Effect of the Antimicrobial Peptide LL-37 on Gene Expression of Chemokines and 29 Toll-like Receptor-Associated Proteins in Human Gingival Fibroblasts Under Stimulation with Porphyromonas gingivalis Lipopolysaccharide

• Published in: Probiotics and antimicrobial proteins Vol. 12; no. 1; pp. 64 - 72
• Main Authors: Inomata, Megumi, Horie, Toshi, Into, Takeshi
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.03.2020; Springer Nature B.V
• Subjects: Antimicrobial peptides; Applied Microbiology; Biological activity; CD14 antigen; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Chemokines; CXCL10 protein; Cytotoxicity; Fibroblasts; Gene expression; Gene regulation; Interleukin 8; IRAK protein; Lipopolysaccharides; Microbiology; Monocyte chemoattractant protein 1; Nutrition; Peptides; Porphyromonas gingivalis; Protein Science; TLR4 protein; Toll-like receptors; Human gingival fibroblasts; LL-37; lipopolysaccharide; Toll-like receptor; Porphyromonas gingivalis lipopolysaccharide
• ISSN: 1867-1306; 1867-1314
• DOI: 10.1007/s12602-019-09600-2

The antimicrobial peptide LL-37 neutralizes the biological activity of lipopolysaccharide (LPS), while it upregulates the expression of several immune-related genes. We investigated the effect of LL-37 on gene regulation of human gingival fibroblasts (HGFs), stimulated with or without Porphyromonas gingivalis -derived LPS, a ligand for Toll-like receptor (TLR). LL-37 was non-toxic to HGFs up to a concentration of 10 μg/ml. P. gingivalis LPS upregulated the expression of IL8 , CXCL10 , and CCL2 , whereas LL-37 reduced this upregulation. In absence of LPS, LL-37 itself upregulated the expression of IL8 and CCL2 . LL-37 increased the expression of P2X7, which was constitutively expressed in HGFs. The P2X7 antagonist A-438079 suppressed the cytotoxicity and upregulatory effect of LL-37 on chemokine response, but not its downregulatory effect on P. gingivalis LPS–induced chemokine response. Whether LL-37 alters the expression of 29 genes that encode TLR-associated proteins, including TLRs, co-receptors, signaling molecules, and negative regulators, in HGFs, under stimulation with LPS, was examined. Among TLRs, P. gingivalis LPS upregulated the level of TLR4 , whereas LL-37 reduced it. In co-receptors, LL-37 downregulated the level of CD14 . Among signaling molecules, LL-37 augmented the LPS-upregulated expression of IRAK1 . Similar effects were observed in the specific negative regulators TNFAIP3 , RNF216 , TOLLIP , and SIGIRR . Our results suggest that LL-37 exerts cytotoxicity and upregulation of chemokine response via the P2X7 receptor, while it induces downregulation of P. gingivalis LPS–induced chemokine response through alteration in the expression of 7 specific TLR-associated genes: downregulation of TLR4 and CD14 and upregulation of IRAK1 , TNFAIP3 , RNF216 , TOLLIP , and SIGIRR .