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J C Antoine

Publications and source records attributed to J C Antoine.

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

Accurate quantitation of Leishmania infection in cultured cells by flow cytometry.

BACKGROUND: Leishmaniases are major parasitic diseases caused by protozoans that are obligate intracellular parasites during the mammalian phase of their life cycle. Quantitation of experimental mammalian cell infections is usually performed by time-consuming microscopic examination. In this report a flow cytometry (FCM)-based assay suitable for studying in vitro infections by L.amazonensis is presented. METHODS: Intense fluorescence staining of the amastigote forms with a stage- and species-specific monoclonal antibody was obtained after permeabilization of both the host-cell cytoplasmic membrane and the parasitophorous vacuole membrane by saponin treatment. RESULTS: Upon flow cytometry (FCM) analysis, parasitized cells separated sharply from the auto-fluorescence of the mammalian host cells, giving the assay a high degree of sensitivity and specificity. Ninety to 98% of cells in the more fluorescent population harbored parasites visible by phase-contrast and UV-light microscopy, while no parasites were observed in more than 95% of the cells in the population with background fluorescence. Comparisons of the FCM results with those from microscope counting and analysis of various dilutions of parasitized cells confirmed the reliability of the method. CONCLUSIONS: The FCM assay provided rapid quantitation of Leishmania infection either in mouse macrophages, the natural host cell in murine leishmaniasis, or in Chinese hamster ovary (CHO) cells, a non-macrophage cell line proposed as an in vitro model for studying host-parasite interactions. The protocol described here should be adaptable to studies involving other parasites residing in nucleated cells.

Animals↗
PubMed2000

Differential expression of collapsin response mediator proteins (CRMP/ULIP) in subsets of oligodendrocytes in the postnatal rodent brain.

The family of collapsin response mediator protein/Unc-33-like protein (CRMP/Ulip), composed of four homologous members, is specifically and highly expressed in the nervous system during embryonic neuronal development and dramatically down-regulated in the adult. Members of this family have been proposed to be part of the semaphorins signal transduction pathway involved in axonal outgrowth. Here, we show by in situ hybridization and immunohistochemistry that CRMP2/Ulip2, and to a lesser extent CRMP3/Ulip4, are expressed in immature and mature oligodendrocytes, but not in astrocytes. Transcripts encoding the other CRMP/Ulip members are also detectable by RT-PCR in highly purified mature oligodendrocytes. Interestingly, in the adult, the protein CRMP2/Ulip2 is mainly detectable in subsets of oligodendrocytes distributed according to an increasing rostrocaudal gradient, with the largest number of positive cells being present in the brain stem and spinal cord. In cultures of highly purified oligodendrocytes, however, CRMP2/Ulip2 was detectable in all the cells. Addition of Sema3A in the culture medium completely inhibited the emergence of oligodendrocyte processes suggesting that, as in neurons, a Sema3A signaling pathway mediated via CRMP2/Ulip2 may be involved in the regulation of oligodendroglial process outgrowth.

Animals↗
PubMed2000

Macrophage subsets harbouring Leishmania donovani in spleens of infected BALB/c mice: localization and characterization.

The purpose of the current study was to characterize parasite-containing cells located in spleens of BALB/c mice infected with Leishmania donovani. In particular, expression of MHC class II molecules by these cells was examined to determine whether they could potentially act as cells capable of immunostimulating Leishmania-reactive CD4+ T lymphocytes. To this end, an immunohistological analysis of spleens taken at various time points after infection was undertaken. Using this approach, we observed, in the red pulp, the formation of small cellular infliltrates containing heavily infected macrophages that could be stained with the monoclonal antibodies MOMA-2 and FA/11. All of them expressed high levels of MHC class II molecules. Parasites were also detected in the white pulp, especially in MOMA-2+, FA/11+ and MHC class II+ macrophages of the periarteriolar lymphocyte sheath and in MOMA-2+ marginal zone macrophages. Infected cells were further characterized by fluorescence microscopy after their enrichment by adherence. All infected mononuclear cells recovered by this procedure could be stained with MOMA-2 and FA/11 and thus very probably belonged to the mononuclear phagocyte lineage. Furthermore, all of them strongly expressed both MHC class II as well as H-2M molecules, regardless of the time points after infection. Analysis of the parasitophorous vacuoles (PV) by confocal microscopy showed that these compartments were surrounded by a membrane enriched in lysosomal glycoproteins lamp-1 and lamp-2, in macrosialin (a membrane protein of prelysosomes recognized by FA/11) and in MOMA-2 antigen. About 80% of the PV also had MHC class II and H-2M molecules on their membrane. Altogether, these data indicate that in the spleens of L. donovani-infected mice, a high percentage of amastigotes are located in macrophages expressing MHC class II molecules and that they live in PV exhibiting properties similar to those of PV detected in mouse bone marrow-derived macrophages exposed to a low dose of interferon gamma (IFN-gamma) and infected in vitro.

Animals↗
PubMed2000

LdARL-3A, a Leishmania promastigote-specific ADP-ribosylation factor-like protein, is essential for flagellum integrity.

The small G protein-encoding LdARL-3A gene, a homologue of the human ARL-3 gene, was isolated from Leishmania donovani, and its protein product characterised. It is unique in the Leishmania genome and expressed only in the extracellular promastigote insect form, but not in the intracellular amastigote mammalian form, as shown by northern blots and western blots developed with a specific anti-C terminus immune serum. Indirect immunofluorescence microscopy revealed distinct labelled spots regularly distributed on the plasma membrane, including the part lining the flagellum and the flagellar pocket. By transfection experiments, it was found that wild-type LdARL-3A-overexpressing promastigotes reached higher densities in culture, but released significantly less secreted acid phosphatase in the extracellular medium than the parental strain. When LdARL-3A blocked under the GDP-bound 'inactive' form or with an inactivated potential myristoylation site was overexpressed, the cells displayed an apparent wild-type phenotype, but died earlier in the stationary phase; in contrast to parental cells, they showed a diffuse pattern of fluorescence labelling in the cytoplasm and on the cell membrane. Strikingly, when a constitutively 'active' form of LdARL-3A (blocked under the GTP-bound form) was overexpressed, the promastigotes were immobile with a very short flagellum, a slow growth rate and a low level of acid phosphatase secretion; the length of the flagellum was inversely proportional to mutant protein expression. We concluded that LdARL-3A could be an essential gene involved in flagellum biogenesis; it may provide new approaches for control of the parasite at the insect stage.

ADP-Ribosylation Factors↗
PubMed2000

[Anti-neuronal antibodies and central nervous system diseases: contribution to diagnosis and pathophysiology].

Antibodies against antigens found in the central nervous system have been evidenced in several neurological diseases. The most well-known are associated with paraneoplastic neurological diseases (Anti-Hu, Yo, Ri amphiphysin, Tr, CV2 and Ta antibodies). Some of these antibodies are specific for certain types of cancer or neurological syndromes and are highly useful diagnostic tools for the clinician. They have contributed to the hypothesis that these paraneoplastic neurological syndromes involve autoimmune cross reactions between tumoral and nervous system antigens. They are however most unlikely pathogenic on their own. Anti voltage-dependent calcium channel antibodies associated with Lambert-Eaton syndrome which is paraneoplastic in only 60 p. 100 of the cases are also observed in cases of paraneoplastic cerebellar atrophy. Anti-GAD antibodies are seen in non-paraneoplastic stiff man syndrome and in certain progressive cerebellar atrophies. Antibodies reacting with different glutamate receptors are detected in different neurological diseases including Rasmussen's encephalitis. Finally, antibodies are described in diverse conditions such as amyotrophic lateral sclerosis, Sydeham chorea or Gilles de la Tourette syndrome. The significance of the antibodies observed outside the context of paraneoplastic syndromes is not well understood, but the anti-GAD antibodies associated with progressive cerebellar disorders and autoimmune polyendocrinopathies could be an expression of the autoimmune nature of certain neurological degenerative processes affecting the central nervous system.

Antibodies↗
PubMed2000

[18F]fluorodeoxyglucose positron emission tomography in the diagnosis of cancer in patients with paraneoplastic neurological syndrome and anti-Hu antibodies.

The diagnosis of cancer is often difficult in patients with paraneoplastic neurological syndrome and anti-Hu antibodies. Fluorodeoxyglucose 18 positron emission tomography scanning is a highly sensitive and specific method to detect lung tumors. We investigated 15 patients with paraneoplastic neurological syndrome and anti-Hu antibodies. Radiological methods led to the diagnosis of cancer in 12 patients, and test results were negative in 3. Whole-body [18F]fluorodeoxyglucose positron emission tomography showed abnormal uptake in the mediastinum in these 3 patients in accordance with the expected location of the malignancy.

Aged↗
PubMed1999

Antiamphiphysin antibodies are associated with various paraneoplastic neurological syndromes and tumors.

BACKGROUND: Antiamphiphysin antibodies react with a 128-kd protein found in synaptic vesicles. They were first described in patients with paraneoplastic stiff-man syndrome and breast cancer, but studies suggest that they can also occur in patients with other tumors and neurological disorders. OBJECTIVE: To determine if antiamphiphysin antibodies are associated with various paraneoplastic neurological syndromes and tumors. PATIENTS AND METHODS: Of 2800 serum samples tested by routine immunohistochemical procedures on sections of paraformaldehyde-fixed rat brain for the detection of autoantibodies associated with paraneoplastic neurological syndromes, 5 were selected because of labeling suggestive of antiamphiphysin antibodies and subsequently confirmed by the results of Western blot analysis using recombinant amphiphysin protein. Controls consisted of 40 patients with various nonparaneoplastic neurological diseases; 101 patients with cancer but without paraneoplastic neurological syndrome; 9 patients with small cell lung cancer, anti-Hu antibodies, and paraneoplastic neurological syndrome; 3 patients with M2-type antimitochondrial antibodies but no neurological disorder; and 30 normal subjects. RESULTS: Of the 5 patients with antiamphiphysin antibodies, patient 1 had sensory neuronopathy, encephalomyelitis, and breast cancer; patient 2 had limbic encephalitis, and small cell lung cancer was detected in the mediastinum after 24 months of follow-up; patient 3 had encephalomyelitis and ovarian carcinoma; and patients 4 and 5 had Lambert-Eaton myasthenic syndrome and small cell lung cancer (patient 4 subsequently developed cerebellar degeneration). None of the 5 had stiffness. Two patients (Nos. 2 and 4) had antimitochondrial antibodies. The two patients (Nos. 4 and 5) with Lambert-Eaton myasthenic syndrome had antibodies directed against the voltage-gated calcium channel, and patient 2 subsequently developed anti-Hu antibodies. In the controls, antiamphiphysin antibodies were detected by Western blot analysis in 3 of 8 patients with anti-Hu antibodies, but in none of the other groups. CONCLUSIONS: These data indicate that antiamphiphysin antibodies are not specific for one type of tumor or one neurological syndrome and can be associated with other neural and nonneural antibodies. The simultaneous association of several antibodies in some patients suggests multimodal autoantibody production.

Aged↗
PubMed1999

Presentation of the Leishmania antigen LACK by infected macrophages is dependent upon the virulence of the phagocytosed parasites.

We have previously demonstrated that murine macrophages (Mphi) infected with Leishmania promastigotes, in contrast to Mphi infected with the amastigote stage of these parasites, are able to present the Leishmania antigen LACK (Leishmania homologue of receptors for activated C kinase) to specific, I-Ad-restricted T cell hybrids and to the T cell clone 9.1-2. These T cells react with the LACK (158-173) peptide, which is immunodominant in BALB/c mice. Here, we show that the level of stimulation of the LACK-specific T cell hybridoma OD12 by promastigote-infected Mphi is clearly dependent upon the differentiation state of the internalized parasites. Thus, shortly after infection with log-phase or stationary-phase promastigotes of L. major or of L. amazonensis, Mphi strongly activated OD12. The activity was transient and rapidly lost. However, under the same conditions, activation of OD12 by Mphi infected with metacyclic promastigotes of L. major or of L. amazonensis was barely detectable. At the extreme, Mphi infected with amastigotes were incapable to stimulate OD12. Thus, the presentation of LACK by infected Mphi correlates with the degree of virulence of the phagocytosed parasites, the less virulent being the best for the generation/expression of LACK (158-173)-I-Ad complexes. While the intracellular killing of the parasites appears to be an important condition for the presentation of LACK, it is not the only requisite. The partial or total destruction of intracellular L. amazonensis amastigotes does not allow the presentation of LACK to OD12. A preferential interaction of LACK (158-173) with recycling rather than newly synthesized MHC class II molecules does not explain the transient presentation of LACK by Mphi infected with log-phase or stationary-phase promastigotes because brefeldin A strongly inhibited the presentation of LACK to OD12. Taken together, these results suggest that virulent stages of Leishmania, namely metacyclics and amastigotes, have evolved strategies to avoid or minimize their recognition by CD4+ T lymphocytes.

Amino Acid Sequence↗
PubMed1999

[Mechanisms of paraneoplastic neurologic syndromes].

INTRODUCTION: Paraneoplastic neurological syndromes (PNS) refer to a set of neurological disorders associated with neuronal degeneration in some patients with systemic cancers. These disorders are not related to the tumor mass or metastasis. CURRENT KNOWLEDGE AND KEY POINTS: Evidence argues for an autoimmune reaction against tumor cells which expresses antigens normally present in neurons. A high percentage of patients with PNS harbors high titers of anti-neuronal autoantibodies in their serum and cerebrospinal fluid. In addition to their clinical interest in diagnosis and pathophysiology, these autoantibodies provide a unique opportunity to identify genes encoding previously undiscovered neuronal proteins which are also expressed by tumor cells. These "onconeural" antigens have been classified in four groups: neuromuscular junction proteins, nerve terminal/vesicle-associated proteins, neuronal RNA binding proteins, or neuronal signal transduction proteins. FUTURE PROSPECTS AND PROJECTS: All of these proteins would play a major role in the neuronal maturation and homeostasis, and for some of them in cellular proliferation. Better understanding of the exact role of these proteins would in turn permit better understanding of the mechanisms of neuronal degeneration and tumor cell proliferation in PNS.

Autoantibodies↗
PubMed1999

Ulip/CRMP proteins are recognized by autoantibodies in paraneoplastic neurological syndromes.

Anti-CV2 autoantibodies have recently been discovered in patients with paraneoplastic neurological diseases (PND). These disorders are associated with neuronal degeneration, mediated by autoimmune processes, in patients with systemic cancer. Anti-CV2 autoantibodies recognize a brain protein of 66 kDa developmentally regulated and specifically expressed by a subpopulation of oligodendrocytes in the adult brain. Here, we demonstrate that anti-CV2 sera recognize several post-translationally modified forms of Ulip4/CRMP3, a member of a protein family related to the axonal guidance and homologous to the Unc-33 gene product in Caenorhabditis elegans. The sequence of the human Ulip4/CRMP3 was determined and the gene localized to chromosome 10q25.2-q26, a region mutated in glioblastomas and containing tumour suppressor genes. The identification of the Ulip/CRMP proteins as recognized by anti-CV2 sera should provide new insights into the role of Ulip/CRMPs in oligodendrocytes and into pathophysiology of PND.

Amino Acid Sequence↗
PubMed1999

Carcinoma associated paraneoplastic peripheral neuropathies in patients with and without anti-onconeural antibodies.

OBJECTIVE: When to suspect a paraneoplastic disorder is a puzzling problem that has not recently been studied in a large series of patients referred for peripheral neuropathy. METHODS: From 422 consecutive patients with peripheral neuropathy, 26 were analysed who concomitantly had carcinoma but no tumorous infiltration, drug toxicity, or cachexia. Their clinical, pathological, and electrophysiological data were analysed according to the presence of anti-onconeural antibodies, the latency between presentation and cancer diagnosis, and the incidence of carcinoma in the corresponding types of neuropathy of the population of 422 patients. RESULTS: Seven patients (group I) had anti-onconeural antibodies (six anti-Hu, one anti-CV2) and 19 did not (groups IIA and B). In group I, subacute sensory neuropathy (SSN) was the most frequent but other neuropathies including demyelinating neuropathies were present. Patients in group II A had a short latency (mean 7.88 months), and a rapidly and usually severe neuropathy which corresponded in 11/14 to an established inflammatory disorder including neuropathy with encephalomyelitis, mononeuritis multiplex, and acute or chronic inflammatory demyelinating polyneuropathy (CIDP). Patients in group IIB had a long latency (mean 8.4 years) and a very chronic disorder corresponding in four of five to an axonal non-inflammatory polyneuropathy. In this population, the incidence of carcinoma occurring with a short latency was 47% in sensory neuronopathy, 1.7% in Guillain-Barré syndrome, 10% in mononeuritis multiplex and CIDP, and 4.5% in axonal polyneuropathy. CONCLUSIONS: Paraneoplastic neuropathies associated with carcinoma are heterogeneous disorders. Neuropathies occurring with a long latency with tumours probably resulted from a coincidental association. Neuropathies which occurred within a few years of the tumour evolved rapidly and corresponded mostly to inflammatory disorders. As dysimmune neuropathies are probably paraneoplastic in a limited number of cases, patients with these disorders should probably not be investigated systematically for carcinoma in the absence of anti-onconeural antibodies, except when the neuropathy is associated with encephalomyelitis and probably with vasculitis. Questions remain concerning CIDP.

Aged↗
PubMed1999

H-2M molecules, like MHC class II molecules, are targeted to parasitophorous vacuoles of Leishmania-infected macrophages and internalized by amastigotes of L. amazonensis and L. mexicana.

In their amastigote stage, Leishmania are obligatory intracellular parasites of mammalian macrophages, residing and multiplying within phagolysosomal compartments called parasitophorous vacuoles (PV). These organelles have properties similar to those described for the MHC class II compartments of antigen-presenting cells, sites where peptide-class II molecule complexes are formed before their expression at the cell surface. After infection with Leishmania amazonensis or L. mexicana, endocytosis and degradation of class II molecules by intracellular amastigotes have also been described, suggesting that these parasites have evolved mechanisms to escape the potentially hazardous antigen-presentation process. To determine whether these events extend to other molecules of the antigen-presentation machinery, we have now studied the fate of the MHC molecule H-2M in mouse macrophages infected with Leishmania amastigotes. At least for certain class II alleles, H-2M is an essential cofactor, which catalyses the release of the invariant chain-derived CLIP peptide from the peptide-binding groove of class II molecules and facilitates the binding of antigenic peptides. H-2M was detected in PV of mouse macrophages infected with various Leishmania species including L. amazonensis, L. mexicana, L. major and L. donovani. PV thus contain all the molecules required for the formation of peptide-class II molecule complexes and especially of complexes with parasite peptides. The present data indicate, however, that if this process occurs, it does not lead to a clear increase of SDS-stable compact (alpha)(beta) dimers of class II. In PV that contained L. amazonensis or L. mexicana, both class II and H-2M molecules often colocalized at the level where amastigotes bind to the PV membrane, suggesting that these molecules are physically associated, directly or indirectly, and possibly interact with parasite components. Furthermore, as class II molecules, H-2M molecules were internalized by amastigotes of these Leishmania species and reached parasite compartments that also contained class II molecules. Immunostaining of H-2M within parasites was increased by treatment of infected macrophages with the cysteine protease inhibitors Z-Phe-AlaCHN2 or Z-Phe-PheCHN2 or by incubation of the parasites with the same inhibitors before infection. These data thus support the idea that amastigotes of certain Leishmania species capture and degrade some of the molecules required for antigen presentation. To examine whether endocytosis of class II molecules by the parasites occurs through interactions with parasite components involving their peptide-binding groove, we made use of the fact that a large fraction of the class II molecules of H-2M(alpha) knock-out H-2(b) mice are occupied by the peptide CLIP and are unable to bind other peptides. We found that, in Leishmania-infected macrophages of these mutant mice, class II-CLIP complexes reached PV and were internalized by amastigotes. These results thus prove that endocytosis of class II molecules by amastigotes (1) is H-2M-independent and (2) does not necessarily involve the peptide-binding pocket of these molecules. Altogether, these data are compatible with an endocytic mechanism based on general properties shared by classical and non-classical class II molecules.

Animals↗
PubMed1998

Autoimmunity in paraneoplastic neurological disorders.

Antibodies to neuronal antigens are found in a range of different neurological disorders, both central and peripheral, and often indicate the presence of particular underlying tumours. This conference and workshop was an opportunity to discuss the clinical associations of these antibodies, the relevance of new antibody specificities, and to establish protocols for their detection.

Antibodies↗
PubMed1998

Paraneoplastic demyelinating neuropathy, subacute sensory neuropathy, and anti-Hu antibodies: clinicopathological study of an autopsy case.

A patient with anti-Hu antibodies, small-cell lung carcinoma, and autopsy-proven subacute sensory neuropathy had early slowing of motor and sensory conduction velocities. In the peripheral nerves, chronic demyelinating and remyelinating lesions with axonal degeneration were associated with an inflammatory reaction consisting of CD8+ T cells and CD68+ macrophages. On immunohistochemical testing, the patient's serum did not react with normal nerve, suggesting that the Hu proteins were not the target of the inflammatory reaction in the nerve.

Aged↗
PubMed1998

The biogenesis and properties of the parasitophorous vacuoles that harbour Leishmania in murine macrophages.

Leishmania are protozoan parasites that, as amastigotes, live in the macrophages of mammalian hosts within compartments called parasitophorous vacuoles. These organelles share features with late endosomes/lysosomes and are also involved in the trafficking of several major histocompatibility complex (MHC)-encoded molecules. Improved knowledge of the parasitophorous vacuoles may help clarify how these protozoa persist in their hosts.

Adaptation, Biological↗
PubMed1998

POP66, a paraneoplastic encephalomyelitis-related antigen, is a marker of adult oligodendrocytes.

Paraneoplastic neurological diseases are disorders of the central nervous system, associated with neuronal degeneration in patients with systemic cancer, but are not a direct result of the tumor mass or metastasis. The biological diagnosis of these syndromes is based mainly on the detection, in the patient's serum and cerebrospinal fluid, of autoantibodies (anti-Hu, anti-Yo, for example), suggesting an autoimmune origin for these disorders. Recently, we described novel autoantibodies (anti-CV2 autoantibodies) associated with paraneoplastic neurological disease, which recognize a 66 kDa brain protein. We named this antigen POP66, for Paraneoplastic Oligodendrocyte Protein of 66 kDa molecular weight, as in the adult human, rat, and mouse brain, it is specifically expressed by a subpopulation of oligodendrocytes. This cell type specificity was surprising given the fact that the cell loss in the brains of patients with anti-CV2 autoantibodies is neuronal. POP66-expressing oligodendrocytes are distributed along the longitudinal axis of the brain according to an increasing rostro-caudal gradient, with no positive oligodendrocytes being found in the forebrain and the greatest number found in the spinal cord. In addition, in transverse sections of the spinal cord, the distribution of POP66-positive oligodendrocytes follows an increasing dorsal-to-ventral gradient, which may be related to different oligodendrocyte precursor pools. In addition, the neuronal loss without demyelination seen in the brains of patients with anti-CV2 autoantibodies, together with the exclusive oligodendroglial expression of POP66 in the adult brain, raises the question of the possible involvement of POP66 in neuron survival via neuron/oligodendrocyte interactions.

Adult↗