Cutting Edge: A Novel Nonoxidative Phagosomal Mechanism Exerted by Cathepsin-D Controls Listeria monocytogenes Intracellular Growth

Abstract

Deciphering how Listeria monocytogenes exploits the host cell machinery to invade mammalian cells is a key issue in understanding the pathogenesis of this food-borne pathogen, which can cause diseases ranging from gastroenteritis to meningitis and abortion. In this study, we show that the lysosomal aspartyl-protease cathepsin-D (Ctsd) is of considerable importance for nonoxidative listericidal defense mechanisms. We observed enhanced susceptibility to L. monocytogenes infection of fibroblasts and bone-marrow macrophages and increased intraphagosomal viability of bacteria in fibroblasts isolated from Ctsd-deficient mice compared with wild type. These findings are further supported by prolonged survival of L. monocytogenes in Ctsd-deficient mice after infection. Transient transfection of Ctsd in wild-type cells was sufficient to revert these wild-type phagosomes back to microbicidal compartments. Based on infection experiments with mutant bacteria, in vitro degradation, and immunoprecipitation experiments, we suggest that a major target of cathepsin D is the main virulence factor listeriolysin O.

Dietary Polyunsaturated Fatty Acids Increase Survival and Decrease Bacterial Load during Septic Staphylococcus aureus Infection and Improve Neutrophil Function in Mice

“…In the present study, mice fed HFD-P have higher levels of cathepsin D mRNA in bone marrow than mice fed HFD-S. Previous studies show that cathepsin D deficiency leads to impaired bacterial clearance (29,30). This is in line with our results where mice fed HFD-P have higher cathepsin D expression and decreased bacterial load.…”

The Pore-Forming Toxin Listeriolysin O Is Degraded by Neutrophil Metalloproteinase-8 and Fails To Mediate Listeria monocytogenes Intracellular Survival in Neutrophils

“…8), lysosomal cathepsin-D was reported to degrade LLO. L. monocytogenes intracellular survival was increased in cathepsin-D-deficient cells in vitro, and cathepsin-D-deficient mice were more susceptible to L. monocytogenes infection (82,83). Therefore, our data further support that enzymatic degradation of LLO is important for the antilisterial immune defense.…”

LIMP-2 Links Late Phagosomal Trafficking with the Onset of the Innate Immune Response to Listeria monocytogenes

“…, and Ctsd-deficient mice (Ctsd Ϫ/Ϫ ) (15). The animals were used in accordance with the regulations of the University of Kiel and the Hospital Universitario Marqués de Valdecilla Instituto de Formación e Investigación Marqués de Valdecilla animal use and welfare board.…”

“…The animals were used in accordance with the regulations of the University of Kiel and the Hospital Universitario Marqués de Valdecilla Instituto de Formación e Investigación Marqués de Valdecilla animal use and welfare board. BM-DM and mouse embryonic fibroblast culture conditions and requirements, as well as in vivo and in vitro infections and treatments, were described previously (15).…”

“…The first stage corresponds with LM internalization by the Tolllike receptor (TLR) recognition system and several scavenger receptors (4 -9). Next, the phagosomal stage promotes the degradation of LM via the action of oxidative pathways, such as phox and inducible NOS enzymatic complexes (10 -13), and nonoxidative microbicidal components, such as endosomal-lysosomal proteins (11,14,15). Lastly, a newly described cytosolic surveillance system mediated by NOD-like receptors senses degraded phagosomal bacteria (2,3) and induces the production of MØ-derived pro-inflammatory cytokines/chemokines MCP-1, TNF-␣, IL-6, and IL-12.…”