Jeffrey W Brown1,2, Arwa Badahdah3, Micah Iticovici2, Tim J Vickers4, David M Alvarado2, Eva J Helmerhorst5, Frank G Oppenheim5,6, Jason C Mills2,7,8, Matthew A Ciorba2, James M Fleckenstein4,9,10, Esther Bullitt1. 1. Department of Physiology and Biophysics, Boston University School of Medicine, Massachusetts. 2. Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St Louis, Missouri. 3. Department of Periodontology and Oral Biology, Boston University Goldman School of Dental Medicine, Massachusetts. 4. Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St Louis, Missouri. 5. Department of Molecular and Cell Biology, Boston University, Massachusetts. 6. Department of Biochemistry, Henry M. Goldman School of Dental Medicine, Boston University, Massachusetts. 7. Department of Developmental Biology, Washington University School of Medicine, St Louis, Missouri. 8. Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri. 9. Department of Molecular Microbiology and Microbial Pathogenesis Program, Washington University School of Medicine, St Louis, Missouri. 10. Department of USA Medicine Service, Veterans Affairs Medical Center, St Louis, Missouri.
Abstract
Background: Diarrheal disease from enterotoxigenic Escherichia coli (ETEC) causes significant worldwide morbidity and mortality in young children residing in endemic countries and is the leading cause of traveler's diarrhea. As ETEC enters the body through the oral cavity and cotransits the digestive tract with salivary components, we hypothesized that the antimicrobial activity of salivary proteins might extend beyond the oropharynx into the proximal digestive tract. Results: Here, we show that the salivary peptide histatin-5 binds colonization factor antigen I pili, thereby blocking adhesion of ETEC to intestinal epithelial cells. Mechanistically, we demonstrate that histatin-5 stiffens the typically dynamic pili, abolishing their ability to function as spring-like shock absorbers, thereby inhibiting colonization within the turbulent vortices of chyme in the gastrointestinal tract. Conclusions: Our data represent the first report of a salivary component exerting specific antimicrobial activity against an enteric pathogen and suggest that histatin-5 and related peptides might be exploited for prophylactic and/or therapeutic uses. Numerous viruses, bacteria, and fungi traverse the oropharynx to cause disease, so there is considerable opportunity for various salivary components to neutralize these pathogens prior to arrival at their target organ. Identification of additional salivary components with unexpectedly broad antimicrobial spectra should be a priority.
Background: Diarrheal disease from enterotoxigenic Escherichia coli (ETEC) causes significant worldwide morbidity and mortality in young children residing in endemic countries and is the leading cause of traveler's diarrhea. As ETEC enters the body through the oral cavity and cotransits the digestive tract with salivary components, we hypothesized that the antimicrobial activity of salivary proteins might extend beyond the oropharynx into the proximal digestive tract. Results: Here, we show that the salivary peptide histatin-5 binds colonization factor antigen I pili, thereby blocking adhesion of ETEC to intestinal epithelial cells. Mechanistically, we demonstrate that histatin-5 stiffens the typically dynamic pili, abolishing their ability to function as spring-like shock absorbers, thereby inhibiting colonization within the turbulent vortices of chyme in the gastrointestinal tract. Conclusions: Our data represent the first report of a salivary component exerting specific antimicrobial activity against an enteric pathogen and suggest that histatin-5 and related peptides might be exploited for prophylactic and/or therapeutic uses. Numerous viruses, bacteria, and fungi traverse the oropharynx to cause disease, so there is considerable opportunity for various salivary components to neutralize these pathogens prior to arrival at their target organ. Identification of additional salivary components with unexpectedly broad antimicrobial spectra should be a priority.