Genome Editing of Food-Grade Lactobacilli To Develop Therapeutic Probiotics

Abstract

For thousands of years, lactic acid bacteria (LAB) have been interwoven with our food supply. The earliest evidence of milk use dates back to 7,000 years BCE (1), while cheeses were produced as early as 6,000 years BCE (2). Advances in our understanding of the microbial world in the past couple of centuries have enabled microbiology-based food manufacturing on an industrial scale. Not only are LAB used to ferment dairy products, but they are also applied to pickle vegetables, to cure meats, and to produce alcoholic beverages such as wine and sake (3, 4). This long history of safe consumption led to the consideration that many LAB strains are Generally Recognized As Safe (GRAS). As early as 1906, LAB were linked to the promotion of human health. The Russian Nobel laureate Élie Metchnikoff hypothesized that ingestion of yogurt prolonged life in Eastern European populations by reducing "putrefying" [sic] bacteria. His linkage of the perceived longevity of the Eastern European populations with consumption of fermented dairy products (5) made him the grandfather of modern probiotics. Probiotics are defined as "live microorganisms, which when administrated in adequate amounts, confer a health benefit to the host" (6). Metchnikoff's probiotic theory of life prolongation was never directly tested, and researchers reported in 1924 that LAB present in yogurt, specifically Lactobacillus bulgaricus, most likely do not reduce "putrifying" bacteria in the intestine because L. bulgaricus did not survive gastrointestinal (GI) transit (7). Other groups challenged this finding. Elli et al. demonstrated that both Streptococcus thermophilus and L. bulgaricus were present in human feces after yogurt ingestion (8). Regardless, Metchnikoff's theory was born that bacteria could be health-promoting through modifying the composition of the bacterial population that inhabits our intestine. In 2017, this translates into the use of (tailored) probiotics to modify the gut microbiota to promote human health. Today we can engineer LAB in general, and recent advances have made it possible to engineer select probiotic strains in a high-throughput manner. Also, we have an increased appreciation and understanding of the role of the gut microbiota in health and disease. Thus, the contemporary application of tailored probiotics to promote human health Bugs as Drugs: Therapeutic Microbes for the Prevention and Treatment of Disease

Hsp65-Producing Lactococcocus lactis Prevents Antigen-Induced Arthritis in Mice

“…Hsp65-producing L. lactis in the present format is still not suitable for human use because of the antibiotic resistant gene and the requirement for xylose for Hsp65 induction. However, novel recombinant technologies that makes possible the expression of exogenous proteins in probiotics used for dairy products without the use of antibiotics and exogenous inducing agents are available (62)(63)(64)(65)(66). A version of Hsp65-producing L. lactis with such features would be suitable for clinical studies.…”

Genetically Engineered Probiotics and Therapies Applications

“…Regarding immunomodulation, teichoic acids (TAs) present in lactobacilli cell walls, activate immunological responses in the host by stimulating dendritic cells and affect the adhesion of bacteria to host cells (Fig. 1A) (8). Genetic engineering of lactobacilli could alter these cell wall components suggesting better survival times in the host by improving adhesion.…”

“…Genetic engineering of lactobacilli could alter these cell wall components suggesting better survival times in the host by improving adhesion. In addition, another study on lactobacilli TAs focused on modifying proinflammatory responses by integrating a knockout vector in the gene responsible for D-alanylation of TAs in order to acquire antiinflammatory responses 8 . Such discovery could be useful in colon cancer prevention which occurs due to chronic inflammation in the colon (Fig.…”

Beyond Structure: Defining the Function of the Gut Using Omic Approaches for Rational Design of Personalized Therapeutics

“…We have designed a novel platform to identify, engineer, optimize, and biochemically characterize new BSHs capable of altering conjugated bile acids and to define their ability to influence the bile acid pool, gut microbiota, and host physiology in vivo . In order to do this, we also need a robust organism for delivery and expression in vivo and have selected Lactobacillus as our model system ( 11 ). This work will result in the construction of genetically modified Lactobacillus strains for therapeutic interventions to rationally alter the bile acid pool in the gut, modulating the gut microbiota and host physiology in GI and metabolic diseases.…”