Roles of macrophages in tumor development: a spatiotemporal perspective

Emerging nanomedicines for macrophage-mediated cancer therapy

Tumor-associated macrophages (TAMs) contribute to tumor progression by promoting angiogenesis, remodeling the tumor extracellular matrix, inducing tumor invasion and metastasis, as well as immune evasion. Due to the high plasticity of TAMs, they can polarize into different phenotypes with distinct functions, which are primarily categorized as the pro-inflammatory, anti-tumor M1 type, and the anti-inflammatory, pro-tumor M2 type. Notably, anti-tumor macrophages not only directly phagocytize tumor cells, but also present tumor-specific antigens and activate adaptive immunity. Therefore, targeted regulation of TAMs to unleash their potential anti-tumor capabilities is crucial for improving the efficacy of cancer immunotherapy. Nanomedicine serves as a promising vehicle and can inherently interact with TAMs, hence, emerging as a new paradigm in cancer immunotherapy. Due to their controllable structures and properties, nanomedicines offer a plethora of advantages over conventional drugs, thus enhancing the balance between efficacy and toxicity. In this review, we provide an overview of the hallmarks of TAMs and discuss nanomedicines for targeting TAMs with a focus on inhibiting recruitment, depleting and reprogramming TAMs, enhancing phagocytosis, engineering macrophages, as well as targeting TAMs for tumor imaging. We also discuss the challenges and clinical potentials of nanomedicines for targeting TAMs, aiming to advance the exploitation of nanomedicine for cancer immunotherapy.

Green Tea Catechins: A Promising Anticancer Approach for Leukaemia

Green tea catechins are bioactive polyphenolic compounds that possess a number of biological activities and potential health benefits. This review will focus on discussing the effects of green tea catechins, with a particular emphasis on clinical studies that evaluate their anticancer potential. Epigallocatechin gallate (EGCG), either as a stand-alone treatment or in conjunction with conventional anticancer therapies, represents a promising alternative strategy for the management of leukaemia. This review was based on a search of the scientific sources indexed in the databases PubMed and Scopus using the following keywords: 'Camellia sinensis', 'tea catechins', 'anticancer', 'antioxidant', 'hematological cancer', and 'leukaemia' in combination. A deeper comprehension of the multifaceted mechanisms and findings of research could facilitate the development of novel strategies and the integration of green tea catechins into clinical practice, thus enhancing treatment outcomes for patients with leukaemia.

Artificial intelligence-based virtual staining platform for identifying tumor-associated macrophages from hematoxylin and eosin-stained images

BACKGROUND

Virtual staining is an artificial intelligence-based approach that transforms pathology images between stain types, such as hematoxylin and eosin (H&E) to immunohistochemistry (IHC), providing a tissue-preserving and efficient alternative to traditional IHC staining. However, existing methods for translating H&E to virtual IHC often fail to generate images of sufficient quality for accurately delineating cell nuclei and IHC+ regions. To address these limitations, we introduce VISTA, an artificial intelligence-based virtual staining platform designed to translate H&E into virtual IHC.

METHODS

We applied VISTA to identify M2-subtype tumor-associated macrophages (M2-TAMs) in H&E images from 968 patients with HPV+ oropharyngeal squamous cell carcinoma across six institutional cohorts. M2-TAMs are a critical component of the tumor microenvironment, and their increased presence has been linked to poor survival. Co-registered H&E and CD163 + IHC tissue microarrays were used to train (D1, N = 102) and test (D2, N = 50) the VISTA platform. M2-TAM density, defined as the ratio of M2-TAMs to total nuclei, was derived from VISTA-generated CD163 + IHC images and evaluated for prognostic significance in additional training (D3, N = 360) and testing (D4, N = 456) cohorts using biopsy or resection H&E whole slide images.

RESULTS

High M2-TAM density was associated with worse overall survival in D4 (p = 0.0152, Hazard Ratio=1.63 [1.1-2.42]). VISTA outperformed existing methods, generating higher-quality virtual CD163 + IHC images in D2, with a Structural Similarity Index of 0.72, a Peak Signal-to-Noise Ratio of 21.5, and a Fréchet Inception Distance of 41.4. Additionally, VISTA demonstrated superior performance in segmenting M2-TAMs in D2 (Dice=0.74).

CONCLUSION

These findings establish VISTA as a computational platform for generating virtual IHC and facilitating the discovery of novel biomarkers from H&E images.

Emodin Decreases Tumor-Associated Macrophages Accumulation and Suppresses Bladder Cancer Development by Inhibiting CXCL1 Secretion from Cancer-Associated Fibroblasts

Tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs) are the most abundant stromal cells in the bladder cancer (BC) microenvironment (TME). However, the detailed mechanisms underlying TAM-CAF communication and their contributions to BC progression remain incompletely understood. Emerging evidence shows that Emodin exerts anti-tumor effect on several tumor models by targeting TME. To date, the impact of Emodin on BC has not been previously reported. Our study firstly demonstrated that Emodin significantly inhibited tumor growth and reduced TAM accumulation in a murine BC model. Emodin markedly decreased serum levels of multiple chemokines in tumor-bearing mice, with CXCL1 showing the most pronounced reduction. Strikingly, Emodin selectively suppressed CXCL1 secretion in CAFs but not in TAMs or tumor cells. Furthermore, the decrease in TAM migration induced by Emodin was dependent on CAF-derived CXCL1. Using a subcutaneous tumor model, we found that Emodin failed to inhibit tumor growth when CXCL1-deficient CAFs were co-injected with tumor cells, underscoring the critical role of CXCL1 in this process. Bioinformatics analysis further revealed that elevated CXCL1 levels correlated negatively with invasive/metastatic potential and overall survival in BC patients. In conclusion, our findings establish that Emodin delays BC progression by disrupting CXCL1-mediated crosstalk between CAFs and TAMs.

INHBA, transcriptionally activated by SPI1, facilitates gastric cancer progression by inducing macrophage recruitment and M2 polarization via activating the TGF-β signaling to increase CCL2

Tumor-associated macrophages (TAMs) are associated with the occurrence, development, and poor prognosis of human cancers. Inhibin beta A subunit (INHBA) is found to be aberrantly upregulated in gastric cancer (GC). However, whether INHBA is involved in macrophage recruitment and M2 polarization is unclear. Herein, INHBA expression was increased in GC tumor tissues and cells. INHBA expression was positively correlated with macrophage infiltration and M2 macrophage markers. Knockdown of INHBA in GC cells suppressed macrophage recruitment and M2 polarization by downregulaitng CCL2 expression and secretion. Mechanistic assays showed that SPI1 could bind to INHBA and transcriptionally activate its expression. SPI1 promoted macrophage recruitment and M2 polarization by upregulating INHBA expression. Moreover, SPI1 induced CCL2 expression by regulating INHBA in GC cells. INHBA upregulated CCL2 expression by activating the TGF-β signaling. Furthermore, SPI1-induced macrophages facilitated cell proliferation, migration, and invasion by increasing INHBA expression. INHBA-induced macrophages promoted cell proliferation, migration, and invasion by inducing CCL2 expression. Additionally, knockdown of INHBA inhibited tumor growth in vivo. In conclusion, SPI1 induces the macrophage recruitment and M2 polarization by transcriptionally regulating INHBA to activating the TGF-β signaling, thereby upregulating CCL2 expression and then contributing to GC cell malignant progression. Targeting SPI1/INHBA/CCL2 axis might be a promising therapeutic strategy for GC and potentially used for cancer immunotherapy.

Oropharyngeal carcinomas induce circulating monocytes to express a TAM-like pro-tumor expression profile that suppresses T-cell proliferation

Introduction

Tumor-associated macrophages (TAMs) recruited from circulating monocytes drive tumor-growth and establish an immunosuppressive tumor microenvironment (TME). Initial events in transition from resting monocytes to TAMs are poorly understood. Here, we report that monocytes from oropharyngeal cancer (OPC) patients and control monocytes treated with OPC-conditioned media (CM) express a repertoire of pro-tumor mediators that is characteristic of TAMs.

Methods

Monocytes were stimulated with OPC cell line CM, analyzed by single-cell RNAseq. Results of select genes were confirmed by qPCR with monocytes and analyzed in OPC tumors vs. clinically normal tissue. OPC spheroids containing control monocytes and T-cells were established, TAM phenotype characterized by flow analysis and qPCR, and T-cell proliferation assessed by flow.

Results

OPC-conditioned media induced multiple pro-tumor genes including CXCL1, CXCL5, CXCL8, SPP1, IL1B, GPNMB, and FABP5. Patient monocytes had higher baseline levels or achieved higher levels after stimulation than control monocytes. A subset of patient monocytes had high baseline levels of CXCL9/-10/-11 expression that resisted downregulation in response to stimulation, a potential sign of a more favorable TME. CXCL9/-10/-11 expression in OPC tumor biopsies compared to clinically normal tissue correlated with patient outcome. Spheroid TAMs derived from control monocytes maintained the pro-tumor repertoire seen with monocytes stimulated by tumor line conditioned media. These TAMs suppress T-cell proliferation. Inhibition of COX-2 or IL1 signaling during differentiation into TAMs partially blocked the suppression of T-cell proliferation.

Conclusion

Targeting the early transition of monocytes into pro-tumor TAMs could be used to develop new therapies for OPC.

Inflammation and cancer: molecular mechanisms and clinical consequences

Inflammation, a hallmark of cancer, has been associated with tumor progression, transition into malignant phenotype and efficacy of anticancer treatments in cancer. It affects all stages of cancer, from the initiation of carcinogenesis to metastasis. Chronic inflammation induces immunosup-pression, providing an environment conducive to carcinogenesis, whereas acute inflammation induces an antitumor immune response, leading to tumor suppression. Solid tumors have an inflammatory tumor microenvironment (TME) containing cancer cells, immune cells, stromal cells, and soluble molecules, which plays a key role in tumor progression and therapy response. Both cancer cells and stromal cells in the TME are highly plastic and constantly change their phenotypic and functional properties. Cancer-associated inflammation, the majority of which consists of innate immune cells, plays an important role in cancer cell plasticity, cancer progression and the development of anticancer drug resistance. Today, with the combined used of advanced technologies, such as single-cell RNA sequencing and spatial molecular imaging analysis, the pathways linking chronic inflammation to cancer have been largely elucidated. In this review article, we highlighted the molecular and cellular mechanisms involved in cancer-associated inflammation and its effects on cancer progression and treatment response. We also comprehensively review the mechanisms linking chronic inflammation to cancer in the setting of GI cancers.

Insulin resistance and cancer: molecular links and clinical perspectives

The association between insulin resistance (IR), type 2 diabetes mellitus (T2DM), and cancer is increasingly recognized and poses an escalating global health challenge, as the incidence of these conditions continues to rise. Studies indicate that individuals with T2DM have a 10-20% increased risk of developing various solid tumors, including colorectal, breast, pancreatic, and liver cancers. The relative risk (RR) varies depending on cancer type, with pancreatic and liver cancers showing a particularly strong association (RR 2.0-2.5), while colorectal and breast cancers demonstrate a moderate increase (RR 1.2-1.5). Understanding these epidemiological trends is crucial for developing integrated management strategies. Given the global rise in T2DM and cancer cases, exploring the complex relationship between these conditions is critical. IR contributes to hyperglycemia, chronic inflammation, and altered lipid metabolism. Together, these factors create a pro-tumorigenic environment conducive to cancer development and progression. In individuals with IR, hyperinsulinemia triggers the insulin-insulin-like growth factor (IGF1R) signaling pathway, activating cancer-associated pathways such as mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PIK3CA), which promote cell proliferation and survival, thereby supporting tumor growth. Both IR and T2DM are linked to increased morbidity and mortality in patients with cancer. By providing an in-depth analysis of the molecular links between insulin resistance and cancer, this review offers valuable insights into the role of metabolic dysfunction in tumor progression. Addressing insulin resistance as a co-morbidity may open new avenues for risk assessment, early intervention, and the development of integrated treatment strategies to improve patient outcomes.

Targeting stemness pathways modulates macrophage polarization and reprograms the tumor microenvironment

Introduction

The tumor microenvironment plays a pivotal role in cancer progression and therapeutic resistance, with tumor-associated macrophages significantly influencing immune suppression and tumor growth. Colorectal cancers (CRC) classified as Consensus Molecular Subtype 4 (CMS4) and triple-negative breast cancers subsets are particularly characterized by a mesenchymal phenotype, immune exclusion, and extensive macrophage infiltration. This study aimed to investigate how targeting cancer cell stemness with specific inhibitors could modulate macrophage polarization in CRC in vitro and breast cancer in vivo, potentially shifting the immune balance from pro-tumor M2-like to anti-tumor M1-like macrophages.

Methods

We used four stemness inhibitors-salinomycin, SB-431542, JIB-04, and napabucasin-each targeting different pathways (Wnt/β-catenin, TGF-β, histone demethylation, and STAT3, respectively), to evaluate their effects on CMS4 CRC cell lines (HCT116 and SW620) and human peripheral blood-derived macrophages in an indirect co-culture model.

Results

Our results showed that CMS4 CRC cell lines induced distinct macrophage polarization patterns, with HCT116 promoting M2-like macrophages and SW620 leaning toward M1-like profile. Notably, the combination of stemness inhibitors reduced stemness markers (CD133, CD44) in colorectal cancer cells and shifted macrophage polarization toward an M1-like phenotype, particularly in co-culture with HCT116. In vivo studies using the syngeneic immunocompetent EO771 breast cancer mouse model demonstrated that combination of stemness inhibitors increased the M1/M2 macrophage ratio.

Conclusions

Our study highlights the dual potential of stemness inhibitors to target both cancer cells and the immune microenvironment. These findings offer promising strategies for enhancing favorable immunomodulation in mesenchymal-like colorectal tumors.

Significance of the monocyte CCR2-CCL2 axis in triple-negative breast cancer

BACKGROUND

The monocyte CCR2-CCL2 axis appears to play a crucial role in the generation of tumor-associated macrophages (TAMs), which subsequently promotes tumor metastasis and resistance to therapy.

AIMS

Our study assessed the monocyte CCR2-CCL2 axis in triple-negative breast cancer (TNBC) and its ability to predict tumor response to neoadjuvant chemotherapy (NAC).

METHODS

The study included 42 female patients diagnosed with TNBC and eligible for NAC. Response to neoadjuvant chemotherapy was based on pathological complete response (pCR). Surface expression of CCR2 on monocytes was evaluated by flow cytometry. Circulating CCL2 was measured by Luminex X-Map technology.

RESULTS

Increased monocyte CCR2 expression and higher circulating CCL2 levels were observed in the patients with TNBC. After dividing the patients according to their response to NAC, a significant difference in CCL2 levels was found only between patients who achieved pCR and those who did not. ROC curves showed that the optimum diagnostic cut-off value of CCL2 ≤89.61 pg/mL better discriminated patients with TNBC who achieved pCR better than the Ki-67 index. Univariate analysis demonstrated that circulating. CCL2 ≤89.61 pg/mL was significantly associated with pCR. However, this correlation lost statistical significance in the multivariate model.

CONCLUSIONS

Our study demonstrated the activation of the monocyte CCR2-CCL2 axis in TNBC for the first time. This activation occurs mainly in patients who do not respond to NAC. Circulating CCL2 levels ≤89.61 pg/mL were found to predict, to some extent, the achievement of pCR in patients with TNBC receiving NAC.

Dual checkpoint inhibition in M2 macrophages via anti-PD-L1 and siRNA-Loaded M1-Exosomes: Enhancing tumor immunity through RNA-targeting Strategies

The interaction between a cluster of differentiation 47 (CD47) on cancer cells and signal regulatory protein alpha (SIRPα) on macrophages is thought to hinder macrophage phagocytic activity, which can be blocked by combining siRNAs targeting SIRPα (siSIRPα) with simultaneous involvement of activating receptors like FcRs (Fc receptors) using anti-programmed death-ligand 1 (anti-PD-L1). For this study, M1 macrophage-derived exosomes isolated from lipopolysaccharide (LPS)-stimulated RAW264.7 cells were used to deliver the siRNAs, and electroporated with siSIRPα. The exosomes were characterized and used to treat M2 macrophages (RAW264.7 cells triggered by interleukin-4 (IL-4)), and the polarization of macrophages was evaluated using flow cytometry, real-time PCR, ELISA, and phagocytosis assays. The anti-tumor functions of treated macrophages were assessed by co-culturing them with 4T1 cells, evaluating the migration and invasion of 4T1 cells, and examining the phagocytosis of 4T1 cells by macrophages. The results showed that siSIRPα-loaded M1-exosomes caused polarization of M2 macrophage toward M1 phenotype and enhanced anti-tumor effects by reducing migration and invasion of 4T1 cells and enhancing phagocytosis of 4T1 cells by macrophages, especially with combination of anti-PD-L1. This study suggests that blocking the SIRPα-CD47 interaction and the PD-1/PD-L1 pathway in M2 macrophages could be a promising therapeutic approach to enhance anti-tumor immune responses.

Hydrotalcites-Induced Pyroptosis Combined with Toll-Like Receptor Activation Elicited Dual Stimulation of Innate and Adaptive Immunity

Increasing evidence illustrates the significance of promoting tumor immunogenicity and an efficient immune response in immunotherapy, but the immunosuppressive tumor microenvironment (TME) remains an obstacle. Herein, AlZn hydrotalcite (AZOH) was synthesized as a pyroptosis inducer and further loaded with R848 to formulate R@AZOH. R@AZOH efficiently triggered CT26 cell pyroptosis through Zn2+ overload-evoked mitochondrial dysfunction and its downstream caspase-1/GSDMD pathway, resulting in the release of inflammatory cytokines, membrane fracture, and immunogenic cell death (ICD). Moreover, R@AZOH served as antigen traps to facilitate antigen presentation, thereby cooperating with TLR activation to dually stimulate dendritic cells (DCs). The combination of R@AZOH rapidly initiated innate immunity and prolonged the adaptive immune response, resulting in the suppression of tumor growth, immune cell activation and a "hot" tumor niche. The potent antitumor immunity was further enhanced by combination with an immune checkpoint inhibitor (αCTLA-4), which inhibited both primary and distant tumors, as well as systemic immune activation. Astonishingly, we also explored the potential application of R@AZOH as a tumor vaccine adjuvant and demonstrated its ability to elicit immunological memory to prevent tumor growth in an orthotopic melanoma model. Overall, our work emphasized the potential application of combining pyroptosis and TLR activation to stimulate both innate and adaptive immunity to overcome the immunosuppressive TME and presented a good adjuvant candidate.

CKIP-1 inhibits M2 macrophage polarization to suppress the progression of gastric cancer by inactivating JAK/STAT3 signaling

Gastric cancer (GC) is a frequently occurring malignancy with poor prognosis. Casein kinase 2 interacting protein-1 (CKIP-1) is a PH domain-containing protein implicated in regulating tumorigenesis and macrophage homeostasis. This study aimed to elucidate the role and potential mechanism of CKIP-1 in the progression of GC. CKIP-1 expression in GC tumor and para-carcinoma tissues was detected using RT-qPCR. Then, human monocyte cell line THP-1 was treated with PMA, interleukin (IL)-4 and IL-13 to induce M2-polarized macrophages. CD206, arginase-1 (Arg-1) and transforming growth factorβ1 (TGFβ1) expression in M2-polarized macrophages with or without CKIP-1 overexpression was evaluated. Moreover, GC cell lines (MKN45 and HGC27 cells) were co-cultured with CKIP-1-overexpressed M2-polarized macrophages, and the viability, migration and invasion of GC cells were measured. Additionally, immunoblotting assessed the expression of JAK/STAT3 signaling-related proteins and STAT3 agonist Colivelin was used to treat GC cells to perform the rescue experiments to analyze the changes of malignant phenotypes of GC cells. Results showed that CKIP-1 was downregulated in GC tissues and M2-polarized macrophages. CKIP-1 overexpression inhibited M2 macrophage polarization and decreased TGFβ1 secretion. Besides, elevated CKIP-1 expression in M2-polarized macrophages inhibited the viability, migration and invasion of GC cells. Furthermore, CKIP-1 overexpression inactivated JAK2/STAT3 signaling in GC cells by inhibiting TGFβ1 level. Specifically, Colivelin treatment abrogated the influences of CKIP-1 upregulation on the malignant phenotypes of GC cells. Collectively, CKIP-1 inhibits M2 macrophage polarization to suppress the progression of GC by inactivating JAK/STAT3 signaling pathway.

The multifaceted roles of macrophages in the transition from hepatitis to hepatocellular carcinoma: From mechanisms to therapeutic strategies

Macrophages are central to the progression from hepatitis to hepatocellular carcinoma (HCC), with their remarkable plasticity and ability to adapt to the changing liver microenvironment. Chronic inflammation, fibrosis, and ultimately tumorigenesis are driven by macrophage activation, making them key regulators of liver disease progression. This review explores the diverse roles of macrophages in the transition from hepatitis to HCC. In the early stages of hepatitis, macrophages are essential for pathogen clearance and tissue repair. However, chronic activation leads to prolonged inflammation, which exacerbates liver damage and promotes fibrosis. As the disease progresses to liver fibrosis, macrophages interact with hepatic stellate cells, fostering a pro-tumorigenic microenvironment that supports HCC development. In hepatocarcinogenesis, macrophages contribute to tumor initiation, growth, metastasis, immune evasion, cancer stem cell maintenance, and angiogenesis. Their functional plasticity enables them to adapt to the tumor microenvironment, thereby promoting tumor progression and resistance to therapy. Targeting macrophages represents a promising strategy for preventing and treating HCC. Therapeutic approaches, including reprogramming macrophage phenotypes to enhance anti-tumor immunity, blocking macrophage recruitment and activation, and utilizing nanoparticle-based drug delivery systems, may provide new avenues for combating HCC by modulating macrophage functions and tumor microenvironment dynamics.

PLIN2 Promotes Lipid Accumulation in Ascites-Associated Macrophages and Ovarian Cancer Progression by HIF1α/SPP1 Signaling

A major characteristic of ovarian cancer (OC) is its unique route of metastasis via ascites. The immune microenvironment in ascites remains understudied, leaving the mechanism of ascites-mediated abdominal metastasis obscure. Here, a single-cell transcriptomic landscape of CD45+ immune cells across multiple anatomical sites is depicted, including primary tumors, metastatic lesions, and ascites, from patients diagnosed with high-grade serous ovarian carcinoma (HGSOC). A novel subset of perilipin 2 high (PLIN2hi) macrophages are identified that are enriched in ascites and positively correlated with OC progression, hence being designated as "ascites-associated macrophages (AAMs)". AAMs are lipid-loaded with overexpression of the lipid droplet protein PLIN2. Overexpression or suppression of PLIN2 can enhance or inhibit tumor cell migration, invasion, and vascular permeability in vitro, which is also confirmed in vivo. Mechanistically, it is demonstrated that PLIN2 boosts HIF1α/SPP1 signaling in macrophages, thereby exerting pro-tumor functions. Finally, a PLIN2-targeting liposome is designed to efficiently suppress ascites production and tumor metastasis. Taken together, this work provides a comprehensive characterization of the cancer-promoting function and lipid-rich property of ascites-enriched PLIN2hi macrophages, establishes a link between lipid metabolism and hypoxia within the context of the ascites microenvironment, and elucidates the pivotal role of ascites in trans-coelomic metastasis of OC.

Genomic and micro-environmental insights into drug resistance in colorectal cancer liver metastases

BACKGROUND

Colorectal cancer (CRC) is known for its high heterogeneity, with liver metastases significantly impairing survival outcomes. Understanding the tumor microenvironment (TME) and genomic alterations in metastatic sites is crucial for developing personalized therapies that overcome drug resistance and improve prognosis.

METHODS

We profiled 54 CRC liver metastases, comparing them with 198 other metastatic lesions and normal liver tissues. By analyzing immune cell infiltration, stromal interactions, and key genomic alterations, we constructed an 11-gene prognostic model to predict survival and immunotherapy outcomes.

RESULTS

CRC liver metastases with high-risk profiles demonstrated enriched follicular helper T cells, activated dendritic cells, and M2 macrophages in the TME. Frequent mutations in APC, TP53, KRAS, and PIK3CA were identified, alongside altered EGFR signaling. The 11-gene model effectively stratified patients by prognosis and predicted immunotherapy responses, emphasizing the therapeutic potential of targeting resistance mechanisms.

CONCLUSIONS

This study reveals how genomic and TME-driven factors contribute to drug resistance in CRC liver metastases. Integrating these insights with clinical data could advance precision therapies, addressing the evolving challenge of tumor drug resistance in CRC.

Tumor-infiltrating myeloid cells; mechanisms, functional significance, and targeting in cancer therapy

Tumor-infiltrating myeloid cells (TIMs), which encompass tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), myeloid-derived suppressor cells (MDSCs), and tumor-associated dendritic cells (TADCs), are of great importance in tumor microenvironment (TME) and are integral to both pro- and anti-tumor immunity. Nevertheless, the phenotypic heterogeneity and functional plasticity of TIMs have posed challenges in fully understanding their complexity roles within the TME. Emerging evidence suggested that the presence of TIMs is frequently linked to prevention of cancer treatment and improvement of patient outcomes and survival. Given their pivotal function in the TME, TIMs have recently been recognized as critical targets for therapeutic approaches aimed at augmenting immunostimulatory myeloid cell populations while depleting or modifying those that are immunosuppressive. This review will explore the important properties of TIMs related to immunity, angiogenesis, and metastasis. We will also document the latest therapeutic strategies targeting TIMs in preclinical and clinical settings. Our objective is to illustrate the potential of TIMs as immunological targets that may improve the outcomes of existing cancer treatments.

Bacterial-Mediated In Situ Engineering of Tumour-Associated Macrophages for Cancer Immunotherapy

BACKGROUND/OBJECTIVES

Tumour-associated macrophages (TAMs) are critical components of the tumour microenvironment (TME), significantly influencing cancer progression and treatment resistance. This review aims to explore the innovative use of engineered bacteria to reprogram TAMs, enhancing their anti-tumour functions and improving therapeutic outcomes.

METHODS

We conducted a systematic review following a predefined protocol. Multiple databases were searched to identify relevant studies on TAMs, their phenotypic plasticity, and the use of engineered bacteria for reprogramming. Inclusion and exclusion criteria were applied to select studies, and data were extracted using standardised forms. Data synthesis was performed to summarise the findings, focusing on the mechanisms and therapeutic benefits of using non-pathogenic bacteria to modify TAMs.

RESULTS

The review summarises the findings that engineered bacteria can selectively target TAMs, promoting a shift from the tumour-promoting M2 phenotype to the tumour-fighting M1 phenotype. This reprogramming enhances pro-inflammatory responses and anti-tumour activity within the TME. Evidence from various studies indicates significant tumour regression and improved immune responses following bacterial therapy.

CONCLUSIONS

Reprogramming TAMs using engineered bacteria presents a promising strategy for cancer therapy. This approach leverages the natural targeting abilities of bacteria to modify TAMs directly within the tumour, potentially improving patient outcomes and offering new insights into immune-based cancer treatments. Further research is needed to optimise these methods and assess their clinical applicability.

Immunomodulatory role of exosome-derived content in pediatric medulloblastoma: a molecular subgroup perspective

Medulloblastoma (MB) is the most common malignant brain tumor in children, comprising four distinct subgroups: wingless (WNT), sonic hedgehog (SHH), Group 3, and Group 4. MYC amplification and metastatic dissemination are challenges in clinical management, and tumor-associated macrophages (TAMs) play an essential role in these intricate molecular processes. However, the influence of immune cells in MB metastasis and MYC-amp is unclear. Secretion of extracellular vesicles (EVs) has emerged as a pivotal mediator facilitating communication within the tumor microenvironment, orchestrating coordinated responses among immune cells during tumor initiation, progression, and tumor dissemination. Here, we sought to elucidate the role of exosome-derived MBs in promoting specific patterns of TAM polarization across different molecular subgroups of MB cell lines. CIBERSORTx analysis using a single-cell RNA dataset revealed an increase in M0 macrophages and a decreased proportion of M2 macrophages in MB patients with tumor dissemination in the central nervous system (CNS). Cell-derived exosomes were found to secrete high levels of IL-4, IL-10, and TGF-β, indicative of a protumor M2-profile pattern. Moreover, EVs from SHH TP53-mutated, Group 3/4, and MYC-amplified MBs induced dissimilar patterns of TNF-α and/or IL-1β overexpression. This study demonstrates that exosomes from pediatric MBs promote a predominant M2-macrophage phenotype and Group 3, Group 4, SHH TP53-mutated, and MYC-amplified MBs induced a mixed M1/M2 response pattern. These findings shed light on the pivotal role of exosomes in modulating the immune response, potentially contributing to immune escape in this malignant neoplasm.

Extracellular Vesicle-Based Strategies for Tumor Immunotherapy

Immunotherapy is one of the most promising approaches for cancer management, as it utilizes the intrinsic immune response to target cancer cells. Normally, the human body uses its immune system as a defense mechanism to detect and eliminate foreign objects, including cancer cells. However, cancers develop a 'switch off' mechanism, known as immune checkpoint proteins, to evade immune surveillance and suppress immune activation. Therefore, significant efforts have been made to develop the strategies for stimulating immune responses against cancers. Among these, the use of extracellular vesicles (EVs) to enhance the anti-tumor immune response has emerged as a particularly promising approach in cancer management. EVs possess several unique properties that elevate the potency in modulating immune responses. This review article provides a comprehensive overview of recent advances in this field, focusing on the strategic usage of EVs to overcome tumor-induced immune tolerance. We discuss the biogenesis and characteristics of EVs, as well as their potential applications in medical contexts. The immune mechanisms within the tumor microenvironment and the strategies employed by cancers to evade immune detection are explored. The roles of EVs in regulating the tumor microenvironment and enhancing immune responses for immunotherapy are also highlighted. Additionally, this article addresses the challenges and future directions for the development of EV-based nanomedicine approaches, aiming to improve cancer immunotherapy outcomes with greater precision and efficacy while minimizing off-target effects.

Tumor microenvironment-mimicking macrophage nanovesicles as a targeted therapy platform for colorectal cancer

Macrophages are a pivotal immune cell population in the tumor microenvironment of colorectal cancer (CRC). Differently-polarized macrophages could be exploited to yield naturally-tailored biomimetic nanoparticles for CRC targeting. Here, membrane proteins were isolated from the THP-1 cell line, and anti-tumor macrophages (M1) were obtained from differentiation of THP-1. Membrane proteins were isolated from THP-1 and M1 and used to produce lipid nanovesicles (LNVs; T-LNVs and M1-LNVs) by microfluidic process, which were loaded with doxorubicin (DOXO). The DOXO loaded T-LNVs and M1-LNVs showed similar size (120-145 nm), PDI (0.11-0.28), zeta potential (-15 to -30 mV) and drug loading efficiency (65-75 %). Mass-spectrometry confirmed the presence of the membrane proteins in the LNVs. The abundance of proteins related to stealth properties, cancer targeting, endothelial adhesion and immune-related markers was significantly different in T-LNVs and M1-LNVs. Cell culture studies showed that M1-LNVs possessed higher cancer cell targeting, uptake and cytotoxicity compared to T-LNVs. In vivo studies performed with zebrafish embryos showed that M1-LNVs yielded higher cancer cell targeting and cytotoxicity while systemic cytotoxicity was lower compared to free DOXO. These findings confirm the potentiality and versatility of M1-LNVs for cancer treatment, which could be exploited as new avenue of nanoparticles-based therapies for precision medicine.

Cancer stem cells and tumor-associated macrophages as mates in tumor progression: mechanisms of crosstalk and advanced bioinformatic tools to dissect their phenotypes and interaction

Cancer stem cells (CSCs) are a small subset within the tumor mass significantly contributing to cancer progression through dysregulation of various oncogenic pathways, driving tumor growth, chemoresistance and metastasis formation. The aggressive behavior of CSCs is guided by several intracellular signaling pathways such as WNT, NF-kappa-B, NOTCH, Hedgehog, JAK-STAT, PI3K/AKT1/MTOR, TGF/SMAD, PPAR and MAPK kinases, as well as extracellular vesicles such as exosomes, and extracellular signaling molecules such as cytokines, chemokines, pro-angiogenetic and growth factors, which finely regulate CSC phenotype. In this scenario, tumor microenvironment (TME) is a key player in the establishment of a permissive tumor niche, where CSCs engage in intricate communications with diverse immune cells. The "oncogenic" immune cells are mainly represented by B and T lymphocytes, NK cells, and dendritic cells. Among immune cells, macrophages exhibit a more plastic and adaptable phenotype due to their different subpopulations, which are characterized by both immunosuppressive and inflammatory phenotypes. Specifically, tumor-associated macrophages (TAMs) create an immunosuppressive milieu through the production of a plethora of paracrine factors (IL-6, IL-12, TNF-alpha, TGF-beta, CCL1, CCL18) promoting the acquisition by CSCs of a stem-like, invasive and metastatic phenotype. TAMs have demonstrated the ability to communicate with CSCs via direct ligand/receptor (such as CD90/CD11b, LSECtin/BTN3A3, EPHA4/Ephrin) interaction. On the other hand, CSCs exhibited their capacity to influence immune cells, creating a favorable microenvironment for cancer progression. Interestingly, the bidirectional influence of CSCs and TME leads to an epigenetic reprogramming which sustains malignant transformation. Nowadays, the integration of biological and computational data obtained by cutting-edge technologies (single-cell RNA sequencing, spatial transcriptomics, trajectory analysis) has significantly improved the comprehension of the biunivocal multicellular dialogue, providing a comprehensive view of the heterogeneity and dynamics of CSCs, and uncovering alternative mechanisms of immune evasion and therapeutic resistance. Moreover, the combination of biology and computational data will lead to the development of innovative target therapies dampening CSC-TME interaction. Here, we aim to elucidate the most recent insights on CSCs biology and their complex interactions with TME immune cells, specifically TAMs, tracing an exhaustive scenario from the primary tumor to metastasis formation.

Insights into CSF-1/CSF-1R signaling: the role of macrophage in radiotherapy

Macrophage plays an important role in homeostasis and immunity, and dysfunctional macrophage polarization is believed to be associated with the pathogenesis of tissue fibrosis and tumor progression. Colony stimulating factor-1 (CSF-1), a polypeptide chain cytokine, through its receptor (CSF-1R) regulates the differentiation of macrophages. Recently, the promising therapeutic potential of CSF-1/CSF-1R signaling pathway inhibition in cancer treatment is widely used. Furthermore, inhibition of CSF-1/CSF-1R signaling combined with radiotherapy has been extensively studied to reduce immunosuppression and promote abscopal effect. In addition, cumulative evidence demonstrated that M2 phenotype macrophage is dominant in tissue fibrosis and the inhibition of CSF-1/CSF-1R signaling pathway ameliorated pulmonary fibrosis, including radiation-induced lung fibrosis. Herein, we provide a comprehensive review of the CSF-1/CSF-1R signaling pathway in radiotherapy, with a focus on advances in macrophage-targeted strategies in the treatment of cancer and pulmonary fibrosis.

Comprehensive analysis reveals the tumor suppressor role of macrophage signature gene FCER1G in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) progression is closely linked to the role of macrophages. This study utilized single-cell RNA sequencing and genomic analysis to explore the characteristic genes of macrophages in HCC and their impact on patient prognosis. We obtained single-cell se-quencing data from seven HCC samples in the GEO database. Through principal component analysis and t-SNE dimensionality reduction, we identified 2,000 highly variable genes and per-formed clustering and annotation of 17 cell clusters, revealing 482 macrophage-related feature genes. A LASSO regression model based on these genes was developed to predict the prognosis of HCC patients, with validation in the TCGA-LIHC cohort demonstrating model accuracy (AUC = 0.78, 0.72, 0.71 for 1-, 3-, and 5-year survival rates, respectively). Additionally, patients in the high-risk group exhibited elevated tumor stemness scores, although no significant differences were observed in microsatellite instability (MSI) and tumor mutational burden (TMB) scores. Immune-related analyses revealed that FCER1G expression was downregulated in HCC and was associated with key pathways such as apoptosis and ferroptosis. Reduced FCER1G expression significantly affected HCC cell proliferation and migration. Our prognostic model provides new insights into precision and immunotherapy for HCC and holds significant implications for future clinical applications.

Understanding the Dual Role of Macrophages in Tumor Growth and Therapy: A Mechanistic Review

Macrophages are heterogeneous cells that are the mediators of tissue homeostasis. These immune cells originated from monocytes and are classified into two basic categories, M1 and M2 macrophages. M1 macrophages exhibit anti-tumorous inflammatory reactions due to the behavior of phagocytosis. M2 macrophages or tumor-associated macrophages (TAMs) are the most abundant immune cells in the tumor microenvironment (TME) and have a basic role in tumor progression by interacting with other immune cells in TME. By the expression of various cytokines, chemokines, and growth factors, TAMs lead to strengthening tumor cell proliferation, angiogenesis, and suppression of the immune system which further support invasion and metastasis. This review discusses recent and updated mechanisms regarding tumor progression by M2 macrophages. Moreover, the current therapeutic approaches targeting TAMs, their advantages, and limitations are also summarized, and further treatment approaches are outlined along with an elaboration of the tumor regression role of macrophages. This comprehensive review article possibly helps to understand the mechanisms underlying the tumor progression and regression role of macrophages in a comparative way from a basic level to the advanced one.

Arginine metabolism in myeloid cells in health and disease

Metabolic flexibility is key for the function of myeloid cells. Arginine metabolism is integral to the regulation of myeloid cell responses. Nitric oxide (NO) production from arginine is vital for the antimicrobial and pro-inflammatory responses. Conversely, the arginase 1 (ARG1)-dependent switch between the branch of NO production and polyamine synthesis downregulates inflammation and promotes recovery of tissue homeostasis. Creatine metabolism is key for energy supply and proline metabolism is required for collagen synthesis. Myeloid ARG1 also regulates extracellular arginine availability and T cell responses in parasitic diseases and cancer. Cancer, surgery, sepsis and persistent inflammation in chronic inflammatory diseases, such as neuroinflammatory diseases or arthritis, are associated with dysregulation of arginine metabolism in myeloid cells. Here, we review current knowledge on arginine metabolism in different myeloid cell types, such as macrophages, neutrophils, microglia, osteoclasts, tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs) and myeloid-derived suppressor cells (MDSCs). A deeper understanding of the function of arginine metabolism in myeloid cells will improve our knowledge on the pathology of several diseases and may set the platform for novel therapeutic applications.

The Single-Cell Landscape of Peripheral and Tumor-infiltrating Immune Cells in HPV- HNSCC

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. HPV-negative HNSCC, which arises in the upper airway mucosa, is particularly aggressive, with nearly half of patients succumbing to the disease within five years and limited response to immune checkpoint inhibitors compared to other cancers. There is a need to further explore the complex immune landscape in HPV-negative HNSCC to identify potential therapeutic targets. Here, we integrated two single-cell RNA sequencing datasets from 29 samples and nearly 300,000 immune cells to investigate immune cell dynamics across tumor progression and lymph node metastasis. Notable shifts toward adaptative immune cell populations were observed in the 14 distinct HNSCC-associated peripheral blood mononuclear (PBMCs) and 21 tumor-infiltrating immune cells (TICs) considering disease stages. All PBMCs and TICs revealed unique molecular signatures correlating with lymph node involvement; however, broadly, TICs increased ligand expression among effector cytokines, growth factors, and interferon-related genes. Pathway analysis comparing PBMCs and TICs further confirmed active cell signaling among Monocyte-Macrophage, Dendritic cell, Natural Killer (NK), and T cell populations. Receptor-ligand analysis revealed significant communication patterns shifts among TICs, between CD8+ T cells and NK cells, showing heightened immunosuppressive signaling that correlated with disease progression. In locally invasive HPV-negative HNSCC samples, highly multiplexed immunofluorescence assays highlighted peri-tumoral clustering of exhausted CD8+ T and NK cells, alongside their exclusion from intra-tumoral niches. These findings emphasize cytotoxic immune cells as valuable biomarkers and therapeutic targets, shedding light on the mechanisms by which the HNSCC sustainably evades immune responses.

Enhancing the anti-tumor activity and reprogramming M2 macrophages by delivering siRNAs against SIRPα and STAT6 via M1 exosomes and combining with anti-PD-L1

BACKGROUND

The invasive property of breast cancer and the complex composition of the tumor microenvironment (TME) antibodies like anti-PD-L1, can inhibit tumor growth by promoting macrophage phagocytosis. In this research, we used anti-PD-L1 antibody and siRNAs targeting SIRPα (siSIRPα) and STAT6 (siSTAT6). The siRNAs were transported to macrophages using M1-derived exosomes.

METHODS

For this purpose, exosomes were isolated from the supernatant of lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Next, siSIRPα and siSTAT6 were electroporated into the M1-exosomes. M1-exosomes without siRNA or loaded with different siRNAs were used to treat M2 macrophages. Then, the polarization of macrophages was evaluated. By co-culturing of treated macrophages with 4T1 cells, anti-tumor functions of macrophages were assessed.

RESULTS

It was demonstrated that siRNA-loaded M1-exosomes induced macrophage polarization into an M1 phenotype and promoted the anti-tumor effects of macrophages as shown by a reduction in migration, invasion and proliferation of 4T1 cells, as well as an enhancement of phagocytosis of 4T1 cells by macrophages.

CONCLUSION

This study demonstrated the potential of a multifaceted therapeutic approach targeting TAMs to enhance anti-tumor immune responses in breast cancer.

Targeting immune checkpoints on myeloid cells: current status and future directions

Myeloid cells accumulate extensively in most tumors and play a critical role in immunosuppression of the tumor microenvironment (TME). Like T cells, myeloid cells also express immune checkpoint molecules, which induce the immunosuppressive phenotype of these cells. In this review, we summarize the tumor-promoting function and immune checkpoint expression of four types of myeloid cells: macrophages, neutrophils, dendritic cells, and myeloid-derived suppressor cells, which are the main components of the TME. By summarizing the research status of myeloid checkpoints, we propose that blocking immune checkpoints on myeloid cells might be an effective strategy to reverse the immunosuppressive status of the TME. Moreover, combining nanotechnology, cellular therapy, and bispecific antibodies to achieve precise targeting of myeloid immune checkpoints can help to avoid the adverse effects of systemic administration, ultimately achieving a balance between efficacy and safety in cancer therapy.

Identification and Characterization of Prognostic Macrophage Subpopulations for Human Esophageal Carcinoma

AIMS

The aim of the present study was to investigate the relationship between the cellular ecosystem and the progression of esophageal carcinoma (ESCA) based on the evolution of macrophages and to analyze the potential of using macrophages as a new therapeutic approach in ESCA treatment.

BACKGROUND

Macrophage-based immunotherapy could be used for treating ESCA patients, but its clinical application is limited by the intra-tumor heterogeneity of macrophages.

OBJECTIVE

The objective of this study was to analyze the diversity, differentiation trajectory, and intercellular communication of macrophages in ESCA and its prognostic significance.

METHODS

Single-cell RNA sequencing (scRNA-seq) data in the GSE154763 dataset were downloaded from Gene Expression Omnibus (GEO) to identify cell clusters and annotate cell types using the Seurat R package. The scRNA-seq profiles of macrophages were extracted, and cluster analysis was performed to identify macrophage subsets. The differentiation trajectories of macrophage subgroups were visualized employing Monocle2. Finally, ligand-receptor pairs and communication intensity among the classified subgroups were analyzed using Cell Chat.

RESULTS

A total of 8 cell types were identified between ESCA tissues and paracancer tissues. The most abundant macrophages in ESCA tissues were further divided into 5 cell clusters. Compared with the normal tissues, the proportion of HSPA6+ macrophages in ESCA tissues increased the most, and the number of ligand-receptor pairs that mediated the communication of HSPA6+ macrophages with mast cells and monocytes also increased significantly. More importantly, a high proportion of HSPA6+ macrophages was inversely correlated with the survival outcomes for ESCA patients.

CONCLUSIONS

This study analyzed the diversity, distribution and differentiation trajectory of macrophages in ESCA tissues at single-cell level and classified a prognostic macrophage subtype (HSPA6+ macrophages) of ESCA, providing a theoretical basis for macrophage-targeted therapy in ESCA.

Histone lactylation in macrophage biology and disease: from plasticity regulation to therapeutic implications

Epigenetic modifications have been identified as critical molecular determinants influencing macrophage plasticity and heterogeneity. Among these, histone lactylation is a recently discovered epigenetic modification. Research examining the effects of histone lactylation on macrophage activation and polarization has grown substantially in recent years. Evidence increasingly suggests that lactate-mediated changes in histone lactylation levels within macrophages can modulate gene transcription, thereby contributing to the pathogenesis of various diseases. This review provides a comprehensive analysis of the role of histone lactylation in macrophage activation, exploring its discovery, effects, and association with macrophage diversity and phenotypic variability. Moreover, it highlights the impact of alterations in macrophage histone lactylation in diverse pathological contexts, such as inflammation, tumorigenesis, neurological disorders, and other complex conditions, and demonstrates the therapeutic potential of drugs targeting these epigenetic modifications. This mechanistic understanding provides insights into the underlying disease mechanisms and opens new avenues for therapeutic intervention.

Immune biomarkers and predictive signatures in gastric cancer: Optimizing immunotherapy responses

Gastric cancer is a malignant disease with a poor prognosis and few therapeutic options once it has advanced. Immunotherapy using ICIs has emerged as a viable therapeutic method; nevertheless, reliable immunological biomarkers are required to identify who may benefit from these therapies. It focuses on key immune biomarkers and predictive signatures in gastric cancer, such as PD-L1 expression, microsatellite instability (MSI), tumor mutational burden (TMB), and Epstein-Barr virus (EBV) status, to optimize gastric cancer patients' immunotherapy responses. PD-L1 expression is a popular biomarker for ICI effectiveness. Tumors with high MSI-H and TMB are the most susceptible to ICIs because they are highly immunogenic. EBV-positive stomach tumors are highly immunogenic, and immunotherapy has a high response rate. Combining composite biomarker panels with multi-omics-based techniques improved patient selection accuracy. In recent years, machine learning models have been integrated into next-generation sequencing. Dynamic, real-time-monitorable biomarkers for real-time immune response monitoring are also being considered. Thus, enhancing biomarker-driven immunotherapy is critical for improving clinical outcomes with gastric cancer. There is still more work to be done in this field, and verifying developing biomarkers will be an important component in the future of customized cancer therapy.

Bisphosphonate-mineralized nano-IFNγ suppresses residual tumor growth caused by incomplete radiofrequency ablation through metabolically remodeling tumor-associated macrophages

Rationale: Radiofrequency ablation (RFA), as a minimally invasive surgery strategy based on local thermal-killing effect, is widely used in the clinical treatment of multiple solid tumors. Nevertheless, RFA cannot achieve the complete elimination of tumor lesions with larger burden or proximity to blood vessels. Incomplete RFA (iRFA) has even been validated to promote residual tumor growth due to the suppressive tumor immune microenvironment (TIME). Therefore, exploring strategies to remodel TIME is a key issue for the development of RFA therapy. Methods: The negative effect of iRFA on colorectal cancer therapy was firstly investigated. Then a zoledronate-mineralized nanoparticle loaded with IFNγ (Nano-IFNγ/Zole) was designed and its tumor suppressive efficacy was evaluated. Finally, the metabolic reprogramming mechanism of Nano-IFNγ/Zole on tumor-associated macrophages (TAMs) was studied in detail. Results: We found iRFA dynamically altered TIME and promoted TAM differentiation from M1 to M2. Nano-IFNγ/Zole was fabricated to metabolically remodel TAMs. IFNγ in Nano-IFNγ/Zole concentrated in the ablation site to play a long-term remodeling role. Acting on mevalonate pathway, Nano-IFNγ/Zole was discovered to reduce lysosomal acidification and activate transcription factor TFEB by inhibiting isoprene modification of the Rab protein family. These mechanisms, in conjunction with IFNγ-activated JAK/STAT1 signaling, accelerated the reprogramming of TAMs from M2 to M1, and suppressed tumor recurrence after iRFA. Conclusions: This study elaborates the synergistic mechanism of zoledronate and IFNγ in Nano-IFNγ/Zole to reshape suppressive TIME caused by iRFA by remodeling TAMs, and highlights the important value of metabolically induced cellular reprogramming. Since both zoledronate and IFNγ have already been approved in clinics, this integrative nano-drug delivery system establishes an effective strategy with great translational promise to overcome the poor prognosis after clinically incomplete RFA.

Macrophage Infiltration and ITGB2 Expression in ESCC: A Novel Correlation

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is one of the most prevalent and lethal malignancies worldwide. Despite progress in immunotherapy for cancer treatment, its application and efficacy in ESCC remain limited. Therefore, there is an ongoing need to explore potential molecules and therapeutic strategies related to tumor immunity in ESCC.

METHODS

In this study, we integrated high-throughput sequencing data, gene chip data, single-cell sequencing data, and various bioinformatics analysis methods along with experimental approaches to identify key genes involved in immune infiltration in ESCC and investigate their relationship with immune cell development, as well as the potential of these key genes in immunotherapy.

RESULTS

We discovered and validated a positive correlation between macrophage infiltration and ITGB2 expression in ESCC. ITGB2 is overexpressed in ESCC and has potential as a prognostic biomarker for the disease. We present for the first time the finding that the expression of ITGB2 in infiltrating macrophages increases as these macrophages polarize toward a tumor-promoting phenotype in ESCC. Moreover, during the progression of ESCC, ITGB2 expression in infiltrating macrophages is upregulated. The higher the expression of ITGB2, the more feasible it is to target macrophages. Additionally, we found that evaluating immune therapy responses in ESCC patients through ITGB2 expression is a viable approach. Furthermore, we identified three miRNAs associated with abnormal ITGB2 expression, providing insights into the upstream molecular interactions of ITGB2.

CONCLUSIONS

Macrophage infiltration in ESCC is closely associated with ITGB2, which holds significant potential for immunotherapy applications in ESCC. Based on our findings and prior studies, we propose a novel hypothesis: inducing M1 macrophages in vitro, knocking out ITGB2, and then reinfusing these ITGB2-knockout M1 macrophages into ESCC patients may represent a promising new immunotherapy strategy, providing a new avenue for ESCC immunotherapy.

The Kaposi sarcoma herpesvirus control of monocytes, macrophages, and the tumour microenvironment

Kaposi sarcoma herpesvirus (KSHV) is an oncogenic DNA virus associated with various malignancies, including tumours like Kaposi sarcoma and Primary effusion lymphoma. Recently, the importance of the tumour microenvironment in KSHV-associated tumours is being studied. New studies utilizing human primary cells, co-culture experiments with KSHV-infected cells, and modern techniques like time-resolved single cell analysis, have significantly advanced the understanding of KSHV interactions with monocytes and macrophages. These cells play key roles in shaping the tumour microenvironment. It has become clear that KSHV-infected endothelial cells regulate the growth and the differentiation of monocytes and macrophages. Monocytes and macrophages, in turn, can regulate KSHV-infected cells in tumorigenesis and cytokine secretion, leading to the pro-tumour microenvironment. Further investigations into the viral regulation of monocytes and macrophages thus have potential to lead to the discovery of novel antitumour therapeutics.

Therapeutic advantage of combinatorial chimeric antigen receptor T cell and chemotherapies

Chimeric antigen receptor (CAR) T cell therapies have transformed outcomes for many patients with hematological malignancies. However, some patients do not respond to CAR T cell treatment, and adapting CAR T cells for treatment of solid and brain tumors has been met with many challenges, including a hostile tumor microenvironment and poor CAR T cell persistence. Thus, it is unlikely that CAR T cell therapy alone will be sufficient for consistent, complete tumor clearance across patients with cancer. Combinatorial therapies of CAR T cells and chemotherapeutics are a promising approach for overcoming this because chemotherapeutics could augment CAR T cells for improved antitumor activity or work in tandem with CAR T cells to clear tumors. Herein, we review efforts toward achieving successful CAR T cell and chemical drug combination therapies. We focus on combination therapies with approved chemotherapeutics because these will be more easily translated to the clinic but also review nonapproved chemotherapeutics and drug screens designed to reveal promising new CAR T cell and chemical drug combinations. Overall, this review highlights the promise of CAR T cell and chemotherapy combinations with a specific focus on how combinatorial therapy overcomes challenges faced by either monotherapy and supports the potential of this therapeutic strategy to improve outcomes for patients with cancer. SIGNIFICANCE STATEMENT: Improving currently available CAR T cell products via combinatorial therapy with chemotherapeutics has the potential to drastically expand the types of cancers and number of patients that could benefit from these therapies when neither alone has been sufficient to achieve tumor clearance. Herein, we provide a thorough review of the current efforts toward studying CAR T and chemotherapy combinatorial therapies and offer perspectives on optimal ways to identify new and effective combinations moving forward.

IL-17A/CEBPβ/OPN/LYVE-1 axis inhibits anti-tumor immunity by promoting tumor-associated tissue-resident macrophages

Tumor-associated macrophages (TAMs) are a critical component of the immunosuppressive tumor microenvironment, comprising monocyte-derived macrophages (MDM-TAMs) and tissue-resident macrophages (TRM-TAMs). Here, we discovered that TRM-TAMs mediate the pro-tumor effects of interleukin (IL)-17A and that IL-17A-driven tumor progression requires tumor cell production of osteopontin (OPN). Mechanistically, we identified CEBPβ as a transcription factor downstream of IL-17A in tumor cells and LYVE-1 as an OPN receptor on TRM-TAMs. IL-17A stimulates tumor cell production of OPN, and OPN/LYVE-1 signaling activates the JNK/c-Jun pathway, leading to the proliferation of immunosuppressive LYVE-1+ TRM-TAMs. Unlike its effect on LYVE-1+ TRM-TAMs, OPN interacts with α4β1 to promote the chemotaxis of LYVE-1- MDM-TAMs toward tumors. IL-17A neutralization, OPN inactivation in tumor cells, or LYVE-1 deletion in macrophages inhibited TAMs and enhanced anti-tumor immune responses and anti-PDL1 therapy. Thus, the IL-17A/CEBPβ/OPN/LYVE-1 axis offers a mechanism suppressing anti-tumor immune responses and, hence, an effective therapeutic target for cancer.

Napabucasin-loaded PLGA nanoparticles trigger anti-HCC immune responses by metabolic reprogramming of tumor-associated macrophages

BACKGROUND

JAK/STAT3 is one of the critical signaling pathways involved in the occurrence and development of hepatocellular carcinoma (HCC). BBI608 (Napabucasin), as a novel small molecule inhibitor of STAT3, has shown previously excellent anti-HCC effects in vitro and in mouse models. However, low bioavailability, high cytotoxicity and other shortcomings limit its clinical application. In this study, PLGA was selected to prepare Napabucasin PLGA nanoparticles (NPs) by solvent evaporation method, overcoming these limitations and improving the passive targeting effect that nanoparticle mediated. Base on this, we systematically evaluated the anti-HCC effect of Napabucasin-PLGA NPs and explored the underlying mechanisms.

METHODS

Napabucasin-PLGA NPs were prepared by solvent evaporation method. CCK-8 assay, Annexin V/PI double staining, RT-qPCR, colony formation assay, and Western blotting were performed to evaluate the anti-HCC effect of Napabucasin-PLGA NPs in vitro. Proliferation assay and migration assay were used to detect the effects of Napabucasin-PLGA NPs-treated HCC-TAMs on tumor biological characteristics of HCC cells. Flow cytometry was used to detect anti-HCC immune responses induced by Napabucasin-PLGA NPs in vivo.

RESULTS

Our results demonstrated that Napabucasin-PLGA NPs could improve the bioavailability of Napabucasin and enhance Napabucasin-mediated the anti-HCC effects in vitro and in vivo with no significant drug toxicity. In addition to the direct inhibitory effects on the tumor biological characteristics of HCC cells, Napabucasin-PLGA NPs could promote the polarization of macrophages from tumor-promoting M2-type to anti-tumor M1-type, improving the tumor immune microenvironment and augmenting T cell-mediated anti-tumor responses. The underlining mechanisms showed Napabucasin-PLGA NPs suppressed the STAT3/FAO signaling axis in HCC-induced tumor-associated macrophages (TAMs).

CONCLUSIONS

These findings demonstrated Napabucasin-PLGA NPs is a potential therapeutic candidate for HCC, and provided a new theoretical and experimental basis for further development and clinical application of Napabucasin.

Adipocyte-derived CXCL10 in obesity promotes the migration and invasion of ovarian cancer cells

BACKGROUND

As a widespread epidemic, obesity poses a significant risk to health and leads to physiological abnormalities, including diabetes mellitus and inflammation. Obesity-induced inflammation can accelerate the development of various cancers; however, the role of obesity in the migration of ovarian carcinoma is still unclear.

RESULTS

Twenty-four commonly upregulated genes were identified from single-cell RNA sequencing datasets of both ovarian carcinoma and adipose tissue of obese humans, with the chemokine CXCL10 showing a significant increase in adipose tissues associated with obesity. And CXCL10 treated primed macrophages exhibit both direct and indirect effects on the proliferation, apoptosis, migration, and invasion of ovarian adenocarcinoma cells. The treatment of CXCL10 on the SKOV3 cells enhances FAK expression and phosphorylation, thereby accelerating the migration and invasion of ovarian cancer cells. Conditioned medium-derived from CXCL10-treated THP-1 cells significantly promoted ovarian cancer cell migration and invasion, which may be attributed to the increased expression of C1QA, C1QC, CCL24, and IL4R in macrophages.

CONCLUSIONS

Obesity exacerbates the production of CXCL10 from adipose tissues in obese women. CXCL10 is a key hub factor between developments of ovarian cancer and adipose tissues in obese. Targeting adipose-derived CXCL10 or its downstream macrophages may be a potential strategy to alleviate ovarian cancer accompanied by obesity.

Disrupting Notch signaling related HES1 in myeloid cells reinvigorates antitumor T cell responses

BACKGROUND

Tumor-associated macrophages (TAMs) are immunosuppressive cells within the tumor microenvironment (TME) that hinder anti-tumor immunity. Notch signaling is a pathway crucial for TAM differentiation and function. Here, we investigate the role of HES1, a downstream target of Notch signaling, in TAM-mediated immunosuppression and explore its potential as a target for cancer immunotherapy.

METHODS

In this work, we constructed conditional Hes1 knockout mice to selectively delete Hes1 in TAMs. We further analyzed the TME composition, T cell infiltration and activation, and anti-tumor effects in these mice, both alone and in combination with PD-1 checkpoint blockade.

RESULTS

Our study showed that expression levels of Notch target Hes1 were increase in TAMs and mice with conditional knockout of Hes1 gene in TAMs exhibited decreased tumor growth, with increased infiltration and activation of cytotoxic T cells in tumors. Expression of tumor promoting factors was critically altered in Hes1-conditional KO TAMs, leading to the improved tumor microenvironment. Notably, arginase-1 expression was decreased in Hes1-conditional KO mice. Arg1 is known to deplete arginine and deactivate T cells in the TME. Administration of anti-PD-1 monoclonal antibody inhibited tumor growth to a greater extent in Hes1-conditional KO mice than in WT mice.

CONCLUSIONS

We identified a pivotal role for the Notch signaling pathway in shaping TAM function, suggesting that T-cell dysfunction in the TME is caused when the Notch target, HES1, in TAMs is upregulated by tumor-associated factors (TAFs), which, in turn, increases the expression of arginase-1. Targeting HES1 in TAMs appears to be a promising strategy for cancer immunotherapy.

Dendritic cell activation by iron oxide nanoparticles depends on the extracellular environment

Nanoparticles can exert immune modulating effects in a host depending on composition, mode of administration, and type of disease. Although the specific mechanisms of nanoparticle-induced immune responses remain unclear, their uptake by macrophages and other phagocytic innate immune cells is considered to be a key event. Our objective here was to ascertain if nanoparticle-mediated activation of dendritic cells (DCs) occurs in vitro or in vivo when exposed to hydroxyethyl starch-coated iron oxide nanoparticles. For the present studies, our choice of nanoparticles, animal model, and experimental design is motivated by our previously published observations that systemic exposure can induce antitumor adaptive immune responses in mouse models of metastatic breast cancer. Here, we began by assessing the potential toxicity of systemic exposure to commercially available starch-coated Bionized Nanoferrite® nanoparticles (BP) by measuring body weight, complete blood count, and enzyme parameters in healthy FVB/NJ mice after repeated BP dosing. We observed no evidence of toxicity at doses up to 25 mg Fe per mouse, five-fold higher than those used in subsequent in vivo experiments. We then measured the expression of surface maturation markers (CD86, MHC II) in DCs incubated with BP in vitro. Although DCs cultured with BP revealed high levels of nanoparticle uptake, neither JAWSII dendritic cells nor bone marrow derived dendritic cells (BMDCs) showed significant changes in marker expression to indicate stimulation of maturation and effector function. To assess whether BP interactions in vivo produced different effects, we analyzed CD80, CD86, and MHC II expression of DCs recovered from the livers, spleens, bone marrows, and lymph nodes of mice injected once with BP (5 mg Fe). Interestingly, only DCs in spleens and bone marrow cells responded to BP exposure. DCs recovered from other organs showed no evidence of increased activation. These findings highlight complex interactions between living systems and nanoparticles, and their potential to mediate context-specific and selective activation of innate immune cells. Our study also emphasizes that results obtained from in vitro experiments must be interpreted with caution, as they may not faithfully represent responses in living systems.

Exploring the Complexity of Pan-Cancer: Gene Convergences and in silico Analyses

Cancer is a complex and multifaceted group of diseases characterized by highly intricate mechanisms of tumorigenesis and tumor progression, which complicates diagnosis, prognosis, and treatment. In recent years, targeted therapies have gained prominence by focusing on specific mutations and molecular features unique to each tumor type, offering more effective and personalized treatment options. However, it is equally critical to explore the genetic commonalities across different types of cancer, which has led to the rise of pan-cancer studies. These approaches help identify shared therapeutic targets across various tumor types, enabling the development of broader and potentially more widely applicable treatment strategies. This review aims to provide a comprehensive overview of key concepts related to tumors, including tumorigenesis processes, the tumor microenvironment, and the role of extracellular vesicles in tumor biology. Additionally, we explore the molecular interactions and mechanisms driving tumor progression, with a particular focus on the pan-cancer perspective. To achieve this, we conducted an in silico analysis using publicly available datasets, which facilitated the identification of both common and divergent genetic and molecular patterns across different tumor types. By integrating these diverse areas, this review offers a clearer and deeper understanding of the factors influencing tumorigenesis and highlights potential therapeutic targets.

Development of anti-cancer drugs for tumor-associated macrophages: a comprehensive review and mechanistic insights

This review provides an in-depth summary of the development of anti-cancer drugs for tumor-associated macrophages (TAMs), with a particular focus on the development and tissue specialization of macrophages, and factors influencing the polarization of M1 and M2 macrophages, and mechanistic insights underlying the targeting therapeutic approaches. TAMs, pivotal in the tumor microenvironment, exhibit notable plasticity and diverse functional roles. Influenced by the complex milieu, TAMs polarize into M1-type, which suppresses tumors, and M2-type, which promotes metastasis. Notably, targeting M2-TAMs is a promising strategy for tumor therapy. By emphasizing the importance of macrophages as a therapeutic target of anti-cancer drugs, this review aims to provide valuable insights and research directions for clinicians and researchers.

Mild Magnetothermal Immunotherapy for Malignant Pleural Effusion

Malignant pleural effusion (MPE) is one of the most difficult complications of cancer to cure, usually indicating poor prognosis in late-stage cancer patients. Due to the presence of a large number of tumor-associated immune cells with the tumor promoting phenotype in MPE and pleural tumors, current clinical therapy offers limited effectiveness. Here, a mild magnetothermal regulation strategy is proposed based on a magnetic nanocatlytic nanoplatform ZCMF@PEG-AF (ZCMF-AF) constructed by surface-modifying anti-F4/80 antibody (AF) on ZnCoFe2O4@ZnMnFe2O4 magnetic nanoparticles (ZCMF) to target and polarize tumor-associated macrophages. Under alternating magnetic field-induced hyperthermia (41-42 °C), ZCMF-AF exhibits in situ nanocatalytic production of hydroxyl radicals via released iron ions under acidic cellular environment, which induces repolarization from the immunosuppressed M2 phenotype to the M1 phenotype. More importantly, the tumor cell damage induced by M1 macrophages and magnetic hyperthermia promote the maturation of dendritic cells, which subsequently awakens cytotoxic T lymphocytes to combat tumor cells. The integrated innate and adaptive immunity activations based on ZCMF-AF nano-immunomedicine through intrapleural administration elicit substantially regulated immune microenvironment of MPE and pleural tumors. Moreover, the interpleural magnetic nanoparticle-based immunotherapy effectively reduced the MPE volume and inhibited tumor growth in the pleural cavity, significantly prolonging the survival of the MPE-bearing mice.

A digital manufactured microfluidic platform for flexible construction of 3D co-culture tumor model with spatiotemporal resolution

The specific spatiotemporal distribution of diverse components in tumor microenvironment plays a crucial role in the cancer progression.In vitrothree-dimensional (3D) tumor models with polydimethylsiloxane (PDMS) based microfluidic platform have been applied as useful tool to conduct studies from cancer biology to drug screening. However, PDMS has not been welcomed as a standardized commercial application for preclinical screening due to inherent limitations in scale-up production and molecule absorption. Here, we present a novel microfluidic platform to flexibly construct 3D co-culture models with spatiotemporal resolution by using multiple digital manufacturing technologies. The platform, which consist of reduplicative microfluidic chips, is made of biocompatible poly methyl methacrylate by fast laser cutting. Each replica includes a simple microfluidic chamber without internal structures which can be flexibly post-fabricated according to various research requirements. Digital light processing based 3D bioprinting was used to pattern fine hydrogel structures for post-fabrication on-chip. By multi-step bioprinting and automatic image alignment, we show that this approach provides sufficient design flexibility to construct 3D co-culture tumor model with spatiotemporal resolution to replicate microarchitecture of tumor microtissuein situ. And the tumor model has the potential to mimic tumor biology behaviors which can be used for mechanism study and drug test. Our microengineered tumor model may serve as an enabling tool to recapitulate pathophysiological complexity of tumor, and to systematically examine the contribution of the tumor microenvironment to the cancer progression. The proposed strategy can also be applied to help engineer diverse meaningfulin vitromodels for extensive biomedical applications, from physiology and disease study to therapy evaluation.

Modeling development of breast cancer: from tumor microenvironment to preclinical applications

Breast cancer is a complex disease and its progression is related not only to tumor cells but also to its microenvironment, which can not be sufficiently reflected by the traditional monolayer cell culture manner. The novel human cancer models comprising tumor microenvironment (TME), such as tumor organoids and organs-on-a-chip, has been established in recent years to help elucidate the underlying mechanisms of tumorigenesis and promote the development of cancer therapies. In this review, we first discuss the current state of breast cancer and their treatment strategies, and elucidates the complex properties of TME of breast cancer in vivo. The culture models used in breast cancer research are then summarized with insights into recent development. Finally, we also conclude by discussing the current limitations and future directions of culture models in breast cancer research for providing a preclinical reference for the precise treatment of cancer patients.

Immune safety challenges facing the preclinical assessment and clinical progression of cell therapies

The promise of curative outcomes for life-limiting diseases using cell therapies is starting to become a reality, not only for patients with end-stage cancer, but also increasingly for regenerative therapies, including dentistry, ocular, neurodegenerative, and cardiac diseases. The introduction of often genetically modified cells into a patient can come with an extensive range of safety considerations. From an immune perspective, cell-based therapies carry inherent consequences and consideration of factors, such as the cell source (donor-derived autologous cells versus allogeneic cells), the intrinsic cellular nature of the therapy, and engineering/manufacturing methods, all of which influence the likelihood of inducing unwanted immune responses. Here, we provide an overview of the potential immune safety risks associated with cell therapies and explore possible mitigation approaches.

Targeting of TAMs: can we be more clever than cancer cells?

АBSTRACT: With increasing incidence and geography, cancer is one of the leading causes of death, reduced quality of life and disability worldwide. Principal progress in the development of new anticancer therapies, in improving the efficiency of immunotherapeutic tools, and in the personification of conventional therapies needs to consider cancer-specific and patient-specific programming of innate immunity. Intratumoral TAMs and their precursors, resident macrophages and monocytes, are principal regulators of tumor progression and therapy resistance. Our review summarizes the accumulated evidence for the subpopulations of TAMs and their increasing number of biomarkers, indicating their predictive value for the clinical parameters of carcinogenesis and therapy resistance, with a focus on solid cancers of non-infectious etiology. We present the state-of-the-art knowledge about the tumor-supporting functions of TAMs at all stages of tumor progression and highlight biomarkers, recently identified by single-cell and spatial analytical methods, that discriminate between tumor-promoting and tumor-inhibiting TAMs, where both subtypes express a combination of prototype M1 and M2 genes. Our review focuses on novel mechanisms involved in the crosstalk among epigenetic, signaling, transcriptional and metabolic pathways in TAMs. Particular attention has been given to the recently identified link between cancer cell metabolism and the epigenetic programming of TAMs by histone lactylation, which can be responsible for the unlimited protumoral programming of TAMs. Finally, we explain how TAMs interfere with currently used anticancer therapeutics and summarize the most advanced data from clinical trials, which we divide into four categories: inhibition of TAM survival and differentiation, inhibition of monocyte/TAM recruitment into tumors, functional reprogramming of TAMs, and genetic enhancement of macrophages.

Exosome crosstalk between cancer stem cells and tumor microenvironment: cancer progression and therapeutic strategies

Cancer stem cells (CSCs) represent a small yet pivotal subset of tumor cells endowed with self-renewal capabilities. These cells are intricately linked to tumor progression and are central to drug resistance, metastasis, and recurrence. The tumor microenvironment (TME) encompasses the cancer cells and their surrounding milieu, including immune and inflammatory cells, cancer-associated fibroblasts, adjacent stromal tissues, tumor vasculature, and a variety of cytokines and chemokines. Within the TME, cells such as immune and inflammatory cells, endothelial cells, adipocytes, and fibroblasts release growth factors, cytokines, chemokines, and exosomes, which can either sustain or disrupt CSCs, thereby influencing tumor progression. Conversely, CSCs can also secrete cytokines, chemokines, and exosomes, affecting various components of the TME. Exosomes, a subset of extracellular vesicles (EVs), carry a complex cargo of nucleic acids, proteins, and lipids, playing a crucial role in the communication between CSCs and the TME. This review primarily focuses on the impact of exosomes secreted by CSCs (CSC-exo) on tumor progression, including their roles in maintaining stemness, promoting angiogenesis, facilitating metastasis, inducing immune suppression, and contributing to drug resistance. Additionally, we discuss how exosomes secreted by different cells within the TME affect CSCs. Finally, we explore the potential of utilizing exosomes to mitigate the detrimental effects of CSCs or to target and eliminate them. A thorough understanding of the exosome-mediated crosstalk between CSCs and the TME could provide valuable insights for developing targeted therapies against CSCs.

Age-associated modulation of TREM1/2- expressing macrophages promotes melanoma progression and metastasis

Aging is a known risk factor for melanoma, yet mechanisms underlying melanoma progression and metastasis in older populations remain largely unexplored. Among the current knowledge gaps is how aging alters phenotypes of cells in the melanoma microenvironment. Here we demonstrate that age enriches the immunosuppressor tumor microenvironment, which is linked to phenotypes associated with melanoma metastasis. Among cellular populations enriched by aging were macrophages with a tolerogenic phenotype expressing TREM2 and dysfunctional CD8-positive cells with an exhausted phenotype, while macrophages with profibrotic phenotype expressing TREM1 were depleted. Notably, TREM1 inhibition decreased melanoma growth in young but not old mice, whereas TREM2 inhibition prevented lung metastasis in aged mice. These data identify novel targets associated with melanoma metastasis and may guide aged-dependent immunotherapies.