Sialic Acid is Crucial to Citrobacter Rodentium’s Role in Bacterial Pathogenesis

Celiac.com 08/03/2023 - Sialic acid is a sugar, derived from intestinal mucus, that plays a crucial role in the infection process of a bacterial pathogen called Citrobacter rodentium. C. rodentium has developed strategies to overcome the protective barrier of intestinal mucus, and reach the gut's mucosal surface to cause diseases; this potentially includes celiac disease. 

Upon acquiring sialic acid, the pathogen uses it as a fuel for growth and expansion in the gut. Sialic acid also triggers the secretion of two important proteins, Pic and EspC, which help the pathogen penetrate the mucus and adhere to the gut's cells.

Can C. rodentium Metabolize Sialic Acid for Growth?

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A team of researchers recently set out to determine if C. rodentium can metabolize sialic acid, and use it as a primary carbon source for growth. The research team included Qiaochu Liang; Caixia Ma; Shauna M. Crowley; Joannie M. Allaire; Xiao Han; Raymond W. W. Chong; Nicolle H. Packer; Hong Bing Yu; and Bruce A. Vallance.

They are variously affiliated with the Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, BC Children’s Hospital Research Institute and the University of British Columbia, Vancouver, BC, Canada; and the ARC Centre of Excellence for Synthetic Biology, School of Natural Sciences, Faculty of Science and Engineering, Macquarie University, North Ryde, Sydney, Australia.

When the researchers deleted the nanT gene responsible for sialic acid transportation, the pathogen's ability to colonize the intestine was significantly impaired. Sialic acid enhances the pathogen's ability to degrade intestinal mucus and adhere to intestinal cells, promoting its infection in the host.

Conclusion

Understanding how pathogens like C. rodentium navigate through the gut's defenses and establish infections is essential for human health. By focusing on sialic acid's role as a nutrient and a signaling molecule for bacterial pathogenesis, this research sheds light on the pathogen's adaptation to the host's intestinal environment. 

Sialic acid is crucial to promoting Citrobacter rodentium’s role in bacterial pathogenesis, and may offer insights into celiac disease development. These findings can help researchers unravel the mechanisms behind bacterial infections, and may pave the way for new strategies to combat enteric bacterial pathogens, and to protect against intestinal infections.

Read more at pnas.org