A red light-controlled probiotic bio-system for in-situ gut-brain axis regulation

A dual light-controlled co-culture system enables the regulation of population composition

With the development of metabolic engineering, increasing requirements for efficient microbial biosynthesis call for establishment of multi-strain co-culture system. Dynamic regulation of population ratios is crucial for optimizing bioproduction performance. Optogenetic systems with high universality and flexibility have the potential to realize dynamic control of population proportion. In this study, we utilized an optimized chromatic acclimation sensor/regulator (CcaS/R) system and a blue light-activated YF1-FixJ-PhlF system as induction modules. A pair of orthogonal quorum sensing systems and a toxin-antitoxin system were employed as communication module and effector module, respectively. By integrating these modules, we developed a dual light-controlled co-culture system that enables dynamic regulation of population ratios. This co-culture system provides a universal toolkit for applications in metabolic engineering and synthetic biology.

Photosensitive Biomimetic Nanomedicine-Mediated Recombination of Adipose Microenvironments for Antiobesity Therapy

Obesity-induced insulin resistance is a hallmark of metabolic syndrome, and chronic low-grade inflammation links obesity to insulin resistance through the activation of tissue-infiltrating immune cells. Current treatments are lacking in efficacy and immunosuppression. Therefore, novel therapies are needed to prevent chronic inflammation and alleviate obesity-related insulin resistance. In this work, novel red light-responsive biomimetic nanoparticles (RSCP NPs) are reported to perform targeted delivery of multiple drugs and effectively reduce nonspecific enrichment. These results showed that the dual-targeting and multiple-signaling response (red light signaling and different pH microenvironments) of the RSCP NPs enabled the precise delivery of astaxanthin (Asta) and rosiglitazone (Rosi) to M1-like macrophages and white adipocytes, respectively, to alleviate the low-grade inflammation of white adipose tissue (WAT) and promote white adipocyte browning. Moreover, RSCP NPs-mediated Asta and Rosi treatment robustly alleviated insulin resistance and other metabolic disorders in the obese animal models (high-fat diet (HFD)-induced or genetically obese mice). Overall, this study provides a theoretical and practical basis for the development and application of novel drug delivery systems for metabolic diseases by elucidating the synergistic long-term targeting mechanism and target molecule stability of red light-sensitive bionic nanodrug delivery systems.

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.

Empowering bacteria with light: Optogenetically engineered bacteria for light-controlled disease theranostics and regulation

Bacterial therapy has emerged as a promising approach for disease treatment due to its environmental sensitivity, immunogenicity, and modifiability. However, the clinical application of engineered bacteria is limited by differences of expression levels in patients and possible off-targeting. Optogenetics, which combines optics and genetics, offers key advantages such as remote controllability, non-invasiveness, and precise spatiotemporal control. By utilizing optogenetic tools, the behavior of engineered bacteria can be finely regulated, enabling on-demand control of the dosage and location of their therapeutic products. In this review, we highlight the latest advancements in the optogenetic engineering of bacteria for light-controlled disease theranostics and therapeutic regulation. By constructing a three-dimensional analytical framework of "sense-produce-apply", we begin by discussing the key components of bacterial optogenetic systems, categorizing them based on their photosensitive protein response to blue, green, and red light. Next, we introduce innovative light-producing tools that extend beyond traditional light sources. Then, special emphasis is placed on the biomedical applications of optogenetically engineered bacteria in treating diseases such as cancer, intestinal inflammation and systemic disease regulation. Finally, we address the challenges and future prospects of bacterial optogenetics, outlining potential directions for enhancing the safety and efficacy of light-controlled bacterial therapies. This review aims to provide insights and strategies for researchers working to advance the application of optogenetically engineered bacteria in drug delivery, precision medicine and therapeutic regulation.

Bacterial Autonomous Intelligent Microrobots for Biomedical Applications

Micro/nanorobots are being increasingly utilized as new diagnostic and therapeutic platforms in the biomedical field, enabling remote navigation to hard-to-reach tissues and the execution of various medical procedures. Although significant progress has been made in the development of biomedical micro/nanorobots, how to achieve closed-loop control of them from sensing, memory, and precise trajectory planning to feedback to carry out biomedical tasks remains a challenge. Bacteria with self-propulsion and autonomous intelligence properties are well suited to be engineered as microrobots to achieve closed-loop control for biomedical applications. By virtue of synthetic biology, bacterial microrobots possess an expanded genetic toolbox, allowing them to load input sensors to respond or remember external signals. To achieve accurate control in the complex physiological environment, the development of bacterial microrobots should be matched with the corresponding control system design. In this review, a detailed summary of the sensing and control mechanisms of bacterial microrobots is presented. The engineering and applications of bacterial microrobots in the biomedical field are highlighted. Their future directions of bacterial autonomous intelligent microrobots for precision medicine are forecasted.

Oral delivery of therapeutic proteins by engineered bacterial type zero secretion system

Genetically engineered commensal bacteria are promising living drugs, however, their therapeutic molecules are frequently confined to their colonization sites. Herein, we report an oral protein delivery technology utilizing an engineered bacterial type zero secretion system (T0SS) via outer membrane vesicles (OMVs). We find that OMVs produced in situ by Escherichia coli Nissle 1917 (EcN) can penetrate the intact gut epithelial barrier to enter the circulation and that epithelial transcytosis involves pinocytosis and dynamin-dependent pathways. EcN is engineered to endogenously load various enzymes into OMVs, and the secreted enzyme-loaded OMVs are able to stably catalyze diverse detoxification reactions against digestive fluid and even enter the circulation. Using hyperuricemic mice and uricase delivery as a demonstration, we demonstrate that the therapeutic efficacy of our engineered EcN with a modified T0SS outperforms that with a direct protein secretion apparatus. The enzyme-loaded OMVs also effectively detoxify human serum samples, highlighting the potential for the clinical treatment of metabolic disorders.

Utilizing Engineered Bacteria as "Cell Factories" In Vivo for Intracellular RNA-Loaded Outer Membrane Vesicles' Self-Assembly in Tumor Treatment

Delivery systems play a crucial role in RNA therapy. However, the current RNA delivery system involves complex preparation and transport processes, requiring RNA preassembly in vitro, transportation at low temperatures throughout, and possibly multiple injections for improved therapeutic efficacy. To address these challenges, we developed a simple and efficient RNA delivery system. This system only requires the injection of engineered bacteria, which serve as in vivo "cell factories" for continuous production of the target RNA. The RNA can self-assemble with engineered bacteria's outer membrane vesicles (OMVs), facilitating in vivo RNA delivery. Experimental results demonstrated that this system allowed effective delivery with excellent stability and continuity for various types of RNA, including mRNA, miRNA, and siRNA. And the relative abundance of target RNA in the OMVs was 104-107 times higher than that in the mock group. We took the delivery of PD-L1 siRNA for tumor treatment as an example and found that this system could effectively downregulate the gene expression of PD-L1 by approximately twofold. Notably, a single injection of engineered bacteria achieved a significant tumor suppression of 49.37% in vivo. This research provides promising insights into the RNA delivery system for tumor therapy.

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.

Synthetic Biology-Driven Microbial Therapeutics for Disease Treatment

The human microbiome, consisting of microorganisms that coexist symbiotically with the body, impacts health from birth. Alterations in gut microbiota driven by factors such as diet and medication can contribute to diseases beyond the gut. Synthetic biology has paved the way for engineered microbial therapeutics, presenting promising treatments for a variety of conditions. Using genetically encoded biosensors and dynamic regulatory tools, engineered microbes can produce and deliver therapeutic agents, detect biomarkers, and manage diseases. This review organizes engineered microbial therapeutics by disease type, emphasizing innovative strategies and recent advancements. The scope of diseases includes gastrointestinal disorders, cancers, metabolic diseases, infections, and other ailments. Synthetic biology facilitates precise targeting and regulation, improving the efficacy and safety of these therapies. With promising results in animal models, engineered microbial therapeutics provide a novel alternative to traditional treatments, heralding a transformative era in diagnostics and treatment for numerous diseases.

What We Know About the Actual Role of Traditional Probiotics in Health and Disease

The complex relationship between probiotics and human health goes beyond their traditional function in gut health, generating considerable interest for their broad potential in disease treatment. This review explores the various functions of probiotics, highlighting their impact on the immune system, their benefits for gut and oral health, their effects on metabolic and neurological disorders, and their emerging potential in cancer therapy. We give significant importance to studying the effects of probiotics on the gut-brain axis, revealing new and non-invasive therapeutic approaches for complex neurological disorders. In addition, we expand the discussion to encompass the impact of probiotics on the gut-liver and gut-lung axes, recognizing their systemic effects and potential in treating respiratory and hepatic conditions. The use of probiotic "cocktails" to improve cancer immunotherapy outcomes indicates a revolutionary approach to oncological treatments. The review explores the specific benefits associated with various strains and the genetic mechanisms that underlie them. This study sets the stage for precision medicine, where probiotic treatments can be tailored to meet the unique needs of each patient. Recent developments in delivery technologies, including microencapsulation and nanotechnology, hold great potential for enhancing the effectiveness and accuracy of probiotic applications in therapeutic settings. This study provides a strong basis for future scientific research and clinical use, promoting the incorporation of probiotics into treatment plans for a wide range of diseases. This expands our understanding of the potential benefits of probiotics in modern medicine.

Advanced Bioinspired Multifunctional Platforms Focusing on Gut Microbiota Regulation

Gut microbiota plays a crucial role in maintaining host homeostasis, impacting the progression and therapeutic outcomes of diseases, including inflammatory bowel disease, cancer, hepatic conditions, obesity, cardiovascular pathologies, and neurologic disorders, via immune, neural, and metabolic mechanisms. Hence, the gut microbiota is a promising target for disease therapy. The safety and precision of traditional microbiota regulation methods remain a challenge, which limits their widespread clinical application. This limitation has catalyzed a shift toward the development of multifunctional delivery systems that are predicated on microbiota modulation. Guided by bioinspired strategies, an extensive variety of naturally occurring materials and mechanisms have been emulated and harnessed for the construction of platforms aimed at the monitoring and modulation of gut microbiota. This review outlines the strategies and advantages of utilizing bioinspired principles in the design of gut microbiota intervention systems based on traditional regulation methods. Representative studies on the development of bioinspired therapeutic platforms are summarized, which are based on gut microbiota modulation to confer multiple pharmacological benefits for the synergistic management of diseases. The prospective avenues and inherent challenges associated with the adoption of bioinspired strategies in the refinement of gut microbiota modulation platforms are proposed to augment the efficacy of disease treatment.

Biomedical engineering utilizing living photosynthetic cyanobacteria and microalgae: Current status and future prospects

Cyanobacteria are the only prokaryotes capable of performing oxygenic photosynthesis on Earth. Besides their traditional roles serving as primary producers, cyanobacteria also synthesize abundant secondary metabolites including carotenoids, alkaloids, peptides, which have been reported to possess medicinal potentials. More importantly, the advancement of synthetic biology technology has further expanded their potential biomedical applications especially using living/engineered cyanobacteria, providing promising and attractive strategies for future disease treatments. To improve the understanding and to facilitate future applications, this review aims to discuss the current status and future prospects of cyanobacterial-based biomedical engineering. Firstly, specific properties of cyanobacteria related with biomedical applications like their natural products of bioactive compounds and heavy metal adsorption were concluded. Subsequently, based on these properties of cyanobacteria, we discussed the progress of their applications in various disease models like hypoxia microenvironment alleviation, wound healing, drug delivery, and so on. Finally, the future prospects including further exploration of cyanobacteria secondary metabolites, the integration of bioactive compounds synthesized by cyanobacteria in situ with medical diagnosis and treatment, and the optimization of in vivo application were critically presented. The review will promote the studies related with cyanobacteria-based biomedical engineering and its practical application in clinical trials in the future.

Nano-optogenetics for Disease Therapies

Optogenetic, known as the method of 21 centuries, combines optic and genetic engineering to precisely control photosensitive proteins for manipulation of a broad range of cellular functions, such as flux of ions, protein oligomerization and dissociation, cellular intercommunication, and so on. In this technique, light is conventionally delivered to targeted cells through optical fibers or micro light-emitting diodes, always suffering from high invasiveness, wide-field illumination facula, strong absorption, and scattering by nontargeted endogenous substance. Light-transducing nanomaterials with advantages of high spatiotemporal resolution, abundant wireless-excitation manners, and easy functionalization for recognition of specific cells, recently have been widely explored in the field of optogenetics; however, there remain a few challenges to restrain its clinical applications. This review summarized recent progress on light-responsive genetically encoded proteins and the myriad of activation strategies by use of light-transducing nanomaterials and their disease-treatment applications, which is expected for sparking helpful thought to push forward its preclinical and translational uses.

Lighting the way: recent developments and applications in molecular optogenetics

Molecular optogenetics utilizes genetically encoded, light-responsive protein switches to control the function of molecular processes. Over the last two years, there have been notable advances in the development of novel optogenetic switches, their utilization in elucidating intricate signaling pathways, and their progress toward practical applications in biotechnological processes, material sciences, and therapeutic applications. In this review, we discuss these areas, offer insights into recent developments, and contemplate future directions.

Ultrasound-visible engineered bacteria for tumor chemo-immunotherapy

Our previous work developed acoustic response bacteria, which enable the precise tuning of transgene expression through ultrasound. However, it is still difficult to visualize these bacteria in order to guide the sound wave to precisely irradiate them. Here, we develop ultrasound-visible engineered bacteria and chemically modify them with doxorubicin (DOX) on their surfaces. These engineered bacteria (Ec@DIG-GVs) can produce gas vesicles (GVs), providing a real-time imaging guide for remote hyperthermia high-intensity focused ultrasound (hHIFU) to induce the expression of the interferon (IFN)-γ gene. The production of IFN-γ can kill tumor cells, induce macrophage polarization from the M2 to the M1 phenotype, and promote the maturation of dendritic cells. DOX can be released in the acidic tumor microenvironment, resulting in immunogenic cell death of tumor cells. The concurrent effects of IFN-γ and DOX activate a tumor-specific T cell response, producing the synergistic anti-tumor efficacy. Our study provides a promising strategy for bacteria-mediated tumor chemo-immunotherapy.

Minimizing endogenous cryptic plasmids to construct antibiotic-free expression systems for Escherichia coli Nissle 1917

The probiotic bacterium Escherichia coli Nissle 1917 (EcN) holds significant promise for use in clinical and biological industries. However, the reliance on antibiotics to maintain plasmid-borne genes has overshadowed its benefits. In this study, we addressed this issue by engineering the endogenous cryptic plasmids pMUT1 and pMUT2. The non-essential elements were removed to create more stable derivatives pMUT1NR△ and pMUT2HBC△. Synthetic promoters by integrating binding motifs on sigma factors were further constructed and applied for expression of Bacteroides thetaiotaomicron heparinase III and the biosynthesis of ectoine. Compared to traditional antibiotic-dependent expression systems, our newly constructed antibiotic-free expression systems offer considerable advantages for clinical and synthetic biology applications.

Microbiota-gut-brain axis and its therapeutic applications in neurodegenerative diseases

The human gastrointestinal tract is populated with a diverse microbial community. The vast genetic and metabolic potential of the gut microbiome underpins its ubiquity in nearly every aspect of human biology, including health maintenance, development, aging, and disease. The advent of new sequencing technologies and culture-independent methods has allowed researchers to move beyond correlative studies toward mechanistic explorations to shed light on microbiome-host interactions. Evidence has unveiled the bidirectional communication between the gut microbiome and the central nervous system, referred to as the "microbiota-gut-brain axis". The microbiota-gut-brain axis represents an important regulator of glial functions, making it an actionable target to ameliorate the development and progression of neurodegenerative diseases. In this review, we discuss the mechanisms of the microbiota-gut-brain axis in neurodegenerative diseases. As the gut microbiome provides essential cues to microglia, astrocytes, and oligodendrocytes, we examine the communications between gut microbiota and these glial cells during healthy states and neurodegenerative diseases. Subsequently, we discuss the mechanisms of the microbiota-gut-brain axis in neurodegenerative diseases using a metabolite-centric approach, while also examining the role of gut microbiota-related neurotransmitters and gut hormones. Next, we examine the potential of targeting the intestinal barrier, blood-brain barrier, meninges, and peripheral immune system to counteract glial dysfunction in neurodegeneration. Finally, we conclude by assessing the pre-clinical and clinical evidence of probiotics, prebiotics, and fecal microbiota transplantation in neurodegenerative diseases. A thorough comprehension of the microbiota-gut-brain axis will foster the development of effective therapeutic interventions for the management of neurodegenerative diseases.

Unlocking the potential of optogenetics in microbial applications

Optogenetics is a powerful approach that enables researchers to use light to dynamically manipulate cellular behavior. Since the first published use of optogenetics in synthetic biology, the field has expanded rapidly, yielding a vast array of tools and applications. Despite its immense potential for achieving high spatiotemporal precision, optogenetics has predominantly been employed as a substitute for conventional chemical inducers. In this short review, we discuss key features of microbial optogenetics and highlight applications for understanding biology, cocultures, bioproduction, biomaterials, and therapeutics, in which optogenetics is more fully utilized to realize goals not previously possible by other methods.

Advice to People with Parkinson's in My Clinic: Probiotics and Prebiotics

There is increasing evidence that microbial-based therapies can be useful in people with Parkinson's disease (PD). In this viewpoint, we provide a state-of-the-art review of the clinical and pre-clinical evidence for probiotics and prebiotics in PD. Currently, short-term clinical studies, including double-blind placebo-controlled randomized clinical trials, have demonstrated safety, and efficacy primarily in improving constipation-related symptoms. Pre-clinical studies consistently reported improvements in a range of biological markers and outcomes, including evidence for attenuation of gut dysfunction and neuroprotection. Bacteria from the genus Lactobacillus and Bifidobacterium have been the most frequently studied both in clinical and pre-clinical probiotics studies, while research into prebiotics is still limited and primarily involved resistant starch and fructooligosaccharides. We provide practical suggestions for clinicians on how to advise patients in the clinic regarding these popular treatments, and important caveats to be aware of. Finally, areas for further advancements are highlighted. It is envisaged that in the future, microbial-based therapies may benefit from personalization based on an enhanced understanding of a whole range of host factors and host-microbiome interactions.

Engineering Escherichia coli Nissle 1917 as a microbial chassis for therapeutic and industrial applications

Genetically engineered microbes, especially Escherichia coli, have been widely used in the biosynthesis of proteins and metabolites for medical and industrial applications. As a traditional probiotic with a well-established safety record, E. coli Nissle 1917 (EcN) has recently emerged as a microbial chassis for generating living therapeutics, drug delivery vehicles, and microbial platforms for industrial production. Despite the availability of genetic tools for engineering laboratory E. coli K-12 and B strains, new genetic engineering systems are still greatly needed to expand the application range of EcN. In this review, we have summarized the latest progress in the development of genetic engineering systems in EcN, as well as their applications in the biosynthesis and delivery of valuable small molecules and biomacromolecules of medical and/or industrial interest, followed by a glimpse of how this rapidly growing field will evolve in the future.