Oral treatment with SRP299 (killed Mycobacterium vaccae) inhibits experimental periodontal disease in Wistar rats.

OBJECTIVE

Mycobacterium vaccae injected subcutaneously was previously shown to prevent and treat ligature-induced periodontal disease (PD) in Wistar rats (Breivik & Rook 2000, 2002). Since mycobacteria are readily taken up via Peyer's patches in the intestine, we have now tested the ability of oral SRP299 (killed M. vaccae) to prevent ligature-enhanced PD in Wistar rats, and to modulate the accompanying cytokine and corticosterone responses.

MATERIAL AND METHODS

A single oral dose of SRP299 (1 mg) was given 14 days before the application of ligatures. PD was assessed when the ligatures had been in place for 56 days.

RESULTS

Oral SRP299 reduced bone loss (p = 0.036, X-ray; p = 0.061, histometry) and fibre loss, both on the ligatured (p = 0.0047) and control (p = 0.005) sides, and also reduced the level of TNF-alpha (p = 0.0137) and corticosterone (p = 0.048) induced by intraperitoneal endotoxin lipopolysaccharide (LPS).

CONCLUSIONS

SRP299 administered by the oral route diminishes ligature-induced bone and fibre loss in this model. This effect may be attributable to the known ability of SRP299 to evoke regulatory T cells, although the mechanism could not be investigated in this study. Treated rats also had less excitable hypothalamo-pituitary-adrenal (HPA) axes. HPA axis overactivity is a known risk factor in human PD. Trials of SRP299 in human PD are now justified.