- Deletion of neutral endopeptidase exacerbates intestinal inflammation induced by Clostridium difficile toxin A. Kirkwood, K.S., Bunnett, N.W., Maa, J., Castagliolo, I., Liu, B., Gerard, N., Zacks, J., Pothoulakis, C., Grady, E.F. Am. J. Physiol. Gastrointest. Liver Physiol. (2001)