Human hair follicle epithelium has an antimicrobial defence system that includes the inducible antimicrobial peptide psoriasin (S100A7) and RNase 7

• Published in: British journal of dermatology (1951) Vol. 161; no. 1; pp. 78 - 89
• Main Authors: Reithmayer, K., Meyer, K.C., Kleditzsch, P., Tiede, S., Uppalapati, S.K., Gläser, R., Harder, J., Schröder, J.-M., Paus, R.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.07.2009; Wiley-Blackwell
• Subjects: Aged; antimicrobial peptides; Biological and medical sciences; Calcium-Binding Proteins - metabolism; Dermatology; Epithelium - immunology; Epithelium - metabolism; Female; Hair Follicle - drug effects; Hair Follicle - immunology; Hair Follicle - metabolism; human hair follicle; Humans; Immunohistochemistry; Interferon-gamma - pharmacology; Lipopolysaccharides - pharmacology; Medical sciences; Middle Aged; psoriasin; Reverse Transcriptase Polymerase Chain Reaction; Ribonucleases - metabolism; RNA, Messenger - analysis; S100 Calcium Binding Protein A7; S100 Proteins; S100A7; Toll-Like Receptor 4 - metabolism; Up-Regulation - drug effects; Human; Peptides; Dermatology; human hair follicle, psoriasin; Hair follicle; Epithelium; Antimicrobial agent; antimicrobial peptides; S100A7
• ISSN: 0007-0963; 1365-2133
• DOI: 10.1111/j.1365-2133.2009.09154.x

Summary Background  Hair follicle (HF) ostia represent a potential port of microbial entry into the skin. However, they rarely show clinical signs of infection. This suggests the presence of local, efficient, antimicrobial defence systems, which may include antimicrobial peptides (AMPs). Objectives  We determined the presence and distribution of the major AMPs, RNase 7 and psoriasin (S100A7), in human scalp HFs. We investigated whether HF production of these AMPs was induced by prototypic microbial products and proinflammatory cytokines, i.e. interferon (IFN)‐γ. Finally, we examined whether the classical pathways for AMP induction, such as toll‐like receptor (TLR)4 and TLR5 expression, are present in human HFs and up‐regulated after stimulation with bacterium‐associated ligands. Methods  Cryosections from fresh or organ‐cultured full‐thickness normal human scalp skin treated with lipopolysaccharide (LPS), flagellin, protein A, lipoteichoic acid (LTA) or IFN‐γ were stained for psoriasin and RNase 7 immunoreactivity (IR) as well as for TLR4 and TLR5. In addition, outer root sheath cell culture and semiquantitative analysis of mRNA expression levels of RNase 7 and psoriasin were performed. Results  Specific RNase 7 IR was present throughout the entire HF outer root sheath in situ and in cell culture, whereas psoriasin IR was present only in the most distal compartment and not detectable in cultured ORS cells. Upon treatment with Gram‐positive (LTA, protein A) or Gram‐negative bacterial (LPS, flagellin) cell wall components, or with the cytokine IFN‐γ, the IR of both psoriasin and RNase 7 was modified. TLR4 and TLR5 IR was detected in the normal HF epithelium and were upregulated after treatment with their respective ligand. The mRNA analysis confirmed the immunohistochemistry results. Conclusions  This pilot study suggests that normal human scalp HF epithelium possesses a functional antimicrobial defence system, which includes the AMPs RNase 7 and psoriasin, and TLRs, and that these are induced by classical microbial products.