Microbiota is a key player in maintaining intestinal homeostasis and is severely affected during the gut inflammation. Changes in species compositions influence the severity of damage to intestinal mucosae. Huang et al. demonstrated that host glycosylation of α2’3’-linked sialic acids affects the expansion of Enterobacteriaceae during gut inflammation. Although sialic acids are preferred substrates for intestinal E. coli, this gram negative bacteria cannot digest sialylated oligosaccharides. It therefore depends on scavenging monosaccharides released by free sialidases secreted by other components of microbiome. This study showed the increase in the abundance of sialidase-coding genes during intestinal inflammation, which resulted in higher availability of sialic acids and led to increased E. coli outgrowth as well as higher severity of colitis. Oral administration of sialidase inhibitor Neu5Ac2en alleviated the inflammation symptoms. Sialidase activity assayed with fluorescent substrate 4MU-NANA.Na from Carbosynth and the fluorescence was measured at Ex360/Em440 nm.
For more details, read the original paper published in Nature communications: Huang et al., 2015.