Differential cytokine expression by human dendritic cells in response to different Porphyromonas gingivalis capsular serotypes

Abstract

Aim: Capsular polysaccharides play an important role in the virulence of Grampositive and Gram-negative bacteria. In Porphyromonas gingivalis, six serotypes have been described based on capsular antigenicity and its pathogenicity has been correlated both in vitro and in animal models. This study aimed to investigate the differential response of human dendritic cells (DCs) when stimulated with different P. gingivalis capsular serotypes. Materials and Methods: Using different multiplicity of infection (MOI) of the encapsulated strains K1–K6 and the non-encapsulated K strain of P. gingivalis, the mRNA expression levels for interleukin (IL)-1b, IL-2, IL-5, IL-6, IL-10, IL-12, IL-13, interferon (IFN)-g, tumour necrosis factor (TNF)-a, and TNF-b in stimulated DCs were quantified by real-time reverse transcription-polymerase chain reaction. Results: All P. gingivalis capsular serotypes induced a T-helper type 1 (Th1) pattern of cytokine expression. K1- and K2-stimulated DCs expressed higher levels of IL-1b, IL-6, IL-12p35, IL-12p40, and IFN-g and at lower MOI than DCs stimulated with the other strains. Conclusions: These results demonstrate a differential potential of P. gingivalis capsular serotypes to induce DC responses and a higher capacity of strains K1 W83 and K2 HG184 than other K serotypes to trigger cytokine expression.