Usefulness of PBMCs to predict clinical response to corticosteroids in asthmatic patients

Abstract

Background Blood tests are needed to identify steroid resistant (SR) asthmatics early so they can be managed with alternative anti-inflammatory therapy. Objective to assess usefulness of peripheral blood to predict steroid response in asthmatics. Methods 19 asthmatics with FEV1<80% predicted were classified as SR or steroid sensitive (SS) based on change in lung FEV1% following 7 days of oral prednisone. Blood was collected at baseline and 30 days post-prednisone administration (Visit 3). PBMC were cultured for 4h+/−10−7 M dexamethasone (DEX), and cellular response to DEX was determined by real-time PCR based on expression analysis of steroid-regulated genes. Suppression of PHA-induced T cell proliferation by DEX was assessed. Results Prednisone significantly improved FEV1% in SS (mean±SE: 17.5±2.4%) but not SR asthmatics (0.8±2.0%) (p<0.001). Prior to prednisone treatment, MKP-1 (p=0.01) and IL-8 mRNA (p<0.05) levels were significantly higher in PBMC from SR asthmatics. TNF-alpha (p<0.05) and IL-8 fold suppression by DEX (p<0.05) were significantly reduced in SR asthmatics PBMC. The expression of GCR-beta, but not GCR-alpha was significantly elevated in PBMC of SR asthmatics (p=0.01). DEX IC50 for PBMC proliferation was significantly higher for SR asthmatics (p<0.05). These markers no longer differed between groups in PBMC 30 days post-prednisone administration. The composite score of assays at baseline, prior to prednisone, was significantly different between SR and SS asthmatics (p<0.001). Conclusions PBMC from SR asthmatics have higher baseline MKP-1, IL-8, and GCR-beta mRNA levels, a lower GCR-alpha/GCR-beta mRNA ratio, are less responsive to suppression of TNF-alpha and IL-8 by DEX, and require more DEX to suppress T cell proliferation as compared to SS asthmatics.

Cysteine oxidation impairs systemic glucocorticoid responsiveness in children with difficult-to-treat asthma

“…31, 32 Other studies have reported increased expression of the GR beta isoform in airway cells, 33 immune cells 34 and airway tissue 35 of patients with severe asthma that may act as a negative inhibitor and compete for binding of GR consensus. Abnormal histone acetylation has also been reported in patients with severe asthma 36 and COPD 37 and is characterized by a reduction in histone deacetylase 2 expression and activity, which may be induced by oxidative and nitrosative stress.…”

Peripheral blood IRF1 expression as a marker for glucocorticoid sensitivity

“…With prediction in mind, it is important to develop a model system to quantify expression changes that can be evaluated prior to administering the drug to patients. Based on prior research which suggests that gene expression and expression changes in peripheral blood may be reflective of airway tissues, [5, 18, 19], we chose to evaluate expression changes in peripheral blood-derived cells.…”

“…A recent study in patients with idiopathic pulmonary fibrosis found that four gene expression levels quantified in patients’ peripheral blood mononuclear cells (PBMCs) were predictive of poor outcome from the disease [17]. Asthma researchers are beginning to use PBMCs as a surrogate model system for GC response marker discovery [5, 18, 19]. Indeed, Hakonarson et al reported that baseline expression of 11 genes in PBMCs correctly predicted GC response phenotype in 84% of patients in an independent sample, with baseline expression of NFKB1 alone making an accurate prediction in 81.25% of patients [5].…”

Aberrant function of neutrophils in asthma

“…Previous studies about the mechanisms of glucocorticoid insensitivity were focused on decreased binding affinity of the glucocorticoid receptor (GR) and translocation, increased expression of the alternatively-spliced variant GR-β, increased binding of the activated GR receptor to pro-inflammatory transcription factors such as AP-1 and reduced recruitment of histone deacetylase and so on [73,74] . And those in their researches are mostly other cell types, such as peripheral blood mononuclear cells [75][76][77] , alveolar macrophages [78][79][80] , or monocytes [81,82] . These factors also exerted critical effect on the impaired response to glucocorticoid in neutrophilia.…”