FGL2 promotes tumor progression in the CNS by suppressing CD103+ dendritic cell differentiation

Fibrinogen-like 2 in tumor-associated macrophage-derived extracellular vesicles shapes an immunosuppressive microenvironment in colorectal liver metastases by promoting tumor stemness and neutrophil extracellular traps formation

Investigating the mechanisms underlying the development of an immunosuppressive microenvironment within colorectal liver metastases (CRLM) is important for identifying synergistic targets for immunotherapy. The regulatory role of tumor-associated macrophage-derived extracellular vesicles (TAM-EVs) in the immune microenvironment of CRLM has not yet been fully explored. Here, we found that TAM-EVs shaped the immunosuppressive microenvironment at the invasive front in murine CRLM models, thus dampening anti-PD-1 immunotherapy. This environment is characterized by an increased tumor stemness potential and abundant neutrophil extracellular traps (NETs) formation. Mechanistically, TAM-EVs-derived fibrinogen-like 2 (FGL2) interacts with the FCGR2B receptor in tumor cells, which further activates a p-STAT3/IL-1β positive feedback loop to increase the stemness potential of cancer cells, whereas IL-1β mediates the communication between cancer cells and neutrophils. The use of an anti-IL-1β monoclonal antibody can reduce NETs production and synergize with anti-PD-1 immunotherapy, which offers clinical translational significance for CRLM therapy. The FGL2/p-STAT3/IL-1β loop correlates with an immunosuppressive microenvironment and poor prognosis in human patients with CRLM. Our results revealed the potential of enhancing the efficacy of immunotherapy via the targeted clearance of NETs using anti-IL-1β monoclonal antibodies, which have significant clinical translational value in the treatment of CRLM.

Role of fibrinogen-like 2 (FGL2) proteins in implantation: Potential implications and mechanism

Fibrinogen-like (Fgl2) protein belongs to fibrinogen super family, which catalyzes the conversion of prothrombin to thrombin and is involved in the coagulation process. There are two different forms of functional Fgl2 protein: membrane associated Fgl2 (mFgl2) and soluble Fgl2 (sFgl2). mFgl2, as a type II transmembrane protein with property with prothrombinase activity from its N-terminal fragment, was extensively secreted or expressed by inflammatory macrophages, dendritic cells (DCs), Th1 cells and endothelial cells. While sFgl2 was mainly produced by regulatory T cells (Tregs) and then secreted into the vasculature, which contributes to autoimmune disease by regulating maturation of (DCs), polarization of macrophage, inhibiting T cell proliferation and differentiation and inducing apoptosis of B cells. In particular, emerging evidence has shown that Fgl2 is implicated in female reproductive system that contributes to embryo development, ovarian granulosa cells differentiation and implantation failure. This article summarizes the role and potential mechanisms of Fgl2 in reproduction and identifies research gaps along with the future directions.

Macrophage-derived Fgl2 dampens antitumor immunity through regulation of FcγRIIB+CD8+ T cells in melanoma

Cancer immunotherapy has emerged as a promising therapeutic modality but heterogeneity in patient responsiveness remains. Thus, greater understanding of the immunologic factors that dictate response to immunotherapy is critical to improve patient outcomes. Here, we show that fibrinogen-like protein 2 (Fgl2) is elevated in the setting of melanoma in humans and mice and plays a functional role in inhibiting the CD8+ T cell response. Surprisingly, the tumor itself is not the major cellular source of Fgl2. Instead, we found that macrophage-secreted Fgl2 dampens the CD8+ T cell response through binding and apoptosis of FcγRIIB+CD8+ T cells. This regulation was CD8+ T cell autonomous and not via an antigen-presenting cell intermediary, as absence of Fcgr2b from the CD8+ T cells rendered T cells insensitive to Fgl2 regulation. Fgl2 is robustly expressed by macrophages in 10 cancer types in humans and in 6 syngeneic tumor models in mice, underscoring the clinical relevance of Fgl2 as a therapeutic target to promote T cell activity and improve patient immunotherapeutic response.

New insights on anti-tumor immunity of CD8+ T cells: cancer stem cells, tumor immune microenvironment and immunotherapy

Recent breakthroughs in tumor immunotherapy have confirmed the capacity of the immune system to fight several cancers. The effective means of treating cancer involves accelerating the death of tumor cells and improving patient immunity. Dynamic changes in the tumor immune microenvironment alter the actual effects of anti-tumor drug production and may trigger favorable or unfavorable immune responses by modulating tumor-infiltrating lymphocytes. Notably, CD8+ T cells are one of the primary tumor-infiltrating immune cells that provide anti-tumor response. Tumor cells and tumor stem cells will resist or evade destruction through various mechanisms as CD8+ T cells exert their anti-tumor function. This paper reviews the research on the regulation of tumor development and prognosis by cancer stem cells that directly or indirectly alter the role of tumor-infiltrating CD8+ T cells. We also discuss related immunotherapy strategies.

Fibrinogen: A new player and target on the formation of pre-metastatic niche in tumor metastasis

Tumor metastasis involves a series of complex and coordinated processes, which is the main cause of patient death and still a significant challenge in cancer treatment. Pre-metastatic niches (PMN), a specialized microenvironment that develops in distant organs prior to the arrival of metastatic cancer cells, plays a crucial role in driving tumor metastasis. The development of PMN depends on a complex series of cellular and molecular components including tumor-derived factors, bone marrow-derived cells, resident immune cells, and extracellular matrix. Fibrinogen, a key factor in the typical blood clotting process, is related to tumor metastasis and prognosis, according to a growing body of evidence in recent years. Fibrinogen has emerged as an important factor in mediating the formation of tumor microenvironment. Nevertheless, a clear and detailed mechanism by which fibrinogen promotes tumor metastasis remains unknown. In this review, we first explore the roles of fibrinogen in the development of PMN from four perspectives: immunosuppression, inflammation, angiogenesis, and extracellular matrix remodeling. We highlight the significance of fibrinogen in shaping PMN and discuss its potential therapeutic values, opening new avenues for targeting fibrinogen to prevent or treat metastasis.

Microenvironmental Drivers of Glioma Progression

Gliomas, particularly glioblastoma (GBM), are among the most challenging brain tumors due to their complex and dynamic tumor microenvironment (TME). The TME plays a pivotal role in tumor progression, immune evasion, and resistance to therapy through intricate interactions among glioma cells, immune components, neurons, astrocytes, the extracellular matrix, and the blood-brain barrier. Targeting the TME has demonstrated potential, with immunotherapies such as checkpoint inhibitors and neoadjuvant therapies enhancing immune responses. Nonetheless, overcoming the immunosuppressive landscape and metabolic adaptations continues to pose significant challenges. This review explores the diverse cellular and molecular mechanisms that shape the glioma TME. A deeper understanding of these mechanisms holds promise for providing novel therapeutic opportunities to improve glioma treatment outcomes.

FGL2172-220 peptides improve the antitumor effect of HCMV-IE1mut vaccine against glioblastoma by modulating immunosuppressive cells in the tumor microenvironment

Glioblastoma multiforme (GBM) is a highly aggressive primary brain tumor characterized by poor prognosis and lack of effective treatments. In recent years, peptide vaccines that use sequences based on tumor-specific or tumor-associated antigens to activate immune responses against tumor cells have emerged as a new therapeutic strategy. In this study, we developed a novel therapeutic polypeptide vaccine targeting the tumor-associated antigen Fibrinogen-Like Protein 2 (FGL2), whose dominant epitope peptide was tandemly linked to the C-terminus of HCMV-IE1mut via a linker. We used this vaccine to compare the therapeutic efficacy of HCMV-IE1mut alone versus HCMV-IE1mut-FGL2172-220 and investigate the potential mechanism of action of HCMV-IE1mut-FGL2172-220 in glioma treatment. An in situ GBM model (GL261-IE1-luc cells) was used to determine the efficacy of the vaccine. Treatment with HCMV-IE1mut-FGL2172-220 exerted antitumor effects and extended the survival of the GL261 animal model. We observed reduced proportions of microglia, regulatory T cells (Treg), and myeloid-derived suppressor cells (MDSC) in the tumor microenvironment (TME) by immunofluorescence. Flow cytometry showed that compared to HCMV-IE1mut alone, treatment with HCMV-IE1mut-FGL2172-220 increased the proportion of CD8+ T cells and tissue-resident memory T cells (TRM). ELISA analysis showed that it improved the secretion of tumor-specific IFN-γ and TNF-α by these cells and downregulated the expression of IL-6 and IL-10. Our study demonstrates that the long-peptide FGL2172-220 improves the antitumor efficacy of HCMV-IE1mut, possibly by reshaping immune cells in the glioma microenvironment. These findings lay the groundwork for the development of therapeutic antigenic peptide vaccines to improve antitumor effects for cancer.

FGL2: A new target molecule for coagulation and immune regulation in infectious disease

Infectious diseases are complex inflammatory-immunologic host responses caused by various pathogens, such as viruses, bacteria, parasites, and fungi. In the process of infectious disease development, immune cells are activated, and a substantial number of inflammatory factors are released within the endothelium, which results in coagulation activation and the formation of intravascular thrombi. Furthermore, infection-induced hypercoagulability amplifies the inflammatory response and immune dysregulation. Emerging evidence suggests that fibrinogen-like protein 2 (FGL2) has a crucial role in facilitating procoagulant, pro-inflammatory, and immune-regulatory responses in various infectious diseases. This review illustrates the complex procoagulation and immunoregulatory roles of FGL2, suggesting it could be a target for novel immune interventions in intractable infectious diseases.

Prognostic significance and gene co-expression network of CD16A and FGL2 in gliomas

Introduction

The CD16A protein encoding gene FcγRIIIa (FCGR3A) and its potential ligand Fibrinogen-like protein 2 (FGL2) are involved in various cell physiological activities on the extracellular surface. Aberrant expression of these genes has been linked to tumorigenesis.

Methods

To assess the prognostic significance of FCGR3A and FGL2 transcription expression in glioma and explore their roles in glioma initiation and progression, we utilized multiple online databases, including TCGA, GEPIA, CGGA, cBioPortal, TISCH, LinkedOmics, Ivy Glioblastoma Atlas Project, and Human Protein Atlas.

Results

Our analysis revealed that FCGR3A and FGL2 expression was significantly correlated with clinical variables such as age, tumor type, WHO grade, histology, IDH-1 mutation, and 1p19q status. A strong correlation was also observed between the transcriptional expression levels of FCGR3A and FGL2. High expression of both genes predicted poor prognosis in primary and recurrent glioma patients, particularly those with lower grade gliomas. Cox regression analysis further confirmed that elevated expression of FCGR3A and FGL2 were independent prognostic factors for shorter overall survival in glioma patients. Gene co-expression network analysis suggested that FCGR3A, FGL2, and their co-expressed genes were involved in inflammatory activities and tumor-related signaling pathways. Additionally, tissue microarrays from glioma patients at Tiantan Hospital showed significantly higher FCGR3A protein expression in high-grade gliomas compared to low-grade gliomas.

Discussion

In conclusion, our findings suggest that FCGR3A and FGL2 could serve as promising prognostic biomarkers and potential therapeutic targets for glioma patients.

Inhibitory Fcγ receptor deletion enhances CD8 T cell stemness increasing anti-PD-1 therapy responsiveness against glioblastoma

BACKGROUND

Certain cancers present challenges for treatment because they are resistant to immune checkpoint blockade (ICB), attributed to low tumor mutational burden and the absence of T cell-inflamed features. Among these, glioblastoma (GBM) is notoriously resistant to ICB. To overcome this resistance, the identification of T cells with heightened stemness marked by T-cell factor 1 (TCF1) expression has gained attention. Several studies have explored ways to preserve stem-like T cells and prevent terminal exhaustion. In this study, we investigate a target that triggers stem-like properties in CD8 T cells to enhance the response to ICB in a murine GBM model.

METHODS

Using Fcgr2b-/- mice and a murine GL261 GBM model, we confirmed the efficacy of anti-programmed cell death protein-1 (PD-1) immunotherapy, observing improved survival. Analysis of immune cells using fluorescence-activated cell sorting and single-cell RNA sequencing delineated distinct subsets of tumor-infiltrating CD8 T cells in Fcgr2b-/- mice. The crucial role of the stem-like feature in the response to anti-PD-1 treatment for reinvigorating CD8 T cells was analyzed. Adoptive transfer of OT-I cells into OVA-expressing GL261 models and CD8 T cell depletion in Fcgr2b-/- mice confirmed the significance of Fcgr2b-/- CD8 T cells in enhancing the antitumor response. Last, S1P1 inhibitor treatment confirmed that the main source of tumor antigen-specific Fcgr2b-/- CD8 T cells is the tumor-draining lymph nodes (TdLNs).

RESULTS

In a murine GBM model, anti-PD-1 monotherapy and single-Fc fragment of IgG receptor IIb (FcγRIIB) deletion exhibit limited efficacy. However, their combination substantially improves survival by enhancing cytotoxicity and proliferative capacity in tumor-infiltrating Fcgr2b-/- CD8 T cells. The improved response to anti-PD-1 treatment is associated with the tumor-specific memory T cells (Ttsms) exhibiting high stemness characteristics within the tumor microenvironment (TME). Ttsms in the TdLN thrives in a protective environment, maintaining stem-like characteristics and serving as a secure source for tumor infiltration. This underscores the significance of FcγRIIB ablation in triggering Ttsms and enhancing ICB therapy against GBM.

CONCLUSIONS

Deletion of FcγRIIB on CD8 T cells leads to the generation of a Ttsms, which is localized in TdLN and protected from the immunosuppressive TME. Incorporating these highly stemness-equipped Ttsms enhances the response to anti-PD-1 therapy in immune-suppressed brain tumors.

Role of T Lymphocytes in Glioma Immune Microenvironment: Two Sides of a Coin

Glioma is known for its immunosuppressive microenvironment, which makes it challenging to target through immunotherapies. Immune cells like macrophages, microglia, myeloid-derived suppressor cells, and T lymphocytes are known to infiltrate the glioma tumor microenvironment and regulate immune response distinctively. Among the variety of immune cells, T lymphocytes have highly complex and multifaceted roles in the glioma immune landscape. T lymphocytes, which include CD4+ helper and CD8+ cytotoxic T cells, are known for their pivotal roles in anti-tumor responses. However, these cells may behave differently in the highly dynamic glioma microenvironment, for example, via an immune invasion mechanism enforced by tumor cells. Therefore, T lymphocytes play dual roles in glioma immunity, firstly by their anti-tumor responses, and secondly by exploiting gliomas to promote immune invasion. As an immunosuppression strategy, glioma induces T-cell exhaustion and suppression of effector T cells by regulatory T cells (Tregs) or by altering their signaling pathways. Further, the expression of immune checkpoint inhibitors on the glioma cell surface leads to T cell anergy and dysfunction. Overall, this dynamic interplay between T lymphocytes and glioma is crucial for designing more effective immunotherapies. The current review provides detailed knowledge on the roles of T lymphocytes in the glioma immune microenvironment and helps to explore novel therapeutic approaches to reinvigorate T lymphocytes.

Integrated analysis of bulk and single-cell RNA-seq data reveals cell differentiation-related subtypes and a scoring system in bladder cancer

Bladder cancer (BLCA) exhibits notable molecular heterogeneity, influencing diverse clinical outcomes. However, the molecular subtypes associated with cell differentiation-related genes (CDR) and their prognostic implications remain unexplored. Analysing two GEO single-cell datasets, we identified genes linked to cell differentiation. Utilizing these genes, we explored distinct molecular subtypes. WGCNA analysis further identified CDR-associated genes, and the CDR score system, constructed using Lasso and Cox regression, was developed. Clinical prognosis and variations in immune-related factors among patient groups were assessed. Core genes were selected and confirmed through in vitro experiments. Two BLCA subtypes related to cell differentiation were identified: Subtype B demonstrated a favourable prognosis, while Subtype A exhibited significant immune cell infiltration. The CDR score system of nine genes revealed a positive correlation between higher scores and a poorer prognosis. The comprehensive analysis uncovered a positive association between CDR genes and M2 macrophages and unresponsiveness to immune therapy. Functional experiments validated that ANXA5 downregulation influences tumour cell migration without affecting proliferation. Our study reveals distinct cell differentiation-related molecular subtypes and introduces the CDR scoring system in BLCA. ANXA5 emerges as a potential therapeutic target, offering promising avenues for personalized treatment strategies.

Dendritic Cell-Hitchhiking In Vivo for Vaccine Delivery to Lymph Nodes

Therapeutic cancer vaccines are among the first FDA-approved cancer immunotherapies. Among them, it remains a major challenge to achieve robust lymph-node (LN) accumulation. However, delivering cargo into LN is difficult owing to the unique structure of the lymphatics, and clinical responses have been largely disappointing. Herein, inspired by the Migrated-DCs homing from the periphery to the LNs, an injectable hydrogel-based polypeptide vaccine system is described for enhancing immunostimulatory efficacy, which could form a local niche of vaccine "hitchhiking" on DCs. The OVA peptide modified by lipophilic DSPE domains in the hydrogel is spontaneously inserted into the cell membrane to achieve "antigen anchoring" on DCs in vivo. Overall, OVA peptide achieves active access LNs through recruiting and "hitchhiking" subcutaneous Migrated-DCs. Remarkably, it is demonstrated that the composite hydrogel enhances LNs targeting efficacy by approximately six-fold compared to free OVA peptide. Then, OVA peptide can be removed from the cell surface under a typical acidic microenvironment within the LNs, further share them with LN-resident APCs via the "One-to-Many" strategy (One Migrated-DC corresponding to Many LN-resident APCs), thereby activating powerful immune stimulation. Moreover, the hydrogel vaccine exhibits significant tumor growth inhibition in melanoma and inhibits pulmonary metastatic nodule formation.

Glioblastoma-derived exosomes promote lipid accumulation and induce ferroptosis in dendritic cells via the NRF2/GPX4 pathway

Glioblastoma-derived exosomes (GDEs), containing nucleic acids, proteins, fatty acids and other substances, perform multiple important functions in glioblastoma microenvironment. Tumor-derived exosomes serve as carriers of fatty acids and induce a shift in metabolism towards oxidative phosphorylation, thus driving immune dysfunction of dendritic cells (DCs). Lipid peroxidation is an important characteristic of ferroptosis. Nevertheless, it remains unclear whether GDEs can induce lipid accumulation and lipid oxidation to trigger ferroptosis in DCs. In our study, we investigate the impact of GDEs on lipid accumulation and oxidation in DCs by inhibiting GDEs secretion through knocking down the expression of Rab27a using a rat orthotopic glioblastoma model. The results show that inhibiting the secretion of GDEs can reduce lipid accumulation in infiltrating DCs in the brain and decrease mature dendritic cells (mDCs) lipid peroxidation levels, thereby suppressing glioblastoma growth. Mechanistically, we employed in vitro treatments of bone marrow-derived dendritic cells (BMDCs) with GDEs. The results indicate that GDEs decrease the viability of mDCs compared to immature dendritic cells (imDCs) and trigger ferroptosis in mDCs via the NRF2/GPX4 pathway. Overall, these findings provide new insights into the development of immune-suppressive glioblastoma microenvironment through the interaction of GDEs with DCs.

The CEBPB+ glioblastoma subcluster specifically drives the formation of M2 tumor-associated macrophages to promote malignancy growth

Rationale: The heterogeneity of tumor cells within the glioblastoma (GBM) microenvironment presents a complex challenge in curbing GBM progression. Understanding the specific mechanisms of interaction between different GBM cell subclusters and non-tumor cells is crucial. Methods: In this study, we utilized a comprehensive approach integrating glioma single-cell and spatial transcriptomics. This allowed us to examine the molecular interactions and spatial localization within GBM, focusing on a specific tumor cell subcluster, GBM subcluster 6, and M2-type tumor-associated macrophages (M2 TAMs). Results: Our analysis revealed a significant correlation between a specific tumor cell subcluster, GBM cluster 6, and M2-type TAMs. Further in vitro and in vivo experiments demonstrated the specific regulatory role of the CEBPB transcriptional network in GBM subcluster 6, which governs its tumorigenicity, recruitment of M2 TAMs, and polarization. This regulation involves molecules such as MCP1 for macrophage recruitment and the SPP1-Integrin αvβ1-Akt signaling pathway for M2 polarization. Conclusion: Our findings not only deepen our understanding of the formation of M2 TAMs, particularly highlighting the differential roles played by heterogeneous cells within GBM in this process, but also provided new insights for effectively controlling the malignant progression of GBM.

Identification of two key biomarkers CD93 and FGL2 associated with survival of acute myeloid leukaemia by weighted gene co-expression network analysis

Acute myeloid leukaemia (AML) is a biologically heterogeneous haematological malignancy. This study was performed to identify the potential biomarkers for the prognosis and treatment of AML. We applied weighted gene co-expression network analysis to identify key modules and hub genes related to the prognosis of AML using data from The Cancer Genome Atlas (TCGA). In total, 1581 differentially expressed genes (1096 upregulated and 485 downregulated) were identified between AML patients and healthy controls, with the blue module being the most significant among 14 modules associated with AML morphology. Through functional enrichment analysis, we identified 217 genes in the blue module significantly enriched in 'neutrophil degranulation' and 'neutrophil activation involved in immune response' pathways. The survival analysis revealed six genes (S100A9, S100A8, HK3, CD93, CXCR2 and FGL2) located in the significantly enriched pathway that were notably related to AML survival. We validated the expression of these six genes at gene and single-cell levels and identified methylation loci of each gene, except for S100A8. Finally, in vitro experiments were performed to demonstrate whether the identified hub genes were associated with AML survival. After knockdown of CD93 and FGL2, cell proliferation was significantly reduced in U937 cell line over 5 days. In summary, we identified CD93 and FGL2 as key hub genes related to AML survival, with FGL2 being a novel biomarker for the prognosis and treatment of AML.

CD8+ T cell-derived Fgl2 regulates immunity in a cell-autonomous manner via ligation of FcγRIIB

The regulatory circuits dictating CD8+ T cell responsiveness versus exhaustion during anti-tumor immunity are incompletely understood. Here we report that tumor-infiltrating antigen-specific PD-1+ TCF-1- CD8+ T cells express the immunosuppressive cytokine Fgl2. Conditional deletion of Fgl2 specifically in mouse antigen-specific CD8+ T cells prolongs CD8+ T cell persistence, suppresses phenotypic and transcriptomic signatures of T cell exhaustion, and improves control of the tumor. In a mouse model of chronic viral infection, PD-1+ CD8+ T cell-derived Fgl2 also negatively regulates virus-specific T cell responses. In humans, CD8+ T cell-derived Fgl2 is associated with poorer survival in patients with melanoma. Mechanistically, the dampened responsiveness of WT Fgl2-expressing CD8+ T cells, when compared to Fgl2-deficient CD8+ T cells, is underpinned by the cell-intrinsic interaction of Fgl2 with CD8+ T cell-expressed FcγRIIB and concomitant caspase 3/7-mediated apoptosis. Our results thus illuminate a cell-autonomous regulatory axis by which PD-1+ CD8+ T cells both express the receptor and secrete its ligand in order to mediate suppression of anti-tumor and anti-viral immunity.

FGL1 and FGL2: emerging regulators of liver health and disease

Liver disease is a complex group of diseases with high morbidity and mortality rates, emerging as a major global health concern. Recent studies have highlighted the involvement of fibrinogen-like proteins, specifically fibrinogen-like protein 1 (FGL1) and fibrinogen-like protein 2 (FGL2), in the regulation of various liver diseases. FGL1 plays a crucial role in promoting hepatocyte growth, regulating lipid metabolism, and influencing the tumor microenvironment (TME), contributing significantly to liver repair, non-alcoholic fatty liver disease (NAFLD), and liver cancer. On the other hand, FGL2 is a multifunctional protein known for its role in modulating prothrombin activity and inducing immune tolerance, impacting viral hepatitis, liver fibrosis, hepatocellular carcinoma (HCC), and liver transplantation. Understanding the functions and mechanisms of fibrinogen-like proteins is essential for the development of effective therapeutic approaches for liver diseases. Additionally, FGL1 has demonstrated potential as a disease biomarker in radiation and drug-induced liver injury as well as HCC, while FGL2 shows promise as a biomarker in viral hepatitis and liver transplantation. The expression levels of these molecules offer exciting prospects for disease assessment. This review provides an overview of the structure and roles of FGL1 and FGL2 in different liver conditions, emphasizing the intricate molecular regulatory processes and advancements in targeted therapies. Furthermore, it explores the potential benefits and challenges of targeting FGL1 and FGL2 for liver disease treatment and the prospects of fibrinogen-like proteins as biomarkers for liver disease, offering insights for future research in this field.

Understanding the immunosuppressive microenvironment of glioma: mechanistic insights and clinical perspectives

Glioblastoma (GBM), the predominant and primary malignant intracranial tumor, poses a formidable challenge due to its immunosuppressive microenvironment, thereby confounding conventional therapeutic interventions. Despite the established treatment regimen comprising surgical intervention, radiotherapy, temozolomide administration, and the exploration of emerging modalities such as immunotherapy and integration of medicine and engineering technology therapy, the efficacy of these approaches remains constrained, resulting in suboptimal prognostic outcomes. In recent years, intensive scrutiny of the inhibitory and immunosuppressive milieu within GBM has underscored the significance of cellular constituents of the GBM microenvironment and their interactions with malignant cells and neurons. Novel immune and targeted therapy strategies have emerged, offering promising avenues for advancing GBM treatment. One pivotal mechanism orchestrating immunosuppression in GBM involves the aggregation of myeloid-derived suppressor cells (MDSCs), glioma-associated macrophage/microglia (GAM), and regulatory T cells (Tregs). Among these, MDSCs, though constituting a minority (4-8%) of CD45+ cells in GBM, play a central component in fostering immune evasion and propelling tumor progression, angiogenesis, invasion, and metastasis. MDSCs deploy intricate immunosuppressive mechanisms that adapt to the dynamic tumor microenvironment (TME). Understanding the interplay between GBM and MDSCs provides a compelling basis for therapeutic interventions. This review seeks to elucidate the immune regulatory mechanisms inherent in the GBM microenvironment, explore existing therapeutic targets, and consolidate recent insights into MDSC induction and their contribution to GBM immunosuppression. Additionally, the review comprehensively surveys ongoing clinical trials and potential treatment strategies, envisioning a future where targeting MDSCs could reshape the immune landscape of GBM. Through the synergistic integration of immunotherapy with other therapeutic modalities, this approach can establish a multidisciplinary, multi-target paradigm, ultimately improving the prognosis and quality of life in patients with GBM.

N6-methyladenosine in myeloid cells: a novel regulatory factor for inflammation-related diseases

N6-methyladenosine (m6A) is one of the most abundant epitranscriptomic modifications on eukaryotic mRNA. Evidence has highlighted that m6A is altered in response to inflammation-related factors and it is closely associated with various inflammation-related diseases. Multiple subpopulations of myeloid cells, such as macrophages, dendritic cells, and granulocytes, are crucial for the regulating of immune process in inflammation-related diseases. Recent studies have revealed that m6A plays an important regulatory role in the functional of multiple myeloid cells. In this review, we comprehensively summarize the function of m6A modification in myeloid cells from the perspective of myeloid cell production, activation, polarization, and migration. Furthermore, we discuss how m6A-mediated myeloid cell function affects the progression of inflammation-related diseases, including autoimmune diseases, chronic metabolic diseases, and malignant tumors. Finally, we discuss the challenges encountered in the study of m6A in myeloid cells, intended to provide a new direction for the study of the pathogenesis of inflammation-related diseases.

LTX-315 triggers anticancer immunity by inducing MyD88-dependent maturation of dendritic cells

LTX-315 is a synthetic cationic oncolytic peptide with potent anticancer activity but limited toxicity for non-malignant cells. LTX-315 induces both immunogenic tumor cell death and generation of tumor-specific immune responses in multiple experimental tumor models. Given the central role of dendritic cell (DC) maturation in the induction of antigen-specific immunity, we investigated the effect of LTX-315 treatment on the maturation of tumor-infiltrating DCs (TiDCs) and the generation of anti-melanoma immunity. We found that LTX-315 treatment induces the maturation of DCs, both indirectly through the release of cancer cell-derived damage-associated molecular patterns (DAMPs)/alarmins and nucleic acids (DNA and RNA) capable of triggering distinct Toll-like receptor (TLR) signaling, and, directly by activating TLR7. The latter results in the ignition of multiple intracellular signaling pathways that promotes DC maturation, including NF-κB, mitogen activated protein kinases (MAPKs), and inflammasome signaling, as well as increased type 1 interferon production. Critically, the effects of LTX-315 on DCs the consequent promotion of anti-melanoma immunity depend on the cytosolic signal transducer myeloid differentiation response gene 88 (MyD88). These results cast light on the mechanisms by which LTX-315 induces DC maturation and hence elicits anticancer immunity, with important implications for the use of LTX-315 as an anticancer immunotherapeutic.

FGL2 promotes tumour growth and attenuates infiltration of activated immune cells in melanoma and ovarian cancer models

The tumour microenvironment is infiltrated by immunosuppressive cells, such as regulatory T cells (Tregs), which contribute to tumour escape and impede immunotherapy outcomes. Soluble fibrinogen-like protein 2 (sFGL2), a Treg effector protein, inhibits immune cell populations, via receptors FcγRIIB and FcγRIII, leading to downregulation of CD86 in antigen presenting cells and limiting T cell activation. Increased FGL2 expression is associated with tumour progression and poor survival in several different cancers, such as glioblastoma multiforme, lung, renal, liver, colorectal, and prostate cancer. Querying scRNA-seq human cancer data shows FGL2 is produced by cells in the tumour microenvironment (TME), particularly monocytes and macrophages as well as T cells and dendritic cells (DCs), while cancer cells have minimal expression of FGL2. We studied the role of FGL2 exclusively produced by cells in the TME, by leveraging Fgl2 knockout mice. We tested two murine models of cancer in which the role of FGL2 has not been previously studied: epithelial ovarian cancer and melanoma. We show that absence of FGL2 leads to a more activated TME, including activated DCs (CD86+, CD40+) and T cells (CD25+, TIGIT+), as well as demonstrating for the first time that the absence of FGL2 leads to more activated natural killer cells (DNAM-1+, NKG2D+) in the TME. Furthermore, the absence of FGL2 leads to prolonged survival in the B16F10 melanoma model, while the absence of FGL2 synergizes with oncolytic virus to prolong survival in the ID8-p53-/-Brca2-/- ovarian cancer model. In conclusion, targeting FGL2 is a promising cancer treatment strategy alone and in combination immunotherapies.

Cellular Components of the Tumor Environment in Gliomas-What Do We Know Today?

A generation ago, the molecular properties of tumor cells were the focus of scientific interest in oncology research. Since then, it has become increasingly apparent that the tumor environment (TEM), whose major components are non-neoplastic cell types, is also of utmost importance for our understanding of tumor growth, maintenance and resistance. In this review, we present the current knowledge concerning all cellular components within the TEM in gliomas, focusing on their molecular properties, expression patterns and influence on the biological behavior of gliomas. Insight into the TEM of gliomas has expanded considerably in recent years, including many aspects that previously received only marginal attention, such as the phenomenon of phagocytosis of glioma cells by macrophages and the role of the thyroid-stimulating hormone on glioma growth. We also discuss other topics such as the migration of lymphocytes into the tumor, phenotypic similarities between chemoresistant glioma cells and stem cells, and new clinical approaches with immunotherapies involving the cells of TEM.

Engineering of dendritic cell bispecific extracellular vesicles for tumor-targeting immunotherapy

Advances in the development of therapeutic extracellular vesicles (EVs) for cancer immunotherapy have allowed them to emerge as an alternative to cell therapy. In this proof-of-concept work, we develop bispecific EVs (BsEVs) by genetically engineering EV-producing dendritic cells (DCs) with aCD19 scFv and PD1 for targeting tumor antigens and blocking immune checkpoint proteins simultaneously. We find that these bispecific EVs (EVs-PD1-aCD19) have an impressive ability to accumulate in huCD19-expressing solid tumors following intravenous injection. In addition, EVs-PD1-aCD19 can remarkably reverse the immune landscape of the solid tumor by blocking PD-L1. Furthermore, EVs-PD1-aCD19 can also target tumor-derived EVs in circulation, which prevents the formation of a premetastatic niche in other tissues. Our technology is a demonstration of bispecific EV-based cancer immunotherapy, which may inspire treatments against various types of tumors with different surface antigens and even a patient-tailored therapy.

Proteomic analyses reveal cystatin c is a promising biomarker for evaluation of systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disease with multiple organ involvement, especially the kidneys. However, the underlying mechanism remains unclear, and accurate biomarkers are still lacking. This study aimed to identify biomarkers to assess organ damage and disease activity in patients with SLE using quantitative proteomics.

METHODS

Proteomic analysis was performed using mass spectrometry in 15 patients with SLE and 15 age-matched healthy controls. Proteomic profiles were compared in four main subtypes: SLE with proteinuria (SLE-PN), SLE without proteinuria (SLE-non-PN), SLE with anti-dsDNA positivity (SLE-DP), and SLE with anti-dsDNA negativity (SLE-non-DP). Gene ontology biological process analysis revealed differentially expressed protein networks. Cystatin C (CysC) levels were measured in 200 patients with SLE using an immunoturbidimetric assay. Clinical and laboratory data were collected to assess their correlation with serum CysC levels.

RESULTS

Proteomic analysis showed that upregulated proteins in both the SLE-PN and SLE-DP groups were mainly mapped to neutrophil activation networks. Moreover, CysC from neutrophil activation networks was upregulated in both the SLE-PN and SLE-DP groups. The associations of serum CysC level with proteinuria, anti-dsDNA positivity, lower complement C3 levels, and SLE disease activity index score in patients with SLE were further validated in a large independent cohort.

CONCLUSIONS

Neutrophil activation is more prominent in SLE with proteinuria and anti-dsDNA positivity, and CysC is a promising marker for monitoring organ damage and disease activity in SLE.

Dendritic cell vaccine of gliomas: challenges from bench to bed

Gliomas account for the majority of brain malignant tumors. As the most malignant subtype of glioma, glioblastoma (GBM) is barely effectively treated by traditional therapies (surgery combined with radiochemotherapy), resulting in poor prognosis. Meanwhile, due to its "cold tumor" phenotype, GBM fails to respond to multiple immunotherapies. As its capacity to prime T cell response, dendritic cells (DCs) are essential to anti-tumor immunity. In recent years, as a therapeutic method, dendritic cell vaccine (DCV) has been immensely developed. However, there have long been obstacles that limit the use of DCV yet to be tackled. As is shown in the following review, the role of DCs in anti-tumor immunity and the inhibitory effects of tumor microenvironment (TME) on DCs are described, the previous clinical trials of DCV in the treatment of GBM are summarized, and the challenges and possible development directions of DCV are analyzed.

The construction and validation of ECM-related prognosis model in laryngeal squamous cell carcinoma

Background

Laryngeal squamous cell carcinoma (LSCC) is a kind of common and aggressive tumor with high mortality. The application of molecular biomarkers is useful for the early diagnosis and treatment of LSCC.

Methods

The expression and clinical information were obtained from The Cancer Genome Atlas (TCGA) database. Principal components analysis (PCA) was used to discriminate between LSCC and normal samples. The hub genes were screened out through univariate and multivariate cox analyses. The Kaplan-Meier (K-M) and receiver operating characteristic (ROC) curve was used to validate the predictive performance. The single sample gene set enrichment analysis (ssGSEA), Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were used to determine the enrichment function. Protein-Protein Interaction (PPI) network was constructed in STRING. The immune analysis was performed by ESTIMATE, IPS and xCELL. The drug sensitivity was identified with GSCA database.

Results

We identified that 47 extracellular matrix (ECM) genes were differentially expressed in LSCC compared with normal group. Univariate and multivariate cox analysis determined that leucine-rich glioma-inactivated 4 (LGI4), matrilin 4 (MATN4), microfibrillar-associated protein 2 (MFAP2) and fibrinogen like 2 (FGL2) were closely related to the disease free survival (DSS) of LSCC. ROC curve determined that the risk model has a good predictive performance. PPI network showed the top 100 genes with high correlation of hub genes. The ssGSEA, GO and KEGG enrichment analyses determined that immune response was significantly involved in the development of LSCC. Immune infiltration analysis showed that most immune cells and immune checkpoints were inhibited in high risk score group. Drug sensitivity analysis showed that MATN4, FGL2 and LGI4 were negatively related to various drugs, while MFAP2 was positively related to many drugs.

Conclusion

We established a risk model constructed with four ECM-related genes, which could effectively predict the prognosis of LSCC.

A, Gota V, Goda JS. Insight into lipid-based nanoplatform-mediated drug and gene delivery in neuro-oncology and their clinical prospects

Tumors of the Central nervous System (CNS) are a spectrum of neoplasms that range from benign lesions to highly malignant and aggressive lesions. Despite aggressive multimodal treatment approaches, the morbidity and mortality are high with dismal survival outcomes in these malignant tumors. Moreover, the non-specificity of conventional treatments substantiates the rationale for precise therapeutic strategies that selectively target infiltrating tumor cells within the brain, and minimize systemic and collateral damage. With the recent advancement of nanoplatforms for biomaterials applications, lipid-based nanoparticulate systems present an attractive and breakthrough impact on CNS tumor management. Lipid nanoparticles centered immunotherapeutic agents treating malignant CNS tumors could convene the clear need for precise treatment strategies. Immunotherapeutic agents can selectively induce specific immune responses by active or innate immune responses at the local site within the brain. In this review, we discuss the therapeutic applications of lipid-based nanoplatforms for CNS tumors with an emphasis on revolutionary approaches in brain targeting, imaging, and drug and gene delivery with immunotherapy. Lipid-based nanoparticle platforms represent one of the most promising colloidal carriers for chemotherapeutic, and immunotherapeutic drugs. Their current application in oncology especially in brain tumors has brought about a paradigm shift in cancer treatment by improving the antitumor activity of several agents that could be used to selectively target brain tumors. Subsequently, the lab-to-clinic transformation and challenges towards translational feasibility of lipid-based nanoplatforms for drug and gene/immunotherapy delivery in the context of CNS tumor management is addressed.

Fibrinogen-like protein 2 in inflammatory diseases: A future therapeutic target

Fibrinogen-like protein 2 (FGL2), a member of the fibrinogen family, exists as a membrane-bound protein with immune-associated coagulation activity and a soluble form possessing immunosuppressive functions. The immunomodulatory role of FGL2 is evident in fibrin deposition-associated inflammatory diseases and cancer, suggesting that FGL2 expression could be exploited as a disease biomarker and a therapeutic target. Recently, in vitro studies and knockout and transgenic animal FGL2 models have been used by us and others to reveal the involvement of FGL2 in the pathogenesis of various inflammatory diseases. This review summarizes our current knowledge of the immunomodulatory role of FGL2 in inflammatory diseases and examines the role of FGL2 as a potential therapeutic target.

Immunotoxin-αCD40 therapy activates innate and adaptive immunity and generates a durable antitumor response in glioblastoma models

D2C7-immunotoxin (IT), a dual-specific IT targeting wild-type epidermal growth factor receptor (EGFR) and mutant EGFR variant III (EGFRvIII) proteins, demonstrates encouraging survival outcomes in a subset of patients with glioblastoma. We hypothesized that immunosuppression in glioblastoma limits D2C7-IT efficacy. To improve the response rate and reverse immunosuppression, we combined D2C7-IT tumor cell killing with αCD40 costimulation of antigen-presenting cells. In murine glioma models, a single intratumoral injection of D2C7-IT+αCD40 treatment activated a proinflammatory phenotype in microglia and macrophages, promoted long-term tumor-specific CD8+ T cell immunity, and generated cures. D2C7-IT+αCD40 treatment increased intratumoral Slamf6+CD8+ T cells with a progenitor phenotype and decreased terminally exhausted CD8+ T cells. D2C7-IT+αCD40 treatment stimulated intratumoral CD8+ T cell proliferation and generated cures in glioma-bearing mice despite FTY720-induced peripheral T cell sequestration. Tumor transcriptome profiling established CD40 up-regulation, pattern recognition receptor, cell senescence, and immune response pathway activation as the drivers of D2C7-IT+αCD40 antitumor responses. To determine potential translation, immunohistochemistry staining confirmed CD40 expression in human GBM tissue sections. These promising preclinical data allowed us to initiate a phase 1 study with D2C7-IT+αhCD40 in patients with malignant glioma (NCT04547777) to further evaluate this treatment in humans.

Fibrinogen-like protein 2: Its biological function across cell types and the potential to serve as an immunotherapy target for brain tumors

Brain tumors are among the 10 leading causes of cancer-related death and present unique treatment challenges due to their critical location, genetic heterogeneity, and the blood-brain barrier. Recent advances in targeted immunotherapy and immune checkpoint blocking therapy provide alternative therapeutic strategies for brain tumors. Fibrinogen-like protein 2 (FGL2), which induces transformation from low-grade glioma to high-grade glioblastoma, is a type II membrane protein that is highly expressed in both host immune cells and tumor cells. Studies have uncovered multiple forms of FGL2 proteins with a broad range of roles in inducing immune tolerance and avoiding immune surveillance in tumor cells. Of note, presence of FGL2 transforms low grade to high grade brain tumors via promoting Treg, macrophages, and perhaps stemness. Absence (knockout) of FGL2 in tumor cells (not in host cells) induces CD103 DC cells, which triggers tumor specific CD8 +T cell activity to reject brain tumor progression. Immunotherapies targeting FGL2 have shown great promise in improving survival time in murine models. In this article, we will summarize the biological function of FGL2 in immune and tumor cells.

The Conventional Dendritic Cell 1 Subset Primes CD8+ T Cells and Traffics Tumor Antigen to Drive Antitumor Immunity in the Brain

The central nervous system (CNS) antigen-presenting cell (APC) that primes antitumor CD8+ T-cell responses remains undefined. Elsewhere in the body, the conventional dendritic cell 1 (cDC1) performs this role. However, steady-state brain parenchyma cDC1 are extremely rare; cDCs localize to the choroid plexus and dura. Thus, whether the cDC1 play a function in presenting antigen derived from parenchymal sources in the tumor setting remains unknown. Using preclinical glioblastoma (GBM) models and cDC1-deficient mice, we explored the presently unknown role of cDC1 in CNS antitumor immunity. We determined that, in addition to infiltrating the brain tumor parenchyma itself, cDC1 prime neoantigen-specific CD8+ T cells against brain tumors and mediate checkpoint blockade-induced survival benefit. We observed that cDC, including cDC1, isolated from the tumor, the dura, and the CNS-draining cervical lymph nodes harbored a traceable fluorescent tumor antigen. In patient samples, we observed several APC subsets (including the CD141+ cDC1 equivalent) infiltrating glioblastomas, meningiomas, and dura. In these same APC subsets, we identified a tumor-specific fluorescent metabolite of 5-aminolevulinic acid, which fluorescently labeled tumor cells during fluorescence-guided GBM resection. Together, these data elucidate the specialized behavior of cDC1 and suggest that cDC1 play a significant role in CNS antitumor immunity.

Presence and activity of Fibrinogen like protein 2 in platelets

BACKGROUND

Fibrinogen-like protein 2 (FGL2) is a serine protease capable of converting prothrombin into thrombin (i.e., prothrombinase-like activity) while bypassing the classic coagulation cascade. It has been reported to be expressed by mononuclear blood cells and endothelial cells. There are multiple reports that FGL2 supports tumor development and metastasis. However, in the blood, the origin and functional significance of FGL2 has not been established.

OBJECTIVE

To determine if FGL2, a malignancy related enzyme, is present in platelets.

METHODS

Peripheral blood samples were collected in K2 EDTA tubes. Blood cells and platelets were separated and thoroughly washed to produce plasma-free samples. Procoagulant activity was measured in the cell lysates using a thrombin generation test or an adjusted prothrombin time (PT) test in plasma deficient of factor X. The findings were further supported by confocal microscopy, immunoprecipitation, flow cytometry, enzyme-linked immunosorbent assays and specific inhibition assays.

RESULTS

FGL2 protein was readily detected in platelets. Also, despite being expressed by lymphocytes, FGL2 prothrombinase-like activity was solely detected in platelet samples, but not in white blood cell samples. Quiescent platelets were shown to contain the FGL2 protein in an active form. Upon activation, platelets secreted the active FGL2 into the milieu.

CONCLUSIONS

Active FGL2 is found in platelets. This suggests another role for the involvement of platelets in malignancies.

Targeting FGL2 in glioma immunosuppression and malignant progression

Glioblastoma (GBM) is the most malignant type of glioma with the worst prognosis. Traditional therapies (surgery combined with radiotherapy and chemotherapy) have limited therapeutic effects. As a novel therapy emerging in recent years, immunotherapy is increasingly used in glioblastoma (GBM), so we expect to discover more effective immune targets. FGL2, a member of the thrombospondin family, plays an essential role in regulating the activity of immune cells and tumor cells in GBM. Elucidating the role of FGL2 in GBM can help improve immunotherapy efficacy and design treatment protocols. This review discusses the immunosuppressive role of FGL2 in the GBM tumor microenvironment and its ability to promote malignant tumor progression while considering FGL2-targeted therapeutic strategies. Also, we summarize the molecular mechanisms of FGL2 expression on various immune cell types and discuss the possibility of FGL2 and its related mechanisms as new GBM immunotherapy.

A microfluidics-based method for isolation and visualization of cells based on receptor-ligand interactions

Receptor-ligand binding has been analyzed at the protein level using isothermal titration calorimetry and surface plasmon resonance and at the cellular level using interaction-associated downstream gene induction/suppression. However, no currently available technique can characterize this interaction directly through visualization. In addition, all available assays require a large pool of cells; no assay capable of analyzing receptor-ligand interactions at the single-cell level is publicly available. Here, we describe a new microfluidic chip-based technique for analyzing and visualizing these interactions at the single-cell level. First, a protein is immobilized on a glass slide and a low-flow-rate pump is used to isolate cells that express receptors that bind to the immobilized ligand. Specifically, we demonstrate the efficacy of this technique by immobilizing biotin-conjugated FGL2 on an avidin-coated slide chip and passing a mixture of GFP-labeled wild-type T cells and RFP-labeled FcγRIIB-knockout T cells through the chip. Using automated scanning and counting, we found a large number of GFP+ T cells with binding activity but significantly fewer RFP+ FcγRIIB-knockout T cells. We further isolated T cells expressing a membrane-anchored, tumor-targeted IL-12 based on the receptor's affinity to vimentin to confirm the versatility of our technique. This protocol allows researchers to isolate receptor-expressing cells in about 4 hours for further downstream processing.

Neuroinflammation: Extinguishing a blaze of T cells

Inflammation is a biological process that dynamically alters the surrounding microenvironment, including participating immune cells. As a well-protected organ surrounded by specialized barriers and with immune privilege properties, the central nervous system (CNS) tightly regulates immune responses. Yet in neuroinflammatory conditions, pathogenic immunity can disrupt CNS structure and function. T cells in particular play a key role in promoting and restricting neuroinflammatory responses, while the inflamed CNS microenvironment can influence and reshape T cell function and identity. Still, the contraction of aberrant T cell responses within the CNS is not well understood. Using autoimmunity as a model, here we address the contribution of CD4 T helper (Th) cell subsets in promoting neuropathology and disease. To address the mechanisms antagonizing neuroinflammation, we focus on the control of the immune response by regulatory T cells (Tregs) and describe the counteracting processes that preserve their identity under inflammatory challenges. Finally, given the influence of the local microenvironment on immune regulation, we address how CNS-intrinsic signals reshape T cell function to mitigate abnormal immune T cell responses.

Gene expression analysis during progression of malignant meningioma compared to benign meningioma

OBJECTIVE

Meningioma is the most common primary intracranial neoplasm. Only 1%-3% of meningiomas are malignant according to the 2016 WHO criteria (WHO grade III). High-grade meningiomas present specific gene expression signatures indicating aggressive growth or recurrence. However, changes in gene expression and in neuroinflammatory gene expression signatures in WHO grade III meningiomas and during progression from WHO grade I or II to grade III are unknown.

METHODS

The authors used a NanoString targeted gene expression panel with focus on 787 genes relevant in meningioma pathology and neuroinflammatory pathways to investigate patients with grade III meningiomas treated at Rigshospitalet from 2000 to 2020 (n = 51). A temporal dimension was added to the investigation by including samples from patients' earlier grade I and II meningiomas and grade III recurrences (n = 139 meningiomas). The authors investigated changes in neuroinflammatory gene expression signatures in 1) grade I meningiomas that later transformed into grade III meningiomas, and 2) grade III meningiomas compared with nonrecurrent grade I meningiomas.

RESULTS

The authors' data indicate that FOXM1, TOP2A, BIRC5, and MYBL2 were enriched and the HOTAIR regulatory pathway was enriched in grade III meningiomas compared with nonrecurrent grade I meningiomas. They discovered a separation of malignant and benign meningiomas based only on genes involved in microglia regulation with enrichment of P2RY12 in grade I compared with grade III meningiomas. Interestingly, FOXM1 was upregulated in premalignant grade I meningioma years before the grade III transformation.

CONCLUSIONS

The authors found gene expression changes in low-grade meningiomas that predated histological transformation to grade III meningiomas. Neuroinflammation genes distinguished grade III from grade I meningiomas.

The Interplay of Tumor Vessels and Immune Cells Affects Immunotherapy of Glioblastoma

Immunotherapies with immune checkpoint inhibitors or adoptive cell transfer have become powerful tools to treat cancer. These treatments act via overcoming or alleviating tumor-induced immunosuppression, thereby enabling effective tumor clearance. Glioblastoma (GBM) represents the most aggressive, primary brain tumor that remains refractory to the benefits of immunotherapy. The immunosuppressive immune tumor microenvironment (TME), genetic and cellular heterogeneity, and disorganized vasculature hinder drug delivery and block effector immune cell trafficking and activation, consequently rendering immunotherapy ineffective. Within the TME, the mutual interactions between tumor, immune and endothelial cells result in the generation of positive feedback loops, which intensify immunosuppression and support tumor progression. We focus here on the role of aberrant tumor vasculature and how it can mediate hypoxia and immunosuppression. We discuss how immune cells use immunosuppressive signaling for tumor progression and contribute to the development of resistance to immunotherapy. Finally, we assess how a positive feedback loop between vascular normalization and immune cells, including myeloid cells, could be targeted by combinatorial therapies with immune checkpoint blockers and sensitize the tumor to immunotherapy.

Translational landscape of glioblastoma immunotherapy for physicians: guiding clinical practice with basic scientific evidence

Despite recent advances in cancer therapeutics, glioblastoma (GBM) remains one of the most difficult cancers to treat in both the primary and recurrent settings. GBM presents a unique therapeutic challenge given the immune-privileged environment of the brain and the aggressive nature of the disease. Furthermore, it can change phenotypes throughout the course of disease—switching between mesenchymal, neural, and classic gene signatures, each with specific markers and mechanisms of resistance. Recent advancements in the field of immunotherapy—which utilizes strategies to reenergize or alter the immune system to target cancer—have shown striking results in patients with many types of malignancy. Immune checkpoint inhibitors, adoptive cellular therapy, cellular and peptide vaccines, and other technologies provide clinicians with a vast array of tools to design highly individualized treatment and potential for combination strategies. There are currently over 80 active clinical trials evaluating immunotherapies for GBM, often in combination with standard secondary treatment options including re-resection and anti-angiogenic agents, such as bevacizumab. This review will provide a clinically focused overview of the immune environment present in GBM, which is frequently immunosuppressive and characterized by M2 macrophages, T cell exhaustion, enhanced transforming growth factor-β signaling, and others. We will also outline existing immunotherapeutic strategies, with a special focus on immune checkpoint inhibitors, chimeric antigen receptor therapy, and dendritic cell vaccines. Finally, we will summarize key discoveries in the field and discuss currently active clinical trials, including combination strategies, burgeoning technology like nucleic acid and nanoparticle therapy, and novel anticancer vaccines. This review aims to provide the most updated summary of the field of immunotherapy for GBM and offer both historical perspective and future directions to help inform clinical practice.

[18F]BIBD-239: 18F-Labeled ER176, a Positron Emission Tomography Tracer Specific for the Translocator Protein

[¹¹C]ER176 has adequate sensitivity to image the human brain translocator protein (TSPO) in all three genotypes by positron emission tomography (PET). However, its clinical application is limited by the short half-life of ¹¹C (20.38 min). To overcome the deficiency of [¹¹C]ER176 and keep the pharmacophore features of ER176 to the maximum extent, we designed four fluorine-labeled ER176 derivatives using the deuterium method. In vitro competition binding confirmed that the designed compounds had high affinity for TSPO. Biodistribution experiments showed that tissues with high expression of TSPO had high uptake of these compounds, as well as that the compound showed high brain penetration and mild defluorination in vivo. Therefore, [¹⁸F]BIBD-239 with simple synthesis conditions was selected for further biological evaluation. Theoretical simulations showed that BIBD-239 and ER176 have similar binding modes and sites to Ala147-TSPO and Thr147-TSPO, which indicated that the tracers may have consistent sensitivity to the three affinity genotypes. In vitro autoradiography and in vivo PET studies of the ischemic rat brain showed dramatically higher uptake of [¹⁸F]BIBD-239 on the lesion site compared to the contralateral side with good brain kinetics. Additionally, [¹⁸F]BIBD-239 provided clear tumor PET images in a GL261 glioma model. Importantly, PET imaging and liquid chromatography-high-resolution mass spectrometry (LC-HRMS) results showed that in vivo defluorination and other metabolites of [¹⁸F]BIBD-239 did not interfere with brain imaging. Conclusively, [¹⁸F]BIBD-239, similar to ER176 with low polymorphism sensitivity, has simple labeling conditions, high labeling yield, high affinity, and high specificity for TSPO, and it is planned for further evaluation in higher species.

Meningeal lymphatics regulate radiotherapy efficacy through modulating anti-tumor immunity

As a first-line treatment, radiotherapy (RT) is known to modulate the immune microenvironment of glioma, but it is unknown whether the meningeal lymphatic vessel (MLV)-cervical lymph node (CLN) network regulates the process or influences RT efficacy. Here, we show that the MLV-CLN network contributes to RT efficacy in brain tumors and mediates the RT-modulated anti-tumor immunity that is enhanced by vascular endothelial growth factor C (VEGF-C). Meningeal lymphatic dysfunction impaired tumor-derived dendritic cell (DC) trafficking and CD8⁺ T cell activation after RT, whereas tumors overexpressing VEGF-C with meningeal lymphatic expansion were highly sensitive to RT. Mechanistically, VEGF-C-driven modulation of RT-triggered anti-tumor immunity was attributed to C-C Motif Chemokine Ligand 21 (CCL21)-dependent DC trafficking and CD8⁺ T cell activation. Notably, delivery of VEGF-C mRNA significantly enhanced RT efficacy and anti-tumor immunity in brain tumors. These findings suggest an essential role of the MLV-CLN network in RT-triggered anti-tumor immunity, and highlight the potential of VEGF-C mRNA for brain tumor therapy.

Friends with Benefits: Chemokines, Glioblastoma-Associated Microglia/Macrophages, and Tumor Microenvironment

Glioma is the most common primary intracranial tumor and has the greatest prevalence of all brain tumors. Treatment resistance and tumor recurrence in GBM are mostly explained by considerable alterations within the tumor microenvironment, as well as extraordinary cellular and molecular heterogeneity. Soluble factors, extracellular matrix components, tissue-resident cell types, resident or newly recruited immune cells together make up the GBM microenvironment. Regardless of many immune cells, a profound state of tumor immunosuppression is supported and developed, posing a considerable hurdle to cancer cells' immune-mediated destruction. Several studies have suggested that various GBM subtypes present different modifications in their microenvironment, although the importance of the microenvironment in treatment response has yet to be determined. Understanding the microenvironment and how it changes after therapies is critical because it can influence the remaining invasive GSCs and lead to recurrence. This review article sheds light on the various components of the GBM microenvironment and their roles in tumoral development, as well as immune-related biological processes that support the interconnection/interrelationship between different cell types. Also, we summarize the current understanding of the modulation of soluble factors and highlight the dysregulated inflammatory chemokine/specific receptors cascades/networks and their significance in tumorigenesis, cancer-related inflammation, and metastasis.

Targeting cancer-associated fibroblast-secreted WNT2 restores dendritic cell-mediated antitumour immunity

OBJECTIVE

Solid tumours respond poorly to immune checkpoint inhibitor (ICI) therapies. One major therapeutic obstacle is the immunosuppressive tumour microenvironment (TME). Cancer-associated fibroblasts (CAFs) are a key component of the TME and negatively regulate antitumour T-cell response. Here, we aimed to uncover the mechanism underlying CAFs-mediated tumour immune evasion and to develop novel therapeutic strategies targeting CAFs for enhancing ICI efficacy in oesophageal squamous cell carcinoma (OSCC) and colorectal cancer (CRC).

DESIGN

Anti-WNT2 monoclonal antibody (mAb) was used to treat immunocompetent C57BL/6 mice bearing subcutaneously grafted mEC25 or CMT93 alone or combined with anti-programmed cell death protein 1 (PD-1), and the antitumour efficiency and immune response were assessed. CAFs-induced suppression of dendritic cell (DC)-differentiation and DC-mediated antitumour immunity were analysed by interfering with CAFs-derived WNT2, either by anti-WNT2 mAb or with short hairpin RNA-mediated knockdown. The molecular mechanism underlying CAFs-induced DC suppression was further explored by RNA-sequencing and western blot analyses.

RESULTS

A negative correlation between WNT2⁺ CAFs and active CD8⁺ T cells was detected in primary OSCC tumours. Anti-WNT2 mAb significantly restored antitumour T-cell responses within tumours and enhanced the efficacy of anti-PD-1 by increasing active DC in both mouse OSCC and CRC syngeneic tumour models. Directly interfering with CAFs-derived WNT2 restored DC differentiation and DC-mediated antitumour T-cell responses. Mechanistic analyses further demonstrated that CAFs-secreted WNT2 suppresses the DC-mediated antitumour T-cell response via the SOCS3/p-JAK2/p-STAT3 signalling cascades.

CONCLUSIONS

CAFs could suppress antitumour immunity through WNT2 secretion. Targeting WNT2 might enhance the ICI efficacy and represent a new anticancer immunotherapy.

Fibrinogen-like protein 2 in gastrointestinal stromal tumour

Gastrointestinal stromal tumour (GIST), the most common sarcoma of the gastrointestinal tract, can be treated effectively with tyrosine kinase inhibitors, such as imatinib. Cancer immune therapy has limited efficacy, and little is known about the immune suppressive factors in GISTs. Fibrinogen‐like protein 2 (FGL2) is expressed either as a membrane‐associated protein or as a secreted soluble protein that has immune suppressive functions. We found that GISTs expressed FGL2 mRNA highly compared to other types of cancer in a large human cancer transcriptome database. GIST expressed FGL2 frequently also when studied using immunohistochemistry in two large clinical series, where 333 (78%) out of the 425 GISTs were FGL2 positive. The interstitial cells of Cajal, from which GISTs may originate, expressed FGL2. FGL2 expression was associated with small GIST size, low mitotic counts and low tumour‐infiltrating lymphocyte (TIL) counts. Patients whose GIST expressed FGL2 had better recurrence‐free survival than patients whose GIST lacked expression. Imatinib upregulated FGL2 in GIST cell lines, and the patients with FGL2‐negative GIST appeared to benefit most from long duration of adjuvant imatinib. We conclude that GISTs express FGL2 frequently and that FGL2 expression is associated with low TIL counts and favourable survival outcomes.

The Fgl2 interaction with Tyrobp promotes the proliferation of cutaneous squamous cell carcinoma by regulating ERK-dependent autophagy

Human fibroleukin 2 (Fgl2), a member of the fibrinogen superfamily, can cleave prothrombin to generate thrombin or is secreted in a soluble form as a new type of effector of Tregs with immunomodulatory functions. However, there is little research on the role of Fgl2 in cutaneous squamous cell carcinoma (CSCC) growth. We examined the expression of Fgl2 in samples from CSCC patients and CSCC cell lines. Then, the effect of Fgl2 on CSCC was evaluated in vitro and in animals. Regulation of autophagy by Fgl2 was explored in CSCC. Coimmunoprecipitation (Co-IP) and immunofluorescence colocalization experiments were conducted to identify the regulatory effect of Fgl2 on the downstream protein Tyrobp. Then, gain- or loss-of-function analyses and evaluation of Tyrobp expression were performed to validate its role in autophagy and proliferation promoted by Fgl2. Here, our study demonstrated that Fgl2 promoted the proliferation of CSCC cells in vitro and in vivo. Knocking down Fgl2 reduced CSCC cell proliferation and inhibited autophagy in CSCC. Mechanistically, Fgl2 interacted with Tyrobp and promoted ERK-dependent autophagy, resulting in the proliferation of CSCC cells. Our study suggested that Fgl2 could be a promising prognostic biomarker and useful therapeutic target for CSCC.

Mesenchymal Stem Cell-Derived Extracellular Vesicles with High PD-L1 Expression for Autoimmune Diseases Treatment

Autoimmune diseases are the third most common disease influencing the quality of life of many patients. Here, a programmed cell death-ligand 1 + (PD-L1) mesenchymal stem cell (MSC) derived extracellular vesicles (MSC-sEVs-PD-L1) using lentivirus-mediated gene transfection technology is developed for reconfiguration of the local immune microenvironment of affected tissue in autoimmune diseases. MSC-sEVs-PD-L1 exhibits an impressive ability to regulate various activated immune cells to an immunosuppressed state in vitro. More importantly, in dextran sulfate sodium-induced ulcerative colitis (UC) and imiquimod-induced psoriasis mouse models, a significantly high accumulation of MSC-sEVs-PD-L1 is observed in the inflamed tissues compared to the PD-L1+ MSCs. Therapeutic efficiency in both UC and psoriasis mouse disease models is demonstrated using MSC-sEVs-PD-L1 to reshape the inflammatory ecosystem in the local immune context. A technology is developed using MSC-sEVs-PD-L1 as a natural delivery platform for autoimmune diseases treatment with high clinical potential.

The Systematic Landscape of Nectin Family and Nectin-Like Molecules: Functions and Prognostic Value in Low Grade Glioma

Objective: Nectin and nectin-like molecules (Necls) are molecules that are involved in cell–cell adhesion and other vital cellular processes. This study aimed to determine the expression and prognostic value of nectin and Necls in low grade glioma (LGG).

Materials and Methods: Differentially expressed nectin and Necls in LGG samples and the relationship of nectin family and Necls expression with prognosis, clinicopathological parameters, and survival were explored using The Cancer Genome Atlas (TCGA), the Chinese Glioma Genome Atlas (CGGA), and Repository of Molecular Brain Neoplasia Data (REMBRANDT) databases. Univariate and multivariate Cox analysis models were performed to construct the prognosis-related gene signature. Kaplan-Meier curves and time-dependent receiver operating characteristic (ROC) curves and multivariate Cox regression analysis, were utilized to evaluate the prognostic capacity of the four-gene signature. Gene ontology (GO)enrichment analysis and Gene Set Enrichment Analyses (GSEA) were performed to further understand the underlying molecular mechanisms. The Tumor Immune Estimation Resource (TIMER) was used to explore the relationship between the four-gene signature and tumor immune infiltration.

Results: Several nectin and Necls were differentially expressed in LGG. Kaplan–Meier survival analyses and Univariate Cox regression showed patients with high expression of NECTIN2 and PVR and low expression of CADM2 and NECTIN1 had worse prognosis among TCGA, CGGA, and REMBRANDT database. Then, a novel four-gene signature was built for LGG prognosis prediction. ROC curves, KM survival analyses, and multivariate COX regression indicated the new signature was an independent prognostic indicator for overall survival. Finally, GSEA and GO enrichment analyses revealed that immune-related pathways participate in the molecular mechanisms. The risk score had a strong negative correlation with tumor purity and data of TIMER showed different immune cell proportions (macrophage and myeloid dendritic cell) between high- and low-risk groups. Additionally, signature scores were positively related to multiple immune-related biomarkers (IL 2, IL8 and IFNγ).

Conclusion: Our results offer an extensive analysis of nectin and Necls levels and a four-gene model for prognostic prediction in LGG, providing insights for further investigation of CADM2, NECTIN1/2, and PVR as potential clinical and immune targets in LGG.

Glial and myeloid heterogeneity in the brain tumour microenvironment

Brain cancers carry bleak prognoses, with therapeutic advances helping only a minority of patients over the past decade. The brain tumour microenvironment (TME) is highly immunosuppressive and differs from that of other malignancies as a result of the glial, neural and immune cell populations that constitute it. Until recently, the study of the brain TME was limited by the lack of methods to de-convolute this complex system at the single-cell level. However, novel technical approaches have begun to reveal the immunosuppressive and tumour-promoting properties of distinct glial and myeloid cell populations in the TME, identifying new therapeutic opportunities. Here, we discuss the immune modulatory functions of microglia, monocyte-derived macrophages and astrocytes in brain metastases and glioma, highlighting their disease-associated heterogeneity and drawing from the insights gained by studying these malignancies and other neurological disorders. Lastly, we consider potential approaches for the therapeutic modulation of the brain TME.

Identification of ITPR1 as a Hub Gene of Group 3 Medulloblastoma and Coregulated Genes with Potential Prognostic Values

The Group 3 Medulloblastoma (Grp3-MB) is an aggressive molecular subtype with a high incidence of metastasis and deaths. In this study, were used an RNA sequencing data (RNA-Seq) from a Brazilian cohort of MBs to identify hub genes associated with the metastatic risk. Data validation were performed by using multiple large datasets from MBs (GSE85217, GSE37418, and EGAS00001001953). DESeq2 package in R software was used to identify the differentially expressed genes (DEGs) in our RNA-Seq data. The DEGs data were accessed to construct the modules/graphs of co-expression and to identify hub genes through Cytoscape platform. The coregulated genes were enriched by the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and the protein-protein interaction (PPI) network was visualized by Cytoscape. The Kaplan-Meier plotter and ROC curves were used to validate the diagnostic and prognostic values of specific biomarkers identified through this model. We identified that inositol 1,4,5-trisphosphate receptor type 1 (ITPR1) as a downregulated hub gene, with a high diagnostic accuracy to Grp3-MBs and associated with tumor metastasis. In addition, we identified genes significantly correlated with ITPR1 that were associated with metastasis in Grp3-MB (ATP1A2, MTTL7A, and RGL1) and worst overall survival in MBs (ANTXR1 and RGL1). Our findings suggest that the ITPR1 hub gene is potentially involved in the metastatic process for Grp3-MB. Our data also provide evidence of targets that may serve as prognostic predictors and/or regulators for the metastatic process that maybe explored for further research of individualized therapy to Grp3-MBs.

Tertiary Lymphoid Structures in the Central Nervous System: Implications for Glioblastoma

Glioblastoma is the most common and aggressive brain tumor, which is uniformly lethal due to its extreme invasiveness and the absence of curative therapies. Immune checkpoint inhibitors have not yet proven efficacious for glioblastoma patients, due in part to the low prevalence of tumor-reactive T cells within the tumor microenvironment. The priming of tumor antigen-directed T cells in the cervical lymph nodes is complicated by the shortage of dendritic cells and lack of appropriate lymphatic vessels within the brain parenchyma. However, recent data suggest that naive T cells may also be primed within brain tumor-associated tertiary lymphoid structures. Here, we review the current understanding of the formation of these structures within the central nervous system, and hypothesize that promotion of tertiary lymphoid structures could enhance priming of tumor antigen-targeted T cells and sensitize glioblastomas to cancer immunotherapy.