RESUMO
Studies that seek to understand which factors influence the patterns of infection in the lizard Coleodactylus meridionalis are non-existent. In this way, we recorded the infection rates for these lizards from three different sized fragments of the Atlantic rainforest and investigated if there is influence of the size, mass and sex of the host regarding the endoparasite abundance. In addition, we investigated if there were possible associations between the host's diet and parasitism, by calculating the diet niche breadth (based on the prey number of pooled stomachs) for each host population and comparing the diet between fragments and sexes (from the three sampled fragments). We collected 38 lizards across the three sampled forest fragments. We only found parasites in the lizards sampled from the smallest of the three forest fragments which included: Physaloptera lutzi, Haplometroides odhneri and Oligacanthorhynchus sp. For this population, lizards with greater length and body mass have a greater endoparasite abundance. In addition, based on the results obtained in our study, the diet of the lizards varies in food composition between sampled populations. Finally, knowing that among the infected lizards there is no sexual dimorphism in relation to size and body mass and that the stomach sampling for this population is insufficient to calculate the indexes related to the food niche; we used the number of prey lizards from all populations, thus we were able to associate the fact that female lizards have a greater endoparasite abundance due to variations in food composition between sexes.
RESUMO
The distribution of parasites within host populations and communities, and the mechanisms responsible for these patterns, are poorly understood aspects of wildlife parasitology. Here, we evaluate the influence of the average abundance of endoparasite variance, using endoparasites of lizards from the Caatinga domain (semiarid region), north-eastern Brazil. We hypothesized that, due to the high number of generalist endoparasite species, they may occur randomly throughout host populations in an aggregate pattern. In addition, we evaluated the degree to which sample variance is influenced by the average abundance of endoparasite species, patterns of co-occurrence and dominance among endoparasite species and similarities between abundance and the richness of endoparasite infracommunities in several host species. Between September 2015 and February 2016, 2141 lizards (1233 infected) from 16 species were collected from six Caatinga areas. In total, 25,687 endoparasites were collected, which belonged to 13 species including nematodes, pentastomids, cestodes, trematodes and acanthocephalans. Parasite-host associations documented here included 39 newly identified interactions. Endoparasites occurred in a typical aggregate pattern of distribution within their hosts; there was no measurable preference related to the acquisition of hosts by endoparasites. Despite the new records, endoparasites found were commonly associated with lizards in Caatinga environments, which may reflect fauna composed of generalist endoparasite species.
Assuntos
Lagartos/parasitologia , Parasitos , Acantocéfalos/classificação , Acantocéfalos/isolamento & purificação , Distribuição Animal , Animais , Brasil , Cestoides/classificação , Cestoides/isolamento & purificação , Helmintos/classificação , Helmintos/isolamento & purificação , Especificidade de Hospedeiro , Interações Hospedeiro-Parasita , Nematoides/classificação , Nematoides/isolamento & purificação , Parasitos/classificação , Parasitos/isolamento & purificação , Pentastomídeos/classificação , Trematódeos/classificação , Trematódeos/isolamento & purificaçãoRESUMO
The objective of this study was to evaluate the frequency of CD4+ T cell subsets in peripheral blood mononuclear cells (PBMC), urine and renal tissue from patients with lupus nephritis (LN). PBMC and urinary cells were collected from 17 patients with active LN, 20 disease controls (DC) with primary glomerulonephritis and 10 healthy controls (HC) and were analysed by flow cytometry with markers for T helper type 1 (Th1), Th2, Th17 and regulatory T cells (Treg ) cells. T cell subsets were assessed by immunohistochemistry from LN biopsy specimens from 12 LN patients. T cell subtypes in PBMC were re-evaluated at 6 months of therapy. CD4+ T cells were decreased in PBMC in LN compared with DC and HC (P = 0·0001). No differences were observed in urinary CD4+ T cell subsets between LN and DC. The frequency of urinary Th17 cells was higher in patients with non-proliferative than in proliferative LN (P = 0·041). CD3+ and T-box 21 ( Tbet+) cells were found in glomeruli and interstitium of LN patients, while forkhead box protein 3 (FoxP3), retinoid-related orphan receptor gamma (ROR-γ) and GATA binding protein 3 (GATA-3) were present only in glomeruli. Th1 cells in PBMC were correlated negatively with urinary Th1 cells (Rho = -0·531; P = 0·028) and with Tbet in renal interstitium (Rho = -0·782; P = 0·004). At 6 months, LN patients showed an increase in Th17 cells in PBMC. In conclusion, the inverse association between Th1 cells from PBMC and urinary/renal tissue indicate a role for Th1 in LN pathophysiology. Urinary Th17 cells were associated with less severe LN, and Th17 increased in PBMC during therapy. Urinary CD4+ T cells were not different between LN and DC.
Assuntos
Nefrite Lúpica/imunologia , Nefrite Lúpica/metabolismo , Linfócitos T Auxiliares-Indutores/imunologia , Linfócitos T Auxiliares-Indutores/metabolismo , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Adulto , Biomarcadores , Estudos de Casos e Controles , Feminino , Fator de Transcrição GATA3/metabolismo , Humanos , Imuno-Histoquímica , Imunofenotipagem , Nefrite Lúpica/patologia , Nefrite Lúpica/terapia , Contagem de Linfócitos , Masculino , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Subpopulações de Linfócitos T/patologia , Linfócitos T Auxiliares-Indutores/patologia , Linfócitos T Reguladores/patologia , Células Th1/imunologia , Células Th1/metabolismo , Células Th2/imunologia , Células Th2/metabolismoRESUMO
We analyzed the patterns of infection by helminths in populations of the Gymnophthalmidae lizard Dryadosaura nordestina from three Atlantic Forest fragments in Northeast Brazil. Prevalence and mean intensity of infection by location showed the following results: ARIE Mata de Goiamunduba (60.8 % and 10.4 ± 8), RPPN Engenho Gargaú (83.3 % and 20.8 ± 19.7) and Benjamim Maranhão Botanical Garden (70.4 % and 7.78 ± 5.8). We provide the first records of helminth infection for the lizard D. nordestina, in which three species of nematodes, Aplectana sp., Cosmocerca sp. and Physaloptera lutzi and one trematode Haplometroides odhneri were recovered. Trematodes of the genus Haplometroides were previously known as parasites only in snake and amphisbaenian hosts in South America. Now, our study provides the first record of a species belonging to this genus parasitizing lizards. In conclusion, our study shows that D. nordestina have a depleted helminth fauna (three species at maximum), similar to other studies with lizards of this family in Brazil and that its parasite abundance is related to host snout-vent length, but not to the sex.
RESUMO
Ecological characteristics and environmental variation influence both host species composition and parasite abundance. Abiotic factors such as rainfall and temperature can improve parasite development and increase its reproduction rate. The comparison of these assemblages between different environments may give us a more refined analysis of how environment affects the variation of helminth parasite abundance. The aim of the present study was to evaluate how temporal variation, host size, sex and reproduction affect helminth abundance in the Tropidurus hispidus lizard in Caatinga, Restinga and Atlantic Forest environments. Overall, larger-sized lizards showed higher helminth abundance. We found a monthly variation in the helminth species abundance in all studied areas. In the Caatinga area, monoxenic and heteroxenic parasites were related to the rainy season and to the reproductive period of lizards. In Restinga, monoxenic and heteroxenic helminth species were more abundant during the driest months. In the Atlantic Forest, the rainy and host reproductive season occurred continuously throughout the year, so parasite abundance was relatively constant. Nevertheless, heteroxenic species were more abundant in this area. The present results showed that the temporal variation, body size, sex, reproductive period and habitat type influence the abundance and composition of helminth species in T. hispidus.
Assuntos
Helmintíase Animal/parasitologia , Helmintos/classificação , Helmintos/isolamento & purificação , Lagartos/parasitologia , Carga Parasitária , Animais , Brasil , Exposição Ambiental , Análise Espaço-TemporalRESUMO
Trophic networks can have architectonic configurations influenced by historical and ecological factors. The objective of this study was to analyze the architecture of networks between lizards, their endoparasites, diet, and micro-habitat, aiming to understand which factors exert an influence on the composition of the species of parasites. All networks showed a compartmentalized pattern. There was a positive relation between diet and the diversity of endoparasites. Our analyses also demonstrated that phylogeny and the use of micro-habitat influenced the composition of species of endoparasites and diet pattern of lizards. The principal factor that explained the modularity of the network was the foraging strategy, with segregation between the "active foragers" and "sit-and-wait" lizards. Our analyses also demonstrated that historical (phylogeny) and ecological factors (use of micro-habitat by the lizards) influenced the composition of parasite communities. These results corroborate other studies with ectoparasites, which indicate phylogeny and micro-habitat as determinants in the composition of parasitic fauna. The influence of phylogeny can be the result of coevolution between parasites and lizards in the Caatinga, and the influence of micro-habitat should be a result of adaptations of species of parasites to occupy the same categories of micro-habitats as hosts, thus favoring contagion.
Assuntos
Ecossistema , Lagartos/parasitologia , Parasitos/classificação , Filogenia , Adaptação Fisiológica , Animais , Evolução Biológica , Brasil , Lagartos/classificaçãoRESUMO
OBJECTIVE: The identification of regulatory T cells (Treg cells) as CD4(+)CD25(high) cells may be upset by the increased frequency of activated effector T cells (Teff cells) in inflammatory diseases such as systemic lupus erythematosus (SLE). This study aimed to evaluate the frequency of T-cell subsets according to the expression of CD25 and CD127 in active (A-SLE) and inactive SLE (I-SLE). METHODS: Peripheral blood mononuclear cells (PBMCs) from 26 A-SLE patients (SLE Disease Activity Index (SLEDAI) = 10.17 ± 3.7), 31 I-SLE patients (SLEDAI = 0), and 26 healthy controls (HC) were analysed by multicolour flow cytometry. RESULTS: CD25(high) cell frequency was increased in A-SLE (5.2 ± 5.7%) compared to I-SLE (3.4 ± 3.4%) and HC (1.73 ± 0.8%) (p < 0.01). However, the percentage of FoxP3(+) cells in the CD25(high) subset was decreased in A-SLE (24.6 ± 16.4%) compared to I-SLE (33.7 ± 16) and HC (45 ± 25.1%) (p < 0.01). This was partly due to the increased frequency of Teff cells (CD25(high)CD127(+)FoxP3(Ø)) in A-SLE (10.7 ± 7.3%) compared to I-SLE (8.5 ± 6.5) and HC (6.1 ± 1.8%) (p = 0.02). Hence the frequency of Treg cells (CD25(+/high)CD127(low/Ø)FoxP3(+)) was equivalent in A-SLE (1.4 ± 0.8%), I-SLE (1.37 ± 1.0%), and HC (1.13 ± 0.59%) (p = 0.42). A-SLE presented an increased frequency of CD25(+)CD127(+)FoxP3(+) and CD25(Ø)FoxP3(+)CD127(low/Ø) T cells, which may represent intermediate phenotypes between Treg and Teff cells. CONCLUSIONS: The present study has provided data supporting normal Treg cell frequency in A-SLE and I-SLE as well as increased frequency of Teff cells in A-SLE. This scenario reflects a Treg/Teff ratio imbalance that may favour the inflammatory phenotype of the disease. In addition, the increased frequency of T cells with putative intermediate phenotypes may be compatible with a highly dynamic immune system in SLE.
Assuntos
Citometria de Fluxo/métodos , Imunofenotipagem/métodos , Lúpus Eritematoso Sistêmico/imunologia , Linfócitos T Reguladores/imunologia , Adulto , Contagem de Células , Feminino , Fatores de Transcrição Forkhead/metabolismo , Humanos , Subunidade alfa de Receptor de Interleucina-7/metabolismo , Lúpus Eritematoso Sistêmico/patologia , Lúpus Eritematoso Sistêmico/fisiopatologia , Masculino , Receptores de IgE/metabolismo , Índice de Gravidade de Doença , Linfócitos T Reguladores/metabolismo , Linfócitos T Reguladores/patologiaRESUMO
Different approaches using microscopy image analysis procedures were employed for characterization of activated sludge systems. The approaches varied mainly on the type of visualization and acquisition method used for collection of data. In this context, this study focused on the comparison of the two most common acquisition methods: bright field and phase-contrast microscopy. Images were acquired from seven different wastewater treatment plants for a combined period of two years. Advantages and disadvantages of each acquisition technique and the results are discussed. Bright field microscopy proved to be more simple and inexpensive and provided the best overall results.
Assuntos
Processamento de Imagem Assistida por Computador/métodos , Microscopia/métodos , Material Particulado/análise , Esgotos/microbiologia , Purificação da ÁguaRESUMO
The properties of activated sludge systems can be characterized using image analysis procedures. When these systems operate with high biomass content, accurate sludge characterization requires samples to be diluted. Selection of the best image acquisition magnification is directly related to the amount of biomass screened. The aim of the present study was to survey the effects of dilution and magnification on the assessment of aggregated and filamentous bacterial content and structure using image analysis procedures. Assessments of biomass content and structure were affected by dilutions. Therefore, the correct operating dilution requires careful consideration. Moreover, the acquisition methodology comprising a 100× magnification allowed data on aggregated and filamentous biomass to be determined and smaller aggregates to be identified and characterized, without affecting the accuracy of lower magnifications regarding biomass representativeness.
Assuntos
Bactérias/citologia , Processamento de Imagem Assistida por Computador/métodos , Microscopia/métodos , Esgotos/microbiologia , Técnicas Bacteriológicas/métodosRESUMO
The monitoring of emerging pollutants in wastewaters is nowadays an issue of special concern, with the classical quantification methods being time and reagent consuming. In this sense, a FTIR transmission spectroscopy based chemometric methodology was developed for the determination of eight of these pollutants. A total of 456 samples were, therefore, obtained, from an activated sludge wastewater treatment process spiked with the studied pollutants, and analysed in the range of 200â¯cm-1 to 14,000â¯cm-1. Then, a k-nearest neighbour (kNN) analysis aiming at identifying each sample pollutant was employed. Next, partial least squares (PLS) and ordinary least squares (OLS) modelling approaches were employed in order to obtain suitable prediction models. This procedure resulted in good prediction abilities regarding the estimation of atrazine, desloratadine, paracetamol, ß-estradiol, ibuprofen, carbamazepine, sulfamethoxazole and ethynylestradiol concentrations in wastewaters. These promising results suggest this technology as a fast, eco-friendly and reagent free alternative methodology for the quantification of emerging pollutants in wastewaters.
Assuntos
Monitoramento Ambiental/métodos , Espectroscopia de Infravermelho com Transformada de Fourier , Águas Residuárias/química , Poluentes Químicos da Água/análise , Monitoramento Ambiental/instrumentação , Análise dos Mínimos Quadrados , Modelos Teóricos , Espectroscopia de Infravermelho com Transformada de Fourier/métodosRESUMO
Acute lymphoblastic leukemia (ALL) accounts for approximately 80% of all acute leukemias during childhood. Chromosomal anomalies resulting from gene fusion, which are frequent in leukemias, create hybrid transcripts, the great majority of which encode transcription factors. We analyzed 88 pediatric patients (median age 7.3 years) who had B-lineage acute lymphoblastic leukemia (B-ALL), using reverse transcriptase-polymerase chain reaction, to look for gene fusion transcripts of TEL/AML1, E2A/PBX1, BCR/ABL p190, and MLL/AF4. The frequencies of these transcripts were 21.21, 9.68, 3.03, and 0%, respectively. All positive cases had a common B-ALL immunophenotype. The low frequency of the TEL/AML1 transcript that is found in developing countries, such as Brazil, may be due to the low incidence of leukemia; this would support Greaves' hypothesis.
Assuntos
Aberrações Cromossômicas , Mutação , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Brasil , Linhagem da Célula , Criança , Bases de Dados Genéticas , Feminino , Humanos , Imunofenotipagem , Masculino , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismoRESUMO
In recent years, a great deal of attention has been focused on the research of activated sludge processes, where the solid-liquid separation phase is frequently considered of critical importance, due to the different problems that severely affect the compaction and the settling of the sludge. Bearing that in mind, in this work, image analysis routines were developed in Matlab environment, allowing the identification and characterization of microbial aggregates and protruding filaments in eight different wastewater treatment plants, for a combined period of 2 years. The monitoring of the activated sludge contents allowed for the detection of bulking events proving that the developed image analysis methodology is adequate for a continuous examination of the morphological changes in microbial aggregates and subsequent estimation of the sludge volume index. In fact, the obtained results proved that the developed image analysis methodology is a feasible method for the continuous monitoring of activated sludge systems and identification of disturbances.
Assuntos
Bactérias/citologia , Interpretação de Imagem Assistida por Computador/métodos , Microscopia/métodos , Nefelometria e Turbidimetria/métodos , Esgotos/análise , Esgotos/microbiologia , Microbiologia da Água , Resíduos Industriais/análise , Resíduos Industriais/prevenção & controle , Purificação da Água/métodosRESUMO
The quantification of pollutants, as pharmaceuticals, in wastewater is an issue of special concern. Usually, typical methods to quantify these products are time and reagent consuming. This paper describes the development and validation of a Fourier transform near-infrared (FT-NIR) spectroscopy methodology for the quantification of pharmaceuticals in wastewaters. For this purpose, 276 samples obtained from an activated sludge wastewater treatment process were analysed in the range of 200â¯cm-1 to 14,000â¯cm-1, and further treated by chemometric techniques to develop and validate the quantification models. The obtained results were found adequate for the prediction of ibuprofen, sulfamethoxazole, 17ß-estradiol and carbamazepine with coefficients of determination (R2) around 0.95 and residual prediction deviation (RPD) values above four, for the overall (training and validation) data points. These results are very promising and confirm that this technology can be seen as an alternative for the quantification of pharmaceuticals in wastewater.
Assuntos
Preparações Farmacêuticas/análise , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Águas Residuárias/química , Poluentes Químicos da Água/análise , Limite de DetecçãoRESUMO
This work aims to explore the potential of near infrared (NIR) spectroscopy to quantify volatile compounds in Vinho Verde wines, commonly determined by gas chromatography. For this purpose, 105 Vinho Verde wine samples were analyzed using Fourier transform near infrared (FT-NIR) transmission spectroscopy in the range of 5435â¯cm-1 to 6357â¯cm-1. Boxplot and principal components analysis (PCA) were performed for clusters identification and outliers removal. A partial least square (PLS) regression was then applied to develop the calibration models, by a new iterative approach. The predictive ability of the models was confirmed by an external validation procedure with an independent sample set. The obtained results could be considered as quite good with coefficients of determination (R2) varying from 0.94 to 0.97. The current methodology, using NIR spectroscopy and chemometrics, can be seen as a promising rapid tool to determine volatile compounds in Vinho Verde wines.
Assuntos
Análise dos Mínimos Quadrados , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Compostos Orgânicos Voláteis/análise , Vinho/análise , Calibragem , Análise de Alimentos/métodos , Análise de Fourier , Análise de Componente Principal , Reprodutibilidade dos Testes , Processamento de Sinais Assistido por Computador , Espectroscopia de Infravermelho com Transformada de Fourier/métodosRESUMO
Sperm ultrastructure of five teiid lizards (Callopistes flavipunctatus, Crocodilurus amazonicus, Dicrodon guttulatum, Dracaena guianensis, and Teius oculatus), and the gymnophthalmid Cercosaura ocellata is described for the first time. Comparisons of sperm ultrastructure among these species and with those of previously examined teiids and gymnophthalmids revealed that the two groups of Teiioidea (Gymnophthalmidae and Teiidae), and the two subfamilies of Teiidae (Teiinae and Tupinambinae) could be distinguished on the basis of sperm ultrastructure data. Significant differences in sperm dimensions between Cnemidophorus and Aspidoscelis support the recent splitting of these two lineages into different genera. Our results revealed high levels of inter-generic variability in sperm ultrastructure within Teiidae, which produces a data set useful in analyzing relationships between genera and families. In phylogenetic analyses, however, sampling multiple species within teiid genera is essential and recording sperm measurements may profitably complement qualitative ultrastructural characters, maximizing the information content of these structures.
Assuntos
Classificação/métodos , Lagartos/anatomia & histologia , Filogenia , Espermatozoides/ultraestrutura , Animais , Fertilização/fisiologia , Variação Genética/fisiologia , Lagartos/fisiologia , Masculino , Microscopia Eletrônica de Transmissão , Espermatogênese/fisiologia , Espermatozoides/fisiologiaRESUMO
In Saccharomyces cerevisiae the vacuoles are partitioned from mother cells to daughter cells in a cell-cycle-coordinated process. The molecular basis of this event remains obscure. To date, few yeast mutants had been identified that are defective in vacuole partitioning (vac), and most such mutants are also defective in vacuole protein sorting (vps) from the Golgi to the vacuole. Both the vps mutants and previously identified non-vps vac mutants display an altered vacuolar morphology. Here, we report a new method to monitor vacuole inheritance and the isolation of six new non-vps vac mutants. They define five complementation groups (VAC8-VAC12). Unlike mutants identified previously, three of the complementation groups exhibit normal vacuolar morphology. Zygote studies revealed that these vac mutants are also defective in intervacuole communication. Although at least four pathways of protein delivery to the vacuole are known, only the Vps pathway seems to significantly overlap with vacuole partitioning. Mutants defective in both vacuole partitioning and endocytosis or vacuole partitioning and autophagy were not observed. However, one of the new vac mutants was additionally defective in direct protein transport from the cytoplasm to the vacuole.
Assuntos
Proteínas Fúngicas/metabolismo , Proteínas de Saccharomyces cerevisiae , ATPases Vacuolares Próton-Translocadoras , Vacúolos/genética , Leveduras/genética , Aminopeptidases/genética , Aminopeptidases/metabolismo , Núcleo Celular/genética , Endocitose/genética , Citometria de Fluxo/métodos , Fluorescência , Corantes Fluorescentes , Teste de Complementação Genética , Complexo de Golgi/metabolismo , Mitocôndrias/genética , Mutação , ATPases Translocadoras de Prótons/genética , ATPases Translocadoras de Prótons/metabolismo , Compostos de Piridínio/química , Compostos de Amônio Quaternário/química , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/genética , Vacúolos/classificação , Vacúolos/fisiologia , Leveduras/citologia , Leveduras/fisiologia , ZigotoRESUMO
Sequential or domino liver transplantation is a well-established procedure for patients with familial amyloidotic polyneuropathy (FAP). Donation for domino liver transplantation imposed the resection of the inferior vena cava along with the liver, requiring complete suprarenal vena cava clamping and usually the use of venovenous bypass. We describe a successful case in which it was possible to perform the FAP hepatectomy by the piggyback technique.
Assuntos
Neuropatias Amiloides Familiares/cirurgia , Transplante de Fígado/métodos , Adulto , Cadáver , Humanos , Masculino , Doadores de Tecidos , Resultado do TratamentoRESUMO
Yarrowia lipolytica, a yeast strain with a huge biotechnological potential, capable to produce metabolites such as γ-decalactone, citric acid, intracellular lipids and enzymes, possesses the ability to change its morphology in response to environmental conditions. In the present study, a quantitative image analysis (QIA) procedure was developed for the identification and quantification of Y. lipolytica W29 and MTLY40-2P strains dimorphic growth, cultivated in batch cultures on hydrophilic (glucose and N-acetylglucosamine (GlcNAc) and hydrophobic (olive oil and castor oil) media. The morphological characterization of yeast cells by QIA techniques revealed that hydrophobic carbon sources, namely castor oil, should be preferred for both strains growth in the yeast single cell morphotype. On the other hand, hydrophilic sugars, namely glucose and GlcNAc caused a dimorphic transition growth towards the hyphae morphotype. Experiments for γ-decalactone production with MTLY40-2P strain in two distinct morphotypes (yeast single cells and hyphae cells) were also performed. The obtained results showed the adequacy of the proposed morphology monitoring tool in relation to each morphotype on the aroma production ability. The present work allowed establishing that QIA techniques can be a valuable tool for the identification of the best culture conditions for industrial processes implementation.
Assuntos
Meios de Cultura/química , Micologia/métodos , Yarrowia/citologia , Yarrowia/crescimento & desenvolvimento , Técnicas de Cultura Celular por Lotes , Biomassa , Carbono/química , Carbono/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Hifas/citologia , Hifas/crescimento & desenvolvimento , Nitrogênio/metabolismo , Imagem Óptica/métodos , Yarrowia/metabolismoRESUMO
The traditional concept that effector T helper (Th) responses are mediated by Th1/Th2 cell subtypes has been broadened by the recent demonstration of two new effector T helper cells, the IL-17 producing cells (Th17) and the follicular helper T cells (Tfh). These new subsets have many features in common, such as the ability to produce IL-21 and to express the IL-23 receptor (IL23R), the inducible co-stimulatory molecule ICOS, and the transcription factor c-Maf, all of them essential for expansion and establishment of the final pool of both subsets. Tfh cells differ from Th17 by their ability to home to B cell areas in secondary lymphoid tissue through interactions mediated by the chemokine receptor CXCR5 and its ligand CXCL13. These CXCR5+ CD4+ T cells are considered an effector T cell type specialized in B cell help, with a transcriptional profile distinct from Th1 and Th2 cells. The role of Tfh cells and its primary product, IL-21, on B-cell activation and differentiation is essential for humoral immunity against infectious agents. However, when deregulated, Tfh cells could represent an important mechanism contributing to exacerbated humoral response and autoantibody production in autoimmune diseases. This review highlights the importance of Tfh cells by focusing on their biology and differentiation processes in the context of normal immune response to infectious microorganisms and their role in the pathogenesis of autoimmune diseases.
Assuntos
Doenças Autoimunes/imunologia , Autoimunidade/imunologia , Linfócitos T Auxiliares-Indutores/imunologia , Linfócitos B/imunologia , Linfócitos T CD4-Positivos/imunologia , Diferenciação Celular , Humanos , Interleucina-17/imunologia , Interleucinas/imunologia , Ativação Linfocitária/imunologia , Transdução de Sinais , Células Th17/imunologia , Células Th2/imunologiaRESUMO
Stress factors, such as osmotic stress and genotoxic agents, activate stress kinases, whereas growth factors preferentially stimulate the structurally homologous mitogen-activated protein kinases, ERK1/2. Hyperosmolarity also has insulin-mimicking action as reflected by ERK1/2 activation and by the stimulation of glucose uptake in adipocytes. We examined to what extent hyperosmolarity activates components of the insulin receptor (IR) signalling pathway. CHO cells expressing the human IR were treated with 500 mM NaCl or 700 mM sorbitol and the activation of insulin signalling intermediates was studied. Hyperosmolarity induced tyrosine phosphorylation of the IR beta-subunit, and the adaptor proteins p52-Shc, p66-Shc, and IRS1. Furthermore, the stress kinases JNK and p38 were activated. When CHO cells were transfected with a kinase-dead IR (K1030R) mutant, hyperosmolarity did not induce tyrosine phosphorylation of the IR, indicating that hyperosmolarity induced IR autophosphorylation directly, rather than inducing phosphorylation by an exogenous tyrosine kinase. A partially purified and detergent-solubilized IR was not phosphorylated in response to hyperosmolarity, suggesting that hyperosmolarity activates the receptor only when present in the plasma membrane. In cells stably expressing the kinase-dead IR, IRS1 and Shc Tyr phosphorylation was abrogated, indicating that the hyperosmolarity signalling was dependent on an active IR tyrosine kinase. In contrast, the stress kinases p38 and JNK were normally activated by hyperosmolarity in the IR-K1030R mutant. We conclude that, at least in CHO cells, hyperosmolarity signals partially through IR autophosphorylation and subsequent activation of the IR downstream targets. This may be responsible for some of the insulin-mimicking effects of hyperosmolarity. The activation of stress kinases by hyperosmolarity occurs independent of the IR.