Engineered calprotectin-sensing probiotics for IBD surveillance in humans

Design of a Continuous GAA-Producing Probiotic as a Potential Mitigator of the Effects of Sleep Deprivation

Creatine is a popular athletic supplement that has also been shown to improve cognitive performance upon sleep deprivation. However, it is rapidly cleared from the gastrointestinal tract a few hours after consumption. Toward providing a persistent creatine dose, we engineered the human probiotic Escherichia coli Nissle (EcN) to produce guanidinoacetic acid (GAA), which is converted to creatine in the liver. We find GAA-producing enzymes present in the human microbiome and compare their activities to known enzymes. Three copies of arginine:glycine amidinotransferase (AGAT) from Actinokineospora terrae are expressed from the genome, and native gcvP, argR, and argA are edited or deleted to improve substrate availability without negatively impacting cell viability. A standard EcN dose (1012 cells) produces 41 ± 7 mg GAA per hour under laboratory conditions. This work demonstrates that a probiotic bacterium can be engineered to produce sustained GAA titers known to impact cognitive performance.

Gut microbiota - bidirectional modulator: role in inflammatory bowel disease and colorectal cancer

The gut microbiota is a diverse ecosystem that significantly impacts human health and disease. This article focuses on how the gut microbiota interacts with inflammatory bowel diseases and colorectal tumors, especially through immune regulation. The gut microbiota plays a role in immune system development and regulation, while the body's immune status can also affect the composition of the microbiota. These microorganisms exert pathogenic effects or correct disease states in gastrointestinal diseases through the actions of toxins and secretions, inhibition of immune responses, DNA damage, regulation of gene expression, and protein synthesis. The microbiota and its metabolites are essential in the development and progression of inflammatory bowel diseases and colorectal tumors. The complexity and bidirectionality of this connection with tumors and inflammation might render it a new therapeutic target. Hence, we explore therapeutic strategies for the gut microbiota, highlighting the potential of probiotics and fecal microbiota transplantation to restore or adjust the microbial community. Additionally, we address the challenges and future research directions in this area concerning inflammatory bowel diseases and colorectal tumors.

Gut Microbiota Modulation in IBD: From the Old Paradigm to Revolutionary Tools

Inflammatory bowel diseases (IBDs) are chronic inflammatory disorders primarily comprising two main conditions: ulcerative colitis and Crohn's disease. The gut microbiota's role in driving inflammation in IBD has garnered significant attention, yet the precise mechanisms through which the microbiota influences IBD pathogenesis remain largely unclear. Given the limited therapeutic options for IBD, alternative microbiota-targeted therapies-including prebiotics, probiotics, postbiotics, and symbiotics-have been proposed. While these approaches have shown promising results, microbiota modulation is still mainly considered an adjunct therapy to conventional treatments, with a demonstrated impact on patients' quality of life. Fecal microbiota transplantation (FMT), already approved for treating Clostridioides difficile infection, represents the first in a series of innovative microbiota-based therapies under investigation. Microbial biotherapeutics are emerging as personalized and cutting-edge tools for IBD management, encompassing next-generation probiotics, bacterial consortia, bacteriophages, engineered probiotics, direct metabolic pathway modulation, and nanotherapeutics. This review explores microbial modulation as a therapeutic strategy for IBDs, highlighting current approaches and examining promising tools under development to better understand their potential clinical applications in managing intestinal inflammatory disorders.

Engineered bacteria launch and control an oncolytic virus

The ability of bacteria and viruses to selectively replicate in tumors has led to synthetic engineering of new microbial therapies. Here we design a cooperative strategy whereby S. typhimurium bacteria transcribe and deliver the Senecavirus A RNA genome inside host cells, launching a potent oncolytic viral infection. "Encapsidated" by bacteria, the viral genome can further bypass circulating antiviral antibodies to reach the tumor and initiate replication and spread within immune mice. Finally, we engineer the virus to require a bacterially delivered protease to achieve virion maturation, demonstrating bacterial control over the virus. This work extends bacterially delivered therapeutics to viral genomes, and shows how a consortium of microbes can achieve a cooperative aim.

Potential applications of engineered bacteria in disease diagnosis and treatment

Probiotics are live microorganisms that confer health benefits to the host when administered in appropriate quantities. This beneficial effect has spurred extensive research in the medical and health fields. With rapid advancements in synthetic biology, the genetic and biological characteristics of a broad array of probiotics have been elucidated. Utilizing these insights, genetic editing technologies now enable the precise modification of probiotics, leading to the development of engineered bacteria. Emerging evidence underscores the significant potential of these engineered bacteria in disease management. This review explores the methodologies for creating engineered bacteria, their preliminary applications in healthcare, and the mechanisms underlying their functions. Engineered bacteria are being developed for roles such as in vivo drug delivery systems, biosensors, and mucosal vaccines, thereby contributing to the treatment, diagnosis, and prevention of conditions including inflammatory bowel disease (IBD), metabolic disorders, cancer, and neurodegenerative diseases. The review concludes by assessing the advantages and limitations of engineered bacteria in the context of disease management.

Genetically engineered bacteria as inflammatory bowel disease therapeutics

Inflammatory bowel disease (IBD) is a chronic and recurrent disease caused by immune response disorders that disrupt the intestinal lumen symbiotic ecosystem and dysregulate mucosal immune functions. Current therapies available for IBD primarily focus on symptom management, making early diagnosis and prompt intervention challenging. The development of genetically engineered bacteria using synthetic biology presents a new strategy for addressing these challenges. In this review, we present recent breakthroughs in the field of engineered bacteria for the treatment and detection of IBD and describe how bacteria can be genetically modified to produce therapeutic molecules or execute diagnostic functions. In particular, we discuss the challenges faced in translating live bacterial therapeutics from bacterial design to delivery strategies for further clinical applications.

The role of the fecal microbiota in inflammatory bowel disease

The understanding of the potential role of the microbiota in the pathogenesis of inflammatory bowel disease (IBD) is ever-evolving. Traditionally, the management of IBD has involved medical therapy and/or surgical intervention. IBD can be characterized by gut microbiome alterations through various pathological processes. Various studies delve into nontraditional methods such as probiotics and fecal microbiota transplant and their potential therapeutic effects. Fecal microbiota transplant involves the delivery of a balanced composition of gut microorganisms into an affected patient via multiple possible routes and methods, while probiotics consist of live microorganisms given via the oral route. At present, neither method is considered first-line treatment, however, fecal microbiota transplant has shown potential success in inducing and maintaining remission in ulcerative colitis. In a study by Kruis and colleagues, Escherichia coli Nissle 1917 was considered to be equivalent to mesalamine in mild ulcerative colitis. Alteration of the microbiome in the management of Crohn's disease is less well defined. Furthermore, variation in the clinical usefulness of 5-aminosalicylic acid medication has been attributed, in part, to its acetylation and inactivation by gut microbes. In summary, our understanding of the microbiome's role is continually advancing, with the possibility of paving the way for personalized medicine based on the microbiome.

The Gut Microbiome Advances Precision Medicine and Diagnostics for Inflammatory Bowel Diseases

The gut microbiome emerges as an integral component of precision medicine because of its signature variability among individuals and its plasticity, which enables personalized therapeutic interventions, especially when integrated with other multiomics data. This promise is further fueled by advances in next-generation sequencing and metabolomics, which allow in-depth high-precision profiling of microbiome communities, their genetic contents, and secreted chemistry. This knowledge has advanced our understanding of our microbial partners, their interaction with cellular targets, and their implication in human conditions such as inflammatory bowel disease (IBD). This explosion of microbiome data inspired the development of next-generation therapeutics for treating IBD that depend on manipulating the gut microbiome by diet modulation or using live products as therapeutics. The current landscape of artificial microbiome therapeutics is not limited to probiotics and fecal transplants but has expanded to include community consortia, engineered probiotics, and defined metabolites, bypassing several limitations that hindered rapid progress in this field such as safety and regulatory issues. More integrated research will reveal new therapeutic targets such as enzymes or receptors mediating interactions between microbiota-secreted molecules that drive or modulate diseases. With the shift toward precision medicine and the enhanced integration of host genetics and polymorphism in treatment regimes, the following key questions emerge: How can we effectively implement microbiomics to further personalize the treatment of diseases like IBD, leveraging proven and validated microbiome links? Can we modulate the microbiome to manage IBD by altering the host immune response? In this review, we discuss recent advances in understanding the mechanism underpinning the role of gut microbes in driving or preventing IBD. We highlight developed targeted approaches to reverse dysbiosis through precision editing of the microbiome. We analyze limitations and opportunities while defining the specific clinical niche for this innovative therapeutic modality for the treatment, prevention, and diagnosis of IBD and its potential implication in precision medicine.

Recent advances in bacteria-based platforms for inflammatory bowel diseases treatment

Inflammatory bowel disease (IBD) is a recurring chronic inflammatory disease. Current treatment strategies are aimed at alleviating clinical symptoms and are associated with gastrointestinal or systemic adverse effects. New delivery strategies are needed for the treatment of IBD. Bacteria are promising biocarriers, which can produce drugs in situ and sense the gut in real time. Herein, we focus on recent studies of engineered bacteria used for IBD treatment and introduce the application of engineered bacteria in the diagnosis. On this basis, the current dilemmas and future developments of bacterial delivery systems are discussed.

Engineered Bacteria for Visualization and Localization of Gastrointestinal Bleeding: A Promising Application

Gastrointestinal bleeding, especially obscure gastrointestinal bleeding (OGIB), is a common and serious clinical emergency with a notable incidence rate. However, the current diagnostic method, gastroscopy, is invasive and often struggles to efficiently detect microhemorrhagic lesions, leading to diagnostic challenges and potential misdiagnoses. Here, we developed an intelligently engineered bacterium utilizing synthetic biology techniques for in vivo localization detection of gastrointestinal bleeding. By constructing three gene circuit modules within E. coli Nissle 1917 for heme recognition, response, and output generation, we have successfully enabled specific heme sensing and real-time optical signal production in vivo. This innovative strategy overcomes the limitations of the existing diagnostic methods, offering a noninvasive and precise means of detecting gastrointestinal bleeding. These advancements hold promise for enhancing diagnostic accuracy and treatment efficacy in future clinical settings within the realm of gastroenterology.

Deconstructing synthetic biology across scales: a conceptual approach for training synthetic biologists

Synthetic biology allows us to reuse, repurpose, and reconfigure biological systems to address society's most pressing challenges. Developing biotechnologies in this way requires integrating concepts across disciplines, posing challenges to educating students with diverse expertise. We created a framework for synthetic biology training that deconstructs biotechnologies across scales-molecular, circuit/network, cell/cell-free systems, biological communities, and societal-giving students a holistic toolkit to integrate cross-disciplinary concepts towards responsible innovation of successful biotechnologies. We present this framework, lessons learned, and inclusive teaching materials to allow its adaption to train the next generation of synthetic biologists.

Accelerating Genetic Sensor Development, Scale-up, and Deployment Using Synthetic Biology

Living cells are exquisitely tuned to sense and respond to changes in their environment. Repurposing these systems to create engineered biosensors has seen growing interest in the field of synthetic biology and provides a foundation for many innovative applications spanning environmental monitoring to improved biobased production. In this review, we present a detailed overview of currently available biosensors and the methods that have supported their development, scale-up, and deployment. We focus on genetic sensors in living cells whose outputs affect gene expression. We find that emerging high-throughput experimental assays and evolutionary approaches combined with advanced bioinformatics and machine learning are establishing pipelines to produce genetic sensors for virtually any small molecule, protein, or nucleic acid. However, more complex sensing tasks based on classifying compositions of many stimuli and the reliable deployment of these systems into real-world settings remain challenges. We suggest that recent advances in our ability to precisely modify nonmodel organisms and the integration of proven control engineering principles (e.g., feedback) into the broader design of genetic sensing systems will be necessary to overcome these hurdles and realize the immense potential of the field.

One small step for stool, one giant leap for IBD surveillance

Inflammatory bowel diseases (IBDs) are chronic conditions in which the digestive tract undergoes cycles of relapsing and remitting inflammatory episodes that cause patients to experience severe abdominal pain, bleeding, and diarrhea. Developing noninvasive and cost-effective surveillance methods that can detect an ensuing disease bout proffers an avenue to improve the quality of life for patients with IBD. Now, a recent report describes an ingenious, economical approach using a rationally designed Escherichia coli strain that can dynamically monitor inflammation inside the mammalian gastrointestinal tract. The ability of the engineered probiotic to specifically discern between dormant and activated inflammatory states of the digestive system demonstrates that living biosensors can be used to monitor health status, thus providing a powerful proof of concept that heralds the arrival of a new age of clinical diagnostics for people living with inflammatory diseases of the gut.

Core microbiome-associated proteins associated with ulcerative colitis interact with cytokines for synergistic or antagonistic effects on gut bacteria

Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is associated with a loss or an imbalance of host-microorganism interactions. However, such interactions at protein levels remain largely unknown. Here, we applied a depletion-assisted metaproteomics approach to obtain in-depth host-microbiome association networks of IBD, where the core host proteins shifted from those maintaining mucosal homeostasis in controls to those involved in inflammation, proteolysis, and intestinal barrier in IBD. Microbial nodes such as short-chain fatty-acid producer-related host-microbial crosstalk were lost or suppressed by inflammatory proteins in IBD. Guided by protein-protein association networks, we employed proteomics and lipidomics to investigate the effects of UC-related core proteins S100A8, S100A9, and cytokines (IL-1β, IL-6, and TNF-α) on gut bacteria. These proteins suppressed purine nucleotide biosynthesis in stool-derived in vitro communities, which was also reduced in IBD stool samples. Single species study revealed that S100A8, S100A9, and cytokines can synergistically or antagonistically alter gut bacteria intracellular and secreted proteome, with combined S100A8 and S100A9 potently inhibiting beneficial Bifidobacterium adolescentis. Furthermore, these inflammatory proteins only altered the extracellular but not intracellular proteins of Ruminococcus gnavus. Generally, S100A8 induced more significant bacterial proteome changes than S100A9, IL-1β, IL-6, and TNF-α but gut bacteria degrade significantly more S100A8 than S100A9 in the presence of both proteins. Among the investigated species, distinct lipid alterations were only observed in Bacteroides vulgatus treated with combined S100A8, S100A9, and cytokines. These results provided a valuable resource of inflammatory protein-centric host-microbial molecular interactions.

Engineered live bacteria as disease detection and diagnosis tools

Sensitive and minimally invasive medical diagnostics are essential to the early detection of diseases, monitoring their progression and response to treatment. Engineered bacteria as live sensors are being developed as a new class of biosensors for sensitive, robust, noninvasive, and in situ detection of disease onset at low cost. Akin to microrobotic systems, a combination of simple genetic rules, basic logic gates, and complex synthetic bioengineering principles are used to program bacterial vectors as living machines for detecting biomarkers of diseases, some of which cannot be detected with other sensing technologies. Bacterial whole-cell biosensors (BWCBs) can have wide-ranging functions from detection only, to detection and recording, to closed-loop detection-regulated treatment. In this review article, we first summarize the unique benefits of bacteria as living sensors. We then describe the different bacteria-based diagnosis approaches and provide examples of diagnosing various diseases and disorders. We also discuss the use of bacteria as imaging vectors for disease detection and image-guided surgery. We conclude by highlighting current challenges and opportunities for further exploration toward clinical translation of these bacteria-based systems.

Systems and synthetic biology-driven engineering of live bacterial therapeutics

The past decade has seen growing interest in bacterial engineering for therapeutically relevant applications. While early efforts focused on repurposing genetically tractable model strains, such as Escherichia coli, engineering gut commensals is gaining traction owing to their innate capacity to survive and stably propagate in the intestine for an extended duration. Although limited genetic tractability has been a major roadblock, recent advances in systems and synthetic biology have unlocked our ability to effectively harness native gut commensals for therapeutic and diagnostic purposes, ranging from the rational design of synthetic microbial consortia to the construction of synthetic cells that execute "sense-and-respond" logic operations that allow real-time detection and therapeutic payload delivery in response to specific signals in the intestine. In this review, we outline the current progress and latest updates on microbial therapeutics, with particular emphasis on gut commensal engineering driven by synthetic biology and systems understanding of their molecular phenotypes. Finally, the challenges and prospects of engineering gut commensals for therapeutic applications are discussed.