Nahed Ismail

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CD1d-restricted natural killer T (NKT) cells are innate-like lymphocytes that express a conserved T-cell receptor and contribute to host defence against various microbial pathogens. However, their target lipid antigens have remained elusive. Here we report evidence for microbial, antigen-specific activation of NKT cells against Gram-negative,(More)
Rickettsiae cause some of the most severe human infections, including epidemic typhus and Rocky Mountain spotted fever. Substantial progress has been made in research into the genomics, vector relationships, pathogenesis and immunity of these obligate, intracellular, arthropod-transmitted bacteria. This Review summarizes our understanding of the early and(More)
Human ehrlichiosis and anaplasmosis are acute febrile tick-borne diseases caused by various members of the genera Ehrlichia and Anaplasma (Anaplasmataceae). Human monocytotropic ehrlichiosis has become one of the most prevalent life-threatening tick-borne disease in the United States. Ehrlichiosis and anaplasmosis are becoming more frequently diagnosed as(More)
BACKGROUND The pathophysiologic mechanisms that determine the severity of Mediterranean spotted fever (MSF) and the host-related and microbe-related risk factors for a fatal outcome are incompletely understood. METHODS This prospective study used univariate and multivariate analyses to determine the risk factors for a fatal outcome for 140 patients with(More)
OBJECTIVE Infection triggers inflammation that, in turn, enhances the expression of contractile-associated factors in myometrium and increases the risk of preterm delivery. In this study, we assessed vitamin D regulation of inflammatory markers, contractile-associated factors, steroid hormone receptors, and NFκB pathway proteins in human uterine myometrial(More)
Spotted fever group rickettsioses are emerging and reemerging infectious diseases, some of which are life-threatening. In order to understand how dendritic cells (DCs) contribute to the host resistance or susceptibility to rickettsial diseases, we first characterized the in vitro interaction of rickettsiae with bone marrow-derived DCs (BMDCs) from resistant(More)
We investigated the mechanisms by which natural killer (NK) cells mediate innate host defense against infection with an endothelium-targeting intracellular bacterium, Rickettsia. We found that a robust Rickettsia-induced innate response in resistant mice cleared the bacteria early in the infection and was associated with significantly higher frequencies of(More)
Rickettsiae actively escape from vacuoles and replicate free in the cytoplasm of host cells, where inflammasomes survey the invading pathogens. In the present study, we investigated the interactions of Rickettsia australis with the inflammasome in both mouse and human macrophages. R. australis induced a significant level of IL-1β secretion by human(More)
Human monocytotropic ehrlichiosis (HME) is an emerging, life-threatening, infectious disease caused by Ehrlichia chaffeensis, an obligate intracellular bacterium that lacks cell wall LPS. We have previously developed an animal model of severe HME using a strain of Ehrlichia isolated from Ixodes ovatus ticks (IOE). To understand the basis of susceptibility(More)
BACKGROUND The mechanisms of immunity to Rickettsia conorii that have been elucidated in mouse models have not been evaluated in human tissues. METHODS In this study, quantitative real-time polymerase chain reaction was used to determine the levels of expression of inflammatory and immune mediators in skin-biopsy samples collected from 23 untreated(More)