Glycocalyx-Mimicking Nanoparticles Improve Anti-PD-L1 Cancer Immunotherapy through Reversion of Tumor-Associated Macrophages

Enhancing cancer immunotherapy: Exploring strategies to target the PD-1/PD-L1 axis and analyzing the associated patent, regulatory, and clinical trial landscape

Cancer treatment modalities and their progression is guided by the specifics of cancer, including its type and site of localization. Surgery, radiation, and chemotherapy are the most often used conventional treatments. Conversely, emerging treatment techniques include immunotherapy, hormone therapy, anti-angiogenic therapy, dendritic cell-based immunotherapy, and stem cell therapy. Immune checkpoint inhibitors' anticancer properties have drawn considerable attention in recent studies in the cancer research domain. Programmed Cell Death Protein-1 (PD-1) and its ligand (PD-L1) checkpoint pathway are key regulators of the interactions between activated T-cells and cancer cells, protecting the latter from immune destruction. When the ligand PD-L1 attaches to the receptor PD-1, T-cells are prevented from destroying cells that contain PD-L1, including cancer cells. The PD-1/PD-L1 checkpoint inhibitors block them, boosting the immune response and strengthening the body's defenses against tumors. Recent years have seen incredible progress and tremendous advancement in developing anticancer therapies using PD-1/PD-L1 targeting antibodies. While immune-related adverse effects and low response rates significantly limit these therapies, there is a need for research on methods that raise their efficacy and lower their toxicity. This review discusses various recent innovative nanomedicine strategies such as PLGA nanoparticles, carbon nanotubes and drug loaded liposomes to treat cancer targeting PD-1/PD-L1 axis. The biological implications of PD-1/PD-L1 in cancer treatment and the fundamentals of nanotechnology, focusing on the novel strategies used in nanomedicine, are widely discussed along with the corresponding guidelines, clinical trial status, and the patent landscape of such formulations.

Exploratory mapping of tumor associated macrophage nanoparticle article abstracts using an eLDA topic modeling machine learning approach

The role of macrophages in regulating the tumor microenvironment has spurned the exponential generation of nanoparticle targeting technologies. With the large amount of literature and the speed at which it is generated it is difficult to remain current with the most up-to-date literature. In this study we performed a topic modeling analysis of 854 abstracts of peer-reviewed literature for the most common usages of nanoparticle targeting of tumor associated macrophages (TAMs) in solid tumors. The data spans 20 years of literature, providing a broad perspective of the nanoparticle strategies. Our topic model found 6 distinct topics: Immune and TAMs, Nanoparticles, Imaging, Gene Delivery and Exosomes, Vaccines, and Multi-modal Therapies. We also found distinct nanoparticle usage, tumor types, and therapeutic trends across these topics. Moreover, we established that the topic model could be used to assign new papers into the existing topics, thereby creating a Living Review. This type of "birds-eye-view" analysis provides a useful assessment tool for exploring new and emerging themes within a large field.

Macrophage-modulating nanomedicine for cancer immunotherapy

Tumor-associated macrophages (TAMs) play crucial roles in the immunosuppressive solid tumor microenvironment (TME). Despite their tumor-promoting functions, TAMs can also be therapeutically modulated to exhibit tumor-killing properties, making them attractive targets for tumor immunotherapy. This review highlights the recent advances in nanomedicine-based strategies centered around macrophages for enhanced cancer immunotherapy. Emerging nanomedicine-based strategies to modulate TAMs in cancer treatment include repolarization of the TAM phenotype, inhibition of monocyte recruitment, depletion of TAMs, and blockage of immune checkpoints. These strategies have shown great promise in significantly improving the efficacy of cancer immunotherapy. Moreover, macrophage-inspired drug delivery systems have demonstrated significant promise in inducing immunotherapeutic effects and enhancing therapeutic efficacy by facilitating evasion from the reticuloendothelial system and promoting accumulation at the tumor site. Finally, we also discuss the challenges and propose future opportunities associated with macrophage-modulating nanomedicine to enhance cancer immunotherapy.

Induction of therapeutic immunity and cancer eradication through biofunctionalized liposome-like nanovesicles derived from irradiated-cancer cells

Immunotherapy has revolutionized the treatment of cancer. However, its efficacy remains to be optimized. There are at least two major challenges in effectively eradicating cancer cells by immunotherapy. Firstly, cancer cells evade immune cell killing by down-regulating cell surface immune sensors. Secondly, immune cell dysfunction impairs their ability to execute anti-cancer functions. Radiotherapy, one of the cornerstones of cancer treatment, has the potential to enhance the immunogenicity of cancer cells and trigger an anti-tumor immune response. Inspired by this, we fabricate biofunctionalized liposome-like nanovesicles (BLNs) by exposing irradiated-cancer cells to ethanol, of which ethanol serves as a surfactant, inducing cancer cells pyroptosis-like cell death and facilitating nanovesicles shedding from cancer cell membrane. These BLNs are meticulously designed to disrupt both of the aforementioned mechanisms. On one hand, BLNs up-regulate the expression of calreticulin, an "eat me" signal on the surface of cancer cells, thus promoting macrophage phagocytosis of cancer cells. Additionally, BLNs are able to reprogram M2-like macrophages into an anti-cancer M1-like phenotype. Using a mouse model of malignant pleural effusion (MPE), an advanced-stage and immunotherapy-resistant cancer model, we demonstrate that BLNs significantly increase T cell infiltration and exhibit an ablative effect against MPE. When combined with PD-1 inhibitor (α-PD-1), we achieve a remarkable 63.6% cure rate (7 out of 11) among mice with MPE, while also inducing immunological memory effects. This work therefore introduces a unique strategy for overcoming immunotherapy resistance.

NF-κB: Governing Macrophages in Cancer

Tumor-associated macrophages (TAMs) are the major component of the tumor microenvironment (TME), where they sustain tumor progression and or-tumor immunity. Due to their plasticity, macrophages can exhibit anti- or pro-tumor functions through the expression of different gene sets leading to distinct macrophage phenotypes: M1-like or pro-inflammatory and M2-like or anti-inflammatory. NF-κB transcription factors are central regulators of TAMs in cancers, where they often drive macrophage polarization toward an M2-like phenotype. Therefore, the NF-κB pathway is an attractive therapeutic target for cancer immunotherapy in a wide range of human tumors. Hence, targeting NF-κB pathway in the myeloid compartment is a potential clinical strategy to overcome microenvironment-induced immunosuppression and increase anti-tumor immunity. In this review, we discuss the role of NF-κB as a key driver of macrophage functions in tumors as well as the principal strategies to overcome tumor immunosuppression by targeting the NF-κB pathway.

Cancer Nano-Immunotherapy: The Novel and Promising Weapon to Fight Cancer

Cancer is a complex disease that, despite advances in treatment and the greater understanding of the tumor biology until today, continues to be a prevalent and lethal disease. Chemotherapy, radiotherapy, and surgery are the conventional treatments, which have increased the survival for cancer patients. However, the complexity of this disease together with the persistent problems due to tumor progression and recurrence, drug resistance, or side effects of therapy make it necessary to explore new strategies that address the challenges to obtain a positive response. One important point is that tumor cells can interact with the microenvironment, promoting proliferation, dissemination, and immune evasion. Therefore, immunotherapy has emerged as a novel therapy based on the modulation of the immune system for combating cancer, as reflected in the promising results both in preclinical studies and clinical trials obtained. In order to enhance the immune response, the combination of immunotherapy with nanoparticles has been conducted, improving the access of immune cells to the tumor, antigen presentation, as well as the induction of persistent immune responses. Therefore, nanomedicine holds an enormous potential to enhance the efficacy of cancer immunotherapy. Here, we review the most recent advances in specific molecular and cellular immunotherapy and in nano-immunotherapy against cancer in the light of the latest published preclinical studies and clinical trials.

Glucosylation endows nanoparticles with TLR4 agonist capability to trigger macrophage polarization and augment antitumor immunity

Carbohydrates have emerged as promising candidates for immunomodulation, however, how to present them to immune cells and achieve potent immunostimulatory efficacy remains challenging. Here, we proposed and established an effective way of designing unique glyconanoparticles that can amplify macrophage-mediated immune responses through structural mimicry and multiple stimulation. We demonstrate that surface modification with glucose can greatly augment the immunostimulatory efficacy of nanoparticles, comparing to mannose and galactose. In vitro studies show that glucosylation improved the pro-inflammatory efficacy of iron oxide nanoparticles (IONPs) by up to 300-fold, with the immunostimulatory activity of glucosylated IONPs even surpassing that of LPS under certain conditions. In vivo investigation show that glucosylated IONPs elicited increased antitumor immunity and achieved favorable therapeutic outcomes in multiple murine tumor models. Mechanistically, we proposed that glucosylation potentiated the immunostimulatory effect of IONPs by amplifying toll-like receptors 4 (TLR4) activation. Specifically, glucosylated IONPs directly interacted with the TLR4-MD2 complex, resulting in M1 macrophage polarization and enhanced antitumor immunity via activation of NF-κB, MAPK, and STAT1 signaling pathways. Our work provides a simple modification strategy to endow nanoparticles with potent TLR4 agonist effects, which may shed new light on the development of artificial immune modulators for cancer immunotherapy.

The cross-talk between macrophages and tumor cells as a target for cancer treatment

Macrophages represent an important component of the innate immune system. Under physiological conditions, macrophages, which are essential phagocytes, maintain a proinflammatory response and repair damaged tissue. However, these processes are often impaired upon tumorigenesis, in which tumor-associated macrophages (TAMs) protect and support the growth, proliferation, and invasion of tumor cells and promote suppression of antitumor immunity. TAM abundance is closely associated with poor outcome of cancer, with impediment of chemotherapy effectiveness and ultimately a dismal therapy response and inferior overall survival. Thus, cross-talk between cancer cells and TAMs is an important target for immune checkpoint therapies and metabolic interventions, spurring interest in it as a therapeutic vulnerability for both hematological cancers and solid tumors. Furthermore, targeting of this cross-talk has emerged as a promising strategy for cancer treatment with the antibody against CD47 protein, a critical macrophage checkpoint recognized as the "don't eat me" signal, as well as other metabolism-focused strategies. Therapies targeting CD47 constitute an important milestone in the advancement of anticancer research and have had promising effects on not only phagocytosis activation but also innate and adaptive immune system activation, effectively counteracting tumor cells' evasion of therapy as shown in the context of myeloid cancers. Targeting of CD47 signaling is only one of several possibilities to reverse the immunosuppressive and tumor-protective tumor environment with the aim of enhancing the antitumor response. Several preclinical studies identified signaling pathways that regulate the recruitment, polarization, or metabolism of TAMs. In this review, we summarize the current understanding of the role of macrophages in cancer progression and the mechanisms by which they communicate with tumor cells. Additionally, we dissect various therapeutic strategies developed to target macrophage-tumor cell cross-talk, including modulation of macrophage polarization, blockade of signaling pathways, and disruption of physical interactions between leukemia cells and macrophages. Finally, we highlight the challenges associated with tumor hypoxia and acidosis as barriers to effective cancer therapy and discuss opportunities for future research in this field.

Meta-analysis of macrophage nanoparticle targeting across blood and solid tumors using an eLDA Topic modeling Machine Learning approach

The role of macrophages in regulating the tumor microenvironment has spurned the exponential generation of nanoparticle targeting technologies. With the large amount of literature and the speed at which it is generated it is difficult to remain current with the most up-to-date literature. In this study we performed a topic modeling analysis of the most common usages of nanoparticle targeting of macrophages in solid tumors. The data spans 20 years of literature, providing an extensive meta-analysis of the nanoparticle strategies. Our topic model found 6 distinct topics: Immune and TAMs, Nanoparticles, Imaging, Gene Delivery and Exosomes, Vaccines, and Multi-modal Therapies. We also found distinct nanoparticle usage, tumor types, and therapeutic trends across these topics. Moreover, we established that the topic model could be used to assign new papers into the existing topics, thereby creating a Living Review. This type of meta-analysis provides a useful assessment tool for aggregating data about a large field.

Reprogramming Hypoxic Tumor-Associated Macrophages by Nanoglycoclusters for Boosted Cancer Immunotherapy

The tumor-associated macrophages (TAMs) in intratumoral hypoxic regions are key drivers of immune escape. Reprogramming the hypoxic TAMs to antitumor phenotype holds great therapeutic benefits but remains challenging for current drugs. Here, an in situ activated nanoglycocluster is reported to realize effective tumor penetration and potent repolarization of hypoxic TAMs. Triggered by the hypoxia-upregulated matrix metalloproteinase-2 (MMP-2), the nanoglycocluster is self-assembled from the administered mannose-containing precursor glycopeptides and presents densely-arrayed mannoses to multivalently engage with mannose receptors on M2-like TAMs for efficient phenotype switch. By virtue of the high diffusivity of precursor glycopeptides due to their low molecular mass and weak affinity with TAMs in perivascular regions, the nanoglycoclusters are capable of substantially accumulating in hypoxic areas to strongly interact with local TAMs. This enables the efficient repolarization of overall TAMs with a higher rate than the small-molecule drug R848 and CD40 antibody, and beneficial therapeutic effects in mouse tumor models especially when combining with PD-1 antibody. This on-demand activated immunoagent is endowed with tumor-penetrating properties and inspires the design of diverse intelligent nanomedicines for hypoxia-related cancer immunotherapy.

Photoinduced electron transfer (PeT) based fluorescent probes for cellular imaging and disease therapy

Typical PeT-based fluorescent probes are multi-component systems where a fluorophore is connected to a recognition/activating group by an unconjugated linker. PeT-based fluorescent probes are powerful tools for cell imaging and disease diagnosis due to their low fluorescence background and significant fluorescence enhancement towards the target. This review provides research progress towards PeT-based fluorescent probes that target cell polarity, pH and biological species (reactive oxygen species, biothiols, biomacromolecules, etc.) over the last five years. In particular, we emphasise the molecular design strategies, mechanisms, and application of these probes. As such, this review aims to provide guidance and to enable researchers to develop new and improved PeT-based fluorescent probes, as well as promoting the use of PeT-based systems for sensing, imaging, and disease therapy.

Glycopolymers for Antibacterial and Antiviral Applications

Diseases induced by bacterial and viral infections are common occurrences in our daily life, and the main prevention and treatment strategies are vaccination and taking antibacterial/antiviral drugs. However, vaccines can only be used for specific viral infections, and the abuse of antibacterial/antiviral drugs will create multi-drug-resistant bacteria and viruses. Therefore, it is necessary to develop more targeted prevention and treatment methods against bacteria and viruses. Proteins on the surface of bacteria and viruses can specifically bind to sugar, so glycopolymers can be used as potential antibacterial and antiviral drugs. In this review, the research of glycopolymers for bacterial/viral detection/inhibition and antibacterial/antiviral applications in recent years are summarized.

M2 tumor-associated macrophage mediates the maintenance of stemness to promote cisplatin resistance by secreting TGF-β1 in esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a deadly gastrointestinal malignancy, and chemotherapy resistance is a key factor leading to its poor prognosis. M2 tumor-associated macrophages (M2-TAMs) may be an important cause of chemoresistance in ESCC, but its exact mechanism is still unclear.

METHODS

In order to study the role of M2-TAMs in ESCC chemoresistance, CCK-8, clone formation assay, flow cytometric apoptosis assay, qRT-PCR, western blotting, and serum-free sphere formation assays were used. In vivo animal experiments and human ESCC tissues were used to confirm the findings.

RESULTS

In vitro and in vivo animal experiments, M2-TAMs reduced the sensitivity of ESCC cells to cisplatin. Mechanistically, M2-TAMs highly secreted TGF-β1 which activated the TGFβR1-smad2/3 pathway to promote and maintain the stemness characteristic of ESCC cells, which could inhibit the sensitivity to cisplatin. Using TGFβ signaling inhibitor SB431542 or knockdown of TGFβR1 could reverse the cisplatin resistance of ESCC cells. In 92 cases of human ESCC tissues, individuals with a high density of M2-TAMs had considerably higher levels of TGF-β1. These patients also had worse prognoses and richer stemness markers.

CONCLUSION

TGF-β1 secreted from M2-TAMs promoted and maintained the stemness characteristic to induce cisplatin resistance in ESCC by activating the TGFβ1-Smad2/3 pathway.

Identification and analysis of a CD8+ T cell-related prognostic signature for colorectal cancer based on bulk RNA sequencing and scRNA sequencing data: A STROBE-compliant retrospective study

Colorectal cancer (CRC) is one of the most common malignancies worldwide, leading to a large number of cancer-related mortalities. Aberrant CD8+ T cell infiltration plays a critical role in tumor progression and patient prognosis. This study aimed to identify a prognostic model for CRC based on CD8+ T cell-related genes. The infiltration levels of immune cells in CRC tissues were accessed by the ESTIMATE algorithm. Weighted gene co-expression network analysis (WGCNA) analysis was used to select CD8+ T cell-related genes. Prognostic genes were identified using Cox regression analysis and Kaplan-Meier curves. The least absolute shrinkage and selection operator (LASSO) algorithm was used to construct prognostic models. Gene set enrichment analysis (GSEA) was performed to annotate enriched gene sets. Single-cell RNA (scRNA) sequencing analysis was used to examine gene expression in different cell types. We found that the downregulated infiltration level of CD8+ T cells was an independent prognostic factor for CRC and selected a cluster of differentially expressed genes correlated with CD8+ T cell infiltration (CD8TDEGs). Subsequently, we identified 18 prognostic CD8TDEGs, according to which patients were reclassified into two clusters with distinct overall survival. Seven prognostic CD8TDEGs were selected to calculate the constructed prognostic model's risk scores. Interestingly, although CRC tissues with higher risk scores had higher infiltration levels of CD8+ T cells, the level of immune checkpoint genes was also high. Moreover, the scRNA-sequencing analysis showed that the expression levels of CD8TDEGs in the prognostic model varied among different types of cells. This study constructed a novel prognostic model for CRC and provided a foundation for targeting CD8+ T cell infiltration to improve the survival of CRC patients.

Reclassifying TNM stage I/II colorectal cancer into two subgroups with different overall survival, tumor microenvironment, and response to immune checkpoint blockade treatment

Background: The traditional TNM staging system is often insufficient to differentiate the survival discrepancies of colorectal cancer (CRC) patients at TNM stage I/II. Our study aimed to reclassify stage I/II CRC patients into several subgroups with different prognoses and explore their suitable therapeutic methods.

Methods: Single-cell RNA (scRNA) sequencing data, bulk RNA sequencing data, and clinicopathological information of CRC patients were enrolled from the TCGA and GEO databases. The tumor microenvironment of CRC tissues was accessed by the ESTIMATE algorithm. The prognostic genes were identified by Cox regression analysis. GO and KEGG analyses were conducted in the DAVID database. GSEA analysis was performed for annotation of the correlated gene sets.

Results: We successfully reclassified stage I/II CRC patients into two subgroups and discovered that patients in cluster-2 underwent worse overall survival than those in cluster-1. GSEA analysis showed that immune-associated gene sets were positively enriched in cluster-2. Besides, the differentially expressed genes (DEGs) between cluster-1 and cluster-2 patients also participated in immune-related biological processes and signaling pathways. Moreover, we found that more immune cells infiltrated the microenvironment of cluster-2 patients compared to that of cluster-1 patients, such as Tregs and tumor-associated macrophages. ScRNA sequencing analysis uncovered that most of the enriched immune-associated signaling in cluster-2 patients was mainly attributed to these upregulated immune cells whose infiltration levels were also high in CRC tissues rather than in normal tissues. In addition, we demonstrated that the expression of immune checkpoint genes was significantly higher in cluster-2 patients compared to cluster-1 patients. ScRNA sequencing analysis revealed that the infiltrated CD8+T cells in CRC were naïve T cells and can be activated into effector T cells after immune checkpoint blockade (ICB) treatment.

Conclusion: TNM stage I/II CRC patients can be divided into two subgroups, which have different overall survival rates, tumor microenvironment, and response to ICB therapy.

Nanomaterials and Advances in Tumor Immune-Related Therapy: A Bibliometric Analysis

With the rapid growth of the research content of nanomaterials and tumor immunity, the hot spots and urgent problems in the field become blurred. In this review, noticing the great development potential of this research field, we collected and sorted out the research articles from The Clarivate Analytics Web of Science (WOS) Core Collection database in the field over the past 20 years. Next, we use Excel 2019 from Microsoft (Microsoft Corp, Redmond,WA, USA), VOSviewer (version 1.6.18, Leiden University, Leiden, Netherlands), CiteSpace (Chaomei Chen, Drexel University, USA) and other softwares to conduct bibliometric analysis on the screened literatures. This paper not only analyzes the countries, institutions and authors with outstanding contributions in the current research field, but also comes up with the hot spots of current research. We hope that by analyzing and sorting out the past data, we can provide help for the current clinical work and future scientific research.

Prognostic alternative splicing events related splicing factors define the tumor microenvironment and pharmacogenomic landscape in lung adenocarcinoma

Background: Recent studies identified correlations between splicing factors (SFs) and tumor progression and therapy. However, the potential roles of SFs in immune regulation and the tumor microenvironment (TME) remain unknown.

Methods: We used UpSet plots to screen for prognostic-related alternative splicing (AS) events. We evaluated SF patterns in specific immune landscapes. Single sample gene set enrichment analysis (ssGSEA) algorithms were used to quantify relative infiltration levels in immune cell subsets. Principal component analysis (PCA) algorithm-based SFscore were used to evaluate SF patterns in individual tumors with an immune response.

Results: From prognosis-related AS events, 16 prognosis-related SFs were selected to construct three SF patterns. Further TME analyses showed these patterns were highly consistent with immune-inflamed, immune-excluded, and immune-desert landscapes. Based on SFscore constructed using differentially expressed genes (DEGs) between SF patterns, patients were classified into two immune-subtypes associated with differential pharmacogenomic landscapes and cell features. A low SFscore was associated with high immune cell infiltration, high tumor mutation burden (TMB), and elevated expression of immune check points (ICPs), indicating a better immune response.

Conclusions: SFs are significantly associated with TME remodeling. Evaluating different SF patterns enhances our understanding of the TME and improves effective immunotherapy strategies.

Liposome-Based Carbohydrate Vaccine for Simultaneously Eliciting Humoral and Cellular Antitumor Immunity

Tumor-associated carbohydrate antigen (TACA)-based cancer vaccines achieved promising results, whereas missing the T cell-mediated cellular immune response is still a crucial problem to be solved. Here, we have developed Tn antigen (GalNAc)-modified liposome-encapsulated TLR9 agonist CpG ODN adjuvant as a cancer vaccine. The glyco-liposome vaccines exhibit strong binding ability with an anti-Tn specific antibody and enhance antigen presentation of both bone marrow-derived dendritic cells (BMDCs) and spleen B cells. In vivo immunogenicity studies have demonstrated that the glyco-liposome vaccines can significantly enhance the generation of high anti-Tn antigen antibody titers and further induce a Th1-dependent cellular immune response, evidenced by IFN-γ secretion in an immune coculture of immunized T cells with Tn-expression 4T1 cancer cells. Collectively, our results highlight a liposome-based carbohydrate vaccine as a promising platform, which can simultaneously elicit both humoral and cellular antitumor immunity.

Cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs); where do they stand in tumorigenesis and how they can change the face of cancer therapy?

The tumor microenvironment (TME) and its components have recently attracted tremendous attention in cancer treatment strategies, as alongside the genetic and epigenetic alterations in tumor cells, TME could also provide a fertile background for malignant cells to survive and proliferate. Interestingly, TME plays a vital role in the mediation of cancer metastasis and drug resistance even against immunotherapeutic agents. Among different cells that are presenting in TME, tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs) have shown to have significant value in the regulation of angiogenesis, tumor metastasis, and drug-resistance through manipulating the composition as well as the organization of extracellular matrix (ECM). Evidence has shown that the presence of both TAMs and CAFs in TME is associated with poor prognosis and failure of chemotherapeutic agents. It seems that these cells together with ECM form a shield around tumor cells to protect them from the toxic agents and even the adaptive arm of the immune system, which is responsible for tumor surveillance. Given this, targeting TAMs and CAFs seems to be an essential approach to potentiate the cytotoxic effects of anti-cancer agents, either conventional chemotherapeutic drugs or immunotherapies. In the present review, we aimed to take a deep look at the mechanobiology of CAFs and TAMs in tumor progression and to discuss the available therapeutic approaches for harnessing these cells in TME.

Harnessing anti-tumor and tumor-tropism functions of macrophages via nanotechnology for tumor immunotherapy

Reprogramming the immunosuppressive tumor microenvironment by modulating macrophages holds great promise in tumor immunotherapy. As a class of professional phagocytes and antigen-presenting cells in the innate immune system, macrophages can not only directly engulf and clear tumor cells, but also play roles in presenting tumor-specific antigen to initiate adaptive immunity. However, the tumor-associated macrophages (TAMs) usually display tumor-supportive M2 phenotype rather than anti-tumor M1 phenotype. They can support tumor cells to escape immunological surveillance, aggravate tumor progression, and impede tumor-specific T cell immunity. Although many TAMs-modulating agents have shown great success in therapy of multiple tumors, they face enormous challenges including poor tumor accumulation and off-target side effects. An alternative solution is the use of advanced nanostructures, which not only can deliver TAMs-modulating agents to augment therapeutic efficacy, but also can directly serve as modulators of TAMs. Another important strategy is the exploitation of macrophages and macrophage-derived components as tumor-targeting delivery vehicles. Herein, we summarize the recent advances in targeting and engineering macrophages for tumor immunotherapy, including (1) direct and indirect effects of macrophages on the augmentation of immunotherapy and (2) strategies for engineering macrophage-based drug carriers. The existing perspectives and challenges of macrophage-based tumor immunotherapies are also highlighted.

Polyaniline-Based Glyco-Condensation on Au Nanoparticles Enhances Immunotherapy in Lung Cancer

Lung cancer is considered among the deadliest cancers with a poor prognosis. Au@PG nanoparticles (NPs) are gold (Au)-based NPs featuring a polyaniline-based glyco structure (PG) generated from the polymerization of ortho-nitrophenyl-β-d-galactopyranoside (ONPG) with promising M1 macrophage polarization activity, resulting in tumor remodeling and from a cold to a hot microenvironment, which promotes the cytotoxic T cell response and tumor inhibition. The combination of Au@PG NPs and anti-programmed cell death protein 1 (PD-1) therapy improved tumor inhibition and immunosuppression, accompanied by the secretion of immunogenic cytokines. A one-pot synthetic method was developed to achieve glyco-condensation during the formation of Au@PG NPs, which induced macrophage polarization more efficiently than Au@glucose, Au@mannose, and Au@galactose NPs. The switch from M2 to M1 macrophages was dependent on NP size, with smaller Au@PG NPs performing better than larger ones, with effectiveness ranked as follows: 32.2 nm ≈ 29.8 nm < 26.4 nm < 18.3 nm. Cellular uptake by endocytosis induced size-dependent endoplasmic reticulum (ER) stress, which resulted in the activation of spleen tyrosine kinase (SYK), leading to immune modulations and macrophage polarization. Our results suggested the promising potential of Au@PG NPs in lung cancer immunotherapy.

Manipulation of the tumor immuno-microenvironment via TAM-targeted expression of transcription factors

An immunosuppressive tumor microenvironment (TME) leads to cancer growth, metastasis, and therapeutic resistance. Immunomodulatory immunotherapy aims to skew the immunosuppressive TME back to an immune active state. Tumor-associated macrophages (TAMs) are a critical component of the TME that are actively involved in tumor-specific inflammation and immunosuppression. TAMs exhibit a diverse range of phenotypes and functions, from pro-tumor to anti-tumor. The plasticity of TAMs makes them a promising target for immunotherapy, and TAM-targeted therapies via different strategies have shown great potential. This review discusses current TAM-specific delivery targets and genes of interest for TAM-reprogramming. As phagocytic cells, TAMs have several receptors that have been used to increase TAM-targeted in vivo delivery. Furthermore, a promising approach for reprogramming TAMs is to activate or suppress specific transcription factors in the signal transducers and activators of transcription (STAT) and interferon regulatory factor (IRF) families. Altering TAM transcription factor expression results in a potent shift in cytokine expression and overall TAM function potentially tipping the balance from an immunosuppressive to an immune active TME.

Targeting the PD-1/PD-L1 axis for cancer treatment: a review on nanotechnology

Although nanomedicines have been in the oncology field for almost three decades with the introduction of doxil, only a few nanomedicine products have reached approval. Can nanotechnology be a realistic tool to reduce the number of hospital beds? At present, several clinically approved anti-PD-1/PD-L1 antibodies or CAR T cell-based therapies are available; however, the immunotherapy field is far from mature. Will immunotherapy be the fourth pillar of cancer treatment? In this review, we summarized the current status of immunotherapy using PD-1/PD-L1-targeting nanocarriers. The knowledge on material science, therapeutic agents and formulation designs could pave the way for high-efficacy treatment outcomes.

Glycoconjugate Nanoparticle-Based Systems in Cancer Immunotherapy: Novel Designs and Recent Updates

For many years, cell-surface glycans (in particular, Tumor-Associated Carbohydrate Antigens, TACAs) have been the target of both passive and active anticancer immunotherapeutic design. Recent advances in immunotherapy as a treatment for a variety of malignancies has revolutionized anti-tumor treatment regimens. Checkpoint inhibitors, Chimeric Antigen Receptor T-cells, Oncolytic virus therapy, monoclonal antibodies and vaccines have been developed and many approvals have led to remarkable outcomes in a subset of patients. However, many of these therapies are very selective for specific patient populations and hence the search for improved therapeutics and refinement of techniques for delivery are ongoing and fervent research areas. Most of these agents are directed at protein/peptide epitopes, but glycans-based targets are gaining in popularity, and a handful of approved immunotherapies owe their activity to oligosaccharide targets. In addition, nanotechnology and nanoparticle-derived systems can help improve the delivery of these agents to specific organs and cell types based on tumor-selective approaches. This review will first outline some of the historical beginnings of this research area and subsequently concentrate on the last 5 years of work. Based on the progress in therapeutic design, predictions can be made as to what the future holds for increasing the percentage of positive patient outcomes for optimized systems.

In Situ Formation of Au-Glycopolymer Nanoparticles for Surface-Enhanced Raman Scattering-Based Biosensing and Single-Cell Immunity

Successful synthesis of glyconanoparticles has attracted much attention due to their various biointeractive capabilities, but it is still a challenge to understand different single-cell responses to exogenous particles among cell populations. Herein, we designed polyaniline-containing galactosylated gold nanoparticles (Au@PGlyco NPs) via in situ polymerization of ortho-nitrophenyl-β-galactoside assisted by Au nucleation. The nanogold-carrying polyaniline block produced electromagnetic enhancement in surface-enhanced Raman scattering (SERS). The underlying polymerization mechanism of ortho-nitrophenyl compounds via the formation of Au nanoparticles was investigated. Depending on how the galactoside moiety reacted with β-galactosidase derived from bacteria, the Au@PGlyco NPs-mediated SERS biosensor could detect low amounts of bacteria (∼1 × 102 CFU/mL). In addition, a high accumulation of Au@PGlyco NPs mediated the immune response of tumor-associated M2 macrophages to the immunogenic M1 macrophage transition, which was elicited by reactive oxygen levels biostimulation using single-cell SERS-combined fluorescence imaging. Our study suggested that Au@PGlyco NPs may serve as a biosensing platform with the labeling capacity on galactose-binding receptors expressed cell and immune regulation.

Modulating Repolarization of Tumor-Associated Macrophages with Targeted Therapeutic Nanoparticles as a Potential Strategy for Cancer Therapy

There are always some components in the tumor microenvironment (TME), such as tumor-associated macrophages (TAMs), that help tumor cells escape the body's immune surveillance. Therefore, this situation can lead to tumor growth, progression, and metastasis, resulting in low response rates for cancer therapy. Macrophages play an important role with strong plasticity and functional diversity. Facing different microenvironmental stimulations, macrophages undergo a dynamic change in phenotype and function into two major macrophage subpopulations, namely classical activation/inflammation (M1) and alternative activation/regeneration (M2) type. Through various signaling pathways, macrophages polarize into complex groups, which can perform different immune functions. In this review, we emphasize the use of nanopreparations for macrophage related immunotherapy based on the pathological knowledge of TAMs phenotype. These macrophages targeted nanoparticles re-edit and re-educate macrophages by attenuating M2 macrophages and reducing aggregation to the TME, thereby relieving or alleviating immunosuppression. Among them, we describe in detail the cellular mechanisms and regulators of several major signaling pathways involved in the plasticity and polarization functions of macrophages. The advantages and challenges of those nanotherapeutics for these pathways have been elucidated, providing the basis and insights for the diagnosis and treatment strategies of various diseases centered on macrophages.

Carbohydrate-Based Macromolecular Biomaterials

Carbohydrates are the most abundant and one of the most important biomacromolecules in Nature. Except for energy-related compounds, carbohydrates can be roughly divided into two categories: Carbohydrates as matter and carbohydrates as information. As matter, carbohydrates are abundantly present in the extracellular matrix of animals and cell walls of various plants, bacteria, fungi, etc., serving as scaffolds. Some commonly found polysaccharides are featured as biocompatible materials with controllable rigidity and functionality, forming polymeric biomaterials which are widely used in drug delivery, tissue engineering, etc. As information, carbohydrates are usually referred to the glycans from glycoproteins, glycolipids, and proteoglycans, which bind to proteins or other carbohydrates, thereby meditating the cell-cell and cell-matrix interactions. These glycans could be simplified as synthetic glycopolymers, glycolipids, and glycoproteins, which could be afforded through polymerization, multistep synthesis, or a semisynthetic strategy. The information role of carbohydrates can be demonstrated not only as targeting reagents but also as immune antigens and adjuvants. The latter are also included in this review as they are always in a macromolecular formulation. In this review, we intend to provide a relatively comprehensive summary of carbohydrate-based macromolecular biomaterials since 2010 while emphasizing the fundamental understanding to guide the rational design of biomaterials. Carbohydrate-based macromolecules on the basis of their resources and chemical structures will be discussed, including naturally occurring polysaccharides, naturally derived synthetic polysaccharides, glycopolymers/glycodendrimers, supramolecular glycopolymers, and synthetic glycolipids/glycoproteins. Multiscale structure-function relationships in several major application areas, including delivery systems, tissue engineering, and immunology, will be detailed. We hope this review will provide valuable information for the development of carbohydrate-based macromolecular biomaterials and build a bridge between the carbohydrates as matter and the carbohydrates as information to promote new biomaterial design in the near future.

Sialic acid conjugate-modified liposomal platform modulates immunosuppressive tumor microenvironment in multiple ways for improved immune checkpoint blockade therapy

Immune checkpoint blockade (ICB) treatment is promising for the clinical therapy of numerous malignancies. However, most cancer patients rarely benefit from such single-agent immunotherapies because of the complexity of both the tumor and tumor microenvironment. A tumor-specific liposomal vehicle (DOX-SAL) modified with a sialic acid-cholesterol conjugate (SA-CH) and remotely loaded with doxorubicin (DOX) is herein reported for improving chemoimmunotherapy. The intravenous administration of DOX-SAL dramatically downregulates tumor-associated macrophage (TAM)-mediated immunosuppression, inhibits immunoregulatory functions, and promotes intratumoral infiltration of CD8⁺ T cells. Compared to conventional liposomes, DOX-SAL-mediated combination therapy with a PD-1-blocking monoclonal antibody (aPD-1 mAb) almost completely eliminates B16F10 tumors and efficiently inhibits 4T1 tumors. Moreover, cancer stem cells exhibit efficient tumor-initiating, tumor-propagating, and immunosuppressive tumor microenvironment-shaping capabilities. To further improve the treatment efficacy of an immunologically "cold" tumor, metformin (MET), which selectively eradicates breast cancer tumor stem cells, is co-encapsulated with DOX into liposomes to develop DOX/MET-SAL. The combination therapy with DOX/MET-SAL and aPD-1 mAb in a 4T1 orthotopic mouse model indicates their synergetic benefit on primary tumor inhibition, metastasis suppression, and survival rate improvement. Thus, the multifunctional liposomal platform has potential value for ICB combination immunotherapy.

A Review on Cancer Immunotherapy and Applications of Nanotechnology to Chemoimmunotherapy of Different Cancers

Clinically, different approaches are adopted worldwide for the treatment of cancer, which still ranks second among all causes of death. Immunotherapy for cancer treatment has been the focus of attention in recent years, aiming for an eventual antitumoral effect through the immune system response to cancer cells both prophylactically and therapeutically. The application of nanoparticulate delivery systems for cancer immunotherapy, which is defined as the use of immune system features in cancer treatment, is currently the focus of research. Nanomedicines and nanoparticulate macromolecule delivery for cancer therapy is believed to facilitate selective cytotoxicity based on passive or active targeting to tumors resulting in improved therapeutic efficacy and reduced side effects. Today, with more than 55 different nanomedicines in the market, it is possible to provide more effective cancer diagnosis and treatment by using nanotechnology. Cancer immunotherapy uses the body's immune system to respond to cancer cells; however, this may lead to increased immune response and immunogenicity. Selectivity and targeting to cancer cells and tumors may lead the way to safer immunotherapy and nanotechnology-based delivery approaches that can help achieve the desired success in cancer treatment.

Synthesis and Biopharmaceutical Applications of Sugar-Based Polymers: New Advances and Future Prospects

The rapid rise in research interest in carbohydrate-based polymers is undoubtedly due to the nontoxic nature of such materials in an in vivo environment and the versatile roles that the polymers can play in cellular functions. Such polymers have served as therapeutic tools for drug delivery, including antigens, proteins, and genes, as well as diagnostic devices. Our focus in the first half of this Review is on synthetic methods based on ring-opening polymerization and enzyme-catalyzed polymerization, along with controlled radical polymerization. In the second half of this Review, sugar-based polymers are discussed on the basis of their remarkable success in competitive receptor binding, as multifunctional nanocarriers of targeting inhibitors for cancer treatment, in genome-editing delivery, in immunotherapy based on endogenous antibody recruitment, and in treatment of respiratory diseases, including influenza A. Particular emphasis is put on the synthesis and biopharmaceutical applications of sugar-based polymers published in the most recent 5 years. A noticeable attribute of carbohydrate-based polymers is that the sugar-receptor interactions can be facilitated by the cooperative effect of multiple sugar units. Their diversified topology and structures will drive the development of new synthetic strategies and bring about important applications, including coronavirus-related drug therapy.

Tumor microenvironment remodeling and tumor therapy based on M2-like tumor associated macrophage-targeting nano-complexes

Background: Among the many immunosuppressive cells in the tumor microenvironment, tumor-associated-macrophages (TAMs) are well known to contribute to tumor development. TAMs can be conditioned (polarized) to transition between classical M1-like macrophages, or alternatively to M2-like macrophages. Both are regulated by signaling molecules in the microenvironment. M1-like TAMs can secrete classic inflammatory cytokines that kill tumors by promoting tumor cell necrosis and immune cell infiltration into the tumor microenvironment. In contrast, M2-like TAMs exhibit powerful tumor-promoting functions, including degradation of tumor extracellular matrix, destruction of basement membrane, promotion of angiogenesis, and recruitment of immunosuppressor cells, all of which further promote tumor progression and distal metastasis. Therefore, remodeling the tumor microenvironment by reversing the TAM phenotype will be favorable for tumor therapy, especially immunotherapy. Methods: PLGA nanoparticles encapsulating baicalin and melanoma antigen Hgp peptide fragment 25-33 were fabricated using the ultrasonic double-emulsion technique. The nanoparticles were further loaded with CpG fragments and used conjugated M2pep and α-pep peptides on their surfaces to produce novel nano-complexes. The capability to target M2-like TAMs and anti-tumor immunotherapy effects of nano-complexes were evaluated by flow cytometry and confocal microscopy in vitro. We also investigated the survival and histopathology of murine melanoma models administrated with different nanocomplexes. Improvements in the tumor microenvironment for immune attack of melanoma-bearing mice were also assessed. Results: The nano-complexes were effectively ingested by M2-like TAMs in vitro and in vivo, and the acidic lysosomal environment triggered the disintegration of polydopamine from the nanoparticle surface, which resulted in the release of the payloads. The released CpG played an important role in transforming the M2-like TAMs into the M1-like phenotype that further secreted inflammatory cytokines. The reversal of TAM released cytokines and gradually suppressed tumor angiogenesis, permitting the remodeling of the tumor microenvironment. Moreover, the activated TAMs also presented antigen to T cells, which further stimulated the antitumor immune response that inhibited tumor metastasis. Activated T cells released cytokines, which stimulated NK cell infiltration and directly resulted in killing tumor cells. The baicalin released by M1-like TAMs also killed tumor cells. Conclusion: The nano-complexes facilitated baicalin, antigen, and immunostimulant delivery to M2-like TAMs, which polarized and reversed the M2-like TAM phenotype and remodeled the tumor microenvironment to allow killing of tumor cells.

Tumor-associated macrophages: role in tumorigenesis and immunotherapy implications

Tumor-associated macrophages (TAMs) occupy an important position in the tumor microenvironment (TME), they are a highly plastic heterogeneous population with complex effects on tumorigenesis and development. TAMs secrete a variety of cytokines, chemokines, and proteases, which promote the remodeling of extracellular matrix, tumor cell growth and metastasis, tumor vessel and lymphangiogenesis, and immunosuppression. TAMs with different phenotypes have different effects on tumor proliferation and metastasis. TAMs act a pivotal part in occurrence and development of tumors, and are very attractive target to inhibit tumor growth and metastasis in tumor immunotherapy. This article reviews the interrelationship between TAMs and tumor microenvironment and its related applications in tumor therapy.

Nanomedicine enables spatiotemporally regulating macrophage-based cancer immunotherapy

Cancer immunotherapy, leveraging the host's coordinated immune system to fight against tumor has been clinically validated. However, the modest response owing to the multiple ways of tumor immune evasion is one of the challenges in cancer immunotherapy. Tumor associated macrophages (TAMs), as a major component of the leukocytes infiltrating in all tumors, play crucial roles in driving cancer initiation, progress and metastasis via multiple mechanisms such as mediating chronic inflammation, promoting angiogenesis, taming protective immune responses, and supporting migration and intravasation. TAMs targeted therapeutics have achieved remarkable successes in clinical trials mostly through the use of small-molecule agents and antibodies. However, efforts for further application have met with challenges of limited efficacy and safety. Nanomaterials can provide versatile approaches to realize the superior spatiotemporal control over immunomodulation to amplify immune responses, ultimately enhancing the therapeutic benefits and reducing toxicity. Here, the potential drugs used in TAM-centered cancer treatment in clinic are summarized and the recent advances of TAMs targeted nanomedicines in this filed are highlighted. More importantly, we focus on how nanomedicine can exert their advantages in spatial and temporal control of immunomodulation.

The Crosstalk Between Tumor-Associated Macrophages (TAMs) and Tumor Cells and the Corresponding Targeted Therapy

Tumor microenvironment (TME) is composed of tumor cells and surrounding non-tumor stromal cells, mainly including tumor associated macrophages (TAMs), endothelial cells, and carcinoma-associated fibroblasts (CAFs). The TAMs are the major components of non-tumor stromal cells, and play an important role in promoting the occurrence and development of tumors. Macrophages originate from bone marrow hematopoietic stem cells and embryonic yolk sacs. There is close crosstalk between TAMs and tumor cells. With the occurrence of tumors, tumor cells secrete various chemokines to recruit monocytes to infiltrate tumor tissues and further promote their M2-type polarization. Importantly, M2-like TAMs can in turn accelerate tumor growth, promote tumor cell invasion and metastasis, and inhibit immune killing to promote tumor progression. Therefore, targeting TAMs in tumor tissues has become one of the principal strategies in current tumor immunotherapy. Current treatment strategies focus on reducing macrophage infiltration in tumor tissues and reprogramming TAMs to M1-like to kill tumors. Although these treatments have had some success, their effects are still limited. This paper mainly summarized the recruitment and polarization of macrophages by tumors, the support of TAMs for the growth of tumors, and the research progress of TAMs targeting tumors, to provide new treatment strategies for tumor immunotherapy.

Tumor Microenvironment: Implications in Melanoma Resistance to Targeted Therapy and Immunotherapy

Simple Summary

The response to pharmacological treatments is deeply influenced by the tight interactions between the tumor cells and the microenvironment. In this review we describe, for melanoma, the most important mechanisms of resistance to targeted therapy and immunotherapy mediated by the components of the microenvironment. In addition, we briefly describe the most recent therapeutic advances for this pathology. The knowledge of molecular mechanisms, which are underlying of drug resistance, is fundamental for the development of new therapeutic approaches for the treatment of melanoma patients.

Abstract

Antitumor therapies have made great strides in recent decades. Chemotherapy, aggressive and unable to discriminate cancer from healthy cells, has given way to personalized treatments that, recognizing and blocking specific molecular targets, have paved the way for targeted and effective therapies. Melanoma was one of the first tumor types to benefit from this new care frontier by introducing specific inhibitors for v-Raf murine sarcoma viral oncogene homolog B (BRAF), mitogen-activated protein kinase kinase (MEK), v-kit Hardy–Zuckerman 4 feline sarcoma viral oncogene homolog (KIT), and, recently, immunotherapy. However, despite the progress made in the melanoma treatment, primary and/or acquired drug resistance remains an unresolved problem. The molecular dynamics that promote this phenomenon are very complex but several studies have shown that the tumor microenvironment (TME) plays, certainly, a key role. In this review, we will describe the new melanoma treatment approaches and we will analyze the mechanisms by which TME promotes resistance to targeted therapy and immunotherapy.

Engineering Macrophages for Cancer Immunotherapy and Drug Delivery

Macrophages play an important role in cancer development and metastasis. Proinflammatory M1 macrophages can phagocytose tumor cells, while anti-inflammatory M2 macrophages such as tumor-associated macrophages (TAMs) promote tumor growth and invasion. Modulating the tumor immune microenvironment through engineering macrophages is efficacious in tumor therapy. M1 macrophages target cancerous cells and, therefore, can be used as drug carriers for tumor therapy. Herein, the strategies to engineer macrophages for cancer immunotherapy, such as inhibition of macrophage recruitment, depletion of TAMs, reprograming of TAMs, and blocking of the CD47-SIRPα pathway, are discussed. Further, the recent advances in drug delivery using M1 macrophages, macrophage-derived exosomes, and macrophage-membrane-coated nanoparticles are elaborated. Overall, there is still significant room for development in macrophage-mediated immune modulation and macrophage-mediated drug delivery, which will further enhance current tumor therapies against various malignant solid tumors, including drug-resistant tumors and metastatic tumors.

Targeted delivery of chlorogenic acid by mannosylated liposomes to effectively promote the polarization of TAMs for the treatment of glioblastoma

Tumor-associated macrophages (TAMs) generally display an immunosuppressive M2 phenotype and promote tumor progression and metastasis, suggesting their potential value as a target in cancer immunotherapy. Chlorogenic acid (CHA) has been identified as a potent immunomodulator that promotes the polarization of TAMs from an M2 to an M1 phenotype. However, rapid clearance in vivo and low tumor accumulation have compromised the immunotherapeutic efficacy of CHA in clinical trials. In this study, mannosylated liposomes are developed for targeted delivery of CHA to TAMs. The immunoregulatory effects of CHA, along with the overall antitumor efficacy of CHA-encapsulated mannosylated liposomes, are investigated through in vitro and in vivo experiments. The prepared CHA-encapsulated mannosylated liposomes exhibit an ideal particle size, favorable stability, and preferential accumulation in tumors via the mannose receptor-mediated TAMs-targeting effects. Further, CHA-encapsulated mannosylated liposomes inhibit G422 glioma tumor growth by efficiently promoting the polarization of the pro-tumorigenic M2 phenotype to the anti-tumorigenic M1 phenotype. Overall, these findings indicate that CHA-encapsulated mannosylated liposomes have great potential to enhance the immunotherapeutic efficacy of CHA by inducing a shift from the M2 to the M1 phenotype.

Glycosyltransferase-Induced Morphology Transition of Glycopeptide Self-Assemblies with Proteoglycan Residues

We previously proposed the deprotection-induced block copolymer self-assembly (DISA), that is, the deprotection of hydroxyl groups of saccharides resulted in self-assembly of glycopolymers (Qi et al. J. Am. Chem. Soc. 2018, 140 (28), 8851-8857 and Su et al. ACS Macro Lett. 2014, 3 (6), 534-539). In this study, we further combined glycochemistry and self-assembly strategy by introducing glycosyltransferase as the trigger, which constructs another glycosidic bonds and another carbohydrate building blocks in situ. Herein, we propose to utilize glycosyltransferase to induce the morphology transition of glycopeptide assemblies in the process of glycosidic bonds construction, which has never been reported in literature. This strategy provides us an alternative tool to construct proteoglycan-mimicking polymeric materials and deepens our understanding on the natural process of proteoglycan construction better in the future.

Exploring and Controlling the Polymorphism in Supramolecular Assemblies of Carbohydrates and Proteins

In biology, polymorphism is a well-known phenomenon by which a discrete biomacromolecule can adopt multiple specific conformations in response to its environment. This term can be extended to the ability of biomacromolecules to pack into different ordered patterns. Thus, exploration and control of the polymorphism of biomacromolecules via supramolecular methods have been key steps in achieving bioinspired structures, developing bioinspired functional materials, and exploring the mechanisms of these self-assembly processes, which are models for more complex biological systems. This task could be difficult for proteins and carbohydrates due to the complicated multiple noncovalent interactions of these two species which can hardly be manipulated.In this account, dealing with the structural polymorphisms from biomacromolecular assemblies, we will first briefly comment on the problems that carbohydrate/protein assemblies are facing, and then on the basis of our long-term research on carbohydrate self-assemblies, we will summarize the new strategies that we have developed in our laboratory in recent years to explore and control the polymorphism of carbohydrate/protein assemblies.Considering the inherent ability of carbohydrates to recognize lectin, we proposed the "inducing ligand" strategy to assemble natural proteins into various nanostructures with highly ordered packing patterns. The newly developed inducing ligand approach opened a new window for protein assembly where dual noncovalent interactions (i.e., carbohydrate-protein interactions and dimerization of rhodamine) instead of the traditionally used protein-protein interactions direct the assembly pattern of proteins. As a result, various polymorphisms of protein assemblies have been constructed by simply changing the ligand chemical structure and/or the rhodamine dimerization.Another concept that we proposed for glycopolymer self-assembly is DISA (i.e., deprotection-induced glycopolymer self-assembly). It is well known that protection-deprotection chemistry has been employed to construct complex oligosaccharide structures. However, its application in glycopolymer self-assembly has been overlooked. We initiated this new strategy with diblock copolymers. Such copolymers with a carbohydrate block having protected pendent groups exist as single chains in organic media. The self-assembly can be initiated by the deprotection of the pendent groups. The process was nicely controlled by introducing various protective groups with different deprotection rates. Later on, the DISA process has been proven practical in water and even in the cellular environment, which opens a new avenue for the development of polymeric glycomaterials.Finally, the resultant polymeric glyco-materials, as a new type of biomimetic materials, provide a nice platform for investigating the functions of glycocalyx. The glycocalyx-mimicking nanoparticles achieved unprecedent functions which exceed their carbohydrate precursors. Here, the reversion of tumor-associated macrophages induced by glycocalyx-mimicking nanoparticles will be discussed with potential applications in cancer immunotherapy, where such a reversion effect could be combined with other methods (e.g., tumor checkpoint blockade).

Artificial Nanoscale Erythrocytes from Clinically Relevant Compounds for Enhancing Cancer Immunotherapy

Because of enhanced efficacy and lower side effects, cancer immunotherapies have recently been extensively investigated in clinical trials to overcome the limitations of conventional cancer monotherapies. Although engineering attempts have been made to build nanosystems even including stimulus nanomaterials for the efficient delivery of antigens, adjuvants, or anticancer drugs to improve immunogenic cancer cell death, this requires huge R&D efforts and investment for clinically relevant findings to be approved for translation of the nanosystems. To this end, in this study, an air-liquid two-phase electrospray was developed for stable bubble pressing under a balance between mechanical and electrical parameters of the spray to continuously produce biomimetic nanosystems consisting of only clinically relevant compounds [paclitaxel-loaded fake blood cell Eudragit particle (Eu-FBCP/PTX)] to provide a conceptual leap for the timely development of translatable chemo-immunotherapeutic nanosystems. This was pursued as the efficacy of systems for delivering anticancer agents that has been mainly influenced by nanosystem shape because of its relevance to transporting behavior to organs, blood circulation, and cell-membrane interactions. The resulting Eu-FBCP/PTX nanosystems exhibiting phagocytic and micropinocytic uptake behaviors can confer better efficacy in chemo-immunotherapeutics in the absence and presence of anti-PD-L1 antibodies than similar sized PTX-loaded spherical Eu particles (Eu-s/PTX).

Zwitterionic chitooligosaccharide-modified ink-blue titanium dioxide nanoparticles with inherent immune activation for enhanced photothermal therapy

Photothermal therapy (PTT) can trigger massive apoptosis of cancer cells, and this sharply increasing local apoptotic rate may recruit plenty of tumor-associated macrophages (TAMs). Although TAMs are recognized to display an M2-like subtype, which encourages tumor ontogenesis, they can be re-educated to a tumoricidal M1-like subtype by immunomodulatory reagents. Chitooligosaccharides (COSs) are endowed with immunomodulatory ability, but the positive electrical property limits their application; besides, their re-educating ability on TAMs is uncertain. Therefore, we proposed whether the combination of zwitterionic COS with a photothermal material can impair the undesirable tumor promotion of TAMs, thus enhancing the PTT treatment outcome. Herein, zwitterionic COS was obtained via the carboxymethylate method and then, the obtained COS was modified on the surface of ink-blue titanium dioxide (BTiO2) with photothermal ability to synthesize BTC NPs. In vitro, the immunofluorescence staining and cell survival assays indicated that BTC NPs could re-educate 87% of the M2-like RAW264.7 macrophages stimulated by apoptotic tumor cell secretion and significantly inhibit the liver tumor cell proliferation. Notably, in a mouse H22 liver cancer model, compared with mono PTT with BTiO2, the PTT treatment of BTC could reverse the ratio of M2 : M1 from 3.3 : 1 to 0.5 : 1, thus leading to 20.7% increase in the tumor inhibition rate. In general, our study demonstrated that zwitterionic COS can act as a potent immune activator to re-educate TAMs to M1. Furthermore, equipping the photothermal material with zwitterionic COS can be a potential treatment paradigm to achieve more forceful PTT.

Models for Monocytic Cells in the Tumor Microenvironment

Monocytes (Mos) are immune cells that critically regulate cancer, enabling tumor growth and modulating metastasis. Mos can give rise to tumor-associated macrophages (TAMs) and Mo-derived dendritic cells (moDCs), all of which shape the tumor microenvironment (TME). Thus, understanding their roles in the TME is key for improved immunotherapy. Concurrently, various biological and mechanical factors including changes in local cytokines, extracellular matrix production, and metabolic changes in the TME affect the roles of monocytic cells. As such, relevant TME models are critical to achieve meaningful insight on the precise functions, mechanisms, and effects of monocytic cells. Notably, murine models have yielded significant insight into human Mo biology. However, many of these results have yet to be confirmed in humans, reinforcing the need for improved in vitro human TME models for the development of cancer interventions. Thus, this chapter (1) summarizes current insight on the tumor biology of Mos, TAMs, and moDCs, (2) highlights key therapeutic applications relevant to these cells, and (3) discusses various TME models to study their TME-related activity. We conclude with a perspective on the future research trajectory of this topic.

Phosphorylation: A Fast Switch For Checkpoint Signaling

Checkpoint signaling involves a variety of upstream and downstream factors that participate in the regulation of checkpoint expression, activation, and degradation. During the process, phosphorylation plays a critical role. Phosphorylation is one of the most well-documented post-translational modifications of proteins. Of note, the importance of phosphorylation has been emphasized in aspects of cell activities, including proliferation, metabolism, and differentiation. Here we summarize how phosphorylation of specific molecules affects the immune activities with preference in tumor immunity. Of course, immune checkpoints are given extra attention in this book. There are many common pathways that are involved in signaling of different checkpoints. Some of them are integrated and presented as common activities in the early part of this chapter, especially those associated with PD-1/PD-L1 and CTLA-4, because investigations concerning them are particularly abundant and variant. Their distinct regulation is supplementarily discussed in their respective section. As for checkpoints that are so far not well explored, their related phosphorylation modulations are listed separately in the later part. We hope to provide a clear and systematic view of the phosphorylation-modulated immune signaling.

The influence of microenvironment on tumor immunotherapy

Tumor immunotherapy has achieved remarkable efficacy, with immune-checkpoint inhibitors as especially promising candidates for cancer therapy. However, some issues caused by immunotherapy have raised attention, such as limited efficacy for some patients, narrow antineoplastic spectrum, and adverse reactions, suggesting that using regulators of tumor immune response may prove to be more complicated than anticipated. Current evidence indicates that different factors collectively constituting the unique tumor microenvironment promote immune tolerance, and these include the expression of co-inhibitory molecules, the secretion of lactate, and competition for nutrients between tumor cells and immune cells. Furthermore, cancer-associated fibroblasts, the main cellular components of solid tumors, promote immunosuppression through inhibition of T cell function and extracellular matrix remodeling. Here, we summarize the research advances in tumor immunotherapy and the latest insights into the influence of microenvironment on tumor immunotherapy.

At the bench: Engineering the next generation of cancer vaccines

Cancer vaccines hold promise as an immunotherapeutic modality based on their potential to generate tumor antigen-specific T cell responses and long-lived antitumor responses capable of combating metastatic disease and recurrence. However, cancer vaccines have historically failed to deliver significant therapeutic benefit in the clinic, which we maintain is due in part to drug delivery challenges that have limited vaccine immunogenicity and efficacy. In this review, we examine some of the known and putative failure mechanisms of common first-generation clinical cancer vaccines, and describe how the rational design of materials engineered for vaccine delivery and immunomodulation can address these shortcomings. First, we outline vaccine design principles for augmenting cellular immunity to tumor antigens and describe how well-engineered materials can improve vaccine efficacy, highlighting recent innovations in vaccine delivery technology that are primed for integration into neoantigen vaccine development pipelines. We also discuss the importance of sequencing, timing, and kinetics in mounting effective immune responses to cancer vaccines, and highlight examples of materials that potentiate antitumor immunity through spatiotemporal control of immunomodulation. Furthermore, we describe several engineering strategies for improving outcomes of in situ cancer vaccines, which leverage local, intratumoral delivery to stimulate systemic immunity. Finally, we highlight recent innovations leveraging nanotechnology for increasing the immunogenicity of the tumor microenvironment (TME), which is critical to enhancing tumor infiltration and function of T cells elicited in response to cancer vaccines. These immunoengineering strategies and tools complement ongoing advances in cancer vaccines as they reemerge as an important component of the immunotherapeutic armamentarium.

The influence of microenvironment on tumor immunotherapy

Tumor immunotherapy has achieved remarkable efficacy, with immune-checkpoint inhibitors as especially promising candidates for cancer therapy. However, some issues caused by immunotherapy have raised attention, such as limited efficacy for some patients, narrow antineoplastic spectrum, and adverse reactions, suggesting that using regulators of tumor immune response may prove to be more complicated than anticipated. Current evidence indicates that different factors collectively constituting the unique tumor microenvironment promote immune tolerance, and these include the expression of co-inhibitory molecules, the secretion of lactate, and competition for nutrients between tumor cells and immune cells. Furthermore, cancer-associated fibroblasts, the main cellular components of solid tumors, promote immunosuppression through inhibition of T cell function and extracellular matrix remodeling. Here, we summarize the research advances in tumor immunotherapy and the latest insights into the influence of microenvironment on tumor immunotherapy.

Drug-free mannosylated liposomes inhibit tumor growth by promoting the polarization of tumor-associated macrophages

Background: Tumor-associated macrophages (TAMs) are critical in tumor progression and metastasis. Selective targeting of TAMs holds great potential to ameliorate the immunosuppressive tumor microenvironment and enhance the efficacy of antitumor therapy. Various liposomes have been developed to target TAMs via cell-specific surface receptors either to deplete or re-educate TAMs. Since immuno-stimulation often initiates with the interaction of nanocarriers with the innate immunity cells such as macrophages, the intrinsic impact of drug-free liposomes on macrophage activation and polarization via cell interaction is one of the most critical issues in nanomedicine for promoting effective immunotherapy.

Methods: In this study, conventional bare liposomes, PEGylated liposomes, and mannosylated liposomes were developed and the cytotoxicity, cellular internalization, immunostimulatory activity, targeting efficiency, antitumor efficacy, and mechanism were evaluated in vitro and in vivo.

Results: All liposomes displayed an ideal particle size, good biocompatibility, and controlled release behavior. Mannosylated liposomes exhibited superior in vitro cellular internalization and tumor spheroid penetration with the aid of the mannose receptor-mediated TAMs-targeting effects. In particular, mannosylated liposomes promoted the polarization of both M0 and M2 to the M1 phenotype by enhancing the expression ratio of CD86/CD206 in vitro. Of note, mannosylated liposomes could inhibit G422 glioma tumor growth, which may be attributed to the polarization of TAMs, as evidenced by the reduction in expression level of the TAMs surface marker.

Conclusion: These results indicate the potential value of mannosylated liposomes in the design of a rational delivery system to enhance the antitumor immune efficacy of immunomodulators by inducing a shift from the M2 to the M1 phenotype.