Cathepsin E-deficient mice show increased susceptibility to bacterial infection associated with the decreased expression of multiple cell surface Toll-like receptors

Takayuki Tsukuba, Shinya Yamamoto, Michiyo Yanagawa, Kuniaki Okamoto, Yoshiko Okamoto, Keiichi I. Nakayama, Tomoko Kadowaki, Kenji Yamamoto

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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 languageEnglish
Pages (from-to)57-66
Number of pages10
JournalJournal of biochemistry
Volume140
Issue number1
DOIs
Publication statusPublished - Jul 1 2006

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All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology

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