Activation of epidermal toll-like receptor 2 enhances tight junction function: implications for atopic dermatitis and skin barrier repair

J Invest Dermatol. 2013 Apr;133(4):988-98. doi: 10.1038/jid.2012.437. Epub 2012 Dec 6.

Abstract

Atopic dermatitis (AD) is characterized by epidermal tight junction (TJ) defects and a propensity for Staphylococcus aureus skin infections. S. aureus is sensed by many pattern recognition receptors, including Toll-like receptor 2 (TLR2). We hypothesized that an effective innate immune response will include skin barrier repair, and that this response is impaired in AD subjects. S. aureus-derived peptidoglycan (PGN) and synthetic TLR2 agonists enhanced TJ barrier and increased expression of TJ proteins, claudin-1 (CLDN1), claudin-23 (CLDN23), occludin, and Zonulae occludens 1 (ZO-1) in primary human keratinocytes. A TLR2 agonist enhanced skin barrier recovery in human epidermis wounded by tape stripping. Tlr2(-/-) mice had a delayed and incomplete barrier recovery following tape stripping. AD subjects had reduced epidermal TLR2 expression as compared with nonatopic subjects, which inversely correlated (r=-0.654, P=0.0004) with transepidermal water loss (TEWL). These observations indicate that TLR2 activation enhances skin barrier in murine and human skin and is an important part of a wound repair response. Reduced epidermal TLR2 expression observed in AD patients may have a role in their incompetent skin barrier.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Neutralizing / pharmacology
  • Bacterial Proteins / pharmacology
  • Dermatitis, Atopic / immunology
  • Dermatitis, Atopic / metabolism*
  • Dermatitis, Atopic / pathology
  • Epidermis / immunology
  • Epidermis / metabolism*
  • Epidermis / pathology
  • Female
  • Foreskin / cytology
  • Humans
  • Keratinocytes / cytology
  • Keratinocytes / immunology
  • Keratinocytes / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Peptidoglycan / pharmacology
  • Permeability
  • RNA, Messenger / metabolism
  • Tight Junctions / immunology
  • Tight Junctions / metabolism*
  • Tight Junctions / pathology
  • Toll-Like Receptor 1 / genetics
  • Toll-Like Receptor 1 / immunology
  • Toll-Like Receptor 1 / metabolism
  • Toll-Like Receptor 2 / agonists
  • Toll-Like Receptor 2 / genetics
  • Toll-Like Receptor 2 / metabolism*
  • Transcutaneous Electric Nerve Stimulation
  • Wound Healing / physiology

Substances

  • Antibodies, Neutralizing
  • Bacterial Proteins
  • Peptidoglycan
  • RNA, Messenger
  • TLR2 protein, human
  • Tlr2 protein, mouse
  • Toll-Like Receptor 1
  • Toll-Like Receptor 2