The phase-shift mutation in the glucocorticoid receptor gene: potential etiologic significance of neuroendocrine mechanisms in lupus nephritis

Assessment of the Link of ABCB1 and NR3C1 gene polymorphisms with the prednisolone resistance in pediatric nephrotic syndrome patients of Bangladesh: A genotype and haplotype approach

Introduction

Nephrotic syndrome is a common pediatric kidney disease. Investigations on several genetic polymorphisms revealed an inconsistent influence on the resistance of patients to steroids.

Objectives

This study aimed to identify the association of ABCB1 (1236C > T, 2677G > T, 3435C > T), NR3C1 (rs10482634, rs6877893), and CYP3A5 (CYP3A5*3) gene polymorphism as well as sociodemographic and clinicopathological parameters with the risk of developing prednisolone resistance in pediatric patients with nephrotic syndrome.

Methods

A case-control analysis was performed on 180 nephrotic syndrome patients. Among them, 30 patients were classified as prednisolone resistant group, and 150 were classified as prednisolone sensitive group. Genotyping was performed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

Results

No significant association of 1236C > T polymorphism with the risk of prednisolone resistance (p > 0.05) was found. The GT heterozygous of 2677G > T was found to be significantly associated with the development of prednisolone resistance (OR = 3.9, p = 0.034). In the case of 3435C > T, a statistically significant association was observed in TC heterozygous and TT mutant homozygous genotypes (OR = 0.38, p = 0.047; OR = 3.06, p = 0.038, respectively) with prednisolone resistance. For rs10482634 polymorphism, the AG heterozygous and AG+GG genotypes were significantly linked with prednisolone resistance (OR = 2.40, p = 0.033; OR = 2.36, p = 0.034, respectively). We found no association with the risk of prednisolone resistance with rs6877893 and CYP3A5*3 polymorphism (p > 0.05). CTC and TGT haplotypes of ABCB1 and GA haplotype of NR3C1 were also associated with the increased risk of pediatric prednisolone resistance (OR = 4.47, p = 0.0003; OR = 2.71, p = 0.03; and OR = 4.22, p = 0.022, consecutively). We also observed the correlation of different sociodemographic and clinicopathological factors with prednisolone resistance in pediatric nephrotic syndrome.

Conclusion

Our findings showed a significant association of ABCB1 and NR3C1 gene polymorphisms with prednisolone resistant pediatric nephrotic syndrome.

Glucocorticoids-All-Rounders Tackling the Versatile Players of the Immune System

Glucocorticoids regulate fundamental processes of the human body and control cellular functions such as cell metabolism, growth, differentiation, and apoptosis. Moreover, endogenous glucocorticoids link the endocrine and immune system and ensure the correct function of inflammatory events during tissue repair, regeneration, and pathogen elimination via genomic and rapid non-genomic pathways. Due to their strong immunosuppressive, anti-inflammatory and anti-allergic effects on immune cells, tissues and organs, glucocorticoids significantly improve the quality of life of many patients suffering from diseases caused by a dysregulated immune system. Despite the multitude and seriousness of glucocorticoid-related adverse events including diabetes mellitus, osteoporosis and infections, these agents remain indispensable, representing the most powerful, and cost-effective drugs in the treatment of a wide range of rheumatic diseases. These include rheumatoid arthritis, vasculitis, and connective tissue diseases, as well as many other pathological conditions of the immune system. Depending on the therapeutically affected cell type, glucocorticoid actions strongly vary among different diseases. While immune responses always represent complex reactions involving different cells and cellular processes, specific immune cell populations with key responsibilities driving the pathological mechanisms can be identified for certain autoimmune diseases. In this review, we will focus on the mechanisms of action of glucocorticoids on various leukocyte populations, exemplarily portraying different autoimmune diseases as heterogeneous targets of glucocorticoid actions: (i) Abnormalities in the innate immune response play a crucial role in the initiation and perpetuation of giant cell arteritis (GCA). (ii) Specific types of CD4+ T helper (Th) lymphocytes, namely Th1 and Th17 cells, represent important players in the establishment and course of rheumatoid arthritis (RA), whereas (iii) B cells have emerged as central players in systemic lupus erythematosus (SLE). (iv) Allergic reactions are mainly triggered by several different cytokines released by activated Th2 lymphocytes. Using these examples, we aim to illustrate the versatile modulating effects of glucocorticoids on the immune system. In contrast, in the treatment of lymphoproliferative disorders the pro-apoptotic action of glucocorticoids prevails, but their mechanisms differ depending on the type of cancer. Therefore, we will also give a brief insight into the current knowledge of the mode of glucocorticoid action in oncological treatment focusing on leukemia.

DNA methylation in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease facilitated by aberrant immune responses directed against cells and tissues, resulting in inflammation and organ damage. In the majority of patients, genetic predisposition is accompanied by additional factors conferring disease expression. While the exact molecular mechanisms remain elusive, epigenetic alterations in immune cells have been demonstrated to play a key role in disease pathogenesis through the dysregulation of gene expression. Since epigenetic marks are dynamic, allowing cells and tissues to differentiate and adjust, they can be influenced by environmental factors and also be targeted in therapeutic interventions. Here, we summarize reports on DNA methylation patterns in SLE, underlying molecular defects and their effect on immune cell function. We discuss the potential of DNA methylation as biomarker or therapeutic target in SLE.

Hypermethylation of glucocorticoid receptor gene promoter results in glucocorticoid receptor gene low expression in peripheral blood mononuclear cells of patients with systemic lupus erythematosus

Our aim was to investigate the relationship between the DNA methylation status of glucocorticoid receptor (GR) gene promoter and mRNA expression level of GRα gene of peripheral blood mononuclear cells (PBMCs) in patients with systemic lupus erythematosus (SLE). Fifteen newly emerging SLE patients and fifteen healthy controls were enrolled in this study. DNA and total RNA were extracted from the PBMCs of the SLE patients and healthy controls. The DNA methylation status of GR gene promoter 1 of PBMCs was detected through bisulfite-sequencing PCR. The mRNA expression of GRα, DNA methyltransferases (DNMT1, DNMT3a, DNMT3b) and growth arrest, and DNA damage-induced 45α (GADD45α) of PBMCs was detected using the quantitative real-time polymerase chain reaction method. The mRNA expression of GRα was significantly declined in SLE patients, and the mRNA expression of DNMT1 and GADD45α was significantly elevated in SLE patients. The global methylation status of PBMCs in SLE patients was obviously lower than healthy controls. There were 38, 25, 30, and 49 CpG islands in amplified fragment of GR promoter 1D, 1E, 1F, and 1H, respectively. The overall mean methylation status of the 152 CpG islands of the four promoters was significantly elevated in SLE patients. There was a negative correlation between hypermethylation of GR promoter and GRα mRNA expression in SLE patients. This study demonstrated that hypermethylation of GRα promoter may result in GRα gene low expression in PBMCs of patients with SLE. This study also found that the global methylation status of PBMCs in SLE patients was obviously lower than healthy controls, and it was related to the elevated GADD45α mRNA expression in SLE patients. These conclusions have to be certified by larger-scale clinical studies.

Lack of association between NR3C1 polymorphism and glucocorticoid resistance in Chinese patients with immune thrombocytopenia

Resistance to glucocorticoids (GCs) is a tricky problem in therapy for immune thrombocytopenia (ITP). As GCs exert their effects through glucocorticoid receptor (GR), being a GR gene, NR3C1 is thought to connect with individual differences in GC responsiveness during GCs treatments. We analyzed the frequency of three novel single nucleotide polymorphisms (SNPs) of NR3C1 in ITP patients and evaluated the role of these genetic variants in GCs therapy. Four hundred and seventy-three patients with ITP and 160 healthy controls were recruited. Patients were allocated into GCs-responsive (n = 358) and -non-responsive group (n = 115). All subjects of the three groups were genotyped by the PCR-RFLP (restriction fragment length polymorphism) method for the BclI, N363S and ER22/23EK polymorphisms. Assess the statistical differences of genotypes between ITP and controls, and those between GCs- responsive and non-responsive groups. In healthy controls, BclI-GG/GC/CC occurred with 0.581/0.35/0.069 frequency. In ITP patients, BclI-GG/GC/CC was found with 0.617/0.353/0.03 frequency. There was no statistically differences between ITP and controls (p = 0.070). In GCs-responsive and -non-responsive group, BclI-GG, GC, CC occurred with frequencies of 0.628/0.352/0.02 and 0.583/0.357/0.061, respectively. No correlations in the variants of BclI was found between the GCs-responsive and -non-responsive group (p = 0.086). Neither N363S nor ER22/23EK polymorphism was observed in all 636 participants. The BclI polymorphism is not related to the response of GCs in patients with ITP. Furthermore, we did not observe N363S and ER22/23EK polymorphism in Chinese Han population.

Negative relationship between expression of glucocorticoid receptor alpha and disease activity: glucocorticoid treatment of patients with systemic lupus erythematosus

OBJECTIVE

Glucocorticoid receptor alpha (GRalpha) is crucial for glucocorticoids (GC) to carry out their physiological and pharmacological roles. Studies have shown the disorder of GR-GC systems in autoimmune diseases. Our study was performed to test the relationship between GRalpha expression and disease activity of systemic lupus erythematosus (SLE).

METHODS

The responses of 55 patients with SLE to GC were screened. We examined GRalpha mRNA and protein expression in peripheral blood mononuclear cells from SLE patients and healthy volunteers by reverse transcriptase-polymerase chain reaction and Western blotting.

RESULTS

Expression of GRalpha in patients with SLE was lower than that in controls (p < 0.05). Expression of GRalpha obviously decreased after administration of GC in the steroid-sensitive group with SLE (p < 0.05). Expression of GRalpha was negatively correlated with SLE Disease Activity Index scores in the steroid-sensitive group with SLE.

CONCLUSION

The expression of GRalpha in patients with SLE was low and there was a negative correlation between GRalpha expression and disease activity; these findings might provide insight into the pathogenesis of SLE and help to screen whether the patient is sensitive to GC treatment. (Heilungkiang Provincial Health Department Guiding Projects Funding. Trial registration No. 2006-094.).

Reduction in glucocorticoid receptors in renal biopsies of patients with lupus nephritis

OBJECTIVES

The first-line treatment for lupus nephritis is the administration of glucocorticoids (GC) that mediate their effects via the glucocorticoid receptor (GR). The aim of this study was to investigate the expression of GR protein in the cortical area of renal parenchyma of normal and diseased renal biopsies from treated and untreated patients.

DESIGN AND METHODS

The immunohistochemical EnVision/HRP technique was performed on renal tissue to detect GR protein. Statistical analysis was performed by SAS (2001).

RESULTS

The antigen was mainly detected in glomerular podocytes and in tubules. The number of GR-positive podocytes of the controls was significantly higher than in the untreated patients, which was accordingly higher than in patients who were under medication.

CONCLUSIONS

The lower number of GR-positive cells in the diseased kidney compared to controls is possibly linked to tissue-specific GC resistance, whereas the decreased GR expression in podocytes of treated compared to untreated patients may be due to a down-regulation effect after GCs' administration.

Glucocorticoid resistance syndrome: A diagnostic and therapeutic approach

In the past decades, several cases of the syndrome of generalized glucocorticoid (GC) resistance have been reported. This familial disease is characterized by reduced cortisol effects, due to a GC receptor (GR) defect, which is compensated by hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis. As a consequence, patients present with signs of adrenal overproduction of mineralocorticoids (hypertension and hypokalaemic alkalosis) and, in females, of androgens (hirsutism, male pattern of baldness, menstrual irregularities). In a few kindreds the underlying molecular basis has been revealed--e.g. mutations in the gene coding for the GR--but in a substantial number of patients the cause of GC resistance has not yet been elucidated. In this chapter we also discuss some other determinants which can lead to GC resistance. Diagnosis of generalized GC resistance can be difficult. This review highlights the diagnostic process and therapeutic options for treating patients with this disease.

Genetic variations of the NR3C1 gene in children with sporadic nephrotic syndrome

Previous studies have demonstrated that the genetic variations of glucocorticoid receptor gene (NR3C1) are associated with both familial steroid resistance and acquired steroid resistance in some diseases, such as Cushing's disease, leukemia, lupus nephritis, and female pseudohermaphroditism. In this study, we examined the genetic variations of NR3C1 in 35 children with sporadic steroid-resistant nephrotic syndrome (SRNS), and in 83 cases with sporadic steroid-sensitive NS (SSNS) using polymerase chain reaction, denaturing high-performance liquid chromatography and DNA sequencing, and analyzed possible associations between NR3C1 variants and steroid resistance in sporadic NS. No causative mutations were found; however, six previously identified and six novel polymorphisms, 1206C > T, 1374A > G, 2382C > T, 2193T > G, IVS7-68_-63delAAAAAA, and IVS8-9C > G, were detected. Two novel haplotypes, [1374A > G; IVS7-68_-63delAAAAAA; IVS8-9C > G; 2382C > T] and [1896C > T; 2166C > T; 2430T > C], of NR3C1 were also identified in sporadic NS and controls. The odds ratios (95% Confidence Interval) for the two novel NR3C1 haplotypes in the sporadic nephrotic children at risk of steroid resistance were 4.970 (0.889-27.788) and 2.194 (0.764-6.306), respectively, but the association between NR3C1 haplotypes and steroid resistance was not significant. Further studies on the possible association between the two novel NR3C1 haplotypes and steroid resistance in sporadic NS in larger cohorts are required.

Abnormal expression and distribution of heat shock protein 90: potential etiologic immunoendocrine mechanism of glucocorticoid resistance in idiopathic nephrotic syndrome

Resistance to glucocorticoid (GC) treatment in some patients with idiopathic nephrotic syndrome (INS) is a significant clinical problem. Heat shock protein 90 (HSP90) is the chaperon protein of the GC receptor, which is supposed to be the key factor of GC response. Therefore, we conducted this study to define the mechanisms of GC resistance related to HSP90. INS patients and cell lines with differing GC responses were included in the present study. We found that the level of HSP90 mRNA expression in INS patients was significantly higher than that in healthy controls and that HSP90 expression in GC-resistant INS patients was higher than that in GC-sensitive INS patients. A confocal immunofluorescence test was performed to investigate the subcellular localization of HSP90, and we found that the distribution of HSP90 in the GC-resistant INS group was greater in the nuclei than that of the GC-sensitive INS group. When the function of HSP90 was blocked by the HSP90-specific inhibitor, the GC sensitivity of GC-sensitive cells decreased remarkably. These results indicate that HSP90 plays a vital role in GC response. In addition, the abnormality in the mRNA level and subcellular distribution of HSP90 in GC-resistant INS patients may be etiologically significant in terms of endogenous/synthetic GC resistance. On one hand, it may disturb immunoendocrine regulation via endogenous GC and immune homeostasis and thus be involved in the occurrence of the immune-mediated disease; on the other hand, it may influence the patient's response to synthetic GC treatment and result in treatment failure.

Neural regulation of innate immunity: a coordinated nonspecific host response to pathogens

The central nervous system (CNS) regulates innate immune responses through hormonal and neuronal routes. The neuroendocrine stress response and the sympathetic and parasympathetic nervous systems generally inhibit innate immune responses at systemic and regional levels, whereas the peripheral nervous system tends to amplify local innate immune responses. These systems work together to first activate and amplify local inflammatory responses that contain or eliminate invading pathogens, and subsequently to terminate inflammation and restore host homeostasis. Here, I review these regulatory mechanisms and discuss the evidence indicating that the CNS can be considered as integral to acute-phase inflammatory responses to pathogens as the innate immune system.

Activation of the hypothalamic-pituitary-adrenal axis and autonomic nervous system during inflammation and altered programming of the neuroendocrine-immune axis during fetal and neonatal development: lessons learned from the model inflammagen, lipopolysaccharide

The hypothalamic-pituitary-adrenal axis (HPAA) and autonomic nervous system (ANS) are both activated during inflammation as an elaborate multi-directional communication pathway designed to restore homeostasis, in part, by regulating the inflammatory and subsequent immune response. During fetal and neonatal development programming of the HPAA, ANS and possibly the immune system is influenced by signals from the surrounding environment, as part of an adaptive mechanism to enhance the survival of the offspring. It is currently hypothesized that if this programming is either misguided, or the individual's environment is drastically altered such that neuroendocrine programming becomes maladaptive, it may contribute to the pathogenesis of certain diseases. Current research, suggests that exposure to inflammatory signals during critical windows of early life development may influence the programming of various genes within the neuroendocrine-immune axis. This review will provide, (1) an overview of the HPAA and ANS pathways that are activated during inflammation, highlighting studies that have used lipopolysaccharide as a model inflammagen and, (2) evidence to support the hypothesis that inflammatory stress during fetal and neonatal development can alter programming of the neuroendocrine-immune axis, influencing stress and immune responsiveness, and possibly disease resistance later in life.

Glucocorticoid receptor, nuclear factor kappaB, activator protein-1 and C-jun N-terminal kinase in systemic lupus erythematosus patients

OBJECTIVE

Due to the crucial role of the glucocorticoid receptor (GR), nuclear factor kappaB (NFkappaB), activator protein-1 (AP-1) and c-jun N-terminal kinase (JNK) in regulating inflammatory mediators and immune responses, we investigated their potential role in systemic lupus erythematosus (SLE).

PATIENTS AND METHODS

Whole cell and nuclear extracts from peripheral blood lymphocytes, isolated from 25 SLE patients and 25 controls, were immunoblotted using GR, p65/NFkappaB, c-fos and JNK1 antibodies. The electrophoretic mobility shift assay (EMSA) assessed GR, NFkappaB and AP-1-DNA binding in nuclear aliquots. Associations with the disease state and the doses of corticosteroids administered were studied.

RESULTS

(i) SLE patients had lower GR-DNA binding (p < 0.001), NFkappaB-DNA binding (p < 0.001) and whole cell c-fos (p < 0.01) but higher nuclear NFkappaB (p < 0.01). (ii) SLE patients and controls had similar AP-1-DNA binding, nuclear c-fos, GR and JNK, whole cell GR, NFkappaB and JNK. (iii) No differences were detected between active and non-active SLE or high- and low-dose corticosteroid patients. (iv) In SLE, increases in GR-DNA binding were associated with increases in NFkappaB-DNA binding (p < 0.0001), and increases in nuclear JNK were associated with increases in AP-1-DNA binding (p < 0.01). (v) In controls, increases in GR-DNA binding were associated with increases in AP-1-DNA binding (p < 0.001).

CONCLUSION

We suggest disturbed GR, NFkappaB, AP-1 and JNK signaling in SLE, characterized by a reduced GR- and NFkappaB-DNA binding, a significant association between GR-mediated and NFkappaB-driven pathways, and a significant correlation between nuclear JNK- and AP-1-driven pathways. These disturbances may contribute to abnormal cytokine production and the etiopathogenesis of SLE.

Signaling pathways in brain involved in predisposition and pathogenesis of stress-related disease: genetic and kinetic factors affecting the MR/GR balance

Optimal regulation of the stress response is a prerequisite for adaptation, homeostasis, and health. There are two modes of operation in the stress response. First, an immediate response mode mediated by corticotrophin-releasing hormone-1 (CRH-1) receptors that organizes the behavioral, sympathetic, and hypothalamic-pituitary-adrenal (HPA) response to a stressor. Second, a slower mode, which facilitates behavioral adaptation, promotes recovery, and reestablishes homeostasis. Corticosteroid hormones are implicated in both stress system modes. On the one hand, cortisol and corticosterone determine the threshold or sensitivity of the fast responding mode, whereas the very same hormones in high concentrations facilitate termination of the stress response. In the brain, these actions exerted by the corticosteroid hormones are mediated by two distinct nuclear receptor types, that is, mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs). Whereas MRs maintain neuronal homeostasis and limit the disturbance by stress, GRs help to recover after the challenge and to store the experience for coping with future encounters. Imbalance in MR/GR-mediated actions compromises homeostatic processes in these neurons, which is thought to underlie maladaptive behavior and HPA dysregulation that may lead to aberrant metabolism, impaired immune function, and altered cardiovascular control. The balance in MR/GR-mediated actions depends on bioavailability of corticosteroids, access to the receptors, the stoichiometry of co-regulators, and other proteins as well as genetic factors, among which single nucleotide polymorphisms (SNPs) of the GRs are extensively documented. Stress can bias the receptor signaling pathways, changing "good" corticosteroid actions into "bad" ones.

Significance of glucocorticoid receptor expression in colonic mucosal cells of patients with ulcerative colitis

AIM: Glucocorticoid (GC) resistant ulcerative colitis (UC) remains a serious disease and is difficult to manage. Although the molecular basis of GC insensitivity is still unknown, GC receptors (GRα and GRβ) may play an important role in it. This study was aimed to investigate the relationship between the expression of GRα and GRβ in colonic mucosal cells of patients with UC, the efficacy of GC therapy and the intensity of inflammation.

METHODS: Twenty-five cases of UC were classified into: GC sensitive (n = 16) and GC resistant (n = 9) cases. Patients consisted of mild (n = 6), moderate (n = 8) and severe (n = 11) cases. GRα and GRβ expression in colonic mucosal specimens were investigated by immunohistochemistry, and compared between GC resistant and sensitive groups, and also among various degrees of inflammation.

RESULTS: All cases were positive for GRα and GRβ expression. Both positive association between GRα expression and the response of UC to GC and strong negative association between GRβ expression and the response of UC to GC were identified. There was no significant association between GRα/GRβ expression and the degree of inflammation of UC.

CONCLUSION: These findings suggest that both GRα and GRβ may play an important role in the action of GC, and that GRβ functions as a dominant negative inhibitor of GRα. Expression of GRα and GRβ in colonic mucosal cells of patients with UC may serve as predictors of glucocorticoid response, but can not function as markers of inflammatory intensity.

Identification of polymorphisms in the human glucocorticoid receptor gene (NR3C1) in a multi-racial asthma case and control screening panel

The glucocorticoid receptor (GR) gene (NR3C1) maps to 5q31, a region genetically linked to asthma. In this study, NR3C1 exons 1A, 1B, and exons 1C to 9 (alpha and beta) were sequenced in a screening panel of asthmatics and unaffected controls from US Caucasian, African American, US Hispanic, and Dutch Caucasian populations to identify polymorphisms for genetic association studies. Eight polymorphisms were identified in exon 1A, but none were located in putative transcription regulatory sites. Thirty-four polymorphisms were identified in exons 1B to 9 (alpha and beta), 17 of which were novel. Eight coding polymorphisms were identified (4 non-synonymous). One novel mutation (Ala229Thr) was identified in a Hispanic individual. Linkage disequilibrium (LD) was strongest between polymorphisms spanning intron 2 to exon 9beta. This data shows the variability of NR3C1 polymorphism frequencies between racial groups and confirms that NR3C1 non-synonymous coding polymorphisms are generally rare in mild/moderate asthmatics and unaffected controls.

Brain-immune interactions and disease susceptibility

Many studies have established the routes by which the immune and central nervous (CNS) systems communicate. This network of connections permits the CNS to regulate the immune system through both neuroendocrine and neuronal pathways. In turn, the immune system signals the CNS through neuronal and humoral routes, via immune mediators and cytokines. This regulatory system between the immune system and CNS plays an important role in susceptibility and resistance to autoimmune, inflammatory, infectious and allergic diseases. This review focuses on the regulation of the immune system via the neuroendocrine system, and underlines the link between neuroendocrine dysregulation and development of major depressive disorders, autoimmune diseases and osteoporosis.

A mutation of the glucocorticoid receptor gene in patients with systemic lupus erythematosus

We screened for mutations of the glucocorticoid receptor (GR) gene in patients with systemic lupus erythematosus (SLE), a typical autoimmune disease. Polymerase chain reaction-single-strand conformation polymorphism analysis (PCR-SSCP) revealed a single mutation in exon 9 of the GR gene in 11/132 (8.3%) among 66 patients with SLE. No mutations were detected in 52 healthy individuals (0/104, 0.0%), but the same mutation was detected in other autoimmne diseases (4/108, 3.7%). DNA sequencing showed a T to C substitution at codon 766 (position 2430) of the GR gene, which does not alter the amino acid sequence of the GR. Further analysis using a LightCycler generated different melting curves indicates that the pattern with this mutation is different from that of wild type. The identified mutation of the GR gene may represent a polymorphism associated with SLE.

Structure and function of the glucocorticoid receptor ligand binding domain

After binding to an activating ligand, such as corticosteroid, the glucocorticoid receptor (GR) performs an impressive array of functions ranging from nuclear translocation, oligomerization, cofactor/kinase/transcription factor association, and DNA binding. One of the central functions of the receptor is to regulate gene expression, an activity triggered by ligand binding. In this role, GR acts as an adapter molecule by encoding the ligand's message within the structural flexibility of the ligand binding domain (LBD). The purpose of this review is to discuss the many structural and functional features of the GR LBD in light of recent successful biochemical and crystallographic studies. Progress in this area of research promises to reveal new strategies and insights allowing for the design of novel drugs to treat inflammatory diseases, diabetic conditions, steroid resistance, and cancers.

Functional analysis of three genetic polymorphisms in the glucocorticoid receptor gene

Glucocorticoids are widely used as potent anti-inflammatory drugs. Glucocorticoids exert their pharmacological effects by binding to a glucocorticoid receptor (GR), which promotes expression of its target genes or suppresses transcription mediated by other transcriptional factors, such as nuclear factor-kappaB (NF-kappaB). To identify genetic polymorphisms affecting glucocorticoid responses, the GR gene was sequenced, and two novel single nucleotide alterations, 1510A>T (T504S) and 1952C>T (S651F), were identified in addition to an adenine base insertion at nucleotide 2314 (2314insA). mRNA expression levels of T504S and S651F were comparable with that of the wild type (WT), whereas the mRNA level of 2314insA was reduced to approximately 36% of the WT level. Protein expression was reduced to approximately 66% of WT levels in S651F and to approximately 6% in 2314insA. No significant change was seen in the T504S variant levels. The instability of the 2314insA mRNA, S651F protein, and 2314insA protein was confirmed by time course experiments. The transcriptional activity of S651F and 2314insA was also reduced to approximately 63 and 2% of the WT levels, respectively, in the luciferase reporter assay. Moreover, the inhibitory effect of GR on NF-kappaB transactivation was reduced to approximately 81 and 12% of the WT levels for S651F and 2314insA, respectively. These results indicated that the overall transcriptional activity and inhibitory effect on NF-kappaB transactivation of S651F and 2314insA have partially reduced and almost abrogated, respectively, almost paralleling their reduced protein expression levels caused by mRNA and/or protein instabilities. Thus, these two variations were suggested to influence the response to glucocorticoid treatment.

Intravenous pulses of methylprednisolone for systemic lupus erythematosus

BACKGROUND

Intravenous (IV) pulses of methylprednisolone (MEP) commonly are used to treat severe manifestations of systemic lupus erythematosus (SLE). However, despite wide use of this treatment the best dose, timing, and the situations in which this treatment should be used remain largely anecdotal.

AIM

To review the mechanisms of action and evidence for clinical use of IV MEP in the treatment of SLE.

METHOD

The literature on MEP use in SLE from 1966 to 2002, using PubMed from the National Library of Medicine, was reviewed.

RESULTS

As with other modes of corticosteroid administration, IV MEP has significant anti-inflammatory and immunosuppressive actions. These actions have been shown to be effective in treating SLE in clinical trials, for lupus nephritis. The studies are mainly uncontrolled and retrospective. Long-term observations from a few double-blind prospective trials suggest that monthly pulses of MEP, in addition to IV cyclophosphamide, may be useful. Pulse MEP is beneficial for several serious manifestations of SLE, such as neuro-psychiatric lupus, pulmonary hemorrhage, severe blood dyscrasias, cardiomyopathy, and vasculitis. However, significant side effects may occur, mostly infections, which are worse in patients with hypoalbuminemia.

CONCLUSION

IV pulses of MEP rapidly immunosuppress patients with organ and/or life-threatening manifestations of SLE. However, the gold standard 1 g/day for 3 consecutive days is associated with significant infectious complications and lower doses may be just as useful.

Application of denaturing gradient gel electrophoresis (DGGE) to screen for mutations of the human glucocorticoid receptor alpha gene (hGRalpha)

OBJECTIVES

In a previous publication, we had presented a sensitive method to detect mutations of the segment of the human glucocorticoid receptor alpha (hGRalpha) gene encoding the ligand binding domain (LBD) and part of the DNA binding domain (DBD) of hGRalpha, as several types of glucocorticoid resistance syndromes have been correlated with mutations in the respective nucleotide sequences. However, mutations affecting various regions covering the whole length of hGRalpha are increasingly reported in a variety of disease states. We now present an expanded screening methodology to detect mutations covering the whole length of hGRalpha.

DESIGN AND METHODS

We developed a sensitive, simple screening PCR-DGGE method to detect mutations in the aminoterminal domain and DNA-binding domain of the hGRalpha. Wild type hGRalpha cDNA and mutant samples were included in the analysis to ensure the accuracy and sensitivity of the method.

RESULTS

The PCR-DGGE method identified the mutant samples and discriminated them from wild type hGRalpha.

CONCLUSIONS

The method described is accurate, sensitive, simple, cheap and fulfills the critera for a screening method which will be useful in delineating possible involvement of hGRalpha mutations in the aetiopathology of diseases correlated to derangements of glucocorticoid action.

Variations of the human glucocorticoid receptor gene (NR3C1): pathological and in vitro mutations and polymorphisms

Glucocorticoid (GC) resistance can occur in a number of diseases. It can be either generalized (i.e., familial glucocorticoid resistance) or localized (i.e., asthma). In many cases, a reason for this resistance to steroids lies with mutations or polymorphisms present in the glucocorticoid receptor gene (GR/NR3C1) that belongs to a large family of nuclear receptors. A number of GC-resistant cell lines have been isolated in vitro, some of which arose or may have arisen in vivo. These and the mutations defined in them are included in this review as well as mutations engineered in plasmids and expressed in vitro. It also lists polymorphisms and the individual studies where association-related studies have been performed. NR3C1 is located on chromosome 5q31 and contains 10 exons that code for a 777 amino acid protein. There are two naturally occurring isoforms of the NR3C1, GRalpha (functional) and GRbeta (no hormone-binding ability). A total of 15 missense, three nonsense, three frameshift, one splice site, and two alternative spliced mutations have been reported in the NR3C1 gene associated with glucocorticoid resistance as well as 16 polymorphisms. Mutation and polymorphism data for NR3C1 will soon be found on the newly created locus-specific database.

The glucocorticoid receptor gene and its association to metabolic syndrome

In recent decades, there has been an increasing interest in the role of endogenous glucocorticoids such as cortisol in the pathogenesis of metabolic syndrome. Studies in humans have suggested a positive association between obesity, hypertension, and insulin resistance, with alleles at the glucocorticoid receptor (GR) gene. For instance, the BclI polymorphism within the intron upstream of GR exon 2 has been associated with cardiovascular risk factors such as visceral obesity, hypertension, insulin resistance, and elevated cortisol concentrations. However, the location of the BclI polymorphism is not known, and the variant has so far not been compared with the wild-type receptor for its ability to be activated by glucocorticoids. Although several other mutations in the GR gene have been postulated as being relevant to the progression to type 2 diabetes and cardiovascular diseases, conflicting results makes it difficult to determine exactly what effect these GR variations have on metabolic syndrome incidence and progression. Further studies focusing on the most compelling GR mutations might offer a better understanding of metabolic syndrome pathogenesis and progression, aiding in the development of more effective treatments for this condition.

The role of pharmacogenetically-variable cytochrome P450 enzymes in drug abuse and dependence

The risk of drug dependence is determined by the interaction of drug, individual and environment. 'Pharmacogenetics' is the study of the influence of heredity on the response to drugs and their fate in the body; these studies aim to improve the understanding of inter-individual variability in drug response. The authors have applied this research approach to the study of drug metabolism and dependence. Specifically the interaction of genetically variable hepatic cytochrome P450 (CYP) enzymes and their effect on self-administration of drugs has been examined. Many drugs of abuse are substrates (e.g., amphetamines, codeine, nicotine) or inhibitors (e.g., (-)-cocaine) of polymorphic CYPs. Drug metabolism by genetically polymorphic enzymes can have significant clinical implications relating to drug toxicity, therapeutic failure, drug-drug interactions, disease susceptibility and abuse liability. There is good evidence that drug metabolism by genetically variable CYPs can influence the risk of drug dependence, the amount of drug consumed by dependent individuals and some of the toxicities associated with drug-taking behavior. It is anticipated that pharmacogenetics will be used to identify individuals at a greater risk for specific drug dependencies, provide information that can lead to novel treatment and prevention approaches as well as provide guidance for individualization of treatment choice.