In vitro immune activation by Treponema pallidum and the effect on osteoclastogenesis: first experimental step towards an integration between osteoimmunology and paleopathology.

The presence of pathogens in the human body influences the expression of pro-inflammatory cytokines by activated immune cells. These cytokines, and other factors, regulate osteoclastogenesis and osteoclast activity. Through experimental osteoimmunology, interactions between the inflammatory response and bone cell physiology may provide insight into how immune processes can be translated into the lesions or abnormalities observed in the osteological record. In this research, our objective was to determine if the cytokines produced by activated immune cells increase osteoclastogenesis and osteoclast activity. To evaluate this hypothesis, we used two main protocols, one for immune activation and one for osteoclastogenesis, that utilized peripheral blood mononuclear cells (PBMCs) from healthy donors. The results of these protocols indicated that cells exposed to Tp47, an antigen of Treponema pallidum, produce relatively more TNFα and IFNg than cells not exposed to infectious stimuli, yet osteoclastogenesis conditions exposed to Tp47 supernatants produced only slightly more osteoclasts than conditions exposed to untreated supernatants. After preliminary data, this outcome indicates that higher concentrations of TNFα and IFNg may not be connected to increased osteoclastogenesis. Further research is needed to increase the sample size, allowing for statistical analyses that control for the high inter-sample variability