Biomedical subjects

Vianney Ortiz-Navarrete

Publications and source records attributed to Vianney Ortiz-Navarrete.

6 recordsLinked to original sources

PubMed2006

Macrophage-activation inhibitor factor from L5178Y murine lymphoma and formation of hepatic abscesses in BALB/c mice.

BACKGROUND: Normal mice are naturally resistant to hepatic abscesses produced by Listeria monocytogenes. A macrophage-activation inhibitor factor (MAIF) isolated from the cell-free ascitic fluid of L5178Y lymphoma-bearing mice inhibited the lipopolysaccharide-induced production of nitric oxide (NO) by the macrophages. Because macrophages are also involved in the immune response towards L. monocytogenes, the present study had the objective of investigating whether MAIF was also capable of allowing L. monocytogenes to form hepatic abscesses. METHODS: BALC/c mice were inoculated intrahepatically with 5 x 10(5) bacteria. Experimental groups were treated daily with subcutaneous or intraperitoneal doses of 0, 1, 5 or 10 microg of MAIF/g of body weight. One dose was applied before inoculating bacteria and the remaining three doses 24, 48, and 72 h after inoculating bacteria. The development of hepatic abscess was analyzed 24 h after the last administration of MAIF. RESULTS: All treated mice (but not controls) developed hepatic abscess showing no differences regarding MAIF administration route. CONCLUSIONS: These results suggest a possible MAIF in vivo inhibition of NO macrophage production that allows L. monocytogenes hepatic abscess development in mice.

Animals↗

PubMed2005

Human class-I restricted T cell associated molecule is highly expressed in the cerebellum and is a marker for activated NKT and CD8+ T lymphocytes.

We have previously reported the characterization of a novel immunoglobulin supergene family member, designated class-I MHC-restricted T cell associated molecule (CRTAM). Here we further characterize human CRTAM and find that it is highly expressed in the cerebellum, notably in Purkinje neurons. We identify CRTAM as a new member of the nectin-like (Necls) family and find significant expression of Necl-2 (IGSF4), a protein known to bind CRTAM and another member of the nectin superfamily, in the cerebellum. These findings suggest that CRTAM/Necl-2 binding may contribute to neuronal interactions. We also show that, in the immune system, CRTAM expression is restricted to activated class-I MHC-restricted T cells, including NKT and CD8 T cells. CRTAM represents one of the most highly expressed surface markers of activated human CD8 T cells and NKT cells, suggesting it may have diagnostic uses in various human viral and autoimmune diseases.

Amino Acid Sequence↗

PubMed2005

Survival of Salmonella enterica serovar Typhimurium within late endosomal-lysosomal compartments of B lymphocytes is associated with the inability to use the vacuolar alternative major histocompatibility complex class I antigen-processing pathway.

Gamma interferon (IFN-gamma)-activated macrophages use an alternative processing mechanism to present Salmonella antigens to CD8(+) T lymphocytes. This pathway involves processing of antigen in a vacuolar compartment followed by secretion and loading of antigenic peptides to major histocompatibility complex class I (MHC-I) molecules on macrophage cell surface and bystander cells. In this study, we have shown that B lymphocytes are not able to process Salmonella antigens using this alternative pathway. This is due to differences in Salmonella enterica serovar Typhimurium-containing vacuoles (SCV) when comparing late endosomal-lysosomal processing compartments in B lymphocytes to those in macrophages. The IFN-gamma-activated IC21 macrophage cell line and A-20 B-cell line were infected with live or dead Salmonella enterica serovar Typhimurium. The SCV in B cells were in a late endosomal-lysosomal compartment, whereas SCV in macrophages were remodeled to a non-characteristic late endosomal-lysosomal compartment over time. Despite the difference in SCV within macrophages and B lymphocytes, S. enterica serovar Typhimurium survives more efficiently within the IFN-gamma-activated B cells than in activated macrophage cell lines. Similar results were found during in vivo acute infection. We determined that a lack of remodeling of late endosomal-lysosomal compartments by live Salmonella infection in B lymphocytes is associated with the inability to use the alternative MHC-I antigen-processing pathway, providing a survival advantage to the bacterium. Our data also suggest that the B lymphocyte late endosome-lysosome environment allows the expression of Salmonella virulence mechanisms favoring B lymphocytes in addition to macrophages and dendritic cells as a reservoir during in vivo infection.

Animals↗

PubMed2004

Detection of antibodies against a human papillomavirus (HPV) type 16 peptide that differentiate high-risk from low-risk HPV-associated low-grade squamous intraepithelial lesions.

A nonapeptide (16L1) was derived from the human papillomavirus type 16 (HPV-16) major capsid protein and tested for detection of potential cross-reactive serum IgG and cervical IgA antibodies in low- and high-risk HPV-associated low-grade squamous intraepithelial lesions (LSIL) and cervical cancer patients by ELISA. The IgG response was similar in women with low-risk HPV-associated LSIL and controls (P=0.1). In contrast, more than 90 % of patients with high-risk HPV-associated LSIL were seropositive. Although tumours from cancer patients were all positive for the presence of high-risk HPV DNA, the level of seropositivity decreased significantly in this group (P<0.0001). Cervical IgA antibodies were also detected in a significantly high proportion of women with high-risk HPV-associated LSIL compared with controls. However, the proportion of IgA-positive patients was lower than the proportion of IgG seropositives. In conclusion, the 16L1 peptide appears to be a high-risk type-common epitope that induces cross-reactive antibodies in high-risk, but not low-risk, HPV-associated LSIL patients, allowing differentiation of high- and low-risk infected women at this stage of infection.

Adult↗

PubMed2004

Two Salmonella OmpC K(b)-restricted epitopes for CD8+-T-cell recognition.

We report the identification of two peptides from Salmonella OmpC porin that can bind to major histocompatibility complex class I K(b) molecules and are targets of cytotoxic T lymphocytes from Salmonella-infected mice. These peptides are conserved in gram-negative bacterial porins and are the first Salmonella porin-specific epitopes described for possible CD8(+)-T-cell elimination of infected cells.

Animals↗

PubMed2003

A Salmonella typhi OmpC fusion protein expressing the CD154 Trp140-Ser149 amino acid strand binds CD40 and activates a lymphoma B-cell line.

CD154 is a type II glycoprotein member of the tumour necrosis factor (TNF) ligand family, which is expressed mainly on the surface of activated T lymphocytes. The interaction with its receptor CD40, plays a central role in the control of several functions of the immune system. Structural models based on the homology of CD154 with TNF and lymphotoxin indicate that binding to CD40 involves three regions surrounding amino acids K143, R203 and Q220, and that strands W140-S149 and S198-A210 are critical for such interactions. Also, it has been reported that two recombinant CD154 fragments, including amino acid residues Y45-L261 or E108-L261 are biologically active, whereas other polypeptides, including S149-L261, are not. Therefore, we decided to construct a fusion protein inserting the W140-S149 amino acid strand (WAEKGYYTMS) in an external loop of the outer membrane protein C (OmpC) from Salmonella enterica serovar Typhi and assess its ability to bind CD40 and activate B cells. The sodium dodecyl sulphate-polyacrylamide gel electrophoresis demonstrated that the chimeric OmpC-gp39 protein conserved its ability to form trimers. Binding to CD40 was established by three variants of enzyme-linked immunosorbent assay, a direct binding assay by coating plates with a recombinant CD40-Fc protein and through two competition assays between OmpC-gp39 and recombinant CD154 or soluble CD40-Fc. Flow cytometry analysis demonstrated that OmpC-gp39 increased the expression levels of major histocompatibility complex II, CD23, and CD80, in Raji human B-cell lymphoma similarly to an antibody against CD40. These results further support that the CD154/CD40 interaction is similar to the TNF/TNF receptor. This is the first report of a bacterial fusion protein containing a small amino acid strand form a ligand that is able to activate its cognate receptor.

Amino Acid Sequence↗