T-lymphocyte phenotype and function triggered by Aggregatibacter actinomycetemcomitans is serotype-dependent

J Periodontal Res. 2015 Dec;50(6):824-35. doi: 10.1111/jre.12270. Epub 2015 Mar 30.

Abstract

Background and objective: Based on lipopolysaccharide (LPS) antigenicity, different Aggregatibacter actinomycetemcomitans serotypes have been described. Serotype b strains have demonstrated a stronger capacity to trigger cytokine production on dendritic cells (DCs). As DCs regulate the development of T-lymphocyte lineages, the objective of this investigation was to study the response of T lymphocytes after being stimulated with autologous DCs primed with different bacterial strains belonging to the most prevalent serotypes of A. actinomycetemcomitans in humans: a-c.

Material and methods: Human DCs were primed with increasing multiplicity of infection (10(-1) -10(2) ) or the purified LPS (10-50 ng/mL) of A. actinomycetemcomitans serotypes a-c and then used to stimulate autologous naïve CD4(+) T lymphocytes. The T-helper (Th) type 1, Th2, Th17 and T-regulatory transcription factors T-bet, GATA-3, RORC2 and Foxp3, which are the master-switch genes implied in their specific differentiation, as well as T-cell phenotype-specific cytokine patterns were quantified by real-time reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. In addition, the intracellular expression of T-bet/interferon-γ, GATA-3/interleukin-4, RORC2/interleukin-17A and Foxp3/transforming growth factor-β1 was analysed by double staining and flow cytometry.

Results: All the A. actinomycetemcomitans serotypes led to T-lymphocyte activation; however, when T lymphocytes were stimulated with DCs primed with the A. actinomycetemcomitans serotype b strain or their purified LPS, higher levels of Th1- and Th17-associated transcription factors and cytokines were detected compared with similar experiments with the other serotypes.

Conclusion: These results demonstrate that serotype b of A. actinomycetemcomitans has a higher capacity of trigger Th1 and Th17 phenotype and function and it was demonstrated that their LPS is a more potent immunogen compared with the other serotypes.

Keywords: Aggregatibacter actinomycetemcomitans; T lymphocytes; cytokines; lipopolysaccharide; serotypes; transcription factors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aggregatibacter actinomycetemcomitans / classification
  • Aggregatibacter actinomycetemcomitans / immunology*
  • Cells, Cultured
  • Cytokines / analysis
  • Enzyme-Linked Immunosorbent Assay
  • Flow Cytometry
  • Gene Expression Profiling
  • Humans
  • Immunophenotyping
  • Lipopolysaccharides / immunology
  • Phenotype*
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • Serogroup*
  • T-Lymphocytes / immunology*
  • Transcription Factors / analysis

Substances

  • Cytokines
  • Lipopolysaccharides
  • Transcription Factors