title: Evaluation of high throughput gene expression platforms using a genomic biomarker signature for prediction of skin sensitization.
abstract: BACKGROUND
  Allergic contact dermatitis (ACD) develops upon exposure to certain chemical compounds termed skin sensitizers. To reduce the occurrence of skin sensitizers, chemicals are regularly screened for their capacity to induce sensitization. The recently developed Genomic Allergen Rapid Detection (GARD) assay is an in vitro alternative to animal testing for identification of skin sensitizers, classifying chemicals by evaluating transcriptional levels of a genomic biomarker signature. During assay development and biomarker identification, genome-wide expression analysis was applied using microarrays covering approximately 30,000 transcripts. However, the microarray platform suffers from drawbacks in terms of low sample throughput, high cost per sample and time consuming protocols and is a limiting factor for adaption of GARD into a routine assay for screening of potential sensitizers. With the purpose to simplify assay procedures, improve technical parameters and increase sample throughput, we assessed the performance of three high throughput gene expression platforms--nCounter®, BioMark HD™ and OpenArray®--and correlated their performance metrics against our previously generated microarray data. We measured the levels of 30 transcripts from the GARD biomarker signature across 48 samples. Detection sensitivity, reproducibility, correlations and overall structure of gene expression measurements were compared across platforms.
  
  
  RESULTS
  Gene expression data from all of the evaluated platforms could be used to classify most of the sensitizers from non-sensitizers in the GARD assay. Results also showed high data quality and acceptable reproducibility for all platforms but only medium to poor correlations of expression measurements across platforms. In addition, evaluated platforms were superior to the microarray platform in terms of cost efficiency, simplicity of protocols and sample throughput.
  
  
  CONCLUSIONS
  We evaluated the performance of three non-array based platforms using a limited set of transcripts from the GARD biomarker signature. We demonstrated that it was possible to achieve acceptable discriminatory power in terms of separation between sensitizers and non-sensitizers in the GARD assay while reducing assay costs, simplify assay procedures and increase sample throughput by using an alternative platform, providing a first step towards the goal to prepare GARD for formal validation and adaption of the assay for industrial screening of potential sensitizers.
authors.forename: Andy
authors.initials: A
authors.lastname: Forreryd
authors.forename: Henrik
authors.initials: H
authors.lastname: Johansson
authors.forename: Ann-Sofie
authors.initials: AS
authors.lastname: Albrekt
authors.affiliation: Department of Immunotechnology, Lund University Medicon, Village 406, Scheelevägen 2, 223 81 Lund, Sweden. Malin.lindstedt@immun.lth.se.
authors.forename: Malin
authors.initials: M
authors.lastname: Lindstedt
mesh_terms: D000485:Allergens / Q000633:toxicity*; D051940:B7-2 Antigen / Q000235:genetics / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism*; D045744:Cell Line, Tumor; D017449:Dermatitis, Allergic Contact / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D006801:Humans; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D025341:Principal Component Analysis; D012313:RNA / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D059467:Transcriptome / Q000187:drug effects*
chemical_list: D000485:Allergens; D051940:B7-2 Antigen; D015415:Biomarkers; D012313:RNA