Aggregatibacter actinomycetemcomitans Outer Membrane Proteins 29 and 29 Paralogue Induce Evasion of Immune Response.

Maike Paulino Da Silva,Maike Paulino Da Silva,Dione Kawamoto,Silvana Pasetto,Silvana Pasetto,Ramiro Mendonça Murata,Viviam De Oliveira Silva,Casey Chen,Ellen Sayuri Ando-Suguimoto,Gardênia Márcia Silva Campos Mata,Gardênia Márcia Silva Campos Mata,Marcia Pinto Alves Mayer

doi:10.3389/froh.2022.835902

Abstract

Aggregatibacter actinomycetemcomitans (Aa) is abundant within the microbial dysbiotic community of some patients with periodontitis. Aa outer membrane protein 29 (OMP29), a member of the OMPA family, mediates the invasion of Aa to gingival epithelial cells (GECs). This study evaluated the effect of OMP29 and its paralogue OMP29par on the response of GECs to Aa. The omp29 or/and omp29par deletion mutants AaΔ29, AaΔ29P, and AaΔ29Δ29P were constructed, and recombinant Aa OMP29His was obtained. Microarray analysis and the evaluation of cxcl-8 gene expression were performed to examine the response of GECs line OBA-09 to Aa and its mutants. The expression of cxcl-8 and its product CXCL-8 was examined in LPS-stimulated OBA-09 cells with Aa OMP29His. Proteomics analysis showed that the deletion of omp29 led to overexpression of both OMP29par and another membrane protein OMP39, the expression of which was further increased in AaΔ29Δ29P. OBA-09 cells challenged with AaΔ29Δ29P exhibited a higher expression of cxcl-8 in comparison to wildtype Aa strain AaD7S or single-deletion mutants AaΔ29 or AaΔ29P. LPS-stimulated OBA-09 cells challenged with Aa OMP29His showed reduced expressions of cxcl-8 and its product CXCL-8. OBA-09 cells challenged with AaΔ29Δ29P in comparison to Aa strain AaD7S resulted in higher expressions of genes involved in apoptosis and inflammatory response such as bcl2, birc3, casp3, c3, ep300, fas, fosb, grb2, il-1α, il-1β, il-6, cxcl-8, nr3c1, prkcq, socs3, and tnfrsf1β and reduced expressions of cd74, crp, faslg, tlr1, and vcam1. The results suggested a novel strategy of Aa, mediated by OMP29 and OMP29par, to evade host immune response by inhibiting CXCL-8 expression and modulating the genes involved in apoptosis and inflammatory response in GECs. Pending further confirmation, the strategy might interfere with the recruitment of neutrophils and dampen the host inflammatory response, leading to a more permissive subgingival niche for bacterial growth.

Highlights

Aggregatibacter actinomycetemcomitans (Aa) is associated with a rapidly progressing form of periodontitis in young subjects, previously known as localized aggressive periodontitis [1,2,3,4,5,6,7]
To determine whether the effect on cxcl-8 expression was due to the compensatory expression of other proteins such as OMP39 in the mutants, we investigated the interaction between OBA09 cell and Aa OMP29His (Figure 2B)
To improve our understanding of the mechanisms involved in periodontitis associated with Aa, we aimed to evaluate the effect of Aa outer membrane protein 29 (OMP29) on the interaction with gingival epithelial cells

Summary

Introduction

Aggregatibacter actinomycetemcomitans (Aa) is associated with a rapidly progressing form of periodontitis in young subjects, previously known as localized aggressive periodontitis [1,2,3,4,5,6,7]. Recent microbiome data confirmed this association and indicated that Aa is 50 times more abundant in periodontal pockets of Grade C/molar–incisor pattern periodontitis (GC/MIP) patients than in subgingival sites of healthy subjects [8]. Aa interacts with epithelial cells through adhesins such as OMP100 [10]. OMP29 causes apoptosis of gingival epithelial cells (GECs) [12]. The OMP29 and its paralogue can inhibit the classical and mannose-binding lectin complement activation by binding to C4-binding protein [13]

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