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J F Nicolas

Publications and source records attributed to J F Nicolas.

At least 37 records · Page 2Linked to original sources
PubMed2000

Culture of dendritic cells from a nonlymphoid organ, the thyroid gland: evidence for TNFalpha-dependent phenotypic changes of thyroid-derived dendritic cells.

Because they are sparsely distributed in tissues, dendritic cells (DC) present in nonlymphoid organs are difficult to isolate. Only DC from skin and lung have been successfully studied in culture. The objective of the present work was to investigate the possibility of isolating and culturing DC from an endocrine organ, the thyroid gland, which is particularly susceptible to the development of autoimmune processes. The study was conducted on pig thyroid glands to have sufficient amounts of starting material. This choice required the characterization of immunological reagents capable of recognizing DC markers in the pig species. Using a discontinuous trypsinization procedure, a DC population representing 2% to 3% of the thyroid cell suspension was reproducibly obtained. Isolated DC quantitatively attached to tissue culture-treated dishes and segregated from thyrocytes. DC identified as cells expressing major histocompatibility complex class II molecules, the mannose receptor, and the S100 protein were found to have a high capacity to internalize labeled ligands, dextran, and mannosylated albumin. These cells had a phenotype of immature DC. Secondarily, a fraction of DC detached from culture dishes, and floating DC had low or no endocytic activity, a characteristic of mature DC. Treatment of DC/thyrocytes cocultures with tumor necrosis factor alpha (TNFalpha) activated the transformation of immature DC into mature DC. These data show that DC isolated from the thyroid gland can be maintained immature or activated to undergo maturation in primary culture. The procedure of cell isolation and culture should be adaptable to human thyroid tissue for in vitro analyses of DC-mediated immune responses.

Animals↗
PubMed2000

Different clonal dispersion in the rostral and caudal mouse central nervous system.

We have performed a systematic clonal analysis to describe the modes of growth, dispersion and production of cells during the development of the mouse neural system. We have used mice expressing a LaacZ reporter gene under the control of the neuron specific enolase promoter to randomly generate LacZ clones in the central nervous system (CNS). We present evidence for (1) a pool of CNS founder cells that is not regionalized, i.e. give descendants dispersed along the entire A-P axis, (2) an early separation between pools of precursors for the anterior and posterior CNS and (3) distinct modes of production of progenitors in these two domains. More specifically, cell growth and dispersion of the progenitors follow a relatively coherent pattern throughout the anterior CNS, a mode that leads to a progressive regionalization of cell fates. In contrast, cell growth of progenitors of the SC appears to involve self-renewing stem cells that progress caudally during regression of the mode. Therefore, at least part of the area surrounding the node is composed of precursors with self-renewing properties and the development of the trunk is dependent on pools of stem cells regressing from A to P. Taken together with our analysis of the cell growth changes associated with neuromere formation (Mathis, L., Sieur, J., Voiculescu, O., Charnay, P. and Nicolas, J. F. (1999) Development 126, 4095-4106), our results suggest that major transitions in CNS development correspond to changes in cell behavior and may provide a link between morphogenesis and genetic patterning mechanisms (i.e. formation of the body plan).

Animals↗
PubMed1999

Cytotoxicity is mandatory for CD8(+) T cell-mediated contact hypersensitivity.

Contact hypersensitivity (CHS) is a T cell-mediated skin inflammation induced by epicutaneous exposure to haptens in sensitized individuals. We have previously reported that CHS to dinitrofluorobenzene in mice is mediated by major histocompatibility complex (MHC) class I-restricted CD8(+) T cells. In this study, we show that CD8(+) T cells mediate the skin inflammation through their cytotoxic activity. The contribution of specific cytotoxic T lymphocytes (CTLs) to the CHS reaction was examined both in vivo and in vitro, using mice deficient in perforin and/or Fas/Fas ligand (FasL) pathways involved in cytotoxicity. Mice double deficient in perforin and FasL were able to develop hapten-specific CD8(+) T cells in the lymphoid organs but did not show CHS reaction. However, they did not generate hapten-specific CTLs, demonstrating that the CHS reaction is dependent on cytotoxic activity. In contrast, Fas-deficient lpr mice, FasL-deficient gld mice, and perforin-deficient mice developed a normal CHS reaction and were able to generate hapten-specific CTLs, suggesting that CHS requires either the Fas/FasL or the perforin pathway. This was confirmed by in vitro studies showing that the hapten-specific CTL activity was exclusively mediated by MHC class I-restricted CD8(+) T cells which could use either the perforin or the Fas/FasL pathway for their lytic activity. Thus, cytotoxic CD8(+) T cells, commonly implicated in the host defence against tumors and viral infections, could also mediate harmful delayed-type hypersensitivity reactions.

Animals↗
PubMed1999

T-cell repertoire analysis in chronic plaque psoriasis suggests an antigen-specific immune response.

Psoriasis is a chronic inflammatory cutaneous disease of unknown etiology. Activation of T cells is thought to play a major role in the pathophysiology of psoriasis. In order to gain insight into the nature of the antigen (superantigen or nominal protein antigen) involved in psoriatic lesions, we have used a RT-PCR method to analyze the frequency of the 24 T cell receptor V beta chain (TCRBV) subfamilies and the size of the antigen-binding region (CDR3), using the immunoscope assay, in skin lesions of patients with chronic plaque-type psoriasis. Semi-quantitative analysis showed that no significant difference in V beta subfamily usage could be detected in T lymphocytes infiltrating lesional skin as compared to blood lymphocytes. Alternatively, determination of the size distribution of the CDR3 of all the V beta subfamilies revealed only in psoriatic skin a marked TCR oligoclonality defined by the presence in 3 to 5 V beta subfamilies of a single predominant CDR3 size which was associated with a unique V beta-J beta combination. Identical patterns of CDR3 length and V beta-J beta combination profiles were found in symetrical lesional sites from two psoriatic patients. This type of skewed CDR3 size profile is reminiscent of a local stimulation of T lymphocytes by nominal protein antigens. These data suggest that T lymphocytes infiltrating plaque-type psoriatic skin comprise expansions of oligoclonal T cells in response to stimulation by an antigen present in the skin.

Adult↗
PubMed1999

[LagoZ and LagZ, 2 genes depleted of CpG dinucleotides, derived from the LacZ gene for the study of epigenetic control].

The methylation of 5'CpG 3' dinucleotides within genes creates potential targets for protein complexes that bind to methylated DNA sequences and to histone deacetylases (MBD-HDAC). This can lead to transcriptional repression by modification of chromatic. To test the importance of this repression in vivo and to determine when during development these epigenetic controls are placed on genes, two novel genes have been engineered by directed mutagenesis of the CpG-rich LacZ gene that are depleted of (LagZ) or completely lacking (LagoZ) CpG sequences. We report that the expression (transcriptional and translational) of the three genes is indistinguishable in transient assays in cleaving mouse embryos. Therefore, the complete absence of CpG sequences within three kilobases of coding sequence is compatible with its maintenance in the nucleus and with its expression. These molecules can now be used to study the ontogenesis of the CpG-dependent repressive system in intact organisms.

Acetylation↗
PubMed1999

Successive patterns of clonal cell dispersion in relation to neuromeric subdivision in the mouse neuroepithelium.

We made use of the laacz procedure of single-cell labelling to visualize clones labelled before neuromere formation, in 12.5-day mouse embryos. This allowed us to deduce two successive phases of cell dispersion in the formation of the rhombencephalon: an initial anterior-posterior (AP) cell dispersion, followed by an asymmetrical dorsoventral (DV) cell distribution during which AP cell dispersion occurs in territories smaller than one rhombomere. We conclude that the general arrest of AP cell dispersion precedes the onset of morphological segmentation and is not imposed by the interface between adjacent rhombomeres. This demonstrates a major change in the mode of epithelial growth that precedes or accompanies the formation of neuromeres. We also deduced that the period of DV cell dispersion in the neuroepithelium is followed by a coherent growth phase. These results suggest a cell organization on a Cartesian grid, the coordinates of which correspond to the AP and DV axis of the neural tube. A similar sequence of AP cell dispersion followed by an arrest of AP cell dispersion, a preferential DV cell dispersion and then by a coherent neuroepithelial growth, is also observed in the spinal cord and mesencephalon. This demonstrates that a similar cascade of cell events occurs in these different domains of the CNS. In the prosencephalon, differences in spatial constraints may explain the variability in the orientation of cell clusters. Genetic and clonal patterning in the AP and DV dimensions follow the same spatial sequence. An interesting possibility is that these successive patterns of cell growth facilitate the acquisition of positional information.

Animals↗
PubMed1999

Contact dermatitis II. Clinical aspects and diagnosis.

Contact dermatitis (CD) is an altered state of skin reactivity induced by exposure to an external agent. "Eczema" and "dermatitis" are often used synonymously to denote a polymorphic pattern of inflammation of the skin characterized, at least in its acute phase, by erythema, vesiculation and pruritus. Substances that induce CD after single or multiple exposures may be irritant or allergic in nature. The clinical presentation may vary depending on the identity of the triggering agent and the reactivity of the subject, but in all cases the lesions are primarily confined to the site of contact. According to the mechanism of elicitation, the following types of contact reactions may be distinguished: (1) allergic contact dermatitis (ACD); (2) irritant contact dermatitis (ICD); (3) phototoxic and photoallergic contact dermatitis, and (4) immediate type contact reactions. The present review will focus on allergic contact dermatitis. ACD is the clinical presentation of contact sensitivity in humans. The pathophysiology of the contact sensitivity reaction has been reviewed in a preceding issue of this journal [1].

Dermatitis, Allergic Contact↗
PubMed1999

[Biological diagnosis of immediate drug allergy. Comparative study of histamine liberation tests and CD63 expression by flow cytometry (preliminary results)].

The diagnosis of drug allergy is mainly based upon a detailed clinical history, positive skin tests (ST) and detection of specific IgE. In case of discrepant results, in vitro investigations to identify the responsible drug are needed. The histamine release test (HR) is usually performed. Nevertheless, its clinical benefit remains controversial. Flow cytometric methods (FCM) for the study of allergen induced basophil activation have been recently described. We assessed their usefulness in the diagnosis of drug allergy in comparison to HR results. Eighteen patients were included and 24 drugs (mainly antibiotics and muscle relaxant drugs) were tested. On the basis of clinical signs, 15 patients were classified as allergic (18 drugs). Sensitivity of biological investigations were found as follows: 71% (ST), 71% (FCM) and 24% (HR). This suggests performing FCM rather than HR. In addition, HR is more costly in terms of both reagents and laboratory technician time. Thus, CD63 detection by FCM seems to be a more reliable method in the clinical immunology laboratory. Additional data are needed to validate these preliminary results (sensitivity and specificity, especially in atopic patients) and to assess the interest of the method to investigate drug allergy due to other types of molecules.

Antigens, CD↗
PubMed1998

[Physiopathology of eczema].

Eczema is a skin inflammatory reaction mediated by antigen-specific T cells. Two main disorders belong to this group: contact dermatitis and atopic dermatitis. The pathophysiological mecanisms involved in both disorders are similar and include, at the cellular level, three elements: the antigen (hapten or environmental antigen), antigen-presenting cells belonging to the group of dendritic cells and antigen-specific T cells. The Langerhans cell responsible for antigen handling and presentation to specific T cells appears to play a central role for the generation of the inflammatory reaction.

Antigen-Presenting Cells↗
PubMed1998

Dual role of dendritic cells in the induction and down-regulation of antigen-specific cutaneous inflammation.

We have previously reported that contact sensitivity (CS) to dinitrofluorobenzene (DNFB) in C57BL/6 mice was mediated by MHC class I-restricted CD8+ T cells and down-regulated by MHC class II-restricted CD4+ T cells. In this study, we analyzed the contribution of dendritic cells (DC) in the induction of these two T cell subsets endowed with opposite functions. Hapten-pulsed skin- and bone marrow-derived DC, obtained from either normal C57BL/6 mice or from MHC class II (I+ II-) and MHC class I (I- II+)-deficient mice, were tested for their ability to prime normal mice for CS to dinitrofluorobenzene. Expression of MHC class I molecules by transferred DC was mandatory both for the induction of CS and for the generation of hapten-specific CD8+ T cells in lymphoid organs. I+ II- DC were as potent as I+ II+ DC in priming for CS, demonstrating that activation of effector CD8+ T cells can occur independently of CD4+ T cell help. I- II+ DC could not immunize for CS, although they could sensitize for a delayed-type hypersensitivity reaction to protein Ags. Moreover, I- II+ DC injected simultaneously with cutaneous sensitization down-regulated the inflammatory response, suggesting that hapten presentation by MHC class II molecules could prime regulatory CD4+ T cells. These results indicate that DC can present haptenated peptides by both MHC class I and class II molecules and activate Ag-specific CD8+ effector and CD4+ regulatory T cell subsets, concurrently and independently.

Animals↗
PubMed1998

IgE antibodies in sera from patients with bullous pemphigoid are autoantibodies preferentially directed against the 230-kDa epidermal antigen (BP230)

Bullous pemphigoid (BP) is unique among autoimmune skin diseases in which a high serum IgE level has been detected. We sought to determine the antigenic specificity of these IgE antibodies in 39 BP sera by immunofluorescence microscopy, immunoblot, and ELISA. The patient's sera contained IgG antibodies to 230-kDa (BP230) (n = 20), 180-kDa (BP180) (n = 9), and both BP230 and BP180 (n = 10) antigens. Serum IgE levels varied from 29 to 5000 kIU/L (mean +/- SD, 856 +/- 1426 kIU/L), among which sera containing IgG antibodies to BP230 had an IgE level on average 4.3 times higher than anti-BP180 sera. IgE antibodies in 18 sera were found to be autoantibodies reactive either with an epidermal component of basement membrane zone by immunofluorescence microscopy on 1 M NaCl-split skin or with a 230-kDa antigen by immunoblots of cultured human keratinocytes. The 230-kDa epidermal antigen recognized by IgE antibodies comigrated with the BP230 as labeled by a specific human monoclonal antibody. IgE anti-BP230 antibodies in patients' sera were always associated with IgG autoantibodies. No sera contained IgE antibodies to BP180 or to any other epidermal or dermal antigens as verified by immunoblot and ELISA. A good correlation was found between the presence of IgE circulating autoantibodies and the level of serum IgE (P < 0.004). IgE antibodies to BP230, like IgG autoantibodies, were mapped primarily to the C-terminal end of the protein, as they labeled rBP55, a BP230 recombinant protein encoded by a cDNA for the C-terminal end of BP230.

Autoantibodies↗
PubMed1998

Relief of a repressed gene expression state in the mouse 1-cell embryo requires DNA replication.

In the mouse, transcriptional permissiveness is established in the fertilized egg prior to the activation of zygotic genes at the 2-cell stage. Therefore, gene inactivity initiated at the end of gametogenesis results from a complex process, involving more than an inhibition of the basal transcriptional apparatus. We have examined the ability of the first intron (I1) of the human hypoxanthine phosphoribosyl transferase gene, which functions as an enhancer in embryonic stem cells, to activate a reporter gene when placed proximally to or at a distance from the HSV-tk promoter, or when integrated into the mouse genome as part of a stable transgene. In microinjected embryos, I1 functions as an enhancer sequence; however, its competence for long-range activation appears only after the late 1-cell stage and depends on the first DNA replication. Moreover, activation of microinjected transgenes from proximal enhancers occurs in the late 2-cell embryo and in the male pronucleus of 1-cell embryos blocked for DNA replication; whereas, for integrated transgenes, proximal enhancer activity is subject to position effects in the 2-cell embryo and first occurs at the 2- or 4-cell stage, but only after completion of DNA replication. Therefore, the absence of long-range activation and a non-permissive genomic state (the relief of which both depend on DNA replication), together with an inactive transcriptional apparatus, appear to converge to prevent any gene activity in the 1-cell embryo. We propose that the embryo exploits the process of DNA replication to relieve the transcriptionally repressive state that was initially established to fulfil two purposes: (1) to arrest maternal gene expression in the maturing oocyte and (2) to protect the unicellular egg and 1-cell embryo from premature differentiation. Reactivation of gene expression by DNA replication would therefore serve to coordinate cell proliferation and differentiation in the preimplantation embryo.

Animals↗
PubMed1997

CD4 monoclonal antibody administration in atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory dermatosis that probably involves a dysregulated activation of helper T cells, type 2 (Th2 cells). Severe refractory AD can be controlled by cyclosporine treatment. OBJECTIVE: We attempted to determine whether short-term CD4 monoclonal antibody (mAb) therapy could improve severe AD in adults. METHODS: The CD4 mAb, B-F5, was infused over 2 days in three patients with severe refractory AD and, for control purposes, in two patients with severe psoriasis. RESULTS: Administration of B-F5 was well tolerated, despite moderate first dose side effects. Clinical improvement was observed in two patients. In the third patient, a dramatic worsening occurred between 8 and 30 days after treatment, associated with an increased percentage of activated CD4+, CD25+, HLA-DR+, and CD45RO+ cells and peripheral blood eosinophilia. The same CD4 mAb administered to two patients with severe psoriasis induced marked clinical improvement of the lesions. CONCLUSION: Although CD4 mAb infusion may be potentially useful in the treatment of AD, the risk of aggravating the Th1/Th2 imbalance in AD should be considered in the design of future protocols.

Adult↗
PubMed1997

Linear IgA bullous dermatosis with IgA antibodies exclusively directed against the 180- or 230-kDa epidermal antigens.

This study describes the presence in sera from patients with linear IgA bullous dermatosis (LABD) of IgA antibodies specific for 230- or 180-kDa epidermal antigens. Of 11 patients' sera with IgA antibodies reactive with the epidermal antigens obtained from cultured keratinocytes, 6 sera recognized the 230-kDa antigen and co-migrated with the polypeptide recognized by a human monoclonal antibody against the 230-kDa bullous pemphigoid antigen (BPAgl). Five sera recognized the 180-kDa antigen and co-migrated with the polypeptide stained by a polyclonal antibody to the 180-kDa bullous pemphigoid antigen (BPAg2). None of these LABD sera contained IgG antibodies reactive with the basement membrane zone antigens and none labeled a 97-kDa epidermal antigen or a 290-kDa dermal antigen. Immunoaffinity-purified IgA antibodies from the 230 kDa band further reacted with the epidermal side of the skin basement membrane zone. Epitope mapping with rBP55, a fusion protein containing the C-terminal end of BPAg1, suggested that the major antigenic epitopes for LABD and BP antibodies on the 230-kDa antigen are different. Only one serum with IgA antibodies was found to label rBP55, contrasting with nine of ten BP sera reacting with this protein. Our study demonstrates the presence of an exclusive IgA response against the 230- or 180-kDa antigens in a subset of patients with LABD.

Adult↗
PubMed1997

Retrospective clonal analysis of the cerebellum using genetic laacZ/lacZ mouse mosaics.

Analysis of lacZ neuronal clones in the mouse cerebellum demonstrates genealogical independence of the primary and secondary germinal epithelia (PGE and SGE) from early development. PGE precursors and their neuronal descendants are organised into two polyclonal groups of similar sizes that exhibit parasagittal patterning and generally respect the midline. The relationship between these two groups cannot be traced back in time to less than 80 independent cells, which were probably recruited following a period of non-coherent growth that distributes unrelated cells into distinct territories of the neural tube. A lateromedial clonal organisation is observed in the mature cerebellum, suggesting the existence of many small parasagittal domains of clonal restriction and/or of cell dispersion in the rostrocaudal but not in the mediolateral dimension. The organisation is orthogonal with respect to the cellular organisation in the neural tube as is the genetic organisation. Cellular and genetic patterning of the cerebellum therefore share similarities. A possible hypothesis is that distinct cell behaviours create the different clonal domains observed in this study and that the cellular and genetic organisation of the cerebellum are coordinated.

Animals↗