Attenuation of Colitis by Serum-Derived Bovine Immunoglobulin/Protein Isolate in a Defined Microbiota Mouse Model

The pathogenesis of inflammatory bowel disease (IBD) is complex and multifaceted including genetic predisposition, environmental components, microbial dysbiosis, and inappropriate immune activation to microbial components. Pathogenic bacterial provocateurs like adherent and invasive E. coli have been reported to increase susceptibility to Crohn's disease. Serum-derived bovine immunoglobulin/protein isolate (SBI) is comprised primarily of immunoglobulins (Igs) that bind to conserved microbial components and neutralize exotoxins. To demonstrate that oral administration of SBI may modulate mucosal inflammation following colonization with E. coli, LF82, and exposure to dextran sodium sulfate (DSS). Defined microbiota mice harboring the altered Schaedler flora (ASF) were administered SBI or hydrolyzed collagen twice daily starting 7 days prior to challenge with E. coli LF82 and continuing for the remainder of the experiment. Mice were treated with DSS for 7 days and then evaluated for evidence of local and peripheral inflammation. Igs within SBI bound multiple antigens from all eight members of the ASF and E. coli LF82 by western blot analysis. Multiple parameters of LF82/DSS-induced colitis were reduced following administration of SBI, including histological lesion scores, secretion of cytokines and chemokines from cecal biopsies, intestinal fatty acid binding protein (I-FABP) and serum amyloid A from plasma. Oral administration of SBI attenuated clinical signs of LF82/DSS-induced colitis in mice. The data are consistent with the hypothesis that SBI immunoglobulin binding of bacterial antigens in the intestinal lumen may inhibit the inflammatory cascades that contribute to IBD, thus attenuating DSS-induced colitis.