LACK OF SOLUBLE TUMOR NECROSIS FACTOR ALPHA RECEPTOR 1 AND 2 AND INTERLEUKIN-1β COMPARTMENTALIZATION IN LUNGS OF MICE AFTER A SINGLE INTRATRACHEAL INOCULATION WITH LIVE PORPHYROMONAS GINGIVALIS.

Porphyromonas gingivalis aspiration pneumonia induces local and systemic cytokine responses, but the dynamic of the immune response following lung exposure to live P. gingivalis is poorly understood. Groups of 50 12-week-old male BALB/c mice were inoculated intratracheally with live P. gingivalis ATCC 33277 using low dose (2 × 105 colony-forming units [CFU]), high dose (2.9 × 109 CFU), or phosphate-buffered saline (PBS; sham-inoculated), and the 3 groups were sacrificed at 2, 6, 24, 72, 168 hours. Lung and serum samples were collected for tumor necrosis factor alpha (TNF-α), soluble TNF-α receptors (sTNFRs), interleukin (IL)-1β, and IL-6 analysis and lung histology. Pneumonia, only observed in the high-dose group, was associated with an early increase in lung TNF-α, IL-1β, and IL-6, whereas no significant changes were observed in lung sTNFRs. Serum sTNFRs were significantly increased in high-dose animals at all times. IL-1β elevation occurred earlier in serum than in lungs. IL-1β was also significantly elevated in serum from low-dose animals at 6 hours. Serum IL-6 and sTNFRs remained raised at 7 days, whereas all other measured cytokines returned to basal levels with resolution of pneumonia. Development of pneumonia is dependent on the P. gingivalis dose; however, part of the cytokine response is unique to the systemic compartment, even in animals that do not develop pneumonia. [ABSTRACT FROM AUTHOR]