Myeloid-derived suppressor cells: an emerging target for anticancer immunotherapy

Euphorbia helioscopia L. inhibits lung tumorigenesis through alleviating exhausted T cell induced by chronic inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Euphorbia helioscopia L. (ZQ) is a very effective traditional Chinese medicine for treating pneumonia and lung cancer. However, the effects and mechanisms by which ZQ prevents lung tumorigenesis in the presence of chronic inflammation remain unexplored.

AIM

To examine the effects and mechanisms of ZQ in alleviating chronic inflammation-induced T cell exhaustion and inhibiting lung tumorigenesis.

METHODS

A mice model of lung tumorigenesis under chronic inflammation conditions was established by repeated administration of lipopolysaccharide (LPS) and exposure to the tobacco carcinogen nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Mice were treated with ZQ (0.9, 1.8, and 3.6 g/kg/day) for 25 weeks. Lung pathology and tumor incidence were assessed, and inflammatory cytokine levels in bronchoalveolar lavage fluid (BALF) and serum were measured. Additionally, the proportions of CD3+ T, CD4+ T, and CD8+ T cells and their inhibitory receptors expression were evaluated. In vitro, T cell exhaustion models were induced using inflammatory-conditioned media, followed by treatment with ZQ (0.5, 2, 8 μg/mL). T cell exhaustion markers and characteristics were analyzed, and molecular mechanisms were explored using RNA sequencing and Immunoblotting analysis.

RESULTS

In vivo, ZQ significantly reduced inflammatory infiltration and lung damage, tumor incidence, number, size, and lung and spleen indices in mice. It also markedly lowered the levels of pro-inflammatory cytokines and immunosuppressive cytokines in BALF and serum. Additionally, ZQ improved the proportions of CD3+ T, CD4+ T, and CD8+ T cells and significantly decreased the expression of inhibitory receptors on CD4+ T and CD8+ T cells in the lung tissues and spleen. In vitro, ZQ effectively alleviated T cell exhaustion induced by the inflammatory environment, marked by reduced expression of inhibitory receptors, increased cytokine secretion, improved proliferation, and enhanced tumoricidal activity. RNA sequencing revealed that ZQ significantly downregulated the JAK-STAT signaling and upregulated stemness-associated pathways. Immunoblotting results indicated that treatment with ZQ markedly reduced the phosphorylation of Signal transducer and activator of transcription 3 (STAT3) and increased the expression of T cell factor -1/7 (TCF1/7).

CONCLUSION

ZQ inhibits lung tumorigenesis in LPS/NNK-treated mice through alleviating exhausted T cells induced by chronic inflammation, which is attributed to the suppression of STAT3 activation and the maintenance of stemness characteristics in T cells. These findings provide experimental evidence for the potential use of ZQ in preventing and treating lung tumourigenesis in patients with chronic inflammation and the clinical management of lung cancer patients with concomitant chronic inflammation.

Metabolic crossroads: unravelling immune cell dynamics in gastrointestinal cancer drug resistance

Metabolic reprogramming within the tumor microenvironment (TME) plays a critical role in driving drug resistance in gastrointestinal cancers (GI), particularly through the pathways of fatty acid oxidation and glycolysis. Cancer cells often rewire their metabolism to sustain growth and reshape the TME, creating conditions such as nutrient depletion, hypoxia, and acidity that impair antitumor immune responses. Immune cells within the TME also undergo metabolic alterations, frequently adopting immunosuppressive phenotypes that promote tumor progression and reduce the efficacy of therapies. The competition for essential nutrients, particularly glucose, between cancer and immune cells compromises the antitumor functions of effector immune cells, such as T cells. Additionally, metabolic by-products like lactate and kynurenine further suppress immune activity and promote immunosuppressive populations, including regulatory T cells and M2 macrophages. Targeting metabolic pathways such as fatty acid oxidation and glycolysis presents new opportunities to overcome drug resistance and improve therapeutic outcomes in GI cancers. Modulating these key pathways has the potential to reinvigorate exhausted immune cells, shift immunosuppressive cells toward antitumor phenotypes, and enhance the effectiveness of immunotherapies and other treatments. Future strategies will require continued research into TME metabolism, the development of novel metabolic inhibitors, and clinical trials evaluating combination therapies. Identifying and validating metabolic biomarkers will also be crucial for patient stratification and treatment monitoring. Insights into metabolic reprogramming in GI cancers may have broader implications across multiple cancer types, offering new avenues for improving cancer treatment.

Effects of metabolism upon immunity: Targeting myeloid-derived suppressor cells for the treatment of breast cancer is a promising area of study

Breast cancer (BC) ranks among the most prevalent malignancies affecting women, with advanced-stage patients facing an increased mortality risk. Myeloid-derived suppressor cells (MDSCs) contribute significantly to poor prognostic outcomes. Research has concentrated predominantly on the immunological mechanisms underlying MDSC functions, but a comprehensive investigation into the metabolic interactions between BC cells and MDSCs is lacking. In a hypoxic tumor microenvironment (TME), BC cells can enhance aerobic-glycolysis rates, upregulate expression of key lipid metabolism enzymes such as cluster of differentiation (CD) 36 and 5-lipoxygenase (5-LOX), accelerate glutamine (Gln) uptake, and elevate extracellular adenosine (eADO) levels, thereby fostering MDSC proliferation and amplifying immune suppression. Concurrently, alterations in the metabolic state of MDSCs also influence BC progression. To ensure adequate proliferative resources, MDSCs upregulate the pentose phosphate pathway and expedite glycolysis for energy supply while increasing the expression of fatty acid transport proteins (FATPs) such as CD36 and fatty acid transporter 2 (FATP2) to maintain intracellular lipid availability, thereby enhancing their adaptability within the TME. Furthermore, MDSCs undermine T-cell anti-tumor efficacy by depleting essential amino acids (AAs), such as arginine (Arg), tryptophan (Trp), and cysteine (Cys), required for T-cell function. This review elucidates how pharmacological agents such as metformin, liver X receptor (LXR) agonists, and 6-diazo-5-oxo-L-norleucine (DON) can augment anti-cancer treatment efficacy by targeting metabolic pathways in MDSCs. We systematically delineate the mechanisms governing interactions between BC cells and MDSCs from a metabolic standpoint while summarizing therapeutic strategies to modulate metabolism within MDSCs. Our review provides a framework for optimizing MDSC applications in BC immunotherapy.

Orchestrating cancer therapy: Recent advances in nanoplatforms harmonize immunotherapy with multifaceted treatments

Advancements in cancer therapy have increasingly focused on leveraging the synergistic effects of combining immunotherapy with other treatment modalities, facilitated by the use of innovative nanoplatforms. These strategies aim to augment the efficacy of standalone treatments while addressing their inherent limitations. Nanoplatforms enable precise delivery and controlled release of therapeutic agents, which enhances treatment specificity and reduces systemic toxicity. This review highlights the critical role of nanomaterials in enhancing immunotherapy when combined with chemotherapy, radiotherapy, photodynamic therapy, photothermal therapy, and sonodynamic therapy. Additionally, it addresses current challenges, including limited in vivo studies, difficulties in standardizing and scaling production, complexities of combination therapies, lack of comparative analyses, and the need for personalized treatments. Future directions involve refining nanoplatform engineering for improved targeting and minimizing adverse effects, alongside large animal studies to establish the long-term efficacy and safety of these combined therapeutic strategies. These efforts aim to translate laboratory successes into clinically viable treatments, significantly improving therapeutic outcomes and advancing the field of oncology.

The Recruitment and Immune Suppression Mechanisms of Myeloid-Derived Suppressor Cells and Their Impact on Bone Metastatic Cancer

BACKGROUND

MDSCs are immature neutrophils and monocytes with immunosuppressive potentials, involving mononuclear MDSCs (M-MDSCs) and polymorphonuclear MDSCs (PMN-MDSCs).

RECENT FINDINGS

They are significant components of the tumor microenvironment (TME). Besides, recent studies also verified that MDSCs also facilitated the progression of bone metastasis by regulating the network of cytokines and the function of immune cells.

CONCLUSION

It is necessary to summarize the mechanisms of MDSC recruitment and immunosuppression, and their impact on bone metastasis.

Myeloid-Derived Suppressor Cell Accumulation Drives Intestinal Fibrosis through mCCL6/hCCL15 Chemokine-Mediated Fibroblast Activation

Intestinal fibrosis, a severe complication of Crohn's disease (CD), is linked to chronic inflammation, but the precise mechanism by which immune-driven intestinal inflammation leads to fibrosis development is not fully understood. This study investigates the role of myeloid-derived suppressor cells (MDSCs) in intestinal fibrosis in CD patients and a 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced mouse model. Elevated MDSCs are observed in inflamed intestinal tissues prior to fibrosis and their sustained presence in fibrotic tissues of both CD patients and murine models. Depletion of MDSCs significantly reduces fibrosis, highlighting their key role in the fibrotic process. Mechanistically, MDSC-derived mCCL6 activates fibroblasts via the CCR1-MAPK signaling, and interventions targeting this axis, including neutralizing antibodies, a CCR1 antagonist, or fibroblast-specific Ccr1 knockout mice reduce fibrosis. In CD patients with stenosis, human CCL15, analogous to mCCL6, is found to be elevated in MDSCs and activated fibroblasts. Additionally, CXCR2 and CCR2 ligands are identified as key mediators of MDSC recruitment in intestinal fibrosis. Blocking MDSC recruitment with CXCR2 and CCR2 antagonists alleviates intestinal fibrosis. These findings suggest that strategies targeting MDSC recruitment and mCCL6/hCCL15 signaling could offer therapeutic benefits for intestinal fibrosis.

Spatial‒temporal heterogeneities of liver cancer and the discovery of the invasive zone

Solid tumours are intricate and highly heterogeneous ecosystems, which grow in and invade normal organs. Their progression is mediated by cancer cells' interaction with different cell types, such as immune cells, stromal cells and endothelial cells, and with the extracellular matrix. Owing to its high incidence, aggressive growth and resistance to local and systemic treatments, liver cancer has particularly high mortality rates worldwide. In recent decades, spatial heterogeneity has garnered significant attention as an unfavourable biological characteristic of the tumour microenvironment, prompting extensive research into its role in liver tumour development. Advances in spatial omics have facilitated the detailed spatial analysis of cell types, states and cell‒cell interactions, allowing a thorough understanding of the spatial and temporal heterogeneities of tumour microenvironment and informing the development of novel therapeutic approaches. This review illustrates the latest discovery of the invasive zone, and systematically introduced specific macroscopic spatial heterogeneities, pathological spatial heterogeneities and tumour microenvironment heterogeneities of liver cancer.

HDAC1-3 inhibition triggers NEDD4-mediated CCR2 downregulation and attenuates immunosuppression in myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) play a critical role in cancer progression and resistance, thus representing promising targets for immunotherapy. Despite the established role of histone deacetylases (HDACs) in epigenetic regulation of cell fate and function, their specific impact on MDSCs remains elusive. We sought to investigate the effects and underlying mechanisms of HDAC on MDSCs using various HDAC inhibitors. Our results indicate that HDAC1-3 inhibitors reduce CCR2 expression, a chemokine receptor that mediates the migration of monocytic (M-)MDSCs to tumors and attenuated the immunosuppressive activity of MDSCs. In an orthotropic hepatocellular carcinoma (HCC) murine model, HDAC1-3 inhibitors reduced the infiltration of M-MDSCs, increased the number of natural killer cells in tumors, and suppressed tumor growth. Our results also suggest that HDAC1-3 inhibitors potentiate the antitumor effects of anti-programmed cell death protein 1 antibodies. ATAC-seq and RNA-seq analyses revealed 115 genes epigenetically upregulated by HDAC1-3 inhibitors, primarily linked to transcriptional regulation and ubiquitination. We further elucidated that HDAC1-3 inhibitors facilitate CCR2 protein degradation through ubiquitination-mediated by NEDD4 E3 ligase. Our findings reveal a novel mechanism of action of HDAC1-3 inhibitors in MDSCs and suggest a potential synergistic immunotherapy strategy for clinical benefit in HCC.

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.

Combating tumor PARP inhibitor resistance: Combination treatments, nanotechnology, and other potential strategies

PARP (poly (ADP-ribose) polymerase) inhibitors (PARPi) have demonstrated significant potential in cancer treatment, particularly in tumors with breast cancer susceptibility gene (BRCA) mutations and other DNA repair deficiencies. However, the development of resistance to PARPi has become a major challenge in their clinical application. The emergence of drug resistance leads to reduced efficacy of the PARPi over time, impacting long-term treatment outcomes and survival rates. PARPi resistance in tumors often arises as cells activate alternative DNA repair pathways or evade the effect of PARPi, diminishing therapeutic effectiveness. Consequently, overcoming resistance is crucial for maintaining treatment efficacy and improving patient prognosis. This paper reviews the strategies to overcome PARPi resistance through combination treatment and nanotechnology therapy. We first review the current combination therapies with PARPi, including anti-angiogenic therapies, radiotherapies, immunotherapies, and chemotherapies, and elucidate their mechanisms for overcoming PARPi resistance. Additionally, this paper focuses on the application of nanotechnology in improving the effectiveness of PARPi and overcoming drug resistance. Subsequently, this paper presents several promising strategies to tackle PARPi resistance, including but not limited to: structural modifications of PARPi, deployment of gene editing systems, implementation of "membrane lipid therapy," and modulation of cellular metabolism in tumors. By integrating these strategies, this research will provide comprehensive approaches to overcome the resistance of PARPi in cancer treatment and offer guidance for future research and clinical practice.

Polyphenol-mediated assembly of toll-like receptor 7/8 agonist nanoparticles for effective tumor immunotherapy

Toll-like receptor (TLR) 7/8 agonists have shown significant potential in tumor immunotherapy. However, the limited pharmacokinetic properties and systemic toxicity resulting from off-target effects limits their biomedical applications. We here report the polyphenol-mediated assembly of resiquimod (R848, a TLR7/8 agonist) nanoparticles (RTP NPs) to achieve tumor-selective immunotherapy while avoiding systemic adverse effects. Upon intravenous administration, the prepared RTP NPs are effectively accumulated at tumor sites, which increase their bioavailability and reduce systemic inflammation. RTP NPs can trigger a potent antitumor immune response in a mouse tumor model to inhibit tumor growth. Additionally, after subcutaneous injection at the tail base, RTP NPs efficiently migrate to the lymph nodes, where they elicit immune memory to prevent tumorigenesis. This study underscores the potential application of polyphenol-mediated assembly in developing nanomedicines with reduced toxicity for tumor-specific immunotherapy. STATEMENT OF SIGNIFICANCE: Toll-like receptor agonist (R848) nanoparticles for tumor-selective immunotherapy were synthesized through polyphenol-mediated assembly, a method that simplifies preparation process and minimizes potential side effects. Intravenously administered these nanoparticles effectively extended circulation time, enhanced tumor enrichment, and reduced systemic inflammation, thus augmenting the bioavailability and minimizing the side effects of R848. The nanoparticles significantly inhibited tumor growth by triggering a potent antitumor immune response, including dendritic cell maturation, macrophage polarization, T-cell infiltration, and cytokine secretion. Moreover, after subcutaneous injection at the tail base, they can elicit immune memory to prevent tumorigenesis.

Deciphering mechanical cues in the microenvironment: from non-malignant settings to tumor progression

The tumor microenvironment functions as a dynamic and intricate ecosystem, comprising a diverse array of cellular and non-cellular components that precisely orchestrate pivotal tumor behaviors, including invasion, metastasis, and drug resistance. While unraveling the intricate interplay between the tumor microenvironment and tumor behaviors represents a tremendous challenge, recent research illuminates a crucial biological phenomenon known as cellular mechanotransduction. Within the microenvironment, mechanical cues like tensile stress, shear stress, and stiffness play a pivotal role by activating mechanosensitive effectors such as PIEZO proteins, integrins, and Yes-associated protein. This activation initiates cascades of intrinsic signaling pathways, effectively linking the physical properties of tissues to their physiological and pathophysiological processes like morphogenesis, regeneration, and immunity. This mechanistic insight offers a novel perspective on how the mechanical cues within the tumor microenvironment impact tumor behaviors. While the intricacies of the mechanical tumor microenvironment are yet to be fully elucidated, it exhibits distinct physical attributes from non-malignant tissues, including elevated solid stresses, interstitial hypertension, augmented matrix stiffness, and enhanced viscoelasticity. These traits exert notable influences on tumor progression and treatment responses, enriching our comprehension of the multifaceted nature of the microenvironment. Through this innovative review, we aim to provide a new lens to decipher the mechanical attributes within the tumor microenvironment from non-malignant contexts, broadening our knowledge on how these factors promote or inhibit tumor behaviors, and thus offering valuable insights to identify potential targets for anti-tumor strategies.

Progress in immune microenvironment, immunotherapy and prognostic biomarkers in pediatric osteosarcoma

Pediatric osteosarcoma, the most prevalent primary malignant bone tumor in children, is marked by aggressive progression and a generally poor prognosis. Despite advances in treatment, including multi-agent chemotherapy, survival rates remain suboptimal, with metastasis, particularly to the lungs, contributing significantly to mortality. The tumor microenvironment plays a crucial role in osteosarcoma progression, with immune cells such as tumor-associated macrophages and T lymphocytes significantly influencing tumor behavior. The immunosuppressive environment, dominated by M2 macrophages, contributes to immune evasion and poor therapeutic outcomes, though recent findings suggest the potential for reprogramming these cells to enhance immune responses. This review provides a comprehensive overview of the immune landscape in pediatric osteosarcoma, with a focus on the role of immune cells and their interactions within the tumor microenvironment (TME). It examines the impact of immune checkpoints, genetic mutations, and inflammatory pathways on osteosarcoma progression, highlighting their contribution to tumor immune evasion and disease advancement. Additionally, emerging immunotherapeutic strategies, such as immune checkpoint inhibitors, macrophage reprogramming, and antibody-based therapies, are summarized in detail, showcasing their potential to improve therapeutic outcomes.

PMN-MDSCs are responsible for immune suppression in anti-PD-1 treated TAP1 defective melanoma

INTRODUCTION

The transporter associated with antigen processing (TAP) is a key component of the classical HLA I antigen presentation pathway. Our previous studies have demonstrated that the downregulation of TAP1 contributes to tumor progression and is associated with an increased presence of myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment. However, it remains unclear whether the elevation of MDSCs leads to immune cell exhaustion in tumors lacking TAP1. In this study, we established mouse models of tumors with TAP1 deficiency, and we employed PMN-MDSC depletion to investigate their impact on the immune microenvironment within the tumors. We found that MDSC depletion significantly altered the immune-suppressive effects of TAP1-deficient tumor when anti-PD-1 treatment was administered. Targeting PMN-MDSC may be a promising therapeutic strategy for the treatment of tumors with TAP1 deficiency during ICB treatment.

METHODS

Immunohistochemistry (IHC) was conducted to assess TAP1 expression in mouse melanoma tissues. Ly6G, F4/80, and NKp46 markers were detected in B16 parental and TAP1 knockout tissues, respectively. To enhance anti-tumor immunity, hyperthermia-treated B16F10 WT cell suspension was injected prior to tumor cell introduction. Subsequently, we established B16F10 TAP1 knockout and WT melanoma mouse models. Tumors were collected, and the immune microenvironment was monitored accordingly. Anti-Ly6G antibody was administered to deplete polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). Finally, flow cytometry analysis for immune infiltration, quantitative PCR for cytokine levels, and immunofluorescence assays were performed to analyze the immune response.

RESULTS

The level of Ly6G+ cell infiltration was significantly higher in samples exhibiting low TAP1 expression, while no differences were observed in the infiltration of F4/80+ cells or NKp46+ cells. Furthermore, the immune-suppressive effects associated with PMN-MDSCs were reversed following their elimination; this resulted in an increase in CD8+ T cells and a higher ratio of CD8+ T cells to Tregs, while the infiltration of innate immune cells remained unaffected. Functional markers of these immune cells indicated an active anti-tumoral immune response following the removal of PMN-MDSCs. Quantitative PCR analysis indicated elevated levels of TNF-α and IL-6, accompanied by decreased levels of TGF-β in the tumor microenvironment of TAP1.

CONCLUSIONS

Our data indicate that myeloid-derived suppressor cells (PMN-MDSCs) play an essential role in creating a tumorigenic immune microenvironment in TAP1 knockout tumors. Therefore, targeting PMN-MDSCs may become a promising therapeutic strategy for the treatment of tumors with TAP1 deficiency during ICB treatment.

Metabolic regulation of myeloid-derived suppressor cells in tumor immune microenvironment: targets and therapeutic strategies

Cancer remains a major challenge to global public health, with rising incidence and high mortality rates. The tumor microenvironment (TME) is a complex system of immune cells, fibroblasts, extracellular matrix (ECM), and blood vessels that form a space conducive to cancer cell proliferation. Myeloid-derived suppressor cells (MDSCs) are abundant in tumors, and they drive immunosuppression through metabolic reprogramming in the TME. This review describes how metabolic pathways such as glucose metabolism, lipid metabolism, amino acid metabolism, and adenosine metabolism have a significant impact on the function of MDSCs by regulating their immunosuppressive activity and promoting their survival and expansion in tumors. The review also explores key metabolic targets in MDSCs and strategies to modulate MDSC metabolism to improve the tumor immune microenvironment and enhance anti-tumor immune responses. Understanding these pathways can provide insight into potential therapeutic targets for modulating MDSC activity and improving outcomes of cancer immunotherapies.

Harnessing the tumor microenvironment: targeted cancer therapies through modulation of epithelial-mesenchymal transition

The tumor microenvironment (TME) is integral to cancer progression, impacting metastasis and treatment response. It consists of diverse cell types, extracellular matrix components, and signaling molecules that interact to promote tumor growth and therapeutic resistance. Elucidating the intricate interactions between cancer cells and the TME is crucial in understanding cancer progression and therapeutic challenges. A critical process induced by TME signaling is the epithelial-mesenchymal transition (EMT), wherein epithelial cells acquire mesenchymal traits, which enhance their motility and invasiveness and promote metastasis and cancer progression. By targeting various components of the TME, novel investigational strategies aim to disrupt the TME's contribution to the EMT, thereby improving treatment efficacy, addressing therapeutic resistance, and offering a nuanced approach to cancer therapy. This review scrutinizes the key players in the TME and the TME's contribution to the EMT, emphasizing avenues to therapeutically disrupt the interactions between the various TME components. Moreover, the article discusses the TME's implications for resistance mechanisms and highlights the current therapeutic strategies toward TME modulation along with potential caveats.

CAR-T cell therapy: developments, challenges and expanded applications from cancer to autoimmunity

Chimeric Antigen Receptor (CAR)-T cell therapy has rapidly emerged as a groundbreaking approach in cancer treatment, particularly for hematologic malignancies. However, the application of CAR-T cell therapy in solid tumors remains challenging. This review summarized the development of CAR-T technologies, emphasized the challenges and solutions in CAR-T cell therapy for solid tumors. Also, key innovations were discussed including specialized CAR-T, combination therapies and the novel use of CAR-Treg, CAR-NK and CAR-M cells. Besides, CAR-based cell therapy have extended its reach beyond oncology to autoimmune disorders. We reviewed preclinical experiments and clinical trials involving CAR-T, Car-Treg and CAAR-T cell therapies in various autoimmune diseases. By highlighting these cutting-edge developments, this review underscores the transformative potential of CAR technologies in clinical practice.

Myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment and their targeting in cancer therapy

The advent of immunotherapy represents a significant breakthrough in cancer treatment, with immune checkpoint inhibitors (ICIs) targeting PD-1 and CTLA-4 demonstrating remarkable therapeutic efficacy. However, patient responses to immunotherapy vary significantly, with immunosuppression within the tumor microenvironment (TME) being a critical factor influencing this variability. Immunosuppression plays a pivotal role in regulating cancer progression, metastasis, and reducing the success rates of immunotherapy. Myeloid-derived suppressor cells (MDSCs), due to their potent immunosuppressive capabilities, emerged as major negative regulators within the TME, facilitating tumor immune evasion by modulating various immune cells. In addition to their immunosuppressive functions, MDSCs also promote tumor growth and metastasis through non-immunological mechanisms, such as angiogenesis and the formation of pre-metastatic niches. Consequently, MDSCs in the TME are key regulators of cancer immune responses and potential therapeutic targets in cancer treatment. This review describes the origins and phenotypes of MDSCs, their biological roles in tumor progression, and regulatory mechanisms, with a focus on current therapeutic approaches targeting tumor-associated MDSCs. Furthermore, the synergistic effects of targeting MDSCs in combination with immunotherapy are explored, aiming to provide new insights and directions for cancer therapy.

Tumor microenvironment targeted nano-drug delivery systems for multidrug resistant tumor therapy

In recent years, nano-drug delivery systems (Nano-DDS) that target the tumor microenvironment (TME) to overcome multidrug resistance (MDR) have become a research hotspot in the field of cancer therapy. By precisely targeting the TME and regulating its unique pathological features, such as hypoxia, weakly acidic pH, and abnormally expressed proteins, etc., these Nano-DDS enable effective delivery of therapeutic agents and reversal of MDR. This scientific research community is increasing its investment in the development of diversified systems and exploring their anti-drug resistance potential. Therefore, it is particularly important to conduct a comprehensive review of the research progress of TME-targeted Nano-DDS in recent years. After a brief introduction of TME and tumor MDR, the design principle and structure of liposomes, polymer micelles and inorganic nanocarriers are focused on, and their characteristics as TME-targeted nanocarriers are described. It also demonstrates how these systems break through the cancer MDR treatment through various targeting mechanisms, discusses their synthetic innovation, research results and resistance overcoming mechanisms. The review was concluded with deliberations on the key challenges and future outlooks of targeting TME Nano-DDS in cancer therapy.

Platelet-activating factor: a potential therapeutic target to improve cancer immunotherapy

The tumor microenvironment (TME) fosters cancer progression by supporting the differentiation and proliferation of myeloid-derived suppressor cells (MDSCs), which play a critical role in suppressing immune responses and facilitating tumor growth. Recent findings by Dahal et al. reveal that platelet-activating factor (PAF), a lipid mediator elevated in the TME, contributes to the differentiation of neutrophils into immunosuppressive neutrophils. They showed that inhibiting PAF signaling reduces MDSC-mediated immunosuppression, thereby enhancing cytotoxic T-cell activity. This approach may improve cancer immunotherapy outcomes, particularly when combined with checkpoint blockade therapies, suggesting a promising avenue for therapeutic development.

20(S)-ginsenoside Rg3 alleviates DSS-induced colitis by promoting ERK-dependent maturation of MDSCs into M2 macrophages

Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells with immunosuppressive functions that play various roles in tumors and inflammatory diseases. In colitis, MDSCs accumulate in the inflamed colon, where they mature into M2-polarized macrophages and modulate inflammatory responses. Ginsenosides, active components of ginseng, have been shown to display colitis-alleviating effects in mouse models. However, the detailed mechanisms underlying these effects are incompletely understood. This study explores the impact of ginsenosides on MDSC functions and differentiation, focusing on their potential to mitigate inflammatory symptoms in colitis. Among the 15 ginsenosides tested, Rg3(R) and Rg3(S) were found to promote the maturation of MDSCs into M2 macrophages at non-cytotoxic concentrations. This was confirmed by the increased expression of ARG1, an immunosuppressive marker. These effects were attributed to the activation of the ERK pathway, as confirmed by selective ERK inhibition. In a DSS-induced colitis mouse model, oral administration of Rg3(S) alleviated disease severity and increased MDSC differentiation into M2 macrophages in colon lamina propria, highlighting its therapeutic potential colitis.

Stimulator of Interferon Genes Signal in Lung Cancer Regulates Differentiation of Myeloid-Derived Suppressor Cells in the Tumor Microenvironment Via the Interferon Regulatory Factor 3/NF-κB Pathway

Background: This study was designed to explore the action mechanism of stimulator of interferon genes (STING) on the differentiation of myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment of lung cancer. Methods: Bioinformatics analysis yielded a potential pathway for STING to regulate MDSC differentiation, the interferon regulatory factor 3 (IRF3)/NF-κB axis. The transfection efficiency of STING overexpression plasmid and small interfering RNA against IRF3 (siIRF3) was examined by quantitative real-time polymerase chain reaction (qRT-PCR). After transfection, A9 cells were co-cultured with extracted bone marrow cells (BMCs). MDSC differentiation, protein expression of the IRF3/NF-κB pathway, and changes in nuclear translocation of NF-κB were analyzed by flow cytometry, Western blot, and immunofluorescence staining experiments. A transplanted tumor mouse model was used for in vivo experiments. After cyclic diadenyl monophosphate (CDA; STING agonist) treatment, changes in MDSC differentiation and protein expression of the IRF3/NF-κB axis in transplanted tumors were verified by immunohistochemical staining, qRT-PCR, and Western blot. Results: Coculture of A9 cells and BMCs promoted MDSC differentiation, inhibited activation of IRF3/NF-κB signal in A9 cells, and boosted nuclear translocation of NF-κB. However, after the upregulation of STING, IRF3/NF-κB signal was activated, while MDSC differentiation and nuclear translocation of NF-κB were inhibited. SiIRF3 reversed the effects of STING overexpression. In vivo, CDA dampened MDSC differentiation and promoted protein expression of the IRF3/NF-κB axis. Conclusion: STING signal in lung cancer cells inhibits MDSC differentiation through activation of the IRF3/NF-κB pathway.

Role and value of the tumor microenvironment in the progression and treatment resistance of gastric cancer (Review)

Gastric cancer (GC) is characterized by a complex and heterogeneous tumor microenvironment (TME) that significantly influences disease progression and treatment outcomes. The tumor stroma, which is composed of a variety of cell types such as cancer‑associated fibroblasts, immune cells and vascular components, displays significant spatial and temporal diversity. These stromal elements engage in dynamic crosstalk with cancer cells, shaping their proliferative, invasive and metastatic potential. Furthermore, the TME is instrumental in facilitating resistance to traditional chemotherapy, specific treatments and immunotherapy strategies. Understanding the underlying mechanisms by which the GC microenvironment evolves and supports tumor growth and therapeutic resistance is critical for developing effective treatment strategies. The present review explores the latest progress in understanding the intricate interactions between cancer cells and their immediate environment in GC, highlighting the implications for disease pathogenesis and therapeutic interventions.

Cancer knocks you out by fasting: Cachexia as a consequence of metabolic alterations in cancer

Neoplastic transformation reprograms tumor and surrounding host cell metabolism, increasing nutrient consumption and depletion in the tumor microenvironment. Tumors uptake nutrients from neighboring normal tissues or the bloodstream to meet energy and anabolic demands. Tumor-induced chronic inflammation, a high-energy process, also consumes nutrients to sustain its dysfunctional activities. These tumor-related metabolic and physiological changes, including chronic inflammation, negatively impact systemic metabolism and physiology. Furthermore, the adverse effects of antitumor therapy and tumor obstruction impair the endocrine, neural, and gastrointestinal systems, thereby confounding the systemic status of patients. These alterations result in decreased appetite, impaired nutrient absorption, inflammation, and shift from anabolic to catabolic metabolism. Consequently, cancer patients often suffer from malnutrition, which worsens prognosis and increases susceptibility to secondary adverse events. This review explores how neoplastic transformation affects tumor and microenvironment metabolism and inflammation, leading to poor prognosis, and discusses potential strategies and clinical interventions to improve patient outcomes.

Knowledge mapping of immunotherapy for breast cancer: A bibliometric analysis from 2013 to 2022

Breast cancer is the leading cause of cancer-related death among women globally. Immunotherapy has emerged as a major milestone in contemporary oncology. This study aims to conduct a bibliometric analysis in the field of immunotherapy for breast cancer, providing a comprehensive overview of the current research status, identifying trends and hotspots in research topics. We searched and retrieved data from the Web of Science Core Collection, and performed a bibliometric analysis of publications on immunotherapy for breast cancer from 2013 to 2022. Current status and hotspots were evaluated by co-occurrence analysis using VOSviewer. Evolution and bursts of knowledge base were assessed by co-citation analysis using CiteSpace. Thematic evolution by bibliometrix package was used to discover keywords trends. The attribution and collaboration of countries/regions, institutions and authors were also explored. A total of 7,975 publications were included. In co-occurrence analysis of keywords, 6 major clusters were revealed: tumor microenvironment, prognosis biomarker, immune checkpoints, novel drug delivery methods, immune cells and therapeutic approaches. The top three most frequently mentioned keywords were tumor microenvironment, triple-negative breast cancer, and programmed cell death ligand 1. The most productive country, institution and author were the USA (2926 publications), the University of Texas MD Anderson Cancer Center (219 publications), and Sherene Loi (28 publications), respectively. There has been a rapid growth in studies on immunotherapy for breast cancer worldwide. This research area has gained increasing attention from different countries and institutions. With the rising incidence of breast cancer, immunotherapy represents a research field of significant clinical value and potential.

Mechanisms of immunotherapy resistance in small cell lung cancer

Small-cell lung cancer (SCLC) is an aggressive neuroendocrine tumor with a poor prognosis. Although the addition of immunotherapy to chemotherapy has modestly improved outcomes, most patients rapidly develop resistance. Resistance to immunotherapy can be broadly categorized into primary resistance and acquired resistance, as proposed by the Society for Immunotherapy of Cancer (SITC) consensus definition. Primary resistance occurs in the setting of failure to respond to immune checkpoint inhibitors (ICIs), while acquired resistance develops after initial response. The mechanisms of acquired and primary resistance to ICI are not well understood in SCLC, denoting an area of critical unmet need. Both intrinsic and extrinsic mechanisms play significant roles in immunotherapy resistance. Intrinsic mechanisms include defects in antigen presentation, mutations in key genes, reduced tumor immunogenicity, and epigenetic alterations. Extrinsic mechanisms involve the tumor microenvironment (TME), which is a complex interplay of both tumor- and immunosuppressive immune cells, vasculature, and microbiome. An understanding of these resistance mechanisms is crucial for developing novel therapeutic strategies to advance effective immunotherapy in patients with SCLC, a critical area of unmet need.

[Myeloid-derived suppressor cells as important factors and potential targets for breast cancer progression]

Recurrence and metastasis remain the leading cause of death in breast cancer patients due to the lack of effective treatment. A microenvironment suitable for cancer cell growth, referred to as pre-metastatic niche (PMN), is formed in distant organs before metastasis occurs. Myeloid-derived suppressor cells (MDSCs) are a heterogenous population of immature myeloid cells with immunosuppressive effects. They can expand in large numbers in breast cancer patients and participate in the formation of PMN. MDSCs can remodel the extracellular matrix of pulmonary vascular endothelial cells and recruit cancer stem cells to promote the lung metastasis of breast cancer. Furthermore, MDSCs facilitate immune evasion of breast cancer cells to impact the efficacy of immunotherapy. It is proposed that MDSCs represent a potential therapeutic target for the inhibition of recurrence and metastasis in breast cancer. Therapeutic strategies targeting MDSCs have shown promising efficacy in preclinical studies and clinical trials. This review presents a summary of the principal factors involved in the recruitment and activation of MDSCs during the formation of PMN, and outlines MDSCs functions such as immunosuppression and the current targeted therapies against MDSCs, aiming to provide new ideas for the treatment of distant metastases in breast cancer.

Neutrophil and Colorectal Cancer

Colorectal cancer (CRC) is often associated with metastasis and recurrence and is the leading cause of cancer-related mortality. In the progression of CRC, recent studies have highlighted the critical role of neutrophils, particularly tumor-associated neutrophils (TANs). TANs have both tumor-promoting and tumor-suppressing activities, contributing to metastasis, immunosuppression, angiogenesis, and epithelial-to-mesenchymal transition. Tumor-promoting TANs promote tumor growth by releasing proteases, reactive oxygen species, and cytokines, whereas tumor-suppressing TANs enhance immune responses by activating T cells and natural killer cells. Understanding the mechanisms underlying TAN mobilization, plasticity, and their role in the tumor microenvironment has revealed potential therapeutic targets. This review provides a comprehensive overview of TAN biology in CRC and discusses both the tumor-promoting and tumor-suppressing functions of neutrophils. Novel therapeutic approaches targeting TANs, such as chemokine receptor antagonists, aim to modulate neutrophil reprogramming and offer promising avenues for improving treatment outcomes of CRC.

SQLE-mediated squalene metabolism promotes tumor immune evasion in pancreatic cancer

Background

Squalene epoxidase (SQLE) is a key enzyme in cholesterol biosynthesis and has been shown to negatively affect tumor immunity and is associated with poor outcomes of immunotherapy in various cancers. While most research in this area has focused on the impact of cholesterol on immune functions, the influence of SQLE-mediated squalene metabolism within the tumor immune microenvironment (TIME) remains unexplored.

Methods

We established an immune-competent mouse model (C57BL/6) bearing mouse pancreatic cancer xenografts (KPC cells) with or without stable SQLE-knockdown (SQLE-KD) to evaluate the impact of SQLE-mediated metabolism on pancreatic cancer growth and immune functions. The effect of squalene on tumor growth and immune cells was tested by direct administration of squalene to C57BL/6 mice bearing KPC tumors. Flow cytometry analysis and immunohistochemical (IHC) staining of immune cells from the tumor tissues were performed to evaluate changes in immune function. We also employed RNA-sequencing to analyze the gene expression profiles in pancreatic cancer cells (PANC-1) treated with or without squalene. RT-PCR and Western blot analyses were used to investigate the relevant molecular mechanisms.

Results

We show that SQLE is significantly overexpressed in pancreatic cancer, and abrogation of SQLE results in a significant increase in squalene accumulation within tumor cells. The elevated squalene inhibits CXCL1 transcription through its impact on the NF-κB pathway via p65, and thus reduces the recruitment of myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs) into the tumor microenvironment. Silencing of SQLE also leads to an increased proportion of CD8+ T cells in the tumor tissues and suppresses tumor growth in vivo. Importantly, direct administration of squalene, the metabolic substrate of SQLE, to immune-competent mice bearing KPC pancreatic cancer tumors causes a substantial decrease in CD206+ TAMs and MDSCs, thus releasing immune suppression and inhibiting tumor growth.

Conclusion

Our study shows that squalene is an important immune-modulating metabolite that inhibits the infiltration of immune-suppressive cells in TIME, and that SQLE exerts its tumor immune evasion effect by metabolic removal of squalene. Thus, SQLE-mediated squalene metabolic pathway could be a potential target to enhance antitumor immunity in pancreatic cancer.

Association of immunosuppressive CD45+CD33+CD14- CD10-HLA-DR-/low neutrophils with poor prognosis in patients with lymphoma and their expansion and activation through STAT3/arginase-1 pathway in vitro

Objective

This study aimed to explore the clinical significance of CD45+CD33+CD14-CD10-HLA-DR-/low neutrophils (Cluster of Differentiation 10 [CD10-] neutrophils) in B-cell non-Hodgkin's lymphoma (B-NHL). An amplification system of CD10- neutrophils in vitro was constructed using cytokines, and the mechanisms underlying the cytokine-induced expansion and activation of the CD10- neutrophil subpopulation were investigated.

Material and Methods

We identified a novel suppressive cell population known as CD10- neutrophils in the peripheral blood of patients with B-NHL in different statuses by flow cytometry and found it to be correlated with interleukin-6 levels, T cell counts, and plasma arginase-1 (Arg-1) levels. We then verified the effect of CD10- neutrophil expression on the prognosis of patients with B-NHL. Furthermore, we described a clinically compatible method for generating granulocyte populations rich in CD10- neutrophils using cultures of peripheral blood-isolated neutrophils supplemented with cytokines in vitro. Arg-1 expression was detected in neutrophils before and after induction by cytokines through reverse-transcription polymerase chain reaction, enzyme-linked immunosorbent assay, and flow cytometry. T-cell proliferation and apoptosis were measured by carboxyfluorescein succinimidyl ester assay and Annexin V-Propidium Iodide stains, and induced cells were exposed to Arg-1 inhibitor and ruxolitinib. signal transducer and activator of transcription 3 (STAT3)/Arg-1 signaling was studied mainly by western blot and chromatin immunoprecipitation experiments.

Results

We established a correlation between high CD10- neutrophil levels and poorer survival outcomes in patients with B-NHL. Moreover, CD10- neutrophils were positively correlated with interleukin (IL)-6, T-reg cells, and plasma Arg-1 levels and negatively correlated with the absolute number of total T cells. Granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor, and IL-6 could all induce the expansion of CD10- neutrophil phenotype cells in vitro, which exhibit typical immature cellular morphology, and the combination of IL-6 and GM-CSF was the most effective. We confirmed that the STAT3/Arg-1 signaling pathway could be a critical mechanism regulating CD10- neutrophil-mediated immunosuppression in vitro.

Conclusion

CD10- neutrophils exhibited basic characteristics similar to conventional myeloid-derived suppressor cells. Our observations provide a promising STAT3 or Arg-1 targeting strategy for B-NHL and an important method for generating remarkably amounts of inhibitory granulocyte populations rich in CD10- neutrophils for immunotherapy.

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.

Colorectal cancer patients-derived immunity-organoid platform unveils cancer-specific tissue markers associated with immunotherapy resistance

Colorectal cancer (CRC) is a devastating disease, ranking as the second leading cause of cancer-related deaths worldwide. Immune checkpoint inhibitors (ICIs) have emerged as promising treatments; however, their efficacy is largely restricted to a subgroup of microsatellite instable (MSI) CRCs. In contrast, microsatellite stable (MSS) CRCs, which account for the majority of cases, exhibit variable and generally weaker response to ICIs, with only a subset demonstrating exceptional responsiveness. Identifying novel cancer-specific tissue (CST) markers predictive of immunotherapy response is crucial for refining patient selection and overcoming treatment resistance. In this study, we developed clinically relevant CRC organoids and autologous immune system interaction platforms to model ICI response. We conducted a comprehensive molecular characterization of both responder and non-responder models, identifying CST markers that predict ICI response. Validation of these findings was performed using an independent cohort of patient specimens through multiplex immunofluorescence. Furthermore, we demonstrated that knocking out a key gene from the identified predictive signature in resistant organoids restored immune sensitivity and induced T-cell-mediated apoptosis. Overall, our results provide novel insights into the mechanisms underlying immunotherapy resistance and suggest new markers for enhancing patient selection. These findings may pave the way for new therapeutic options in MSS patients, potentially broadening the cohort of individuals eligible for immunotherapy.

Impact of Structural Racism and Social Determinants of Health on Disparities in Breast Cancer Mortality

The striking ethnic and racial disparities in breast cancer mortality are not explained fully by pathologic or clinical features. Structural racism contributes to adverse conditions that promote cancer inequities, but the pathways by which this occurs are not fully understood. Social determinants of health, such as economic status and access to care, account for a portion of this variability, yet interventions designed to mitigate these barriers have not consistently led to improved outcomes. Based on the current evidence from multiple disciplines, we describe a conceptual model in which structural racism and racial discrimination contribute to increased mortality risk in diverse groups of patients by promoting adverse social determinants of health that elevate exposure to environmental hazards and stress; these exposures in turn contribute to epigenetic and immune dysregulation, thereby altering breast cancer outcomes. Based on this model, opportunities and challenges arise for interventions to reduce racial and ethnic disparities in breast cancer mortality.

Echinacoside inhibits tumor immune evasion by downregulating inducible PD-L1 and reshaping tumor immune landscape in breast and colorectal cancer

BACKGROUND

Targeting PD-L1 has become a crucial approach in tumor immunotherapy. Echinacoside (ECH) is a natural compound known for its extensive biological activities, its impact on antitumor immunity remains uncertain.

PURPOSE

This work was designed to assess the effects of ECH on the PD-L1/PD-1-mediated tumor immune evasion and its underlying mechanisms.

METHODS

Flow cytometry and RT-qPCR were utilized to explore the influence of ECH on PD-L1 expression. Western blot was employed to examine the mechanism by which ECH might modulate PD-L1 expression. Flow cytometry was conducted to evaluate the influence of ECH therapy, or the synergistic effects of ECH combined with immune checkpoint blockade (ICB) on tumor immune microenvironment (TIME) in tumor-burden mice. Blood biochemistry tests were used to evaluate the safety of ECH treatment.

RESULTS

ECH downregulated both the protein and mRNA expression levels of IFN-γ-induced PD-L1 through JAK/STAT1/IRF1 signaling pathway. ECH treatment upregulated the infiltration of IFN-γ+CD8+ T cells and Ki-67+CD8+ T cells, lowered the frequency of TIM-3+PD-1+ T cells, promoted the infiltration of effector CD4+ T cells and total CD8+ T cells while suppressed the percentage of regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSC). Moreover, the combination of ECH and anti-PD-1 or anti-CTLA-4 therapy exhibited synergistic anti-tumor effects, reshaping TIME. Blood biochemistry tests unveiled that ECH did not show additional toxicity.

CONCLUSION

ECH upregulates the expression of inducible PD-L1 through the JAK/STAT1/IRF1 signaling pathway, enhances T cell function, and reshapes the tumor immune landscape into an anti-tumor phenotype. Importantly, ECH markedly enhances the efficacy of ICB treatment, indicating its potential application in anti-tumor therapy.

CD36-mediated accumulation of MDSCs exerts abscopal immunosuppressive responses in hepatocellular carcinoma after insufficient microwave ablation

The immune landscape of distant unablated tumors following insufficient microwave ablation (iMWA) in hepatocellular carcinoma (HCC) remains to be clarified. The objective of this study is to define the abscopal immune landscape in distant unablated tumor before and after iMWA for HCC. Two treatment-naive patients were recruited for tumor tissue sampling, of each with two HCC lesions. Tumor samples were obtained at before and after microwave ablation in distant unablated sites for single-cell RNA sequencing (scRNA-seq). Mouse model with bilateral hepatoma tumors were developed, and distant unablated tumors were analyzed using multicolor immunofluorescence, RNA sequencing and flow cytometry. The scRNA-seq revealed that a reduced proportion of CD8+ T cells and an increased proportion of myeloid-derived suppressor cells (MDSCs) were observed in the distant unablated tumor microenvironment (TME). A notable disruption was observed in the lipid metabolism of tumor-associated immune cells, accompanied by an upregulated expression of CD36 in tumor-infiltrating immune cells in distant unablated tumor. The administration of a CD36 inhibitor has been demonstrated to ameliorate the adverse effects induced by iMWA, primarily by reinstating the anti-tumor responses of T cells in distant unablated tumor. These findings explain the recurrence and progression of tumors after iMWA and provide a new target of immunotherapy for HCC.

Depletion of monocytic myeloid-derived suppressor cells in LP-BM5 murine retroviral infection has a positive impact on virus-induced host immunodeficiency

We have shown the induction of CD11b+Ly6C+ monocytic myeloid-derived suppressor cells (M-MDSCs) during infection of B6 mice by LP-BM5 immunodeficiency-inducing retrovirus. We published that the molecular mechanisms of these M-MDSCs vary, and depend on the cell type targeted by the suppression -defined by use of biochemical inhibitors, mouse M-MDSCs knock-out strains and blocking antibodies. These M-MDSCs suppressed proliferation and function of T cells, via nitric oxide synthase/nitric oxide; and that of B cells, ∼50% via INOS/NO along with the negative checkpoint regulator VISTA, reactive nitrogen and oxygen species, and other soluble mediators. Here, LP-BM5 infected mice were treated weekly with 5-Fluorouracil (5-FU), resulting in depletion of peripheral blood and splenic M-MDSCs, reduced MDSC activity, and significantly decreased standard disease parameters of: splenomegaly, impaired B-and T-cell ex vivo polyclonal responses, and viral load. In addition, 5-FU treatment significantly increased percentages of CD4+ and CD8+ T cells.

The AXL-mediated modulation of myeloid-derived suppressor cells (MDSC) in nasopharyngeal carcinoma

AXL has ubiquitous expression in multiple cancers, and is strongly linked to both tumor progression, metastasis, and poor prognosis, as well as anti-tumor immune response suppression and induction of tumor resistance to immunotherapy. Therefore, it is a strong target for cancer intervention. Despite the wide application of AXL inhibitors in clinical trials, the role of AXL in the tumor immune microenvironment (TIME) remains undetermined. Herein, we established cell lines with stable AXL knockdown or overexpression using lentiviral infection. Subsequently, we co-cultured the cells with healthy human blood-derived CD33 + PBMCs. After two days of culture, we evaluated the differentiation of PBMCs into MDSCs. Additionally, the culture supernatants were collected from both the co-culture system and the individual cultures of each cell group to measure the concentrations of IL-6 and GM-CSF. Additionally, we subcutaneously administered nasopharyngeal carcinoma (NPC) cells into mice, and evaluated the association between AXL content and MDSC recruitment in the resulting tumors. We demonstrated that AXL is a critical modulator of MDSC differentiation and accumulation in NPC. It modulates IL-6, GM-CSF, and Toll-like receptor contents to achieve the aforementioned actions. Herein, we revealed a strong and direct link between AXL, cytokines in TIME, and MDSC differentiation and accumulation. Our work highlights novel approaches to optimizing existing immunotherapeutic interventions.

Rg3-lipo biomimetic delivery of paclitaxel enhances targeting of tumors and myeloid-derived suppressor cells

Liposomal drug delivery systems have revolutionized traditional cytotoxic drugs. However, the relative instability and toxicity of the existing liposomal drug delivery systems compromised their efficacy. Herein, we present Rg3-lipo, an innovative drug delivery system using a glycosyl moiety-enriched ginsenoside (Rg3). This system is distinguished by its glycosyl moieties exposed on the liposomal surface. These moieties imitate human cell membranes to stabilize and evade phagocytic clearance. The Rg3-lipo system loaded with paclitaxel (PTX-Rg3-lipo) demonstrated favorable bioavailability and safety in Sprague-Dawley rats, beagle dogs, and cynomolgus monkeys. With its glycosyl moieties recognizing tumor cells via the glucose transporter Glut1, PTX-Rg3-lipo inhibited gastric, breast, and esophageal cancers in human cancer cell lines, tumor-bearing mice, and patient-derived xenograft models. These glycosyl moieties selectively targeted myeloid-derived suppressor cells (MDSCs) through the glucose transporter Glut3 to attenuate their immunosuppressive effect. The mechanism study revealed that Rg3-lipo suppressed glycolysis and downregulated the transcription factors c-Maf and Mafb overcoming the MDSC-mediated immunosuppressive microenvironment and enhancing PTX-Rg3-lipo's antitumor effect. Taken together, we supply substantial evidence for its advantageous bioavailability and safety in multiple animal models, including nonhuman primates, and Rg3-lipo's dual targeting of cancer cells and MDSCs. Further investigation regarding Rg3-lipo's druggability will be conducted in clinical trials.

Causal relationship between cancer and immune cell traits: A two-sample mendelian randomization study

Background

Observational studies provide evidence of correlations between cancer and the immune system. Previous research has established associations between immune traits and the propensity for developing certain cancers. However, a systematic exploration of these connections remains largely uncharted. Therefore, further investigation is needed to examine the causal association between cancer and immune cell traits using Mendelian randomization (MR) approach.

Methods

We identified genetic instruments for breast cancer (BC), lung cancer (LC), endometrial cancer (EC), ovarian cancer (OC), prostate cancer (PC), and their subtype cancers to investigate their potential causal impact on immune traits. Data on cancer and immune cell traits were obtained from the IEU Open GWAS project. To assess whether these five cancer types and subtype cancers have a causal association with immune cell traits, we conducted two-sample MR analyses. Additionally, we conducted bidirectional MR analyses to examine the direction of causal relationships and adjusted for potentially related pleiotropy through multivariable MR analysis.

Results

We have identified several causal relationships between different types of cancer and immune traits. We found that breast cancer may influence 49 immune cell traits, endometrial cancer may influence 38, lung cancer may influence 25, ovarian cancer may influence 19, and prostate cancer may influence 28. Among these, breast cancer and lung cancer were associated with four common immune traits: CD25 on IgD- CD38dim, CD25 on sw mem, CD24 on IgD- CD38-, and CD25 on IgD- CD38-. Lung cancer and prostate cancer shared four immune traits: CD25 on IgD+ CD24+, CD25 on IgD+ CD38-, CD66b on CD66b++ myeloid cell, DN (CD4-CD8-) AC. Endometrial cancer and ovarian cancer shared two immune traits: TD DN (CD4-CD8-) %DN, EM DN (CD4-CD8-) %DN. Breast cancer and endometrial cancer shared one immune trait: CD20 on IgD- CD38dim. Endometrial cancer and prostate cancer shared one immune trait: CCR2 on myeloid DC. Lastly, breast cancer, lung cancer, and prostate cancer shared one immune trait: CD25 on CD24+ CD27+. Additionally, we identified specific immune traits that may serve as protective or risk factors for cancers. We found 14 immune traits may influence breast cancer, 9 immune traits may influence endometrial cancer, 22 immune traits may influence lung cancer, 9 immune traits may influence ovarian cancer, and 14 immune traits may influence prostate cancer. Among these, breast cancer and prostate cancer shared three immune traits: HLA DR++ monocyte %monocyte, HLA DR on plasmacytoid DC, and HLA DR on DC. Lung cancer and ovarian cancer shared one immune trait: CD62L- monocyte %monocyte. Prostate cancer and endometrial cancer shared one immune trait: HLA DR on CD33dim HLA DR + CD11b+. Lastly, ovarian cancer and prostate cancer shared one immune trait: CD3 on resting Treg.

Conclusions

Our MR study suggests a potential relationship between immune traits and cancers, particularly highlighting 14 immune traits that are simultaneously influenced by two or three of five cancer types, while also indicating that 6 immune traits may simultaneously contribute to the development of two of the cancers. This elucidation enables us to reveal a significant involvement of immune traits in cancer progression, providing critical insights into how immune traits affect cancer susceptibility.

Immune dynamics shaping pre-metastatic and metastatic niches in liver metastases: from molecular mechanisms to therapeutic strategies

Liver metastases are commonly detected in the advanced stages of various malignant tumors, representing a significant clinical challenge. Throughout the process of liver metastases formation, immune cells play a pivotal role, particularly in the pre-metastatic and metastatic niches within the liver. Immune cells establish extensive and intricate interactions with tumor cells and other components in the liver, collectively promoting and sustaining the growth of liver metastases. Despite the limited efficacy of existing therapeutic modalities against some advanced liver metastases, novel immune-based treatment approaches are continuously being explored and validated. Building on the systematic elucidation of the immunosuppressive characteristics of liver metastases, we explored the potential of novel immunotherapies applicable to patients with liver metastases from multiple dimensions.

Flow cytometry-based monitoring of myeloid-derived suppressor cells in the peripheral blood of patients with solid tumors

Myeloid-derived suppressor cells (MDSCs) ameliorate inflammation by inhibiting T cell responses. In pathological conditions, such as autoimmunity, chronic infections or cancer they accumulate in the periphery. In cancer, MDSCs can also be part of the tumor microenvironment and are associated with a worse prognosis and limited response to immunotherapy. Nowadays attempts are made to specifically target MDSCs in cancer therapy. Still, the role of MDSCs in standard cancer treatment modalities, such as radiotherapy remains mostly elusive. Here, we describe a flow cytometry-based method to determine and monitor monocytic and granulocytic-derived MDSCs directly from whole blood in an easy, fast and reliable assay. As specific surface markers for MDSCs are lacking, the assay follows a gating strategy that excludes successively the main immune cells types and analyzes the remaining events for a set of molecules that are expressed on MDSCs. This assay is especially appropriate for longitudinal analyses and clinical trials and is suitable for being integrated into more complex immunophenotyping panels to generate a comprehensive immune status.

Biomaterials' enhancement of immunotherapy for breast cancer by targeting functional cells in the tumor micro-environment

Immunotherapy for breast cancer is now being considered clinically, and more recently, the number of investigations aimed specifically at nano-biomaterials-assisted immunotherapy for breast cancer treatment is growing. Alterations of the breast cancer micro-environment can play a critical role in anti-tumor immunity and cancer development, progression and metastasis. The improvement and rearrangement of tumor micro-environment (TME) may enhance the permeability of anti-tumor drugs. Therefore, targeting the TME is also an ideal and promising option during the selection of effective nano-biomaterial-based immuno-therapeutic strategies excepted for targeting intrinsic resistant mechanisms of the breast tumor. Although nano-biomaterials designed to specifically release loaded anti-tumor drugs in response to tumor hypoxia and low pH conditions have shown promises and the diversity of the TME components also supports a broad targeting potential for anti-tumor drug designs, yet the applications of nano-biomaterials for targeting immunosuppressive cells/immune cells in the TME for improving the breast cancer treating outcomes, have scarcely been addressed in a scientific review. This review provides a thorough discussion for the application of the different forms of nano-biomaterials, as carrier vehicles for breast cancer immunotherapy, targeting specific types of immune cells in the breast tumor microenvironment. In parallel, the paper provides a critical analysis of current advances/challenges with leading nano-biomaterial-mediated breast cancer immunotherapeutic strategies. The current review is timely and important to the cancer research field and will provide a critical tool for nano-biomaterial design and research groups pushing the clinical translation of new nano-biomaterial-based immuno-strategies targeting breast cancer TME, to further open new avenues for the understanding, prevention, diagnosis and treatment of breast cancer, as well as other cancer types.

Phenylboronic acid-functionalized biomaterials for improved cancer immunotherapy via sialic acid targeting

Phenylboronic acid (PBA) is recognized as one of the most promising cancer cell binding modules attributed to its potential to form reversible and dynamic boronic ester covalent bonds. Exploring the advanced chemical versatility of PBA is crucial for developing new anticancer therapeutics. The presence of a specific Lewis acidic boron atom-based functional group and a Π-ring-connected ring has garnered increasing interest in the field of cancer immunotherapy. PBA-derivatized functional biomaterials can form reversible bonds with diols containing cell surface markers and proteins. This review primarily focuses on the following topics: (1) the importance and versatility of PBA, (2) different PBA derivatives with pKa values, (3) specific key features of PBA-mediated biomaterials, and (4) cell surface activity for cancer immunotherapy applications. Specific key features of PBA-mediated materials, including sensing, bioadhesion, and gelation, along with important synthesis strategies, are highlighted. The utilization of PBA-mediated biomaterials for cancer immunotherapy, especially the role of PBA-based nanoparticles and PBA-mediated cell-based therapeutics, is also discussed. Finally, a perspective on future research based on PBA-biomaterials for immunotherapy applications is presented.

Targeting acid ceramidase enhances antitumor immune response in colorectal cancer

INTRODUCTION

Acid ceramidase (hereafter referred as ASAH1) is an enzyme in sphingolipid metabolism that converts pro-survival ceramide into sphingosine. ASAH1 has been shown to be overexpressed in certain cancers. However, the role of ASAH1 in colorectal cancer still remain elusive.

OBJECTIVE

The present study is aimed to understand how ASAH1 regulates colorectal cancer (CRC) progression and resistance to checkpoint inhibitor therapy.

METHODS

Both pharmacological and genetic silencing of ASAH1 was used in the study. In vitro experiments were done on human and mouse CRC cell lines. The in vivo studies were conducted in NOD-SCID and BALB/c mice models. The combination of ASAH1 inhibitor and checkpoint inhibitor was tested using a syngeneic tumor model of CRC. Transcriptomic and metabolomic analyses were done to understand the effect of ASAH1 silencing.

RESULTS

ASAH1 is overexpressed in human CRC cases, and silencing the expression resulted in the induction of immunological cell death (ICD) and mitochondrial stress. The ASAH1 inhibitor (LCL-521), either as monotherapy or in combination with an anti-PD-1 antibody, resulted in reduction of tumors and, through induction of type I and II interferon response, activation of M1 macrophages and T cells, leading to enhanced infiltration of cytotoxic T cells. Our findings supported that the combination of LCL-521 and ICIs, which enhances the antitumor responses, and ASAH1 can be a druggable target in CRC.

Neutrophils promote the activation of monocytes via ROS to boost systemic antitumor immunity after cryo-thermal therapy

Background

The characteristics of the tumor immunosuppressive microenvironment represent a major challenge that limits the efficacy of immunotherapy. Our previous results suggested that cryo-thermal therapy, a tumor ablation system developed in our laboratory, promotes macrophage M1-type polarization and the complete maturation of DCs to remodel the immunosuppressive environment. However, the cells that respond promptly to CTT have not yet been identified. CTT can cause extensive cell death and the release of danger-associated molecular patterns and antigens. Neutrophils are the first white blood cells recruited to sites of damage and acute inflammation. Therefore, we hypothesized that neutrophils are the initial cells that respond to CTT and are involved in the subsequent establishment of antitumor immunity.

Methods

In this study, we examined the kinetics of neutrophil recruitment after CTT via flow cytometry and immunofluorescence staining and explored the effect of neutrophils on the establishment of systemic antitumor immunity by in vivo neutrophil depletion and in vitro co-culture assays.

Results

We found that CTT led to a rapid and strong proinflammatory neutrophil response, which was essential for the long-term survival of mice. CTT-induced neutrophils promoted the activation of monocytes via reactive oxygen species and further upregulated the expression of IFN-γ and cytotoxic molecules in T and NK cells. Adoptive neutrophil transfer further enhanced the antitumor efficacy of CTT in tumor models of spontaneous and experimental metastasis.

Conclusion

These results reveal the important role of neutrophil‒monocyte interactions in the development of anti-tumor immunity and highlight that CTT could be used as an immunotherapy for targeting neutrophils and monocytes to enhance antitumor immunity.

Molecular Mechanism for Malignant Progression of Gastric Cancer Within the Tumor Microenvironment

Gastric cancer (GC) is one of the most common cancers worldwide. Most patients are diagnosed at the progressive stage of GC, and progress in the development of effective anti-GC drugs has been insufficient. The tumor microenvironment (TME) regulates various functions of tumor cells, and interactions between the cellular and molecular components of the TME-e.g., inflammatory cells, fibroblasts, vasculature cells, and innate and adaptive immune cells-promote the aggressiveness of cancer cells and dissemination to distant organs. This review summarizes the roles of various TME cells and molecules in regulating the malignant progression and metastasis of GC. We also address the important roles of signaling pathways in mediating the interaction between cancer cells and the different components of the GC TME. Finally, we discuss the implications of these molecular mechanisms for developing novel and effective therapies targeting molecular and cellular components of the GC TME to control the malignant progression of GC.

The causal relationship between immune cell-mediated gut microbiota and ulcerative colitis: a bidirectional two-sample, mediation Mendelian randomization analysis

Background

Numerous studies have highlighted the close association between gut microbiota and the development of ulcerative colitis (UC), yet research on whether immune cells mediate this process remains scarce. This study utilizes various Mendelian randomization (MR) methods to investigate the causal relationship between gut microbiota and UC, further exploring the mediating role of immune cells in this process.

Methods

Genome-wide association study (GWAS) summary statistics for 473 gut microbiota, 731 immune cell phenotypes, and UC were obtained from the GWAS catalog database. Single nucleotide polymorphisms (SNP) were used as instrumental variables (IV) to validate the causal relationship between gut microbiota and UC through two-sample MR and Bayesian weighted MR (BWMR), and reverse MR was employed to explore the presence of reverse causal effects. Two-step MR was applied to identify immune cell mediators and evaluate their mediation effects.

Results

The study revealed a causal relationship between 20 gut microbiota and UC, with 14 microbiota acting as protective factors for UC and 6 as risk factors. Mediation MR identified 26 immune cell mediators, among which the association between CD11b on Mo MDSC and Bifidobacterium bifidum (B. bifidum) was most significant (p = 0.0017, OR = 1.4540, 95% CI: 1.1504-1.8378). Mediation MR analysis indicated that the mediation effect of CD11b on Mo MDSC between B. bifidum and UC was -0.0385, with a mediation effect ratio of 16.67%.

Conclusion

There is a clear causal relationship between certain gut microbiota and UC, and CD11b on Mo MDSC is a significant mediator between B. bifidum and UC, providing new insights for the clinical treatment of UC.

NF-κB signaling pathway in tumor microenvironment

The genesis and progression of tumors are multifaceted processes influenced by genetic mutations within the tumor cells and the dynamic interplay with their surrounding milieu, which incessantly impacts the course of cancer. The tumor microenvironment (TME) is a complex and dynamic entity that encompasses not only the tumor cells but also an array of non-cancerous cells, signaling molecules, and the extracellular matrix. This intricate network is crucial in tumor progression, metastasis, and response to treatments. The TME is populated by diverse cell types, including immune cells, fibroblasts, endothelial cells, alongside cytokines and growth factors, all of which play roles in either suppressing or fostering tumor growth. Grasping the nuances of the interactions within the TME is vital for the advancement of targeted cancer therapies. Consequently, a thorough understanding of the alterations of TME and the identification of upstream regulatory targets have emerged as a research priority. NF-κB transcription factors, central to inflammation and innate immunity, are increasingly recognized for their significant role in cancer onset and progression. This review emphasizes the crucial influence of the NF-κB signaling pathway within the TME, underscoring its roles in the development and advancement of cancer. By examining the interactions between NF-κB and various components of the TME, targeting the NF-κB pathway appears as a promising cancer treatment approach.

Stable triangle: nanomedicine-based synergistic application of phototherapy and immunotherapy for tumor treatment

In recent decades, cancer has posed a challenging obstacle that humans strive to overcome. While phototherapy and immunotherapy are two emerging therapies compared to traditional methods, they each have their advantages and limitations. These limitations include easy metastasis and recurrence, low response rates, and strong side effects. To address these issues, researchers have increasingly focused on combining these two therapies by utilizing a nano-drug delivery system due to its superior targeting effect and high drug loading rate, yielding remarkable results. The combination therapy demonstrates enhanced response efficiency and effectiveness, leading to a preparation that is highly targeted, responsive, and with low recurrence rates. This paper reviews several main mechanisms of anti-tumor effects observed in combination therapy based on the nano-drug delivery system over the last five years. Furthermore, the challenges and future prospects of this combination therapy are also discussed.

The multiple roles of interferon regulatory factor family in health and disease

Interferon Regulatory Factors (IRFs), a family of transcription factors, profoundly influence the immune system, impacting both physiological and pathological processes. This review explores the diverse functions of nine mammalian IRF members, each featuring conserved domains essential for interactions with other transcription factors and cofactors. These interactions allow IRFs to modulate a broad spectrum of physiological processes, encompassing host defense, immune response, and cell development. Conversely, their pivotal role in immune regulation implicates them in the pathophysiology of various diseases, such as infectious diseases, autoimmune disorders, metabolic diseases, and cancers. In this context, IRFs display a dichotomous nature, functioning as both tumor suppressors and promoters, contingent upon the specific disease milieu. Post-translational modifications of IRFs, including phosphorylation and ubiquitination, play a crucial role in modulating their function, stability, and activation. As prospective biomarkers and therapeutic targets, IRFs present promising opportunities for disease intervention. Further research is needed to elucidate the precise mechanisms governing IRF regulation, potentially pioneering innovative therapeutic strategies, particularly in cancer treatment, where the equilibrium of IRF activities is of paramount importance.