Open AccessMembrane Damage during Listeria monocytogenes Infection Triggers a Caspase-7 Dependent Cytoprotective Response
Author(s) -
Sara K. B. Cassidy,
Jon A. Hagar,
ThirumalaDevi Kanneganti,
Luigi Franchi,
Gabriel Núñez,
Mary O’Riordan
Publication year - 2012
Publication title -
plos pathogens
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.719
H-Index - 206
eISSN - 1553-7374
pISSN - 1553-7366
DOI - 10.1371/journal.ppat.1002628
Subject(s) - listeriolysin o , listeria monocytogenes , caspase 1 , caspase , pore forming toxin , biology , caspase 8 , microbiology and biotechnology , intracellular parasite , innate immune system , caspase 3 , intracellular , programmed cell death , apoptosis , immune system , toxin , listeria , immunology , bacteria , microbial toxins , biochemistry , genetics
The cysteine protease caspase-7 has an established role in the execution of apoptotic cell death, but recent findings also suggest involvement of caspase-7 during the host response to microbial infection. Caspase-7 can be cleaved by the inflammatory caspase, caspase-1, and has been implicated in processing and activation of microbial virulence factors. Thus, caspase-7 function during microbial infection may be complex, and its role in infection and immunity has yet to be fully elucidated. Here we demonstrate that caspase-7 is cleaved during cytosolic infection with the intracellular bacterial pathogen, Listeria monocytogenes . Cleavage of caspase-7 during L. monocytogenes infection did not require caspase-1 or key adaptors of the primary pathways of innate immune signaling in this infection, ASC, RIP2 and MyD88. Caspase-7 protected infected macrophages against plasma membrane damage attributable to the bacterial pore-forming toxin Listeriolysin O (LLO). LLO-mediated membrane damage could itself trigger caspase-7 cleavage, independently of infection or overt cell death. We also detected caspase-7 cleavage upon treatment with other bacterial pore-forming toxins, but not in response to detergents. Taken together, our results support a model where cleavage of caspase-7 is a consequence of toxin-mediated membrane damage, a common occurrence during infection. We propose that host activation of caspase-7 in response to pore formation represents an adaptive mechanism by which host cells can protect membrane integrity during infection.