Remodeling Macrophages by an Iron Nanotrap for Tumor Growth Suppression

Acidity-responsive polyphenol-coordinated nanovaccines for improving tumor immunotherapy via bidirectional reshaping of the immunosuppressive microenvironment and controllable release of antigens

The tumor immunosuppressive microenvironment (TIME) and uncontrollable release of antigens can lower the efficacy of nanovaccine-based immunotherapy (NBI). Therefore, it is necessary to develop a new strategy for TIME reshaping and controllable release of antigens to improve the NBI efficacy. Herein, an acidity-responsive Schiff base-conjugated polyphenol-coordinated nanovaccine was constructed for the first time to realize bidirectional TIME reshaping and controllable release of antigens for activating T cells. In particular, an acidity-responsive tannic acid-ovalbumin (TA-OVA) nanoconjugate was prepared via a Schiff base reaction. FeIII was coordinated with TA-OVA to produce a FeIII-TA-OVA nanosystem, and 1-methyltryptophan (1-MT) as an indoleamine 2,3-dioxygenase inhibitor was loaded to form a polyphenol-coordinated nanovaccine. The coordination between FeIII and TA could cause photothermal ablation of primary tumors, and the acidity-triggered Schiff base dissociation of TA-OVA could controllably release OVA to realize lysosome escape, initiating the body's immune response. More importantly, oxidative stress generated by a tumor-specific Fenton reaction of Fe ions could promote the polarization of tumor-associated macrophages from the M2 to M1 phenotype, resulting in the upregulation of cytotoxic T cells and helper T cells. Meanwhile, 1-MT could downregulate immunosuppressive regulatory T cells. Overall, such skillful combination of bidirectional TIME reshaping and controllable antigen release into one coordination nanosystem could effectively enhance the NBI efficacy of tumors.

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.

Single-Atom Catalysts Mediated Bioorthogonal Modulation of N6-Methyladenosine Methylation for Boosting Cancer Immunotherapy

Bioorthogonal reactions provide a powerful tool to manipulate biological processes in their native environment. However, the transition-metal catalysts (TMCs) for bioorthogonal catalysis are limited to low atomic utilization and moderate catalytic efficiency, resulting in unsatisfactory performance in a complex physiological environment. Herein, sulfur-doped Fe single-atom catalysts with atomically dispersed and uniform active sites are fabricated to serve as potent bioorthogonal catalysts (denoted as Fe-SA), which provide a powerful tool for in situ manipulation of cellular biological processes. As a proof of concept, the N6-methyladensoine (m6A) methylation in macrophages is selectively regulated by the mannose-modified Fe-SA nanocatalysts (denoted as Fe-SA@Man NCs) for potent cancer immunotherapy. Particularly, the agonist prodrug of m6A writer METTL3/14 complex protein (pro-MPCH) can be activated in situ by tumor-associated macrophage (TAM)-targeting Fe-SA@Man, which can upregulate METTL3/14 complex protein expression and then reprogram TAMs for tumor killing by hypermethylation of m6A modification. Additionally, we find the NCs exhibit an oxidase (OXD)-like activity that further boosts the upregulation of m6A methylation and the polarization of macrophages via producing reactive oxygen species (ROS). Ultimately, the reprogrammed M1 macrophages can elicit immune responses and inhibit tumor proliferation. Our study not only sheds light on the design of single-atom catalysts for potent bioorthogonal catalysis but also provides new insights into the spatiotemporal modulation of m6A RNA methylation for the treatment of various diseases.

Tumor Microenvironment-Activatable Nanosystem Capable of Overcoming Multiple Therapeutic Obstacles for Augmenting Immuno/Metal-Ion Therapy

Abnormal tumor microenvironment (TME) imposes barriers to nanomedicine penetration into tumors and evolves tumor-supportive nature to provide tumor cell protection, seriously weakening the action of antitumor nanomedicines and posing significant challenges to their development. Here, we engineer a TME-activatable size-switchable core-satellite nanosystem (Mn-TI-Ag@HA) capable of increasing the effective dose of therapeutic agents in deep-seated tumors while reversing tumor-supportive microenvironment for augmenting immuno/metal-ion therapy. When activated by TME, the nanosystem disintegrates, allowing ultrasmall-sized Ag nanoparticles to become unbound and penetrate deep into solid tumors. Simultaneously, the nanosystem produces O2 and releases TGF-β inhibitors in situ to drive macrophage M2-to-M1 polarization, increasing intratumoral H2O2 concentration, and ultimately augmenting metal-ion therapy by accelerating hypertoxic Ag+ production. The nanosystem can overcome multiple obstacles that aid in tumor resistance to nanomedicine, demonstrating effective tumor penetration, TME regulation, and tumor inhibition effects. It can provoke long-term immunological memory effects against tumor rechallenge when combined with immune checkpoint inhibitor anti-PD-1. This work provides a paradigm for designing efficient antitumor nanomedicines.

Fabrication of highly luminescent and thermally stable composites of sulfur nanodots through surface modification and assembly

Sulfur nanodots (S-dots) have emerged as a promising luminescent material to excel over traditional heavy metal-based quantum dots. However, their relatively low emission efficiency and poor thermal stability in the solid state have limited their wide applications in photoelectric devices. In this work, highly luminescent, with a photoluminescence quantum yield higher than 50%, and thermally stable composites of S-dots were produced through modulating their surface states and aggregation behaviors by introducing pyromellitic dianhydride (PMDA) and benzoyleneurea (BEU), respectively. PMDA eliminated the relatively short-lived surface states and defects on the surface of S-dots and BEU regulated the aggregation states and facilitated the energy transfer from BEU to S-dots. The as-obtained composites also showed significantly improved thermal stability compared to S-dots, aided by the hydrophobic chemical groups and dense matrix of PMDA and BEU, which extended their applications in fabricating light-emitting diodes. Our presented results provide a new approach to produce highly luminescent S-dots, which widen their applications in the fields of bioimaging, sensing, photoelectric devices, and environmental science.

Crosstalk between ferroptosis and macrophages: potential value for targeted treatment in diseases

Ferroptosis is a newly identified form of programmed cell death that is connected to iron-dependent lipid peroxidization. It involves a variety of physiological processes involving iron metabolism, lipid metabolism, oxidative stress, and biosynthesis of nicotinamide adenine dinucleotide phosphate, glutathione, and coenzyme Q10. So far, it has been discovered to contribute to the pathological process of many diseases, such as myocardial infarction, acute kidney injury, atherosclerosis, and so on. Macrophages are innate immune system cells that regulate metabolism, phagocytize pathogens and dead cells, mediate inflammatory reactions, promote tissue repair, etc. Emerging evidence shows strong associations between macrophages and ferroptosis, which can provide us with a deeper comprehension of the pathological process of diseases and new targets for the treatments. In this review, we summarized the crosstalk between macrophages and ferroptosis and anatomized the application of this association in disease treatments, both non-neoplastic and neoplastic diseases. In addition, we have also addressed problems that remain to be investigated, in the hope of inspiring novel therapeutic strategies for diseases.

Recent Advances in Cancer Immunotherapy Delivery Modalities

Immunotherapy is crucial in fighting cancer and achieving successful remission. Many novel strategies have recently developed, but there are still some obstacles to overcome before we can effectively attack the cancer cells and decimate the cancer environment by inducing a cascade of immune responses. To successfully demonstrate antitumor activity, immune cells must be delivered to cancer cells and exposed to the immune system. Such cutting-edge technology necessitates meticulously designed delivery methods with no loss or superior homing onto cancer environments, as well as high therapeutic efficacy and fewer adverse events. In this paper, we discuss recent advances in cancer immunotherapy delivery techniques, as well as their future prospects.

Metal ions and nanometallic materials in antitumor immunity: Function, application, and perspective

The slightest change in the extra/intracellular concentration of metal ions results in amplified effects by signaling cascades that regulate both cell fate within the tumor microenvironment and immune status, which influences the network of antitumor immunity through various pathways. Based on the fact that metal ions influence the fate of cancer cells and participate in both innate and adaptive immunity, they are widely applied in antitumor therapy as immune modulators. Moreover, nanomedicine possesses the advantage of precise delivery and responsive release, which can perfectly remedy the drawbacks of metal ions, such as low target selectivity and systematic toxicity, thus providing an ideal platform for metal ion application in cancer treatment. Emerging evidence has shown that immunotherapy applied with nanometallic materials may significantly enhance therapeutic efficacy. Here, we focus on the physiopathology of metal ions in tumorigenesis and discuss several breakthroughs regarding the use of nanometallic materials in antitumor immunotherapeutics. These findings demonstrate the prominence of metal ion-based nanomedicine in cancer therapy and prophylaxis, providing many new ideas for basic immunity research and clinical application. Consequently, we provide innovative insights into the comprehensive understanding of the application of metal ions combined with nanomedicine in cancer immunotherapy in the past few years.

Macrophages: From Simple Phagocyte to an Integrative Regulatory Cell for Inflammation and Tissue Regeneration-A Review of the Literature

The understanding of macrophages and their pathophysiological role has dramatically changed within the last decades. Macrophages represent a very interesting cell type with regard to biomaterial-based tissue engineering and regeneration. In this context, macrophages play a crucial role in the biocompatibility and degradation of implanted biomaterials. Furthermore, a better understanding of the functionality of macrophages opens perspectives for potential guidance and modulation to turn inflammation into regeneration. Such knowledge may help to improve not only the biocompatibility of scaffold materials but also the integration, maturation, and preservation of scaffold-cell constructs or induce regeneration. Nowadays, macrophages are classified into two subpopulations, the classically activated macrophages (M1 macrophages) with pro-inflammatory properties and the alternatively activated macrophages (M2 macrophages) with anti-inflammatory properties. The present narrative review gives an overview of the different functions of macrophages and summarizes the recent state of knowledge regarding different types of macrophages and their functions, with special emphasis on tissue engineering and tissue regeneration.

A theranostic metallodrug modulates immunovascular crosstalk to combat immunosuppressive liver cancer

Hepatocellular carcinoma (HCC) is a highly malignant, fatal disease with a complex tumor microenvironment (TME) characterized by severe immunosuppression and malformed vascular structures, thus most advanced HCC patients do not respond well to current mainstream pharmacotherapy and T-cell-related immunotherapy. Therefore, an efficient immunovascular crosstalk modulation strategy may help combat HCC by reversing immunosuppression and vessel normalization, especially by reprogramming tumor associated macrophages (TAMs). In this study, tyrosine kinase inhibitor lenvatinib (Len) was loaded into mesoporous Fe₃O₄ (mFe) nanoparticles (NPs), and bovine serum albumin (BSA) was attached to the NP surface to produce a metallodrug (BSA-mFe@Len NPs). In acidic TME, BSA allowed pH-responsive Len release and mFe exposure. Len directly triggered HCC apoptosis and changed the abnormal TME via vessel normalization, cytotoxic T-lymphocyte recruitment, and regulatory T-cell elimination at tailored dosages. After TAM phagocytosis, mFe NPs reprogrammed TAMs into M1 phenotypes to synergistically amplify antitumor immunity. The metallodrug achieved significant tumor growth inhibition, induced tumor vessel normalization effects, and acquired instant antitumor immunity as well as long-term immune memory in vivo. Furthermore, it displayed good T₂ weighted magnetic resonance imaging performance, indicating potential theranostic applications. Collectively, this research provides new insights for unleashing the multifaceted potential of current pharmaceuticals in synergy with metallic nanomedicine for treating intractable liver cancer. STATEMENT OF SIGNIFICANCE: Current pharmacotherapy and immunotherapy have limited success in treating advanced hepatocellular carcinoma (HCC) due to its complex tumor microenvironment (TME). Hence, this work first put forward a theranostic metallodrug by loading lenvatinib (Len) into mesoporous Fe₃O₄ (mFe) nanoparticles (NPs) and coating a pH-degradable bovine serum albumin corona onto the surface. The metallodrug was able to modulate immunovascular TME for combating HCC via metalloimmunotherapy induced by the mFe NPs and Len's multiple functions (direct triggering of tumor apoptosis, vessel normalization, cytotoxic T-lymphocyte recruitment, and regulatory T-cell elimination). In vivo experiments showed that the metallodrug could significantly inhibit HCC growth and evoke long-term antitumor immune memory, paving a new avenue for treating advanced HCC patients.

Functional 2D Iron-Based Nanosheets for Synergistic Immunotherapy, Phototherapy, and Chemotherapy of Tumor

Immunotherapy efficacy has been limited by tumor-associated macrophages (TAMs), which are the most abundant immune regulatory cells infiltrating around tumor tissues. The repolarization of pro-tumor M2 TAMs to anti-tumor M1 TAMs is a very promising immunotherapeutic strategy for cancer therapy. In this manuscript, multifunctional 2D iron-based nanosheets (FeNSs) are synthesized via a simple hydrothermal method for the first time, which not only possess photothermal and photodynamic properties, but also can repolarize TAMs from M2 to M1. After modifying with polyethylene glycol and loading with bioreductive prodrug banoxantrone (AQ4N), abbreviated as _AP FeNSs, it can effectively repolarize TAMs from M2 to M1 and deliver AQ4N to tumor microenvironment (TME). Moreover, the repolarized M1 TAMs overexpress inducible nitric oxide synthase, which can convert nontoxic AQ4N to cytotoxic AQ4 under hypoxic TME, enabling immunomodulation-activated chemotherapy. A series of in vitro and in vivo results corroborate that _AP FeNSs effectively exert photothermal and photodynamic effects and repolarize M2 TAMs to M1 TAMs, releasing inflammatory factors and activating the chemotherapeutic effect, thereby realizing synergistic tumor therapy.

Nanoparticle-Based Drug Delivery Systems Targeting Tumor Microenvironment for Cancer Immunotherapy Resistance: Current Advances and Applications

Cancer immunotherapy has shown impressive anti-tumor activity in patients with advanced and early-stage malignant tumors, thus improving long-term survival. However, current cancer immunotherapy is limited by barriers such as low tumor specificity, poor response rate, and systemic toxicities, which result in the development of primary, adaptive, or acquired resistance. Immunotherapy resistance has complex mechanisms that depend on the interaction between tumor cells and the tumor microenvironment (TME). Therefore, targeting TME has recently received attention as a feasibility strategy for re-sensitizing resistant neoplastic niches to existing cancer immunotherapy. With the development of nanotechnology, nanoplatforms possess outstanding features, including high loading capacity, tunable porosity, and specific targeting to the desired locus. Therefore, nanoplatforms can significantly improve the effectiveness of immunotherapy while reducing its toxic and side effects on non-target cells that receive intense attention in cancer immunotherapy. This review explores the mechanisms of tumor microenvironment reprogramming in immunotherapy resistance, including TAMs, CAFs, vasculature, and hypoxia. We also examined whether the application of nano-drugs combined with current regimens is improving immunotherapy clinical outcomes in solid tumors.

Nanoparticles mediated tumor microenvironment modulation: current advances and applications

The tumor microenvironment (TME) plays a key role in cancer development and emergence of drug resistance. TME modulation has recently garnered attention as a potential approach for reprogramming the TME and resensitizing resistant neoplastic niches to existing cancer therapies such as immunotherapy or chemotherapy. Nano-based solutions have important advantages over traditional platform and can be specifically targeted and delivered to desired sites. This review explores novel nano-based approaches aimed at targeting and reprogramming aberrant TME components such as macrophages, fibroblasts, tumor vasculature, hypoxia and ROS pathways. We also discuss how nanoplatforms can be combined with existing anti-tumor regimens such as radiotherapy, immunotherapy, phototherapy or chemotherapy to enhance clinical outcomes in solid tumors.