95 research outputs found
Aspergillus fumigatus Stimulates the NLRP3 Inflammasome through a Pathway Requiring ROS Production and the Syk Tyrosine Kinase
Invasive aspergillosis (IA) is a life-threatening disease that occurs in immunodepressed patients when infected with Aspergillus fumigatus. This fungus is the second most-common causative agent of fungal disease after Candida albicans. Nevertheless, much remains to be learned about the mechanisms by which A. fulmigatus activates the innate immune system. We investigated the inflammatory response to conidia and hyphae of A. fumigatus and specifically, their capacity to trigger activation of an inflammasome. Our results show that in contrast to conidia, hyphal fragments induce NLRP3 inflammasome assembly, caspase-1 activation and IL-1β release from a human monocyte cell line. The ability of Aspergillus hyphae to activate the NLRP3 inflammasome in the monocytes requires K+ efflux and ROS production. In addition, our data show that NLRP3 inflammasome activation as well as pro-IL-1β expression relies on the Syk tyrosine kinase, which is downstream from the pathogen recognition receptor Dectin-1, reinforcing the importance of Dectin-1 in the innate immune response against fungal infection. Furthermore, we show that treatment of monocytes with corticosteroids inhibits transcription of the gene encoding IL-1β. Thus, our data demonstrate that the innate immune response against A. fumigatus infection involves a two step activation process, with a first signal promoting expression and synthesis of pro-IL-1β; and a second signal, involving Syk-induced activation of the NLRP3 inflammasome and caspase-1, allowing processing and secretion of the mature cytokine
Biological Function and Molecular Mapping of M Antigen in Yeast Phase of Histoplasma capsulatum
Histoplasmosis, due to the intracellular fungus Histoplasma capsulatum, can be diagnosed by demonstrating the presence of antibodies specific to the immunodominant M antigen. However, the role of this protein in the pathogenesis of histoplasmosis has not been elucidated. We sought to structurally and immunologically characterize the protein, determine yeast cell surface expression, and confirm catalase activity. A 3D-rendering of the M antigen by homology modeling revealed that the structures and domains closely resemble characterized fungal catalases. We generated monoclonal antibodies (mAbs) to the protein and determined that the M antigen is present on the yeast cell surface and in cell wall/cell membrane preparations. Similarly, we found that the majority of catalase activity was in extracts containing fungal surface antigens and that the M antigen is not significantly secreted by live yeast cells. The mAbs also identified unique epitopes on the M antigen. The localization of the M antigen to the cell surface of H. capsulatum yeast and the characterization of the protein's major epitopes have important implications since it demonstrates that although the protein may participate in protecting the fungus against oxidative stress it is also accessible to host immune cells and antibody
Splenectomy for splenomegaly and secondary hypersplenism
Splenomegaly and secondary hypersplenism may be associated with acute and chronic infections, autoimmune states, portal hypertension or splenic vein thrombosis, and a number of infiltrative and neoplastic conditions involving the spleen. Our experience and that of others with these various conditions demonstrates that the decision to perform splenectomy should be based on well-defined and often strictly limited indications. Except for idiopathic splenomegaly, the presence and severity of secondary hypersplenism or severely symptomatic splenomegaly should be well documented. In each case, the potential for palliation and known mean duration of expected response must be weighed against the increased morbidity and mortality of splenectomy (as compared to operation for “primary” hypersplenism) . La splĂ©nomĂ©galie avec hypersplĂ©nisme secondaire relève de multiples causes: infection aigue ou chronique, Ă©tats autoimmunologiques, hypertension portale, thrombose de la veine splĂ©nique, lĂ©sions tumorales splĂ©niques. L'expĂ©rience de l'auteur qui rejoint celle de nombreux collègues lui permet d'affirmer que les indications de la splĂ©nectomie doivent ĂŞtre bien dĂ©finies et sont strictement limitĂ©es. A l'exception de la splĂ©nomĂ©galie idiopathique, l'existence et l'intensitĂ© de l'hypersplĂ©nisme, l'importance des symptomes provoquĂ©s par la splĂ©nomĂ©galie doivent ĂŞtre aprrĂ©ciĂ©es avec prĂ©cision. Dans chaque cas le potentiel de la rĂ©mission de l'affection et la durĂ©e de la rĂ©mission doivent ĂŞtre pris en considĂ©ration en fonction de l'Ă©ventuelle morbiditĂ© et de l'Ă©ventuelle mortalitĂ© de la splĂ©nectomie (par comparaison avec la splĂ©nectomie pour hypersplĂ©nisme primaire). Eplenomegalia e hiperesplenismo secundario pueden estar asociados con infecciones agudas y crĂłnicas, estados autoinmunes (sĂndrome de Felty, lupus eritematoso sistĂ©mico), “esplenomegalia congestiva” por hipertensiĂłn portal o trombosis de la vena esplĂ©nica y con una variedad de entidades de tipo infiltrativo y neoplásico que afectan al bazo (sarcoidosis, enfermedad de Gaucher, varios desĂłrdenes mieloproliferativos y linfomas). Nuestra experiencia, y aquella de otros autores, con tales condiciones demuestra que la decisiĂłn de realizar esplenectomĂa debe estar fundamentada en indicaciones bien definidas y estrictamente limitadas. Excepto en casos de esplenomegalia idiopática, la presencia y severidad del hiperesplenismo secundario o de esplenomegalia severamente sintomática debe ser bien documentada. En cada caso debe determinarse el potencial de paliaciĂłn y la duraciĂłn de la respuesta que se espera obtener frente a la incrementada morbilidad y mortalidad de la esplenectomĂa (en comparaciĂłn con la operaciĂłn que se realiza por hiperesplenismo “primario”).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41318/1/268_2005_Article_BF01655279.pd
The Impact of State Abortion Policies on Teen Pregnancy Rates
Restrictive abortion policies, Teen pregnancy rates,
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