TLR7/8-agonist-loaded nanoparticles promote the polarization of tumour-associated macrophages to enhance cancer immunotherapy

Sustained release of drug-loaded nanoparticles from injectable hydrogels enables long-term control of macrophage phenotype

Injectable hydrogels may be pre-formed through dynamic crosslinks, allowing for injection and subsequent retention in the tissue by shear-thinning and self-healing processes, respectively. These properties enable the site-specific delivery of encapsulated therapeutics; yet, the sustained release of small-molecule drugs and their cell-targeted delivery remains challenging due to their rapid diffusive release and non-specific cellular biodistribution. Herein, we develop an injectable hydrogel system composed of a macrophage-targeted nanoparticle (cyclodextrin nanoparticles, CDNPs) crosslinked by adamantane-modified hyaluronic acid (Ad-HA). The polymer-nanoparticle hydrogel uniquely leverages cyclodextrin's interaction with small molecule drugs to create a spatially discrete drug reservoir and with adamantane to yield dynamic, injectable hydrogels. Through an innovative two-step drug screening approach and examination of 45 immunomodulatory drugs with subsequent in-depth transcriptional profiling of both murine and human macrophages, we identify celastrol as a potent inhibitor of pro-inflammatory (M1-like) behavior that furthermore promotes a reparatory (M2-like) phenotype. Celastrol encapsulation within the polymer-nanoparticle hydrogels permitted shear-thinning injection and sustained release of drug-laden nanoparticles that targeted macrophages to modulate cell behavior for greater than two weeks in vitro. The modular hydrogel system is a promising approach to locally modulate cell-specific phenotype in a range of applications for immunoregenerative medicine.

The role of toll-like receptors (TLRs) in pan-cancer

BACKGROUND

Toll-like receptors (TLRs) are important components of the innate and adaptive immune systems, and abnormal TLR expression has been linked to a variety of cancers. However, there was a lack of clarity on the association of TLR stimulation with the carcinogenesis of cancer. The study's goal was to analyse the clinical importance of TLRs expression at the mRNA level in pan-cancer datasets, as well as the link between TLR expression and carcinogenesis, progression, and clinical prognosis.

METHODS

The expression profile of TLRs derived from UCSC pan-cancer data was analysed in multiple dimensions, including clinical analysis, immunological subtype analysis, tumour microenvironment (TME) analysis, tumour stem cell correlation analysis, and drug sensitivity analysis. Additionally, we analyse protein-protein interactions, functional enrichment, and chromatin accessibility, as well as TLR expression in single-cell sequencing data.

RESULTS

Our multi-omics analysis results imply that TLRs may operate as a biological marker for carcinogenesis and progression, a potential target for anti-tumour therapy, and a prognostic biomarker, laying the theoretical groundwork for future translational medicine research.

CONCLUSION

TLRs are involved in the formation of malignancies and can be explored in further detail as potential prognostic indicators. Key MessagesToll-like receptors (TLRs) are key factors in the process of the innate and adaptive immune response, and their aberrant expression of TLRs have been widely reported in various cancer. However, the association between TLRs stimulation and tumorigenesis of cancer has not been well clarified.In this study, in the pan-cancer data, integrated TLR family gene expression analysis, clinical correlation analysis, immune subtype correlation analysis, tumour microenvironment correlation analysis, tumour stem cell correlation analysis, and drug sensitivity correlation analysis were performed.TLRs play an important role in the development of tumours and can be studied in depth as potential prognostic markers.

Biophysical heterogeneity of myeloid-derived microenvironment to regulate resistance to cancer immunotherapy

Despite the advances in immunotherapy for cancer treatment, patients still obtain limited benefits, mostly owing to unrestrained tumour self-expansion and immune evasion that exploits immunoregulatory mechanisms. Traditionally, myeloid cells have a dominantly immunosuppressive role. However, the complicated populations of the myeloid cells and their multilateral interactions with tumour/stromal/lymphoid cells and physical abnormalities in the tumour microenvironment (TME) determine their heterogeneous functions in tumour development and immune response. Tumour-associated myeloid cells (TAMCs) include monocytes, tumour-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), dendritic cells (DCs), and granulocytes. Single-cell profiling revealed heterogeneous TAMCs composition, sub-types, and transcriptomic signatures across 15 human cancer types. We systematically reviewed the biophysical heterogeneity of TAMC composition and pro/anti-tumoral and immuno-suppressive/stimulating properties of myeloid-derived microenvironments. We also summarised comprehensive clinical strategies to overcome resistance to immunotherapy from three dimensions: targeting TAMCs, reversing physical abnormalities, utilising nanomedicines, and finally, put forward futuristic perspectives for scientific and clinical research.

Macrophage Reprogramming with Anti-miR223-Loaded Artificial Protocells Enhances In Vivo Cancer Therapeutic Potential

Several immune cell-expressed miRNAs (miRs) are associated with altered prognostic outcome in cancer patients, suggesting that they may be potential targets for development of cancer therapies. Here, translucent zebrafish (Danio rerio) is utilized to demonstrate that genetic knockout or knockdown of one such miR, microRNA-223 (miR223), globally or specifically in leukocytes, does indeed lead to reduced cancer progression. As a first step toward potential translation to a clinical therapy, a novel strategy is described for reprogramming neutrophils and macrophages utilizing miniature artificial protocells (PCs) to deliver anti-miRs against the anti-inflammatory miR223. Using genetic and live imaging approaches, it is shown that phagocytic uptake of anti-miR223-loaded PCs by leukocytes in zebrafish (and by human macrophages in vitro) effectively prolongs their pro-inflammatory state by blocking the suppression of pro-inflammatory cytokines, which, in turn, drives altered immune cell-cancer cell interactions and ultimately leads to a reduced cancer burden by driving reduced proliferation and increased cell death of tumor cells. This PC cargo delivery strategy for reprogramming leukocytes toward beneficial phenotypes has implications also for treating other systemic or local immune-mediated pathologies.

Targeted Cancer Immunotherapy: Nanoformulation Engineering and Clinical Translation

With the rapid growth of advanced nanoengineering strategies, there are great implications for therapeutic immunostimulators formulated in nanomaterials to combat cancer. It is crucial to direct immunostimulators to the right tissue and specific immune cells at the right time, thereby orchestrating the desired, potent, and durable immune response against cancer. The flexibility of nanoformulations in size, topology, softness, and multifunctionality allows precise regulation of nano-immunological activities for enhanced therapeutic effect. To grasp the modulation of immune response, research efforts are needed to understand the interactions of immune cells at lymph organs and tumor tissues, where the nanoformulations guide the immunostimulators to function on tissue specific subsets of immune cells. In this review, recent advanced nanoformulations targeting specific subset of immune cells, such as dendritic cells (DCs), T cells, monocytes, macrophages, and natural killer (NK) cells are summarized and discussed, and clinical development of nano-paradigms for targeted cancer immunotherapy is highlighted. Here the focus is on the targeting nanoformulations that can passively or actively target certain immune cells by overcoming the physiobiological barriers, instead of directly injecting into tissues. The opportunities and remaining obstacles for the clinical translation of immune cell targeting nanoformulations in cancer therapy are also discussed.

Cytokine Therapy Combined with Nanomaterials Participates in Cancer Immunotherapy

Immunotherapy has gradually become an emerging treatment modality for tumors after surgery, radiotherapy, and chemotherapy. Cytokine therapy is a promising treatment for cancer immunotherapy. Currently, there are many preclinical theoretical bases to support this treatment strategy and a variety of cytokines in clinical trials. When cytokines were applied to tumor immunotherapy, it was found that the efficacy was not satisfactory. As research on tumor immunity has deepened, the role of cytokines in the tumor microenvironment has been further explored. Meanwhile, the study of nanomaterials in drug delivery has been fully developed in the past 20 years. Researchers have begun to think about the possibility of combining cytokine therapy with nanomaterials. Herein, we briefly review various nano-delivery systems that can directly deliver cytokines or regulate the expression of cytokines in tumor cells for cancer immunotherapy. We further discussed the feasibility of the combination of various therapies. We looked forward to the main challenges, opportunities, and prospects of tumor immunotherapy with multiple cytokines and a nano-delivery system.

Toll-like receptor-targeted anti-tumor therapies: Advances and challenges

Toll-like receptors (TLRs) are pattern recognition receptors, originally discovered to stimulate innate immune reactions against microbial infection. TLRs also play essential roles in bridging the innate and adaptive immune system, playing multiple roles in inflammation, autoimmune diseases, and cancer. Thanks to the immune stimulatory potential of TLRs, TLR-targeted strategies in cancer treatment have proved to be able to regulate the tumor microenvironment towards tumoricidal phenotypes. Quantities of pre-clinical studies and clinical trials using TLR-targeted strategies in treating cancer have been initiated, with some drugs already becoming part of standard care. Here we review the structure, ligand, signaling pathways, and expression of TLRs; we then provide an overview of the pre-clinical studies and an updated clinical trial watch targeting each TLR in cancer treatment; and finally, we discuss the challenges and prospects of TLR-targeted therapy.

Development of functional nanomedicines for tumor associated macrophages-focused cancer immunotherapy

Clinical cancer immunotherapies are usually impeded by tumor immunosuppression driven by tumor associated macrophages (TAMs). Thus, TAMs can be considered as a promising therapeutic target for improved immunotherapy, and TAMs-focused molecular targeting agents have made ideal progress in clinical practice. Even so, most TAMs-targeting agents still cannot cover up their own shortcomings as free drugs. The emergence of multifunctional nanomaterials can expectedly endow these therapeutic cargoes with high solubility, favorable pharmacokinetic distribution, cell-specific delivery, and controlled release. Here, the underlying mechanisms of tumor immunosuppression caused by TAMs are first emphatically elucidated, and then the basic design of TAMs-focused immune-nanomedicines are discussed, mainly including diverse categories of nanomaterials, targeted and stimulus-responsive modifications, and TAM imaging in nanomedicines. A summary of current TAMs-targeting immunotherapeutic mechanisms based on functional nanomedicines for TAMs elimination and/or repolarization is further presented. Lastly, some severe challenges related to functional nanomedicines for TAMs-focused cancer immunotherapy are proposed, and some feasible perspectives on clinical translation of TAMs-associated anticancer immunonanomedicines are provided. It is hoped that, with rapid development of nanomedicine in cancer immunotherapy, TAMs-focused therapeutic strategies may be anticipated to become an emerging immunotherapeutic modality for future clinical cancer treatment.

TAM-targeted reeducation for enhanced cancer immunotherapy: Mechanism and recent progress

Tumor-associated macrophage (TAM) as an important component of tumor microenvironment (TME) are closely related with the occurrence, development, and metastasis of malignant tumors. TAMs are generally identified as two distinct functional populations in TME, i.e., inflammatory/anti-tumorigenic (M1) and regenerative/pro-tumorigenic (M2) phenotype. Evidence suggests that occupation of the TME by M2-TAMs is closely related to the inactivation of anti-tumor immune cells such as T cells in TME. Recently, efforts have been made to reeducate TAMs from M2- to M1- phenotype to enhance cancer immunotherapy, and great progress has been made in realizing efficient modulation of TAMs using nanomedicines. To help readers better understand this emerging field, the potential TAM reeducation targets for potentiating cancer immunotherapy and the underlying mechanisms are summarized in this review. Moreover, the most recent advances in utilizing nanomedicine for the TAM immunomodulation for augmented cancer immunotherapy are introduced. Finally, we conclude with our perspectives on the future development in this field.

Local immunotherapy with the RNA-based immune stimulator CV8102 induces substantial anti-tumor responses and enhances checkpoint inhibitor activity

Immunotherapy has revolutionized cancer treatment in recent years. Although currently approved checkpoint inhibitors (CPIs) yield remarkable anti-tumoral responses in several cancer types, a substantial proportion of patients do not benefit from such therapies. Local activation of innate immune signaling pathways is a promising approach to overcome the immunosuppressive tumor microenvironment, induce anti-tumor immunity, and improve the efficacy of CPI therapies. Here, we assessed the mode of action and efficacy of the RNA-based innate immune stimulator CV8102 for local immunotherapy in preclinical models. Intratumoral (i.t.) administration of CV8102 activated innate immune responses in the tumor microenvironment and draining lymph nodes, resulting in a dose-dependent anti-tumoral response. Combining i.t. CV8102 with systemic anti-programmed death protein 1 (PD-1) treatment further enhanced anti-tumoral responses, inducing tumor infiltration and activation of CD8+ T cells. The resulting memory response prevented tumor growth in rechallenged animals and impaired the growth of non-injected distal tumors. Therefore, i.t. CV8102 delivery is a promising approach for local cancer immunotherapy, especially in combination with CPIs. Clinical testing of CV8102 is ongoing (NCT03291002).

Biomaterial-assisted biotherapy: A brief review of biomaterials used in drug delivery, vaccine development, gene therapy, and stem cell therapy

Biotherapy has recently become a hotspot research topic with encouraging prospects in various fields due to a wide range of treatments applications, as demonstrated in preclinical and clinical studies. However, the broad applications of biotherapy have been limited by critical challenges, including the lack of safe and efficient delivery systems and serious side effects. Due to the unique potentials of biomaterials, such as good biocompatibility and bioactive properties, biomaterial-assisted biotherapy has been demonstrated to be an attractive strategy. The biomaterial-based delivery systems possess sufficient packaging capacity and versatile functions, enabling a sustained and localized release of drugs at the target sites. Furthermore, the biomaterials can provide a niche with specific extracellular conditions for the proliferation, differentiation, attachment, and migration of stem cells, leading to tissue regeneration. In this review, the state-of-the-art studies on the applications of biomaterials in biotherapy, including drug delivery, vaccine development, gene therapy, and stem cell therapy, have been summarized. The challenges and an outlook of biomaterial-assisted biotherapies have also been discussed.

Challenging the fundamental conjectures in nanoparticle drug delivery for chemotherapy treatment of solid cancers

Nanomedicines for cancer treatment have been studied extensively over the last few decades. Yet, only five anticancer nanomedicines have received approvals from the United States Food and Drug Administration (FDA) for treating solid tumors. This drastic mismatch between effort and return calls into question the basic understanding of this field. Various viewpoints on nanomedicines have been presented regarding their potentials and inefficiencies. However, the underlying logics of nanomedicine research and its inadequate translation to the successful use in the clinic have not been thoroughly examined. Tumor-targeted drug delivery was used to understand the shortfalls of the nanomedicine field in general. The concept of tumor-targeted drug delivery by nanomedicine has been based on two conjectures: (i) increased drug delivery to tumors provides better efficacy, and (ii) decreased drug delivery to healthy organs results in fewer side effects. The clinical evidence gathered from the literature indicates that nanomedicines bearing classic chemotherapeutic drugs, such as Dox, cis-Pt, CPT and PTX, have already reached the maximum drug delivery limit to solid tumors in humans. Still, the anticancer efficacy and safety remain unchanged despite the increased tumor accumulation. Thus, it is understandable to see few nanomedicine-based formulations approved by the FDA. The examination of FDA-approved nanomedicine formulations indicates that their approvals were not based on the improved delivery to tumors but mostly on changes in dose-limiting toxicity unique to each drug. This comprehensive analysis of the fundamentals of anticancer nanomedicines is designed to provide an accurate picture of the field's underlying false conjectures, hopefully, thereby accelerating the future clinical translations of many formulations under research.

Isolating and targeting a highly active, stochastic dendritic cell subpopulation for improved immune responses

Dendritic cell (DC) activation via pathogen-associated molecular patterns (PAMPs) is critical for antigen presentation and development of adaptive immune responses, but the stochastic distribution of DC responses to PAMP signaling, especially during the initial stages of immune activation, is poorly understood. In this study, we isolate a unique DC subpopulation via preferential phagocytosis of microparticles (MPs) and characterize this subpopulation of "first responders" (FRs). We present results that show these cells (1) can be isolated and studied via both increased accumulation of the micron-sized particles and combinations of cell surface markers, (2) show increased responses to PAMPs, (3) facilitate adaptive immune responses by providing the initial paracrine signaling, and (4) can be selectively targeted by vaccines to modulate both antibody and T cell responses in vivo. This study presents insights into a temporally controlled, distinctive cell population that influences downstream immune responses. Furthermore, it demonstrates potential for improving vaccine designs via FR targeting.

Tumor-promoting myeloid cells in the pathogenesis of human oncoviruses: potential targets for immunotherapy

Oncoviruses, known as cancer-causing viruses, are typically involved in cancer progression by inhibiting tumor suppressor pathways and uncontrolled cell division. Myeloid cells are the most frequent populations recruited to the tumor microenvironment (TME) and play a critical role in cancer development and metastasis of malignant tumors. Tumor-infiltrating myeloid cells, including tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), tumor-associated dendritic cells (TADCs), and tumor-associated neutrophils (TANs) exert different states from anti-tumorigenic to pro-tumorigenic phenotypes in TME. Although their role in the anti-tumorigenic state is well introduced, their opposing roles, pro-tumorigenic activities, such as anti-inflammatory cytokine and reactive oxygen species (ROS) production, should not be ignored since they result in inflammation, tumor progression, angiogenesis, and evasion. Since the blockade of these cells had promising results against cancer progression, their inhibition might be helpful in various cancer immunotherapies. This review highlights the promoting role of tumor-associated myeloid cells (TAMCs) in the pathophysiology of human virus tumorigenesis.

Engineered nanomaterials trigger abscopal effect in immunotherapy of metastatic cancers

Despite advances in cancer treatment, metastatic cancer is still the main cause of death in cancer patients. At present, the treatment of metastatic cancer is limited to palliative care. The abscopal effect is a rare phenomenon in which shrinkage of metastatic tumors occurs simultaneously with the shrinkage of a tumor receiving localized treatment, such as local radiotherapy or immunotherapy. Immunotherapy shows promise for cancer treatment, but it also leads to consequences such as low responsiveness and immune-related adverse events. As a promising target-based approach, intravenous or intratumoral injection of nanomaterials provides new opportunities for improving cancer immunotherapy. Chemically modified nanomaterials may be able to trigger the abscopal effect by regulating immune cells. This review discusses the use of nanomaterials in killing metastatic tumor cells through the regulation of immune cells and the prospects of such nanomaterials for clinical use.

Tumor Cell-Surface Binding of Immune Stimulating Polymeric Glyco-Adjuvant via Cysteine-Reactive Pyridyl Disulfide Promotes Antitumor Immunity

Immune stimulating agents like Toll-like receptor 7 (TLR7) agonists induce potent antitumor immunity but are limited in their therapeutic window due to off-target immune activation. Here, we developed a polymeric delivery platform that binds excess unpaired cysteines on tumor cell surfaces and debris to adjuvant tumor neoantigens as an in situ vaccine. The metabolic and enzymatic dysregulation in the tumor microenvironment produces these exofacial free thiols, which can undergo efficient disulfide exchange with thiol-reactive pyridyl disulfide moieties upon intratumoral injection. These functional monomers are incorporated into a copolymer with pendant mannose groups and TLR7 agonists to target both antigen and adjuvant to antigen presenting cells. When tethered in the tumor, the polymeric glyco-adjuvant induces a robust antitumor response and prolongs survival of tumor-bearing mice, including in checkpoint-resistant B16F10 melanoma. The construct additionally reduces systemic toxicity associated with clinically relevant small molecule TLR7 agonists.

Multiplexed imaging mass cytometry reveals distinct tumor-immune microenvironments linked to immunotherapy responses in melanoma

Background

Single-cell technologies have enabled extensive analysis of complex immune composition, phenotype and interactions within tumor, which is crucial in understanding the mechanisms behind cancer progression and treatment resistance. Unfortunately, knowledge on cell phenotypes and their spatial interactions has only had limited impact on the pathological stratification of patients in the clinic so far. We explore the relationship between different tumor environments (TMEs) and response to immunotherapy by deciphering the composition and spatial relationships of different cell types.

Methods

Here we used imaging mass cytometry to simultaneously quantify 35 proteins in a spatially resolved manner on tumor tissues from 26 melanoma patients receiving anti-programmed cell death-1 (anti-PD-1) therapy. Using unsupervised clustering, we profiled 662,266 single cells to identify lymphocytes, myeloid derived monocytes, stromal and tumor cells, and characterized TME of different melanomas.

Results

Combined single-cell and spatial analysis reveals highly dynamic TMEs that are characterized with variable tumor and immune cell phenotypes and their spatial organizations in melanomas, and many of these multicellular features are associated with response to anti-PD-1 therapy. We further identify six distinct TME archetypes based on their multicellular compositions, and find that patients with different TME archetypes responded differently to anti-PD-1 therapy. Finally, we find that classifying patients based on the gene expression signature derived from TME archetypes predicts anti-PD-1 therapy response across multiple validation cohorts.

Conclusions

Our results demonstrate the utility of multiplex proteomic imaging technologies in studying complex molecular events in a spatially resolved manner for the development of new strategies for patient stratification and treatment outcome prediction.

Major pathways involved in macrophage polarization in cancer

Macrophages play an important role in tissue homeostasis, tissue remodeling, immune response, and progression of cancer. Consequently, macrophages exhibit significant plasticity and change their transcriptional profile and function in response to environmental, tissue, and inflammatory stimuli resulting in pro- and anti-tumor effects. Furthermore, the categorization of tissue macrophages in inflammatory situations remains difficult; however, there is an agreement that macrophages are predominantly polarized into two different subtypes with pro- and anti-inflammatory properties, the so-called M1-like and M2-like macrophages, respectively. These two macrophage classes can be considered as the extreme borders of a continuum of many intermediate subsets. On one end, M1 are pro-inflammatory macrophages that initiate an immunological response, damage tissue integrity, and dampen tumor progression by fostering robust T and natural killer (NK) cell anti-tumoral responses. On the other end, M2 are anti-inflammatory macrophages involved in tissue remodeling and tumor growth, that promote cancer cell proliferation, invasion, tumor metastasis, angiogenesis and that participate to immune suppression. These decisive roles in tumor progression occur through the secretion of cytokines, chemokines, growth factors, and matrix metalloproteases, as well as by the expression of immune checkpoint receptors in the case of M2 macrophages. Moreover, macrophage plasticity is supported by stimuli from the Tumor Microenvironment (TME) that are relayed to the nucleus through membrane receptors and signaling pathways that result in gene expression reprogramming in macrophages, thus giving rise to different macrophage polarization outcomes. In this review, we will focus on the main signaling pathways involved in macrophage polarization that are activated upon ligand-receptor recognition and in the presence of other immunomodulatory molecules in cancer.

Polarization of tumor-associated macrophages by TLR7/8 conjugated radiosensitive peptide hydrogel for overcoming tumor radioresistance

Radioresistance reduces the antitumor efficiency of radiotherapy and further restricts its clinical application, which is mainly caused by the aggravation of immunosuppressive tumor microenvironment (ITM). Especially tumor-associated macrophages (TAMs) usually display the tumor-promoting M2 phenotype during high-dose fractional radiotherapy mediating radiotherapy resistance. Herein, the toll like receptor agonist TLR7/8a was conjugated with radiosensitive peptide hydrogel (Smac-TLR7/8 hydrogel) to regulate TAMs repolarization from M2 type into M1 type, thus modulating the ITM and overcoming the radioresistance. The Smac-TLR7/8 hydrogel was fabricated through self-assembly with nanofibrous morphology, porous structure and excellent biocompatibility. Upon γ-ray radiation, Smac-TLR7/8 hydrogel effectively polarized the macrophages into M1 type. Notably, combined with radiotherapy, TAMs repolarization regulated by Smac-TLR7/8 hydrogel could increase tumor necrosis factor secretion, activate antitumor immune response and effectively inhibit tumor growth. Moreover, TAMs repolarization rebuilt the ITM and elicited the immunogenic phenotypes in solid tumors, thus enhanced the PD1-blockade efficacy through increasing tumor infiltrating lymphocytes (TILs) and decreasing Treg cells in two different immune activity tumor mice models. Overall, this study substantiated that recruiting and repolarization of TAMs were critical in eliciting antitumor immune response and overcoming radioresistance, thus improving the efficacy of radiotherapy and immunotherapy.

Biomimetic nanoparticles directly remodel immunosuppressive microenvironment for boosting glioblastoma immunotherapy

Glioblastoma (GBM), as a very aggressive cancer of central nervous system, is very challenging to completely cure by the conventional combination of surgical resection with radiotherapy and chemotherapy. The success of emerging immunotherapy in hot tumors has attracted considerable interest for the treatment of GBM, but the unique tumor immunosuppressive microenvironment (TIME) of GBM leads to the failure of immunotherapy. Here, we show the significant improvement of the immunotherapy efficacy of GBM by modulating the TIME through novel all-in-one biomimetic nanoparticles (i.e. CS-I/J@CM NPs). The nanoparticles consist of utrasmall Cu_2-x Se nanoparticles (NPs) with outstanding intrinsic properties (e.g., photo-responsive Fenton-like catalytic property for inducing immunogenic cell death (ICD) and alleviating the hypoxia of tumor), indoximod (IND, an inhibitor of indoleamine-2,3-dioxygenease in tumor), JQ1 (an inhibitor for reducing the expression of PD-L1 by tumor cells), and tumor cell membrane for improving the targeting capability and accumulation of nanoparticles in tumor. We reveal that these smart CS-I/J@CM NPs could drastically activate the immune responses through remodeling TIME of GBM by multiple functions. They could (1) increase M1-phenotype macrophages at tumor site by promoting the polarization of tumor-associated macrophages through the reactive oxygen species (ROS) and oxygen generated from the Fenton-like reaction between nanoparticles and H₂O₂ within tumor under NIR II irradiation; (2) decrease the infiltration of Tregs cells at tumor site through the release of IND; (3) decrease the expression of PD-L1 on tumor cells through JQ1. The notable increments of anti-tumor CD8⁺T cells in the tumor and memory T cells (T_EM) in the spleen show excellent therapy efficacy and effectively prevent the recurrence of GBM after modulation of the TIME. This work demonstrates the modulation of TIME could be a significant strategy to improve the immunotherapy of GBM and other cold tumors.

Opportunities for Nitric Oxide in Potentiating Cancer Immunotherapy

Despite nearly 30 years of development and recent highlights of nitric oxide (NO) donors and NO delivery systems in anticancer therapy, the limited understanding of exogenous NO's effects on the immune system has prevented their advancement into clinical use. In particular, the effects of exogenously delivered NO differing from that of endogenous NO has obscured how the potential and functions of NO in anticancer therapy may be estimated and exploited despite the accumulating evidence of NO's cancer therapy-potentiating effects on the immune system. After introducing their fundamentals and characteristics, this review discusses the current mechanistic understanding of NO donors and delivery systems in modulating the immunogenicity of cancer cells as well as the differentiation and functions of innate and adaptive immune cells. Lastly, the potential for the complex modulatory effects of NO with the immune system to be leveraged for therapeutic applications is discussed in the context of recent advancements in the implementation of NO delivery systems for anticancer immunotherapy applications. SIGNIFICANCE STATEMENT: Despite a 30-year history and recent highlights of nitric oxide (NO) donors and delivery systems as anticancer therapeutics, their clinical translation has been limited. Increasing evidence of the complex interactions between NO and the immune system has revealed both the potential and hurdles in their clinical translation. This review summarizes the effects of exogenous NO on cancer and immune cells in vitro and elaborates these effects in the context of recent reports exploiting NO delivery systems in vivo in cancer therapy applications.

Supramolecular engineering of cell membrane vesicles for cancer immunotherapy

The clinical translation of nanomedicines has been strongly hampered by the limitations of delivery vehicles, promoting scientists to search for novel nanocarriers. Although cell membrane-based delivery systems have attracted extensive attention, further functionalizations are urgently desired to augment their theranostic functions. We propose a cell-friendly supramolecular strategy to engineer cell membranes utilizing cyclodextrin-based host-guest molecular recognitions to fix the defects arising from chemical and genetic modifications. In this study, the supramolecular cell membrane vesicles (SCMVs) specifically accumulate in tumors, benefiting from tumor-homing capability and the enhanced permeability and retention effect. SCMVs co-delivering indocyanine green and an indoleamine 2,3-dioxygenase inhibitor effectively ablate tumors combining photodynamic therapy and immunotherapy. Driven by host-guest inclusion complexation, SCMVs successfully encapsulate resiquimod to repolarize tumor-associated macrophages into M1 phenotype, synergizing with immune checkpoint blockade therapy. This supramolecular engineering methodology based on noncovalent interactions presents a generalizable and cell-friendly tactic to develop living cell-originated nanomaterials for precise cancer therapy.

The soldiers needed to be awakened: Tumor-infiltrating immune cells

In the tumor microenvironment, tumor-infiltrating immune cells (TIICs) are a key component. Different types of TIICs play distinct roles. CD8+ T cells and natural killer (NK) cells could secrete soluble factors to hinder tumor cell growth, whereas regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) release inhibitory factors to promote tumor growth and progression. In the meantime, a growing body of evidence illustrates that the balance between pro- and anti-tumor responses of TIICs is associated with the prognosis in the tumor microenvironment. Therefore, in order to boost anti-tumor response and improve the clinical outcome of tumor patients, a variety of anti-tumor strategies for targeting TIICs based on their respective functions have been developed and obtained good treatment benefits, including mainly immune checkpoint blockade (ICB), adoptive cell therapies (ACT), chimeric antigen receptor (CAR) T cells, and various monoclonal antibodies. In recent years, the tumor-specific features of immune cells are further investigated by various methods, such as using single-cell RNA sequencing (scRNA-seq), and the results indicate that these cells have diverse phenotypes in different types of tumors and emerge inconsistent therapeutic responses. Hence, we concluded the recent advances in tumor-infiltrating immune cells, including functions, prognostic values, and various immunotherapy strategies for each immune cell in different tumors.

In Situ Programming of Nanovaccines for Lymph Node-Targeted Delivery and Cancer Immunotherapy

In situ cancer vaccines consisting of antigens and adjuvants are a promising cancer treatment modality; however, the convenient manufacture of vaccines in vivo and their efficient delivery to lymph nodes (LNs) remains a major challenge. Herein, we outline a facile approach to simultaneously achieve the in situ programming of vaccines via two synergetic nanomedicines, Tu-NP_FN and Ln-NP_R848. Tu-NP_FN (∼100 nm) generated a large number of antigens under an alternating magnetic field, and Ln-NP_R848 (∼35 nm) encapsulating adjuvant R848 captured a portion of generated antigens for the manufacture of nanovaccines in situ and LN-targeted delivery, which significantly promoted the uptake and maturation of dendritic cells to initiate potent anticancer immune responses. Notably, combined with an anti-CTLA4 antibody (aCTLA-4), this therapy completely eradicated distant tumors in some mice and exerted a long-term immune memory effect on tumor metastasis. This study provides a generalizable strategy for in situ cancer vaccination.

Intratumoral delivery of TransCon™ TLR7/8 Agonist promotes sustained anti-tumor activity and local immune cell activation while minimizing systemic cytokine induction

Background

Intratumoral (IT) delivery of toll-like receptor (TLR) agonists has shown encouraging anti-tumor benefit in preclinical and early clinical studies. However, IT delivery of TLR agonists may lead to rapid effusion from the tumor microenvironment (TME), potentially limiting the duration of local inflammation and increasing the risk of systemic adverse events.

Methods

To address these limitations, TransCon^™ TLR7/8 Agonist—an investigational sustained-release prodrug of resiquimod that uses a TransCon linker and hydrogel technology to achieve sustained and predictable IT release of resiquimod—was developed. TransCon TLR7/8 Agonist was characterized for resiquimod release in vitro and in vivo, in mice and rats, and was assessed for anti-tumor efficacy and pharmacodynamic activity in mice.

Results

Following a single IT dose, TransCon TLR7/8 Agonist mediated potent tumor growth inhibition which was associated with sustained resiquimod release over several weeks with minimal induction of systemic cytokines. TransCon TLR7/8 Agonist monotherapy promoted activation of antigen-presenting cells in the TME and tumor-draining lymph nodes, with evidence of activation and expansion of CD8⁺ T cells in the tumor-draining lymph node and TME. Combination of TransCon TLR7/8 Agonist with systemic immunotherapy further promoted anti-tumor activity in TransCon TLR7/8 Agonist-treated tumors. In a bilateral tumor setting, combination of TransCon TLR7/8 Agonist with systemic IL-2 potentiated tumor growth inhibition in both injected and non-injected tumors and conferred protection against tumor rechallenge following complete regressions.

Conclusions

Our findings show that a single dose of TransCon TLR7/8 Agonist can mediate sustained local release of resiquimod in the TME and promote potent anti-tumor effects as monotherapy and in combination with systemic immunotherapy, supporting TransCon TLR7/8 Agonist as a novel intratumoral TLR agonist for cancer therapy. A clinical trial to evaluate the safety and efficacy of TransCon TLR7/8 Agonist, as monotherapy and in combination with pembrolizumab, in cancer patients is currently ongoing (transcendIT-101; NCT04799054).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02708-6.

Clinical significance and oncogenic function of NR1H4 in clear cell renal cell carcinoma

BACKGROUND

Nuclear receptor subfamily 1 group H member 4 (NR1H4) have been reported in various cancer types, however, little is known about the clinical values and biological function in clear cell Renal cell carcinoma (ccRCC).

METHODS

The expression pattens of NR1H4 in ccRCC were investigated in clinical specimens, cell lines and publicly‑available databases. Cell Counting Kit-8 (CCK-8), colony formation, 5-ethynyl-2' -deoxyuridine (EdU), transwell and cell wound healing assays were performed to assess the biological functions of NR1H4 in 786-O ccRCC cells. Gene set enrichment analysis (GSEA), Flow Cytometry, quantitative real-time PCR (qRT-PCR), western blot and immunofluorescence were performed to explore the molecular mechanism of NR1H4 in ccRCC. We explored the early diagnostic value, prognostic value, genetic mutation and DNA methylation of NR1H4 by a comprehensive bioinformatics analysis based on the data published in the following databases: The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), Kaplan-Meier Plotter, Gene Expression Profiling Interactive Analysis (GEPIA), UNIVERSITY OF CALIFORNIA SANTA CRUZ Xena (UCSC Xena), cBio Cancer Genomics Portal, MethSurv, SurvivalMeth and The University of ALabama at Birmingham CANcer data analysis Portal (UALCAN). Its correlation with tumor-infiltrating immune cells in ccRCC was analyzed by Tumor Immune Estimation Resource 2.0 (TIMER2.0) and Tumor Immune System Interactions Database (TISIDB).

RESULTS

In this study, NR1H4 was found to be highly expressed in ccRCC tissues and ccRCC cell lines. Knockdown of NR1H4 significantly suppressed cancer cell proliferation, migration and invasion. Mechanistically, tumor-associated signaling pathways were enriched in the NR1H4 overexpression group and si-NR1H4 could induce the downregulation of Cyclin E2 (CCNE2). By bioinformatics analysis, NR1H4 was identified as highly expressed in stage I ccRCC with a high diagnostic accuracy (area under the receiver operating characteristic curve > 0.8). Genetic alteration and DNA methylation of NR1H4 were significantly associated with prognosis in ccRCC patients. Moreover, NR1H4 expression associated with immune cell infiltration levels in ccRCC, which provides a new idea for immunotherapy.

CONCLUSIONS

Our study indicated that NR1H4 might be a potential tumor biomarker and therapeutic target for ccRCC which could promote cancer cell proliferation, migration and invasion via regulating CCNE2.

Tissue-adhesive hydrogel for multimodal drug release to immune cells in skin

Both innate and adaptive immune systems play a crucial role in the pathology of skin diseases. To control these cells, there is a need for transdermal drug delivery systems that can target multiple cell populations at independently tunable rates. Herein, we describe a tissue-adhesive hydrogel system that contains particles capable of regulating the release of small molecule drugs at defined rates. Resiquimod (a macrophage-targeting drug) and palbociclib (a T cell-targeting drug) are encapsulated within two types of silicone particles embedded within the hydrogel. We demonstrate that drug release is mediated by the crosslink density of the particles, which is decoupled from the bulk properties of the hydrogel. We show that this system can be used to sustainably polarize macrophages toward an anti-tumor phenotype in vitro and ex vivo, and that the hydrogels can remain attached to skin explants for several days without generating toxicity. The hydrogel system is compatible with standard dermatological procedures and allows transdermal passage of drugs. The multimodal, tunable nature of this system has implications in treating a variety of skin disorders, managing infections, and delivering vaccines. STATEMENT OF SIGNIFICANCE: We describe a tissue-adhesive hydrogel that can regulate the release of drugs in a manner that is decoupled from its bulk properties. The mechanism of drug release is mediated by embedded microparticles with well-defined crosslink densities. The significance of this system is that, by encapsulating different drugs into the particles, it is possible to achieve multimodal drug release. We demonstrate this capability by releasing two immunomodulatory drugs at disparate rates. A drug that targets innate immune cells is released quickly, and a drug that targets adaptive immune cells is released slowly. This programmable system offers a direct means by which cellular responses can be enhanced through independent targeting for a variety of transdermal applications, including cancer treatment and vaccine delivery.

Role of lignin-based nanoparticles in anticancer drug delivery and bioimaging: An up-to-date review

Lignin, an aromatic biopolymer, is the second most abundant naturally occurring one after cellulose that has drawn a great deal of interest over the years for its potential uses owing to the presence of high content of phenolic compounds, ecofriendly feature and cost-efficiency in comparison to the synthetic polymers. Nevertheless, with the intention of advancing its development, several efforts have been performed in the direction of utilizing lignin on the nanoscale due to its inimitable properties. The notable absorption capacity, fluorescence emission, biodegradability and non-toxicity of lignin nanoparticles permit its appropriateness as a vehicle for drugs and as a bioimaging material. Moreover, lignin nanoparticles have shown plausible therapeutic effects, such as anticancer, antimicrobial, and antioxidant. The current review sheds light on the recent development in the formulation and anticancer applications of lignin nanoparticles as a drug carrier and as a diagnostic tool. The surface properties of the nanomaterial affect the end product characteristics, hence, factors namely; lignin source, isolation technique, purification and quantitation methods, are discussed in this review. This study represents original work that has not been published elsewhere and that has not been submitted simultaneously for publication elsewhere. The manuscript has been read, revised, and approved by the authors.

Injectable Hydrogel-Based Combination Cancer Immunotherapy for Overcoming Localized Therapeutic Efficacy

Various immunotherapeutic agents that can elicit antitumor immune responses have recently been developed with the potential for improved efficacy in treating cancer. However, insufficient delivery efficiency at the tumor site, along with severe side effects after systemic administration of these anticancer agents, have hindered their therapeutic application in cancer immunotherapy. Hydrogels that can be directly injected into tumor sites have been developed to help modulate or elicit antitumor responses. Based on the biocompatibility, degradability, and controllable mechanochemical properties of these injectable hydrogels, various types of immunotherapeutic agents, such as hydrophobic anticancer drugs, cytokines, antigens, and adjuvants, have been easily and effectively encapsulated, resulting in the successful elicitation of antitumor immune responses and the retention of long-term immunotherapeutic efficacy following administration. This review summarizes recent advances in combination immunotherapy involving injectable hydrogel-based chemoimmunotherapy, photoimmunotherapy, and radioimmunotherapy. Finally, we briefly discuss the current limitations and future perspectives on injectable hydrogels for the effective combination immunotherapy of tumors.

Utility of Intravenous Curcumin Nanodelivery Systems for Improving In Vivo Pharmacokinetics and Anticancer Pharmacodynamics

Curcumin nanoformulations for intravenous injection have been developed to offset poor absorption, biotransformation, degradation, and excessive clearance associated with parenteral delivery. This review investigates (1) whether intravenous nanoformulations improve curcumin pharmacokinetics (PK) and (2) whether improved PK yields greater therapeutic efficacy. Standard PK parameters (measured maximum concentration [Cmax], area under the curve [AUC], distribution volume [Vd], and clearance [CL]) of intravenously administered free curcumin in mice and rats were sourced from literature and compared to curcumin formulated in nanoparticles, micelles, and liposomes. The studies that also featured analysis of pharmacodynamics (PD) in murine cancer models were used to determine whether improved PK of nanoencapsulated curcumin resulted in improved PD. The distribution and clearance of free and nanoformulated curcumin were very fast, typically accounting for >80% curcumin elimination from plasma within 60 min. Case-matched analysis demonstrated that curcumin nanoencapsulation generally improved curcumin PK in terms of measured Cmax (n = 27) and AUC (n = 33), and to a lesser extent Vd and CL. However, when the data were unpaired and clustered for comparative analysis, only 5 out of the 12 analyzed nanoformulations maintained a higher relative curcumin concentration in plasma over time compared to free curcumin. Quantitative analysis of the mean plasma concentration of free curcumin versus nanoformulated curcumin did not reveal an overall marked improvement in curcumin PK. No correlation was found between PK and PD, suggesting that augmentation of the systemic presence of curcumin does not necessarily lead to greater therapeutic efficacy.

New opportunities for immunomodulation of the tumour microenvironment using chemical tools

Immunotherapy is recognised as an attractive method for the treatment of cancer, and numerous treatment strategies have emerged over recent years. Investigations of the tumour microenvironment (TME) have led to the identification of many potential therapeutic targets and methods. However, many recently applied immunotherapies are based on previously identified strategies, such as boosting the immune response by combining commonly used stimulators, and the release of drugs through changes in pH. Although methodological improvements such as structural optimisation and combining strategies can be undertaken, applying those novel targets and methods in immunotherapy remains an important goal. In this review, we summarise the latest research on the TME, and discuss how small molecules, immune cells, and their interactions with tumour cells can be regulated in the TME. Additionally, the techniques currently employed for delivery of these agents to the TME are also mentioned. Strategies to modulate cell phenotypes and interactions between immune cells and tumours are mainly discussed. We consider both modulatory and targeting methods aiming to bridge the gap between the TME and chemical modulation thereof.

Nanocarrier Co-formulation for Delivery of a TLR7 Agonist plus an Immunogenic Cell Death Stimulus Triggers Effective Pancreatic Cancer Chemo-immunotherapy

Although toll-like receptor (TLR) agonists hold great promise as immune modulators for reprogramming the suppressive immune landscape in pancreatic ductal adenocarcinoma (PDAC), their use is limited by poor pharmacokinetics (PK) and off-target systemic inflammatory effects. To overcome these challenges as well as to attain drug synergy, we developed a lipid bilayer (LB)-coated mesoporous silica nanoparticle (silicasome) platform for co-delivery of the TLR7/8 agonist 3M-052 with the immunogenic chemotherapeutic agent irinotecan. This was accomplished by incorporating the C18 lipid tail of 3M-052 in the coated LB, also useful for irinotecan remote loading in the porous interior. Not only did the co-formulated carrier improve PK, but it strengthened the irinotecan-induced immunogenic cell death response by 3M-052-mediated dendritic cell activation at the tumor site as well as participating lymph nodes. The accompanying increase in CD8+ T-cell infiltration along with a reduced number of regulatory T-cells was associated with tumor shrinkage and metastasis disappearance in subcutaneous and orthotopic KRAS-mediated pancreatic carcinoma tumor models. Moreover, this therapeutic outcome was accomplished without drug or nanocarrier toxicity. All considered, dual-delivery strategies that combine chemo-immunotherapy with co-formulated TLR agonists or other lipid-soluble immune modulators predict successful intervention in heterogeneous PDAC immune landscapes.

An Updated Overview of Cyclodextrin-Based Drug Delivery Systems for Cancer Therapy

Encompassing a group of complex and heterogeneous diseases, cancer continues to be a challenge for patients and healthcare systems worldwide. Thus, it is of vital importance to develop advanced treatment strategies that could reduce the trends of cancer-associated morbidity and mortality rates. Scientists have focused on creating performant delivery vehicles for anti-cancer agents. Among the possible materials, cyclodextrins (CDs) attracted increasing interest over the past few years, leading to the emergence of promising anti-tumor nanomedicines. Tackling their advantageous chemical structure, ease of modification, natural origin, biocompatibility, low immunogenicity, and commercial availability, researchers investigated CD-based therapeutical formulations against many types of cancer. In this respect, in this paper, we briefly present the properties of interest of CDs for designing performant nanocarriers, further reviewing some of the most recent potential applications of CD-based delivery systems in cancer management.

An Updated Overview of Cyclodextrin-Based Drug Delivery Systems for Cancer Therapy

Encompassing a group of complex and heterogeneous diseases, cancer continues to be a challenge for patients and healthcare systems worldwide. Thus, it is of vital importance to develop advanced treatment strategies that could reduce the trends of cancer-associated morbidity and mortality rates. Scientists have focused on creating performant delivery vehicles for anti-cancer agents. Among the possible materials, cyclodextrins (CDs) attracted increasing interest over the past few years, leading to the emergence of promising anti-tumor nanomedicines. Tackling their advantageous chemical structure, ease of modification, natural origin, biocompatibility, low immunogenicity, and commercial availability, researchers investigated CD-based therapeutical formulations against many types of cancer. In this respect, in this paper, we briefly present the properties of interest of CDs for designing performant nanocarriers, further reviewing some of the most recent potential applications of CD-based delivery systems in cancer management.

Macrophage phenotype-switching in cancer

Tumour-associated macrophages (TAMs) have been found to be of great importance in tumorigenesis and in promoting malignant progression, including tumour angiogenesis and metastasis. Moreover, the TAM phenotype is more likely to be an M2 type. Transforming TAMs by M2-polarization into the tumour-suppressive M1-phenotype is an important approach for tumour therapy. In this review, we analysed the effects of the tumour microenvironment on macrophage phenotype-switching, including hypoxia and cytokines, and the mechanisms of drugs targeting TAMs. Furthermore, we analysed the effects of exosomes on macrophage polarization, phenotype switching of macrophages, and the mechanisms of lipid mediators targeting TAMs.

Recent Advances and Challenges in Cancer Immunotherapy

Simple Summary

Immunotherapy helps a person’s immune system to target tumor cells. Recent advances in cancer immunotherapy, including immune checkpoint inhibition, chimeric antigen receptor T-cell therapy and cancer vaccination, have changed the landscape of cancer treatment. These approaches have had profound success in certain cancer types but still fail in the majority of cases. This review will cover both successes and current challenges in cancer immunotherapy, as well as recent advances in the field of basic tumor immunology that will allow us to overcome resistance to existing treatments.

Abstract

Cancer immunotherapy has revolutionized the field of oncology in recent years. Harnessing the immune system to treat cancer has led to a large growth in the number of novel immunotherapeutic strategies, including immune checkpoint inhibition, chimeric antigen receptor T-cell therapy and cancer vaccination. In this review, we will discuss the current landscape of immuno-oncology research, with a focus on elements that influence immunotherapeutic outcomes. We will also highlight recent advances in basic aspects of tumor immunology, in particular, the role of the immunosuppressive cells within the tumor microenvironment in regulating antitumor immunity. Lastly, we will discuss how the understanding of basic tumor immunology can lead to the development of new immunotherapeutic strategies.

Cancer Immunotherapy and Delivery System: An Update

With an understanding of immunity in the tumor microenvironment, immunotherapy turns out to be a powerful tool in the clinic to treat many cancers. The strategies applied in cancer immunotherapy mainly include blockade of immune checkpoints, adoptive transfer of engineered cells, such as T cells, natural killer cells, and macrophages, cytokine therapy, cancer vaccines, and oncolytic virotherapy. Many factors, such as product price, off-target side effects, immunosuppressive tumor microenvironment, and cancer cell heterogeneity, affect the treatment efficacy of immunotherapies against cancers. In addition, some treatments, such as chimeric antigen receptor (CAR) T cell therapy, are more effective in treating patients with lymphoma, leukemia, and multiple myeloma rather than solid tumors. To improve the efficacy of targeted immunotherapy and reduce off-target effects, delivery systems for immunotherapies have been developed in past decades using tools such as nanoparticles, hydrogel matrix, and implantable scaffolds. This review first summarizes the currently common immunotherapies and their limitations. It then synopsizes the relative delivery systems that can be applied to improve treatment efficacy and minimize side effects. The challenges, frontiers, and prospects for applying these delivery systems in cancer immunotherapy are also discussed. Finally, the application of these approaches in clinical trials is reviewed.

Spatiotemporal control of engineered bacteria to express interferon-γ by focused ultrasound for tumor immunotherapy

Bacteria-based tumor therapy has recently attracted wide attentions due to its unique capability in targeting tumors and preferentially colonizing the core area of the tumor. Various therapeutic genes are also harbored into these engineering bacteria to enhance their anti-tumor efficacy. However, it is difficult to spatiotemporally control the expression of these inserted genes in the tumor site. Here, we engineer an ultrasound-responsive bacterium (URB) which can induce the expression of exogenous genes in an ultrasound-controllable manner. Owing to the advantage of ultrasound in tissue penetration, an acoustic remote control of bacterial gene expression can be realized by designing a temperature-actuated genetic switch. Cytokine interferon-γ (IFN-γ), an important immune regulatory molecule that plays a significant role in tumor immunotherapy, is used to test the system. Our results show that brief hyperthermia induced by focused ultrasound promotes the expression of IFN-γ gene, improving anti-tumor efficacy of URB in vitro and in vivo. Our study provides an alternative strategy for bacteria-mediated tumor immunotherapy.

In Vivo Click Chemistry Enables Multiplexed Intravital Microscopy

The ability to observe cells in live organisms is essential for understanding their function in complex in vivo milieus. A major challenge today has been the limited ability to perform higher multiplexing beyond four to six colors to define cell subtypes in vivo. Here, a click chemistry-based strategy is presented for higher multiplexed in vivo imaging in mouse models. The method uses a scission-accelerated fluorophore exchange (SAFE), which exploits a highly efficient bioorthogonal mechanism to completely remove fluorescent signal from antibody-labeled cells in vivo. It is shown that the SAFE-intravital microscopy imaging method allows 1) in vivo staining of specific cell types in dorsal and cranial window chambers of mice, 2) complete un-staining in minutes, 3) in vivo click chemistries at lower (µm) and thus non-toxic concentrations, and 4) the ability to perform in vivo cyclic imaging. The potential utility of the method is demonstrated by 12 color imaging of immune cells in live mice.

Tumor-Activatable Nanoparticles Target Low-Density Lipoprotein Receptor to Enhance Drug Delivery and Antitumor Efficacy

The binding of plasma proteins to nanomedicines is widely considered detrimental to their delivery to tumors. Here, the design of OxPt/SN38 nanoparticle containing a hydrophilic oxaliplatin (OxPt) prodrug in a coordination polymer core and a hydrophobic cholesterol-conjugated SN38 prodrug on the lipid shell for active tumor targeting is reported. OxPt/SN38 hitchhikes on low-density lipoprotein (LDL) particles, concentrates in tumors via LDL receptor-mediated endocytosis, and selectively releases SN38 and OxPt in acidic, esterase-rich, and reducing tumor microenvironments, leading to 6.0- and 4.9-times higher accumulations in tumors over free drugs. By simultaneously crosslinking DNA and inhibiting topoisomerase I, OxPt/SN38 achieved 92-98% tumor growth inhibition in five colorectal cancer tumor models and prolonged mouse survival by 58-80 days compared to free drug controls in three human colorectal cancer tumor models without causing serious side effects. The study has uncovered a novel nanomedicine strategy to co-deliver combination chemotherapies to tumors via active targeting of the LDL receptor.

Hydroxyapatite nanoparticles drive the potency of Toll-like receptor 9 agonist for amplified innate and adaptive immune response

The potency of Toll-like receptor 9 (TLR9) agonist to drive innate immune response was limited due to immune suppression or tolerance during TLR9 signaling activation in immune cells. Herein we addressed this problem by introducing hydroxyapatite nanoparticles (HANPs) to CpG ODN (CpG), a TLR9 agonist. The study revealed that HANPs concentration and duration-dependently reprogramed the immune response by enhancing the secretion of immunostimulatory cytokines (tumor necrosis factor α (TNFα) or IL-6) while reducing the production of immunosuppressive cytokine (IL-10) in macrophages in response to CpG. Next, the enhanced immune response benefited from increased intracellular Ca²⁺ in macrophage by the addition of HANPs. Further, we found exposure to HANPs impacted the mitochondrial function of macrophages in support of the synthesis of adenosine triphosphate (ATP), the production of nicotinamide adenine dinucleotide (NAD), and reactive oxygen species (ROS) in the presence or absence of CpG. In vaccinated mice model, only one vaccination with a mixture of CpG, HANPs, and OVA, a model antigen, allowed the development of a long-lasting balanced humoral immunity in mice without any histopathological change in the local injection site. Therefore, this study revealed that HANPs could modulate the intracellular calcium level, mitochondrial function, and immune response in immune cells, and suggested a potential combination adjuvant of HANPs and TLR9 agonist for vaccine development.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material (TEM image, LDH activity, the Ca²⁺ release in PBS, qRT-PCR analysis, H&E staining, and IL-6 level in the injection site and serum) is available in the online version of this article at 10.1007/s12274-022-4683-x.

Cationic poly(amino acid) surface functionalized manganese nanoparticles for nitric oxide-based immunotherapy and magnetic resonance imaging

The low therapeutic efficacy of conventional cancer chemotherapy has been associated with an immunosuppressive tumor microenvironment (TME). Tumor-associated macrophages (TAMs), which display an M2-like phenotype, are abundant in many tumors and facilitate tumor growth and resistance to therapy. Here, we show that poly(L-arginine) (PLR), a cationic poly(amino acid) can induce the polarization of macrophages into the tumor-suppressive M1 phenotype, in vitro. Further, we demonstrate that hyaluronic acid (HA) and PLR-coated manganese dioxide (MnO₂) nanoparticles (hpMNPs) display efficient anti-cancer effects by upregulating nitric oxide (NO) production. Surface modification with biocompatible HA reduced the cytotoxicity of the cationic PLR. Additionally, manganese ions released from these nanoparticles by the high concentrations of glutathione (GSH) in the TME increased iNOS expression level in macrophages and enhanced the performance of T₁ weighted magnetic resonance imaging. Particularly, our results illustrate the therapeutic effects, such as growth inhibition and apoptosis of tumor cells, of hpMNP treated macrophages. Therefore, the newly designed multifunctional PLR-assisted MNPs may facilitate the polarization of M2 macrophages into the M1 phenotype, which can mediate NO-dependent anticancer immunotherapy.

Correlation between PD-1/PD-L1 expression and polarization in tumor-associated macrophages: A key player in tumor immunotherapy

Tumor immunotherapy, such as PD-1/PD-L1 blockade, has shown promising clinical efficacy in patients with various types of tumors. However, the response to PD-1/PD-L1 blockade in a majority of malignancies is limited, indicating an urgent need for a deeper understanding of the mechanisms of PD-1/PD-L1 axis-mediated tumor tolerance. As the most abundant immune cells in the tumor stroma, macrophages display multiple phenotypes and functions in response to the stimuli of the tumor microenvironment. PD-1/PD-L1 has been demonstrated to be highly expressed in tumor-associated macrophages (TAMs), and TAM polarization has been shown to be important during tumor progression. In this review, we outline the relationship between TAM PD-1/PD-L1 expression and polarizations, summarize the involvement of M2 TAMs in PD-1/PD-L1-mediated T-cell exhaustion, and discuss improved approaches for overcoming PD-1/PD-L1 blockade resistance by inducing M2/M1 switching of TAMs.