Analysis of RNA recovery and gene expression in the epidermis using non-invasive tape stripping.

BACKGROUND: The recovery of RNA from the upper epidermis by tape stripping yields variable RNA mass but has not been evaluated for its dependence on anatomical location. Gene expression at different body locations and the origin of RNA recovered by tape stripping have not been investigated. OBJECTIVES: To characterize the recovery of RNA from different anatomical locations by tape stripping; to correlate the recovery of RNA and removal of barrier by tape stripping, as assayed by transepidermal water loss; and to investigate gene expression in the upper epidermis at different body locations. METHODS: Twelve subjects were tape stripped at 15 body locations. RNA mass was evaluated and gene expression assayed. Subjects were tape stripped 4, 8 and 12 times on the upper back and transepidermal water loss and RNA recovery assayed. RESULTS: Ranked by median RNA recovery, the following order was observed: mastoid>forehead>chest>upper back>mid back>cheek>lower back>deltoid>forearm>abdomen>ventral thigh>inner arm>shin>dorsal thigh>lower leg. Expression of the housekeeping gene mRNAs is found to be uniform and reproducible while IL-8 and TNFalpha mRNAs are expressed in different quantities both at different body sites within an individual and between individuals at a specific anatomical site. Data show a significant and high correlation between the number of tapes used to strip a site and transepidermal water loss but no strong correlation between transepidermal water loss and RNA recovery or number of tapes used to strip a site and RNA recovery. CONCLUSIONS: Subjects and anatomical location are shown to be significantly different for the ability to recover RNA by tape stripping. We hypothesize that RNA recovered by tape strip is not derived from corneocytes but from cells associated with the stratum corneum.

An analysis of select pathogenic messages in lesional and non-lesional psoriatic skin using non-invasive tape harvesting.

We report the use of non-invasive tape stripping to sample psoriatic lesional and non-lesional skin in 96 patients. The procedure was well tolerated with any discomfort described as mild; we did not observe any cases of Koebner phenomena at any non-lesional tape-stripped sites. Tape-harvested epidermis was extracted for RNA, which was profiled by semiquantitative reverse transcriptase-PCR. This analysis revealed that mRNAs for tumor necrosis factor alpha, IFNgamma, Krt-16, CD2, IL-23A, IL-12B, and vascular endothelial growth factor are overexpressed in the "average" psoriatic lesion in a majority of patients. In addition, 10 of these patients were biopsied at lesional and non-lesional sites and the expression data compared to tape-stripping data. This comparison shows that five of seven mRNA are more highly expressed in cells captured by tape stripping than biopsy, suggesting that the upper aspect of a lesion contains cells very active in the disease. The tape-harvesting data reveal that approximately 46% of lesions have at least one pathogenic mRNA within non-lesional skin limits. Data demonstrate that tape stripping reveals mRNA markers not detected in biopsy samples and thus the method may be a useful supplement to biopsy.

Use of RT-PCR and DNA microarrays to characterize RNA recovered by non-invasive tape harvesting of normal and inflamed skin.

We describe a non-invasive approach for recovering RNA from the surface of skin via a simple tape stripping procedure that permits a direct quantitative and qualitative assessment of pathologic and physiologic biomarkers. Using semi-quantitative RT-PCR we show that tape-harvested RNA is comparable in quality and utility to RNA recovered by biopsy. It is likely that tape-harvested RNA is derived from epidermal cells residing close to the surface and includes adnexal structures and present data showing that tape and biopsy likely recover different cell populations. We report the successful amplification of tape-harvested RNA for hybridization to DNA microarrays. These experiments showed no significant gene expression level differences between replicate sites on a subject and minimal differences between a male and female subject. We also compared the array generated RNA profiles between normal and 24 h 1% SLS-occluded skin and observed that SLS treatment resulted in statistically significant changes in the expression levels of more than 1,700 genes. These data establish the utility of tape harvesting as a non-invasive method for capturing RNA from human skin and support the hypothesis that tape harvesting is an efficient method for sampling the epidermis and identifying select differentially regulated epidermal biomarkers.