Therapeutic Mechanism of Macrophage Inflammatory Protein 1 Neutralizing Antibody (CCL3) in Clostridium difficile Infection in Mice

Background. Clostridium difficile infection (CDI) causes diarrhea and colitis. We aimed to find a common pathogenic pathway in CDI among humans and mice by comparing toxin-mediated effects in human and mouse colonic tissues. Method. Using multiplex enzyme-linked immunosorbent assay, we determined the cytokine secretion of toxin A- and B-treated human and mouse colonic explants. Results. Toxin A and toxin B exposure to fresh human and mouse colonic explants caused different patterns of cytokine secretion. Toxin A induced macrophage inflammatory protein (MIP) 1 alpha secretion in both human and mouse explants. Toxin A reduced the expression of chloride anion exchanger SLC26A3 expression in mouse colonic explants and human colonic epithelial cells. Patients with CDI had increased colonic MIP-1 alpha expression and reduced colonic SLC26A3 (solute carrier family 26, member 3) compared with controls. Anti-MIP-1 alpha neutralizing antibody prevented death, ameliorated colonic injury, reduced colonic interleukin 1 beta (IL-1 beta) messenger RNA expression, and restored colonic SLC26a3 expression in C. difficile-infected mice. The anti-MIP-1 alpha neutralizing antibody prevented CDI recurrence. SLC26a3 inhibition augmented colonic IL-1 beta messenger RNA expression and abolished the protective effect of anti-MIP-1 alpha neutralizing antibody in mice with CDI. Conclusion. MIP-1 alpha is a common toxin A-dependent chemokine in human and mouse colon. MIP-1 alpha mediates detrimental effects by reducing SLC26a3 and enhancing IL-1 beta expression in the colon.