933 resultados para Lymphocytes T CD4
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Les cellules mylodes incluant les monocytes, les macrophages et les cellules dendritiques (DCs, dendritic cells) contribuent la pathognse de linfection VIH-1 en participant la dissmination du virus, mais galement en reprsentant des rservoirs viraux potentiels. Leurs fonctions sont exploites par le VIH-1 afin dassurer sa propagation travers lorganisme. Notamment, une infection VIH-1 est associe une altration de la prsentation antignique et la perte de lymphocytes T CD4+ spcifiques des antignes. Lautophagie est un processus catabolique universel impliqu dans la rgulation de la prsentation antignique subsquente la neutralisation/destruction du pathogne. Des tudes rcentes suggrent que le VIH-1 altre le mcanisme dautophagie afin dassurer sa survie. Le premier volet de ce projet de matrise a vis la caractrisation des effets du VIH-1 sur lautophagie dans les DCs drives de monocytes circulants (MDDC, monocyte-derived dendritic cells) et lidentification des stratgies thrapeutiques pour contrecarrer ces effets. Les objectifs spcifiques ont t de : (i) caractriser lexpression de marqueurs de maturation sur des MDDC exposes au VIH-1 in vitro, (ii) quantifier lexpression des protines lies la rgulation positive (i.e., ATG5, LC3, p62) et ngative (i.e., mTOR) de lautophagie dans les MDDC exposes au VIH, (iii) dterminer le rle de lautophagie dans la trans infection du VIH-1 aux lymphocytes T CD4+ et (iv) explorer limpact de lautophagie sur la prsentation antignique par les MDDC infectes VIH-1 in vitro. Nos rsultats dmontrent quune exposition des MDDC au VIH-1 in vitro altre dramatiquement leur maturation et leur habilet induire la prolifration des cellules T autologues en rponse Staphylococcus aureus et Cytomegalovirus (CMV) mais pas la rponse induite par Staphylococcal enterotoxin B (SEB). Nous dmontrons que lexposition des MDDC au VIH sassocie une augmentation de lexpression de la protine mTOR totale et de sa forme phosphoryle (phospho-mTOR) et de la protine p62. Le traitement des MDDC la rapamycine diminue lexpression de mTOR et rduit la capacit de trans infection du VIH-1 par les MDDC, sans toutefois restaurer leur potentiel immunogne. En effet, nous observons que la rapamycine rduit lexpression de CD83 par les MDDC et augmente lexpression de CCR7, indiquant ainsi que leffet immunosuppresseur document de la rapamycine est associ une dfaillance de maturation des MDDC. Le second volet de ce projet de recherche sest intress la contribution des cellules mylodes la persistance virale chez les sujets infects par le VIH-1 sous thrapie antirtrovirale. Les objectifs spcifiques ont t : (i) dvaluer la prsence de diffrentes formes dADN viral dans les monocytes circulants de patients infects par le VIH-1 et (ii) de mesurer lintgration et la rplication virale dans des macrophages drivs de monocytes (MDM) de patients infects sous ART. Nos rsultats indiquent que les monocytes portent des formes prcoces de transcription virale inverse (ADN du VIH RU5) et que, malgr une charge virale plasmatique indtectable sous ART, les MDM supportent la rplication virale. Ces donnes trs prliminaires apportent des vidences en faveur de la contribution des cellules mylodes la persistance virale sous ART et reprsentent une ouverture pour un projet de recherche plus complexe dans le futur. En somme, nos rsultats dmontrent que le VIH-1 altre le potentiel immunogne des MDDC et que la rapamycine peut tre employe pour limiter la trans infection des lymphocytes T CD4+ par les MDDC. Nanmoins, lincapacit de la rapamycine rtablir le potentiel immunogne des MDDC incite identifier de nouvelles stratgies manipulant lautophagie pour une restauration optimale de la comptence immunitaire chez les sujets infects VIH-1. Les cellules mylodes jouent un rle primordial dans la dissmination et la persistance virale et doivent donc tre cibles par les stratgies actuelles dradication des rservoirs du VIH sous ART.
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La prsentation antignique par les molcules de classe II du complexe majeur dhistocompatibilit (CMH II) est un mcanisme essentiel au contrle des pathognes par le systme immunitaire. Le CMH II humain existe en trois isotypes, HLA-DP, DQ et DR, tous des htrodimres composs dune chane et dune chane . Le CMH II est entre autres exprim la surface des cellules prsentatrices dantignes (APCs) et des cellules pithliales actives et a pour fonction de prsenter des peptides dorigine exogne aux lymphocytes T CD4+. Loligomrisation et le trafic intracellulaire du CMH II sont largement facilits par une chaperone, la chane invariante (Ii). Il sagit dune protine non-polymorphique de type II. Aprs sa biosynthse dans le rticulum endoplasmique (ER), Ii htro- ou homotrimrise, puis interagit via sa rgion CLIP avec le CMH II pour former un complexe Ii. Le complexe sort du ER pour entamer son chemin vers diffrents compartiments et la surface cellulaire. Chez lhomme, quatre isoformes dIi sont rpertories : p33, p35, p41 et p43. Les deux isoformes exprimes de manire prdominante, Iip33 et p35, diffrent par une extension N-terminale de 16 acides amins porte par Iip35. Cette extension prsente un motif de rtention au rticulum endoplasmique (ERM) compos des rsidus RXR. Ce motif doit tre masqu par la chane du CMH II pour permettre au complexe de quitter le ER. Notre groupe sest intress au mcanisme du masquage et au mode de sortie du ER des complexes Ii. Nous montrons ici que linteraction directe, ou en cis, entre la chane du CMH II et Iip35 dans une structure Ii est essentielle pour sa sortie du ER, promouvant la formation de structures de haut niveau de complexit. Par ailleurs, nous dmontrons que NleA, un facteur de virulence bactrien, permet daltrer le trafic de complexes Ii comportant Iip35. Ce phnotype est mdi par linteraction entre p35 et les sous-units de COPII. Bref, Iip35 joue un rle central dans la formation des complexes Ii et leur transport hors du ER. Ceci fait dIip35 un rgulateur clef de la prsentation antignique par le CMH II.
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Fundao de Amparo Pesquisa do Estado de So Paulo (FAPESP)
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The advent of highly active antiretroviral therapy (HAART), since 1996, represented a profound impact on the natural history of HIV-infection by promoting important and sustainable viral replication suppression and increasing survival and quality of life among seropositive patients. Nonetheless, antiretroviral therapy has been observed to be accompanied by metabolic alterations such as dyslipidemia, especially hypertriglyceridemia, insulin resistance, hyperglycemia and lipodystrophy (body fat redistribution). Epidemiological studies have demonstrated a correlation between high triglyceride (TG) levels and higher incidence of coronary artery disease (CAD). Some investigators suggest dietary intervention as part of hyperlipidemia treatment, including an increase in soluble fiber intake (10-25g/day). Whereas some studies have demonstrated that both cholesterol and serum triglyceride levels decrease with the use of food fiber, others have shown just a serum triglyceride decrease, and others failed to observe any alteration in lipid metabolism. The purpose of this study was to assess the effect of soluble fiber (R) (partially hydrolyzed guar gum) supplementation on hypertriglyceridemia and immune profile in HIVpositive individuals on HAART. Nineteen HIV-positive individuals with hypertriglyceridemia (serum levels >= 150 to < 500mg/dl) were studied. of these individuals, 63.16% were males and 36.84% females, with mean age of 43.52 +/- 9.22 years. These individuals had been on the same HAART regimen for at least six months, had no change in therapy during the study and received 20g/day of soluble fiber for four months at pre-established times. Clinical-nutritional, biochemical (total proteins, albumin, globulin, total cholesterol, LDL-c, HDL-c, TG, TG/HDL-c and LDLc/HDL-c), hematimetric (hemoglobin, hematocrit and total lymphocytes), and immunologic (lymphocytes T CD4(+), T CD8(+); T CD4(+)/CD8(+) ratio, viral load, TNF-alpha and IL-6) parameters were assessed in all patients at three time points (M0: pretreatment, M1: 30 days, and M2: four months after intervention). Significance level was set at 5% for all data statistically analyzed. Serum TG and TG/HDL-c ratio reduction was observed at all time points, but statistical significance was found just at M0 and M2. The remaining biochemical, hematimetric and immunologic parameters (lymphocytes T CD4(+), T CD8(+); T CD4(+)/ CD8(+) ratio, and viral load) showed no significant difference at all times. Regarding serum cytokines, TNF-alpha and IL-6 significantly decreased between M0 and M2, and only IL-6 reduced between M1 and M2. The data collected show that dietary and anthropometric parameters remained unchanged excluding potential confounding factors related with the effect of fiber supplementation on serum TG, TNF-alpha and IL-6. Thus, soluble fiber (R) contributed to an important reduction in hypertriglyceridemia and in the serum levels of the proinflammatory cytokines TNF-alpha and IL-6 in HIV-seropositive individuals on HAART. In addition, soluble fiber (R) might have minimized the process of atherosclerosis in these individuals, given that elevated serum levels of TG, TNF-alpha and IL-6 have been associated with the development of these lesions.
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Ps-graduao em Doenas Tropicais - FMB
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Fundao de Amparo Pesquisa do Estado de So Paulo (FAPESP)
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Coordenao de Aperfeioamento de Pessoal de Nvel Superior (CAPES)
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A estimativa de pessoas infectadas pelo HIV no mundo, no ano de 2006, foi cerca de 39,5 milhes. No Brasil, o Ministrio da Sade indica terapia para pacientes com manifestaes clnicas associadas ao HIV-1 e para aqueles com contagem de linfcitos T CD4<sup>+</sup> abaixo de 200 clulas/ mm<sup>3</sup>. Paralelamente aos benefcios da terapia anti-retroviral h o reconhecimento de efeitos adversos, como miopatia, lipodistrofia, pancreatite, hepatotoxicidade e acidose ltica. A complexidade dos esquemas teraputicos torna a adeso terapia difcil, contribuindo para a falha teraputica. Neste trabalho foi realizado um estudo epidemiolgico, de monitoramento de Lamivudina (3TC) e Zidovudina (AZT) e correlacionado com as funes heptica, renal e nutricional em pacientes portadores de HIV-1, atendidos na CASA DIA, em Belm/PA. O grupo populacional estudado constou de 60 portadores do HIV-1 de ambos os gneros, com faixa etria de 20 a 61 anos, que faziam uso de AZT e/ou 3TC. Os nveis plasmticos de aminotransferases, uria e creatinina foram determinados por fotometria de absoro e, por Cromatografia Lquida de Alta Eficincia, foram determinadas as concentraes plasmticas de 3TC e AZT. O estado nutricional foi avaliado atravs do ndice de Massa Corprea (IMC). As concentraes de 3TC variaram de 1,283 a 355,953 g/mL, enquanto que as de AZT variaram de 0,008 a 22,544 g/mL. A concentrao de 3TC evidenciou associao com a ocupao (p < 0,05) e com a creatininemia (p < 0,0001), mas no com as aminotrasnferases e uremia (p > 0,05). No encontramos associao entre a concentrao de AZT com as informaes demogrficas e com a creatininemia (p > 0,05), todavia verificou-se associao com as aminotransferases e uremia (p < 0,0001). O IMC revelou associao com todos os parmetros estudados: concentraes de 3TC, AZT, aminotransferases, uremia e creatininemia (p < 0,05). Conclumos que as concentraes de 3TC podem afetar os nveis de creatinina e sofrem influncia do estado nutricional do paciente, enquanto que as concentraes de AZT podem alterar os nveis de aminotransferases, uria e tambm so influenciadas pelo estado nutricional, ratificando os processos farmacocinticos desses frmacos.
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Fundao de Amparo Pesquisa do Estado de So Paulo (FAPESP)
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The aim of the present trial was to determine the frequencies and absolute number of B and T lymphocytes subpopulations in bovine leukemia virus (BLV)-infected dairy cows with distinct lymphocyte profile known as non-leukemic (AL) and persistent lymphocytosis (PL). Thus, 15 animals were selected and divided uniformly in three groups (negative, AL, PL). The BLV infection was detected by agar gel immunodiffusion and enzyme-linked immunosorbent-assay. The lymphocytes subsets were evaluated using monoclonal antibodies by flow cytometry. The results of the present study pointed out to an increase in B lymphocytes, and also an augment in CD5(+) and CD11b(+) cells in animals showing PL. Consequently, it can be observed a decrease in the percentage of T cells subsets in these animals. Conversely, no significant alterations in the absolute number of the T lymphocytes, T CD4(+) cells and T CD8(+) lymphocytes were found in BLV-infected dairy cows with PL. Therefore, the correlation between the absolute numbers of B- and T cell subsets in the peripheral blood applied to each group showed a significant and positive strong correlation between numbers of B cells and T cells or T CD8(+) cells in the PL animals, although the same cannot be predicted for T CD4(+) lymphocytes. No such correlation was encountered for the AL and negative-control animals.
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Abstract Objectives In this work we investigated how immunological dysfunction and malnutrition interact in alcoholic and viral aetiologies of cirrhosis. Methods To investigate the matter, 77 cirrhotic patients divided in three aetiologies [Alcohol, HCV and Alcohol + HCV) and 32 controls were prospectivelly and sequentially studied. Parameters of humoral immunity (Components 3 and 4 of seric complement and immunoglobulins A M, G and E) and of cellular immunity (total leukocytes and lymphocytes in peripheral blood, T lymphocytes subpopulations, CD4+ and CD8+, CD4+/CD8+ ratio and intradermic tests of delayed hypersensitivity), as well as nutrititional parameters: anthropometric measures, serum albumin and transferrin were evaluated. Results Multiple statistical comparisons showed that IgM was higher in HCV group; IgG was significantly elevated in both HCV and Alcohol + HCV, whereas for the Alcohol group, IgE was found at higher titles. The analysis of T- lymphocytes subpopulations showed no aetiologic differences, but intradermic tests of delayed hypersensitivity did show greater frequency of anergy in the Alcohol group. For anthropometric parameters, the Alcohol +HCV group displayed the lowest triceps skinfold whereas creatinine height index evaluation was more preserved in the HCV group. Body mass index, arm muscle area and arm fat area showed that differently from alcohol group, the HCV group was similar to control. Conclusion Significant differences were found among the main aetiologies of cirrhosis concerning immunological alterations and nutritional status: better nutrition and worse immunology for HCV and vice-versa for alcohol.
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Immunosenescence is characterized by a complex remodelling of the immune system, mainly driven by lifelong antigenic burden. Cells of the immune system are constantly exposed to a variety of stressors capable of inducing apoptosis, including antigens and reactive oxygen species continuously produced during immune response and metabolic pathways. The overall homeostasis of the immune system is based on the balance between antigenic load, oxidative stress, and apoptotic processes on one side, and the regenerative potential and renewal of the immune system on the other. Zinc is an essential trace element playing a central role on the immune function, being involved in many cellular processes, such as cell death and proliferation, as cofactor of enzymes, nuclear factors and hormones. In this context, the age associated changes in the immune system may be in part due to zinc deficiency, often observed in aged subjects and able to induce impairment of several immune functions. Thus, the aim of this work was to investigate the role of zinc in two essential events for immunity during aging, i.e. apoptosis and cell proliferation. Spontaneous and oxidative stress-induced apoptosis were evaluated by flow cytometry in presence of a physiological concentration of zinc in vitro on peripheral blood mononuclear cells (PBMCs) obtained from healthy subjects of different age: a group of young subjects, a group of old subjects and a group of nonagenarians. In addition, cell cycle phases were analyzed by flow cytometry in PBMCs, obtained from the subjects of the same groups in presence of different concentration of zinc. We also analyzed the influence of zinc in these processes in relation to p53 codon 72 polymorphism, known to affect apoptosis and cell cycle in age-dependent manner. Zinc significantly reduces spontaneous apoptosis in all age-groups; while it significantly increases oxidative stress-induced late apoptosis/necrosis in old and nonagenarians subjects. Some factors involved in the apoptotic pathway were studied and a zinc effect on mitochondrial membrane depolarization, cytochrome C release, caspase-3 activation, PARP cleavage and Bcl-2 expression was found. In conclusion, zinc inhibits spontaneous apoptosis in PBMCs contrasting the harmful effects due to the cellular culture conditions. On the other hand, zinc is able to increase toxicity and induce cell death in PBMCs from aged subjects when cells are exposed to stressing agents that compromise antioxidant cellular systems. Concerning the relationship between the susceptibility to apoptosis and p53 codon 72 genotype, zinc seems to affect apoptosis only in PBMCs from Pro- people suggesting a role of this ion in strengthening the mechanism responsible of the higher propensity of Pro- towards apoptosis. Regarding cell cycle, high doses of zinc could have a role in the progression of cells from G1 to S phase and from S to G2/M phase. These effect seems depend on the age of the donor but seems to be unrelated to p53 codon 72 genotype. In order to investigate the effect of an in vivo zinc supplementation on apoptosis and cell cycle, PBMCs from a group of aged subjects were studied before and after six weeks of oral zinc supplementation. Zinc supplementation reduces spontaneous apoptosis and it strongly reduces oxidative stress-induced apoptosis. On the contrary, no effect of zinc was observed on cell cycle. Therefore, its clear that in vitro and in vivo zinc supplementation have different effects on apoptosis and cell cycle in PBMCs from aged subjects. Further experiments and clinical trials are necessary to clarify the real effect of an in vivo zinc supplementation because this preliminary data could encourage the of this element in all that disease with oxidative stress pathogenesis. Moreover, the expression of metallothioneins (MTs), proteins well known for their zinc-binding ability and involved in many cellular processes, i.e. apoptosis, metal ions detoxification, oxidative stress, differentiation, was evaluated in total lymphocytes, in CD4+ and in CD8+ T lymphocytes from young and old healthy subjects in presence of different concentration of zinc in vitro. Literature data reported that during ageing the levels of these proteins increase and concomitantly they lose the ability to release zinc. This fact induce a down-regulation of many biological functions related to zinc, such as metabolism, gene expression and signal transduction. Therefore, these proteins may turn from protective in young-adult age to harmful agents for the immune function in ageing following the concept that several genes/proteins that increase fitness early in life may have negative effects later in life: named Antagonistic Pleyotropy Theory of Ageing. Data obtained in this work indicate an higher and faster expression of MTs with lower doses of zinc in total lymphocytes, in CD4+ and in CD8+ T lymphocytes from old subjects supporting the antagonistic pleiotropic role of these proteins.
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La prsentation antignique par les molcules de classe II du complexe majeur dhistocompatibilit (CMH II) est un mcanisme essentiel au contrle des pathognes par le systme immunitaire. Le CMH II humain existe en trois isotypes, HLA-DP, DQ et DR, tous des htrodimres composs dune chane et dune chane . Le CMH II est entre autres exprim la surface des cellules prsentatrices dantignes (APCs) et des cellules pithliales actives et a pour fonction de prsenter des peptides dorigine exogne aux lymphocytes T CD4+. Loligomrisation et le trafic intracellulaire du CMH II sont largement facilits par une chaperone, la chane invariante (Ii). Il sagit dune protine non-polymorphique de type II. Aprs sa biosynthse dans le rticulum endoplasmique (ER), Ii htro- ou homotrimrise, puis interagit via sa rgion CLIP avec le CMH II pour former un complexe Ii. Le complexe sort du ER pour entamer son chemin vers diffrents compartiments et la surface cellulaire. Chez lhomme, quatre isoformes dIi sont rpertories : p33, p35, p41 et p43. Les deux isoformes exprimes de manire prdominante, Iip33 et p35, diffrent par une extension N-terminale de 16 acides amins porte par Iip35. Cette extension prsente un motif de rtention au rticulum endoplasmique (ERM) compos des rsidus RXR. Ce motif doit tre masqu par la chane du CMH II pour permettre au complexe de quitter le ER. Notre groupe sest intress au mcanisme du masquage et au mode de sortie du ER des complexes Ii. Nous montrons ici que linteraction directe, ou en cis, entre la chane du CMH II et Iip35 dans une structure Ii est essentielle pour sa sortie du ER, promouvant la formation de structures de haut niveau de complexit. Par ailleurs, nous dmontrons que NleA, un facteur de virulence bactrien, permet daltrer le trafic de complexes Ii comportant Iip35. Ce phnotype est mdi par linteraction entre p35 et les sous-units de COPII. Bref, Iip35 joue un rle central dans la formation des complexes Ii et leur transport hors du ER. Ceci fait dIip35 un rgulateur clef de la prsentation antignique par le CMH II.
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Mmoire numris par la Direction des bibliothques de l'Universit de Montral.
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Mmoire numris par la Direction des bibliothques de l'Universit de Montral.
