Intestinal Engineered Probiotics as Living Therapeutics: Chassis Selection, Colonization Enhancement, Gene Circuit Design, and Biocontainment

Abstract

Intestinal probiotics are often used for the in situ treatment of diseases, such as metabolic disorders, tumors, and chronic inflammatory infections. Recently, there has been an increased emphasis on intelligent, customized treatments with a focus on long-term efficacy; however, traditional probiotic therapy has not kept up with this trend. The use of synthetic biology to construct gut-engineered probiotics as live therapeutics is a promising avenue in the treatment of specific diseases, such as phenylketonuria and inflammatory bowel disease. These studies generally involve a series of fundamental design issues: choosing an engineered chassis, improving the colonization ability of engineered probiotics, designing functional gene circuits, and ensuring the safety of engineered probiotics. In this review, we summarize the relevant past research, the progress of current research, and discuss the key issues that restrict the widespread application of intestinal engineered probiotic living therapeutics.

Armored probiotics for oral delivery

“…In recent years, many probiotic adhesion strategies have been proposed to this end. 119 For example, inspired by adhesins that promote bacterial colonization, Anselmo and colleagues attached streptomycin-conjugated anti-MUC2 antibody on biotinylated EcN to achieve targeted adhesion, which significantly increased the colonization efficiency of EcN and prolonged their colonization time (Figure 6A,B). 120 Shapiro and colleagues modified magnetic nanoparticles on the surface of probiotics using the biotin-streptavidin method and enhanced the localization and colonization of oral probiotics with the aid of micromagnet amplifiers and an external magnetic field (Figure 6C,D).…”

Synthetic biology in multicellular organisms: Opportunities in nematodes

“…The use of organisms for therapeutic purposes is not limited to preclinical testing, but includes direct applications as therapeutic agents in what is known as live biotherapeutics. Such approaches can use engineered or non‐engineered organisms, mainly bacteria, which are typically delivered to the gut, or topically, or via injection (Charbonneau et al, 2020; Chernikova et al, 2022; FDA, 2016; Huang et al, 2022). Currently, such organisms are in clinical trials to treat solid tumors, gastrointestinal inflammation, or metabolic disorders (hyperammonemia or phenylketonuria) among others (Charbonneau et al, 2020).…”

“…Both T. suis and N. americanus transition through the intestine, and therefore are candidates to be engineered for treatment of conditions such as Crohn's disease, irritable bowel, or digestive tract cancer. Parasitic nematodes should outperform bacteria in delivering biotherapeutics in the gut as they can easily colonize the intestinal tract of the host without competition with endogenous bacteria (Huang et al, 2022). The main issue so far is conflicting results regarding efficacy.…”

“…The main issue so far is conflicting results regarding efficacy. However, this could be overcome by engineering nematodes to secrete therapeutic molecules, as has been done with yeast (Liu, Grote, et al, 2020; Liu, Chang, et al, 2020) or bacteria (Huang et al, 2022; Ma et al, 2021), though as previously discussed, the state‐of‐the‐art in engineering parasitic nematodes lags behind that in unicellular models. Furthermore, survival of the model organism C. elegans for prolonged periods inside the host is problematic due to the harsh conditions compared to the native environment.…”

“…However, this could be overcome by engineering nematodes to secrete therapeutic molecules, as has been done with yeast (Liu, Grote, et al, 2020;Liu, Chang, et al, 2020) or bacteria (Huang et al, 2022;Ma et al, 2021), though as previously discussed, the state-of-the-art in engineering parasitic nematodes lags behind that in unicellular models. Furthermore, survival of the model organism C.…”