Differential transcription of virulence genes in Aggregatibacter actinomycetemcomitans serotypes

Background: Aggregatibacter actinomycetemcomitans serotypes are clearly associated with periodontitis or health, which suggests distinct strategies for survival within the host.\ud Objective: We investigated the transcription profile of virulence-associated genes in A. actinomycetemcomitans serotype b (JP2 and SUNY 465) strains associated with disease and serotype a (ATCC 29523) strain associated with health. Design: Bacteria were co-cultured with immortalized gingival epithelial cells (OBA-9). The adhesion efficiency\ud after 2 hours and the relative transcription of 13 genes were evaluated after 2 and 24 hours of interaction. Results: All strains were able to adhere to OBA-9, and this contact induced transcription of pgA for polysaccharide biosynthesis in all tested strains. Genes encoding virulence factors as Omp29, Omp100, leukotoxin, and CagE (apoptotic protein) were more transcribed by serotype b strains than by serotype a. ltxA and omp29, encoding the leukotoxin and the highly antigenic Omp29, were induced in serotype b by\ud interaction with epithelial cells. Factors related to colonization (aae, flp, apaH, and pgA) and cdtB were upregulated in serotype a strain after prolonged interaction with OBA-9.\ud Conclusion: Genes relevant for surface colonization and interaction with the immune system are regulated differently among the strains, which may help explaining their differences in association with disease.FAPESP - 03/08598-0FAPESP - 05/58903-

Gene expression analysis after interaction between Aggregatibacter actinomycetemcomitans and epithelial cell.

Aggregatibacter actinomycetemcomitans (A.a) é associado a periodontite agressiva. Na infecção, pode ocorrer ativação de vias de sinalização do hospedeiro e bacterianas. Objetivos: determinar a transcrição de genes relacionados à virulência bacteriana e das vias de transdução de sinais da célula epitelial após interação bactéria-célula epitelial. Métodos: cepas de A.a foram co-cultivadas com células epiteliais OBA-9. A transcrição dos genes bacterianos e das células epiteliais foi determinada por RT-qPCR e a concentração de citocinas determinada por ELISA. Resultados: A regulação da transcrição de certos genes de virulência de A.a é cepa e tempo específica. Quinze genes foram regulados positivamente nas células OBA-9 infectadas. Altos níveis de GM-CSF, TNF-&#945 e ICAM-1 foram detectados em células OBA-9 infectadas e tecidos gengivais de pacientes com periodontite. Conclusão: a interação entre A. a e célula epitelial pode modular a resposta do hospedeiro com a indução da expressão de fatores que exacerbam o processo inflamatório.Aggregatibacter actinomycetemcomitans (A.a) is associated with the etiology of aggressive periodontitis. The activation of signaling pathways by the host and bacterial cells occurs during infection. Objectives: to determine the transcription of genes related to bacterial virulence and epithelial cell after bacterial-epithelial cell interaction. Methods: A.a strains were co-cultured with epithelial cells OBA-9. The transcription of A.a virulence genes and genes belonging to signaling transduction pathway were determined by RT-qPCR and the concentration of cytokines was determined by ELISA. Results: the transcription of some virulence genes is strain and time specific. Fifteen genes were up-regulated in OBA-9 cells. High levels of GM-CSF, TNF-&#945 and ICAM-1 were detected in infected OBA-9 cells and tissues of patients with periodontitis. Conclusion: the interaction between A.a and epithelial cell can modulate the host response with induction of factors which exacerbate inflammatory process