Abstract
Cathepsin E, an intracellular aspartic proteinase, is predominantly localized in the endosomal compartments of immune system cells. In the present study, we investigated the role of cathepsin E in immune defense systems against bacterial infection. Cathepsin E-deficient (CatE-/-) mice showed dramatically increased susceptibility to infection with both the Gram-positive bacterium Staphyrococcus aureus, and the Gram-negative bacterium Porphyromonas gingivalis when compared with syngeneic wild-type mice, most likely due to impaired regulation of bacterial elimination. Peritoneal macrophages from CatE-/- mice showed significantly impaired tumor necrosis factor-α and IL-6 production in response to S. aureus and decreased bactericidal activities toward this bacterium. Moreover, the cell surface levels of Toll-like receptor-2 (TLR2) and TLR4, which recognize specific components of Gram-positive and -negative bacteria, respectively, were decreased in CatE -/- macrophages, despite no significant difference in the total cellular expression levels of these receptors between the wild-type and CatE-/- macrophages, implying trafficking defects in these surface receptors in the latter. These results indicate an essential role of cathepsin E in immune defense against invading microorganisms, most probably due to regulation of the cell surface expression of TLR family members required for innate immune responses.
Original language | English |
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Pages (from-to) | 57-66 |
Number of pages | 10 |
Journal | Journal of biochemistry |
Volume | 140 |
Issue number | 1 |
DOIs | |
Publication status | Published - Jul 2006 |
Externally published | Yes |
Keywords
- Aspartic proteinase
- Cathepsin E
- Knockout
- Macrophage
- Toll-like receptors
- Trafficking
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology