[ODP4E] e. Intra- and Inter-cellular Signal Transduction

[ODP-069] Strategies used by Leptospira interrogans to disassemble the epithelial apical junctional complex

Isabel Sebastián¹, Nobuhiko Okura², Bruno M. Humbel³, Jun Xu¹, Malgorzata Hall³, Chitoshi Takayama², Tetsu Yamashiro¹, Shuichi Nakamura⁴, ○Claudia Toma¹ (¹Dept. Bacteriol., Grad. Sch. Med., Univ. of the Ryukyus, ²Dept. Mol. Anatomy, Grad. Sch. Med., Univ. of the Ryukyus, ³Imaging Section,OIST, ⁴Applied Physics, Grad. Sch. Eng., Tohoku Univ.)

Bacterial pathogens have evolved multiple strategies to disassemble the epithelial apical junctional complex and establish the infection. In leptospirosis, a worldwide spread zoonotic infection mainly caused by Leptospira interrogans, dissemination across host cells is an essential stage in pathogenesis. However, the mechanisms of bacterial dissemination across epithelial cells remain poorly characterized.
In this study, we developed an in vitro model to study the interactions of L. interrogans with renal proximal tubule epithelial cells (RPTECs). Our results show that after 24 hours post-infection, the main bacterial population interacting with RPTECs remained extracellularly in close contact with the plasma membrane by adhering or crawling. L. interrogans induced E-cadherin cleavage and endocytosis with release of the soluble N-terminal fragment to the extracellular medium, concomitantly with gradually transepithelial electrical resistance (TEER) decrease, mislocalization of AJC proteins (occludin, claudin-10, ZO-1, and cingulin), and cytoskeletal rearrangement. Inhibition of the dynamin dependent-E-cadherin endocytosis prevents TEER decrease. Our findings show that AJC disassembly of epithelial cells and transmigration of bacteria through the paracellular route is an important step during dissemination of L. interrogans in the host.