Glucocorticoid receptor polymorphisms in Korean patients with rheumatoid arthritis

Glucocorticoid receptor polymorphisms and haplotypes and their expression in health and disease

Cortisol is involved in many physiological processes, including immunosuppressive and anti-inflammatory actions, and therefore cortisol and its synthetic analogs are widely used to treat a large number of diseases. In glucocorticoid treatment, a large variability of clinical responses is observed. This variability may, in part, be ascribed to genetic variation in the glucocorticoid receptor (GR) gene. In this review we present a catalogue of the various single nucleotide polymorphisms (SNPs) in the glucocorticoid receptor gene and their consequences for human health and disease. Many different GR SNP association studies have been described. However, most studies come down to only a few SNPs reported with different annotations. In this review we clarified these different annotations to uniform names. Most associations between GR SNPs and phenotype have been found in body composition, metabolism, the cardiovascular system, the immune system and psychiatric illnesses. However, many associations have not been replicated (yet), and future replication studies and meta-analyses are needed. There is a substantial body of evidence for GR SNPs to have effects on clinical phenotype. However, as most SNP frequencies are low and their variation is within the range of the general population, the impact of a single SNP for health and disease in the general population is probably modest. However, in-depth studying of the molecular mechanisms of repeatedly observed clinical associations could lead to new possibilities for drug development. In particular the development of selective glucocorticoid receptor modulators holds promise.

Investigation of glucocorticoid receptor polymorphisms in relation to metabolic parameters in Addison's disease

BACKGROUND

Uncertainty exists whether glucocorticoid receptor (GCR) polymorphisms play a role in steroid-related side effects in Addison's disease (AD) patients on hydrocortisone. The polymorphisms Bcll and N363S appear to increase sensitivity to cortisol, while the ER22/23EK polymorphism has been associated with resistance to cortisol.

METHOD

One hundred and forty seven AD patients, and gender, and ethnicity-matched controls were recruited in South Africa. Three polymorphisms in the GCR were studied, using PCR followed by restriction fragment length analysis. Associations with BMI, lipids, glucose and inflammatory markers were investigated.

RESULTS

In both patients and controls, the Bcll polymorphism occurred more frequently in whites than in other ethnic groups studied but was not associated with any of the metabolic parameters tested. The ER22/23EK polymorphism was associated with an increased BMI in both patients (29.4 vs 24.7  kg/m²) and control subjects (26.3 vs 24.2  kg/m²). The ER22/23EK polymorphism was also associated with lower LDL cholesterol in control subjects (3.46 vs 3.93  mmol/l) and in patients (3.52 vs 4.10  mmol/l). N363S was associated with increased BMI in controls 29.9  kg/m² vs wild type 24.8  kg/m². Median hydrocortisone doses were greater in patients heterozygous for either ER22/23EK 30.0  mg or N363S 25.0  mg polymorphisms than in wild type patients 20.0  mg (both comparisons).

CONCLUSION

Alterations in lipids, BMI and hydrocortisone dose were associated with two polymorphisms. Further larger studies are warranted to corroborate these findings.

Primary generalized familial and sporadic glucocorticoid resistance (Chrousos syndrome) and hypersensitivity

Familial or sporadic primary generalized glucocorticoid resistance or Chrousos syndrome is a rare genetic condition characterized by generalized, partial, target-tissue insensitivity to glucocorticoids and a consequent hyperactivation of the hypothalamic-pituitary-adrenal (HPA) axis. Primary generalized glucocorticoid hypersensitivity (PGGH) represents the mirror image of the former, and is characterized by generalized, partial, target-tissue hypersensitivity to glucocorticoids, and compensatory hypoactivation of the HPA axis. The molecular basis of both conditions has been ascribed to mutations in the human glucocorticoid receptor (hGR) gene, which impair the molecular mechanisms of hGR action and alter tissue sensitivity to glucocorticoids. This review summarizes the pathophysiology, molecular mechanisms and clinical aspects of Chrousos syndrome and PGGH.

Glucocorticoid sensitivity in Behçet's disease

OBJECTIVE

Glucocorticoid (GC) sensitivity is highly variable among individuals and has been associated with susceptibility to develop (auto-)inflammatory disorders. The purpose of the study was to assess GC sensitivity in Behçet's disease (BD) by studying the distribution of four GC receptor (GR) gene polymorphisms and by measuring in vitro cellular GC sensitivity.

METHODS

Healthy controls and patients with BD in three independent cohorts were genotyped for four functional GR gene polymorphisms. To gain insight into functional differences in in vitro GC sensitivity, 19 patients with BD were studied using two bioassays and a whole-cell dexamethasone-binding assay. Finally, mRNA expression levels of GR splice variants (GR-α and GR-β) were measured.

RESULTS

Healthy controls and BD patients in the three separate cohorts had similar distributions of the four GR polymorphisms. The Bcll and 9β minor alleles frequency differed significantly between Caucasians and Mideast and Turkish individuals. At the functional level, a decreased in vitro cellular GC sensitivity was observed. GR number in peripheral blood mononuclear cells was higher in BD compared with controls. The ratio of GR-α/GR-β mRNA expression levels was significantly lower in BD.

CONCLUSIONS

Polymorphisms in the GR gene are not associated with susceptibility to BD. However, in vitro cellular GC sensitivity is decreased in BD, possibly mediated by a relative higher expression of the dominant negative GR-β splice variant. This decreased in vitro GC sensitivity might play an as yet unidentified role in the pathophysiology of BD.

Glucocorticoid receptor gene polymorphism and juvenile idiopathic arthritis

BACKGROUND

The glucocorticoid receptor gene (NR3C1) has been suggested as a candidate gene affecting juvenile idiopathic arthritis (JIA) course and prognosis. The purpose of this study is to investigate the glucocorticoid receptor gene BclI polymorphism (rs41423247) in JIA patients, the gene's role in susceptibility to juvenile idiopathic arthritis, and its associations with JIA activity, course and bone mineralization.

METHODS

One hundred twenty-two Caucasian children with JIA and 143 healthy ethnically matched controls were studied. We checked markers of clinical and laboratory activity: morning stiffness, Ritchie Articular Index (RAI), swollen joint count (SJC), tender joint count (TJC), physician's visual analog scale (VAS), hemoglobin level (Hb), leukocyte count (L), platelet count (Pl), Westergren erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), albumin, DAS and DAS28. Bone mineralization was measured by dual-energy X-ray absorptiometry (DXA) of lumbar spine L1-L4. Assessments of bone metabolism included osteocalcin, C-terminal telopeptide (CTT), parathyroid hormone (PTH), total and ionized calcium, inorganic phosphate and total alkaline phosphatase (TAP). BclI polymorphism was genotyped by polymerase chain reaction restriction fragment length polymorphism.

RESULTS

No association was observed between glucocorticoid receptor gene polymorphism and the presence or absence of JIA. In girls with JIA, the presence of the G allele was associated with an unfavorable arthritis course, a younger age of onset of arthritis (p = 0.0017), and higher inflammatory activity. The higher inflammatory activity was demonstrated by the following: increased time of morning stiffness (p = 0.02), VAS (p = 0.014), RAI (p = 0.048), DAS (p = 0.035), DAS28 (p = 0.05), Pl (p = 0.003), L (p = 0.046), CRP (p = 0.01). In addition, these patients had bone metabolism disturbances as follows: decreased BA (p = 0.0001), BMC (p = 0.00007), BMD (0.005) and Z score (p = 0.002); and higher levels of osteocalcin (p = 0.03), CTT (p = 0.036), TAP activity (p = 0.01) and ionized calcium (p = 0.017). In boys with JIA, no significant differences were observed related to the polymorphic alleles or genotypes.

CONCLUSIONS

We suggest that G allele and the GG genotype of the glucocorticoid receptor gene BclI polymorphism contribute to an unfavorable course and low bone mineral density in girls with JIA.

Polymorphisms in the glucocorticoid receptor gene that modulate glucocorticoid sensitivity are associated with rheumatoid arthritis

Introduction

The glucocorticoid receptor (GR) plays an important regulatory role in the immune system. Four polymorphisms in the GR gene are associated with differences in glucocorticoid (GC) sensitivity; the minor alleles of the polymorphisms N363 S and BclI are associated with relative hypersensitivity to GCs, while those of the polymorphisms ER22/23EK and 9β are associated with relative GC resistance. Because differences in GC sensitivity may influence immune effector functions, we examined whether these polymorphisms are associated with the susceptibility to develop Rheumatoid Arthritis (RA) and RA disease severity.

Methods

The presence of GR polymorphisms was assessed in healthy controls (n = 5033), and in RA patients (n = 368). A second control group (n = 532) was used for confirmation of results. In RA patients, the relationship between GR polymorphisms and disease severity was examined.

Results

Carriers of the N363 S and BclI minor alleles had a lower risk of developing RA: odds ratio (OR) = 0.55 (95% confidence interval (CI) 0.32-0.96, P = 0.032) and OR = 0.73 (95% CI 0.58-0.91, P = 0.006), respectively. In contrast, 9β minor allele carriers had a higher risk of developing RA: OR = 1.26 (95% CI 1.00-1.60, P = 0.050). For ER22/23EK minor allele carriers a trend to an increased risk OR = 1.42 (95% CI 0.95-2.13, P = 0.086) was found. All ER22/23EK carriers (32/32) had erosive disease, while only 77% (259/336) of the non-carriers did (P = 0.008). In addition, ER22/23EK carriers were treated more frequently with anti-tumor necrosis factor-alpha (TNFα) therapy (P < 0.05).

Conclusions

The minor alleles of the 9β and ER22/23EK polymorphisms seem to be associated with increased predisposition to develop RA. Conversely, the minor alleles of the N363 S and BclI polymorphisms are associated with reduced susceptibility to develop RA. These opposite associations suggest that constitutionally determined GC resistance may predispose to development of auto-immunity, at least in RA, and vice versa.

Clinical features associated with glucocorticoid receptor polymorphisms. An overview

The glucocorticoid receptor (GR) is crucial for the effects of glucocorticoids (GCs). Several polymorphisms of the GR are associated with altered sensitivity to GCs. For the ER22/23EK polymorphism, a relative GC resistance has been demonstrated. In vivo, this was suggested by a smaller response to a dexamethasone suppression test (DST), whereas in vitro experiments showed a diminished transactivational activity. The associated features of ER22/23EK carriers consist of favorable metabolic and body compositional conditions. In elderly subjects this polymorphism was associated with longevity and decreased risk of dementia. Interestingly, recent studies also showed an increased risk of major depression. In contrast, the N363S polymorphism was reported to be associated with an enhanced sensitivity to GCs, as was demonstrated by a DST. This polymorphism has also been associated with increased body mass index (BMI) and LDL-cholesterol levels, as well as increased risk of cardiovascular disease. However, additional studies yielded conflicting results, showing no associations with being overweight. The BclI polymorphism is also associated with increased GC sensitivity. In addition, associations with increased abdominal fat mass, Crohn's disease and, remarkably, major depression have been reported. Another GR polymorphism, located in exon 9beta, is associated with increased expression and stabilization of the dominant negative splice variant GR-beta. Carriers of this polymorphism displayed a relative GC resistance in vitro as evidenced by diminished transrepressional activity, which is important for the immune system and inflammation. Associations have been found with increased inflammatory parameters, cardiovascular disease, and rheumatoid arthritis. In this article, studies concerning these clinically relevant GR variants are discussed.

Simultaneous evaluation of in vivo glucocorticoid sensitivity and expression of glucocorticoid receptor alpha-isoform in rheumatoid arthritis patients

OBJECTIVES: To analyze glucocorticoid (GC) sensitivity using intravenous very low dose dexamethasone suppression test (IV-VLD-DST) in patients with rheumatoid arthritis (RA) and its correlation with glucocorticoid receptor alpha-isoform (GRα) gene expression. METHODS: We evaluated 20 healthy controls and 32 RA patients with Health Assessment Questionnaire (HAQ) and Disease Activity Score 28 joints (DAS) scores and IV-VLD-DST and GRα expression in mononuclear cells. RESULTS: Basal cortisol and the percentage of cortisol reduction after IV-VLD-DST were lower in RA patients than in controls, whereas GRα expression was similar among groups. In the RA group there was an inverse correlation between GRα expression and the percentage of cortisol suppression that was not observed in controls. There was a direct relationship between DAS and GRα expression. CONCLUSIONS: Mechanisms involved in GC resistance observed in patients with RA are possibly not at the level of GRα gene expression, since it was similar among groups and GRα increased with disease activity.

The role of glucocorticoids and progestins in inflammatory, autoimmune, and infectious disease

A bidirectional communication exists between the CNS and the immune system. The autonomic nervous system, through neurotransmitters and neuropeptides, works in parallel with the hypothalamic-pituitary-adrenal axis through the actions of glucocorticoids to modulate inflammatory events. The immune system, through the action of cytokines and other factors, in turn, activates the CNS to orchestrate negative-feedback mechanisms that keep the immune response in check. Disruption of these interactions has been associated with a number of syndromes including inflammatory, autoimmune, and cardiovascular diseases, metabolic and psychiatric disorders, and the development of shock. The hypothalamic-pituitary-gonadal axis also plays an important part in regulating immunity through the secretion of sex hormones. Although numerous studies have established a role for immunomodulation by estrogen and testosterone, the role of progesterone is less well understood. Progesterone is crucial for reproductive organ development and maintenance of pregnancy, and more recent studies have clearly shown its role as an important immune regulator. The main focus of this review will be about the role of steroid hormones, specifically glucocorticoids and progesterone, in inflammatory responses and infectious diseases and how dysregulation of their actions may contribute to development of autoimmune and inflammatory disease.

Neuroendocrine-immune interactions in rheumatoid arthritis: mechanisms of glucocorticoid resistance

Rheumatoid arthritis (RA) is characterized by chronic inflammation of the synovial membrane, leading to joint destruction. Many autoimmune diseases and disease states of chronic inflammation are accompanied by alterations in the complex interactions between the endocrine, nervous and immune systems. Glucocorticoids, an end product of the hypothalamic-pituitary-adrenal axis, are a mainstay treatment for many autoimmune diseases, including RA, because of their potent anti-inflammatory action. However, about 30% of patients with RA fail to respond to steroid therapy. There are various mechanisms that may contribute to the development of glucocorticoid resistance in inflammatory disorders, which will be the subject of this review. In addition, glucocorticoid resistance may be a contributing factor in the development of inflammatory/autoimmune diseases themselves. Therefore, further elucidation of these mechanisms will reveal new targets for therapeutic intervention in the treatment of RA.

Glucocorticoid receptor gene polymorphisms and susceptibility to rheumatoid arthritis

BACKGROUND

A defect in hypothalamic-pituitary-adrenal (HPA) axis function has been suggested to contribute to susceptibility to rheumatoid arthritis (RA).

OBJECTIVE

To investigate polymorphisms of the glucocorticoid receptor (GR) gene and determine any associations with RA.

METHODS

Three GR polymorphisms that tag 95% of all haplotypes across the GR gene were genotyped. These are an intron B Bcl1 polymorphism, a ttg insertion/deletion within intron F (rs2307674) and the single nucleotide polymorphism (SNP) lying in the 3' untranslated region of exon 9b (rs6198). The dye terminator-based SNaPshot method or size resolution by capillary electrophoresis was performed. The study population comprised 198 UK Caucasian RA cases and 393 ethnically matched controls.

RESULTS

No significant single point or haplotypic associations were found for GR polymorphisms with RA susceptibility. Furthermore, no evidence for GR polymorphisms with aspects of RA severity was seen.

CONCLUSION

In this study of the most comprehensive coverage of GR polymorphisms with RA, no significant contributing role for GR polymorphisms with RA was found.

Detection of the Bcl I polymorphism of the glucocorticoid receptor gene by single-tube allele-specific polymerase chain reaction

The Bcl I polymorphism of the glucocorticoid receptor gene, recently identified as an intronic C to G change 646 nucleotides downstream of exon 2, has been associated with increased sensitivity to glucocorticoids and its potential relevance in metabolic disturbances and in various disorders has been extensively investigated. In the present study, we designed a single-tube allele-specific polymerase chain reaction for genotyping this polymorphism in peripheral blood DNA samples. When the Bcl I polymorphism was detected with this novel method in a cohort of 247 healthy subjects, the observed genotype distribution matched the Hardy-Weinberg equilibrium (100 subjects homozygous for the wild-type, 124 heterozygous and 23 homozygous for the mutant allele). In 50 randomly selected subjects the Bcl I polymorphism was also determined using a traditional restriction fragment length polymorphism technique and DNA sequencing, and the results showed 100% coincidence with those obtained by our novel method. The method proved to be more rapid and less labour-intensive compared to currently used techniques, and it avoided the use of extensive instrumentals. We assume that this novel method may have a broad utility in clinical and molecular epidemiological studies aimed to elucidate the impact of the Bcl I polymorphism of the glucocorticoid receptor gene either on metabolic disturbances, or various disorders, including cancer treatment and hormone substitution therapies.