Friebel, JuliánSchinnerling, KatinaWeigt, KathleenHeldt, ClaudiaFromm, AnjaBojarski, ChristianSiegmund, BrittaEpple, Hans-JörgKikhney, JudithMoter, AnnetteSchneider, ThomasSchulzke, Jörg D.2024-01-022024-01-022023-04International Journal of Molecular Sciences, Open Access, Volume 24, Issue 7April 2023 Article number 619716616596https://repositorio.unab.cl/xmlui/handle/ria/54573Indexación: Scopus.Background: Tropheryma whipplei (TW) can cause different pathologies, e.g., Whipple’s disease and transient gastroenteritis. The mechanism by which the bacteria pass the intestinal epithelial barrier, and the mechanism of TW-induced gastroenteritis are currently unknown. Methods: Using ex vivo disease models comprising human duodenal mucosa exposed to TW in Ussing chambers, various intestinal epithelial cell (IEC) cultures exposed to TW and a macrophage/IEC coculture model served to characterize endocytic uptake mechanisms and barrier function. Results: TW exposed ex vivo to human small intestinal mucosae is capable of autonomously entering IECs, thereby invading the mucosa. Using dominant-negative mutants, TW uptake was shown to be dynamin- and caveolin-dependent but independent of clathrin-mediated endocytosis. Complementary inhibitor experiments suggested a role for the activation of the Ras/Rac1 pathway and actin polymerization. TW-invaded IECs underwent apoptosis, thereby causing an epithelial barrier defect, and were subsequently subject to phagocytosis by macrophages. Conclusions: TW enters epithelia via an actin-, dynamin-, caveolin-, and Ras-Rac1-dependent endocytosis mechanism and consecutively causes IEC apoptosis primarily in IECs invaded by multiple TW bacteria. This results in a barrier leak. Moreover, we propose that TW-packed IECs can be subject to phagocytic uptake by macrophages, thereby opening a potential entry point of TW into intestinal macrophages.enApoptosisBarrier functionCaveolinEndocytosisGastroenteritisInvasionTropheryma whippleiUssing chamberWhipple’s diseaseArtículoCC BY 4.0 DEED Attribution 4.0 International10.3390/ijms24076197