Effects of polyhexamethylene guanidine phosphate on human gingival fibroblasts

Objective: Polyhexamethylene guanidine phosphate (PHMG-P) was compared to chlorhexidine (CHX) in order to determine potential cytotoxic and immune-modulatory effects on human gingival fibroblasts. Materials and methods: Cytotoxic effects of PHMG-P and CHX on human gingival fibroblasts were assessed using cell viability assay at various time points and concentrations. The effects of PHMG-P and CHX on the secretion of prostaglandin (PG) E-2, interleukin (IL)-6, IL-8 and matrix metalloproteinase (MMP)-1 by non-stimulated or IL-1 stimulated fibroblasts were evaluated by enzyme-linked immunosorbent assays. Results: PHMG-P concentration 0.00009% led to the total loss of fibroblast viability within 24h, whereas inhibition of fibroblast viability by CHX occurred at significantly higher concentrations of 0.0009% (p<.001). Short-term exposure to 0.005% PHMG-P led to loss of fibroblast viability after 5min, whilst cells exposed to 0.005% CHX survived 30min of treatment (p<.001). IL-1 stimulation induced an inflammatory response with a significant increase in the secretion of PGE(2), IL-6, IL-8 and MMP-1. Treatment of IL-1 stimulated fibroblasts in combination with PHMG-P or CHX at concentrations of 0.000045 or 0.0.00009% resulted in significantly decreased PGE(2), IL-6, IL-8 and MMP-1 levels. PHMG-P or CHX alone did not affect the baseline secretion of PGE(2), IL-6, IL-8 or MMP-1 by gingival fibroblasts. Conclusions: Cytotoxic effects on gingival fibroblasts were triggered by both PHMG-P and CHX at concentrations below those used in clinical practice. The tested antiseptics did not cause inflammation and reduced IL-1-induced secretion of inflammatory mediators and collagenase by gingival fibroblasts, which suggests anti-inflammatory properties.