title: Assessment of outer membrane vesicles of periodontopathic bacterium Porphyromonas gingivalis as possible mucosal immunogen.
abstract: Periodontitis is the most prevalent infectious disease and related to oral and systemic health, therefore novel prophylaxis to prevent the disease is highly desirable. Here, we assessed the outer membrane vesicles (OMVs) of a keystone periodontal pathogen, Porphyromonas gingivalis, as a candidate mucosal immunogen and adjuvant for a periodontitis vaccine. The structural and functional stability of OMVs, demonstrated by proteinase K resistance and ability to withstand long-term storage, are considered advantageous for carrying the OMV components into the host immune system. Intranasal vaccination of OMVs in mice elicited production of P. gingivalis-specific antibodies in blood and saliva by OMVs in a dose-dependent manner, which was dramatically enhanced by addition of a TLR3 agonist, Poly(I:C). Serum samples from mice immunized with OMVs plus Poly(I:C) adjuvant [OMV+Poly(I:C)] showed significant inhibition of gingipain proteolytic activity of not only the vaccine strain, but also heterologous strains. The viability of P. gingivalis was also decreased by preincubation with OMV+Poly(I:C)-immunized sera, while the killing effect was partially blocked by heat-inactivation of the sera. Saliva samples from mice immunized with OMV+Poly(I:C) enhanced bacterial agglutination of both the vaccine and heterologous strains. In an oral infection mouse model, the numbers of P. gingivalis in the oral cavity were significantly decreased in mice intranasally immunized with OMV+Poly(I:C) as compared to mock (only Poly[I:C])-immunized mice. The high levels of serum IgG (including IgG1 and IgG2a) and salivary S-IgA were elicited in mice intranasally immunized with OMV+Poly(I:C), which were maintained for at least 28 and 18weeks, respectively, after immunization. An experiment examining the accumulation of OMVs after intranasal immunization in proximal organs and an intracerebral injection experiment confirmed the safety of OMVs. Based on our results, we propose that intranasal immunization with OMV+Poly(I:C) is a feasible vaccine strategy in the context of bacterial clearance and safety.
authors.affiliation: Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo 162-8640, Japan. Electronic address: ryoma73@nih.go.jp.
authors.forename: Ryoma
authors.initials: R
authors.lastname: Nakao
authors.affiliation: Department of Pathology, National Institute of Infectious Diseases, Tokyo 162-8640, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Hasegawa
authors.affiliation: Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo 162-8640, Japan.
authors.forename: Bai
authors.initials: B
authors.lastname: Dongying
authors.affiliation: Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo 162-8640, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Ohnishi
authors.affiliation: Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo 162-8640, Japan.
authors.forename: Hidenobu
authors.initials: H
authors.lastname: Senpuku
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000281:Administration, Intranasal; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology; D001428:Bacterial Vaccines / Q000276:immunology*; D055252:Cell-Derived Microparticles / Q000276:immunology*; D005260:Female; D018928:Immunity, Mucosal; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D009092:Mucous Membrane / Q000276:immunology; D010518:Periodontitis / Q000517:prevention & control*; D011070:Poly I-C; D011119:Polynucleotides / Q000008:administration & dosage; D016966:Porphyromonas gingivalis / Q000276:immunology*; D012463:Saliva / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D007074:Immunoglobulin G; D011119:Polynucleotides; D011070:Poly I-C
keywords: Intranasal immunization; Outer membrane vesicles; Periodontal disease; Poly(I:C); Porphyromonas gingivalis