title: A polymer-type water-soluble peptidoglycan exhibited both Toll-like receptor 2- and NOD2-agonistic activities, resulting in synergistic activation of human monocytic cells.
abstract: Bacterial peptidoglycan (PGN) has been reported to be sensed by cell-surface Toll-like receptor (TLR)2. On the other hand, intracellular NOD-like receptors recognize PGN partial structures: NOD1 and NOD2 recognize the peptide moiety containing diaminopimelic acid, and the muramyldipeptide (MDP) moiety, respectively. In this study, we examined in human monocytic THP-1 cells the pro-inflammatory cytokine-inducing abilities of PGNs and their fragments enzymatically prepared from Staphylococcus epidermidis ATCC 155: a polymer-type water-soluble PGN possessing an intact glycan chain (SEPS) and a monomer-type PGN (SEPS-M). The water-soluble PGN polymer, SEPS, exhibited considerably stronger activities to induce pro-inflammatory cytokines than parent PGNs and the PGN monomer, SEPS-M. Short interference RNA targeting TLR2 and NOD2 markedly reduced the activities of SEPS. In the same experiments, the activities of PGNs were mainly reduced in TLR2-silenced cells, whereas the activities of SEPS-M as well as a synthetic MDP were markedly reduced in NOD2-silenced cells. Furthermore, the PGNs and a reference PGN from Staphylococcus aureus in combination with MDP synergistically induced interleukin-8 in THP-1 cells. These findings strongly suggested that a polymer-type water-soluble PGN fragment, SEPS, exhibits both TLR2-and NOD2-agonistic activities, which induced the synergistic activation of human monocytic cells.
authors.affiliation: Department of Microbiology and Immunology, Tohoku University School of Dentistry, Aoba-ku, Sendai, Japan.
authors.forename: Mizuho
authors.initials: M
authors.lastname: Natsuka
authors.forename: Akiko
authors.initials: A
authors.lastname: Uehara
authors.forename: Shuhua
authors.initials: S
authors.lastname: Yang
authors.forename: Seishi
authors.initials: S
authors.lastname: Echigo
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Takada
mesh_terms: D045744:Cell Line, Tumor; D016207:Cytokines / Q000096:biosynthesis; D006801:Humans; D008213:Lymphocyte Activation; D009000:Monocytes / Q000187:drug effects* / Q000276:immunology; D053473:Nod2 Signaling Adaptor Protein / Q000819:agonists* / Q000378:metabolism; D010457:Peptidoglycan / Q000737:chemistry / Q000276:immunology* / Q000302:isolation & purification; D013211:Staphylococcus aureus / Q000276:immunology; D013212:Staphylococcus epidermidis / Q000276:immunology; D051195:Toll-Like Receptor 2 / Q000819:agonists* / Q000378:metabolism
chemical_list: D016207:Cytokines; D053473:Nod2 Signaling Adaptor Protein; D010457:Peptidoglycan; D051195:Toll-Like Receptor 2