Ezrin-radixin-moesin-binding phosphoprotein (EBP50), an estrogen-inducible scaffold protein, contributes to biliary epithelial cell proliferation.

Ezrin-radixin-moesin-binding phosphoprotein 50 (EBP50) anchors and regulates apical membrane proteins in epithelia. EBP50 is inducible by estrogen and may affect cell proliferation, although this latter function remains unclear. The goal of this study was to determine whether EBP50 was implicated in the ductular reaction that occurs in liver disease. EBP50 expression was examined in normal human liver, in human cholangiopathies (ie, cystic fibrosis, primary biliary cirrhosis, and primary sclerosing cholangitis), and in rats subjected to bile-duct ligation. The regulation of EBP50 by estrogens and its impact on proliferation were assessed in both bile duct-ligated rats and Mz-Cha-1 human biliary epithelial cells. Analyses of cell isolates and immunohistochemical studies showed that in normal human liver, EBP50 is expressed in the canalicular membranes of hepatocytes and, together with ezrin and cystic fibrosis transmembrane conductance regulator, in the apical domains of cholangiocytes. In both human cholangiopathies and bile duct-ligated rats, EBP50 was redistributed to the cytoplasmic and nuclear compartments. EBP50 underwent a transient increase in rat cholangiocytes after bile-duct ligation, whereas such expression was down-regulated in ovariectomized rats. In addition, in Mz-Cha-1 cells, EBP50 underwent up-regulation and intracellular redistribution in response to 17beta-estradiol, whereas its proliferation was inhibited by siRNA-mediated EBP50 knockdown. These results indicate that both the expression and distribution of EBP50 are regulated by estrogens and contribute to the proliferative response in biliary epithelial cells.

New ideas in asthma and allergy research: creating a multidisciplinary graduate school.

The spring term of 2001 saw the start of a new, unique graduate research training program at the Centre for Allergy Research at the Karolinska Institutet in Stockholm, Sweden. The program was created to bridge the gaps between basic, clinical, social, and behavioral sciences and to establish a global approach to the study of asthma and allergy. A reflection, two years on, discusses the strategies that are key to this model's success and the challenges in introducing a multidisciplinary research program.

A mouse model for in vivo tracking of the major dust mite allergen Der p 2 after inhalation.

Inhaled environmental antigens, i.e. allergens, cause allergic symptoms in millions of patients worldwide. As little is known about the fate of an allergen upon inhalation, we addressed this issue for a major dust mite allergen, Der p 2. First, a model for Der p 2-sensitization was established in C57BL/6 J mice, in which sensitized mice mounted a Der p 2-specific IgE-response with eosinophilic lung inflammation after allergen challenge in the airways. In this model, we applied recombinant Der p 2 carrying a novel C-terminal tetrapeptide Sel-tag enabling labelling with the gamma-emitting radionuclide 75Se at a single selenocysteine residue ([75Se]Der p 2). In vivo tracking of intratracheally administered [75Se]Der p 2 using whole-body autoradiography revealed that [75Se]Der p 2-derived radioactivity persisted in the lungs of sensitized mice as long as 48 h. Radioactivity was also detected in kidneys, liver and in enlarged lung-associated lymph nodes. Interestingly, a larger proportion of radioactivity was found in the lungs of sensitized compared with nonsensitized mice 24 h after intratracheal instillation of [75Se]Der p 2. A radioactive protein corresponding to intact Der p 2 could only be detected in the lungs, whereas [75Se]Der p 2-derived radioactivity was recovered in known selenoproteins both in lung and other organs. Hence, using the recently developed Sel-tag method in a mouse model for Der p 2-sensitization, we could track the fate of an inhaled allergen in vivo. Based upon our findings, we conclude that the inflammatory state of the lung influences the rate of metabolism and clearance of Der p 2. Thus, an allergic response to the inhaled allergen may lead to prolonged retention of Der p 2 in the lung.

The Malassezia sympodialis allergen Mala s 11 induces human dendritic cell maturation, in contrast to its human homologue manganese superoxide dismutase.

BACKGROUND: Recently, we identified a major Malassezia sympodialis allergen, Mala s 11, which displays a high degree of DNA sequence homology to human manganese superoxide dismutase (hMnSOD). In atopic eczema patients sensitized to M. sympodialis, hMnSOD can elicit eczematous reactions and positive skin prick tests, suggesting cross- reactivity to Mala s 11 based on molecular mimicry. The objective of the current study was to compare the influence of Mala s 11 and hMnSOD on human dendritic antigen-presenting cells. METHODS: Monocyte-derived dendritic cells (MDDCs) from healthy blood donors were co-cultured with recombinant Mala s 11 (rMala s 11), recombinant hMnSOD (rhMnSOD), lipopolysaccharide or cultured in medium alone. Phenotypic changes were analysed using flow cytometry and allogeneic lymphocyte proliferation assays. Cytokine release into culture supernatants was investigated using cytometric bead array. RESULTS: Whereas rhMnSOD did not affect the MDDC phenotype, rMala s 11 up-regulated the maturation marker CD83, the co-stimulatory molecules CD40, CD80, CD86 and HLA-DR to a similar extent as lipopolysaccharide. Furthermore, rMala s 11, but not rhMnSOD, induced significantly higher levels of TNF-alpha, IL-6, IL-8, IL-10 and IL-12p70 in the culture supernatants at 24 h in comparison with MDDCs cultured in medium alone. Finally, MDDCs pre-incubated with rMala s 11 induced a significantly higher proliferation of allogeneic CD14-depleted peripheral blood monocytes than MDDCs pre-incubated with rhMnSOD. CONCLUSION: Our results suggest that Mala s 11, but not hMnSOD, affects the immune response of healthy individuals through dendritic cell maturation and cytokine release. This indicates that dendritic cells possess the ability to distinguish between Mala s 11 and its human homologue MnSOD.