National Jewish Health

About: National Jewish Health is a healthcare organization based out in Denver, Colorado, United States. It is known for research contribution in the topics: T cell & Asthma. The organization has 883 authors who have published 833 publications receiving 79201 citations. The organization is also known as: National Jewish Medical and Research Center.

Immune protection and control of inflammatory tissue necrosis by gamma delta T cells.

Abstract: Host defenses against experimental listeriosis in mice involve neutrophils, macrophages, NK cells, and alpha beta T cells. Recently gamma delta T cells have also been implicated in antilisterial resistance. However, their specific role has remained unclear. Here we show that efficient resistance to infection by this bacterium depends on the functions of both alpha beta and gamma delta T cells in both primary and secondary responses. We also present evidence that these functions are complementary. In the livers of alpha beta T cell-depleted mice, bacteria grow to large numbers within hepatocytes but are infrequently found extracellularly. Granulomatous lesions are more frequent and somewhat larger than in normal controls, but remain focal. Neutrophils are absent from liver lesions in these mice. In contrast, the livers of gamma delta T cell-depleted mice contain many extracellular bacteria, but do not show hepatocytes containing large numbers of Listeria. Liver lesions in gamma delta T cell-depleted mice are far more extensive than in normal controls or in alpha beta T cell-depleted mice, and contain large numbers of neutrophils. Particularly in secondary listeriosis, gamma delta T cell-depleted mice show vast coalescent areas of necrotic liver parenchyma within 48 h after infection. Because the bacterial numbers in gamma delta T cell-depleted mice remain lower than in alpha beta T cell-depleted mice, increased mortality in the former may be in part caused by liver failure. We conclude that gamma delta T cells are required to control inflammatory reactivity and to prevent excessive liver damage during the immune response to Listeria monocytogenes.

Cre/loxP recombination system and gene targeting.

Abstract: Embryonic stem (ES) cell technology has clearly established itself as a powerful technique for the examination of gene function in vivo. The vast majority of gene-targeting experiments to date have been designed simply to inactivate the function of the gene of interest by the targeted insertion of a selectable marker into the ES genome. Homologous recombinant ES cells are used without further modification for the generation of mice that bear a permanently modified allele in all cells from the onset of development. In contrast to this “conventional” gene-targeting strategy, in recent years, the use of the Cre/loxP recombination system in conjunction with gene targeting has greatly expanded the versatility and avenues with which biologic questions can be addressed in the mouse. In addition to the generation of subtle mutations, this system allows for a number of other genotypic options in ES cells or mice by strategically incorporating Cre recombinase recognition (loxP) sites into the genome and the subsequent expression of recombinase in vitro or in vivo. In particular, when Cre is expressed in mice harboring a loxP-containing target gene, the desired gene modification can be restricted to certain cell types or developmental stages of the mouse (conditional gene targeting) depending on the tissue specificity and timing of recombinase expression. There is no definitive rule to decide whether, for a particular experiment, conventional or conditional gene targeting is more appropriate since this depends on the specific biologic question and the peculiarities of the gene studied.

Pulmonary Surfactant Protein A Modulates the Cellular Response to Smooth and Rough Lipopolysaccharides by Interaction with CD14

Abstract: Pulmonary surfactant protein A (SP-A) plays an important part in Ab-independent host defense mechanisms of the lung. In this study we investigated how SP-A interacts with distinct serotypes of bacterial LPS and modulates LPS-elicited cellular responses. SP-A bound to rough forms but not to smooth forms of LPS. In the macrophage-like cell line U937, SP-A inhibited mRNA expression and secretion of TNF-α induced by smooth LPS, but rough LPS-induced TNF-α expression was unaffected by SP-A. When U937 cells and rat alveolar macrophages were preincubated with SP-A, smooth LPS failed to induce TNF-α secretion, whereas rough LPS-induced TNF-α secretion was modestly increased. To clarify the mechanism by which SP-A modulates LPS-elicited cellular responses, we further examined the interaction of SP-A with CD14, which is known as a major LPS receptor. Western blot analysis revealed that CD14 was one of the SP-A binding proteins isolated from solubilized U937 cells. In addition, SP-A directly bound to recombinant soluble CD14 (rsCD14). When rsCD14 was preincubated with SP-A, the binding of rsCD14 to smooth LPS was significantly reduced but the association of rsCD14 with rough LPS was augmented. These results demonstrate the different actions of SP-A upon distinct serotypes of LPS and indicate that the direct interaction of SP-A with CD14 constitutes a likely mechanism by which SP-A modulates LPS-elicited cellular responses.