Over-expression of interleukin 10 in mucosal T cells of patients with active ulcerative colitis

Ulcerative colitis (UC), a chronic inflammatory bowel disease, exhibits pronounced increase of T lymphocytes in the inflamed mucosa. To understand the role of intestinal T lymphocytes in the pathogenesis of UC their cytokine production in the mucosa was analysed. Intestinal T lymphocytes of UC, Crohn's disease and control patients were analysed for cytokine mRNA levels by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) directly after isolation without in vitro stimulation. Frequencies of cytokine positive cells were determined in UC and control colon by immunomorphometry. T lymphocytes in normal colon expressed interleukin (IL)-2, interferon (IFN)-gamma, tumour necrosis factor (TNF)-alpha and transforming growth factor (TGF)-beta1, but not IL-4, IL-5 or IL-10. In UC, a highly significant increase in IL-10 mRNA levels in T lymphocytes and an increased frequency of IL-10 positive cells was seen in colon. IL-10 mRNA levels were also elevated in T lymphocytes of the non-inflamed ileum and correlated with disease activity at both locations. CD4+ T lymphocytes were the major source of IL-10 mRNA. IL-2, IFN-gamma and TNF-alpha mRNA levels were decreased in colonic T lymphocytes, and virtually no IL-2, IFN-gamma, TNF-alpha or TGF-beta positive cells were detected in basal lymphoid aggregates. However, scattered IL-10 positive cells were found here. Lamina propria outside the aggregates contained IL-10-, IFN-gamma, TNF-alpha and TGF-beta but not IL-2 positive cells. T cells of UC patients did not express IL-4 or IL-5. Taken, together the data suggest a generalized activation of IL-10 producing CD4+ T cells along the intestine of UC patients. The local environment seems to determine the biological consequences of elevated IL-10.

beta-Defensin-3 and -4 in intestinal epithelial cells display increased mRNA expression in ulcerative colitis

mRNA expression of two recently described human beta-defensins (hBD-3 and hBD-4) in epithelial cells of normal small and large intestine and the impact of chronic intestinal inflammation on their expression levels was investigated. Intestinal specimens from patients with ulcerative colitis (UC), Crohn's disease (CD) and controls with no history of inflammatory bowel disease were studied. hBD-3 and hBD-4 mRNAs were determined in freshly isolated epithelial cells by real-time quantitative reverse transcription-polymerase chain reaction (QRT-PCR) and by in situ hybridization. The effect of proinflammatory cytokines on hBD-3 and hBD-4 mRNA expression in colon carcinoma cells was also investigated. Purified epithelial cells of normal small and large intestine expressed both hBD-3 and hBD-4 mRNA, with higher expression levels of hBD-3 mRNA. In situ hybridization revealed higher levels of mRNA expression in the crypt- compared to the villus/luminal-compartment. Interferon (IFN)-gamma, but not tumour necrosis factor (TNF)-alpha or IL-1beta, augmented hBD-3 mRNA expression. None of these agents stimulated hBD-4 expression. Colonic epithelial cells from patients with UC displayed a significant increase in hBD-3 and hBD-4 mRNA compared to epithelial cells of controls. In contrast, small intestinal epithelial cells from CD patients did not show increased expression levels compared to the corresponding control cells. Moreover, Crohn's colitis did not show increased expression of hBD-4 mRNA, while the data are inconclusive for hBD-3 mRNA. We conclude that the chronic inflammatory reaction induced in the colon of UC patients enhances hBD-3 and hBD-4 mRNA expression in the epithelium, whereas in CD this is less evident.

Characterization of two highly amyloidogenic mutants of transthyretin

The plasma protein transthyretin (TTR) has the potential to form amyloid under certain conditions. More than 50 different point mutations have been associated with amyloid formation that occurs only in adults. It is not known what structural changes are introduced into the structure of this otherwise stable molecule that results in its aggregation into insoluble amyloid fibrils. On the basis of calculations of the frequency of known mutations over the polypeptide, we have constructed two mutants in the D-strand of the polypeptide. These molecules, containing either a deletion or a substitution at amino acid positions 53-55, were unstable and spontaneously formed aggregates upon storage in TBS (pH 7.6). The precipitates were shown to be amyloid by staining with thioflavin T and Congo Red. Their ultrastructure was very similar to that of amyloid fibrils deposited in the vitreous body of patients with familial amyloidotic polyneuropathy type 1 with an amino acid replacement in position 30 (TTRmet30). Like amyloid isolated from the vitreous body of the eye, the amyloid precipitates generated from the TTR mutants exposed a trypsin cleavage site between amino acid residues 48 and 49, while plasma TTRmet30 isolated from amyloidosis patients as well as wild-type TTR only showed minor trypsin sensitivity. Our data indicate that the mutants we have constructed are similar to amyloid precursors or may share structural properties with intermediates on a pathway leading to amyloid deposits of plasma TTR.

A human epithelial cell line, intestine 407, can produce 5-hydroxyeicosatetraenoic acid and leukotriene B4

The present study was carried out to further characterize the role of non-inflammatory cells in the inflammatory process. More specifically, we have investigated whether human epithelial cells can generate inflammatory lipid mediators via activation of the 5-lipoxygenase pathway. The cells were stimulated with the calcium ionophore A23187 (5 microM) for different periods of time, after which the production of eicosanoids was determined by gradient reverse-phase high performance liquid chromatography (RP-HPLC) and rapid spectral detection, permitting continuous ultraviolet spectroscopy. In both non-prelabeled cells and cells prelabeled with [1-14C]arachidonic acid, cell stimulation for 30 min or more resulted in the production of two important 5-lipoxygenase products: 5-hydroxyeicosatetraenoic acid (5-HETE) and leukotriene B4 (LTB4). Stimulation for 15 min or less, however, led solely to the formation of 5-HETE. The identities of 5-HETE and LTB4 were confirmed by HPLC retention times and UV spectra, as well as by gas chromatography-mass spectrometry for 5-HETE and radioimmunoassay for LTB4. It can therefore be concluded that human epithelial cells in general can produce important inflammatory mediators, which suggests that epithelial cells may play a more active role in the inflammatory process than is normally assumed.

Mevalonate dependency of the early cell cycle mitogenic response to epidermal growth factor and prostaglandin F2 alpha in Swiss mouse 3T3 cells

Lovastatin (LOV), a hydroxy-methylglutaryl-coenzyme A (HMGCoA) reductase competitive inhibitor, blocks epidermal growth factor (EGF)- or prostaglandin F2 alpha (PGF2 alpha)-induced mitogenesis in confluent resting Swiss 3T3 cells. This inhibition occurs even in the presence of insulin, which potentiates the action of these mitogens in such cells. LOV exerts its effect in a 2-80 microM concentration range, with both mitogens attaining 50% inhibition at 7.5 microM. LOV exerted its effect within 0-8 h following mitogenic induction. Mevanolactone (10-80 microM) in the presence of LOV could reverse LOV inhibition within a similar time period. LOV-induced blockage of PGF2 alpha response is reflected in a decrease in the rate of cell entry into S phase. Neither cholesterol, ubiquinone, nor dolichols of various lengths could revert LOV blockage. In EGF- or PGF2 alpha-stimulated cells, LOV did not inhibit [3H]leucine or [3H]mannose incorporation into proteins, while tunicamycin, an inhibitor of N' glycosylation, prevented this last phenomenon. Thus, it appears that LOV exerts its action neither by inhibiting unspecific protein synthesis nor by impairing the N' glycosylation process. These findings strongly suggest that either EGF or PGF2 alpha stimulations generate early cell cycle signals which induce mevalonate formation, N' glycoprotein synthesis, and proliferation. The causal relationship of these events to various mechanisms controlling the onset of DNA synthesis is also discussed.

Intra-and inter-individual heterogeneity in exon 2 of the MDR1 gene in primary breast carcinoma and healthy individuals

Increased expression of P-glycoprotein, encoded by the MDR1 gene, is considered to be responsible for chemotherapy failure in a number of human cancers. Although it is clear that mutations in the MDR1 gene affect substrate specificity of the transporter in multidrug-resistant cell lines, scant interest has been directed at whether mutations have a unique clinical presentation. To address this question, we studied exon 2 of the MDR1 gene in 9 patients with primary breast carcinoma and 9 healthy controls using PCR and DNA sequence analysis. In order to reduce the possibility of nucleotide misincorporations introduced by Tag polymerase, sequencing of six subclones of each DNA specimen was performed. A mutation was seen as a substitution from G to A at position -1 in two patients and one control. An A to G nucleotide substitution giving rise to an amino acid substitution (Asn-->Asp) in codon 21 at the first potential N-glycosylation site of the P-glycoprotein was seen in primary tumors from four patients and in an axillar lymph node metastases from one of these patients. This mutation was also seen in two healthy individuals, which similar to the patients, both seem to be heterozygous for this MDR1 exon 2 allele. Three other mutations were also found in the patients; a substitution of A to G at position 23 and A to G at position 52 in the same patient and in another patient, G at position 42 was changed to A. However, the last three mutations were not confirmed by repeating analysis of the original genomic sample. The results revealed different distribution of a point mutation between various parts of the same primary tumor and between a lymph node metastasis and the primary tumor tissue. Thus, demonstrating both intra-and inter-tumor heterogeneity. The results also emphasized constitutional allelic variation in the MDR1 gene. Whether this might affect sensitivity to chemotherapy has to be further evaluated.

Antigenic sites in carcinoembryonic antigen

The epitope reactivities of 52 well-characterized monoclonal antibodies (Mabs) against carcinoembryonic antigen from 11 different research groups were studied using competitive solid-phase immunoassays. About 60% of all possible combinations of Mabs as inhibitors and as the primary binding antibody were investigated. The inhibition data were analyzed by a specially developed computer program "EPITOPES" which measures concordance and discordance in inhibition patterns between Mabs. The analysis showed that 43 of the 52 Mabs (83%) could be classified into one of five essentially noninteracting epitope groups (GOLD 1-5) containing between four and 15 Mabs each. The epitopes recognized by the Mabs belonging to groups 1 to 5 were peptide in nature. With one or two possible exceptions non-classifiable Mabs were either directed against carbohydrate epitopes (4 Mabs) or were inactive in the tests used. Within epitope groups GOLD 1, 4, and 5 two partially overlapping subgroups were distinguished. Mabs with a high degree of carcinoembryonic antigen specificity generally belonged to epitope groups GOLD 1 and 3.