Glucocorticoid resistance in atopic dermatitis associated with decreased expression of glucocorticoid receptor-α in peripheral blood mononuclear cells

Update on pharmacology, actions, dosimetry and regimens of oral glucocorticoids in dermatology

Glucocorticoids are arguably the most widely used and misused drug in dermatology. There have been recent updates in its mode of action which can impact on its judicious use. There is need to use the correct steroid preparation to maximize results and minimize side effects. We present an updated review on glucocorticoids focusing on its mode of action, rationale of its prescribing considerations and dosing regimens in dermatology. This is based on PubMed search with a focus on mode of actions and dosimetry with additional updates from standard drug books, databases and rheumatology books.

REVEALING THE MOLECULAR-GENETIC AND CLINICAL PREDICTORS OF GLUCOCORTICOID RESISTANCE IN PATIENTS WITH HAND ECZEMA

OBJECTIVE

The aim: To reveal the possible predictors of the glucocorticoid resistance in patients with hand eczema (HE) based on the demographic, clinical, and molecular-genetic data.

PATIENTS AND METHODS

Materials and methods: 143 patients with HE were included in the study. Demographic, clinical, biochemical (blood content of IgE, IL-17A, IL-2, 25(OH)D), and genetic (rs41423247 genotypes) data were obtained from all patients.

RESULTS

Results: After 2 weeks of treatment by glucocorticoids, all subjects were divided into "responder" and "non-responder" groups according to change of the Hand Eczema Severity Index (HECSI). Statistical analysis was done using SPSS (version 22.0.). Binary logistic regression was used to identify predictors of glucocorticoid resistance. P-value 0.05). The results of the multivariate regression showed that Bcl-1 G-allele (OR =3.83; P = 0.033), and severe eczema (OR = 2.52; P = 0.023) are linked with an elevated risk of glucocorticoid resistance in patients with hand eczema.

CONCLUSION

Conclusions: Insensitivity to glucocorticoids in HE patients is associated with NR3C1 gene Bcl-1 polymorphism, eczema severity and blood level of IL-17, IL-2, 25(OH)D. The final adjustment showed that minor C-allele of the Bcl-1 polymorphism and severe eczema are the strongest predictors of the glucocorticoid resistance.

Acquired Glucocorticoid Resistance Due to Homologous Glucocorticoid Receptor Downregulation: A Modern Look at an Age-Old Problem

For over 70 years, the unique anti-inflammatory properties of glucocorticoids (GCs), which mediate their effects via the ligand-activated transcription factor, the glucocorticoid receptor alpha (GRα), have allowed for the use of these steroid hormones in the treatment of various autoimmune and inflammatory-linked diseases. However, aside from the onset of severe side-effects, chronic GC therapy often leads to the ligand-mediated downregulation of the GRα which, in turn, leads to a decrease in GC sensitivity, and effectively, the development of acquired GC resistance. Although the ligand-mediated downregulation of GRα is well documented, the precise factors which influence this process are not well understood and, thus, the development of an acquired GC resistance presents an ever-increasing challenge to the pharmaceutical industry. Recently, however, studies have correlated the dimerization status of the GRα with its ligand-mediated downregulation. Therefore, the current review will be discussing the major role-players in the homologous downregulation of the GRα pool, with a specific focus on previously reported GC-mediated reductions in GRα mRNA and protein levels, the molecular mechanisms through which the GRα functional pool is maintained and the possible impact of receptor conformation on GC-mediated GRα downregulation.

Disease- and treatment-associated acquired glucocorticoid resistance

The development of resistance to glucocorticoids (GCs) in therapeutic regimens poses a major threat. Generally, GC resistance is congenital or acquired over time as a result of disease progression, prolonged GC treatment or, in some cases, both. Essentially, disruptions in the function and/or pool of the glucocorticoid receptor α (GRα) underlie this resistance. Many studies have detailed how alterations in GRα function lead to diminished GC sensitivity; however, the current review highlights the wealth of data concerning reductions in the GRα pool, mediated by disease-associated and treatment-associated effects, which contribute to a significant decrease in GC sensitivity. Additionally, the current understanding of the molecular mechanisms involved in driving reductions in the GRα pool is discussed. After highlighting the importance of maintaining the level of the GRα pool to combat GC resistance, we present current strategies and argue that future strategies to prevent GC resistance should involve biased ligands with a predisposition for reduced GR dimerization, a strategy originally proposed as the SEMOGRAM-SEDIGRAM concept to reduce the side-effect profile of GCs.

Systemic glucocorticoids: important issues and practical guidelines for the dermatologist

BACKGROUND

The potent anti-inflammatory and immunosuppressive effects of systemic glucocorticoids have led to their wide use in the treatment of dermatologic diseases. However, glucocorticoids have been designated the "archetypal double-edged sword of medicine" as a result of their various potential adverse side effects. Dermatologists face major challenges in their usage and require knowledge of both the risks related to their usage and strategies with which to manage them.

OBJECTIVES

This brief review includes an evidence-based, strategic approach to the general risk management of systemic glucocorticoids with a focus on preventing glucocorticoid-induced osteoporosis (GIOP).

METHODS

We assess which classes of corticosteroid are most likely to provoke allergic cross-reactions and outline the mechanism for glucocorticoid resistance. We examine how glucocorticoids both help and impair normal physiology.

RESULTS

Five reactivity groups are defined, based on the structural and clinical characteristics of glucocorticoids. Tests for allergy reactions and mechanisms for glucocorticoid resistance are described. Guidelines for the prevention and treatment of GIOP are introduced.

CONCLUSION

Glucocorticoids play an important teleologic role in maintaining blood glucose levels adequate for brain function by inducing a catabolic state through the production of carbohydrates at the expense of proteins and fat stores. It is hoped that the various recommendations for the protection of patients treated with systemic glucocorticoids will provide physicians with practical guidelines for prescribing.

Low expression of glucocorticoid receptor alpha isoform in adult immune thrombocytopenia correlates with glucocorticoid resistance

The expression of glucocorticoid receptor (GR) isoforms has been linked to glucocorticoid (GC) resistance in various diseases treated with GC. However, existing data are conflicting in these diseases, and little information is available regarding immune thrombocytopenia (ITP). To further investigate the role of GR isoforms in GC resistance in adult ITP patients, we measured the mRNA expression of GR isoforms (GRα, GRβ, GRγ, GRp) in peripheral blood mononuclear cells (PBMC) from 54 newly diagnosed ITP patients, including GC-sensitive (GCS) and GC-resistant (GCR) patients and 35 healthy volunteers. The GRα and GRβ proteins in PBMC, nuclear factor-κB (NF-κB), and activator protein-1 (AP-1) in the nucleus were detected by Western blotting. Compared to normal subjects, both GRα and GRβ mRNAs were significantly increased in ITP patients (p < 0.05), while there was no significant difference in the mRNA expression of GRγ and GRp. Compared to GCR patients, the expressions of GRα mRNA and GRα protein were significantly higher in GCS patients (p < 0.05). Moreover, no significant difference in the mRNA expression of the GRβ, GRγ, and GRp isoforms was observed between GCS and GCR patients and the GRβ protein could not be detected. Compared to GCS group, the expression of p65/NF-κB was significantly higher in the GCR group (p < 0.05). Overall, we did not find differences in c-Jun/AP-1 protein expression between GCS and GCR patients. In summary, GC resistance in adult ITP patients is associated with a reduced expression of GRα, which may be related with increased NF-κB. GRβ was very low and may not be involved in GC resistance in adult ITP, warranting further exploration.

IL-4 up-regulates epidermal chemotactic, angiogenic, and pro-inflammatory genes and down-regulates antimicrobial genes in vivo and in vitro: relevant in the pathogenesis of atopic dermatitis

Atopic dermatitis (AD) is a common chronic inflammatory skin disease. Although the pathogenesis of AD is not fully understood, we and others have shown that IL-4 plays a key role. In this study we aimed to identify keratinocyte genes regulated by IL-4 that may play important roles in the pathophysiology of AD. HaCat cells were treated with IL-4 at various concentrations for 24h, and PCR gene array on inflammation/autoimmunity was performed three times for analysis of differential gene expression. Of all the 370 genes examined, 32 and 53 genes are up- and down-regulated, respectively. Specifically related to AD, chemokines CCL3L1, CCL8, CCL24, CCL25, CCL26, CXCL6 and CXCL16 are up-regulated by IL-4. Pro-inflammatory factors, such as IL-19, IL-20, IL-1α, IL-12Rβ2, IL-25, IL-31RA, OSMR and nitric oxide synthase 2, are also up-regulated. In addition, IL-4 up-regulates VEGFA, a pro-angiogenic factor. In contrast, antimicrobial peptides (AMPs) or factors involved in APM production, such as IFN-κ, S100s, Toll-like receptors, and several chemokines are down-regulated. Similarly IL-4 also down-regulates TNF-α, lymphotoxin-β, an IgE suppressor, TNFSF18, a T-cells function regulator, and the glucocorticoid receptor. On the in vivo level, real-time RT-PCR on the selected genes confirmed that IL-4 up-regulates chemokines, proinflammatory cytokines while it suppresses AMP production related genes in the skin obtained from IL-4 Tg mice. Detailed examination of these genes will delineate their specific roles in chemotaxis, inflammation, angiogenesis and AMP production, all of which may contribute to the development and progression of AD.