Intestinal Absorption of Bacterial Cell Wall Polymers in Rats

Abstract

Bacterial cell wall polymers initiate and sustain chronic granulomatous inflammation and characteristic immunological changes in animal models after local and systemic injection (1,2). The component of the cell wall responsible for the inflammation and immunodulation is the covalently bound peptidoglycan-polysaccharide (PG-PS) complex, which is found in nearly all bacterial species, including the normal enteric flora. Purified aqueous suspensions of PG-PS can induce granulomatous enterocolitis that persists for 6 months in rats after intramural injection and chronic relapsing synovitis, uveitis, vasculitis with skin lesions, hepatic granulomas, carditis and anemia after systemic injection (3). PG-PS activates macrophages and the alternate complement pathway and has mitogenic, adjuvant and immunogenic properties for B cells (4). Because the histologic appearance, immunologic response and location of systemic inflammation of PG-PS-induced inflammation resembles that seen in Crohn’s disease and because high concentrations of bacteria are found in the distal intestine, we postulate that PG-PS from intestinal bacteria may be important in the pathogenesis of Crohn’s disease However, to be etiologically significant, PG-PS must cross the intestinal epithelium. The purpose of these experiments is to investigate absorption of gavage-fed PG-PS by measuring systemic uptake and serum antibody response in rats.