Helicobacter pylori-infection induces podoplanin-mediated migration of macrophages

Abstract

Background: Helicobacter pylori is a gram-negative microaerophilic bacterium that colonizes human gut. The pathogen is notoriously known to persist by evading the host immune system, resulting in chronic inflammation which precedes gastric adenocarcinoma in human host. In a preliminary microarray experiment, we showed that a mucin transmembrane protein encoding gene, Podoplanin (Pdpn) has increased >10-fold following H. pylori infection in RAW 264.7 monocytic macrophage cells, suggesting a vital role of Pdpn during H. pylori infection. Our current study aims to investigate the role of the Pdpn in the immunity against H. pylori. Methods and materials: Podoplanin knockout and transgenic RAW 264.7 cells were generated using CRISPR-Cas9 technology and retroviral transduction, respectively. Functional aspects of the wildtype and mutant clones were identified through phagocytosis, ELISA, migration and wound healing assay. Transcriptomic profiles of these cells were investigated using Nanostring nCounter gene expression assay. Results: Cell activation, bacteria phagocytosis (uptake and killing) and cytokine secretion were not significantly affected in the Pdpn knockout cells. However, transwell migration in the Boyden chamber and ability for wound healing were significantly impaired in the knockout cells. Transcriptomic analysis revealed a few cell adhesion and actin regulation associated genes were dysregulated in both Pdpn knockout and transgenic cells. Conclusion: Our finding suggests Pdpn as a crucial molecule which regulates the migration of macrophage during H. pylori infection.