title: Development and validation of a novel bioassay to determine glucocorticoid sensitivity.
abstract: BACKGROUND
  Glucocorticoids (GCs) remain the first line treatment for almost all non-infectious inflammatory diseases, ranging from acute asthma to rheumatoid arthritis. However, across all conditions, patients have a variable response to GCs with approximately 30% being non-responders. This group of GC resistant patients is typically exposed to high-dose GCs and their side-effects before more appropriate immunotherapy is instituted. Hence, there is a pressing clinical need for a predictive biomarker of GC responsiveness. The availability of such a tool would also enable patient stratification for the conduct of smart clinical trials in GC resistance. Lymphocyte GC sensitivity has been shown to be closely associated with clinical GC sensitivity in a number of inflammatory diseases. However, the method for determining in vitro GC response is not standardized and requires the use of specialist equipment, including a radioisotope to quantify cellular proliferation, making it challenging to translate into clinical practice.
  
  
  RESULTS
  Here we describe the optimization and validation of a novel non-radioactive in vitro bioassay based on measuring cellular proliferation by incorporation of bromodeoxyuridine (BrdU), termed the BrdU incorporation in lymphocyte steroid sensitivity assay (BLISS). In comparison to the current gold standard lymphocyte GC sensitivity assay in 101 healthy control samples, BLISS has an area under receiver operating characteristic of 0.82 and a sensitivity of 83% for correctly identifying GC resistant subjects.
  
  
  CONCLUSIONS
  The performance of the novel BLISS bioassay makes it a strong candidate biomarker for clinical application. It now requires validation in a prospective patient cohort.
authors.affiliation: School of Clinical Sciences, Medical Sciences Building, University of Bristol, Bristol, BS9 1TD UK.|National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, University Hospitals Bristol NHS Foundation Trust and University of Bristol, Bristol, UK.
authors.forename: Emily L
authors.initials: EL
authors.lastname: Williams
authors.affiliation: School of Clinical Sciences, Medical Sciences Building, University of Bristol, Bristol, BS9 1TD UK.|National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, University Hospitals Bristol NHS Foundation Trust and University of Bristol, Bristol, UK.
authors.forename: Madeleine L
authors.initials: ML
authors.lastname: Stimpson
authors.affiliation: School of Clinical Sciences, Medical Sciences Building, University of Bristol, Bristol, BS9 1TD UK.|Department of Liver Medicine, University Hospitals Bristol NHS Foundation Trust, Bristol, BS2 8HW UK.
authors.forename: Peter L
authors.initials: PL
authors.lastname: Collins
authors.affiliation: Biostatistics, Bioinformatics and Biomarkers research group, Plymouth University, N15 Plymouth Science Park, Plymouth, PL6 8BX UK.
authors.forename: Doyo G
authors.initials: DG
authors.lastname: Enki
authors.affiliation: Department of Liver Medicine, University Hospitals Bristol NHS Foundation Trust, Bristol, BS2 8HW UK.
authors.forename: Ashish
authors.initials: A
authors.lastname: Sinha
authors.affiliation: School of Clinical Sciences, Medical Sciences Building, University of Bristol, Bristol, BS9 1TD UK.|National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, University Hospitals Bristol NHS Foundation Trust and University of Bristol, Bristol, UK.
authors.forename: Richard W
authors.initials: RW
authors.lastname: Lee
authors.affiliation: School of Clinical Sciences, Medical Sciences Building, University of Bristol, Bristol, BS9 1TD UK.|Institute of Translational and Stratified Medicine, Plymouth University Peninsula Schools of Medicine and Dentistry, John Bull Building, Plymouth, PL6 8BU UK.|South West Liver Unit, Plymouth Hospitals NHS Trust, Plymouth, UK.
authors.forename: Ashwin D
authors.initials: AD
authors.lastname: Dhanda
keywords: Biomarker; Bromodeoxyuridine; Glucocorticoid sensitivity; Proliferation