Development and validation of a novel bioassay to determine glucocorticoid sensitivity

Abstract

BackgroundGlucocorticoids (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.ResultsHere 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.ConclusionsThe performance of the novel BLISS bioassay makes it a strong candidate biomarker for clinical application. It now requires validation in a prospective patient cohort.Electronic supplementary materialThe online version of this article (doi:10.1186/s40364-016-0079-y) contains supplementary material, which is available to authorized users.

Disease- and treatment-associated acquired glucocorticoid resistance

“…GC-resistant patients often require higher GC doses for prolonged periods of time in order to efficiently combat chronic inflammation, which likely leads to adverse side effects and may aggravate GC insensitivity ( 16 ). Thus, it is of importance for practitioners to be able to evaluate the GC responsiveness, of individual patients, to permit personalized GC treatment to obtain an optimal therapeutic outcome ( 12 ). Acquired resistance is more difficult to diagnose than generalized resistance, which generally displays a ‘clinical picture’ of GC resistance ( 1 ).…”

“…Acquired resistance is more difficult to diagnose than generalized resistance, which generally displays a ‘clinical picture’ of GC resistance ( 1 ). In terms of generalized GC resistance, no single, standardized method for determining patient sensitivity to GC treatment exists ( 12 ), however, a range of endocrine ( 1 ) (e.g. cortisol awakening rise/response (CAR) or the 24-h urinary-free cortisol (UFC)) and biochemical methods ( 9 ) (dexamethasone suppression test (DST) or the more recent Dex/CRH suppression test) are employed to determine generalized GC resistance.…”

“…cortisol awakening rise/response (CAR) or the 24-h urinary-free cortisol (UFC)) and biochemical methods ( 9 ) (dexamethasone suppression test (DST) or the more recent Dex/CRH suppression test) are employed to determine generalized GC resistance. In contrast, patients with or developing acquired GC resistance are mostly asymptomatic, thus, a range of in depth biochemical diagnostic approaches ( 12 , 20 , 21 ) (e.g. BrdU incorporation lymphocyte steroid sensitivity assay (BLISS) and measuring the GC-responsive gene expression) are required to determine the GC responsiveness of specific tissues and/or cells.…”

“…This stochastic response to GCs within disease groups ( 10 ), is compounded by inter-individual variation in patient sensitivity, as well as tissue-specific intra-individual differences in GC responsiveness ( 1 ). Thus, research is now focussed on developing diagnostic tools for determining GC sensitivity prior to treatment, for the use in personalized therapeutic regimens ( 12 ), which will likely assist in limiting adverse side effects and restrict the development of further GC insensitivity.…”

Novel role for receptor dimerization in post-translational processing and turnover of the GRα

“…GC resistance is an ever increasing threat, with approximately a third of all patients, receiving GC treatment, displaying a degree of insensitivity to treatment 11 , 12 . Specifically, 4–10% of asthma patients, 30% of rheumatoid arthritis patients, almost all chronic obstructive pulmonary disease (COPD) and sepsis patients 11 and 10–30% of untreated acute lymphoblastic leukaemia (ALL) patients 13 experience varying degrees of GC insensitivity.…”