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TLR4 signaling via MyD88 and TRIF differentially shape the CD4+ T cell response to Porphyromonas gingivalis hemagglutinin B.

ABSTRACT: Recombinant hemagglutinin B (rHagB), a virulence factor of the periodontal pathogen Porphyromonas gingivalis, has been shown to induce protective immunity against bacterial infection. Furthermore, we have demonstrated that rHagB is a TLR4 agonist for dendritic cells. However, it is not known how rHagB dendritic cell stimulation affects the activation and differentiation of T cells. Therefore, we undertook the present study to examine the role of TLR4 signaling in shaping the CD4(+) T cell response following immunization of mice with rHagB. Immunization with this Ag resulted in the induction of specific CD4(+) T cells and Ab responses. In TLR4(-/-) and MyD88(-/-) but not Toll/IL-1R domain-containing adapter inducing IFN-?-deficient (TRIF(Lps2)) mice, there was an increase in the Th2 CD4(+) T cell subset, a decrease in the Th1 subset, and higher serum IgG(1)/IgG(2) levels of HagB-specific Abs compared with those in wild-type mice. These finding were accompanied by increased GATA-3 and Foxp3 expression and a decrease in the activation of CD4(+) T cells isolated from TLR4(-/-) and MyD88(-/-) mice. Interestingly, TLR4(-/-) CD4(+) T cells showed an increase in IL-2/STAT5 signaling. Whereas TRIF deficiency had minimal effects on the CD4(+) T cell response, it resulted in increased IFN-? and IL-17 production by memory CD4(+) T cells. To our knowledge, these results demonstrate for the first time that TLR4 signaling, via the downstream MyD88 and TRIF molecules, exerts a differential regulation on the CD4(+) T cell response to HagB Ag. The gained insight from the present work will aid in designing better therapeutic strategies against P. gingivalis infection.

SUBMITTER: Gaddis DE

PROVIDER: S-EPMC3809913 | biostudies-literature | 2011 May

REPOSITORIES: biostudies-literature

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TLR4 signaling via MyD88 and TRIF differentially shape the CD4+ T cell response to Porphyromonas gingivalis hemagglutinin B.

Gaddis Dalia E DE Michalek Suzanne M SM Katz Jannet J

Journal of immunology (Baltimore, Md. : 1950) 20110415 10

Recombinant hemagglutinin B (rHagB), a virulence factor of the periodontal pathogen Porphyromonas gingivalis, has been shown to induce protective immunity against bacterial infection. Furthermore, we have demonstrated that rHagB is a TLR4 agonist for dendritic cells. However, it is not known how rHagB dendritic cell stimulation affects the activation and differentiation of T cells. Therefore, we undertook the present study to examine the role of TLR4 signaling in shaping the CD4(+) T cell respon ...[more]

PMID: 21498664

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Project description:Periodontal disease is a highly complex chronic inflammatory disease of the oral cavity. Multiple factors influence periodontal disease, including socio-economic status, genetics and age; however, inflammation elicited by the presence of specific bacteria in the subgingival space is thought to drive the majority of soft- and hard-tissue destruction. Porphyromonas gingivalis is closely associated with periodontal disease. Toll-like receptors (TLRs) and their intracellular signaling pathways play roles in the host response to P. gingivalis. The focus of the current study was to use microarray analysis to define the contributions of the TLR adaptor molecules myeloid differentiation factor 88 (MyD88) and Toll/interleukin-1 receptor domain-containing adaptor inducing interferon-beta (TRIF), and aging, on the expression of TLR pathway-associated mRNAs in response to P. gingivalis.Bone marrow-derived macrophages (BMØ) from wild-type (Wt), MyD88 knockout (MyD88-KO) and Trif(Lps2) [i.e. containing a point mutation in the lipopolysaccharide 2 (Lps2) gene rendering the Toll/interleukin (IL)-1 receptor domain-containing adaptor inducing interferon-beta (TRIF) protein nonfunctional] mice, at 2-and 12-mo of age, were cultured with P. gingivalis. Expression of genes in BMØ cultured with P. gingivalis was determined in comparison with expression of genes in BMØ cultured in medium only.Using, as criteria, a twofold increase or decrease in mRNA expression, differential expression of 32 genes was observed when Wt BMØ from 2-mo-old mice were cultured with P. gingivalis compared with the medium-only control. When compared with 2-mo-old Wt mice, 21 and 12 genes were differentially expressed (p < 0.05) as a result of the mutations in MyD88 or TRIF, respectively. The expression of five genes was significantly (p < 0.05) reduced in Wt BMØ from 12-mo-old mice compared with those from 2-mo-old mice following culture with P. gingivalis. Age also influenced the expression of genes in MyD88-KO and Trif(Lps2) mice challenged with P. gingivalis.Our results indicate that P. gingivalis induces differential expression of TLR pathway-associated genes, and both MyD88 and TRIF play roles in the expression of these genes. Age also played a role in the expression of TLR-associated genes following stimulation of BMØ with P. gingivalis.

Project description:Binge/moderate alcohol suppresses TLR4-MyD88 proinflammatory cytokines; however, alcohol's effects on TLR-TRIF signaling, especially after in vivo exposure in humans, are unclear. We performed a comparative analysis of the TLR4-MyD88, TLR4-TRIF, and TLR3-TRIF pathways in human monocytes following binge alcohol exposure. Mechanistic regulation of TLR-TRIF signaling by binge alcohol was evaluated by analyzing IRF3 and TBK1, upstream regulator protein phosphatase 1 (PP1), and immunoregulatory stress proteins HspA1A and XBP-1 in alcohol-treated human and mouse monocytes/macrophages. Two approaches for alcohol exposure were used: in vivo exposure of primary monocytes in binge alcohol-consuming human volunteers or in vitro exposure of human monocytes/murine macrophages to physiological alcohol concentrations (25-50 mM ethanol), followed by LPS (TLR4) or polyinosinic-polycytidylic acid (TLR3) stimulation ex vivo. In vivo and in vitro binge alcohol exposure significantly inhibited the TLR4-MyD88 cytokines TNF-? and IL-6, as well as the TLR4-TRIF cytokines/chemokines IFN-?, IP-10, and RANTES, in human monocytes, but not TLR3-TRIF-induced cytokines/chemokines, as detected by quantitative PCR and ELISA. Mechanistic analyses revealed TBK-1-independent inhibition of the TLR4-TRIF effector IRF3 in alcohol-treated macrophages. Although stress protein XBP-1, which is known to regulate IRF3-mediated IFN-? induction, was not affected by alcohol, HspA1A was induced by in vivo alcohol in human monocytes. Alcohol-induced HspA1A was required for inhibition of TLR4-MyD88 signaling but not TLR4-TRIF cytokines in macrophages. In contrast, inhibition of PP1 prevented alcohol-mediated TLR4-TRIF tolerance in macrophages. Collectively, our results demonstrate that in vivo and in vitro binge alcohol exposure in humans suppresses TLR4-MyD88 and TLR4-TRIF, but not TLR3-TRIF, responses. Whereas alcohol-mediated effects on the PP1-IRF3 axis inhibit the TLR4-TRIF pathway, HspA1A selectively suppresses the TLR4-MyD88 pathway in monocytes/macrophages.

Project description:ObjectivePeriodontitis is a microbe-induced chronic inflammatory disease. Previous exposure of the host to bacteria or their virulence factors leads to refractory responses to further stimuli, which is called tolerance. Porphyromonas gingivalis (P. gingivalis) is one of the most important pathogenic microorganisms associated with periodontitis, and is a potent inducer of pro- and anti-inflammatory cytokines. The aim of this study was to explore the roles and possible mechanisms of tolerance induced by P. gingivalis.MethodsTHP-1-derived macrophages were pretreated with 1x108 colony-forming units/ml P. gingivalis ATCC 33277 or 21 clinical isolates from moderate to severe chronic periodontitis patients (24 h), washed (2 h) and treated with P. gingivalis ATCC 33277 or the same clinical isolates again (24 h). Levels of pro-inflammatory cytokines TNF-? and IL-1? and anti-inflammatory cytokine IL-10 in supernatants were detected by ELISA. Moreover, to identify the possible mechanisms for the changes in cytokine secretion, Toll-like receptor 2 (TLR2) and TLR4 protein expressions were explored in these cells by flow cytometry.ResultsAfter repeated challenge with P. gingivalis ATCC 33277 or clinical isolates, production of TNF-? and IL-1? in macrophages was decreased significantly compared with that following a single stimulation (p<0.05), while only comparable levels of IL-10 were detected in P. gingivalis ATCC 33277 or clinical isolate-tolerized cells (p>0.05). In addition, there was interstrain variability in the ability to induce IL-1? and IL-10 production after repeated P. gingivalis stimulation. However, no significant changes in TLR2 or TLR4 were detected in macrophages that were repeatedly treated with P. gingivalis ATCC 33277 or clinical isolates compared with those stimulated with P. gingivalis only once (p>0.05).ConclusionsRepeated P. gingivalis stimulation triggered tolerance, which might contribute to limiting periodontal inflammation. However, tolerance induced by P. gingivalis might develop independently of TLR2 and TLR4 and be related to molecules in signaling pathways downstream of TLR2 and TLR4.

Dataset Information

TLR4 signaling via MyD88 and TRIF differentially shape the CD4+ T cell response to Porphyromonas gingivalis hemagglutinin B.

Publications

TLR4 signaling via MyD88 and TRIF differentially shape the CD4+ T cell response to Porphyromonas gingivalis hemagglutinin B.

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