Sequentially Triggered Bacterial Outer Membrane Vesicles for Macrophage Metabolism Modulation and Tumor Metastasis Suppression

Bacterial ghosts: A breakthrough approach to cancer vaccination

Cancer is a devastating disease worldwide with high mortality rates and is a foremost concern for society. Immunotherapy has emerged as a promising strategy for treating cancer, harnessing the power of immune system to recognize and kill tumor cells. Bacterial ghosts (BGs), a novel platform in cancer vaccination, are suitable for personalized and effective immunotherapeutic interventions. BG are empty bacterial cell envelopes generated through a controlled lysis process, leaving behind empty but structurally intact cell membranes. BGs have been used as vaccine adjuvants and vaccine delivery vehicles worldwide. They possess inherent immunogenicity, enabling them to be used for controlled release and targeted drug delivery. Recently, the potential of BGs has been explored for tumor inhibition, making them suitable carrier vehicles. This review highlights cancer immunotherapy, methods of BG preparation, characterization of BGs, the interaction of BGs with the immune system, and research progress on BG-based cancer vaccines with future insights.

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

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

Bioorthogonal Engineering of Bacterial Outer Membrane Vesicles for NIR-II Fluorescence Imaging-Guided Synergistic Enhanced Immunotherapy

The efficacy of immunotherapy in treating triple-negative breast cancer (TNBC) has been restricted due to its low immunogenicity and suppressive immune microenvironment. Bacterial outer membrane vesicles (OMVs) have emerged as innovative immunotherapeutic agents in antitumor therapy by stimulating the innate immune system, but intricate modifications and undesirable multiple dose administration severely hinder their utility. Herein, a two-step bacterial metabolic labeling technique was utilized for the bioorthogonal engineering of OMVs. At first, d-propargylglycine (DPG, an alkyne-containing d-amino acid) was introduced into the incubation process of probiotic Escherichia coli 1917 (Ecn) to produce DPG-functionalized OMVs, which were subsequently conjugated with azide-functionalized new indocyanine green (IR820) to yield OMV-DPG-IR820. The combination of phototherapy and immunostimulation of OMV-DPG-IR820 effectively arouses adaptive immune responses, causing maturation of dendritic cells, infiltration of T cells, repolarization of the M2 macrophage to the M1 macrophage, and upregulation of inflammatory factors. Remarkably, OMV-DPG-IR820 demonstrated tumor-targeting capabilities with guidance provided by near-infrared II (NIR-II) fluorescence imaging, leading to remarkable inhibition on both primary and distant tumors and preventing metastasis without causing noticeable adverse reactions. This study elucidates a sophisticated bioorthogonal engineering strategy for the design and production of functionalized OMVs and provides novel perspectives on the microbiome-mediated reversal of TNBC through a precise and efficient immunotherapy.

Research progress of paclitaxel nanodrug delivery system in the treatment of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, characterized by the loss or low expression of estrogen receptor (ER), human epidermal growth factor receptor 2 (HER2) and progesterone receptor (PR). Due to the lack of clear therapeutic targets, paclitaxel (PTX) is often used as a first-line standard chemotherapy drug for the treatment of high-risk and locally advanced TNBC. PTX is a diterpenoid alkaloid extracted and purified from Taxus plants, functioning as an anticancer agent by inducing and promoting tubulin polymerization, inhibiting spindle formation in cancer cells, and preventing mitosis. However, its clinical application is limited by low solubility and high toxicity. Nanodrug delivery system (NDDS) is one of the feasible methods to improve the water solubility of PTX and reduce side effects. In this review, we summarize the latest advancements in PTX-targeted NDDS, as well as its combination with other codelivery therapies for TNBC treatment. NDDS includes passive targeting, active targeting, stimuli-responsive, codelivery, and multimode strategies. These systems have good prospects in improving the bioavailability of PTX, enhancing tumor targeting, reducing toxicity, controlling drug release, and reverse tumor multidrug resistance (MDR). This review provides valuable insights into the clinical development and application of PTX-targeted NDDS in the treatment of TNBC.

Engineered Macrophage Exosomes Deliver Drug-Targeted Therapy for Breast Cancer

Breast cancer is a highly widespread form of malignant tumor characterized by a high rate of recurrence and mortality; it primarily occurs when tumor cells spread to peripheral regions of the body. Macrophages have a significant impact on the proliferation and metastasis of breast cancer. The exosomes generated by these cells exhibit an extensive spectrum of capabilities in suppressing the spread of cancer cells. These feature very specific targeting properties for breast cancer cells and inhibit the proliferation of cancer cells by altering the immune milieu within the tumor. This study investigates methods for developing macrophage-derived exosomes, such as using protein-coupled exosome membranes to protect delivery contents, creating multifunctional biomimetic particles, and utilizing ultrasonic fusion to protect delivery contents. Furthermore, this paper addresses recent advances in producing macrophage exosomes from organic and inorganic materials. In general, targeted treatment for breast cancer could benefit greatly from creating drug delivery systems mediated by macrophage exosomes.

The Acid-Stimulated Self-Assembled DNA Nanonetwork for Sensitive Detection and Living Cancer Cell Imaging of MicroRNA-221

Herein, a novel functional DNA structure, acid-stimulated self-assembly DNA nanonetwork (ASDN), was proposed for miRNA-221 sensitive detection and high-resolution living cancer cell imaging. Significantly, the self-assembly of ASDN only occurred in the acidic extracellular environment of cancer cells, which could be endocytosed by cancer cells to eliminate the interference of noncancer cells and deliver the ASDN into cancer cells. Subsequently, endogenous miRNA-221 could trigger the catalytic hairpin assembly within ASDN, resulting in the separation of the fluorophore Cy5 and the quencher BHQ2 to recover the substantial Cy5 fluorescence signals, thus achieving signal amplification for sensitive detection of miRNA-221 with a detection limit of 5.5 pM, as well as facilitating high-resolution and low-background imaging of miRNA-221 in cancer cells. In consequence, this strategy provides an innovative DNA nanonetwork to distinguish cancer cells from other cells for sensitive detection of biomarkers, offering a meaningful reference for the application of DNA nanostructure self-assembly technology in relevant fundamental research and disease diagnosis.

Double-camouflaged tellurium nanoparticles for enhanced photothermal immunotherapy of tumor

The photothermal conversion properties of tellurium (Te) nanoparticles have been extensively investigated, rendering them a promising candidate for tumor photothermal therapy. However, there is still room for improvement in the development of efficient Te-based drug delivery systems. Here, Te nanoparticles are mineralized with bioactive molecules within attenuated Salmonella (S-Te), which are subsequently taken up by macrophages (RAW264.7) to construct a double-camouflaged delivery platform (RS-Te). Remarkably, RS-Te retains superior photothermal properties under near-infrared irradiation. The mineralization process eliminates bacterial proliferation potential, thereby mitigating the risk of excessive bacterial growth in vivo. Furthermore, the uptake of bacteria by macrophages not only polarizes them into M1 macrophages to induce an anti-tumor immune response but also circumvents any adverse effects caused by complex antigens on the bacterial surface. The results show that RS-Te can effectively accumulate and retain in tumors. RS-Te-mediated photothermal immunotherapy largely promotes the maturation of dendritic cells and priming of cytotoxic T cells induced by near-infrared laser irradiation. Moreover, RS-Te can switch the activation of macrophages from an immunosuppressive M2 phenotype to a more inflammatory M1 state. The double-camouflaged delivery system may offer highly efficient and safe cancer treatment.

Reprogramming the immunosuppressive tumor microenvironment through nanomedicine: an immunometabolism perspective

Increasing evidence indicates that immunotherapy is hindered by a hostile tumor microenvironment (TME) featured with deprivation of critical nutrients and pooling of immunosuppressive metabolites. Tumor cells and immunosuppressive cells outcompete immune effector cells for essential nutrients. Meanwhile, a wide range of tumor cell-derived toxic metabolites exerts negative impacts on anti-tumor immune response, diminishing the efficacy of immunotherapy. Nanomedicine with excellent targetability offers a novel approach to improving cancer immunotherapy via metabolically reprogramming the immunosuppressive TME. Herein, we review recent strategies of enhancing immunotherapeutic effects through rewiring tumor metabolism via nanomedicine. Attention is drawn on immunometabolic tactics for immune cells and stromal cells in the TME via nanomedicine. Additionally, we discuss future directions of developing metabolism-regulating nanomedicine for precise and efficacious cancer immunotherapy.

Engineering Versatile Bacteria-Derived Outer Membrane Vesicles: An Adaptable Platform for Advancing Cancer Immunotherapy

In recent years, cancer immunotherapy has undergone a transformative shift toward personalized and targeted therapeutic strategies. Bacteria-derived outer membrane vesicles (OMVs) have emerged as a promising and adaptable platform for cancer immunotherapy due to their unique properties, including natural immunogenicity and the ability to be engineered for specific therapeutic purposes. In this review, a comprehensive overview is provided of state-of-the-art techniques and methodologies employed in the engineering of versatile OMVs for cancer immunotherapy. Beginning by exploring the biogenesis and composition of OMVs, unveiling their intrinsic immunogenic properties for therapeutic appeal. Subsequently, innovative approaches employed to engineer OMVs are delved into, ranging from the genetic engineering of parent bacteria to the incorporation of functional molecules. The importance of rational design strategies is highlighted to enhance the immunogenicity and specificity of OMVs, allowing tailoring for diverse cancer types. Furthermore, insights into clinical studies and potential challenges utilizing OMVs as cancer vaccines or adjuvants are also provided, offering a comprehensive assessment of the current landscape and future prospects. Overall, this review provides valuable insights for researchers involved in the rapidly evolving field of cancer immunotherapy, offering a roadmap for harnessing the full potential of OMVs as a versatile and adaptable platform for cancer treatment.

Decoding the secret of extracellular vesicles in the immune tumor microenvironment of the glioblastoma: on the border of kingdoms

Over the last decades, extracellular vesicles (EVs) have become increasingly popular for their roles in various pathologies, including cancer and neurological and immunological disorders. EVs have been considered for a long time as a means for normal cells to get rid of molecules it no longer needs. It is now well established that EVs play their biological roles also following uptake or by the interaction of EV surface proteins with cellular receptors and membranes. In this review, we summarize the current status of EV production and secretion in glioblastoma, the most aggressive type of glioma associated with high mortality. The main purpose is to shed light on the EVs as a universal mediator of interkingdom and intrakingdom communication in the context of tumor microenvironment heterogeneity. We focus on the immunomodulatory EV functions in glioblastoma-immune cross-talk to enhance immune escape and reprogram tumor-infiltrating immune cells. We critically examine the evidence that GBM-, immune cell-, and microbiome-derived EVs impact local tumor microenvironment and host immune responses, and can enter the circulatory system to disseminate and drive premetastatic niche formation in distant organs. Taking into account the current state of the art in intratumoral microbiome studies, we discuss the emerging role of bacterial EV in glioblastoma and its response to current and future therapies including immunotherapies.

Bacterial outer membrane vesicles in the fight against cancer

ABSTRACT

Bacterial outer membrane vesicles (OMVs) are diminutive vesicles naturally released by Gram-negative bacteria. These vesicles possess distinctive characteristics that attract attention for their potential use in drug administration and immunotherapy in cancer treatment. Therapeutic medicines may be delivered via OMVs directly to the tumor sites, thereby minimizing exposure to healthy cells and lowering the risk of systemic toxicity. Furthermore, the activation of the immune system by OMVs has been demonstrated to facilitate the recognition and elimination of cancer cells, which makes them a desirable tool for immunotherapy. They can also be genetically modified to carry specific antigens, immunomodulatory compounds, and small interfering RNAs, enhancing the immune response to cancerous cells and silencing genes associated with disease progression. Combining OMVs with other cancer treatments like chemotherapy and radiation has shown promising synergistic effects. This review highlights the crucial role of bacterial OMVs in cancer, emphasizing their potential as vectors for novel cancer targeted therapies. As researchers delve deeper into the complexities of these vesicles and their interactions with tumors, there is a growing sense of optimism that this avenue of study will bring positive outcomes and renewed hope to cancer patients in the foreseeable future.

Metal ions-anchored bacterial outer membrane vesicles for enhanced ferroptosis induction and immune stimulation in targeted antitumor therapy

The activation of ferroptosis presents a versatile strategy for enhancing the antitumor immune responses in cancer therapy. However, developing ferroptosis inducers that combine high biocompatibility and therapeutic efficiency remains challenging. In this study, we propose a novel approach using biological nanoparticles derived from outer membrane vesicles (OMVs) of Escherichia coli for tumor treatment, aiming to activate ferroptosis and stimulate the immune responses. Specifically, we functionalize the OMVs by anchoring them with ferrous ions via electrostatic interactions and loading them with the STING agonist-4, followed by tumor-targeting DSPE-PEG-FA decoration, henceforth referred to as OMV/SaFeFA. The anchoring of ferrous ions endows the OMVs with peroxidase-like activity, capable of inducing cellular lipid peroxidation by catalyzing H2O2 to •OH. Furthermore, OMV/SaFeFA exhibits pH-responsive release of ferrous ions and the agonist, along with tumor-targeting capabilities, enabling tumor-specific therapy while minimizing side effects. Notably, the concurrent activation of the STING pathway and ferroptosis elicits robust antitumor responses in colon tumor-bearing mouse models, leading to exceptional therapeutic efficacy and prolonged survival. Importantly, no acute toxicity was observed in mice receiving OMV/SaFeFA treatments, underscoring its potential for future tumor therapy and clinical translation.

Harnessing and Mimicking Bacterial Features to Combat Cancer: From Living Entities to Artificial Mimicking Systems

Bacterial-derived micro-/nanomedicine has garnered considerable attention in anticancer therapy, owing to the unique natural features of bacteria, including specific targeting ability, immunogenic benefits, physicochemical modifiability, and biotechnological editability. Besides, bacterial components have also been explored as promising drug delivery vehicles. Harnessing these bacterial features, cutting-edge physicochemical and biotechnologies have been applied to attenuated tumor-targeting bacteria with unique properties or functions for potent and effective cancer treatment, including strategies of gene-editing and genetic circuits. Further, the advent of bacteria-inspired micro-/nanorobots and mimicking artificial systems has furnished fresh perspectives for formulating strategies for developing highly efficient drug delivery systems. Focusing on the unique natural features and advantages of bacteria, this review delves into advances in bacteria-derived drug delivery systems for anticancer treatment in recent years, which has experienced a process from living entities to artificial mimicking systems. Meanwhile, a summary of relative clinical trials is provided and primary challenges impeding their clinical application are discussed. Furthermore, future directions are suggested for bacteria-derived systems to combat cancer.

Bacteria extracellular vesicle as nanopharmaceuticals for versatile biomedical potential

Bacteria extracellular vesicles (BEVs), characterized as the lipid bilayer membrane-surrounded nanoparticles filled with molecular cargo from parent cells, play fundamental roles in the bacteria growth and pathogenesis, as well as facilitating essential interaction between bacteria and host systems. Notably, benefiting from their unique biological functions, BEVs hold great promise as novel nanopharmaceuticals for diverse biomedical potential, attracting significant interest from both industry and academia. Typically, BEVs are evaluated as promising drug delivery platforms, on account of their intrinsic cell-targeting capability, ease of versatile cargo engineering, and capability to penetrate physiological barriers. Moreover, attributing to considerable intrinsic immunogenicity, BEVs are able to interact with the host immune system to boost immunotherapy as the novel nanovaccine against a wide range of diseases. Towards these significant directions, in this review, we elucidate the nature of BEVs and their role in activating host immune response for a better understanding of BEV-based nanopharmaceuticals' development. Additionally, we also systematically summarize recent advances in BEVs for achieving the target delivery of genetic material, therapeutic agents, and functional materials. Furthermore, vaccination strategies using BEVs are carefully covered, illustrating their flexible therapeutic potential in combating bacterial infections, viral infections, and cancer. Finally, the current hurdles and further outlook of these BEV-based nanopharmaceuticals will also be provided.

Hybrid Cell Membrane-Based Nanoplatforms for Enhanced Immunotherapy against Cancer and Infectious Diseases

Immunotherapy based on nanoplatforms is a promising approach to treat cancer and infectious diseases, and it has achieved considerable progress in clinical practices. Cell membrane-based nanoplatforms endow nanoparticles with versatile characteristics, such as half-life extension, targeting ability, and immune-system regulation. However, monotypic cell membrane usually fails to provoke strong immune response for immunotherapy while maintaining good biosafety. The integration of different cell-membrane types provides a promising approach to construct multifunctional nanoplatforms for improved immunotherapeutic efficacy by enhancing immunogenicity or targeting function, evading immune clearance, or combining with other therapeutic modalities. In this review, the design principles, preparation strategies, and applications of hybrid cell membrane-based nanoplatforms for cancer and infection immunotherapy are first discussed. Furthermore, the challenges and prospects for the potential clinical translation of hybrid cell membrane-based nanoplatforms are discussed.

Targeted Ferroptosis-Immunotherapy Synergy: Enhanced Antiglioma Efficacy with Hybrid Nanovesicles Comprising NK Cell-Derived Exosomes and RSL3-Loaded Liposomes

Ferroptosis therapy and immunotherapy have been widely used in cancer treatment. However, nonselective induction of ferroptosis in tumors is prone to immunosuppression, limiting the therapeutic effect of ferroptosis cancer treatment. To address this issue, this study reports a customized hybrid nanovesicle composed of NK cell-derived extracellular versicles and RSL3-loaded liposomes (hNRVs), aiming to establish a positive cycle between ferroptosis therapy and immunotherapy. Thanks to the enhanced permeability and retention effect and the tumor homing characteristics of NK exosomes, our data indicate that hNRVs can actively accumulate in tumors and enhance cellular uptake. FASL, IFN-γ, and RSL3 are released into the tumor microenvironment, where FASL derived from NK cells effectively lyses tumor cells. RSL3 downregulates the expression of GPX4 in the tumor, leading to the accumulation of LPO and ROS, and promotes ferroptosis in tumor cells. The accumulation of IFN-γ and TNF-α stimulates the maturation of dendritic cells and effectively induces the inactivation of GPX4, promoting lipid peroxidation, making them sensitive to ferroptosis and indirectly promoting the occurrence of ferroptosis. This study highlights the role of the customized hNRV platform in enhancing the effectiveness of synergistic treatment with selective delivery of ferroptosis inducers and immune activation against glioma without causing additional side effects on healthy organs.

Differential reinforcement of cGAS-STING pathway-involved immunotherapy by biomineralized bacterial outer membrane-sensitized EBRT and RNT

Radiotherapy (RT), including external beam radiation therapy (EBRT) and radionuclide therapy (RNT), realizes physical killing of local tumors and activates systemic anti-tumor immunity. However, these effects need to be further strengthened and the difference between EBRT and RNT should be discovered. Herein, bacterial outer membrane (OM) was biomineralized with manganese oxide (MnO2) to obtain OM@MnO2-PEG nanoparticles for enhanced radio-immunotherapy via amplifying EBRT/RNT-induced immunogenic cell death (ICD) and cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) activation. OM@MnO2-PEG can react with H2O2 and then gradually produce O2, Mn2+ and OM fragments in the tumor microenvironment. The relieved tumor hypoxia improves the radio-sensitivity of tumor cells, resulting in enhanced ICD and DNA damage. Mn2+ together with the DNA fragments in the cytoplasm activate the cGAS-STING pathway, further exhibiting a positive role in various aspects of innate immunity and adaptive immunity. Besides, OM fragments promote tumor antigen presentation and anti-tumor macrophages polarization. More importantly, our study reveals that OM@MnO2-PEG-mediated RNT triggers much stronger cGAS-STING pathway-involved immunotherapy than that of EBRT, owing to the duration difference of RT. Therefore, this study develops a powerful sensitizer of radio-immunotherapy and uncovers some differences between EBRT and RNT in the activation of cGAS-STING pathway-related anti-tumor immunity.

Reconciling the Cooperative-Competitive Patterns among Tumor and Immune Cells for Triple-Negative Breast Cancer Treatment Using Multimodule Nanocomplexes

Targeting the competitive-cooperative relationships among tumor cells and various immune cells can efficiently reverse the immune-dysfunction microenvironment to boost the immunotherapies for the triple-negative breast cancer treatment. Hence, a bacterial outer membrane vesicle-based nanocomplex is designed for specifically targeting malignant cells and immune cells to reconcile the relationships based on metabolic-immune crosstalk. By uniquely utilizing the property of charge-reversal polymers to realize function separation, the nanocomplexes could synergistically regulate tumor cells and immune cells. This approach could reshape the immunosuppressive competition-cooperation pattern into one that is immune-responsive, showcasing significant potential for inducing tumor remission in TNBC models.

Influences of bacterial extracellular vesicles on macrophage immune functions

Bacterial extracellular vesicles (EVs) are crucial mediators of information transfer between bacteria and host cells. Macrophages, as key effector cells in the innate immune system, have garnered widespread attention for their interactions with bacterial EVs. Increasing evidence indicates that bacterial EVs can be internalized by macrophages through multiple pathways, thereby influencing their immune functions. These functions include inflammatory responses, antimicrobial activity, antigen presentation, and programmed cell death. Therefore, this review summarizes current research on the interactions between bacterial EVs and macrophages. This will aid in the deeper understanding of immune modulation mediated by pathogenic microorganisms and provide a basis for developing novel antibacterial therapeutic strategies.

The role of intratumoral microorganisms in the progression and immunotherapeutic efficacy of head and neck cancer

The effectiveness of cancer immunization is largely dependent on the tumor’s microenvironment, especially the tumor immune microenvironment. Emerging studies say microbes exist in tumor cells and immune cells, suggesting that these microbes can affect the state of the immune microenvironment of the tumor. Our comprehensive review navigates the intricate nexus between intratumoral microorganisms and their role in tumor biology and immune modulation. Beginning with an exploration of the historical acknowledgment of microorganisms within tumors, the article underscores the evolution of the tumor microenvironment (TME) and its subsequent implications. Using findings from recent studies, we delve into the unique bacterial compositions across different tumor types and their influence on tumor growth, DNA damage, and immune regulation. Furthermore, we illuminate the potential therapeutic implications of targeting these intratumoral microorganisms, emphasizing their multifaceted roles from drug delivery agents to immunotherapy enhancers. As advancements in next-generation sequencing (NGS) technology redefine our understanding of the tumor microbiome, the article underscores the importance of discerning their precise role in tumor progression and tailoring therapeutic interventions. The review culminates by emphasizing ongoing challenges and the pressing need for further research to harness the potential of intratumoral microorganisms in cancer care.

Nanomaterials in modulating tumor-associated macrophages and enhancing immunotherapy

Tumor-associated macrophages (TAMs) are predominantly present in the tumor microenvironment (TME) and play a crucial role in shaping the efficacy of tumor immunotherapy. These TAMs primarily exhibit a tumor-promoting M2-like phenotype, which is associated with the suppression of immune responses and facilitation of tumor progression. Interestingly, recent research has highlighted the potential of repolarizing TAMs from an M2 to a pro-inflammatory M1 status-a shift that has shown promise in impeding tumor growth and enhancing immune responsiveness. This concept is particularly intriguing as it offers a new dimension to cancer therapy by targeting the tumor microenvironment, which is a significant departure from traditional approaches that focus solely on tumor cells. However, the clinical application of TAM-modulating agents is often challenged by issues such as insufficient tumor accumulation and off-target effects, limiting their effectiveness and safety. In this regard, nanomaterials have emerged as a novel solution. They serve a dual role: as delivery vehicles that can enhance the accumulation of therapeutic agents in the tumor site and as TAM-modulators. This dual functionality of nanomaterials is a significant advancement as it addresses the key limitations of current TAM-modulating strategies and opens up new avenues for more efficient and targeted therapies. This review provides a comprehensive overview of the latest mechanisms and strategies involving nanomaterials in modulating macrophage polarization within the TME. It delves into the intricate interactions between nanomaterials and macrophages, elucidating how these interactions can be exploited to drive macrophage polarization towards a phenotype that is more conducive to anti-tumor immunity. Additionally, the review explores the burgeoning field of TAM-associated nanomedicines in combination with tumor immunotherapy. This combination approach is particularly promising as it leverages the strengths of both nanomedicine and immunotherapy, potentially leading to synergistic effects in combating cancer.

Lactate and lactylation in macrophage metabolic reprogramming: current progress and outstanding issues

It is commonly known that different macrophage phenotypes play specific roles in different pathophysiological processes. In recent years, many studies have linked the phenotypes of macrophages to their characteristics in different metabolic pathways, suggesting that macrophages can perform different functions through metabolic reprogramming. It is now gradually recognized that lactate, previously overlooked as a byproduct of glycolytic metabolism, acts as a signaling molecule in regulating multiple biological processes, including immunological responses and metabolism. Recently, lactate has been found to mediate epigenetic changes in macrophages through a newfound lactylation modification, thereby regulating their phenotypic transformation. This novel finding highlights the significant role of lactate metabolism in macrophage function. In this review, we summarize the features of relevant metabolic reprogramming in macrophages and the role of lactate metabolism therein. We also review the progress of research on the regulation of macrophage metabolic reprogramming by lactylation through epigenetic mechanisms.

Interaction between intestinal flora and gastric cancer in tumor microenvironment

Gastric Cancer (GC) is a prevalent malignancy globally and is the third leading cause of cancer-related deaths. Recent researches focused on the correlation between intestinal flora and GC. Studies indicate that bacteria can influence the development of gastrointestinal tumors by releasing bacterial extracellular vesicles (BEVs). The Tumor microenvironment (TME) plays an important role in tumor survival, with the interaction between intestinal flora, BEVs, and TME directly impacting tumor progression. Moreover, recent studies have demonstrated that intestinal microflora and BEVs can modify TME to enhance the effectiveness of antitumor drugs. This review article provides an overview and comparison of the biological targets through which the intestinal microbiome regulates TME, laying the groundwork for potential applications in tumor diagnosis, treatment, and prognosis.

The Emerging Role of Human Gut Bacteria Extracellular Vesicles in Mental Disorders and Developing New Pharmaceuticals

In recent years, further evidence has emerged regarding the involvement of extracellular vesicles in various human physiopathological conditions such as Alzheimer's disease, Parkinson's disease, irritable bowel syndrome, and mental disorders. The biogenesis and cargo of such vesicles may reveal their impact on human health nd disease and set the underpinnings for the development of novel chemical compounds and pharmaceuticals. In this review, we examine the link between bacteria-derived exosomes in the gastrointestinal tract and mental disorders, such as depression and anxiety disorders. Crucially, we focus on whether changes in the gut environment affect the human mental state or the other way around. Furthermore, the possibility of handling bacteria-derived exosomes as vectors of chemicals to treat such conditions is examined.

Evolving Tumor Characteristics and Smart Nanodrugs for Tumor Immunotherapy

Typical physiological characteristics of tumors, such as weak acidity, low oxygen content, and upregulation of certain enzymes in the tumor microenvironment (TME), provide survival advantages when exposed to targeted attacks by drugs and responsive nanomedicines. Consequently, cancer treatment has significantly progressed in recent years. However, the evolution and adaptation of tumor characteristics still pose many challenges for current treatment methods. Therefore, efficient and precise cancer treatments require an understanding of the heterogeneity degree of various factors in cancer cells during tumor evolution to exploit the typical TME characteristics and manage the mutation process. The highly heterogeneous tumor and infiltrating stromal cells, immune cells, and extracellular components collectively form a unique TME, which plays a crucial role in tumor malignancy, including proliferation, invasion, metastasis, and immune escape. Therefore, the development of new treatment methods that can adapt to the evolutionary characteristics of tumors has become an intense focus in current cancer treatment research. This paper explores the latest understanding of cancer evolution, focusing on how tumors use new antigens to shape their "new faces"; how immune system cells, such as cytotoxic T cells, regulatory T cells, macrophages, and natural killer cells, help tumors become "invisible", that is, immune escape; whether the diverse cancer-associated fibroblasts provide support and coordination for tumors; and whether it is possible to attack tumors in reverse. This paper discusses the limitations of targeted therapy driven by tumor evolution factors and explores future strategies and the potential of intelligent nanomedicines, including the systematic coordination of tumor evolution factors and adaptive methods, to meet this therapeutic challenge.

Harnessing Bacterial Extracellular Vesicle Immune Effects for Cancer Therapy

There are a growing number of studies linking the composition of the human microbiome to disease states and treatment responses, especially in the context of cancer. This has raised significant interest in developing microbes and microbial products as cancer immunotherapeutics that mimic or recapitulate the beneficial effects of host-microbe interactions. Bacterial extracellular vesicles (bEVs) are nano-sized, membrane-bound particles secreted by essentially all bacteria species and contain a diverse bioactive cargo of the producing cell. They have a fundamental role in facilitating interactions among cells of the same species, different microbial species, and even with multicellular host organisms in the context of colonization (microbiome) and infection. The interaction of bEVs with the immune system has been studied extensively in the context of infection and suggests that bEV effects depend largely on the producing species. They thus provide functional diversity, while also being nonreplicative, having inherent cell-targeting qualities, and potentially overcoming natural barriers. These characteristics make them highly appealing for development as cancer immunotherapeutics. Both natively secreted and engineered bEVs are now being investigated for their application as immunotherapeutics, vaccines, drug delivery vehicles, and combinations of the above, with promising early results. This suggests that both the intrinsic immunomodulatory properties of bEVs and their ability to be modified could be harnessed for the development of next-generation microbe-inspired therapies. Nonetheless, there remain major outstanding questions regarding how the observed preclinical effectiveness will translate from murine models to primates, and humans in particular. Moreover, research into the pharmacology, toxicology, and mass manufacturing of this potential novel therapeutic platform is still at early stages. In this review, we highlight the breadth of bEV interactions with host cells, focusing on immunologic effects as the main mechanism of action of bEVs currently in preclinical development. We review the literature on ongoing efforts to develop natively secreted and engineered bEVs from a variety of bacterial species for cancer therapy and finally discuss efforts to overcome outstanding challenges that remain for clinical translation.

The emerging tumor microbe microenvironment: From delineation to multidisciplinary approach-based interventions

Intratumoral microbiota has become research hotspots, and emerges as a non-negligent new component of tumor microenvironments (TME), due to its powerful influence on tumor initiation, metastasis, immunosurveillance and prognosis despite in low-biomass. The accumulations of microbes, and their related components and metabolites within tumor tissues, endow TME with additional pluralistic features which are distinct from the conventional one. Therefore, it's definitely necessary to comprehensively delineate the sophisticated landscapes of tumor microbe microenvironment, as well as their functions and related underlying mechanisms. Herein, in this review, we focused on the fields of tumor microbe microenvironment, including the heterogeneity of intratumor microbiota in different types of tumors, the controversial roles of intratumoral microbiota, the basic features of tumor microbe microenvironment (i.e., pathogen-associated molecular patterns (PAMPs), typical microbial metabolites, autophagy, inflammation, multi-faceted immunomodulation and chemoresistance), as well as the multidisciplinary approach-based intervention of tumor microbiome for cancer therapy by applying wild-type or engineered live microbes, microbiota metabolites, antibiotics, synthetic biology and rationally designed biomaterials. We hope our work will provide valuable insight to deeply understand the interplay of cancer-immune-microbial, and facilitate the development of microbes-based tumor-specific treatments.

Advances in Engineered Macrophages: A New Frontier in Cancer Immunotherapy

Macrophages, as pivotal cells within the tumour microenvironment, significantly influence the impact of and reactions to treatments for solid tumours. The rapid evolution of bioengineering technology has revealed the vast potential of engineered macrophages in immunotherapy, disease diagnosis, and tissue engineering. Given this landscape, the goal of harnessing and innovating macrophages as a novel strategy for solid tumour immunotherapy cannot be overstated. The diverse strategies for engineered macrophages in the realm of cancer immunotherapy, encompassing macrophage drug delivery systems, chimeric antigen receptor macrophage therapy, and synergistic treatment approaches involving bacterial outer membrane vesicles and macrophages, are meticulously examined in this review. These methodologies are designed to enhance the therapeutic efficacy of macrophages against solid tumours, particularly those that are drug-resistant and metastatic. Collectively, these immunotherapies are poised to supplement and refine current solid tumour treatment paradigms, thus heralding a new frontier in the fight against malignant tumours.

Oral probiotics microgel plus Galunisertib reduced TGF-β blockade resistance and enhanced anti-tumor immune responses in colorectal cancer

Transforming growth factor β (TGF-β), a versatile immunosuppressive cytokine, has gained increasing attention as a potential target for cancer immunotherapy. However, current strategies are constrained by tumor heterogeneity and drug resistance. Therapeutic probiotics, such as Escherichia coli Nissle1917 (EcN), not only regulate the gut microbiota to increase beneficial bacteria with anti-tumor effects, but also modulate immune factors within the body, thereby enhancing immunity. In this study, we developed an oral microgel delivery system of EcN@(CS-SA)2 by electrostatic interaction between chitosan (CS) and sodium alginate (SA), aiming to enhance its bioavailability in the gastrointestinal tract (GIT). Notably, EcN@(CS-SA)2 microgel showed a synergistic enhancement of the anti-tumor efficacy of Galunisertib (Gal, a TGF-β inhibitor) by inducing apoptosis and immunogenic cell death (ICD) in tumor cells, as well as promoting increased infiltration of CD8+ T cells into the tumor microenvironment (TME).

Engineered Bacterial Biomimetic Vesicles Reprogram Tumor-Associated Macrophages and Remodel Tumor Microenvironment to Promote Innate and Adaptive Antitumor Immune Responses

Tumor-associated macrophages (TAMs) are among the most abundant infiltrating leukocytes in the tumor microenvironment (TME). Reprogramming TAMs from protumor M2 to antitumor M1 phenotype is a promising strategy for remodeling the TME and promoting antitumor immunity; however, the development of an efficient strategy remains challenging. Here, a genetically modified bacterial biomimetic vesicle (BBV) with IFN-γ exposed on the surface in a nanoassembling membrane pore structure was constructed. The engineered IFN-γ BBV featured a nanoscale structure of protein and lipid vesicle, the existence of rich pattern-associated molecular patterns (PAMPs), and the costimulation of introduced IFN-γ molecules. In vitro, IFN-γ BBV reprogrammed M2 macrophages to M1, possibly through NF-κB and JAK-STAT signaling pathways, releasing nitric oxide (NO) and inflammatory cytokines IL-1β, IL-6, and TNF-α and increasing the expression of IL-12 and iNOS. In tumor-bearing mice, IFN-γ BBV demonstrated a targeted enrichment in tumors and successfully reprogrammed TAMs into the M1 phenotype; notably, the response of antigen-specific cytotoxic T lymphocyte (CTL) in TME was promoted while the immunosuppressive myeloid-derived suppressor cell (MDSC) was suppressed. The tumor growth was found to be significantly inhibited in both a TC-1 tumor and a CT26 tumor. It was indicated that the antitumor effects of IFN-γ BBV were macrophage-dependent. Further, the modulation of TME by IFN-γ BBV produced synergistic effects against tumor growth and metastasis with an immune checkpoint inhibitor in an orthotopic 4T1 breast cancer model which was insensitive to anti-PD-1 mAb alone. In conclusion, IFN-γ-modified BBV demonstrated a strong capability of efficiently targeting tumor and tuning a cold tumor hot through reprogramming TAMs, providing a potent approach for tumor immunotherapy.

Physio-chemical Modifications to Re-engineer Small Extracellular Vesicles for Targeted Anticancer Therapeutics Delivery and Imaging

Cancer theranostics developed through nanoengineering applications are essential for targeted oncologic interventions in the new era of personalized and precision medicine. Recently, small extracellular vesicles (sEVs) have emerged as an attractive nanoengineering platform for tumor-directed anticancer therapeutic delivery and imaging of malignant tumors. These natural nanoparticles have multiple advantages over synthetic nanoparticle-based delivery systems, such as intrinsic targeting ability, less immunogenicity, and a prolonged circulation time. Since the inception of sEVs as a viable replacement for liposomes (synthetic nanoparticles) as a drug delivery vehicle, many studies have attempted to further the therapeutic efficacy of sEVs. This article discusses engineering strategies for sEVs using physical and chemical methods to enhance their anticancer therapeutic delivery performance. We review physio-chemical techniques of effective therapeutic loading into sEV, sEV surface engineering for targeted entry of therapeutics, and its cancer environment sensitive release inside the cells/organ. Next, we also discuss the novel hybrid sEV systems developed by a combination of sEVs with lipid and metal nanoparticles to garner each component's benefits while overcoming their drawbacks. The article extensively analyzes multiple sEV labeling techniques developed and investigated for live tracking or imaging sEVs. Finally, we discuss the theranostic potential of engineered sEVs in future cancer care regimens.

Chemoimmunotherapeutic Nanogel for Pre- and Postsurgical Treatment of Malignant Melanoma by Reprogramming Tumor-Associated Macrophages

Surgery is the primary method to treat malignant melanoma; however, the residual microtumors that cannot be resected completely often trigger tumor recurrence, causing tumor-related mortality following melanoma resection. Herein, we developed a feasible strategy based on the combinational chemoimmunotherapy by cross-linking carboxymethyl chitosan (CMCS)-originated polymetformin (PolyMetCMCS) with cystamine to prepare stimuli-responsive nanogel (PMNG) owing to the disulfide bond in cystamine that can be cleaved by the massive glutathione (GSH) in tumor sites. Then, chemotherapeutic agent doxorubicin (DOX) was loaded in PMNG, which was followed by a hyaluronic acid coating to improve the overall biocompatibility and targeting ability of the prepared nanogel (D@HPMNG). Notably, PMNG effectively reshaped the tumor immune microenvironment by reprogramming tumor-associated macrophage phenotypes and recruiting intratumoral CD8+ T cells owing to the inherited immunomodulatory capability of metformin. Consequently, D@HPMNG treatment remarkably suppressed melanoma growth and inhibited its recurrence after surgical resection, proposing a promising solution for overcoming lethal melanoma recurrence.

Tenacibaculum dicentrarchi produce outer membrane vesicles (OMV) that are associated with the cytotoxic effect in rainbow trout head kidney macrophages

Tenacibaculum dicentrarchi is the second most important pathogen in Chilean salmon farming. This microorganism causes severe skin lesions on the body surface of farmed fish. The bacterium can also adhere to surfaces and form biofilm, survive in fish skin mucus, and possess different systems for iron acquisition. However, the virulence mechanisms are still not fully elucidated. Outer membrane vesicles (OMV) are nanostructures released by pathogenic Gram-negative bacteria during growth, but none has been described yet for T. dicentrarchi. In this study, we provide the first reported evidence of the fish pathogen T. dicentrarchi producing and releasing OMV from 24 h after incubation, increasing thereafter until 120 h. Analyses were conducted with T. dicentrarchi TdCh05, QCR29, and the type strain CECT 7612T . The OMV sizes, determined via scanning electron microscopy, ranged from 82.25 nm to 396.88 nm as per the strain and incubation time point (i.e., 24 to 120 h). SDS-PAGE revealed that the number of protein bands evidenced a drastically downward trend among the T. dicentrarchi strains. In turn, the OMV shared five proteins (i.e., 22.2, 31.9, 47.7, 56.3, and 107.1 kDa), but no protein pattern was identical. A heterogeneous amount of protein, RNA, and DNA were obtained, depending on the time at which OMV were extracted. Purified OMV were biologically active and induced a cytotoxic effect in macrophage-enriched cell cultures from rainbow trout (Oncorhynchus mykiss) head kidneys. This is the first step towards understanding the role that OMV could play in the pathogenesis of T. dicentrarchi.

Nanotechnology Reprogramming Metabolism for Enhanced Tumor Immunotherapy

Mutation burden, hypoxia, and immunoediting contribute to altered metabolic profiles in tumor cells, resulting in a tumor microenvironment (TME) characterized by accumulation of toxic metabolites and depletion of various nutrients, which significantly hinder the antitumor immunity via multiple mechanisms, hindering the efficacy of tumor immunotherapies. In-depth investigation of the mechanisms underlying these phenomena are vital for developing effective antitumor drugs and therapies, while the therapeutic effects of metabolism-targeting drugs are restricted by off-target toxicity toward effector immune cells and high dosage-mediated side effects. Nanotechnologies, which exhibit versatility and plasticity in targeted delivery and metabolism modulation, have been widely applied to boost tumor immunometabolic therapies via multiple strategies, including targeting of metabolic pathways. In this review, recent advances in understanding the roles of tumor cell metabolism in both immunoevasion and immunosuppression are reviewed, and nanotechnology-based metabolic reprogramming strategies for enhanced tumor immunotherapies are discussed.

Magnetically-targetable outer-membrane vesicles for sonodynamic eradication of antibiotic-tolerant bacteria in bacterial meningitis

Treatment of acute bacterial meningitis is difficult due to the impermeability of the blood-brain barrier, greatly limiting the antibiotic concentrations that can be achieved in the brain. Escherichia coli grown in presence of iron-oxide magnetic nanoparticles secrete large amounts of magnetic outer-membrane vesicles (OMVs) in order to remove excess Fe from their cytoplasm. OMVs are fully biomimetic nanocarriers, but can be inflammatory. Here, non-inflammatory magnetic OMVs were prepared from an E. coli strain in which the synthesis of inflammatory lipid A acyltransferase was inhibited using CRISPR/Cas9 mediated gene knockout. OMVs were loaded with ceftriaxone (CRO) and meso-tetra-(4-carboxyphenyl)porphine (TCPP) and magnetically driven across the blood-brain barrier for sonodynamic treatment of bacterial meningitis. ROS-generation upon ultrasound application of CRO- and TCPP-loaded OMVs yielded similar ROS-generation as by TCPP in solution. In vitro, ROS-generation by CRO- and TCPP-loaded OMVs upon ultrasound application operated synergistically with CRO to kill a hard-to-kill, CRO-tolerant E. coli strain. In a mouse model of CRO-tolerant E. coli meningitis, CRO- and TCPP-loaded OMVs improved survival rates and clinical behavioral scores of infected mice after magnetic targeting and ultrasound application. Recurrence did not occur for at least two weeks after arresting treatment.

Tumor Metabolism-Rewriting Nanomedicines for Cancer Immunotherapy

Cancer immunotherapy has become an established therapeutic paradigm in oncologic therapy, but its therapeutic efficacy remains unsatisfactory in the majority of cancer patients. Accumulating evidence demonstrates that the metabolically hostile tumor microenvironment (TME), characterized by acidity, deprivation of oxygen and nutrients, and accumulation of immunosuppressive metabolites, promotes the dysfunction of tumor-infiltrating immune cells (TIICs) and thereby compromises the effectiveness of immunotherapy. This indicates the potential role of tumor metabolic intervention in the reinvigoration of antitumor immunity. With the merits of multiple drug codelivery, cell and organelle-specific targeting, controlled drug release, and multimodal therapy, tumor metabolism-rewriting nanomedicines have recently emerged as an attractive strategy to strengthen antitumor immune responses. This review summarizes the current progress in the development of multifunctional tumor metabolism-rewriting nanomedicines for evoking antitumor immunity. A special focus is placed on how these nanomedicines reinvigorate innate or adaptive antitumor immunity by regulating glucose metabolism, amino acid metabolism, lipid metabolism, and nucleotide metabolism at the tumor site. Finally, the prospects and challenges in this emerging field are discussed.

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.

Magnetically Powered Immunogenic Macrophage Microrobots for Targeted Multimodal Cancer Therapy

Motile microrobots open a new realm for disease treatment. However, the concerns of possible immune elimination, targeted capability and limited therapeutic avenue of microrobots constrain its practical biomedical applications. Herein, a biogenic macrophage-based microrobot loaded with magnetic nanoparticles and bioengineered bacterial outer membrane vesicles (OMVs), capable of magnetic propulsion, tumor targeting, and multimodal cancer therapy is reported. Such cell robots preserve intrinsic properties of macrophages for tumor suppression and targeting, and bioengineered OMVs for antitumor immune regulation and fused anticancer peptides. Cell robots display efficient magnetic propulsion and directional migration in the confined space. In vivo tests show that cell robots can accumulate at the tumor site upon magnetic manipulation, coupling with tumor tropism of macrophages to greatly improve the efficacy of its multimodal therapy, including tumor inhibition of macrophages, immune stimulation, and antitumor peptides of OMVs. This technology offers an attractive avenue to design intelligent medical microrobots with remote manipulation and multifunctional therapy capabilities for practical precision treatment.

Targeting Pyroptosis through Lipopolysaccharide-Triggered Noncanonical Pathway for Safe and Efficient Cancer Immunotherapy

Inducing pyroptosis in cancer cells holds great potential in cancer immunotherapy. Lipopolysaccharide (LPS)-sensing noncanonical pathways are an important mechanism of pyroptosis to eliminate damaged cells, which has not yet been explored for cancer immunotherapy. Here, we utilize bacterial outer membrane vesicles (OMVs) as a natural LPS carrier to trigger a noncanonical pyroptosis pathway for immunotherapy. To address the concern of systemic toxicity, molecule engineered OMVs were designed by equipping DNA aptamers on the OMVs (Apt-OMVs). In addition to improving capacity to target tumors, Apt-OMVs also took advantage of the spherical nucleic acid structure to shield OMVs against nonspecific immune recognition and evade immunogenicity. The selective pyroptosis enhanced tumor immunogenicity, not only promoting the infiltration of effector T cells but also reducing the amount of immunosuppressive regulatory T cells, which remarkably suppressed tumor growth. This work reports the first pyroptosis inducer by the noncanonical pathway, offering inspiration for safe and efficient pyroptosis-mediated immunotherapy.

Bacterial outer membrane vesicles in cancer: Biogenesis, pathogenesis, and clinical application

Outer membrane vesicles (OMVs) are spherical, nano-sized particles of bilayer lipid structure secreted by Gram-negative bacteria. They contain a series of cargos from bacteria and are important messengers for communication between bacteria and their environment. OMVs play multiple roles in bacterial survival and adaptation and can affect host physiological functions and disease development by acting on host cell membranes and altering host cell signaling pathways. This paper summarizes the mechanisms of OMV genesis and the multiple roles of OMVs in the tumor microenvironment. Also, this paper discusses the prospects of OMVs for a wide range of applications in drug delivery, tumor diagnosis, and therapy.

Microbe-host interactions: structure and functions of Gram-negative bacterial membrane vesicles

Bacteria-host interaction is a common, relevant, and intriguing biological phenomena. The host reacts actively or passively to the bacteria themselves, their products, debris, and so on, through various defense systems containing the immune system, the bacteria communicate with the local or distal tissues of the host via their own surface antigens, secreted products, nucleic acids, etc., resulting in relationships of attack and defense, adaptation, symbiosis, and even collaboration. The significance of bacterial membrane vesicles (MVs) as a powerful vehicle for the crosstalk mechanism between the two is growing. In the recent decade, the emergence of MVs in microbial interactions and a variety of bacterial infections, with multiple adhesions to host tissues, cell invasion and evasion of host defense mechanisms, have brought MVs to the forefront of bacterial pathogenesis research. Whereas MVs are a complex combination of molecules not yet fully understood, research into its effects, targeting and pathogenic components will advance its understanding and utilization. This review will summarize structural, extraction and penetration information on several classes of MVs and emphasize the role of MVs in transport and immune response activation. Finally, the potential of MVs as a therapeutic method will be highlighted, as will future research prospects.

Engineered extracellular vesicles-like biomimetic nanoparticles as an emerging platform for targeted cancer therapy

Nanotechnology offers the possibility of revolutionizing cancer theranostics in the new era of precision oncology. Extracellular vesicles (EVs)-like biomimetic nanoparticles (EBPs) have recently emerged as a promising platform for targeted cancer drug delivery. Compared with conventional synthetic vehicles, EBPs have several advantages, such as lower immunogenicity, longer circulation time, and better targeting capability. Studies on EBPs as cancer therapeutics are rapidly progressing from in vitro experiments to in vivo animal models and early-stage clinical trials. Here, we describe engineering strategies to further improve EBPs as effective anticancer drug carriers, including genetic manipulation of original cells, fusion with synthetic nanomaterials, and direct modification of EVs. These engineering approaches can improve the anticancer performance of EBPs, especially in terms of tumor targeting effectiveness, stealth property, drug loading capacity, and integration with other therapeutic modalities. Finally, the current obstacles and future perspectives of engineered EBPs as the next-generation delivery platform for anticancer drugs are discussed.

Smart Targeted Delivery Systems for Enhancing Antitumor Therapy of Active Ingredients in Traditional Chinese Medicine

As a therapeutic tool inherited for thousands of years, traditional Chinese medicine (TCM) exhibits superiority in tumor therapy. The antitumor active components of TCM not only have multi-target treatment modes but can also synergistically interfere with tumor growth compared to traditional chemotherapeutics. However, most antitumor active components of TCM have the characteristics of poor solubility, high toxicity, and side effects, which are often limited in clinical application. In recent years, delivering the antitumor active components of TCM by nanosystems has been a promising field. The advantages of nano-delivery systems include improved water solubility, targeting efficiency, enhanced stability in vivo, and controlled release drugs, which can achieve higher drug-delivery efficiency and bioavailability. According to the method of drug loading on nanocarriers, nano-delivery systems can be categorized into two types, including physically encapsulated nanoplatforms and chemically coupled drug-delivery platforms. In this review, two nano-delivery approaches are considered, namely physical encapsulation and chemical coupling, both commonly used to deliver antitumor active components of TCM, and we summarized the advantages and limitations of different types of nano-delivery systems. Meanwhile, the clinical applications and potential toxicity of nano-delivery systems and the future development and challenges of these nano-delivery systems are also discussed, aiming to lay the foundation for the development and practical application of nano-delivery systems of TCM in clinical settings.

Bacterial Outer Membrane Vesicles Loaded with Perhexiline Suppress Tumor Development by Regulating Tumor-Associated Macrophages Repolarization in a Synergistic Way

Tumor-associated macrophages (TAMs) promote tumor development and metastasis and are categorized into M1-like macrophages, suppressing tumor cells, and M2-like macrophages. M2-like macrophages, occupying a major role in TAMs, can be repolarized into anti-tumoral phenotypes. In this study, outer membrane vesicles (OMVs) secreted by Escherichia coli Nissle 1917 carry perhexiline (OMV@Perhx) to explore the influence of OMVs and perhexiline on TAM repolarization. OMV@Perhx was internalized by macrophages and regulated the phenotype of TAMs from M2-like to M1-like efficiently to increase the level of tumor suppressor accordingly. Re-polarized macrophages promoted apoptosis and inhibited the mobility of tumor, cells including invasion and migration. The results indicate that OMVs improve the efficacy of perhexiline and also represent a promising natural immunomodulator. Combining OMVs with perhexiline treatments shows powerfully synergistic anti-tumor effects through co-culturing with re-polarized macrophages. This work is promising to exploit the extensive applications of OMVs and chemical drugs, therefore developing a meaningful drug carrier and immunomodulator as well as expanding the purposes of traditional chemical drugs.

Biomembrane-wrapped gene delivery nanoparticles for cancer therapy

As a promising strategy, gene delivery for cancer treatment accepts encouraging progress due to its high efficacy, low toxicity, and exclusive selectivity. However, the delivery efficiency, specific biological distribution, targeted uptake, and biosafety of naked nucleic acid agents still face serious challenges, which limit further clinical application. To overcome the above bottleneck, safe and efficient functional nanovectors are developed to improve the delivery efficiency of nucleic acid agents. In recent years, emerging membrane-wrapped biomimetic nanoparticles (MBNPs) based on the concept of "imitating nature" are well known for their advantages, such as low immunogenicity and long cycle time, and especially play a crucial role in improving the overall efficiency of gene delivery and reducing adverse reactions. Therefore, combining MBNPs and gene delivery is an effective strategy to enhance tumor treatment efficiency. This review presents the mechanism of gene therapy and the current obstacles to gene delivery. Remarkably, the latest development of gene delivery MBNPs and the strategies to overcome these obstacles are summarized. Finally, the future challenges and prospects of gene delivery MBNPs toward clinical transformation are introduced. The principal purpose of this review is to discuss the biomedical potential of gene delivery MBNPs for cancer therapy and to provide guidance for further enhancing the efficiency of tumor gene therapy.

Lipid-based nanoparticles for cancer immunotherapy

As the fourth most important cancer management strategy except surgery, chemotherapy and radiotherapy, cancer immunotherapy has been confirmed to elicit durable antitumor effects in the clinic by leveraging the patient's own immune system to eradicate the cancer cells. However, the limited population of patients who benefit from the current immunotherapies and the immune related adverse events hinder its development. The immunosuppressive microenvironment is the main cause of the failure, which leads to cancer immune evasion and immunity cycle blockade. Encouragingly, nanotechnology has been engineered to enhance the efficacy and reduce off-target toxicity of their therapeutic cargos by spatiotemporally controlling the biodistribution and release kinetics. Among them, lipid-based nanoparticles are the first nanomedicines to make clinical translation, which are now established platforms for diverse areas. In this perspective, we discuss the available lipid-based nanoparticles in research and market here, then describe their application in cancer immunotherapy, with special emphasis on the T cells-activated and macrophages-targeted delivery system. Through perpetuating each step of cancer immunity cycle, lipid-based nanoparticles can reduce immunosuppression and promote drug delivery to trigger robust antitumor response.

Pathogen Recognition-Driven Dendritic Cell-Specific Gene Silencing and Editing

Dendritic cells (DCs) play an essential role in both the induction of the immune response and the maintenance of immune tolerance, with any malfunction of DCs potentially causing several diseases. While gene-based therapy for DC manipulation is a promising approach, it remains challenging due to the lack of efficient delivery systems for DC targeting. Herein, we describe a novel bacterial nanomedicine (BNM) system for pathogen recognition-mediated DCs-specific gene silencing and gene editing. BNMs contain components from bacterial outer membranes and achieve efficient DC targeting through the recognition of pathogen-associated molecular patterns by pattern recognition receptors on DCs. The targeting efficiency of BNMs is reduced in DCs lacking toll-like receptor 4, which is responsible for recognizing lipopolysaccharide, a major component of the bacterial outer membrane. As a proof-of-concept demonstration, we present gene-based therapy mediated by BNMs for enhancing antigen cross-presentation in DCs, which generates a remarkable antitumor effect.

Bacterial-Mediated Tumor Therapy: Old Treatment in a New Context

Targeted therapy and immunotherapy have brought hopes for precision cancer treatment. However, complex physiological barriers and tumor immunosuppression result in poor efficacy, side effects, and resistance to antitumor therapies. Bacteria-mediated antitumor therapy provides new options to address these challenges. Thanks to their special characteristics, bacteria have excellent ability to destroy tumor cells from the inside and induce innate and adaptive antitumor immune responses. Furthermore, bacterial components, including bacterial vesicles, spores, toxins, metabolites, and other active substances, similarly inherit their unique targeting properties and antitumor capabilities. Bacteria and their accessory products can even be reprogrammed to produce and deliver antitumor agents according to clinical needs. This review first discusses the role of different bacteria in the development of tumorigenesis and the latest advances in bacteria-based delivery platforms and the existing obstacles for application. Moreover, the prospect and challenges of clinical transformation of engineered bacteria are also summarized.

Versatile biomimetic nanomedicine for treating cancer and inflammation disease

Nanosized drug delivery systems (NDDSs) have emerged as a powerful tool to optimize drug delivery in complex diseases, including cancer and inflammation. However, the therapeutic effect of NDDSs is still far from satisfactory due to their poor circulation time, low delivery efficiency, and innate toxicity. Fortunately, biomimetic approaches offer new opportunities to develop nanomedicine, which is derived from a variety of native biomolecules including cells, exosomes, bacteria, and so on. Since inheriting the superior biocompatibility and versatile functions of natural materials, biomimetic nanomedicine can mimic biological processes, prolong blood circulation, and lower immunogenicity, serving as a desired platform for precise drug delivery for treating cancer and inflammatory disease. In this review, we outline recent advances in biomimetic NDDSs, which consist of two concepts: biomimetic exterior camouflage and bioidentical molecule construction. We summarize engineering strategies that further functionalized current biomimetic NDDSs. A series of functional biomimetic NDDSs created by our group are introduced. We conclude with an outlook on remaining challenges and possible directions for biomimetic NDDSs. We hope that better technologies can be inspired and invented to advance drug delivery systems for cancer and inflammation therapy.

YY1 complex in M2 macrophage promotes prostate cancer progression by upregulating IL-6

BACKGROUND

Tumor-associated macrophages are mainly polarized into the M2 phenotype, remodeling the tumor microenvironment and promoting tumor progression by secreting various cytokines.

METHODS

Tissue microarray consisting of prostate cancer (PCa), normal prostate, and lymph node metastatic samples from patients with PCa were stained with Yin Yang 1 (YY1) and CD163. Transgenic mice overexpressing YY1 were constructed to observe PCa tumorigenesis. Furthermore, in vivo and in vitro experiments, including CRISPR-Cas9 knock-out, RNA sequencing, chromatin immunoprecipitation (ChIP) sequencing, and liquid-liquid phase separation (LLPS) assays, were performed to investigate the role and mechanism of YY1 in M2 macrophages and PCa tumor microenvironment.

RESULTS

YY1 was highly expressed in M2 macrophages in PCa and was associated with poorer clinical outcomes. The proportion of tumor-infiltrated M2 macrophages increased in transgenic mice overexpressing YY1. In contrast, the proliferation and activity of anti-tumoral T lymphocytes were suppressed. Treatment targeting YY1 on M2 macrophages using an M2-targeting peptide-modified liposome carrier suppressed PCa cell lung metastasis and generated synergistic anti-tumoral effects with PD-1 blockade. IL-4/STAT6 pathway regulated YY1, and YY1 increased the macrophage-induced PCa progression by upregulating IL-6. Furthermore, by conducting H3K27ac-ChIP-seq in M2 macrophages and THP-1, we found that thousands of enhancers were gained during M2 macrophage polarization, and these M2-specific enhancers were enriched in YY1 ChIP-seq signals. In addition, an M2-specific IL-6 enhancer upregulated IL-6 expression through long-range chromatin interaction with IL-6 promoter in M2 macrophages. During M2 macrophage polarization, YY1 formed an LLPS, in which p300, p65, and CEBPB acted as transcriptional cofactors.

CONCLUSIONS

Phase separation of the YY1 complex in M2 macrophages upregulated IL-6 by promoting IL-6 enhancer-promoter interactions, thereby increasing PCa progression.