Lipopolysaccharide preparation extracted from Porphyromonas gingivalis lipoprotein-deficient mutant shows a marked decrease in toll-like receptor 2-mediated signaling.
We recently demonstrated that a new PG1828-encoded lipoprotein (PG1828LP) was able to be separated from a Porphyromonas gingivalis lipopolysaccharide (LPS) preparation, and we found that it exhibited strong cell activation, similar to that of Escherichia coli LPS, through a Toll-like receptor 2 (TLR2)-dependent pathway. In order to determine the virulence of PG1828LP toward cell activation, we generated a PG1828-deficient mutant of P. gingivalis strain 381 by allelic exchange mutagenesis using an ermF-ermAM antibiotic resistance cassette. A highly purified preparation of LPS from a PG1828-deficient mutant (DeltaPG1828-LPS) showed nearly the same ladder-like patterns in silver-stained gels as a preparation of LPS from a wild-type strain (WT-LPS), as well as Limulus amoebocyte lysate activities that were similar to those of the WT-LPS preparation. However, the ability of the DeltaPG1828-LPS preparation to activate NF-kappaB in TLR2-expressing cells was markedly attenuated. Cytokine production by human gingival fibroblasts was also decreased in response to the DeltaPG1828-LPS preparation in comparison with the WT-LPS preparation, and the activity was comparable to the stimulation of highly purified lipid A of P. gingivalis by TLR4. Further, lethal toxicity was rarely observed following intraperitoneal injection of the PG1828-deficient mutant into mice compared to that with the wild-type strain, while the DeltaPG1828-LPS preparation showed no lethal toxicity. Taken together, these results clearly indicate that PG1828LP plays an essential role in inflammatory responses and may be a major virulence factor of P. gingivalis.
Asai
Yasuyuki
Y
Department of Oral Microbiology, Asahi University School of Dentistry, 1851-1 Hozumi, Mizuho, Gifu 501-0296, Japan.
Hashimoto
Masahito
M
Fletcher
Hansel M
HM
Miyake
Kensuke
K
Akira
Shizuo
S
Ogawa
Tomohiko
T
D000818:Animals; D006801:Humans; D008070:Lipopolysaccharides / Q000633:toxicity*; D008074:Lipoproteins / Q000502:physiology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D016966:Porphyromonas gingivalis / Q000472:pathogenicity*; D011956:Receptors, Cell Surface / Q000502:physiology*; D015398:Signal Transduction; D051195:Toll-Like Receptor 2; D037521:Virulence Factors / Q000502:physiology
D008070:Lipopolysaccharides; D008074:Lipoproteins; D011956:Receptors, Cell Surface; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D037521:Virulence Factors