Glucocorticoid Action Research Articles

Glucocorticoids orchestrate adult hippocampal plasticity: growing points and translational aspects

The review analyzes modern concepts regarding the control of various mechanisms of the hippocampal neuroplasticity in adult mammals and humans by glucocorticoids. Glucocorticoid hormones ensure the coordinated functioning of key components and mechanisms of hippocampal plasticity: neurogenesis, glutamatergic neurotransmission, microglia and astrocytes, systems of neurotrophic factors, neuroinflammation, protease activities, metabolic hormones, neurosteroids. Regulatory mechanisms are diverse; along with the direct action of glucocorticoids through their receptors, there are indirect glucocorticoid-dependent effects, as well as numerous interactions between various systems and components. Despite the fact that many connections in this complex regulatory scheme have not yet been established, the study of the factors and mechanisms considered in the review forms growth points in the field of glucocorticoid-regulated processes in the brain and primarily in the hippocampus. These studies are fundamentally important for the translation into the clinic and the potential treatment/prevention of common diseases of the emotional and cognitive spheres and respective comorbid conditions.

Identification of antimicrobial and glucocorticoid compounds in wastewater effluents with effect-directed analysis

Pharmaceuticals, such as glucocorticoids and antibiotics, are inadequately removed from wastewater and may cause unwanted toxic effects in the receiving environment. This study aimed to identify contaminants of emerging concern in wastewater effluent with antimicrobial or glucocorticoid activity by applying effect-directed analysis (EDA). Effluent samples from six wastewater treatment plants (WWTPs) in the Netherlands were collected and analyzed with unfractionated and fractionated bioassay testing. Per sample, 80 fractions were collected and in parallel high-resolution mass spectrometry (HRMS) data were recorded for suspect and nontarget screening. The antimicrobial activity of the effluents was determined with an antibiotics assay and ranged from 298 to 711 ng azithromycin equivalents·L−1. Macrolide antibiotics were identified in each effluent and found to significantly contribute to the antimicrobial activity of each sample. Agonistic glucocorticoid activity determined with the GR-CALUX assay ranged from 98.1 to 286 ng dexamethasone equivalents·L−1. Bioassay testing of several tentatively identified compounds to confirm their activity revealed inactivity in the assay or the incorrect identification of a feature. Effluent concentrations of glucocorticoid active compounds were estimated from the fractionated GR-CALUX bioassay response. Subsequently, the biological and chemical detection limits were compared and a sensitivity gap between the two monitoring approaches was identified. Overall, these results emphasize that combining sensitive effect-based testing with chemical analysis can more accurately reflect environmental exposure and risk than chemical analysis alone.

Glucocorticoid activation of macrophages protects against insulin resistance.

Glucocorticoid activation of macrophages protects against insulin resistance.

Renato Baserga, MD: In Memoriam (1925–2023)

We are saddened by the passing of Renato Baserga, who died on March 5, 2023, several days before his ninety-eighth birthday. Renato's contributions to defining the biology and pathology of the cell cycle and growth control are highly significant and far-reaching. His impact on the understanding of physiological regulation of cell division and cancer-compromised mechanisms that govern proliferation was enormous and mechanistically, as well as clinically, significant.Renato received an MD degree and completed a pathology residency at the University of Milan. He then completed a second residency in oncology and pathology at the Chicago Medical School and graduate training in biochemistry at Northwestern University in Chicago. His early research addressed tumor initiation, progression, and metastasis in animal models, providing important insights into hormonal control of tumorigenesis, including the action of glucocorticoids on tumor growth. As a faculty member at Northwestern University, Renato pioneered the development of autoradiography and radiolabeling approaches to investigate growth control and metabolic regulation in cancer cells. These approaches were instrumental for the development of molecular pathology as a strategy to mechanistically investigate cancer, and they provided a foundation for the evolution of molecular diagnostics.In 1965, Renato moved to Philadelphia. At the Fels Research Institute, Temple University School of Medicine, and at the Thomas Jefferson Kimmel Cancer Center, he developed cancer research programs that provided transformative advances in defining the molecular parameters of cell cycle control in in vivo animal models, as well as in highly informative cell systems. Beyond identification and characterization of regulatory pathways that mediate proliferation, Renato’s work elucidated the relationships between the cell cycle and growth control, proliferation and differentiation, and cell structure and gene expression.In addition to the enormous contributions of his laboratory discoveries that advanced the understanding of cancer biology and pathology, Renato was committed to disseminating research findings. As an associate editor for Cancer Research (1990–2000), he advocated for maximizing effective communication, emphasizing accessibility to the broad biomedical community.While he was devoted to his research, Renato's priority was his family. He was immensely proud of his two daughters, Janice (1959–2016), who was a veterinarian, and Susan, who is an internationally recognized leader in RNA biology and pathology. Renato's wife, Beverly, was his treasured and dedicated partner who meant more to him than words can describe.Renato had a contagious passion for discovery. He was an exceptional mentor and role model for his students. By example, he conveyed the power of innovative thinking as the basis for rigorous and systematic investigation. Renato leaves behind a legacy of insights into aberrant regulatory mechanisms that mediate cancer initiation and progression. In addition, he provided valuable guidance to research scientists and clinical investigators who will continue exploring cancer-compromised regulatory mechanisms to further expand our understanding of cancer biology and pathology.

Abstract 700: Genetic Deletion Of Neutrophil Elastase Does Not Alter Lesions In Mice With Atherosclerosis Induced By Aav8-mediated Over-expression Of PCSK9

Introduction: Elevated circulating glucocorticoids are causally linked to increased cardiovascular disease. Atherosclerosis is a key cardiovascular pathology, yet the contribution of glucocorticoids underlying atherogenesis is unclear. Corticosteroid binding globulin (CBG) regulates glucocorticoid action through binding, thus controlling its systemic bioavailability. Cleavage of CBG by neutrophil elastase (NE) is proposed to enhance bioavailability of glucocorticoids by reducing its binding affinity. Strikingly, Apoe -/- mice lacking NE (ELA -/- ) display reduced atherosclerosis. Hypothesis: This investigation addresses the hypothesis that NE influences atherogenesis through CBG cleavage, increasing glucocorticoid bioavailability at sites of plaque development. Methods: Adult (8-12wk old) male C57BL/6J, ELA -/- and ELA +/+ mice were injected with AAV8-PCSK9 (IP; 1x10 12 vector genomes) and fed a western diet (21% fat; 0.21% cholesterol) for 18wks (N=10-13). Control mice received diet without viral injection (N=10). Results: In C57BL/6J mice, histological analysis of brachiocephalic arteries demonstrated lesion development with AAV8-PCSK9-treatment, in parallel with increased (P=0.015) circulating NE protein levels (58.0 ± 5.5ng/ml) compared to diet-control mice (NE levels 32.8 ± 6.2ng/ml). AAV8-PCSK9 treatment did not alter circulating glucocorticoids (Corticosterone AM levels P=0.94; AAV8-PCSK9 65 ± 16nM; Control 74 ± 36nM) but hepatic CBG (Serpina6) transcript levels were reduced (1-fold; P=0.01; AAV8-PCSK9 0.57 ± 0.04; Control 1.13 ± 0.20). Interestingly, no differences in lesion size (P=0.8539; 23.2 ± 2.5%) or collagen content (P=0.5156; 17.64 ± 5.6%), or in circulating glucocorticoid levels (corticosterone AM levels; P=0.36; 225 ± 59nM) were observed in ELA -/- mice compared to controls (lesion size 24.2 ± 6.3%; collagen 12 ± 5%; glucocorticoid levels 142 ± 29nM). Conclusions: In contrast to published data using Apoe -/- mice, these results demonstrate that NE does not influence lesion size in this model of atherosclerosis. This suggests that NE inhibition would not be a useful therapeutic target in atherosclerosis. Future studies will directly address the role of CBG in the development of atherosclerosis.

Human neutrophils are a key target of glucocorticoids

Abstract Neutrophils play central roles in immunity and inflammation. Glucocorticoids (GCs) are the cornerstone of anti-inflammatory and immunosuppressive therapy. While GCs trigger an acute rise in circulating neutrophils, little is known about the mechanisms by which GCs modulate neutrophil biology. We studied the response of 9 primary human cells to in vitro treatment with GCs. Surprisingly, neutrophils were transcriptionally the most responsive cell type, and they express proportionally the most glucocorticoid receptor (GR) transcripts. Long-read RNA-seq revealed 42 full-length GR transcript isoforms in neutrophils, twice as many as had been reported previously in all other cell types. At the protein level, neutrophils also have a unique and diverse set of GR isoforms. In contrast to the widely accepted model of GR signaling, in which GR binds GC molecules in the cytoplasm and then translocates to the nucleus, GR localization in neutrophils is almost exclusively nuclear, even in the absence of GC treatment. To validate our findings in vivo, we then performed a study of healthy volunteers, with blood collected before and serially after GC infusion. We generated a pathway-level map of the human neutrophil transcriptome at baseline and in response to GCs. The in vivo transcriptional response of human neutrophils to GCs was as strong as that observed in vitro, with a predominance of upregulation. Among the most strongly induced genes are several that are either not expressed, or expressed at very low levels, in human neutrophils at baseline. Some of the proteins encoded by these genes may have putative effects on neutrophil function, including SAMSN1 and ZBTB16. These findings indicate that human neutrophils are a key target for GC action.

Impact of the LPS from Cyanobacteria Brasilonema sp.on Lung Inflammation and Glucocorticoid Expression

Abstract Inhaled glucocorticoids (GCs) are the first-line treatment for asthma. However, patients with asthma characterized by recruitment of neutrophils show poor sensitivity to GC therapy. A potential etiology of this GC-resistant asthma is aerosolized cyanobacterial lipopolysaccharide (LPS) from cyanobacterial blooms. Previously, we demonstrated that inhalation of LPS from Geitlerinema sp. of cyanobacteria induces neutrophilic lung infiltration in mice. Our current data shows that the LPS from another cyanobacteria, Brasilonema sp., also induces lung inflammation after inhalation. Flow cytometric data demonstrate that Brasilonema sp. LPS induces neutrophil infiltration and ELISA identified increases in pro-inflammatory cytokine levels in bronchoalveolar lung fluid after Brasilonema sp. LPS exposure. Furthermore, IHC data demonstrate that mice exposed to Brasilonema sp. LPS show an increased level of lung epithelial GCRβ, a glucocorticoid receptor (GR) analog that inhibits GC activity. Conversely, expression of GCRα, the GR isoform responsible for glucocorticoid sensitivity, remains unchanged. These data help to elucidate the mechanisms of Brasilonema sp. LPS-induced lung-inflammation and potential glucocorticoid resistance, while highlighting the importance of the toxin in promoting human disease near cyanobacterial blooms. This work is supported by the Kenneth A. Suarez Fellowship and Intramural Funds at Midwestern University.

Impaired alveolar macrophage 11β-hydroxysteroid dehydrogenase type 1 reductase activity contributes to increased pulmonary inflammation and mortality in sepsis-related ARDS.

Acute Respiratory Distress Syndrome (ARDS) is a devastating pulmonary inflammatory disorder, commonly precipitated by sepsis. Glucocorticoids are immunomodulatory steroids that can suppress inflammation. Their anti-inflammatory properties within tissues are influenced by their pre-receptor metabolism and amplification from inactive precursors by 11β-hydroxysteroid dehydrogenase type-1 (HSD-1). We hypothesised that in sepsis-related ARDS, alveolar macrophage (AM) HSD-1 activity and glucocorticoid activation are impaired, and associated with greater inflammatory injury and worse outcomes. We analysed broncho-alveolar lavage (BAL) and circulating glucocorticoid levels, AM HSD-1 reductase activity and Receptor for Advanced Glycation End-products (RAGE) levels in two cohorts of critically ill sepsis patients, with and without ARDS. AM HSD-1 reductase activity was also measured in lobectomy patients. We assessed inflammatory injury parameters in models of lung injury and sepsis in HSD-1 knockout (KO) and wild type (WT) mice. No difference in serum and BAL cortisol: cortisone ratios are shown between sepsis patients with and without ARDS. Across all sepsis patients, there is no association between BAL cortisol: cortisone ratio and 30-day mortality. However, AM HSD-1 reductase activity is impaired in patients with sepsis-related ARDS, compared to sepsis patients without ARDS and lobectomy patients (0.075 v 0.882 v 0.967 pM/hr/106 AMs, p=0.004). Across all sepsis patients (with and without ARDS), impaired AM HSD-1 reductase activity is associated with defective efferocytosis (r=0.804, p=0.008) and increased 30-day mortality. AM HSD-1 reductase activity negatively correlates with BAL RAGE in sepsis patients with ARDS (r=-0.427, p=0.017). Following intra-tracheal lipopolysaccharide (IT-LPS) injury, HSD-1 KO mice demonstrate increased alveolar neutrophil infiltration, apoptotic neutrophil accumulation, alveolar protein permeability and BAL RAGE concentrations compared to WT mice. Caecal Ligation and Puncture (CLP) injury in HSD-1 KO mice results in greater peritoneal apoptotic neutrophil accumulation compared to WT mice. AM HSD-1 reductase activity does not shape total BAL and serum cortisol: cortisone ratios, however impaired HSD-1 autocrine signalling renders AMs insensitive to the anti-inflammatory effects of local glucocorticoids. This contributes to the decreased efferocytosis, increased BAL RAGE concentrations and mortality seen in sepsis-related ARDS. Upregulation of alveolar HSD-1 activity could restore AM function and improve clinical outcomes in these patients.

SUMO regulation of FKBP51 activity and the stress response.

Glucocorticoids (GCs)actions are mostly mediated by the GC receptor (GR), a member of the nuclear receptor superfamily. Alterations of the GR activity have been associated to different diseases including mood disorders. FKBP51 is a GR chaperone that has gained much attention because it is a strong inhibitor of GR activity. FKBP51 exerts effects on many stress-related pathways and may be an important mediator of emotional behavior. Key proteins involved in the regulation of the stress response and antidepressant action are regulated by SUMOylation, a post-translational modification that has an important role in the regulation of neuronal physiology and disease. In this review, we focus on the role of SUMO-conjugation as a regulator of this pathway.

PARP1 mediated PARylation contributes to myogenic progression and glucocorticoid transcriptional response

The ADP-ribosyltransferase, PARP1 enzymatically generates and applies the post-translational modification, ADP-Ribose (ADPR). PARP1 roles in genome maintenance are well described, but recent work highlights roles in many fundamental processes including cellular identity and energy homeostasis. Herein, we show in both mouse and human skeletal muscle cells that PARP1-mediated PARylation is a regulator of the myogenic program and the muscle transcriptional response to steroid hormones. Chemical PARP1 modulation impacts the expression of major myocellular proteins, including troponins, key in dictating muscle contractile force. Whilst PARP1 in absence of DNA damage is often assumed to be basally inactive, we show PARylation to be acutely sensitive to extracellular glucose concentrations and the steroid hormone class, glucocorticoids which exert considerable authority over muscle tissue mass. Specifically, we find during myogenesis, a transient and significant rise in PAR. This early-stage differentiation event, if blocked with PARP1 inhibition, reduced the abundance of important muscle proteins in the fully differentiated myotubes. This suggests that PAR targets during early-stage differentiation are central to the proper development of the muscle contractile unit. We also show that reduced PARP1 in myoblasts impacts a variety of metabolic pathways in line with the recorded actions of glucocorticoids. Currently, as both regulators of myogenesis and muscle mass loss, glucocorticoids represent a clinical conundrum. Our work goes on to identify that PARP1 influences transcriptional activation by glucocorticoids of a subset of genes critical to human skeletal muscle pathology. These genes may therefore signify a regulatory battery of targets through which selective glucocorticoid modulation could be achieved. Collectively, our data provide clear links between PARP1-mediated PARylation and skeletal muscle homeostatic mechanisms crucial to tissue mass maintenance and endocrine response.

Glucocorticoid activation of anti-inflammatory macrophages protects against insulin resistance

Insulin resistance (IR) during obesity is linked to adipose tissue macrophage (ATM)-driven inflammation of adipose tissue. Whether anti-inflammatory glucocorticoids (GCs) at physiological levels modulate IR is unclear. Here, we report that deletion of the GC receptor (GR) in myeloid cells, including macrophages in mice, aggravates obesity-related IR by enhancing adipose tissue inflammation due to decreased anti-inflammatory ATM leading to exaggerated adipose tissue lipolysis and severe hepatic steatosis. In contrast, GR deletion in Kupffer cells alone does not alter IR. Co-culture experiments show that the absence of GR in macrophages directly causes reduced phospho-AKT and glucose uptake in adipocytes, suggesting an important function of GR in ATM. GR-deficient macrophages are refractory to alternative ATM-inducing IL-4 signaling, due to reduced STAT6 chromatin loading and diminished anti-inflammatory enhancer activation. We demonstrate that GR has an important function in macrophages during obesity by limiting adipose tissue inflammation and lipolysis to promote insulin sensitivity.

743 Diosmetin increases endogenous active glucocorticoid by activating local 11β-hydroxysteroid dehydrogenase 1 and suppresses skin inflammation

743 Diosmetin increases endogenous active glucocorticoid by activating local 11β-hydroxysteroid dehydrogenase 1 and suppresses skin inflammation

Glucocorticoid activation by HSD11B1 limits T cell-driven interferon signaling and response to PD-1 blockade in melanoma

BackgroundImmune responses against tumors are subject to negative feedback regulation. Immune checkpoint inhibitors (ICIs) blocking Programmed cell death protein 1 (PD-1), a receptor expressed on T cells, or its ligand...

Topical glucocorticoids іn dermatological practice: the problem of efficiency and safety

The problem of choosing the optimal glucocorticoids for topical use regularly arises for any physician involved in the treatment of dermatological diseases. When solving this problem, the doctor should take into account the nature, severity and localization of the pathological process, the patient's age, as well as the potency and the safety profile of the drug itself. One of the most common approaches to making the optimal choice of glucocorticoids for topical use, which is designed to reduce potential risks, involves administration the least active drugs at the beginning of the treatment, if they are ineffective, they switch to the use of more active drugs, and further the most active drugs. An obvious disadvantage of this approach is the duration of the procedure of the empirical selection of the drug, which can significantly impede treatment. The emergence of VI generation glucocorticoids, such as mometasone furoate, methylprednisolone aceponate and prednicarbate. The therapeutic potential of these drugs combines high activity and safety of use. It has changed the situation significantly and helped to solve the problem of the safe use of glucocorticoid drugs in pediatric and geriatric practice for the treatment of severe forms of dermatological diseases wich requires administration of the active glucocorticoids. The paper contains an overview of the main classification systems that are applied to glucocorticoids intended for use in dermatological practice, and a short analysis of literary data regarding the experience of the clinical use of VI generation glucocorticoids. The article also contains a retrospective overview of development of main approaches to improving the pharmacotherapeutic properties of topical glucocorticoids. Special attention is paid on the analysis of the influence of peculiarities of the chemical structure of drugs into pharmacokinetic and pharmacodynamic parameters. Keywords: corticosteroid-responsive dermatoses, mometasone furoate, methylprednisolone aceponate, prednicarbate.

11β-HSD1 inhibition does not affect murine tumour angiogenesis but may exert a selective effect on tumour growth by modulating inflammation and fibrosis.

Glucocorticoids inhibit angiogenesis by activating the glucocorticoid receptor. Inhibition of the glucocorticoid-activating enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) reduces tissue-specific glucocorticoid action and promotes angiogenesis in murine models of myocardial infarction. Angiogenesis is important in the growth of some solid tumours. This study used murine models of squamous cell carcinoma (SCC) and pancreatic ductal adenocarcinoma (PDAC) to test the hypothesis that 11β-HSD1 inhibition promotes angiogenesis and subsequent tumour growth. SCC or PDAC cells were injected into female FVB/N or C57BL6/J mice fed either standard diet, or diet containing the 11β-HSD1 inhibitor UE2316. SCC tumours grew more rapidly in UE2316-treated mice, reaching a larger (P<0.01) final volume (0.158 ± 0.037 cm3) than in control mice (0.051 ± 0.007 cm3). However, PDAC tumour growth was unaffected. Immunofluorescent analysis of SCC tumours did not show differences in vessel density (CD31/alpha-smooth muscle actin) or cell proliferation (Ki67) after 11β-HSD1 inhibition, and immunohistochemistry of SCC tumours did not show changes in inflammatory cell (CD3- or F4/80-positive) infiltration. In culture, the growth/viability (assessed by live cell imaging) of SCC cells was not affected by UE2316 or corticosterone. Second Harmonic Generation microscopy showed that UE2316 reduced Type I collagen (P<0.001), whilst RNA-sequencing revealed that multiple factors involved in the innate immune/inflammatory response were reduced in UE2316-treated SCC tumours. 11β-HSD1 inhibition increases SCC tumour growth, likely via suppression of inflammatory/immune cell signalling and extracellular matrix deposition, but does not promote tumour angiogenesis or growth of all solid tumours.

Periodic hypoxia, intermittent pain, and caffeine in male and female neonatal rats: corticosterone, insulin resistance, and hepatic gene expression.

Preterm infants experience multiple stressors including periodic neonatal hypoxia, maternal/caregiver separation, and acute pain from clinical procedures. Although neonatal hypoxia or interventional pain are associated with sexually dimorphic effects that may last into adulthood, the interaction of these common preterm stressors and caffeine pretreatment remains unknown. We hypothesize that an interaction of acute neonatal hypoxia, isolation, and pain modeling the experience of the preterm infant will augment the acute stress response and that caffeine routinely given to preterm infants will alter this response. Male and female rat pups were isolated and exposed to six cycles of periodic hypoxia (10% O2) or normoxia (room air control) and/or intermittent pain by administering needle pricks (or touch control) to the paw on postnatal (PD) days 1-4. An additional set of rat pups was pretreated with caffeine citrate (80 mg/kg ip) and studied on PD1. Plasma corticosterone, fasting glucose, and insulin were measured to calculate homeostatic model assessment for insulin resistance (HOMA-IR) (index of insulin resistance). Glucocorticoid-, insulin-, and caffeine-sensitive gene mRNAs were analyzed in the PD1 liver and hypothalamus to evaluate downstream markers of glucocorticoid action. Acute pain with periodic hypoxia led to a large increase in plasma corticosterone, which was attenuated by pretreatment with caffeine. Pain with periodic hypoxia led to a 10-fold increase in hepatic Per1 mRNA expression in males, which was attenuated with caffeine. The augmentation of corticosterone and HOMA-IR at PD1 after periodic hypoxia with pain suggests early intervention to attenuate the stress response may mitigate the programming effects of neonatal stress.

Direct inhibition of human and rat 11β-hydroxysteroid dehydrogenase 2 by per- and polyfluoroalkyl substances: Structure-activity relationship and in silico docking analysis

Per- and polyfluoroalkyl substances (PFAS) are persistent in the environment and may disrupt the endocrine system. Our previous study showed that perfluorooctanoic acid (PFOA, C8) and perfluorooctanesulfonic acid (PFOS, C8S) can inhibit 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2) activity leading to an active glucocorticoid accumulation. In this study, we extended investigation for 17 PFAS, including carboxylic and sulfonic acids, with different carbon-chain lengths, to determine their inhibitory potency and structure-activity relationship in human placental and rat renal 11β-HSD2. C8-C14 PFAS at 100 μM significantly inhibited human 11β-HSD2 with a potency as C10 (half-maximal inhibitory concentration, IC50, 9.19 μM) > C11 (15.09 μM) > C12 (18.43 μM) > C9 (20.93 μM) > C13 (124 μM) > C14 (147.3 μM) > other C4-C7 carboxylic acids, and C8S > C7S = C10S > other sulfonic acids. For rat 11β-HSD2, only C9 and C10 and C7S and C8S PFAS exhibited significant inhibitory effects. PFAS are primarily mixed/competitive inhibitors of human 11β-HSD2. Preincubation and simultaneous incubation with the reducing agent dithiothreitol significantly increased human 11β-HSD2 but not rat 11β-HSD2, and preincubation but not simultaneous incubation with dithiothreitol partially reversed C10-mediated inhibition on human 11β-HSD2. Docking analysis showed that all PFAS bound to the steroid-binding site and carbon-chain length determined the potency of inhibition, with the optimal molecular length (12.6 Å) for potent inhibitors PFDA and PFOS, which is comparable to the molecular length (12.7 Å) of the substrate cortisol. The length between 8.9 and 17.2 Å is the probable threshold molecular length to inhibit human 11β-HSD2. In conclusion, the carbon-chain length determines the inhibitory effect of PFAS on human and rat 11β-HSD2, and the inhibitory potency of long-chain PFAS on human and rat 11β-HSD2 showed V-shaped pattern. Long-chain PFAS may partially act on the cysteine residues of human 11β-HSD2.

Immunohistochemical localization of glucocorticoid receptors in the human cochlea

In the present study we investigated the localization of glucocorticoid receptors (GCR) in the human inner ear using immunohistochemistry. Celloidin-embedded cochlear sections of patients with normal hearing (n = 5), patients diagnosed with MD (n = 5), and noise induced hearing loss (n = 5) were immunostained using GCR rabbit affinity-purified polyclonal antibodies and secondary fluorescent or HRP labeled antibodies. Digital fluorescent images were acquired using a light sheet laser confocal microscope. In celloidin-embedded sections GCR-IF was present in the cell nuclei of hair cells and supporting cells of the organ of Corti. GCR-IF was detected in cell nuclei of the Reisner’s membrane. GCR-IF was seen in cell nuclei of the stria vascularis and the spiral ligament. GCR-IF was found in the spiral ganglia cell nuclei, however, spiral ganglia neurons showed no GCR-IF. Although GCRs were found in most cell nuclei of the cochlea, the intensity of IF was differential among the different cell types being more intense in supporting cells than in sensory hair cells. The differential expression of GCR receptors found in the human cochlea may help to understand the site of action of glucocorticoids in different ear diseases.

11β-HSD1 inhibition in men mitigates prednisolone-induced adverse effects in a proof-of-concept randomised double-blind placebo-controlled trial

Glucocorticoids prescribed to limit inflammation, have significant adverse effects. As 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) regenerates active glucocorticoid, we investigated whether 11β-HSD1 inhibition with AZD4017 could mitigate adverse glucocorticoid effects without compromising their anti-inflammatory actions. We conducted a proof-of-concept, randomized, double-blind, placebo-controlled study at Research Unit, Churchill Hospital, Oxford, UK (NCT03111810). 32 healthy male volunteers were randomized to AZD4017 or placebo, alongside prednisolone treatment. Although the primary endpoint of the study (change in glucose disposal during a two-step hyperinsulinemic, normoglycemic clamp) wasn’t met, hepatic insulin sensitivity worsened in the placebo-treated but not in the AZD4017-treated group. Protective effects of AZD4017 on markers of lipid metabolism and bone turnover were observed. Night-time blood pressure was higher in the placebo-treated but not in the AZD4017-treated group. Urinary (5aTHF+THF)/THE ratio was lower in the AZD4017-treated but remained the same in the placebo-treated group. Most anti-inflammatory actions of prednisolone persisted with AZD4017 co-treatment. Four adverse events were reported with AZD4017 and no serious adverse events. Here we show that co-administration of AZD4017 with prednisolone in men is a potential strategy to limit adverse glucocorticoid effects.

Melatonin-mediated FKBP4 downregulation protects against stress-induced neuronal mitochondria dysfunctions by blocking nuclear translocation of GR

The physiological crosstalk between glucocorticoid and melatonin maintains neuronal homeostasis in regulating circadian rhythms. However, the stress-inducing level of glucocorticoid triggers mitochondrial dysfunction including defective mitophagy by increasing the activity of glucocorticoid receptors (GRs), leading to neuronal cell death. Melatonin then suppresses glucocorticoid-induced stress-responsive neurodegeneration; however, the regulatory mechanism of melatonin, i.e., associated proteins involved in GR activity, has not been elucidated. Therefore, we investigated how melatonin regulates chaperone proteins related to GR trafficking into the nucleus to suppress glucocorticoid action. In this study, the effects of glucocorticoid on suppressing NIX-mediated mitophagy, followed by mitochondrial dysfunction, neuronal cell apoptosis, and cognitive deficits were reversed by melatonin treatment by inhibiting the nuclear translocation of GRs in both SH-SY5Y cells and mouse hippocampal tissue. Moreover, melatonin selectively suppressed the expression of FKBP prolyl isomerase 4 (FKBP4), which is a co-chaperone protein that works with dynein, to reduce the nuclear translocation of GRs among the chaperone proteins and nuclear trafficking proteins. In both cells and hippocampal tissue, melatonin upregulated melatonin receptor 1 (MT1) bound to Gαq, which triggered the phosphorylation of ERK1. The activated ERK then enhanced DNA methyltransferase 1 (DNMT1)-mediated hypermethylation of FKBP52 promoter, reducing GR-mediated mitochondrial dysfunction and cell apoptosis, the effects of which were reversed by knocking down DNMT1. Taken together, melatonin has a protective effect against glucocorticoid-induced defective mitophagy and neurodegeneration by enhancing DNMT1-mediated FKBP4 downregulation that reduced the nuclear translocation of GRs.