Angiopoietin-2 regulates gene expression in TIE2-expressing monocytes and augments their inherent proangiogenic functions

Evaluating the efficacy and safety of trebananib in treating ovarian cancer and non-ovarian cancer patients: a meta-analysis and systematic review

OBJECTIVES

Due to its anti-angiogenic properties, trebananib is frequently employed in the treatment of cancer patients, particularly those with ovarian cancer. We conducted a meta-analysis to assess the efficacy and safety profile of trebananib in combination with other drugs for treating both ovarian and non-ovarian cancer patients.

METHODS

Our search encompassed PubMed, Medline, Cochrane, and Embase databases, with a focus on evaluating study quality. Data extraction was conducted from randomized controlled trials (RCTs), and RevMan 5.3 facilitated result analysis.

RESULTS

Combining trebananib with other drugs extended progression-free survival (PFS) [HR 0.81, (95%CI: 0.65, 0.99), p = 0.04] and overall survival (OS) [HR 0.88, (95%CI: 0.79, 1.00), p = 0.04] in ovarian cancer patients. Ovarian cancer patients exhibited a higher objective response rate (ORR) with trebananib compared to non-ovarian cancer cohorts. Moreover, the incorporation of trebananib into the standard treatment regimen for malignant tumors did not significantly elevate drug-related adverse events [RR 1.05, (95% CI: 1.00, 1.11), p = 0.05].

CONCLUSION

Trebananib plus other drugs can improve the PFS, OS and ORR in patients with cancer, especially ovarian cancer. Our recommendation is to use trebananib plus other drugs to treat advanced cancer, and to continuously monitor and manage drug-related adverse events.

REGISTRATION

PROSPERO (No. CRD42023466988).

Navigating tumor angiogenesis: therapeutic perspectives and myeloid cell regulation mechanism

Sustained angiogenesis stands as a hallmark of cancer. The intricate vascular tumor microenvironment fuels cancer progression and metastasis, fosters therapy resistance, and facilitates immune evasion. Therapeutic strategies targeting tumor vasculature have emerged as transformative for cancer treatment, encompassing anti-angiogenesis, vessel normalization, and endothelial reprogramming. Growing evidence suggests the dynamic regulation of tumor angiogenesis by infiltrating myeloid cells, such as macrophages, myeloid-derived suppressor cells (MDSCs), and neutrophils. Understanding these regulatory mechanisms is pivotal in paving the way for successful vasculature-targeted cancer treatments. Therapeutic interventions aimed to disrupt myeloid cell-mediated tumor angiogenesis may reshape tumor microenvironment and overcome tumor resistance to radio/chemotherapy and immunotherapy.

Non-Coding RNA in Tumor Cells and Tumor-Associated Myeloid Cells-Function and Therapeutic Potential

The RNA world is wide, and besides mRNA, there is a variety of other RNA types, such as non-coding (nc)RNAs, which harbor various intracellular regulatory functions. This review focuses on small interfering (si)RNA and micro (mi)RNA, which form a complex network regulating mRNA translation and, consequently, gene expression. In fact, these RNAs are critically involved in the function and phenotype of all cells in the human body, including malignant cells. In cancer, the two main targets for therapy are dysregulated cancer cells and dysfunctional immune cells. To exploit the potential of mi- or siRNA therapeutics in cancer therapy, a profound understanding of the regulatory mechanisms of RNAs and following targeted intervention is needed to re-program cancer cells and immune cell functions in vivo. The first part focuses on the function of less well-known RNAs, including siRNA and miRNA, and presents RNA-based technologies. In the second part, the therapeutic potential of these technologies in treating cancer is discussed, with particular attention on manipulating tumor-associated immune cells, especially tumor-associated myeloid cells.

Targeting Macrophage Polarization for Reinstating Homeostasis following Tissue Damage

Tissue regeneration and remodeling involve many complex stages. Macrophages are critical in maintaining micro-environmental homeostasis by regulating inflammation and orchestrating wound healing. They display high plasticity in response to various stimuli, showing a spectrum of functional phenotypes that vary from M1 (pro-inflammatory) to M2 (anti-inflammatory) macrophages. While transient inflammation is an essential trigger for tissue healing following an injury, sustained inflammation (e.g., in foreign body response to implants, diabetes or inflammatory diseases) can hinder tissue healing and cause tissue damage. Modulating macrophage polarization has emerged as an effective strategy for enhancing immune-mediated tissue regeneration and promoting better integration of implantable materials in the host. This article provides an overview of macrophages' functional properties followed by discussing different strategies for modulating macrophage polarization. Advances in the use of synthetic and natural biomaterials to fabricate immune-modulatory materials are highlighted. This reveals that the development and clinical application of more effective immunomodulatory systems targeting macrophage polarization under pathological conditions will be driven by a detailed understanding of the factors that regulate macrophage polarization and biological function in order to optimize existing methods and generate novel strategies to control cell phenotype.

Targeting tumor-associated macrophages to reverse antitumor drug resistance

Currently, antitumor drugs show limited clinical outcomes, mainly due to adaptive resistance. Clinical evidence has highlighted the importance of the tumor microenvironment (TME) and tumor-associated macrophages (TAMs) in tumor response to conventional antitumor drugs. Preclinical studies show that TAMs following antitumor agent can be reprogrammed to an immunosuppressive phenotype and proangiogenic activities through different mechanisms, mediating drug resistance and poor prognosis. Potential extrinsic inhibitors targeting TAMs repolarize to an M1-like phenotype or downregulate proangiogenic function, enhancing therapeutic efficacy of anti-tumor therapy. Moreover, pharmacological modulation of macrophages that restore the immune stimulatory characteristics is useful to reshaping the tumor microenvironment, thus further limiting tumor growth. This review aims to introduce macrophage response in tumor therapy and provide a potential therapeutic combination strategy of TAM-targeting immunomodulation with conventional antitumor drugs.

Insights into lenvatinib resistance: mechanisms, potential biomarkers, and strategies to enhance sensitivity

Lenvatinib is a multitargeted tyrosine kinase inhibitor capable of promoting apoptosis, suppressing angiogenesis, inhibiting tumor cell proliferation, and modulating the immune response. In multiple cancer types, lenvatinib has presented manageable safety and is currently approved as an effective first-line therapy. However, with the gradual increase in lenvatinib application, the inevitable progression of resistance to lenvatinib is becoming more prevalent. A series of recent researches have reported the mechanisms underlying the development of lenvatinib resistance in tumor therapy, which are related to the regulation of cell death or proliferation, histological transformation, metabolism, transport processes, and epigenetics. In this review, we aim to outline recent discoveries achieved in terms of the mechanisms and potential predictive biomarkers of lenvatinib resistance as well as to summarize untapped approaches available for improving the therapeutic efficacy of lenvatinib in patients with various types of cancers.

Macrophage heterogeneity and its interactions with stromal cells in tumour microenvironment

Macrophages and tumour stroma cells account for the main cellular components in the tumour microenvironment (TME). Current advancements in single-cell analysis have revolutionized our understanding of macrophage diversity and macrophage-stroma interactions. Accordingly, this review describes new insight into tumour-associated macrophage (TAM) heterogeneity in terms of tumour type, phenotype, metabolism, and spatial distribution and presents the association between these factors and TAM functional states. Meanwhile, we focus on the immunomodulatory feature of TAMs and highlight the tumour-promoting effect of macrophage-tumour stroma interactions in the immunosuppressive TME. Finally, we summarize recent studies investigating macrophage-targeted therapy and discuss their therapeutic potential in improving immunotherapy by alleviating immunosuppression.

Identification and validation of methylation-CpG prognostic signature for prognosis of hepatocellular carcinoma

Epigenetic biomarkers help predict the prognosis of cancer patients and evaluating the clinical outcome of immunization therapy. In this study, we present a personalized gene methylation-CpG signature to enhance the accuracy of survival prediction for individuals with hepatocellular carcinoma (HCC). Utilizing RNA sequencing and methylation datasets from GEO as well as TCGA, we conducted single sample GSEA (ssGSEA), WGCNA, as well as Cox regression. Through these analyses, we identified 175 oxidative stress and immune-related genes along with 4 CpG loci that are associated with the prognosis of HCC. Subsequently, we constructed a prognostic signature for HCC utilizing these 4 CpG sites, referred to as the HCC Prognostic Signature of Methylation-CpG sites (HPSM). Further investigation revealed an enrichment of immune-related signal pathways in the HPSM-low group, which demonstrated a positive correlation with better survival among HCC patients. Moreover, the methylation of the CpG sites in HPSM was found to be closely linked to drug sensitivity. In vitro experiments tentatively confirmed that promoter methylation regulated the expression of BMPER, one of the CpG sites within HPSM. The expression of BMPER was significantly correlated with cell death in the oxidative stress pathway, and overexpression of BMPER effectively inhibited HCC cell proliferation. Consequently, our findings suggest that HPSM is an independent predictive factor and holds promise for accurately predicting the prognosis of HCC patients.

Research progress on mitochondria regulating tumor immunity

Tumor cells adapt their metabolism to meet the demands for energy and biosynthesis. Mitochondria, pivotal organelles in the metabolic reprogramming of tumor cells, contribute to tumorigenesis and cancer progression significantly through various dysfunctions in both tumor and immune cells. Alterations in mitochondrial dynamics and metabolic signaling pathways exert crucial regulatory influence on the activation, proliferation, and differentiation of immune cells. The tumor microenvironment orchestrates the activation and functionality of tumor-infiltrating immune cells by reprogramming mitochondrial metabolism and inducing shifts in mitochondrial dynamics, thereby facilitating the establishment of a tumor immunosuppressive microenvironment. Stress-induced leakage of mitochondrial DNA contributes multifaceted regulatory effects on anti-tumor immune responses and the immunosuppressive microenvironment by activating multiple natural immune signals, including cGAS-STING, TLR9, and NLRP3. Moreover, mitochondrial DNA-mediated immunogenic cell death emerges as a promising avenue for anti-tumor immunotherapy. Additionally, mitochondrial reactive oxygen species, a crucial factor in tumorigenesis, drives the formation of tumor immunosuppressive microenvironment by changing the composition of immune cells within the tumor microenvironment. This review focuses on the intrinsic relationship between mitochondrial biology and anti-tumor immune responses from multiple angles. We explore the core role of mitochondria in the dynamic interplay between the tumor and the host to facilitate the development of targeted mitochondrial strategies for anti-tumor immunotherapy.

HTATIP2 regulates arteriogenic activity in monocytes from patients with limb ischemia

Use of autologous cells isolated from elderly patients with multiple comorbidities may account for the modest efficacy of cell therapy in patients with chronic limb threatening ischemia (CLTI). We aimed to determine whether proarteriogenic monocyte/macrophages (Mo/MΦs) from patients with CLTI were functionally impaired and to demonstrate the mechanisms related to any impairment. Proarteriogenic Mo/MΦs isolated from patients with CLTI were found to have an impaired capacity to promote neovascularization in vitro and in vivo compared with those isolated from healthy controls. This was associated with increased expression of human HIV-1 TAT interactive protein-2 (HTATIP2), a transcription factor known to suppress angiogenesis/arteriogenesis. Silencing HTATIP2 restored the functional capacity of CLTI Mo/MΦs, which was associated with increased expression of arteriogenic regulators Neuropilin-1 and Angiopoietin-1, and their ability to enhance angiogenic (endothelial tubule formation) and arteriogenic (smooth muscle proliferation) processes in vitro. In support of the translational relevance of our findings, silencing HTATIP2 in proarteriogenic Mo/MΦs isolated from patients with CLTI rescued their capacity to enhance limb perfusion in the ischemic hindlimb by effecting greater angiogenesis and arteriogenesis. Ex vivo modulation of HTATIP2 may offer a strategy for rescuing the functional impairment of pro-angio/arteriogenic Mo/MΦs prior to autologous delivery and increase the likelihood of clinical efficacy.

Targeting the immune microenvironment for ovarian cancer therapy

Ovarian cancer (OC) is an aggressive malignancy characterized by a complex immunosuppressive tumor microenvironment (TME). Immune checkpoint inhibitors have emerged as a breakthrough in cancer therapy by reactivating the antitumor immune response suppressed by tumor cells. However, in the case of OC, these inhibitors have failed to demonstrate significant improvements in patient outcomes, and existing biomarkers have not yet identified promising subgroups. Consequently, there remains a pressing need to understand the interplay between OC tumor cells and their surrounding microenvironment to develop effective immunotherapeutic approaches. This review aims to provide an overview of the OC TME and explore its potential as a therapeutic strategy. Tumor-infiltrating lymphocytes (TILs) are major actors in OC TME. Evidence has been accumulating regarding the spontaneous TILS response against OC antigens. Activated T-helpers secrete a wide range of inflammatory cytokines with a supportive action on cytotoxic T-cells. Simultaneously, mature B-cells are recruited and play a significant antitumor role through opsonization of target antigens and T-cell recruitment. Macrophages also form an important subset of innate immunity (M1-macrophages) while participating in the immune-stimulation context. Finally, OC has shown to engage a significant natural-killer-cells immune response, exerting direct cytotoxicity without prior sensitization. Despite this initial cytotoxicity, OC cells develop various strategies to induce an immune-tolerant state. To this end, multiple immunosuppressive molecules are secreted to impair cytotoxic cells, recruit regulatory cells, alter antigen presentation, and effectively evade immune response. Consequently, OC TME is predominantly infiltrated by immunosuppressive cells such as FOXP3+ regulatory T-cells, M2-polarized macrophages and myeloid-derived suppressor cells. Despite this strong immunosuppressive state, PD-1/PD-L1 inhibitors have failed to improve outcomes. Beyond PD-1/PD-L1, OC expresses multiple other immune checkpoints that contribute to immune evasion, and each representing potential immune targets. Novel immunotherapies are attempting to overcome the immunosuppressive state and induce specific immune responses using antibodies adoptive cell therapy or vaccines. Overall, the OC TME presents both opportunities and obstacles. Immunotherapeutic approaches continue to show promise, and next-generation inhibitors offer exciting opportunities. However, tailoring therapies to individual immune characteristics will be critical for the success of these treatments.

Construction of monocyte-related prognosis model based on comprehensive analysis of bulk RNA-seq and single-cell RNA-seq in high-grade serous ovarian cancer

High-grade serous ovarian cancer (HGSOC) is a common subtype of ovarian cancer with high mortality. Finding a new biomarker is useful for the diagnosis and treatment of HGSOC. The scRNA and bulk RNA data were obtained from The Cancer Genome Atlas and Gene Expression Omnibus databases. The monocyte-related clusters were identified and annotated by Seruat and SingleR package. The Kaplan-Meier and receiver operating characteristic curve was used to determine the prognosis. The differentially expressed genes were determined by limma. The single sample Gene Set Enrichment Analysis, Gene Set Enrichment Analysis, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes were used for the enrichment function. The correlation between drug activity and gene expression was assessed by rcellminer and rcellminer Data package. We identified 9 cell types and obtained 37 differentially expressed marker genes of monocyte. A2M, CD163, and FPR1 were screened out as hub genes and used to construct risk model in HGSOC through univariate and multivariate cox analysis. Single sample Gene Set Enrichment Analysis showed risk score was related to B cell and T cell signal pathways, and further analysis showed most immune checkpoint genes expressions were upregulated in high-risk score group. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis exhibited that hub gene related genes were involved in signal receptor binding and cytokine-cytokine interaction. Low A2M expression and high expression of CD163 and FPR1 were associated with poor prognosis. Gene Set Enrichment Analysis revealed that A2M promoted tumor development through enhancing immune cell related signal pathways, while CD163 and FPR1 inhibited tumor development through activated carcinogenic signal pathways. Drug sensitivity analysis revealed that these hub genes could be potential therapeutic targets for the treatment of HGSOC. We constructed a risk model for the overall survival and explored the potential mechanism of monocyte in HGSOC.

Targeting vascular normalization: a promising strategy to improve immune-vascular crosstalk in cancer immunotherapy

Blood vessels are a key target for cancer therapy. Compared with the healthy vasculature, tumor blood vessels are extremely immature, highly permeable, and deficient in pericytes. The aberrantly vascularized tumor microenvironment is characterized by hypoxia, low pH, high interstitial pressure, and immunosuppression. The efficacy of chemotherapy, radiotherapy, and immunotherapy is affected by abnormal blood vessels. Some anti-angiogenic drugs show vascular normalization effects in addition to targeting angiogenesis. Reversing the abnormal state of blood vessels creates a normal microenvironment, essential for various cancer treatments, specifically immunotherapy. In addition, immune cells and molecules are involved in the regulation of angiogenesis. Therefore, combining vascular normalization with immunotherapy may increase the efficacy of immunotherapy and reduce the risk of adverse reactions. In this review, we discussed the structure, function, and formation of abnormal vessels. In addition, we elaborated on the role of the immunosuppressive microenvironment in the formation of abnormal vessels. Finally, we described the clinical challenges associated with the combination of immunotherapy with vascular normalization, and highlighted future research directions in this therapeutic area.

Role of chemokines in the crosstalk between tumor and tumor-associated macrophages

Tumor microenvironment (TME) consists of a dynamic network of non-tumoral stromal cells, including cancer-associated fibroblasts, endothelial cells, tumor-associated macrophages (TAMs), B and T cells. In the TME, TAMs support tumor initiation, progression, invasion and metastasis by promoting angiogenesis and immunosuppression of the tumor cells. There is close crosstalk between TAMs and tumor cells. Notably, chemokines are a significant messenger mediating the crosstalk between tumor cells and TAMs. TAMs can promote tumor progression via secretion of chemokines. Various chemokines secreted by tumors are involved in the generation and polarization of TAMs, the infiltration of TAMs in tumors, and the development of TAMs' suppressive function. This paper reviews CCL2-CCR2, CCL3/5-CCR5, CCL15-CCR1, CCL18-CCR8, CX3CL1/CCL26-CX3CR1, CXCL8-CXCR1/2, CXCL12-CXCR4/CXCR7 signaling pathways, their role in the recruitment, polarization and exertion of TAMs, and their correlation with tumor development, metastasis and prognosis. Furthermore, we present the current research progress on modulating the effects of TAMs with chemokine antagonists and discuss the prospects and potential challenges of using chemokine antagonists as therapeutic tools for cancer treatment. The TAMs targeting by chemokine receptor antagonists in combination with chemotherapy drugs, immune checkpoint inhibitors or radiotherapy appears to be a promising approach.

Monocyte-endothelial cell interactions in vascular and tissue remodeling

Monocytes are circulating leukocytes of innate immunity derived from the bone marrow that interact with endothelial cells under physiological or pathophysiological conditions to orchestrate inflammation, angiogenesis, or tissue remodeling. Monocytes are attracted by chemokines and specific receptors to precise areas in vessels or tissues and transdifferentiate into macrophages with tissue damage or infection. Adherent monocytes and infiltrated monocyte-derived macrophages locally release a myriad of cytokines, vasoactive agents, matrix metalloproteinases, and growth factors to induce vascular and tissue remodeling or for propagation of inflammatory responses. Infiltrated macrophages cooperate with tissue-resident macrophages during all the phases of tissue injury, repair, and regeneration. Substances released by infiltrated and resident macrophages serve not only to coordinate vessel and tissue growth but cellular interactions as well by attracting more circulating monocytes (e.g. MCP-1) and stimulating nearby endothelial cells (e.g. TNF-α) to expose monocyte adhesion molecules. Prolonged tissue accumulation and activation of infiltrated monocytes may result in alterations in extracellular matrix turnover, tissue functions, and vascular leakage. In this review, we highlight the link between interactions of infiltrating monocytes and endothelial cells to regulate vascular and tissue remodeling with a special focus on how these interactions contribute to pathophysiological conditions such as cardiovascular and chronic liver diseases.

Biomaterial-Assisted Macrophage Cell Therapy for Regenerative Medicine

Although most tissue types are capable of some form of self-repair and regeneration, injuries that are larger than a critical threshold or those occurring in the setting of certain diseases can lead to impaired healing and ultimately loss of structure and function. The immune system plays an important role in tissue repair and must be considered in the design of therapies in regenerative medicine. In particular, macrophage cell therapy has emerged as a promising strategy that leverages the reparative roles of these cells. Macrophages are critical for successful tissue repair and accomplish diverse functions throughout all phases of the process by dramatically shifting in phenotypes in response to microenvironmental cues. Depending on their response to various stimuli, they may release growth factors, support angiogenesis, and facilitate extracellular matrix remodeling. However, this ability to rapidly shift phenotype is also problematic for macrophage cell therapy strategies, because adoptively transferred macrophages fail to maintain therapeutic phenotypes following their administration to sites of injury or inflammation. Biomaterials are a potential way to control macrophage phenotype in situ while also enhancing their retention at sites of injury. Cell delivery systems incorporated with appropriately designed immunomodulatory signals have potential to achieve tissue regeneration in intractable injuries where traditional therapies have failed. Here we explorecurrent challenges in macrophage cell therapy, especially retention and phenotype control, how biomaterials may overcome them, and opportunities for next generation strategies. Biomaterials will be an essential tool to advance macrophage cell therapy for widespread clinical applications.

Angiopoietin-2-Dependent Spatial Vascular Destabilization Promotes T-cell Exclusion and Limits Immunotherapy in Melanoma

T-cell position in the tumor microenvironment determines the probability of target encounter and tumor killing. CD8+ T-cell exclusion from the tumor parenchyma is associated with poor response to immunotherapy, and yet the biology that underpins this distinct pattern remains unclear. Here we show that the vascular destabilizing factor angiopoietin-2 (ANGPT2) causes compromised vascular integrity in the tumor periphery, leading to impaired T-cell infiltration to the tumor core. The spatial regulation of ANGPT2 in whole tumor cross-sections was analyzed in conjunction with T-cell distribution, vascular integrity, and response to immunotherapy in syngeneic murine melanoma models. T-cell exclusion was associated with ANGPT2 upregulation and elevated vascular leakage at the periphery of human and murine melanomas. Both pharmacologic and genetic blockade of ANGPT2 promoted CD8+ T-cell infiltration into the tumor core, exerting antitumor effects. Importantly, the reversal of T-cell exclusion following ANGPT2 blockade not only enhanced response to anti-PD-1 immune checkpoint blockade therapy in immunogenic, therapy-responsive mouse melanomas, but it also rendered nonresponsive tumors susceptible to immunotherapy. Therapeutic response after ANGPT2 blockade, driven by improved CD8+ T-cell infiltration to the tumor core, coincided with spatial TIE2 signaling activation and increased vascular integrity at the tumor periphery where endothelial expression of adhesion molecules was reduced. These data highlight ANGPT2/TIE2 signaling as a key mediator of T-cell exclusion and a promising target to potentiate immune checkpoint blockade efficacy in melanoma.

SIGNIFICANCE

ANGPT2 limits the efficacy of immunotherapy by inducing vascular destabilization at the tumor periphery to promote T-cell exclusion.

Regulation of tumor angiogenesis by the crosstalk between innate immunity and endothelial cells

Endothelial cells and immune cells are major regulators of cancer progression and prognosis. Endothelial cell proliferation and angiogenesis are required for providing nutrients and oxygen to the nascent tumor and infiltration of immune cells to the tumor is dependent on endothelial cell activation. Myeloid cells and innate lymphocytes have an important role in shaping the tumor microenvironment by crosstalking with cancer cells and structural cells, including endothelial cells. Innate immune cells can modulate the activation and functions of tumor endothelial cells, and, in turn, endothelial cell expression of adhesion molecules can affect immune cell extravasation. However, the mechanisms underlying this bidirectional crosstalk are not fully understood. In this review, we will provide an overview of the current knowledge on the pathways regulating the crosstalk between innate immune cells and endothelial cells during tumor progression and discuss their potential contribution to the development of novel anti-tumor therapeutic approaches.

Characterization of circulating immune cells and correlation with Tie2/Angiopoietins level in well differentiated neuroendocrine gastroenteropancreatic tumors: a cross-sectional analysis

PURPOSE

The immune environment represents a new, but little explored, tool for understanding neuroendocrine neoplasms (NENs) behavior. An immunosuppressed microenvironment is hypothesized to promote NENs progression. A missing profiling of circulating leukocyte and peripheral blood mononuclear cells (PBMCs) subpopulations would open new perspectives in the still limited diagnostic-therapeutic management of NENs.

METHODS

A cross-sectional case-control pilot study was performed recruiting 30 consecutive subjects: 15 patients naïve to treatment, with histologically proven gastroenteropancreatic (GEP) neuroendocrine tumors (NETs) and 15 healthy controls, matched for age and sex. PBMCs subpopulations were studied by flow cytometry. Soluble Tie2 (sTie2), Angiopoietin-1 (Ang-1), Angiopoietin-2 (Ang-2) were evaluated by ELISA.

RESULTS

Immune cell profiling revealed a significant lower CD3^-CD56⁺ natural killer (NK) cell count in NETs vs controls (p = 0.04). NK subset analysis showed a reduced relative count of CD56⁺CD16⁺ NK cells (p =0.002) in NETs vs controls. Patients with NET showed a higher percentage of CD14⁺CD16⁺⁺ non-classical monocytes (p = 0.01), and a lower percentage of CD14⁺CD16⁺ intermediate monocytes (p = 0.04). A decrease in percentage (p = 0.004) of CD4⁺ T-helper lymphocytes was found in NET patients. Evaluation of cellular and serum angiopoietin pathway mediators revealed in NET patients a higher relative count of Tie2-expressing monocytes (TEMs) (p < 0.001), and high levels of Ang-1 (p = 0.003) and Ang-2 (p = 0.002).

CONCLUSIONS

Patients with GEP-NET presented an immunosuppressed environment characterized by a low count of cytotoxic NK cells, a high count of anti-inflammatory non-classical monocytes, and a low count of T-helper lymphocytes. Higher levels of TEMs and angiopoietins suggest a crosstalk between innate immunity and angiogenic pathways in NETs.

PP2Ac/STRN4 negatively regulates STING-type I IFN signaling in tumor-associated macrophages

Stimulator of IFN genes type I (STING-Type I) IFN signaling in myeloid cells plays a critical role in effective antitumor immune responses, but STING agonists as monotherapy have shown limited efficacy in clinical trials. The mechanisms that downregulate STING signaling are not fully understood. Here, we report that protein phosphatase 2A (PP2A), with its specific B regulatory subunit Striatin 4 (STRN4), negatively regulated STING-Type I IFN in macrophages. Mice with macrophage PP2A deficiency exhibited reduced tumor progression. The tumor microenvironment showed decreased immunosuppressive and increased IFN-activated macrophages and CD8+ T cells. Mechanistically, we demonstrated that Hippo kinase MST1/2 was required for STING activation. STING agonists induced dissociation of PP2A from MST1/2 in normal macrophages, but not in tumor conditioned macrophages. Furthermore, our data showed that STRN4 mediated PP2A binding to and dephosphorylation of Hippo kinase MST1/2, resulting in stabilization of YAP/TAZ to antagonize STING activation. In human patients with glioblastoma (GBM), YAP/TAZ was highly expressed in tumor-associated macrophages but not in nontumor macrophages. We also demonstrated that PP2A/STRN4 deficiency in macrophages reduced YAP/TAZ expression and sensitized tumor-conditioned macrophages to STING stimulation. In summary, we demonstrated that PP2A/STRN4-YAP/TAZ has, in our opinion, been an unappreciated mechanism that mediates immunosuppression in tumor-associated macrophages, and targeting the PP2A/STRN4-YAP/TAZ axis can sensitize tumors to immunotherapy.

Tumor-infiltrating regulatory T cells as targets of cancer immunotherapy

Regulatory T cells (Tregs) are abundant in tumor tissues, raising a question of whether immunosuppressive tumor-infiltrating Tregs (TI-Tregs) can be selectively depleted or functionally attenuated to evoke effective anti-tumor immune responses by conventional T cells (Tconvs), without perturbing Treg-dependent immune homeostasis in healthy organs and causing autoimmunity. Here, we review current cancer immunotherapy strategies, including immune checkpoint blockade (ICB) antibodies against CTLA-4 and PD-1 and discuss their effects on TI-Tregs. We also discuss approaches that exploit differentially regulated molecules on the cell surface (e.g., CTLA-4) and intracellularly (e.g., T cell receptor signaling molecules) between TI-Tregs and Tconvs as well as their dependence on cytokines (e.g., IL-2) and metabolites (e.g., lactate). We envisage that targeting TI-Tregs could be effective as a monotherapy and/or when combined with ICB antibodies.

Pharmacodynamic and Antitumor Activity of BI 836880, a Dual Vascular Endothelial Growth Factor and Angiopoietin 2 Inhibitor, Alone and Combined with Programmed Cell Death Protein-1 Inhibition

Vascular endothelial growth factor (VEGF) and angiopoietin (ANG)-2 have complementary roles in angiogenesis and promote an immunosuppressive tumor microenvironment. It is anticipated that the combination of VEGF and ANG2 blockade could provide superior activity to the blockade of either pathway alone and that the addition of VEGF/ANG2 inhibition to an anti-programmed cell death protein-1 (PD-1) antibody could change the tumor microenvironment to support T-cell-mediated tumor cytotoxicity. Here, we describe the pharmacologic and antitumor activity of BI 836880, a humanized bispecific nanobody comprising two single-variable domains blocking VEGF and ANG2, and an additional module for half-life extension in vivo. BI 836880 demonstrated high affinity and selectivity for human VEGF-A and ANG2, resulting in inhibition of the downstream signaling of VEGF/ANG2 and a decrease in endothelial cell proliferation and survival. In vivo, BI 836880 exhibited significant antitumor activity in all patient-derived xenograft models tested, showing significantly greater tumor growth inhibition (TGI) than bevacizumab (VEGF inhibition) and AMG386 (ANG1/2 inhibition) in a range of models. In a Lewis lung carcinoma syngeneic tumor model, the combination of PD-1 inhibition with VEGF inhibition showed superior efficacy versus the blockade of either pathway alone. TGI was further increased with the addition of ANG2 inhibition to VEGF/PD-1 blockade. VEGF/ANG2 inhibition had a strong antiangiogenic effect. Our data suggest that the blockade of VEGF and ANG2 with BI 836880 may offer improved antitumor activity versus the blockade of either pathway alone and that combining VEGF/ANG2 inhibition with PD-1 blockade can further enhance antitumor effects. SIGNIFICANCE STATEMENT: Vascular endothelial growth factor (VEGF) and angiopoietin (ANG)-2 play key roles in angiogenesis and have an immunosuppressive effect in the tumor microenvironment. This study shows that BI 836880, a bispecific nanobody targeting VEGF and ANG2, demonstrates substantial antitumor activity in preclinical models. Combining VEGF/ANG2 inhibition with the blockade of the PD-1 pathway can further improve antitumor activity.

Tumor Vasculature as an Emerging Pharmacological Target to Promote Anti-Tumor Immunity

Tumor vasculature abnormality creates a microenvironment that is not suitable for anti-tumor immune response and thereby induces resistance to immunotherapy. Remodeling of dysfunctional tumor blood vessels by anti-angiogenic approaches, known as vascular normalization, reshapes the tumor microenvironment toward an immune-favorable one and improves the effectiveness of immunotherapy. The tumor vasculature serves as a potential pharmacological target with the capacity of promoting an anti-tumor immune response. In this review, the molecular mechanisms involved in tumor vascular microenvironment-modulated immune reactions are summarized. In addition, the evidence of pre-clinical and clinical studies for the combined targeting of pro-angiogenic signaling and immune checkpoint molecules with therapeutic potential are highlighted. The heterogeneity of endothelial cells in tumors that regulate tissue-specific immune responses is also discussed. The crosstalk between tumor endothelial cells and immune cells in individual tissues is postulated to have a unique molecular signature and may be considered as a potential target for the development of new immunotherapeutic approaches.

The contradictory roles of macrophages in non-alcoholic fatty liver disease and primary liver cancer-Challenges and opportunities

Chronic liver diseases from varying etiologies generally lead to liver fibrosis and cirrhosis. Among them, non-alcoholic fatty liver disease (NAFLD) affects roughly one-quarter of the world population, thus representing a major and increasing public health burden. Chronic hepatocyte injury, inflammation (non-alcoholic steatohepatitis, NASH) and liver fibrosis are recognized soils for primary liver cancer, particularly hepatocellular carcinoma (HCC), being the third most common cause for cancer-related deaths worldwide. Despite recent advances in liver disease understanding, therapeutic options on pre-malignant and malignant stages remain limited. Thus, there is an urgent need to identify targetable liver disease-driving mechanisms for the development of novel therapeutics. Monocytes and macrophages comprise a central, yet versatile component of the inflammatory response, fueling chronic liver disease initiation and progression. Recent proteomic and transcriptomic studies performed at singular cell levels revealed a previously overlooked diversity of macrophage subpopulations and functions. Indeed, liver macrophages that encompass liver resident macrophages (also named Kupffer cells) and monocyte-derived macrophages, can acquire a variety of phenotypes depending on microenvironmental cues, and thus exert manifold and sometimes contradictory functions. Those functions range from modulating and exacerbating tissue inflammation to promoting and exaggerating tissue repair mechanisms (i.e., parenchymal regeneration, cancer cell proliferation, angiogenesis, fibrosis). Due to these central functions, liver macrophages represent an attractive target for the treatment of liver diseases. In this review, we discuss the multifaceted and contrary roles of macrophages in chronic liver diseases, with a particular focus on NAFLD/NASH and HCC. Moreover, we discuss potential therapeutic approaches targeting liver macrophages.

Mesenchymal stem cells elicits Anti-PD1 immunotherapy by targeted delivery of CX3CL1

Anti-PD1/PDL1 monotherapy has failed to acquire sufficiently ideal results in most solid tumors. Mesenchymal stem cells (MSCs) have been reported to exert therapeutic effects on some tumors, but the functions of MSCs in colorectal cancer (CRC) need further research. In this study, we aimed to investigate the therapeutic effect and the improvement of sensitivity of MSCs to anti-PD1 antibodies (αPD1) in CRC and to evaluate the possible mechanism. The relative distribution of immune cells in tumor microenvironment was examined after the mice were treated with MSC and/or αPD1. Our study revealed that MSC recruits CX3CR1^high macrophages and promotes M1 polarization to inhibit tumor growth via highly secretion of CX3CL1.The combination of MSC and αPD1 was superior to monotherapy against CRC. MSC inhibits PD1 expression on CD8⁺ T cells by facilitating M1 macrophage polarization, which promotes the proliferation of CD8⁺ T cells, thus improving the sensitivity to αPD1 therapy in CRC. Additionally, the above therapeutic effect disappeared after inhibiting the secretion of CX3CL1 in MSC. Our MSC-based immunotherapeutic strategy simultaneously recruited and activated immune effector cells at the tumor site, suggesting that the combination of MSC and αPD1 could be a potential therapy for CRC.

Effects of a Novel Beta Lactam Compound, MC-100093, on the Expression of Glutamate Transporters/Receptors and Ethanol Drinking Behavior of Alcohol-Preferring Rats

Chronic ethanol exposure affects the glutamatergic system in several brain reward regions including the nucleus accumbens (NAc). Our laboratory has shown that chronic exposure to ethanol reduced the expression of glutamate transporter 1 (GLT-1) and cystine/glutamate exchanger (xCT) and, as a result, increased extracellular glutamate concentrations in the NAc of alcohol-preferring (P) rats. Moreover, previous studies from our laboratory reported that chronic ethanol intake altered the expression of certain metabotropic glutamate receptors in the brain. In addition to central effects, chronic ethanol consumption induced liver injury, which is associated with steatohepatitis. In the present study, we investigated the effects of chronic ethanol consumption in the brain and liver. Male P rats had access to a free choice of ethanol and water bottles for five weeks. Chronic ethanol consumption reduced GLT-1 and xCT expression in the NAc shell but not in the NAc core. Furthermore, chronic ethanol consumption increased fat droplet content as well as peroxisome proliferator-activated receptor alpha (PPAR-α) and GLT-1 expression in the liver. Importantly, treatment with the novel beta-lactam compound, MC-100093, reduced ethanol drinking behavior and normalized the levels of GLT-1 and xCT expression in the NAc shell as well as normalized GLT-1 and PPAR-α expression in the liver. In addition, MC-100093 attenuated ethanol-induced increases in fat droplet content in the liver. These findings suggest that MC-100093 may be a potential lead compound to attenuate ethanol-induced dysfunction in the glutamatergic system and liver injury. SIGNIFICANCE STATEMENT: This study identified a novel beta-lactam, MC-100093, that has demonstrated upregulatory effects on GLT-1. MC-100093 reduced ethanol drinking behavior and normalized levels of GLT-1 and xCT expression in the NAc shell as well as normalized GLT-1 and PPAR-α expression in the liver. In addition, MC-100093 attenuated ethanol-induced increases in fat droplet content in the liver.

Clinical Significance of Tie-2-Expressing Monocytes/Macrophages and Angiopoietins in the Progression of Ovarian Cancer-State-of-the-Art

Tumour growth and metastasis are specific to advanced stages of epithelial ovarian cancer (EOC). Tumour angiogenesis is an essential part of these processes. It is responsible for providing tumours with nutrients, metabolites, and cytokines and facilitates tumour and immune cell relocation. Destabilised vasculature, a distinctive feature of tumours, is also responsible for compromising drug delivery into the bulk. Angiogenesis is a complex process that largely depends on how the tumour microenvironment (TME) is composed and how a specific organ is formed. There are contrary reports on whether Tie-2-expressing monocytes/macrophages (TEMs) reported as the proangiogenic population of monocytes have any impact on tumour development. The aim of this paper is to summarise knowledge about ovarian-cancer-specific angiogenesis and the unique role of Tie-2-expressing monocytes/macrophages in this process. The significance of this cell subpopulation for the pathophysiology of EOC remains to be investigated.

Reactive astrocytes transduce inflammation in a blood-brain barrier model through a TNF-STAT3 signaling axis and secretion of alpha 1-antichymotrypsin

Astrocytes are critical components of the neurovascular unit that support blood-brain barrier (BBB) function. Pathological transformation of astrocytes to reactive states can be protective or harmful to BBB function. Here, using a human induced pluripotent stem cell (iPSC)-derived BBB co-culture model, we show that tumor necrosis factor (TNF) transitions astrocytes to an inflammatory reactive state that causes BBB dysfunction through activation of STAT3 and increased expression of SERPINA3, which encodes alpha 1-antichymotrypsin (α1ACT). To contextualize these findings, we correlated astrocytic STAT3 activation to vascular inflammation in postmortem human tissue. Further, in murine brain organotypic cultures, astrocyte-specific silencing of Serpina3n reduced vascular inflammation after TNF challenge. Last, treatment with recombinant Serpina3n in both ex vivo explant cultures and in vivo was sufficient to induce BBB dysfunction-related molecular changes. Overall, our results define the TNF-STAT3-α1ACT signaling axis as a driver of an inflammatory reactive astrocyte signature that contributes to BBB dysfunction.

Therapy-induced shaping of the glioblastoma microenvironment: Macrophages at play

The intricate cross-talks between tumor cells and their microenvironment play a key role in cancer progression and resistance to treatment. In recent years, targeting pro-tumorigenic components of the tumor microenvironment (TME) has emerged as a tantalizing strategy to improve the efficacy of standard-of-care (SOC) treatments, particularly for hard-to-treat cancers such as glioblastoma. In this review, we explore how the distinct microenvironmental niches characteristic of the glioblastoma TME shape response to therapy. In particular, we delve into the interplay between tumor-associated macrophages (TAM) and glioblastoma cells within angiogenic and hypoxic niches, and interrogate their dynamic co-evolution upon SOC therapies that fuels malignancy. Resolving the complexity of therapy-induced alterations in the glioblastoma TME and their impact on disease relapse is a stepping stone to identify targetable pro-tumorigenic pathways and TAM subsets, and may open the way to efficient combination therapies that will improve clinical outcomes.

Major pathways involved in macrophage polarization in cancer

Macrophages play an important role in tissue homeostasis, tissue remodeling, immune response, and progression of cancer. Consequently, macrophages exhibit significant plasticity and change their transcriptional profile and function in response to environmental, tissue, and inflammatory stimuli resulting in pro- and anti-tumor effects. Furthermore, the categorization of tissue macrophages in inflammatory situations remains difficult; however, there is an agreement that macrophages are predominantly polarized into two different subtypes with pro- and anti-inflammatory properties, the so-called M1-like and M2-like macrophages, respectively. These two macrophage classes can be considered as the extreme borders of a continuum of many intermediate subsets. On one end, M1 are pro-inflammatory macrophages that initiate an immunological response, damage tissue integrity, and dampen tumor progression by fostering robust T and natural killer (NK) cell anti-tumoral responses. On the other end, M2 are anti-inflammatory macrophages involved in tissue remodeling and tumor growth, that promote cancer cell proliferation, invasion, tumor metastasis, angiogenesis and that participate to immune suppression. These decisive roles in tumor progression occur through the secretion of cytokines, chemokines, growth factors, and matrix metalloproteases, as well as by the expression of immune checkpoint receptors in the case of M2 macrophages. Moreover, macrophage plasticity is supported by stimuli from the Tumor Microenvironment (TME) that are relayed to the nucleus through membrane receptors and signaling pathways that result in gene expression reprogramming in macrophages, thus giving rise to different macrophage polarization outcomes. In this review, we will focus on the main signaling pathways involved in macrophage polarization that are activated upon ligand-receptor recognition and in the presence of other immunomodulatory molecules in cancer.

Origin, production and molecular determinants of macrophages for their therapeutic targeting

Macrophages, the most heterogeneous cells of the hematopoietic system and the giant eaters of the immune system that present either as tissue-resident cells or infiltrated immune cells, eliminate foreign pathogens and microbes and also play different physiological roles to maintain the body's immune response. In this review, we basically provide a broad overview of macrophages from their origin, functional diversity to M1-M2 polarization, specialized markers, and their role as important therapeutic targets in different diseases based on the current research and evidence. Apart from this, we have precisely discussed about tumor-associated macrophages (TAMs) and their role in tumor progression and newly discovered lesser-known markers of TAMs that could be used as potential therapeutic targets to treat life-threatening diseases. It is really very important to understand the diversity of macrophages to develop TAM-modulating strategies to activate our own immune system against diseases and to overcome immune resistance.

Mitochondrial oxidative stress in the tumor microenvironment and cancer immunoescape: foe or friend?

The major concept of "oxidative stress" is an excess elevated level of reactive oxygen species (ROS) which are generated from vigorous metabolism and consumption of oxygen. The precise harmonization of oxidative stresses between mitochondria and other organelles in the cell is absolutely vital to cell survival. Under oxidative stress, ROS produced from mitochondria and are the major mediator for tumorigenesis in different aspects, such as proliferation, migration/invasion, angiogenesis, inflammation, and immunoescape to allow cancer cells to adapt to the rigorous environment. Accordingly, the dynamic balance of oxidative stresses not only orchestrate complex cell signaling events in cancer cells but also affect other components in the tumor microenvironment (TME). Immune cells, such as M2 macrophages, dendritic cells, and T cells are the major components of the immunosuppressive TME from the ROS-induced inflammation. Based on this notion, numerous strategies to mitigate oxidative stresses in tumors have been tested for cancer prevention or therapies; however, these manipulations are devised from different sources and mechanisms without established effectiveness. Herein, we integrate current progress regarding the impact of mitochondrial ROS in the TME, not only in cancer cells but also in immune cells, and discuss the combination of emerging ROS-modulating strategies with immunotherapies to achieve antitumor effects.

Prognostic Role of Molecular and Imaging Biomarkers for Predicting Advanced Hepatocellular Carcinoma Treatment Efficacy

Simple Summary

Molecular biomarkers play a marginal role in clinical practice for hepatocellular carcinoma (HCC) diagnosis, surveillance and treatment monitoring. Radiological biomarker: alpha-fetoprotein is still a lone protagonist in this field. The potential role of molecular biomarkers in the assessment of prognosis and treatment results could reduce the health costs faced by standard radiology. The majority of efforts are oriented towards early HCC detection, but the field faces an important challenge to find adequate biomarkers for advanced HCC management.

Abstract

Hepatocellular carcinoma (HCC) is the sixth most common malignancy worldwide and the fourth cause of tumor-related death. Imaging biomarkers are based on computed tomography, magnetic resonance, and contrast-enhanced ultrasound, and are widely applied in HCC diagnosis and treatment monitoring. Unfortunately, in the field of molecular biomarkers, alpha-fetoprotein (AFP) is still the only recognized tool for HCC surveillance in both diagnostic and follow-up purposes. Other molecular biomarkers have little roles in clinical practice regarding HCC, mainly for the detection of early-stage HCC, monitoring the response to treatments and analyzing tumor prognosis. In the last decades no important improvements have been achieved in this field and imaging biomarkers maintain the primacy in HCC diagnosis and follow-up. Despite the still inconsistent role of molecular biomarkers in surveillance and early HCC detection, they could play an outstanding role in prognosis estimation and treatment monitoring with a potential reduction in health costs faced by standard radiology. An important challenge resides in identifying sufficiently sensitive and specific biomarkers for advanced HCC for prognostic evaluation and detection of tumor progression, overcoming imaging biomarker sensitivity. The aim of this review is to analyze the current molecular and imaging biomarkers in advanced HCC.

Inducing vascular normalization: A promising strategy for immunotherapy

In solid tumors, the vasculature is highly abnormal in structure and function, resulting in the formation of an immunosuppressive tumor microenvironment by limiting immune cells infiltration into tumors. Vascular normalization is receiving much attention as an alternative strategy to anti-angiogenic therapy, and its potential therapeutic targets include signaling pathways, angiogenesis-related genes, and metabolic pathways. Endothelial cells play an important role in the formation of blood vessel structure and function, and their metabolic processes drive blood vessel sprouting in parallel with the control of genetic signals in cancer. The feedback loop between vascular normalization and immunotherapy has been discussed extensively in many reviews. In this review, we summarize the impact of aberrant tumor vascular structure and function on drug delivery, metastasis, and anti-tumor immune responses. In addition, we present evidences for the mutual regulation of immune vasculature. Based on the importance of endothelial metabolism in controlling angiogenesis, we elucidate the crosstalk between endothelial cells and immune cells from the perspective of metabolic pathways and propose that targeting abnormal endothelial metabolism to achieve vascular normalization can be an alternative strategy for cancer treatment, which provides a new theoretical basis for future research on the combination of vascular normalization and immunotherapy.

The Role of TAMs in Tumor Microenvironment and New Research Progress

Tumor-associated macrophages (TAMs) are an important part of tumor microenvironment (TME) and play a key role in TME, participating in the process of tumor occurrence, growth, invasion, and metastasis. Among them, metastasis to tumor tissue is the key step of malignant development of tumor. In this paper, the latest progress in the role of TAMs in the formation of tumor microenvironment is summarized. It is particularly noteworthy that cell and animal experiments show that TAMs can provide a favorable microenvironment for the occurrence and development of tumors. At the same time, clinical pathological experiments show that the accumulation of TAMs in tumor is related to poor clinical efficacy. Finally, this paper discusses the feasibility of TAMs-targeted therapy as a new indirect cancer therapy. This paper provides a theoretical basis for finding a potentially effective macrophage-targeted tumor therapy.

Increased frequency of proangiogenic tunica intima endothelial kinase 2 (Tie2) expressing monocytes in individuals with type 2 diabetes mellitus

Background

Individuals with type 2 diabetes mellitus (T2DM) have an increased risk for developing macrovascular disease (MVD) manifested by atherosclerosis. Phenotypically and functionally different monocyte subsets (classical; CD14⁺⁺CD16⁻, non-classical; CD14⁺CD16⁺⁺, and intermediate; CD14⁺⁺CD16⁺) including pro-angiogenic monocytes expressing Tie2 (TEMs) can be identified. Here we investigated monocyte heterogeneity and its association with T2DM and MVD.

Methods

Individuals with (N = 51) and without (N = 56) T2DM were recruited and allocated to "non-MVD" or "with MVD" (i.e., peripheral or coronary artery disease) subgroups. Blood monocyte subsets were quantified based on CD14, CD16 and Tie2 expression levels. Plasma levels of Tie2-ligands angiopoietin-1 and angiopoietin-2 were determined using ELISA. Carotid endarterectomy samples from individuals with (N = 24) and without (N = 22) T2DM were stained for intraplaque CD68⁺ macrophages (inflammation) and CD34⁺ (angiogenesis), as plaque vulnerability markers.

Results

Monocyte counts were similar between individuals with T2DM and healthy controls (non-diabetic, non-MVD). Non-classical monocytes were reduced (p < 0.05) in T2DM, whereas the percentage of TEMs within the intermediate subset was increased (p < 0.05). T2DM was associated with increased angiopoietin-1 (p < 0.05) and angiopoietin-2 (p = 0.0001) levels. Angiopoietin-2 levels were higher in T2DM individuals with MVD compared with non-MVD (p < 0.01). Endarterectomized plaques showed no differences in macrophage influx and microvessel number between individuals with and without T2DM.

Conclusions

Monocyte subset distribution is altered in T2DM with reduced non-classical monocytes and increased TEM percentage in the intermediate monocyte subset. Increased angiopoietin-2 levels together with increased frequency of TEMs might promote plaque vulnerability in T2DM which could however not be confirmed at tissue level in advanced atherosclerotic lesions.

NLGP regulates RGS5-TGFβ axis to promote pericyte-dependent vascular normalization during restricted tumor growth

Altered RGS5-associated intracellular pericyte signaling and its abnormal crosstalk with endothelial cells (ECs) result chaotic tumor-vasculature, prevent effective drug delivery, promote immune-evasion and many more to ensure ultimate tumor progression. Moreover, the frequency of lethal-RGS5^high  pericytes within tumor was found to increase with disease progression, which signifies the presence of altered cell death pathway within tumor microenvironment (TME). In this study, we checked whether and how neem leaf glycoprotein (NLGP)-immunotherapy-mediated tumor growth restriction is associated with modification of pericytes' signaling, functions and its interaction with ECs. Analysis of pericytes isolated from tumors of NLGP treated mice suggested that NLGP treatment promotes apoptosis of NG2⁺ RGS5^high -fuctionally altered pericytes by downregulating intra-tumoral TGFβ, along with maintenance of more matured RGS5^neg  pericytes. NLGP-mediated inhibition of TGFβ within TME rescues binding of RGS5 with Gαi and thereby termination of PI3K-AKT mediated survival signaling by downregulating Bcl2 and initiating pJNK mediated apoptosis. Limited availability of TGFβ also prevents complex-formation between RGS5 and Smad2 and rapid RGS5 nuclear translocation to mitigate alternate immunoregulatory functions of RGS5^high  tumor-pericytes. We also observed binding of Ang1 from pericytes with Tie2 on ECs in NLGP-treated tumor, which support re-association of pericytes with endothelium and subsequent vessel stabilization. Furthermore, NLGP-therapy- associated RGS5 deficiency relieved CD4⁺  and CD8⁺ T cells from anergy by regulating 'alternate-APC-like' immunomodulatory characters of tumor-pericytes. Taken together, present study described the mechanisms of NLGP's effectiveness in normalizing tumor-vasculature by chiefly modulating pericyte-biology and EC-pericyte interactions in tumor-host to further strengthen its translational potential as single modality treatment.

Tissue-resident FOLR2+ macrophages associate with CD8+ T cell infiltration in human breast cancer

Macrophage infiltration is a hallmark of solid cancers, and overall macrophage infiltration correlates with lower patient survival and resistance to therapy. Tumor-associated macrophages, however, are phenotypically and functionally heterogeneous. Specific subsets of tumor-associated macrophage might be endowed with distinct roles on cancer progression and antitumor immunity. Here, we identify a discrete population of FOLR2+ tissue-resident macrophages in healthy mammary gland and breast cancer primary tumors. FOLR2+ macrophages localize in perivascular areas in the tumor stroma, where they interact with CD8+ T cells. FOLR2+ macrophages efficiently prime effector CD8+ T cells ex vivo. The density of FOLR2+ macrophages in tumors positively correlates with better patient survival. This study highlights specific roles for tumor-associated macrophage subsets and paves the way for subset-targeted therapeutic interventions in macrophages-based cancer therapies.

Combination strategies with PD-1/PD-L1 blockade: current advances and future directions

Antibodies targeting programmed cell death protein-1 (PD-1) or its ligand PD-L1 rescue T cells from exhausted status and revive immune response against cancer cells. Based on the immense success in clinical trials, ten α-PD-1 (nivolumab, pembrolizumab, cemiplimab, sintilimab, camrelizumab, toripalimab, tislelizumab, zimberelimab, prolgolimab, and dostarlimab) and three α-PD-L1 antibodies (atezolizumab, durvalumab, and avelumab) have been approved for various types of cancers. Nevertheless, the low response rate of α-PD-1/PD-L1 therapy remains to be resolved. For most cancer patients, PD-1/PD-L1 pathway is not the sole speed-limiting factor of antitumor immunity, and it is insufficient to motivate effective antitumor immune response by blocking PD-1/PD-L1 axis. It has been validated that some combination therapies, including α-PD-1/PD-L1 plus chemotherapy, radiotherapy, angiogenesis inhibitors, targeted therapy, other immune checkpoint inhibitors, agonists of the co-stimulatory molecule, stimulator of interferon genes agonists, fecal microbiota transplantation, epigenetic modulators, or metabolic modulators, have superior antitumor efficacies and higher response rates. Moreover, bifunctional or bispecific antibodies containing α-PD-1/PD-L1 moiety also elicited more potent antitumor activity. These combination strategies simultaneously boost multiple processes in cancer-immunity cycle, remove immunosuppressive brakes, and orchestrate an immunosupportive tumor microenvironment. In this review, we summarized the synergistic antitumor efficacies and mechanisms of α-PD-1/PD-L1 in combination with other therapies. Moreover, we focused on the advances of α-PD-1/PD-L1-based immunomodulatory strategies in clinical studies. Given the heterogeneity across patients and cancer types, individualized combination selection could improve the effects of α-PD-1/PD-L1-based immunomodulatory strategies and relieve treatment resistance.

HMGB1-Mediated Activation of the Inflammatory-Reparative Response Following Myocardial Infarction

Different cell types belonging to the innate and adaptive immune system play mutually non-exclusive roles during the different phases of the inflammatory-reparative response that occurs following myocardial infarction. A timely and finely regulation of their action is fundamental for the process to properly proceed. The high-mobility group box 1 (HMGB1), a highly conserved nuclear protein that in the extracellular space can act as a damage-associated molecular pattern (DAMP) involved in a large variety of different processes, such as inflammation, migration, invasion, proliferation, differentiation, and tissue regeneration, has recently emerged as a possible regulator of the activity of different immune cell types in the distinct phases of the inflammatory reparative process. Moreover, by activating endogenous stem cells, inducing endothelial cells, and by modulating cardiac fibroblast activity, HMGB1 could represent a master regulator of the inflammatory and reparative responses following MI. In this review, we will provide an overview of cellular effectors involved in these processes and how HMGB1 intervenes in regulating each of them. Moreover, we will summarize HMGB1 roles in regulating other cell types that are involved in the different phases of the inflammatory-reparative response, discussing how its redox status could affect its activity.

Tumor cell-derived exosomes deliver TIE2 protein to macrophages to promote angiogenesis in cervical cancer

Tyrosine kinase with immunoglobulin and epidermal growth factor homology domains 2 (TIE2)-expressing macrophages (TEMs) are an angiogenesis-promoting subset of tumor-associated macrophages that have been demonstrated to be increased in solid tumors and associated with the progression of cervical cancer. However, the induction mechanism of TEMs remains unclear. Here, based on multicolor immunofluorescence of 58 cervical cancer tissues and the GEPIA database, we found that TEMs were increased in TIE2-high cervical cancer and related to shorter survival. In vitro and in vivo experiments verified that exosomes derived from TIE2-high cervical cancer cells transferred TIE2 protein directly to macrophages, thereby inducing TEMs. Similar to primary TEMs, TEMs induced by tumor-derived exosomes promoted angiogenesis, could be induced by angiopoietin-2, and possessed an M2-like phenotype. In conclusion, exosomes derived from TIE2-high cervical cancer cells induce TEMs by directly transporting TIE2 to promote tumor angiogenesis.

Monocytes mediate Salmonella Typhimurium-induced tumor growth inhibition in a mouse melanoma model

The use of bacteria as an alternative cancer therapy has been reinvestigated in recent years. SL7207: an auxotrophic Salmonella enterica serovar Typhimurium aroA mutant with immune-stimulatory potential has proven a promising strain for this purpose. Here, we show that systemic administration of SL7207 induces melanoma tumor growth arrest in vivo, with greater survival of the SL7207-treated group compared to control PBS-treated mice. Administration of SL7207 is accompanied by a change in the immune phenotype of the tumor-infiltrating cells toward pro-inflammatory, with expression of the TH 1 cytokines IFN-γ, TNF-α, and IL-12 significantly increased. Interestingly, Ly6C+ MHCII+ monocytes were recruited to the tumors following SL7207 treatment and were pro-inflammatory. Accordingly, the abrogation of these infiltrating monocytes using clodronate liposomes prevented SL7207-induced tumor growth inhibition. These data demonstrate a previously unappreciated role for infiltrating inflammatory monocytes underlying bacterial-mediated tumor growth inhibition. This information highlights a possible novel role for monocytes in controlling tumor growth, contributing to our understanding of the immune responses required for successful immunotherapy of cancer.

Reviewing Schwannoma-Hemangioma Composite Tumors With Their Tumorigenetic Molecular Pathways and Associated Syndromic Manifestations

Schwannomas are common peripheral nerve sheath tumors. Cavernous hemangiomas are vascular tumors that can affect any organ system. The coexistence of cavernous hemangioma with peripheral nervous system neoplasms is a rare occurrence. So far, 37 cases have been documented, and they have been divided into two categories: conjoined association (neoplasms discovered within the tumor tissue) and discrete association (neoplasms discovered outside the tumor tissue, thus placing neoplasms and tumors in close proximity but in different locations). Schwannomas and neurofibromas are the most prevalent tumors linked to cavernous hemangiomas that have been documented. The author provides a comprehensive review of all such cases published in the past with an emphasis on the implications of their tumorigenetic molecular pathways and syndromic manifestations.

Propensity for Early Metastatic Spread in Breast Cancer: Role of Tumor Vascularization Features and Tumor Immune Infiltrate

Breast cancer is a complex and highly heterogeneous disease consisting of various subtypes. It is classified into human epidermal growth receptor 2 (HER-2)-enriched, luminal A, luminal B and basal-like/triple negative (TNBC) breast cancer, based on histological and molecular features. At present, clinical decision-making in breast cancer is focused only on the assessment of tumor cells; nevertheless, it has been recognized that the tumor microenvironment (TME) plays a critical biologic role in breast cancer. This is constituted by a large group of immune and non-immune cells, but also by non-cellular components, such as several cytokines. TME is deeply involved in angiogenesis, immune-evasion strategies, and propensity for early metastatic spread, impacting on prognosis and prediction of response to specific treatments. In this review, we focused our attention on the early morphological changes of tumor microenvironment (tumor vasculature features, presence of immune and non-immune cells infiltrating the stroma, levels of cytokines) during breast cancer development. At the same time, we correlate these characteristics with early metastatic propensity (defined as synchronous metastasis or early recurrence) with particular attention to breast cancer subtypes.

Impact of immune cells on the hallmarks of cancer: A literature review

Tumor-infiltrating immune cells (TIICs) are critical players in the tumor microenvironment, modulating cancer cell functions. TIICs are highly heterogenic and plastic and may either suppress cancers or provide support for tumor growth. A wide range of studies have shed light on how tumor-associated macrophages, dendritic cells, neutrophils, mast cells, natural killer cells and lymphocytes contribute for the establishment of several hallmarks of cancer and became the basis for successful immunotherapies. Many of those TIICs play pivotal roles in several hallmarks of cancer. This review contributes to elucidate the multifaceted roles of immune cells in cancer development, highlighting molecular components that constitute promising therapeutic targets. Additional studies are needed to clarify the relation between TIICs and hallmarks such as enabling replicative immortality, evading growth suppressors, sustaining proliferative signaling, resisting cell death and genome instability and mutation, to further explore their therapeutic potential and improve the outcomes of cancer patients.

Combining CTLA-4 and angiopoietin-2 blockade in patients with advanced melanoma: a phase I trial

Background

Angiogenic factors promote the growth of tumor vasculature, modulate lymphocyte trafficking into tumors, and inhibit maturation of dendritic cells. We hypothesized that MEDI3617, a human IgG1 kappa monoclonal antibody directed against human angiopoietin-2, in combination with tremelimumab (treme), an IgG2 monoclonal antibody blocking cytotoxic T-lymphocyte-associated protein- (CTLA-4), is safe in patients with advanced melanoma.

Methods

In a phase I, 3+3 dose escalation trial, patients with metastatic or unresectable melanoma received treme in combination with MEDI3617. The primary objectives of the study were safety and determination of recommended phase II dose (RP2D). The secondary objectives included determination of 6-month and 1-year overall survival and best overall response rate. Immune cell populations and soluble factors were assessed in peripheral blood and metastatic tumors using Fluorescence activated cell sorting (FACS), Luminex, and multiplexed immunofluorescence.

Results

Fifteen patients (median age: 62) were enrolled in the study (3 patients in cohort 1: treme at 10 mg/kg and MEDI3617 at 200 mg; and 12 patients in cohort 2: treme at 10 mg/kg and MEDI3617 at 600 mg). The most common all-grade treatment-related adverse events were rash, pruritus, fatigue, and extremity edema. No dose-limiting toxicities were observed. Cohort 2 was determined to be the RP2D. There were no patients with confirmed immune-related complete response or immune-related partial response. Six of 15 patients had immune-related stable disease, resulting in a disease control rate of 0.40 (95% CI 0.16 to 0.68). An increase in frequencies of circulating inducible T-cell costimulator (ICOS)⁺ and human leukocyte antigen (HLA)-DR⁺ CD4⁺ and CD8⁺ T cells and production of Interleukin-2 and Interleukin-10 was observed post therapy.

Conclusions

Tremelimumab in combination with MEDI3617 is safe in patients with advanced melanoma. Angiopoietin-2 inhibition in combination with immune checkpoint inhibition warrants further exploration.

Trial registration number

NCT02141542.

Oxygen and metabolic reprogramming in the tumor microenvironment influences metastasis homing

Tumor metastasis is the leading cause of cancer mortality, often characterized by abnormal cell growth and invasion to distant organs. The cancer invasion due to epithelial to mesenchymal transition is affected by metabolic and oxygen availability in the tumor-associated micro-environment. A precise alteration in oxygen and metabolic signaling between healthy and metastatic cells is a substantial probe for understanding tumor progression and metastasis. Molecular heterogeneity in the tumor microenvironment help to sustain the metastatic cell growth during their survival shift from low to high metabolic-oxygen-rich sites and reinforces the metastatic events. This review highlighted the crucial role of oxygen and metabolites in metastatic progression and exemplified the role of metabolic rewiring and oxygen availability in cancer cell adaptation. Furthermore, we have also addressed potential applications of altered oxygen and metabolic networking with tumor type that could be a signature pattern to assess tumor growth and chemotherapeutics efficacy in managing cancer metastasis.