Entamoeba histolytica Gal/GalNAc lectin intermediate subunit promotes inflammation and epithelial damage in intestinal amebiasis through its C3 region.

Entamoeba histolytica is a common enteric protozoan that sometimes transitions from a symbiont to a pathogen, causing intestinal amebiasis and extraintestinal abscesses in the host. The early-to-intermediate stages of intestinal amebiasis are characterized by an intense inflammatory response, during which host innate immune defenses play an important role. Here, using the cecal infection model of C3H/HeNCrl mice, we performed single-cell RNA sequencing of cecal tissues and identified the prominent pro-inflammatory function of host macrophages in intestinal amebiasis. On the amoebic cell surface, Igl is an intermediate subunit of galactose- and N-acetyl-D-galactosamine-inhibitable lectins, which contributes to parasite adherence. We proposed that E. histolytica Igl diffuses along with amoebic extracellular vesicles and contacts host macrophages, binding to the TLR4 co-receptor MD2 through its C3 region and initiating the TLR4/MyD88/NF-{kappa}B inflammatory signaling pathway in host cells. Moreover, by inducing macrophage inflammation and cytokine production, E. histolytica indirectly impairs intestinal epithelium integrity through the Igl protein. To our knowledge, this is the first report showing a host single-cell atlas in the field of amebiasis research. In response to the parasite invasion during intestinal amebiasis, our study provides new insights elucidating the inflammatory formation and epithelial damage of gut mucosal immune system, and also conduces to the identification of potential drug targets for these amoebas.