Signaling of Neisseria meningitidis MC58 mutants to primary human umbilical vein endothelial cells (HUVEC)

We examined the adherence-mediated signaling of meningococci to human cells by comparing gene expression profiles of primary human umbilical vein endothelial cells (HUVEC) infected by piliated and adherent wild-type (WT), frpC/frpA-deficient mutant, or the non-adherent (pilD) N. meningitidis MC58 bacteria defective in production of the type IV pilus, respectively. Surprisingly, no significant difference was found between the transcriptomes of HUVECs infected by bacteria producing, or not the RTX FrpC and FrpA proteins, thus failing to provide any hints on their biological activity. In contrast, pili-mediated adhesion of meningococci resulted in alterations of expression levels of human genes known to regulate apoptosis, cell proliferation, inflammatory response or adhesion. In particular, genes for signaling pathway proteins involved in early embryonic development, such as transforming growth factor- (TGF-)/Smad, Wnt/-catenin, and Notch/Jagged were found to be upregulated upon adhesion of N. meningitidis together with genes for a number of transcription factors. This reveals that adhering piliated meningocci manipulate signaling pathways controlling human cell proliferation, survival and defense mechanisms, while establishing a commensal relationship with the host.

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Linhartova I, Basler M, Ichikawa J, Pelicic V, Osicka R, Lory S, Nassif X, Sebo P