Single gavage with Porphyromonas gingivalis reduces acute systemic nitric oxide response in mice

Porphyromonas gingivalis, an important periodontal pathogen, can also induce host responses in distant tissues. P. gingivalis induces nitric oxide (NO) production in immune system cells and non-immune system cells, therefore NO might be involved in an acute systemic host response.

Eighteen female BALB/c mice were perorally inoculated with 10(8) colony-forming units live P. gingivalis ATCC 33277. Plasma nitrite and nitrate (NOx) and NO production in lungs, aorta, heart, liver, spleen, kidneys, and brain were measured at intervals after inoculation and compared with levels in 11 control animals.

NOx levels were significantly (P = 0.017) lower at 7, 13, and 25 h after P. gingivalis inoculation. A similar trend in NO production occurred in most tested organs, but never reached statistical significance. The correlation between NOx in plasma and NO in liver was positive (Spearman correlation coefficient = 0.81, P = 0.0025) and marginal for kidney (0.58, P = 0.059).

Single peroral inoculation of mice with P. gingivalis reduces the acute systemic NO response. As NO is important for host defense, the reduction of NO levels after exposure is likely to delay the host response, increasing the chances that infection with P. gingivalis will become established.