PrtT-Regulated Proteins Secreted by Aspergillus fumigatus Activate MAPK Signaling in Exposed A549 Lung Cells Leading to Necrotic Cell Death

Sharon, Haim; Amar, David; Levdansky, Emma; Mircus, Gabriel; Shadkchan, Yana; Shamir, Ron; Osherov, Nir

doi:10.1371/journal.pone.0017509

Cited by 33 publications

(51 citation statements)

References 54 publications

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“…A. fumigatus culture filtrates cause epithelial desquamation and destroy F-actin cytoskeletal fibres of in vitro -cultured pneumocytes [8] , [60] . Kogan et al , 2004 found deletion of the alp1 gene (AFUA_4G11800) encoding a secreted alkaline protease, or antipain treatment of wild-type culture supernatants to be equally ablative of secreted protease activity in vitro .…”

Section: Discussionmentioning

confidence: 99%

The pH-Responsive PacC Transcription Factor of Aspergillus fumigatus Governs Epithelial Entry and Tissue Invasion during Pulmonary Aspergillosis

et al. 2014

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Destruction of the pulmonary epithelium is a major feature of lung diseases caused by the mould pathogen Aspergillus fumigatus. Although it is widely postulated that tissue invasion is governed by fungal proteases, A. fumigatus mutants lacking individual or multiple enzymes remain fully invasive, suggesting a concomitant requirement for other pathogenic activities during host invasion. In this study we discovered, and exploited, a novel, tissue non-invasive, phenotype in A. fumigatus mutants lacking the pH-responsive transcription factor PacC. Our study revealed a novel mode of epithelial entry, occurring in a cell wall-dependent manner prior to protease production, and via the Dectin-1 β-glucan receptor. ΔpacC mutants are defective in both contact-mediated epithelial entry and protease expression, and significantly attenuated for pathogenicity in leukopenic mice. We combined murine infection modelling, in vivo transcriptomics, and in vitro infections of human alveolar epithelia, to delineate two major, and sequentially acting, PacC-dependent processes impacting epithelial integrity in vitro and tissue invasion in the whole animal. We demonstrate that A. fumigatus spores and germlings are internalised by epithelial cells in a contact-, actin-, cell wall- and Dectin-1 dependent manner and ΔpacC mutants, which aberrantly remodel the cell wall during germinative growth, are unable to gain entry into epithelial cells, both in vitro and in vivo. We further show that PacC acts as a global transcriptional regulator of secreted molecules during growth in the leukopenic mammalian lung, and profile the full cohort of secreted gene products expressed during invasive infection. Our study reveals a combinatorial mode of tissue entry dependent upon sequential, and mechanistically distinct, perturbations of the pulmonary epithelium and demonstrates, for the first time a protective role for Dectin-1 blockade in epithelial defences. Infecting ΔpacC mutants are hypersensitive to cell wall-active antifungal agents highlighting the value of PacC signalling as a target for antifungal therapy.

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Section: Discussionmentioning

confidence: 99%

The pH-Responsive PacC Transcription Factor of Aspergillus fumigatus Governs Epithelial Entry and Tissue Invasion during Pulmonary Aspergillosis

et al. 2014

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“…S2). The ERK inhibitor FR180204 attenuated ERK1/2 phosphorylation in human U138 glioblastoma cells and human A549 lung epithelial cells2425. The JNK inhibitor SP600125 inhibited the phosphorylation of JNK but not ERK1/2 in rat alveolar epithelial cells and lung tissue2627.…”

Section: Resultsmentioning

confidence: 99%

JNK activation is essential for activation of MEK/ERK signaling in IL-1β-induced COX-2 expression in synovial fibroblasts

Kitanaka

Nakano

Kitanaka

et al. 2017

Sci Rep

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The proinflammatory cytokine interleukin 1β (IL-1β) induces prostaglandin E2 (PGE2) production via upregulation of cyclooxygenase-2 (COX-2) expression in synovial fibroblasts. This effect of IL-1β is involved in osteoarthritis. We investigated MAPK signaling pathways in IL-1β-induced COX-2 expression in feline synovial fibroblasts. In the presence of MAPK inhibitors, IL-1β-induced COX-2 expression and PGE2 release were both attenuated. IL-1β induced the phosphorylation of p38, JNK, MEK, and ERK1/2. A JNK inhibitor prevented not only JNK phosphorylation but also MEK and ERK1/2 phosphorylation in IL-1β-stimulated cells, but MEK and ERK1/2 inhibitors had no effect on JNK phosphorylation. A p38 inhibitor prevented p38 phosphorylation, but had no effect on MEK, ERK1/2, and JNK phosphorylation. MEK, ERK1/2, and JNK inhibitors had no effect on p38 phosphorylation. We also observed that in IL-1β-treated cells, phosphorylated MEK, ERK1/2, and JNK were co-precipitated with anti-phospho-MEK, ERK1/2, and JNK antibodies. The silencing of JNK1 in siRNA-transfected fibroblasts prevented IL-1β to induce phosphorylation of MEK and ERK1/2 and COX-2 mRNA expression. These observations suggest that JNK1 phosphorylation is necessary for the activation of the MEK/ERK1/2 pathway and the subsequent COX-2 expression for PGE2 release, and p38 independently contributes to the IL-1β effect in synovial fibroblasts.

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“…Transcriptome and proteomic analyses have recently been used to identify novel responses and pathways activated in infected cells (Gomez et al, 2010; Oosthuizen et al, 2011; Sharon et al, 2011; Fekkar et al, 2012). A major advance towards a more credible in vitro model has been the development of a cellular bilayer system constructed with human alveolar epithelial cells and human pulmonary artery endothelial cells grown on either side of a semipermeable polyester membrane (Hope et al, 2007; Gregson et al, 2012).…”

Section: Experimental Systems Currently Used To Study the Interactionmentioning

confidence: 99%

Interaction of the pathogenic mold Aspergillus fumigatus with lung epithelial cells

Osherov

2012

Front. Microbio.

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Aspergillus fumigatus is an opportunistic environmental mold that can cause severe allergic responses in atopic individuals and poses a life-threatening risk for severely immunocompromised patients. Infection is caused by inhalation of fungal spores (conidia) into the lungs. The initial point of contact between the fungus and the host is a monolayer of lung epithelial cells. Understanding how these cells react to fungal contact is crucial to elucidating the pathobiology of Aspergillus-related disease states. The experimental systems, both in vitro and in vivo, used to study these interactions, are described. Distinction is made between bronchial and alveolar epithelial cells. The experimental findings suggest that lung epithelial cells are more than just “innocent bystanders” or a purely physical barrier against infection. They can be better described as an active extension of our innate immune system, operating as a surveillance mechanism that can specifically identify fungal spores and activate an offensive response to block infection. This response includes the internalization of adherent conidia and the release of cytokines, antimicrobial peptides, and reactive oxygen species. In the case of allergy, lung epithelial cells can dampen an over-reactive immune response by releasing anti-inflammatory compounds such as kinurenine. This review summarizes our current knowledge regarding the interaction of A. fumigatus with lung epithelial cells. A better understanding of the interactions between A. fumigatus and lung epithelial cells has therapeutic implications, as stimulation or inhibition of the epithelial response may alter disease outcome.

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PrtT-Regulated Proteins Secreted by Aspergillus fumigatus Activate MAPK Signaling in Exposed A549 Lung Cells Leading to Necrotic Cell Death

Cited by 33 publications

References 54 publications

The pH-Responsive PacC Transcription Factor of Aspergillus fumigatus Governs Epithelial Entry and Tissue Invasion during Pulmonary Aspergillosis

The pH-Responsive PacC Transcription Factor of Aspergillus fumigatus Governs Epithelial Entry and Tissue Invasion during Pulmonary Aspergillosis

JNK activation is essential for activation of MEK/ERK signaling in IL-1β-induced COX-2 expression in synovial fibroblasts

Interaction of the pathogenic mold Aspergillus fumigatus with lung epithelial cells

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