Infection of Human Dental Pulp Stromal Cells by Streptococcus mutans : Shedding Light on Bacteria Pathogenicity and Pulp Inflammation.

CariogenicStreptococcus mutans(S. mutans) is implicated in the dental pulp necrosis but also in cardiovascular tissue infections. Herein, the purpose was to elucidate how human dental pulp derived stromal cells (DPSCs) react toward a direct interaction withS. mutans. DPSCs were challenged withS. mutans. Following 3 h of interaction, DPSCs were able to internalizeS. mutans(rate < 1%), and F-actin fibers played a significant role in this process.S. mutanspersisted in the DPSCs for 48 h without causing a cytotoxic effect.S. mutanswas, however, able to get out of the DPSCs cytoplasm and to proliferate in the extracellular environment. Yet, we noticed several adaptive responses of bacteria to the extracellular environment such as a modification of the kinetic growth, the increase in biofilm formation on type I collagen and polyester fabrics, as well as a tolerance toward amoxicillin. In response to infection, DPSCs adopted a proinflammatory profile by increasing the secretion of IL-8, lL-1 beta, and TNF-alpha, strengthening the establishment of the dental pulp inflammation. Overall, these findings showed a direct impact ofS. mutanson DPSCs, providing new insights into the potential role ofS. mutansin infective diseases.