Chronic exposure to cortisone induces thyroid endocrine disruption and retinal dysfunction in adult female zebrafish (Danio rerio)

Cortisone has a large content in rivers because of its wide range of medical applications and elimination by organisms that naturally secrete it. As a steroid hormone, cortisone is recognized as a novel endocrine disruptor. Although ecotoxicological effects of the reproductive endocrine system have mainly been reported recently, thyroid endocrine in fish remains relatively less understood. Here, adult female zebrafish were exposed to cortisone at 0.0 (control), 3.2, 38.7, and 326.9 ng/L for 60 days. Evidence in this study came from fish behavior, hormone levels, gene expression, histological and morphological examinations. The results showed that THs (thyroid hormone) level disruption and pathohistological changes occurred in the thyroid gland, which may account for the gene expression changes in the hypothalamus-pituitary-thyroid gland axis. Specifically, more conversion of T4 (thyroxine) to T3 (triiodothyronine) led to an increased TSH (thyroid stimulating hormone) level in plasma. Severe thyroid tissue damage mainly occurred in the zebrafish exposed to 326.9 ng/L of cortisone. Meanwhile, consistent with the THs trend, the fish locomotion activity displayed more anxiety and excitement, the partial blockage of GABA (γ - aminobutyric acid) synthetic pathway genes might be the explanation of the underlying mechanism. Cortisone affected the gene expressions in the visual cycle and the circadian rhythm network also suggested interactions between thyroid endocrine disruption, retinal dysfunction, and abnormal behaviors of zebrafish. In summary, these findings suggest chronic exposure to cortisone induced various adverse effects in adult female zebrafish, which may help us better understand the risk of cortisone to fish in the wild.

The rise in expression and activity of 11β-HSD1 in human mesenchymal progenitor cells induces adipogenesis through increased local cortisol synthesis

11β-Hydroxysteroid dehydrogenase 1 (11β-HSD1) plays an important role in pre-receptor glucocorticoid metabolism. This enzyme is expressed in bone, increases with age, and catalyzes the conversion of the inactive glucocorticoid cortisone into the active glucocorticoid cortisol and vice versa. Here we hypothesized that the physiological activity of 11β-HSD1 to produce cortisol in human mesenchymal progenitor cells (hMSC) is principally sufficient to shift the differentiation potential in the direction of adipogenic. We thus investigated differentiating hMSCs and the mesenchymal stem cell line SCP-1 cultured under osteogenic conditions and stimulated with supra-physiological cortisone levels. The release of active cortisol into the medium was monitored and the influence on cell differentiation analyzed. We revealed an increase in 11β-HSD1 expression followed by increased reductive activity of the enzyme, thereby inducing a more adipogenic phenotype of the cell models via cortisol with negative effects on osteogenesis. Through inhibition experiments with the specific inhibitor 10 j, we proved the enzyme specificity for cortisol synthesis and adipogenic differentiation. Increased expression of 11β-HSD1 followed by higher cortisol levels might thus explain bone marrow adiposity followed by reduced bone quality and stability in old age or in situations of supra-physiological glucocorticoid exposure.

Curcuma longa aqueous extract: A potential solution for the prevention of corneal scarring as a result of pterygium surgical excision (Review)

Curcumin has been used since ancient times as a treatment for a wide range of pathologies. For centuries, it has been considered to be an effective aid for common human diseases. Curcuma longa has been reported to possess various beneficial properties and actions, including anti‑inflammatory, proapoptotic, antiangiogenic and cortisone‑like actions. Pterygium is a degenerative disorder of the conjunctiva indicative of a strong inflammatory condition that requires surgical treatment, which often results in disfiguring sclerocorneal scars. The delay in the healing of superficial corneal wounds caused by topical administration of light‑cortisone results in improved restoration of corneal functions and anatomy compared with physiological healing processes. The present review is focused on the medicinal properties of curcumin, the main component of Curcuma longa extract, in particular its strong cortisone‑like effect, and its potential use for the prevention and treatment of sclerocorneal scars resulting from pterygium surgical excision.

The Differential Effect of Cortisone and of A.C.T.H. On Mood

It is evident from many reports published in the last four years that psychological changes can occur during the treatment of physical illness by Cortisone and corticotrophin (A.C.T.H.). There is no doubt, too, that similar mental symptoms have been occasioned by giving either of these agents in therapeutic doses. It is perhaps for this reason that most writers have not distinguished between them in this respect. Thus, the mild mood changes that often occur, and the relatively rare psychotic reactions are usually spoken of as complications of A.C.T.H. or Cortisone therapy. This implies that, in the individual case, these substances would be equivalent in their influence on the mental state; yet there are grounds for suspecting otherwise. The aetiology of these psychological reactions remains obscure, so that any evidence which serves to differentiate the psychiatric side-effects of the two drugs would be of interest.

Glucocorticoids and microbiota regulate ontogeny of intestinal fucosyltransferase 2 requisite for gut homeostasis

At weaning, the intestinal mucosa surface glycans change from predominantly sialylated to fucosylated. Intestinal adaptation from milk to solid food is regulated by intrinsic and extrinsic factors. The contribution by glucocorticoid, an intrinsic factor, and colonization by microbiota, an extrinsic factor, was measured as the induction of α1,2/3-fucosyltransferase and sucrase-isomaltase (SI) activity and gene expression in conventionally raised, germ-free, and bacteria-depleted mice. In conventionally raised mice, cortisone acetate (CA) precociously accelerated SI gene expression up to 3 weeks and fut2 to 4 weeks of age. In germ-free mice, CA treatment induces only SI expression but not fucosyltransferase. In post-weaning bacteria-deficient (germ-free and bacteria-depleted) mice, fut2 expression remains at low suckling levels. In microbiota deficient mice, intestinal fut2 (but not fut1, fut4 or fut7) was induced only by adult microbiota, but not immature microbiota or CA. Fut2 induction could also be restored by colonization by Bacteroides fragilis, but not by a B. fragilis mutant unable to utilize fucose. Restoration of fut2 expression (by either microbiota or B. fragilis) in bacteria-depleted mice is necessary for recovery from dextran sulfate sodium-induced mucosal injury. Thus, glucocorticoids and microbes regulate distinct aspects of gut ontogeny: CA precociously accelerates SI expression and, only in colonized mice, fut2 early expression. The adult microbiota is required for the fut2 induction responsible for the highly fucosylated adult gut phenotype and is necessary for recovery from intestinal injury. Fut2-dependent recovery from inflammation may explain the high incidence of inflammatory disease (Crohn's and necrotizing enterocolitis) in populations with mutant FUT2 polymorphic alleles.

Compound f: the history of hydrocortisone and hand surgery

Hydrocortisone (cortisol) is used daily in the practice of medicine and hand surgery. It has an effective use in a number of orthopedic conditions, including tendinitis, tenovaginitis, bursitis, carpal tunnel syndrome, and joint inflammation. But are surgeons aware of how this important pharmaceutical agent was discovered and prepared for clinical trial and who was responsible for its first clinical application? How did medical doctors determine that, like penicillin, cortisone and its derivative hydrocortisone would have such a life-changing effect on certain medical conditions? The purpose of this review is to relate the story of the development of cortisone (Compound E) and hydrocortisone (Compound F) and how both influenced the practice of hand surgeons in the treatment of rheumatoid arthritis and related inflammatory conditions. This history of cortisone and hydrocortisone also relates to the importance of partnership between physician and research scientist and of the principle at Mayo Clinic that the only concern--or the first concern--is the concern for the patient.

1, 25-Dihydroxyvitamin D3Modulation of Adipocyte Glucocorticoid Function

OBJECTIVE

1,25-Dihydroxyvitamin D3 dose dependently increases intracellular calcium in human adipocytes. We have demonstrated that suppression of circulating 1,25-dihydroxyvitamin D3 levels by increasing dietary calcium reduces adipocyte intracellular calcium and reduces adiposity in both humans and rodents, with preferential loss of trunk fat. Autocrine production of cortisol by adipocytes of mice overexpressing 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD 1) in adipose tissue increases visceral adiposity, whereas knockout of 11beta-HSD 1 appears to attenuate truncal obesity. Accordingly, our objective was to investigate the role of 1,25-dihydroxyvitamin D3 in the modulation of adipocyte glucocorticoid metabolism.

RESEARCH METHODS AND PROCEDURES

We examined the effect of 1,25-dihydroxyvitamin D3 or angiotensin II on cortisol production and expression using real-time reverse transcriptase-polymerase chain reaction of 11beta-HSD 1, angiotensin II receptor type 1 (AT1), and AT2 receptor in human adipocytes.

RESULTS

Adipocytes produced negligible cortisol in the absence of substrate (cortisone). In the presence of cortisone (1 to 10 nM), there was significant cortisol production, which was dose dependently augmented (2- to 6-fold, p < 0.001) by 1,25-dihydroxyvitamin D3 (0.1 to 10 nM). 1,25-Dihydroxyvitamin D3 dose dependently increased 11beta-HSD 1 expression up to 2-fold (p < 0.01) in both the presence and absence of cortisone. In contrast, 1,25-dihydroxyvitamin D3 dose dependently decreased adipocyte AT1 expression (by 30% to 50%, p < 0.001) in both the presence and absence of cortisone, suggesting compensatory down-regulation of AT(1).

DISCUSSION

We conclude that 1,25-dihydroxyvitamin D3 directly regulates adipocyte 11beta-HSD 1 expression and, consequently, local cortisol levels and that this may contribute to the preferential loss of visceral adiposity by high-calcium diets.

Lack of significant metabolic abnormalities in mice with liver-specific disruption of 11β-hydroxysteroid dehydrogenase type 1

Glucocorticoids (GC) are implicated in the development of metabolic syndrome, and patients with GC excess share many clinical features, such as central obesity and glucose intolerance. In patients with obesity or type 2 diabetes, systemic GC concentrations seem to be invariably normal. Tissue GC concentrations determined by the hypothalamic-pituitary-adrenal (HPA) axis and local cortisol (corticosterone in mice) regeneration from cortisone (11-dehydrocorticosterone in mice) by the 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) enzyme, principally expressed in the liver. Transgenic mice have demonstrated the importance of 11β-HSD1 in mediating aspects of the metabolic syndrome, as well as HPA axis control. In order to address the primacy of hepatic 11β-HSD1 in regulating metabolism and the HPA axis, we have generated liver-specific 11β-HSD1 knockout (LKO) mice, assessed biomarkers of GC metabolism, and examined responses to high-fat feeding. LKO mice were able to regenerate cortisol from cortisone to 40% of control and had no discernible difference in a urinary metabolite marker of 11β-HSD1 activity. Although circulating corticosterone was unaltered, adrenal size was increased, indicative of chronic HPA stimulation. There was a mild improvement in glucose tolerance but with insulin sensitivity largely unaffected. Adiposity and body weight were unaffected as were aspects of hepatic lipid homeostasis, triglyceride accumulation, and serum lipids. Additionally, no changes in the expression of genes involved in glucose or lipid homeostasis were observed. Liver-specific deletion of 11β-HSD1 reduces corticosterone regeneration and may be important for setting aspects of HPA axis tone, without impacting upon urinary steroid metabolite profile. These discordant data have significant implications for the use of these biomarkers of 11β-HSD1 activity in clinical studies. The paucity of metabolic abnormalities in LKO points to important compensatory effects by HPA activation and to a crucial role of extrahepatic 11β-HSD1 expression, highlighting the contribution of cross talk between GC target tissues in determining metabolic phenotype.

The Effect of Cortisone and Hydrocortisone on the Plasma Levels of Corticotrophin in the Rat, After an Acute Stress

Pretreatment of intact female rats with cortisone and hydrocortisone acetates produces a graded inhibition of ACTH release in response to acute stress as shown by changes in plasma ACTH levels. The inhibition was greater with hydrocortisone and was dependent upon the time and dose relations.

Inhibition of cortisol metabolism by 17alpha,20beta-P: mechanism mediating semelparity in salmon?

In vitro experiments were conducted to test the hypothesis that 17alpha,20beta-dihydroxy-4-prengnen-3-one (17,20-P) regulates cortisol metabolism in Pacific salmon. In both rainbow trout and coho salmon, cortisol metabolism was significantly higher in the kidney compared to the liver. The rainbow trout kidney converted cortisol primarily into an unidentified water-soluble metabolite with a molecular mass of 354. The coho salmon kidney converted cortisol primarily into cortisol-21-sulfate. High physiological concentrations of 17,20-P had no effect on cortisol metabolism by the rainbow trout kidney, but almost completely inhibited the production of cortisol-21-sulfate by the coho salmon kidney. This was accompanied by a coincident increase in the production several neutral cortisol metabolites, including cortisone. Cortisone was also found to inhibit renal sulfotransferase (SULT) activity suggesting that there could be a local positive feedback mechanism initiated by the rise in 17,20-P that quickly reduces SULT activity as follows: the pre-spawning rise in 17,20-P inhibits SULT, cortisol is metabolized to cortisone instead of cortisol-21-sulfate, cortisone further inhibits SULT, more cortisone is produced, and so on. If SULT normally acts as a gatekeeper enzyme to protect the cell from cortisol excess, this mechanism would rapidly remove enzymatic protection and expose tissues to high local concentrations of cortisol. In addition, the inhibition of peripheral cortisol metabolism by 17,20-P could increase circulating concentrations of the corticosteroid. These events could be a part of the mechanism that leads to the symptoms of cortisol excess associated with the post-spawning mortality of semelparous Pacific salmon.

Plasma cortisol concentrations after oral substitution of cortisone in the fasting and non-fasting state

Nine corticosteroid-substituted patients received oral cortisone acetate in the fasting state and together with a breakfast meal. Plasma cortisol concentrations were determined before, after 30 min, and at 1-hour intervals until 6 hours after drug ingestion. There were great interindividual variations in the time to peak values (tmax), the peak concentrations (Cmax), and the areas under the time-concentration curves (AUC0--6h). The AUC and Cmax values were significantly increased when cortisone tablets were ingested with food compared to the values obtained in the fasting state (p less than 0.01 and p less than 0.05 respectively), whereas tmax values were not significantly different. The differences were minor and probably without clinical implications.

Glucocorticoid-mediated effects on metabolism are reversed by targeting 11 beta hydroxysteroid dehydrogenase type 1 in human skeletal muscle

BACKGROUND

Adipose tissue and liver play important roles in mediating the metabolic actions of glucocorticoids. However, the effects of glucocorticoids on glucose and lipid metabolism in skeletal muscle are not understood completely. Intracellular glucocorticoid action is dependent on 11 beta-hydroxysteroid dehydrogenase 1 (HSD1), an enzyme that converts cortisone to active cortisol.

METHODS

We investigated the direct role of HSD1 in cultured primary human skeletal muscle cells using siRNA and pharmacological inhibitors of the enzyme. Primary human skeletal muscle cells were cultured in the presence of 0.5 microM cortisone or 0.5 microM cortisol for eight days. siRNA was utilized to reduce expression of either HSD1 or pyruvate dehydrogenase kinase (PDK) 4. Effects of pharmacological inhibitors of HSD1 were also studied.

RESULTS

Exposure to cortisone or cortisol decreased basal glucose uptake and glucose incorporation into glycogen, but was without effect on the insulin-stimulated response. Glucocorticoid exposure increased palmitate oxidation, as well as the expression of PDK4. siRNA-mediated reduction or pharmacological inhibition of HSD1 prevented the effects of cortisone, but not cortisol, on metabolic responses. siRNA-mediated reduction of PDK4 prevented the effect of cortisol to attenuate glycogen synthesis.

CONCLUSION

Targeted reduction or pharmacological inhibition of HSD1 in primary human skeletal muscle cells prevents the effects of cortisone, but not cortisol, on glucose metabolism and palmitate oxidation. Furthermore, the glucocorticoid-mediated reductions in glucose metabolism are dependent on PDK4.

Studies on interference with tolerance induction in T cells

The mechanism of T-cell tolerance to a thymus-dependent antigen was examined, using the adjuvant polyadenylic-polyuridylic acid (poly A:U). In adoptive transfer experiments, thymus cells obtained from donor mice 2 days after treatment with a tolerogenic dose of bovine gamma-globulin (sBGG) did not cooperate with bone marrow (BM) cells in irradiated recipients challenged with aggregated BGG (aBGG). In contrast, thymus cells from donors given sBGG plus poly A:U retained their helper activity, as assayed by hemagglutination and rosette formation of spleen cells. The effect of poly A:U in preventing tolerance induction was also demonstrable in the cortisone-resistant population, in that thymus cells from cortisone-treated donors that had received sBGG and poly A:U retained their helper function. The presence of suppressor cells and the effect of poly A:U on their stimulation were also examined. sBGG-treated thymus cells suppressed the response of BGG-primed spleen cells in lethally irradiated mice, whereas thymus cells from donors treated with sBGG and poly A:U were not suppressive. These observations show that poly A:U prevents tolerance induction and the development of suppressor activity in T cells.

Preventive effect of beta-adrenoceptor blockade on glucocorticoid-induced memory retrieval deficits

OBJECTIVE

Elevated glucocorticoid levels impair retrieval of emotional information, and animal studies indicate that this effect depends on concurrent emotional arousal-induced increases in noradrenergic transmission within the brain. The authors investigated whether the beta-adrenoceptor antagonist propranolol blocks glucocorticoid-induced memory retrieval impairments in human subjects.

METHOD

In a double-blind, placebo-controlled study, 42 healthy volunteers were presented a set of words with variable emotionality and asked to learn them for recall. A day later, cortisone (25 mg), propranolol (40 mg), or both drugs were administered orally 1 hour before a free-recall test.

RESULTS

Cortisone selectively impaired the recall of emotionally arousing words by 42%. This impairment was blocked by the concurrent administration of propranolol. Propranolol alone did not affect recall of either emotional or neutral words.

CONCLUSIONS

A pharmacological blockade of beta-adrenoceptors prevents glucocorticoid-induced memory retrieval deficits in human subjects. This finding may have important implications for the treatment of memory deficits in hypercortisolemic states, such as stress and depression.

Conformation-sensitive steroid and fatty acid sites in the transmembrane domain of the nicotinic acetylcholine receptor

The mechanism by which some hydrophobic molecules such as steroids and free fatty acids (FFA) act as noncompetitive inhibitors of the nicotinic acetylcholine receptor (AChR) is still not known. In the present work, we employ Förster resonance energy transfer (FRET) between the intrinsic fluorescence of membrane-bound Torpedo californica AChR and the fluorescent probe Laurdan using the decrease in FRET efficiency (E) caused by steroids and FFA to identify potential sites of these hydrophobic molecules. Structurally different steroids produced similar changes (DeltaE) in FRET, and competition studies between them demonstrate that they occupy the same site(s). They also share their binding site(s) with FFA. Furthermore, the FRET conditions define the location of the sites at the lipid-protein interface. Endogenous production of FFA by controlled phospholipase A2 enzymatic digestion of membrane phospholipids yielded DeltaE values similar to those obtained by addition of exogenous ligand. This finding, together with the preservation of the sites in membranes subjected to controlled proteolysis of the extracellular AChR moiety with membrane-impermeable proteinase K, further refines the topology of the sites at the AChR transmembrane domain. Agonist-induced desensitization resulted in the masking of the sites observed in the absence of agonist, thus demonstrating the conformational sensitivity of FFA and steroid sites in the AChR.

Differential expression, function and response to inflammatory stimuli of 11beta-hydroxysteroid dehydrogenase type 1 in human fibroblasts: a mechanism for tissue-specific regulation of inflammation

Stromal cells such as fibroblasts play an important role in defining tissue-specific responses during the resolution of inflammation. We hypothesized that this involves tissue-specific regulation of glucocorticoids, mediated via differential regulation of the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). Expression, activity and function of 11β-HSD1 was assessed in matched fibroblasts derived from various tissues (synovium, bone marrow and skin) obtained from patients with rheumatoid arthritis or osteoarthritis. 11β-HSD1 was expressed in fibroblasts from all tissues but mRNA levels and enzyme activity were higher in synovial fibroblasts (2-fold and 13-fold higher mRNA levels in dermal and synovial fibroblasts, respectively, relative to bone marrow). Expression and activity of the enzyme increased in all fibroblasts following treatment with tumour necrosis factor-α or IL-1β (bone marrow: 8-fold and 37-fold, respectively, compared to vehicle; dermal fibroblasts: 4-fold and 14-fold; synovial fibroblasts: 7-fold and 31-fold; all P < 0.01 compared with vehicle). Treatment with IL-4 or interferon-γ was without effect, and there was no difference in 11β-HSD1 expression between fibroblasts (from any site) obtained from patients with rheumatoid arthritis or osteoarthritis. In the presence of 100 nmol/l cortisone, IL-6 production – a characteristic feature of synovial derived fibroblasts – was significantly reduced in synovial but not dermal or bone marrow fibroblasts. This was prevented by co-treatment with an 11β-HSD inhibitor, emphasizing the potential for autocrine activation of glucocorticoids in synovial fibroblasts. These data indicate that differences in fibroblast-derived glucocorticoid production (via the enzyme 11β-HSD1) between cells from distinct anatomical locations may play a key role in the predeliction of certain tissues to develop persistent inflammation.

Roles of 11beta-hydroxysteroid dehydrogenase in fish spermatogenesis

In fish spermatogenesis, the main action of progestins is generally regarded as the induction of sperm maturation. Our previous in vitro study demonstrated that a progestin, 17alpha,20beta-dihydroxy-4-pregnen-3-one (DHP), induced the initiation of meiosis in spermatogenesis in the Japanese eel (Anguilla japonica). In the present study, to elucidate the molecular mechanisms underlying the action of DHP, we attempted to clone cDNAs encoding genes whose expression was induced by DHP in eel testis, using cDNA subtraction. One of the cDNAs we isolated encodes eel 11beta-hydroxysteroid dehydrogenase short form (e11beta-HSDsf), and Northern blot and RT-PCR analysis showed that transcripts of e11beta-HSDsf in testis were induced by DHP. The recombinant e11beta-HSDsf had 11beta-dehydrogenase activity, metabolizing cortisol to cortisone, and 11beta-hydroxytestosterone to 11-ketotestosterone (11-KT). In vitro experiments revealed that eel immature testis had 11beta-dehydrogenase activity, and DHP treatment enhanced the activity. To understand the role of 11beta-HSD in spermatogenesis, we examined the direct effects of cortisol on eel spermatogenesis using an organ culture system. Cortisol induced DNA replication in spermatogonia and enhanced the spermatogonial proliferation induced by 11-KT. However, excess cortisol inhibited proliferation. In addition, 11-KT production was induced in testicular fragments incubated with cortisol. These results suggest that optimal levels of cortisol induced spermatogonial mitosis by increasing 11-KT production. Furthermore, two possible roles of DHP on spermatogenesis, via the up-regulation of 11beta-HSD expression, are suggested: positive feedback control of 11-KT production and the modulation of cortisol levels to protect testes from excess circulating cortisol.

11beta-Hydroxysteroid dehydrogenase type 1-driven cortisone reactivation regulates plasminogen activator inhibitor type 1 in adipose tissue of obese women

BACKGROUND

Plasminogen activator inhibitor type 1 (PAI-1) is the main inhibitor of the fibrinolytic system and contributes to an increased risk of atherothrombosis in insulin-resistant obese patients. In adipose tissue, we have shown that PAI-1 is synthesized mainly in the visceral stromal compartment and is positively regulated by glucocorticoids. We have demonstrated that adipose tissue expression of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD-1), an enzyme that catalyzes the conversion of inactive cortisone to active cortisol, is exaggerated in obese patients.

OBJECTIVES

We hypothesized that increased action of 11beta-HSD-1 in adipose tissue of obese subjects may contribute to PAI-1 overproduction.

PATIENTS AND METHODS

Using in situ hybridization, we studied the expression of the mRNAs coding for PAI-1 and 11beta-HSD-1 in the stromal compartment of visceral adipose tissue obtained from obese women. The regulation of PAI-1 secretion from in vitro incubated tissue explants was also investigated.

RESULTS

Regression analysis showed a significant positive linear relationship between PAI-1 and 11beta-HSD-1 mRNAs expression. In vitro incubation of adipose tissue explants demonstrated that cortisone stimulated PAI-1 gene expression and secretion, and that these effects were inhibited by co-incubation with the 11beta-HSD inhibitor, glycyrrhetinic acid.

CONCLUSIONS

Our data demonstrate that 11beta-HSD-1-driven cortisone reactivation regulates adipose PAI-1 synthesis and secretion. They suggest that the increased PAI-1 synthesis and secretion observed in obese patients can be also related, at least in part, to an increased local conversion of cortisone to cortisol. Therefore, local cortisol metabolism in adipose tissue may be involved in increasing the risk of cardiovascular disease in obese subjects.

Increased expression of 11beta-hydroxysteroid dehydrogenase type 1 in type 2 diabetic myotubes

BACKGROUND

Alterations in glucocorticoid hormone metabolism in skeletal muscle have been suggested to contribute to the pathogenesis of the metabolic syndrome. Circulating glucocorticoids consist of inactive cortisone and active cortisol interconverted in various tissues by the enzyme 11beta hydroxysteroid dehydrogenase (HSD). This study aims to investigate whether human myotubes established from healthy obese and matched obese type 2 diabetic (T2D) subjects reveal differences in the expression level of glucocorticoid receptor (GR) and 11beta hydroxysteroid dehydrogenase (HSD1 and HSD2), and to investigate whether chronic exposure to cortisone affects glucose transport.

METHODS

In myotubes established from T2D and healthy control subjects we determined the mRNA expression of HSD1, HSD2, GR and determined basal and insulin-stimulated glucose uptake in myotubes precultured with cortisone, cortisol and the HSD1 inhibitor, carbenoxolone for four days.

RESULTS

Myotubes established from T2D subjects showed an increased expression of HSD1 mRNA, but with no differences in mRNA of GRalpha, LXRalpha and LXRbeta, whereas HSD2 mRNA was not expressed. Cortisone reduced glucose uptake in diabetic myotubes and the cortisone effect could be abolished by the HSD1 inhibitor carbenoxolone.

CONCLUSIONS

Our study shows that cortisone reduces glucose uptake in diabetic myotubes and that this effect seems mediated by an increased mRNA HSD1 expression emphasizing that the local conversion of inactive to active glucocorticoids may be important in the pathogenesis of insulin resistance.

Expression of 11beta-hydroxysteroid dehydrogenase type 1 permits regulation of glucocorticoid bioavailability by human dendritic cells

Glucocorticoids (GCs) exert powerful anti-inflammatory effects that may relate in part to their ability to restrict the differentiation and function of dendritic cells (DCs). Although these inhibitory effects are dependent upon GCs binding to nuclear glucocorticoid receptors (GRs), fine-tuning of GR signaling is achieved by prereceptor interconversion of cortisol that binds GRs with high affinity and cortisone that does not. We show for the first time that human monocyte-derived DCs are able to generate cortisol as a consequence of up-regulated expression of the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). Immature DCs demonstrate selective enhancement of 11beta-HSD1 reductase activity, leading to increased conversion of inactive cortisone to active cortisol. Enhancement of GC bioavailability is maintained or increased upon terminal differentiation induced by signals associated with innate immune activation. In marked contrast, maturation induced by CD40 ligation leads to a sharp reduction in cortisol generation by DCs. The differentiation of DCs from monocyte precursors is inhibited at physiologic concentrations of inactive cortisone, an effect that requires activity of the 11beta-HSD1 enzyme. In conclusion, prereceptor regulation of endogenous GCs appears to be an important determinant of DC function and represents a potential target for therapeutic manipulation.

Ligand-Selective Targeting of the Glucocorticoid Receptor to Nuclear Subdomains Is Associated with Decreased Receptor Mobility

The association between nuclear distribution and mobility of the human glucocorticoid receptor was examined in living COS-1 cells using yellow fluorescent protein- and cyan fluorescent protein-tagged receptors. Quantitation of the nuclear distribution induced by an array of glucocorticoid ligands revealed a continuum from a random (cortisone) to a nonrandom (triamcinolone acetonide) receptor distribution. Structure-function analysis revealed that the 9-fluoro and 17-hydroxy groups on the steroid significantly impact nuclear receptor distribution. Using time-lapse microscopy, the triamcinolone acetonide-induced receptor distribution did not change significantly over a period of 15 sec. However, using fluorescence recovery after photobleaching, the individual receptors moved at a much faster rate, indicating rapid exchange of receptors on immobile nuclear subdomains. Receptor mobilities for 13 different steroids, measured by fluorescence recovery after photobleaching, appeared to correlate with receptor distribution. Ligands that induced a nonrandom distribution induced slower receptor mobility and vice versa. Finally, application of 2-photon confocal microscopy revealed differences in receptor mobility between nuclear subdomains. Areas of high receptor concentration showed slower mobility than areas of low receptor concentration. Thus, glucocorticoid receptors can be targeted (depending on the ligand) to relatively immobile nuclear subdomains. The transient association of receptor with these domains decreases the mobility of the receptor.

Involvement of P-gp in the process of apoptosis in peripheral blood mononuclear cells

Multidrug resistance mediated by the drug-efflux protein P (P-gp) is one of mechanisms that cells use to escape death induced by drugs and other agents. The aim of the study was to evaluate the effect of P-gp inhibition on apoptosis of PHA-activated peripheral blood mononuclear cells (MNC) as well as apoptosis induced by methotrexate (MTX), dexamethasone (DEX), methylprednisolone (MP) and cortisone (COR). Apoptosis was quantified by flow cytometry using Annexin V/PI and terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL). P-gp expression was inhibited using verapamil (VER) and P-gp specific monoclonal antibodies (mAb). VER and mAb enhanced the apoptosis of PHA-activated MNC. Moreover these agents significantly increased the apoptosis induced by MTX, DEX, MP and COR. The results of this study suggest that P-gp is involved in the process of apoptosis in peripheral blood mononuclear cells.