title: In vivo and in vitro characterization of the immune stimulating activity of the Neisserial porin PorB.
abstract: Vaccines play a vital role in modern medicine. The development of novel vaccines for emerging and resistant pathogens has been aided in recent years by the use of novel adjuvants in subunit vaccines. A deeper understanding of the molecular pathways behind adjuvanticity is required to better select immunostimulatory molecules for use in individual vaccines. To this end, we have undertaken a study of the essential signaling pathways involved in the innate and adaptive immune responses to the Neisseria meningitidis outer membrane protein Porin B (PorB). We have previously demonstrated that PorB is an agonist of Toll-Like Receptor 2 (TLR2) and acts as an adjuvant in vaccines for protein, carbohydrate and lipopolysaccharide antigens using murine models. Here we demonstrate NFκB translocation following stimulation with PorB only occurs in the presence of TLR2. IL-6 and TNF-α secretion was shown to be MAPK dependent. Surface expression of activation markers on macrophages, including CD40, CD69, and CD86, was increased following PorB stimulation in vitro. Interestingly, some upregulation of CD54 and CD69 was still observed in macrophages obtained from TLR2 KO mice, indicating a possible non-TLR2 mediated activation pathway induced by PorB. In a murine vaccination model, using ovalbumin as the antigen and PorB as the adjuvant, a decreased antigen-specific IgG production was observed in TLR2 KO mice; adjuvant-dependent increased IgG production was entirely ablated in MyD88 KO mice. These observations demonstrate the importance of the above pathways to the adjuvant activity of PorB. The potential TLR2 independent effect is currently being explored.
authors.affiliation: Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: Andrew
authors.initials: A
authors.lastname: Platt
authors.affiliation: Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: Heather
authors.initials: H
authors.lastname: MacLeod
authors.affiliation: Section of Infectious Diseases, Department of Medicine, Boston Medical Center, Boston, Massachusetts, United States of America.
authors.forename: Paola
authors.initials: P
authors.lastname: Massari
authors.affiliation: Section of Infectious Diseases, Department of Medicine, Boston Medical Center, Boston, Massachusetts, United States of America.
authors.forename: Xiuping
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America ; Section of Infectious Diseases, Department of Medicine, Boston Medical Center, Boston, Massachusetts, United States of America.
authors.forename: Lee
authors.initials: L
authors.lastname: Wetzler
mesh_terms: D056704:Adaptive Immunity / Q000187:drug effects; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D005260:Female; D007109:Immunity / Q000187:drug effects*; D007074:Immunoglobulin G / Q000378:metabolism; D058847:Inflammasomes / Q000378:metabolism; D018836:Inflammation Mediators / Q000378:metabolism; D053583:Interleukin-1beta / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology; D051379:Mice; D008810:Mice, Inbred C57BL; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D018272:Porins / Q000494:pharmacology*; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D016207:Cytokines; D007074:Immunoglobulin G; D058847:Inflammasomes; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D053594:Myeloid Differentiation Factor 88; D018272:Porins; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; C057699:porin protein, Neisseria; D000255:Adenosine Triphosphate; D020928:Mitogen-Activated Protein Kinases