1. Molecular Mechanisms Underlying Diarrheagenic Enteroaggregative Escherichia coli (EAEC)-Induced Epithelial Inflammation Anja Sander Prof. Karen A. Krogfelt Statens Serum Institut Prof. Beth A. McCormick UMASS Medical School, USA PhD Erik Juncker Boll Statens Serum Institut

2. EAEC and its pathogenesis Results Methods Conclusions Future perspectives Outline

4. EAEC pathogenesis Modified after Harrington et al. (2006)

9. Pathogen-induced transepithelial migration of neutrophils Neutrophil migration LUMEN BASOLATERAL Blood Tight junction Bacteria 1 Host signaling response 2 IL-8 3 PMNs Virulence factors trigger

10. In vitro assay: Transepithelial migration of polymorphonuclear neutrophils (PMNs) Methods 96-well microtiter plate Colorimetric assay: Myeloperoxidase Transwell inserts Human colon cancer-derived epithelial cells

12. Example results for PMN migration assay Positive control EAEC strains tested Negative control Measures the number of transmigrated PMNs, reflecting the inflammatory response induced by EAEC infection Mean ± St.Dev.

14. Expression of AAFs is required for triggering PMN migration 042: EAEC prototype strain expressing AAF/II 55989: EAEC prototype strain expressing AAF/III – not constructed C1010-00: EAEC prototype strain expressing AAF/IV (Olesen et al. 1994)

15. AAF/II biogenesis genes encoded on pEJB02 Region 1 aggR: transcription activator aafA: major fimbrial subunit aafD: accessory gene Region 2 AafC: accessory gene AafB: minor fimbrial subunit From Erik Juncker Boll Aim: To directly characterize the pro-inflammatory properties of plasmid-encoded AAFs

16. Expression of plasmid-encoded AAF required for triggering PMN migration In a model of human intestinal xenografts in immuno-deficient mice, HB101/pEJB02 caused PMN migration and tissue damage to the same extent as 042 (Boll et al. 2011) HB101: afimbrial E. coli laboratory strain Plasmid constructs from Boll et al. 2011 and Boisen et al. 2008

17. Hypothesized model of EAEC-induced inflammation – Based on drug inhibitor studies Results part 2: Signaling pathway AIM: Do other EAEC's than 042 trigger the signaling pathway underlying EAEC induced inflammation?

18. The inhibitor baicalein blocks 12/15-LOX activity Drug inhibitor study to characterize the signaling pathway underlying EAEC-induced PMN migration

19. Using an RNA interference-based approach to test the hypothesized model of EAEC-induced inflammation Key enzymes

21. siRNA generated against mRNA of PLA 2 G 6 reduces the expression of this enzyme iPLA 2 is involved in the host signaling pathway underlying EAEC 042-induced PMN transepithelial migration

22. 12/15-LOX and MRP2 are involved in the host signaling pathway underlying EAEC-induced PMN migration siRNA generated against mRNA of ALOX15 reduces the expression of these enzymes siRNA generated against mRNA of MRP2 reduces the expression of these enzymes