Lactobacillus casei expressing internalins A and B reduces Listeria monocytogenes interaction with Caco-2 cells in vitro

Authors: MATHIPA, MOLOKO - UNIVERSITY OF PRETORIA; THANTSHA, MAPITSI - UNIVERSITY OF PRETORIA; BHUNIA, ARUN - PURDUE UNIVERSITY

Submitted to: Microbial Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2019
Publication Date: 4/15/2019
Citation: Mathipa, M.G., Thantsha, M.S., Bhunia, A.K. 2019. Lactobacillus casei expressing internalins A and B reduces Listeria monocytogenes interaction with Caco-2 cells in vitro. Microbial Biotechnology. 12(4):715-729.
DOI: https://doi.org/10.1111/1751-7915.13407

Interpretive Summary: Interpretative Summary Listeria monocytogenes has been implicated in a number of deadly outbreaks of foodborne illnesses, including a recent large outbreak in South Africa in 2018 resulting in over 216 deaths. In this study we tested probiotic bioengineering (genetically modifying a beneficial bacterium) as a potential strategy for preventing Listeria infection in a high-risk population. Two genes that code for invasion proteins (InlAB) that are important for the spread of Listeria from the gastrointestinal tract to the distant organs and tissues during infection were cloned into Lactobacillus casei, a well-known probiotic bacterium. In laboratory experiments the bioengineered Lactobacillus was able to prevent L. monocytogenes interaction with intestinal cells suggesting that InlAB-expressing Lactobacillus casei could be a practical approach for the prevention of listeriosis.

Technical Abstract: Listeria monocytogenes has been implicated in a number of outbreaks including the recent largest outbreak in South Africa. Current methods for prevention of foodborne L. monocytogenes infection are inadequate, thus raising a need for an alternative strategy. Probiotic bioengineering is considered a prevailing approach to enhance the efficacy of probiotics for targeted control of pathogens. Here, the ability of Lactobacillus casei expressing the L. monocytogenes invasion proteins Internalins A and B (inlAB) to prevent infection was investigated. The inlAB operon was cloned and surface-expressed on L. casei resulting in a recombinant strain, Lbc-InlAB, and subsequently, its ability to inhibit adhesion, invasion and translocation of L. monocytogenes through enterocyte-like Caco-2 cells was examined. Cell surface expression of InlAB on the Lbc-InlAB was confirmed by Western blotting and immunofluorescence staining. The Lbc-InlAB strain showed significantly higher (P < 0.0001) adherence, invasion and translocation of Caco-2 cells than the wild-type L. casei strain (Lbc-WT), as well as reduced L. monocytogenes adhesion, invasion and transcellular passage through the cell monolayer than Lbc-WT. Furthermore, pre-exposure of Caco-2 cells to Lbc-InlAB significantly reduced L. monocytogenes-induced cell cytotoxicity and epithelial barrier dysfunction. These results suggest that InlAB-expressing L. casei could be a potential practical approach for prevention of listeriosis.