Relationship between expression of glucocorticoid receptor isoforms and glucocorticoid resistance in immune thrombocytopenia

The Glucocorticoid Receptor: Isoforms, Functions, and Contribution to Glucocorticoid Sensitivity

Glucocorticoids exert pleiotropic effects on all tissues to regulate cellular and metabolic homeostasis. Synthetic forms are used therapeutically in a wide range of conditions for their anti-inflammatory benefits, at the cost of dose and duration-dependent side effects. Significant variability occurs between tissues, disease states, and individuals with regard to both the beneficial and deleterious effects. The glucocorticoid receptor (GR) is the site of action for these hormones and a vast body of work has been conducted understanding its function. Traditionally, it was thought that the anti-inflammatory benefits of glucocorticoids were mediated by transrepression of pro-inflammatory transcription factors, while the adverse metabolic effects resulted from direct transactivation. This canonical understanding of the GR function has been brought into question over the past 2 decades with advances in the resolution of scientific techniques, and the discovery of multiple isoforms of the receptor present in most tissues. Here we review the structure and function of the GR, the nature of the receptor isoforms, and the contribution of the receptor to glucocorticoid sensitivity, or resistance in health and disease.

Trimethylamine-N-oxide (TMAO) and basic fibroblast growth factor (bFGF) are possibly involved in corticosteroid resistance in adult patients with immune thrombocytopenia

PURPOSE

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by accelerated platelet clearance. Gut dysbiosis was associated with its pathogenesis, but the underlying mechanisms have not been fully elucidated. Patients with ITP exhibit varying degrees of responsiveness to corticosteroid treatment. Therefore, prognostic indexes for corticosteroid responsiveness in ITP could offer valuable guidance for clinical practices.

METHODS

The present study examined the signature of six types of gut-microbiota metabolites and forty-eight types of cytokines, chemokines, and growth factors and their clinical significance in patients with ITP.

RESULTS

Both patients with good and poor corticosteroid responsiveness exhibited significantly elevated/suppressed secretion of twenty-two cyto(chemo)kins/growth factors in comparison to healthy controls. Additionally, patients with ITP demonstrated a significant decrease in plasma levels of trimethylamine-N-oxide (TMAO), which was found to be negatively correlated to circulating platelet counts, and positively correlated with Interleukin (IL)-1β and IL-18. Notably, patients who exhibited poor response to corticosteroid treatment displayed elevated levels of TMAO and basic fibroblast growth factor (bFGF) in comparison to responders. Additionally, we found that the amalgamation of TMAO, bFGF and interleukin (IL)-13 could serve as a valuable prognostic tool for predicting CS responsiveness.

CONCLUSION

Patients with ITP were characterized overall by an imbalanced secretion of cyto(cheo)kins/growth factors and inadequate levels of TMAO. The varying degrees of responsiveness to corticosteroid treatment can be attributed to different profiles of basic FGF and TMAO that might be related to overburdened oxidative stress and inflammasome overactivation, and ultimately mediate corticosteroid resistance.

Association between glucocorticoid receptor beta and steroid resistance: A systematic review

BACKGROUND

Glucocorticoids are the most commonly used anti-inflammatory drugs for a variety of diseases, despite the fact that resistance to them is growing in a number of conditions. There is currently no biomarker that can be used to identify steroid resistance. According to a number of studies, an overexpression of the glucocorticoid receptor beta (GR-β) isoform is associated with steroid-resistant illness. Our goal is to find out whether or not steroid-resistant disorders are associated with an increased level of GR-β expression.

METHODS

We conducted searches in the databases of Web of Science and PubMed until January 17, 2023. This systematic review was done according to the preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The Joanna Briggs Institute Appraisal scale was used to assess the quality of the included studies.

RESULTS

After the initial search, we identified 556 papers and finally included 20 studies. Twelve of these studies found an elevated level of GR-β in the steroid resistant group. All five studies on asthma, two out of three on nasal polyps, both studies on ulcerative colitis found an up regulation of GR-β in steroid resistant group as compared to steroid-sensitive groups. GR-β was also shown to be elevated in patients with allergic rhinitis, Crohn's disease and rheumatoid arthritis. In the majority of the investigations, higher levels of GR-β were identified in peripheral blood mononuclear cells through the use of reverse transcription polymerase chain reaction.

CONCLUSION

GR-β was associated with steroid-resistant diseases. It was overexpressed in steroid-resistant diseases and has the potential to be used as a biomarker for disorders involving steroid resistance.

Correlation between nuclear expression of heat shock protein 90 in dermis and glucocorticoid resistance in bullous dermatosis

BACKGROUND

bullous dermatosis is a group of skin diseases that occur on the skin and mucous membrane, with blister and bulla as basic damage, mainly including pemphigus and bullous pemphigoid. Glucocorticoid (GC) is still the preferred drug for its treatment, but some patients respond poorly to GC and even develop glucocorticoid resistance (GCR). However, at present about the disease the understanding of the mechanisms for GCR is limited.

OBJECTIVE

This study attempted to investigate the molecular mechanism of GCR in bullous dermatosis with heat shock proteins 90 (HSP90) and glucocorticoid receptor (GR) as molecular targets.

METHODS

In this study, flow cytometry was used to measure and analyze the expression of HSP90 and GR in the lesions of patients with glucocorticoid-resistant bullosa dermatosis. Immunohistochemistry and immunofluorescence were used to observe the expression distribution and cell localization of HSP90 and GR.

RESULTS

The expression of HSP90 in skin lesions of GCR group was significantly higher than that of glucocorticoid-sensitive (GCS) group, while the expression level of GR was lower than that of GCS group. In the epidermis, the expression and distribution of HSP90 were not different between the GCR group and the GCS group. And in the dermis, HSP90 and GR were more likely to be expressed in the nucleus in the GCR group.

CONCLUSION

The overexpression and nuclear distribution of HSP90 may be related to the occurrence of GCR in patients with bullous dermatosis. And this correlation is more likely to occur in the dermis than in the epidermis.

Steroid regulation: An overlooked aspect of tolerance and chronic rejection in kidney transplantation

Steroid conversion (HSD11B1, HSD11B2, H6PD) and receptor genes (NR3C1, NR3C2) were examined in kidney-transplant recipients with "operational tolerance" and chronic rejection (CR), independently and within the context of 88 tolerance-associated genes. Associations with cellular types were explored. Peripheral whole-blood gene-expression levels (RT-qPCR-based) and cell counts were adjusted for immunosuppressant drug intake. Tolerant (n = 17), stable (n = 190) and CR patients (n = 37) were compared. Healthy controls (n = 14) were used as reference. The anti-inflammatory glucocorticoid receptor (NR3C1) and the cortisol-activating HSD11B1 and H6PD genes were up-regulated in CR and were lowest in tolerant patients. The pro-inflammatory mineralocorticoid gene (NR3C2) was downregulated in stable and CR patients. NR3C1 was associated with neutrophils and NR3C2 with T-cells. Steroid conversion and receptor genes, alone, enabled classification of tolerant patients and were major contributors to gene-expression signatures of both, tolerance and CR, alongside known tolerance-associated genes, revealing a key role of steroid regulation and response in kidney transplantation.

Peripheral sensitivity to steroids revisited

Resistance to steroid hormones presents a serious problem with respect to their mass use in therapy. It may be caused genetically by mutation of genes involved in hormonal signaling, not only steroid receptors, but also other players in the signaling cascade as co-regulators and other nuclear factors, mediating the hormone-born signal. Another possibility is acquired resistance which may develop under long-term steroid treatment, of which a particular case is down regulation of the receptors. In the review recent knowledge is summarized on the mechanism of main steroid hormone action, pointing to already proven or potential sites causing steroid resistance. We have attempted to address following questions: 1) What does stay behind differences among patients as to their response to the (anti)steroid treatment? 2) Why do various tissues/cells respond differently to the same steroid hormone though they contain the same receptors? 3) Are such differences genetically dependent? The main attention was devoted to glucocorticoids as the most frequently used steroid therapeutics. Further, androgen insensitivity is discussed with a particular attention to acquired resistance to androgen deprivation therapy of prostate cancer. Finally the potential causes are outlined of breast and related cancer(s) resistance to antiestrogen therapy.