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Biomedical subjects

B M Wittig

Publications and source records attributed to B M Wittig.

29 records · Page 2Linked to original sources
PubMed2000

Identical T-cell expansions in the colon mucosa and the synovium of a patient with enterogenic spondyloarthropathy.

Intestinal T lymphocytes activated by antigen are suspected to play a key role in enterogenic spondyloarthropathies (SpA). Therefore, we aimed to identify and functionally characterize T-cell clones that are coexpanded in the intestinal mucosa and the synovium. Colon, peripheral blood, and synovium of a patient with enterogenic SpA were screened for clonal T-cell expansions by TCRB-CDR3 length analysis and sequencing. T-cell clones expanded in vivo were isolated from archived synovial cells by targeted T-cell cloning and characterized for phenotype, cytokine production, and antigen specificity. The synovial TCRBV18(+) T-cell repertoire of the patient was dominated by 2 CD8(+) T-cell clones using related CDR3. Both clones were expanded throughout the colon and were present in the peripheral blood. Upon in vitro stimulation with PDB/ionomycin, they showed predominantly interferon gamma and interleukin (IL)-4 but also tumor necrosis factor alpha and IL-10 production and did not specifically lyse autologous T-cell blasts, B-cell lines, or other autologous or allogeneic target or CD1d-transfected cells. These findings strongly suggest that T lymphocytes activated by antigen in the intestinal mucosa contribute to joint inflammation in enterogenic SpA by recognition of antigens specific for the inflamed synovium.

ATP-Binding Cassette Transporters↗
PubMed2000

Modulation of gastrointestinal inflammation by chimeric proteins in experimental models.

Conventional drug therapy in patients with chronic gastrointestinal inflammation is clinically effective in the majority of patients. However, in a relevant group of patients with highly active disease refractory to conventional drugs and for patients with severe side effects new therapeutic strategies are necessary. An advanced understanding of the immune mechanisms underlying chronic diseases resulted in the possibility to use chimeric proteins, in which the variable domains of an immunoglobulin are replaced by extracellular domains of cell surface molecules or cytokines for specific immunomodulation. The immunomodulating effects of chimeric proteins such as CTLA-4-IgG, interleukin-10-IgG, IL-2-IgG or tumour necrosis factor (TNF)-receptor IgG have been proven beneficial in a variety of in vitro and in vivo models of chronic gastrointestinal inflammation and autoimmune diseases. It thus seems likely that genetically engineered fusion proteins targeting specific elements of the immune response may become an essential element in new clinical treatment protocols.

Animals↗
PubMed1999

Expression and regulation by interferon-gamma of the membrane-bound complement regulators CD46 (MCP), CD55 (DAF) and CD59 in gastrointestinal tumours.

The membrane-bound complement inhibitors CD46 (membrane cofactor protein), CD55 (decay-accelerating factor) and CD59 (protectin) protect tumour cells against lysis by activated complement. In this study, a total of 14 (3 gastric, 3 colonic and 8 pancreatic) gastrointestinal tumour cell lines were examined for the expression of CD46, CD55 and CD59 with respect to the regulatory efficacy of interferon-gamma (IFN-gamma). The effects of IFN-gamma on mRNA and protein expression levels of CD46, CD55 and CD59 were evaluated by Northern blot hybridisation, RT-PCR, flow cytometry and immunostaining. In unstimulated cell lines, CD46 and CD59 transcripts were expressed at comparable levels, whereas the basal expression of CD55 mRNA was heterogeneous. The complement inhibitor proteins were detected in all cell lines using specific antibodies. Additional immunohistochemical stainings of gastrointestinal tissue specimens supported these findings. IFN-gamma evoked a weak induction of certain transcripts in a subset of the cell lines. Upregulation of protein expression was only observed in HT29 cells for CD55 and CD59 and was accompanied by a marked increase of the corresponding transcripts. We conclude that membrane-bound complement inhibitors are broadly expressed in gastrointestinal tumour cells and vary in their susceptibility to IFN-gamma. Thus, they may be involved in tumour escape mechanisms in gastric, pancreatic and colorectal cancer.

Antigens, CD↗
PubMed1998

Detection of the DCC gene product in normal and malignant colorectal tissues and its relation to a codon 201 mutation.

Protein expression of the putative tumour-suppressor gene DCC on chromosome 18q was evaluated in a panel of 16 matched colorectal cancer and normal colonic tissue samples together with DCC mRNA expression and allelic deletions (loss of heterozygosity, LOH). Determined by a polymerase chain reaction (PCR)-LOH assay, 12 of the 16 (75%) cases were informative with LOH occurring in 2 of the 12 cases. For DCC mRNA, transcripts could be detected in all analysed normal tissues (eight out of eight) by RT-PCR, whereas 6 of the 15 tumours were negative. DCC protein expression, investigated by immunohistochemistry using the monoclonal antibody 15041 A directed against the intracellular domain, was homogeneously positive in all normal tissue samples. In tumour tissues, no DCC protein was seen in 11 out of 16 samples (69%). For the DCC codon 201, we found a loss of a wild-type codon sequence caused by mutation or LOH in at least 8 out of 15 cases (53%) compared with the corresponding normal tissue. DCC protein expression was undetectable in eight of the nine tumours missing both wild-type codons. Only one of the five tumours with retained DCC protein expression had no detectable wild-type codon 201. In addition, 9 out of 15 normal tissue specimens were mutated in codon 201. In two out of three cases with homozygous wild-type codons in peripheral blood lymphocyte (PBL) DNA, mutations were already observed in the tumour adjacent normal colonic mucosa. We conclude that DCC immunostaining should be introduced in the clinicopathological routine because of its strong correlation with the known prognostic markers 18q LOH and mutation of codon 201.

Blotting, Southern↗
PubMed1997

Soluble E-selectin enhances intercellular adhesion molecule-1 (ICAM-1) expression in human tumor cell lines.

E-selectin mediates neovascularization via its soluble form, while its membrane-bound form initiates binding of tumor cells to vascular endothelium. Therefore, it was studied whether soluble E-selectin regulates further adhesion molecules on tumor cells. In tumor cells but not in related nonmalignant cells, intercellular adhesion molecule (ICAM)-1 expression was strikingly increased from 5 to 68% positive cells by in vitro inoculation of a recombinant E-selectin-IgG1 within 24 h, as analyzed by flow cytometry. The absence of changes in the expression of vascular cell adhesion molecule, integrin ligands (CD11a, CD18, integrin alpha 4), and sialyl-Lewis X indicates a specific effect of soluble E-selectin on ICAM-1. A cell adhesion assay revealed that the enhanced adhesion on T-cells to tumor cells mediated by soluble E-selectin-induced ICAM-1 expression was at a maximum after a 12-h incubation period. Therefore, ICAM-1 regulation on tumor cells might be a mechanism of immune escape.

Cell Adhesion↗
PubMed1996

alpha(1,3)Fucosyltransferase expression in E-selectin-mediated binding of gastrointestinal tumor cells.

E-selectin recognizes the oncofetal antigen sialyl-Lewis X, which is highly expressed in adenocarcinoma. Five alpha(1,3)fucosyltransferases (FT) have been cloned that confer cell-surface expression of sialyl-Lewis X on transfected cells. We show here that 12/18 gastrointestinal-tumor cell lines bind specifically to immobilized E-selectin and that in sialyl-Lewis-X-positive cells binding is inhibited with a monoclonal antibody against sialyl-Lewis X. Using RT-PCR, we determined the expression of the alpha(1,3)fucosyltransferases III, IV, V, VI and VII in gastrointestinal tumor cells. Transcripts of FT IV and FT VII are abundantly expressed in all tested cells. Therefore no single fucosyltransferase could be correlated with the expression of sialyl-Lewis X and the ability of the tumor cells to bind to E-selectin. The data suggest that in gastrointestinal-tumor cells sialyl-Lewis X is necessary but not sufficient for E-selectin binding.

Base Sequence↗
PubMed1996

Elevated serum E-selectin in patients with liver metastases of colorectal cancer.

E-selectin, an endothelial cell adhesion molecule, mediates the initial step of leucocyte adhesion to activated vascular endothelium. The soluble isoform of E-selectin promotes angiogenesis in rat cornea. In the present study, we investigated whether leucocyte adhesion and angiogenesis are also involved in tumour progression and metastasis of colorectal cancer. Therefore, we determined the level of circulating soluble E-selectin in serum samples of 38 patients with colorectal cancer; 20 patients with non-metastatic and 18 patients with metastatic disease. Median levels of soluble E-selectin were found to be significantly higher in metastatic tumour disease (88.7 ng/ml, range 25-203 ng/ml) than in healthy controls (34.9 ng/ml, range 15-59 ng/ml, P = 0.01), in patients with primary tumours or with local recurrences (39.5 ng/ml, range 22-100 ng/ml). Furthermore, there was no correlation with the serum level of C-reactive protein, fibrinogen or tumour necrosis factor alpha suggesting that the elevation of E-selectin is independent of inflammation in tumour patients. Therefore, we propose that elevated soluble E-selectin may reflect increased neovascularisation in metastatic tumour tissue.

Adult↗
PubMed1996

Activity of the DNA repair protein O6-methylguanine-DNA methyltransferase in human tumor and corresponding normal tissue.

The DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) is a main determinant of resistance of cells towards the cytostatic effect of N-nitrosoureas. Here we report the activity of MGMT in different types of human tumors. Colorectal tumors showed the highest mean of MGMT activity (481 +/- 258 fmol/mg protein) followed by ovarian tumors (437 +/- 291 fmol/mg), breast (306 +/- 204 fmol/mg), testicular (299 +/- 179 fmol/mg), and brain tumors (55 +/- 44 fmol/mg). Only in breast and brain tumors were MGMT-deficient samples found, with a frequency of 3 and 5%, respectively. No significant difference in mean MGMT activity was observed between breast tumors of grading I, II, and III. For brain tumors there was a tendency of MGMT to decline with increasing grading. Breast and colorectal carcinomas were compared with the corresponding normal tissue obtained from the same patient. The data showed for 11 out of 12 pairs of breast tissue and for 13 out of 15 pairs of colorectal tissue that MGMT activity in the tumor was equal to or, more frequently, higher than the activity found in the corresponding normal tissue. Thus, it appears that in these groups of tumors, increase of MGMT activity during tumor formation and progression is the rule rather than the exception.

Brain Neoplasms↗
PubMed1993

CEA-immunoscintigraphy with 99m-technetium correlates with tumour cell differentiation in colorectal cancer.

The clinical usefulness of immunoscintigraphy with the monoclonal anti-CEA (carcinoembryonic antigen) antibody BW431/26, directly labelled with 99m-Technetium in targeting colorectal carcinomas was investigated in 43 patients. In addition, tumour cell grading and CEA-expression were examined immunohistochemically. Best imaging results were obtained in pelvic tumour lesions (sensitivity 80%). Tumour grading correlated with radioimmunoimaging, well differentiated tumours being detectable at a higher rate (P = 0.09). Immunoscintigraphy preceded the findings of conventional diagnostic methods in 3 patients. In 4 cases immunoscintigraphy was decisive for patients management. Therefore, immunoscintigraphy with 99m-Technetium is valuable in directing patients management if conventional diagnostic methods remain undecisive.

Adult↗
PubMed1990

[Immunoscintigraphy in colorectal cancers from the viewpoint of the gastroenterologist].

In the last decade radioimmunoscintigraphy developed from an experimental approach to a clinically useful method. First promising results were obtained with Technetium-99m labelled murine monoclonal antibodies against carcinoembryonic antigen (CEA). Routine clinical application is restricted to colorectal carcinoma at the moment. Radioimmunoscintigraphy is recommended in case of recurring disease when conventional methods are ineffective or doubtful, especially in the pelvic region. The availability of monoclonal antibodies to new tumor-associated antigens will extend the spectrum to other gastrointestinal tumors. The possibility to generate recombinant humanized monoclonal antibodies and antibody fragments are encouraging new perspectives. These developments and the use of biological immune response modifiers to increase antigen expression could provide means to consider radioimmunotherapy of gastrointestinal cancers.

Antibodies, Monoclonal↗