title: Tandem repeated irritation in aged skin induces distinct barrier perturbation and cytokine profile in vivo.
abstract: BACKGROUND
  The barrier perturbation pattern and molecular markers of inflammation upon tandem repeated irritation in chronologically aged skin have not been previously studied.
  
  
  OBJECTIVE
  We aimed to investigate the barrier impairment kinetic and in vivo cytokine profile following sequential irritation with sodium lauryl sulfate (SLS) and undiluted toluene (Tol) in aged compared with young skin.
  
  
  METHODS
  Four fields on the volar forearm of healthy aged and young volunteers (median age, respectively, 63.9 and 32.6 years) were sequentially exposed to 0.5% SLS and undiluted toluene in a controlled tandem repeated irritation test; an adjacent nontreated field served as control. The permeability barrier function was monitored by repeated measurements of transepidermal water loss (TEWL), capacitance and erythema every 24 h up to 96 h. The stratum corneum cytokines were harvested by sequential tape stripping and quantified by multiplex bead array and enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Compared with young skin, aged skin was characterized by delayed and/or less pronounced alterations in the visual irritation score, TEWL, chromametry a*-value and capacitance, assessed by the respective Δ-values for each parameter and monitoring time point. In both groups, exposure to SLS/SLS, SLS/Tol and Tol/SLS resulted in decreased interleukin (IL)-1α levels, whereas the application of Tol/Tol induced an increase in IL-1α. Furthermore, decreased IL-1 receptor antagonist (IL-1RA) levels and a lower IL-1RA/IL-1α ratio were found following repeated exposure to the irritants.
  
  
  CONCLUSIONS
  Our results provide evidence for selective alterations in the cytokine profile and distinct barrier impairment kinetic following tandem repeated irritation with SLS and Tol in aged compared with young skin in vivo.
authors.affiliation: Department of Dermatology, University of Lübeck, Germany. irena.angelova-fischer@uk-sh.de
authors.forename: I
authors.initials: I
authors.lastname: Angelova-Fischer
authors.forename: V
authors.initials: V
authors.lastname: Becker
authors.forename: T W
authors.initials: TW
authors.lastname: Fischer
authors.forename: D
authors.initials: D
authors.lastname: Zillikens
authors.forename: W
authors.initials: W
authors.lastname: Wigger-Alberti
authors.forename: S
authors.initials: S
authors.lastname: Kezic
mesh_terms: D000328:Adult; D000368:Aged; D001834:Body Water / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism*; D017453:Dermatitis, Irritant / Q000209:etiology* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D004817:Epidermis / Q000187:drug effects* / Q000378:metabolism; D004890:Erythema / Q000139:chemically induced; D005260:Female; D006801:Humans; D053582:Interleukin-1alpha / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D053573:Receptors, Interleukin-1 Type I / Q000037:antagonists & inhibitors / Q000378:metabolism; D012867:Skin / Q000187:drug effects*; D015595:Skin Aging / Q000187:drug effects*; D012967:Sodium Dodecyl Sulfate / Q000633:toxicity*; D012997:Solvents / Q000633:toxicity; D013501:Surface-Active Agents / Q000633:toxicity*; D014050:Toluene / Q000633:toxicity; D055815:Young Adult
chemical_list: D016207:Cytokines; D053582:Interleukin-1alpha; D053573:Receptors, Interleukin-1 Type I; D012997:Solvents; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D014050:Toluene