Anti-inflammatory Effects Of Glucocorticoids Research Articles

NEW INSIGHTS INTO THE MOLECULAR BASIS OF GLUCOCORTICOID ACTION

Because of the realization that inflammation plays a primary role in the pathogenesis of asthma, glucocorticoids are now considered to be the most efficacious antiasthmatic agents. 12 The anti-inflammatory effects of glucocorticoids are mediated through receptors that function by modulating gene expression. Glucocorticoid receptors (GRs) are members of the large steroid/nuclear receptor family that also includes receptors for mineralocorticoids, androgens, estrogens, progesterone, vitamin D, thyroid hormone, and retinoic acid. During the past decade, there has been a tremendous increase in the knowledge of the mechanisms through which glucocorticoids affect gene expression. Much is known about how glucocorticoids enhance activation of gene expression, but an important aspect of the anti-inflammatory effects of glucocorticoids in asthma involves repression of the expression of inflammatory mediators, particularly cytokines. There is less knowledge concerning the mechanisms through which glucocorticoids repress gene expression, but this is an important area of research. Studies have also recently demonstrated a significant role for steroid/nuclear receptor co-activators, histone acetylation, and chromatin structure in gene regulation. This article begins with an overview of glucocorticoid receptors and glucocorticoid-induced gene activation and then focuses on mechanisms of glucocorticoid-mediated gene repression.

Glucocorticoid receptor down-regulates c-Jun amino terminal kinases induced by tumor necrosis factor alpha in fetal rat hepatocyte primary cultures.

The effect of dexamethasone on Jun N-terminal kinase (JNK) activity was assayed by using fetal hepatocytes in primary culture. The addition of tumor necrosis factor alpha (TNF-alpha) caused an increase in JNK in a dose- and time-dependent manner. We show that activation of JNK by this extracellular signal is inhibited by dexamethasone in a dose-dependent fashion. This inhibitory effect was observed in cells treated for 10 minutes with dexamethasone in the presence of protein phosphatase inhibitors such as orthovanadate or okadaic acid, or in cells previously treated with actinomycin D. Glucocorticoid receptor (GR) can be precipitated with the fusion protein, GST-c-Jun (1-79), bound to agarose beads. However, the inhibitory effect of glucocorticoids on JNK activity was also observed using ATF-2 as substrate. In addition, dexamethasone inhibits JNK phosphorylation induced by TNF-alpha. Finally, we show that GR can also be phosphorylated in tyrosine residues in response to TNF-alpha and epidermal growth factor (EGF) upon ligand-binding. Our results suggest that the anti-inflammatory effect of glucocorticoids on the inflammatory pathways induced by TNF-alpha can be explained, at least in part, by modulating JNK activity through a direct protein-protein interaction; the JNK phosphorylation and tyrosine-phosphorylation state of GR may be regulatory steps also involved in that effect.

Topical Budesonide Treatment Reduces Endothelial Expression of Intercellular Adhesion Molecules (Vascular Cell Adhesion Molecule-1 and P-selectin) and Eosinophil Infiltration in Nasal Polyps

Infiltration of eosinophil granulocytes and endothelial expression of vascular cell adhesion molecule-1 (VCAM-1) and P-selectin was investigated in biopsies of polyps and inferior turbinates from 16 patients with nasal polyps, by the use of immunohistochemical staining and stereological quantification before, during and after topical treatment with budesonide (Rhinocort® Turbuhaler®). Before glucocorticoid treatment a higher density of eosinophil profiles (p<0.005), making up a larger proportion of the total cellular infiltrate (p<0.0005), was found in the polyps compared with the inferior turbinates. Endothelial VCAM-1 expression was higher in polyps than in inferior turbinates (p<0.005), in contrast with the expression of P-selectin, which was more frequently expressed in the inferior turbinates (p<0.05). Topical glucocorticoid treatment reduced the density of eosinophil profiles (p<0.05) and the endothelial expression of VCAM-1 (p<0.007) and P-selectin (p<0.02) in polyps. Eosinophil counts and VCAM-1 expression returned to pre-treatment levels 8 weeks after discontinuation of budesonide treatment. The observed reduction in endothelial expression of cellular adhesion molecules may interfere with cellular recruitment in nasal polyps and thus contribute to the known anti-inflammatory effect of glucocorticoid in nasal polyposis.

Inhibition of gingival collagenase gene expression by dexamethasone.

Glucocorticoids are potent immunosuppressants shown to be effective in the treatment of inflammatory diseases. Reportedly, they work, in part, by inhibiting cytokines and other transcription factors including AP-1. In this study we investigated the mechanisms of efficient repression of collagenase gene expression by dexamethasone in the human gingival fibroblast. Northern analyses showed that IL-1-dependent collagenase mRNA production was significantly decreased in the presence of dexamethasone. The influence of dexamethasone on the transcription factor NF-kappaB, STAT3, and AP-1 was investigated by using the gel mobility shift assay with nuclear extracts prepared from the cells grown in the presence of dexamethasone. We observed that in addition to AP-1, binding of NF-kappaB and STAT3 to DNA was also decreased significantly. Additionally, dexamethasone induced the transcription of the I kappaB-alpha gene suggesting that in the presence of dexamethasone, NF-kappaB quickly reassociates with newly synthesized I kappaB-alpha and markedly reduces the amount of NF-kappaB. CAT transfection studies utilizing collagenase promoter demonstrated a dose-dependent transcriptional inhibition of IL-1-induced gingival collagenase gene expression by dexamethasone. These data reveal that collagenase gene expression can be regulated by the impairment of IL-1-stimulated NF-kappaB, STAT3, and AP-1 activities, and can highlight a possible molecular mechanism for the anti-inflammatory effects of glucocorticoids.

Effects of dexamethasone and phorbol ester on P2 receptor-coupled Ca2+ signalling and lipocortin 1 presentation in U937 cells.

1. Cell surface bound lipocortin 1 (LC1) is a putative mediator of the antiproliferative and anti-inflammatory effects of glucocorticoids. This study assessed the hypothesis that the glucocorticoid, dexamethasone-phosphate (dex-p), might exert the above effects via an LC1-mediated downregulation of receptor-coupled Ca2+ signalling, using P2-receptor mediated intracellular Ca2+ accumulation in U937 cells as an appropriate model. 2. Addition of ATP (1-100 microM) to cells resulted in a transient increase in cytosolic Ca2+ ([Ca2+]i). Prior treatment of cells with dex-p (3-24 h) increased the magnitude of this Ca2+ transient at high, but not low concentrations of ATP, and increased thapsigargin (Tg)-induced Ca2+ influx, indicating that store-operated Ca2+ influx was potentiated in these cells. For cells treated with dex-p for 24 h, cell surface levels of LC1 were significantly reduced by 63%. 3. Differentiation of cells with 1 nM phorbol ester (PMA) for 24 h resulted in a 2.4 fold increase in the cell surface level of LC1 and inhibition of the ATP-induced Ca2+ response. However, the Tg-induced Ca2+ response was unaffected by long-term PMA treatment, and incubating cells with LC1 did not alter Tg-induced Ca2+ mobilization and influx, or the ATP-mediated Ca2+ response. 4. Data from this study suggest that: (1) dex-p does not inhibit P2-receptor-coupled Ca2+ signalling in this cell line, (2) the observed modulation of the ATP-induced increase in [Ca2+]i by dex-p and PMA, and store-operated Ca2+ influx by dex-p, is not linked to an increase in the cell surface level of LC1, and (3) differentiation of U937 cells with PMA downregulates the ATP-induced Ca2+ response, but does not affect the thapsigargin-sensitive Ca2+ pool or store-operated Ca2+ influx of these cells.

Glucocorticoid receptor signaling in a bronchial epithelial cell line.

Glucocorticoids are an effective anti-inflammatory therapy for the treatment of asthma. The anti-inflammatory effects of glucocorticoids may be due to the inhibition of transcription factors that regulate cytokine synthesis. Because of the potential role of the bronchial epithelium in asthmatic inflammation and the possibility that this cell may be the main target of inhaled glucocorticoids, we have characterized glucocorticoid receptors (GR) and GR signaling in the human bronchial epithelial cell line BEAS-2B. Western blot analysis and radioligand binding studies demonstrated that BEAS-2B cells have functional GR that bind to dexamethasone (Dex) (dissociation constant = 5.6 nM and maximal density of binding sites = 228 +/- 3.3 fmol/mg protein). GR were activated by Dex as assessed using a glucocorticoid-responsive reporter plasmid. Transfection of BEAS-2B cells with an activator protein-1 (AP-1) reporter construct followed by 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment resulted in a fivefold induction of reporter gene activity. Transfection with a nuclear factor (NF)-kappa B reporter construct followed by tumor necrosis factor-alpha (TNF-alpha) treatment resulted in a 10-fold induction of reporter gene activity. Dex (10(-7) M) markedly repressed both the induced AP-1 and NF-kappa B activity. The GR antagonist RU-486 inhibited the repressive effect of Dex on TNF-alpha-induced NF-kappa B activity by 81% but only counteracted the repressive effect of Dex on TPA-induced AP-1 activity by 43%. These studies demonstrate that cross-signaling between AP-1 and NF-kappa B with GR may explain the anti-inflammatory properties of glucocorticoids in airway epithelial cells.

Regulatory role for macrophage migration inhibitory factor in acute respiratory distress syndrome.

Migration inhibitory factor (MIF) is known to exert significant pro-inflammatory effects and has the potential to override the anti-inflammatory action of glucocorticoids. In this study we have identified significant quantities of MIF in the alveolar airspaces of patients with acute respiratory distress syndrome (ARDS). We show in alveolar cells from patients with ARDS that MIF augments pro-inflammatory cytokine secretion (TNF alpha and IL-8), anti-MIF significantly attenuates TNF alpha and IL-8 secretion and MIF overrides, in a concentration-related fashion, the anti-inflammatory effects of glucocorticoids. These findings suggest that MIF may act as a mediator sustaining the pulmonary inflammatory response in ARDS and that an anti-MIF strategy may represent a novel therapeutic approach in inflammatory diseases such as ARDS.

Modulation of in vitro cytokine release from human leukemic mast cells (HMC-1) by glucocorticoids.

Mast cells are well known effector cells not only in allergic but also in diverse acute and chronic inflammatory diseases. We have shown previously that these cells produce a broad spectrum of cytokines which might contribute to mast cell-dependent pathology. In the present study, we have investigated the influence of four potent glucocorticoids, methylprednisolone-aceponate, methylprednisolone-17-propionate, prednicarbate, and betametasone valerate (10(-5) M-10(-9) M), on the IL-1 beta, IL-3, IL-8, and tumor necrosis factor alpha secretion of the HMC-1 mast cell line as measured by ELISA. All four glucocorticoids caused a comparable dose- and time-dependent inhibition of cytokine release from HMC-1 cells stimulated for 24 h with phorbol 12-myristate 13-acetate 25 ng/ml and calcium ionophore 2 x 10(-7) M. These results shed further light on the mechanisms involved in antiinflammatory effects of glucocorticoids in allergic inflammation.

Effect of RU 486 on the atrophogenic and antiinflammatory effects of glucocorticoids in skin

Clobetasol-17-propionate (CP), a synthetic glucocorticoid (GC), reduced skin thickness in rats. Both the subcutaneous injection and topical applications of RU 486 counteracted CP-induced reduction in skin thickness. Topical application of the CP cream completely inhibited the ear edema produced by croton oil. A less potent GC, hydrocortisone-17-butyrate, also inhibited ear edema. This antiinflammatory effect was not abolished by the subcutaneous injection or topical application of RU 486. These observations suggest that GC-induced skin atrophy is mediated by glucocorticoid receptors (GRs), while the inhibition of croton oil-induced inflammation by GC is primarily related to the direct effects of GC, which are not mediated by GRs. Our findings suggest that RU 486 inhibits the atrophogenic effect of GCs without interfering with their antiinflammatory effect. Dissociation of antiinflammatory and atrophogenic activity of GC seems favorable in treating inflammatory skin diseases lacking epidermal proliferation.

Steroid resistance in asthma

Resistance to the anti-inflammatory effects of glucocorticoids in asthma and other inflammatory and immune diseases is uncommon, but presents a management problem. Understanding the mechanisms of steroid resistance provides new insights into the mechanism of steroid action as well as the underlying chronic disease process. In patients with primary steroid-resistant (SR) asthma there is no abnormality in the pharmacokinetics of the exogenous steroid and no significant defect in steroid binding to the glucocorticoid receptor (GR). Recent studies have demonstrated a marked reduction in the binding of GR to DNA; this appears to be due to increased binding of GR to the transcription factor activator protein-1 (AP-1). Secondary steroid resistance in asthma may arise in response to the release of cytokines that activate AP-1 and other transcription factors that bind directly to GR. A similar effect may also be seen with high concentrations of beta 2-agonists that activate another GR binding transcription factor, CREB. Several existing and novel treatment strategies are possible in the management of SR asthma.

A factor released by monocytes in the presence of dexamethasone stimulates neutrophil locomotion.

1. Steroid-treated monocyte supernatants cause a dramatic increase in the speed of locomotion of human neutrophils and a significant decrease in their adhesion to protein-coated glass. In contrast, control monocyte supernatants have a smaller effect on the speed of locomotion, but cause a large increase in their adhesiveness. 2. This supernatant activity was produced equally well in the presence or absence of serum after 24 h culture at 37 degrees C with 10(-6) M dexamethasone. 3. The effect of the steroid-treated monocyte supernatants on the speed of locomotion of human peripheral blood neutrophils was not altered by rabbit polyclonal antisera against lipocortins 1-6. 4. Rabbit anti-interleukin-8 antibody which blocked the effect of IL-8 on the speed of locomotion of neutrophils did not antagonize the locomotion stimulating action of steroid-treated monocyte supernatants. 5. The exocellular release of this factor(s) by human mononuclear leucocytes suggests that it may be an in vivo mediator of the anti-inflammatory effect of glucocorticoids.

Neutral endopeptidase and kininase II mediate glucocorticoid inhibition of neurogenic inflammation in the rat trachea.

Glucocorticoids inhibit plasma extravasation induced in the rat tracheal mucosa by substance P and other tachykinins released from sensory nerves. This study was performed to determine whether this antiinflammatory effect of glucocorticoids is mediated by the tachykinin-degrading enzymes neutral endopeptidase (NEP) and kininase II (angiotensin converting enzyme, ACE). In addition, we studied the effect of dexamethasone on a nonpeptide inflammatory mediator, platelet-activating factor (PAF), which is not degraded by NEP or ACE. Adult male pathogen-free F344 rats were treated for 2 d with dexamethasone (0.5 mg/kg per d i.p.), or with the vehicle used to dissolve the steroid. The magnitude of plasma extravasation produced by an intravenous injection of substance P (5 micrograms/kg) or PAF (10 micrograms/kg) was then assessed by using Monastral blue pigment as an intravascular tracer. The role of NEP and ACE activities in the changes produced by dexamethasone was investigated by examining the effect of the selective inhibitors of these enzymes, phosphoramidon and captopril. Dexamethasone reduced the substance P-induced extravasation by 57% but did not affect the PAF-induced extravasation. The suppressive effect of dexamethasone on substance P-induced extravasation was completely reversed by simultaneously inhibiting NEP and ACE activities, but the inhibition of these enzymes had no effect on PAF-induced extravasation, regardless of whether the rats were pretreated with dexamethasone or not. These results suggest that NEP and ACE mediate a selective inhibitory effect of glucocorticoids on neurogenic plasma extravasation.

Sex steroids, glucocorticoids, stress and autoimmunity

Interest in the field of neuroimmunoendocrinology is in full expansion. With regard to this, steroid influence on the immune system, in particular sex steroids and glucocorticoids, has been known for a long time. Sex steroids are part of the mechanism underlying the immune sexual dimorphism, as particularly emphasized in autoimmune diseases. Immunosuppressive and anti-inflammatory effects of glucocorticoids are now considered a physiological negative feedback loop to cytokines produced during an immune and/or inflammatory response. Psychosocial factors may play a role in the development of immunologically-mediated diseases, e.g. autoimmune diseases. The nonobese diabetic (NOD) mouse, that develops an immunologically-mediated insulin-dependent diabetes mellitus (IDDM) is an interesting model to study the role of endogenous steroids. Insulitis is present in both sexes, but diabetes has a strong preponderance in females. Hormonal alteration, such as castration, modulates the incidence of diabetes, whereas environmental factors, such as stress, accelerate the disease. In the present paper, we have reviewed the role of gender, sex steroid hormones, stress and glucocorticoids in autoimmunity as well as analyzed their different levels of actions and interrelationships, focusing particular attention on the immunologically-mediated IDDM of the NOD mouse.

Correlation in inflammatory fibroblasts between the number of glucocorticoid receptors and PGE 2 release

The anti-inflammatory effects of glucocorticoids are mediated through steroid receptor occupancy and there is a significant correlation between the extent of receptor saturation and the extent of the biological effects. In a previously published study, we found that the number of these receptors was higher in inflammatory fibroblasts than in quiescent ones. PGE 2 release, measured at the same time as the number of steroid receptors, was higher when the cells were from inflammatory tissue. Our aim, in the present study, was to determine whether the PGE 2 released by cells during inflammatory processes could participate in increasing the number of steroid receptors. Fibroblasts obtained from rat quiescent subcutaneous connective tissue and granulomas were subcultured in monolayers. The specific binding of [ 3H]dexamethasone was assessed and analyzed by a method described by Kalimi et al. After a freeze-thaw cycle, we observed a decrease in the number of receptors in inflammatory fibroblasts. When the frozen and thawed fibroblasts were subcultured in the presence of PGE 2 (10 −8 M), the number of receptors was enhanced in fibroblasts from inflammatory tissue. Cycloheximide (3 × 10 −7 M) prevented this increase. The release of PGE 2 decreased after freezing and then increased simultaneously with the number of receptors in inflammatory cells. These findings suggest that PGE 2 may play a role in regulating steroid effects on fibroblast function.

Vasocortin: a novel glucocorticoid-induced anti-inflammatory protein.

The preliminary characterization of ;vasocortin' a novel glucocorticoid-induced anti-inflammatory protein, is described. Vasocortin is released into the rat peritoneal cavity following systemic dexamethasone administration, has an apparent mol. wt. of 100 kD and inhibits rat dextran oedema. Vasocortin is distinct from lipocortin and is likely to be associated with the anti-inflammatory effect of glucocorticoids.

Factors secreted by untreated and hydrocortisone-treated monocytes that modulate neutrophil function.

When incubated for 1.0 hr with neutrophils isolated from bovine peripheral blood, hydrocortisone (0.05, 0.5, or 5.0 micrograms/ml) had no significant effect on their ability to ingest Staphylococcus aureus, to reduce nitroblue tetrazolium (NBT) or iodinate protein, or to mediate antibody-dependent cell-mediated cytotoxicity (ADCC) against chicken erythrocytes. Random migration was significantly enhanced by the highest concentration of hydrocortisone (HC) but was unaffected by the lower concentrations. Resting bovine monocytes were incubated for 24 hr in medium with or without added hydrocortisone (0.05, 0.5, or 5.0 micrograms/ml). Purified bovine neutrophils were then incubated for 1.0 hr with the resulting monocyte supernatant (MS). The MS from untreated monocytes significantly enhanced neutrophil ADCC but did not affect the other neutrophil functions evaluated. Supernatants from monocytes incubated with 0.5 or 5.0 micrograms/ml hydrocortisone (HC-treated MS) failed to enhance neutrophil ADCC but did enhance neutrophil random migration under agarose. The other parameters of neutrophil function were unaffected. Production of the factors in MS was reduced by inhibition of protein synthesis in monocytes. Their activity was reduced by exposure of MS to proteolytic enzymes, suggesting that the monocyte factors were polypeptides or proteins. Protein synthesis by the neutrophil was not necessary for its response to the monocyte-produced ADCC-enhancing factor but was necessary for its response to the HC-induced monocyte factor. The results suggest that the antiinflammatory effects of glucocorticoids may be partially mediated by factors released by monocytes.

Dexamethasone-mediated inhibition of human T cell growth factor and gamma-interferon messenger RNA.

Glucocorticoids suppress the proliferation of human T lymphocytes. Activated T lymphocytes require T cell growth factor (TCGF) for proliferation. TCGF is produced by a subset of T lymphocytes, and this production is regulated at the TCGF mRNA level. Dexamethasone, a synthetic glucocorticoid, strongly inhibits the synthesis of TCGF mRNA in human normal peripheral blood lymphocytes stimulated in culture with phytohemagglutinin. It also inhibits the accumulation of gamma-interferon mRNA in these cells. This dual effect may in part explain some of the immunosuppressive and anti-inflammatory effects of glucocorticoids.

Anti-inflammatory effects of polyamines in serotonin and carrageenan paw edemata - possible mechanism to increase vascular permeability inhibitory protein level which is regulated by glucocorticoids and superoxide radical.

Serotonin paw edema of mice and carrageenan paw edema of rats were inhibited by subcutaneously or orally administered certain polyamines. They must be given at least 2 h before serotonin challenge to get inhibitions which were blocked by the concomitant injections of cycloheximide. Thirty percent inhibitory dose (ID30) of polyamines (s.c.) 3 h before serotonin (s.c.) were: spermidine (8 mg/kg), spermine 28 mg/kg) and putrescine (55 mg/kg). Agmatine, cadaverine, ornithine, citrulline, lysine and arginine were not inhibitory even at 200 mg/kg. Three inhibitory polyamines were effective by oral administration but were not inhibitory by local administration into the paws. Intravenous injections of spermidine also required 2 h of lag period for inhibitions. Serotonin edema was inhibited by dexamethasone (1 mg/kg), prednisolone (1 mg/kg) or by superoxide dismutase (SOD, 5 mg/kg) in lag period requiring manner (s.c. and i.v.). High dose of cyclo-oxygenase inhibitors indomethacin and diclofenac sodium, lipo-oxygenase inhibitor BW755C (30 mg/kg s.c., respectively) and phospholipase A2 inhibitor quinacrine (100 mg/kg s.c.) failed to inhibit serotonin edema, suggesting that arachidonate metabolites are not participating in this model. ID30 of polyamines which were administered (s.c. and oral) to rats 3 h before carrageenan and determined at 3 h by paw weight were: spermidine (28 and 100 mg/kg), spermine (18 and 90 mg/kg) and putrescine (both greater than 200 mg/kg). Adrenalectomized rats responded to polyamines just as normal rats. Local vascular permeability, irritancy and acute toxicity were also tested in mice. Polyamines were proved to be glucocorticoid-type anti-inflammatory drugs. Polyamines may be mediators of glucocorticoids for the synthesis of the postulated vascular permeability inhibitory protein (called as 'vasoregulin' for convenience). Anti-inflammatory effect of glucocorticoid is recently explained by its capacity to induce phospholipase A2 inhibitory protein(s) (macrocortin or lipomodulin). However, this hypothesis has not yet been proved by in vivo experiment and our data suggest that there is induction by glucocorticoid of another kind of protein which does not inhibit phospholipase A2 activity.

Effects of glucocorticoids and disodium cromoglycate on avidin production in chick tissues.

The effects of anti-inflammatory glucocorticoids and a membrane stabilizer (disodium cromoglycate) on avidin induction were studied. Chicks were primed for 0, 3 or 7 days with diethylstilboestrol (DES; 0.5 mg/day per animal, s.c.). Actinomycin D (0.2 mg/kg, i.p.) stimulated avidin production in the oviduct, intestine, lung and wing muscle of both DES-primed and unprimed chicks. Prednisolone (5 mg/animal, i.m.) given 1 h before actinomycin D reduced the avidin amounts to control levels in the unprimed oviducts and in non-oviductal tissues. The signs of inflammation (ascites, oedema) in chicks receiving actinomycin D also disappeared with prednisolone premedication. Cortisol (50 mg/animal, i.m. or 1, 5 or 50 microgram/ml medium), prednisolone (5 mg/animal, i.m. or 0.5, 5, 10 or 50 microgram/ml medium) and dexamethasone (1 mg/animal, i.m. or 0.05 or 0.5 microgram/ml medium) stimulated avidin production in DES-primed oviducts in vivo and in vitro. Culture in vitro induced avidin production in lung and oviduct but not in wing muscle. This avidin production in culture was not inhibited by cortisol, prednisolone or disodium cromoglycate. It is concluded that actinomycin D induces avidin production through its inflammatory effect and that the induction can be prevented by anti-inflammatory glucocorticoids. It is proposed that the 'spontaneous' avidin production in culture is not the effect of trauma during tissue preparation but rather a new form of avidin induction.

The role of glucocorticoid receptor and gene expression in the anti-inflammatory action of dexamethasone.

GLUCOCORTICOIDS are potent anti-inflammatory agents, but the molecular mechanisms involved in this activity are not yet understood. The biological actions of various steroid hormones have been shown to be mediated by functional proteins synthesised following translocation of a hormone-cytoplasmic receptor complex into the nucleus1,2. It is still not clear, however, whether the anti-inflammatory effects of glucocorticoids are mediate via binding to a cytoplasmic receptor in target cells and subsequent activation of gene expression3, although glucocorticoid receptors have been demonstrated in HTC cells, liver5, thymocytes6 and lymphocytes7. The results reported here suggest that a glucocorticoid receptor and the induction of gene expression are involved in the anti-inflammatory action of dexamethasone.