Temperature for Bacterial Growth Affects P. gingivalis-THP-1 Monocytes Interaction

Abstract

Objective: Environmental factors could play important roles in modulating bacteria-host crosstalk and interaction in the current paradigm of periodontal pathogenesis. Given that in different oral inflammatory conditions, the temperature in periodontal niches varies as well. This study aimed to examine the effect of bacterial growth temperature on the crosstalk of P. gingivalis-THP-1 monocytes. Method: The ‘keystone’ periodontopathogen Porphyromonas gingivalis (Pg) 33277 was subcultured on blood agar in anaerobic environment at 37oC, 39oC and 41oC one week prior to the experiments. The cultured bacteria were then added to THP-1 monocytes with MOI 10 to establish a Pg-THP-1 co-culture model for an incubation of 2 hours at 37oC. The expression of IL-1β, IL-6, IL-8 and TNF-α was assessed using ELISA and real-time qPCR.

Result: No significant difference was found in the viability of Pg and the THP-1 cells challenged with Pg, as well as the CFU counting among the three co-culture groups with Pg prior cultured under different growth temperatures. The expression levels of IL-8 and TNF-α at the co-culture group with Pg prior cultured at 37oC (37oC-group), 39oC (39oC-group) and 41oC (41oC-group) were higher than the control (p<0.05). Interestingly, the 37oC-group showed higher level of IL-8 as compared to the 41oC-group (p<0.05). Moreover, the group with Pg prior cultured at 37oC had a significantly higher level of TNF-α than the 39oC- and 41oC-groups (p<0.05). No significant difference in IL-1β and IL-6 levels occurred among the 3 groups with reference to the control.

Conclusion: This pioneer study shows that Pg cultured at different temperatures interacts differentially with human monocytes. This ‘keystone’ periodontopathogen could modulate immuno-inflammatory response in different periodontal conditions under which temperature could be niche/site-specific in connection to various bacteria-host crosstalks, thereby contributing to periodontal pathogenesis.