Naip5 Affects Host Susceptibility to the Intracellular Pathogen Legionella pneumophila

Wright, Edward K.; Goodart, Sheryl A.; Growney, Joseph D.; Hadinoto, Vey; Endrizzi, Matthew G.; Long, Elizabeth M.; Sadigh, Keyvan; Abney, Andrew L.; Bernstein-Hanley, Isaac; Dietrich, William F.

doi:10.1016/s0960-9822(02)01359-3

Cited by 241 publications

(216 citation statements)

References 44 publications

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“…Intracellular growth was quantified by plating appropriately diluted (Yamamoto et al, 1988). However, bone-marrow-derived macrophages from BALB/c mice permit the intracellular replication of L. pneumophila (Wright et al, 2003), which corresponds to the observed permissiveness of RAW264.7 macrophages.…”

Section: Methodsmentioning

confidence: 82%

The amoebae plate test implicates a paralogue of lpxB in the interaction of Legionella pneumophila with Acanthamoeba castellanii

et al. 2005

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Legionella pneumophila is a bacterial parasite of freshwater amoebae which also grows in alveolar macrophages and thus causes the potentially fatal pneumonia Legionnaires' disease. Intracellular growth within amoebae and macrophages is mechanistically similar and requires the Icm/Dot type IV secretion system. This paper reports the development of an assay, the amoebae plate test (APT), to analyse growth of L. pneumophila wild-type and icm/dot mutant strains spotted on agar plates in the presence of Acanthamoeba castellanii. In the APT, wild-type L. pneumophila formed robust colonies even at high dilutions, icmT, -R, -P or dotB mutants failed to grow, and icmS or -G mutants were partially growth defective. The icmS or icmG mutant strains were used to screen an L. pneumophila chromosomal library for genes that suppress the growth defect in the presence of the amoebae. An icmS suppressor plasmid was isolated that harboured the icmS and flanking icm genes, indicating that this plasmid complements the intracellular growth defect of the mutant. In contrast, different icmG suppressor plasmids rendered the icmG mutant more cytotoxic for A. castellanii without enhancing intracellular multiplication in amoebae or RAW264.7 macrophages. Deletion of individual genes in the suppressor plasmids inserts identified lcs (Legionella cytotoxic suppressor) -A, -B, -C and -D as being required for enhanced cytotoxicity of an icmG mutant strain. The corresponding proteins show sequence similarity to hydrolases, NlpD-related metalloproteases, lipid A disaccharide synthases and ABC transporters, respectively. Overexpression of LcsC, a putative paralogue of the lipid A disaccharide synthase LpxB, increased cytotoxicity of an icmG mutant but not that of other icm/dot or rpoS mutant strains against A. castellanii. Based on sequence comparison and chromosomal location, lcsB and lcsC probably encode enzymes involved in cell wall maintenance and peptidoglycan metabolism. The APT established here may prove useful to identify other bacterial factors relevant for interactions with amoeba hosts.

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Section: Methodsmentioning

confidence: 82%

The amoebae plate test implicates a paralogue of lpxB in the interaction of Legionella pneumophila with Acanthamoeba castellanii

et al. 2005

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“…The possibility of a cooperative interaction between Ipaf and Naip5 has been investigated thoroughly in L. pneumophila infections, which we have recently reviewed in detail (4). Briefly, several lines of indirect evidence have suggested that Ipaf and Naip5 act in concert: (i) Ipaf and Naip5 coimmunoprecipitate in overexpression assays (9,11), (ii) both Ipaf and Naip5 are L. pneumophila susceptibility genes in vitro in macrophages and in vivo in mice (6,7,9,13), and (iii) both Ipaf and Naip5 modulate caspase 1 activity (5,9). Other data indicate that Naip5-deficient macrophages retain their ability to activate caspase 1 and IL-1␤ secretion in response to L. pneumophila (8,10,12).…”

Section: Discussionmentioning

confidence: 99%

“…Nalp3 activates caspase 1 via a pyrin domain, but does so by using the adaptor protein ASC to recruit caspase 1 (3). The NLR Naip5 was identified as the Legionella pneumophila susceptibility locus in A/J mice (6,7). Because Ipaf also provides resistance to L. pneumophila infection and Ipaf and Naip5 have been shown to interact with each other in overexpression assays, it has been suggested that the two work in concert to activate caspase 1 (8)(9)(10)(11).…”

mentioning

confidence: 99%

Pseudomonas aeruginosa activates caspase 1 through Ipaf

Miao

Ernst

Dors

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

274

253

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The innate immune system encodes cytosolic Nod-like receptors (NLRs), several of which activate caspase 1 processing and IL-1␤ and IL-18 secretion. Macrophages respond to Salmonella typhimurium infection by activating caspase 1 through the NLR Ipaf. This activation is mediated by cytosolic flagellin through the activity of the virulence-associated type III secretion system (T3SS). We demonstrate here that Pseudomonas aeruginosa activates caspase 1 and induces IL-1␤ secretion in infected macrophages. While live, virulent P. aeruginosa activate IL-1␤ secretion through caspase 1 and Ipaf, strains that have mutations in the T3SS or in flagellin did not. Ipaf-dependent caspase 1 activation could be recapitulated by delivering P. aeruginosa flagellin to the macrophage cytosol. We examined the role of Naip5 in P. aeruginosa-induced caspase 1 activation by using A/J (Naip5-deficient) compared with C57BL/6 and BALB/c (Naip5-sufficient) macrophages and observed that A/J macrophages secrete IL-1␤ in response to P. aeruginosa, S. typhimurium, and Listeria monocytogenes infection, as well as in response to cytosolic flagellin, but at slightly reduced levels. Thus, Ipaf-dependent detection of cytosolic flagellin is a conserved mechanism by which macrophages detect the presence of pathogens that use T3SS.flagellin ͉ inflammation ͉ type III secretion ͉ macrophage

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“…19 NAIP was the first mammalian IAP to be discovered, but rather than having a role in regulation of cell death, it is a 44,45 that appears to function in providing innate immunity to infection by bacteria such as Leigonella pneumophila. 46,47 Although some initial reports suggested it might be able to inhibit caspases in vitro, subsequent studies have shown NAIP cannot directly inhibit caspases at physiological concentrations. 29 Similarly, although Survivin, an IAP that acts together with aurora kinase B and the inner centromere protein during mitosis, was initially proposed to inhibit caspases, 48 it is no longer thought to be able to do so.…”

Section: Iapsmentioning

confidence: 99%