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S Bailly

Publications and source records attributed to S Bailly.

At least 19 recordsLinked to original sources
PubMed2000

Transcriptional regulation of the gene encoding the StAR protein in the human adrenocortical cell line, H295R by cAMP and TGFbeta1.

In the present work, we have analyzed the transcriptional regulation of StAR expression in the human adrenocortical cell line H295R. We observed that StAR mRNA levels rapidly increased in response to forskolin, starting after 2 h of treatment and reaching a maximum by 12 h. Deletion analysis of the human StAR promoter demonstrated that the first 150 bp upstream of the transcription start were sufficient for both basal and cAMP-induced expression of a reporter gene. We demonstrate that out of the three binding sequences for the steroidogenic factor 1 (SF-1) only the central one (-105 to -96) is implicated in both basal and cAMP-induced StAR expression. In addition, another important regulatory element for both basal and cAMP-induced StAR expression is present between -62 and -24 upstream of the transcription start. We also show that TGF1beta1 inhibits StAR expression at the transcriptional level. We found that the TGFbeta-inhibitory element lies between -150 and -85 upstream of the transcription start and that the SF-1 binding sites are not implicated in TGFbeta1 regulation.

Adrenal Cortex↗
PubMed2000

[Molecular bases of angiogenesis].

Angiogenesis is a multistep process that drives the formation of new blood capillaries from the pre-existing vasculature. It is usual to distinguish two phases in this process: a morphogenic phase that requires endothelial cell proliferation and migration followed by a maturation phase characterized by the reconstitution of extracellular matrix and the recruitment of pericytes around the newly formed microvessel. Angiogenesis is actively involved in embryonic organogenesis as well as in cancer tumor growth. Although the properties of neovessels formed under these two situations are different, the molecules and the mechanisms implicated are common. VEGF and its receptors flk-1 and flt-1 are the main actors of the morphogenic phase whereas PDGF-BB and its receptor PDGF-R beta, TGF beta 1 and its receptors ALK-5 and ALK-1, angiopoietin-1 and its receptor tie-2 are implied in the vascular maturation phase.

Animals↗
PubMed1998

Smad3 is involved in the intracellular signaling pathways that mediate the inhibitory effects of transforming growth factor-beta on StAR expression.

Transforming growth factor betas (TGFbetas) constitute a family of dimeric proteins that regulate growth and differentiation of many cell types. TGFbeta1 is also a potent autocrine regulator of adrenocortical steroidogenesis. We have recently shown that in primary cultures of bovine fasciculo-reticularis cells, the main target of TGFbeta is the steroidogenic acute relay protein (StAR), a key protein necessary for intramitochondrial cholesterol transport. Here, we show that StAR expression is also inhibited by TGFbeta1 in the human adrenocortical carcinoma cell line NCI-H295R. This inhibitory effect is mediated by Smad proteins. Indeed, we found that overexpression of wild-type Smad3 inhibited endogenous StAR mRNA expression while overexpression of a dominant negative Smad3 protein reversed the inhibitory effect of TGFbeta1 on StAR mRNA expression. Taken together, these results demonstrate that the Smad3 protein is involved in TGFbeta-dependent regulation of steroidogenesis.

Adrenal Cortex↗
PubMed1998

Transforming growth factor beta1 decreases cholesterol supply to mitochondria via repression of steroidogenic acute regulatory protein expression.

Transforming growth factor-betas (TGF-betas) constitute a family of dimeric proteins that affect growth and differentiation of many cell types. TGF-beta1 has also been proposed to be an autocrine regulator of adrenocortical steroidogenesis, acting mainly by decreasing the expression of cytochrome P450c17. Here, we demonstrate that TGF-beta1 has a second target in bovine adrenocortical cells, namely the steroidogenic acute regulatory protein (StAR). Indeed, supplying cells with steroid precursors revealed that TGF-beta1 inhibited two steps in the steroid synthesis pathway, one prior to pregnenolone production and another corresponding to P450c17. More specifically, TGF-beta1 inhibited pregnenolone production but neither the conversion of 25-hydroxycholesterol to pregnenolone nor P450scc activity. Thus, TGF-beta1 must decrease the cholesterol supply to P450scc. We therefore examined the effect of TGF-beta1 on the expression of StAR, a mitochondrial protein implicated in intramitochondrial cholesterol transport. TGF-beta1 decreased the steady state level of StAR mRNA in a time- and concentration-dependent manner. This inhibition occurs at the level of StAR transcription and depends on RNA and protein synthesis. It is likely that the TGF-beta1-induced decrease of StAR expression that we report here may be expanded to other steroidogenic cells in which a decrease of cholesterol accessibility to P450scc by TGF-beta1 has been hypothesized.

Animals↗
PubMed1998

Tissue culture assays using Caco-2 cell line differentiate virulent from non-virulent Listeria monocytogenes strains.

Within the group of Listeria sp., only L. monocytogenes is pathogenic for humans and numerous studies of L. monocytogenes strains have described non-virulent isolates. In this study, the potential value of two tissue culture assays (TCA) was analysed to ascertain the virulence properties of L. monocytogenes strains, initially typed for virulence using the immunocompromised mouse model (ICMM). The first assay assessed both the penetration into, and multiplication within, Caco-2 cells (PM assay): the second was a plaque-forming assay (PF assay). All the clinical isolates (nine strains) were virulent in both TCA. Conversely, all the non-pathogenic species (seven strains) were non-virulent in PM and PF assays. Compared with the virulence obtained in the ICMM with 29 Listeria strains, including 12 non-virulent L. monocytogenes strains, the sensitivity of both TCA was equal to1. Specificity was 0.89 and 0.84 for the PF and PM assays, respectively. However, a study of strains exhibiting virulence differences in three other in vivo virulence models showed that ICMM only detected highly virulent strains. The specificity of the PF test could, therefore, be higher, and close to that obtained by the enumeration of viable bacteria in the spleen of mice infected by subcutaneous injection in the footpad and by intravenous injection. Taken together, this study confirms the existence of low-virulence L. monocytogenes strains and shows that the virulence status of some non-clinical L. monocytogenes isolates depends on the virulence models used. The data suggest that the PF assay could be used as a primary test to evaluate the virulence of Listeria strains in order to reduce the cost of testing all strains in vivo.

Animals↗
PubMed1997

Analysis of small latent transforming growth factor-beta complex formation and dissociation by surface plasmon resonance. Absence of direct interaction with thrombospondins.

Transforming growth factor-beta (TGFbeta) is a pluripotent regulator of cell growth and differentiation. The growth factor is expressed as a latent complex that must be converted to an active form before interacting with its ubiquitous high affinity receptors. This conversion involves the release of the mature TGFbeta through disruption of the noncovalent interactions with its propeptide or latency associated protein (LAP). Complex formation or dissociation between LAP and TGFbeta plays a very important role in TGFbeta biological activity at different steps. To further characterize the kinetic parameters of this interaction, we have employed surface plasmon resonance biosensor methodology. Using this technique, we observed real time association of LAP with mature TGFbeta1. The complex formation showed an equilibrium Kd around 3-7 nM. Furthermore, we observed dissociation of the complex in the presence of extreme pH, chaotropic agents, or plasmin, confirming their effects on TGFbeta activation. The same approach was used to examine whether latent TGFbeta1 could interact with thrombospondins, previously described as activators of latent TGFbeta. Using this method, we could not detect any direct interaction of thrombospondins with either LAP alone, TGFbeta1 alone, or the small latent TGFbeta1 complex. This suggests that activation of latent TGFbeta1 complex by thrombospondins is through an indirect mechanism.

Humans↗
PubMed1996

An intronic polymorphic repeat sequence modulates interleukin-1 alpha gene regulation.

Recently, we characterized a polymorphism within IL-1 alpha intron 6 as a variable number of a 46 bp tandem repeat (ranging from 5 to 18 repeats). We now analyse whether this polymorphism could play a role in IL-1 alpha gene regulation. We have found that reporter gene expression driven by the IL-1 alpha promoter or a heterologous promoter was decreased by increasing numbers of the repeat sequence corresponding to the most frequent alleles seen in the human population. Furthermore, we showed that the transcription factor Sp1 can bind to the 46 bp sequence. Finally, we were unable to show a statistically-significant relation between in vitro IL-1 alpha production and the number of repeats although there was a clear trend towards an inverse relation. Taken together, these results are consistent with a negative regulatory role for IL-1 alpha intron 6 repeat sequence on IL-1 alpha basal gene transcription.

Adult↗
PubMed1995

Absence of correlation between IL-1 alpha intron 6 polymorphism and rheumatoid arthritis.

Several studies have implicated interleukin 1 alpha (IL-1 alpha) in the pathogenesis of rheumatoid arthritis (RA). We analysed IL-1 alpha intron 6 polymorphism in relation to RA (50 patients with RA and 50 healthy controls). The study of a healthy control population confirmed the existence of the different alleles with a frequency similar to that in the Caucasian populations of northern England. Allele and genotype distributions did not differ significantly between the normal and RA populations, although the allele corresponding to 8 repeats was over-represented in the RA population (8 and 14% in the healthy and RA populations respectively). This suggests that IL-1 alpha intron 6 polymorphism could be part of a complex process involving other unidentified genetic factors in the pathogenesis of RA.

Alleles↗
PubMed1995

[Determining of new karyotypes: value of a statistical method].

For the authors, Ectemnorrhininae (coleoptera, curculionidae) from Southern Indian Ocean islands constitute the subject of systematic karyological studies, in order to get further information as to the phylogeny of this group of insects. A previous study had been carried out about 3 different species, Ectemnorrhinus drygalskii, E. viridis and Dusmoecetes richtersi, through direct observation of the only few mitotic metaphase plates, completely isolated from each other, which could be found in adult testis squashes. But a new sort of technique is now available, and which involves a program of data statistical analysis, allowing the sorting out of objects which are characterized by 2 different parameters (in this case, the objects are chromosomes, defined by their length and centromeric index). So that almost all chromosomes can be fully examined in a given preparation, and this can be done in a standardized manner. Applying these new principles, a new determination of the mean values of the parameters characterizing the different chromosomes of the same 3 species is now being worked out. These values will be more accurently determined, and it will then be possible to compare such values, more efficiently, with those of other species of the same group when determined according to the same principles.

Animals↗
PubMed1994

Absence of lentiviral and human T cell leukemia viral sequences in patients with rheumatoid arthritis.

OBJECTIVE: The etiology of rheumatoid arthritis (RA) is unknown, and the possibility that an infectious agent is involved has not been excluded. Lentiviruses can cause chronic arthritis in humans and in animals and have been suggested as candidate agents in RA. We therefore tested for the presence of lentiviruses and also for human T cell leukemia virus type I (HTLV-I)/HTLV-II in cells from patients with RA. METHODS: We used the polymerase chain reaction with degenerate primers designed to recognize highly conserved nucleotide sequences from 5 different pathogenic lentiviruses. This method allowed the detection of at least 1 infected cell/20,000 uninfected cells in control experiments. RESULTS: Testing of synovial cells and blood cells from patients with early RA and patients with established RA did not yield any specific viral product. CONCLUSION: Our results do not support the presence of lentiviruses or HTLV-like sequences in RA.

Adult↗
PubMed1994

Comparative production of IL-1 beta and IL-1 alpha by LPS-stimulated human monocytes: ELISAs measurement revisited.

There has always been an apparent discrepancy between the levels of IL-1 alpha and IL-1 beta mRNA and that of their corresponding proteins. Indeed, LPS-stimulated human monocytes produce about 10 times more IL-1 beta mRNA and IL-1 alpha mRNA, while the ratio of the corresponding proteins is the opposite, a difference that has been attributed to less efficient translation of IL-1 beta mRNA. Using a home-made ELISA that recognizes the 31-kDa precursor of IL-1 beta (proIL-1 beta), we found that LPS-stimulated human monocytes produced at least 20 times more IL-1 beta than IL-1 alpha, a ratio in accordance with the corresponding mRNA levels. This difference with previous reports is due to the fact that commercial ELISAs recognize, little if at all, proIL-1 beta. Furthermore, we found that cell lysis with CHAPS released significantly more IL-1 beta than did classical freeze-thawing.

Adult↗
PubMed1994

Differential priming effects of proinflammatory cytokines on human neutrophil oxidative burst in response to bacterial N-formyl peptides.

Cytokines such as tumor necrosis factor alpha (TNF-alpha), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 8 (IL-8), IL-6, IL-1 alpha, and IL-1 beta produced during the immune and inflammatory responses to bacterial stimuli have been reported to interact with polymorphonuclear neutrophil (PMN) activities. However, contradictory findings on their direct and priming effects on the PMN oxidative burst, which is essential for bacterial killing, have been reported. We have used a flow cytometry method to study the effects of these cytokines on the oxidative burst of PMN in whole blood to avoid PMN activation related to isolation procedures. None of the cytokines tested directly activated the PMN oxidative burst, but they did have differential priming effects on the oxidative burst in response to bacterial N-formyl peptides. TNF, GM-CSF, and IL-8 strongly primed a subpopulation of PMN to produce H2O2 in response to N-formyl-methionyl-leucyl-phenylalanine (FMLP), while IL-1 alpha, IL-1 beta, and IL-6 failed to do so. Furthermore, the addition of TNF, GM-CSF, or IL-8 to whole blood increased the capacity of a subpopulation of PMN to bind N-formyl peptides, a phenomenon that could account, at least in part, for the strong H2O2 production in response to FMLP after priming by the cytokines. The size of the primed hyperresponsive subpopulation was greater after priming with TNF or GM-CSF than after priming with IL-8. However, GM-CSF, TNF, and IL-8 at suboptimal concentrations cooperated in the induction of a subpopulation hyperresponsive to FMLP. These results show that, of the various proinflammatory cytokines tested, TNF, GM-CSF, and IL-8 strongly prime the PMN oxidative burst in response to bacterial peptides in whole blood and suggest that these cytokines may play a critical role in bacterial killing in vivo.

Cytokines↗
PubMed1993

Priming of polymorphonuclear neutrophils by tumor necrosis factor alpha in whole blood: identification of two polymorphonuclear neutrophil subpopulations in response to formyl-peptides.

We have used a cytofluorometric method to study the effect of tumor necrosis factor alpha (TNF) priming on the oxidative burst, FMLP-receptor expression and actin polymerization of whole blood polymorphonuclear neutrophils (PMN). This technique permits the study of single cells and, thus, allowed us to examine the responsiveness of PMN to TNF in whole blood. We found that TNF in whole blood strongly primed a subpopulation of PMN to produce H2O2 in response to FMLP stimulation, whereas TNF and FMLP alone did not have a significant effect. Furthermore, adding TNF to whole blood increased the capacity of a subpopulation of PMN to bind N-formyl peptides at 4 degrees C, a phenomenon that could account, at least in part, for the strong H2O2 production in response to FMLP after TNF priming. Dual-color cytometric analysis showed that TNF primed actin polymerization on the same subpopulation in response to FMLP. Because the PMN subpopulation, which strongly bound N-formyl peptides at 4 degrees C, was no longer detectable after 1 minute of incubation at 37 degrees C, our data suggest that TNF treatment of PMN in whole blood primes a subpopulation that actively cycles FMLP receptors. These results suggest that PMN in the circulation may respond weakly to bacterial peptides and that TNF may play a critical role in the induction of the oxidative burst in vivo.

Actins↗
PubMed1993

Genetic polymorphism of human interleukin-1 alpha.

Interleukin-1 alpha (IL-1 alpha) has been implicated in the pathogenesis of infectious, autoimmune and inflammatory diseases. There is, however, very little information on the cis-acting sequences involved in IL-1 alpha regulation or whether there is any variation in the structure of the gene. It is known that intron 6 of IL-1 alpha shows a 5 x 46 bp tandem repeat in the genomic sequence. We have studied this region of the gene. Amplification by polymerase chain reaction showed different sized products from different individuals, most being of higher molecular weight than the expected size of 620 bp. Sequencing demonstrated that the polymorphism was due to a variable number of repeats of the 46 bp sequence. This was confirmed by restriction fragment length analysis of genomic DNA. Altogether, 72 unrelated individuals were tested and 6 alleles ranging from 5 to 18 repeats were found, the most frequent allele (62%) containing 9 repeats. This polymorphism may be of interest in gene function, since each repeat contains three potential binding sites for transcriptional factors: an SP1 site, a viral enhancer element and a glucocorticoid-responsive element. The latter, at least, demonstrates site-specific protein binding by electromobility shift assay. The functional significance of the polymorphism and its allelic frequency in inflammatory and autoimmune diseases are currently under investigation.

Base Sequence↗
PubMed1993

Polymorphic tandem repeat region in interleukin-1 alpha intron 6.

Analysis of polymerase chain reaction amplified products from the sixth intron of the human interleukin-1 alpha gene reveals a high polymorphism (polymorphism information content = 0.51) in a Caucasian population. Altogether, seven alleles have been defined ranging from 620 to 1220bp. This polymorphism is probably attributable to a variable number of 46-bp tandem repeats, each containing potential regulatory sequences.

Base Sequence↗
PubMed1993

[Effects of antibiotics on production of cytokines by human monocytes].

Antibiotics do not act alone but in conjunction with the host defence system. In particular, it has been shown that antibiotics can modify cytokine production. The authors reported here the effects of antibiotics which penetrate inside the cells, such as quinolones and macrolides, on the capacity of blood monocytes to produce IL-I alpha, IL-1 beta, TNF alpha and IL-6 in response to endotoxin. Antibiotics can exert a differential effect on cytokine production: in fact, quinolones, in vitro, at concentrations higher than 25 micrograms/ml decreased IL-1 beta, TNF alpha and IL-6, while they do not modify IL-1 alpha. Moreover, ciprofloxacin orally administered (25 mg/kg for 7 days) transitory increased cytokine production. These results are discussed in terms of tissue concentration. Among the same family of antibiotics such as macrolides, differences on cytokine modulation were observed: spiramycin and erythromycin increased IL-6 production while roxithromycin did not exert any significant effect. All these results tend to prove that some antibiotics are immunomodulators; however interactions between antibiotics and immune responses are complex and studies with patients with infections will be necessary to a better understanding of these relationships.

4-Quinolones↗