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Review

Bacteria-Based Microdevices for the Oral Delivery of Macromolecules

by
Zhenping Cao
,
Sisi Lin
* and
Jinyao Liu
*
Shanghai Key Laboratory for Nucleic Acid Chemistry and Nanomedicine, Institute of Molecular Medicine, State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
*
Authors to whom correspondence should be addressed.
Pharmaceutics 2021, 13(10), 1610; https://doi.org/10.3390/pharmaceutics13101610
Submission received: 31 August 2021 / Revised: 21 September 2021 / Accepted: 23 September 2021 / Published: 3 October 2021
(This article belongs to the Special Issue Novel Devices for the Oral Delivery of Macromolecules)
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Abstract

:
The oral delivery of macromolecules is quite challenging due to environmental insults and biological barriers encountered along the gastrointestinal (GI) tract. Benefiting from their living characteristics, diverse bacterial species have been engineered as intelligent platforms to deliver various therapeutics. To tackle difficulties in oral delivery, innovative bacteria-based microdevices have been developed by virtue of advancements in synthetic biology and nanotechnology, with aims to overcome the instability and short half-life of macromolecules in the GI tract. In this review, we summarize the main classes of macromolecules that are produced and delivered through the oral ingestion of bacteria and bacterial derivatives. Furtherly, we discuss the engineering strategies and biomedical applications of these living microdevices in disease diagnosis, bioimaging, and treatment. Finally, we highlight the advantages as well as the limitations of these engineered bacteria used as platforms for the oral delivery of macromolecules and also propose their potential for clinical translation. The results summarized in this review article would contribute to the invention of next-generation bacteria-based systems for the oral delivery of macromolecules.

Graphical Abstract

1. Introduction

Biologics, also known as biomacromolecular pharmaceuticals, including peptides, proteins, antibodies, polysaccharides, and nucleic acids, produced from various biological systems, such as microorganisms, mammalian cells, and animal- or human-derived tissues via biotechnological means [1]. These biomacromolecules have been widely used for the prevention, diagnosis, and treatment of human diseases, such as tumors, AIDS, cardiovascular and cerebrovascular diseases, and hepatitis [1,2,3,4,5,6,7]. Currently, approximately 30 percent of all the U.S. Food and Drug Administration (FDA) approved drugs are biomacromolecules [8]. Among them, proteins and peptides take up the majority of these therapeutic biomacromolecules [8,9,10,11]. Owing to their clinical success and rapid improvements in commercial values and market shares, biologicals have been recognized as one of the most promising areas in drug research and development in the 21st century.
Although biologicals provide high specificity and activity thanks to their large and complex structures, there are problems and obstacles that need to be solved for the use of these drugs as most of them suffer from low stability, short half-life, and limited penetration across biological barriers [2,8]. In order to improve their treatment efficacy, the preferential method for the use of biologicals is injection, which is able to promote drug absorption, rapidly increase the blood drug concentration and enable accurate dosing [8,12]. However, conventional parenteral administration inevitably has problems with pain, patient incompliance, needle sickness, needle-stick injuries, and risks of systemic infections [13]. In contrast, the oral delivery of macromolecules drugs is a more convenient and non-invasive approach, with significant ameliorations in patient compliance and reduction of economic cost [1,8]. Unfortunately, the oral delivery of biomacromolecular pharmaceuticals faces biological barriers and microenvironmental insults encountered along the gastrointestinal (GI) tract [1,10]. For instance, the GI tract presents harsh environments with low pH in the stomach as well as high levels of bile salts and enzymes in the intestine for digestion and processing, which can severely reduce the efficacy of oral biomacromolecular drugs [1,14]. Therefore, innovative delivery strategies and systems of oral therapeutic macromolecules are highly desirable to overcome these challenges, with an overarching goal to increase bioavailability.
In recent years, many researches have been focusing on the development of medical devices including microneedle-based pills, nanostraws, microjets, hydrogels, intestinal patches, and bacterial therapeutics, which are capable of overcoming these biological barriers and orally delivering a wide range of biologics [15,16,17,18]. These new delivery devices are designed to enable the oral dosing of biomacromolecules and improve their bioavailability, with increased patient adherence and reduced pain and other side effects [1,10,15,19,20]. Bacteria have been investigated as drug delivery microdevices due to their living characteristics that are able to carry macromolecular drugs via genetic engineering [21]. Moreover, various therapeutics can be attached to bacteria through physicochemical modifications [22,23]. Given the ability to colonize specific positions, for example disease sites, bacteria-based systems have been designed to release drugs preciously and continuously in the targets of interest. Compared to conventional drug delivery systems for the oral delivery of macromolecules, bacterial microdevices exhibit the advantages of the in situ production of biologicals, long-term colonization in the intestine, targeting ability, and versatility to load diverse drugs [24,25]. In this review, we mainly focus on bacteria-based microdevices and summarize their current progress and future prospects for the oral delivery of biomacromolecules (Figure 1). We firstly introduce the different kinds of biomacromolecular drugs prepared and delivered by bacteria and bacterial derivatives. Then, current technologies for the modification of bacteria-based therapeutic macromolecules are described, with an emphasis on the strategy of genetic engineering. Lastly, biomedical applications of these bacteria-based microdevices as well as their future prospects in this field will be discussed.

2. Biomacromolecules-Loaded Oral Bacterial Microdevices

Bacteria play extensively, yet important, roles in our lives both directly and indirectly [26]. With the development of interdisciplinary research on bacteria and their applications, numerous bacteria have been widely administrated as oral probiotics or bacterial therapeutics for treating various diseases including cancers, diabetes, inflammatory bowel diseases (IBDs), and pathogenic infections [27,28,29,30,31,32,33]. Due to their unique characteristics, such as genetic manipulation, rapid proliferation, and targeting specificity to disease sites, bacteria have successfully expressed different kinds of biologics through biological technologies and exhibited extremely promising potential to be utilized in bioimaging, diagnosis, and therapy [34,35,36]. Currently, the reported therapeutic biomacromolecules that are delivered by bacteria mainly include proteins, glycans, and nucleic acids. In this section, we focus on the introduction of the types and biomedical functions of these biomacromolecular drugs.

2.1. Therapeutic Proteins/Peptides

Proteins have specific and dynamic functions including forming receptors and channels, transporting molecules, and catalyzing chemical reactions [37,38,39]. Diseases may be caused, when proteins in the host body present mutations or abnormal concentrations [1,11]. Since their ability to serve a set of functions that are more specific and tolerable than small molecules, proteins are attractive to be used as therapeutics [11]. For several decades, therapeutic proteins have been considered as an important class of pharmaceutical biomacromolecular drugs [11], which encompass natural or engineered versions of large proteins, peptides, and antibodies [40,41]. With the rapid development of molecular biology and biotechnology, increasing numbers of recombinant proteins have been emerged and employed as pharmaceuticals, playing different clinical roles in healthcare (Table 1) [2].
To date, hundreds of proteins have been approved by the FDA for clinical applications, and there are many more in the pipeline [10,11]. However, because of the limitations of recombinant bacterial systems, lots of proteins are expressed as inclusion bodies, which can be used functionally only after renaturation processes [42]. At the time of clinical trials, human insulin, as the first recombinant therapeutic protein, was generated by combining separately pre-produced chain A and chain B via chemical conjugation [43]. Subsequently, recombinant insulin is predominantly expressed in the large scale by Escherichia coli (E. coli) [42,44]. Advances in biotechnologies, for example codon optimization, enable the improvement of production and solubility and realize the delivery of insulin through oral ingestion of bacteria [45]. Another series of therapeutic cytokines, interleukins (ILs), have been expressed in bacteria and orally administrated for disease treatments [46,47]. For instance, IL-2 and IL-17A, both of which demonstrate their antitumor efficacies, are produced and secreted by a recombinant Lactococcus lactis strain [48,49]. IL-35, an anti-inflammatory cytokine, is also delivered by an engineered bacterium for the prevention and treatment of dextran sulfate sodium (DSS)-induced colitis (Figure 2A) [47]. Moreover, therapeutic proteins have been attached to bacteria via surface decoration for combination therapy [22,50]. Recently, we have exploited silk fibroin that shows anti-inflammatory effects and can target the ulcerous or damaged areas of the intestine to decorate probiotics by self-assembly on their surface (Figure 2B) [50]. Silk fibroin is co-delivered as a therapeutic protein drug to synergistically enhance the treatment efficacy in mice associated with intestinal mucositis. Meanwhile, the self-assembled silk fibroin could form an entire shell on the surface to protect the decorated probiotics from the insults in the GI tract.
Therapeutic peptides are another class of therapeutic proteins. Gastric stable pentadecapeptide, BPC-157, is reported to be able to prevent and treat GI inflammations [51]. In order to deliver BPC-157 orally, lactic acid bacteria, which are capable of producing and delivering diverse therapeutic proteins via genetic engineering [52,60,61,62,63], are used to produce BPC-157 fusing with a membrane protein. The heterologous peptide is successfully displayed on the bacterial surface and orally delivered into the host as a therapeutic agent to reduce reactive oxygen species (ROS) production [52]. Another therapeutic peptide, glucagon-like peptide-1 (GLP-1), for the treatment of non-insulin-dependent diabetes, is delivered orally by a recombinant Lactococcus lactis that is genetically modified with a plasmid-encoding GLP-1 cDNA [41]. In addition, antibodies and antigens have also been expressed by bacteria, which are delivered orally to elicit strong immune responses [1,10,11,63]. The soluble receptor activator of nuclear factor kappa-Β ligand (RANKL) expressed in Lactococcus lactis exhibit the potential to act as an oral vaccine adjuvant that enhances the systemic and mucosal immune responses [64]. As an antigen, the HIV envelope protein is expressed in commensal Streptococcus mitis, which are co-administrated as an oral vaccination to induce both salivary and systemic antibody responses and develop antigen-specific systemic T cell tolerance [65].

2.2. Nucleic Acids

Nucleic acids, as a type of macromolecular therapeutic agents, are a series of functional DNA and RNA [19]. They have been widely applied for gene therapy in different forms including short-interfering RNAs, DNA/RNA vaccines, and genetic pharmacology [66]. In general, nucleic acid drugs include aptamers, interfering RNAs, antigens, ribozymes, and antisense nuclear acids. Nucleic-acid-based therapeutics exhibit the potential to treat a number of diseases by correcting the abnormal expression of specific genes, by virtue of their characteristic of high specificity to target genes [19]. However, due to the presence of multiple biological barriers including enzymatic barriers, mucus gel barriers, and cell membrane barriers in the GI tract, the oral delivery of nucleic acid drugs suffers from similar challenges to therapeutic proteins/peptides [1,10].
To overcome obstacles encountered in the oral administration of nucleic acids, numerous strategies that can address instability resulted from enzymatic degradation and side effects caused by anionic charges and enhance the oral bioavailability have been developed [67,68]. It is worth noting that some of them have entered into clinical trials [53,69]. The main approaches developed for nucleic acid delivery can be categorized into non-virus (such as liposomes, polymer vectors, and plasmid DNA) and virus vectors (such as adenovirus and retrovirus) [68,70]. As an alternative, bacteria have been extensively engineered to deliver nucleic acids, such as plasmid DNA, aptamers, and DNA vaccines for treating IBDs and colon cancer [1,71,72]. Non-pathogenic bacterial species are considered as a promising approach to drug delivery in both forms of intravenous injection and oral administration. For example, the human Elafin gene, encoding Elafin that is absent in mucosa of IBD patients, has been delivered via a plasmid vector inside oral probiotics for inflammation inhibition and intestinal flora regulation [54]. Additionally, Lactococcus lactis has been developed as a therapeutic microdevice to deliver IL-10 gene that encodes an immunomodulative protein for IBD treatment [73]. With the merit of in situ production, IL-10 is able to avoid degradation from intraluminal harsh environments and maintain their native therapeutic activities [73]. Meanwhile, pathogenic bacteria, such as Clostridium species, Salmonella Typhimurium (S. Typhimurium), and Listeria monocytogenes, have been applied for targeted tumor killing and oral vaccines [20,63,74,75]. Since these invasive species can deliver heterologous genes into tumor cells for expressing antitumor drugs, their tumor killing efficacies have been improved significantly [75,76]. Furthermore, chemically modified bacteria have been investigated for the oral delivery of DNA. For instance, Hu and colleagues have developed an engineered bacterium that is anchored with cationic DNA nanoparticles on the surface (Figure 3A) [74]. Equipped with protective DNA nanoparticles layers on the surface, bacteria succeed in escaping phagosomes and remain intact and active after exposure to the GI tract. The delivered DNA vaccines are able to encode vascular endothelial growth factor receptor 2 (VEGFR2) and activate T cells, showing significant inhibition against tumor growth [74]. Additionally, bacterial ghosts, empty bacterial envelopes that lack infectious abilities but display bio-adhesive properties, have been explored as vectors for the delivery of DNA drugs [20,77]. In order to induce peripheral and mucosal immune responses, Wen et al. have delivered HIV-1 gp-140 DNA vaccine through S. typhimurium-derived bacterial ghosts, which could activate antibody responses via the TLR4 pathway (Figure 3B) [78].

2.3. Polysaccharides

Polysaccharides, a sort of biological macromolecules produced by plants, animals, and microorganisms, refer to a class of therapeutic agents containing a glycan molecular skeleton or derived from carbohydrate compounds and their derivatives, such as glycoproteins, proteoglycans, glycolipids, lipopolysaccharides, and glycosides. The chains of polysaccharides with a complex structure on the cell surface play critical roles in a variety of physiological and pathological processes in organisms. However, due to a higher degree of the complexity and diversity of the structure compared to those of proteins and nucleic acids, progresses achieved in polysaccharide-based macromolecular drugs lag far behind. In recent years, with the developments of glycomics and glycobiology as well as the technologic improvements in separation and purification, structural characterization, and qualitative and quantitative analysis, more polysaccharides with excellent pharmacological activities have entered the vision of scientists and pharmacists. Polysaccharide drugs have become an important part of drug discovery and development in recent years. In this section, we focus on the bacteria-mediated oral delivery of therapeutic polysaccharide agents.
Both lipopolysaccharides (LPS) in bacterial cell walls and capsular polysaccharides attached on the surface of the bacterial cell wall are the interface of bacteria to interact with surrounding environments. These polysaccharides are associated with the bacterial virulence and immune regulation of the host. Benefiting from their immune activation abilities, bacterial lipopolysaccharides and capsular polysaccharides have been utilized as oral vaccines [79,80]. For example, E. coli has been glycol-engineered as a polyvalent pneumococcal bioconjugate vaccine by using recombinant techniques and established as a robust platform for the development of bioconjugate vaccines to prevent and treat numerous pathogenic infections [81]. The immunogenic and protective pneumococcal bioconjugates produced by E. coli are able to endow mice with high levels of bactericidal killing activities, suggesting a promising potential of bioconjugate vaccines to treat many severe pathogenic infections. Later, Su et al. have synthesized a Streptococcus pneumoniae (S. pneumoniae) capsular polysaccharide via recombinant attenuated Salmonella, which have been delivered orally as a vaccine against S. pneumoniae infection (Figure 4A) [82]. On the other hand, various polysaccharides, such as chitosan, cellulose, inulin, and alginate, have been utilized for probiotic encapsulation for colon-specific drug delivery, due to their biocompatibility and biodegradability [14,83,84,85]. With the help of chitosan that inhibits bacterial infection and accumulation in disease sites in the host, we have fabricated a robust platform of multimodal probiotics by decorating bacteria with dopamine and chitosan (Figure 4B) [86]. Given the hybrid dopamine and chitosan coating on the probiotic surface, the bioavailability of decorated probiotics in the gut increased to more than 30-times higher, and their accumulation in the inflamed tissue is improved by 4 times. Compared to non-encapsulated bacteria, the treatment efficacy of the coated probiotics is validated to be strikingly enhanced in colitis mice.

3. Biomedical Applications of Oral Bacterial Microdevices

Thanks to close connections between bacteria and the host, numbers of bacteria have demonstrated their advantages in immune regulation, homeostasis maintenance, and host health [26]. On the other side, speedy developments in synthetic biology technology and nanotechnology endow bacteria with both programmable endogenous and exogenous functions, such as chemotaxis, biomacromolecule secretion, loading of synthetic substrates, which outperform conventional diagnostics and therapeutics in a range of diseases [25]. In this section, the biomedical applications of oral bacterial microdevices are summarized, and their current status and future prospect are also discussed.

3.1. Diagnosis

Living bacterial cells perform biological functions by sensing and responding to different signal molecules in surrounding environments, such as nutrients, metabolites, cytokines, and biological stimuli [87,88]. Taking advantages of genetic engineering technologies, synthetic gene circuits have been created in both prokaryotes and eukaryotes, which are able to respond to specific signal molecules and continuously produce measurable unique biomarkers or therapeutic macromolecules in target sites [27,55,56,89]. By synthetic gene circuits, diagnostic bacteria can readily record and quantify the process of measurement, which cannot be achieved by conventional test strategies [89].
To diagnose gut inflammation and colon cancer via oral administration, bacterial strains have been engineered to sense disease markers by using a gene circuit. For example, Lee et al. have equipped E. coli with a responsive genetic circuit and an optimized nitrate biosensor, which could simultaneously detect thiosulfate and nitrate biomarkers [55]. Similarly, Naydich et al. have developed an E. coli memory circuit and identified a wide variety of new responsive bacterial biosensor triggers from inflamed gut [56]. They illustrated that this noninvasively engineered bacterial biosensor is able to report transient molecules and observe the inflammation in mouse gut for over six months. The results demonstrated that genetic engineered bacteria could be used as new strategies for the non-invasive diagnostics of inflammation diseases. Owing to the unique ability to selectively home in tumors, bacteria have been also investigated to detect cancers. For example, Danino et al. have programmed probiotics as a PROP-Z diagnostic platform for the non-invasive detection of metastatic cancer, which is difficult to be detected by conventional imaging (Figure 5A) [27]. After oral administration into the GI tract, the programmed bacteria enter metastatic tumors in the liver and the expressed specific enzyme green LacZ is cleaved into red and yellow substrates by injection with LuGal. The yellow substrate is filtered by the renal system, and the released luminescent molecules could be detected and quantified sensitively in urine. Moreover, they have successfully detected metastases from colon, lung, ovary, and pancreatic tumors in the liver by the oral delivery of these programmed probiotics. The application of bacteria-based oral microdevices for disease diagnosis, particularly for early cancer detections, is able to extend patient survival time significantly in a more effective and less painful way.

3.2. Bioimaging

Monitoring bacterial colonization and bioactivities in the intestinal tract is fundamental and urgent, given the important roles of the gut microbiome in regulating human health [90]. By means of the rapid blossom of genetic manipulation technology, bacteria have been genetically modified to deliver biomacromolecules orally for bioimaging. A series of conventional optic reporter genes, such as GFP and mCherry, has been utilized for the in vivo imaging of bacteria colonizing in the gut [91]. However, these optic reporters have limitations in deep tissues due to complex and harsh environments in the intestinal tract and the limited light penetration depth [34,92]. In order to improve bioimaging performance in deep tissues, researchers have developed acoustic reporter genes encoding gas-filled proteins for assembling gas vesicles, which allow the bacteria to be imaged by ultrasound with characteristics of deep tissue penetration and high spatial resolution [92,93]. For example, Bourdeau and his colleagues have designed an acoustic reporter gene based on the microbubbles of some aquatic photosynthetic organisms (Figure 5B) [34]. With the transformation of acoustic reporter genes, E. coli successfully expresses gas-filled protein and generates nanosized gas vesicles, which can be imaged by ultrasound when the bulk density is less than 0.01%. Furthermore, the authors have optimized the reporter genes with different acoustic characteristics, by which they have successfully detected bacteria in the host GI tract with a resolution less than 100 microns. Obviously, this technology enables the observation of the gut microbiome in vivo and contributes to the development of multimodal bacteria-mediated diagnosis and treatment.

3.3. Disease Treatments

The human gut microflora consisting of a huge community of microorganisms and thousands of bacterial species plays vital roles in nutrient metabolism, host immunoregulation, defense against pathogens, and maintenance of intestinal barrier integrity [90]. Imbalances of the gut microbiome are associated with a variety of diseases, such as GI infectious diseases and cancers [94,95,96,97]. Thus, to prevent and treat dysbacteriosis-related diseases, it is quite essential to positively modulate the symbiosis and composition of the gut microbiota.

3.3.1. Intestinal Infectious Diseases

Microbiota transplantation, including fecal microbiota transplantation (FMT) and orally delivered bacteria carrying therapeutic biomacromolecules, is an effective approach to restoring the homeostasis and health of the intestine [98]. Here, we focus on the treatment of intestinal infectious diseases by functional biomacromolecules that are orally delivered in forms of engineered bacteria (Table 1). Owing to the unique properties of bacteria, engineered bacteria are designed to express specific therapeutic biomacromolecules that can prevent and treat human diseases. Actic acid bacteria, e.g., Lactococcus and Bifidobacterium, are eatable probiotics that have been used for yogurt preparation over centuries [99]. In addition to the ability to manipulate microbiome in the intestinal tract, actic acid bacteria have been intensively investigated as an alternative for intestinal disease prevention and treatment, due to their advantages in safety, manipulability, accumulation in the GI tract, and pathogen inhibition ability [100]. With an aim to improve their anti-inflammatory property and therapeutic efficacy, genetic engineering has been performed to express a series of heterologous biomacromolecules such as therapeutic proteins/peptides of medical interests, including IL-10, IL-35, Elafin, and adhesive proteins of pathogenic bacteria [47,54,57,73]. For example, Lactococcus fermentum I5007 is engineered to express superoxide dismutase that exists in other bacterial species and applied for treating trinitrobenzene sulfonic acid-induced colitis by protection against ROS and inhibiting the NF-κB pathway [101]. In addition, Drolia and colleagues have camouflaged Lactobacillus casei by expressing the characteristic adhesive protein of Listeria (LAP) on the bacterial surface (Figure 6A,B) [57]. With the presence of LAP on the surface, the engineered Lactobacillus occupies LAP receptors and excludes Listeria competitively. In consequence, the engineered Lactobacillus reduces Listeria infection by the immune regulation mechanism of probiotics and the increased “competitiveness” enabled by bioengineering (Figure 6C). Inspired by the promising results of the recombinant actic acid bacteria in treating intestinal diseases, some of them have enter into preclinic trials [102]. E. coli Nissle 1917 (EcN) is another well-known probiotic bacterium, which is reported to effectively inhibit pathogenic bacteria in the gut and be engineered variously for enhancing treatment efficacies of intestinal diseases. To promote the therapeutic effects in IBD treatment, EcN is modified to express bioengineered curli fibers protein, which is able to form fibrous matrices by self-assembly (Figure 7A). The bioengineered curli fiber protein is expressed by fusing with a trefoil factor domain (Figure 7B), endowing the formed curli fibrous matrices with enhanced epithelial healing ability following the oral delivery of the engineered bacteria to the inflammation sites of the intestine (Figure 7C,D) [58]. In addition, EcN is programmed to produce an anti-biofilm protein, dispersin B (DspB), which is able to disrupt the integrity of mature biofilms [59,103]. The results suggested that after oral administration, the engineered EcN shows effective elimination and prevention activities against Pseudomonas aeruginosa in gut infection models.

3.3.2. Cancers

Cancer is considered as a leading public health problem globally, which has caused 9.6 million deaths in 2018, with a proportion of approximately 20% in all deaths [104]. Currently, cancers have been treated mostly by conventional treatment strategies, such as surgery, chemotherapy, radiotherapy, and immunotherapy. However, these traditional therapeutic methods are often inadequate to eliminate cancers effectively and completely, because of the potential of triggering intrinsic and acquired resistance as well as unavoidable cytotoxic side effects [105]. Since Coley and coworkers pioneered the use of bacteria, e.g., S. pyogenes expressing Coley’s toxins, to treat cancers more than 100 years ago [105,106], the door of bacteria-mediated cancer therapy has opened. Subsequently, more bacterial species, including Bifidobacterium spp., Clostridium spp., S. typhimurium, and E. coli, have been found to accumulate in tumor sites [25]. In light of their inherent capacities of breaking related biological barriers and colonizing tumor tissue, these bacterial species have been intensively attracted for cancer therapy [107,108]. Moreover, equipped with technologies progressed rapidly in gene editing and bio-interface science, bacteria have been engineered to act as vehicles for the delivery of therapeutic agents including both small molecules and biomacromolecules (proteins and DNAs) (Table 2) [20,54,64,100,109]. In this part, engineered bacteria that are capable of delivering biomacromolecular drugs orally are discussed.
To facilitate oral delivery, antitumor biomacromolecular therapeutics, such as cytotoxic proteins, cancer-specific antigens, and cytokines, have been encoded into bacteria by genetic engineering, which can produce inducibly or constantly [49,110,112,113,114]. Chung et al. have developed a bacteria-based drug delivery platform for treating colorectal cancer [110]. A lactic acid bacterium Pediococcus pentosaceus is modified to produce a small protein (P8) against CRC fused with a secretion signal peptide under the control of a strong inducible promoter. After oral administration into the intestine, the engineered anti-CRC therapeutic probiotics demonstrates significant anticancer efficacies in two different tumor-bearing mouse models. Combining expressing therapeutic protein TNF-α driven by a thermal-sensitive promoter and decorating with biomineralized gold nanoparticles (AuNPs) on the bacterial surface, E. coli MG1655 is engineered both genetically and chemically to generate a thermal-sensitive therapeutic platform termed as TPB@Au (Figure 8A,B) [111]. The engineered bacteria deliver Au nanoparticles to tumor site with the help of bacterial inherent homing capability. Upon near-infrared light irradiation, the Au nanoparticles generate heat and induce the expression of TNF-α, which could kill tumor cells (Figure 8C). In addition, researchers have generated a bacteria-based oral DNA vaccine for cancer therapy. Attenuated Salmonella was decorated with DNA nanoparticles that could encode autologous vascular endothelial growth factor receptor 2 (VEGFR2) on the surface (Figure 3A) [74]. The results suggested that the acid resistance of this vaccine is improved remarkably, due largely to the protection effects of the nanoparticle layers. With the assistance of bacteria that enhances the accumulation of more DNA inside tumor tissues, significantly improved therapeutic efficacy is observed in tumor-bearing mice.

3.3.3. Other Diseases

In addition to intestinal inflammation diseases and cancers, bacteria have been designed to deliver therapeutic agents for other diseases, such as diabetes, obesity, HIV, and ethanol-induced liver disease (Table 3) [41,46,78]. Insulin, an essential drug for diabetes treatment, is usually delivered by subcutaneous injection as its inability to resist the strong acids and digestive enzymes in the GI tract. Thus, it is attractive to use bacteria that could be engineered to orally deliver protein/peptide therapeutics against diabetes. Lactococcus lactis is genetically modified to produce a single-chain insulin analog, which is able to bind and stimulate the expression of the insulin receptor [45]. Another major therapeutic drug for diabetes, GLP-1, is expressed in engineered Lactococcus and Bifidobacterium longum to enhance the efficiency of glucose control in murine models [41,115]. In addition, Lactobacillus reuteri is engineered to produce mouse IL-22 for treating alcoholic liver disease [46]. Previous studies demonstrated that in alcoholic liver disease models, the production of IL-22, which regulates the expression of antimicrobial C-type lectin regenerating islet-derived 3 gamma (REG3G), is reduced significantly [116]. To restore REG3G expression in the intestine, probiotic bacteria are genetically modified to orally deliver IL-22 [46]. As a result, compared to mice administered with unmodified bacteria, mice fed with engineered bacteria exhibit reduced liver damage and inflammation. These works verify that oral-bacteria-based microdevices propose an alternative to solve the problems associated with the parenteral administration of anti-diabetes drugs, such as pain, patient reluctance, and needle-related injuries and risks.

4. Conclusions and Future Prospects

In summary, bacteria can be easily constructed by either genetic engineering or physicochemical modification to carry various therapeutic macromolecules including proteins/peptides, nucleic acids, and polysaccharides. Given their living characteristics, such as proliferation and colonization in the gut, different bacterial species have been fabricated as versatile, yet intelligent, microdevices for the oral delivery of diverse biologicals. These living-bacteria-based microdevices have demonstrated great potential for biomedical applications including bioimaging, diagnosis, and treatment in intestinal inflammation and infectious diseases, cancers, and diabetes. Encouragingly, a few engineered bacteria have shown promising treatment efficacies and enter into clinical trials. Despite a remarkable progress has been made in this field, the oral delivery of therapeutic biomacromolecular drugs by bacteria-based microdevices faces a couple of substantial obstacles that are needed to be overcome urgently. Firstly, due to the complexity of synthetic biological techniques, many macromolecular agents cannot be expressed in their native forms by genetic modification, which suggests that the kinds of macromolecules could be orally delivered by bacteria are limited. Moreover, it is quite essential to protect bacteria from strongly acidic and digestive environments in the GI tract, with aims to increase their bioavailability and colonization. Furtherly, the disease-targeting ability of engineered bacteria is necessary to be improved. With adequate targeting ability, more bacteria can accumulate in the right sites, and hence, more therapeutic drugs can be delivered. Lastly, new mechanisms and strategies regarding increments in absorption and penetration across the intestinal barrier should be considered particularly in the delivery of biologicals into distal organs or tissues. In general, much work on bacteria-based microdevices for the oral delivery of macromolecules has been limited to in vitro or preclinical animal studies, suggesting that more efforts are needed to promote future translation of these advanced microdevices for clinical applications. However, we believe that current limitations remaining in the field are addressable considering the speedy advancements in synthetic biological methodologies, nanotechnology, and related interdiscipline. We anticipate that bacteria-based microdevices could pave an avenue for the preparation of next-generation drug carriers for the oral delivery of biomacromolecules.

Funding

This work was financially supported by the National Natural Science Foundation of China (21875135), the Recruitment Program of Global Youth Experts of China (D1410022), the Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant Support (20181704), the Innovative Research Team of High-Level Local Universities in Shanghai (SSMU-ZLCX20180701), the Youth Science and Technology Talents Yang Fan Plan of Shanghai (19YF1427800), and the Interdisciplinary Program of Shanghai Jiao Tong University (ZH2018QNA44).

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Duran-Lobato, M.; Niu, Z.; Alonso, M.J. Oral Delivery of Biologics for Precision Medicine. Adv. Mater. 2020, 32, e1901935. [Google Scholar] [CrossRef]
  2. Leader, B.; Baca, Q.J.; Golan, D.E. Protein therapeutics: A summary and pharmacological classification. Nat. Rev. Drug Discov. 2008, 7, 21–39. [Google Scholar] [CrossRef]
  3. Carvalho, A.L.; Fonseca, S.; Miquel-Clopes, A.; Cross, K.; Kok, K.S.; Wegmann, U.; Gil-Cordoso, K.; Bentley, E.G.; Al Katy, S.H.M.; Coombes, J.L.; et al. Bioengineering commensal bacteria-derived outer membrane vesicles for delivery of biologics to the gastrointestinal and respiratory tract. J. Extracell. Vesicles 2019, 8, 1632100. [Google Scholar] [CrossRef] [PubMed]
  4. Zhang, Y.; Thanou, M.; Vllasaliu, D. Exploiting disease-induced changes for targeted oral delivery of biologics and nanomedicines in inflammatory bowel disease. Eur. J. Pharm. Biopharm. 2020, 155, 128–138. [Google Scholar] [CrossRef] [PubMed]
  5. Fiorentini, S.; Giagulli, C.; Caccuri, F.; Magiera, A.K.; Caruso, A. HIV-1 matrix protein p17: A candidate antigen for therapeutic vaccines against AIDS. Pharmacology 2010, 128, 433–444. [Google Scholar] [CrossRef]
  6. Jafari, R.; Zolbanin, N.M.; Rafatpanah, H.; Majidi, J.; Kazemi, T. Fc-fusion Proteins in Therapy: An Updated View. Curr. Med. Chem. 2017, 24, 1228–1237. [Google Scholar] [CrossRef] [PubMed]
  7. Zhao, S.; Mysler, E.; Moots, R.J. Etanercept for the treatment of rheumatoid arthritis. Immunotherapy 2018, 10, 433–445. [Google Scholar] [CrossRef] [PubMed]
  8. Anselmo, A.C.; Gokarn, Y.; Mitragotri, S. Non-invasive delivery strategies for biologics. Nat. Rev. Drug Discov. 2019, 18, 19–40. [Google Scholar] [CrossRef]
  9. Sharfstein, S.T. Non-protein biologic therapeutics. Curr. Opin. Biotechnol. 2018, 53, 65–75. [Google Scholar] [CrossRef]
  10. Drucker, D.J. Advances in oral peptide therapeutics. Nat. Rev. Drug Discov. 2020, 19, 277–289. [Google Scholar] [CrossRef]
  11. Philippart, M.; Schmidt, J.; Bittner, B. Oral Delivery of Therapeutic Proteins and Peptides: An Overview of Current Technologies and Recommendations for Bridging from Approved Intravenous or Subcutaneous Administration to Novel Oral Regimens. Drug Res. 2016, 66, 113–120. [Google Scholar] [CrossRef]
  12. Usach, I.; Martinez, R.; Festini, T.; Peris, J.E. Subcutaneous Injection of Drugs: Literature Review of Factors Influencing Pain Sensation at the Injection Site. Adv. Ther. 2019, 36, 2986–2996. [Google Scholar] [CrossRef] [Green Version]
  13. Hogan, N.C.; Taberner, A.J.; Jones, L.A.; Hunter, I.W. Needle-free delivery of macromolecules through the skin using controllable jet injectors. Expert Opin. Drug Deliv. 2015, 12, 1637–1648. [Google Scholar] [CrossRef]
  14. Jiang, T.; Li, H.S.; Han, G.G.; Singh, B.; Kang, S.K.; Bok, J.D.; Kim, D.D.; Hong, Z.S.; Choi, Y.J.; Cho, C.S. Oral Delivery of Probiotics in Poultry Using pH-Sensitive Tablets. J. Microbiol. Biotechnol. 2017, 27, 739–746. [Google Scholar] [CrossRef]
  15. Abramson, A.; Caffarel-Salvador, E.; Soares, V.; Minahan, D.; Tian, R.Y.; Lu, X.; Dellal, D.; Gao, Y.; Kim, S.; Wainer, J.; et al. A luminal unfolding microneedle injector for oral delivery of macromolecules. Nat. Med. 2019, 25, 1512–1518. [Google Scholar] [CrossRef] [PubMed]
  16. Fox, C.B.; Cao, Y.; Nemeth, C.L.; Chirra, H.D.; Chevalier, R.W.; Xu, A.M.; Melosh, N.A.; Desai, T.A. Fabrication of Sealed Nanostraw Microdevices for Oral Drug Delivery. ACS Nano 2016, 10, 5873–5881. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  17. Qi, X.; Yuan, Y.; Zhang, J.; Bulte, J.W.M.; Dong, W. Oral Administration of Salecan-Based Hydrogels for Controlled Insulin Delivery. J. Agric. Food Chem. 2018, 66, 10479–10489. [Google Scholar] [CrossRef] [PubMed]
  18. Aran, K.; Chooljian, M.; Paredes, J.; Rafi, M.; Lee, K.; Kim, A.Y.; An, J.; Yau, J.F.; Chum, H.; Conboy, I.; et al. An oral microjet vaccination system elicits antibody production in rabbits. Sci. Transl. Med. 2017, 9, eaaf6413. [Google Scholar] [CrossRef] [PubMed]
  19. Attarwala, H.; Han, M.; Kim, J.; Amiji, M. Oral nucleic acid therapy using multicompartmental delivery systems. Wiley Interdiscip Rev. Nanomed. Nanobiotechnol. 2018, 10, e1478. [Google Scholar] [CrossRef]
  20. Huang, J.; Jia, R.; Shen, H.; Wang, M.; Zhu, D.; Chen, S.; Liu, M.; Zhao, X.; Wu, Y.; Yang, Q.; et al. Oral Delivery of a DNA Vaccine Expressing the PrM and E Genes: A Promising Vaccine Strategy against Flavivirus in Ducks. Sci. Rep. 2018, 8, 12360. [Google Scholar] [CrossRef] [Green Version]
  21. Lin, D.; Feng, X.; Mai, B.; Li, X.; Wang, F.; Liu, J.; Liu, X.; Zhang, K.; Wang, X. Bacterial-based cancer therapy: An emerging toolbox for targeted drug/gene delivery. Biomaterials 2021, 277, 121124. [Google Scholar] [CrossRef]
  22. Cao, Z.; Liu, J. Bacteria and bacterial derivatives as drug carriers for cancer therapy. J. Control. Release 2020, 326, 396–407. [Google Scholar] [CrossRef]
  23. Li, Z.; Wang, Y.; Liu, J.; Rawding, P.; Bu, J.; Hong, S.; Hu, Q. Chemically and Biologically Engineered Bacteria-Based Delivery Systems for Emerging Diagnosis and Advanced Therapy. Adv. Mater. 2021, 33, e2102580. [Google Scholar] [CrossRef]
  24. Hosseinidoust, Z.; Mostaghaci, B.; Yasa, O.; Park, B.W.; Singh, A.V.; Sitti, M. Bioengineered and biohybrid bacteria-based systems for drug delivery. Adv. Drug Deliv. Rev. 2016, 106, 27–44. [Google Scholar] [CrossRef]
  25. Li, S.; Jiang, W.; Zheng, C.; Shao, D.; Liu, Y.; Huang, S.; Han, J.; Ding, J.; Tao, Y.; Li, M. Oral delivery of bacteria: Basic principles and biomedical applications. J. Control. Release 2020, 327, 801–833. [Google Scholar] [CrossRef] [PubMed]
  26. Lagier, J.C.; Dubourg, G.; Million, M.; Cadoret, F.; Bilen, M.; Fenollar, F.; Levasseur, A.; Rolain, J.M.; Fournier, P.E.; Raoult, D. Culturing the human microbiota and culturomics. Nat. Rev. Microbiol. 2018, 16, 540–550. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  27. Danino, T.; Prindle, A.; Kwong, G.A.; Skalak, M.; Li, H.; Allen, K.; Hasty, J.; Bhatia, S.N. Programmable probiotics for detection of cancer in urine. Sci. Transl. Med. 2015, 7, 289ra284. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  28. Ou, B.; Yang, Y.; Tham, W.L.; Chen, L.; Guo, J.; Zhu, G. Genetic engineering of probiotic Escherichia coli Nissle 1917 for clinical application. Appl. Microbiol. Biotechnol. 2016, 100, 8693–8699. [Google Scholar] [CrossRef]
  29. Schultz, M. Clinical use of E. coli Nissle 1917 in inflammatory bowel disease. Inflamm. Bowel. Dis. 2008, 14, 1012–1018. [Google Scholar] [CrossRef] [PubMed]
  30. Sonnenborn, U.; Schulze, J. The non-pathogenic Escherichia coli strain Nissle 1917—Features of a versatile probiotic. Microb. Ecol. Health Dis. 2009, 21, 122–158. [Google Scholar] [CrossRef]
  31. Stritzker, J.; Weibel, S.; Hill, P.J.; Oelschlaeger, T.A.; Goebel, W.; Szalay, A.A. Tumor-specific colonization, tissue distribution, and gene induction by probiotic Escherichia coli Nissle 1917 in live mice. Int. J. Med Microbiol. 2007, 297, 151–162. [Google Scholar] [CrossRef]
  32. Sully, E.K.; Malachowa, N.; Elmore, B.O.; Alexander, S.M.; Femling, J.K.; Gray, B.M.; DeLeo, F.R.; Otto, M.; Cheung, A.L.; Edwards, B.S.; et al. Selective chemical inhibition of agr quorum sensing in Staphylococcus aureus promotes host defense with minimal impact on resistance. PLoS Pathog. 2014, 10, e1004174. [Google Scholar] [CrossRef] [PubMed]
  33. Low, K.B.; Ittensohn, M.; Le, T.; Platt, J.; Sodi, S.; Amoss, M.; Ash, O.; Carmichael, E.; Chakraborty, A.; Fischer, J.; et al. Lipid A mutant Salmonella with suppressed virulence and TNFalpha induction retain tumor-targeting in vivo. Nat. Biotechnol. 1999, 17, 37–41. [Google Scholar] [CrossRef] [PubMed]
  34. Bourdeau, R.W.; Lee-Gosselin, A.; Lakshmanan, A.; Farhadi, A.; Kumar, S.R.; Nety, S.P.; Shapiro, M.G. Acoustic reporter genes for noninvasive imaging of microorganisms in mammalian hosts. Nature 2018, 553, 86–90. [Google Scholar] [CrossRef]
  35. Min, J.J.; Nguyen, V.H.; Kim, H.J.; Hong, Y.; Choy, H.E. Quantitative bioluminescence imaging of tumor-targeting bacteria in living animals. Nat. Protoc. 2008, 3, 629–636. [Google Scholar] [CrossRef] [PubMed]
  36. Chen, J.; Gao, P.; Yuan, S.; Li, R.; Ni, A.; Chu, L.; Ding, L.; Sun, Y.; Liu, X.Y.; Duan, Y. Oncolytic Adenovirus Complexes Coated with Lipids and Calcium Phosphate for Cancer Gene Therapy. ACS Nano 2016, 10, 11548–11560. [Google Scholar] [CrossRef]
  37. Cao, Z.; Casabona, M.G.; Kneuper, H.; Chalmers, J.D.; Palmer, T. The type VII secretion system of Staphylococcus aureus secretes a nuclease toxin that targets competitor bacteria. Nat. Microbiol. 2016, 2, 16183. [Google Scholar] [CrossRef] [Green Version]
  38. Ulhuq, F.R.; Gomes, M.C.; Duggan, G.M.; Guo, M.; Mendonca, C.; Buchanan, G.; Chalmers, J.D.; Cao, Z.; Kneuper, H.; Murdoch, S.; et al. A membrane-depolarizing toxin substrate of the Staphylococcus aureus type VII secretion system mediates intraspecies competition. Proc. Natl. Acad. Sci. USA 2020, 117, 20836–20847. [Google Scholar] [CrossRef]
  39. Sundaramoorthy, R.; Fyfe, P.K.; Hunter, W.N. Structure of Staphylococcus aureus EsxA suggests a contribution to virulence by action as a transport chaperone and/or adaptor protein. J. Mol. Biol. 2008, 383, 603–614. [Google Scholar] [CrossRef] [Green Version]
  40. Zeng, Z.; Yu, R.; Zuo, F.; Zhang, B.; Peng, D.; Ma, H.; Chen, S. Heterologous Expression and Delivery of Biologically Active Exendin-4 by Lactobacillus paracasei L14. PLoS ONE 2016, 11, e0165130. [Google Scholar] [CrossRef] [Green Version]
  41. Agarwal, P.; Khatri, P.; Billack, B.; Low, W.K.; Shao, J. Oral delivery of glucagon like peptide-1 by a recombinant Lactococcus lactis. Pharm. Res. 2014, 31, 3404–3414. [Google Scholar] [CrossRef]
  42. Ladisch, M.R.; Kohlmann, K.L. Recombinant human insulin. Biotechnol. Prog. 1992, 8, 469–478. [Google Scholar] [CrossRef]
  43. Chance, R.E.; Frank, B.H. Research, development, production, and safety of biosynthetic human insulin. Diabetes Care 1993, 16 (Suppl 3), 133–142. [Google Scholar] [CrossRef]
  44. Baeshen, N.A.; Baeshen, M.N.; Sheikh, A.; Bora, R.S.; Ahmed, M.M.; Ramadan, H.A.; Saini, K.S.; Redwan, E.M. Cell factories for insulin production. Microb. Cell Factories 2014, 13, 141. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  45. Mao, R.; Wu, D.; Hu, S.; Zhou, K.; Wang, M.; Wang, Y. Secretory expression and surface display of a new and biologically active single-chain insulin (SCI-59) analog by lactic acid bacteria. Appl. Microbiol. Biotechnol. 2017, 101, 3259–3271. [Google Scholar] [CrossRef] [PubMed]
  46. Hendrikx, T.; Duan, Y.; Wang, Y.; Oh, J.H.; Alexander, L.M.; Huang, W.; Starkel, P.; Ho, S.B.; Gao, B.; Fiehn, O.; et al. Bacteria engineered to produce IL-22 in intestine induce expression of REG3G to reduce ethanol-induced liver disease in mice. Gut 2019, 68, 1504–1515. [Google Scholar] [CrossRef]
  47. Wang, J.; Tian, M.; Li, W.; Hao, F. Preventative delivery of IL-35 by Lactococcus lactis ameliorates DSS-induced colitis in mice. Appl. Microbiol. Biotechnol. 2019, 103, 7931–7941. [Google Scholar] [CrossRef] [PubMed]
  48. Jacouton, E.; Torres Maravilla, E.; Boucard, A.S.; Pouderous, N.; Pessoa Vilela, A.P.; Naas, I.; Chain, F.; Azevedo, V.; Langella, P.; Bermudez-Humaran, L.G. Anti-tumoral Effects of Recombinant Lactococcus lactis Strain Secreting IL-17A Cytokine. Front. Microbiol. 2018, 9, 3355. [Google Scholar] [CrossRef] [Green Version]
  49. Neirynck, S.; Steidler, L. Delivery of therapeutic proteins through Lactococcus lactis. Biotechnol. Genet. Eng. Rev. 2006, 22, 253–266. [Google Scholar] [CrossRef] [Green Version]
  50. Hou, W.; Li, J.; Cao, Z.; Lin, S.; Pan, C.; Pang, Y.; Liu, J. Decorating Bacteria with a Therapeutic Nanocoating for Synergistically Enhanced Biotherapy. Small 2021, 17, e2101810. [Google Scholar] [CrossRef]
  51. Seiwerth, S.; Rucman, R.; Turkovic, B.; Sever, M.; Klicek, R.; Radic, B.; Drmic, D.; Stupnisek, M.; Misic, M.; Vuletic, L.B.; et al. BPC 157 and Standard Angiogenic Growth Factors. Gastrointestinal Tract Healing, Lessons from Tendon, Ligament, Muscle and Bone Healing. Curr. Pharm. Des. 2018, 24, 1972–1989. [Google Scholar] [CrossRef]
  52. Skrlec, K.; Rucman, R.; Jarc, E.; Sikiric, P.; Svajger, U.; Petan, T.; Perisic Nanut, M.; Strukelj, B.; Berlec, A. Engineering recombinant Lactococcus lactis as a delivery vehicle for BPC-157 peptide with antioxidant activities. Appl. Microbiol. Biotechnol. 2018, 102, 10103–10117. [Google Scholar] [CrossRef] [PubMed]
  53. Ginn, S.L.; Amaya, A.K.; Alexander, I.E.; Edelstein, M.; Abedi, M.R. Gene therapy clinical trials worldwide to 2017: An update. J. Gene Med. 2018, 20, e3015. [Google Scholar] [CrossRef]
  54. Motta, J.P.; Bermudez-Humaran, L.G.; Deraison, C.; Martin, L.; Rolland, C.; Rousset, P.; Boue, J.; Dietrich, G.; Chapman, K.; Kharrat, P.; et al. Food-grade bacteria expressing elafin protect against inflammation and restore colon homeostasis. Sci. Transl. Med. 2012, 4, 158ra144. [Google Scholar] [CrossRef] [PubMed]
  55. Woo, S.G.; Moon, S.J.; Kim, S.K.; Kim, T.H.; Lim, H.S.; Yeon, G.H.; Sung, B.H.; Lee, C.H.; Lee, S.G.; Hwang, J.H.; et al. A designed whole-cell biosensor for live diagnosis of gut inflammation through nitrate sensing. Biosens. Bioelectron. 2020, 168, 112523. [Google Scholar] [CrossRef] [PubMed]
  56. Naydich, A.D.; Nangle, S.N.; Bues, J.J.; Trivedi, D.; Nissar, N.; Inniss, M.C.; Niederhuber, M.J.; Way, J.C.; Silver, P.A.; Riglar, D.T. Synthetic Gene Circuits Enable Systems-Level Biosensor Trigger Discovery at the Host-Microbe Interface. mSystems 2019, 4, e00125-19. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  57. Drolia, R.; Amalaradjou, M.A.R.; Ryan, V.; Tenguria, S.; Liu, D.; Bai, X.; Xu, L.; Singh, A.K.; Cox, A.D.; Bernal-Crespo, V.; et al. Receptor-targeted engineered probiotics mitigate lethal Listeria infection. Nat. Commun. 2020, 11, 6344. [Google Scholar] [CrossRef]
  58. Praveschotinunt, P.; Duraj-Thatte, A.M.; Gelfat, I.; Bahl, F.; Chou, D.B.; Joshi, N.S. Engineered E. coli Nissle 1917 for the delivery of matrix-tethered therapeutic domains to the gut. Nat. Commun. 2019, 10, 5580. [Google Scholar] [CrossRef] [Green Version]
  59. Hwang, I.Y.; Koh, E.; Wong, A.; March, J.C.; Bentley, W.E.; Lee, Y.S.; Chang, M.W. Engineered probiotic Escherichia coli can eliminate and prevent Pseudomonas aeruginosa gut infection in animal models. Nat. Commun. 2017, 8, 15028. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  60. Shi, D.; Song, Y.; Li, Y.J. Progress on lactococcus lactis expressing heterologous antigens as live mucosal vaccines. Wei Sheng Wu Xue Bao 2006, 46, 680–683. [Google Scholar]
  61. Zadravec, P.; Strukelj, B.; Berlec, A. Improvement of LysM-mediated surface display of designed ankyrin repeat proteins (DARPins) in recombinant and nonrecombinant strains of Lactococcus lactis and Lactobacillus Species. Appl. Environ. Microbiol. 2015, 81, 2098–2106. [Google Scholar] [CrossRef] [Green Version]
  62. Tay, P.K.R.; Lim, P.Y.; Ow, D.S. A SH3_5 Cell Anchoring Domain for Non-recombinant Surface Display on Lactic Acid Bacteria. Front. Bioeng. Biotechnol. 2020, 8, 614498. [Google Scholar] [CrossRef] [PubMed]
  63. Jiang, T.; Singh, B.; Maharjan, S.; Li, H.S.; Kang, S.K.; Bok, J.D.; Cho, C.S.; Choi, Y.J. Oral delivery of probiotic expressing M cell homing peptide conjugated BmpB vaccine encapsulated into alginate/chitosan/alginate microcapsules. Eur. J. Pharm. Biopharm. 2014, 88, 768–777. [Google Scholar] [CrossRef] [PubMed]
  64. Kim, J.I.; Park, T.E.; Maharjan, S.; Li, H.S.; Lee, H.B.; Kim, I.S.; Piao, D.; Lee, J.Y.; Cho, C.S.; Bok, J.D.; et al. Soluble RANKL expression in Lactococcus lactis and investigation of its potential as an oral vaccine adjuvant. BMC Immunol. 2015, 16, 71. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  65. Smaldini, P.L.; Ibanez, A.E.; Fossati, C.A.; Cassataro, J.; Docena, G.H. Oral delivery of Brucella spp. recombinant protein U-Omp16 abrogates the IgE-mediated milk allergy. Hum. Vaccin. Immunother. 2014, 10, 2015–2023. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  66. Stojanov, S.; Berlec, A. Electrospun Nanofibers as Carriers of Microorganisms, Stem Cells, Proteins, and Nucleic Acids in Therapeutic and Other Applications. Front. Bioeng. Biotechnol. 2020, 8, 130. [Google Scholar] [CrossRef] [PubMed]
  67. Aied, A.; Greiser, U.; Pandit, A.; Wang, W. Polymer gene delivery: Overcoming the obstacles. Drug Discov. Today 2013, 18, 1090–1098. [Google Scholar] [CrossRef] [PubMed]
  68. O’Driscoll, C.M.; Bernkop-Schnurch, A.; Friedl, J.D.; Preat, V.; Jannin, V. Oral delivery of non-viral nucleic acid-based therapeutics—Do we have the guts for this? Eur. J. Pharm. Sci. 2019, 133, 190–204. [Google Scholar] [CrossRef] [PubMed]
  69. Yu, C.; Li, L.; Hu, P.; Yang, Y.; Wei, W.; Deng, X.; Wang, L.; Tay, F.R.; Ma, J. Recent Advances in Stimulus-Responsive Nanocarriers for Gene Therapy. Adv. Sci. 2021, 8, 2100540. [Google Scholar] [CrossRef]
  70. Hossian, A.; Mackenzie, G.G.; Mattheolabakis, G. miRNAs in gastrointestinal diseases: Can we effectively deliver RNA-based therapeutics orally? Nanomedicine 2019, 14, 2873–2889. [Google Scholar] [CrossRef]
  71. Loessner, H.; Weiss, S. Bacteria-mediated DNA transfer in gene therapy and vaccination. Expert Opin. Biol. Ther. 2004, 4, 157–168. [Google Scholar] [CrossRef]
  72. Reisfeld, R.A.; Niethammer, A.G.; Luo, Y.; Xiang, R. DNA vaccines designed to inhibit tumor growth by suppression of angiogenesis. Int. Arch. Allergy Immunol. 2004, 133, 295–304. [Google Scholar] [CrossRef] [PubMed]
  73. Mohit, E.; Rafati, S. Biological delivery approaches for gene therapy: Strategies to potentiate efficacy and enhance specificity. Mol. Immunol. 2013, 56, 599–611. [Google Scholar] [CrossRef] [PubMed]
  74. Hu, Q.; Wu, M.; Fang, C.; Cheng, C.; Zhao, M.; Fang, W.; Chu, P.K.; Ping, Y.; Tang, G. Engineering nanoparticle-coated bacteria as oral DNA vaccines for cancer immunotherapy. Nano Lett. 2015, 15, 2732–2739. [Google Scholar] [CrossRef] [PubMed]
  75. Sinha, S.; Kuo, C.Y.; Ho, J.K.; White, P.J.; Jazayeri, J.A.; Pouton, C.W. A suicidal strain of Listeria monocytogenes is effective as a DNA vaccine delivery system for oral administration. Vaccine 2017, 35, 5115–5122. [Google Scholar] [CrossRef]
  76. Baban, C.K.; Cronin, M.; O’Hanlon, D.; O’Sullivan, G.C.; Tangney, M. Bacteria as vectors for gene therapy of cancer. Bioeng. Bugs. 2010, 1, 385–394. [Google Scholar] [CrossRef] [Green Version]
  77. Hou, R.; Li, M.; Tang, T.; Wang, R.; Li, Y.; Xu, Y.; Tang, L.; Wang, L.; Liu, M.; Jiang, Y.; et al. Construction of Lactobacillus casei ghosts by Holin-mediated inactivation and the potential as a safe and effective vehicle for the delivery of DNA vaccines. BMC Microbiol. 2018, 18, 80. [Google Scholar] [CrossRef]
  78. Wen, J.; Yang, Y.; Zhao, G.; Tong, S.; Yu, H.; Jin, X.; Du, L.; Jiang, S.; Kou, Z.; Zhou, Y. Salmonella typhi Ty21a bacterial ghost vector augments HIV-1 gp140 DNA vaccine-induced peripheral and mucosal antibody responses via TLR4 pathway. Vaccine 2012, 30, 5733–5739. [Google Scholar] [CrossRef]
  79. Herbert, J.A.; Kay, E.J.; Faustini, S.E.; Richter, A.; Abouelhadid, S.; Cuccui, J.; Wren, B.; Mitchell, T.J. Production and efficacy of a low-cost recombinant pneumococcal protein polysaccharide conjugate vaccine. Vaccine 2018, 36, 3809–3819. [Google Scholar] [CrossRef]
  80. Huang, J.; Pan, C.; Sun, P.; Feng, E.; Wu, J.; Zhu, L.; Wang, H. Application of an O-Linked Glycosylation System in Yersinia enterocolitica Serotype O:9 to Generate a New Candidate Vaccine against Brucella abortus. Microorganisms 2020, 8, 436. [Google Scholar] [CrossRef] [Green Version]
  81. Harding, C.M.; Nasr, M.A.; Scott, N.E.; Goyette-Desjardins, G.; Nothaft, H.; Mayer, A.E.; Chavez, S.M.; Huynh, J.P.; Kinsella, R.L.; Szymanski, C.M.; et al. A platform for glycoengineering a polyvalent pneumococcal bioconjugate vaccine using E. coli as a host. Nat. Commun. 2019, 10, 891. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  82. Su, H.; Liu, Q.; Bian, X.; Wang, S.; Curtiss, R., 3rd; Kong, Q. Synthesis and delivery of Streptococcus pneumoniae capsular polysaccharides by recombinant attenuated Salmonella vaccines. Proc. Natl. Acad. Sci. USA 2021, 118, e2013350118. [Google Scholar] [CrossRef] [PubMed]
  83. Anselmo, A.C.; McHugh, K.J.; Webster, J.; Langer, R.; Jaklenec, A. Layer-by-Layer Encapsulation of Probiotics for Delivery to the Microbiome. Adv. Mater. 2016, 28, 9486–9490. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  84. Sinha, V.R.; Kumria, R. Polysaccharides in colon-specific drug delivery. Int. J. Pharm. 2001, 224, 19–38. [Google Scholar] [CrossRef]
  85. Chadha, S.; Kumar, A.; Srivastava, S.A.; Behl, T.; Ranjan, R. Inulin as a Delivery Vehicle for Targeting Colon-Specific Cancer. Curr. Drug Deliv. 2020, 17, 651–674. [Google Scholar] [CrossRef]
  86. Pan, C.; Li, J.; Hou, W.; Lin, S.; Wang, L.; Pang, Y.; Wang, Y.; Liu, J. Polymerization-Mediated Multifunctionalization of Living Cells for Enhanced Cell-Based Therapy. Adv. Mater. 2021, 33, e2007379. [Google Scholar] [CrossRef]
  87. Inda, M.E.; Lu, T.K. Microbes as Biosensors. Annu. Rev. Microbiol. 2020, 74, 337–359. [Google Scholar] [CrossRef]
  88. Rottinghaus, A.G.; Amrofell, M.B.; Moon, T.S. Biosensing in Smart Engineered Probiotics. Biotechnol. J. 2020, 15, e1900319. [Google Scholar] [CrossRef]
  89. Sedlmayer, F.; Aubel, D.; Fussenegger, M. Synthetic gene circuits for the detection, elimination and prevention of disease. Nat. Biomed. Eng. 2018, 2, 399–415. [Google Scholar] [CrossRef]
  90. Fan, Y.; Pedersen, O. Gut microbiota in human metabolic health and disease. Nat. Rev. Microbiol. 2021, 19, 55–71. [Google Scholar] [CrossRef]
  91. Cao, Z.; Wang, X.; Pang, Y.; Cheng, S.; Liu, J. Biointerfacial self-assembly generates lipid membrane coated bacteria for enhanced oral delivery and treatment. Nat. Commun. 2019, 10, 5783. [Google Scholar] [CrossRef]
  92. Maresca, D.; Lakshmanan, A.; Abedi, M.; Bar-Zion, A.; Farhadi, A.; Lu, G.J.; Szablowski, J.O.; Wu, D.; Yoo, S.; Shapiro, M.G. Biomolecular Ultrasound and Sonogenetics. Annu. Rev. Chem. Biomol. Eng. 2018, 9, 229–252. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  93. Yang, H.; Jiang, F.; Ji, X.; Wang, L.; Wang, Y.; Zhang, L.; Tang, Y.; Wang, D.; Luo, Y.; Li, N.; et al. Genetically Engineered Bacterial Protein Nanoparticles for Targeted Cancer Therapy. Int. J. Nanomed. 2021, 16, 105–117. [Google Scholar] [CrossRef] [PubMed]
  94. Alexander, J.L.; Wilson, I.D.; Teare, J.; Marchesi, J.R.; Nicholson, J.K.; Kinross, J.M. Gut microbiota modulation of chemotherapy efficacy and toxicity. Nat. Rev. Gastroenterol. Hepatol. 2017, 14, 356–365. [Google Scholar] [CrossRef] [PubMed]
  95. Eom, T.; Kim, Y.S.; Choi, C.H.; Sadowsky, M.J.; Unno, T. Current understanding of microbiota- and dietary-therapies for treating inflammatory bowel disease. J. Microbiol. 2018, 56, 189–198. [Google Scholar] [CrossRef] [PubMed]
  96. Knip, M.; Siljander, H. The role of the intestinal microbiota in type 1 diabetes mellitus. Nat. Rev. Endocrinol. 2016, 12, 154–167. [Google Scholar] [CrossRef] [PubMed]
  97. Lau, L.H.S.; Wong, S.H. Microbiota, Obesity and NAFLD. Adv. Exp. Med. Biol. 2018, 1061, 111–125. [Google Scholar] [CrossRef]
  98. Korpela, K.; Helve, O.; Kolho, K.L.; Saisto, T.; Skogberg, K.; Dikareva, E.; Stefanovic, V.; Salonen, A.; Andersson, S.; de Vos, W.M. Maternal Fecal Microbiota Transplantation in Cesarean-Born Infants Rapidly Restores Normal Gut Microbial Development: A Proof-of-Concept Study. Cell 2020, 183, 324–334. [Google Scholar] [CrossRef]
  99. Nishiyama, K.; Kobayashi, T.; Sato, Y.; Watanabe, Y.; Kikuchi, R.; Kanno, R.; Koshizuka, T.; Miyazaki, N.; Ishioka, K.; Suzutani, T. A Double-Blind Controlled Study to Evaluate the Effects of Yogurt Enriched with Lactococcus lactis 11/19-B1 and Bifidobacterium lactis on Serum Low-Density Lipoprotein Level and Antigen-Specific Interferon-gamma Releasing Ability. Nutrients 2018, 10, 1778. [Google Scholar] [CrossRef] [Green Version]
  100. Pontes, D.S.; de Azevedo, M.S.; Chatel, J.M.; Langella, P.; Azevedo, V.; Miyoshi, A. Lactococcus lactis as a live vector: Heterologous protein production and DNA delivery systems. Protein Expr. Purif. 2011, 79, 165–175. [Google Scholar] [CrossRef]
  101. Hou, C.L.; Zhang, J.; Liu, X.T.; Liu, H.; Zeng, X.F.; Qiao, S.Y. Superoxide dismutase recombinant Lactobacillus fermentum ameliorates intestinal oxidative stress through inhibiting NF-kappaB activation in a trinitrobenzene sulphonic acid-induced colitis mouse model. J. Appl. Microbiol. 2014, 116, 1621–1631. [Google Scholar] [CrossRef]
  102. Carvalho, R.D.O.; do Carmo, F.L.R.; de Oliveira Junior, A.; Langella, P.; Chatel, J.M.; Bermudez-Humaran, L.G.; Azevedo, V.; de Azevedo, M.S. Use of Wild Type or Recombinant Lactic Acid Bacteria as an Alternative Treatment for Gastrointestinal Inflammatory Diseases: A Focus on Inflammatory Bowel Diseases and Mucositis. Front. Microbiol. 2017, 8, 800. [Google Scholar] [CrossRef] [PubMed]
  103. Itoh, Y.; Wang, X.; Hinnebusch, B.J.; Preston, J.F., 3rd; Romeo, T. Depolymerization of beta-1,6-N-acetyl-D-glucosamine disrupts the integrity of diverse bacterial biofilms. J. Bacteriol. 2005, 187, 382–387. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  104. Bray, F.; Ferlay, J.; Soerjomataram, I.; Siegel, R.L.; Torre, L.A.; Jemal, A. Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J. Clin. 2018, 68, 394–424. [Google Scholar] [CrossRef] [Green Version]
  105. Patyar, S.; Joshi, R.; Byrav, D.S.; Prakash, A.; Medhi, B.; Das, B.K. Bacteria in cancer therapy: A novel experimental strategy. J. Biomed. Sci. 2010, 17, 21. [Google Scholar] [CrossRef] [Green Version]
  106. Richardson, M.A.; Ramirez, T.; Russell, N.C.; Moye, L.A. Coley toxins immunotherapy: A retrospective review. Altern. Ther. Health Med. 1999, 5, 42–47. [Google Scholar]
  107. Liang, K.; Liu, Q.; Li, P.; Luo, H.; Wang, H.; Kong, Q. Genetically engineered Salmonella Typhimurium: Recent advances in cancer therapy. Cancer Lett. 2019, 448, 168–181. [Google Scholar] [CrossRef]
  108. Lou, X.; Chen, Z.; He, Z.; Sun, M.; Sun, J. Bacteria-Mediated Synergistic Cancer Therapy: Small Microbiome Has a Big Hope. Nanomicro. Lett. 2021, 13, 37. [Google Scholar] [CrossRef]
  109. McKay, R.; Ghodasra, M.; Schardt, J.; Quan, D.; Pottash, A.E.; Shang, W.; Jay, S.M.; Payne, G.F.; Chang, M.W.; March, J.C.; et al. A platform of genetically engineered bacteria as vehicles for localized delivery of therapeutics: Toward applications for Crohn’s disease. Bioeng. Transl. Med. 2018, 3, 209–221. [Google Scholar] [CrossRef] [PubMed]
  110. Chung, Y.; Ryu, Y.; An, B.C.; Yoon, Y.S.; Choi, O.; Kim, T.Y.; Yoon, J.; Ahn, J.Y.; Park, H.J.; Kwon, S.K.; et al. A synthetic probiotic engineered for colorectal cancer therapy modulates gut microbiota. Microbiome 2021, 9, 122. [Google Scholar] [CrossRef] [PubMed]
  111. Fan, J.X.; Li, Z.H.; Liu, X.H.; Zheng, D.W.; Chen, Y.; Zhang, X.Z. Bacteria-Mediated Tumor Therapy Utilizing Photothermally-Controlled TNF-alpha Expression via Oral Administration. Nano Lett. 2018, 18, 2373–2380. [Google Scholar] [CrossRef] [PubMed]
  112. Ryan, R.M.; Green, J.; Williams, P.J.; Tazzyman, S.; Hunt, S.; Harmey, J.H.; Kehoe, S.C.; Lewis, C.E. Bacterial delivery of a novel cytolysin to hypoxic areas of solid tumors. Gene Ther. 2009, 16, 329–339. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  113. Pamer, E.G. Immune responses to Listeria monocytogenes. Nat. Rev. Immunol 2004, 4, 812–823. [Google Scholar] [CrossRef]
  114. Kaufman, H.L.; Flanagan, K.; Lee, C.S.; Perretta, D.J.; Horig, H. Insertion of interleukin-2 (IL-2) and interleukin-12 (IL-12) genes into vaccinia virus results in effective anti-tumor responses without toxicity. Vaccine 2002, 20, 1862–1869. [Google Scholar] [CrossRef]
  115. Wei, P.; Yang, Y.; Li, T.; Ding, Q.; Sun, H. A engineered Bifidobacterium longum secreting a bioative penetratin-Glucagon-like peptide 1 fusion protein enhances Glucagon-like peptide 1 absorption in the intestine. J. Microbiol. Biotechnol. 2015. Available online: https://www.researchgate.net/publication/272188048_A_engineered_Bifidobacterium_longum_secreting_a_bioative_penetratin-Glucagon-like_peptide_1_fusion_protein_enhances_Glucagon-like_peptide_1_absorption_in_the_intestine (accessed on 1 Ocotber 2021).
  116. Hartmann, P.; Chen, P.; Wang, H.J.; Wang, L.; McCole, D.F.; Brandl, K.; Starkel, P.; Belzer, C.; Hellerbrand, C.; Tsukamoto, H.; et al. Deficiency of intestinal mucin-2 ameliorates experimental alcoholic liver disease in mice. Hepatology 2013, 58, 108–119. [Google Scholar] [CrossRef] [PubMed] [Green Version]
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Figure 1. Schematic illustration of the oral delivery of therapeutic biomacromolecules by bacteria-based microdevices for disease diagnosis and treatment.
Figure 1. Schematic illustration of the oral delivery of therapeutic biomacromolecules by bacteria-based microdevices for disease diagnosis and treatment.
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Figure 2. Engineered bacteria for the oral delivery of therapeutic proteins. (A) Oral delivery of heterogeneous interleukin (IL)-35 expressed by genetically modified bacteria. Adapted from [47], published by Springer, 2019. (B) Oral co-delivery of therapeutic silk fibroin and probiotics through self-assembly on the surface of bacteria for synergistically enhanced biotherapy. Adapted with permission from [50]; published by Wiley-VCH, 2021.
Figure 2. Engineered bacteria for the oral delivery of therapeutic proteins. (A) Oral delivery of heterogeneous interleukin (IL)-35 expressed by genetically modified bacteria. Adapted from [47], published by Springer, 2019. (B) Oral co-delivery of therapeutic silk fibroin and probiotics through self-assembly on the surface of bacteria for synergistically enhanced biotherapy. Adapted with permission from [50]; published by Wiley-VCH, 2021.
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Figure 3. Engineered bacteria for the oral delivery of nucleic acids. (A) DNA nanoparticle-decorated bacteria as an oral vaccine for cancer therapy. Adapted from [74], published by American Chemical Society, 2015. (B) DNA vaccines orally delivered by bacterial ghost for HIV. Adapted from [78], published by Elsevier BV, 2012.
Figure 3. Engineered bacteria for the oral delivery of nucleic acids. (A) DNA nanoparticle-decorated bacteria as an oral vaccine for cancer therapy. Adapted from [74], published by American Chemical Society, 2015. (B) DNA vaccines orally delivered by bacterial ghost for HIV. Adapted from [78], published by Elsevier BV, 2012.
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Figure 4. Engineered bacteria for oral delivery of therapeutic polysaccharides. (A) Oral delivery of Streptococcus pneumoniae capsular polysaccharides produced by recombinant attenuated Salmonella. Adapted from [82], published by National Academy of Sciences, 2021. (B) Attachment of chitosan on the surface of probiotics for enhanced oral delivery and biotherapy. Adapted with permission from [86]; published by Wiley-VCH, 2021.
Figure 4. Engineered bacteria for oral delivery of therapeutic polysaccharides. (A) Oral delivery of Streptococcus pneumoniae capsular polysaccharides produced by recombinant attenuated Salmonella. Adapted from [82], published by National Academy of Sciences, 2021. (B) Attachment of chitosan on the surface of probiotics for enhanced oral delivery and biotherapy. Adapted with permission from [86]; published by Wiley-VCH, 2021.
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Figure 5. Programmed bacteria for diagnosis and bioimaging. (A) Genetically modified probiotics for noninvasive cancer diagnosis. Adapted with permission from [27]; published by BioMed Central, 2015. (B) Ultrasound imaging of engineered bacteria-carrying acoustic reporter genes in the gastrointestinal (GI) tract. Adapted with permission from [34]; published by Nature Research, 2018.
Figure 5. Programmed bacteria for diagnosis and bioimaging. (A) Genetically modified probiotics for noninvasive cancer diagnosis. Adapted with permission from [27]; published by BioMed Central, 2015. (B) Ultrasound imaging of engineered bacteria-carrying acoustic reporter genes in the gastrointestinal (GI) tract. Adapted with permission from [34]; published by Nature Research, 2018.
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Figure 6. Engineered Lactobacillus for treating Listeria infection. (A) Detection of the expression of LAP from Listeria by western blot, showing LAP presenting in both the cell wall and whole-cell fractions of engineered Lactobacillus strains. (B) Immunofluorescence images of LAP expressed successfully on the surface of engineered Lactobacillus. (C) Schematic illustration of the mechanism for the protection effect of engineered Lactobacillus against listeriosis. Adapted with permission from [57]; published by Springer Nature, 2020.
Figure 6. Engineered Lactobacillus for treating Listeria infection. (A) Detection of the expression of LAP from Listeria by western blot, showing LAP presenting in both the cell wall and whole-cell fractions of engineered Lactobacillus strains. (B) Immunofluorescence images of LAP expressed successfully on the surface of engineered Lactobacillus. (C) Schematic illustration of the mechanism for the protection effect of engineered Lactobacillus against listeriosis. Adapted with permission from [57]; published by Springer Nature, 2020.
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Figure 7. Bioengineered EcN for inflammatory bowel disease (IBD) treatment. (A) Self-assembly of modified curli into fibrous matrices. (B) Structure of curli fiber protein CsgA (yellow) fused with the trefoil factor domain (green). (C) Oral delivery of engineered probiotics to the site of inflammation in the GI tract. (D) Schematic illustration of the protective mechanisms of engineered probiotics in IBDs. Adapted with permission from [58]; published by Frontiers Media S.A, 2017.
Figure 7. Bioengineered EcN for inflammatory bowel disease (IBD) treatment. (A) Self-assembly of modified curli into fibrous matrices. (B) Structure of curli fiber protein CsgA (yellow) fused with the trefoil factor domain (green). (C) Oral delivery of engineered probiotics to the site of inflammation in the GI tract. (D) Schematic illustration of the protective mechanisms of engineered probiotics in IBDs. Adapted with permission from [58]; published by Frontiers Media S.A, 2017.
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Figure 8. Oral delivery of bioengineered E. coli for cancer therapy. (A) Scheme of the mechanism of TNF-α expression in plasmid pBV220. (B) Preparation of thermally sensitive bacteria (TPB@Au). (C) Therapeutic effects and mechanism of the orally delivered TPB@Au. Adapted with permission from [111]; published by American Chemical Society, 2018.
Figure 8. Oral delivery of bioengineered E. coli for cancer therapy. (A) Scheme of the mechanism of TNF-α expression in plasmid pBV220. (B) Preparation of thermally sensitive bacteria (TPB@Au). (C) Therapeutic effects and mechanism of the orally delivered TPB@Au. Adapted with permission from [111]; published by American Chemical Society, 2018.
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Table
Table 1. Therapeutic biomacromolecules orally delivered by bacteria for treating intestinal infectious diseases.
Table 1. Therapeutic biomacromolecules orally delivered by bacteria for treating intestinal infectious diseases.
Bacteria Species Therapeutic AgentsModification StrategiesTypes of TherapyRefs
Lactococcus lactisIL-35Genetic modification Dextran sulfate sodium (DSS)-induced colitis[32]
Escherichia coli (E. coli) Nissle 1917Silk fibroinSurface decorationDSS-induced colitis[33]
Lactococcus lactisElafin Genetic modification Inflammatory bowel disease (IBD)[51]
Lactococcus lactisIL-10Genetic modification IBD[52]
Salmonella typhimuriumStreptococcus pneumoniae capsular polysaccharidesGenetic modification Streptococcus pneumoniae infection[53]
E. coli Nissle 1917ChitosanSurface decorationDSS-induced colitis[54]
E. coliA responsive genetic circuit Genetic modificationInflammation disease diagnosis [55,56]
Lactobacillus caseiListeria adhesion proteinGenetic modificationListeria infection [57]
E. coli Nissle 1917Trefoil factorGenetic modificationIBD[58]
E. coli Nissle 1917Dispersin B (DspB)Genetic modificationGut infection [59]
Table
Table 2. Therapeutic biomacromolecules orally delivered for bacteria-mediated cancer therapy.
Table 2. Therapeutic biomacromolecules orally delivered for bacteria-mediated cancer therapy.
Bacteria Species Therapeutic AgentsModification StrategiesTypes of TherapyRefs
E. coli Nissle 1917LacZ (plasmid)
luxCDABE (genomic)		Genetic modificationCancer diagnosis[27]
Lactococcus lactisIL-17AGenetic modification Cancer[48]
Lactococcus lactisIL-2Genetic modification Cancer[49]
Salmonella typhimuriumDNASurface decorationCancer[74]
Pediococcus pentosaceusP8Genetic modificationCancer[110]
E. coliTNF-αGenetic modification Cancer[111]
Table
Table 3. Therapeutic biomacromolecules based on oral bacterial microdevices for treating other diseases.
Table 3. Therapeutic biomacromolecules based on oral bacterial microdevices for treating other diseases.
Bacteria Species Therapeutic AgentsModification StrategiesTypes of TherapyRefs
Lactococcus lactisGLP-1Genetic modificationDiabetes[41]
Lactococcus lactisInsulinGenetic modificationDiabetes[45]
Lactobacillus reuteriIL-22Genetic modificationEthanol-induced liver disease[46]
Salmonella typhimurium derived bacterial ghostgp-140 DNALoadingHIV-1[78]
Bifidobacterium longumGlucagon-like peptide-1 (GLP-1)Genetic modificationDiabetes[115]
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Cao, Z.; Lin, S.; Liu, J. Bacteria-Based Microdevices for the Oral Delivery of Macromolecules. Pharmaceutics 2021, 13, 1610. https://doi.org/10.3390/pharmaceutics13101610

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Cao Z, Lin S, Liu J. Bacteria-Based Microdevices for the Oral Delivery of Macromolecules. Pharmaceutics. 2021; 13(10):1610. https://doi.org/10.3390/pharmaceutics13101610

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Cao, Zhenping, Sisi Lin, and Jinyao Liu. 2021. "Bacteria-Based Microdevices for the Oral Delivery of Macromolecules" Pharmaceutics 13, no. 10: 1610. https://doi.org/10.3390/pharmaceutics13101610

APA Style

Cao, Z., Lin, S., & Liu, J. (2021). Bacteria-Based Microdevices for the Oral Delivery of Macromolecules. Pharmaceutics, 13(10), 1610. https://doi.org/10.3390/pharmaceutics13101610

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