Control of Helicobacter Pylori with Engineered Probiotics Secreting Selective Guided Antimicrobial Peptides

Helicobacter pylori is the primary cause of 78% of gastric cancer cases, providing an opportunity to prevent cancer by controlling a single bacterial pathogen within the complex gastric microbiota. Worldwide, over 750,000 deaths are due to gastric cancer annually, and increasing H. pylori antibiotic resistance threatens control strategies. We developed highly selective antimicrobial agents against H. pylori by fusing an H. pylori-binding guide peptide (MM1) to broad spectrum antimicrobial peptides. The common dairy probiotic Lactococcus lactis was then engineered to secrete these guided antimicrobial peptides (gAMPs). When co-cultured in vitro with H. pylori, the gAMP probiotics were at least 10-fold less toxic against off-target bacteria while remaining fully toxic against the targeted H. pylori. The MM1 guide was shown to specifically bind to H. pylori and not off-target bacteria using a guide-GFP fusion protein and flow cytometry. These highly selective gAMP probiotics were then tested by oral gavage in mice infected with H. pylori. As a therapy, the probiotics outperformed antibiotic treatment, effectively eliminating H. pylori in just five days, and also protected mice from challenge infection as a prophylactic. As expected, the gAMP probiotics were as toxic against H. pylori as the unguided AMP probiotics, though both guided and unguided AMPs were effective in restoring the microbiome diversity, indicating that simply alleviating the dysbiosis of H. pylori infection was the major factor in diversity restoration. Given the commercial success of the engineered probiotic from Zbiotics, there may commercial space for highly selective yet inexpensive antimicrobials such as the one presented here.

Learning Objectives:

1. Evaluate the potential of the newly emerging technology of probiotics engineered to deliver therapeutic peptides for different applications. For which applications would this technology be inappropriate?

2. Determine the risks associated with continued antibiotic use versus the use of probiotics engineered to deliver antimicrobial peptides specifically targeting bacterial pathogens.

3. Evaluate the potential for (or currently actual) commercial availability of engineered probiotics.