Lack of induction of suppressor T cells by intestinal epithelial cells from patients with inflammatory bowel disease.

The mechanisms underlying the chronic unrelenting inflammatory response seen in inflammatory bowel disease (IBD) are poorly understood. We have recently proposed a novel role for the normal intestinal enterocyte, that of antigen presenting cell. However, in contrast to conventional antigen presenting cells, normal enterocytes appear to selectively activate CD8+ antigen nonspecific suppressor T cells. To determine whether failure of this process may be occurring in inflammatory bowel disease, freshly isolated enterocytes from small and large bowel from normal patients, patients with Crohn's disease, ulcerative colitis, and inflammatory (diverticulitis, ischemic colitis, and gold induced colitis) controls were co-cultured with allogeneic T cells in a modified mixed lymphocyte reaction. In contrast to normal enterocytes, 42/42 Crohn's and 35/38 ulcerative colitis-derived epithelial cells stimulated CD4+ T cells, whereas 65/66 and 9/9 normal and inflammatory control enterocytes, respectively, stimulated CD8+ T cells (as previously described), suggesting that the results seen were not just a reflection of underlying inflammation. Furthermore, IBD enterocytes from both histologically involved and uninvolved tissue were similar in their ability to selectively activate CD4+ T cells, speaking for a more global defect in epithelial cells in IBD. Finally, activated T cells from IBD epithelial cell-stimulated mixed lymphocyte cultures displayed potent T helper activity in an antigen nonspecific fashion. Taken together, these data suggest that there may be an intrinsic defect in epithelial cells from patients with IBD, resulting in the inability to normally stimulate suppressor T cells in an antigen overloaded environment.

[Comparison of trunk muscle strength of soccer players with and without low back pain]. / Vergleich der Rumpfmuskelkraft von Fussballspielern mit und ohne Rückenschmerzen.

AIM OF THE STUDY: Low back pain in soccer players is one of the frequently appearing disorders caused by overuse. Myogenic dysbalances are under discussion as possible reason for this problem. In the present study the muscular strength profile of the trunk musculature of soccer players with and without low back pain was evaluated. The results of the asymptomatic players were compared to those of players with low back pain; furthermore, the collected data were compared to those of an asymptomatic reference group. The question posed was whether soccer players show a specific strength profile caused by the special, sports-specific requirements and whether this strength profile differs between players with and without low back pain. METHOD: In the present study the isometric maximal strength of 18 soccer players with and 18 soccer players without low back pain was measured in all 3 planes. The reference group was provided by the Proxomed company, which had previously analysed 1045 healthy untrained individuals of various age groups. RESULTS: The soccer players showed a sport-specific profile for the musculature, which was determined by a significant reduction of the flexion and rotation strength (flex: Ø 5.21 N/kg vs. Ø 6.49 N/kg; Ø 5.78 N/kg vs. Ø 6.66 N/kg respectively; rotation: left 7.09 N/kg, right 8.69 N/kg vs. left/right 10.1 N/kg; left 7.22 N/kg, right 8.24 N/kg vs. left/right 10.0 N/kg, respectively) as well as by an increased lateral flexion strength to the right-hand side in comparison to the reference group (lat. flex. right: 9.87 N/kg, respectively, 10.67 N/kg vs. 8.3 N/kg). A statistically significant correlation between the muscular activity in the trunk stability of soccer players with and without low back pain could not be shown. CONCLUSION: Obviously sports-specific training with additional specific training of the trunk muscles is not sufficient for the development of a balanced strength of trunk musculature. In the present study an influence of the performance of the trunk musculature on the incidence of low back pain could not be shown.

The PKA-CREB system encoded by the honeybee genome.

The cAMP-dependent kinase (PKA) plays a crucial part in long-term memory formation in the honeybee (Apis mellifera). One of the putative substrates of the PKA activity is the cAMP response element binding protein (CREB), a transcription factor in the bZIP protein family. We searched the honeybee genome to characterize genes from the CREB/CREM and the PKA families. We identified two genes that encode regulatory subunits and three genes encode catalytic subunits of PKA. Eight genes code for bZIP proteins, but only one gene was found that encodes a member of the CREB/CREM family. The phylogenetic relationship of these genes was analysed with their Drosophila and human counterparts.

Isolation of murine thymic epithelium and an improved method for its propagation in vitro.

A reliable and reproducible method for the isolation and propagation of thymic epithelial cells is described. Thymic epithelial cells from enzymatically dissociated thymus stroma are first enriched by separation on a discontinuous Percoll density gradient. The cell fractions enriched for epithelial cells are then cultured with irradiated fibroblasts in Ham's F-12 nutrient medium. Colonies of cells in these cultures contain keratin and exhibit morphologic characteristics of epithelial cells. When subcultured, the epithelial cells no longer require irradiated fibroblasts as filler cells. Some of the epithelial cells in vitro retain expression of class II (Ia) major histocompatibility antigens. The generation of defined cultures of thymic epithelial cells promises to be useful in defining their role in T cell differentiation.

Expression of class II molecules on intestinal epithelial cells in humans. Differences between normal and inflammatory bowel disease.

Expression of class II antigens on human intestinal epithelial cells was assessed using a sensitive avidinbiotin-peroxidase technique. HLA-DR was present predominantly in the normal small bowel with diminished but evident expression in the colon. HLA-DP staining was less prominent, and HLA-DQ was absent. In inflammatory bowel disease the expression of both HLA-DR and HLA-DP was increased, but that for HLA-DQ remained absent, suggesting an inherent defect in the ability of intestinal epithelial cells to express HLA-DQ. In related experiments, an interferon gamma-treated malignant epithelial cell line T84 also failed to stain for HLA-DQ and HLA-DP despite the presence of HLA-DR. Isolated RNAs for all three subclasses of HLA-D were detectable by slot-blot analysis, suggesting that the lack of HLA-DQ expression relates to posttranscriptional defects in intestinal epithelium. These and other differences with conventional class II antigen-positive accessory cells (macrophages/B cells) may help to explain the unique properties of intestinal epithelial cells as antigen-presenting cells.

The AmCREB gene is an ortholog of the mammalian CREB/CREM family of transcription factors and encodes several splice variants in the honeybee brain.

The transcription factor CREB (cAMP response element binding protein) is required for the switch from short-term to long-term synaptic plasticity and from short-term to long-term memory. Its activity is regulated by the cAMP-dependent signalling cascade, which has been shown to play a crucial role in the honeybee's long-term memory formation. To elucidate the role of the CREB in honeybee memory formation we analysed a CREB-homologous gene, AmCREB, which is expressed as several transcripts in the honeybee brain. Eight transcripts have been identified (AmCREB 1-8) that are generated by alternate splicing. One antibody generated against a subset of these variants reveals a cytosolic localization in the mushroom body alpha-lobes, the glomeruli of the antennal lobes, the protocerebral lobes, the central complex and in the optical lobes.

Cloning of a catalytic subunit of cAMP-dependent protein kinase from the honeybee (Apis mellifera) and its localization in the brain.

In the honeybee the cAMP-dependent signal transduction cascade has been implicated in processes underlying learning and memory. The cAMP-dependent protein kinase (PKA) is the major mediator of cAMP action. To characterize the PKA system in the honeybee brain we cloned a homologue of a PKA catalytic subunit from the honeybee. The deduced amino acid sequence shows 80-94% identity with catalytic subunits of PKA from Drosophila melanogaster, Aplysia californica and mammals. The corresponding gene is predominantly expressed in the mushroom bodies, a structure that is involved in learning and memory processes. However, expression can also be found in the antennal and optic lobes. The level of expression varies within all three neuropiles.

Medullary epithelial cell lines from murine thymus constitutively secrete IL-1 and hematopoietic growth factors and express class II antigens in response to recombinant interferon-gamma.

In this report, we describe the generation of two cloned epithelial cell lines, TE-71 and TE-75, from murine thymus. These cell lines resemble medullary thymic epithelium by a number of criteria, including reactivity with the monoclonal antibodies A2B5 and ER-TR5, the fucose-specific lectin derived from Ulex europeus, and the expression of keratins normally expressed by medullary thymic epithelial cells in situ. Constitutive Class II antigen expression by these cells is not detectable at the light or electron microscopic level or with flow cytometry. Following exposure to recombinant interferon-gamma or supernatants from mitogen-stimulated spleen cells, expression of Class II antigens by these thymic epithelial cell lines is increased, although less than the levels expressed by spleen cells. Medium conditioned by TE-71 and TE-75 cells exhibited colony-stimulating activity for bone marrow cells. In addition, TE-71-conditioned medium exhibited IL-1-like activity which could be neutralized with anti-IL-1 antibodies.