196,034 research outputs found
Role of nitric oxide and melanogenesis in the accomplishment of anticryptococcal activity by the BV-2 microglial cell line.
No full textJ Neuroimmunol. 1995 Apr;58(1):111-6.
Role of nitric oxide and melanogenesis in the accomplishment of anticryptococcal activity by the BV-2 microglial cell line.
Blasi E, Barluzzi R, Mazzolla R, Tancini B, Saleppico S, Puliti M, Pitzurra L, Bistoni F.
SourceDepartment of Biomedical Sciences, University of Modena, Italy.
Abstract
In the present paper, we investigated the involvement of cryptococcal melanogenesis and macrophage nitric oxide (NO) production in the accomplishment of anticryptococcal activity by microglial effector cells, using the murine cell line BV-2. We demonstrate that the constitutive levels of anticryptococcal activity exerted by BV-2 cells is significantly enhanced upon interferon gamma plus lipopolysaccharide treatment. The phenomenon, which occurs with no enhancement of phagocytic activity, is associated with the production of high levels of NO and is abolished by addition of NG-monomethyl-L-arginine. Comparable patterns of results are observed employing either unopsonized or opsonized microbial targets, the latter microorganisms being markedly more susceptible to BV-2 cell antimicrobial activity. Furthermore, melanization of Cryptococcus neoformans significantly reduces its susceptibility to BV-2 antimicrobial activity, regardless of the fact that activated macrophages or opsonized microorganisms have been employed. In conclusion, our results provide evidence that NO-dependent events are involved in the fulfillment of anticryptococcal activity by activated microglial cells and that fungal melanization is a precious escamotage through which C. neoformans overcomes host defenses.
PMID: 773044
Discussion of 'Simple method for confined-aquifer parameter estimation' by S.K. Singh
No full textLa discussion non ha abstrac
Influence of the Bcg locus on macrophage response to the dimorphic fungus Candida albicans
No full textThe Bcg/Tty/Lsh gene (candidate Nramp) controls natural resistance to several parasites, such as Mycobacterium bovis, Leishmania donovani, and Salmonella typhimurium. Using two macrophage (M phi) cell lines (B10R and B10S) derived from mouse strains congenic at Beg, we found that M phi s from resistant mice (B10R M phi s) act more effectively against the two morphogenetic forms of the dimorphic fungus Candida albicans compared with M phi s from susceptible mice (B10S M phi s). Moreover, when assessed for tumor necrosis factor secretion in response to the hyphal form of C. albicans, B10R M phi s are significantly more effective at expressing this secretory function than are B10S M phi s, closely resembling the trend of response to lipopolysaccharide. Overall, these results provide insight into the influence of the Beg locus on the M phi response to C. albicans
Immunology and pathogenesis of infections of the central nervous system(CNS)
No full textThe central nervous system (CNS) has long been regarded as an immunologically privileged site for the presence of blood-brain and blood- cerebrospinal fluid barriers. Nevertheless, experimental evidence indicates that, under physiological conditions, minimal amounts of blood-derived immune cells exist within the brain and cooperate with the resident immune elements, such as microglia and astrocyte, to the surveillance of the district. Following microbial invasion, both blood-derived and local effector systems synergize against the pathogen. The timing and entity of such reaction is crucial, allowing the clearance of the pathogen or rather contributing to the extent of sometimes irreversible brain tissue damage
Differential susceptibility of yeast and hyphal forms of Candida albicans to macrophage-derived nitrogen-containing compounds
No full textCandida albicans is a dimorphic Fungus capable of transition from the yeast form (Y-Candida) to the hyphal form (H-Candida). Both Y-Candida and H-Candida are known to be growth inhibited by murine macrophages (M phi) in vitro. In the present report, we demonstrate that M phi exposed to interferon gamma (IFN-gamma) plus lipopolysaccharide (LPS) show enhanced anti-Y-Candida and anti-H-Candida activities. To further investigate the phenomenon, Y-Candida and H-Candida were assessed for susceptibilities to M phi-derived supernatants. Only the growth of H-Candida, and not that of Y-Candida, is impaired by cell-free supernatants from M phi, treated with IFN-gamma plus LPS. In contrast, no H-Candida growth inhibition occurs when supernatants from M phi exposed to IFN-gamma plus LPS in the presence of N-G-monomethyl-L-arginine, an inhibitor of nitric oxide (NO) synthesis, are employed. Finally, supernatants from M phi incubated with sodium nitroprusside, an NO-generating agent, also show anti-H-Candida activity, In conclusion, these results indicate that H-Candida but not Y-Candida is susceptible to extracellular antifungal mechanisms employed by M phi, which likely involve stable nitrogen-containing compounds
Different events involved in the induction of macrophage tumor necrosis factor by Candida albicans and lipopolysaccharide.
No full textUsing an in vitro experimental model, we have recently demonstrated that Candida albicans in its hyphal form (H-Candida), similarly to lipopolysaccharide (LPS), enhances tumor necrosis factor (TNF) secretory response in the cloned macrophage (M phi) population ANA-1. Here we show that H-Candida and LPS each differ in their requirements for intact protein kinase functions, susceptibility to 0.4-microns micropore-size membranes, and sensitivity to polymyxin B. These results, together with the synergistic effect occurring between H-Candida and LPS in inducing TNF response, indicate the existence of different receptor(s) and/or signal-transduction pathway(s) through which the two stimuli act
La tossina tetanica previene l'aumento interferone-gamma mediato dei livelli di mRNA lisozima specifici in macrofagi GG2EE.
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