Cold Exposure and Oral Delivery of GLP-1R Agonists by an Engineered Probiotic Yeast Strain Have Antiobesity Effects in Mice

Advanced microbiome therapeutics for oral delivery of peptides and proteins: Advances, challenges, and opportunities

Peptide and protein medicines have changed the therapeutic landscape for many diseases, yet oral delivery remains a significant challenge due to enzymatic degradation, instability, and poor permeability in the gastrointestinal tract. Advanced Microbiome Therapeutics (AMTs) could overcome some of these barriers by producing and releasing therapeutic peptides directly in the gastrointestinal tract. AMTs can localize peptide production at the site of absorption, providing either sustained or controlled release while potentially reducing side effects associated with systemic administration. Here, this review assesses the status of AMTs for oral peptide delivery and discusses the potential integration of permeation enhancers, mucoadhesive systems, and receptor-mediated transport strategies to improve oral bioavailability further. Combining these approaches could pave the way for more widespread oral delivery strategies for peptide and protein medicines.

Enabling technologies for in situ biomanufacturing using probiotic yeast

Saccharomyces boulardii (Sb) is a Generally Regarded As Safe (GRAS) probiotic yeast currently used to alleviate symptoms from various gastrointestinal diseases. Sb is a promising platform for probiotic and biotherapeutic engineering as it is the only probiotic eukaryote and carries with it a unique set of advantages compared to bacterial strains, including resistance to phage, high protein secretion abilities, and intrinsic resistance to antibiotics. While engineered Sb has not been studied as extensively as its close relative Saccharomyces cerevisiae (Sc), many genetic engineering tools developed for Sc have also shown promise in Sb. In this review, we address recent research to develop tools for genetic engineering, colonization modulation, biomarker sensing, and drug production in Sb. Ongoing efforts, especially those that overcome gut-specific challenges to engineered performance, are highlighted as they advance this chassis as a scalable platform for treating gastrointestinal diseases.

Enhancing intestinal absorption of a macromolecule through engineered probiotic yeast in the murine gastrointestinal tract

Oral administration of therapeutic peptides is limited by poor intestinal absorption. Use of engineered microorganisms as drug delivery vehicles can overcome the challenges faced by conventional delivery methods. The potential of engineered microorganisms to act synergistically with the therapeutics they deliver opens new horizons for noninvasive treatment modalities. This study engineered a probiotic yeast, Saccharomyces boulardii, to produce cell-penetrating peptides (CPPs) in situ for enhanced intestinal permeability. Four CPPs were integrated into the yeast chromosome: RRL helix, Shuffle, Penetramax, and PN159. In vitro tests on a Caco-2 cell model showed that three CPP-producing strains increased permeability without causing permanent damage. In vivo experiments on mice revealed that Sb PN159 administration over 10 days significantly increased FITC-dextran translocation into the bloodstream without causing inflammation. This study demonstrates, for the first time, the ability of an engineered microorganism to modulate host permeability for improved intestinal absorption of a macromolecule.

The Functions of Major Gut Microbiota in Obesity and Type 2 Diabetes

Background: Gut microbiomes play a vital role in maintaining whole-body metabolic homeostasis. It has gained significant attention in recent years due to advancements in genome sequencing technologies and a deeper understanding of its relationship with obesity. However, the specific ways in which different microorganisms directly or indirectly influence host obesity, as well as the underlying mechanisms, remain uncertain because of the complexity of gut microbiota composition. Methods: In this review, we summarize the roles of the major gut microbiota phyla such as Bacteroidetes, Firmicutes, Proteobacteria, and Verrucomicrobia in obesity and type 2 diabetes based on studies published in the past five years on PubMed and Google Scholar. The current therapeutic strategies associated with gut microbiota are also explored from clinical trials, and challenges and future directions are discussed. Results and Conclusions: This review will provide a deeper understanding of the functions of major gut microbiota in obesity and type 2 diabetes, which could lead to more individualized and effective treatments for metabolic diseases.

Development of a Dihydrofolate Reductase Selection System for Saccharomyces boulardii

Saccharomyces boulardii, the only commercially available probiotic yeast, has gained attention as a recombinant live biotherapeutic product (rLBP) empowered with the expression of heterologous therapeutic proteins for treating gastrointestinal diseases. However, the genetic modification of S. boulardii intended for clinical use is hindered by regulatory and technical challenges. In this study, we developed a dihydrofolate reductase (DHFR)-based selection system as an innovative alternative to traditional auxotrophic selection strategies for engineering S. boulardii. The DHFR selection system overcame inherent resistance of the yeast to methotrexate (MTX) by incorporating sulfanilamide, a dihydrofolate synthesis inhibitor, to enhance selection efficiency. The system demonstrated robust functionality, enabling the efficient screening of high-expression clones and tunable expression of therapeutic proteins, such as cytokines and antibodies, by modulating MTX concentrations. Furthermore, the yeast's endogenous DHFR homolog, DFR1, was shown to be a viable selection marker, providing greater host compatibility while maintaining functionality compared to DHFR. This selection system avoids reliance on foreign antibiotic selection markers and the construction of auxotrophic strains, thus simplifying engineering and allowing for a tunable protein expression. These advancements establish the DHFR/DFR1 selection system as a robust and versatile platform for developing S. boulardii-based live biotherapeutics.

A yeast-based oral therapeutic delivers immune checkpoint inhibitors to reduce intestinal tumor burden

Engineered probiotics are an emerging platform for in situ delivery of therapeutics to the gut. Herein, we developed an orally administered, yeast-based therapeutic delivery system to deliver next-generation immune checkpoint inhibitor (ICI) proteins directly to gastrointestinal tumors. We engineered Saccharomyces cerevisiae var. boulardii (Sb), a probiotic yeast with high genetic tractability and innate anticancer activity, to secrete "miniature" antibody variants that target programmed death ligand 1 (Sb_haPD-1). When tested in an ICI-refractory colorectal cancer (CRC) mouse model, Sb_haPD-1 significantly reduced intestinal tumor burden and resulted in significant shifts to the immune cell profile and microbiome composition. This oral therapeutic platform is modular and highly customizable, opening new avenues of targeted drug delivery that can be applied to treat a myriad of gastrointestinal malignancies.

Engineering Saccharomyces cerevisiae for medical applications

BACKGROUND

During the last decades, the advancements in synthetic biology opened the doors for a profusion of cost-effective, fast, and ecologically friendly medical applications priorly unimaginable. Following the trend, the genetic engineering of the baker's yeast, Saccharomyces cerevisiae, propelled its status from an instrumental ally in the food industry to a therapy and prophylaxis aid.

MAIN TEXT

In this review, we scrutinize the main applications of engineered S. cerevisiae in the medical field focusing on its use as a cell factory for pharmaceuticals and vaccines, a biosensor for diagnostic and biomimetic assays, and as a live biotherapeutic product for the smart in situ treatment of intestinal ailments. An extensive view of these fields' academic and commercial developments as well as main hindrances is presented.

CONCLUSION

Although the field still faces challenges, the development of yeast-based medical applications is often considered a success story. The rapid advances in synthetic biology strongly support the case for a future where engineered yeasts play an important role in medicine.

Advanced microbiome therapeutics as a novel modality for oral delivery of peptides to manage metabolic diseases

The rising prevalence of metabolic diseases calls for innovative treatments. Peptide-based drugs have transformed the management of conditions such as obesity and type 2 diabetes. Yet, challenges persist in oral delivery of these peptides. This review explores the potential of 'advanced microbiome therapeutics' (AMTs), which involve engineered microbes for delivery of peptides in situ, thereby enhancing their bioavailability. Preclinical work on AMTs has shown promise in treating animal models of metabolic diseases, including obesity, type 2 diabetes, and metabolic dysfunction-associated steatotic liver disease. Outstanding challenges toward realizing the potential of AMTs involve improving peptide expression, ensuring predictable colonization control, enhancing stability, and managing safety and biocontainment concerns. Still, AMTs have potential for revolutionizing the treatment of metabolic diseases, potentially offering dynamic and personalized novel therapeutic approaches.

Peptide GLP-1 receptor agonists: From injection to oral delivery strategies

Peptide glucagon-like peptide-1 receptor agonists (GLP-1RAs) are effective drugs for treating type 2 diabetes (T2DM) and have been proven to benefit the heart and kidney. Apart from oral semaglutide, which does not require injection, other peptide GLP-1RAs need to be subcutaneously administered. However, oral semaglutide also faces significant challenges, such as low bioavailability and frequent gastrointestinal discomfort. Thus, it is imperative that advanced oral strategies for peptide GLP-1RAs need to be explored. This review mainly compares the current advantages and disadvantages of various oral delivery strategies for peptide GLP-1RAs in the developmental stage and discusses the latest research progress of peptide GLP-1RAs, providing a useful guide for the development of new oral peptide GLP-1RA drugs.

New Insights into Chronic Pancreatitis: Potential Mechanisms Related to Probiotics

Chronic pancreatitis is a progressive fibroinflammatory disorder with no currently satisfactory treatment. Emerging evidence suggests an association between gut microbial dysbiosis and chronic pancreatitis. Although direct causative evidence is lacking, it is hypothesized that the gut microbiota may play a pivotal role in modulating pancreatic function via the gut-pancreas axis. Thus, modulating the gut microbiota through the administration of probiotics or prebiotics may alleviate pancreatic disorders. In this review, we first propose the potential mechanisms by which specific probiotics or prebiotics may ameliorate chronic pancreatitis, including the alleviation of small intestinal bacterial overgrowth (SIBO), the facilitation of short-chain fatty acids' (SCFAs) production, and the activation of glucagon-like peptide-1 receptors (GLP-1Rs) in the pancreas. Since there are currently no probiotics or prebiotics used for the treatment of chronic pancreatitis, we discuss research in other disease models that have used probiotics or prebiotics to modulate pancreatic endocrine and exocrine functions and prevent pancreatic fibrosis. This provides indirect evidence for their potential application in the treatment of chronic pancreatitis. We anticipate that this research will stimulate further investigation into the gut-pancreas axis and the potential therapeutic value of probiotics and prebiotics in chronic pancreatitis.

Programming Probiotics: Diet-Responsive Gene Expression and Colonization Control in Engineered S. boulardii

Saccharomyces boulardii (Sb) is an emerging probiotic chassis for delivering biomolecules to the mammalian gut, offering unique advantages as the only eukaryotic probiotic. However, precise control over gene expression and gut residence time in Sb have remained challenging. To address this, we developed five ligand-responsive gene expression systems and repaired galactose metabolism in Sb, enabling inducible gene expression in this strain. Engineering these systems allowed us to construct AND logic gates, control the surface display of proteins, and turn on protein production in the mouse gut in response to dietary sugar. Additionally, repairing galactose metabolism expanded Sb's habitat within the intestines and resulted in galactose-responsive control over gut residence time. This work opens new avenues for precise dosing of therapeutics by Sb via control over its in vivo gene expression levels and localization within the gastrointestinal tract.

Saccharomyces boulardii promoters for control of gene expression in vivo

BACKGROUND

Interest in the use of engineered microbes to deliver therapeutic activities has increased in recent years. The probiotic yeast Saccharomyces boulardii has been investigated for production of therapeutics in the gastrointestinal tract. Well-characterised promoters are a prerequisite for robust therapeutic expression in the gut; however, S. boulardii promoters have not yet been thoroughly characterised in vitro and in vivo.

RESULTS

We present a thorough characterisation of the expression activities of 12 S. boulardii promoters in vitro in glucose, fructose, sucrose, inulin and acetate, under both aerobic and anaerobic conditions, as well as in the murine gastrointestinal tract. Green fluorescent protein was used to report on promoter activity. Promoter expression was found to be carbon-source dependent, with inulin emerging as a favourable carbon source. Furthermore, relative promoter expression in vivo was highly correlated with expression in sucrose (R = 0.99).

CONCLUSIONS

These findings provide insights into S. boulardii promoter activity and aid in promoter selection in future studies utilising S. boulardii to produce therapeutics in the gut.