRNA expression compared to the untreated counterparts. However, in vitro FasL blockade or in vivo cytotoxicity experiments with mice deficient in Fas or FasL indicated that the Fas-FasL pathway might not be crucial for tolerance induction. Another pro-apoptotic molecule BIM was upregulated in alloreactive T cells during co-stimulation blockade. This suggests that both the Fas pathway and BIM may be playing complementary roles in inducing deletional tolerance. Although FasL expression was diminished in alloreactive T cells in the presence of LPS, BIM expression was not diminished, suggesting that alloreactive T cells may still be vulnerable to undergo apoptosis. Concomitantly, I also found that LPS treatment during co-stimulation blockade resulted in non-specific upregulation of Fas expression in alloreactive T cells and non-transgenic T cells (CD4+ and CD8+). I demonstrate here that treatment with Fas agonistic antibody in vitrofor 4 hours can selectively induce apoptosis of alloreactive T cells that were believed to be refractory to apoptosis during LPS treatment. I speculate that under these conditions, deletion may be occurring due to the involvement of both Fas and BIM. Further, the mRNA expression profile revealed interleukin-10 (IL-10) as a molecule induced in alloreactive T cells during LPS treatment. Analysis of serum confirmed the systemic expression of IL-10 protein in mice treated with LPS during co-stimulation blockade. I hypothesized that LPS-induced IL-10 can have an anti-apoptotic role in preventing the deletion of alloreactive T cells and mediating allograft rejection. Contrary to my hypothesis, I found that IL-10 KO mice rejected allogeneic target cells similar to their WT counterparts, suggesting that IL-10 may not be required for LPS-mediated abrogation of tolerance induction. In addition to the systemic induction of IL-10, LPS also induced cytokines such as interleukin-6 (IL-6), TNF and interferon-γ (IFN-γ). These findings suggest that both Fas-FasL and BIM mediated apoptotic pathways may play complementary roles in inducing the early deletion of activated alloreactive T cells during tolerance induction. On the other hand, the mechanism of LPS mediated abrogation of tolerance induction can not be attributed to IL-10 alone as it may be playing a synergistic role along with other proinflammatory cytokines that may in turn result in the prevention of alloreactive T cell death during this process. Most importantly, these findings indicate that despite emerging from a pro-inflammatory cytokine milieu, alloreactive T cells are still susceptible to undergo Fas-mediated apoptosis during the first 24 hours after co-stimulation blockade and LPS treatment. Therefore, targeting the Fas-FasL pathway to induce deletion of alloreactive T cells during the peri-transplant period may still be a potential strategy to improve the efficacy of co-stimulation blockade induced transplantation tolerance during an environmental perturbation such as inflammation or infection.

Dengue viruses (DV) are re-emerging mosquito-borne pathogens for which four distinct lineages, grouped based on serology and referred to as serotypes 1-4 (DIV-D4V), have been described. Epidemiological data imply that re-infection with a "heterologous" serotype, i.e, one other than that to which the individual was originally exposed, enhances the risk for development of severe disease, dengue hemorrhagic fever (DHF). The hallmark of DHF is a transient capillary leakage syndrome of rapid onset, temporally associated with the resolution of fever and viremia. In its most grave form, the vascular permeability phenomenon in DHF may progress to dengue shock syndrome (DSS), which is often fatal in the absence of appropriate medical care. Despite the fulminant nature of vascular leakage during DHF/DSS, this phenomenon does not appear to be due to direct cytopathic effects of DV. Rather, inappropriate reactivation and/or regulation of dengue-specific memory are the prevailing theorized (immunopathological) etiologies. Traditional vaccine development techniques have proven insufficient for DV, since any vaccine must offer complete protection against all four serotypes to avoid enhanced pathology on natural viral challenge. Understanding the underlying mechanisms that contribute to dengue disease, particularly the development of dengue-specific memory, is therefore of critical importance. Dengue immunopathology and the specific aspects of immunological memory that determine disease severity are heatedly debated. Previous research in our lab has suggested that T cell responses contribute to the severity of dengue illness. Clinical data indicate enhanced immune activation in more grave cases of DV infection, and serotype cross-reactive T cells from multiple individuals are present after both primary and secondary dengue infections. However, little is known about the conditions under which T cells are primed and dengue-specific memory is generated. Dendritic cells (DCs) are bone marrow-derived cells that play a central role in directing activity within the immune system. DCs shape quantitative and qualitative aspects of adaptive immunity, and therefore the intrinsic characteristics of host memory to a pathogen. DCs are essential in generating primary immune responses, due to their particular effectiveness in stimulating naïve T cells. DCs also play important roles in the reactivation of memory to an infectious agent, and as reservoirs for the dissemination of invading microorganisms. Exposure to pathogens or their products initiates a series of phenotypic and functional changes in DCs, termed maturation. DC maturation involves a coordinated response of immunomodulatory surface molecule elaboration and cytokine production, culminating in antigen presentation to, and co-stimulation of, T cells specific for the invading agent. The DC response is ostensibly tailored to facilitate effective elimination by regulating effective downstream interactions of the DC with T cells. A number of viruses have evolved to infect DCs and alter their functional behavior, facilitating their own survival within the host, and the herd. DV readily infects DCs both in primary cell cultures and in vivo. However, reports on the effects of DV infection on DC maturation vary both with regard to some of the cytokines produced, and the phenotypes of infected versus bystander cells. Although DCs appear to be activated following DV exposure, responses on the single-cell level appear to depend on the infection state of the cell, hypothetically driven by intracellular virus-mediated effects. Therefore, downstream responses to these divergent populations - i.e., actively infected cells versus uninfected bystander cells - are likely to be the consequence of at least two modes of DC behavior. Because DCs play a pivotal role in adaptive immune development, and because the resulting memory response appears to be critical in affecting disease pathology after heterologous DV re-infection, I sought to explore the phenomena of DC maturation in response to dengue exposure, and to begin to answer the question of how active infection alters the functional capabilities of DCs. Notably, primary dengue infection is generally well-controlled with minimal pathology. Therefore, this thesis addresses the hypothesis that DV infection of DCs results in cellular activation and stimulation of antiviral immunity, despite virus-mediated alteration of DC maturation. In order to address this hypothesis, I examined both DV infection-dependent and independent effects on DC functional responses including surface molecule regulation secretory activity, and CD4 T cell allostimulatory priming. DCs derived from human peripheral blood monocytes were readily infected with multiple strains of DV. DV infection of DCs derived from separate donors was dose-dependent, with substantial variability in DC susceptibility to infection. Exposure to live DV activated surface molecule expression in DCs, similar to the effects of defined maturation stimuli including a combination of TNF-α and IFN-α, or LPS. In addition, UV-inactivated DV induced expression of cell surface molecules, albeit to a lesser extent than did live virus demonstrating inherent stimulatory properties of DV particles. Using intracellular staining for DV envelope (E) protein, I detected increased surface molecule expression on both infected DCs and uninfected bystander DCs from the same culture, as compared to mock-infected DCs. These data indicate that activation was not prevented in cells undergoing active viral replication. However, the degree of surface molecule induction depended on the infection state of the cell. Infected DCs had enhanced PD-L2 and MHC II expression relative to uninfected bystander cells, while PD-L1, CD80, CD86, and MHC I expression were suppressed with active infection. Therefore, intracellular DV replication altered the process of cell surface molecule regulation within these cells. DV infection of DCs also resulted in the secretion of a broad array of cytokines and chernokines. These included the antiviral cytokine IFN-α, inflammatory cytokines TNF-α, IL-6, and IL-1α, and inflammatory chemokines IP10, MCP-1, MIP-1α, and RANTES. DV infection did not induce DC production of the IL-12 p70 heterodimer, and secretion of the immunosuppressive cytokine IL-10 was low in most experiments. Similar to the results seen with surface molecule induction, UV inactivation of DV reduced, but did not eliminate, cytokine and chemokine responses. At the single-cell level, TNF-α and IP10 production profiles of infected DCs and uninfected bystander DCs were distinct. DV infection in DCs reduced production of IP10, but stimulated TNF-α as compared to uninfected bystander cells in the same culture. Blocking experiments demonstrated that IFN-α/β produced by DCs in response to infection actively inhibited viral protein expression and drove IP10, but not TNF-α, production. DV infection of DCs did not consistently suppress DC stimulation of allogeneic CD4 T cell proliferation. In cases where infection enhanced DC stimulatory function, T cell proliferation was less pronounced than that induced by DCs activated with exogenous TNF-α plus IFN-α. Increasing multiplicity of infection (MOI) of DCs with DV resulted in increasing DC infection rates, but a statistically significant trend at the highest MOIs for decreased T cell alloproliferation, suggesting that direct infection of DCs reduces their CD4 T cell priming function. MOI-dependent reduction in DC stimulatory function depended on replication-competent virus. Increased MOIs during DV infection of DCs did not cause an elevation in detectable IL-10 in supernatants derived from T-DC co-cultures. In addition, increased DV MOI of DCs was not associated with increased levels of either IL-13 or IFN-γ in supernatants from T-DC co-culture, suggesting that actively infected DC do not skew CD4 T cells towards a specific Th phenotype. These data demonstrate that DV infection induces functional maturation of DCs that is modified by the presence of virus through both IFN-dependent and independent mechanisms. However, the allostimulatory phenotype of DCs was not universally enhanced, nor was it skewed towards antiviral (Th1)-type responses. These data suggest a model whereby dengue infection during primary illness results in controlled immune stimulation through activation of bystander DCs, and the generation of mixed Th-type responses. Direct DV infection of DCs appears to attenuate activation of, and potentially clearance by, antiviral mechanisms. During secondary infection, reduced IP10 production and enhanced TNF-α secretion by infected cells coupled with MHC I downregulation and enhanced PD-L2 expression, would subvert both Th1 CD4 T cell recruitment and result in CD8 T cell suppression and death. Furthermore, DV-specific effects on DCs would allow for continued viral replication in the absence of effective clearance. These DV-mediated effects would modify T cell memory responses to infected DC, and potentially facilitate the expansion of pathologic T cell subsets. Contributing to this pathological cascade, antibody-dependent enhancement of infection in monocytic cells and macrophages would shift antigen presentation and cytokine production paradigms, increasing the risk of DHF.

TNFα-induced programmed necrosis is a caspase-independent cell death program that is contingent upon the formation of a multiprotein complex termed the necrosome. The association of two of the components of the necrosome, receptor interacting protein 1 (RIP1) and RIP3, is a critical and signature molecular event during necrosis. Within this complex, both RIP1 and RIP3 are phosphorylated which are consequential for transmission of the pro-necrotic signal. Namely, it has been demonstrated that RIP3 phosphorylation is required for binding to downstream substrates. Nevertheless, the regulatory mechanisms governing necrosome activation remain unclear. Since necrosis is implicated in a variety of different diseases, understanding the biochemical signaling pathway can potentially yield future drug targets. I was interested in identifying other regulators of necrosis in hope of gaining a better understanding of the necrosis signaling pathway and regulators of the necrosome. To address this, I screened a cancer gene siRNA library in a cell line sensitive to necrosis. From this, I independently identified CYLD as a positive regulator of necrosis. Previous studies suggest that deubiquitination of RIP1 in the TNF receptor (TNFR)-1 signaling complex is a prerequisite for transition of RIP1 into the cytosol and assembly of the RIP1-RIP3 necrosome. The deubiquitinase cylindromatosis (CYLD) is presumed to promote programmed necrosis by facilitating RIP1 deubiquitination in this membrane receptor complex. Surprisingly, I found that TNFα could induce RIP1-dependent necrosis in CYLD-/- cells. I show that CYLD does not regulate RIP1 ubiquitination at the receptor complex. Strikingly, assembly of the RIP1-RIP3 necrosome was delayed, but not abolished in the absence of CYLD. In addition to the TNFR-1 complex, I found that RIP1 within the necrosome was also ubiquitinated. In the absence of CYLD, RIP1 ubiquitination in the NP-40 insoluble necrosome was greatly increased. Increased RIP1 ubiquitination correlated with impaired RIP1 and RIP3 phosphorylation, a signature of kinase activation. My results show that CYLD regulates RIP1 ubiquitination in the NP-40 insoluble necrosome, but not in the TNFR-1 signaling complex. Contrary to the current model, CYLD is not essential for necrosome assembly. Rather, it facilitates RIP1 and RIP3 activation within the necrosome and the corollary is enhancement of necrosome functionality and subsequent necrosis. My results therefore indicate that CYLD exerts its pro-necrotic function in the NP-40 insoluble necrosome, and illuminates the mechanism of necrosome activation.

Studien utvärderar egenskaper hos mesenkymala stromaceller (MSC) i passage 2 och 3. I ett samarbete mellan Cellcolabs och Karolinska Institutet (KI) genomfördes projektet med Katarina Le Blancs forskargrupp. Genom att studera membranmarkörer från tre friska MSC-donatorer, tillsammans med deras förmåga att differentiera till osteoblaster, adipocyter och kondrocyter, samt deras förmåga att inhibera profileringen av CD8+ och CD4+ T-lymfocyter, och slutligen deras möjlighet att öka uttrycket av Indoleamine 2,3-dioxygenase 1 (IDO1) och interleukin 6 (IL6), kunde en jämförelse mellan passage 2 och 3 göras. I korta drag kunde enbart en tydlig skillnad göras mellan de två passagerna. Skillnaden sågs i förmågan att differentiera till osteoblaster, där passage 3 inte kunde prestera på samma nivå som passage 2. Utöver detta var resultaten för de två typerna jämförbara och antydde inte till några större förändringar mellan passage 2 och 3. För att stärka tillförlitligheten av resultatet bör dock fler MSC-donatorer jämföras. / The study evaluates the characteristics and consistency of mesenchymal stromal cells (MSCs) in two different passages, specifically 2 and 3. In a collaboration between Cellcolabs and Karolinska Institutet (KI), the project was conducted with Katarina Le Blanc’s research group. Through studying the surface expression on cells from three distinct MSC donors, along with their differentiation ability into osteoblasts, adipocytes and chondrocytes, their capability to suppress the proliferation of CD8+ and CD4+ T lymphocytes, and finally their possibility to increase the expression of indoleamine 2,3-dioxygenase 1 (IDO1) and interleukin 6 (IL6), a comparison between passage 2 and 3 could be done. It was seen that a clear distinction could be made between the two passages while looking at their ability to differentiate into osteoblasts. The remaining results showed comparable outcomes between passage 2 and 3, suggesting minor changes with the increased passage number. However, to strengthen the reliability of the outcome, more MSC donors should be compared.