Salivary Expression of Antimicrobial Peptide LL37 and Its Correlation with Pro-inflammatory Cytokines in Patients with Different Periodontal Treatment Needs

Antimicrobial peptide LL37, present in the saliva, has an important role in oral health maintenance, and many studies have shown that this peptide can modulate pro-inflammatory cytokine expression. The study of salivary cytokine expression helps shed further light on the salivary immune system and can predict or monitor periodontal disease. The aim of this study was to determine LL37 levels, comparing them with the levels of salivary TNF-α, IL6, and IL-1β of patients with different treatment needs. A total of 120 patients, classified by periodontal treatment needs according to the PSR/CPITN index, participated in this study. Group 1 included periodontally healthy patients (index 0), whereas groups 2 and 3 consisted of patients with periodontal disease—group 2 with at least one sextant classified as index 1 or 2 and group 3 with at least one sextant presenting index 3 or 4. Salivary samples were collected from all patients and TNF-α, IL6, IL-1β, and LL37 antimicrobial peptide were determined by ELISA. Patients without periodontal treatment needs showed higher salivary levels of LL37 when compared to those with any periodontal involvement. Low salivary LL37 levels in patients with periodontal disease were associated with the increase of TNF-α and IL6 expressions. No relationship between salivary IL-1β levels and different PSR/CPTIN indices, nor any correlation of IL-1β with salivary LL37 concentration, was observed. Results of the present study support the hypothesis that low levels of LL37 can modulate the production of pro-inflammatory cytokines such as TNF-α and IL6.