Human antimicrobial peptide LL-37 modulates proinflammatory responses induced by cytokine milieus and double-stranded RNA in human keratinocytes

Biochem Biophys Res Commun. 2013 Apr 19;433(4):532-7. doi: 10.1016/j.bbrc.2013.03.024. Epub 2013 Mar 20.


Epidermal keratinocytes produce proinflammatory cytokines/chemokines upon stimulation with cytokine milieus and Toll-like receptor ligands, which are considered to reflect epidermal environments in inflamed skin. The human antimicrobial peptide LL-37, besides having microbicidal functions, plays multiple roles as a "host defense peptide" in the immune system. Here, we examined the effect of LL-37 on proinflammatory responses induced by double-stranded RNA (dsRNA) and cytokines in primary human keratinocytes. LL-37 inhibited dsRNA-induced production of thymic stromal lymphopoietin (TSLP), CCL5/RANTES, CXCL10/IP-10, and CXCL8/IL-8, which was attributable to interaction between LL-37 and dsRNA, although LL-37 upregulated CXCL8 expression at an earlier time point (8 h). LL-37 inhibited the increase of CXCL10 and CCL5 induced by TNF-α- and/or IFN-γ but enhanced that of CXCL8. LL-37 and Th17 cytokines (IL-17 and IL-22) synergistically upregulated the expression of CXCL8 and IL-6. LL-37 showed the effects above at a high concentration (25 μg/ml, 5.6 μM). We also examined effects of a peptide with a scrambled LL-37 sequence, which has been frequently used as a negative control, and those of another peptide with the reversed LL-37 sequence, activities of which have not been well investigated. Interestingly, the reversed LL-37 had effects similar to LL-37 but the scrambled LL-37 did not. The modulation by LL-37 of the keratinocyte proinflammatory responses induced by cytokine milieus and dsRNA suggests novel roles for LL-37 in skin inflammation such as the promotion of IL17/IL-22/IL-6-associated psoriasis and suppression of TSLP-associated atopic dermatitis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Anti-Inflammatory Agents / immunology
  • Anti-Inflammatory Agents / pharmacology
  • Antimicrobial Cationic Peptides / immunology*
  • Antimicrobial Cationic Peptides / pharmacology
  • Cells, Cultured
  • Chemokine CCL5 / immunology
  • Chemokine CXCL10 / immunology
  • Cytokines / genetics
  • Cytokines / immunology
  • Dermatitis, Atopic / immunology
  • Dermatitis, Atopic / pathology
  • Enzyme-Linked Immunosorbent Assay
  • Humans
  • Interferon-gamma / immunology
  • Interferon-gamma / pharmacology
  • Interleukin-6 / immunology
  • Interleukin-8 / immunology
  • Interleukins / immunology
  • Interleukins / pharmacology
  • Keratinocytes / drug effects*
  • Keratinocytes / immunology*
  • Keratinocytes / pathology
  • Molecular Sequence Data
  • Primary Cell Culture
  • Psoriasis / immunology
  • Psoriasis / pathology
  • RNA, Double-Stranded / genetics
  • RNA, Double-Stranded / metabolism*
  • Recombinant Proteins / immunology
  • Th17 Cells / drug effects
  • Th17 Cells / immunology
  • Time Factors
  • Tumor Necrosis Factor-alpha / immunology
  • Tumor Necrosis Factor-alpha / pharmacology


  • Anti-Inflammatory Agents
  • Antimicrobial Cationic Peptides
  • CCL5 protein, human
  • CXCL10 protein, human
  • CXCL8 protein, human
  • Chemokine CCL5
  • Chemokine CXCL10
  • Cytokines
  • IL6 protein, human
  • Interleukin-6
  • Interleukin-8
  • Interleukins
  • RNA, Double-Stranded
  • Recombinant Proteins
  • Tumor Necrosis Factor-alpha
  • ropocamptide
  • Interferon-gamma
  • thymic stromal lymphopoietin
  • interleukin-22