title: The RgpA-Kgp proteinase-adhesin complexes of Porphyromonas gingivalis Inactivate the Th2 cytokines interleukin-4 and interleukin-5.
abstract: The RgpA-Kgp proteinase-adhesin complexes are a primary virulence factor of Porphyromonas gingivalis, a major pathogen in the development of chronic periodontitis. The RgpA-Kgp complexes have been suggested to bias the immune response to a Th2 phenotype in disease by hydrolysis of Th1 cytokines. Here, we show that the RgpA-Kgp complexes hydrolyze and inactivate interleukin-4 (IL-4) and IL-5 under physiologically relevant conditions. Using the IL-4/IL-5-dependent TF1.8 T-cell line, it was found that at equimolar ratios of cytokine to RgpA-Kgp complexes, IL-4 and IL-5 were inactivated in the culture medium. The inactivation of IL-4 and IL-5 was RgpA-Kgp concentration dependent, as at an enzyme-to-cytokine molar ratio of 1:8, the bioactivity of the cytokines was greater than at the higher concentration of RgpA-Kgp of 1:1. Furthermore, inactivation of the cytokines by the RgpA-Kgp complexes was time dependent, as longer preincubation times resulted in lower cytokine activity. IL-5 was found to be slightly more resistant to inactivation than IL-4. Mass spectrometric analyses of IL-4 and IL-5 showed that hydrolysis by RgpA-Kgp complexes was C terminal to Arg and Lys residues of the cytokines. The peptides released indicated that the regions of IL-4 and IL-5 important for bioactivity were being hydrolyzed in the first 15 min of incubation. The ability of the RgpA-Kgp complexes to degrade Th2 cytokines may contribute to immune dysregulation and may play a role in the pathology of chronic periodontitis.
authors.affiliation: Cooperative Research Centre for Oral Health Science, Melbourne Dental School, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Australia.
authors.forename: Vivian
authors.initials: V
authors.lastname: Tam
authors.forename: Neil M
authors.initials: NM
authors.lastname: O'Brien-Simpson
authors.forename: Yu-Yen
authors.initials: YY
authors.lastname: Chen
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Sanderson
authors.forename: Beverley
authors.initials: B
authors.lastname: Kinnear
authors.forename: Eric C
authors.initials: EC
authors.lastname: Reynolds
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism*; D016866:Bacteroidaceae Infections / Q000276:immunology / Q000503:physiopathology; D002460:Cell Line; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D000080867:Gingipain Cysteine Endopeptidases; D006801:Humans; D015847:Interleukin-4 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015848:Interleukin-5 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013058:Mass Spectrometry; D010518:Periodontitis / Q000276:immunology / Q000503:physiopathology; D016966:Porphyromonas gingivalis / Q000201:enzymology / Q000472:pathogenicity*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013601:T-Lymphocytes; D018418:Th2 Cells / Q000276:immunology
chemical_list: D018829:Adhesins, Bacterial; D000080867:Gingipain Cysteine Endopeptidases; D015848:Interleukin-5; D011994:Recombinant Proteins; D015847:Interleukin-4; D003546:Cysteine Endopeptidases