Corticosteroid-resistant Research Articles

The association of FKBP5 polymorphism with asthma susceptibility in asthmatic patients.

Inhaled corticosteroids are the most effective controllers of asthma, although asthmatics vary in their response. FKBP51 is a major component of the glucocorticoid receptor which regulates its responses to corticosteroids. Therefore, the present study aims to identify the role of FKBP5 gene polymorphism in asthma susceptibility and corticosteroid resistance. DNA was extracted from the blood of 68 asthmatic and 40 control subjects. FKBP5 gene fragments were amplified by PCR and sequenced by the Sanger method. The sequencing results were aligned by mapping on the reference sequences of National center of Biotechnology Information (NCBI) and single nucleotide polymorphisms (SNPs) which were checked. Finally, the genotype, allele frequency and odds ratio (OR) were calculated. The FKBP5 fragment sequencing revealed the presence of rs1360780 and one novel SNP found in 17 samples taken from asthmatic patients as compared to db SNP data in the NCBI database. The FKBP5 variant (rs1360780) indicated that the allele frequency of risk allele T was 41.18% in patients and 20% in control group members p<0.001 and OR=2.8 when compared to a wild C allele frequency of 58.82% in patients and 64% in the control group members. The novel SNP FKBP5 was compared to the SNP database in the NCBI database in which wild T allele was substituted with G. The novel SNP was submitted to the ClinVar Submission Portal at NCBI with accession number: rs1581842283 and confirmed an asthma susceptibility risk factor with allele G frequency of 11.76% in asthmatics and 2.5% in the control group members (OR=5.2, p<0.05), as compared to a wild T allele frequency of 88.24% in asthmatics and 97.5% in the control group members. The risk allele T of rs1360780 and the novel SNP rs1581842283 risk allele G predict asthma susceptibility but show no association with corticosteroid resistant.

Responsiveness to oral prednisolone in severe asthma is related to the degree of eosinophilic airway inflammation.

Patients with severe asthma appear relatively corticosteroid resistant. Corticosteroid responsiveness is closely related to the degree of eosinophilic airway inflammation. The extent to which eosinophilic airway inflammation in severe asthma responds to treatment with systemic corticosteroids is not clear. To relate the physiological and inflammatory response to systemic corticosteroids in asthma to disease severity and the baseline extent of eosinophilic inflammation. Patients with mild/moderate and severe asthma were investigated before and after 2 weeks of oral prednisolone (Clintrials.gov NCT00331058 and NCT00327197). We pooled the results from two studies with common protocols. The US study contained two independent centres and the UK one independent centre. The effect of oral corticosteroids on FEV1 , Pc20, airway inflammation and serum cytokines was investigated. Baseline measurements were compared with healthy subjects. Thirty-two mild/moderate asthmatics, 50 severe asthmatics and 35 healthy subjects took part. At baseline, both groups of asthmatics had a lower FEV1 and Pc20 and increased eosinophilic inflammation compared to healthy subjects. The severe group had a lower FEV1 and more eosinophilic inflammation compared to mild/moderate asthmatics. Oral prednisolone caused a similar degree of suppression of eosinophilic inflammation in all compartments in both groups of asthmatics. There were small improvements in FEV1 and Pc20 for both mild/ moderate and severe asthmatics with a correlation between the baseline eosinophilic inflammation and the change in FEV1 . There was a ~50% reduction in the serum concentration of CXCL10 (IP-10), CCL22 (MDC), CCL17 (TARC), CCL-2 (MCP-1) and CCL-13 (MCP-4) in both asthma groups after oral corticosteroids. Disease severity does not influence the response to systemic corticosteroids. The study does not therefore support the concept that severe asthma is associated with corticosteroid resistance. Only baseline eosinophilic inflammation was associated with the physiological response to corticosteroids, confirming the importance of measuring eosinophilic inflammation to guide corticosteroid use.

The Bronchial Microbiome and Asthma Phenotypes

The Bronchial Microbiome and Asthma Phenotypes

The Effects of Airway Microbiome on Corticosteroid Responsiveness in Asthma

The role of airway microbiome in corticosteroid response in asthma is unknown. To examine airway microbiome composition in patients with corticosteroid-resistant (CR) asthma and compare it with patients with corticosteroid-sensitive (CS) asthma and normal control subjects and explore whether bacteria in the airways of subjects with asthma may direct alterations in cellular responses to corticosteroids. 16S rRNA gene sequencing was performed on bronchoalveolar lavage (BAL) samples of 39 subjects with asthma and 12 healthy control subjects. In subjects with asthma, corticosteroid responsiveness was characterized, BAL macrophages were stimulated with pathogenic versus commensal microorganisms, and analyzed by real-time polymerase chain reaction for the expression of corticosteroid-regulated genes and cellular p38 mitogen-activated protein kinase (MAPK) activation. Of the 39 subjects with asthma, 29 were CR and 10 were CS. BAL microbiome from subjects with CR and CS asthma did not differ in richness, evenness, diversity, and community composition at the phylum level, but did differ at the genus level, with distinct genus expansions in 14 subjects with CR asthma. Preincubation of asthmatic airway macrophages with Haemophilus parainfluenzae, a uniquely expanded potential pathogen found only in CR asthma airways, resulted in p38 MAPK activation, increased IL-8 (P < 0.01), mitogen-activated kinase phosphatase 1 mRNA (P < 0.01) expression, and inhibition of corticosteroid responses (P < 0.05). This was not observed after exposure to commensal bacterium Prevotella melaninogenica. Inhibition of transforming growth factor-β-associated kinase-1 (TAK1), upstream activator of MAPK, but not p38 MAPK restored cellular sensitivity to corticosteroids. A subset of subjects with CR asthma demonstrates airway expansion of specific gram-negative bacteria, which trigger TAK1/MAPK activation and induce corticosteroid resistance. TAK1 inhibition restored cellular sensitivity to corticosteroids.

Gene Expression Changes Associated with Resistance to Intravenous Corticosteroid Therapy in Children with Severe Ulcerative Colitis

Background and AimsMicroarray analysis of RNA expression allows gross examination of pathways operative in inflammation. We aimed to determine whether genes expressed in whole blood early following initiation of intravenous corticosteroid treatment can be associated with response.MethodsFrom a prospectively accrued cohort of 128 pediatric patients hospitalized for intravenous corticosteroid treatment of severe UC, we selected for analysis 20 corticosteroid responsive (hospital discharge or PUCAI ≤45 by day 5) and 20 corticosteroid resistant patients (need for second line medical therapy or colectomy, or PUCAI >45 by day 5). Total RNA was extracted from blood samples collected on day 3 of intravenous corticosteroid therapy. The eluted transcriptomes were quantified on Affymetrix Human Gene 1.0 ST arrays. The data was analysed by the local-pooled error method for discovery of differential gene expression and false discovery rate correction was applied to adjust for multiple comparisons.ResultsA total of 41 genes differentially expressed between responders and non-responders were detected with statistical significance. Two of these genes, CEACAM1 and MMP8, possibly inhibited by methylprednisolone through IL8, were both found to be over-expressed in non-responsive patients. ABCC4 (MRP4) as a member of the multi-drug resistance superfamily was a novel candidate gene for corticosteroid resistance. The expression pattern of a cluster of 10 genes selected from the 41 significant hits were able to classify the patients with 80% sensitivity and 80% specificity.ConclusionsElevated expression of several genes involved in inflammatory pathways was associated with resistance to intravenous corticosteroid therapy early in the course of treatment. Gene expression profiles may be useful to classify resistance to intravenous corticosteroids in children with severe UC and assist with clinical management decisions.

Corticosteroid-resistant asthma is associated with classical antimicrobial activation of airway macrophages

The cause of corticosteroid-resistant (CR) asthma is unknown. We sought to perform gene microarray analyses by using bronchoalveolar lavage (BAL) cells from well-characterized subjects with CR asthma and subject with corticosteroid-sensitive (CS) asthma to elucidate the differential expression of genes that contribute to the development of corticosteroid resistance. The patients were characterized as having CR or CS asthma based on FEV(1) percent predicted improvement after a 1-week course of oral prednisone. Expression of selected gene targets was verified by means of real-time PCR and ELISA. Microarray analyses demonstrated significantly higher levels (>3-fold increase, P < .05) of transcripts for TNF-alpha, IL-1 alpha, IL-1 beta, IL-6, CXCL1, CXCL2, CXCL3, CXCL8 (IL-8), CCL3, CCL4, and CCL20 in BAL cells of subjects with CR asthma. These findings, confirmed by means of RT-PCR in additional BAL samples, were consistent with classical macrophage activation by bacterial products. In contrast, markers of alternatively activated macrophages, arginase I and CCL24, were decreased. Genes associated with activation of the LPS signaling pathway (early growth response 1, dual-specificity phosphatase 2, molecule possessing ankyrin repeats induced by LPS, and TNF-alpha-induced protein 3) were significantly increased in BAL samples from subjects with CR asthma (P < .05). These patients had significantly higher amounts (1444.0 +/- 457.3 pg/mg total protein) of LPS in BAL fluid than seen in subjects with CS asthma (270.5 +/- 216.0 pg, P < .05), as detected by using the LAL assay and confirmed by means of gas chromatographic/mass spectrometric analysis. Prolonged exposure to LPS induced functional steroid resistance to dexamethasone in normal human monocytes, as demonstrated by persistently increased IL-6 levels in the presence of dexamethasone. Classical macrophage activation and induction of LPS signaling pathways along with high endotoxin levels detected in BAL fluid from subjects with CR asthma suggest that LPS exposure might contribute to CR asthma.

Corticosteroid Therapy in the Age of Infliximab: Acute and 1-Year Outcomes in Newly Diagnosed Children With Crohn’s Disease

The aim of this study was to describe 3-month and 1-year outcomes of children with Crohn's disease (CD) treated with corticosteroids within 30 days of diagnosis, with particular emphasis on the influence of infliximab on these outcomes. We also aimed to determine whether there are clinical or laboratory characteristics associated with corticosteroid therapy outcomes. Data from 109 children were drawn from a multicenter observational registry that was started in 2002. Clinical characteristics and data on corticosteroid and other therapies were recorded prospectively. Corticosteroid therapy outcomes at 3 months were defined as complete acute response, partial response, or corticosteroid resistance. At 1 year, corticosteroid responsiveness, dependence, and surgical rates were determined. Infliximab's influence on short- and long-term outcomes also was investigated. At 3 months, 65 of 109 (60%) patients had a complete acute response to corticosteroids, 26 (24%) had a partial response, and 18 (17%) were corticosteroid resistant. At 1 year, 61% were corticosteroid responsive, 31% were corticosteroid dependent, and 8% required surgery. Irrespective of the duration of corticosteroid treatment, 16 of 24 of corticosteroid-dependent/resistant patients rapidly discontinued corticosteroids after starting infliximab. No clinical or laboratory characteristics at diagnosis predicted short-term outcome. Growth impairment at diagnosis increased risk for corticosteroid dependence or surgery at 1 year. At 3 months, 84% of children had a complete or partial response to corticosteroids. However, despite concomitant immunomodulators, at 1 year 31% were corticosteroid dependent and 8% required surgery. Infliximab improves outcomes of corticosteroid-dependent/resistant patients because the duration of corticosteroid use can be controlled by initiating treatment with infliximab.

Corticosteroid Resistant (CR) Asthma Is Associated with Classical Activation Of Airway Macrophages and Exposure To Lipopolysaccharide (LPS)

RATIONALE: Microbial products like LPS affect the phenotype and function of airway macrophages and have been shown to cause severe asthma. We studied airway macrophages from CR and corticosteroid sensitive (CS) asthmatics for expression of pro-inflammatory cytokines, chemokines and exposure to LPS to further identify mechanisms of steroid resistance.

Molecular mechanisms of corticosteroids in allergic diseases.

Molecular mechanisms of corticosteroids in allergic diseases.

In vivo resistance to corticosteroids in bronchial asthma is associated with enhanced phosyphorylation of JUN N-terminal kinase and failure of prednisolone to inhibit JUN N-terminal kinase phosphorylation

Background: Corticosteroid-resistant (CR) asthma is associated with increased in vitro activity of the proinflammatory transcription factor activating peptide (AP)-1 in PBMCs resulting from increased c-FOS synthesis. Increased AP-1 may sequester the glucocorticoid receptor to produce a CR state. Using the tuberculin-induced inflammatory responses in the skin, we have previously demonstrated that a therapeutically effective dose of prednisolone suppressed T-cell, macrophage, and eosinophil infiltration into purified protein derivative–induced lesional skin of corticosteroid-sensitive (CS), but not CR, individuals. Objective: Skin biopsy specimens from a tuberculin-induced model of dermal inflammation have been evaluated for the effect of corticosteroids in regulating components of AP-1 in vivo. Methods: Immunohistochemical analysis of the tuberculin-mediated cutaneous response has been performed on 9 subjects with CS asthma and 6 subjects with CR asthma for the regulatory components of AP-1 before and after 9 days of either 40 mg prednisolone or placebo. Results: Significantly greater expression of c-FOS, phosphorylated c-JUN, and phosphorylated JUN N-terminal kinase (JNK) protein has been identified in CR than in CS subjects. Corticosteroids suppressed phosphorylation of c-JUN and JNK in the CS Group ( P = .004 for both) but enhanced phosphorylation of c-JUN and JNK in the CR group ( P = .031 for both). Conclusion: Resistance to corticosteroids in asthmatic subjects may be caused, at least in part, by failure to suppress JNK phosphorylation, leading to failure to suppress c-JUN N-phosphorylation. Increased JNK may be one of the mechanisms central to the mechanism of CR asthma. (J Allergy Clin Immunol 1999;104:565-74.)

Corticosteroid-resistant bronchial asthma is associated with increased c-fos expression in monocytes and T lymphocytes.

Unstimulated peripheral blood mononuclear cells (PBMCs) from corticosteroid-resistant (CR) but not corticosteroid-sensitive (CS) asthmatics demonstrate increased activating peptide-1 (AP-1)- and decreased glucocorticoid receptor (GR)-DNA binding. We test whether these abnormalities are associated with excessive generation of c-fos, the inducible component of AP-1. The c-fos transcription rate, mRNA and protein levels, and GR-DNA binding were quantitated in PBMCs, T cells, and monocytes from CS, CR, and nonasthmatic subjects. There was a 1.7-, 4.2-, and 2.3-fold greater increase in the baseline c-fos transcription rate, mRNA expression, and protein levels, respectively, in PBMCs derived from CR compared with CS patients. At optimal stimulation with PMA, there was a 5.7-, 3.4-, and 2-fold greater increase in the c-fos transcription rate, mRNA accumulation, and protein levels, respectively, in CR compared with CS PBMCs. These abnormalities were detected in both the T cell and monocyte subpopulations. PMA stimulation converted PBMCs from a CS to a CR phenotype and was associated with direct interaction between c-Fos and the GR. Pretreatment of PBMCs from CR patients with c-fos antisense oligonucleotides enhanced GR-DNA binding activity in CR PBMCs stimulated with dexamethasone. We suggest that increased c-fos synthesis provides a major mechanism for the increased AP-1- and decreased GR- DNA binding seen in CR asthma.

Mechanisms of corticosteroid resistance in asthmatic patients.

Corticosteroid-resistant (CR) asthma is associated with disease chronicity, a more frequent family history of asthma and impaired in vitro and in vivo responsiveness of peripheral blood mononuclear cells to the suppressive effects of glucocorticoids. CR asthma is associated with normal suppression of the hypothalamic-pituitary-adrenal axis and of biochemical indices of bone turnover by dexamethasone, indicating that the phenomenon of glucocorticoid resistance is specific to inflammatory leukocytes and that these patients are equally at risk of developing 'cushingoid' side effects. We have been unable to detect altered bioavailability of administered glucocorticoid, impaired ligand binding or nuclear translocation of the activated glucocorticoid receptor (GR) complex or structural abnormalities of the GR cDNA in our population of CR asthmatics. We have recently demonstrated that CR asthma is associated with decreased GR and increased AP-1 (Fos; Jun) DNA binding in peripheral blood mononuclear cells as compared to corticosteroid-sensitive asthma. These results highlight the central role of the AP-1/GR interactions in glucocorticoid action in CR asthma.

Effects of prednisolone on bone turnover in patients with corticosteroid resistant asthma

Although corticosteroid resistant (CR) bronchial asthma is associated with impaired in vitro an din vivo glucocorticoid (GC) responsiveness in mononuclear cell function, it is not known whether this is a cell specific phenomenon or whether these patients are at risk of glucocorticoid side-effects as corticosteroid-sensitive (CS) subjects. In order to address this question we have examined the effects of GCs on biochemical indices of bone turnover in vivo. Six CS and six CR subjects received prednisolone 40 mg orally at 09.00 daily for 5 days. At 08.30 on day 1 and day 6 a fasting blood was taken for estimation of serum osteocalcin, tartrate resistant acid phosphatase (TRAP) and alkaline phosphatase (ALP; total and bone isoenzyme), and a urine sample taken for estimation of free deoxy-pyridinoline crosslinks. TRAP and ALP were measured by a colorimetric method and osteocalcin and deoxy-pyridinoline crosslinks by ELISA. Serum osteocalcin (nmol/L) decreased from 1.39 +/- 0.09 (mean +/- SEM) to 1.14 +/- 0.07 (P = 0.023) and from 1.19 +/- 0.05 to 0.96 +/- 0.1 (P = 0.037) in the CS and CR groups respectively. There was no difference between baseline and post-treatment levels in either group. Serum total ALP (units/L) decreased from 178 +/- 7 to 168 +/- 4 (P = 0.02) and from 195 +/- 22 to 175 +/- 16 (P = 0.04) in the CS and CR groups, respectively. There was no difference between baseline and post-treatment levels in either group. There was no significant elevation of deoxy-pyridinoline crosslinks or TRAP and no suppression of bone ALP in either group. We suggest that CR asthmatics may be equally at risk from the metabolic side-effects of glucocorticoids.

Mononuclear Cells in Corticosteroid-resistant Asthma

The airflow obstruction of the majority of patients with chronic and severe bronchial asthma will improve following treatment with glucocorticoids (OCs), but despite their clinical efficacy their mechanism of action in bronchial asthma is unknown. One way in which the mechanisms can be explored is to study a subgroup of patients in whom systemic or inhaled treatment with OCs, even when given in large doses, does not lead to any improve­ ment in airflow obstruction. The asthma in such patients is usu­ ally severe, and they are seriously disabled for long periods of time. We have defined corticosteroid-resistant (CR) asthma as an improvement in FEV, of less than 151170 after a 14-d course of 40 mg of prednisolone, whereas corticosteroid-sensitive (CS) asthma has been defined as an improvement of greater than 30% in FEV, after a similar course of prednisolone (1). CR asthma is associated with disease chronicity and a more frequent family history of asthma (2). Furthermore, there is increasing evidence for impaired in vitro and in vivo responsiveness of peripheral blood mononuclear cells (PBMCs) to the suppressive effects of glucocorticoids in these subjects. MONONUClEAR CELL DEFECTS IN CR ASTHMA In an ex vivo study, complement receptor expression on mono­ cytes from CS subjects was reduced after 1 wk of treatment with 20 mg oral prednisolone daily compared with cellsfrom untreated patients (3). The reduction in complement receptor expression induced by prednisolone was not observed in the monocytes of those patients exhibiting CR asthma. This work was extended by Poznansky and colleagues (4), who demonstrated that lO-8 to 109

Hypothalamic-pituitary-adrenal axis in corticosteroid-resistant bronchial asthma.

We have examined whether the lack of clinical response to corticosteroids seen in corticosteroid resistant (CR) bronchial asthma is reflected in abnormalities of endogenous cortisol secretion and in the sensitivity of the hypothalamic-pituitary-adrenal (HPA) axis in CR subjects by using a modification of the standard dexamethasone suppression test (DST) in response to 0.25 and 1 mg oral dexamethasone. Five corticosteroid-sensitive (CS) and five CR asthmatic subjects were studied on two occasions 1 mo apart. In the first limb of the study subjects received 0.25 mg of oral dexamethasone, and in the second limb they received 1 mg. Urinary cortisol was measured by fluorimetry after extraction, and plasma cortisol and adrenocorticotropic hormone (ACTH) concentrations were estimated by enzyme-linked immunosorbent assay (ELISA) and immunoradiometric assays, respectively. On Day 1, a 24-h urine sample was collected for estimation of urinary free cortisol. On Day 2, a fasting blood sample was taken at 9:00 A.M. for estimation of plasma cortisol and ACTH. At 11:00 P.M., 0.25 mg (1 mg) of dexamethasone was taken orally by each subject. On Day 3, blood was taken at 9:00 A.M. and 3:00 P.M. for similar estimations. The levels of urinary free cortisol (nmol/24 h) and predose plasma ACTH (ng/L) and cortisol (nmol/L) were 199 +/- 42, 27.4 +/- 5.7, and 300 +/- 48 (mean +/- SEM), respectively, in the CS group, and 210 +/- 74, 23.4 +/- 6.7, and 263 +/- 32 (mean +/- SEM), respectively, in the CR group (p > 0.05 for all comparisons). Plasma ACTH and cortisol concentrations were not significantly suppressed in either group after 0.25 mg dexamethasone, but were equally suppressed in both groups to undetectable levels by 1 mg dexamethasone. We conclude that CR asthma is not reflected in an altered secretory rate of endogenous cortisol or in an altered sensitivity of the HPA axis to dexamethasone suppression.

529 Increased c-fos synthesis in mononuclear cells from patients with corticosteroid resistent asthma

529 Increased c-fos synthesis in mononuclear cells from patients with corticosteroid resistent asthma

Chemical mutational analysis of the human glucocorticoid receptor cDNA in glucocorticoid-resistant bronchial asthma.

Corticosteroid-resistant (CR) asthma is not caused by altered bioavailability of the administered drug, altered ligand-binding characteristics, or altered nuclear translocation of the activated human glucocorticoid receptor (hGR) complex. We have tested the hypothesis that CR asthma results from a consistent polymorphism in the functionally diverse hGR cDNA using the sensitive screening technique of polymerase chain reaction (PCR) amplification and chemical mutational analysis. Total RNA was extracted from peripheral blood monocytes derived from six corticosteroid-sensitive (CS) and six CR asthmatic subjects. The RNA was reverse transcribed, and overlapping hGR cDNA fragments were amplified by nested PCR. Double-stranded hGR cDNA fragments were hybridized to corresponding 32P-5'-labeled wild-type fragments, chemically modified with osmium and hydroxylamine, and cleaved with piperidine. The resultant cleaved strands were detected by autoradiography. As controls, single base pair mutated hGR cDNA fragments sensitive to hydroxylamine and osmium modification were used. Using this technique, we did not detect any base pair mismatch between the six CS and six CR patients and the corresponding wild-type hGR, despite a 100% detection of control mutations. We conclude that the defect in CR asthma does not lie in the structure of the hGR.

Vincristine in steroid-resistant nephrotic syndrome

The therapeutic response to vincristine was examined in seven children (aged 2-15 years) with corticosteroid-resistant (CR) nephrotic syndrome (NS) with focal and segmental glomerulosclerosis (FGS). Five were also resistant to cyclophosphamide. Vincristine was given weekly (1.5 mg/m2 intravenously) for 8 weeks. Simultaneously, prednisone (60 mg/m2 per day, orally) was given for 4 weeks and then gradually tapered. Two of these patients had a complete and stable remission; in five no benefit was observed. It was not possible to identify any characteristics to predict the response to vincristine. Although there is a case for trying vincristine therapy in CR NS with FGS, the results of this study are not encouraging and a better understanding of its action and indications is necessary.

Glucocorticoid Receptor Characteristics in Monocytes of Patients with Corticosteroid-Resistant Bronchial Asthma

The mechanism of corticosteroid resistance in bronchial asthma has been studied by determining the rank order of potency for different corticosteroids in inhibiting the generation of a 3 kD molecule from peripheral blood monocytes isolated from corticosteroid-sensitive (CS) and corticosteroid-resistant (CR) asthmatic subjects, which augments leukotriene B4 (LTB4) generation by human neutrophils (PMN) stimulated by calcium ionophore. In addition, binding studies with (3H) dexamethasone have been performed to determine the dissociation constant (Kd) and receptor numbers (Ro) in the monocytes of these two groups of subjects. The concentration of corticosteroid producing 50% inhibition (IC50) was 600 nM, 70 nM, and 0.5 nM for hydrocortisone, methylprednisolone, and dexamethasone, respectively, in monocytes from CS individuals. There was only weak inhibition of the generation of enhancing activity by the corticosteroids in the CR asthmatic individuals. The dexamethasone Kd was 2.45 +/- 0.58 nM (mean +/- SEM, n = 6) in the CS group and 1.6 +/- 0.35 nM (mean +/- SEM, n = 6) in the CR group of patients (p = 0.14). The Ro in the CS group was 3,605 +/- 984 binding sites per nucleus (mean +/- SEM, n = 6) and 4,757 +/- 692 binding sites per nucleus (mean +/- SEM, n = 6) in the CR group (p = 0.23). These findings indicate that corticosteroid resistance in bronchial asthma cannot be explained by abnormalities in corticosteroid receptor characteristics.

Effects of Corticosteroids on Cytokine Generation and Expression of Activation Antigens by Monocytes in Bronchial Asthma

The capacity of corticosteroids to inhibit the secretion of cytokines and the expression of selective antigens on monocytes has been studied in corticosteroid-sensitive (CS) and corticosteroid-resistant (CR) asthmatic patients. Incubation of monocytes derived from CS subjects with hydrocortisone inhibited the production of the enhancing activity, whereas in CR subjects hydrocortisone at concentrations of up to 10(-4) M did not suppress the release of enhancing activity. There was a rank order of potency for corticosteroid action: hydrocortisone less than methylprednisolone less than dexamethasone. The major activity was characterized as a heat-sensitive peptide of 3,000 daltons. The expression of CR1, CR3 and class II on asthmatic peripheral-blood mononuclear cells was increased relative to normal control donors. Culturing monocytes for 24 h in the presence of 10(-4) M hydrocortisone inhibited the expression of CR1, CR3 and class II in CS subjects but not in CR individuals. These results suggest that monocytes of CR asthmatic patients can increase the inflammatory potential of neutrophils and that they are hyperactive, as indicated by increased cytokine production and enhanced expression of activation markers, despite the presence of corticosteroids.