Subchronic Infection of Porphyromonas gingivalis and Tannerella forsythia Stimulates an Immune Response but Not Arthritis in Experimental Murine Model

Studies have proposed that Porphyromonas gingivalis (Pg) and Tannerella forsythia (Tf) promote a nonspecific inflammatory response that could produce systemic disease. Oral inoculation of Pg and Tf on the immune and arthritis response was evaluated in BALB/C mice divided into four groups: (1) sham; (2) food contaminated with Pg/Tf; (3) complete Freund's adjuvant (CFA) + Pg/Tf; and (4) CFA alone. CFA was administered subcutaneously on days 1 and 14. The arthritis response was monitored for 21 days after day 14 of CFA administration. IL-1β and IL-6 were determined in serum. T cell activation was evaluated by CD25 in salivary lymph nodes or mouse spleen. Pad inflammation appeared by day 19 in the CFA group, but animals with bacteria inoculation presented a delay. A significant increase in IL-6 was found in Groups 3 and 4, but not with respect to IL-1β. We observed an increase in CD25 in cells derived from cervical nodes and in animals with bacteria inoculation and CFA. A local immune response was observed in mice inoculated with Pg and Tf (T cell activation); a systemic response was observed with CFA. Since pad inflammation was delayed by bacterial inoculation this suggests that local T cell activation could decrease pad inflammation.