title: Favorable interleukin-8 induction in human gingival epithelial cells by the antimicrobial peptide LL-37.
abstract: BACKGROUND
  LL-37, the only member of the antimicrobial peptide cathelicidin family in humans, exerts a variety of biological activities, especially immunomodulation through either direct chemotactic activity or up-regulation of several cytokines and chemokines in various cell types. In this study, we aimed to determine the immunoregulatory effect of LL-37 on Th1/Th2 cytokine expression and production in human gingival epithelial cells (HGECs).
  
  
  METHODS
  Cultured HGECs were treated with different concentrations of LL-37 for different numbers of times. The cytotoxicity of LL-37 was determined by an MTT assay. Total RNA was isolated for RT-PCR and real-time PCR analyses of cytokine expression. Cell-free culture supernatants were assayed for Th1/Th2 cytokine levels by a cytokine bead array.
  
  
  RESULTS
  Out of eleven Th1/Th2 cytokines tested, treatment of HGECs with non-toxic doses of LL-37 (2-6 μM) significantly raised only IL-8 levels in the cell-free culture supernatants, when compared to control untreated cells (P <0.05). Consistent with the elevated IL-8 levels, IL-8 mRNA expression was remarkably and significantly induced by LL-37 treatment (P < 0.05), when compared to the modest mRNA induction of other three cytokines, including IL-1β, IL-6, and TNF-α. The time-course study demonstrated a cumulative IL-8 mRNA induction by LL-37 treatment within a 24-hour interval.
  
  
  CONCLUSIONS
  These findings indicate that LL-37 favorably induces IL-8 expression and secretion in HGECs, suggesting both direct and indirect involvement of LL-37 in neutrophil recruitment into an inflammatory site within diseased periodontal tissues.
authors.affiliation: Department of Restorative Dentistry and Periodontology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand.
authors.forename: Pattanin
authors.initials: P
authors.lastname: Montreekachon
authors.forename: Sirikul
authors.initials: S
authors.lastname: Nongparn
authors.forename: Thanapat
authors.initials: T
authors.lastname: Sastraruji
authors.forename: Sakornrat
authors.initials: S
authors.lastname: Khongkhunthian
authors.forename: Nuttapol
authors.initials: N
authors.lastname: Chruewkamlow
authors.forename: Watchara
authors.initials: W
authors.lastname: Kasinrerk
authors.forename: Suttichai
authors.initials: S
authors.lastname: Krisanaprakornkit
mesh_terms: D023181:Antimicrobial Cationic Peptides; D054804:Cathelicidins / Q000276:immunology / Q000378:metabolism*; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D005881:Gingiva / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000276:immunology; D008297:Male; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D023181:Antimicrobial Cationic Peptides; C508606:CXCL8 protein, human; D054804:Cathelicidins; D016209:Interleukin-8