Anti-inflammatory glucocorticoids: changing concepts

Dexamethasone weakens the respiratory effects of pro-inflammatory cytokine TNF-α in rat

The goal of the current study was to identify the role of the glucocorticoids in the respiratory effects of proinflammatory cytokines. For this purpose intravenous injections of TNF-α were used in anesthetized spontaneously breathing rats before and after pretreatment of dexamethasone, a synthetic steroid with predominant glucocorticoid activity. Dexamethasone was injected intraperitoneally at a dose of 1 mg/kg. TNF-α was administrated into the tail vein at a dose of 40 mg/kg. We found that dexamethasone pretreatment eliminated the cytokine-induced increase in pulmonary ventilation and decrease in the hypoxic ventilatory response. Dexamethasone had a pronounced rapid effect on the respiratory activity of TNF-α as early as 30 minutes after administration. Therefore, we assume that this mechanism of action of dexamethasone was non-genomic, associated with the blocking of secondary mediators of the cytokine response.

A cluster-randomized trial of water, sanitation, handwashing and nutritional interventions on stress and epigenetic programming

A regulated stress response is essential for healthy child growth and development trajectories. We conducted a cluster-randomized trial in rural Bangladesh (funded by the Bill & Melinda Gates Foundation, ClinicalTrials.gov NCT01590095) to assess the effects of an integrated nutritional, water, sanitation, and handwashing intervention on child health. We previously reported on the primary outcomes of the trial, linear growth and caregiver-reported diarrhea. Here, we assessed additional prespecified outcomes: physiological stress response, oxidative stress, and DNA methylation (N = 759, ages 1-2 years). Eight neighboring pregnant women were grouped into a study cluster. Eight geographically adjacent clusters were block-randomized into the control or the combined nutrition, water, sanitation, and handwashing (N + WSH) intervention group (receiving nutritional counseling and lipid-based nutrient supplements, chlorinated drinking water, upgraded sanitation, and handwashing with soap). Participants and data collectors were not masked, but analyses were masked. There were 358 children (68 clusters) in the control group and 401 children (63 clusters) in the intervention group. We measured four F2-isoprostanes isomers (iPF(2α)-III; 2,3-dinor-iPF(2α)-III; iPF(2α)-VI; 8,12-iso-iPF(2α)-VI), salivary alpha-amylase and cortisol, and methylation of the glucocorticoid receptor (NR3C1) exon 1F promoter including the NGFI-A binding site. Compared with control, the N + WSH group had lower concentrations of F2-isoprostanes isomers (differences ranging from -0.16 to -0.19 log ng/mg of creatinine, P < 0.01), elevated post-stressor cortisol (0.24 log µg/dl; P < 0.01), higher cortisol residualized gain scores (0.06 µg/dl; P = 0.023), and decreased methylation of the NGFI-A binding site (-0.04; P = 0.037). The N + WSH intervention enhanced adaptive responses of the physiological stress system in early childhood.

Analysis of Key Genes and miRNA-mRNA Networks Associated with Glucocorticoids Treatment in Chronic Obstructive Pulmonary Disease

Background

Some patients with chronic obstructive pulmonary disease (COPD) benefit from glucocorticoid (GC) treatment, but its mechanism is unclear.

Objective

With the help of the Gene Expression Omnibus (GEO) database, the key genes and miRNA-mRNA related to the treatment of COPD by GCs were discussed, and the potential mechanism was explained.

Methods

The miRNA microarray dataset (GSE76774) and mRNA microarray dataset (GSE36221) were downloaded, and differential expression analysis were performed. Gene Ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed on the differentially expressed genes (DEGs). The protein interaction network of the DEGs in the regulatory network was constructed with the STRING database, and the key genes were screened through Cytoscape. Potential downstream target genes regulated by differentially expressed miRNAs (DEMs) were predicted by the miRWalk3.0 database, and miRNA-mRNA regulatory networks were constructed. Finally, some research results were validated.

Results

① Four DEMs and 83 DEGs were screened; ② GO and KEGG enrichment analysis mainly focused on the PI3K/Akt signalling pathway, ECM receptor interaction, etc.; ③ CD2, SLAMF7, etc. may be the key targets of GC in the treatment of COPD; ④ 18 intersection genes were predicted by the mirwalk 3.0 database, and 9 pairs of miRNA-mRNA regulatory networks were identified; ⑤ The expression of miR-320d-2 and TFCP2L1 were upregulated by dexamethasone in the COPD cell model, while the expression of miR-181a-2-3p and SLAMF7 were downregulated.

Conclusion

In COPD, GC may mediate the expression of the PI3K/Akt signalling pathway through miR-181a-2-3p, miR-320d-2, miR-650, and miR-155-5p, targeting its downstream signal factors. The research results provide new ideas for RNA therapy strategies of COPD, and also lay a foundation for further research.

Molecular mechanisms of the stress-induced regulation of the inflammatory response in fish

Stressors in the environment of aquatic organisms can profoundly affect their immune system. The stress response in fish involves the activation of the hypothalamus-pituitary-interrenal (HPI) axis, leading to the release of several stress hormones, among them glucocorticoids, such as cortisol, which bind and activate corticosteroid receptors, namely the glucocorticoid receptor (GR) and mineralocorticoid receptor (MR). These receptors are highly expressed on immune cells, thereby allowing stress to have a potent effect that is classically considered to suppress immune function. In this review, we highlight the conserved structure and function of GR and MR among vertebrates and describe their role in modulating inflammation by regulating the expression of pro-inflammatory and anti-inflammatory genes. In particular, the involvement of MR during inflammation is reviewed, which in many studies has been shown to be immune-enhancing. In recent years, the use of zebrafish as a model organism has opened up new possibilities to study the effects of stress on inflammation, making it possible to investigate knockout lines for MR and/or GR, in combination with transgenic models with fluorescently labeled leukocyte subpopulations that enable the visualization and manipulation of these immune cells. The potential roles of other hormones of the HPI axis, such as corticotrophin-releasing hormone (Crh) and adrenocorticotropic hormone (Acth), in immune modulation are also discussed. Overall, this review highlights the need for further research to elucidate the specific roles of GR, MR and other stress hormones in regulating immune function in fish. Understanding these mechanisms will contribute to improving fish health and advancing our knowledge of stress signalling.

Prediction and prognostic potential of NR3C1 gene expression level in DLBCL patients

Objective: Diffuse Large B-Cell Lymphoma (DLBCL) is a common and frequently occurring subtype of Non-Hodgkin Lymphoma (NHL). The effective treatment and prognosis of DLBCL are still urgently needed to be explored. This article aims to shed light on the connection between DLBCL survival and NR3C1 expression levels. Methods: First, we divided the 952 DLBCL patients into an NR3C1 high-expression group and an NR3C1 low-expression group and compared the baseline characteristics of the two groups. Second, we used multivariate analysis to predict the dependent variable for age, pathology, ECOG score, lactate dehydrogenase (LDH) ratio, and NR3C1 expression level. Finally, we analyzed the progression-free survival (PFS) and overall survival rate (OS) of DLBCL patients with high or low NR3C1 expression. Results: DLBCL patients with high NR3C1 expression had a better prognosis than those with low NR3C1 expression (OS, P < 0.0001). In DLBCL patients of CHOP therapy, high NR3C1 expression was associated with a good survival prognosis in OS (OS, P = 0.028). Conclusion: In multivariate analysis, NR3C1 high expression was an independent prognostic factor that predicted a longer OS of DLBCL (OS, P = 0.0003). NR3C1 is considered an independent predictor of DLBCL patients and can be used as a biomarker for the prognosis of DLBCL.

Epigenetic and transcriptional regulation of CCL17 production by glucocorticoids in arthritis

Glucocorticoids (GCs) are potent anti-inflammatory agents and are broadly used in treating rheumatoid arthritis (RA) patients, albeit with adverse side effects associated with long-term usage. The negative consequences of GC therapy provide an impetus for research into gaining insights into the molecular mechanisms of GC action. We have previously reported that granulocyte-macrophage colony-stimulating factor (GM-CSF)-induced CCL17 has a non-redundant role in inflammatory arthritis. Here, we provide molecular evidence that GCs can suppress GM-CSF-mediated upregulation of IRF4 and CCL17 expression via downregulating JMJD3 expression and activity. In mouse models of inflammatory arthritis, GC treatment inhibited CCL17 expression and ameliorated arthritic pain-like behavior and disease. Significantly, GC treatment of RA patient peripheral blood mononuclear cells ex vivo resulted in decreased CCL17 production. This delineated pathway potentially provides new therapeutic options for the treatment of many inflammatory conditions, where GCs are used as an anti-inflammatory drug but without the associated adverse side effects.

Differential regulation of BIRC2 and BIRC3 expression by inflammatory cytokines and glucocorticoids in pulmonary epithelial cells

Roles for the baculoviral inhibitor of apoptosis repeat-containing (BIRC) genes, BIRC2 and BIRC3, may include signaling to the inflammatory transcription factor, nuclear factor-κB (NF-κB) and protection from cell death. However, distinct functions for each BIRC are not well-delineated. Given roles for the epithelium in barrier function and host defence, BIRC2 and BIRC3 expression was characterized in pulmonary epithelial cell lines and primary human bronchial epithelial cells (pHBECs) grown as undifferentiated cells in submersion culture (SC) or as highly differentiated cells at air-liquid interface (ALI). In A549 cells, interleukin-1β (IL1B) and tumor necrosis factor α (TNF) induced BIRC3 mRNA (~20-50-fold), with maximal protein expression from 6-24 h. Similar effects occurred in BEAS-2B and Calu-3 cells, as well as SC and ALI pHBECs. BIRC2 protein was readily detected in unstimulated cells, but was not markedly modulated by IL1B or TNF. Glucocorticoids (dexamethasone, budesonide) modestly increased BIRC3 mRNA and protein, but showed little effect on BIRC2 expression. In A549 cells, BIRC3 mRNA induced by IL1B was unchanged by glucocorticoids and showed supra-additivity with TNF-plus-glucocorticoid. Supra-additivity was also evident for IL1B-plus-budesonide induced-BIRC3 in SC and ALI pHBECs. Using A549 cells, IL1B- and TNF-induced BIRC3 expression, and to a lesser extent, BIRC2, was prevented by NF-κB inhibition. Glucocorticoid-induced BIRC3 expression was prevented by silencing and antagonism of the glucocorticoid receptor. Whereas TNF, but not IL1B, induced degradation of basal BIRC2 and BIRC3 protein, IL1B- and TNF-induced BIRC3 protein remained stable. Differential regulation by cytokines and glucocorticoids shows BIRC2 protein expression to be consistent with roles in rapid signaling events, whereas cytokine-induced BIRC3 may be more important in later effects. While TNF-induced degradation of both BIRCs may restrict their activity, cytokine-enhanced BIRC3 expression could prime for its function. Finally, shielding from glucocorticoid repression, or further enhancement by glucocorticoid, may indicate a key protective role for BIRC3.

Preliminary exploration of method for screening efficacy markers compatibility in TCM prescriptions based on Q-markers: Anti-inflammatory activity of Dachaihu decoction as an example

ETHNOPHARMACOLOGICAL RELEVANCE

Dachaihu Decoction (DD), a classic Chinese herbal prescription, is composed of radix of Bupleurum chinense DC. (Chaihu), radix of Scutellaria baicalensis Georgi (Huangqin), radix of Paeonia lactiflora Pall. (Baishao), rhizoma of Pinellia ternata (Thunb.) Breit. (Banxia), fructus of Citrus aurantium L. (Zhishi), rhizoma of Zingiber officinale Rosc. (Shengjiang), fructus of Ziziphus jujuba Mill. (Dazao) and rhizoma of Rheum officinale Baill. (Dahuang). DD has the traditional effects of soothing the liver, relieving depression and clearing heat from the stomach, and is mainly used to treat heat stagnation in the liver and stomach.

AIM OF THE STUDY

Dachaihu decoction (DD), a classic prescription commonly used in clinical practice for the treatment of pancreatitis and cholecystitis. Although its pharmacological effects are clear, the efficacy components and mechanism of action remain intricate and difficult to clarify.

MATERIALS AND METHODS

The action targets and components of the anti-inflammatory activity of DD were predicted by network pharmacology; the effective components and targets were verified by HPLC and qPCR; the efficacy markers of DD were further screened by in vitro experiments; the pharmacological value of DD and its components compatibility were evaluated by in vitro experiments.

RESULTS

The key targets MMP9, JAK2, MAP2K1 and NR3C1 were screened by network pharmacology; HPLC analysis showed that paeoniflorin, naringin, hesperidin, neohesperidin, baicalin, wogonoside, baicalein and saikosaponin B₂ were identified as potential efficacy markers of DD; molecular docking combined with qPCR verification suggested that baicalin, naringin, neohesperidin, hesperidin and baicalein and wogonoside had certain ability to regulate above targets; in vitro studies revealed that paeoniflorin, naringin, hesperidin, neohesperidin, baicalin, wogonoside, baicalein and saikosaponin B₂ could inhibit the release of NO, pancreatic lipase and α-glucosidase; after comprehensive comparison and analysis, naringin, hesperidin, neohesperidin, baicalin, wogonoside, baicalein and saikosaponin B₂ were selected as the efficacy markers of DD; in vivo studies indicated that DD and its efficacy markers (components compatibility) had definite therapeutic effects on guinea pigs with cholecystitis.

CONCLUSIONS

The efficacy markers of DD including naringin, hesperidin, neohesperidin, baicalin, wogonoside, baicalein and saikosaponin B₂ can be used as components compatibility to exert anti-inflammatory activity. In addition, a method for obtaining the compatibility of efficacy markers by simplifying the prescription is initially established.

Glucocorticoids increase tissue cell protection against pore-forming toxins from pathogenic bacteria

Many species of pathogenic bacteria damage tissue cells by secreting toxins that form pores in plasma membranes. Here we show that glucocorticoids increase the intrinsic protection of tissue cells against pore-forming toxins. Dexamethasone protected several cell types against the cholesterol-dependent cytolysin, pyolysin, from Trueperella pyogenes. Dexamethasone treatment reduced pyolysin-induced leakage of potassium and lactate dehydrogenase, limited actin cytoskeleton alterations, reduced plasma membrane blebbing, and prevented cytolysis. Hydrocortisone and fluticasone also protected against pyolysin-induced cell damage. Furthermore, dexamethasone protected HeLa and A549 cells against the pore-forming toxins streptolysin O from Streptococcus pyogenes, and alpha-hemolysin from Staphylococcus aureus. Dexamethasone cytoprotection was not associated with changes in cellular cholesterol or activating mitogen-activated protein kinase (MAPK) cell stress responses. However, cytoprotection was dependent on the glucocorticoid receptor and 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR). Collectively, our findings imply that glucocorticoids could be exploited to limit tissue damage caused by pathogens secreting pore-forming toxins.

Recent Advances in Nanomaterials for Asthma Treatment

Asthma is a chronic airway inflammatory disease with complex mechanisms, and these patients often encounter difficulties in their treatment course due to the heterogeneity of the disease. Currently, clinical treatments for asthma are mainly based on glucocorticoid-based combination drug therapy; however, glucocorticoid resistance and multiple side effects, as well as the occurrence of poor drug delivery, require the development of more promising treatments. Nanotechnology is an emerging technology that has been extensively researched in the medical field. Several studies have shown that drug delivery systems could significantly improve the targeting, reduce toxicity and improve the bioavailability of drugs. The use of multiple nanoparticle delivery strategies could improve the therapeutic efficacy of drugs compared to traditional delivery methods. Herein, the authors presented the mechanisms of asthma development and current therapeutic methods. Furthermore, the design and synthesis of different types of nanomaterials and micromaterials for asthma therapy are reviewed, including polymetric nanomaterials, solid lipid nanomaterials, cell membranes-based nanomaterials, and metal nanomaterials. Finally, the challenges and future perspectives of these nanomaterials are discussed to provide guidance for further research directions and hopefully promote the clinical application of nanotherapeutics in asthma treatment.

[Effective intranasal GCS application strategy of mono and combines forms in treating patients, suffering from allergic rhinitis. Evidence-based medicine to help a practitioner]

OBJECTIVE

To summarize effective intranasal glucocorticosteroids (GCS) application strategies in treatment of patients, suffering from allergic rhinitis (depending on disease type), based on actual research results. Current study determines the place of fixed intranasal GCS and topic antihistamine medication combination, specifically azelastine and mometasone furoate, as a first line of choice therapy in treatment of patients, suffering from allergic rhinitis. Effective application of stage therapy allows us establish control over allergic inflammation and significantly decrease pharmaceutical load in cases of patients, suffering from allergic rhinitis.

Packaging and Delivery of Asthma Therapeutics

Asthma is a life-altering, chronic disease of heterogenous origin that features a complex interplay of immune and environmental signaling. Although very little progress has been made in prevention, diverse types of medications and delivery systems, including nanoscale systems, have been or are currently being developed to control airway inflammation and prevent exacerbations and fibrosis. These medications are delivered through mechanical methods, with various inhalers (with benefits and drawbacks) existing, and new types offering some variety in delivery. Of particular interest is the progress being made in nanosized materials for efficient penetration into the epithelial mucus layer and delivery into the deepest parts of the lungs. Liposomes, nanoparticles, and extracellular vesicles, both natural and synthetic, have been explored in animal models of asthma and have produced promising results. This review will summarize and synthesize the latest developments in both macro-(inhaler) and micro-sized delivery systems for the purpose of treating asthma patients.

Human Lung Mast Cells Impair Corticosteroid Responsiveness in Human Airway Smooth Muscle Cells

The mechanisms underlying corticosteroid insensitivity in severe asthma have not been elucidated although some indirect clinical evidence points toward a role of mast cells. Here, we tested the hypothesis that mast cells can drive corticosteroid insensitivity in airway smooth muscle cells, a key player in asthma pathogenesis. Conditioned media from resting or FcεR1-activated human lung mast cells were incubated with serum-deprived ASM cells (1:4 dilution, 24 h) to determine their impact on the anti-inflammatory action of fluticasone on ASM cell chemokine expression induced by TNFα (10 ng/ml). Conditioned media from FcεR1-activated mast cells (but not that from non-activated mast cells or control media) significantly reduced the ability of 100 nM fluticasone to suppress ASM TNFα-dependent CCL5 and CXCL10 production at both mRNA and protein levels. In contrast, fluticasone inhibition of CXCL-8 production by TNFα was still preserved in the presence of activated mast cell conditioned media. Transcriptomic analysis validated by individual qPCR assays revealed that activated mast cell conditioned media dramatically reduced the number of anti-inflammatory genes induced by fluticasone in ASM cells. Our study demonstrates for the first time that conditioned media from FcεR1-activated mast cells blunt the anti-inflammatory action of corticosteroids in ASM cells by altering their transactivation properties. Because infiltration of mast cells within the ASM bundles is a defining feature of asthma, mast cell-derived mediators may contribute to the glucocorticoid insensitivity present in severe asthma.

SARS-CoV-2 attenuates corticosteroid sensitivity by suppressing DUSP1 expression and activating p38 MAPK pathway

The efficacy of corticosteroids and its use for the treatment of SARS-CoV-2 infections is controversial. In this study, using data sets of SARS-CoV-2 infected lung tissues and nasopharyngeal swabs, as well as in vitro experiments, we show that SARS-CoV-2 infection significantly downregulates DUSP1 expression. This downregulation of DUSP1 could be the mechanism regulating the enhanced activation of MAPK pathway as well as the reported steroid resistance in SARS-CoV-2 infection. Moreover, chloroquine, an off labeled COVID-19 drug is able to induce DUSP1 and attenuate MAPK pathway; and is expected to improve sensitivity to steroid treatment. However, further mechanistic studies are required to confirm this effect.

The effect of stress on the transcriptomes of circulating immune cells in patients with Gulf War Illness

AIMS

In an effort to gain further insight into the underlying mechanisms tied to disease onset and progression of Gulf War Illness (GWI), our team evaluated GWI patient response to stress utilizing RNA-Seq.

MAIN METHODS

The protocol included blood collection before exercise challenge (baseline), at maximal exertion, and after exercise challenge (recovery - four hours post-exercise challenge). Peripheral blood mononuclear cell (PBMC) transcriptomics data were analyzed to understand why GWI patients process stressors differently from their healthy counterparts.

KEY FINDINGS

Our findings validate previously identified dysregulation of immune and inflammatory pathways among GWI patients as well as highlight novel immune and inflammatory markers of disease activity. These results provide a foundation for future research efforts in understanding GWI pathophysiology and creating targeted treatments.

SIGNIFICANCE

Gulf War Illness is a complex, chronic, and debilitating multi-system illness impacting 25%-30% of the U.S. troops deployed to the 1990-1991 Gulf War. The condition is characterized by medically unexplained fatigue and affects multiple organ systems. Because the underlying mechanisms are largely unknown, patients receive symptom-based treatment, rather than targeting fundamental biological processes. To the best of our knowledge, this is the first study that applies RNA-Seq to analyze the effect of GWI, and the response to stressors in GWI, on the transcriptomic changes in circulating immune cells.

Epithelial deletion of the glucocorticoid receptor (Nr3c1) protects the mouse intestine against experimental inflammation

BACKGROUND AND PURPOSE

Glucocorticoids are the first line treatment for the flare-ups of inflammatory bowel disease, but they have significant limitations. The objective of this study is to investigate whether glucocorticoid epithelial actions contribute to such limitations.

EXPERIMENTAL APPROACH

Intestinal epithelium glucocorticoid receptor knockout mice (Nr3c1^ΔIEC ) received dextran sulfate sodium (DSS) to induce colitis. Inflammatory status was assessed by morphological and biochemical methods, and corticoid production was measured in colonic explants. Some mice were administered budesonide.

KEY RESULTS

After 7 days of DSS Nr3c1^ΔIEC , mice exhibited 23.1% lower disease activity index (DAI) and 37% lower diarrheal score than WT mice, with decreased weight loss in days 5-7 of colitis, attenuated tissue damage, reduced colonic expression of S100A9 and STAT3 phosphorylation, and a better overall state. Ki67 immunoreactivity was increased at the crypt base, indicating enhanced epithelial proliferation. Mice administered budesonide (6 μg·day^-1 PO) showed modest antiinflammatory effects but increased weight loss, which was prevented in knockout mice. Epithelial deletion of the glucocorticoid receptor also protected mice in a protracted colitis protocol. Conversely, knockout mice presented a worse status compared to the control group at 1 day post DSS. In a separate experiment, colonic corticosterone production was shown to be significantly increased in knockout mice at 7 days of colitis but not at earlier stages.

CONCLUSIONS AND IMPLICATIONS

The intestinal epithelial glucocorticoid receptor has deleterious effects in experimental colitis induced by DSS, probably related to inhibition of epithelial proliferative responses leading to impaired wound healing and reduced endogenous corticosterone production.

Pentacyclic triterpene compounds from loquat leaves reduce skin inflammation and epidermal hyperplasia in psoriasis via inhibiting the Th17 cells

Psoriasis is a refractory inflammatory skin disease affecting 2 %-3 % of the world population, characterized by the infiltration and hyper-proliferation of inflammatory cells and aberrant differentiation of keratinocytes. Targeting the IL-23/ Th17 axis has been well recognized as a promising therapeutic strategy, as the IL-23/ Th17 signal plays a vital role in the pathology of psoriasis. Three pentacyclic triterpene compounds isolated from loquat leaves have been reported with significant inhibitory effects on RORγt transcription activity and Th17 cell differentiation, and excellent performance in preventing lupus nephritis pathogenesis. However, the potential effects of these pentacyclic triterpene compounds on psoriasis remain unknown. In this study, we demonstrated the potent therapeutic effects of these pentacyclic triterpene compounds on psoriasis. These three pentacyclic triterpene compounds significantly alleviated skin inflammation as well as aberrant keratinocyte proliferation in an imiquimod-induced mouse psoriasis model. These compounds also inhibited the infiltration of immune cells and the level of pro-inflammatory cytokine in the dermis, as well as the cells number and changed the cytokine profiling expression of Th17 cells. These compounds could reduce the amount of CD4⁺ and CD8⁺ T cells in local lymph node, but not in spleen, which is different from hydrocortisone, the positive control treatment. These results suggest better performance of these compounds than steroids on treating psoriasis with less side effects on the integrated immune system. In summary, our findings uncover the potent therapeutic effects of pentacyclic triterpene compounds on psoriasis, providing potential candidate compounds for drug development.

Insights into glucocorticoid responses derived from omics studies

Glucocorticoid drugs are commonly used in the treatment of several conditions, including autoimmune diseases, asthma and cancer. Despite their widespread use and knowledge of biological pathways via which they act, much remains to be learned about the cell type-specific mechanisms of glucocorticoid action and the reasons why patients respond differently to them. In recent years, human and in vitro studies have addressed these questions with genomics, transcriptomics and other omics approaches. Here, we summarize key insights derived from omics studies of glucocorticoid response, and we identify existing knowledge gaps related to mechanisms of glucocorticoid action that future studies can address.

Important lessons learned from studies on the pharmacology of glucocorticoids in human airway smooth muscle cells: Too much of a good thing may be a problem

Glucocorticoids (GCs) are the treatment of choice for chronic inflammatory diseases such as asthma. Despite proven effective anti-inflammatory and immunosuppressive effects, long-term and/or systemic use of GCs can potentially induce adverse effects. Strikingly, some recent experimental evidence suggests that GCs may even exacerbate some disease outcomes. In asthma, airway smooth muscle (ASM) cells are among the targets of GC therapy and have emerged as key contributors not only to bronchoconstriction, but also to airway inflammation and remodeling, as implied by experimental and clinical evidence. We here will review the beneficial effects of GCs on ASM cells, emphasizing the differential nature of GC effects on pro-inflammatory genes and on other features associated with asthma pathogenesis. We will also summarize evidence describing how GCs can potentially promote pro-inflammatory and remodeling features in asthma with a specific focus on ASM cells. Finally, some of the possible solutions to overcome these unanticipated effects of GCs will be discussed.

Shifts in the gut microbiota of mice in response to dexamethasone administration

Glucocorticoids (GCs) are an important anti-inflammatory drug, used widely, regardless of its side effects. GCs can affect intestinal flora directly or indirectly, though few studies have focused on the changes of gut microbiota composition. In this study, ICR mice were randomly divided into three groups, gavage administration with saline, and different doses of dexamethasone (DEX): 0.1 mg/kg and 1 mg/kg. Five days later, the microbial diversity of the colon contents was analyzed. A significant loss in weight was observed in the DEX1.0 group as compared with the control group (P = 0.011). The gut microbiota richness (ACE, P = 0.01; Chao, P = 0.013) and diversity (Shannon, P = 0.035; Simpson, P = 0.032) were decreased in DEX group. The proportions of genus Butyricicoccus, Oscillibacter, Anaerotruncus, Ruminiclostridium, Ruminococcaceae, and Lachnospiraceae were the most abundant and predominant followed by Lactobacillus, Pseudomonas, and Enterorhabdus. Dex administration led to changes in the liver/body ratio and spleen/body ratio. The results obtained from our study indicate that DEX can decrease the level of WBC and change the structure of the gut microbiota composition; moreover, the results of this study provide new insight into alleviating the clinical side effects of GC therapy.

Silencing of microRNA-517a induces oxidative stress injury in melanoma cells via inactivation of the JNK signaling pathway by upregulating CDKN1C

Background

Melanoma is notoriously resistant to current treatments, and less than 25% of metastatic melanoma cases respond to existing therapies. Growing evidence has shown that microRNAs (miRNAs) play a vital role in the prognosis of melanoma. MiR-517a has been implicated in many types of cancer; however, its expressional features and potential biological functions in melanoma remain unclear. The present study aimed to investigate the possible effects of miR-517a on oxidative stress (OS) in melanoma cells.

Methods

miR-517a expression in melanoma was determined using RT-qPCR. After treatment with different concentrations of H₂O₂, cell viability was determined in order to identify the most appropriate H₂O₂ concentration. Through loss and gain of function experiments, the interactions between miR-517a, the cyclin dependent kinase inhibitor 1C (CDKN1C) and the c-Jun NH2-terminal kinase (JNK) signaling pathway, as well as their roles in OS of melanoma cells were identified. Moreover, the expression of Cleaved Caspase-3, extent of ERK1/2 phosphorylation, Bax/Bcl-2 ratio, levels of T-AOC, ROS and MDA, and SOD activity were also tested. Finally, melanoma cell viability and apoptosis were detected.

Results

MiR-517a was upregulated, while CDKN1C was downregulated in melanoma tissues and cells. MiR-517a targets CDKN1C and consequently reduced its expression. Inhibition of miR-517a was shown to increase Cleaved Caspase-3 expression, Bax/Bcl-2 ratio, levels of ROS and MDA, as well as cell apoptosis but decrease extent of ERK1/2 phosphorylation, T-AOC levels, SOD activity, along with cell proliferation and mitochondrial membrane potential.

Conclusions

Overall, silencing miR-517a results in upregulated CDKN1C expression, and inhibited JNK signaling pathway activation, consequently promoting OS in melanoma cells.

Effects of aging on the motor, cognitive and affective behaviors, neuroimmune responses and hippocampal gene expression

The known effects of aging on the brain and behavior include impaired cognition, increases in anxiety and depressive-like behaviors, and reduced locomotor activity. Environmental exposures and interventions also influence brain functions during aging. We investigated the effects of normal aging under controlled environmental conditions and in the absence of external interventions on locomotor activity, cognition, anxiety and depressive-like behaviors, immune function and hippocampal gene expression in C57BL/6 mice. Healthy mice at 4, 9, and 14 months of age underwent behavioral testing using an established behavioral battery, followed by cellular and molecular analysis using flow cytometry, immunohistochemistry, and quantitative PCR. We found that 14-month-old mice showed significantly reduced baseline locomotion, increased anxiety, and impaired spatial memory compared to younger counterparts. However, no significant differences were observed for depressive-like behavior in the forced-swim test. Microglia numbers in the dentate gyrus, as well as CD8+ memory T cells increased towards late middle age. Aging processes exerted a significant effect on the expression of 43 genes of interest in the hippocampus. We conclude that aging is associated with specific changes in locomotor activity, cognition, anxiety-like behaviors, neuroimmune responses and hippocampal gene expression.

The Gene Expression Biomarkers for Chronic Obstructive Pulmonary Disease and Interstitial Lung Disease

COPD (chronic obstructive pulmonary disease) and ILD (interstitial lung disease) are two common respiratory diseases. They share similar clinical traits but require different therapeutic treatments. Identifying the biomarkers that are differentially expressed between them will not only help the diagnosis of COPD and ILD, but also provide candidate drug targets that may facilitate the development of new treatment for COPD and ILD. Due to the irreversible complex pathological changes of COPD, there are very limited therapeutic options for COPD patients. In this study, we analyzed the gene expression profiles of two datasets: one training dataset that includes 144 COPD patients and 194 ILD patients, and one test dataset that includes 75 COPD patients and 61 ILD patients. Advanced feature selection methods, mRMR (minimal Redundancy Maximal Relevance) and incremental feature selection (IFS), were applied to identify the 38-gene biomarker. An SVM (support vector machine) classifier was built based on the 38-gene biomarker. Its accuracy, sensitivity, and specificity on training dataset evaluated by leave one out cross-validation were 0.905, 0.896, and 0.912, respectively. And on independent test dataset, the accuracy, sensitivity, and specificity on were as great as and were 0.904, 0.933, and 0.869, respectively. The biological function analysis of the 38 genes indicated that many of them can be potential treatment targets that may benefit COPD and ILD patients.

Intestinal epithelial deletion of the glucocorticoid receptor NR3C1 alters expression of inflammatory mediators and barrier function

Glucocorticoids (GCs) are important hormones involved in the regulation of multiple physiologic functions. GCs are also widely used in anti-inflammatory/immunosuppressant drugs. GCs are synthesized by the adrenal cortex as part of the hypothalamus-pituitary-adrenal axis and also by intestinal epithelial cells, among other peripheral sites. GCs are one of the main therapy choices for the exacerbations of inflammatory bowel disease, but they are not useful to prolong remission, and development of tolerance with secondary treatment failure is frequent. Thus, GC actions at the intestinal epithelial level are of great importance, both physiologically and pharmacologically. We generated a tamoxifen-inducible nuclear receptor subfamily 3 group C member 1 (NR3C1)^ΔIEC mouse model to study the effects of GCs on epithelial cells in vivo. Nr3c1 deletion in epithelial cells of the small intestine and colon was associated with limited colonic inflammation at 1 wk postdeletion, involving augmented epithelial proliferation and mucus production, plus local and systemic immune/inflammatory changes. This phenotype regressed substantially, but not completely, after 2 wk. The mechanism may involve augmented inflammatory signaling by epithelial cells or defective barrier function. We conclude that the epithelial GC receptor plays a significant role in colonic homeostasis in basal conditions, but its deficiency can be compensated in the short term. Future studies are required to assess the impact of Nr3c1 deletion in other conditions such as experimental colitis.-Aranda, C. J., Arredondo-Amador, M., Ocón, B., Lavín, J. L., Aransay, A. M., Martínez-Augustin, O., Sánchez de Medina, F. Intestinal epithelial deletion of the glucocorticoid receptor NR3C1 alters expression of inflammatory mediators and barrier function.

The Medical Management of Cerebral Edema: Past, Present, and Future Therapies

Cerebral edema is commonly associated with cerebral pathology, and the clinical manifestation is largely related to the underlying lesioned tissue. Brain edema usually amplifies the dysfunction of the lesioned tissue and the burden of cerebral edema correlates with increased morbidity and mortality across diseases. Our modern-day approach to the medical management of cerebral edema has largely revolved around, an increasingly artificial distinction between cytotoxic and vasogenic cerebral edema. These nontargeted interventions such as hyperosmolar agents and sedation have been the mainstay in clinical practice and offer noneloquent solutions to a dire problem. Our current understanding of the underlying molecular mechanisms driving cerebral edema is becoming much more advanced, with differences being identified across diseases and populations. As our understanding of the underlying molecular mechanisms in neuronal injury continues to expand, so too is the list of targeted therapies in the pipeline. Here we present a brief review of the molecular mechanisms driving cerebral edema and a current overview of our understanding of the molecular targets being investigated.

lncRNA PSORS1C3 is regulated by glucocorticoids and fine-tunes OCT4 expression in non-pluripotent cells

OCT4 is a transcription factor known for its regulatory roles in stemness, tumorigenesis and stress response. Considering its versatile functions, expression of OCT4 is regulated at different levels. PSORS1C3, a long non-coding RNA overlapped with OCT4, has a putative association with immune mediated diseases; however, its exact functions remained to be elucidated. Here, we demonstrated that PSORS1C3 is regulated by glucocorticoids (GC), has two endogenously active promoters, promoter 0 and 1, and two sets of transcripts, short and long variants. According to our findings, PSORS1C3 promoters behaved differently during neural differentiation of NT2 cells and glucocorticoid receptor (GR) activation. In both processes the expression pattern of short variants differed from that of long variants and was similar to OCT4 expression. Furthermore, our data revealed that PSORS1C3’s promoter 0 could act as an enhancer for OCT4 in non-pluripotent cells, where its deletion caused a significant decrease in OCT4 expression. Meanwhile, during GR activation promoter 0 functioned as a negative regulator and alleviated transcription induction of OCT4 after GC treatment. Altogether, our work clarified the structure and regulation of PSORS1C3, explained its relation to immune-related disease through GR signaling and introduced it as a novel fine-tuner of OCT4 expression in non-pluripotent cells.

Combined Antioxidant and Glucocorticoid Therapy for Safer Treatment of Preterm Birth

Ante- and postnatal glucocorticoid therapy reduces morbidity and mortality in the preterm infant, and it is therefore one of the best examples of the successful translation of basic experimental science into human clinical practice. However, accruing evidence derived from human clinical studies and from experimental studies in animal models raise serious concerns about potential long-term adverse effects of treatment on growth and neurological and cardiovascular function in the offspring. This review explores whether combined antioxidant and glucocorticoid therapy may be safer than glucocorticoid therapy alone for the treatment of preterm birth.

ANP32E, a Protein Involved in Steroid-Refractoriness in Ulcerative Colitis, Identified by a Systems Biology Approach

BACKGROUND AND AIMS

Steroid-refractoriness is a common and unpredictable phenomenon in ulcerative colitis [UC], but there are no conclusive studies on the molecular functions involved. We aimed to assess the mechanism of action related to steroid failure by integrating transcriptomic data from UC patients, and updated molecular data on UC and glucocorticoids.

METHODS

MicroRNA [miRNA] and mRNA expression were evaluated by sequencing and microarrays, respectively, from rectal biopsies of patients with moderately-to-severe active UC, obtained before and on the third day of steroid treatment. The differential results were integrated into the mathematical models generated by a systems biology approach.

RESULTS

This computational approach identified 18 proteins that stand out either by being associated with the mechanism of action or by providing a means to classify the patients according to steroid response. Their biological functions have been linked to inflammation, glucocorticoid-induced transcription and angiogenesis. All the selected proteins except ANP32E [a chaperone which has been linked to the exchange of H2A.z histone and promotes glucocorticoid receptor-induced transcription] had previously been related to UC and/or glucocorticoid-induced biological actions. Western blot and immunofluorescence assays confirmed the implication of this chaperone in steroid failure in patients with active UC.

CONCLUSIONS

A systems biology approach allowed us to identify a comprehensive mechanism of action of steroid-refractoriness, highlighting the key role of steroid-induced transcription and the potential implication of ANP32E in this phenomenon.

Respiratory Syncytial Virus Nonstructural Protein 1 Blocks Glucocorticoid Receptor Nuclear Translocation by Targeting IPO13 and May Account for Glucocorticoid Insensitivity

Despite their powerful antiinflammatory effect, glucocorticoids have shown no significant clinical benefit in respiratory syncytial virus (RSV)-induced bronchiolitis, the reason for which remains unclear. Upon glucocorticoid binding, the cytoplasmic glucocorticoid receptor (GR) translocates to the nucleus with the help of importin 13 (IPO13). Here, we report that RSV infection reduced GR nuclear translocation in nasopharyngeal aspirates from RSV-infected infants, lungs of infected mice, and A549 cells, which coincided with decreased IPO13 expression. This led to repression of GR-induced antiinflammatory genes, such that dexamethasone failed to suppress airway inflammation and airway hyperresponsiveness in the infected mice. The anti-GR effect of RSV was mediated by viral nonstructural protein 1 , which likely functioned by competing with IPO13 for GR binding. Our findings provide a mechanism for the ineffectiveness of glucocorticoids in RSV-related disease and highlight the potential to target the IPO13-GR axis as a treatment for multiple glucocorticoid-related diseases.

Expression of corticosteroid-regulated genes by PBMCs in children with asthma

BACKGROUND

Variability in response to inhaled corticosteroids (ICSs) can result in less than optimal asthma control. Development of biomarkers assessing the therapeutic efficacy of corticosteroids is important.

OBJECTIVE

We sought to examine whether in vitro PBMC responses to corticosteroids relate to the clinical ICS response.

METHODS

PBMCs were collected from 125 children with asthma (6-17 years) at enrollment (visit 0 [V0]) and after 1 year of bimonthly guidelines-based management visits (visit 6 [V6]). Difficult-to-control and easy-to-control asthma were defined as requiring daily therapy with 500 μg or more of fluticasone propionate (FLU) with or without a long-acting β-agonist versus 100 μg or less of FLU in at least 4 visits. mRNA levels of glucocorticoid receptor α and corticosteroid transactivation (FK506-binding protein 5) and transrepression markers (IL-8 and TNF-α) were measured by using RT-PCR in freshly isolated cells and in response to 10-8 mol/L FLU.

RESULTS

Compared with PBMCs from patients with easy-to-control asthma, PBMCs from those with difficult-to-control asthma had significantly lower glucocorticoid receptor α levels at V0 (P = .05). A 30% increase in IL-8 suppression by FLU (P = .04) and a trend for increased TNF-α suppression by FLU between V0 and V6 (P = .07) were observed in patients with easy-to-control asthma. In contrast, no changes between V0 and V6 in IL-8 and TNF-α suppression by FLU were observed in patients with difficult-to-control asthma. Corticosteroid-mediated transactivation (FK506-binding protein 5 induction by FLU) increased in the PBMCs of patients with difficult-to-control and easy-to-control asthma between V0 and V6 (P = .05 and P = .03, respectively).

CONCLUSIONS

PBMCs of children with difficult-to-control asthma treated with guidelines-based therapy and requiring high-dose ICSs had reduced in vitro responsiveness to corticosteroids.

Glucocorticoids exert differential effects on the endothelium in an in vitro model of the blood-retinal barrier

PURPOSE

Glucocorticoids (GCs) are used as treatment in diabetic macular oedema, a condition caused by blood-retinal barrier (BRB) disruption. The proposed mechanisms by which GCs reduce macular oedema are indirect anti-inflammatory effects and inhibition of VEGF production, but direct effects on the BRB endothelium may be equally important. Here, we investigated direct effects of GCs on the endothelium to understand the specific pathways of GC action, to enable development of novel therapeutics lacking the adverse side-effects of the presently used GCs.

METHODS

Primary bovine retinal endothelial cells (BRECs) were grown on Transwell inserts and treated with hydrocortisone (HC), dexamethasone (Dex) or triamcinolone acetonide (TA). Molecular barrier integrity of the BRB was determined by mRNA and protein expression, and barrier function was assessed using permeability assays. In addition, we investigated whether TA was able to prevent barrier disruption after stimulation with VEGF or cytokines.

RESULTS

Treatment of BRECs with GCs resulted in upregulation of tight junction mRNA (claudin-5, occludin, ZO-1) and protein (claudin-5 and ZO-1). In functional assays, only TA strengthened the barrier function by reducing endothelial permeability. Moreover, TA was able to prevent cytokine-induced permeability in human retinal endothelial cells and VEGF-induced expression of plasmalemma vesicle-associated protein (PLVAP), a key player in VEGF-induced retinal vascular leakage.

CONCLUSION

Glucocorticoids have differential effects in an experimental in vitro BRB model. TA is the most potent in improving barrier function, both at the molecular and functional levels, and TA prevents VEGF-induced expression of PLVAP.

Glucocorticoid-driven transcriptomes in human airway epithelial cells: commonalities, differences and functional insight from cell lines and primary cells

Background

Glucocorticoids act on the glucocorticoid receptor (GR; NR3C1) to resolve inflammation and, as inhaled corticosteroids (ICS), are the cornerstone of treatment for asthma. However, reduced efficacy in severe disease or exacerbations indicates a need to improve ICS actions.

Methods

Glucocorticoid-driven transcriptomes were compared using PrimeView microarrays between primary human bronchial epithelial (HBE) cells and the model cell lines, pulmonary type II A549 and bronchial epithelial BEAS-2B cells.

Results

In BEAS-2B cells, budesonide induced (≥2-fold, P ≤ 0.05) or, in a more delayed fashion, repressed (≤0.5-fold, P ≤ 0.05) the expression of 63, 133, 240, and 257 or 15, 56, 236, and 344 mRNAs at 1, 2, 6, and 18 h, respectively. Within the early-induced mRNAs were multiple transcriptional activators and repressors, thereby providing mechanisms for the subsequent modulation of gene expression. Using the above criteria, 17 (BCL6, BIRC3, CEBPD, ERRFI1, FBXL16, FKBP5, GADD45B, IRS2, KLF9, PDK4, PER1, RGCC, RGS2, SEC14L2, SLC16A12, TFCP2L1, TSC22D3) induced and 8 (ARL4C, FLRT2, IER3, IL11, PLAUR, SEMA3A, SLC4A7, SOX9) repressed mRNAs were common between A549, BEAS-2B and HBE cells at 6 h. As absolute gene expression change showed greater commonality, lowering the cut-off (≥1.25 or ≤ 0.8-fold) within these groups produced 93 induced and 82 repressed genes in common. Since large changes in few mRNAs and/or small changes in many mRNAs may drive function, gene ontology (GO)/pathway analyses were performed using both stringency criteria. Budesonide-induced genes showed GO term enrichment for positive and negative regulation of transcription, signaling, proliferation, apoptosis, and movement, as well as FOXO and PI3K-Akt signaling pathways. Repressed genes were enriched for inflammatory signaling pathways (TNF, NF-κB) and GO terms for cytokine activity, chemotaxis and cell signaling. Reduced growth factor expression and effects on proliferation and apoptosis were highlighted.

Conclusions

While glucocorticoids repress mRNAs associated with inflammation, prior induction of transcriptional activators and repressors may explain longer-term responses to these agents. Furthermore, positive and negative effects on signaling, proliferation, migration and apoptosis were revealed. Since many such gene expression changes occurred in human airways post-ICS inhalation, the effects observed in cell lines and primary HBE cells in vitro may be relevant to ICS in vivo.

Electronic supplementary material

The online version of this article (10.1186/s12920-018-0467-2) contains supplementary material, which is available to authorized users.

Counteracting neuroinflammation in experimental Parkinson's disease favors recovery of function: effects of Er-NPCs administration

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disease, presenting with midbrain dopaminergic neurons degeneration. A number of studies suggest that microglial activation may have a role in PD. It has emerged that inflammation-derived oxidative stress and cytokine-dependent toxicity may contribute to nigrostriatal pathway degeneration and exacerbate the progression of the disease in patients with idiopathic PD. Cell therapies have long been considered a feasible regenerative approach to compensate for the loss of specific cell populations such as the one that occurs in PD. We recently demonstrated that erythropoietin-releasing neural precursors cells (Er-NPCs) administered to MPTP-intoxicated animals survive after transplantation in the recipient's damaged brain, differentiate, and rescue degenerating striatal dopaminergic neurons. Here, we aimed to investigate the potential anti-inflammatory actions of Er-NPCs infused in an MPTP experimental model of PD.

METHODS

The degeneration of dopaminergic neurons was caused by MPTP administration in C57BL/6 male mice. 2.5 × 105 GFP-labeled Er-NPCs were administered by stereotaxic injection unilaterally in the left striatum. Functional recovery was assessed by two independent behavioral tests. Neuroinflammation was investigated measuring the mRNAs levels of pro-inflammatory and anti-inflammatory cytokines, and immunohistochemistry studies were performed to evaluate markers of inflammation and the potential rescue of tyrosine hydroxylase (TH) projections in the striatum of recipient mice.

RESULTS

Er-NPC administration promoted a rapid anti-inflammatory effect that was already evident 24 h after transplant with a decrease of pro-inflammatory and increase of anti-inflammatory cytokines mRNA expression levels. This effect was maintained until the end of the observational period, 2 weeks post-transplant. Here, we show that Er-NPCs transplant reduces macrophage infiltration, directly counteracting the M1-like pro-inflammatory response of murine-activated microglia, which corresponds to the decrease of CD68 and CD86 markers, and induces M2-like pro-regeneration traits, as indicated by the increase of CD206 and IL-10 expression. Moreover, we also show that this activity is mediated by Er-NPCs-derived erythropoietin (EPO) since the co-injection of cells with anti-EPO antibodies neutralizes the anti-inflammatory effect of the Er-NPCs treatment.

CONCLUSION

This study shows the anti-inflammatory actions exerted by Er-NPCs, and we suggest that these cells may represent good candidates for cellular therapy to counteract neuroinflammation in neurodegenerative disorders.

Inhibition of microRNA-124-3p as a novel therapeutic strategy for the treatment of Gulf War Illness: Evaluation in a rat model

Gulf War Illness (GWI) is a chronic, multisymptom illness that continues to affect up to 30% of veterans deployed to the Persian Gulf during the 1990-1991 Gulf War. After nearly 30 years, useful treatments for GWI are lacking and underlying cellular and molecular mechanisms involved in its pathobiology remain poorly understood, although exposures to pyridostigmine bromide (PB) and pesticides are consistently identified to be among the strongest risk factors. Alleviation of the broad range of symptoms manifested in GWI, which involve the central nervous system, the neuroendocrine system, and the immune system likely requires therapies that are able to activate and inactivate a large set of orchestrated genes. Previous work in our laboratory using an established rat model of GWI identified persistent elevation of microRNA-124-3p (miR-124) levels in the hippocampus whose numerous gene targets are involved in cognition-associated pathways and neuroendocrine function. This study aimed to investigate the broad effects of miR-124 inhibition in the brain 9 months after completion of a 28-day exposure regimen of PB, DEET (N,N-diethyl-3-methylbenzamide), permethrin, and mild stress by profiling the hippocampal expression of genes known to play a critical role in synaptic plasticity, glucocorticoid signaling, and neurogenesis. We determined that intracerebroventricular infusion of a miR-124 antisense oligonucleotide (miR-124 inhibitor; 0.05-0.5 nmol/day/28 days), but not a negative control oligonucleotide, into the lateral ventricle of the brain caused increased protein expression of multiple validated miR-124 targets and increased expression of downstream target genes important for cognition and neuroendocrine signaling in the hippocampus. Off-target cardiotoxic effects were revealed in GWI rats receiving 0.1 nmol/day as indicated by the detection in plasma of 5 highly elevated protein cardiac injury markers and 6 upregulated cardiac-enriched miRNAs in plasma exosomes determined by next-generation sequencing. Results from this study suggest that in vivo inhibition of miR-124 function in the hippocampus is a promising, novel therapeutic approach to improve cognition and neuroendocrine dysfunction in GWI. Additional preclinical studies in animal models to assess feasibility and safety by developing a practical, noninvasive drug delivery system to the brain and exploring potential adverse toxicologic effects of miR-124 inhibition are warranted.

Reperfusion Activates AP-1 and Heat Shock Response in Donor Kidney Parenchyma after Warm Ischemia

Utilization of kidneys from extended criteria donors leads to an increase in average warm ischemia time (WIT), which is associated with larger degrees of ischemia-reperfusion injury (IRI). Kidney resuscitation by extracorporeal perfusion in situ allows up to 60 minutes of asystole after the circulatory death. Molecular studies of kidney grafts from human donors with critically expanded WIT are warranted. Transcriptomes of two human kidneys from two different donors were profiled after 35-45 minutes of WIT and after 120 minutes of normothermic perfusion and compared. Baseline gene expression patterns in ischemic grafts display substantial intrinsic differences. IRI does not lead to substantial change in overall transcription landscape but activates a highly connected protein network with hubs centered on Jun/Fos/ATF transcription factors and HSP1A/HSPA5 heat shock proteins. This response is regulated by positive feedback. IRI networks are enriched in soluble proteins and biofluids assayable substances, thus, indicating feasibility of the longitudinal, minimally invasive assessment in vivo. Mapping of IRI related molecules in ischemic and reperfused kidneys provides a rationale for possible organ conditioning during machine assisted ex vivo normothermic perfusion. A study of natural diversity of the transcriptional landscapes in presumably normal, transplantation-suitable human organs is warranted.

Efficacy of corticosteroids for postoperative endodontic pain: A systematic review and meta-analysis

This systematic review aimed to analyze the efficacy of corticosteroid premedication compared to placebo or no treatment to reduce postoperative pain in endodontic patients. Randomized controlled trials (RCTs) assessing corticosteroids via oral, intramuscular, subperiosteal, intraligamentary or intracanal route compared to passive or active placebo, or no treatment were included. Four databases were searched: PubMed, Web of Science, Cochrane Library and Embase up to 2/21/2018. Risk of bias was assessed with Cochrane Risk of bias tool. Fourteen RCTs with 1,462 generally healthy adults in need of endodontic treatment were included. 50% of the studies were at unclear risk and 50% at high risk of bias. Meta-analysis showed Visual Analog Scale (VAS) pain at 4-6 hours after Inferior Alveolar Nerve Block (IANB) was significantly lower by 21 points (0-100 scale) in the corticosteroid group compared to the control group (95% CI -35 to -7; P = 0.003), however this difference was not statistically significant after 24 hours (P = 0.116). The route of administration was oral and intraligament injection. Patients who received corticosteroids prior to IANB were 70.7% more likely to have none or mild pain 4-8 hours after treatment (P = 0.001) and 13.5% more likely 24 hours after IANB (P = 0.013) than patients in the control group. In conclusion, corticosteroid administration (oral or intraligamental) may clinically reduce the level of postoperative pain at 4-8 hours after IANB, however the quality of the evidence was low/moderate due to risk of bias and heterogeneity. Further studies are recommended.

Air pollution and resistance to inhaled glucocorticoids: Evidence, mechanisms and gaps to fill

Substantial evidence indicates that cigarette smoke exposure induces resistance to glucocorticoids, the primary maintenance medication in asthma treatment. Modest evidence also suggests that air pollution may reduce the effectiveness of these critical medications. Cigarette smoke, which has clear parallels with air pollution, has been shown to induce glucocorticoid resistance in asthma and it has been speculated that air pollution may have similar effects. However, the literature on an association of air pollution with glucocorticoid resistance is modest to date. In this review, we detail the evidence for, and against, the effects of air pollution on glucocorticoid effectiveness, focusing on results from epidemiology and controlled human exposure studies. Epidemiological studies indicate a correlation between increased air pollution exposure and worse asthma symptoms. But these studies also show a mix of beneficial and harmful effects of glucocorticoids on spirometry and asthma symptoms, perhaps due to confounding influences, or the induction of glucocorticoid resistance. We describe mechanisms that may contribute to reductions in glucocorticoid responsiveness following air pollution exposure, including changes to phosphorylation or oxidation of the glucocorticoid receptor, repression by cytokines, or inflammatory pathways, and epigenetic effects. Possible interactions between air pollution and respiratory infections are also briefly discussed. Finally, we detail a number of therapies that may boost glucocorticoid effectiveness or reverse resistance in the presence of air pollution, and comment on the beneficial effects of engineering controls, such as air filtration and asthma action plans. We also call attention to the benefits of improved clean air policy on asthma. This review highlights numerous gaps in our knowledge of the interactions between air pollution and glucocorticoids to encourage further research in this area with a view to reducing the harm caused to those with airways disease.

Glucocorticoid receptor in astrocytes regulates midbrain dopamine neurodegeneration through connexin hemichannel activity

The precise contribution of astrocytes in neuroinflammatory process occurring in Parkinson’s disease (PD) is not well characterized. In this study, using GR^Cx30CreERT2 mice that are conditionally inactivated for glucocorticoid receptor (GR) in astrocytes, we have examined the actions of astrocytic GR during dopamine neuron (DN) degeneration triggered by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The results show significantly augmented DN loss in GR^Cx30CreERT2 mutant mice in substantia nigra (SN) compared to controls. Hypertrophy of microglia but not of astrocytes was greatly enhanced in SN of these astrocytic GR mutants intoxicated with MPTP, indicating heightened microglial reactivity compared to similarly-treated control mice. In the SN of GR astrocyte mutants, specific inflammation-associated transcripts ICAM-1, TNF-α and Il-1β as well as TNF-α protein levels were significantly elevated after MPTP neurotoxicity compared to controls. Interestingly, this paralleled increased connexin hemichannel activity and elevated intracellular calcium levels in astrocytes examined in acute midbrain slices from control and mutant mice treated with MPP+ . The increased connexin-43 hemichannel activity was found in vivo in MPTP-intoxicated mice. Importantly, treatment of MPTP-injected GR^Cx30CreERT2 mutant mice with TAT-Gap19 peptide, a specific connexin-43 hemichannel blocker, reverted both DN loss and microglial activation; in wild-type mice there was partial but significant survival effect. In the SN of post-mortem PD patients, a significant decrease in the number of astrocytes expressing nuclear GR was observed, suggesting the participation of astrocytic GR deregulation of inflammatory process in PD. Overall, these data provide mechanistic insights into GR-modulated processes in vivo, specifically in astrocytes, that contribute to a pro-inflammatory state and dopamine neurodegeneration in PD pathology.

Long-Acting β2-Adrenoceptor Agonists Enhance Glucocorticoid Receptor (GR)-Mediated Transcription by Gene-Specific Mechanisms Rather Than Generic Effects via GR

In asthma, the clinical efficacy of inhaled corticosteroids (ICSs) is enhanced by long-acting β₂-adrenoceptor agonists (LABAs). ICSs, or more accurately, glucocorticoids, promote therapeutically relevant changes in gene expression, and, in primary human bronchial epithelial cells (pHBECs) and airway smooth muscle cells, this genomic effect can be enhanced by a LABA. Modeling this interaction in human bronchial airway epithelial BEAS-2B cells transfected with a 2× glucocorticoid response element (2×GRE)-driven luciferase reporter showed glucocorticoid-induced transcription to be enhanced 2- to 3-fold by LABA. This glucocorticoid receptor (GR; NR3C1)-dependent effect occurred rapidly, was insensitive to protein synthesis inhibition, and was maximal when glucocorticoid and LABA were added concurrently. The ability of LABA to enhance GR-mediated transcription was not associated with changes in GR expression, serine (Ser²⁰³, Ser²¹¹, Ser²²⁶) phosphorylation, ligand affinity, or nuclear translocation. Chromatin immunoprecipitation demonstrated that glucocorticoid-induced recruitment of GR to the integrated 2×GRE reporter and multiple gene loci, whose mRNAs were unaffected or enhanced by LABA, was also unchanged by LABA. Transcriptomic analysis revealed glucocorticoid-induced mRNAs were variably enhanced, unaffected, or repressed by LABA. Thus, events leading to GR binding at target genes are not the primary explanation for how LABAs modulate GR-mediated transcription. As many glucocorticoid-induced genes are independently induced by LABA, gene-specific control by GR- and LABA-activated transcription factors may explain these observations. Because LABAs promote similar effects in pHBECs, therapeutic relevance is likely. These data illustrate the need to understand gene function(s), and the mechanisms leading to gene-specific induction, if existing ICS/LABA combination therapies are to be improved.

Roles of the Glucocorticoid and Mineralocorticoid Receptors in Skin Pathophysiology

The nuclear hormone receptor (NR) superfamily comprises approximately 50 evolutionarily conserved proteins that play major roles in gene regulation by prototypically acting as ligand-dependent transcription factors. Besides their central role in physiology, NRs have been largely used as therapeutic drug targets in many chronic inflammatory conditions and derivatives of their specific ligands, alone or in combination, are frequently prescribed for the treatment of skin diseases. In particular, glucocorticoids (GCs) are the most commonly used compounds for treating prevalent skin diseases such as psoriasis due to their anti-proliferative and anti-inflammatory actions. However, and despite their therapeutic efficacy, the long-term use of GCs is limited because of the cutaneous adverse effects including atrophy, delayed wound healing, and increased susceptibility to stress and infections. The GC receptor (GR/NR3C1) and the mineralocorticoid receptor (MR/NR3C2) are members of the NR subclass NR3C that are highly related, both structurally and functionally. While the GR is ubiquitously expressed and is almost exclusively activated by GCs; an MR has a more restricted tissue expression pattern and can bind GCs and the mineralocorticoid aldosterone with similar high affinity. As these receptors share 95% identity in their DNA binding domains; both can recognize the same hormone response elements; theoretically resulting in transcriptional regulation of the same target genes. However, a major mechanism for specific activation of GRs and/or MRs is at the pre-receptor level by modulating the local availability of active GCs. Furthermore, the selective interactions of each receptor with spatio-temporally regulated transcription factors and co-regulators are crucial for the final transcriptional outcome. While there are abundant genome wide studies identifying GR transcriptional targets in a variety of tissue and cell types; including keratinocytes; the data for MR is more limited thus far. Our group and others have studied the role of GRs and MRs in skin development and disease by generating and characterizing mouse and cellular models with gain- and loss-of-function for each receptor. Both NRs are required for skin barrier competence during mouse development and also play a role in adult skin homeostasis. Moreover, the combined loss of epidermal GRs and MRs caused a more severe skin phenotype relative to single knock-outs (KOs) in developing skin and in acute inflammation and psoriasis, indicating that these corticosteroid receptors play cooperative roles. Understanding GR- and MR-mediated signaling in skin should contribute to deciphering their tissue-specific relative roles and ultimately help to improve GC-based therapies.

Epidermal glucocorticoid and mineralocorticoid receptors act cooperatively to regulate epidermal development and counteract skin inflammation

Endogenous and synthetic glucocorticoids (GCs) regulate epidermal development and combat skin inflammatory diseases. GC actions can be mediated through the GC receptor (GR) and/or the mineralocorticoid receptor (MR), highly homologous ligand-activated transcription factors. While the role of GR as a potent anti-inflammatory mediator is well known, that of MR is not as clear, nor is whether these receptors cooperate or antagonize each other in the epidermis. To address this, we generated mice with epidermal-specific loss of both receptors (double knockout, DKO), and analyzed the phenotypical and functional consequences relative to single KOs or controls (CO). At birth, DKO epidermis displayed a phenotype of defective differentiation and inflammation, which was more severe than in either single KO, featuring neutrophil-containing infiltrates, and gene dysregulation characteristic of human psoriatic lesions. This phenotype resolved spontaneously. However, in adulthood, single or combined loss of GC receptors increased susceptibility to inflammation and hyperproliferation triggered by phorbol ester which, different to CO, was not effectively counteracted by GC treatment. Also, DKOs were more susceptible to imiquimod-induced psoriasis than CO showing severe defective epidermal differentiation and microabcesses while single KOs showed an intermediate response. Immortalized DKO keratinocytes featured increased proliferation kinetics and reduced cell size, a unique phenotype relative to single KO cells. The lack of GR and MR in keratinocytes, individual or combined, caused constitutive increases in p38 and ERK activities, which were partially reversed upon reinsertion of receptors into DKO cells. DKO keratinocytes also displayed significant increases in AP-1 and NF-κB transcriptional activities, which were partially rescued by ERK and p38 inhibition, respectively. Reinsertion of GR and MR in DKO keratinocytes resulted in physical and cooperative functional interactions that restored the transcriptional response to GCs. In conclusion, our data have revealed that epidermal GR and MR act cooperatively to regulate epidermal development and counteract skin inflammation.

Imidazo[2,1-b]benzothiazol Derivatives as Potential Allosteric Inhibitors of the Glucocorticoid Receptor

Glucocorticoid receptor (GCR) transactivation reporter gene assays were used as an initial high-throughput screening on a diversified library of 1200 compounds for their evaluation as GCR antagonists. A class of imidazo[2,1-b]benzothiazole and imidazo[2,1-b]benzoimidazole derivatives were identified for their ability to modulate GCR transactivation and anti-inflammatory transrepression effects utilizing GCR and NF-κB specific reporter gene assays. Modeling studies on the crystallographic structure of the GCR ligand binding domain provided three new analogues bearing the tetrahydroimidazo[2,1-b]benzothiazole scaffold able to antagonize the GCR in the presence of dexamethasone (DEX) and also defined their putative binding into the GCR structure. Both mRNA level measures of GCR itself and its target gene GILZ, on cells treated with the new analogues, showed a GCR transactivation inhibition, thus suggesting a potential allosteric inhibition of the GCR.

Glucocorticoids, genes and brain function

The identification of key genes in transcriptomic data constitutes a huge challenge. Our review of microarray reports revealed 88 genes whose transcription is consistently regulated by glucocorticoids (GCs), such as cortisol, corticosterone and dexamethasone, in the brain. Replicable transcriptomic data were combined with biochemical and physiological data to create an integrated view of the effects induced by GCs. The most frequently reported genes were Errfi1 and Ddit4. Their up-regulation was associated with the altered transcription of genes regulating growth factor and mTORC1 signaling (Gab1, Tsc22d3, Dusp1, Ndrg2, Ppp5c and Sesn1) and progression of the cell cycle (Ccnd1, Cdkn1a and Cables1). The GC-induced reprogramming of cell function involves changes in the mRNA level of genes responsible for the regulation of transcription (Klf9, Bcl6, Klf15, Tle3, Cxxc5, Litaf, Tle4, Jun, Sox4, Sox2, Sox9, Irf1, Sall2, Nfkbia and Id1) and the selective degradation of mRNA (Tob2). Other genes are involved in the regulation of metabolism (Gpd1, Aldoc and Pdk4), actin cytoskeleton (Myh2, Nedd9, Mical2, Rhou, Arl4d, Osbpl3, Arhgef3, Sdc4, Rdx, Wipf3, Chst1 and Hepacam), autophagy (Eva1a and Plekhf1), vesicular transport (Rhob, Ehd3, Vps37b and Scamp2), gap junctions (Gjb6), immune response (Tiparp, Mertk, Lyve1 and Il6r), signaling mediated by thyroid hormones (Thra and Sult1a1), calcium (Calm2), adrenaline/noradrenaline (Adcy9 and Adra1d), neuropeptide Y (Npy1r) and histamine (Hdc). GCs also affected genes involved in the synthesis of polyamines (Azin1) and taurine (Cdo1). The actions of GCs are restrained by feedback mechanisms depending on the transcription of Sgk1, Fkbp5 and Nr3c1. A side effect induced by GCs is increased production of reactive oxygen species. Available data show that the brain's response to GCs is part of an emergency mode characterized by inactivation of non-core activities, restrained inflammation, restriction of investments (growth), improved efficiency of energy production and the removal of unnecessary or malfunctioning cellular components to conserve energy and maintain nutrient supply during the stress response.

Systems biology and in vitro validation identifies family with sequence similarity 129 member A (FAM129A) as an asthma steroid response modulator

BACKGROUND

Variation in response to the most commonly used class of asthma controller medication, inhaled corticosteroids, presents a serious challenge in asthma management, particularly for steroid-resistant patients with little or no response to treatment.

OBJECTIVE

We applied a systems biology approach to primary clinical and genomic data to identify and validate genes that modulate steroid response in asthmatic children.

METHODS

We selected 104 inhaled corticosteroid-treated asthmatic non-Hispanic white children and determined a steroid responsiveness endophenotype (SRE) using observations of 6 clinical measures over 4 years. We modeled each subject's cellular steroid response using data from a previously published study of immortalized lymphoblastoid cell lines under dexamethasone (DEX) and sham treatment. We integrated SRE with immortalized lymphoblastoid cell line DEX responses and genotypes to build a genome-scale network using the Reverse Engineering, Forward Simulation modeling framework, identifying 7 genes modulating SRE.

RESULTS

Three of these genes were functionally validated by using a stable nuclear factor κ-light-chain-enhancer of activated B cells luciferase reporter in A549 human lung epithelial cells, IL-1β cytokine stimulation, and DEX treatment. By using small interfering RNA transfection, knockdown of family with sequence similarity 129 member A (FAM129A) produced a reduction in steroid treatment response (P < .001).

CONCLUSION

With this systems-based approach, we have shown that FAM129A is associated with variation in clinical asthma steroid responsiveness and that FAM129A modulates steroid responsiveness in lung epithelial cells.

Jinwei Tang modulates HDAC2 expression in a rat model of COPD

The aim of the present study was to investigate the effect of a Traditional Chinese Herbal Medicine (TCHM), named Jinwei Tang on histone deacetylase 2 (HDAC2) and its role in the regulation of corticosteroid resistance in a rat model of chronic obstructive pulmonary disease (COPD). Male Wistar rats were divided into five groups (each n=10): COPD group, established by the intratracheal instillation of lipopolysaccharide and passive smoke exposure, and control, budesonide, theophylline + budesonide and Jinwei Tang + budesonide groups. Lung function was measured, lung tissue histopathology was examined and HDAC2 expression in the lung was assessed by immunohistochemistry. In addition, protein levels of interleukin-8 (IL-8), tumor necrosis factor (TNF)-α and HDAC2 in lung homogenate were quantified by ELISA. The rat COPD model exhibited alterations of the ratio of forced expiratory volume in 0.2 sec (FEV_0.2) to the forced vital capacity, FEV_0.2, dynamic compliance and airway resistance. HDAC2 expression was markedly reduced in the lung tissue of the COPD group compared with the control group, and treatment with Jinwei Tang + budesonide or theophylline + budesonide resulted in significant attenuation of the reduction of HDAC2 expression in the lungs (P<0.05). However, treatment with budesonide alone did not significantly alter HDAC2 expression. In the Jinwei Tang + budesonide and theophylline + budesonide groups, IL-8 and TNF-α expression was significantly decreased (P<0.05) and the HDAC2 level increased (P<0.05) compared with that in the COPD group. In conclusion, Jinwei Tang modulates airway inflammation and may enhance the anti-inflammatory effect of glucocorticoid through the upregulation of HADC2 expression in a rat model of COPD.

Glucocorticoids promote apoptosis of proinflammatory monocytes by inhibiting ERK activity

Glucocorticoids (GCs) are potent anti-inflammatory drugs whose mode of action is complex and still debatable. One likely cellular target of GCs are monocytes/macrophages. The role of GCs in monocyte survival is also debated. Although both granulocyte macrophage-colony stimulating factor (GM-CSF) and macrophage-CSF (M-CSF) are important regulators of macrophage lineage functions including their survival, the former is often associated with proinflammatory functions while the latter is important in lineage homeostasis. We report here that the GC, dexamethasone, induces apoptosis in GM-CSF-treated human monocytes while having no impact on M-CSF-induced monocyte survival. To understand how GCs, GM-CSF, and M-CSF are regulating monocyte survival and other functions during inflammation, we firstly examined the transcriptomic changes elicited by these three agents in human monocytes, either acting alone or in combination. Transcriptomic and Ingenuity pathway analyses found that dexamethasone differentially modulated dendritic cell maturation and TREM1 signaling pathways in GM-CSF-treated and M-CSF-treated monocytes, two pathways known to be regulated by ERK1/2 activity. These analyses led us to provide evidence that the GC inhibits ERK1/2 activity selectively in GM-CSF-treated monocytes to induce apoptosis. It is proposed that this inhibition of ERK1/2 activity leads to inactivation of p90 ribosomal-S6 kinase and Bad dephosphorylation leading in turn to enhanced caspase-3 activity and subsequent apoptosis. Furthermore, pharmacological inhibition of GC receptor activity restored the ERK1/2 signaling and prevented the GC-induced apoptosis in GM-CSF-treated monocytes. Increased tissue macrophage numbers, possibly from enhanced survival due to mediators such as GM-CSF, can correlate with inflammatory disease severity; also reduction in these numbers can correlate with the therapeutic benefit of a number of agents, including GCs. We propose that the ERK1/2 signaling pathway promotes survival of GM-CSF-treated proinflammatory monocytes, which can be selectively targeted by GCs as a novel mechanism to reduce local monocyte/macrophage numbers and hence inflammation.

Cortisol limits selected actions of synthetic glucocorticoids in the airway epithelium

Cortisol, a physiologic glucocorticoid (GC), is essential for growth and differentiation of the airway epithelium. Epithelial function influences inflammation in chronic respiratory diseases. Synthetic GCs, including inhaled corticosteroids, exert anti-inflammatory effects in airway epithelium by transactivation of genes and by inhibition of proinflammatory cytokine release. We examined the effect of cortisol on the actions of synthetic GCs in the airway epithelium, demonstrating that cortisol acts like a partial agonist at the GC receptor (GR), limiting GC-induced GR-dependent transcription in the BEAS-2B human bronchial epithelial cell line. Cortisol also limited the inhibition of granulocyte macrophage colony-stimulating factor release by synthetic GCs in TNF-α-activated BEAS-2B cells. The relevance of these findings is supported by observations on tracheal epithelium obtained from mice treated for 5 d with systemic GC, showing limitations in selected GC effects, including inhibition of IL-6. Moreover, gene transactivation by synthetic GCs was compromised by standard air-liquid interface (ALI) growth medium cortisol concentration (1.4 μM) in the ALI-differentiated organotypic culture of primary human airway epithelial cells. These findings suggest that endogenous corticosteroids may limit certain actions of synthetic pharmacological GCs and contribute to GC insensitivity, particularly when corticosteroid levels are elevated by stress.-Prodanovic, D., Keenan, C. R., Langenbach, S., Li, M., Chen, Q., Lew, M. J., Stewart, A. G. Cortisol limits selected actions of synthetic glucocorticoids in the airway epithelium.

Selective Glucocorticoid Receptor Properties of GSK866 Analogs with Cysteine Reactive Warheads

Synthetic glucocorticoids (GC) are the mainstay therapy for treatment of acute and chronic inflammatory disorders. Due to the high adverse effects associated with long-term use, GC pharmacology has focused since the nineties on more selective GC ligand-binding strategies, classified as selective glucocorticoid receptor (GR) agonists (SEGRAs) or selective glucocorticoid receptor modulators (SEGRMs). In the current study, GSK866 analogs with electrophilic covalent-binding warheads were developed with potential SEGRA properties to improve their clinical safety profile for long-lasting topical skin disease applications. Since the off-rate of a covalently binding drug is negligible compared to that of a non-covalent drug, its therapeutic effects can be prolonged and typically, smaller doses of the drug are necessary to reach the same level of therapeutic efficacy, thereby potentially reducing systemic side effects. Different analogs of SEGRA GSK866 coupled to cysteine reactive warheads were characterized for GR potency and selectivity in various biochemical and cellular assays. GR- and NFκB-dependent reporter gene studies show favorable anti-inflammatory properties with reduced GR transactivation of two non-steroidal GSK866 analogs UAMC-1217 and UAMC-1218, whereas UAMC-1158 and UAMC-1159 compounds failed to modulate cellular GR activity. These results were further supported by GR immuno-localization and S211 phospho-GR western analysis, illustrating significant GR phosphoactivation and nuclear translocation upon treatment of GSK866, UAMC-1217, or UAMC-1218, but not in case of UAMC-1158 or UAMC-1159. Furthermore, mass spectrometry analysis of tryptic peptides of recombinant GR ligand-binding domain (LBD) bound to UAMC-1217 or UAMC-1218 confirmed covalent cysteine-dependent GR binding. Finally, molecular dynamics simulations, as well as glucocorticoid receptor ligand-binding domain (GR-LBD) coregulator interaction profiling of the GR-LBD bound to GSK866 or its covalently binding analogs UAMC-1217 or UAMC-1218 revealed subtle conformational differences that might underlie their SEGRA properties. Altogether, GSK866 analogs UAMC-1217 and UAMC-1218 hold promise as a novel class of covalent-binding SEGRA ligands for the treatment of topical inflammatory skin disorders.

Role and regulation of MKP-1 in airway inflammation

Mitogen-activated protein kinase (MAPK) phosphatase 1 (MKP-1) is a protein with anti-inflammatory properties and the archetypal member of the dual-specificity phosphatases (DUSPs) family that have emerged over the past decade as playing an instrumental role in the regulation of airway inflammation. Not only does MKP-1 serve a critical role as a negative feedback effector, controlling the extent and duration of pro-inflammatory MAPK signalling in airway cells, upregulation of this endogenous phosphatase has also emerged as being one of the key cellular mechanism responsible for the beneficial actions of clinically-used respiratory medicines, including β₂-agonists, phosphodiesterase inhibitors and corticosteroids. Herein, we review the role and regulation of MKP-1 in the context of airway inflammation. We initially outline the structure and biochemistry of MKP-1 and summarise the multi-layered molecular mechanisms responsible for MKP-1 production more generally. We then focus in on some of the key in vitro studies in cell types relevant to airway disease that explain how MKP-1 can be regulated in airway inflammation at the transcriptional, post-translation and post-translational level. And finally, we address some of the potential challenges with MKP-1 upregulation that need to be explored further to fully exploit the potential of MKP-1 to repress airway inflammation in chronic respiratory disease.

β2-Adrenoceptor Function in Asthma

β2-adrenoceptor agonists, often used in combination with corticosteroids, have been extensively used for the treatment of asthma. However, concerns have been raised regarding their adverse effects and safety including poor asthma control, life-threatening exacerbations, exacerbations that often require hospitalization, and asthma-related deaths. The question as to whether these adverse effects relate to the loss of their bronchoprotective action remains an interesting possibility. In the chapter, we will review the experimental evidence that describes the different potential factors and associated mechanisms that can blunt the therapeutic action of β2-adrenoceptor agonists in asthma. We show here evidence that various key inflammatory cytokines, growth factors, some respiratory viruses, certain allergens, unknown factors present in serum from atopic asthmatics have the capacity to impair β2-adrenoceptor function in airway smooth muscle, the main target of these drugs. More importantly, we present our latest research describing the role played by mast cells in impairing β2-adrenoceptor function. Although no definitive conclusion could be made regarding the implication of one single mechanism, receptor uncoupling, or receptor desensitization due to phosphorylation represents the main inhibitory pathways associated with a loss of β2-adrenoceptor function in airway smooth muscle. Targeting the pathways leading to β2-adrenoceptor dysfunction will likely provide novel therapies to improve the efficacy of β2-agonists in asthma.