title: MPYS/STING-mediated TNF-α, not type I IFN, is essential for the mucosal adjuvant activity of (3'-5')-cyclic-di-guanosine-monophosphate in vivo.
abstract: The bacterial second messenger (3'-5')-cyclic-di-guanosine-monophosphate (CDG) is a promising mucosal adjuvant candidate that activates balanced Th1/Th2/Th17 responses. We showed previously that CDG activates stimulator of IFN genes (STING)-dependent IFN-I production in vitro. However, it is unknown whether STING or IFN-I is required for the CDG adjuvant activity in vivo. In this study, we show that STING(-/-) mice (Tmem173(<tm1Camb>)) do not produce Ag-specific Abs or Th1/Th2/Th17 cytokines during CDG/Ag immunization. Intranasal administration of CDG did not induce TNF-α, IL-1β, IL-6, IL-12, or MCP-1 production in STING(-/-) mice. Surprisingly, we found that the cytokine and Ab responses were unaltered in CDG/Ag-immunized IFNAR(-/-) mice. Instead, we found that CDG activates STING-dependent, IFN-I-independent TNF-α production in vivo and in vitro. Furthermore, using a TNFR1(-/-) mouse, we demonstrate that TNF-α signaling is critical for CDG-induced Ag-specific Ab and Th1/Th2 cytokine production. This is distinct from STING-mediated DNA adjuvant activity, which requires IFN-I, but not TNF-α, production. Finally, we found that CDG activates STING-dependent, but IRF3 stimulation-independent, NF-κB signaling. Our results established an essential role for STING-mediated TNF-α production in the mucosal adjuvant activity of CDG in vivo and revealed a novel IFN-I stimulation-independent STING-NF-κB-TNF-α pathway.
authors.affiliation: Center for Immunology and Microbial Disease, Albany Medical College, Albany, NY 12208.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Blaauboer
authors.forename: Vincent D
authors.initials: VD
authors.lastname: Gabrielle
authors.forename: Lei
authors.initials: L
authors.lastname: Jin
mesh_terms: D000276:Adjuvants, Immunologic; D000818:Animals; D018925:Chemokines / Q000096:biosynthesis; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000276:immunology; D016207:Cytokines / Q000096:biosynthesis; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D005260:Female; D007074:Immunoglobulin G / Q000276:immunology; D050838:Interferon Regulatory Factor-3 / Q000378:metabolism; D007370:Interferon Type I / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D009092:Mucous Membrane / Q000276:immunology* / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D010047:Ovalbumin / Q000276:immunology; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D000099197:STING Protein
chemical_list: D000276:Adjuvants, Immunologic; D018925:Chemokines; D006152:Cyclic GMP; D016207:Cytokines; D007074:Immunoglobulin G; D050838:Interferon Regulatory Factor-3; D007370:Interferon Type I; D008565:Membrane Proteins; D016328:NF-kappa B; D010047:Ovalbumin; D014409:Tumor Necrosis Factor-alpha; C530855:Sting1 protein, mouse; D000099197:STING Protein; C062025:bis(3',5')-cyclic diguanylic acid