Central Nervous System-Infecting Pathogens Escherichia coli and Cryptococcus neoformans Exploit the Host Pdlim2 for Intracellular Traversal and Exocytosis in the Blood-Brain Barrier

Abstract

Microbial penetration of the blood–brain barrier, a prerequisite for development of the central nervous system (CNS) infection, involves microbial invasion, intracellular traversal and exocytosis. Microbial invasion of the blood-brain barrier has been investigated, but the molecular basis for microbial traversal and exit from the blood-brain barrier remains unknown. We performed transcriptome analysis of the human brain microvascular endothelial cell (HBMEC) infected with Escherichia coli and Cryptococcus neoformans , representative bacterial and fungal pathogens common in CNS infection. Among the upregulated targets in response to E. coli and C. neoformans infection, PDLIM2 was knocked down by shRNA in HBMEC for further investigation. We demonstrated that Pdlim2 specifically regulated the microbial traversal and exit from HBMEC by assessing microbial invasion, transcytosis, intracellular multiplication and egression. Additionally, the defective exocytosis of internalized E. coli from the PDLIM2 shRNA knockdown cell was restored by treatment with a calcium ionophore (ionomycin). Moreover, we performed the proximity-dependent biotin labeling with the biotin ligase BioID2 and identified 210 potential Pdlim2-interactors. Among the nine enriched Pdlim2-interactors in response to both E. coli and C. neoformans infection, we selected MPRIP and showed that HBMEC with knockdown of MPRIP mimicked the phenotype of PDLIM2 knockdown cell. These results suggest that the CNS-infecting microbes hijack Pdlim2 and Mprip for intracellular traversal and exocytosis in the blood-brain barrier.

Listeria monocytogenes y mecanismo de caballo de Troya a través de la barrera hematoencefálica

“…(7) Para acceder al cerebro, los microorganismos utilizan rutas transcelulares o paracelulares, para atravesar la barrera hemato-encefálica (BHE). Entre los mecanismos transcelulares están: la interacción directa entre microorganismos con las células endoteliales del cerebro, que conlleva a la endocitosis y la posterior transcitosis (8) ; y la posibilidad de que los monocitos puedan transportar microorganimos (Ej: L. monocytogenes) al cerebro mediante un mecanismo de "caballo de Troya" (8,9) . La alteración de las uniones de las células endoteliales de la BHE permite el paso paracelular libre.…”