Multiscale Invasion Assay for Probing Macrophage Response to Bacteria

Abstract

The immune system is a complex network of various cellular components that must differentiate between pathogenic bacteria and the commensal bacteria of the human microbiome, where misrecognition is linked to inflammatory disorders. Fragments of bacterial cell wall peptidoglycan bind to pattern recognition receptors within macrophages, leading to immune activation. To study this complex process, an approach for three-dimensional (3D) culture of human macrophages and their invasion with relevant bacteria in a well-defined hydrogel-based synthetic matrix inspired by the gut was established. Workflows were developed for monocyte encapsulation and differentiation into macrophages in 3D culture with high viability. Bacteria invaded into macrophages permitted in situ peptidoglycan labeling. Macrophages exhibited biologically-relevant cytokine release in response to bacteria. This multi-dimensional bacteria-macrophage co-culture system will prove useful in future studies to observe bacterial fragment production and localization in the cell at the carbohydrate level for insights into how our immune system properly senses bacteria. TOC Figure O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=125 SRC="FIGDIR/small/385617v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@45cdf1org.highwire.dtl.DTLVardef@d3c3d3org.highwire.dtl.DTLVardef@dd74f2org.highwire.dtl.DTLVardef@128d1da_HPS_FORMAT_FIGEXP M_FIG C_FIG