Infection of murine macrophage cell lines by Legionella pneumophila

Yan, Lei; Cirillo, Jeffrey D.

doi:10.1016/s0378-1097(03)00883-8

Cited by 15 publications

(11 citation statements)

References 24 publications

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“…3B). Among the strains evaluated by THP-1 cells, only L. pneumophila had the ability to proliferate in the presence of both murine and human macrophageike cells, which is consistent with findings of previous studies (Yan and Cirillo, 2004;Sahr et al, 2009).…”

supporting

confidence: 91%

“…Similarly, amoeba-grown L. pneumophila cells were at least 10-fold more invasive and displayed increased replication in human macrophage-like THP-1 cells compared to their agar grown counterparts (Cirillo et al, 1994). THP-1 cells and J774, a murine macrophage-like cell line, are commonly used as primary macrophage cell substitutes, with L. pneumophila replication in J774 cells shown to resemble those levels observed in human primary monocyte-derived macrophages (Yan and Cirillo, 2004). Both cells lines have been used to identify Legionella virulence genes by evaluating the gene mutants' invasiveness and replication further indicating their value as a model for Legionella virulence (Bandyopadhyay and Steinman, 2000;Naylor and Cianciotto, 2004;Ohnishi et al, 2004).…”

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confidence: 99%

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Screening-level assays for potentially human-infectious environmental Legionella spp.

et al. 2011

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In spite of the fact that various Legionella species are isolated from nonclinical water settings, there is no standard method to determine whether environmental legionellae may be infectious to humans. Here we provide a screening-level approach based on an in vivo murine (A/J mouse) model and three in vitro proliferation assays using Acanthamoeba polyphaga, and THP-1 human and J774 murine macrophage cell lines to identify potentially human-infectious legionellae. As an initial demonstration the infectivity potential of three clinical (Legionella pneumophila, L, longbeacheae, and L. micdadei) and three environmental (L. dumoffii, L. maceachernii, and L. sainthelensi) legionellae were evaluated. A/J mice were intranasally infected and by 6 h post infection (p.L), there were significant bacterial titers in the lungs. L. pneumophila, L. dumoffii, and L. micdadei densities were higher than L. longbeacheae, L. maceacherni, and L. sainthelensi at 24 h p.i. However, only L. pneumophila and L. micdadei persisted in the lungs after 48 h, indicating that the other isolates were rapidly cleared. Results from the in vitro assays showed that only L. pneumophila significantly multiplied within A. polyphaga, THP-1 and J774 cells after 72 h, but lysis of any of the in vitro hosts also flagged the strains for potential concern (e.g. L. dumoffii and L. micdadei). The results demonstrate the value of using multiple approaches to assess the potential level of pathogenicity of Legionella strains isolated from different environmental matrices.

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confidence: 91%

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confidence: 99%

Screening-level assays for potentially human-infectious environmental Legionella spp.

et al. 2011

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“…10-fold in their infection of U937 cells (96). To validate the results obtained from using U937 cells, we assessed the intracellular growth capacity of an lspF mutant in three more types of macrophages that are also known to support L. pneumophila intracellular growth; i.e., the MH-S mouse alveolar macrophage cell line (78,118), A/J mouse BMD macrophages (75), and explanted A/J mouse alveolar macrophages (36,46). In all cases, the T2S mutant had a reduced infectivity that was comparable to what has been observed with U937 cells; e.g., there was a 14-fold-reduced recovery of the mutant Fig.…”

Section: T2s Promotes L Pneumophila Infection Of Multiple Types Of Mmentioning

confidence: 99%

Legionella pneumophila Type II Secretion Dampens the Cytokine Response of Infected Macrophages and Epithelia

et al. 2011

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The type II secretion (T2S) system of Legionella pneumophila is required for the ability of the bacterium to grow within the lungs of A/J mice. By utilizing mutants lacking T2S (lsp), we now document that T2S promotes the intracellular infection of both multiple types of macrophages and lung epithelia. Following infection of macrophages, lsp mutants (but not a complemented mutant) elicited significantly higher levels of interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-␣), IL-10, IL-8, IL-1␤, and MCP-1 within tissue culture supernatants. A similar result was obtained with infected lung epithelial cell lines and the lungs of infected A/J mice. Infection with a mutant specifically lacking the T2S-dependent ProA protease (but not a complemented proA mutant) resulted in partial elevation of cytokine levels. These data demonstrate that the T2S system of L. pneumophila dampens the cytokine/chemokine output of infected host cells. Upon quantitative reverse transcription (RT)-PCR analysis of infected host cells, an lspF mutant, but not the proA mutant, produced significantly higher levels of cytokine transcripts, implying that some T2S-dependent effectors dampen signal transduction and transcription but that others, such as ProA, act at a posttranscriptional step in cytokine expression. In summary, the impact of T2S on lung infection is a combination of at least three factors: the promotion of growth in macrophages, the facilitation of growth in epithelia, and the dampening of the chemokine and cytokine output from infected host cells. To our knowledge, these data are the first to identify a link between a T2S system and the modulation of immune factors following intracellular infection.The aquatic bacterium Legionella pneumophila is the primary agent of Legionnaires' disease, a potentially fatal form of pneumonia (38). L. pneumophila is especially pathogenic for the immunocompromised, the elderly, and smokers. Recent studies highlight the significance of travel-associated Legionnaires' disease and an increasing incidence of legionellosis (79). In natural and man-made waters, Gram-negative L. pneumophila survives planktonically, in biofilms, and as an intracellular parasite of protozoa (115). Infection occurs after the inhalation of contaminated droplets that originate from a variety of aerosol-generating devices as well as potable waters (33, 86). In the lung, L. pneumophila multiplies in resident alveolar macrophages, although persistence might also involve growth in alveolar epithelia and extracellular survival (82). Much of the pathogenesis and ecology of L. pneumophila is mediated by secreted factors, including protein and nonprotein molecules (2,25,27,44,57). For secreting proteins into the extracellular milieu and/or target host cells, L. pneumophila uses both the type II secretion (T2S) and the type IV secretion (T4S) system, large membrane-spanning apparatuses that are each composed of at least 10 component proteins (27,82).T2S promotes the physiology and ecology of many bacteria as well as the virulence o...

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“…The host cells responsible for supporting human infection are alveolar macrophages. The MH-S mouse alveolar macrophage cell line has been demonstrated to be a competent model for Legionella infection of the lung (19,37). Infection assays were conducted by standard protocols.…”

Section: Fig 1 Growth Curves Of the Wild-type (ࡗ) Hfq Mutant (■) Andmentioning

confidence: 99%

The Hfq Homolog inLegionella pneumophilaDemonstrates Regulation by LetA and RpoS and Interacts with the Global Regulator CsrA

et al. 2005

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A gene in Legionella pneumophila that has significant homology to published hfq genes demonstrated regulation by RpoS and the transcriptional regulator LetA. Additionally, Hfq has a positive effect on the presence of transcripts of the genes for CsrA and the ferric uptake regulator Fur. Mutants lacking hfq demonstrate defects in growth and pigmentation and slight defects in virulence in both amoeba and macrophage infection models. Hfq appears to play a major role in exponential-phase regulatory cascades of L. pneumophila.

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Infection of murine macrophage cell lines by Legionella pneumophila

Cited by 15 publications

References 24 publications

Screening-level assays for potentially human-infectious environmental Legionella spp.

Screening-level assays for potentially human-infectious environmental Legionella spp.

Legionella pneumophila Type II Secretion Dampens the Cytokine Response of Infected Macrophages and Epithelia

The Hfq Homolog inLegionella pneumophilaDemonstrates Regulation by LetA and RpoS and Interacts with the Global Regulator CsrA

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