Targeted delivery of proapoptotic peptides to tumor-associated macrophages improves survival. Proc Natl Acad Sci U S A. 2013;110:15919-15924. [PMID: 24046373 DOI: 10.1073/pnas.1312197110]

Tumor-Associated Myeloid Cells Selective Delivery of a Therapeutic Tumor Nano-Vaccine for Overcoming Immune Barriers for Effective and Long-Term Cancer Immunotherapy

Therapeutic cancer vaccines have the potential to induce regression of established tumors, eradicate microscopic residual lesions, and prevent metastasis and recurrence, but their efficacy is limited by the low antigenicity of soluble antigens and the immunosuppressive tumor-associated macrophages (TAMs) that promote tumor growth. In this study, a novel strategy is reported for overcoming these defenses: a dual-targeting nano-vaccine (NV) based on hepatitis B core antigen (HBcAg) derived virus-like particles (VLPs), N-M2T-gp100 HBc NV, equipped with both SIGNR+ dendritic cells (DCs)/TAMs-targeting ability and high-density display of tumor-associated antigen (TAA). N-M2T-gp100 HBc NVs-based immunotherapy has demonstrated an optimal interaction between tumor-associated antigens (TAAs) and the immune composition of the tumor microenvironment. In a melanoma model, N-M2T-gp100 HBc VLPs significantly reducing in situ and abscopal tumor growth, and provide long-term immune protection. This remarkable anti-tumor effect is achieved by efficiently boosting of T cells and repolarizing of M2-like TAMs. This work opens exciting avenues for the development of personalized tumor vaccines targeting not just melanoma but potentially a broad range of cancer types based on functionalized VLPs.

Anti-ferroptosis exosomes engineered for targeting M2 microglia to improve neurological function in ischemic stroke

BACKGROUND

Stroke is a devastating disease affecting populations worldwide and is the primary cause of long-term disability. The inflammatory storm plays a crucial role in the progression of stroke. In the acute phase of ischemic stroke, there is a transient increase in anti-inflammatory M2 microglia followed by a rapid decline. Due to the abundant phospholipid in brain tissue, lipid peroxidation is a notable characteristic of ischemia/reperfusion (I/R), constituting a structural foundation for ferroptosis in M2 microglia. Slowing down the decrease in M2 microglia numbers and controlling the inflammatory microenvironment holds significant potential for enhancing stroke recovery.

RESULTS

We found that the ferroptosis inhibitor can modulate inflammatory response in MCAO mice, characterizing that the level of M2 microglia-related cytokines was increased. We then confirmed that different subtypes of microglia exhibit distinct sensitivities to I/R-induced ferroptosis. Adipose-derived stem cells derived exosome (ADSC-Exo) effectively decreased the susceptibility of M2 microglia to ferroptosis via Fxr2/Atf3/Slc7a11, suppressing the inflammatory microenvironment and promoting neuronal survival. Furthermore, through plasmid engineering, a more efficient M2 microglia-targeted exosome, termed M2pep-ADSC-Exo, was developed. In vivo and in vitro experiments demonstrated that M2pep-ADSC-Exo exhibits significant targeting specificity for M2 microglia, further inhibiting M2 microglia ferroptosis and improving neurological function in ischemic stroke mice.

CONCLUSION

Collectively, we illustrated a novel potential therapeutic mechanism that Fxr2 in ADSC-Exo could alleviate the M2 microglia ferroptosis via regulating Atf3/Slc7all expression, hence inhibiting the inflammatory microenvironment, improving neurofunction recovery in cerebral I/R injury. We obtained a novel exosome, M2pep-ADSC-Exo, through engineered modification, which exhibits improved targeting capabilities toward M2 microglia. This provides a new avenue for the treatment of stroke.

A Polymeric Nanoparticle to Co-Deliver Mitochondria-Targeting Peptides and Pt(IV) Prodrug: Toward High Loading Efficiency and Combination Efficacy

Developing combination chemotherapy systems with high drug loading efficiency at predetermined drug ratios to achieve a synergistic effect is important for cancer therapy. Herein, a polymeric dual-drug nanoparticle composed of a Pt(IV) prodrug derived from oxaliplatin and a mitochondria-targeting cytotoxic peptide is constructed through emulsion interfacial polymerization, which processes high drug loading efficiency and high biocompatibility. The depolymerization of polymeric dual-drug nanoparticle and the activation of Pt prodrug can be effectively triggered by the acidic tumor environment extracellularly and the high levels of glutathione intracellularly in cancer cells, respectively. The utilization of mitochondria-targeting peptide can inhibit ATP-dependent processes including drug efflux and DNA damage repair. This leads to increased accumulation of Pt-drugs within cancer cells. Eventually, the polymeric dual-drug nanoparticle demonstrates appreciable antitumor effects on both cell line derived and patient derived xenograft lung cancer model. It is highly anticipated that the polymeric dual-or multi-drug systems can be applied for combination chemotherapy to achieve enhanced anticancer activity and reduced side effects.

Cellular interactions in tumor microenvironment during breast cancer progression: new frontiers and implications for novel therapeutics

The breast cancer tumor microenvironment (TME) is dynamic, with various immune and non-immune cells interacting to regulate tumor progression and anti-tumor immunity. It is now evident that the cells within the TME significantly contribute to breast cancer progression and resistance to various conventional and newly developed anti-tumor therapies. Both immune and non-immune cells in the TME play critical roles in tumor onset, uncontrolled proliferation, metastasis, immune evasion, and resistance to anti-tumor therapies. Consequently, molecular and cellular components of breast TME have emerged as promising therapeutic targets for developing novel treatments. The breast TME primarily comprises cancer cells, stromal cells, vasculature, and infiltrating immune cells. Currently, numerous clinical trials targeting specific TME components of breast cancer are underway. However, the complexity of the TME and its impact on the evasion of anti-tumor immunity necessitate further research to develop novel and improved breast cancer therapies. The multifaceted nature of breast TME cells arises from their phenotypic and functional plasticity, which endows them with both pro and anti-tumor roles during tumor progression. In this review, we discuss current understanding and recent advances in the pro and anti-tumoral functions of TME cells and their implications for developing safe and effective therapies to control breast cancer progress.

Biomimetic "Gemini nanoimmunoregulators" orchestrated for boosted photoimmunotherapy by spatiotemporally modulating PD-L1 and tumor-associated macrophages

A novel strategy of not only stimulating the immune cycle but also modulating the immunosuppressive tumor microenvironment is of vital importance to efficient cancer immunotherapy. Here, a new type of spatiotemporal biomimetic "Gemini nanoimmunoregulators" was engineered to activate robust systemic photoimmunotherapy by integrating the triple-punch of amplified immunogenic cell death (ICD), tumor-associated macrophages (TAMs) phenotype reprogramming and programmed cell death ligand 1 (PD-L1) degradation. The "Gemini nanoimmunoregulators" PM@RM-T7 and PR@RM-M2 were constructed by taking the biocompatible mesoporous polydopamine (mPDA) as nanovectors to deliver metformin (Met) and toll-like receptor 7/8 agonist resiquimod (R848) to cancer cells and TAMs by specific biorecognition via wrapping of red blood cell membrane (RM) inlaid with T7 or M2 peptides. mPDA/Met@RM-T7 (abbreviated as PM@RM-T7) was constructed to elicit an amplified in situ ICD effect through the targeted PTT and effectively stimulated the anticancer immunity. Meanwhile, PD-L1 on the remaining cancer cells was degraded by the burst metformin to prevent immune evasion. Subsequently, mPDA/R848@RM-M2 (abbreviated as PR@RM-M2) specifically recognized TAMs and reset the phenotype from M2 to M1 state, thus disrupting the immunosuppressive microenvironment and further boosting the function of cytotoxic T lymphocytes. This pair of sister nanoimmunoregulators cooperatively orchestrated the comprehensive anticancer activity, which remarkably inhibited the growth of primary and distant 4T1 tumors and prevented malignant metastasis. This study highlights the spatiotemporal cooperative modalities using multiple nanomedicines and provides a new paradigm for efficient cancer immunotherapy against metastatic-prone tumors.

Melanoma immunotherapy enabled by M2 macrophage targeted immunomodulatory cowpea mosaic virus

We have developed nanoparticle formulations targeting M2 macrophages for cancer immunotherapy by conjugating high-affinity binding peptides to cowpea mosaic virus as an immunostimulatory adjuvant. We confirmed the targeting of and uptake by M2 macrophages in vitro and the therapeutic efficacy of the nanoparticles against murine melanoma in vivo.

Nanoparticle-Based Immunotherapy for Reversing T-Cell Exhaustion

T-cell exhaustion refers to a state of T-cell dysfunction commonly observed in chronic infections and cancer. Immune checkpoint molecules blockading using PD-1 and TIM-3 antibodies have shown promising results in reversing exhaustion, but this approach has several limitations. The treatment of T-cell exhaustion is still facing great challenges, making it imperative to explore new therapeutic strategies. With the development of nanotechnology, nanoparticles have successfully been applied as drug carriers and delivery systems in the treatment of cancer and infectious diseases. Furthermore, nanoparticle-based immunotherapy has emerged as a crucial approach to reverse exhaustion. Here, we have compiled the latest advances in T-cell exhaustion, with a particular focus on the characteristics of exhaustion that can be targeted. Additionally, the emerging nanoparticle-based delivery systems were also reviewed. Moreover, we have discussed, in detail, nanoparticle-based immunotherapies that aim to reverse exhaustion, including targeting immune checkpoint blockades, remodeling the tumor microenvironment, and targeting the metabolism of exhausted T cells, etc. These data could aid in comprehending the immunopathogenesis of exhaustion and accomplishing the objective of preventing and treating chronic diseases or cancer.

Spatial targeting of fibrosis-promoting macrophages with nanoscale metal-organic frameworks for idiopathic pulmonary fibrosis therapy

Targeted delivery of therapeutic drugs to fibrosis-promoting macrophages (FPMs) holds promise as a challenging yet effective approach for the treatment of idiopathic pulmonary fibrosis (IPF). Here, nanocarriers composed of Mn-curcumin metal-organic frameworks (MOFs) were utilized to deliver the immune inhibitor BLZ-945 to the lungs, with the goal of depleting fibrosis-promoting macrophages (FPMs) from fibrotic lung tissues. FPM targeting was achieved by functionalizing the nanocarrier surface with an M2-like FPM binding peptide (M2pep). As a result, significant therapeutic benefits were observed through the successful depletion of approximately 80 % of the M2-like macrophages (FPMs) in a bleomycin-induced fibrosis mouse model treated with the designed M2-like FPM-targeting nanoparticle (referred to as M2NP-BLZ@Mn-Cur). Importantly, the released Mn2+ and curcumin after the degradation of M2NP-BLZ@Mn-Cur accumulated in the fibrotic lung tissue, which can alleviate inflammation and oxidative stress reactions, thereby further improving IPF therapy. This study presents a novel strategy with promising prospects for molecular-targeted fibrosis therapy. STATEMENT OF SIGNIFICANCE: Metal-organic frameworks (MOFs)- based nanocarriers equipped with both fibrosis-promoting macrophage (FPM)-specific targeting ability and therapeutic drugs are appealing for pulmonary fibrosis treatment. Here, we prepared M2pep (an M2-like FPM binding peptide)-modified and BLZ945 (a small molecule inhibitor of CSF1/CSF-1R axis)-loaded Mn-curcumin MOF nanoparticles (M2NP-BLZ@Mn-Cur) for pulmonary fibrosis therapy. The functionalized M2NP-BLZ@Mn-Cur nanoparticles can be preferentially taken up by FPMs, resulting in their depletion from fibrotic lung tissues. In addition, Mn2+and curcumin released from the nanocarriers have anti-inflammation and immune regulation effects, which further enhance the antifibrotic effect of the nanoparticles.

Multifunctional nanocomposites modulating the tumor microenvironment for enhanced cancer immunotherapy

Cancer immunotherapy has gained momentum for treating malignant tumors over the past decade. Checkpoint blockade and chimeric antigen receptor cell therapy (CAR-T) have shown considerable potency against liquid and solid cancers. However, the tumor microenvironment (TME) is highly immunosuppressive and hampers the effect of currently available cancer immunotherapies on overall treatment outcomes. Advancements in the design and engineering of nanomaterials have opened new avenues to modulate the TME. Progress in the current nanocomposite technology can overcome immunosuppression and trigger robust immunotherapeutic responses by integrating synergistic functions of different molecules. We will review recent advancements in nanomedical applications and discuss specifically designed nanocomposites modulating the TME for cancer immunotherapy. In addition, we provide information on the current landscape of clinical-stage nanocomposites for cancer immunotherapy.

Advancements in Macrophage-Targeted Drug Delivery for Effective Disease Management

Macrophages play a crucial role in tissue homeostasis and the innate immune system. They perform essential functions such as presenting antigens, regulating cytokines, and responding to inflammation. However, in diseases like cancer, cardiovascular disorders, and autoimmune conditions, macrophages undergo aberrant polarization, which disrupts tissue regulation and impairs their normal behavior. To address these challenges, there has been growing interest in developing customized targeted drug delivery systems specifically designed for macrophage-related functions in different anatomical locations. Nanomedicine, utilizing nanoscale drug systems, offers numerous advantages including improved stability, enhanced pharmacokinetics, controlled release kinetics, and precise temporal drug delivery. These advantages hold significant promise in achieving heightened therapeutic efficacy, specificity, and reduced side effects in drug delivery and treatment approaches. This review aims to explore the roles of macrophages in major diseases and present an overview of current strategies employed in targeted drug delivery to macrophages. Additionally, this article critically evaluates the design of macrophage-targeted delivery systems, highlighting limitations and discussing prospects in this rapidly evolving field. By assessing the strengths and weaknesses of existing approaches, we can identify areas for improvement and refinement in macrophage-targeted drug delivery.

M2pep-Modified Cyclodextrin-siRNA Nanoparticles Modulate the Immunosuppressive Tumor Microenvironment for Prostate Cancer Therapy

Prostate cancer (PCa) is the most prevalent cause of cancer deaths in men. Conventional strategies, such as surgery, radiation, or chemotherapy, face challenges including poor prognosis and resistance. Therefore, the development of new improved strategies is vital to enhance patient outcomes. Recently, immunotherapy has shown potential in the treatment of a range of cancers, including PCa. Tumor-associated macrophages (TAMs) play an important role in the tumor microenvironment (TME) and reprogramming of TAMs is associated with remodeling the TME. The colony-stimulating factor-1/colony stimulating factor-1 receptor (CSF-1/CSF-1R) signaling pathway is closely related to the polarization of TAMs. The downregulation of CSF-1R, using small interfering RNA (siRNA), has been shown to achieve the reprogramming of TAMs, from the immunosuppressive M2 phenotype to the immunostimulatory M1 one. To maximize specific cellular delivery an M2 macrophage-targeting peptide, M2pep, was formulated with an amphiphilic cationic β-Cyclodextrin (CD) incorporating CSF-1R siRNA. The resulting nanoparticles (NPs) increased M2 macrophage targeting both in vitro and in vivo, promoting the release of M1 factors and simultaneously downregulating the levels of M2 factors through TAM reprogramming. The subsequent remodeling of the TME resulted in a reduction in tumor growth in a subcutaneous PCa mouse model mainly mediated through the recruitment of cytotoxic T cells. In summary, this M2pep-targeted CD-based delivery system demonstrated significant antitumor efficacy, thus presenting an alternative immunotherapeutic strategy for PCa treatment.

The Streptococcus virulence protein PepO triggers anti-tumor immune responses by reprograming tumor-associated macrophages in a mouse triple negative breast cancer model

BACKGROUND

The efficacy of current surgery and chemotherapy for triple negative breast cancer (TNBC) is limited due to heterogenous and immunosuppressive tumor microenvironment (TME). Tumor associated macrophages (TAMs), which are regarded as an M2 tumor-promoting phenotype, are crucial in the development of the immunosuppressive TME. Targeting TAM reprograming is a promising strategy in anti-tumor therapy since reprogramming techniques provide the opportunity to actively enhance the antitumor immunological activity of TAM in addition to eliminating their tumor-supportive roles, which is rarely applied in TNBC clinically. However, how to drive M2 macrophages reprogramming into M1 with high potency remains a challenge and the molecular mechanisms how M2 macrophages polarized into M1 are poorly understood. Here, we identified a new immunoregulatory molecular PepO that was served as an immunoregulatory molecule governed the transformation of tumor-promoting M2 to tumor-inhibitory M1 cells and represented an effective anti-tumor property.

RESULTS

At the present study, we identified a new immunoregulatory molecular PepO, as a harmless immunoregulatory molecule, governed the transformation of tumor-promoting M2 to tumor-inhibitory M1 cells efficiently. PepO-primed M2 macrophages decreased the expression of tumor-supportive molecules like Arg-1, Tgfb, Vegfa and IL-10, and increased the expression of iNOS, Cxcl9, Cxcl10, TNF-α and IL-6 to inhibit TNBC growth. Moreover, PepO enhanced the functions of macrophages related to cell killing, phagocytosis and nitric oxide biosynthetic process, thereby inhibiting the development of tumors in vivo and in vitro. Mechanistically, PepO reprogramed TAMs toward M1 by activating PI3K-AKT-mTOR pathway via TLR4 and suppressed the function of M2 by inhibiting JAK2-STAT3 pathway via TLR2. The PI3K inhibitor LY294002 abrogated the role of PepO in switching M2 macrophages into M1 and in inhibiting TNBC growth in vivo. And PepO failed to govern the M2 macrophages to reprogram into M1 macrophages and inhibit TNBC when TLR2 or TLR4 was deficient. Moreover, PepO enhanced the antitumor activity of doxorubicin and the combination exerted a synergistic effect on TNBC suppression.

CONCLUSIONS

Our research identified a possible macrophage-based TNBC immunotherapeutic approach and suggested a novel anticancer immunoregulatory molecular called PepO.

Targeting and repolarizing M2-like tumor-associated macrophage-mediated MR imaging and tumor immunotherapy by biomimetic nanoparticles

Anti-tumor M1-like and pro-tumor M2-like tumor-associated macrophages (TAMs) coexist in tumor microenvironments (TME). The adverse effects of these M1/M2 subsets on tumors directly affect the current strategies to improve anti-tumor immune response. Therefore, it has attracted great attention to change the tumor immunosuppressive microenvironment by reprogramming TAMs. In this paper, we constructed biomimetic nanoparticles (HMMDN-Met@PM) targeting M2-like TAMs for macrophage re-polarization. In detail, the core of the biomimetic nanoparticles is metformin-loaded hollow mesoporous manganese dioxide nanoparticles (HMMDN-Met). Benefited from the hollow and porous structure of HMMDN, metformin, the regulator of M1/M2 adopted in this work, can be easily and widely loaded into HMMDN. Moreover, macrophage membranes were utilized for HMMDN-Met coating (HMMDN-Met@MM) to prevent the premature drug leakage and provide specific molecular recognition/TME targeting. In addition, M2 macrophage targeting peptide (M2pep) was modified on the surface of macrophage membrane to specifically deliver the drug to M2-like TAMs to promote the polarization of M2 to M1 macrophages. Through in vitro and in vivo studies, we found that the expression of surface markers and inflammatory factors CD206, Arg-1 and IL-10 of type M2 macrophages decreased, while the surface markers of type M1 macrophages and the expression of inflammatory factors CD80, TNF-α and iNOS increased, indicating the successful re-polarization of M2 macrophages and finally realizing the inhibition of tumor growth. At the same time, under the acidic and GSH conditions of tumor, HMMDN was decomposed into Mn2+, which is a contrast agent for magnetic resonance imaging, thus realizing the tracking of tumor. This work practices biomimetic nanosystem in targeted imaging and immunotherapy, paving the way for strategy designing for tumor inhibition.

Improving the efficacy of peptide vaccines in cancer immunotherapy

Peptide vaccines have shown great potential in cancer immunotherapy by targeting tumor antigens and activating the patient's immune system to mount a specific response against cancer cells. However, the efficacy of peptide vaccines in inducing a sustained immune response and achieving clinical benefit remains a major challenge. In this review, we discuss the current status of peptide vaccines in cancer immunotherapy and strategies to improve their efficacy. We summarize the recent advancements in the development of peptide vaccines in pre-clinical and clinical settings, including the use of novel adjuvants, neoantigens, nano-delivery systems, and combination therapies. We also highlight the importance of personalized cancer vaccines, which consider the unique genetic and immunological profiles of individual patients. We also discuss the strategies to enhance the immunogenicity of peptide vaccines such as multivalent peptides, conjugated peptides, fusion proteins, and self-assembled peptides. Although, peptide vaccines alone are weak immunogens, combining peptide vaccines with other immunotherapeutic approaches and developing novel approaches such as personalized vaccines can be promising methods to significantly enhance their efficacy and improve the clinical outcomes for cancer patients.

The effect of m2 peptide targeted nanoliposomes containing crocin on induction of phenotypic change in tumor macrophages to M1 state

AIMS

Crocin has immunomodulatory and anticancer effects. In this study, crocin was used to induce the M1 phenotype in mouse tumor macrophages.

MAIN METHODS

A targeted liposomal formulation with m2 peptide was prepared and characterized to deliver crocin to the M2 macrophages present in the tumor environment. RT-qPCR and IHC were performed for in vitro and in vivo (in C26 colon carcinoma mouse model at a dose of 50 mg/kg) assessment of M1 induction, respectively.

KEY FINDINGS

In vitro results indicated that liposome modified with m2 peptide was non-toxic to macrophages and had an improved uptake by macrophages compared to the non-targeted formulation and induced M1 phenotype through an IL6-independent pathway. M2 peptide- modified liposome showed considerable tumor accumulation and anti-tumor effects and significantly shifted the phenotype of tumor macrophages towards an anti-tumor M1 phenotype.

SIGNIFICANCE

Probably the remarkable anti-tumor responses observed in this study with m2 peptide-targeted liposomal formulations containing crocin were due to the enhanced delivery of crocin to the tumor macrophage and the subsequent initiation of anti-tumor immune responses.

Cell microparticles loaded with tumor antigen and resiquimod reprogram tumor-associated macrophages and promote stem-like CD8+ T cells to boost anti-PD-1 therapy

The durable response rate to immune checkpoint blockade such as anti-programmed cell death-1 (PD-1) antibody remains relatively low in hepatocellular carcinoma (HCC), mainly depending on an immunosuppressive microenvironment with limited number of CD8+ T cells, especially stem-like CD8+ T cells, in tumor tissues. Here we develop engineered microparticles (MPs) derived from alpha-fetoprotein (AFP)-overexpressing macrophages to load resiquimod (R848@M2pep-MPsAFP) for enhanced anti-PD-1 therapy in HCC. R848@M2pep-MPsAFP target and reprogram immunosuppressive M2-like tumor-associated macrophages (TAMs) into M1-like phenotype. Meanwhile, R848@M2pep-MPsAFP-reprogrammed TAMs act as antigen-presenting cells, not only presenting AFP antigen to activate CD8+ T cell-mediated antitumor immunity, but also providing an intra-tumoral niche to maintain and differentiate stem-like CD8+ T cells. Combination immunotherapy with anti-PD-1 antibody generates strong antitumor immune memory and induces abundant stem-like CD8+ T cell proliferation and differentiation to terminally exhausted CD8+ T cells for long-term immune surveillance in orthotopic and autochthonous HCC preclinical models in male mice. We also show that the R848-loaded engineered MPs derived from macrophages overexpressing a model antigen ovalbumin (OVA) can improve anti-PD-1 therapy in melanoma B16-OVA tumor-bearing mice. Our work presents a facile and generic strategy for personalized cancer immunotherapy to boost anti-PD-1 therapy.

Chimeric Peptide Engineered Bioregulator for Metastatic Tumor Immunotherapy through Macrophage Polarization and Phagocytosis Restoration

Tumor-associated macrophages (TAMs) are the most abundant immune cells in solid tumor tissues, which restrict antitumor immunity by releasing tumor-supporting cytokines and attenuating phagocytosis behaviors. In this work, a chimeric peptide engineered bioregulator (ChiP-RS) is constructed for tumor immunotherapy through macrophage polarization and phagocytosis restoration. ChiP-RS is fabricated by utilizing macrophage-targeting chimeric peptide (ChiP) to load Toll-like receptor agonists (R848) and Src homology 2 (SH2) domain-containing protein tyrosine phosphatase 2 (SHP-2) inhibitor (SHP099). Among which, ChiP-RS prefers to be internalized by TAMs, repolarizing M2 macrophages into M1 macrophages to reverse the immunosuppressive microenvironment. In addition, SHP-2 can be downregulated to promote phagocytotic elimination behaviors of M1 macrophages, which will also activate T cell-based antitumor immunity for metastatic tumor therapy. In vitro and in vivo findings demonstrate a superior suppression effect of ChiP-RS against metastatic tumors without systemic side effects. Such a simple but effective nanoplatform provides sophisticated synergism for immunotherapy, which may facilitate the development of translational nanomedicine for metastatic tumor treatment.

Tumor-associated macrophages in nanomaterial-based anti-tumor therapy: as target spots or delivery platforms

Targeting tumor-associated macrophages (TAMs) has emerged as a promising approach in cancer therapy. This article provides a comprehensive review of recent advancements in the field of nanomedicines targeting TAMs. According to the crucial role of TAMs in tumor progression, strategies to inhibit macrophage recruitment, suppress TAM survival, and transform TAM phenotypes are discussed as potential therapeutic avenues. To enhance the targeting capacity of nanomedicines, various approaches such as the use of ligands, immunoglobulins, and short peptides are explored. The utilization of live programmed macrophages, macrophage cell membrane-coated nanoparticles and macrophage-derived extracellular vesicles as drug delivery platforms is also highlighted, offering improved biocompatibility and prolonged circulation time. However, challenges remain in achieving precise targeting and controlled drug release. The heterogeneity of TAMs and the variability of surface markers pose hurdles in achieving specific recognition. Furthermore, the safety and clinical applicability of these nanomedicines requires further investigation. In conclusion, nanomedicines targeting TAMs hold great promise in cancer therapy, offering enhanced specificity and reduced side effects. Addressing the existing limitations and expanding our understanding of TAM biology will pave the way for the successful translation of these nano-therapies into clinical practice.

Cell-targeted vaccines: implications for adaptive immunity

Recent advancements in immunology and chemistry have facilitated advancements in targeted vaccine technology. Targeting specific cell types, tissue locations, or receptors can allow for modulation of the adaptive immune response to vaccines. This review provides an overview of cellular targets of vaccines, suggests methods of targeting and downstream effects on immune responses, and summarizes general trends in the literature. Understanding the relationships between vaccine targets and subsequent adaptive immune responses is critical for effective vaccine design. This knowledge could facilitate design of more effective, disease-specialized vaccines.

Phage for cancer therapy

Cancer is currently a global health challenge, characterized by dysfunction of organs due to the uncontrolled growth of cells exponentially. The therapies used to treat cancer in patients so far are widely used. However, there are also some problems, such as the high cost of surgery and chemotherapy. Thus, there are many barriers to care for patients with cancer, especially in low and middle-income countries. In addition, the many risks and adverse effects of radiation treatment. Therefore, to reduce mortality in patients with the disease, we need a newer therapy with more targeted treatment, fewer side effects, and cheaper cost. The application of bacteria in cancer treatment was first developed in 1983. Currently, this therapy is attracting the attention of scientists due to its great potential in cancer treatment. This chapter discusses the successful research on the bacteriophage for cancer, the mechanism and its potential. In addition, some types of bacteria that are most important for cancer treatment and limitations on the widespread application of this therapy were also mentioned. Reviewing all the researches on bacteriotherapy in cancer are essential to increase the knowledge in this area and make this therapy more optimal in the future.

Macrophage-Based Therapeutic Strategies in Hematologic Malignancies

Macrophages are types of immune cells, with ambivalent functions in tumor growth, which depend on the specific environment in which they reside. Tumor-associated macrophages (TAMs) are a diverse population of immunosuppressive myeloid cells that play significant roles in several malignancies. TAM infiltration in malignancies has been linked to a poor prognosis and limited response to treatments, including those using checkpoint inhibitors. Understanding the precise mechanisms through which macrophages contribute to tumor growth is an active area of research as targeting these cells may offer potential therapeutic approaches for cancer treatment. Numerous investigations have focused on anti-TAM-based methods that try to eliminate, rewire, or target the functional mediators released by these cells. Considering the importance of these strategies in the reversion of tumor resistance to conventional therapies and immune modulatory vaccination could be an appealing approach for the immunosuppressive targeting of myeloid cells in the tumor microenvironment (TME). The combination of reprogramming and TAM depletion is a special feature of this approach compared to other clinical strategies. Thus, the present review aims to comprehensively overview the pleiotropic activities of TAMs and their involvement in various stages of cancer development as a potent drug target, with a focus on hematologic tumors.

d-lactate modulates M2 tumor-associated macrophages and remodels immunosuppressive tumor microenvironment for hepatocellular carcinoma

The polarization of tumor-associated macrophages (TAMs) from M2 to M1 phenotype demonstrates great potential for remodeling the immunosuppressive tumor microenvironment (TME) of hepatocellular carcinoma (HCC). d-lactate (DL; a gut microbiome metabolite) acts as an endogenous immunomodulatory agent that enhances Kupffer cells for clearance of pathogens. In this study, the potential of DL for transformation of M2 TAMs to M1 was confirmed, and the mechanisms underlying such polarization were mainly due to the modulation of phosphatidylinositol 3-kinase/protein kinase B pathway. A poly(lactide-co-glycolide) nanoparticle (NP) was used to load DL, and the DL-loaded NP was modified with HCC membrane and M2 macrophage-binding peptide (M2pep), forming a nanoformulation (DL@NP-M-M2pep). DL@NP-M-M2pep transformed M2 TAMs to M1 and remodeled the immunosuppressive TME in HCC mice, promoting the efficacy of anti-CD47 antibody for long-term animal survival. These findings reveal a potential TAM modulatory function of DL and provide a combinatorial strategy for HCC immunotherapy.

Cracking the code: Deciphering the role of the tumor microenvironment in osteosarcoma metastasis

Osteosarcoma (OS) is the most common malignant bone tumor in children and adolescents. It is characterized by a rapid progression, poor prognosis, and early pulmonary metastasis. Over the past 30 years, approximately 85% of patients with osteosarcoma have experienced metastasis. The five-year survival of patients with lung metastasis during the early stages of treatment is less than 20%. The tumor microenvironment (TME) not only provides conditions for tumor cell growth but also releases a variety of substances that can promote the metastasis of tumor cells to other tissues and organs. Currently, there is limited research on the role of the TME in osteosarcoma metastasis. Therefore, to explore methods for regulating osteosarcoma metastasis, further investigations must be conducted from the perspective of the TME. This will help to identify new potential biomarkers for predicting osteosarcoma metastasis and assist in the discovery of new drugs that target regulatory mechanisms for clinical diagnosis and treatment. This paper reviews the research progress on the mechanism of osteosarcoma metastasis based on TME theory, which will provide guidance for the clinical treatment of osteosarcoma.

Evolving strategies and application of proteins and peptide therapeutics in cancer treatment

Several proteins and peptides have therapeutic potential and can be used for cancer therapy. By binding to cell surface receptors and other indicators uniquely linked with or overexpressed on tumors compared to healthy tissue, protein biologics enhance the active targeting of cancer cells, as opposed to the passive targeting of cells by conventional small-molecule chemotherapeutics. This study focuses on peptide medications that exist to slow or stop tumor growth and the spread of cancer, demonstrating the therapeutic potential of peptides in cancer treatment. As an alternative to standard chemotherapy, peptides that selectively kill cancer cells while sparing healthy tissue are developing. A mountain of clinical evidence supports the efficacy of peptide-based cancer vaccines. Since a single treatment technique may not be sufficient to produce favourable results in the fight against cancer, combination therapy is emerging as an effective option to generate synergistic benefits. One example of this new area is the use of anticancer peptides in combination with nonpeptidic cytotoxic drugs or the combination of immunotherapy with conventional therapies like radiation and chemotherapy. This review focuses on the different natural and synthetic peptides obtained and researched. Discoveries, manufacture, and modifications of peptide drugs, as well as their contemporary applications, are summarized in this review. We also discuss the benefits and difficulties of potential advances in therapeutic peptides.

Tumor-Associated Macrophage Subsets: Shaping Polarization and Targeting

The tumor microenvironment (TME) is a critical regulator of tumor growth, progression, and metastasis. Among the innate immune cells recruited to the tumor site, macrophages are the most abundant cell population and are present at all stages of tumor progression. They undergo M1/M2 polarization in response to signals derived from TME. M1 macrophages suppress tumor growth, while their M2 counterparts exert pro-tumoral effects by promoting tumor growth, angiogenesis, metastasis, and resistance to current therapies. Several subsets of the M2 phenotype have been observed, often denoted as M2a, M2b, M2c, and M2d. These are induced by different stimuli and differ in phenotypes as well as functions. In this review, we discuss the key features of each M2 subset, their implications in cancers, and highlight the strategies that are being developed to harness TAMs for cancer treatment.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Immunogenic cell death inducer peptides: A new approach for cancer therapy, current status and future perspectives

Immunogenic Cell Death (ICD) is a type of cell death that kills tumor cells by stimulating the adaptive immune response against other tumor cells. ICD depends on the endoplasmic reticulum (ER) stress and the secretion of Damage-Associated Molecular Patterns (DAMP) by the dying tumor cell. DAMPs recruit innate immune cells such as Dendritic Cells (DC), triggering a cancer-specific immune response such as cytotoxic T lymphocytes (CTLs) to eliminate remaining cancer cells. ICD is accompanied by several hallmarks in dying cells, such as surface translocation of ER chaperones, calreticulin (CALR), and extracellular secretion of DAMPs such as high mobility group protein B1 (HMGB1) and adenosine triphosphate (ATP). Therapeutic peptides can kill bacteria and tumor cells thus affecting the immune system. They have high specificity and affinity for their targets, small size, appropriate cell membrane penetration, short half-life, and simple production processes. Peptides are interesting agents for immunomodulation since they may overcome the limitations of other therapeutics. Thus, the development of peptides affecting the TME and active antitumoral immunity has been actively pursued. On the other hand, several peptides have been recently identified to trigger ICD and anti-cancer responses. In the present review, we review previous studies on peptide-induced ICD, their mechanism, their targets, and markers. They include anti-microbial peptides (AMPs), cationic or mitochondrial targeting, checkpoint inhibitors, antiapoptotic inhibitors, and "don't eat me" inhibitor peptides. Also, peptides will be investigated potentially inducing ICD that is divided into ER stressors, ATPase inhibitors, and anti-microbial peptides.

Emerging advances in engineered macrophages for tumor immunotherapy

Macrophages are versatile antigen-presenting cells. Recent studies suggest that engineered modifications of macrophages may confer better tumor therapy. Genetic engineering of macrophages with specific chimeric antigen receptors offers new possibilities for treatment of solid tumors and has received significant attention. In vitro gene editing of macrophages and infusion into the body can inhibit the immunosuppressive effect of the tumor microenvironment in solid tumors. This strategy is flexible and can be applied to all stages of cancer treatment. In contrast, nongenetic engineering tools are used to block relevant signaling pathways in immunosuppressive responses. In addition, macrophages can be loaded with drugs and engineered into cellular drug delivery systems. Here, we analyze the effect of the chimeric antigen receptor platform on macrophages and other existing engineering modifications of macrophages, highlighting their status, challenges and future perspectives. Indeed, our analyses show that new approaches in the treatment of solid tumors will likely exploit macrophages, an innate immune cell.

Peptide-assembled nanoparticles targeting tumor cells and tumor microenvironment for cancer therapy

Tumor cells and corrupt stromal cells in the tumor microenvironment usually overexpress cancer-specific markers that are absent or barely detectable in normal cells, providing available targets for inhibiting the occurrence and development of cancers. It is noticeable that therapeutic peptides are emerging in cancer therapies and playing more and more important roles. Moreover, the peptides can be self-assembled and/or incorporated with polymeric molecules to form nanoparticles via non-covalent bond, which have presented appealing as well as enhanced capacities of recognizing targeted cells, responding to microenvironments, mediating internalization, and achieving therapeutic effects. In this review, we will introduce the peptide-based nanoparticles and their application advances in targeting tumor cells and stromal cells, including suppressive immune cells, fibrosis-related cells, and angiogenic vascular cells, for cancer therapy.

PTN-PTPRZ1 signaling axis blocking mediates tumor microenvironment remodeling for enhanced glioblastoma treatment

Glioblastoma (GBM) is a malignant brain tumor with a poor prognosis that is highly heterogeneous and invasive. One of the most major challenges of GBM treatment in the clinic is the blood-brain barrier (BBB). Additionally, the tumor microenvironment (TME) is highly enriched with immunosuppressed M2-like tumor-associated macrophages (M2 TAMs) and glioblastoma stem cells (GSCs), which promoted the malignancy of GBM through the PTN-PTPRZ1 signaling axis. Here, we developed a self-assembled dual-targeted hybrid micelle (DT-GM1) as a nanocarrier to deliver the chemotherapeutic agent doxorubicin (DOX). We demonstrated that this DT-GM1/DOX can cross the BBB using in vitro and in vivo GBM models, and that M2pep and PTPRZ1 antibodies allow it to precisely target the tumor microenvironment where M2 TAMs and GSCs are enriched, increasing intracellular drug accumulation via multiple internalization pathways. Additionally, simultaneous elimination of M2 TAMs and GSCs blocked the PTN-PTPRZ1 signaling axis, resulting in less M2 TAM infiltration and increased polarization to the M1 phenotype, reshaping the immune microenvironment. Overall, we have established a nanocarrier that can penetrate the BBB and target the TME while also synergizing with GBM chemotherapeutic agents, providing a promising new strategy for GBM treatment.

Engineered nanomedicines to overcome resistance of pancreatic cancer to immunotherapy

Pancreatic cancer (PC) is a highly aggressive malignant type of cancer. Although immunotherapy has been successfully used for treatment of many cancer types, many challenges limit its success in PC. Therefore, nanomedicines were engineered to enhance the responsiveness of PC cells to immune checkpoint inhibitors (ICIs). In this review, we highlight recent advances in engineering nanomedicines to overcome PC immune resistance. Nanomedicines were used to increase the immunogenicity of PC cells, inactivate stromal cancer-associated fibroblasts (CAFs), enhance the antigen-presenting capacity of dendritic cells (DCs), reverse the highly immunosuppressive nature of the tumor microenvironment (TME), and, hence, improve the infiltration of cytotoxic T lymphocytes (CTLs), resulting in efficient antitumor immune responses.

Reprogramming tumor-associated macrophages as a unique approach to target tumor immunotherapy

In the last ten years, it has become increasingly clear that tumor-infiltrating myeloid cells drive not just carcinogenesis via cancer-related inflammatory processes, but also tumor development, invasion, and metastasis. Tumor-associated macrophages (TAMs) in particular are the most common kind of leucocyte in many malignancies and play a crucial role in establishing a favorable microenvironment for tumor cells. Tumor-associated macrophage (TAM) is vital as the primary immune cell subset in the tumor microenvironment (TME).In order to proliferate and spread to new locations, tumors need to be able to hide from the immune system by creating an immune-suppressive environment. Because of the existence of pro-tumoral TAMs, conventional therapies like chemotherapy and radiotherapy often fail to restrain cancer growth. These cells are also to blame for the failure of innovative immunotherapies premised on immune-checkpoint suppression. Understanding the series of metabolic changes and functional plasticity experienced by TAMs in the complex TME will help to use TAMs as a target for tumor immunotherapy and develop more effective tumor treatment strategies. This review summarizes the latest research on the TAMs functional status, metabolic changes and focuses on the targeted therapy in solid tumors.

Design of Nanoparticles in Cancer Therapy Based on Tumor Microenvironment Properties

Cancer is one of the leading causes of death worldwide, and battling cancer has always been a challenging subject in medical sciences. All over the world, scientists from different fields of study try to gain a deeper knowledge about the biology and roots of cancer and, consequently, provide better strategies to fight against it. During the past few decades, nanoparticles (NPs) have attracted much attention for the delivery of therapeutic and diagnostic agents with high efficiency and reduced side effects in cancer treatment. Targeted and stimuli-sensitive nanoparticles have been widely studied for cancer therapy in recent years, and many more studies are ongoing. This review aims to provide a broad view of different nanoparticle systems with characteristics that allow them to target diverse properties of the tumor microenvironment (TME) from nanoparticles that can be activated and release their cargo due to the specific characteristics of the TME (such as low pH, redox, and hypoxia) to nanoparticles that can target different cellular and molecular targets of the present cell and molecules in the TME.

Morphological Transformation and In Situ Polymerization of Caspase-3 Responsive Diacetylene-Containing Lipidated Peptide Amphiphile for Self-Amplified Cooperative Antitumor Therapy

In order to artificially regulate cell behaviors, intracellular polymerization as an emerging chemical technique has attracted much attention. Yet, it is still a challenge to achieve effective intracellular polymerization to conquer tumors in the complex cellular environment. Herein, this work develops a tumor-targeting and caspase-3 responsive nanoparticle composed of a diacetylene-containing lipidated peptide amphiphile and mitochondria-targeting photosensitizer (C3), which undergoes nanoparticle-to-nanofiber transformation and efficient in situ polymerization triggered by photodynamic treatment and activation of caspase-3. The locational nanofibers on the mitochondria membranes lead to mitochondrial reactive oxygen species (mtROS) burst and self-amplified circulation, offering persistent high oxidative stress to induce cell apoptosis. This study provides a strategy for greatly enhanced antitumor therapeutic efficacy through mtROS burst and self-amplified circulation induced by intracellular transformation and in situ polymerization.

Peptide-Based [68Ga]Ga Labeled PET Tracer for Tumor Imaging by Targeting Tumor-Associated Macrophages

Tumor-associated macrophages (TAMs) are known to promote cancer development and metastasis. In this study, a TAMs-targeting peptide named M2pep was selected to investigate the feasibility of [68Ga]Ga-labeled M2pep as a noninvasive probe in targeted TAMs imaging. The peptide M2pep was conjugated with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and radiolabeled with 68Ga. The cellular uptake and binding assay were assessed in M2 macrophages and in the B16F10 cell line. Micro-PET imaging and a biodistribution study were performed on B16F10 tumor-bearing mice. High radiochemical purity [68Ga]Ga-DOTA-M2pep (>95%) was prepared and was stabilized in saline and bovine serum at 37 °C for 2 h. In vitro studies demonstrated high uptake of [68Ga]Ga-DOTA-M2pep in M2 macrophages, which was effectively blocked by the “cold” M2pep (free peptide). The micro-PET imaging and biodistribution study revealed that [68Ga]Ga-DOTA-M2pep reached the tumor site rapidly and showed high accumulation in the tumor at 1 h post-injection. In addition, the probe was rapidly cleared from the blood and mainly excreted via the kidneys, resulting in a high tumor/background ratio. Preclinical studies have shown that [68Ga]Ga-DOTA-M2pep specifically targets TAMs and might be a promising molecular probe for the noninvasive visualization of TAMs expression.

Gut Microbiota and Tumor Immune Escape: A New Perspective for Improving Tumor Immunotherapy

The gut microbiota is a large symbiotic community of anaerobic and facultative aerobic bacteria inhabiting the human intestinal tract, and its activities significantly affect human health. Increasing evidence has suggested that the gut microbiome plays an important role in tumor-related immune regulation. In the tumor microenvironment (TME), the gut microbiome and its metabolites affect the differentiation and function of immune cells regulating the immune evasion of tumors. The gut microbiome can indirectly influence individual responses to various classical tumor immunotherapies, including immune checkpoint inhibitor therapy and adoptive immunotherapy. Microbial regulation through antibiotics, prebiotics, and fecal microbiota transplantation (FMT) optimize the composition of the gut microbiome, improving the efficacy of immunotherapy and bringing a new perspective and hope for tumor treatment.

Self-assembled peptide-paclitaxel nanoparticles for enhancing therapeutic efficacy in colorectal cancer

Chemotherapy is one of the main treatments for colorectal cancer, but systemic toxicity severely limits its clinical use. Packaging hydrophobic chemotherapeutic drugs in targeted nanoparticles greatly improve their efficacy and reduce side effects. We previously identified a novel colorectal cancer specific binding peptide P-LPK (LPKTVSSDMSLN) from phage display peptide library. Here we designed a self-assembled paclitaxel (PTX)-loaded nanoparticle (LPK-PTX NPs). LPK-PTX NPs displayed a superior intracellular internalization and improved tumor cytotoxicity in vitro. Cy5.5-labeled LPK-PTX NPs showed much higher tumor accumulation in colorectal cancer-bearing mice. Furthermore, LPK-PTX NPs exhibit enhanced antitumor activity and decreased systemic toxicity in colorectal cancer patient-derived xenografts (PDX) model. The excellent in vitro and in vivo antitumor efficacy proves the improved targeting drug delivery, suggesting that peptide P-LPK has potential to provide a novel approach for enhanced drug delivery with negligible systemic toxicity.

Label-free metabolic imaging for sensitive and robust monitoring of anti-CD47 immunotherapy response in triple-negative breast cancer

Background

Immunotherapy is revolutionizing cancer treatment from conventional radiotherapies and chemotherapies to immune checkpoint inhibitors which use patients’ immune system to recognize and attack cancer cells. Despite the huge clinical success and vigorous development of immunotherapies, there is a significant unmet need for a robust tool to identify responders to specific immunotherapy. Early and accurate monitoring of immunotherapy response is indispensable for personalized treatment and effective drug development.

Methods

We established a label-free metabolic intravital imaging (LMII) technique to detect two-photon excited autofluorescence signals from two coenzymes, NAD(P)H (reduced nicotinamide adenine dinucleotide (phosphate) hydrogen) and FAD (flavin adenine dinucleotide) as robust imaging markers to monitor metabolic responses to immunotherapy. Murine models of triple-negative breast cancer (TNBC) were established and tested with different therapeutic regimens including anti-cluster of differentiation 47 (CD47) immunotherapy to monitor time-course treatment responses using the developed metabolic imaging technique.

Results

We first imaged the mechanisms of the CD47-signal regulatory protein alpha pathway in vivo, which unravels macrophage-mediated antibody-dependent cellular phagocytosis and illustrates the metabolism of TNBC cells and macrophages. We further visualized the autofluorescence of NAD(P)H and FAD and found a significant increase during tumor growth. Following anti-CD47 immunotherapy, the imaging signal was dramatically decreased demonstrating the sensitive monitoring capability of NAD(P)H and FAD imaging for therapeutic response. NAD(P)H and FAD intravital imaging also showed a marked decrease after chemotherapy and radiotherapy. A comparative study with conventional whole-body bioluminescence and fluorescent glucose imaging demonstrated superior sensitivity of metabolic imaging. Flow cytometry validated metabolic imaging results. In vivo immunofluorescent staining revealed the targeting ability of NAD(P)H imaging mainly for tumor cells and a small portion of immune-active cells and that of FAD imaging mainly for immunosuppressive cells such as M2-like tumor-associated macrophages.

Conclusions

Collectively, this study showcases the potential of the LMII technique as a powerful tool to visualize dynamic changes of heterogeneous cell metabolism of cancer cells and immune infiltrates in response to immunotherapy thus providing sensitive and complete monitoring. Leveraged on ability to differentiate cancer cells and immunosuppressive macrophages, the presented imaging approach provides particularly useful imaging biomarkers for emerged innate immune checkpoint inhibitors such as anti-CD47 therapy.

Recent advances in erythrocyte membrane-camouflaged nanoparticles for the delivery of anti-cancer therapeutics

INTRODUCTION

Red blood cell (or erythrocyte) membrane-camouflaged nanoparticles (RBC-NPs) not only have a superior circulation life and do not induce accelerated blood clearance, but also possess special functions, which offers great potential in cancer therapy.

AREAS COVERED

This review focuses on the recent advances of RBC-NPs for delivering various agents to treat cancers in light of their vital role in improving drug delivery. Meanwhile, the construction and in vivo behavior of RBC-NPs are discussed to provide an in-depth understanding of the basis of RBC-NPs for improved cancer drug delivery.

EXPERT OPINION

Although RBC-NPs are quite prospective in delivering anti-cancer therapeutics, they are still in their infancy stage and many challenges need to be overcome for successful translation into the clinic. The preparation and modification of RBC membranes, the optimization of coating methods, the scale-up production and the quality control of RBC-NPs, and the drug loading and release should be carefully considered in the clinical translation of RBC-NPs for cancer therapy.

Tumor-associated macrophage-targeted photodynamic cancer therapy using a dextran sulfate-based nano-photosensitizer

The M2-like phenotype of tumor-associated macrophages (TAMs) present in tumors promotes tumor growth and metastasis. Therefore, targeting M2-like TAMs is a potential strategy for cancer therapy. Herein, we fabricated a dextran sulfate-based nano-photosensitizer (dextran sulfate-conjugated chlorin e6, DS-Ce6) to specifically target M2-like TAMs for enhanced photodynamic therapy (PDT). DS-Ce6 was preferentially taken up by interleukin-4-derived M2 macrophages, which overexpressed scavenger receptor-A and selectively targeted macrophages in co-cultured 4T1 tumors/macrophages. The nano-photosensitizer also effectively induced the apoptosis of tumor cells in both monolayer co-culture and three-dimensional co-culture spheroids of tumors/macrophages under laser irradiation. Moreover, the nano-photosensitizer specifically targeted F4/80 and CD206 double-positive M2-like TAMs within tumor tissues. Therefore, the specifically targeted delivery of DS-Ce6 to M2-like TAMs prominently induced tumor apoptosis, leading to excellent phototherapeutic effects in 4T1 tumor-bearing mice after PDT, suggesting the potential of DS-Ce6 for specific targeting of M2-like TAMs and enhanced PDT.

Targeted Immunoimaging of Tumor-Associated Macrophages in Orthotopic Glioblastoma by the NIR-IIb Nanoprobes

Developing dynamic and highly sensitive methods for imaging M2-type tumor-associated macrophages (TAMs) is vital for monitoring the tumor progression and assessing the therapeutic efficacy. Here, the fabrication and application of rationally designed Er-based rare-earth nanoprobes for the targeted imaging of M2-type TAMs in glioblastoma (GBM) through the second near-infrared (NIR-II) fluorescence beyond 1500 nm is reported. The NIR-IIb fluorescence of Er-based rare-earth nanoparticles can be remarkably enhanced by optimizing their core-shell structures and the shell thickness, which allows for in vivo imaging under excitation by a 980 nm laser with the lowest power density (40 mW cm^-2 ). These bright Er-based nanoparticles functionalized with M2pep polypeptide show notable targeting ability to M2-type macrophages, which has been well tested in both in vitro and in vivo experiments by their up-conversion (UC) fluorescence (540 nm) and down-shifting (DS) fluorescence (1525 nm), respectively. The targeting capability of these nanoprobes in vivo is also demonstrated by the overlap of immunofluorescence of M2-type TAMs and Arsenazo III staining of rare-earth ions in tumor tissue. It is envisioned that these nanoprobes can serve as a companion diagnostic tool to dynamically assess the progression and prognosis of GBM.

Phage in cancer treatment - Biology of therapeutic phage and screening of tumor targeting peptide

INTRODUCTION

There is a constant drive to improve disease treatments. Much effort has been directed at identifying less immunogenic anti-cancer agents that produce fewer and less severe side effects. For more than a decade, bacteriophages have been discussed as an effective treatment for cancer with an exact mode of delivery.

AREAS COVERED

We review how bacteriophages are used in cancer treatment, the underlying therapeutic mechanisms, and the tumour attacking peptide screening process. The filamentous bacteriophages are an effective vehicle for delivering displayed peptides toward the tumour target. The peptide must be expressed at the appropriate coat protein, and the peptide must be effective enough to disrupt the complex cancer matrix. The present review also sheds light on the dynamic use of phage in cancer treatment, from detection and diagnostics to treatment.

EXPERT OPINION

Phage has a versatile role as a diagnostic and therapeutic tool. By acting as an appropriate recombinant drug, this phage has every potential to replace existing laborious, high capital investing therapies that may at many times result in failure or drastic side effects. One of the most significant challenges would be identifying tumour homing peptides. Although a few have been discovered, the most effective ones are yet to be determined. This therapeutic method plays a significant role in tumour therapy with high accuracy and efficiency, irrespective of the target location.

Protein-Crowned Micelles for Targeted and Synergistic Tumor-Associated Macrophage Reprogramming to Enhance Cancer Treatment

Tumor-associated macrophages (TAMs) are a promising therapeutic target for cancers, but achieving multitarget therapy of TAMs is still challenging. Here, we develop a protein-crowned micelle system for targeted and synergistic TAM reprogramming to enhance cancer treatment. The doxorubicin-loaded micelles with a hemoglobin crown (Hb-DOXM) can bind with endogenous plasma haptoglobin to realize specific M2-type TAM targeting. Under the tumor hypoxic and acidic environments, Hb-DOXM can responsively release O₂ and DOX to reduce the recruitment of TAMs by hypoxia remission and release DOX to kill M2-type TAMs and cancer cells. To reprogram TAMs adequately, the TAM-modulating drug celecoxib is further encapsulated (Hb-DOXM@Cel) to repolarize M2-type TAMs. The targeted and synergistic TAM reprogramming by Hb-DOXM@Cel can remodel the tumor microenvironment (TME) to an immunostimulatory microenvironment and augment the antitumor effect of cytotoxic T lymphocyte, thus strongly enhancing the DOX-based chemotherapy. The protein-crowned micelle strategy presents a targeted and synergistic TAM therapy tool for enhanced cancer treatment.

Current Development of Nano-Drug Delivery to Target Macrophages

Macrophages are the most important innate immune cells that participate in various inflammation-related diseases. Therefore, macrophage-related pathological processes are essential targets in the diagnosis and treatment of diseases. Since nanoparticles (NPs) can be preferentially taken up by macrophages, NPs have attracted most attention for specific macrophage-targeting. In this review, the interactions between NPs and the immune system are introduced to help understand the pharmacokinetics and biodistribution of NPs in immune cells. The current design and strategy of NPs modification for specific macrophage-targeting are investigated and summarized.

Novel Secreted Peptides From Rhizopus arrhizus var. delemar With Immunomodulatory Effects That Enhance Fungal Pathogenesis

Secreted fungal peptides are known to influence the interactions between the pathogen and host innate immunity. The aim of this study is to screen and evaluate secreted peptides from the fungus Rhizopus arrhizus var. delemar for their immunomodulatory activity. By using mass spectrometry and immuno-informatics analysis, we identified three secreted peptides CesT (S16), Colicin (S17), and Ca2+/calmodulin-dependent protein kinase/ligand (CAMK/CAMKL; S27). Culturing peripheral blood-derived monocytic macrophages (PBMMs) in the presence of S16 or S17 caused cell clumping, while culturing them with S27 resulted in the formation of spindle-shaped cells. S27-treated PBMMs showed cell cycle arrest at G0 phase and exhibited alternatively activated macrophage phenotype with pronounced reduction in scavenger receptors CD163 and CD206. Homology prediction indicated that IL-4/IL-13 is the immunomodulatory target of S27. Confirming this prediction, S27 initiated macrophage activation through phosphorylation of STAT-6; STAT-6 inhibition reversed the activity of S27 and reduced the formation of spindle-shaped PBMMs. Lastly, S27 treatment of PBMMs was associated with altered expression of key iron regulatory genes including hepcidin, ferroportin, transferrin receptor 1, and ferritin in a pattern consistent with increased cellular iron release; a condition known to enhance Rhizopus infection. Collectively, R. arrhizus var. delemar secretes peptides with immunomodulatory activities that support fungal pathogenesis. Targeting the IL-4/IL-13R/STAT-6 axis is a potential therapeutic approach to enhance the PBMM-mediated fungal phagocytosis. This represents a potential new approach to overcome lethal mucormycosis.

Regulation of tumor-associated macrophage (TAM) differentiation by NDRG2 expression in breast cancer cells

Macrophages are a major cellular component of innate immunity and are mainly known to have phagocytic activity. In the tumor microenvironment (TME), they can be differentiated into tumor-associated macrophages (TAMs). As the most abundant immune cells in the TME, TAMs promote tumor progression by enhancing angiogenesis, suppressing T cells and increasing immunosuppressive cytokine production. N-myc downstream-regulated gene 2 (NDRG2) is a tumor suppressor gene, whose expression is down-regulated in various cancers. However, the effect of NDRG2 on the differentiation of macrophages into TAMs in breast cancer remains elusive. In this study, we investigated the effect of NDRG2 expression in breast cancer cells on the differentiation of macrophages into TAMs. Compared to tumor cell-conditioned medium (TCCM) from 4T1-mock cells, TCCM from NDRG2-overexpressing 4T1 mouse breast cancer cells did not significantly change the morphology of RAW 264.7 cells. However, TCCM from 4T1-NDRG2 cells reduced the mRNA levels of TAM-related genes, including MR1, IL-10, ARG1 and iNOS, in RAW 264.7 cells. In addition, TCCM from 4T1-NDRG2 cells reduced the expression of TAM-related surface markers, such as CD206, in peritoneal macrophages (PEM). The mRNA expression of TAM-related genes, including IL-10, YM1, FIZZ1, MR1, ARG1 and iNOS, was also downregulated by TCCM from 4T1-NDRG2 cells. Remarkably, TCCM from 4T1-NDRG2 cells reduced the expression of PD-L1 and Fra-1 as well as the production of GM-CSF, IL-10 and ROS, leading to the attenuation of T cell-inhibitory activity of PEM. These data showed that compared with TCCM from 4T1-mock cells, TCCM from 4T1-NDRG2 cells suppressed the TAM differentiation and activation. Collectively, these results suggest that NDRG2 expression in breast cancer may reduce the differentiation of macrophages into TAMs in the TME.