monique singer | Université Paris VI (original) (raw)
Papers by monique singer
PubMed, Jul 1, 1998
Bronchopulmonary hyperreactivity (BHR), an increased responsiveness to nonspecific bronchoconstri... more Bronchopulmonary hyperreactivity (BHR), an increased responsiveness to nonspecific bronchoconstrictor agents, is a well-known characteristic of bronchial asthma. It has been recently suggested that the severity of this disease is related to the endotoxin content of house dust. In the present report, it is shown that the i.p. administration of bacterial LPS to mice is followed by a marked early dose-dependent BHR in response to methacholine. The microscopic examination showed no ultrastructural lesions of the lungs or of the airways, but a marked neutrophil accumulation in the capillaries, as confirmed by an increase of the lung content in the neutrophil enzyme marker myeloperoxidase. In parallel, high levels of TNF-alpha were found in plasma as well as its transcripts in the lung tissues. Using immunologic (anti-TNF-alpha and anti-granulocyte Abs), and pharmacologic (dexamethasone and vinblastine) tools, it is demonstrated that BHR is apparently neither related to the presence of neutrophils in the pulmonary microvasculature nor to the synthesis of TNF-alpha.
The Journal of Immunology, 1998
Bronchopulmonary hyperreactivity (BHR), an increased responsiveness to nonspecific bronchoconstri... more Bronchopulmonary hyperreactivity (BHR), an increased responsiveness to nonspecific bronchoconstrictor agents, is a well-known characteristic of bronchial asthma. It has been recently suggested that the severity of this disease is related to the endotoxin content of house dust. In the present report, it is shown that the i.p. administration of bacterial LPS to mice is followed by a marked early dose-dependent BHR in response to methacholine. The microscopic examination showed no ultrastructural lesions of the lungs or of the airways, but a marked neutrophil accumulation in the capillaries, as confirmed by an increase of the lung content in the neutrophil enzyme marker myeloperoxidase. In parallel, high levels of TNF-α were found in plasma as well as its transcripts in the lung tissues. Using immunologic (anti-TNF-α and anti-granulocyte Abs), and pharmacologic (dexamethasone and vinblastine) tools, it is demonstrated that BHR is apparently neither related to the presence of neutrophil...
Infection and Immunity, 1999
Infection by the enteric bacterial pathogen Shigella results in intense mucosal inflammation and ... more Infection by the enteric bacterial pathogen Shigella results in intense mucosal inflammation and destruction of the colonic and rectal epithelium in infected humans. Initial bacterial translocation occurs through the follicle-associated epithelium. Previous experiments suggest that interleukin-1 (IL-1) is crucial to trigger inflammation, particularly in the follicular zones. During the first 4 hours of infection in a rabbit ligated-loop model of intestinal invasion, there are two salient characteristics: (i) a high concentration of IL-1α and IL-1β, both in infected Peyer's patch tissue and in the corresponding efferent mesenteric blood, and (ii) a very low level of expression of IL-1 receptor antagonist (IL-1ra). These may reflect a combination of regulation of expression and secretion of IL-1α, IL-1β, and IL-1ra by both resident and recruited phagocytes and the induction of mononuclear phagocyte apoptosis by Shigella . This low IL-1ra/IL-1 ratio likely accounts for the rapid, u...
Journal of Leukocyte Biology, 2000
The central role of alveolar macrophages in the establishment of lipopolysaccharide (LPS)-induced... more The central role of alveolar macrophages in the establishment of lipopolysaccharide (LPS)-induced lung inflammation is well demonstrated. They produce and release numerous proinflammatory molecules, among which is tumor necrosis factor α (TNF-α), a cytokine responsible in part for the neutrophilic alveolitis. Interleu-kin-10 (IL-10) produced by LPS-activated mononuclear phagocytes is a major anti-inflammatory cytokine that down-regulates TNF-α synthesis. We studied the ability of murine alveolar macrophages to produce IL-10 in vivo and in vitro, in response to LPS. Unexpectedly, the IL-10 protein was not detected in the whole lung and airspaces after LPS intranasal instillation. In addition, no IL-10 protein was found in supernatants of isolated and LPS-stimulated alveolar macrophages. The lack of IL-10 synthesis was confirmed by the absence of specific RNA transcripts. By contrast and as expected, autologous peritoneal macrophages produced IL-10 upon LPS challenge. Drugs that usual...
The Journal of Immunology, 1998
ABSTRAC TBronchopulmonary hyperreactivity (BHR), an increased responsiveness to nonspecific bronc... more ABSTRAC TBronchopulmonary hyperreactivity (BHR), an increased responsiveness to nonspecific bronchoconstrictor agents, is a well-known characteristic of bronchial asthma. It has been recently suggested that the severity of this disease is related to the endotoxin content of house dust. In the present report, it is shown that the i.p. administration of bacterial LPS to mice is followed by a marked early dose-dependent BHR in response to methacholine. The microscopic examination showed no ultrastructural lesions of the lungs or of the airways, but a marked neutrophil accumulation in the capillaries, as confirmed by an increase of the lung content in the neutrophil enzyme marker myeloperoxidase. In parallel, high levels of TNF-alpha were found in plasma as well as its transcripts in the lung tissues. Using immunologic (anti-TNF-alpha and anti-granulocyte Abs), and pharmacologic (dexamethasone and vinblastine) tools, it is demonstrated that BHR is apparently neither related to the presence of neutrophils in the pulmonary microvasculature nor to the synthesis of TNF-alpha.
American Journal of Physiology-Lung Cellular and Molecular Physiology, 2003
In mice, intratracheal challenges with antigen (ovalbumin) or recombinant murine interleukin-13 (... more In mice, intratracheal challenges with antigen (ovalbumin) or recombinant murine interleukin-13 (IL-13) induce lung inflammation, bronchial hyperreactivity (BHR), and mucus accumulation as independent events (Singer M, Lefort J, and Vargaftig BB. Am J Respir Cell Mol Biol 26: 74–84, 2002), largely mediated by leukotrienes (LT). We previously showed that LTC4 was released 15 min after ovalbumin, and we show that it induces the expression of monocyte chemoattractant proteins 1 and 5 and KC in the lungs, as well as IL-13 mRNA. Instilled intratracheally, these chemokines induced BHR and mucus accumulation, which were inhibited by the 5-lipoxygenase inhibitor zileuton and by the cysteinyl-LT receptor antagonist MK-571, suggesting mediation by cysteinyl-LT. Because these chemokines also induced release of LT into the bronchoalveolar lavage fluid and IL-13 into the lungs, we hypothesize that LT- and chemokine-based loops for positive-feedback regulations cooperate to maintain and amplify B...
American journal of physiology. Lung cellular and molecular physiology, 2003
Antigen induces murine bronchial hyperreactivity (BHR), inflammation, mucus accumulation, and air... more Antigen induces murine bronchial hyperreactivity (BHR), inflammation, mucus accumulation, and airway remodeling. To investigate whether leukotrienes (LT) mediate the effects of antigen [ovalbumin (Ova)], we studied 5-lipoxygenase (5-LO) expression in immunized BP2 mice and blocked LT synthesis with the 5-LO inhibitor zileuton or antagonized their effects with receptor antagonists [cysteinyl leukotriene (Cys-LT)-ra MK-571, LY-171883; LTB4-ra PH-163]. Cys-LT content increased in the bronchoalveolar lavage fluid (BALF) as early as 15 min after the intratracheal instillation of Ova. Zileuton inhibited LT release in the BALF and eosinophil recruitment in the lungs, and dose dependently reduced BHR, mucus accumulation, and remodeling, as did the LT-ra. Thus LT, released just after antigen challenge, might constitute the first step in accounting for the effects of Ova. Because mucus accumulation is regulated via the EGF receptor (EGFR), which is also implicated in the effects of LT, we stu...
American Journal of Physiology-Lung Cellular and Molecular Physiology, 2002
We previously showed that the seminatural surfactant Curosurf inhibits the in vitro synthesis of ... more We previously showed that the seminatural surfactant Curosurf inhibits the in vitro synthesis of secretory type IIA phospholipase A2 (sPLA2-IIA) in alveolar macrophages (AM). These cells are the main source of sPLA2-IIA in a guinea pig model of lipopolysaccharide (LPS)-induced acute lung injury (ALI). Here, we investigate the effect of Curosurf on the pulmonary synthesis of sPLA2-IIA in this ALI model. Our results showed that intratracheal administration of LPS (330 μg/kg) induced an increase in pulmonary expression of sPLA2-IIA, which was inhibited when animals received Curosurf (16 mg/guinea pig) 30 min or 8 h after LPS instillation. When AM were isolated from LPS-treated animals and cultured in conditioned medium, they expressed higher levels of sPLA2-IIA than AM from saline-treated animals. This ex vivo sPLA2-IIA expression was significantly reduced when guinea pigs received Curosurf 30 min after LPS instillation. Finally, we examined the effect of Curosurf on pulmonary inflamma...
Innate Immunity, 2010
Arsenic trioxide, As 2O3, already used in human anti-cancer therapy, is also an efficient agent a... more Arsenic trioxide, As 2O3, already used in human anti-cancer therapy, is also an efficient agent against the autoimmune and inflammatory diseases developed in MRL/lpr mice. Inflammatory bowel diseases (IBDs), notably Crohn’s disease, which remain without efficient treatment, display autoimmune and inflammatory components. We, therefore, hypothesized that As2O 3 may be active on IBDs. Using the 2,4,6-trinitrobenzene sulfonic acid-induced murine model of colitis, we demonstrate that As2O3 used either in a preventive or a curative mode markedly reduced the induced colitis as assessed by macroscopic and microscopic scores, leading to prolonged mice survival. In addition, As2O3 was able to inhibit NF-κB expression and DNA-binding in colon extracts leading to decreased cytokine gene expression (i.e. tumor necrosis factor-α, interleukin(IL)-1β, IL-12, IL-17, IL-18, and IL-23). Interestingly, As2O3 also reduced keratinocyte-derived chemokine (KC), inducible nitric oxide synthase (iNOS) mRNA ...
European Journal of Biochemistry, 2000
The effect of arachidonic acid (C20:4) on the production of secretory type II phospholipase A2 (s... more The effect of arachidonic acid (C20:4) on the production of secretory type II phospholipase A2 (sPLA2‐II) by guinea‐pig alveolar macrophages was investigated. We show that incubation of these cells with 1–30 µm of arachidonic acid inhibits the synthesis of sPLA2‐II in a concentration‐dependent manner with an IC50 of ≈ 7.5 µm. The inhibition by low concentrations (5 µm) of arachidonic acid was partially reduced by pretreatment of alveolar macrophages with cyclooxygenase or cytochrome P450 inhibitors (aspirin and 1‐aminobenzotriazole, respectively), but not by lipoxygenase inhibitor, BW A4C. However, these inhibitors failed to interfere with the effect of high concentrations (30 µm) of arachidonic acid, suggesting that the latter may act on the expression of sPLA2‐II, at least in part, independently of eicosanoid generation. Indeed, a similar inhibitory effect on sPLA2‐II activity and mRNA expression was observed with other unsaturated fatty acids such as eicosapentaenoic (C20:5) and ...
Molecular Biology and Evolution, 1996
In rodents, the variable coding sequence (VCS) multigene family displays extensive evolutionary d... more In rodents, the variable coding sequence (VCS) multigene family displays extensive evolutionary divergence in the protein-coding region. While certain VCS genes coding for proline-rich proteins (hPR-PB, mMSG1, rPR-VBI) are conserved in primates and rodents, others seem to be specific to certain genera. This appears to be the case for the Rattus genes forming the A-subclass. This subclass is composed of three genes in R. norvegicus and probably five genes in R. ruttus. The first described VCSA gene (Rn. VCSAI) was found to encode a prohormone-like protein named SMRl (-VAl), expressed mainly in the submandibular glands (SMG) of male rats. To further understand the evolution of this variable multigene family, we have cloned the two additional genes (Rn. VCSA2 and Rn. VCSA3) forming the R. norvegicus A-subclass and three VCSA genes (Rr. VCSAla, h and Rr. VCSA2) of R. ruttus. The putative SMRI proteins encoded by all these genes display the same prohormone-like structure as Rn.SMRl-VA I. However, we observe a polymorphism in some internal cleavage sites which suggests that multiple processing of the SMRl proteins could result in the liberation of peptides differing in structure and length. The phylogenetic analysis of the sequences reveals that the duplication events giving rise to the VCSAI,-A2, and-A3 progenitors were anterior to the R. norvegicus and R. ruttus split, and that a VCSAI duplication event likely occurred specifically in R. ruttus. A striking observation is that the coding sequences of the VCSA genes have rapidly diverged from their ancestors. Along all branches of the phylogeny, the nonsynonymous divergence rate is identical or superior to the synonymous divergence rate. We suggest that frequent changes in functional requirements are mainly responsible for the episodic evolution and the rapid divergence of the VCSA genes. Abbreviations: Indels, insertions/deletions; K,, number of nucleotide substitutions per synonymous site; K,, number of nucleotide substitutions per nonsynonymous site; SMG, submandibular gland: ORF, open reading frame; VCS, variable coding sequence.
The Journal of Immunology, 2004
The lack of a mouse model of acute rectocolitis mimicking human bacillary dysentery in the presen... more The lack of a mouse model of acute rectocolitis mimicking human bacillary dysentery in the presence of invasive Shigella is a major handicap to study the pathogenesis of the disease and to develop a Shigella vaccine. The inability of the mouse intestinal mucosa to elicit an inflammatory infiltrate composed primarily of polymorphonuclear leukocytes (PMN) may be due to a defect in epithelial invasion, in the sensing of invading bacteria, or in the effector mechanisms that recruit the PMN infiltrate. We demonstrate that the BALB/cJ mouse colonic epithelium not only can be invaded by Shigella, but also elicits an inflammatory infiltrate that, however, lacks PMN. This observation points to a major defect of mice in effector mechanisms, particularly the lack of expression of the CXC chemokine, IL-8. Indeed, this work demonstrates that the delivery of recombinant human IL-8, together with Shigella infection of the colonic epithelial surface, causes an acute colitis characterized by a stron...
Journal of Immunological Methods, 1997
A competitive RT-PCR method that permits reliable quantification of minute amounts of reverse-tra... more A competitive RT-PCR method that permits reliable quantification of minute amounts of reverse-transcribed mouse lymph node mRNA is described. Using this technique, an absolute number of cDNA copies ranging from 10 3 to 10 5 can be determined, with a precision superior to 25%. The standard templates described in the present study permit the quantitation Ž. of beta-actin, IFN gamma, IL2, IL3, IL4, IL10, IL12 p40 subunit , TGF beta 1, inducible nitric oxide synthase, ELAM-1, VCAM-1, and ICAM-1 mouse mRNA. The expression of a particular transcript is normalized to an arbitrary number of actin transcripts. The standard templates and wild-type cDNA have nearly identical sequences, but they can be distinguished by unique restriction sites. Known amounts of these standard templates, are co-amplified with serial dilutions of the cDNA derived from the mRNA of interest. Oligonucleotide primer pairs possessing 3 X octamers found infrequently in the mouse Ž y6. Ž genome F 0.26 = 10 are used to amplify sequences, chosen to contain no GC stretches longer than 8 PCRaree. Ž. software Griffais et al., 1991. Samples of each PCR product are digested separately with restriction endonucleases unique either for the wild-type or the standard amplicon. The quantitation of the test product and the standard product is easily carried out following their electrophoresis in an ethidium bromide-stained agarose gel. q 1997 Elsevier Science B.V.
Journal of Biological Chemistry, 2000
Exposure of human pulmonary microvascular endothelial cells (HPMECs) to phorbol 12-myristate 13-a... more Exposure of human pulmonary microvascular endothelial cells (HPMECs) to phorbol 12-myristate 13-acetate (PMA) leads to the increase of prostaglandin H synthase (PGHS)-2 protein levels. Under same conditions and according to its constitutive nature, no significant variation of PGHS-1 protein was noted. The elevation of the intracellular cAMP rate is known to enhance PGHS-2 levels through a protein kinase A pathway in various cells. To determine whether the extracellular cAMP also regulates the inducible expression of PGHS, cultured HPMECs were exposed to cAMP alone or in combination with PMA. The PMA-induced PGHS-2 protein was attenuated by the extracellular cAMP. In addition, PGHS-2 activity evaluated through 6-keto-PGF1␣ generation, which was enhanced by PMA was inhibited by extracellular cAMP. Furthermore, in HPMEC medium, PMA-induced PGHS-2 expression was accompanied by the generation of a transferable activity (TA) able to abolish platelet aggregation. This resulting TA was dependent from PGHS-2 pathway, because NS-398, a selective inhibitor of PGHS-2, suppressed its production. The inhibitory TA released by treated HPMECs was also prevented by extracellular cAMP. The specific protein kinase A (PKA) inhibitor blocked the extracellular cAMP effect on both PMA-induced 6-keto-PGF1␣ synthesis and inhibitory TA generation, suggesting the involvement of PKA signaling at the outer surface of HPMECs. Accordingly, we established, in phosphorylation experiments, the presence of an endothelial ectoprotein kinase activity, able to phosphorylate the synthetic substrate kemptide in a cAMP-dependent mode. Reverse transcription-polymerase chain reaction analysis showed that PMA-induced PGHS-2 mRNA was markedly reduced by extracellular cAMP. Together, these findings provide the first experimental evidence that extracellular cAMP is able to reduce HPMEC PGHS-2 expression in terms of mRNA, protein, and enzyme activity through an ecto-PKA pathway. In addition, they outline the potential role of endothelial PGHS-2 in the limitation of platelet activation during inflammatory processes.
European Journal of Immunology, 1996
This report examines the effects of recombinant murine interleukin-10 (rmIL-10) on antigen-induce... more This report examines the effects of recombinant murine interleukin-10 (rmIL-10) on antigen-induced beta-hexosaminidase, leukotriene (LT)C4 and cytokine release from mouse bone marrow-derived mast cells (BMMC). BMMC sensitized to hapten-monoclonal IgE directed against dinitrophenol-bovine serum albumin (DNP-BSA) and challenged with 10 ng/ml DNP-BSA generated beta-hexosaminidase and LTC4-like material which was followed by tumor necrosis factor-alpha (TNF-alpha) and granulocyte-macrophage colony-stimulating factor (GM-CSF) mRNA expression and protein release. Incubation of BMMC with 1-100 ng/ml rmIL-10 inhibited cytokine generation, without affecting beta-hexosaminidase and LTC4-like material release. TNF-alpha, but not GM-CSF mRNA expression, was also diminished in rmIL-10-treated BMMC, suggesting that down-regulation of cytokine production by rmIL-10 involves different mechanisms. These results identify a novel biological action of IL-10 as an inhibitor of cytokine production by stimulated mast cells.
European Journal of Immunology, 1998
We have previously shown that mouse bone marrow-derived mast cells (BMMC) can process and present... more We have previously shown that mouse bone marrow-derived mast cells (BMMC) can process and present immunogenic peptides to CD4 T cells. Here, we report on a T cell-dependent MHC class II-mediated mast cell activation resulting in IL-4 transcription and protein release. Presentation of optimal doses of ovalbumin peptide 323-339 resulted in IL-2 production by a specific T cell hybridoma and increase in IL-4 mRNA transcription in mast cells. IL-4 mRNA transcription increased by 200-fold in mast cells treated in IL-3/IL-4/granulocyte-macrophage colony-stimulating factor (high presenters) whereas only a tenfold increase or no increase were obtained with IL-3/IL-4/IFN-gamma- or IL-3-treated mast cells (low presenters), respectively. Induction of IL-4 mRNA transcription in purified mast cells by direct ligation of MHC class II molecules, using anti-I-A and anti-I-E-coated beads, indicates that MHC class II molecules are critical in this signaling pathway. However, when compared to T cells, anti-MHC class II-coated beads were less efficient, indicating a potential role of accessory molecules in this mast cell activation process. IgE-independent IL-4 production by mast cells as a result of cognate interaction with CD4 T cells could be critical for the development of type 2 responses. This novel mechanism may contribute to the induction and/or amplification of specific IgE-mediated allergic responses.
DNA and Cell Biology, 1995
The Variable Coding Sequence (VCS) multigene family of Rattus norvegicus, is composed of at least... more The Variable Coding Sequence (VCS) multigene family of Rattus norvegicus, is composed of at least 10 members, and shows extensive evolutionary divergence in the protein-coding region. Three members of the VCSA subclass, have been characterized: one of them, the VCSA1 gene mainly expressed in the submandibular gland (SMG) encodes the prohormone-like protein, SMR1-W1. As VCSA-related genes have not been detected in Mus musculus, the VCSA genes subclass is presumed to have recently emerged. To study the evolution of this subclass, we have looked for VCSA genes in a closely related species, Rattus rattus. By Northern analysis, we demonstrate that VCS-related mRNAs are present in the SMG, and that the level of VCSA mRN A accumulation is approximately equal in both sexes. By contrast, in R. norvegicus, males accumulate about 3,000 times more VCSA 1 mRN A than females. Using total SMG mRN A, an almost full-length cDNA, homologous to the cDNA of the R. norvegicus VCSA1 gene, was cloned by reverse transcriptase polymerase chain reaction (RT-PCR). The putative corresponding SMR1-VA1 protein is 146 amino acids long and presents the features characteristic of a secreted protein, with a potential signal peptide of 22 amino acids in the amino-terminal portion. The presence of potential processing multibasic sites suggests that small peptides could be generated (particularly a hexapeptide: Arg-Gln-His-Asn-Leu-Arg), as in the case of the SMR1-VA1 protein of R. norvegicus. From Southern blot analysis there appears that species-species modifications of VCSA gene copy number have occurred; R. rattus contains a greater VCSA1 copy number than R. norvegicus (two or three and one, respectively). demonstrated that SMR1-VA1 is the precursor of an undecapeptide, a hexapeptide, and a pentapeptide, all containing the Gln-His-Asn-Pro sequence. The SMR1-derived peptides are present in saliva; the hexapeptide is also released into the bloodstream following stimulation by catecholamines (Rougeot et al, 1994). The SMR1-VA1 protein is encoded by a gene (VCSA1) spanning 4.7 kb and containing 3 exons (Rosinski-Chupin and Rougeon, 1990a). This gene belongs to a novel family encompassing at least 10 members in R. norvegicus. In this species as in Mus musculus, the characterized members show extensive evolutionary divergence in the protein-coding region (Courty et al., 1994; Tronik Le Roux et al, 1994). The gene family has been named VCS, for variable coding sequence, and the genes have been grouped into different subclasses. In R. norvegicus, the B subclass is represented by the VCS-ßl gene (now named VCSB1) encoding a proline-rich protein (PR-VB1) similar to
Clinical & Experimental Allergy, 2003
Airway hyper-responsiveness (AHR), chronic airway inflammation and predominance of the T helper t... more Airway hyper-responsiveness (AHR), chronic airway inflammation and predominance of the T helper type-2 (Th2; IL-4, IL-5, IL-13) over the Th1 (IL-2, IFN-gamma) immune response are hallmarks of asthma. Alveolar macrophages (AM) are the most numerous cells in the airway lumen, where they represent the first immune cell population encountered by inhaled antigens. AM act as antigen-presenting cells (APC) and they release various soluble mediators and enzymes. AM thus play a prominent role in the modulation of the local immunity in airways. In allergic airways, AM have been implicated in the pathogenesis of inflammation by promoting the Th2 versus the Th1 cytokine patterns. Infections with attenuated bacteria or challenges with bacterial products may involve AM. Such stimuli have been shown to potentially restore the Th1/Th2 balance in asthmatic airways, but they also induce the release of inflammatory mediators. We investigated the response of AM when stimulated by two preparations of non-proliferating Bacillus Calmette-Guérin (BCG). We evaluated the cytokine production by AM from BP2 and C57BL/6 mice when cultured with heat-killed (HK) and extended freeze-dried (EFD) BCG. We then investigated in vivo the release of soluble factors in the airway lumen of mice after instillation of these BCG preparations. Finally, we studied the profile of cytokine transcripts in the lung of mice pre-treated with BCG and then challenged with ovalbumin (OVA). HK BCG induced the production of both TNF-alpha and IL-12, and did not prevent high levels of Th2 cytokine transcripts. In contrast, EFD BCG induced a response dominated by the production of IL-12, with no later over-expression of Th2 cytokine transcripts. Our results show that EFD BCG induce the release of the Th1-promoting cytokine IL-12 by AM, without the deleterious effects of HK BCG. These data suggest that EFD BCG may be considered as a potential novel treatment to restore the Th1/Th2 imbalance in asthma.
British Journal of Pharmacology, 1998
Our previous work demonstrated that bacterial lipopolysaccharide (LPS), administered by aerosol, ... more Our previous work demonstrated that bacterial lipopolysaccharide (LPS), administered by aerosol, induced tumour necrosis factor (TNF‐α) synthesis leading to the infiltration of neutrophils into mice lungs. The treatment of animals with prostaglandin E2 or dibutyryl cyclic AMP impaired both processes. In this study, the target cell for LPS and the modulation by cyclic AMP of TNF‐α production and neutrophil recruitment were investigated. One hour after inhalation of 2 ml of 0.3 mg ml−1 LPS, TNF‐α levels measured by an ELISA method increased in the bronchoalveolar lavage fluid (BALF) of BALB/c mice, reaching a maximal level 3 h after inhalation. The immunocytochemistry assay demonstrated that 1 h after inhalation, 21.2% of alveolar macrophages collected in the BALF were immunopositive for TNF‐α. When mice were pretreated, i.p., with 20 mg kg−1 rolipram, a selective inhibitor of phosphodiesterase type 4, TNF‐α levels in the BALF were significantly reduced and only 7.3% of alveolar macro...
PubMed, Jul 1, 1998
Bronchopulmonary hyperreactivity (BHR), an increased responsiveness to nonspecific bronchoconstri... more Bronchopulmonary hyperreactivity (BHR), an increased responsiveness to nonspecific bronchoconstrictor agents, is a well-known characteristic of bronchial asthma. It has been recently suggested that the severity of this disease is related to the endotoxin content of house dust. In the present report, it is shown that the i.p. administration of bacterial LPS to mice is followed by a marked early dose-dependent BHR in response to methacholine. The microscopic examination showed no ultrastructural lesions of the lungs or of the airways, but a marked neutrophil accumulation in the capillaries, as confirmed by an increase of the lung content in the neutrophil enzyme marker myeloperoxidase. In parallel, high levels of TNF-alpha were found in plasma as well as its transcripts in the lung tissues. Using immunologic (anti-TNF-alpha and anti-granulocyte Abs), and pharmacologic (dexamethasone and vinblastine) tools, it is demonstrated that BHR is apparently neither related to the presence of neutrophils in the pulmonary microvasculature nor to the synthesis of TNF-alpha.
The Journal of Immunology, 1998
Bronchopulmonary hyperreactivity (BHR), an increased responsiveness to nonspecific bronchoconstri... more Bronchopulmonary hyperreactivity (BHR), an increased responsiveness to nonspecific bronchoconstrictor agents, is a well-known characteristic of bronchial asthma. It has been recently suggested that the severity of this disease is related to the endotoxin content of house dust. In the present report, it is shown that the i.p. administration of bacterial LPS to mice is followed by a marked early dose-dependent BHR in response to methacholine. The microscopic examination showed no ultrastructural lesions of the lungs or of the airways, but a marked neutrophil accumulation in the capillaries, as confirmed by an increase of the lung content in the neutrophil enzyme marker myeloperoxidase. In parallel, high levels of TNF-α were found in plasma as well as its transcripts in the lung tissues. Using immunologic (anti-TNF-α and anti-granulocyte Abs), and pharmacologic (dexamethasone and vinblastine) tools, it is demonstrated that BHR is apparently neither related to the presence of neutrophil...
Infection and Immunity, 1999
Infection by the enteric bacterial pathogen Shigella results in intense mucosal inflammation and ... more Infection by the enteric bacterial pathogen Shigella results in intense mucosal inflammation and destruction of the colonic and rectal epithelium in infected humans. Initial bacterial translocation occurs through the follicle-associated epithelium. Previous experiments suggest that interleukin-1 (IL-1) is crucial to trigger inflammation, particularly in the follicular zones. During the first 4 hours of infection in a rabbit ligated-loop model of intestinal invasion, there are two salient characteristics: (i) a high concentration of IL-1α and IL-1β, both in infected Peyer's patch tissue and in the corresponding efferent mesenteric blood, and (ii) a very low level of expression of IL-1 receptor antagonist (IL-1ra). These may reflect a combination of regulation of expression and secretion of IL-1α, IL-1β, and IL-1ra by both resident and recruited phagocytes and the induction of mononuclear phagocyte apoptosis by Shigella . This low IL-1ra/IL-1 ratio likely accounts for the rapid, u...
Journal of Leukocyte Biology, 2000
The central role of alveolar macrophages in the establishment of lipopolysaccharide (LPS)-induced... more The central role of alveolar macrophages in the establishment of lipopolysaccharide (LPS)-induced lung inflammation is well demonstrated. They produce and release numerous proinflammatory molecules, among which is tumor necrosis factor α (TNF-α), a cytokine responsible in part for the neutrophilic alveolitis. Interleu-kin-10 (IL-10) produced by LPS-activated mononuclear phagocytes is a major anti-inflammatory cytokine that down-regulates TNF-α synthesis. We studied the ability of murine alveolar macrophages to produce IL-10 in vivo and in vitro, in response to LPS. Unexpectedly, the IL-10 protein was not detected in the whole lung and airspaces after LPS intranasal instillation. In addition, no IL-10 protein was found in supernatants of isolated and LPS-stimulated alveolar macrophages. The lack of IL-10 synthesis was confirmed by the absence of specific RNA transcripts. By contrast and as expected, autologous peritoneal macrophages produced IL-10 upon LPS challenge. Drugs that usual...
The Journal of Immunology, 1998
ABSTRAC TBronchopulmonary hyperreactivity (BHR), an increased responsiveness to nonspecific bronc... more ABSTRAC TBronchopulmonary hyperreactivity (BHR), an increased responsiveness to nonspecific bronchoconstrictor agents, is a well-known characteristic of bronchial asthma. It has been recently suggested that the severity of this disease is related to the endotoxin content of house dust. In the present report, it is shown that the i.p. administration of bacterial LPS to mice is followed by a marked early dose-dependent BHR in response to methacholine. The microscopic examination showed no ultrastructural lesions of the lungs or of the airways, but a marked neutrophil accumulation in the capillaries, as confirmed by an increase of the lung content in the neutrophil enzyme marker myeloperoxidase. In parallel, high levels of TNF-alpha were found in plasma as well as its transcripts in the lung tissues. Using immunologic (anti-TNF-alpha and anti-granulocyte Abs), and pharmacologic (dexamethasone and vinblastine) tools, it is demonstrated that BHR is apparently neither related to the presence of neutrophils in the pulmonary microvasculature nor to the synthesis of TNF-alpha.
American Journal of Physiology-Lung Cellular and Molecular Physiology, 2003
In mice, intratracheal challenges with antigen (ovalbumin) or recombinant murine interleukin-13 (... more In mice, intratracheal challenges with antigen (ovalbumin) or recombinant murine interleukin-13 (IL-13) induce lung inflammation, bronchial hyperreactivity (BHR), and mucus accumulation as independent events (Singer M, Lefort J, and Vargaftig BB. Am J Respir Cell Mol Biol 26: 74–84, 2002), largely mediated by leukotrienes (LT). We previously showed that LTC4 was released 15 min after ovalbumin, and we show that it induces the expression of monocyte chemoattractant proteins 1 and 5 and KC in the lungs, as well as IL-13 mRNA. Instilled intratracheally, these chemokines induced BHR and mucus accumulation, which were inhibited by the 5-lipoxygenase inhibitor zileuton and by the cysteinyl-LT receptor antagonist MK-571, suggesting mediation by cysteinyl-LT. Because these chemokines also induced release of LT into the bronchoalveolar lavage fluid and IL-13 into the lungs, we hypothesize that LT- and chemokine-based loops for positive-feedback regulations cooperate to maintain and amplify B...
American journal of physiology. Lung cellular and molecular physiology, 2003
Antigen induces murine bronchial hyperreactivity (BHR), inflammation, mucus accumulation, and air... more Antigen induces murine bronchial hyperreactivity (BHR), inflammation, mucus accumulation, and airway remodeling. To investigate whether leukotrienes (LT) mediate the effects of antigen [ovalbumin (Ova)], we studied 5-lipoxygenase (5-LO) expression in immunized BP2 mice and blocked LT synthesis with the 5-LO inhibitor zileuton or antagonized their effects with receptor antagonists [cysteinyl leukotriene (Cys-LT)-ra MK-571, LY-171883; LTB4-ra PH-163]. Cys-LT content increased in the bronchoalveolar lavage fluid (BALF) as early as 15 min after the intratracheal instillation of Ova. Zileuton inhibited LT release in the BALF and eosinophil recruitment in the lungs, and dose dependently reduced BHR, mucus accumulation, and remodeling, as did the LT-ra. Thus LT, released just after antigen challenge, might constitute the first step in accounting for the effects of Ova. Because mucus accumulation is regulated via the EGF receptor (EGFR), which is also implicated in the effects of LT, we stu...
American Journal of Physiology-Lung Cellular and Molecular Physiology, 2002
We previously showed that the seminatural surfactant Curosurf inhibits the in vitro synthesis of ... more We previously showed that the seminatural surfactant Curosurf inhibits the in vitro synthesis of secretory type IIA phospholipase A2 (sPLA2-IIA) in alveolar macrophages (AM). These cells are the main source of sPLA2-IIA in a guinea pig model of lipopolysaccharide (LPS)-induced acute lung injury (ALI). Here, we investigate the effect of Curosurf on the pulmonary synthesis of sPLA2-IIA in this ALI model. Our results showed that intratracheal administration of LPS (330 μg/kg) induced an increase in pulmonary expression of sPLA2-IIA, which was inhibited when animals received Curosurf (16 mg/guinea pig) 30 min or 8 h after LPS instillation. When AM were isolated from LPS-treated animals and cultured in conditioned medium, they expressed higher levels of sPLA2-IIA than AM from saline-treated animals. This ex vivo sPLA2-IIA expression was significantly reduced when guinea pigs received Curosurf 30 min after LPS instillation. Finally, we examined the effect of Curosurf on pulmonary inflamma...
Innate Immunity, 2010
Arsenic trioxide, As 2O3, already used in human anti-cancer therapy, is also an efficient agent a... more Arsenic trioxide, As 2O3, already used in human anti-cancer therapy, is also an efficient agent against the autoimmune and inflammatory diseases developed in MRL/lpr mice. Inflammatory bowel diseases (IBDs), notably Crohn’s disease, which remain without efficient treatment, display autoimmune and inflammatory components. We, therefore, hypothesized that As2O 3 may be active on IBDs. Using the 2,4,6-trinitrobenzene sulfonic acid-induced murine model of colitis, we demonstrate that As2O3 used either in a preventive or a curative mode markedly reduced the induced colitis as assessed by macroscopic and microscopic scores, leading to prolonged mice survival. In addition, As2O3 was able to inhibit NF-κB expression and DNA-binding in colon extracts leading to decreased cytokine gene expression (i.e. tumor necrosis factor-α, interleukin(IL)-1β, IL-12, IL-17, IL-18, and IL-23). Interestingly, As2O3 also reduced keratinocyte-derived chemokine (KC), inducible nitric oxide synthase (iNOS) mRNA ...
European Journal of Biochemistry, 2000
The effect of arachidonic acid (C20:4) on the production of secretory type II phospholipase A2 (s... more The effect of arachidonic acid (C20:4) on the production of secretory type II phospholipase A2 (sPLA2‐II) by guinea‐pig alveolar macrophages was investigated. We show that incubation of these cells with 1–30 µm of arachidonic acid inhibits the synthesis of sPLA2‐II in a concentration‐dependent manner with an IC50 of ≈ 7.5 µm. The inhibition by low concentrations (5 µm) of arachidonic acid was partially reduced by pretreatment of alveolar macrophages with cyclooxygenase or cytochrome P450 inhibitors (aspirin and 1‐aminobenzotriazole, respectively), but not by lipoxygenase inhibitor, BW A4C. However, these inhibitors failed to interfere with the effect of high concentrations (30 µm) of arachidonic acid, suggesting that the latter may act on the expression of sPLA2‐II, at least in part, independently of eicosanoid generation. Indeed, a similar inhibitory effect on sPLA2‐II activity and mRNA expression was observed with other unsaturated fatty acids such as eicosapentaenoic (C20:5) and ...
Molecular Biology and Evolution, 1996
In rodents, the variable coding sequence (VCS) multigene family displays extensive evolutionary d... more In rodents, the variable coding sequence (VCS) multigene family displays extensive evolutionary divergence in the protein-coding region. While certain VCS genes coding for proline-rich proteins (hPR-PB, mMSG1, rPR-VBI) are conserved in primates and rodents, others seem to be specific to certain genera. This appears to be the case for the Rattus genes forming the A-subclass. This subclass is composed of three genes in R. norvegicus and probably five genes in R. ruttus. The first described VCSA gene (Rn. VCSAI) was found to encode a prohormone-like protein named SMRl (-VAl), expressed mainly in the submandibular glands (SMG) of male rats. To further understand the evolution of this variable multigene family, we have cloned the two additional genes (Rn. VCSA2 and Rn. VCSA3) forming the R. norvegicus A-subclass and three VCSA genes (Rr. VCSAla, h and Rr. VCSA2) of R. ruttus. The putative SMRI proteins encoded by all these genes display the same prohormone-like structure as Rn.SMRl-VA I. However, we observe a polymorphism in some internal cleavage sites which suggests that multiple processing of the SMRl proteins could result in the liberation of peptides differing in structure and length. The phylogenetic analysis of the sequences reveals that the duplication events giving rise to the VCSAI,-A2, and-A3 progenitors were anterior to the R. norvegicus and R. ruttus split, and that a VCSAI duplication event likely occurred specifically in R. ruttus. A striking observation is that the coding sequences of the VCSA genes have rapidly diverged from their ancestors. Along all branches of the phylogeny, the nonsynonymous divergence rate is identical or superior to the synonymous divergence rate. We suggest that frequent changes in functional requirements are mainly responsible for the episodic evolution and the rapid divergence of the VCSA genes. Abbreviations: Indels, insertions/deletions; K,, number of nucleotide substitutions per synonymous site; K,, number of nucleotide substitutions per nonsynonymous site; SMG, submandibular gland: ORF, open reading frame; VCS, variable coding sequence.
The Journal of Immunology, 2004
The lack of a mouse model of acute rectocolitis mimicking human bacillary dysentery in the presen... more The lack of a mouse model of acute rectocolitis mimicking human bacillary dysentery in the presence of invasive Shigella is a major handicap to study the pathogenesis of the disease and to develop a Shigella vaccine. The inability of the mouse intestinal mucosa to elicit an inflammatory infiltrate composed primarily of polymorphonuclear leukocytes (PMN) may be due to a defect in epithelial invasion, in the sensing of invading bacteria, or in the effector mechanisms that recruit the PMN infiltrate. We demonstrate that the BALB/cJ mouse colonic epithelium not only can be invaded by Shigella, but also elicits an inflammatory infiltrate that, however, lacks PMN. This observation points to a major defect of mice in effector mechanisms, particularly the lack of expression of the CXC chemokine, IL-8. Indeed, this work demonstrates that the delivery of recombinant human IL-8, together with Shigella infection of the colonic epithelial surface, causes an acute colitis characterized by a stron...
Journal of Immunological Methods, 1997
A competitive RT-PCR method that permits reliable quantification of minute amounts of reverse-tra... more A competitive RT-PCR method that permits reliable quantification of minute amounts of reverse-transcribed mouse lymph node mRNA is described. Using this technique, an absolute number of cDNA copies ranging from 10 3 to 10 5 can be determined, with a precision superior to 25%. The standard templates described in the present study permit the quantitation Ž. of beta-actin, IFN gamma, IL2, IL3, IL4, IL10, IL12 p40 subunit , TGF beta 1, inducible nitric oxide synthase, ELAM-1, VCAM-1, and ICAM-1 mouse mRNA. The expression of a particular transcript is normalized to an arbitrary number of actin transcripts. The standard templates and wild-type cDNA have nearly identical sequences, but they can be distinguished by unique restriction sites. Known amounts of these standard templates, are co-amplified with serial dilutions of the cDNA derived from the mRNA of interest. Oligonucleotide primer pairs possessing 3 X octamers found infrequently in the mouse Ž y6. Ž genome F 0.26 = 10 are used to amplify sequences, chosen to contain no GC stretches longer than 8 PCRaree. Ž. software Griffais et al., 1991. Samples of each PCR product are digested separately with restriction endonucleases unique either for the wild-type or the standard amplicon. The quantitation of the test product and the standard product is easily carried out following their electrophoresis in an ethidium bromide-stained agarose gel. q 1997 Elsevier Science B.V.
Journal of Biological Chemistry, 2000
Exposure of human pulmonary microvascular endothelial cells (HPMECs) to phorbol 12-myristate 13-a... more Exposure of human pulmonary microvascular endothelial cells (HPMECs) to phorbol 12-myristate 13-acetate (PMA) leads to the increase of prostaglandin H synthase (PGHS)-2 protein levels. Under same conditions and according to its constitutive nature, no significant variation of PGHS-1 protein was noted. The elevation of the intracellular cAMP rate is known to enhance PGHS-2 levels through a protein kinase A pathway in various cells. To determine whether the extracellular cAMP also regulates the inducible expression of PGHS, cultured HPMECs were exposed to cAMP alone or in combination with PMA. The PMA-induced PGHS-2 protein was attenuated by the extracellular cAMP. In addition, PGHS-2 activity evaluated through 6-keto-PGF1␣ generation, which was enhanced by PMA was inhibited by extracellular cAMP. Furthermore, in HPMEC medium, PMA-induced PGHS-2 expression was accompanied by the generation of a transferable activity (TA) able to abolish platelet aggregation. This resulting TA was dependent from PGHS-2 pathway, because NS-398, a selective inhibitor of PGHS-2, suppressed its production. The inhibitory TA released by treated HPMECs was also prevented by extracellular cAMP. The specific protein kinase A (PKA) inhibitor blocked the extracellular cAMP effect on both PMA-induced 6-keto-PGF1␣ synthesis and inhibitory TA generation, suggesting the involvement of PKA signaling at the outer surface of HPMECs. Accordingly, we established, in phosphorylation experiments, the presence of an endothelial ectoprotein kinase activity, able to phosphorylate the synthetic substrate kemptide in a cAMP-dependent mode. Reverse transcription-polymerase chain reaction analysis showed that PMA-induced PGHS-2 mRNA was markedly reduced by extracellular cAMP. Together, these findings provide the first experimental evidence that extracellular cAMP is able to reduce HPMEC PGHS-2 expression in terms of mRNA, protein, and enzyme activity through an ecto-PKA pathway. In addition, they outline the potential role of endothelial PGHS-2 in the limitation of platelet activation during inflammatory processes.
European Journal of Immunology, 1996
This report examines the effects of recombinant murine interleukin-10 (rmIL-10) on antigen-induce... more This report examines the effects of recombinant murine interleukin-10 (rmIL-10) on antigen-induced beta-hexosaminidase, leukotriene (LT)C4 and cytokine release from mouse bone marrow-derived mast cells (BMMC). BMMC sensitized to hapten-monoclonal IgE directed against dinitrophenol-bovine serum albumin (DNP-BSA) and challenged with 10 ng/ml DNP-BSA generated beta-hexosaminidase and LTC4-like material which was followed by tumor necrosis factor-alpha (TNF-alpha) and granulocyte-macrophage colony-stimulating factor (GM-CSF) mRNA expression and protein release. Incubation of BMMC with 1-100 ng/ml rmIL-10 inhibited cytokine generation, without affecting beta-hexosaminidase and LTC4-like material release. TNF-alpha, but not GM-CSF mRNA expression, was also diminished in rmIL-10-treated BMMC, suggesting that down-regulation of cytokine production by rmIL-10 involves different mechanisms. These results identify a novel biological action of IL-10 as an inhibitor of cytokine production by stimulated mast cells.
European Journal of Immunology, 1998
We have previously shown that mouse bone marrow-derived mast cells (BMMC) can process and present... more We have previously shown that mouse bone marrow-derived mast cells (BMMC) can process and present immunogenic peptides to CD4 T cells. Here, we report on a T cell-dependent MHC class II-mediated mast cell activation resulting in IL-4 transcription and protein release. Presentation of optimal doses of ovalbumin peptide 323-339 resulted in IL-2 production by a specific T cell hybridoma and increase in IL-4 mRNA transcription in mast cells. IL-4 mRNA transcription increased by 200-fold in mast cells treated in IL-3/IL-4/granulocyte-macrophage colony-stimulating factor (high presenters) whereas only a tenfold increase or no increase were obtained with IL-3/IL-4/IFN-gamma- or IL-3-treated mast cells (low presenters), respectively. Induction of IL-4 mRNA transcription in purified mast cells by direct ligation of MHC class II molecules, using anti-I-A and anti-I-E-coated beads, indicates that MHC class II molecules are critical in this signaling pathway. However, when compared to T cells, anti-MHC class II-coated beads were less efficient, indicating a potential role of accessory molecules in this mast cell activation process. IgE-independent IL-4 production by mast cells as a result of cognate interaction with CD4 T cells could be critical for the development of type 2 responses. This novel mechanism may contribute to the induction and/or amplification of specific IgE-mediated allergic responses.
DNA and Cell Biology, 1995
The Variable Coding Sequence (VCS) multigene family of Rattus norvegicus, is composed of at least... more The Variable Coding Sequence (VCS) multigene family of Rattus norvegicus, is composed of at least 10 members, and shows extensive evolutionary divergence in the protein-coding region. Three members of the VCSA subclass, have been characterized: one of them, the VCSA1 gene mainly expressed in the submandibular gland (SMG) encodes the prohormone-like protein, SMR1-W1. As VCSA-related genes have not been detected in Mus musculus, the VCSA genes subclass is presumed to have recently emerged. To study the evolution of this subclass, we have looked for VCSA genes in a closely related species, Rattus rattus. By Northern analysis, we demonstrate that VCS-related mRNAs are present in the SMG, and that the level of VCSA mRN A accumulation is approximately equal in both sexes. By contrast, in R. norvegicus, males accumulate about 3,000 times more VCSA 1 mRN A than females. Using total SMG mRN A, an almost full-length cDNA, homologous to the cDNA of the R. norvegicus VCSA1 gene, was cloned by reverse transcriptase polymerase chain reaction (RT-PCR). The putative corresponding SMR1-VA1 protein is 146 amino acids long and presents the features characteristic of a secreted protein, with a potential signal peptide of 22 amino acids in the amino-terminal portion. The presence of potential processing multibasic sites suggests that small peptides could be generated (particularly a hexapeptide: Arg-Gln-His-Asn-Leu-Arg), as in the case of the SMR1-VA1 protein of R. norvegicus. From Southern blot analysis there appears that species-species modifications of VCSA gene copy number have occurred; R. rattus contains a greater VCSA1 copy number than R. norvegicus (two or three and one, respectively). demonstrated that SMR1-VA1 is the precursor of an undecapeptide, a hexapeptide, and a pentapeptide, all containing the Gln-His-Asn-Pro sequence. The SMR1-derived peptides are present in saliva; the hexapeptide is also released into the bloodstream following stimulation by catecholamines (Rougeot et al, 1994). The SMR1-VA1 protein is encoded by a gene (VCSA1) spanning 4.7 kb and containing 3 exons (Rosinski-Chupin and Rougeon, 1990a). This gene belongs to a novel family encompassing at least 10 members in R. norvegicus. In this species as in Mus musculus, the characterized members show extensive evolutionary divergence in the protein-coding region (Courty et al., 1994; Tronik Le Roux et al, 1994). The gene family has been named VCS, for variable coding sequence, and the genes have been grouped into different subclasses. In R. norvegicus, the B subclass is represented by the VCS-ßl gene (now named VCSB1) encoding a proline-rich protein (PR-VB1) similar to
Clinical & Experimental Allergy, 2003
Airway hyper-responsiveness (AHR), chronic airway inflammation and predominance of the T helper t... more Airway hyper-responsiveness (AHR), chronic airway inflammation and predominance of the T helper type-2 (Th2; IL-4, IL-5, IL-13) over the Th1 (IL-2, IFN-gamma) immune response are hallmarks of asthma. Alveolar macrophages (AM) are the most numerous cells in the airway lumen, where they represent the first immune cell population encountered by inhaled antigens. AM act as antigen-presenting cells (APC) and they release various soluble mediators and enzymes. AM thus play a prominent role in the modulation of the local immunity in airways. In allergic airways, AM have been implicated in the pathogenesis of inflammation by promoting the Th2 versus the Th1 cytokine patterns. Infections with attenuated bacteria or challenges with bacterial products may involve AM. Such stimuli have been shown to potentially restore the Th1/Th2 balance in asthmatic airways, but they also induce the release of inflammatory mediators. We investigated the response of AM when stimulated by two preparations of non-proliferating Bacillus Calmette-Guérin (BCG). We evaluated the cytokine production by AM from BP2 and C57BL/6 mice when cultured with heat-killed (HK) and extended freeze-dried (EFD) BCG. We then investigated in vivo the release of soluble factors in the airway lumen of mice after instillation of these BCG preparations. Finally, we studied the profile of cytokine transcripts in the lung of mice pre-treated with BCG and then challenged with ovalbumin (OVA). HK BCG induced the production of both TNF-alpha and IL-12, and did not prevent high levels of Th2 cytokine transcripts. In contrast, EFD BCG induced a response dominated by the production of IL-12, with no later over-expression of Th2 cytokine transcripts. Our results show that EFD BCG induce the release of the Th1-promoting cytokine IL-12 by AM, without the deleterious effects of HK BCG. These data suggest that EFD BCG may be considered as a potential novel treatment to restore the Th1/Th2 imbalance in asthma.
British Journal of Pharmacology, 1998
Our previous work demonstrated that bacterial lipopolysaccharide (LPS), administered by aerosol, ... more Our previous work demonstrated that bacterial lipopolysaccharide (LPS), administered by aerosol, induced tumour necrosis factor (TNF‐α) synthesis leading to the infiltration of neutrophils into mice lungs. The treatment of animals with prostaglandin E2 or dibutyryl cyclic AMP impaired both processes. In this study, the target cell for LPS and the modulation by cyclic AMP of TNF‐α production and neutrophil recruitment were investigated. One hour after inhalation of 2 ml of 0.3 mg ml−1 LPS, TNF‐α levels measured by an ELISA method increased in the bronchoalveolar lavage fluid (BALF) of BALB/c mice, reaching a maximal level 3 h after inhalation. The immunocytochemistry assay demonstrated that 1 h after inhalation, 21.2% of alveolar macrophages collected in the BALF were immunopositive for TNF‐α. When mice were pretreated, i.p., with 20 mg kg−1 rolipram, a selective inhibitor of phosphodiesterase type 4, TNF‐α levels in the BALF were significantly reduced and only 7.3% of alveolar macro...