Pneumolysin induced mitochondrial dysfunction leads to release of mitochondrial DNA

Andreas Nerlich, Maren Mieth, Eleftheria Letsiou, Diana Fatykhova, Katja Zscheppang, Aki Imai-Matsushima, Thomas F Meyer, Lisa Paasch, Timothy J Mitchell, Mario Tönnies, Torsten T Bauer, Paul Schneider, Jens Neudecker, Jens C Rückert, Stephan Eggeling, Maria Schimek, Martin Witzenrath, Norbert Suttorp, Stefan Hippenstiel, Andreas C Hocke

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27 Citations (Scopus)
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Abstract

Streptococcus pneumoniae (S.pn.) is the most common bacterial pathogen causing community acquired pneumonia. The pore-forming toxin pneumolysin (PLY) is the major virulence factor of S.pn. and supposed to affect alveolar epithelial cells thereby activating the immune system by liberation of danger-associated molecular patterns (DAMP). To test this hypothesis, we established a novel live-cell imaging based assay to analyse mitochondrial function and associated release of mitochondrial DNA (mtDNA) as DAMP in real-time. We first revealed that bacterially released PLY caused significant changes of the cellular ATP homeostasis and led to morphologic alterations of mitochondria in human alveolar epithelial cells in vitro and, by use of spectral live-tissue imaging, in human alveoli. This was accompanied by strong mitochondrial calcium influx and loss of mitochondrial membrane potential resulting in opening of the mitochondrial permeability transition pore and mtDNA release without activation of intrinsic apoptosis. Moreover, our data indicate cellular mtDNA liberation via microvesicles, which may contribute to S.pn. related pro-inflammatory immune activation in the human alveolar compartment.

Original languageEnglish
Article number182
JournalScientific Reports
Volume8
Issue number1
DOIs
Publication statusPublished - 9 Jan 2018

Keywords

  • Cell death and immune response
  • Cellular microbiology
  • Infection

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