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Biomedical subjects

G Cordier

Publications and source records attributed to G Cordier.

At least 19 recordsLinked to original sources
PubMed2006

Telomerase activation in a model of lung adenocarcinoma.

Ovine pulmonary adenocarcinoma (OPA) is a lung cancer strikingly similar to the pneumonic-type mixed invasive adenocarcinoma with a predominant bronchioloalveolar component in humans. Telomerase activity in OPA and the potential involvement of the kinase Akt in telomerase activation and regulation of cell proliferation were investigated. Lung tissues were collected from sheep with a histopathological diagnosis of OPA or controls. Epithelial cell cultures were derived in vitro from lung tissues. Telomerase activity was evaluated using the telomeric repeat amplification protocol method. Phosphorylation of Akt was detected by Western blotting. Telomerase activity was significantly higher in OPA lung tissues compared to control lung tissues. A high telomerase activity was detected in eight out of 12 (67%) primary cell cultures derived from tumours. A high level of expression of phosphorylated Akt was found in 10 out of 27 (37%) tumours, with abolition of Akt activation in response to epidermal growth factor stimulation demonstrated in primary cell cultures derived from tumours. Telomerase activation takes place in ovine pulmonary adenocarcinoma tumour cells and may be partly attributable to Akt activation. Telomerase may inhibit cellular senescence and contribute to the accumulation of tumour cells in mixed adenocarcinoma with a bronchioloalveolar component. Further work is necessary to identify alternative signalling pathways of telomerase activation in tumours.

Adenocarcinoma↗
PubMed2001

Establishment and characterisation of ovine blood monocyte-derived cell lines.

Studies of the important functions in host defense assured by macrophages, both as functional elements and as potential targets for intracellular pathogens, are often inhibited by the lack of a source of large numbers of uniform, well-characterised cells. To address this lack for ovine studies, we have established cell lines from spontaneously-proliferating adherent mononuclear cells from sheep blood. Eight such lines which have been continuously cultured for over 400 passages have phagocytic activities and cytochemical characteristics indicating that they retain the nature of mononuclear phagocytes. They display typical functional membrane proteins such as CD14, Fc receptors and MHC class II. Such cells can facilitate in vitro studies of pathogen-monocyte interactions and can furnish copious amounts of cells for transfer experiments.

Acid Phosphatase↗
PubMed2000

Viral RNA in middle ear mucosa and exudates in patients with chronic otitis media with effusion.

OBJECTIVE: To evaluate viral and cytokine signaling correlates of the persistent inflammation associated with chronic otitis media with effusion (OME). DESIGN: Prospective study. METHOD: Reverse transcriptase-polymerase chain reaction targeting RNA viruses frequently associated with OME (respiratory syncytial virus and parainfluenza virus type 3, the proinflammatory cytokines interleukin 8 and interleukin 1beta, and RANTES [regulated upon activation, normal T cell expressed and secreted]) was performed on mucosal biopsy samples and on samples of the liquid and cellular compartments of inflammatory exudates obtained from 26 children (49 ears) with infected middle ears. Ribonucleic acid extracted from rapidly frozen samples was reverse transcribed by Moloney murine leukemia virus reverse transcriptase and amplified for 35 cycles using previously validated primers. Amplicons were evaluated by molecular size after agarose gel electrophoresis with ethidium bromide. RESULTS: Most children had evidence of the presence of an RNA virus in at least one specimen. Respiratory syncytial virus was present in 40% and parainfluenza virus type 3 in 8% of effusions. Interleukin 8 messenger RNA was present in 21% of inflammatory exudates but never in cells from the mucosal biopsy samples. CONCLUSIONS: Our data support a viral contribution to the cause of OME and suggest that the inflammatory cytokines observed derive more from cells in the inflammatory exudate than from those in the middle ear mucosa.

Biopsy↗
PubMed1999

Conserved sequence motifs involving the tat reading frame of Brazilian caprine lentiviruses indicate affiliations to both caprine arthritis-encephalitis virus and visna-maedi virus.

The sequence variation in small ruminant lentiviruses from Brazilian herds of milking goats was sampled in a representative region of the pol gene and in a region including the entire tat open reading frame. Clones were amplified from cDNA derived from virus produced in vitro using primers targetting conserved sequences of the pol gene. Iterative sequencing of clones indicated that animals from two herds in the Minas Gerais area were infected by a caprine arthritis-encephalitis virus (CAEV)-like virus and that individual animals carried variant virus populations. Sequences derived from an infected goat from a herd in Pernambuco showed no nucleic acid variation and were distant from the CAEV-type sequence but marginally closer to ovine visna-maedi virus (VMV) sequences. Sequences amplified from a region including the tat gene, amplified with a common upstream primer within the vif coding region and different downstream primers because of the local divergence between CAEV- and VMV-type sequences, confirmed the affiliation of the Minas Gerais sequences to CAEV and indicated that the Pernambuco isolate was indeed related to VMV, which had not previously been reported to cause natural caprine infection. The overlap between the vif and tat open reading frames clearly distinguished between CAEV-like small ruminant lentiviruses, which shared eight common nucleotides, and the VMV group, where the overlap was reduced to a single base; the final adenine of the vif terminator (TAA) is the initial adenine of the presumptive tat initiator codon. This may be useful for epizoological tracing of the origin of outbreaks.

Amino Acid Sequence↗
PubMed1998

Visna-maedi virus induces interleukin-8 in sheep alveolar macrophages through a tyrosine-kinase signaling pathway.

The mechanisms leading to the severe lung damage seen in some sheep naturally infected with the visna-maedi virus, and to pulmonary lesions in other lentiviral diseases, appear to involve the recruitment of large numbers of uninfected inflammatory cells. Only a few alveolar macrophages from experimentally infected lambs express virus, but high levels of interleukin (IL)-8 mRNA are present in the macrophage population. In vitro infection with visna-maedi virus at low multiplicity of alveolar macrophages from uninfected sheep also strongly induced the expression of IL-8 mRNA and the accumulation of IL-8 in the extracellular medium. An initial peak of IL-8 mRNA expression at 3 or 6 h after infection was followed by a fall, then a more persistent expression lasting at least 48 h after infection. The early peak was accompanied by expression of mRNA for IL-1beta, and a possible rise in tumor necrosis factor alpha (TNFalpha) mRNA, although this was frequently elevated in uninfected ovine alveolar macrophages. Interestingly, these events occurred identically in cells treated with non-infectious heat-treated virus, suggesting that interaction between viral components and cellular membrane receptors could suffice for both early and late IL-8 induction. The level of IL-8 mRNA induced by treatment with live or inactivated virus could be severely reduced by pretreatment of the macrophages with genistein but not with staurosporine, suggesting the involvement of a tyrosine-kinase signaling pathway. The early induction of IL-1beta and possibly of TNFalpha may explain the occurrence of a later persistent expression of IL-8 mRNA through an autocrine mechanism.

Animals↗
PubMed1997

Alveolar macrophages from sheep naturally infected by visna-maedi virus contribute to IL-8 production in the lung.

Sheep naturally infected by visna-maedi virus often develop a chronic interstitial lung disease characterized by an alveolitis comprising lymphocytes, neutrophils and macrophages. The alpha chemokine interleukin-8 (IL-8) was detected in cell free bronchoalveolar lavage fluid from naturally infected animals, confirmed by RT-PCR, presenting typical lesions of maedi and elevated total alveolar cell counts. No detectable IL-8 was found in the fluid obtained from uninfected animals. IL-8 concentration in alveolar fluid is correlated with alveolar neutrophil counts. Bronchoalveolar lavage cells from infected animals were found to contain a large amount of IL-8 mRNA and may contribute to IL-8 production. In situ hybridization showed that macrophages were the predominant cell type expressing IL-8 mRNA. Sustained production of IL-8 by alveolar macrophages during visna-maedi infection could suffice for neutrophil attraction to the alveoli, and may contribute to the development of lesions.

Animals↗
PubMed1996

CD4 mAbs prevent progression of alloactivated CD4+ T cells into the S phase of the cell cycle without interfering with early activation signals.

Knowing that several CD4 mAbs may delay allograft rejection in the absence of circulating CD4+ lymphocyte depletion in vivo, we investigated the mechanisms whereby CD4 mAbs can interfere with the development of alloreactive T cells in the mixed lymphocyte reaction (MLR). In agreement with previous reports, CD4 mAbs of different species (mouse, rat, humanized), isotypes (IgG1, IgG2a, and IgG2b) and different epitope specificities decreased 3H-TdR incorporation in MLR, using monocyte-depleted or CD4+ T lymphocyte-enriched blood mononuclear cells as responders. Those effects were achieved at nonsaturating mAb concentration and were still demonstrable upon delayed addition of CD4 mAbs. However, CD4 mAbs decreased neither the number of blast cells nor the expression of CD25 (the alpha chain of IL-2 receptor), indicating that initial activation events leading to blast transformation were not affected. Determination of cytokine gene expression by non competitive quantitative RT-PCR and measurement of protein concentration in supernatants demonstrated that CD4 mAbs did not decrease IFN-gamma induced by alloactivation. However IL-2 concentration was decreased in all supernatants whereas IL-2 mRNA expression, only slightly decreased at 24 hr, and dropped after 72 hr. IL-5 and IL-10 mRNAs, equally expressed by stimulated or nonstimulated responder cells, were not affected by CD4 mAbs. IL-4 mRNA was not detectable. Furthermore, addition of rIL-2, rIFN-gamma or rIL-4 did not overcome proliferation inhibition. The data provide a novel insight into the mechanisms of CD4 mAbs immunosuppresssion that associates a decrease of IL-2 expression with an IL-2 resistant blockade of the progression of activated CD4+ T cells from the G1 to the S phases of the cell cycle.

Antibodies, Monoclonal↗
PubMed1996

Histogenesis of the pulmonary lesions in the course of visna maedi virus-induced pneumonia.

The major characteristic lesion observed following spontaneous infection of sheep by the prototype lentivirus, maedi-visna virus (MVV), is a lymphocytic intestitial pneumonia. Similar lesions may be observed with variable frequency following infection of other species by pathogenic lentiviruses, for example in children infected by HIV-1. Further, lentivirus-induced lesions involving organs other than the lungs frequently involve a comparable cellular infiltration. The cellular composition of bronchoalveolar lavage specimens from naturally- or experimentally-infected sheep has been examined with a view to describing the pathological progression of lentivirus-induced lung lesions. The naturally-infected sheep presented advanced lesions typical of 'maedi', while the experimentally-infected newborn lambs permitted the study of early lesions which we refer to as 'pre-maedi'. In both cases there was a considerable infiltration of lymphocytes, predominantly CD8+ in maedi, but with nearly equal numbers of CD4+ cells in pre-maedi. A large proportion of the alveolar lymphocytes in spontaneous maedi, but not in experimentally-infected lambs, express high levels of MHC class II antigen, suggesting an activated phenotype. Activated macrophages, the chief target cells for MVV infection, are also present at this advanced stage of the disease suggesting the involvement of mediators such as IL-8 in the cellular interactions leading to the localization of particular lymphocyte sub-populations in the pulmonary parenchyma during lentiviral disease.

Animals↗
PubMed1995

Ovine aortic smooth muscle cells allow the replication of visna-maedi virus in vitro.

Visna-maedi virus induces in sheep an interstitial lung disease characterised by an accumulation of smooth muscle cells (SMC) or myomatosis. Infection by HIV-1 has been recently associated with disorders of the vessel-derived cells: primary pulmonary hypertension, coronary artery disease and smooth muscle tumors in humans. We hypothesized that, besides their regular targets (i.e. macrophages and lymphocytes), lentiviruses could infect smooth muscle cells. Smooth muscle cell cultures derived from ovine aorta were infected with visna-maedi virus strain K1514. The cultured cells were smooth muscle cells as demonstrated by their antigenic expression of alpha-actin and vimentin. The lentiviral infection of the smooth muscle cells was demonstrated by a typical cytopathic effect (syncytia), the expression of virus specific antigens, and the presence of genomic RNA detected by Northern blot analysis and RT PCR. The detection of a reverse transcriptase activity, the presence of viral RNA in supernatants of infected smooth muscle cells detected by RT PCR and their ability to infect ovine permissive fibroblasts demonstrated a productive infection. The ability of smooth muscle cells to be infected by lentiviruses may participate in the pathogenesis of the tissue damage associated with the lentiviruses such as myomatosis in sheep and vascular disease in humans.

Animals↗
PubMed1994

Sequencing of the ovine interleukin-8-encoding cDNA using the polymerase chain reaction.

The nucleotide (nt) sequence encoding the ovine homologue of interleukin-8 (IL-8) was determined. The mRNA is 1494-nt long with an ORF of 101 codons. The long 3' non-coding element contains several ATTTA repeats implicated in the swift turnover of other chemokine mRNAs. The encoded protein of 11 kDa before processing, and 9 kDa as mature protein, contains the Cys-Xaa-Cys motif common to alpha-chemokines, and has conserved amino acids (aa) at positions identified as receptor contact sites for IL-8. Identities with other published IL-8 aa sequences are: dog, 91%; pig, 87%; rabbit, 84%; human, 78%; guinea pig, 69%. A 49% aa identity is also found with a chicken embryo fibroblast protein.

Amino Acid Sequence↗
PubMed1994

Lentivirus-induced interstitial lung disease: pulmonary pathology in sheep naturally infected by the visna-maedi virus.

Visna-maedi virus is a lentivirus that causes a chronic disease in sheep affecting, among other organs, the lungs. Interstitial pneumonitis is similar to that in man associated with the infection by the human immunodeficiency virus type-1. We have compared the pathological features of lungs of sheep naturally infected with visna-maedi virus with the results obtained from bronchoalveolar lavage and virus isolation. Semi-quantitative grading of the lesions was performed on 147 sheep lungs obtained from the slaughterhouse. Seventy-seven were macroscopically and histologically normal, 39 had typical lesions of interstitial lung disease (maedi), and 13 had minor lesions of the same type. Eighteen of the affected lungs were heavily infested with parasites. Of these parasite-infected lungs, 9 showed typical maedi lesions and 4 showed minor lesions; parasite infection had no obvious effect on the development of maedi. In keeping with pathological findings, bronchoalveolar lavage disclosed an alveolitis process in the maedi lungs with increased macrophage, lymphocyte and neutrophil numbers. Cytopathic virus was detected from alveolar macrophage coculture with fibroblasts more often from maedi lungs (10/12) than from normal lungs (9/39). Electron microscopy of bronchoalveolar lavage cocultures revealed typical lentiviral particles. Animals with minor lesions may be at an early stage of the disease.

Animals↗
PubMed1993

Early events in the experimental interstitial lung disease induced in sheep by the Visna-maedi virus.

Visna-maedi virus is a lentivirus closely related to the human immunodeficiency virus type I (HIV-I). During spontaneous infection of sheep by Visna-maedi virus an interstitial lung disease is observed. It is characterized by an alveolitis, peribronchovascular lymphoid nodules, alveolar wall thickening and myomatosis. In order to decipher the pathology of this lentiviral infection we have induced this disease in colostrum-deprived newborn lambs.

Animals↗
PubMed1992

Evidence for T-cell involvement during the acute phase of echovirus meningitis.

Little is known about the cellular immune response during the acute phase of enterovirus infection. This was studied in patients with echovirus meningitis by analysing changes in the lymphocyte subset distribution both in blood and in cerebrospinal fluid (CSF) and their stage of activation. A significant increase of whole T-cell and CD4+ T-cell counts was observed in CSF in parallel with a slight decrease of T-cell percentage in blood. Activation of the cellular immune response is supported by the observation of elevated neopterin levels in serum and CSF. However, the phenotypic markers of T-cell activation, IL-2 receptor (CD25), and HLA-DR antigens were not detected in blood or in CSF.

Adolescent↗
PubMed1992

Characterization of the lymphocytic alveolitis in visna-maedi virus-induced interstitial lung disease of sheep.

In order to investigate the contribution of lymphocytes to interstitial lung disease in animals with visna-maedi infection, we studied in parallel bronchoalveolar cells and lung tissue from slaughter-house animals (n = 29) and from colostrum-deprived lambs transtracheally inoculated with field isolates of visna-maedi virus (n = 9) or saline (n = 6). Lymphocyte subpopulations were identified in bronchoalveolar lavage by immunofluorescence and flow cytometry analysis and in lung tissue using indirect immunohistochemistry. In infected animals a lymphocytic alveolitis containing CD4 and CD8 lymphocytes was observed. Peribronchovascular lymphoid nodules comprise mostly CD4 lymphocytes. Alveolar lymphocytes of both subsets displayed increased expression of MHC class II antigens in animals with naturally occurring maedi but not in experimentally infected ones. A sequential process of lymphocyte attraction and activation is likely to occur in vivo as part of the alveolitis.

Animals↗
PubMed1990

Alteration of membrane phospholipid methylation by adenosine analogs does not affect T lymphocyte activation.

Membrane phospholipid methylation has been described during activation of various immune cells. Moreover recent data indicated modulation of immune cells functions by adenosine. As S-Adenosyl-methionine and S-Adenosyl-homocysteine are adenosine analogs and modulators of transmethylation reactions, the effects of SAH and SAM were investigated on membrane phospholipid methylation and lymphocyte activation. SAM (10(-5) M) was shown to induce the membrane phospholipid methylation as assessed by the 3H-methyl-incorporation in membrane extract. This effect was inhibited by SAH. In contrast SAM and SAH did not affect the phytohemagglutinin-induced proliferative response of peripheral blood mononuclear cells. SAH neither modified the early internalization of membrane CD3 antigens nor did it prevent the late expression of HLA-DR antigens on lymphocytes activated by phytohemagglutinin. These results indicate that in vitro alteration of phospholipid methylation does not affect subsequent steps of human T lymphocyte activation and proliferation.

Adenosine↗
PubMed1990

In vivo activation of alveolar macrophages in ovine lentivirus infection.

Sheep infected by visna-maedi virus, a lentivirus related to the human immunodeficiency virus, develop a chronic interstitial lung disease. Since monocyte/macrophages are known to be specifically infected by visna-maedi virus, we investigated the role of macrophages in the appearance of pulmonary lesions in animals with naturally occurring disease. Alveolitis in maedi leads to a doubling in bronchoalveolar lavage total cell counts and of macrophages as compared to normal sheep. A significant increase in the relative percentage of neutrophils was also observed, accompanied by an increased spontaneous release of neutrophil chemotactic activity by alveolar macrophages of diseased animals, suggesting that they may be activated. Macrophage activation is also demonstrated by the observation of a significant (x3) increase of spontaneous fibronectin release by alveolar macrophages from maedi lungs, and furthermore by the high level expression of major histocompatibility complex class II antigens on most of these cells. Thus viral infection, although restricted to a small population of macrophages, is able to modulate extensive activation of macrophages in the lung. Activated macrophages release mediators likely to play a role in the development of the alveolitis and the parenchymal desorganization. These findings may be relevant to our understanding of the mechanisms by which human immunodeficiency virus infection leads to pulmonary disease other than that caused by opportunistic infections.

Animals↗