Viscosity gradient within the mucus layer determines the mucosal barrier function and the spatial organization of the intestinal microbiota.

Background: Migration is an important virulence factor for intestinal bacteria. However, the role of bacterial mobility in the penetration of viscous mucus and their spatial organization within the colon is relatively unknown.

Methods: Movements of fecal bacteria were assessed in gels of varying agarose concentrations and were compared with patterns of bacterial distribution observed in colons from conventional and Enterobacter cloacae-monoassociated mice.

Bacterial antigens alone can influence intestinal barrier integrity, but live bacteria are required for initiation of intestinal inflammation and injury.

Intestinal flora plays a critical role in the initiation and perpetuation of inflammatory bowel disease. This study examined whether live fecal bacteria were necessary for the initiation of this inflammatory response or whether sterile fecal material would provoke a similar response. Three preparations of fecal material were prepared: (1) a slurry of live fecal bacteria, (2) a sterile lysate of bacterial antigens, and (3) a sterile filtrate of fecal water.

Reduction of colitis by prebiotics in HLA-B27 transgenic rats is associated with microflora changes and immunomodulation.

HLA-B27 transgenic rats develop spontaneous colitis under specific pathogen-free conditions (SPF) but germ-free rats remain disease-free, emphasizing a role for intestinal bacteria in the pathogenesis of chronic intestinal inflammation. Prebiotics are dietary substances that affect the host by stimulating growth and/or activity of potentially health promoting bacteria. The aims of this study were to investigate whether prebiotics can prevent colitis in SPF HLA-B27 rats, and secondly, to explore mechanisms of protection.