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

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

doi:10.3389/froh.2022.835902

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

Front Oral Health. 2022 Feb 3:3:835902. doi: 10.3389/froh.2022.835902. eCollection 2022.

Affiliations

¹ Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.
² Division of Periodontology, Diagnostic Sciences and Dental Hygiene, Ostrow School of Dentistry of University of Southern California, Los Angeles, CA, United States.
³ Centro Universitário Atenas- UniAtenas, Paracatu, Brazil.
⁴ Department of Comprehensive Oral Health, Adams School of Dentistry, University of North Carolina, Chapel Hill, NC, United States.
⁵ Instituto de Alimentação e Nutrição, Centro Multidisciplinar UFRJ-Macaé, Universidade Federal do Rio de Janeiro, Macaé, Brazil.
⁶ Department of Foundational Sciences, School of Dental Medicine of University of East Carolina University, Greenville, NC, United States.

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 OMP29^par on the response of GECs to Aa. The omp29 or/and omp29 ^par deletion mutants AaΔ29, AaΔ29P, and AaΔ29Δ29P were constructed, and recombinant Aa OMP29^His 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 OMP29^His. Proteomics analysis showed that the deletion of omp29 led to overexpression of both OMP29^par 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 OMP29^His 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 OMP29^par, 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.

Keywords: Aggregatibacter actinomycetemcomitans; aggressive periodontitis; gingival epithelial cells; inflammatory response; outer membrane protein 29; outer membrane protein 29 paralogue; virulence factors.