Genetic Susceptibility and Caspase Activation in Mouse and Human Macrophages Are Distinct for
            <i>Legionella longbeachae</i>
            and
            <i>L. pneumophila</i>

Asare, Rexford; Šantić, Marina; Gobin, Ivana; Dorić, Miljenko; Suttles, Jill; Graham, James E.; Price, Christopher; Kwaik, Yousef Abu

doi:10.1128/iai.00025-07

Cited by 34 publications

(40 citation statements)

References 47 publications

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“…Heuner et al did not detect the flagellin-encoding flaA sequence in L. longbeachae serogroup 1 using Southern hybridization, nor did they visualize flagella on the surface by electron microscopy (42). On the It has been shown previously that L. pneumophila flagellin is required for caspase 1 activation in murine macrophages (53,62,70).The lack of a flagellum in D-4968 and other L. longbeachae isolates provides an explanation for the failure of this species to activate caspase 1 and trigger rapid pyroptosis in C57BL/6 and BALB/c mouse macrophages, allowing establishment of infection in mice resistant to L. pneumophila (6). The ability to replicate in various mouse strains and the fact that D-4968 was isolated from a Legionnaires' disease patient (4) indicate that the flagellum is not a factor that is required for L. longbeachae virulence.…”

Section: Resultsmentioning

confidence: 99%

“…These differences in murine host susceptibility are likely due to different abilities to activate caspase 1-mediated pyroptosis in macrophages. While L. pneumophila rapidly triggers pyroptosis in C57BL/6 mouse macrophages, L. longbeachae does not do this (6).…”

mentioning

confidence: 99%

“…L. longbeachae replicates in the lungs of A/J, C57BL/6, and BALB/c mice (6), whereas most inbred mice, including C57BL/6 and BALB strains, are resistant to L. pneumophila (61). These differences in murine host susceptibility are likely due to different abilities to activate caspase 1-mediated pyroptosis in macrophages.…”

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confidence: 99%

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Virulence Factors Encoded by Legionella longbeachae Identified on the Basis of the Genome Sequence Analysis of Clinical Isolate D-4968

et al. 2010

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Legionella longbeachae causes most cases of legionellosis in Australia and may be underreported worldwide due to the lack of L. longbeachae-specific diagnostic tests. L. longbeachae displays distinctive differences in intracellular trafficking, caspase 1 activation, and infection in mouse models compared to Legionella pneumophila, yet these two species have indistinguishable clinical presentations in humans. Unlike other legionellae, which inhabit freshwater systems, L. longbeachae is found predominantly in moist soil. In this study, we

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Section: Resultsmentioning

confidence: 99%

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Virulence Factors Encoded by Legionella longbeachae Identified on the Basis of the Genome Sequence Analysis of Clinical Isolate D-4968

et al. 2010

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“…Overall, extracellular and possibly intracellular recognition of L. pneumophila seems to be important for IL-6 expression in lung epithelium. Interestingly, Legionella longbeachae (the common cause of Legionellosis in Western Australia) which contains flagellin but no detectable poreforming activity, does not activate Naip5-related activity, thus implicating possible important strain-specific effects in Legionella-related cell activation [49].…”

Section: Discussionmentioning

confidence: 99%

Legionella pneumophila-induced IκBζ-dependent expression of interleukin-6 in lung epithelium

Lorenz

Zahlten²,

Pollok³

et al. 2010

Eur Respir J

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Severe community-and hospital-acquired pneumonia is caused by Legionella pneumophila. Lung airway and alveolar epithelial cells comprise an important sentinel system in airborne infections. Although interleukin (IL)-6 is known as a central regulator of the immune response in pneumonia, its regulation in the lung is widely unknown.Herein, we demonstrate that different L. pneumophila strains induce delayed expression of IL-6 in comparison with IL-8 by human lung epithelial cells. IL-6 expression depended, at early time points, on flagellin recognition by Toll-like receptor (TLR)5, activity of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK)1 and p38 mitogen-activated protein (MAP) kinase, and, at later time points, on the type-IV secretion system. In the same manner, but more rapidly, the recently described transcription factor IkBf was induced by Legionella infection and, binding to the nuclear factor (NF)-kB subunit p50 -recruited to the il6 promoter together with CCAAT-enhancer-binding protein b and phosphorylated activator protein-1 subunit cJun. Similarly, histone modifications and NF-kB subunit p65/RelA appeared at the ikbf and subsequently at the il6 gene promoter, thereby initiating gene expression. Gene silencing of IkBf reduced Legionella-related IL-6 expression by 41%.Overall, these data indicate a sequence of flagellin/TLR5-and type IV-dependent IkBf expression, recruitment of IkBf/p50 to the il6 promoter, chromatin remodelling and subsequent IL-6 transcription in L. pneumophila-infected lung epithelial cells.

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“…sainthelensi, and L. parisiensis, as well as three non-serogroup 1 strains of L. pneumophila (7,33,48). With the exception of L. longbeachae (6,7), the expression of flagellin and type IV secretion by these strains has not been reported.…”

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confidence: 99%

Mouse Macrophages Are Permissive to MotileLegionellaSpecies That Fail To Trigger Pyroptosis

Whitfield¹,

Byrne

Swanson

2010

Infect Immun

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Genetic Susceptibility and Caspase Activation in Mouse and Human Macrophages Are Distinct for Legionella longbeachae and L. pneumophila

Cited by 34 publications

References 47 publications

Virulence Factors Encoded by Legionella longbeachae Identified on the Basis of the Genome Sequence Analysis of Clinical Isolate D-4968

Virulence Factors Encoded by Legionella longbeachae Identified on the Basis of the Genome Sequence Analysis of Clinical Isolate D-4968

Legionella pneumophila-induced IκBζ-dependent expression of interleukin-6 in lung epithelium

Mouse Macrophages Are Permissive to MotileLegionellaSpecies That Fail To Trigger Pyroptosis

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