Irradiated microparticles suppress prostate cancer by tumor microenvironment reprogramming and ferroptosis.

Immunogenic cell death (ICD) plays a crucial role in triggering the antitumor immune response in the tumor microenvironment (TME). Recently, considerable attention has been dedicated to ferroptosis, a type of ICD that is induced by intracellular iron and has been demonstrated to change the immune desert status of the TME. However, among cancers that are characterized by an immune desert, such as prostate cancer, strategies for inducing high levels of ferroptosis remain limited. Radiated tumor cell-derived microparticles (RMPs) are radiotherapy mimetics that have been shown to activate the cGAS-STING pathway, induce tumor cell ferroptosis, and inhibit M2 macrophage polarization. RMPs can also act as carriers of agents with biocompatibility. In the present study, we designed a therapeutic system wherein the ferroptosis inducer RSL-3 was loaded into RMPs, which were tested in in vitro and in vivo prostate carcinoma models established using RM-1 cells. The apoptosis inducer CT20 peptide (CT20p) was also added to the RMPs to aggravate ferroptosis. Our results showed that RSL-3- and CT20p-loaded RMPs (RC@RMPs) led to ferroptosis and apoptosis of RM-1 cells. Moreover, CT20p had a synergistic effect on ferroptosis by promoting reactive oxygen species (ROS) production, lipid hydroperoxide production, and mitochondrial instability. RC@RMPs elevated dendritic cell (DC) expression of MHCII, CD80, and CD86 and facilitated M1 macrophage polarization. In a subcutaneously transplanted RM-1 tumor model in mice, RC@RMPs inhibited tumor growth and prolonged survival time via DC activation, macrophage reprogramming, enhancement of CD8+ T cell infiltration, and proinflammatory cytokine production in the tumor. Moreover, combination treatment with anti-PD-1 improved RM-1 tumor inhibition. This study provides a strategy for the synergistic enhancement of ferroptosis for prostate cancer immunotherapies.

Applications of Intravital Imaging in Cancer Immunotherapy.

Currently, immunotherapy is one of the most effective treatment strategies for cancer. However, the efficacy of any specific anti-tumor immunotherapy can vary based on the dynamic characteristics of immune cells, such as their rate of migration and cell-to-cell interactions. Therefore, understanding the dynamics among cells involved in the immune response can inform the optimization and improvement of existing immunotherapy strategies. In vivo imaging technologies use optical microscopy techniques to visualize the movement and behavior of cells in vivo, including cells involved in the immune response, thereby showing great potential for application in the field of cancer immunotherapy. In this review, we briefly introduce the technical aspects required for in vivo imaging, such as fluorescent protein labeling, the construction of transgenic mice, and various window chamber models. Then, we discuss the elucidation of new phenomena and mechanisms relating to tumor immunotherapy that has been made possible by the application of in vivo imaging technology. Specifically, in vivo imaging has supported the characterization of the movement of T cells during immune checkpoint inhibitor therapy and the kinetic analysis of dendritic cell migration in tumor vaccine therapy. Finally, we provide a perspective on the challenges and future research directions for the use of in vivo imaging technology in cancer immunotherapy.

The roles of inflammasomes in cancer.

Inflammation is a key characteristic of all stages of tumor development, including tumor initiation, progression, malignant transformation, invasion, and metastasis. Inflammasomes are an important component of the inflammatory response and an indispensable part of the innate immune system. Inflammasomes regulate the nature of infiltrating immune cells by signaling the secretion of different cytokines and chemokines, thus regulating the anti-tumor immunity of the body. Inflammasome expression patterns vary across different tumor types and stages, playing different roles during tumor progression. The complex diversity of the inflammasomes is determined by both internal and external factors relating to tumor establishment and progression. Therefore, elucidating the specific effects of different inflammasomes in anti-tumor immunity is critical for promoting the discovery of inflammasome-targeting drugs. This review focuses on the structure, activation pathway, and identification methods of the NLRP3, NLRC4, NLRP1 and AIM2 inflammasomes. Herein, we also explore the role of inflammasomes in different cancers and their complex regulatory mechanisms, and discuss current and future directions for targeting inflammasomes in cancer therapy. A detailed knowledge of inflammasome function and regulation may lead to novel therapies that target the activation of inflammasomes as well as the discovery of new drug targets.

Mechanisms of antigen-induced reversal of CNS inflammation in experimental demyelinating disease.

Autoimmune central nervous system (CNS) demyelinating diseases are a major public health burden and poorly controlled by current immunosuppressants. More precise immunotherapies with higher efficacy and fewer side effects are sought. We investigated the effectiveness and mechanism of an injectable myelin-based antigenic polyprotein MMPt (myelin oligodendrocyte glycoprotein, myelin basic protein and proteolipid protein, truncated). We find that it suppresses mouse experimental autoimmune encephalomyelitis without major side effects. MMPt induces rapid apoptosis of the encephalitogenic T cells and suppresses inflammation in the affected CNS. Intravital microscopy shows that MMPt is taken up by perivascular F4/80+ cells but not conventional antigen-presenting dendritic cells, B cells, or microglia. MMPt-stimulated F4/80+ cells induce reactive T cell immobilization and apoptosis in situ, resulting in reduced infiltration of inflammatory cells and chemokine production. Our study reveals alternative mechanisms that explain how cognate antigen suppresses CNS inflammation and may be applicable for effectively and safely treating demyelinating diseases.

Engineered Microparticles for Treatment of Murine Brain Metastasis by Reprograming Tumor Microenvironment and Inhibiting MAPK Pathway.

Brain metastases (BRM) are common in advanced lung cancer. However, their treatment is challenging due to the blood-brain barrier (BBB) and the immunosuppressive tumor microenvironment (ITME). Microparticles (MPs), a type of extracellular vesicle, can serve as biocompatible drug delivery vehicles that can be further modulated with genetic engineering techniques. MPs prepared from cells induced with different insults are compared and it is found that radiation-treated cell-released microparticles (RMPs) achieve optimal targeting and macrophage activation. The enzyme ubiquitin-specific protease 7 (USP7), which simultaneously regulates tumor growth and reprograms M2 macrophages (M2Φ), is found to be expressed in BRM. Engineered RMPs are then constructed that comprise: 1) the RMP carrier that targets and reprograms M2Φ; 2) a genetically expressed SR-B1-targeting peptide for improved BBB permeability; and 3) a USP7 inhibitor to kill tumor cells and reprogram M2Φ. These RMPs successfully cross the BBB and target M2Φ in vitro and in vivo in mice, effectively reprogramming M2Φ and improving survival in a murine BRM model. Therapeutic effects are further augmented when combined with immune checkpoint blockade. This study provides proof-of-concept for the use of genetically engineered MPs for the treatment of BRM.

Ionizing Radiation-Induced Tumor Cell-Derived Microparticles Prevent Lung Metastasis by Remodeling the Pulmonary Immune Microenvironment.

PURPOSE: The majority of cancer-related deaths are attributed to metastasis rather than localized primary tumor progression. However, the factors that regulate the premetastatic niche (PMN) and metastasis have not yet been clearly elucidated. We investigated the antimetastatic effects of irradiated tumor cell-derived microparticles (RT-MPs) and highlighted the role of innate immune cells in PMN formation. METHODS AND MATERIALS: Mice were treated 3 times with isolated RT-MPs, followed by tumor cell injection via the tail vein. The hematoxylin and eosin staining was performed to assess the number of tumor nodules in the lungs, and in vivo luciferase-based noninvasive bioluminescence imaging was conducted to detected tumor burden. The mechanisms of RT-MPs mediated PMN formation was evaluated using flow cytometry, transwell assay, and reverse transcription-polymerase chain reaction. RESULTS: RT-MPs inhibited tumor cell colonization in the lungs. Neutrophils phagocytosed RT-MPs and secreted CCL3 and CCL4, which induced monocytes chemotaxis and maturation into macrophages. RT-MPs promoted the transition of neutrophils and macrophages into antitumor phenotypes, hence inhibiting cancer cell colonization and proliferation. CONCLUSIONS: RT-MPs inhibited PMN formation and lung metastasis in a neutrophil- and macrophage-dependent but T cell-independent manner.

PLK1 Inhibition Induces Immunogenic Cell Death and Enhances Immunity against NSCLC.

PLK1 inhibitors were shown, in vitro and in vivo, to possess inhibitory activities against non-small cell lung cancer (NSCLC), and such inhibition has been proven by clinical trials. However, it remains unclear whether and how the immune microenvironment is associated with the action. In this study, we found that inhibiting PLK1 could alter the tumor immune microenvironment by increasing DC maturation, and enriching T cells infiltration. PLK1 inhibitors, serving as immunogenic cell death (ICD) inducers, indirectly activated DCs, instead of directly acting on DC cells, through the surface expression of costimulatory molecules on and enhanced phagocytosis by DCs. Furthermore, upon targeting PLK1, tumor cells that had undergone ICD were converted into an endogenous vaccine, which triggered the immune memory responses and protected the mice from tumor challenge. Collectively, these results suggested that the PLK1 inhibitor might function as an immune modulator in antitumor treatment.

Curcumin loaded sub-30 nm targeting therapeutic lipid nanoparticles for synergistically blocking nasopharyngeal cancer growth and metastasis.

Systemic chemotherapy is still the primary treatment for advanced-stage nasopharyngeal carcinoma (NPC), but only limited therapeutic success has been achieved in the past decade because of drug resistance and systemic toxicity. Curcumin (Cur) is an effective alternative to chemotherapeutics because it showed remarkable therapeutic potential in the treatment of NPC. However, lack of tissue specificity and poor penetration in solid tumors are the major obstacles to effective therapy. Therefore, in this work, a self-assembled sub-30 nm therapeutic lipid nanoparticle loaded with Cur, named as Cur@α-NTP-LN, was constructed, specifically targeting scavenger receptor class B member 1 (SR-B1) and enhancing its therapeutic effects on NPC in vivo. Our results showed that Cur@α-NTP-LNs were effective and superior to free Cur on NPC cell-specific targeting, suppressing cell proliferation and inducing cell apoptosis. In vivo and ex vivo optical imaging revealed that Cur@α-NTP-LNs exerted high targeting efficiency, specifically accumulating in NPC xenograft tumors and delivering Cur into the tumor center after systemic administration. Furthermore, Cur@α-NTP-LNs exhibited a remarkable inhibitory effect on the growth of NPC subcutaneous tumors, with over 71 and 47% inhibition compared to Cur- and α-NTP-LNs-treated groups, respectively. In addition, Cur@α-NTP-LNs almost blocked NPC metastasis in a lung metastasis model of NPC and significantly improved the survival rate. Thus, the sub-30 nm Cur@α-NTP-LNs enhanced the solubility of Cur and demonstrated the ability of targeted Cur delivery into the center of the solid NPC tumor, performing synergistic inhibitory effects on the growth of NPC tumor and its metastasis with high efficiency.

Role of intravital imaging in nanomedicine-assisted anti-cancer therapy.

Although nanomedicines have provided promising anti-tumor effects in cancer animal models, their clinical success remains limited. One of the most significant barriers in the clinical translation of nanomedicines is that they consist of multiple components, each of which may have different toxicities and therapeutic effects. Intravital imaging provides high spatial and temporal resolution for visualizing nanomedicine-mediated interactions between immune cells and tumor cells in real-time. Intravital imaging can facilitate the in vivo evaluation of the properties and effects of nanomedicines, such as their ability to cross the tumor vasculature, specifically eliminate the cancer cells, and modulate the immune cells found in the tumor microenvironment (TME). Thus, intravital imaging can provide direct evidence of nanomedicine's intravital behavior to better understand mechanism and accelerate clinical translation. In this review, we summarize several applications and latest advances in intravital imaging in nanomedicine-assisted anti-cancer therapy and discuss future perspectives in the field.

USP7 targeting modulates anti-tumor immune response by reprogramming Tumor-associated Macrophages in Lung Cancer.

Background: Tumor associated macrophages (TAMs) have strong plasticity and if reprogrammed, can clear tumor cells and regulate the adaptive immune system for cancer immunotherapy. Deubiquitinating enzymes (DUBs), which can remove ubiquitin (Ub) from Ub-modified substrates, have been associated with oncogenic metabolism but are not well-known for regulating TAMs repolarization. Methods: The expression of DUB related genes in macrophages (MΦs) was detected by reverse transcription-PCR. Flow cytometry and immunofluorescence were used to detect the changes of immune cells in the tumor microenvironment and spleen, including M1 (CD11b+F4/80+CD86+CD206-), and M2 (CD11b+F4/80+CD86-CD206+) MΦs, and IFN-γ+CD8+T cells. A proliferation assay was used to determine the effect of M2 MΦs treated with a USP7 inhibitor on T cell proliferation. Western blotting was used to detect the expression of USP7 and the activation of the MAPK pathway. The TGCA database was used to assess the role of USP7 in the immune microenvironment of human lung adenocarcinoma (LUAD). Results: 51 DUB genes were screened and USP7 was identified as a highly expressed gene in M2 but not M1 MΦs. Specific silencing of USP7 using siRNA or USP7 inhibitors led to phenotypical and functional changes in M2 MΦs, favoring CD8+T cells proliferation in vitro. USP7 inhibitors delayed tumor growth in mice with Lewis lung carcinoma, and promoted tumor infiltration of M1 MΦs and IFN-γ+CD8+T cells. Depletion of TAMs attenuated these therapeutic effects. USP7 inhibition was shown to mediate MΦs reprogramming by activating the p38 MAPK pathway. Administration of USP7 inhibitors increased the expression of programmed cell death ligand 1 (PD-L1) in tumors, while blocking programmed cell death protein 1 (PD-1) provided an effective anti-tumor response. Clinical databases suggest that high expression of USP7 in LUAD was negatively correlated with innate and adaptive immunity. Conclusions: Taken together, these results provide evidence to suggest that therapeutic approaches targeting USP7, in combination with immunotherapy, should be considered for lung cancer treatment.

Irradiated tumor cell-derived microparticles mediate tumor eradication via cell killing and immune reprogramming.

Radiotherapy (RT) is routinely used in cancer treatment, but expansion of its clinical indications remains challenging. The mechanism underlying the radiation-induced bystander effect (RIBE) is not understood and not therapeutically exploited. We suggest that the RIBE is predominantly mediated by irradiated tumor cell-released microparticles (RT-MPs), which induce broad antitumor effects and cause immunogenic death mainly through ferroptosis. Using a mouse model of malignant pleural effusion (MPE), we demonstrated that RT-MPs polarized microenvironmental M2 tumor-associated macrophages (M2-TAMs) to M1-TAMs and modulated antitumor interactions between TAMs and tumor cells. Following internalization of RT-MPs, TAMs displayed increased programmed cell death ligand 1 (PD-L1) expression, enhancing follow-up combined anti-PD-1 therapy that confers an ablative effect against MPE and cisplatin-resistant MPE mouse models. Immunological memory effects were induced.

Targeted immunomodulation of inflammatory monocytes across the blood-brain barrier by curcumin-loaded nanoparticles delays the progression of experimental autoimmune encephalomyelitis.

It is difficult to carry out early diagnosis and treatment of Multiple sclerosis (MS) because of the complex pathogenesis elicited by diversified autoantigens. Monocytes play important roles in the process of MS, especially as most of the amplified inflammatory monocytes cross the BBB to promote neuron injury and recruit more immune cells to infiltrate the central nervous system (CNS). Here, we propose monocytes as an effective immunotherapy target for MS. We used High-density lipoprotein-mimicking peptide-phospholipid scaffold (HPPS) as a carrier to improve the bioavailability of curcumin. Curcumin-loaded HPPS (Cur-HPPS) were taken up specifically and efficiently by monocytes through the scavenger receptor class B type I (SR-B1) receptor. This delivery hindered inflammatory monocytes across the BBB in EAE mice, inhibited the proliferation of microglia, and restricted the infiltration of other effector immune cells, resulting in the reduction of EAE morbidity from 100% to 30%. It attributed to the immunomodulatory effect of Cur-HPPS on inflammatory monocytes, which inhibited NF-κB activation and downregulated the expression of adhesion-and migration-related molecules. Meanwhile, infiltrated monocytes in the CNS of EAE mice characterize early inflammation. Therefore, targeted modulation of monocytes with HPPS carrying therapeutic and/or imaging agents offers a novel strategy for MS diagnosis and treatment.

Targeting CAMKII to reprogram tumor-associated macrophages and inhibit tumor cells for cancer immunotherapy with an injectable hybrid peptide hydrogel.

Simultaneously targeted treatment of tumor cells and their surrounding growth-supporting immune cells is a promising strategy to reshape immunosuppressive tumor microenvironment (TME) and potentiate host innate and adaptive antitumor immune responses. Methods: We designed a series of melittin-(RADA)n hybrid peptide sequences with varying self-assembling motifs of RADA and screened out a melittin-(RADA)6 peptide that has an optimal gel-formation ability and in vitro antitumor activity. Results: The formed melittin-(RADA)6 (MR52) hydrogel scaffold could be loaded with a specific Ca2+/calmodulin-dependent protein kinase II (CAMKII) inhibitor, KN93, originally found to have both direct tumoricidal activity and macrophages-reprogramming ability, for potent immunotherapy against melanoma and hepatoma ascites in mice models. Our MR52 hydrogel has an interweaving nanofiber-like structure, possesses direct antitumor and controlled drug release properties, and promotes the enhanced intracellular uptake of loaded cargo. Compared to free KN93, the MR52-KN93 hydrogel (MRK) improved the killing effects and levels of immunogenic cell death (ICD) on tumor cells significantly. Due to the dual role of KN93, the injection of the MRK hydrogel retarded the growth of subcutaneous melanoma tumors dramatically and resulted in a high number of mature dendritic cells of draining lymph nodes, significantly enhancing the portion of cytotoxic T cells and reduced number of M2-like tumor-associated macrophages (TAMs) in tumors. Using a mouse model of malignant ascites (MAs), where traditional therapy was ineffective, we demonstrated that the MRK hydrogel treatment offered a significantly prolonged survival compared to controls. Following treatment with the MRK hydrogel, macrophages had elevated programmed cell death protein ligand-1 (PD-L1) expression, promising follow-up combined anti-PD-1 therapy that confers a cure rate of approximately 30% against MAs in mice models. Conclusion: Thus, the MRK hydrogel may serve as a prospective platform for antitumor applications.

Melittin-lipid nanoparticles target to lymph nodes and elicit a systemic anti-tumor immune response.

Targeted delivery of a nanovaccine loaded with a tumor antigen and adjuvant to the lymph nodes (LNs) is an attractive approach for improving cancer immunotherapy outcomes. However, the application of this technique is restricted by the paucity of suitable tumor-associated antigens (TAAs) and the sophisticated technology required to identify tumor neoantigens. Here, we demonstrate that a self-assembling melittin-lipid nanoparticle (α-melittin-NP) that is not loaded with extra tumor antigens promotes whole tumor antigen release in situ and results in the activation of antigen-presenting cells (APCs) in LNs. Compared with free melittin, α-melittin-NPs markedly enhance LN accumulation and activation of APCs, leading to a 3.6-fold increase in antigen-specific CD8+ T cell responses. Furthermore, in a bilateral flank B16F10 tumor model, primary and distant tumor growth are significantly inhibited by α-melittin-NPs, with an inhibition rate of 95% and 92%, respectively. Thus, α-melittin-NPs induce a systemic anti-tumor response serving as an effective LN-targeted whole-cell nanovaccine.

Neutrophil infiltration and whole-cell vaccine elicited by N-dihydrogalactochitosan combined with NIR phototherapy to enhance antitumor immune response and T cell immune memory.

Melanoma is one of the deadliest malignancies with a high risk of relapse and metastasis. Long-term, tumor-specific, and systemic immunity induced by local intervention is ideal for personalized cancer therapy. Laser immunotherapy (LIT), a combination of local irradiation of laser and local administration of an immunostimulant, was developed to achieve such an immunity. Although LIT showed promising efficacy on tumors, its immunological mechanism is still not understood, especially its spatio-temporal dynamics. Methods: In this study, we investigated LIT-induced immunological responses using a 980-nm laser and a novel immunostimulant, N-dihydrogalactochitosan (GC). Then we followed the functions of key immune cells spatially and temporally using intravital imaging and immunological assays. Results: Immediately after LIT, GC induced a rapid infiltration of neutrophils which ingested most GC in tumors. The cytokines released to the serum peaked at 12 h after LIT. Laser irradiations produced photothermal effects to ablate the tumor, release damage-associated molecular patterns, and generate whole-cell tumor vaccines. LIT-treated tumor-bearing mice efficiently resisted the rechallenged tumor and prevented lung metastasis. Intravital imaging of tumor at rechallenging sites in LIT-treated mice revealed that the infiltration of tumor-infiltrating lymphocytes (TILs) increased with highly active motility. Half of TILs with arrest and confined movements indicated that they had long-time interactions with tumor cells. Furthermore, LIT has synergistic effect with checkpoint blockade to improve antitumor efficacy. Conclusion: Our research revealed the important role of LIT-induced neutrophil infiltration on the in situ whole-cell vaccine-elicited antitumor immune response and long-term T cell immune memory.

Long-Distance Tracing of the Lymphatic System with a Computed Tomography/Fluorescence Dual-Modality Nanoprobe for Surveying Tumor Lymphatic Metastasis.

Noninvasive visualization of deep tissue lymphatic metastasis is crucial for diagnosing malignant tumors and predicting prognosis. However, the limited diffusivity and specificity of imaging contrast agents that are transported in lymph vessels (LVs), even for those agents delivered by nanocarriers, make long-distance tracing of the lymphatic system in vivo challenging. Here, we develop a computed tomography (CT)/fluorescence dual-modality phospholipid nanoprobe (PL(I/D)NP) with a negative charge and sub-60 nm size. By using micro-CT, we noninvasively traced the LVs from the subcutaneous injection site in feet to the thoracic ducts with an entire length of ∼68 mm and measured the volume of the lymph nodes (LNs) and their separation distance along the LVs. For diagnostic imaging of tumor lymphatic metastasis, all LNs with metastasis were identified in vivo. Thus, with their long-distance diffusivity, high lymphatic capillary specificity, and quantifiability, the PL(I/D)NPs combined with noninvasive imaging accurately depicted the changes in the lymphatic system under pathologic conditions, especially cancer metastasis, which indicates their high potential for clinical applicability.

Molecular-Targeted Immunotherapeutic Strategy for Melanoma via Dual-Targeting Nanoparticles Delivering Small Interfering RNA to Tumor-Associated Macrophages.

Tumor-associated macrophages (TAMs) are a promising therapeutic target for cancer immunotherapy. Targeted delivery of therapeutic drugs to the tumor-promoting M2-like TAMs is challenging. Here, we developed M2-like TAM dual-targeting nanoparticles (M2NPs), whose structure and function were controlled by α-peptide (a scavenger receptor B type 1 (SR-B1) targeting peptide) linked with M2pep (an M2 macrophage binding peptide). By loading anti-colony stimulating factor-1 receptor (anti-CSF-1R) small interfering RNA (siRNA) on the M2NPs, we developed a molecular-targeted immunotherapeutic approach to specifically block the survival signal of M2-like TAMs and deplete them from melanoma tumors. We confirmed the validity of SR-B1 for M2-like TAM targeting and demonstrated the synergistic effect of the two targeting units (α-peptide and M2pep) in the fusion peptide (α-M2pep). After being administered to tumor-bearing mice, M2NPs had higher affinity to M2-like TAMs than to tissue-resident macrophages in liver, spleen, and lung. Compared with control treatment groups, M2NP-based siRNA delivery resulted in a dramatic elimination of M2-like TAMs (52%), decreased tumor size (87%), and prolonged survival. Additionally, this molecular-targeted strategy inhibited immunosuppressive IL-10 and TGF-ß production and increased immunostimulatory cytokines (IL-12 and IFN-γ) expression and CD8+ T cell infiltration (2.9-fold) in the tumor microenvironment. Moreover, the siRNA-carrying M2NPs down-regulated expression of the exhaustion markers (PD-1 and Tim-3) on the infiltrating CD8+ T cells and stimulated their IFN-γ secretion (6.2-fold), indicating the restoration of T cell immune function. Thus, the dual-targeting property of M2NPs combined with RNA interference provides a potential strategy of molecular-targeted cancer immunotherapy for clinical application.

Long-term intravital imaging of the multicolor-coded tumor microenvironment during combination immunotherapy.

The combined-immunotherapy of adoptive cell therapy (ACT) and cyclophosphamide (CTX) is one of the most efficient treatments for melanoma patients. However, no synergistic effects of CTX and ACT on the spatio-temporal dynamics of immunocytes in vivo have been described. Here, we visualized key cell events in immunotherapy-elicited immunoreactions in a multicolor-coded tumor microenvironment, and then established an optimal strategy of metronomic combined-immunotherapy to enhance anti-tumor efficacy. Intravital imaging data indicated that regulatory T cells formed an 'immunosuppressive ring' around a solid tumor. The CTX-ACT combined-treatment elicited synergistic immunoreactions in tumor areas, which included relieving the immune suppression, triggering the transient activation of endogenous tumor-infiltrating immunocytes, increasing the accumulation of adoptive cytotoxic T lymphocytes, and accelerating the infiltration of dendritic cells. These insights into the spatio-temporal dynamics of immunocytes are beneficial for optimizing immunotherapy and provide new approaches for elucidating the mechanisms underlying the involvement of immunocytes in cancer immunotherapy.

Magnetic Enrichment of Dendritic Cell Vaccine in Lymph Node with Fluorescent-Magnetic Nanoparticles Enhanced Cancer Immunotherapy.

Dendritic cell (DC) migration to the lymph node is a key component of DC-based immunotherapy. However, the DC homing rate to the lymphoid tissues is poor, thus hindering the DC-mediated activation of antigen-specific T cells. Here, we developed a system using fluorescent magnetic nanoparticles (α-AP-fmNPs; loaded with antigen peptide, iron oxide nanoparticles, and indocyanine green) in combination with magnetic pull force (MPF) to successfully manipulate DC migration in vitro and in vivo. α-AP-fmNPs endowed DCs with MPF-responsiveness, antigen presentation, and simultaneous optical and magnetic resonance imaging detectability. We showed for the first time that α-AP-fmNP-loaded DCs were sensitive to MPF, and their migration efficiency could be dramatically improved both in vitro and in vivo through MPF treatment. Due to the enhanced migration of DCs, MPF treatment significantly augmented antitumor efficacy of the nanoparticle-loaded DCs. Therefore, we have developed a biocompatible approach with which to improve the homing efficiency of DCs and subsequent anti-tumor efficacy, and track their migration by multi-modality imaging, with great potential applications for DC-based cancer immunotherapy.

Targeting dendritic cells in lymph node with an antigen peptide-based nanovaccine for cancer immunotherapy.

The design of peptide-based subunit vaccine formulations for the direct delivery of tumor antigen peptides (Aps) to dendritic cells (DCs) localized within draining lymph nodes (DLNs) is challenging. Mature DCs (mDCs) are abundantly distributed within DLNs but have dramatically reduced endocytic uptake and antigen-processing abilities, so their role as potential vaccine targets has been largely overlooked. Here we report an ultra-small biocompatible nanovaccine (α-Ap-FNP) functionalized by avidly targeting delivery of Ap via the scavenger receptor class B1 (SR-B1) pathway to mDCs. The self-assembly, small size (∼30 nm), SR-B1-targeting and optical properties of α-Ap-FNP resulted in its efficient Ap loading, substantial LN accumulation, targeting of mDCs and enhanced Ap presentation, and fluorescence trafficking, respectively. We also demonstrate that the α-Ap-FNP can be either used alone or encapsulated with CpG oligodeoxynucleotide as a prophylactic and therapeutic vaccine. Thus, the excellent properties of α-Ap-FNP provide it potential for clinical applications as a potent nanovaccine for cancer immunotherapy.