Bacterial ghosts as adjuvant to oxaliplatin chemotherapy in colorectal carcinomatosis

Bacteria colonization in tumor microenvironment creates a favorable niche for immunogenic chemotherapy

The tumor microenvironment (TME) presents differential selective pressure (DSP) that favors the growth of cancer cells, and monovalent therapy is often inadequate in reversing the cancer cell dominance in the TME. In this work, we introduce bacteria as a foreign species to the TME and explore combinatorial treatment strategies to alter DSP for tumor eradication. We show that cancer-selective chemotherapeutic agents and fasting can provide a strong selection pressure against tumor growth in the presence of bacteria. Moreover, we show that an immunogenic drug (oxaliplatin), but not a non-immunogenic one (5-FU), synergizes with the bacteria to activate both the innate and adaptive immunity in the TME, resulting in complete tumor remission and a sustained anti-tumor immunological memory in mice. The combination of oxaliplatin and bacteria greatly enhances the co-stimulatory and antigen-presenting molecules on antigen-presenting cells, which in turn bridge the cytotoxic T cells for cancer-cell killing. Our findings indicate that rational combination of bacterial therapy and immunogenic chemotherapy can promote anticancer immunity against the immunosuppressive TME.

Bacteria and Bacterial Components as Natural Bio-Nanocarriers for Drug and Gene Delivery Systems in Cancer Therapy

Bacteria and bacterial components possess multifunctional properties, making them attractive natural bio-nanocarriers for cancer diagnosis and targeted treatment. The inherent tropic and motile nature of bacteria allows them to grow and colonize in hypoxic tumor microenvironments more readily than conventional therapeutic agents and other nanomedicines. However, concerns over biosafety, limited antitumor efficiency, and unclear tumor-targeting mechanisms have restricted the clinical translation and application of natural bio-nanocarriers based on bacteria and bacterial components. Fortunately, bacterial therapies combined with engineering strategies and nanotechnology may be able to reverse a number of challenges for bacterial/bacterial component-based cancer biotherapies. Meanwhile, the combined strategies tend to enhance the versatility of bionanoplasmic nanoplatforms to improve biosafety and inhibit tumorigenesis and metastasis. This review summarizes the advantages and challenges of bacteria and bacterial components in cancer therapy, outlines combinatorial strategies for nanocarriers and bacterial/bacterial components, and discusses their clinical applications.

Prodigiosin-Functionalized Probiotic Ghosts as a Bioinspired Combination Against Colorectal Cancer Cells

Lactobacillus acidophilus ghosts (LAGs) with the unique safety of a probiotic, inherent tropism for colon cells, and multiple bioactivities offer promise as drug carriers for colon targeting. Our objective was to evaluate LAGs functionalized with prodigiosin (PG), apoptotic secondary bacterial metabolite, as a bioinspired formulation against colorectal cancer (CRC). LAGs were prepared by a chemical method and highly purified by density gradient centrifugation. LAGs were characterized by microscopic and staining techniques as relatively small-sized uniform vesicles (≈1.6 µm), nearly devoid of cytoplasmic and genetic materials and having a negatively charged intact envelope. PG was highly bound to LAGs envelope, generating a physiologically stable bioactive entity (PG-LAGs), as verified by multiple microscopic techniques and lack of PG release under physiological conditions. PG-LAGs were active against HCT116 CRC cells at both the cellular and molecular levels. Cell viability data highlighted the cytotoxicity of PG and LAGs and LAGs-induced enhancement of PG selectivity for HCT116 cells, anticipating dose reduction for PG and LAGs. Molecularly, expression of the apoptotic caspase 3 and P53 biomarkers in HCT116 intracellular proteins was significantly upregulated while that of the anti-apoptotic Bcl-2 (B-cell lymphoma 2) was downregulated by PG-LAGs relative to PG and 5-fluorouracil. PG-LAGs provide a novel bacteria-based combination for anticancer biomedicine.

Stimulators of immunogenic cell death for cancer therapy: focusing on natural compounds

A growing body of evidence indicates that the anticancer effect of the immune system can be activated by the immunogenic modulation of dying cancer cells. Cancer cell death, as a result of the activation of an immunomodulatory response, is called immunogenic cell death (ICD). This regulated cell death occurs because of increased immunogenicity of cancer cells undergoing ICD. ICD plays a crucial role in stimulating immune system activity in cancer therapy. ICD can therefore be an innovative route to improve anticancer immune responses associated with releasing damage-associated molecular patterns (DAMPs). Several conventional and chemotherapeutics, as well as preclinically investigated compounds from natural sources, possess immunostimulatory properties by ICD induction. Natural compounds have gained much interest in cancer therapy owing to their low toxicity, low cost, and inhibiting cancer cells by interfering with different mechanisms, which are critical in cancer progression. Therefore, identifying natural compounds with ICD-inducing potency presents agents with promising potential in cancer immunotherapy. Naturally derived compounds are believed to act as immunoadjuvants because they elicit cancer stress responses and DAMPs. Acute exposure to DAMP molecules can activate antigen-presenting cells (APCs), such as dendritic cells (DCs), which leads to downstream events by cytotoxic T lymphocytes (CTLs) and natural killer cells (NKs). Natural compounds as inducers of ICD may be an interesting approach to ICD induction; however, parameters that determine whether a compound can be used as an ICD inducer should be elucidated. Here, we aimed to discuss the impact of multiple ICD inducers, mainly focusing on natural agents, including plant-derived, marine molecules, and bacterial-based compounds, on the release of DAMP molecules and the activation of the corresponding signaling cascades triggering immune responses. In addition, the potential of synthetic agents for triggering ICD is also discussed.

Biomembrane nanostructures: Multifunctional platform to enhance tumor chemoimmunotherapy via effective drug delivery

Chemotherapeutic drugs have been found to activate the immune response against tumors by inducing immunogenic cell death, in addition to their direct cytotoxic effects toward tumors, therefore broadening the application of chemotherapy in tumor immunotherapy. The combination of other therapeutic strategies, such as phototherapy or radiotherapy, could further strengthen the therapeutic effects of immunotherapy. Nanostructures can facilitate multimodal tumor therapy by integrating various active agents and combining multiple types of therapeutics in a single nanostructure. Biomembrane nanostructures (e.g., exosomes and cell membrane-derived nanostructures), characterized by superior biocompatibility, intrinsic targeting ability, intelligent responsiveness and immune-modulating properties, could realize superior chemoimmunotherapy and represent next-generation nanostructures for tumor immunotherapy. This review summarizes recent advances in biomembrane nanostructures in tumor chemoimmunotherapy and highlights different types of engineering approaches and therapeutic mechanisms. A series of engineering strategies for combining different biomembrane nanostructures, including liposomes, exosomes, cell membranes and bacterial membranes, are summarized. The combination strategy can greatly enhance the targeting, intelligence and functionality of biomembrane nanostructures for chemoimmunotherapy, thereby serving as a stronger tumor therapeutic method. The challenges associated with the clinical translation of biomembrane nanostructures for chemoimmunotherapy and their future perspectives are also discussed.

Bacteria-based immunotherapy for cancer: a systematic review of preclinical studies

Immunotherapy has been emerging as a powerful strategy for cancer management. Recently, accumulating evidence has demonstrated that bacteria-based immunotherapy including naive bacteria, bacterial components, and bacterial derivatives, can modulate immune response via various cellular and molecular pathways. The key mechanisms of bacterial antitumor immunity include inducing immune cells to kill tumor cells directly or reverse the immunosuppressive microenvironment. Currently, bacterial antigens synthesized as vaccine candidates by bioengineering technology are novel antitumor immunotherapy. Especially the combination therapy of bacterial vaccine with conventional therapies may further achieve enhanced therapeutic benefits against cancers. However, the clinical translation of bacteria-based immunotherapy is limited for biosafety concerns and non-uniform production standards. In this review, we aim to summarize immunotherapy strategies based on advanced bacterial therapeutics and discuss their potential for cancer management, we will also propose approaches for optimizing bacteria-based immunotherapy for facilitating clinical translation.

Proteome Analysis of the Antiproliferative Activity of the Novel Chitooligosaccharide-Gallic Acid Conjugate against the SW620 Colon Cancer Cell Line

Chitooligosaccharide (COS) and gallic acid (GA) are natural compounds with anti-cancer properties, and their conjugate (COS-GA) has several biological activities. Herein, the anti-cancer activity of COS-GA in SW620 colon cancer cells was investigated. MTT assay was used to evaluate cell viability after treatment with 62.5, 122, and 250 µg/mL of COS, GA, and COS-GA for 24 and 48 h. The number of apoptotic cells was determined using flow cytometry. Proteomic analysis was used to explore the mechanisms of action of different compounds. COS-GA and GA showed a stronger anti-cancer effect than COS by reducing SW620 cell proliferation at 125 and 250 µg/mL within 24 h. Flow cytometry revealed 20% apoptosis after COS-GA treatment for 24 h. Thus, GA majorly contributed to the enhanced anti-cancer activity of COS via conjugation. Proteomic analysis revealed alterations in protein translation and DNA duplication in the COS group and the structural constituents of the cytoskeleton, intermediate filament organization, the mitochondrial nucleoid, and glycolytic processes in the COS-GA group. Anti-cancer-activity-related proteins were altered, including CLTA, HSPA9, HIST2H2BF, KRT18, HINT1, DSP, and VIM. Overall, the COS-GA conjugate can serve as a potential anti-cancer agent for the safe and effective treatment of colon cancer.

Biomimetic and bioinspired nano-platforms for cancer vaccine development

The advent of immunotherapy has revolutionized the treating modalities of cancer. Cancer vaccine, aiming to harness the host immune system to induce a tumor-specific killing effect, holds great promises for its broad patient coverage, high safety, and combination potentials. Despite promising, the clinical translation of cancer vaccines faces obstacles including the lack of potency, limited options of tumor antigens and adjuvants, and immunosuppressive tumor microenvironment. Biomimetic and bioinspired nanotechnology provides new impetus for the designing concepts of cancer vaccines. Through mimicking the stealth coating, pathogen recognition pattern, tissue tropism of pathogen, and other irreplaceable properties from nature, biomimetic and bioinspired cancer vaccines could gain functions such as longstanding, targeting, self-adjuvanting, and on-demand cargo release. The specific behavior and endogenous molecules of each type of living entity (cell or microorganism) offer unique features to cancer vaccines to address specific needs for immunotherapy. In this review, the strategies inspired by eukaryotic cells, bacteria, and viruses will be overviewed for advancing cancer vaccine development. Our insights into the future cancer vaccine development will be shared at the end for expediting the clinical translation.

Degradable Bottlebrush Polypeptides and the Impact of their Architecture on Cell Uptake, Pharmacokinetics, and Biodistribution In Vivo

Bottlebrush polymers are highly promising as unimolecular nanomedicines due to their unique control over the critical parameters of size, shape and chemical function. However, since they are prepared from biopersistent carbon backbones, most known bottlebrush polymers are non-degradable and thus unsuitable for systemic therapeutic administration. Herein, we report the design and synthesis of novel poly(organo)phosphazene-g-poly(α-glutamate) (PPz-g-PGA) bottlebrush polymers with exceptional control over their structure and molecular dimensions (Dh ≈ 15-50 nm). These single macromolecules show outstanding aqueous solubility, ultra-high multivalency and biodegradability, making them ideal as nanomedicines. While well-established in polymer therapeutics, it has hitherto not been possible to prepare defined single macromolecules of PGA in these nanosized dimensions. A direct correlation was observed between the macromolecular dimensions of the bottlebrush polymers and their intracellular uptake in CT26 colon cancer cells. Furthermore, the bottlebrush macromolecular structure visibly enhanced the pharmacokinetics by reducing renal clearance and extending plasma half-lives. Real-time analysis of the biodistribution dynamics showed architecture-driven organ distribution and enhanced tumor accumulation. This work, therefore, introduces a robust, controlled synthesis route to bottlebrush polypeptides, overcoming limitations of current polymer-based nanomedicines and, in doing so, offers valuable insights into the influence of architecture on the in vivo performance of nanomedicines.

Chemically engineering cells for precision medicine

Cell-based therapy holds great potential to address unmet medical needs and revolutionize the healthcare industry, as demonstrated by several therapeutics such as CAR-T cell therapy and stem cell transplantation that have achieved great success clinically. Nevertheless, natural cells are often restricted by their unsatisfactory in vivo trafficking and lack of therapeutic payloads. Chemical engineering offers a cost-effective, easy-to-implement engineering tool that allows for strengthening the inherent favorable features of cells and confers them new functionalities. Moreover, in accordance with the trend of precision medicine, leveraging chemical engineering tools to tailor cells to accommodate patients individual needs has become important for the development of cell-based treatment modalities. This review presents a comprehensive summary of the currently available chemically engineered tools, introduces their application in advanced diagnosis and precision therapy, and discusses the current challenges and future opportunities.

Advances in Escherichia coli Nissle 1917 as a customizable drug delivery system for disease treatment and diagnosis strategies

With the in-depth and comprehensive study of bacteria and their related ecosystems in the human body, bacterial-based drug delivery system has become an emerging biomimetic platform that can retain the innate biological functions. Benefiting from its good biocompatibility and ideal targeting ability as a biological carrier, Escherichia coli Nissle 1917 (ECN) has been focused on the treatment strategies of inflammatory bowel disease and tumor. The advantage of a bacterial carrier is that it can express exogenous protein while also acting as a natural capsule by releasing drug slowly as a result of its own colonization impact. In order to survive in harsh environments such as the digestive tract and tumor microenvironment, ECN can be modified or genetically engineered to enhance its function and host adaptability. The adoption of ECN carries or expresses drugs which are essential for accurate diagnosis and treatment. This review briefly describes the properties of ECN, the relationship between ECN and inflammation and tumor, and the strategy of using surface modification and genetic engineering to modify ECN as a delivery carrier for disease treatment.

Chemotherapeutic and targeted drugs-induced immunogenic cell death in cancer models and antitumor therapy: An update review

As traditional strategies for cancer treatment, some chemotherapy agents, such as doxorubicin, oxaliplatin, cyclophosphamide, bortezomib, and paclitaxel exert their anti-tumor effects by inducing immunogenic cell death (ICD) of tumor cells. ICD induces anti-tumor immunity through release of, or exposure to, damage-related molecular patterns (DAMPs), including high mobility group box 1 (HMGB1), calreticulin, adenosine triphosphate, and heat shock proteins. This leads to activation of tumor-specific immune responses, which can act in combination with the direct killing functions of chemotherapy drugs on cancer cells to further improve their curative effects. In this review, we highlight the molecular mechanisms underlying ICD, including those of several chemotherapeutic drugs in inducing DAMPs exposed during ICD to activate the immune system, as well as discussing the prospects for application and potential role of ICD in cancer immunotherapy, with the aim of providing valuable inspiration for future development of chemoimmunotherapy.

Anticancer activity of Pseudomonas aeruginosa derived peptide with iRGD in colon cancer therapy

Objectives

Colon cancer is well-known as a life-threatening disease. Since the current treatment modalities for this type of cancer are powerful yet face some limitations, finding novel treatments is required to achieve better outcomes with fewer side effects. Here we investigated the therapeutic potential of Azurin-p28 alone or along with iRGD (Ac-CRGDKGPDC-amide) as a tumor-penetrating peptide and 5-fluorouracil (5-FU) for colon cancer.

Materials and Methods

Inhibitory effect of p28 with or without iRGD/5-FU was studied in CT26 and HT29, as well as the xenograft animal model of cancer. The effect of p28 alone or along with iRGD/5-FU on cell migration, apoptotic activity, and cell cycle of the cell lines was assessed. Level of the BAX and BCL2 genes, tumor suppressor genes [(p53 and collagen type-Iα1 (COL1A1), collagen type-Iα2 (COL1A2)] were assessed by quantitative RT-PCR.

Results

These findings show that using p28 with or without iRGD and 5-FU raised the level of p53 and BAX but decreased BCL2, compared with control and 5-FU groups in tissues of the tumor, which result in raising the apoptosis.

Conclusion

It seems that p28 may be used as a new therapeutic approach in colon cancer therapy that can enhance the anti-tumor effect of 5-FU.

Bacterial Peptides and Bacteriocins as a Promising Therapy for Solid Tumor

The conventional treatment is faced with limitations in treating solid tumors due to their specific pathophysiology. Several novel therapeutics have been introduced in recent decades to treat solid tumors. Among these new methods, tumor therapy using bacterial products like bacteriocins and peptides has been of great interest due to their unique characteristics and advantages of them in comparison to the conventional treatment, including that they can precisely target tumor cells, selective toxicity for tumor cells, low side effect on normal cells, toxicity activity for MDR cancer cells, used as the target delivery vehicles and enhancing drug delivery. Moreover, their small size and low molecular weight have made them easy to synthesize and modify. Furthermore, in recent years, genetic engineering has expanded the therapeutic ability of peptides to treat solid tumors, which results in overcoming the peptide drawbacks. The present review mainly focuses on the new advances in applying bacterial peptides and bacteriocins in treating human solid tumors.

Bacteria-based nanodrug for anticancer therapy

Bacteria-based immunotherapy has become a promising strategy to induce innate and adaptive responses for fighting cancer. The advantages of bacteriolytic tumor therapy mainly lie in stimulation of innate immunity and colonization of some bacteria targeting the tumor microenvironment (TME). These bacteria have cytotoxic proteins and immune modulating factors that can effectively restrain tumor growth. However, cancer is a multifactorial disease and single therapy is typically unable to eradicate tumors. Rapid progress has been made in combining bacteria with nanotechnology. Using the nanomolecular properties of bacterial products for tumor treatment preserves many features from the original bacteria while providing some unique advantages. Nano-bacterial therapy can enhance permeability and retention of drugs, increase the tolerability of the targeted drugs, promote the release of immune cell mediators, and induce immunogenic cell death pathways. In addition, combining nano-bacterial mediated antitumor therapeutic systems with modern therapy is an effective strategy for overcoming existing barriers in antitumor treatment and can achieve satisfactory therapeutic efficacy. Overall, exploring the immune antitumor characteristics of adjuvant clinical treatment with bacteria can provide potential efficacious treatment strategies for combatting cancer.

Recent Update on Bacteria as a Delivery Carrier in Cancer Therapy: From Evil to Allies

Cancer is associated with a comprehensive burden that significantly affects patient’s quality of life. Even though patients’ disease condition is improving following conventional therapies, researchers are studying alternative tools that can penetrate solid tumours to deliver the therapeutics due to issues of developing resistance by the cancer cells. Treating cancer is not the only the goal in cancer therapy; it also includes protecting non-cancerous cells from the toxic effects of anti-cancer agents. Thus, various advanced techniques, such as cell-based drug delivery, bacteria-mediated therapy, and nanoparticles, are devised for site-specific delivery of drugs. One of the novel methods that can be targeted to deliver anti-cancer agents is by utilising genetically modified non-pathogenic bacterial species. This is due to the ability of bacterial species to multiply selectively or non-selectively on tumour cells, resulting in biofilms that leads to disruption of metastasis process. In preclinical studies, this technology has shown significant results in terms of efficacy, and some are currently under investigation. Therefore, researchers have conducted studies on bacteria transporting the anti-cancer drug to targeted tumours. Alternatively, bacterial ghosts and bacterial spores are utilised to deliver anti-cancer drugs. Although in vivo studies of bacteria-mediated cancer therapy have shown successful outcome, further research on bacteria, specifically their targeting mechanism, is required to establish a complete clinical approach in cancer treatment. This review has focused on the up-to-date understanding of bacteria as a therapeutic carrier in the treatment of cancer as an emerging field.

Gut microbiota-drug interactions in cancer pharmacotherapies: implications for efficacy and adverse effects

INTRODUCTION

The gut microbiota is involved in host physiology and health. Reciprocal microbiota-drug interactions are increasingly recognized as underlying some individual differences in therapy response and adverse events. Cancer pharmacotherapies are characterized by a high degree of interpatient variability in efficacy and side effect profile and recently, the microbiota has emerged as a factor that may underlie these differences.

AREAS COVERED

The effects of cancer pharmacotherapy on microbiota composition and function are reviewed with consideration of the relationship between baseline microbiota composition, microbiota modification, antibiotics exposure and cancer therapy efficacy. We assess the evidence implicating the microbiota in cancer therapy-related adverse events including impaired gut function, cognition and pain perception. Finally, potential mechanisms underlying microbiota-cancer drug interactions are described, including direct microbial metabolism, and microbial modulation of liver metabolism and immune function. This review focused on preclinical and clinical studies conducted in the last 5 years.

EXPERT OPINION

Preclinical and clinical research supports a role for baseline microbiota in cancer therapy efficacy, with emerging evidence that the microbiota modification may assist in side effect management. Future efforts should focus on exploiting this knowledge towards the development of microbiota-targeted therapies. Finally, a focus on specific drug-microbiota-cancer interactions is warranted.

Bacterially Synthesized Tellurium Nanorods for Elimination of Advanced Malignant Tumor by Photothermal Immunotherapy

Probiotic Escherichia coli Nissle 1917 (EcN) are employed as a bioreactor for intracellularly synthesizing tellurium nanorods (TeNRs) providing a biohybrid therapeutic platform (Te@EcN) for the elimination of advanced malignant tumor by photothermal immunotherapy. Te@EcN is found to possess superior photothermal property upon near-infrared irradiation, and can efficiently accumulate and retain in tumors, although EcN loses proliferation ability after the synthesis of TeNRs, thus inducing considerable immunogenic tumor cell death. Under co-stimulation by EcN acting as immunoadjuvants, maturation of dendritic cells and priming of cytotoxic T cells are largely promoted. In addition, Te@EcN can reprogram tumor-associated macrophages to ameliorate the immunosuppressive tumor microenvironment. Thus, tumor metastasis and recurrence can be efficiently suppressed. Most importantly, owing to the non-pathogenicity of probiotic EcN and their non-proliferative characteristics after TeNRs synthesis, Te@EcN is found to be rapidly metabolized and cleared from the normal tissues, showing very slight acute side effects in healthy mice even at a relatively high administration dose. Therefore, the proposed combined therapeutic strategy based on bacteria-synthesized TeNRs may find great potential in improving bacteria-mediated tumor therapy with increased antitumor efficacy and reduced toxicity.

CD47-targeted cancer immunogene therapy: Secreted SIRPα-Fc fusion protein eradicates tumors by macrophage and NK cell activation

CD47 protects healthy cells from macrophage attack by binding to signal regulatory protein α (SIRPα), while its upregulation in cancer prevents immune clearance. Systemic treatment with CD47 antibodies requires a weakened Fc-mediated effector function or lower CD47-binding affinity to prevent side effects. Our approach combines “the best of both worlds,” i.e., maximized CD47 binding and full Fc-mediated immune activity, by exploiting gene therapy for paracrine release. We developed a plasmid vector encoding for the secreted fusion protein sCV1-hIgG1, comprising highly efficient CD47-blocking moiety CV1 and Fc domain of human immunoglobulin G1 (IgG1) with maximized immune activation. sCV1-hIgG1 exhibited a potent bystander effect, blocking CD47 on all cells via fusion protein secreted from only a fraction of cells or when transferring transfection supernatant to untransfected cells. The CpG-free plasmid ensured sustained secretion of sCV1-hIgG1. In orthotopic human triple-negative breast cancer in CB17-severe combined immunodeficiency (SCID) mice, ex vivo transfection significantly delayed tumor growth and eradicated one-third of tumors. In intratumoral transfection experiments, CD47 blockage and increased migration of macrophages into the tumor were observed within 17 h of a single injection. Natural killer (NK) cell-mediated lysis of sCV1-hIgG1-expressing cells was demonstrated in vitro. Taken together, this approach also opens the opportunity to block, in principle, any immune checkpoints.

Bacteria from Infectious Particles to Cell Based Anticancer Targeted Drug Delivery Systems

Bacterial ghosts (BGs) are empty cell envelopes of nonliving evacuated bacterial cells. They are free from their cytoplasmic contents; however, they sustain their cellular 3D morphology and antigenic structures, counting on bioadhesive properties. Lately, they have been tested as an advanced drug delivery system (DDS) for different materials like DNA, peptides, or drugs, either single components or combinations. Different studies have revealed that, BG DDS were paid the greatest attention in recent years. The current review explores the impact of BGs on the field of drug delivery and drug targeting. BGs have a varied area of applications, including vaccine and tumor therapy. Moreover, the use of BGs, their synthesis, their uniqueness as a delivery system and application principles in cancer are discussed. Furthermore, the safety issues of BGs and stability aspects of using ghost bacteria as delivery systems are discussed. Future perspective efforts that must be followed for this important system to continue to grow are important and promising.

Bacterial Ghosts-Based Vaccine and Drug Delivery Systems

Bacterial ghosts (BGs) are empty bacterial envelopes of Gram-negative bacteria produced by controlled expressions of cloned gene E, forming a lysis tunnel structure within the envelope of the living bacteria. Globally, BGs have been used as vaccine delivery systems and vaccine adjuvants. There is an increasing interest in the development of novel delivery systems that are based on BGs for biomedical applications. Due to intact reservation of bacterial cell membranes, BGs have an inherent immunogenicity, which enables targeted drug delivery and controlled release. As carrier vehicles, BGs protect drugs from interference by external factors. In recent years, there has been an increasing interest in BG-based delivery systems against tumors, inflammation, and infection, among others. Herein, we reviewed the preparation methods for BGs, interactions between BGs and the host, and further highlighted research progress in BG development.

The role of the tumor microbe microenvironment in the tumor immune microenvironment: bystander, activator, or inhibitor?

The efficacy of cancer immunotherapy largely depends on the tumor microenvironment, especially the tumor immune microenvironment. Emerging studies have claimed that microbes reside within tumor cells and immune cells, suggesting that these microbes can impact the state of the tumor immune microenvironment. For the first time, this review delineates the landscape of intra-tumoral microbes and their products, herein defined as the tumor microbe microenvironment. The role of the tumor microbe microenvironment in the tumor immune microenvironment is multifaceted: either as an immune activator, inhibitor, or bystander. The underlying mechanisms include: (I) the presentation of microbial antigens by cancer cells and immune cells, (II) microbial antigens mimicry shared with tumor antigens, (III) microbe-induced immunogenic cell death, (IV) microbial adjuvanticity mediated by pattern recognition receptors, (V) microbe-derived metabolites, and (VI) microbial stimulation of inhibitory checkpoints. The review further suggests the use of potential modulation strategies of the tumor microbe microenvironment to enhance the efficacy and reduce the adverse effects of checkpoint inhibitors. Lastly, the review highlights some critical questions awaiting to be answered in this field and provides possible solutions. Overall, the tumor microbe microenvironment modulates the tumor immune microenvironment, making it a potential target for improving immunotherapy. It is a novel field facing major challenges and deserves further exploration.

E. coli Membrane Vesicles as a Catalase Carrier for Long-Term Tumor Hypoxia Relief to Enhance Radiotherapy

Hypoxia is one of the most important factors that limit the effect of radiotherapy, and the abundant H₂O₂ in tumor tissues will also aggravate hypoxia-induced radiotherapy resistance. Delivering catalase to decompose H₂O₂ into oxygen is an effective strategy to relieve tumor hypoxia and radiotherapy resistance. However, low stability limits catalase's in vivo application, which is one of the most common limitations for almost all proteins' internal utilization. Here, we develop catalase containing E. coli membrane vesicles (EMs) with excellent protease resistance to relieve tumor hypoxia for a long time. Even treated with 100-fold of protease, EMs showed higher catalase activity than free catalase. After being injected into tumors post 12 h, EMs maintained their hypoxia relief ability while free catalase lost its activity. Our results indicate that EMs might be an excellent catalase delivery for tumor hypoxia relief. Combined with their immune stimulation features, EMs could enhance radiotherapy and induce antitumor immune memory effectively.

Bacteria and Archaea: A new era of cancer therapy

Cancer is one of the most important mortality in the world. The major drawbacks of chemotherapy are the poor absorption of drugs into tumor tissues and development of resistance against anti-cancer agents. To overcome these limitations, the use of microorganisms has been extensively considered in the treatment of cancer. Microorganisms (bacteria/Archaea) secrete different bioactive compounds that can efficiently inhibit cancer cells growth. Biological nanocarriers derived from microorganisms including outer membrane vesicles (OMVs), bacterial ghosts (BGs) and archaeosomes have also been considered as drug delivery systems. Conjugation of drug loaded nanocarriers to bacteria strongly kills the cancer cells after internalization through the bacteria. Merging of microbiology and nanotechnology may provide versatile microbial nano-hybrids for promising treatment of cancer. This strategy causes more amount of drug to enter into cancer cells. In this review, we present evidence that microorganism, their derivatives as well as their intervention with nanotechnology can be a powerful vehicle for eradication cancer.

Gut Microbiota: Influence on Carcinogenesis and Modulation Strategies by Drug Delivery Systems to Improve Cancer Therapy

Gut microbiota have close interactions with the host. It can affect cancer progression and the outcomes of cancer therapy, including chemotherapy, immunotherapy, and radiotherapy. Therefore, approaches toward the modulation of gut microbiota will enhance cancer prevention and treatment. Modern drug delivery systems (DDS) are emerging as rational and promising tools for microbiota intervention. These delivery systems have compensated for the obstacles associated with traditional treatments. In this review, the essential roles of gut microbiota in carcinogenesis, cancer progression, and various cancer therapies are first introduced. Next, advances in DDS that are aimed at enhancing the efficacy of cancer therapy by modulating or engineering gut microbiota are highlighted. Finally, the challenges and opportunities associated with the application of DDS targeting gut microbiota for cancer prevention and treatment are briefly discussed.

Biomimetic bacterial and viral-based nanovesicles for drug delivery, theranostics, and vaccine applications

Smart nanocarriers obtained from bacteria and viruses offer excellent biomimetic properties which has led to significant research into the creation of advanced biomimetic materials. Their versatile biomimicry has application as biosensors, biomedical scaffolds, immobilization, diagnostics, and targeted or personalized treatments. The inherent natural traits of biomimetic and bioinspired bacteria- and virus-derived nanovesicles show potential for their use in clinical vaccines and novel therapeutic drug delivery systems. The past few decades have seen significant progress in the bioengineering of bacteria and viruses to manipulate and enhance their therapeutic benefits. From a pharmaceutical perspective, biomimetics enable the safe integration of naturally occurring bacteria and virus particles to achieve high, stable rates of cellular transfection/infection and prolonged circulation times. In addition, biomimetic technologies can overcome safety concerns associated with live-attenuated and inactivated whole bacteria or viruses. In this review, we provide an update on the utilization of bacterial and viral particles as drug delivery systems, theranostic carriers, and vaccine/immunomodulation modalities.

Resolving the Paradox of Colon Cancer Through the Integration of Genetics, Immunology, and the Microbiota

While colorectal cancers (CRC) are paradigmatic tumors invaded by effector memory lymphocytes, the mechanisms accounting for the relative resistance of MSI negative CRC to immunogenic cell death mediated by oxaliplatin and immune checkpoint inhibitors has remained an open conundrum. Here, we propose the viewpoint where its microenvironmental contexture could be explained -at least in part- by macroenvironmental cues constituted by the complex interplay between the epithelial barrier, its microbial ecosystem, and the local immune system. Taken together this dynamic ménage-à-trois offers novel coordinated actors of the humoral and cellular immune responses actionable to restore sensitivity to immune checkpoint inhibition. Solving this paradox involves breaking tolerance to crypt stem cells by inducing the immunogenic apoptosis of ileal cells in the context of an ileal microbiome shifted towards immunogenic bacteria using cytotoxicants. This manoeuver results in the elicitation of a productive Tfh and B cell dialogue in mesenteric lymph nodes culminating in tumor-specific memory CD8+ T cell responses sparing the normal epithelium.

Can we harness the microbiota to enhance the efficacy of cancer immunotherapy?

There is currently much interest in defining how the microbiota shapes immune responses in the context of cancer. Various studies in both mice and humans have associated particular commensal species with better (or worse) outcomes in different cancer types and following treatment with cancer immunotherapies. However, the mechanisms involved remain ill-defined and even controversial. In this Viewpoint, Nature Reviews Immunology has invited six eminent scientists in the field to share their thoughts on the key questions and challenges for the field.

The bacterial instrument as a promising therapy for colon cancer

OBJECTIVE

Colon cancer is a great health concern worldwide, as it is the second leading cause of cancer-related death. Conventional treatment of cancer such as surgery, radiotherapy, and chemotherapy are faced with limitations and side effects. Therefore, strategies for the treatment of cancer need to be modified or new strategies replacing the old one.

AIMS

The aim of this study is to review the role of bacteria or their products (such as peptides, bacteriocins, and toxins) as a therapeutic agent for colon cancer.

RESULTS AND CONCLUSION

Recently, the therapeutic role of bacteria and their products in colon cancer treatment holds promise as emerging novel anti-cancer agents. Unlike the conventional treatments, targeted therapy based on the use of bacteria that are able to directly target tumor cells without affecting normal cells is evolving as an alternative strategy. Moreover, several bacterial species were used in live, attenuated or genetically modified that are able to multiply selectively in tumors and inhibiting their growth.

Bioengineered smart bacterial carriers for combinational targeted therapy of solid tumours

Despite many endeavours for the development of new anticancer drugs, effective therapy of solid tumours remains a challenging issue. The current cancer chemotherapies may associate with two important limitations, including the lack/trivial specificity of treatment modalities towards diseased cells/tissues resulting in undesired side effects, and the emergence of drug-resistance mechanisms by tumour cells causing the failure of the treatment. Much attention, therefore, has currently been paid to develop smart and highly specific anticancer agents with maximal therapeutic impacts and minimal side effects. Among various strategies used to target cancer cells, bacteria-based cancer therapies (BCTs) have been validated as potential gene/drug delivery carriers, which can also be engineered to be used in diagnosis processes. They can be devised to selectively target the tumour microenvironment (TME), within which they may preferentially proliferate in the necrotic and anaerobic parts - often inaccessible to other therapeutics. BCTs are capable to sense and respond to the environmental signals, upon which they are considered as smart microrobots applicable in the controlled delivery of therapeutic agents to the TME. In this review, we aimed to provide comprehensive insights into the potentials of the bioengineered bacteria as smart and targeted bio-carriers and discuss their applications in cancer therapy.

Trial watch: chemotherapy-induced immunogenic cell death in immuno-oncology

The term ‘immunogenic cell death’ (ICD) denotes an immunologically unique type of regulated cell death that enables, rather than suppresses, T cell-driven immune responses that are specific for antigens derived from the dying cells. The ability of ICD to elicit adaptive immunity heavily relies on the immunogenicity of dying cells, implying that such cells must encode and present antigens not covered by central tolerance (antigenicity), and deliver immunostimulatory molecules such as damage-associated molecular patterns and cytokines (adjuvanticity). Moreover, the host immune system must be equipped to detect the antigenicity and adjuvanticity of dying cells. As cancer (but not normal) cells express several antigens not covered by central tolerance, they can be driven into ICD by some therapeutic agents, including (but not limited to) chemotherapeutics of the anthracycline family, oxaliplatin and bortezomib, as well as radiation therapy. In this Trial Watch, we describe current trends in the preclinical and clinical development of ICD-eliciting chemotherapy as partner for immunotherapy, with a focus on trials assessing efficacy in the context of immunomonitoring.

Relationship between intestinal microorganisms and T lymphocytes in colorectal cancer

Colorectal cancer (CRC) is a common type of malignant cancer worldwide. Recent studies have identified the gut microbiota as the origin of CRC, and T lymphocyte-mediated immune functions have been shown to play an important role in this disease. By summarizing previous literature, we found that Fusobacterium nucleatum may protect CRC from immune cell attack by inhibiting T cells and influencing the production of many chemokines and cytokines. Some bacterial metabolites and probiotics have been shown to participate in the regulation of CRC through T cell-mediated molecular pathways. To visualize the relevant data, an association network of intestinal microorganisms and T lymphocytes associated with CRC was constructed. This work may provide direction for - and insight into - further research on the relationship between intestinal microorganisms and T lymphocytes in CRC.