Aggregatibacter actinomycetemcomitans: GroEL protein promotes conversion of human CD4+T cells into IFNγ IL10 producing Tbet+Th1 cells

Abstract

One of the heat shock family protein (Hsp) expressing bacteria is the gram negative, periodontal pathogen Aggregatibacter actinomycetemcomitans (Aa). A. actinomycetemcomitans' Hsp is a 64-kDa GroEL-protein, which has been shown to influence the host cells. In this study we used recombinant A. actinomycetemcomitans GroEL (rAaGroEL) protein as a model antigen to study GroEL-mediated T cell immune response. Human peripheral mononuclear cells (PBMCs), when stimulated with recombinant rAaGroEL, expressed early activation marker CD69 and IL-2R (CD25). CD25 and CD69 expressions were higher in CD4+ T cells compared to CD8+ T cells. rAaGroEL-responding CD4+ T cells expressed IL-10, IFN gamma and TNF alpha cytokines. Interestingly, there were also IL-10 and IFN gamma double cytokine producing CD4+ T cells. Additionally, IFN gamma expressing CD4+ T cells were also T-bet positive. Altogether the results suggest that rAaGroEL protein affects CD4+ T cells to differentiate into IFN gamma IL10-secreting T-bet+ Th1 cells.