title: Using optical coherence tomography for the longitudinal non-invasive evaluation of epidermal thickness in a murine model of chronic skin inflammation.
abstract: BACKGROUND
  Non-invasive methods are desirable for longitudinal studies examining drug efficacy and disease resolution defined as decreases in epidermal thickness in mouse models of psoriasiform skin disease. This would eliminate the need for either sacrificing animals or collecting serial skin biopsies to evaluate changes in disease progression during an individual study. The quantitation of epidermal thickness using optical coherence tomography (OCT) provides an alternative to traditional histology techniques.
  
  
  METHODS
  Using the KC-Tie2 doxycycline-repressible psoriasiform skin disease mouse model, OCT imaging was completed on diseased back skin of adult KC-Tie2 (n = 3-4) and control (n = 3-4) mice, followed immediately by the surgical excision of the same region for histologic analyses. Animals were then treated with doxycycline to suppress transgene expression and to reverse the skin disease and additional OCT images and tissues were collected 2 and 4 weeks following. Epidermal thickness was measured using OCT and histology.
  
  
  RESULTS
  Optical coherence tomography and histology both demonstrated that KC-Tie2 mice had significantly thicker epidermis (~4-fold; P < 0.0001) than control animals. By 2 weeks following gene repression, decreases in epidermal thickness were observed using both OCT and histology, and were sustained through 4 weeks. Correlation analyses between histology and OCT values at all time points and in all animals revealed high significance (R(2) = 0.78); with correlation being highest in KC-Tie2 mice (R(2) = 0.92) compared to control animals (R(2) = 0.16).
  
  
  CONCLUSIONS
  Non-invasive OCT imaging provided similar values as those collected using standard histologic measures in thick skin of KC-Tie2 mice but became less reliable in thinner control mouse skin, possibly reflecting limitations in resolution of OCT. Future advances in resolution of OCT may improve and allow greater accuracy of epidermal thickness measurements.
authors.affiliation: Department of Dermatology, Case Western Reserve University, Cleveland, Ohio 44106, USA.
authors.forename: Rachel
authors.initials: R
authors.lastname: Silver
authors.forename: Amy
authors.initials: A
authors.lastname: Helms
authors.forename: Wen
authors.initials: W
authors.lastname: Fu
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: Doina
authors.initials: D
authors.lastname: Diaconu
authors.forename: Candace M
authors.initials: CM
authors.lastname: Loyd
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Rollins
authors.forename: Nicole L
authors.initials: NL
authors.lastname: Ward
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001706:Biopsy; D002908:Chronic Disease; D003872:Dermatitis / Q000235:genetics / Q000473:pathology*; D004195:Disease Models, Animal; D004318:Doxycycline / Q000494:pharmacology; D004817:Epidermis / Q000473:pathology*; D015870:Gene Expression / Q000187:drug effects; D015603:Keratinocytes / Q000473:pathology; D008137:Longitudinal Studies; D051379:Mice; D008817:Mice, Mutant Strains; D011565:Psoriasis / Q000235:genetics / Q000473:pathology*; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics; D042787:Receptor, TIE-2; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D041623:Tomography, Optical Coherence / Q000379:methods* / Q000592:standards; D019076:Transgenes / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D020794:Receptor Protein-Tyrosine Kinases; D042787:Receptor, TIE-2; C079086:Tek protein, mouse; D004318:Doxycycline
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