Medizin - Open Access LMU - Teil 15/22

Background: Pancreatic infiltration by leucocytes represents a hallmark in acute pancreatitis. Although leucocytes play an active role in the pathophysiology of this disease, the relation between leucocyte activation, microvascular injury and haemorrhage has not been adequately addressed.Methods: We investigated intrapancreatic leucocyte migration, leucocyte extravasation and pancreatic microperfusion in different models of oedematous and necrotising acute pancreatitis in lys-EGFP-ki mice using fluorescent imaging and time-lapse intravital microscopy.Results: In contrast to the current paradigm of leucocyte recruitment, the initial event of leucocyte activation in acute pancreatitis was represented through a dose- and time-dependent occlusion of pancreatic capillaries by intraluminally migrating leucocytes. Intracapillary leucocyte accumulation (ILA) resulted in dense filling of almost all capillaries close to the area of inflammation and preceded transvenular leucocyte extravasation. ILA was also initiated by isolated exposure of the pancreas to interleukin 8 or fMLP, demonstrating the causal role of chemotactic stimuli in the induction of ILA. The onset of intracapillary leucocyte accumulation was strongly inhibited in LFA-1-/- and ICAM-1-/- mice, but not in Mac-1-/- mice. Moreover, prevention of intracapillary leucocyte accumulation led to the development of massive capillary haemorrhages and transformed mild pancreatitis into lethal haemorrhagic disease.Conclusions: ILA represents a novel protective and potentially lifesaving mechanism of haemostasis in acute pancreatitis. This process depends on expression of LFA-1 and ICAM-1 and precedes the classical steps of the leucocyte recruitment cascade.

Aim: To demonstrate that interference microscopy of flat

mounted internal limiting membrane specimens clearly

delineates cellular proliferations at the vitreomacular

interface.

Methods: ILM specimens harvested during vitrectomy

were fixed in glutaraldehyde 0.05% and paraformaldehyde

2% for 24 h (pH 7.4). In addition to interference

microscopy, immunocytochemistry using antibodies

against glial fibrillar acidic protein (GFAP) and neurofilament

(NF) was performed. After washing in phosphatebuffered

saline 0.1 M, the specimens were flat-mounted

on glass slides without sectioning, embedding or any

other technique of conventional light microscopy. A cover

slide and 49,6-diamidino-2-phenylindole (DAPI) medium

were added to stain the cell nuclei.

Results: Interference microscopy clearly delineates

cellular proliferations at the ILM. DAPI stained the cell

nuclei. Areas of cellular proliferation can be easily

distinguished from ILM areas without cells.

Immunocytochemistry can be performed without changing

the protocols used in conventional microscopy.

Conclusion: Interference microscopy of flat mounted ILM

specimens gives new insights into the distribution of

cellular proliferations at the vitreomacular interface and

allows for determination of the cell density at the ILM.

Given that the entire ILM peeled is seen en face, the

techniques described offer a more reliable method to

investigate the vitreoretinal interface in terms of cellular

distribution compared with conventional microscopy.

Background: Previous cross-sectional studies have shown that job change due to breathing problems at the workplace (respiratory work disability) is common among adults of working age. That research indicated that occupational exposure to gases, dust and fumes was associated with job change due to breathing problems, although causal inferences have been tempered by the cross-sectional nature of previously available data. There is a need for general population-based prospective studies to assess the incidence of respiratory work disability and to delineate better the roles of potential predictors of respiratory work disability.Methods: A prospective general population cohort study was performed in 25 centres in 11 European countries and one centre in the USA. A longitudinal analysis was undertaken of the European Community Respiratory Health Survey including all participants employed at any point since the baseline survey, 6659 subjects randomly sampled and 779 subjects comprising all subjects reporting physician-diagnosed asthma. The main outcome measure was new-onset respiratory work disability, defined as a reported job change during follow-up attributed to breathing problems. Exposure to dusts (biological or mineral), gases or fumes during follow-up was recorded using a job-exposure matrix. Cox proportional hazard regression modelling was used to analyse such exposure as a predictor of time until job change due to breathing problems.Results: The incidence rate of respiratory work disability was 1.2/1000 person-years of observation in the random sample (95% CI 1.0 to 1.5) and 5.7/1000 person-years in the asthma cohort (95% CI 4.1 to 7.8). In the random population sample, as well as in the asthma cohort, high occupational exposure to biological dust, mineral dust or gases or fumes predicted increased risk of respiratory work disability. In the random sample, sex was not associated with increased risk of work disability while, in the asthma cohort, female sex was associated with an increased disability risk (hazard ratio 2.8, 95% CI 1.3 to 5.9).Conclusions: Respiratory work disability is common overall. It is associated with workplace exposures that could be controlled through preventive measures.

Background and aims: Interleukin 26 (IL-26), a novel IL-10-like cytokine without a murine homologue, is expressed in T helper 1 (Th1) and Th17 cells. Currently, its function in human disease is completely unknown. The aim of this study was to analyse its role in intestinal inflammation.Methods: Expression studies were performed by reverse transcription-PCR (RT-PCR), quantitative PCR, western blot and immunohistochemistry. Signal transduction was analysed by western blot experiments and ELISA. Cell proliferation was measured by MTS (3-(4,5-dimethylthiazol-2-yl)-5-(carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. IL-26 serum levels were determined by an immunoluminometric assay (ILMA).Results: All examined intestinal epithelial cell (IEC) lines express both IL-26 receptor subunits IL-20R1 and IL-10R2. IL-26 activates extracellular signal-related kinase (ERK)-1/2 and stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) mitogen-activated protein (MAP) kinases, Akt and signal transducers and activators of transcription (STAT) 1/3. IL-26 stimulation increases the mRNA expression of proinflammatory cytokines but decreases cell proliferation. In inflamed colonic lesions of patients with Crohn's disease, an elevated IL-26 mRNA expression was found that correlated highly with the IL-8 and IL-22 expression. Immunohistochemical analysis demonstrated IL-26 protein expression in colonic T cells including Th17 cells expressing the orphan nuclear receptor ROR\textgreekgt, with an increased number of colonic IL-26-expressing cells in active Crohn's disease.Conclusion: Intestinal cells express the functional IL-26 receptor complex. IL-26 modulates IEC proliferation and proinflammatory gene expression and its expression is upregulated in active Crohn's disease, indicating a role for this cytokine system in the innate host cell response during intestinal inflammation. For the first time, IL-26 expression is demonstrated in colonic ROR\textgreekgt-expressing Th17 cells in situ, supporting a role for this cell type in the pathogenesis of Crohn's disease.

Traditionally, Crohn's disease has been associated with a Th1 cytokine profile, while Th2 cytokines are modulators of ulcerative colitis. This concept has been challenged by the description of tolerising regulatory T cells (Treg) and by proinflammatory Th17 cells, a novel T cell population characterised by the master transcription factor ROR\textgreekgt, the surface markers IL23R and CCR6, and by production of the proinflammatory cytokines IL17A, IL17F, IL21, IL22 and IL26, and the chemokine CCL20. Th17 cells differentiate under the influence of IL1\textgreekb, IL6, IL21 and IL23. Recent studies indicate that TGF\textgreekb is essential not only for the development of murine Th17 cells but also for differentiation of human Th17 cells. TGF\textgreekb reciprocally regulates the differentiation of inflammatory Th17 cells and suppressive Treg subsets, with the concomitant presence of proinflammatory cytokines favouring Th17 cell differentiation. Several studies demonstrated an important role of Th17 cells in intestinal inflammation, particularly in Crohn's disease. Genome-wide association studies indicate that IL23R and five additional genes involved in Th17 differentiation (IL12B, JAK2, STAT3, CCR6 and TNFSF15) are associated with susceptibility to Crohn's disease and partly also to ulcerative colitis. Taken together, both Th1 and Th17 cells are important mediators of inflammation in Crohn's disease, although activities previously ascribed to IL12 may be mediated by IL23. Anti-IL12/IL23p40 antibody therapy, which targets both Th1 and Th17 cells, is effective in Crohn's disease. However, the complex relationship between Th1 and Th17 cells has not been completely analysed. This will be of great importance to delineate the specific contributions of these cells to Crohn's disease and other autoimmune diseases.