Open AccessChemically synthesized pathogen‐associated molecular patterns increase the expression of peptidoglycan recognition proteins via toll‐like receptors, NOD1 and NOD2 in human oral epithelial cells
Author(s) -
Uehara A.,
Sugawara Y.,
Kurata S.,
Fujimoto Y.,
Fukase K.,
Kusumoto S.,
Satta Y.,
Sasano T.,
Sugawara S.,
Takada H.
Publication year - 2005
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/j.1462-5822.2004.00500.x
Subject(s) - peptidoglycan , nod1 , pattern recognition receptor , biology , innate immune system , pathogen associated molecular pattern , nod2 , toll like receptor , microbiology and biotechnology , proinflammatory cytokine , lipopolysaccharide , receptor , flagellin , tlr4 , signal transduction , biochemistry , immunology , inflammation , gene
Summary Peptidoglycan recognition proteins (PGRPs), a novel family of pattern recognition molecules (PRMs) in innate immunity conserved from insects to mammals, recognize bacterial cell wall peptidoglycan (PGN) and are suggested to act as anti‐bacterial factors. In humans, four kinds of PGRPs (PGRP‐L, ‐Iα, ‐Iβ and ‐S) have been cloned and all four human PGRPs bind PGN. In this study, we examined the possible regulation of the expression of PGRPs in oral epithelial cells upon stimulation with chemically synthesized pathogen‐associated molecular patterns (PAMPs) in bacterial cell surface components: Escherichia coli ‐type tryacyl lipopeptide (Pam3CSSNA), E. coli ‐type lipid A (LA‐15‐PP), diaminopimelic acid containing desmuramyl peptide (γ‐ d ‐glutamyl‐ meso ‐DAP; iE‐DAP), and muramyldipeptide (MDP). These synthetic PAMPs markedly upregulated the mRNA expression of the four PGRPs and cell surface expression of PGRP‐Iα and ‐Iβ, but did not induce either mRNA expression or secretion of inflammatory cytokines, in oral epithelial cells. Suppression of the expression of Toll‐like receptor (TLR)2, TLR4, nucleotide‐binding oligomerization domain (NOD)1 and NOD2 by RNA interference specifically inhibited the upregulation of PGRP mRNA expression induced by Pam3CSSNA, LA‐15‐PP, iE‐DAP and MDP respectively. These PAMPs definitely activated nuclear factor (NF)‐κB in the epithelial cells, and suppression of NF‐κB activation clearly prevented the induction of PGRP mRNA expression induced by these PAMPs in the cells. These findings suggested that bacterial PAMPs induced the expression of PGRPs, but not proinflammatory cytokines, in oral epithelial cells, and the PGRPs might be involved in host defence against bacterial invasion without accompanying inflammatory responses.