Differential Modulation of Saliva-Derived Microcosm Biofilms by Antimicrobial Peptide LL-31 and D-LL-31.

Microbiome modulation, aiming to restore a health-compatible microbiota, is a novel strategy to treat periodontitis. This study evaluated the modulation effects of antimicrobial peptide LL-31 and its D-enantiomer (D-LL-31) on saliva-derived microcosm biofilms, spiked with or without Porphyromonas gingivalis. To this end, one-day-old biofilms were incubated for 24 h with biofilm medium alone, or medium containing 40 µM LL-31 or D-LL-31, after which biofilms were grown for 5 days. Biofilms were assessed at 1 day and 5 days after intervention for the total viable cell counts, dipeptidyl peptidase IV (DPP4) activity, P. gingivalis amount (by qPCR) and microbial composition (by sequencing). The results showed that D-LL-31, not LL-31, significantly reduced the total viable cell counts, the P. gingivalis amount, and the DPP4 activity of the biofilms spiked with P. gingivalis, but only at 1 day after intervention. In the biofilms spiked with P. gingivalis, D-LL-31 tended to reduce the α-diversity and the compositional shift of the biofilms in time as compared to the control and LL-31 groups. In conclusion, D-LL-31 showed a better performance than LL-31 in biofilm modulation. The biofilm modulation function of the peptides could be impaired when the biofilms were in a severely dysbiotic state.

Smoking reduces cathelicidin LL-37 and human neutrophil peptide 1-3 levels in the gingival crevicular fluid of patients with periodontitis.

BACKGROUND: Antimicrobial peptides are components of innate immune response that have a key role on susceptibility and resistance of the oral cavity to diseases. This study aimed to investigate the influence of smoking on cathelicidin LL-37 and human neutrophil peptides 1 through 3 (HNP 1-3) levels in the gingival crevicular fluid (GCF) of patients with periodontitis. The relationship between levels of these peptides with the periodontal status and selected inflammatory mediators levels in smokers and non-smokers was also evaluated. METHODS: Forty patients with periodontitis, 20 smokers and 20 non-smokers were recruited. After a full periodontal clinical assessment, GCF samples were collected from healthy (n = 5) and diseased (n = 5) sites of each patient. Peptides and inflammatory mediators in the GCF were quantitated by sandwich ELISAs and Multiplex assay, respectively. RESULTS: Diseased sites had significantly (P <0.05) higher levels of LL-37 and lower levels of HNP 1-3 than healthy sites in both smokers and non-smokers. Diseased sites of smokers presented significantly lower levels of LL-37 and HNP 1-3 when compared with diseased sites of non-smokers. Concentration of LL-37 was directly correlated with the presence of proinflammatory mediators matrix metalloproteinase (MMP)-8 and interleukin (IL)-1ß and inversely correlated with concentration of IL-10. HNP 1-3 concentration was positively correlated with IL-10 and negatively correlated with concentrations of MMP-8 and IL-1ß. CONCLUSIONS: Smoking was associated with reduced levels of LL-37 and HNP 1-3 in GCF of patients with periodontitis. LL-37 had a distinct expression pattern from HNP 1-3: LL-37 was upregulated in diseased sites, and HNP 1-3 was increased in periodontally healthy sites.1.