<p>Apoptosis or programmed cell death is crucial for the resolution of inflammation, and phagocytosis of apoptotic cells initiates the release of actively anti-inflammatory responses from the phagocytes. Eosinophils are one of the most potent inflammatory cells in the body and is involved in a number of diseases, most commonly associated with parasitic infections and allergic diseases. Apoptosis in eosinophils is therefore one of the most important systems to avoid inflammation. This aim of the present investigation was to examine the mechanisms behind, and the consequences of this process in eosinophils. Apoptotic eosinophils have a unique surface receptor expression that indicates abilities to communicate with T-, B- and antigen presenting cells. They have a novel expression of CD49f, indicating an importance for binding to laminin or unknown functions of the VLA-6 receptor, possibly in the concept of phagocytosis of the apoptotic cell. </p><p>In apoptotic eosinophils the granules are translocated to the periphery of the cell, probably through a disruption of the cytoskeleton. This translocation makes the granules easily accessible and the apoptotic eosinophil can release considerable amounts of granule proteins in response to specific stimuli. The spontaneous release however, is decreased as compared with living cells. </p><p>Furthermore, the survival of eosinophils in response to an allergen challenge is increased in healthy subjects, but not in allergic patients. Mechanistically, this needs further investigation, but one theory is that it is due to the presence of specific IgE in patients in combination with differences in the response from the epithelial cells.</p>

Apoptosis or programmed cell death is crucial for the resolution of inflammation, and phagocytosis of apoptotic cells initiates the release of actively anti-inflammatory responses from the phagocytes. Eosinophils are one of the most potent inflammatory cells in the body and is involved in a number of diseases, most commonly associated with parasitic infections and allergic diseases. Apoptosis in eosinophils is therefore one of the most important systems to avoid inflammation. This aim of the present investigation was to examine the mechanisms behind, and the consequences of this process in eosinophils. Apoptotic eosinophils have a unique surface receptor expression that indicates abilities to communicate with T-, B- and antigen presenting cells. They have a novel expression of CD49f, indicating an importance for binding to laminin or unknown functions of the VLA-6 receptor, possibly in the concept of phagocytosis of the apoptotic cell. In apoptotic eosinophils the granules are translocated to the periphery of the cell, probably through a disruption of the cytoskeleton. This translocation makes the granules easily accessible and the apoptotic eosinophil can release considerable amounts of granule proteins in response to specific stimuli. The spontaneous release however, is decreased as compared with living cells. Furthermore, the survival of eosinophils in response to an allergen challenge is increased in healthy subjects, but not in allergic patients. Mechanistically, this needs further investigation, but one theory is that it is due to the presence of specific IgE in patients in combination with differences in the response from the epithelial cells.

The Arabidopsis cyclic nucleotide-gated ion channels (AtCNGCs) form a large family consisting of 20 members. It has been suggested that CNGCs contribute to a wide array of biological functions such as pollen tube growth and pathogen defence signalling. However, the precise mechanisms by which AtCNGCs act, and the extent of their biological roles, have yet to be fully elucidated. AtCNGC11/12, the chimeric CNGC that resulted from the fusion of AtCNGC11 and 12, induces a number of pathogen defence related phenotypes in the Arabidopsis mutant cpr22. Spontaneous lesion formation is one such phenotype. Interestingly, when AtCNGC11/12 is transiently expressed in N. benthamiana it causes cell death which was characterized in this study. Also, AtCNGC11/12 was used to investigate the structural features responsible for the proper function and regulation of AtCNGCs. Electron microscopic analysis of the AtCNGC11/12-induced cell death showed similar characteristics to programmed cell death (PCD), such as plasma membrane shrinkage and vesicle formation. Interestingly caspase-1 inhibitors and the silencing of vacuolar processing enzyme, a plant enzyme with caspase-1 activity, suppressed the induction of cell death. Additionally, pharmacological analyses indicated that the AtCNGC11/12-indiced cell death was also dependent on Ca2+. Furthermore, 3 amino acid residues, R190, A225, and G287, were demonstrated to be essential for AtCNGC11/12-induce cell death. Taken together, these results indicate that the cell death that develops in the cpr22 mutant is indeed PCD and that AtCNGC11/12, is at the point of, or up-stream of, the Ca2+ signal necessary for the development of HR. Furthermore, the functionality of AtCNGC11/12 as a model for AtCNGC structure-function analyses was demonstrated by the identification of several amino acids necessary for cell death development. Yoshioka et al. (2006) demonstrated that the loss of AtCNGC11 or 12 results in decreased resistance to avirulent isolates of the oomycete pathogen, H. arabidopsidis. Thus, the present biological role suggested for AtCNGC11 and 12 is in pathogen defence, specifically within effector triggered immunity (ETI). Like AtCNGC11 and 12, AtCNGC2 has been demonstrated to contribute to pathogen defence signalling but has also been implicated in other physiological responses such as ion stress and senescence. To better understand the roles of AtCNGC11 and 12 in both pathogen defence and other Ca2+ dependent signalling processes, I have investigated promoter:GUS reporter lines, as well as, AtCNGC11 and 12 KO and RNAi silenced lines subjected to various treatments. From this work, I have demonstrated that AtCNGC11 and 12 have similar expression patterns during pathogen defence, development, and dark-induced senescence. Additionally, the findings presented here further characterize AtCNGC11 and 12 as contributors to ETI rather than PAMP triggered immunity. Furthermore, I demonstrated that AtCNGC11 and 12 are likely involved in the endogenous movement of Ca2+, contributing to a range of Ca2+ associated signalling pathways including gravitropism and senescence. Taken together, these results have greatly improved the characterization of AtCNGC11 and 12; significantly contributing to the understanding of a large and increasingly important channel family.

Plant programmed cell death (PCD) is an essential process in plant-pathogen interactions. Importantly, PCD can have contrasting effects on the outcome depending on context. For example, plant PCD in plant-biotroph interactions is clearly beneficial to plants, whereas it could be detrimental to plants in plant-necrotroph interactions. Sclerotinia sclerotiorum is an agriculturally and economically important necrotrophic pathogen. Previous studies have shown that S. sclerotiorum secretes oxalic acid (OA) to enhance Sclerotinia virulence by various mechanisms including induction of PCD in plants. A recent study has also shown that reactive oxygen species (ROS) generation correlates with induction of PCD during disease development. These studies focus on links between ROS, oxalate, and PCD, and how they impact S. sclerotiorum disease development. I examined the involvement of ROS in pathogenic development of S. sclerotiorum. I identified and functionally characterized two predicted S. sclerotiorum NADPH oxidases (Nox1 and Nox2) by RNAi. Both nox genes appear to have roles in sclerotial development, while only Nox1-silenced mutants showed reduced virulence. Interestingly, the reduced virulence of the Nox1-silenced mutant correlated with decreased production of OA in the mutant. This observation suggests that regulation of ROS by S. sclerotiorum Nox1 may be linked to OA. The next study details the phenotype of plants inoculated with an S. sclerotiorum oxalate deficient mutant (A2), which showed restricted growth at the infected site. This response resembles the hypersensitive response (HR), and is associated with plant resistance responses including cell wall strengthening, plant oxidative burst, and induction of defensin genes. Conversely, leaves infected with wild type showed unrestricted spreading of cell death and were not associated with these resistant responses. Furthermore, previous work had shown that a Caenorhabditis elegans anti-apoptotic gene (ced-9) conferred resistance to wild type S. sclerotiorum, while this gene had negligible effects on the phenotype of plant leaves inoculated with A2 mutants. These findings suggest that HR-like cell death by A2 and PCD by wild type S. sclerotiorum may be regulated by different pathways. As a whole, these results reveal the importance of ROS, oxalate, and PCD in Sclerotinia disease development as well as the significance of interplay between them. These studies contribute to the understanding of the underlying mechanisms of Sclerotinia disease.

The Arabidopsis cyclic nucleotide-gated ion channels (AtCNGCs) form a large family consisting of 20 members. It has been suggested that CNGCs contribute to a wide array of biological functions such as pollen tube growth and pathogen defence signalling. However, the precise mechanisms by which AtCNGCs act, and the extent of their biological roles, have yet to be fully elucidated. AtCNGC11/12, the chimeric CNGC that resulted from the fusion of AtCNGC11 and 12, induces a number of pathogen defence related phenotypes in the Arabidopsis mutant cpr22. Spontaneous lesion formation is one such phenotype. Interestingly, when AtCNGC11/12 is transiently expressed in N. benthamiana it causes cell death which was characterized in this study. Also, AtCNGC11/12 was used to investigate the structural features responsible for the proper function and regulation of AtCNGCs. Electron microscopic analysis of the AtCNGC11/12-induced cell death showed similar characteristics to programmed cell death (PCD), such as plasma membrane shrinkage and vesicle formation. Interestingly caspase-1 inhibitors and the silencing of vacuolar processing enzyme, a plant enzyme with caspase-1 activity, suppressed the induction of cell death. Additionally, pharmacological analyses indicated that the AtCNGC11/12-indiced cell death was also dependent on Ca2+. Furthermore, 3 amino acid residues, R190, A225, and G287, were demonstrated to be essential for AtCNGC11/12-induce cell death. Taken together, these results indicate that the cell death that develops in the cpr22 mutant is indeed PCD and that AtCNGC11/12, is at the point of, or up-stream of, the Ca2+ signal necessary for the development of HR. Furthermore, the functionality of AtCNGC11/12 as a model for AtCNGC structure-function analyses was demonstrated by the identification of several amino acids necessary for cell death development. Yoshioka et al. (2006) demonstrated that the loss of AtCNGC11 or 12 results in decreased resistance to avirulent isolates of the oomycete pathogen, H. arabidopsidis. Thus, the present biological role suggested for AtCNGC11 and 12 is in pathogen defence, specifically within effector triggered immunity (ETI). Like AtCNGC11 and 12, AtCNGC2 has been demonstrated to contribute to pathogen defence signalling but has also been implicated in other physiological responses such as ion stress and senescence. To better understand the roles of AtCNGC11 and 12 in both pathogen defence and other Ca2+ dependent signalling processes, I have investigated promoter:GUS reporter lines, as well as, AtCNGC11 and 12 KO and RNAi silenced lines subjected to various treatments. From this work, I have demonstrated that AtCNGC11 and 12 have similar expression patterns during pathogen defence, development, and dark-induced senescence. Additionally, the findings presented here further characterize AtCNGC11 and 12 as contributors to ETI rather than PAMP triggered immunity. Furthermore, I demonstrated that AtCNGC11 and 12 are likely involved in the endogenous movement of Ca2+, contributing to a range of Ca2+ associated signalling pathways including gravitropism and senescence. Taken together, these results have greatly improved the characterization of AtCNGC11 and 12; significantly contributing to the understanding of a large and increasingly important channel family.

O exercício físico intenso está associado à mudanças na quantidade, na função e na morte de neutrófilos. Tem sido proposto que a suplementação com óleo de peixe minimiza os efeitos imunossupressivos do exercício físico e que a fosfatidilcolina também poderia exercer importantes efeitos sobre a função de leucócitos. O objetivo do estudo foi o de investigar os efeitos da meia maratona e da suplementação com lecitina de soja ou óleos de peixe ricos em EPA ou DHA na apoptose de neutrófilos de atletas amadores. Quarenta e seis atletas amadores, foram avaliados antes e após duas competições de meia maratona. Na primeira meia maratona, os atletas não foram suplementados. As coletas de sangue dos atletas foram realizadas nas seguintes condições: Em repouso e imediatamente após a competição. No primeiro dia, após a primeira meia maratona, iniciou-se a suplementação. Os indivíduos foram suplementados diariamente com 3g de óleo de peixe ou lecitina de soja, por 60 dias, e divididos em 3 grupos: 1) Lecitina, 2) DHA e 3) EPA. Os atletas foram reavaliados 8 semanas após o início da suplementação. Já na segunda meia maratona, com todos os atletas suplementados, as coletas de sangue foram realizadas nas mesmas condições da primeira corrida. Neste estudo avaliamos os receptores da apoptose de neutrófilos (Fas e TRAIL), as moléculas de adesão (L-selectina e ICAM-1), a fragmentação de DNA e a externalização de fosfatidilserina. Além disso, foi avaliada a concentração plasmática das citocinas TNF-alfa, IL-8, IL-6, IL-4, IL-10 e IL-1beta. As enzimas creatina quinase e lactato desidrogenase, a concentração de mioglobina, proteína C reativa e o número de leucócitos e neutrófilos também foi determinada. A meia maratona aumentou a atividade das enzimas CK e LDH e a concentração de mioglobina em todos os grupos estudados, sendo que a suplementação não apresentou nenhum efeito sobre estes parâmetros. Já o número de neutrófilos e leucócitos, aumentaram após a meia maratona em todos os grupos, e a suplementação provocou este aumento somente nos grupos EPA e Lecitina. Em neutrófilos de atletas, a meia maratona diminuiu a expressão dos receptores Fas e TRAIL e das móleculas de adesão ICAM-1 e L-selectina em todos os grupos, por outro lado, aumentou a fragmentação de DNA (somente no grupo DHA) e a externalização de FS (DHA, EPA e Lectina). A meia maratona também elevou a concentração das citocinas IL-8, IL-6 e IL-10 em todos os grupos. Já a suplementação (DHA, EPA ou lecitina de soja) diminuiu a fragmentação de DNA e a expressão do receptor Fas em neutrófilos. Além disso, aumentou a expressão de TRAIL, ICAM-1, L-selectina e a externalização de fosfatidilserina. Em relação a concentração plasmática de citocinas a suplementação reduziu a concentração de TNF-alfa e aumentou a de IL-10 em todos os grupos. Enquanto que, a concentração de IL-4 aumentou somente nos grupos DHA e EPA. Concluímos que a suplementação com lecitina de soja apresenta efeitos semelhantes aos dos óleos de peixe ricos em EPA ou DHA sobre a função de leucócitos em atletas amadores. / Intense physical exercise is associated with changes in the number, function and death of neutrophils. It has been proposed that supplementation with fish oil rich minimizes the immunosuppressive effects induced by intense physical exercise and phosphatidylcholine could also have significant effects on leukocytes function. The aim of this study was to investigate the effects of a half-marathon and fish oil suplemmentation rich in EPA or DHA or soy lecithin suplemmentation on neutrophils apoptosis of amateur athletes. Forty-six recreational athletes were evaluated before and after two half marathons. In the first competition the athletes did not receive supplementation. Blood samples were collected in the following conditions: In rest and immediately after competition. On the first day, after the first half-marathon, supplementation began. The subjects were supplemented with 3 g of fish oil or soy lecithin daily for 60 days and divided into 3 groups: 1) Lecithin 2) DHA 3) EPA. The athletes were assessed 8 weeks after the start of supplementation. In the second half-marathon, with all the supplemented athletes, blood samples were collected under the same conditions of the first competition. In this study were evaluated the receptors of neutrophils apoptosis (Fas and TRAIL), adhesion molecules (L-selectin and ICAM-1), DNA fragmentation and phosphatidylserine externalization. Moreover, the plasma concentration of TNF-alpha, IL-8, IL-6, IL-4, IL-10 and IL-1beta cytokines was evaluated. The enzymatic activity of creatine kinase and lactate dehydrogenase, plasma concentration of myoglobin, and C-reactive protein and blood counts was also determined. The half-marathon increased the enzymatic activity of CK and LDH and the myoglobin concentration in all groups studied, and the supplementation had no effect on these parameters. The number of neutrophils and leucocytes increased in all groups after half marathon, and the supplementation caused this increase only in the EPA and Lecithin groups. In athletes neutrophils, the half-marathon decreased the expression of Fas and TRAIL receptors and of ICAM-1 and L-selectin adhesion molecules. On the other hand, it increased DNA fragmentation (only in the DHA group) and phosphatidylserine externalization (DHA, EPA and Lecithin groups). The half-marathon also increased concentrations of IL-8, IL-6 and IL-10 cytokines in all groups. The Supplementation (DHA or EPA or soy lecithin) decreased DNA fragmentation and Fas receptor expression in neutrophils. Moreover, increased expression of TRAIL, ICAM-1, L-selectin and phosphatidylserine externalization. In relation to cytokines plasma concentration the supplementation decreased TNF-alfa and increased the concentration of IL-10 in all groups. Whereas, IL-4 concentration increased only DHA and EPA groups. In conclusion, supplementation with soy lecithin has similar effects to the fish oils rich in EPA or DHA on leukocyte function amateur athletes.

A resistência das paredes celulares vegetais à hidrólise enzimática é um dos grandes gargalos tecnológicos para a obtenção do etanol celulósico. Acredita-se que as modificações nas paredes celulares em processos como a mobilização de reservas, formação de aerênquima, amadurecimento de frutos e senescência, por exemplo, envolvam a ativação de módulos funcionais que culminam em alterações nas paredes celulares. Estes módulos são: 1) recepção de um sinal para início do processo; 2) Morte Celular Programada (PCD); 3) separação celular; 4) expansão celular; 5) hidrólise de hemiceluloses e 6) hidrólise de celulose. No caso da formação de aerênquimas lisígenos o processo que se inicia com a PCD e é seguido pela liberação de glicosil hidrolases que atuam a na degradação e/ou modificação da parede celular, formando espaços de ar no córtex radicular. A formação de aerênquima nas raízes de cana de açúcar é constitutiva e pouco se sabe sobre os mecanismos de modificação que ocorrem na parede celular durante este processo. Este estudo buscou compreender os padrões de variação expressão gênica, proteínas e de atividades enzimáticas associados à formação do aerênquima em raízes de cana de açúcar, com ênfase no papel das hidrolases de parede celular e em algumas proteínas relacionadas à PCD. Foram utilizados 5 segmentos de raízes de 1 cm cada, a partir do ápice radicular. No material coletado observou-se a formação gradual de aerênquima. Foram realizadas análises transcricional, proteômica e atividade enzimática das glicosil hidrolases e outras proteínas que atuam na modificação da parede celular, os quais foram identificados e quantificados ao longo da formação do aerênquima. As glicosil hidrolases pertencentes às famílias Cazy GH1, GH3, GH17, GH18 bem como expansinas, celulose sintase, lacase, calreticulina, calmodulina e proteínas relacionadas a degradação de pectinas, foram encontradas ao longo dos segmentos, principalmente após o segmento 2. De acordo com a atividade transcricional e dados da proteômica, sugere-se que os polissacarídeos seriam atacados por enzimas nos estágios iniciais da formação do aerênquima (seg 2 e 3). O ataque ocorre principalmente sobre as pectinas e o &beta;-glucano. Contudo, os dados apontam para a deposição de xiloglucano, xilanos e celulose (após seg 3), que formam um compósito ao redor dos espaços de ar. Isto sugere que parte dos polissacarídeos das paredes não sejam degradados ao longo do processo, embora enzimas específicas detectadas possam atuar na modificação dos mesmos, como verificado para algumas pectinases e membros de GH17. Além disso, nos pré-tratamentos com água foi possível observar que há maior sacarificação da parede nos seg. 1 e 2. Contudo quando retira-se a maior parte das pectinas e hemiceluloses após pré-tratamento com NaOH, a sacarificação é maior nos segmentos 2, 3 e 4, devido ao maior acesso e a maior quantidade de celulose. As glicosil hidrolases encontradas neste trabalho sugerem que estas atacam a parede de um específico conjunto de células do córtex que dá origem ao aerênquima. Já no fim do processo, quando há lise celular, algumas paredes de células remanescentes são recalcitrante à hidrólise, provavelmente devido a sua arquitetura e composição. Este trabalho traz informações para o desenvolvimento de futuras tecnologias para a produção do etanol do etanol celulósico de cana-de-açúcar / The resistance of plant cell walls to enzymatic hydrolysis is one of the main bottlenecks of the development of technology of production of cellulosic ethanol. It is believed that the modifications in cell walls related to processes of storage mobilization, aerenchyma formation, fruit ripening and senescence, for instance, involve the activation of functional moduli that culminate in alterations of cell walls. These moduli are: 1) signal perception to start the process; 2) Programmed Cell Death (PCD); 3) cell separation; 4) cell expansion; 5) hydrolysis of hemicelluloses and 6) hydrolysis of cellulose. In the case of the formation of lysigenous aerenchyma, the process starts with PCD and is followed by the release of glycosil hydrolases that act on the degradation and/or cell wall modifications, forming air spaces in the cortex of the root. The formation of aerenchyma in the roots of sugarcane is a constitutive phenomenon and little is known about the mechanisms of modification that occur in cell walls during its development. Thus, the present study focused on the visualization of the patterns of variation of gene expression, proteins and enzyme activities associated to the formation of aerenchyma in roots of sugarcane in order to understand the role of the cell wall hydrolases and some proteins related to PCD in cell wall modifications along the process. Five root segments of 1cm each, starting from root apex, were used. A gradual centripetal formation of aerenchyma was recorded in the cortex of developing roots. Analyses of the transcriptional, proteomic and enzyme activity profiles during the process revealed that several enzymes act on cell wall modifications. The glycosil hydrolases belonging to the Cazy families GH1. GH3, GH17, GH18, as well as expansins, cellulose synthase, laccase, calreticulin, calmodulin and other proteins related to pectin degradation have been found along the segments, mainly after segment 2. According to the data on transcriptomics and proteomics, it is suggested that enzymes attack polysaccharides during the initial stages of aerenchyma formation (seg. 2 and 3). The attack of the enzymes occurs mainly on pectins and &beta;-glucan. Conversely, the data point out to the deposition (or maintenance) of xyloglucan, xylan and cellulose (after seg. 3), which form a composite that surrounds the air spaces. This suggests that part of the polysaccharides present in cell walls are not degraded during the process, although specific enzymes have been detected that could act on polysaccharide mobilization, such as the GH17 family. Further, under pretreatment with water, it has been observed that cell wall saccharification was higher at segments 1 and 2. On the other hand, when most of the pectins and hemicelluloses are retrieved by pretreatment with NaOH, saccharification is higher of segments 2, 3 and 4, probably due to the higher access to the wall and also to the higher proportion of cellulose. The profiles related to the glycosil hydrolases found in this work, suggest that these enzymes attack the cell wall. Initially, they are probably kept within a group of cells that will originate the aerenchyma. At the end of the process, when there is cell lysis, the remaining walls of some cells are recalcitrant to hydrolysis probably due to changes in their architecture and composition. Our findings bring promising information that could be used in the future to improve efficiency of hydrolysis for cellulosic ethanol production from sugarcane

京都大学 / 新制・論文博士 / 博士(医学) / 乙第13557号 / 論医博第2286号 / 新制||医||1067(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 生田 宏一, 教授 伊藤 能永, 教授 森信 暁雄 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

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