Dataset Information

TIR-Domain-Containing Adapter-Inducing Interferon-? (TRIF) Regulates CXCR5+ T helper Cells in the Intestine.

ABSTRACT: OBJECTIVE:Establishing an effective humoral immunity is an important host defense mechanism in intestinal mucosa. T follicular helper (Tfh) cells are a spectrum of CXCR5 expressing T helper cells that induce antigen-specific B cell differentiation. Because the differentiation of T helper cells is largely regulated by innate immunity, we addressed whether TRIF signaling regulates Tfh cell differentiation and its ability to trigger humoral immune responses in the intestine. METHOD:CD4+CXCR5+ T cells, B cells, and plasma cells in the Peyer's patches (PPs) of WT and TRIF-deficient (TrifLPS2) mice were analyzed by flow cytometry at the baseline, 9 days post primary infection, and 7 days post-secondary infection with Y. enterocolitica. Y. enterocolitica-specific CD4+CXCR5+ T cells were generated in vitro by co-culturing peritoneal macrophages with splenic naïve T cells in the presence of Y. enterocolitica lysate. WT and TrifLPS2 mice received CD4+CXCR5+ T cells isolated either from Y. enterocolitica-primed WT mice or generated in vitro. These mice were infected with Y. enterocolitica and followed up to 4 weeks. Y. enterocolitica-specific IgA and IgG were measured in stool and serum samples, respectively. RESULTS:At baseline, CD4+CXCR5+ T cell proportion was higher but the proportion of B cells and plasma cells was lower in the PPs of TrifLPS2 mice compared to WT mice. After infection, the proportion of plasma cells also became higher in the PPs of TrifLPS2 mice compared to WT mice. Corresponding increase of Y. enterocolitica-specific stool IgA but not serum IgG was found in TrifLPS2 mice compared to WT mice. Both in vivo isolated and in vitro generated CD4+CXCR5+ T cells induced protective immunity against Y. enterocolitica infection. CONCLUSION:Our results reveal a novel role of TRIF in the regulation of humoral immunity in the intestine that can be utilized as a basis for a unique vaccine strategy.

SUBMITTER: Kanagavelu S

PROVIDER: S-EPMC5108586 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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TIR-Domain-Containing Adapter-Inducing Interferon-<i>β</i> (TRIF) Regulates CXCR5+ T helper Cells in the Intestine.

Kanagavelu Saravana S Flores Claudia C Hagiwara Shinichiro S Ruiz Jose J Hyun Jinhee J Cho Ei E EE Sun Frank F Romero Laura L Shih David Q DQ Fukata Masayuki M

Journal of clinical & cellular immunology 20160930 5

<h4>Objective</h4>Establishing an effective humoral immunity is an important host defense mechanism in intestinal mucosa. T follicular helper (Tfh) cells are a spectrum of CXCR5 expressing T helper cells that induce antigen-specific B cell differentiation. Because the differentiation of T helper cells is largely regulated by innate immunity, we addressed whether TRIF signaling regulates Tfh cell differentiation and its ability to trigger humoral immune responses in the intestine.<h4>Method</h4>C ...[more]

PMID: 27853628

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Project description:BACKGROUND: TIR-domain-containing adapter-inducing interferon-? (TRIF) is the sole downstream adaptor of Toll-like receptor (TLR)3, which is one of the major signaling pathways in immune cells leading to neuroinflammation in the central nervous system. Overexpression of TRIF may lead to activation of inflammatory responses, and contribute to pathophysiological progression in both acute and chronic neurodegenerative retinal diseases. In the present study, was aimed to elucidate the contributions of TRIF to optic nerve (ON) regeneration and retinal ganglion cell (RGC) survival following injury to the ON, a widely studied model of central nervous system injury and of degenerative diseases such as glaucoma. METHODS: We used retrograde labeling with a fluorochrome, hydroxystilbamidine (Fluorogold) to evaluate RGC survival, and immunostaining with growth-associated protein-43 to evaluate axon regeneration in an ON crush model. Changes in microglial cytokines following RGC injury was examined with ELISA and real-time PCR. In vivo studies were carried out in wild-type and trif-/- mice. A Transwell co-culture system and migration test were used to mimic the crosstalk between microglia and RGCs. TRIF-associated downstream adaptors were determined by western blotting. RESULTS: Compared with wild-type (WT) mice, TRIF knockout (KO) mice displayed a robust ability to regenerate axons 3 or 7 days after nerve injury. In addition, RGC survival was considerably higher in trif-/- than in WT mice. ON lesion induced less microglial activation in trif-/- than in WT mice. and more WT microglia distorted and migrated toward the foramen opticum. In the transwell system, few trif-/- microglia migrated through the membrane when stimulated by the performed lesion on RGC axons in a transwell system. Inactivation of microglial cells in trif-/- mice was associated with reduced production of inflammatory cytokines, as detected with real-time RT-PCR and ELISA. Furthermore western blot analysis showed that activation of known downstream effectors of TRIF, including TBK1, IKK? and NF-?B, were significantly inhibited by TRIF deficiency. CONCLUSION: Our results indicate that TRIF deficiency promotes ON axon regeneration by attenuating microglial activation and consequently reducing the release of harmful cytokines via NF-?B inactivation.

Project description:BackgroundTRIF is a key protein in antiviral innate immunity, operating downstream of TLRs. TRIF activation leads to the production of interferon-β and pro-inflammatory cytokines. There is evidence from experiments to suggest that the N-terminal domain of TRIF binds to its TIR domain to avoid constitutive activation. However, no structure of a complex between the N-terminal domain and the TIR domain exists till date. The disordered nature of the region connecting the N-terminal domain and the TIR domain compounds the issue of elucidating the mechanism of autoinhibition of TRIF. In this study, we have employed an integrative approach consisting of mutual information analysis, docking, molecular dynamics simulations and residue network analysis, in combination with existing experimental data to provide a glimpse of TRIF in its autoinhibited state.ResultsOur extensive docking approach reveals that the N-terminal domain binds to the BB loop-B helix region of the TIR domain, consistent with experimental observations. Long length molecular dynamics simulations of 1 microsecond performed on the docked model highlights residues participating in hydrogen bonding and hydrophobic interactions at the interface. A pair of residues present in the vicinity of the interface is also predicted by mutual information analysis, to co-evolve. Residues mediating long-range interactions within the TIR domain of TRIF were identified using residue network analysis.ConclusionsBased on the results of the modelling and residue network analysis, we propose that the N-terminal domain binds to the BB loop region of the TIR domain, thereby preventing its homodimersation. The binding of TRIF to TLR3 or TRAM could induce a slight conformational change, causing the interactions between the N-terminal domain and TIR domain to disrupt, thereby exposing the BB loop and rendering it amenable for higher-order oligomerisation.ReviewersThis article was reviewed by Michael Gromiha, Srikrishna Subramaniam and Peter Bond (nominated by Chandra Verma).

Dataset Information

TIR-Domain-Containing Adapter-Inducing Interferon-? (TRIF) Regulates CXCR5+ T helper Cells in the Intestine.

Publications

TIR-Domain-Containing Adapter-Inducing Interferon-<i>β</i> (TRIF) Regulates CXCR5+ T helper Cells in the Intestine.

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