Protective effect of antibacterial peptide LL37 on lipopolysaccharide-induced inflammatory injury in rat alveolar macrophages

Objective To investigate the protective effect of antimicrobial peptide LL37 on inflammatory damage of rat alveolar macrophage (NR8383) induced by lipopolysaccharide (LPS). Methods The experiment was divided into control group, LPS group, LL37 group, test group and intervention group.Control group was cultured in normal culture medium for 12 h. LPS group was cultured in medium containing 1 mg/L LPS for 12 h. LL37 group was cultured in medium containing 10 mg/L LL37 for 12 h. On the basis of stimulation of 1 mg/L LPS for 12 h, test group was given 10 mg/L LL37 at the same time, intervention group was given 10 mg/L anti-LL-37 antibody on the basis of test group.Cell viability was detected by cell counting Kit-8 assay, cell apoptosis was detected by flow cytometry, The levels of inflammatory factors TNF-α and IL-6 in the cell supernatant were detected by ELISA, The protein expression levels of P-NF-κB p65 were detected by Western blotting. Results Compared with the control group, the cell viability was decreased and the cell apoptosis was increased in LPS group, furthermore, the levels of TNF-α and IL-6 in the supernatant increased, and the protein expression levels of P-NF-κB p65 increased in the LPS group (all P<0.05), Compared with the LPS group, LL37 suppressed the decrease of cell viability and cell apoptosis, and the levels of TNF-α and IL-6 in the supernatant decreased, and the protein expression levels of P-NF-κB p65 also decreased in the test group (all P<0.05), anti-LL-37 antibody could inhibit the effect of LL37 (all P<0.05). Conclusions LL37 can inhibit the production and release of macrophage inflammatory factors induced by LPS and thus play its anti-inflammatory effect by down-regulating the expression of inflammatory-associated NF-κB pathway signaling molecules. Key words: Antimicrobial peptide; Lipopolysaccharide; Inflammatory injury