Inhibiting oral intoxication of botulinum neurotoxin A complex by carbohydrate receptor mimics.
Botulinum neurotoxins (BoNTs) cause the disease botulism manifested by flaccid paralysis that could be fatal to humans and animals. Oral ingestion of the toxin with contaminated food is one of the most common routes for botulism. BoNT assembles with several auxiliary proteins to survive in the gastrointestinal tract and is subsequently transported through the intestinal epithelium into the general circulation. Several hemagglutinin proteins form a multi-protein complex (HA complex) that recognizes host glycans on the intestinal epithelial cell surface to facilitate BoNT absorption. Blocking carbohydrate binding to the HA complex could significantly inhibit the oral toxicity of BoNT. Here, we identify lactulose, a galactose-containing non-digestible sugar commonly used to treat constipation, as a prototype inhibitor against oral BoNT/A intoxication. As revealed by a crystal structure, lactulose binds to the HA complex at the same site where the host galactose-containing carbohydrate receptors bind. In vitro assays using intestinal Caco-2 cells demonstrated that lactulose inhibits HA from compromising the integrity of the epithelial cell monolayers and blocks the internalization of HA. Furthermore, co-administration of lactulose significantly protected mice against BoNT/A oral intoxication in vivo. Taken together, these data encourage the development of carbohydrate receptor mimics as a therapeutic intervention to prevent BoNT oral intoxication.
Department of Physiology and Biophysics, University of California, Irvine, CA 92697, USA.
Kwangkook
K
Lee
Department of Physiology and Biophysics, University of California, Irvine, CA 92697, USA.
Kwok-Ho
KH
Lam
Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover, Germany.
Anna-Magdalena
AM
Kruel
Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover, Germany.
Stefan
S
Mahrhold
NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Building 436E, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA.
Kay
K
Perry
Foodborne Toxin Detection and Prevention Research Unit, Western Regional Research Center, United States Department of Agriculture, Agricultural Research Service, Albany, CA 94710, USA.
Luisa W
LW
Cheng
Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover, Germany. Electronic address: rummel.andreas@mh-hannover.de.
Andreas
A
Rummel
Department of Physiology and Biophysics, University of California, Irvine, CA 92697, USA. Electronic address: r.jin@uci.edu.
Rongsheng
R
Jin
D000284:Administration, Oral; D000818:Animals; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000037:antagonists & inhibitors* / Q000633:toxicity; D001906:Botulism / Q000517:prevention & control; D018938:Caco-2 Cells / Q000187:drug effects; D018360:Crystallography, X-Ray; D005260:Female; D006388:Hemagglutinins / Q000378:metabolism*; D006801:Humans; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D007792:Lactulose / Q000378:metabolism / Q000494:pharmacology*; D051379:Mice; D011485:Protein Binding / Q000187:drug effects
D006388:Hemagglutinins; D007544:Isopropyl Thiogalactoside; D007792:Lactulose; D019274:Botulinum Toxins, Type A
Botulinum neurotoxin; Carbohydrate receptor; Hemagglutinin; Inhibitor; Lactulose; Progenitor toxin complex