Proanthocyanidins from Rumex acetosa L. increase the in vitro rate of phagocytosis of Porphyromonas gingivalis in murine macrophages and provide a cytoprotective and anti-inflammatory potential for modern periodontitis therapy

Periodontitis is a chronic inflammatory disease, triggered by various bacteria. One of the major pathogens involved in the progression of periodontitis, is Porphyromonas gingivalis, a gram-negative anaerobic bacteria. Using multifunctional virulence factors, the bacterium is able to evade the host immune response, without inhibiting the inflammatory cascade. The persistent inflammation leads to subsequent tissue damage, which the bacteria use for nutrient aquisition. Phagocytosis by macrophages plays a crucial role in the first line innate immune defense against P. gingivalis. We have previously reported on the antiadhesive effects of Rumex extract and activity against biofilm formation. Aim of the following study was the investigation of effects of Rumex extract on macrophage activity and on the anti-inflammatory potential.

Acetone-water extract (7:3) from Rumex acetosa L. (RA1) was tested on in vitro phagocytosis rate of murine RAW 264.7 macrophages and the respective NO-production. The viability of the cells was controlled by MTT assay. In addition to that the release of inflammatory cytokines was quantified by ELISA.

The results show that the extract RA1 significantly stimulates the uptake of Zymosan particles (0,1 µg/mL: + 18%; 1 µg/mL: + 9% stimulation) and furthermore the phagocytosis of P. gingivalis (0,1 µg/mL: + 53%; 1 µg/mL: + 39%) by RAW 264.7 macrophages. No influence of RA1 was observed for NO production. In a costimulation experiment with LPS-activated macrophages, the NO production could slightly be decreased by the extract (0,1 µg/mL: -7%). Within MTT assay it was observed that RA1 shows a cytoprotective effect on the viability of the macrophages (0,1 µg/mL: + 24% cell viability).

RA1 (10 µg/mL) decreases cytokine expression of IL 6 and IL 8 from P. gingivalis infected KB cells.