To gain insight into the mechanisms underlying the therapeutic efficacy of our synbiotic, we showed that the combination of chitin–glucan at 1.5 g/d and L. acidophilus NCFM at 109 CFU/d decreased colonic inflammation, reducing the intensity of macroscopic lesions by 35% and the levels of colonic MPO, considered as a marker of neutrophil infiltration, by 49% compared to untreated rats with colitis. The gene discussed is MPO; the disease is colitis.