Combination of bacterial-targeted delivery of gold-based AIEgen radiosensitizer for fluorescence-image-guided enhanced radio-immunotherapy against advanced cancer

Amplifying Radiotherapy by Evoking Mitochondrial Oxidative Stress using a High-performance Aggregation-induced Emission Sonosensitizer

INTRODUCTION

Developing effective methods to enhance tumor radiosensitivity is crucial for improving the therapeutic efficacy of radiotherapy (RT). Due to its deep tissue penetration, excellent safety profile, and precise controllability, sonosensitizer-based sonodynamic therapy (SDT) has recently garnered significant attention as a promising combined approach with RT.

METHODS

However, the limited reactive oxygen species (ROS) generation ability in the aggregated state and the absence of specific organelle targeting in sonosensitizers hinder their potential to augment RT. This study introduces a fundamental principle guiding the design of high-performance sonosensitizers employed in the aggregated state. Building upon these principles, we develop a mitochondria-targeted sonosensitizer molecule (TCSVP) with aggregation- induced emission (AIE) characteristics by organic synthesis. Then, we demonstrate the abilities of TCSVP to target mitochondria and produce ROS under ultrasound in H460 cancer cells using confocal laser scanning microscopy (CLSM) and fluorescence microscopy. Subsequently, we examine the effectiveness of enhancing tumor radiosensitivity by utilizing TCSVP and ultrasound in both H460 cells and H460 and 4T1 tumor-bearing mice.

RESULTS

The results indicate that evoking non-lethal mitochondrial oxidative stress in tumors by TCSVP under ultrasound stimulation can significantly improve tumor radiosensitivity (p <0.05). Additionally, the in vivo safety profile of TCSVP is thoroughly confirmed by histopathological analysis.

CONCLUSION

This work proposes strategies for designing efficient sonosensitizers and underscores that evoking non-lethal mitochondrial oxidative stress is an effective method to enhance tumor radiosensitivity.

Nanomedicines harnessing cGAS-STING pathway: sparking immune revitalization to transform 'cold' tumors into 'hot' tumors

cGAS-STING pathway stands at the forefront of innate immunity and plays a critical role in regulating adaptive immune responses, making it as a key orchestrator of anti-tumor immunity. Despite the great potential, clinical outcomes with cGAS-STING activators have been disappointing due to their unfavorable in vivo fate, signaling an urgent need for innovative solutions to bridge the gap in clinical translation. Recent advancements in nanotechnology have propelled cGAS-STING-targeting nanomedicines to the cutting-edge of cancer therapy, leveraging precise drug delivery systems and multifunctional platforms to achieve remarkable region-specific biodistribution and potent therapeutic efficacy. In this review, we provide an in-depth exploration of the molecular mechanisms that govern cGAS-STING signaling and its potential to dynamically modulate the anti-tumor immune cycle. We subsequently introduced several investigational cGAS-STING-dependent anti-tumor agents and summarized their clinical trial progress. Additionally, we provided a comprehensive review of the unique advantages of cGAS-STING-targeted nanomedicines, highlighting the transformative potential of nanotechnology in this field. Furthermore, we comprehensively reviewed and comparatively analyzed the latest breakthroughs cGAS-STING-targeting nanomedicine, focusing on strategies that induce cytosolic DNA generation via exogenous DNA delivery, chemotherapy, radiotherapy, or dynamic therapies, as well as the nanodelivery of STING agonists. Lastly, we discuss the future prospects and challenges in cGAS-STING-targeting nanomedicine development, offering new insights to bridge the gap between mechanistic research and drug development, thereby opening new pathways in cancer treatment.

Salmonella-based therapeutic strategies: improving tumor microenvironment and bringing new hope for cancer immunotherapy

Immunotherapy has revolutionized cancer treatment, yet its effectiveness is limited by immunosuppressive tumor microenvironment (TME). To overcome this challenge, innovative strategies to effectively modulate the TME are urgently needed. Over the past decades, bacteria-mediated cancer immunotherapy has recaptured increasing attention, driven by advances in synthetic biology, genetic engineering and our knowledge of host-pathogen interactions. Among various bacterial species, Salmonella has emerged as a leading candidate with significant therapeutic potential due to its broad-spectrum anti-tumor activity, tumor-targeting ability, immunomodulatory effects, oncolytic properties, genetic programmability, and engineering flexibility. These characteristics enable Salmonella to reshape the immunosuppressive TME, thereby enhancing anti-tumor efficacy. This review elaborates the regulatory effects of Salmonella on key components of the TME, the versatile engineering strategies for optimizing Salmonella's ability to modulate the TME, and recent advancements in combination cancer therapies. We also summarize current clinical applications and discuss challenges of developing safer and more effective Salmonella-based cancer immunotherapy.

The Rational Engineered Bacteria Based Biohybrid Living System for Tumor Therapy

Living therapy based on bacterial cells has gained increasing attention for their applications in tumor treatments. Bacterial cells can naturally target to tumor sites and active the innate immunological responses. The intrinsic advantages of bacteria attribute to the development of biohybrid living carriers for targeting delivery toward hypoxic environments. The rationally engineered bacterial cells integrate various functions to enhance the tumor therapy and reduce toxic side effects. In this review, the antitumor effects of bacteria and their application are discussed as living therapeutic agents across multiple antitumor platforms. The various kinds of bacteria used for cancer therapy are first introduced and demonstrated the mechanism of antitumor effects as well as the immunological effects. Additionally, this study focused on the genetically modified bacteria for the production of antitumor agents as living delivery system to treat cancer. The combination of living bacterial cells with functional nanomaterials is then discussed in the cancer treatments. In brief, the rational design of living therapy based on bacterial cells highlighted a rapid development in tumor therapy and pointed out the potentials in clinical applications.

Expanding Our Horizons: AIE Materials in Bacterial Research

Bacteria share a longstanding and complex relationship with humans, playing a role in protecting gut health and sustaining the ecosystem to cause infectious diseases and antibiotic resistance. Luminogenic materials that share aggregation-induced emission (AIE) characteristics have emerged as a versatile toolbox for bacterial studies through fluorescence visualization. Numerous research efforts highlight the superiority of AIE materials in this field. Recent advances in AIE materials in bacterial studies are categorized into four areas: understanding bacterial interactions, antibacterial strategies, diverse applications, and synergistic applications with bacteria. Initial research focuses on visualizing the unseen bacteria and progresses into developing strategies involving electrostatic interactions, amphiphilic AIE luminogens (AIEgens), and various AIE materials to enhance bacterial affinity. Recent progress in antibacterial strategies includes using photodynamic and photothermal therapies, bacterial toxicity studies, and combined therapies. Diverse applications from environmental disinfection to disease treatment, utilizing AIE materials in antibacterial coatings, bacterial sensors, wound healing materials, etc., are also provided. Finally, synergistic applications combining AIE materials with bacteria to achieve enhanced outcomes are explored. This review summarizes the developmental trend of AIE materials in bacterial studies and is expected to provide future research directions in advancing bacterial methodologies.

Stimuli-responsive nanotheranostic systems conjugated with AIEgens for advanced cancer bio-imaging and treatment

Aggregation-induced emission (AIE) is a unique phenomenon observed in various materials such as organic luminophores, carbon dots (CDs), organic-inorganic nanocomposites, fluorescent dye molecules, and nanoparticles (NPs). These AIE-active materials, or AIEgens, are ideal for balancing multifunctional phototheranostics and energy dissipation. AIE properties can manifest in organic fluorescent probes, rendering them effective for cancer treatment due to their ability to penetrate deeply and provide high therapeutic efficacy. This efficacy is attributed to their high photobleaching thresholds, ability to induce Stokes shifts, and capacity to activate fluorophores. Therefore, the development of innovative AIE-based materials for disease diagnosis and treatment, particularly for cancer, is both important and promising. Recent years have seen successful demonstrations of nanoparticles with AIE properties being used for photodynamic therapy (PDT) and multimodal imaging of tumor cells. These fluorophores have been shown to impact mitochondria and lysosomes, generate reactive oxygen species (ROS), activate the immune system, load and release drugs, and ultimately induce apoptosis in tumor cells. In this review, we examine previous studies on the manufacturing methods and effects of AIEgens on cancer cells, with a theranostic strategy of simultaneous treatment and imaging. We also investigate the factors affecting drug delivery on different cancer cells, including internal stimuli such as pH, ROS, enzymes, and external stimuli like near-infrared (NIR) light and ultrasound waves.

Biosynthesis of fungus-based oral selenium microcarriers for radioprotection and immuno-homeostasis shaping against radiation-induced heart disease

Radiation-induced heart disease (RIHD), characterized by severe oxidative stress and immune dysregulation, is a serious condition affecting cancer patients undergoing thoracic radiation. Unfortunately, clinical interventions for RIHD are lacking. Selenium (Se) is a trace element with excellent antioxidant and immune-modulatory properties. However, its application in heart radioprotection remains challenging. Herein, we developed a novel bioactive Cordyceps militaris-based Se oral delivery system (Se@CM), which demonstrated superior radioprotection effects in vitro against X-ray-induced damage in H9C2 cells through suppressing excessive ROS generation, compared to the radioprotectant Amifostine. Moreover, Se@CM exhibited exceptional cardioprotective effects in vivo against X-ray irradiation, reducing cardiac dysfunction and myocardial fibrosis by balancing the redox equilibrium and modulating the expression of Mn-SOD and MDA. Additionally, Se@CM maintained immuno-homeostasis, as evidenced by the upregulated population of T cells and M2 macrophages through modulation of selenoprotein expression after irradiation. Together, these results highlight the remarkable antioxidant and immunity modulation properties of Se@CM and shed light on its promising application for cardiac protection against IR-induced disease. This research provides valuable insights into developing effective strategies for preventing and managing RIHD.

Clinical application of immunogenic cell death inducers in cancer immunotherapy: turning cold tumors hot

Immunotherapy has emerged as a promising cancer treatment option in recent years. In immune "hot" tumors, characterized by abundant immune cell infiltration, immunotherapy can improve patients' prognosis by activating the function of immune cells. By contrast, immune "cold" tumors are often less sensitive to immunotherapy owing to low immunogenicity of tumor cells, an immune inhibitory tumor microenvironment, and a series of immune-escape mechanisms. Immunogenic cell death (ICD) is a promising cellular process to facilitate the transformation of immune "cold" tumors to immune "hot" tumors by eliciting innate and adaptive immune responses through the release of (or exposure to) damage-related molecular patterns. Accumulating evidence suggests that various traditional therapies can induce ICD, including chemotherapy, targeted therapy, radiotherapy, and photodynamic therapy. In this review, we summarize the biological mechanisms and hallmarks of ICD and introduce some newly discovered and technologically innovative inducers that activate the immune system at the molecular level. Furthermore, we also discuss the clinical applications of combing ICD inducers with cancer immunotherapy. This review will provide valuable insights into the future development of ICD-related combination therapeutics and potential management for "cold" tumors.

Advancements in Stimulus-Responsive Co-Delivery Nanocarriers for Enhanced Cancer Immunotherapy

Cancer immunotherapy has emerged as a novel therapeutic approach against tumors, with immune checkpoint inhibitors (ICIs) making significant clinical practice. The traditional ICIs, PD-1 and PD-L1, augment the cytotoxic function of T cells through the inhibition of tumor immune evasion pathways, ultimately leading to the initiation of an antitumor immune response. However, the clinical implementation of ICIs encounters obstacles stemming from the existence of an immunosuppressive tumor microenvironment and inadequate infiltration of CD8+T cells. Considerable attention has been directed towards advancing immunogenic cell death (ICD) as a potential solution to counteract tumor cell infiltration and the immunosuppressive tumor microenvironment. This approach holds promise in transforming "cold" tumors into "hot" tumors that exhibit responsiveness to antitumor. By combining ICD with ICIs, a synergistic immune response against tumors can be achieved. However, the combination of ICD inducers and PD-1/PD-L1 inhibitors is hindered by issues such as poor targeting and uncontrolled drug release. An advantageous solution presented by stimulus-responsive nanocarrier is integrating the physicochemical properties of ICD inducers and PD-1/PD-L1 inhibitors, facilitating precise delivery to specific tissues for optimal combination therapy. Moreover, these nanocarriers leverage the distinct features of the tumor microenvironment to accomplish controlled drug release and regulate the kinetics of drug delivery. This article aims to investigate the advancement of stimulus-responsive co-delivery nanocarriers utilizing ICD and PD-1/PD-L1 inhibitors. Special focus is dedicated to exploring the advantages and recent advancements of this system in enabling the combination of ICIs and ICD inducers. The molecular mechanisms of ICD and ICIs are concisely summarized. In conclusion, we examine the potential research prospects and challenges that could greatly enhance immunotherapeutic approaches for cancer treatment.

Recent advances of aggregation‐induced emission in body surface organs

The surface organs mainly comprise the superficial layers of various parts of the mammalian body, including the skin, eyes, and ears, which provide solid protection against various threats to the entire body. Damage to surface organs could lead to many serious diseases or even death. Currently, despite significant advancements in this field, there remain numerous enigmas that necessitate expeditious resolution, particularly pertaining to diagnostic and therapeutic objectives. The advancements in nanomedicine have provided a significant impetus for the development of novel approaches in the diagnosis, bioimaging, and therapy of superficial organs. The aggregation‐induced emission (AIE) phenomenon, initially observed by Prof. Ben Zhong Tang, stands out due to its contrasting behavior to the aggregation‐caused quenching effect. This discovery has significantly revolutionized the field of nanomedicine for surface organs owing to its remarkable advantages. In this review of literature, we aim to provide a comprehensive summary of recent advances of AIE lumenogen (AIEgen)‐based nanoplatforms in the fields of detection, diagnosis, imaging, and therapeutics of surface organ‐related diseases and discuss their prospects in the domain. It is hoped that this review will help attract researchers’ attention toward the utilization of this field for the exploration of a wider range of biomedical and clinical applications.

Doxorubicin-Loaded Microalgal Delivery System for Combined Chemotherapy and Enhanced Photodynamic Therapy of Osteosarcoma

Osteosarcoma (OS) is considered the most frequent type of primary malignant bone tumor. Currently, radiotherapy, photodynamic (PDT), and other therapies for osteosarcoma are limited by tumor hypoxia and single efficacy and serve side-effects. Herein, we reported a microalgal drug delivery system (SpiD), doxorubicin (DOX)-loaded Spirulina platensis (Spi) for OS therapy. The specific surface of Spirulina platensis allowed for effective loading of DOX via surface channels and electrostatic interactions. Under 650 nm laser irradiation, SpiD enabled high oxygen production by photosynthesis and enhanced reactive oxygen species (ROS) generation via chlorophyll-assisted photosensitization, synergistically killing tumor cells with the released DOX. Combined chemotherapy and enhanced PDT mediated by SpiD exerted synergic antitumor effects and resulted in potent therapeutic efficacy in orthotopic osteosarcoma mice. Furthermore, SpiD could reduce the side-effects of chemotherapy, showing excellent blood and tissue safety. Taken together, this microalgal drug delivery system provided a natural, efficient, safe, and inexpensive strategy for OS treatment.

Salmonella enterica and outer membrane vesicles are current and future options for cancer treatment

Conventional cancer therapies have many limitations. In the last decade, it has been suggested that bacteria-mediated immunotherapy may circumvent the restrictions of traditional treatments. For example, Salmonella enterica is the most promising bacteria for treating cancer due to its intrinsic abilities, such as killing tumor cells, targeting, penetrating, and proliferating into the tumor. S. enterica has been genetically modified to ensure safety and increase its intrinsic antitumor efficacy. This bacterium has been used as a vector for delivering anticancer agents and as a combination therapy with chemotherapy, radiotherapy, or photothermic. Recent studies have reported the antitumor efficacy of outer membrane vesicles (OMVs) derived from S. enterica. OMVs are considered safer than attenuated bacteria and can stimulate the immune system as they comprise most of the immunogens found on the surface of their parent bacteria. Furthermore, OMVs can also be used as nanocarriers for antitumor agents. This review describes the advances in S. enterica as immunotherapy against cancer and the mechanisms by which Salmonella fights cancer. We also highlight the use of OMVs as immunotherapy and nanocarriers of anticancer agents. OMVs derived from S. enterica are innovative and promising strategies requiring further investigation.