Olivier Kassel
Education
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Sep 1986–
Dec 1992Université Louis Pasteur, Strasbourg I
Pharm DFrance · Strasbourg
Other
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LanguagesFrench :mother tongue
English : read, written, spoken
German : basic knowledge
Publications
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6.09Impact points
CD24 interacts with and promotes the activity of c-src within lipid rafts in breast cancer cells, thereby increasing integrin-dependent adhesion.
Cellular and molecular life sciences : CMLS. 06/2011; 69(3):435-48.
Expression of the glycosylphosphatidylinositol-anchored membrane protein CD24 correlates with a poor prognosis for many human cancers, and in experimental tumors can promote metastasis. However, the mechanism by which CD24 contributes to tumor progression remains unclear. Here we report that in MTLy... [more] Expression of the glycosylphosphatidylinositol-anchored membrane protein CD24 correlates with a poor prognosis for many human cancers, and in experimental tumors can promote metastasis. However, the mechanism by which CD24 contributes to tumor progression remains unclear. Here we report that in MTLy breast cancer cells CD24 interacts with and augments the kinase activity of c-src, a protein strongly implicated in promoting invasion and metastasis. This occurs within and is dependent upon intact lipid rafts. CD24-augmented c-src kinase activity increased formation of focal adhesion complexes, accelerated phosphorylation of FAK and paxillin and consequently enhanced integrin-mediated adhesion. Loss and gain of function approaches showed that c-src activity is necessary and sufficient to mediate the effects of CD24 on integrin-dependent adhesion and cell spreading, as well as on invasion. Together these results indicate that c-src is a CD24-activated mediator that promotes integrin-mediated adhesion and invasion, and suggest a mechanism by which CD24 might contribute to tumor progression through stimulating the activity of c-src or another member of the Src family.
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3.50Impact points
The nuclear isoform of the LIM domain protein Trip6 integrates activating and repressing signals at the promoter-bound glucocorticoid receptor.
Molecular and cellular endocrinology. 02/2010; 320(1-2):58-66.
Trip6 belongs to a family of cytosolic LIM domain proteins involved in cell adhesion and migration. Recent findings show that these proteins also regulate transcription. We have previously reported that nTrip6, a nuclear isoform of Trip6, acts as a co-activator for AP-1 and NF-kappaB transcription f... [more] Trip6 belongs to a family of cytosolic LIM domain proteins involved in cell adhesion and migration. Recent findings show that these proteins also regulate transcription. We have previously reported that nTrip6, a nuclear isoform of Trip6, acts as a co-activator for AP-1 and NF-kappaB transcription factors. Here we report that nTrip6 is an essential regulator of glucocorticoid receptor (GR) transcriptional activity. nTrip6 is recruited to GR-bound promoters through an interaction with GR, and increases GR-mediated transcription. nTrip6 is also essential for the transrepression of GR by NF-kappaB and AP-1. The interaction of nTrip6 with NF-kappaB and AP-1 at a GR-bound promoter is required for the repression. Thus, nTrip6 serves as the molecular mediator of the crosstalk between nuclear receptors and other transcription factors in that it assembles these factors at promoters. Our results reveal an essential role for LIM domain proteins in the integration of positive and negative signals at target promoters.
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An all polymer optofluidic chip with integrated waveguides for biophotonics
IEEE/LEOS Summer Topical Meetings, 2008 Digest of the; 08/2008
Miniaturized optofluidic systems with integrated waveguides and microfluidic channels were built as monolithic polymer devices. Their potential for biosensor applications was demonstrated by two examples: (1) Change of the light attenuation as function of the analytepsilas refractive index, (2) Chan... [more] Miniaturized optofluidic systems with integrated waveguides and microfluidic channels were built as monolithic polymer devices. Their potential for biosensor applications was demonstrated by two examples: (1) Change of the light attenuation as function of the analytepsilas refractive index, (2) Channels functionalized by Dip-Pen Nanolithography allowed the selective capture of fluorescent markers, which were detected after local excitation through the waveguides.
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5.26Impact points
Restriction to Fos family members of Trip6-dependent co-activation and GR-dependent trans-repression of AP-1.
Molecular endocrinology (Baltimore, Md.). 07/2008;
The term AP-1 describes homodimeric and heterodimeric transcription factors composed of members of the Jun, Fos and CREB/ATF families of proteins. Distinct AP-1 dimers, like for instance the prototypical c-Jun:c-Fos and c-Jun:ATF2 dimers, are differentially regulated by signaling pathways, and bind ... [more] The term AP-1 describes homodimeric and heterodimeric transcription factors composed of members of the Jun, Fos and CREB/ATF families of proteins. Distinct AP-1 dimers, like for instance the prototypical c-Jun:c-Fos and c-Jun:ATF2 dimers, are differentially regulated by signaling pathways, and bind related yet distinct response elements in the regulatory regions of AP-1 target genes. Little is known about the dimer specific regulation of AP-1 activity at the promoter of its target genes. We have previously shown that nTrip6, the nuclear isoform of the LIM domain protein Trip6, acts as an AP-1 co-activator. Moreover, nTrip6 is an essential component of glucocorticoid receptor (GR)-mediated trans-repression of AP-1, in that it mediates the tethering of GR to the promoter-bound AP-1. We now discovered a striking specificity of nTrip6 actions determined by the binding preference of its LIM domains. We show that nTrip6 interacts only with Fos family members. Consequently, nTrip6 is a selective co-activator for AP-1 dimers containing Fos. nTrip6 also assembles activated GR to c-Jun:c-Fos-driven promoters. Neither nTrip6 nor GR are recruited to a promoter occupied by c-Jun:ATF2. Thus, only Fos containing dimers are trans-repressed by GR. Thus, the dimer composition of AP-1 determines the mechanism of both the positive and negative regulation of AP-1 transcriptional activity. Interestingly, on a second level of action, GR represses the increase in transcriptional activity of c-Jun:ATF2 induced by JNK-dependent phosphorylation. This repression depends on GR-mediated induction of MAP kinase phosphatase 1 (MKP-1) expression, which results in JNK inactivation.
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3.50Impact points
Crosstalk between the glucocorticoid receptor and other transcription factors: molecular aspects.
Molecular and cellular endocrinology. 10/2007; 275(1-2):13-29.
Glucocorticoids (GCs) regulate cell fate by altering gene expression via the glucocorticoid receptor (GR). Ligand-bound GR can activate the transcription of genes carrying the specific GR binding sequence, the glucocorticoid response element (GRE). In addition, GR can modulate, positively or negativ... [more] Glucocorticoids (GCs) regulate cell fate by altering gene expression via the glucocorticoid receptor (GR). Ligand-bound GR can activate the transcription of genes carrying the specific GR binding sequence, the glucocorticoid response element (GRE). In addition, GR can modulate, positively or negatively, directly or indirectly, the activity of other transcription factors (TFs), a process referred to as "crosstalk". In the indirect crosstalk, GR interferes with transduction pathways upstream of other TFs. In the direct crosstalk, GR and other TFs modulate each other's activity when bound to the promoters of their target genes. The multiplicity of molecular actions exerted by TFs, particularly the GR, is not only fascinating in terms of molecular structure, it also implies that the TFs participate in a wide range of regulatory processes, broader than anticipated. This review focuses on the molecular mechanisms involved in the crosstalk, on both current ideas and unresolved questions, and discusses the possible significance of the crosstalk for the physiologic and therapeutic actions of GCs.
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12.08Impact points
A nuclear isoform of the focal adhesion LIM-domain protein Trip6 integrates activating and repressing signals at AP-1- and NF-kappaB-regulated promoters.
Genes & development. 11/2004; 18(20):2518-28.
Glucocorticoid receptor (GR)-mediated transrepression of the transcription factors AP-1 and NF-kappaB, responsible for most of the anti-inflammatory effects of glucocorticoids, is initiated by the tethering of GR to the promoters of target genes. We report that this tethering is mediated by a nuclea... [more] Glucocorticoid receptor (GR)-mediated transrepression of the transcription factors AP-1 and NF-kappaB, responsible for most of the anti-inflammatory effects of glucocorticoids, is initiated by the tethering of GR to the promoters of target genes. We report that this tethering is mediated by a nuclear isoform of the focal adhesion LIM domain protein Trip6. Trip6 functions as a coactivator for both AP-1 and NF-kappaB. As shown by chromatin immunoprecipitation, Trip6 is recruited to the promoters of target genes together with AP-1 or NF-kappaB. In the presence of glucocorticoids, GR joins the Trip6 complex. Reducing the level of Trip6 by RNA interference or abolishing its interaction with GR by dominant-negative mutation eliminates transrepression. We propose that GR tethering to the target promoter through Trip6 forms the basis of transrepression, and that Trip6 exerts its nuclear functions by acting as a molecular platform, enabling target promoters to integrate activating or repressing signals.
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5.20Impact points
Paradoxical early glucocorticoid induction of stem cell factor (SCF) expression in inflammatory conditions.
British journal of pharmacology. 02/2004; 141(1):75-84.
1. Stem cell factor (SCF) is a major growth factor for mast cells, promoting their differentiation and chemotaxis. Its expression is regulated by glucocorticoids in inflammatory conditions, showing an early increased protein expression, before the expected anti-inflammatory decrease (Da Silva et al.... [more] 1. Stem cell factor (SCF) is a major growth factor for mast cells, promoting their differentiation and chemotaxis. Its expression is regulated by glucocorticoids in inflammatory conditions, showing an early increased protein expression, before the expected anti-inflammatory decrease (Da Silva et al., Br. J. Pharmacol. 2002:135,1634). 2. We here evaluated the early kinetic of SCF expression regulated by interleukin (IL)-1beta, budesonide and the combination of both in human lung fibroblasts in culture. 3. Budesonide potentiated the IL-1beta-enhanced expression of SCF mRNA (+103%) and protein (+98%) very shortly after treatment (at 30 min and 1 h, respectively). A gentle downregulation followed. This potentiating effect of budesonide was related to increased SCF mRNA stability and SCF gene transcription. 4. Deletion of a kappaB-like site that we identified in the first intron of the SCF gene, in a luciferase reporter system, abolished the potentiation by budesonide, as well as the effect of IL-1beta alone, as compared to the wild-type construction activity. 5. All budesonide-induced effects were glucocorticoid-receptor dependent, since they were reproduced by dexamethasone and blocked by RU486. 6. IL-1beta+budesonide did not affect the relative expression of the soluble and membrane-bound forms of SCF. 7. In conclusion, our results clearly show that glucocorticoids act very early to adversely increase the expression of SCF mRNA and protein in the inflammatory conditions created by IL-1beta, and that this effect involves increased mRNA stability and increased gene expression through activation of the NF-kappaB-like responsive element.
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6.40Impact points
Transcription of stem cell factor (SCF) is potentiated by glucocorticoids and interleukin-1beta through concerted regulation of a GRE-like and an NF-kappaB response element.
The FASEB journal : official publication of the Federation of American Societies for Experimental Biology. 01/2004; 17(15):2334-6.
Expression of stem cell factor SCF, a major mast cell growth factor, is potentiated shortly after co-treatment with interleukin (IL)-1beta and glucocorticoids. SCF promoter contains a GRE-like sequence and a putative kappaB site. We assessed the mechanisms of the regulation of SCF transcription in h... [more] Expression of stem cell factor SCF, a major mast cell growth factor, is potentiated shortly after co-treatment with interleukin (IL)-1beta and glucocorticoids. SCF promoter contains a GRE-like sequence and a putative kappaB site. We assessed the mechanisms of the regulation of SCF transcription in human lung fibroblasts in culture. Chromatin immunoprecipitation showed that co-treatment with IL-1beta and the glucocorticoid budesonide increased the SCF promoter occupancy by NF-kappaB and GR, as compared with IL-1beta and budesonide alone. In reporter gene assays, IL-1beta time-dependently increased the promoter activity, which was abolished by either pre-treatment with the MAP kinase inhibitors PD98059 (MEK) and SB203580 (p38), pre-treatment with the NF-kappaB inhibitor PDTC, or deletion of the kappaB site. Budesonide time-dependently decreased the promoter activity, an effect requiring the GRE-like element. Co-treatment with IL-1beta and budesonide potentiated the promoter activity at 30 min, an effect blocked by PD98059 and SB203580, PDTC, or deletion of the kappaB or GRE-like element. In conclusion, the GRE-like sequence mediating the repression of SCF expression, thus acting as a negative-responsive element, is turned into a positive element in an NF-kappaB site-dependent manner, indicating a concerted action of these two regulatory elements in the potentiation of SCF gene expression.
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5.53Impact points
Nerve growth factor levels and localisation in human asthmatic bronchi.
The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology. 12/2002; 20(5):1110-6.
Nerve growth factor (NGF) has recently been suggested to be an important mediator of inflammation. In support of this, serum levels of NGF have been shown to be enhanced in asthmatics. However, it has not yet been shown whether the levels of NGF are also altered locally in asthmatic airways, when co... [more] Nerve growth factor (NGF) has recently been suggested to be an important mediator of inflammation. In support of this, serum levels of NGF have been shown to be enhanced in asthmatics. However, it has not yet been shown whether the levels of NGF are also altered locally in asthmatic airways, when compared with healthy subjects, and the localisation of potential sources of NGF in the human bronchus have not yet been described. The aim of the present study was to assess NGF levels in bronchoalveolar lavage fluid (BALF) from asthmatics and to compare them to those of control subjects. Furthermore, the authors wanted to localise potential sources of NGF in bronchial tissue, and to number NGF-immunopositive infiltrating cells in the bronchial submucosa. BALF and bronchial biopsies were obtained from seven control subjects and seven asthmatic patients by fibreoptic bronchoscopy. NGF protein levels were quantified by enzyme-linked immunosorbent assay in BALF. NGF localisation was examined by immunohistochemistry on bronchial biopsy sections. The asthmatics exhibited significantly enhanced NGF levels in BALF. Intense NGF-immunoreactivity was observed in bronchial epithelium, smooth muscle cells and infiltrating inflammatory cells in the submucosa, and to a lesser extent in the connective tissue. The asthmatics exhibited a higher number of NGF-immunoreactive infiltrating cells in the bronchial submucosa than control subjects. This study provides evidence that nerve growth factor is locally produced in the airways, and shows that this production is enhanced in asthmatics. These findings suggest that nerve growth factor is produced by both structural cells and infiltrating inflammatory cells in human bronchus in vivo, and the authors suggest that the increase in nerve growth factor protein in bronchoalveolar lavage fluid observed in asthmatic patients may originate both from structural cells, producing increased nerve growth factor levels in inflammatory conditons, and from the increase in nerve growth factor-immunopositive cells determined in the bronchial submucosa.
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5.20Impact points
Inhibition by glucocorticoids of the interleukin-1beta-enhanced expression of the mast cell growth factor SCF.
British journal of pharmacology. 04/2002; 135(7):1634-40.
1. Stem cell factor (SCF) is a major mast cell growth factor that promotes differentiation and chemotaxis of mast cells and inhibits their apoptosis. 2. We evaluated the effect of interleukin (IL)-1beta, a major pro-inflammatory cytokine, on the constitutive expression of SCF and studied the effects... [more] 1. Stem cell factor (SCF) is a major mast cell growth factor that promotes differentiation and chemotaxis of mast cells and inhibits their apoptosis. 2. We evaluated the effect of interleukin (IL)-1beta, a major pro-inflammatory cytokine, on the constitutive expression of SCF and studied the effects of two glucocorticoids, budesonide and dexamethasone, on the IL-1beta-enhanced SCF expression. 3. Human lung fibroblasts in culture were serum-starved for 48 h and treated with IL-1beta, budesonide and/or RU486. SCF cDNA was quantified after total RNA reverse transcription by on-line fluorescent polymerase chain reaction. SCF protein was quantified by ELISA. 4. IL-1beta induced an increase in SCF mRNA (+91% at 2.5 h) and protein production (+32%) by human lung fibroblasts in culture (P<0.001). 5. Budesonide inhibited IL-1beta-induced SCF mRNA expression (-68%) at 2.5 h and even more so at 10 h (-192%) (P<0.001). The expression of SCF protein also decreased by 3.5-fold at 10 h. Results were similar with dexamethasone. The glucocorticoid antagonist RU486 cancelled the effects induced by the glucocorticoids. 6. Increased SCF mRNA levels were associated with increased stability of this mRNA as measured after treatment with actinomycin D (1.9-fold at 2.5 h). Budesonide decreased this IL-1beta-enhanced stability by about 1.5-fold (P<0.001). 7. We conclude that in 'inflammatory' conditions, mimicked in vitro by IL-1beta, glucocorticoid treatment inhibits expression of the mast cell growth factor SCF. The reduced number and activation of mast cells observed in the bronchi of asthmatic patients treated by glucocorticoids may be due in part to this effect.
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Mast cells as targets for glucocorticoids in the treatment of allergic disorders.
Ernst Schering Research Foundation workshop. 02/2002;
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8.99Impact points
Glucocorticoids inhibit MAP kinase via increased expression and decreased degradation of MKP-1.
The EMBO journal. 01/2002; 20(24):7108-16.
Glucocorticoids inhibit the proinflammatory activities of transcription factors such as AP-1 and NF-kappa B as well as that of diverse cellular signaling molecules. One of these signaling molecules is the extracellular signal-regulated kinase (Erk-1/2) that controls the release of allergic mediators... [more] Glucocorticoids inhibit the proinflammatory activities of transcription factors such as AP-1 and NF-kappa B as well as that of diverse cellular signaling molecules. One of these signaling molecules is the extracellular signal-regulated kinase (Erk-1/2) that controls the release of allergic mediators and the induction of proinflammatory cytokine gene expression in mast cells. The mechanism of inhibition of Erk-1/2 activity by glucocorticoids is unknown. Here we report a novel dual action of glucocorticoids for this inhibition. Glucocorticoids increase the expression of the MAP kinase phosphatase-1 (MKP-1) gene at the promoter level, and attenuate proteasomal degradation of MKP-1, which we report to be triggered by activation of mast cells. Both induction of MKP-1 expression and inhibition of its degradation are necessary for glucocorticoid-mediated inhibition of Erk-1/2 activation. In NIH-3T3 fibroblasts, although glucocorticoids up-regulate the MKP-1 level, they do not attenuate the proteasomal degradation of this protein and consequently they are unable to inhibit Erk-1/2 activity. These results identify MKP-1 as essential for glucocorticoid-mediated control of Erk-1/2 activation and unravel a novel regulatory mechanism for this anti-inflammatory drug.
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4.08Impact points
Local increase in the number of mast cells and expression of nerve growth factor in the bronchus of asthmatic patients after repeated inhalation of allergen at low-dose.
Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology. 10/2001; 31(9):1432-40.
BACKGROUND: Repeated inhalation of allergen at low-dose induces an increase in bronchial hyper-responsiveness, without any associated symptom. The concomitant events in the bronchus have not been described. OBJECTIVE: We have studied the dynamic number of mast cells in the airways of patients with m... [more] BACKGROUND: Repeated inhalation of allergen at low-dose induces an increase in bronchial hyper-responsiveness, without any associated symptom. The concomitant events in the bronchus have not been described. OBJECTIVE: We have studied the dynamic number of mast cells in the airways of patients with mild asthma before and after repeated inhalation of allergen at low-dose and the expression of nerve growth factor (NGF), which is reported to promote growth and survival of mast cells. METHODS: Twelve patients with mild asthma to cat allergen were enrolled at random in a blind placebo-controlled study, and submitted to repeated low-dose allergen exposure (1/5 of the provocative dose). Mast cells were immunolocalized using an antibody against mast cell tryptase. NGF and its high affinity receptor, TrkA, were immunolocalized using anti-NGF and anti-TrkA antibodies, respectively. NGF mRNA was quantified by competitive polymerase chain reaction (PCR) after reverse transcription of total RNA extracted from bronchial biopsy. NGF protein levels were measured by ELISA in bronchoalveolar lavage (BAL) fluid. RESULTS: Bronchial mast cell number was increased significantly after allergen exposure as compared with before. NGF expression in the bronchus was immunolocalized mainly to epithelial cells, but also to fibroblasts, blood vessels, and a few infiltrated cells. NGF mRNA levels in bronchial biopsies were increased significantly after allergen exposure. The high affinity receptor for NGF, TrkA, was immunolocalized to the infiltrated mast cell membrane. CONCLUSION: Our study shows that the increase in the number of mast cells and in the expression of NGF induced by allergen exposure in the bronchus of asthmatic patients is occurring before the onset of symptoms. In addition, our finding of the presence of the TrkA receptor on the membrane of the infiltrated mast cell in situ brings evidence of the mast cell as a target cell for the growth factor activity of NGF in the airways in asthma.
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2.02Impact points
The stem cell factor, its properties and potential role in the airways.
Pulmonary pharmacology & therapeutics. 02/2001; 14(4):277-88.
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2.54Impact points
Repeated inhalation of low doses of cat allergen that do not induce clinical symptoms increases bronchial hyperresponsiveness and eosinophil cationic protein levels.
International archives of allergy and immunology. 10/1999; 120(2):158-65.
The aim of this study was to investigate whether repeated exposure to subclinical doses of cat allergens, not inducing asthma symptoms, could affect eosinophil cationic protein (ECP) levels in bronchoalveolar lavage (BAL) or in peripheral blood, without the appearance of clinical symptoms. Twelve pa... [more] The aim of this study was to investigate whether repeated exposure to subclinical doses of cat allergens, not inducing asthma symptoms, could affect eosinophil cationic protein (ECP) levels in bronchoalveolar lavage (BAL) or in peripheral blood, without the appearance of clinical symptoms. Twelve patients with mild asthma, all sensitized to cats and not exposed to cat allergen at home, underwent a series of inhalations of cat allergen or placebo for 8 days over 2 weeks. A methacholine challenge was performed before and after the allergen and saline exposures, and BAL and blood were sampled for ECP measurements and eosinophil counts. No patients experienced asthma symptoms. However, PD20 methacholine (geometric mean) decreased significantly from 263 microg before to 126 microg after inhalation of allergen. Inhalation of saline did not induce any significant change in PD20. The change in log PD20 before and after cat allergen exposure was statistically different from the change in log PD20 before and after saline. Median ECP levels in BAL and serum increased significantly after allergen exposure, from 0.8 to 3.1 microg/l (p<0.02) and from 15.9 to 31.4 microg/l (p<0.05), respectively. No change was observed after saline inhalations. The change in BAL and serum ECP levels was statistically significant compared to that in the control group. The number of eosinophils did not change, however, nor did IL-5 and RANTES levels in BAL and serum. In conclusion, our results show that (1) exposure of asthma patients to repeated low doses of allergen, which did not provoke any clinical symptoms, is capable of inducing a local eosinophil activation associated with an increase in nonspecific bronchial hyperresponsiveness and (2) the increase in serum ECP levels due to eosinophil activation precedes the occurrence of asthma symptoms and may thus be a marker of allergen exposure in allergic asthma.
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5.53Impact points
Human bronchial smooth muscle cells in culture produce stem cell factor.
The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology. 06/1999; 13(5):951-4.
A mast cell infiltration of the bronchial smooth muscle layer has been reported in patients sensitized to common allergens. Stem cell factor (SCF) is a chemotactic and survival factor for mast cells. SCF is expressed as a soluble (sSCF) and a membrane-bound (mSCF) form, after alternative splicing of... [more] A mast cell infiltration of the bronchial smooth muscle layer has been reported in patients sensitized to common allergens. Stem cell factor (SCF) is a chemotactic and survival factor for mast cells. SCF is expressed as a soluble (sSCF) and a membrane-bound (mSCF) form, after alternative splicing of the exon encoding the proteolytic cleavage site. SCF expression by human bronchial smooth muscle cells in culture was evaluated, comparing it to that of human lung fibroblasts in culture. sSCF released in the culture supernatant was assessed by an enzyme-linked immunosorbent assay. Total SCF messenger ribonucleic acid (mRNA) was measured by competitive polymerase chain reaction (PCR) after reverse transcription. Expression of the two forms of SCF mRNA was assessed by PCR, with primers spanning the alternatively spliced exon. Smooth muscle cells produced sSCF (21.9+/-2.6 pg x mL(-1)), although at lower levels than fibroblasts (35.9+/-3.5 pg x mL(-1)); the expression of total SCF mRNA was also at lower levels than in fibroblasts (8.6+/-0.2 and 19.0+/-2.0 amol x fmol glyceraldehyde 3-phosphate dehydrogenase complementary deoxyribonucleic acid(-1), respectively). However, smooth muscle cells expressed proportionally more (1.7-fold) mSCF mRNA than did fibroblasts. In conclusion, this study shows that bronchial smooth muscle cells express stem cell factor, with a relatively high expression of membrane-bound stem cell factor. This might be related to the presence of mast cells within the bronchial smooth muscle layer, i.e. at the site of bronchoconstriction, with possible implications in the pathophysiology of asthma.
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2.63Impact points
Glucocorticoids increase bradykinin B2 receptor gene transcription in cultured guinea-pig tracheal smooth muscle cells.
Naunyn-Schmiedeberg's archives of pharmacology. 04/1999; 359(3):153-9.
We investigated the effect of the glucocorticoid methylprednisolone on the modulation of the expression of the bradykinin B2 receptors in cultured, guinea-pig, tracheal, smooth muscle cells. These receptors are implicated in the pathogenesis of human asthma. Untreated cells expressed a single popula... [more] We investigated the effect of the glucocorticoid methylprednisolone on the modulation of the expression of the bradykinin B2 receptors in cultured, guinea-pig, tracheal, smooth muscle cells. These receptors are implicated in the pathogenesis of human asthma. Untreated cells expressed a single population of binding sites for [3H]bradykinin with a dissociation constant, Kd, of 87.7+/-12.0 pM and a maximum binding site density, Bmax, of 245.4+/-71 fmol/mg protein. Treatment of the cultured guinea-pig tracheal smooth muscle cells with methylprednisolone 10(-5) M for 6 h increased the number of bradykinin receptors; this response reached a maximum of 78% and returned to the basal value after 12 h. Bradykinin (10(-12) M) elicited a six-fold higher calcium level in treated cells than in control cells. To investigate bradykinin B2 receptor mRNA expression in guinea-pig cells, we used the reverse transcription polymerase chain reaction (RT-PCR) technique to synthesize a specific bradykinin B2 cDNA probe of 296 bp corresponding to nucleotides 456-751 of the human sequence. This guinea-pig cDNA had 88%, 86% and 83% homology with the corresponding human, mouse and rat sequences, respectively, but no homology with any other known sequences. Following methylprednisolone treatment, Northern blot hybridization indicated that mRNA increased fourfold after 3 h compared with control cells, and returned to basal level within 7 h. The rate of gene transcription, assessed by nuclear run-on assays, increased fourfold after 3 h treatment with 10(-5) M methylprednisolone. These results indicate that glucocorticoids induce early up-regulation of bradykinin B2 receptors in cultured guinea-pig tracheal smooth muscle cells by increasing the rate of transcription of the bradykinin B2 receptor gene.
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4.53Impact points
Up- and down-regulation by glucocorticoids of the constitutive expression of the mast cell growth factor stem cell factor by human lung fibroblasts in culture.
Molecular pharmacology. 01/1999; 54(6):1073-9.
Stem cell factor (SCF) is a major mast cell growth factor that promotes differentiation and chemotaxis of mast cells and inhibits their apoptosis. SCF therefore may be involved in diseases associated with an increased number of tissue mast cells such as asthma, for which the major treatment is gluco... [more] Stem cell factor (SCF) is a major mast cell growth factor that promotes differentiation and chemotaxis of mast cells and inhibits their apoptosis. SCF therefore may be involved in diseases associated with an increased number of tissue mast cells such as asthma, for which the major treatment is glucocorticoids. In this study, we evaluated the effect of the glucocorticoid budesonide on the constitutive expression of SCF by human lung fibroblasts in primary culture. Budesonide (0.1 microM) induced a time-dependent biphasic effect on SCF mRNA and protein production. A short treatment (2.5-10 hr) induced an inhibition of SCF protein accumulation (-58% at 2.5 hr) and mRNA expression (-69% at 2.5 hr), associated with an accelerated decay of SCF mRNA and with a decrease in SCF gene transcription observed by nuclear run-on assay. Longer treatment (24-72 hr) led to increases in SCF protein accumulation (+64% at 48 hr) and mRNA expression (+125% at 24 hr) as a consequence of transcriptional activation. Similar effects of a decrease followed by an increase in SCF production were observed using another glucocorticoid, dexamethasone. Overall, our results show that glucocorticoids potently regulate SCF expression in human lung fibroblasts, successively decreasing and increasing SCF mRNA levels according to treatment duration. Such time-dependent modulation of SCF levels may explain some current discrepant findings about the effects of glucocorticoids on SCF production and may have functional consequences during glucocorticoid treatment, such as asthma therapy.
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0.10Impact points
[New hypotheses in asthma: the mastocytes]
Revue de pneumologie clinique. 02/1996; 52(2):59-63.
Increasing progress has been made in the understanding of the biology of mast cells. The precursors of mast cells leave the bone marrow in a non-differentiated form as CD34+ cells. The presence of mast cells growth and differentiation factors controls in tissues maturation of different mast cells ph... [more] Increasing progress has been made in the understanding of the biology of mast cells. The precursors of mast cells leave the bone marrow in a non-differentiated form as CD34+ cells. The presence of mast cells growth and differentiation factors controls in tissues maturation of different mast cells phenotypes. The main factors are the mast cell growth factor SCF (stem cell factor), NGF (Nerve Growth Factor), and IL-3 (Interleukin-3). The potential role of each of these factors in the airways is discussed. An altered production of these growth factors in the airways of asthmatic patients might be the cause of the presence of an increased number of mast cells and of phenotypic modifications in the bronchi of these patients.
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5.65Impact points
IgE-dependent expression of mRNA for IL-4 and IL-5 in human lung mast cells.
Journal of immunology (Baltimore, Md. : 1950). 09/1995; 155(4):1796-808.
By using the reverse transcriptase (RT)-PCR and in situ hybridization we have studied the expression of mRNA for IL-5 and IL-4 in human lung mast cells induced by cross-linkage of high affinity Fc epsilon Rs. Lung mast cells were purified using affinity magnetic selection with mAb YB5.B8 against c-k... [more] By using the reverse transcriptase (RT)-PCR and in situ hybridization we have studied the expression of mRNA for IL-5 and IL-4 in human lung mast cells induced by cross-linkage of high affinity Fc epsilon Rs. Lung mast cells were purified using affinity magnetic selection with mAb YB5.B8 against c-kit to achieve a final mast cell purity > 93%. Purified mast cells were precultured with stem cell factor (SCF) (10 ng/ml) and myeloma IgE (3 micrograms/ml) for 16 h before challenge with anti-IgE (1 or 10 micrograms/ml). IgE-dependent activation of lung mast cells caused expression of IL-5 mRNA, which was evident by 2 h and persisted for up to 48-72 h in all of 12 experiments, whereas IL-4 mRNA expression was of a shorter duration and was demonstrable in 6 of 13 experiments. We confirmed that mast cells, and not T cells, were the source of these cytokine messages by using reverse transcriptase-PCR in cell preparations containing known numbers of mast cells and T cells, in situ hybridization in enriched mast cell preparations, and double in situ hybridization-immunocytochemical staining. IL-5 mRNA expression did not require the pretreatment of cells with SCF, whereas expression of IL-4 mRNA seemed to require both anti-IgE and SCF. The strength of IL-5 mRNA signal was related to anti-IgE concentration. Immunoreactive IL-5 was detectable 8 h after anti-IgE challenge, and 10(6) mast cells generated a mean of 731 +/- 400 pg of IL-5 into the supernatant during 48-h culture, but no IL-4 product was detectable. These findings demonstrate the capacity of human lung mast cells to transcribe IL-4 and IL-5 after IgE-dependent activation and to synthesize and release immunoreactive IL-5.
Following (9)
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Steffen Scholpp
Karlsruhe Institute of Technology -
Martin Knapp
Karlsruhe Institute of Technology -
Mahaboob Khan
University of Madras -
Srikanth Aluru
Institut national de la santé et de la recherche médicale -
Urban Liebel
Karlsruhe Institute of Technology
