Antibiotic-induced Porphyromonas gingivalis LPS release and inhibition of LPS-stimulated cytokines by antimicrobial peptides

Bacterial lipopolysaccharide (LPS) release during periodontal infection is a significant component of periodontal disease. We hypothesized that some bacterial LPS release results from bacterial exposure to antibiotics. Therefore, we examined the ability of various classes of antibiotics to induce LPS release from Porphyromonas gingivalis as well as the ability of antimicrobial peptides (AMPs) to inhibit purified LPS. All antibiotics tested against P. gingivalis were able to liberate 1.9–12.9 times more LPS as compared to untreated bacteria. Among the three AMPs tested, LL-37 was found to be the most potent inhibitor of cytokine (tumor necrosis factor-α, interleukin-1β, interleukin-6) production and completely neutralized purified P. ginigivalis LPS activity in the chromogenic limulus amebocyte lysate (LAL) and whole blood cytokine stimulation assays. These observations suggest that therapeutic approaches utilizing AMPs as adjuncts to neutralize released LPS should be considered.

Research highlights▶All antibiotics tested induced the release of LPS from P. gingivalis. ▶ Different antibiotic classes promoted varying degrees of LPS release. ▶ LL-37 was the only AMP able to completely inhibit the LPS activity. ▶ KSL-W and histatin 8 neutralized 50% and 20% of LPS activity, respectively. ▶ Comparatively, minimal amounts (1.4 μM) of LL-37 blocked 100% of all cytokines tested.