Targeted Delivery of Narrow-Spectrum Protein Antibiotics to the Lower Gastrointestinal Tract in a Murine Model of Escherichia coli Colonization

Abstract

Bacteriocins are narrow-spectrum protein antibiotics that could potentially be used to engineer the human gut microbiota. However, technologies for targeted delivery of proteins to the lower gastrointestinal (GI) tract in preclinical animal models are currently lacking. In this work, we have developed methods for the microencapsulation of Escherichia coli targeting bacteriocins, colicin E9 and Ia, in a pH responsive formulation to allow their targeted delivery and controlled release in an in vivo murine model of E. coli colonization. Membrane emulsification was used to produce a water-in-oil emulsion with the water-soluble polymer subsequently cross-linked to produce hydrogel microcapsules. The microcapsule fabrication process allowed control of the size of the drug delivery system and a near 100% yield of the encapsulated therapeutic cargo. pH-triggered release of the encapsulated colicins was achieved using a widely available pH-responsive anionic copolymer in combination with alginate biopolymers. In vivo experiments using a murine E. coli intestinal colonization model demonstrated that oral delivery of the encapsulated colicins resulted in a significant decrease in intestinal colonization and reduction in E. coli shedding in the feces of the animals. Employing controlled release drug delivery systems such as that described here is essential to enable delivery of new protein therapeutics or other biological interventions for testing within small animal models of infection. Such approaches may have considerable value for the future development of strategies to engineer the human gut microbiota, which is central to health and disease.

Review article: The complex interplay between diet and Escherichia coli in inflammatory bowel disease

“…Recent work has demonstrated that E. coli ‐specific protein antibiotics known as colicins can be successfully formulated for targeted oral delivery and controlled release to reduce AIEC LF82 levels in an in vivo murine model of E. coli colonisation. In the future, it is possible that concomitant therapy with such antimicrobial agents and effective dietary therapies, like EEN, will have better synergistic effectiveness than each of these therapeutics in isolation 145 …”

“…In the future, it is possible that concomitant therapy with such antimicrobial agents and effective dietary therapies, like EEN, will have better synergistic effectiveness than each of these therapeutics in isolation. 145 In conclusion, there are preclinical and some clinical trial data to propose that E. coli and other Enterobacteriaceae interact with certain dietary components in CD to promote gut inflammation. Nonetheless, for some dietary components, patterns or therapies the evidence is inconsistent and currently none of these studies can prove a causal relationship.…”

Bacterial pore-forming toxins

“…Another study demonstrated that microcapsule delivery of the active form of colicin Ia reduced E. coli colonisation in murine models [225]. Engineering of chimeric proteins and use of cocktails of different toxins could provide a greater spectrum of activity and reduce the risk of resistance developing in target bacteria [226].…”

“…Moreover, when injected into the bloodstream of mice, pyocin S5 was observed to retain its functionality and to improve mouse survival to Pseudomonas infections [224]. Another study demonstrated that microcapsule delivery of the active form of colicin Ia reduced E. coli colonisation in murine models [225]. Engineering of chimeric proteins and use of cocktails of different toxins could provide a greater spectrum of activity and reduce the risk of resistance developing in target bacteria [226].…”

Reduction of gastrointestinal tract colonization by Klebsiella quasipneumoniae using antimicrobial protein KvarIa

“…Recently, a similar study was published describing the use of encapsulated colicins for the eradication of E. coli in mice [36.] Colicins encapsulated into hydrogel particles were shown to be released from the protective coat at pH above 5 and reduce colonizing E. coli numbers in the gut and in feces, although complete eradication of the pathogen was not achieved [ 39 ]. Consequently, further research on klebicin formulation for the most efficient release in the lower intestinal tract is necessary.…”