Cell-to-Cell Signalling Between Group A Streptococci and Pharyngeal Cells

Abstract

It is becoming more evident that the specific interaction between pathogen and host through their respective surface proteins and counter receptors initiates a series of biochemical signals^{1, 2}. The exchange of these signals between host and pathogen during the initial events of infection determines the final outcome of disease. Although several proteins have been characterized on the surface of streptococci and incriminated to have some role in the pathogenesis of streptococcal diseases³, there is no report related to their potential to initiate host signalling events as a result of the interaction with their specific host cells. Streptococcal Surface Dehydrogenase (SDH) is a multifunctional major streptococcal surface protein that exhibits GAPDH and ADP-ribosylating activity and binds a variety of mammalian proteins^{5, 6}. Since ADP-ribosylation is an important component of intracellular signalling events⁴, ADP-ribosylating activity of SDH indicated that it may have a role in mediating cell-to-cell communication between group A streptococci and pharyngeal cells. In the present communication, we describe this unique role of SDH in terms of its ability to regulate receptor-mediated protein phosphorylation and cytoskeletal rearrangements in human pharyngeal cells using the Detroit 562 human pharyngeal cell line.