Co-culture of S. aureus and A. graevenitziimodulates innate immune responses
Given that co-culture with oral flora like A. graevenitziiappeared to suppress S. aureus growth, we hypothesized that this interaction may also modulate innate immune responses to S. aureus. To test this, we measured neutrophil recruitment to co-culture of S. aureus and A. graevenitzii compared to mono-cultures of S. aureus or A. graevenitzii alone. As previously reported[17], S. aureus mono-cultures induced robust recruitment of neutrophils into the culture chamber (Fig. 6B). Importantly, this response was significantly blunted for co-cultures containing A. graevenitzii (Fig. 6B). Interestingly, recruitment of neutrophils to to co-cultures was also lower compared to A. graevenitzii mono-cultures (Fig. 6B), suggesting that compounds released during co-culture modifiy the microenvironment and influence neutrophil responses. It is also possible that the two species become less active / more quiscent, and thus they stimulate neutrophils less than exponentially growing cultures.