# Modulation of LPS-associated virulence activity for reduction of periodontal inflammatory burden

## TL;DR

This study shows that reducing LPS activity in oral biofilms using LL-37 and Polymyxin B can significantly lower inflammation in periodontal diseases.

## Contribution

The study introduces LL-37 and Polymyxin B as novel modulators of LPS virulence activity in periodontal biofilms.

## Key findings

- LL-37 and Polymyxin B reduced endotoxin activity by over 90% in saliva and subgingival biofilms.
- Modulation suppressed pro-inflammatory cytokines by 40–75% without affecting anti-inflammatory cytokines.
- LL-37 and Polymyxin B showed complementary effects on NF-κB and IRF signaling pathways.

## Abstract

Dysbiotic oral biofilms produce virulence factors, such as lipopolysaccharide (LPS), triggering and sustaining chronic inflammation in periodontal tissues. Modulation of the bioactivity of these products offers a potential novel, adjunctive approach beyond conventional periodontal therapy.

Pooled saliva and subgingival biofilm samples from 324 healthy, gingivitis, and periodontitis participants were assessed for endotoxin activity using the recombinant Factor C (rFC) assay. Functional immune-stimulation was evaluated in THP-1 and THP-1 Dual cell models through NF-κB and IRF pathways activation assessment and cytokine profiling. The modulatory effects of antimicrobial peptide LL-37 and the LPS-binding compound Polymyxin B on saliva and subgingival biofilm inflammatory potential were assessed in the same models.

Recombinant Factor C assays demonstrated marked reductions in endotoxin activity of saliva and subgingival biofilms treated with LL-37 and Polymyxin B (>90% reduction). Both NF-κB and IRF signaling were broadly attenuated following modulation, with polymyxin B exerting greater suppression of NF-κB activity, while LL-37 showed stronger inhibition of IRF, particularly in salivary samples. Pro-inflammatory cytokines secretion by THP-1 cells (IL-1β, IL-6, IL-8, and TNF-α) challenged with bio-modulated samples decreased by 40–75% compared to untreated samples. Interestingly, anti-inflammatory cytokines such as TGF-β and IL-10 remained largely unchanged, suggesting selective suppression of the cytokine cascade.

Modulating LPS-associated virulence activity substantially reduces the inflammatory potential of saliva and subgingival plaque. LL-37 and Polymyxin B illustrate complementary strategies for LPS modulations and highlight the feasibility of their use as adjunctive approaches for the prevention and treatment of periodontal diseases.