Steroid receptor number. Individual variation and downregulation by treatment

Intra-Articular Slow-Release Triamcinolone Acetonide from Polyesteramide Microspheres as a Treatment for Osteoarthritis

Osteoarthritis (OA) is a common cause of pain and disability. Local corticosteroid injections are effective in treating OA pain and inflammation but are short-acting. Prolonged intra-articular (IA) corticosteroid exposure may even lead to cartilage deterioration. The aim of this prospective study was to assess safety and provide proof-of-concept of IA-applied biodegradable polyesteramide-based microspheres (PEAMs) gradually releasing triamcinolone acetonide (TA). Mimicking continuous exposure associated with local drug delivery in canine articular chondrocytes cultured in the continuous presence of TA tissue regeneration was not affected, whereas intermittent exposure reduced proteoglycan production. In this respect, TA-PEAMs administered IA in a proof-of-concept study in 12 client-owned dogs with established OA also showed safety by radiographic examination, without changes in OA severity and in glycosaminoglycan synovial fluid levels. Treatment also resulted in clinical improvement in 10 out of 11 dogs during the two-month follow-up period, which persisted in 6 out of 10 dogs after 6 months, based on objective gait analysis and owner questionnaires. Synovial prostaglandin E₂, a pro-inflammatory marker, was decreased two months after treatment. This study showed safety and proof-of-concept of IA-administered TA-PEAMs in dogs with OA, as a first step towards translation into the veterinary and human clinic.

Methylprednisolone pulse therapy rescued life-threatening pulmonary hemorrhage due to idiopathic pulmonary hemosiderosis

Idiopathic pulmonary hemosiderosis (IPH) is an extremely rare cause of massive pulmonary hemorrhage in children. During the acute phase, death due to massive alveolar hemorrhage and subsequent severe respiratory failure. We report two cases of IPH children who developed hypoxemic respiratory failure and massive pulmonary hemorrhage. One case of a 10-year-old boy was treated with methylprednisolone pulse therapy (10mg/kg/d) for the first three days and followed by systemic steroid therapy, he successfully decannulated 10days later and discharged with a favorable quality of life. Another case of a 4year-old female child with Down's syndrome diagnosed as IPH for over one year and treated with oral corticosteroids for maintenance therapy. She sudden suffered severe hypoxemia with rapid falls in the hemoglobin level. We applied methylprednisolone pulse therapy (10mg/kg/d) for three days and other supportive therapies, the girl survived through complicated with oxygen dependence. We suggest that methylprednisolone pulse therapy provides a chance of recovery and survival for patients with IPH at the acute phase, even if accompanied by severe pulmonary hemorrhage.

Symptomatic treatment of pollen-related allergic rhinoconjunctivitis in children: randomized controlled trial

BACKGROUND

About 12% of children are affected by allergic rhinoconjunctivitis (AR). Although the main symptomatic treatments are intranasal corticosteroids (INCS) (daily or on demand) and oral antihistamines, it remains unclear which treatment provides the best relief of symptoms. Therefore, this study examines whether daily use of INCS is superior to on-demand use or to oral antihistamines on demand.

METHODS

A single-blinded randomized controlled trial in children (aged 6-18 years) with pollen-related AR. Patients received either INCS daily (fluticasone propionate), INCS on demand (fluticasone propionate) or oral antihistamine on demand (levocetirizine) for 3 months during the grass pollen season. A daily online symptom diary on both nose and eye symptoms was completed. The primary outcome was the percentage of symptom-free days.

RESULTS

A total of 150 children were randomized. The percentage symptom-free days was in favour of INCS on demand (30%) compared with INCS daily (22%), that is 8% difference (95% CI -5 to +21%; not significant). The antihistamine on-demand group had 15% symptom-free days, that is 7% difference compared to INCS daily (95% CI -6 to +19%;, not significant). Patients in the INCS on-demand group used on average 61% less fluticasone than patients in the INCS daily group during the study period (P < 0.0001).

CONCLUSIONS

This trial with three parallel treatment groups shows that INCS daily was not superior to INCS on demand or to antihistamine on demand regarding the number of symptom-free days. An on-demand INCS strategy has the advantage of a lower overall corticosteroid exposure and less costs.

The ability of H1 or H2 receptor antagonists or their combination in counteracting the glucocorticoid-induced alveolar bone loss in rats

BACKGROUND

The aim of the present study was to compare between three possible osteoporotic treatments in prevention of glucocorticoid-induced alveolar bone loss.

METHODS

Fifty adult female Wistar rats with an average weight 150-200 g were randomized into five groups: group I (control) was intraperitoneally injected with saline. The other experimental groups (II & III, IV & V) were intraperitoneally injected with 200 µg/100 g body weight dexamethasone. The experimental groups III, IV and V received intraperitoneal injection of 10 mg/kg/day pheniramine maleate (H1 receptor antagonist), ranitidine hydrochloride (H2 receptor antagonist) and concomitant doses of both H1 & H2 receptor antagonists respectively. After 30 days, the rats have been sacrificed. The mandibles were examined histologically, histochemically and histomorphometrically. The bone mineral density was measured using dual-energy X-ray absorptiometry (DEXA).

RESULTS

Histopathologically the glucocorticoid group showed wide medullary cavities with wide osteocytic lacunae. These marrow cavities were reduced in the prophylactic groups (III, IV) but increased in group V. Bone histomorphometric analysis revealed improvement in static bone parameters in groups III and IV and deterioration in group V in comparison to group II. The DEXA revealed significant reduction in the bone mineral density in all experimental groups compared to the control group.

CONCLUSIONS

In a rat model, the administration of H1 or H2 receptor antagonists separately could minimize the alveolar bone loss caused by the administration of glucocorticoids while concomitant administration of both H1 and H2 receptor antagonists deteriorated the bone condition.

Regulation of glucocorticoid receptor in nasal polyps by systemic and intranasal glucocorticoids

BACKGROUND

Poor response of nasal polyps to glucocorticoids (GCs) may be because of abnormal expression of GC receptors (GR) alpha and beta or to downregulation of GRalpha. We aimed to evaluate the in vivo regulation of GR isoforms in GC-treated nasal polyps and to assess the relationship between clinical response to GCs and GR levels.

METHODS

Patients with nasal polyps were randomly (3:1) treated (n = 51) or not (n = 14) with oral prednisone and intranasal budesonide for 2 weeks, plus intranasal budesonide for 10 additional weeks. Nasal symptoms were evaluated. Biopsies were obtained before (w0) and after 2 (w2) and 12 (w12) weeks of treatment, and analysed for their inflammatory content and GR mRNA (10(2) cDNA copies/mug total RNA) and protein (% immunoreactive inflammatory cells) expression. Healthy nasal mucosa (n = 11) was also investigated. Data are presented as median and 25-75th percentile.

RESULTS

At w0, nasal polyps expressed less GRalpha mRNA (1343;683-2263; P < 0.05) and GR protein (41;29-54; P < 0.05) than nasal mucosa (2474;1346-2933; 60;51-72, respectively). GRbeta immunoreactivity was higher in nasal polyps (11;4-19; P < 0.05) than in nasal mucosa (5;2-5). At w2, increased GRalpha mRNA (2010;1037-2732; P < 0.01) and GR protein (56;27-71; P = 0.056) were found compared with w0 (1177;759-2058; 37;29-55, respectively). At w12, GRalpha mRNA and GR protein were similar to w0. GRbeta expression was unaltered by treatment. Neither GRalpha nor GRbeta correlated with nasal symptoms. GR immunoreactivity negatively correlated with eosinophils (r = -0.478; P < 0.001).

CONCLUSIONS

GRalpha is downregulated in nasal polyps and upregulated by GC treatment. Neither GRalpha nor GRbeta appear to determine the sensitivity to GCs in nasal polyposis.

Selective regulation of bone cell apoptosis by translational isoforms of the glucocorticoid receptor

Glucocorticoids are widely used in the treatment of inflammatory and other diseases. However, high-dose or chronic administration often triggers troublesome side effects such as metabolic syndrome and osteoporosis. We recently described that one glucocorticoid receptor gene produces eight translational glucocorticoid receptor isoforms that have distinct gene-regulatory abilities. We show here that specific, but not all, glucocorticoid receptor isoforms induced apoptosis in human osteosarcoma U-2 OS bone cells. Whole human genome microarray analysis revealed that the majority of the glucocorticoid target genes were selectively regulated by specific glucocorticoid receptor isoforms. Real-time PCR experiments confirmed that proapoptotic enzymes necessary for cell death, granzyme A and caspase-6, were induced by specific glucocorticoid receptor isoforms. Chromatin immunoprecipitation assays further suggested that glucocorticoid receptor isoform-dependent induction of proapoptotic genes was likely due to selective coregulator recruitment and chromatin modification. Interestingly, the capabilities to transrepress proinflammatory genes were similar among glucocorticoid receptor isoforms. Together, these findings provide new evidence that translational glucocorticoid receptor isoforms can elicit distinct glucocorticoid responses and may be useful for the development of safe glucocorticoids with reduced side effects.

Expression of glucocorticoid receptors in non-neoplastic lymphoid follicles and B cell type malignant lymphomas

OBJECTIVE

To evaluate the expression of human glucocorticoid receptors (hGRs), such as hGR (4H2), hGR-alpha, and hGR-beta, in non-neoplastic lymphoid follicles and B cell type malignant lymphomas.

METHODS

The expression of hGRs in non-neoplastic lymphoid follicles and malignant lymphomas, including diffuse large cell lymphoma, mantle cell lymphoma, and follicular lymphoma, was examined immunohistochemically. HGR (4H2) expression was confirmed by double immunostaining of tissues and in isolated cells from tonsillar germinal centres, and by immunoelectronmicroscopy.

RESULTS

In secondary lymphoid follicles of any non-neoplastic diseases--such as chronic tonsillitis, reactive lymphadenitis, and Kimura's disease--the germinal centre cells often expressed hGR (4H2) and hGR-alpha. Double immunocytochemical staining of isolated germinal centre cells showed that the majority of hGR (4H2) positive cells were CD20 positive B cells, and that follicular dendritic cells also expressed hGR. Immunoelectronmicroscopy revealed the presence of nuclear hGR (4H2) in the binucleated follicular dendritic cells and germinal centre cells. The frequency of hGR (4H2) expression in diffuse large B cell lymphoma was higher, that in mantle cell lymphoma was lower, and that in follicular lymphoma was intermediate among the types of malignant lymphoma. The hGR (4H2) expression was less frequent in cases of grade I follicular lymphoma.

CONCLUSIONS

There are differences in hGR expression between the germinal centre and the mantle zone in non-neoplastic lymphoid follicles, and differences of hGR (4H2) expression among the types of malignant lymphoma and grades of follicular lymphoma, which probably contribute to the different steroid sensitivities.

Use of corticosteroids, other immunosuppressive therapies, and tonsillectomy in the treatment of IgA nephropathy

Because IgA nephropathy (IgAN) was originally regarded as a benign condition, the indication of corticosteroids or other immunosuppressive therapies have been highly restricted because of potential side effects, and such drugs have been used for a specific subgroup of patients with IgAN, taking the risk/benefit ratio into consideration. During the last decade, however, with the recognition that the overall long-term prognosis of IgAN is a nonbenign condition, more aggressive treatments, including high-dose corticosteroids, various immunosuppressive agents, and tonsillectomy, have been used for wider subgroups of patients with IgAN. Moreover, recent studies have suggested that clinical remission as well as histopathologic regression of the nephropathy could be obtained by such treatments if treatment is initiated in its relatively early stage. Thus, the possibility has now been raised that the goal of treatment for patients with IgAN will shift from "slowing the progression of nephropathy" to "remission of nephropathy."

15-Deoxy-Δ12,14-Prostaglandin J2 Inhibits Glucocorticoid Binding and Signaling in Macrophages through a Peroxisome Proliferator-Activated Receptor γ-Independent Process

15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)) is involved in the control of inflammatory reaction. We tested the hypothesis that 15d-PGJ(2) would exert this control in part by modulating the sensitivity of inflammatory cells to glucocorticoids. Human U937cells and mouse RAW 264.7 cells were exposed to 15d-PGJ(2), and binding experiments were performed with [(3)H]dexamethasone as a glucocorticoid receptor (GR) ligand. 15d-PGJ(2) caused a transient and concentration-dependent decrease in [(3)H]dexamethasone-specific binding to either cells through a decrease in the number of GR per cell without significant modification of the K(d) value. These changes were related to functional alteration of the GR rather than to a decrease in GR protein. They did not require the engagement of peroxisome proliferator-activated receptor gamma (PPARgamma), because the response to 15d-PGJ(2) was neither mimicked by the PPARgamma agonist ciglitazone nor prevented by the PPARgamma antagonist bisphenol A diglycidyl ether. 15d-PGJ(2) altered GR possibly through the interaction of its cyclopentenone ring with GR cysteine residues because the cyclopentenone ring per se could mimic the effect of 15d-PGJ(2), and modification of GR cysteine residues with methyl methanethiosulfonate suppressed the response to 15d-PGJ(2). Finally, 15d-PGJ(2)-induced decreases in glucocorticoid binding to GR resulted in parallel decreases in the ability of GR to activate the transcription of a glucocorticoid-inducible reporter gene and to reduce the expression of monocyte chemoattractant protein-1. Together these data suggest that 15d-PGJ(2) limits glucocorticoid binding and signaling in monocytes/macrophages through a PPARgamma-independent and cyclopentenone-dependent mechanism. It provides a way in which 15d-PGJ(2) would exert proinflammatory activities in addition to its known anti-inflammatory activities.

Enhanced sensitivity to glucocorticoids in peripheral mononuclear leukocytes in posttraumatic stress disorder

BACKGROUND

The aim of this study was to determine whether there is increased responsiveness to corticosteroids in posttraumatic stress disorder (PTSD) by examining the differential effects of dexamethasone (DEX) on the inhibition of lysozyme activity.

METHODS

60 mL of blood was withdrawn at 8:00 am, and mononuclear leukocytes were isolated from the blood of 26 men with, and 18 men without, PTSD. An aliquot of live cells was incubated with a series of concentrations of DEX to determine the rate of inhibition of lysozyme activity; a portion of cells was frozen for the determination of glucocorticoid receptors (GR).

RESULTS

Subjects with PTSD showed evidence of a greater sensitivity to glucocorticoids as reflected by a significantly lower mean concentration (nmol/L) of dexamethasone at which 50% of lysozyme activity is inhibited (IC(50-DEX)) (PTSD+ = 4.9 +/-.53; PTSD- group = 7.2 +/-.64). The lysozyme IC(50-DEX) was significantly correlated with age at exposure to the first traumatic event in subjects with PTSD (r =.44, n = 26, p =.025). The number of cytosolic glucocorticoid receptors was also correlated with age at exposure to the focal traumatic event (r = -.44, n = 25, p =.03) in PTSD.

CONCLUSIONS

This is the first in vitro demonstration of an alteration in target tissue sensitivity to glucocorticoids in PTSD. The lower lysozyme IC(50-DEX) might be related to the risk factor of prior exposure to trauma.

Relationship between dexamethasone-inhibited lysozyme activity in peripheral mononuclear leukocytes and the cortisol and glucocorticoid receptor response to dexamethasone

The assessment of lysozyme activity in mononuclear leukocytes (MNLs) following the in vitro administration of dexamethasone (DEX) provides a measure of peripheral glucocorticoid sensitivity. The goal of the present study was to determine the relationship between the IC(50) of lysozyme activity following such challenge, and the cortisol response to oral administration of 0.50 mg DEX in 18 healthy subjects. The results demonstrated a robust association between the IC(50) and both cortisol decline and percent suppression of cortisol in response to low-dose DEX. However, this measure was uncorrelated with pre or post DEX cortisol levels or GR number. The high correlation between the inhibitory effect of DEX on lysozyme synthesis and two measures reflecting cortisol suppression in response to oral DEX reflects the similarities of GC responsiveness in both in vivo and in vitro models, and suggests that the in vitro assessment of lysozyme activity in MNLs may be useful in the study of neuropsychiatric or other clinical disorder.

A novel specific bioassay for the determination of glucocorticoid bioavailability in human serum

OBJECTIVE

Some patients develop side-effects even on relatively low doses of topically administered glucocorticoids (GCs), while others appear to be less sensitive to GCs. We have developed and validated a bioassay which can measure glucocorticoid bioavailability directly from small amounts of human serum to help elucidate underlying mechanisms.

METHODS

We have stably transfected the human embryonic kidney cell line HEK293 with a plasmid expressing the glucocorticoid receptor, and a plasmid containing the luciferase gene preceded by three concatenated steroid response elements, bringing luciferase expression under control of the liganded glucocorticoid receptor.

RESULTS

The assay, with an intra- and interassay coefficient of variance (CV) better than 10%, showed the expected difference in potency between different GCs (fluticasone propionate > budesonide > dexamethasone > hydrocortisone). No cross-reactivity was detected with other steroid hormones such as progesterone, testosterone and oestradiol. The bioassay easily detects the rise and subsequent fall of bioavailable GCs in human serum following ingestion of only 0.5 mg dexamethasone, and clearly reflects the diurnal cortisol rhythm. Moreover, systemic availability following inhalation of 2 x 250 micro g fluticasone propionate using a pressure dose inhaler could be demonstrated.

CONCLUSIONS

This assay can be used to determine levels of bioavailable GCs in serum, both endogenous and administered, and thus may help in optimizing treatment regimens. The small amount of serum needed to perform an analysis makes this assay applicable even to infants.

Transforming growth factor-beta 1 increases glucocorticoid binding and signaling in macrophages through a Smad- and activated protein-1-mediated process

BACKGROUND

Renal inflammation is regulated by a network of local and systemic mediators. Of them, transforming growth factor-beta1 (TGF-beta 1) and glucocorticoids play an important role in deactivating monocytes/macrophages. We examined the hypothesis that TGF-beta 1 effects may be partially achieved through modulation of the sensitivity of these cells to glucocorticoids.

METHODS

Human promonocytic U 937 cells differentiated to a mature macrophage-like phenotype were exposed to recombinant TGF-beta 1 before specific binding of [3H] dexamethasone was measured. The expression of glucocorticoid receptor (GR) was examined by RNase protection assay and Western blot analysis. The role of Smad 2/3 and activator protein 1 (AP-1) in the response to TGF-beta 1 was determined by introducing transdominant negative mutants and decoy oligodeoxynucleotides, respectively.

RESULTS

U 937 cell exposure to TGF-beta 1 caused a dose- and time-dependent increase in [3H] dexamethasone binding to these cells, with a < or =twofold increase in the number of binding sites per cell, without modification of the affinity. The changes in glucocorticoid binding were associated with identical changes in GR protein and mRNA levels, that were explained by an increase in GR gene transcription rather than by posttranscriptional mechanisms. Functional inactivation of Smad 2/3 and AP-1 limited the response to TGF-beta 1, indicating a role for these transcription factors. Finally, increases in glucocorticoid binding to GR were responsible for increases in the ability of GR to transactivate minimal promoters containing glucocorticoid-responsive elements (GRE) [MMTV-Luc and (GRE)2 TK-Luc].

CONCLUSION

TGF-beta 1 increases glucocorticoid binding and signaling in inflammatory cells through a Smad 2/3- and AP-1-mediated process. This may represent a new target for intervention to increase glucocorticoid responsiveness.

Expression of glucocorticoid receptor alpha- and beta-isoforms in human cells and tissues

Alternative splicing of the human glucocorticoid receptor (GR) primary transcript generates two protein isoforms: GR-alpha and GR-beta. We investigated the expression of both GR isoforms in healthy human cells and tissues. GR-alpha mRNA abundance (x10(6) cDNA copies/microg total RNA) was as follows: brain (3.83 +/- 0.80) > skeletal muscle > macrophages > lung > kidney > liver > heart > eosinophils > peripheral blood mononuclear cells (PBMCs) > nasal mucosa > neutrophils > colon (0.33 +/- 0.04). GR-beta mRNA was much less expressed than GR-alpha mRNA. Its abundance (x10(3) cDNA copies/microg total RNA) was as follows: eosinophils (1.55 +/- 0.58) > PBMCs > liver > or = skeletal muscle > kidney > macrophages > lung > neutrophils > brain > or = nasal mucosa > heart (0.15 +/- 0.08). GR-beta mRNA was not found in colon. While GR-alpha protein was detected in all cells and tissues, GR-beta was not detected in any specimen. Our results suggest that, in physiological conditions, the default splicing pathway is the one leading to GR-alpha. The alternative splicing event leading to GR-beta is minimally activated.

Refractory asthma

Treating patients with refractory asthma remains an ongoing challenge. Although most patients respond to large doses of systemic corticosteroid, the adverse effects associated with such a treatment limit its general use. Clinicians treating patients with refractory asthma must consider tapering systemic corticosteroid at every opportunity. Recent advances in the understanding of the pathogenesis of refractory asthma and corticosteroid resistance have fueled further study in the mechanisms of these processes and have prompted consideration of new treatment approaches. Unfortunately, most alternative approaches require more rigorous evidence to support their regular use.

Cytokines and hormones with anti-inflammatory effects: new tools for therapeutic intervention

The inflammation that is involved in the development of glomerulonephritis is tightly regulated by the expression of anti-inflammatory factors. These include circulating hormones, such as glucocorticoids, and mediators that are produced by intrinsic cells and infiltrating leucocytes. The present review focuses on these anti-inflammatory factors, summarizing in particular their activities in existing models of glomerulonephritis. In addition, experimental evidence is presented that anti-inflammatory mediators are able to increase glucocorticoid binding or signalling in target cells. These data help to explain the in-vivo efficacy of anti-inflammatory mediators, and offer a promising new avenue for therapeutic intervention.

Expression of the human glucocorticoid receptor alpha and beta isoforms in human respiratory epithelial cells and their regulation by dexamethasone

Two isoforms of the human glucocorticoid receptor (hGR) have been described, hGRalpha and hGRbeta. We analyzed the expression and regulation of both hGR isoforms in human respiratory epithelial cells (BEAS-2B, A549, and primary nasal epithelial cells). In BEAS-2B cells, the expression of hGRalpha messenger RNA (mRNA) was much higher than that of hGRbeta mRNA. Dexamethasone (DEX) (10(-6) M) downregulated hGRalpha mRNA at 6 and 24 h (55 +/- 8 and 58 +/- 5% of control, respectively; P < 0.01), whereas it decreased hGRbeta mRNA only at 6 h (55 +/- 7% of control; P < 0.01). Downregulation of hGRalpha and hGRbeta mRNAs occurred even in the presence of cycloheximide. Actinomycin-D studies revealed that DEX enhanced the stabilization of hGRalpha and hGRbeta messages. hGRalpha but not hGRbeta protein was detected in BEAS-2B, A549, and nasal epithelial cells. After 24 h of incubation, 10(-6) M DEX decreased the expression of hGRalpha protein in BEAS-2B, A549, and nasal epithelial cells (16 +/- 4, 14 +/- 4, and 28 +/- 7% of control, respectively; P < 0.01). These results suggest that in respiratory epithelial cells: (1) hGRalpha is much more expressed than hGRbeta at both the mRNA and protein levels; (2) hGRalpha is downregulated by corticosteroids both in cell lines (BEAS-2B, A549) and in nasal primary cells; and (3) transcriptional, post-transcriptional, and post-translational mechanisms appear to be involved in the regulation of hGR expression by corticosteroids.

Pulse glucocorticoids

High-dose intravenous (i.v.) methylprednisolone has been used therapeutically in a number of medical fields to avoid the complications and side effects of long-term glucocorticoid (GC) therapy and because of the perception that high-dose i.v. methylprednisolone may have "special" therapeutic effects. It is possible that aggressive early therapy with GCs allows for a more rapid taper of GCs and therefore prevents some of the dose-related side effects associated with long-term use. Some of the neurologic and rheumatologic literature related to multiple sclerosis and lupus nephritis suggest that i.v. methylprednisolone has therapeutic effects that are different from those of conventional doses of oral prednisone. There is still considerable debate about this in nondermatologic fields, and extrapolation of the role of pulse i.v. methylprednisolone to dermatologic disease, where trials are lacking, is difficult. Given this subset of possible candidates of this therapy as suggested by anecdotal reports, there is at least a rationale for considering the use of this modality in a subset of patients.

Somatostatin increases glucocorticoid binding and signaling in macrophages by blocking the calpain-specific cleavage of Hsp 90

Somatostatin has direct anti-inflammatory actions and participates in the anti-inflammatory actions of glucocorticoids, but the mechanisms underlying this regulation remain poorly understood. The objective of this study was to evaluate whether somatostatin increases glucocorticoid responsiveness by up-regulating glucocorticoid receptor (GR) expression and signaling. Somatostatin promoted a time- and dose-dependent increase in [(3)H]dexamethasone binding to RAW 264.7 macrophages. Cell exposure to 10 nM somatostatin for 18 h promoted a 2-fold increase in the number of GR sites per cell without significant modification of the affinity. Analysis of GR heterocomplex components demonstrated that somatostatin increased the level of heat shock protein (Hsp) 90, whereas the level of GR remained almost unchanged. The increase in Hsp 90 was associated with a decrease in the cleavage of its carboxyl-terminal domain. Evidence for the involvement of calpain inhibition in this process was obtained by the demonstration that 1) somatostatin induced a dose-dependent decrease in calpain activity and 2) calpain inhibitors, calpain inhibitor I and calpeptin, both abolished the cleavage of Hsp 90 and induced a dose-dependent increase in [(3)H]dexamethasone binding. Increases in glucocorticoid binding after somatostatin treatment were associated with similar increases in the ability of GR to transactivate a minimal promoter containing two glucocorticoid response elements (GRE) and to interfere with the activation of nuclear factor-kappaB (NF-kappaB). Thus, the present findings indicate that somatostatin increases glucocorticoid binding and signaling by limiting the calpain-specific cleavage of GR-associated Hsp 90. This mechanism may represent a novel target for intervention to increase glucocorticoid responsiveness.

In vivo modulation of glucocorticoid receptor mRNA by inhaled fluticasone propionate in bronchial mucosa and blood lymphocytes in subjects with mild asthma

BACKGROUND

In vivo regulation of the glucocorticoid receptor (GR) by glucocorticoids provides a means of modulating sensitivity of targeted cells.

OBJECTIVE

We sought to determine the in vivo modulation of GR mRNA expression by fluticasone propionate (FP) in subjects with mild asthma.

METHODS

Ten atopic asthmatic subjects were treated with FP 250 microg twice daily for 4 weeks. Before and after treatment, the patients underwent fiberoptic bronchoscopy with endobronchial biopsy and sampling of venous blood for measurements of GR mRNA levels. A solution hybridization assay was used for quantitative analysis of GR mRNA. In addition, a 24-hour urinary cortisol excretion and an adrenocorticotropic hormone test before and after treatment with FP were performed.

RESULTS

A high interindividual variation in GR mRNA expression was seen. However, we detected a significant reduction of the GR mRNA levels in the endobronchial biopsy specimens after FP treatment (36.6 +/- 23.1 and 25.0 +/- 10.9 amol GR mRNA/microg RNA, respectively; P <.01). In the peripheral blood lymphocytes an even more striking downregulation of the GR by its cognate ligand was documented (30.3 +/- 26.5 and 8.8 +/- 5 amol GR mRNA/microg RNA, respectively; P <.001), possibly reflecting differences in glucocorticoid sensitivity between tissues. A small but significant reduction of the 24-hour urinary cortisol excretion was observed (233 +/- 109 and 157 +/- 66 nmol/L, respectively; P <.01), whereas the feedback regulation of glucocorticoid synthesis by means of the hypothalamic-pituitary-adrenal axis as assessed by the adrenocorticotropic hormone test remained normal after treatment with FP.

CONCLUSION

The results in this study confirm the potency of the inhaled corticosteroid FP and provide evidence for a considerable tissue-specific interindividual variation in the expression of the GR.

Chronic interstitial lung disease in children: response to high-dose intravenous methylprednisolone pulses

The prognosis for children with chronic interstitial lung disease is poor and the mortality rate is high, especially in infants. This explains the many therapeutical protocols which have been proposed and investigated by several authors. In the present work, we evaluated the response of three infants with idiopathic pulmonary fibrosis to high-dose intravenous prednisolone pulses. The patients were referred to the department at the age of 4, 17, and 3 months, respectively. The diagnosis was confirmed by open lung biopsy and intravenous pulse methyl prednisolone therapy was started with the following protocol: 300 mg/m2 methylprednisolone daily for 3 days, repeated every 4 to 6 weeks. Because of the extreme severity of the respiratory distress at the time of diagnosis, the intravenous pulse treatments were initially complemented by oral prednisone. Clinical improvement was noticed within 6 months with progressive correction of hypoxemia. After follow-up for 3.5 to 4 years, with a total number of pulses of 37, 26, and 32, respectively, the children are symptom-free and do not require oxygen supplementation. During this period, no side effects and no adrenal insufficiency could be documented. Based on current knowledge of steroid action, it can be speculated that the response to intermittent high-dose intravenous methylprednisolone may explain the ability of this mode of hormone administration to maintain an adequate level of glucocorticoid receptor expression. More information and trials through multicenter collaborations are needed to assess therapeutical protocols of repeated high-dose intravenous steroid treatment.