Suppression of T-cell chemokines by Porphyromonas gingivalis

Porphyromonas gingivalis is a major pathogen in periodontal disease and is associated with immune dysbiosis. In this study, we found that P. gingivalis did not induce the expression of the T-cell chemokine IP-10 (CXCL10) from neutrophils, peripheral blood mononuclear cells (PBMCs), or gingival epithelial cells. Furthermore, P. gingivalis suppressed gamma interferon (IFN-γ)-stimulated release of IP-10, ITAC (CXCL11), and Mig (CXCL9) from epithelial cells and inhibited IP-10 secretion in a mixed infection with the otherwise stimulatory Fusobacterium nucleatum. Inhibition of chemokine expression occurred at the level of gene transcription and was associated with downregulation of interferon regulatory factor 1 (IRF-1) and decreased levels of Stat1. Ectopic expression of IRF-1 in epithelial cells relieved P. gingivalis-induced inhibition of IP-10 release. Direct contact between P. gingivalis and epithelial cells was not required for IP-10 inhibition. These results highlight the immune-disruptive potential of P. gingivalis. Suppression of IP-10 and other Th1-biasing chemokines by P. gingivalis may perturb the balance of protective and destructive immunity in the periodontal tissues and facilitate the pathogenicity of oral microbial communities.