Targeting Tyro3, Axl and MerTK (TAM receptors): implications for macrophages in the tumor microenvironment

Mutual regulation of microglia and astrocytes after Gas6 inhibits spinal cord injury

JOURNAL/nrgr/04.03/01300535-202502000-00032/figure1/v/2024-05-28T214302Z/r/image-tiff Invasive inflammation and excessive scar formation are the main reasons for the difficulty in repairing nervous tissue after spinal cord injury. Microglia and astrocytes play key roles in the spinal cord injury micro-environment and share a close interaction. However, the mechanisms involved remain unclear. In this study, we found that after spinal cord injury, resting microglia (M0) were polarized into pro-inflammatory phenotypes (MG1 and MG3), while resting astrocytes were polarized into reactive and scar-forming phenotypes. The expression of growth arrest-specific 6 (Gas6) and its receptor Axl were significantly down-regulated in microglia and astrocytes after spinal cord injury. In vitro experiments showed that Gas6 had negative effects on the polarization of reactive astrocytes and pro-inflammatory microglia, and even inhibited the cross-regulation between them. We further demonstrated that Gas6 can inhibit the polarization of reactive astrocytes by suppressing the activation of the Yes-associated protein signaling pathway. This, in turn, inhibited the polarization of pro-inflammatory microglia by suppressing the activation of the nuclear factor-κB/p65 and Janus kinase/signal transducer and activator of transcription signaling pathways. In vivo experiments showed that Gas6 inhibited the polarization of pro-inflammatory microglia and reactive astrocytes in the injured spinal cord, thereby promoting tissue repair and motor function recovery. Overall, Gas6 may play a role in the treatment of spinal cord injury. It can inhibit the inflammatory pathway of microglia and polarization of astrocytes, attenuate the interaction between microglia and astrocytes in the inflammatory microenvironment, and thereby alleviate local inflammation and reduce scar formation in the spinal cord.

The interplay between the tumor microenvironment and tumor-derived small extracellular vesicles in cancer development and therapeutic response

The tumor microenvironment (TME) plays an essential role in tumor cell survival by profoundly influencing their proliferation, metastasis, immune evasion, and resistance to treatment. Extracellular vesicles (EVs) are small particles released by all cell types and often reflect the state of their parental cells and modulate other cells' functions through the various cargo they transport. Tumor-derived small EVs (TDSEVs) can transport specific proteins, nucleic acids and lipids tailored to propagate tumor signals and establish a favorable TME. Thus, the TME's biological characteristics can affect TDSEV heterogeneity, and this interplay can amplify tumor growth, dissemination, and resistance to therapy. This review discusses the interplay between TME and TDSEVs based on their biological characteristics and summarizes strategies for targeting cancer cells. Additionally, it reviews the current issues and challenges in this field to offer fresh insights into comprehending tumor development mechanisms and exploring innovative clinical applications.

Immunostimulatory CKb11 gene combined with immune checkpoint PD-1/PD-L1 blockade activates immune response and simultaneously overcomes the immunosuppression of cancer

Immunosuppression tumor microenvironment (TME) seriously impedes anti-tumor immune response, resulting in poor immunotherapy effect of cancer. This study develops a folate-modified delivery system to transport the plasmids encoding immune stimulatory chemokine CKb11 and PD-L1 inhibitors to tumor cells, resulting in high CKb11 secretion from tumor cells, successfully activating immune cells and increasing cytokine secretion to reshape the TME, and ultimately delaying tumor progression. The chemokine CKb11 enhances the effectiveness of tumor immunotherapy by increasing the infiltration of immune cells in TME. It can cause high expression of IFN-γ, which is a double-edged sword that inhibits tumor growth while causing an increase in the expression of PD-L1 on tumor cells. Therefore, combining CKb11 with PD-L1 inhibitors can counterbalance the suppressive impact of PD-L1 on anti-cancer defense, leading to a collaborative anti-tumor outcome. Thus, utilizing nanotechnology to achieve targeted delivery of immune stimulatory chemokines and immune checkpoint inhibitors to tumor sites, thereby reshaping immunosuppressive TME for cancer treatment, has great potential as an immunogene therapy in clinical applications.

Gas6-Axl signal promotes indoor VOCs exposure-induced pulmonary fibrosis via pulmonary microvascular endothelial cells-fibroblasts cross-talk

Volatile organic compounds (VOCs) as environmental pollutants were associated with respiratory diseases. Pulmonary fibrosis (PF) was characterized by an increase of extracellular matrix, leading to deterioration of lung function. The adverse effects on lung and the potential mechanism underlying VOCs induced PF had not been elucidated clearly. In this study, the indoor VOCs exposure mouse model along with an ex vivo biosensor assay was established. Based on scRNA-seq analysis, the adverse effects on lung and potential molecular mechanism were studied. Herein, the results showed that VOCs exposure from indoor decoration contributed to decreased lung function and facilitated pulmonary fibrosis in mice. Then, the whole lung cell atlas after VOCs exposure and the heterogeneity of fibroblasts were revealed. We explored the molecular interactions among various pulmonary cells, suggesting that endothelial cells contributed to fibroblasts activation in response to VOCs exposure. Mechanistically, pulmonary microvascular endothelial cells (MPVECs) secreted Gas6 after VOCs-induced PANoptosis phenotype, bound to the Axl in fibroblasts, and then activated fibroblasts. Moreover, Atf3 as the key gene negatively regulated PANoptosis phenotype to ameliorate fibrosis induced by VOCs exposure. These novel findings provided a new perspective about MPVECs could serve as the initiating factor of PF induced by VOCs exposure.

EDIL3/Del-1 prevents aortic dissection through enhancing internalization and degradation of apoptotic vascular smooth muscle cells

Thoracic aortic dissection (TAD) is a severe disease, characterized by numerous apoptotic vascular smooth muscle cells (VSMCs). EDIL3/Del-1 is a secreted protein involved in macrophage efferocytosis in acute inflammation. Here, we aimed to investigate whether EDIL3 promoted the internalization and degradation of apoptotic VSMCs during TAD. The levels of EDIL3 were decreased in the serum and aortic tissue from TAD mice. Global edil3 knockout (edil3-/-) mice and edil3-/- bone marrow chimeric mice exhibited a considerable exacerbation in β-aminopropionitrile monofumarate (BAPN)-induced TAD, accompanied with increased apoptotic VSMCs accumulating in the damaged aortic tissue. Two types of phagocytes, RAW264.7 cells and bone marrow-derived macrophages (BMDMs) were used for in vitro efferocytosis assay. edil3-deficient phagocytes exhibited inefficient internalization and degradation of apoptotic VSMCs. Instead, EDIL3 promoted the internalization phase through interacting with phosphatidylserine (PtdSer) on apoptotic VSMCs and binding to the macrophage ITGAV/αv-ITGB3/β3 integrin. In addition, EDIL3 accelerated the degradation phase through activating LC3-associated phagocytosis (LAP). Mechanically, following the engulfment, EDIL3 enhanced the activity of SMPD1/acid sphingomyelinase in the phagosome through blocking ITGAV-ITGB3 integrin, which facilitates phagosomal reactive oxygen species (ROS) production by NAPDH oxidase CYBB/NOX2. Furthermore, exogenous EDIL3 supplementation alleviated BAPN-induced TAD and promoted apoptotic cell clearance. EDIL3 may be a novel factor for the prevention and treatment of TAD.Abbreviations: BAPN: β-aminopropionitrile monofumarate; BMDM: bone marrow-derived macrophage; C12FDG: 5-dodecanoylaminofluorescein-di-β-D-galactopyranoside; CTRL: control; CYBB/NOX2: cytochrome b-245, beta polypeptide; DCFH-DA: 2',7'-dichlorofluorescin diacetate; EDIL3/Del-1: EGF-like repeats and discoidin I-like domains 3; EdU: 5-ethynyl-2'-deoxyuridine; EVG: elastic van Gieson; H&E: hematoxylin and eosin; IL: interleukin; LAP: LC3-associated phagocytosis; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; NAC: N-acetylcysteine; PtdSer: phosphatidylserine; rEDIL3: recombinant EDIL3; ROS: reactive oxygen species; SMPD1: sphingomyelin phosphodiesterase 1; TAD: thoracic aortic dissection; TEM: transmission electron microscopy; VSMC: vascular smooth muscle cell; WT: wild-type.

Dysregulated inflammatory response to urogynecologic meshes in women with diabetes and its implications

BACKGROUND

Diabetes is an independent risk factor for mesh complications in women undergoing mesh-augmented surgical repairs of stress urinary incontinence and/or pelvic organ prolapse. The underlying mechanism remains unclear.

OBJECTIVE

This study aimed to define the diabetes-associated alterations in the host inflammatory response to mesh and correlate them with perioperative glucose management.

STUDY DESIGN

Deidentified demographics and medical records of patients who underwent mesh removal and participated in a mesh biorepository study were reviewed (n=200). In patients with diagnosed diabetes (n=25), blood glucose management before initial mesh implantation and before and after mesh removal was assessed by blood glucose and hemoglobin A1c levels. Age- and body mass index-matched tissue samples excised from patients with and without diabetes were examined. Transcriptomic profiles of immune cell markers, immune mediators, key inflammatory regulators, cell senescence, and epigenetic enzymes were determined by multiplex transcriptomic assays (NanoString). Ratios of apoptotic cells to CD68+ macrophages were examined with immunofluorescence. Protein profiles of 12 molecules involved in apoptotic cell clearance were examined with a multiplex protein assay (Luminex).

RESULTS

Demographic and clinical characteristics, including duration between mesh implantation and removal, reason for removal, and type of mesh, etc., were comparable between patients with and without diabetes, except for 11.6% higher body mass index in the former (P=.005). In patients with diabetes, suboptimal management of blood glucose following mesh implantation was observed, with 59% of the patients having loosely or poorly controlled glucose before and after the mesh removal. Ongoing chronic inflammatory response was observed in the excised mesh-tissue complexes in both groups, whereas markers for M2 macrophages (Mrc1 [mannose receptor C-type 1]) and helper T cells (Cd4 [CD4 molecule]) were increasingly expressed in the diabetic vs nondiabetic group (P=.023 and .047, respectively). Furthermore, the gene expressions of proinflammatory Ccl24 (C-C motif chemokine ligand 24) and Ccl13 (C-C motif chemokine ligand 13) were upregulated by 1.5- and 1.8-fold (P=.035 and .027, respectively), whereas that of Il1a (interleukin 1 alpha) was paradoxically downregulated by 2.2-fold (P=.037) in the diabetic vs nondiabetic group. Interestingly, strong positive correlations were found between the expression of Ccl13, Setdb2 (SET domain bifurcated histone lysine methyltransferase 2), and M2 macrophage markers, and between the expression of Il1a, Fosl1 (activator protein-1 transcription factor subunit), and dendritic cell markers, suggesting the involvement of macrophages and dendritic cells in the diabetes-dysregulated proinflammatory response. Supportively, apoptotic cell clearance, which is an important function of macrophages, appeared to be impaired in the diabetic group, with a significantly increased protein level of CALR (calreticulin), an "eat-me" signal on the surface of apoptotic cells (P=.031), along with an increase of AXL (AXL receptor tyrosine kinase) (P=.030), which mediates apoptotic cell clearance.

CONCLUSION

Diabetes was associated with altered long-term inflammatory response in complicated mesh implantation, particularly involving innate immune cell dysfunction. Suboptimal blood glycemic control following mesh implantation may contribute to this immune dysregulation, necessitating further mechanistic studies.

Discovery of Dual MER/AXL Kinase Inhibitors as Bifunctional Small Molecules for Inhibiting Tumor Growth and Enhancing Tumor Immune Microenvironment

A series of bifunctional compounds have been discovered for their dual functionality as MER/AXL inhibitors and immune modulators. The furanopyrimidine scaffold, renowned for its suitability in kinase inhibitor discovery, offers at least three distinct pharmacophore access points. Insights from molecular modeling studies guided hit-to-lead optimization, which revealed that the 1,3-diketone side chain hybridized with furanopyrimidine scaffold that respectively combined amino-type substituent and 1H-pyrazol-4-yl substituent on the top and bottom of the aryl regions to produce 22 and 33, exhibiting potent antitumor activities in various syngeneic and xenograft models. More importantly, 33 demonstrated remarkable immune-modulating activity by upregulating the expression of total T-cells, cytotoxic CD8+ T-cells, and helper CD4+ T-cells in the spleen. These findings underscored the bifunctional capabilities of 33 (BPR5K230) with excellent oral bioavailability (F = 54.6%), inhibiting both MER and AXL while modulating the tumor microenvironment and highlighting its diverse applicability for further studies to advance its therapeutic potential.

"Find Me" and "Eat Me" signals: tools to drive phagocytic processes for modulating antitumor immunity

Phagocytosis, a vital defense mechanism, involves the recognition and elimination of foreign substances by cells. Phagocytes, such as neutrophils and macrophages, rapidly respond to invaders; macrophages are especially important in later stages of the immune response. They detect "find me" signals to locate apoptotic cells and migrate toward them. Apoptotic cells then send "eat me" signals that are recognized by phagocytes via specific receptors. "Find me" and "eat me" signals can be strategically harnessed to modulate antitumor immunity in support of cancer therapy. These signals, such as calreticulin and phosphatidylserine, mediate potent pro-phagocytic effects, thereby promoting the engulfment of dying cells or their remnants by macrophages, neutrophils, and dendritic cells and inducing tumor cell death. This review summarizes the phagocytic "find me" and "eat me" signals, including their concepts, signaling mechanisms, involved ligands, and functions. Furthermore, we delineate the relationships between "find me" and "eat me" signaling molecules and tumors, especially the roles of these molecules in tumor initiation, progression, diagnosis, and patient prognosis. The interplay of these signals with tumor biology is elucidated, and specific approaches to modulate "find me" and "eat me" signals and enhance antitumor immunity are explored. Additionally, novel therapeutic strategies that combine "find me" and "eat me" signals to better bridge innate and adaptive immunity in the treatment of cancer patients are discussed.

Co-targeting JAK1/STAT6/GAS6/TAM signaling improves chemotherapy efficacy in Ewing sarcoma

Ewing sarcoma is a pediatric bone and soft tissue tumor treated with chemotherapy, radiation, and surgery. Despite intensive multimodality therapy, ~50% patients eventually relapse and die of the disease due to chemoresistance. Here, using phospho-profiling, we find Ewing sarcoma cells treated with chemotherapeutic agents activate TAM (TYRO3, AXL, MERTK) kinases to augment Akt and ERK signaling facilitating chemoresistance. Mechanistically, chemotherapy-induced JAK1-SQ phosphorylation releases JAK1 pseudokinase domain inhibition allowing for JAK1 activation. This alternative JAK1 activation mechanism leads to STAT6 nuclear translocation triggering transcription and secretion of the TAM kinase ligand GAS6 with autocrine/paracrine consequences. Importantly, pharmacological inhibition of either JAK1 by filgotinib or TAM kinases by UNC2025 sensitizes Ewing sarcoma to chemotherapy in vitro and in vivo. Excitingly, the TAM kinase inhibitor MRX-2843 currently in human clinical trials to treat AML and advanced solid tumors, enhances chemotherapy efficacy to further suppress Ewing sarcoma tumor growth in vivo. Our findings reveal an Ewing sarcoma chemoresistance mechanism with an immediate translational value.

Multiomics integration-based immunological characterizations of adamantinomatous craniopharyngioma in relation to keratinization

Although adamantinomatous craniopharyngioma (ACP) is a tumour with low histological malignancy, there are very few therapeutic options other than surgery. ACP has high histological complexity, and the unique features of the immunological microenvironment within ACP remain elusive. Further elucidation of the tumour microenvironment is particularly important to expand our knowledge of potential therapeutic targets. Here, we performed integrative analysis of 58,081 nuclei through single-nucleus RNA sequencing and spatial transcriptomics on ACP specimens to characterize the features and intercellular network within the microenvironment. The ACP environment is highly immunosuppressive with low levels of T-cell infiltration/cytotoxicity. Moreover, tumour-associated macrophages (TAMs), which originate from distinct sources, highly infiltrate the microenvironment. Using spatial transcriptomic data, we observed one kind of non-microglial derived TAM that highly expressed GPNMB close to the terminally differentiated epithelial cell characterized by RHCG, and this colocalization was verified by asmFISH. We also found the positive correlation of infiltration between these two cell types in datasets with larger cohort. According to intercellular communication analysis, we report a regulatory network that could facilitate the keratinization of RHCG+ epithelial cells, eventually causing tumour progression. Our findings provide a comprehensive analysis of the ACP immune microenvironment and reveal a potential therapeutic strategy base on interfering with these two types of cells.

Targeting Tyro3, Axl, and MerTK Receptor Tyrosine Kinases Significantly Sensitizes Triple-Negative Breast Cancer to CDK4/6 Inhibition

Triple-negative breast cancer (TNBC) is the most aggressive subtype with high metastasis and mortality rates. Given the lack of actionable targets such as ER and HER2, TNBC still remains an unmet therapeutic challenge. Despite harboring high CDK4/6 expression levels, the efficacy of CDK4/6 inhibition in TNBC has been limited due to the emergence of resistance. The resistance to CDK4/6 inhibition is mainly mediated by RB1 inactivation. Since our aim is to overcome resistance to CDK4/6 inhibition, in this study, we primarily used the cell lines that do not express RB1. Following a screening for activated receptor tyrosine kinases (RTKs) upon CDK4/6 inhibition, we identified the TAM (Tyro3, Axl, and MerTK) RTKs as a crucial therapeutic vulnerability in TNBC. We show that targeting the TAM receptors with a novel inhibitor, sitravatinib, significantly sensitizes TNBC to CDK4/6 inhibitors. Upon prolonged HER2 inhibitor treatment, HER2+ breast cancers suppress HER2 expression, physiologically transforming into TNBC-like cells. We further show that the combined treatment is highly effective against drug-resistant HER2+ breast cancer as well. Following quantitative proteomics and RNA-seq data analysis, we extended our study into the immunophenotyping of TNBC. Given the roles of the TAM receptors in promoting the creation of an immunosuppressive tumor microenvironment (TME), we further demonstrate that the combination of CDK4/6 inhibitor abemaciclib and sitravatinib modifies the immune landscape of TNBC to favor immune checkpoint blockade. Overall, our study offers a novel and highly effective combination therapy against TNBC and potentially treatment-resistant HER2+ breast cancer that can be rapidly moved to the clinic.

Knocking down of Xkr8 enhances chemotherapy efficacy through modulating tumor immune microenvironment

Scramblase Xk-related protein 8 (Xkr8) regulates the externalization of phosphatidylserine (PS) during apoptosis and holds a pivotal role in fostering tumor immunosuppression. Targeting Xkr8 in conjunction with chemotherapy demonstrated a novel avenue for amplifying antitumor immune response and overcoming chemo-immune resistance. Here we further evaluated this strategy by using a clinically relevant orthotopic model and elucidated the mechanism through in-depth single-cell RNA sequencing (scRNA-seq). We found that Xkr8 knockdown exhibited the potential to lead to immunogenic cell death (ICD) by impeding the normal clearance of apoptotic cells. Co-delivery of Xkr8 small interference RNA (siRNA) and a prodrug conjugate of 5-fluorouracil (5-Fu) and oxoplatin (FuOXP) showed remarkable therapeutic efficacy in an orthotopic pancreatic tumor model with increased infiltration of proliferative NK cells and activated macrophages in the tumor microenvironment (TME). Single-cell trajectory analysis further unveiled that tumor infiltrating CD8+ T cells are differentiated favorably to cytotoxic over exhausted phenotype after combination treatment. Our study sheds new light on the impact of Xkr8 knockdown on TME and solidifies the rationale of combining Xkr8 knockdown with chemotherapy to treat various types of cancers.

Immunological role of Gas6/TAM signaling in hemostasis and thrombosis

The immune system is an emerging regulator of hemostasis and thrombosis. The concept of immunothrombosis redefines the relationship between coagulation and immunomodulation, and the Gas6/Tyro3-Axl-MerTK (TAM) signaling pathway builds the bridge across them. During coagulation, Gas6/TAM signaling pathway not only activates platelets, but also promotes thrombosis through endothelial cells and vascular smooth muscle cells involved in inflammatory responses. Thrombosis appears to be a common result of a Gas6/TAM signaling pathway-mediated immune dysregulation. TAM TK and its ligands have been found to be involved in coagulation through the PI3K/AKT or JAK/STAT pathway in various systemic diseases, providing new perspectives in the understanding of immunothrombosis. Gas6/TAM signaling pathway serves as a breakthrough target for novel therapeutic strategies to improve disease management. Many preclinical and clinical studies of TAM receptor inhibitors are in process, confirming the pivotal role of Gas6/TAM signaling pathway in immunothrombosis. Therapeutics targeting the TAM receptor show potential both in anticoagulation management and immunotherapy. Here, we review the immunological functions of the Gas6/TAM signaling pathway in coagulation and its multiple mechanisms in diseases identified to date, and discuss the new clinical strategies that may generated by these roles.

A novel insight into cancer therapy: Lipid metabolism in tumor-associated macrophages

The tumor immune microenvironment (TIME) can limit the effectiveness and often leads to significant side effects of conventional cancer therapies. Consequently, there is a growing interest in identifying novel targets to enhance the efficacy of targeted cancer therapy. More research indicates that tumor-associated macrophages (TAMs), originating from peripheral blood monocytes generated from bone marrow myeloid progenitor cells, play a crucial role in the tumor microenvironment (TME) and are closely associated with resistance to traditional cancer therapies. Lipid metabolism alterations have been widely recognized as having a significant impact on tumors and their immune microenvironment. Lipids, lipid derivatives, and key substances in their metabolic pathways can influence the carcinogenesis and progression of cancer cells by modulating the phenotype, function, and activity of TAMs. Therefore, this review focuses on the reprogramming of lipid metabolism in cancer cells and their immune microenvironment, in which the TAMs are especially concentrated. Such changes impact TAMs activation and polarization, thereby affecting the tumor cell response to treatment. Furthermore, the article explores the potential of targeting the lipid metabolism of TAMs as a supplementary approach to conventional cancer therapies. It reviews and evaluates current strategies for enhancing efficacy through TAMs' lipid metabolism and proposes new lipid metabolism targets as potential synergistic options for chemo-radiotherapy and immunotherapy. These efforts aim to stimulate further research in this area.

Efferocytosis in dendritic cells: an overlooked immunoregulatory process

Efferocytosis, the process of engulfing and removing apoptotic cells, plays an essential role in preserving tissue health and averting undue inflammation. While macrophages are primarily known for this task, dendritic cells (DCs) also play a significant role. This review delves into the unique contributions of various DC subsets to efferocytosis, highlighting the distinctions in how DCs and macrophages recognize and handle apoptotic cells. It further explores how efferocytosis influences DC maturation, thereby affecting immune tolerance. This underscores the pivotal role of DCs in orchestrating immune responses and sustaining immune equilibrium, providing new insights into their function in immune regulation.

Establishment of a novel efferocytosis potential index predicts prognosis and immunotherapy response in cancers

The biological function and prognostic value of efferocytosis in cancer remains unclear. In this study, we systematically analysed the expression profiles and genetic variations of 50 efferocytosis-related regulator genes in 33 cancer types. Using data from The Cancer Genome Atlas, we established an efferocytosis potential index (EPI) model to represent the efferocytosis level in each cancer type. The relationship between the EPI and prognosis, immune-related molecules, specific pathways, and drug sensitivity was determined. We found that efferocytosis regulator genes were abnormally expressed in cancer tissue, perhaps owing to copy number variations, gene alterations, and DNA methylation. For the most part, the EPI was higher in tumour vs. normal tissues. In most of the 33 cancer types, it positively correlated with cell death- and immune-related pathway enrichment, the tumour microenvironment, immune infiltration, and drug sensitivity. For specific cancers, a high EPI may be a prognostic risk factor and, in patients treated receiving immune checkpoint therapy, a predictor of poor prognosis. Our study reveals the biological functions of efferocytosis-related regulator genes in distinct cancers and highlights the potential of efferocytosis intervention in cancer therapy.

Efferocytosis by macrophages in physiological and pathological conditions: regulatory pathways and molecular mechanisms

Efferocytosis is defined as the highly effective phagocytic removal of apoptotic cells (ACs) by professional or non-professional phagocytes. Tissue-resident professional phagocytes ("efferocytes"), such as macrophages, have high phagocytic capacity and are crucial to resolve inflammation and aid in homeostasis. Recently, numerous exciting discoveries have revealed divergent (and even diametrically opposite) findings regarding metabolic immune reprogramming associated with efferocytosis by macrophages. In this review, we highlight the key metabolites involved in the three phases of efferocytosis and immune reprogramming of macrophages under physiological and pathological conditions. The next decade is expected to yield further breakthroughs in the regulatory pathways and molecular mechanisms connecting immunological outcomes to metabolic cues as well as avenues for "personalized" therapeutic intervention.

Radiation-based immunogenic vaccine combined with a macrophage "checkpoint inhibitor" for boosting innate and adaptive immunity against metastatic colon cancers

Immunogenic dying tumor cells hold promising prospects as cancer vaccines to activate systemic immunity against both primary and metastatic tumors. Especially, X-ray- induced dying tumor cells are rich in highly immunogenic tumor-associated antigens and self-generated dsDNA as potent adjuvants. However, we found that the X-ray induction process can result in the excessive exposure of phosphatidylserine in cancer vaccines, which can specifically bind with the MerTK receptor on macrophages, acting as a "checkpoint" to facilitate immune silence in the tumor microenvironment. Therefore, we developed a novel strategy combining X-ray-induced cancer vaccines with UNC2250, a macrophage MerTK "checkpoint inhibitor," for treating peritoneal carcinomatosis in colon cancer. By incorporating UNC2250 into the treatment regimen, immunosuppressive efferocytosis of macrophages, which relies on MerTK-directed recognition of phosphatidylserine on vaccines, was effectively blocked. Consequently, the immune analysis revealed that this combination strategy promoted the maturation of dendritic cells and M1-like repolarization of macrophages, thereby simultaneously eliciting robust adaptive and innate immunity. This innovative approach utilizing X-ray-induced vaccines combined with a checkpoint inhibitor may provide valuable insights for developing effective cancer vaccines and immunotherapies targeting colon cancer.

Deciphering peri-implantitis: Unraveling signature genes and immune cell associations through bioinformatics and machine learning

Early diagnosis of peri-implantitis (PI) is crucial to understand its pathological progression and prevention. This study is committed to investigating the signature genes, relevant signaling pathways and their associations with immune cells in PI. We analyzed differentially expressed genes (DEGs) from a PI dataset in the gene expression omnibus database. Functional enrichment analysis was conducted for these DEGs. Weighted Gene Co-expression Network Analysis was used to identify specific modules. Least absolute shrinkage and selection operator and support vector machine recursive feature elimination were ultimately applied to identify the signature genes. These genes were subsequently validated in an external dataset. And the immune cells infiltration was classified using CIBERSORT. A total of 180 DEGs were screened from GSE33774. Weighted Gene Co-expression Network Analysis revealed a significant association between the MEturquoise module and PI (cor = 0.6, P < .0001). Least absolute shrinkage and selection operator and support vector machine recursive feature elimination algorithms were applied to select the signature genes, containing myeloid-epithelial-reproductive tyrosine kinase, microfibrillar-associated protein 5, membrane-spanning 4A 4A, tribbles homolog 1. In the validation on the external dataset GSE106090, all these genes achieved area under curve values exceeding 0.95. GSEA analysis showed that these genes were correlated with the NOD-like receptor signaling pathway, metabolism of xenobiotics by cytochrome P450, and arachidonic acid metabolism. CIBERSORT revealed elevated levels of macrophage M2 and activated mast cells in PI. This study provides novel insights into understanding the molecular mechanisms of PI and contributes to advancements in its early diagnosis and prevention.

Establishment of a cholangiocarcinoma risk evaluation model based on mucin expression levels

BACKGROUND

Cholangiocarcinoma (CCA) is a highly malignant cancer, characterized by frequent mucin overexpression. MUC1 has been identified as a critical oncogene in the progression of CCA. However, the comprehensive understanding of how the mucin family influences CCA progression and prognosis is still incomplete.

AIM

To investigate the functions of mucins on the progression of CCA and to establish a risk evaluation formula for stratifying CCA patients.

METHODS

Single-cell RNA sequencing data from 14 CCA samples were employed for elucidating the roles of mucins, complemented by bioinformatic analyses. Subsequent validations were conducted through spatial transcriptomics and immunohistochemistry. The construction of a risk evaluation model utilized the least absolute shrinkage and selection operator regression algorithm, which was further confirmed by independent cohorts and diverse data types.

RESULTS

CCA tumor cells with elevated levels of MUC1 and MUC4 showed activated nucleotide metabolic pathways and increased invasiveness. MUC5AC-high cells were found to promote CCA progression through WNT signaling. MUC5B-high cells exhibited robust cellular oxidation activities, leading to resistance against antitumoral treatments. MUC13-high cells were observed to secret chemokines, recruiting and transforming macrophages into the M2-polarized state, thereby suppressing antitumor immunity. MUC16-high cells were found to promote tumor progression through interleukin-1/nuclear factor kappa-light-chain-enhancer of activated B cells signaling upon interaction with neutrophils. Utilizing the expression levels of these mucins, a risk factor evaluation formula for CCA was developed and validated across multiple cohorts. CCA samples with higher risk factors exhibited stronger metastatic potential, chemotherapy resistance, and poorer prognosis.

CONCLUSION

Our study elucidates the functional mechanisms through which mucins contribute to CCA development, and provides tools for risk stratification in CCA.

Mertk Reduces Blood-Spinal Cord Barrier Permeability Through the Rhoa/Rock1/P-MLC Pathway After Spinal Cord Injury

Disruption of the blood-spinal cord barrier (BSCB) is a critical event in the secondary injury following spinal cord injury (SCI). Mertk has been reported to play an important role in regulating inflammation and cytoskeletal dynamics. However, the specific involvement of Mertk in BSCB remains elusive. Here, we demonstrated a distinct role of Mertk in the repair of BSCB. Mertk expression is decreased in endothelial cells following SCI. Overexpression of Mertk upregulated tight junction proteins (TJs), reducing BSCB permeability and subsequently inhibiting inflammation and apoptosis. Ultimately, this led to enhanced neural regeneration and functional recovery. Further experiments revealed that the RhoA/Rock1/P-MLC pathway plays a key role in the effects of Mertk. These findings highlight the role of Mertk in promoting SCI recovery through its ability to mitigate BSCB permeability and may provide potential targets for SCI repair.

Phosphatidylserine externalization as immune checkpoint in cancer

Cancer is the second leading cause of mortality worldwide. Despite recent advances in cancer treatment including immunotherapy with immune checkpoint inhibitors, new unconventional biomarkers and targets for the detection, prognosis, and treatment of cancer are still in high demand. Tumor cells are characterized by mutations that allow their unlimited growth, program their local microenvironment to support tumor growth, and spread towards distant sites. While a major focus has been on altered tumor genomes and proteomes, crucial signaling molecules such as lipids have been underappreciated. One of these molecules is the membrane phospholipid phosphatidylserine (PS) that is usually found at cytosolic surfaces of cellular membranes but can be rapidly and massively shuttled to the extracellular leaflet of the plasma membrane during apoptosis to serve as a limiting factor for immune responses. These immunosuppressive interactions are exploited by tumor cells to evade the immune system. In this review, we describe mechanisms of immune regulation in tumors, discuss if PS may constitute an inhibitory immune checkpoint, and describe current and future strategies for targeting PS to reactivate the tumor-associated immune system.

Cardiac resident macrophages: Spatiotemporal distribution, development, physiological functions, and their translational potential on cardiac diseases

Cardiac resident macrophages (CRMs) are the main population of cardiac immune cells. The role of these cells in regeneration, functional remodeling, and repair after cardiac injury is always the focus of research. However, in recent years, their dynamic changes and contributions in physiological states have a significant attention. CRMs have specific phenotypes and functions in different cardiac chambers or locations of the heart and at different stages. They further show specific differentiation and development processes. The present review will summarize the new progress about the spatiotemporal distribution, potential developmental regulation, and their roles in cardiac development and aging as well as the translational potential of CRMs on cardiac diseases. Of course, the research tools for CRMs, their respective advantages and disadvantages, and key issues on CRMs will further be discussed.

Big data analytics for MerTK genomics reveals its double-edged sword functions in human diseases

RATIONALE

MER proto-oncogene tyrosine kinase (MerTK) is a key receptor for the clearance of apoptotic cells (efferocytosis) and plays important roles in redox-related human diseases. We will explore MerTK biology in human cells, tissues, and diseases based on big data analytics.

METHODS

The human RNA-seq and scRNA-seq data about 42,700 samples were from NCBI Gene Expression Omnibus and analyzed by QIAGEN Ingenuity Pathway Analysis (IPA) with about 170,000 crossover analysis. MerTK expression was quantified as Log2 (FPKM + 0.1).

RESULTS

We found that, in human cells, MerTK is highly expressed in macrophages, monocytes, progenitor cells, alpha-beta T cells, plasma B cells, myeloid cells, and endothelial cells (ECs). In human tissues, MerTK has higher expression in plaque, blood vessels, heart, liver, sensory system, artificial tissue, bone, adrenal gland, central nervous system (CNS), and connective tissue. Compared to normal conditions, MerTK expression in related tissues is altered in many human diseases, including cardiovascular diseases, cancer, and brain disorders. Interestingly, MerTK expression also shows sex differences in many tissues, indicating that MerTK may have different impact on male and female. Finally, based on our proteomics from primary human aortic ECs, we validated the functions of MerTK in several human diseases, such as cancer, aging, kidney failure and heart failure.

CONCLUSIONS

Our big data analytics suggest that MerTK may be a promising therapeutic target, but how it should be modulated depends on the disease types and sex differences. For example, MerTK inhibition emerges as a new strategy for cancer therapy due to it counteracts effect on anti-tumor immunity, while MerTK restoration represents a promising treatment for atherosclerosis and myocardial infarction as MerTK is cleaved in these disease conditions.

The Role of Macrophage Efferocytosis in the Pathogenesis of Apical Periodontitis

Macrophages (Mφs) play a crucial role in the homeostasis of the periapical immune micro-environment caused by bacterial infection. Mφ efferocytosis has been demonstrated to promote the resolution of multiple infected diseases via accelerating Mφ polarization into M2 type. However, the Mφ efferocytosis-apical periodontitis (AP) relationship has not been elucidated yet. This study aimed to explore the role of Mφ efferocytosis in the pathogenesis of AP. Clinical specimens were collected to determine the involvement of Mφ efferocytosis in the periapical region via immunohistochemical and immunofluorescence staining. For a further understanding of the moderator effect of Mφ efferocytosis in the pathogenesis of AP, both an in vitro AP model and in vivo AP model were treated with ARA290, a Mφ efferocytosis agonist. Histological staining, micro-ct, flow cytometry, RT-PCR and Western blot analysis were performed to detect the inflammatory status, alveolar bone loss and related markers in AP models. The data showed that Mφ efferocytosis is observed in the periapical tissues and enhancing the Mφ efferocytosis ability could effectively promote AP resolution via facilitating M2 Mφ polarization. Collectively, our study demonstrates the functional importance of Mφ efferocytosis in AP pathology and highlights that accelerating Mφ efferocytosis via ARA290 could serve as an adjuvant therapeutic strategy for AP.

Macrocycles and macrocyclization in anticancer drug discovery: Important pieces of the puzzle

Increasing disease-related proteins have been identified as novel therapeutic targets. Macrocycles are emerging as potential solutions, bridging the gap between conventional small molecules and biomacromolecules in drug discovery. Inspired by successful macrocyclic drugs of natural origins, macrocycles are attracting more attention for enhanced binding affinity and target selectivity. Due to the conformation constraint and structure preorganization, macrocycles can reach bioactive conformations more easily than parent acyclic compounds. Also, rational macrocyclization combined with sequent structural modification will help improve oral bioavailability and combat drug resistance. This review introduces various strategies to enhance membrane permeability in macrocyclization and subsequent modification, such as N-methylation, intramolecular hydrogen bonding modulation, isomerization, and reversible bicyclization. Several case studies highlight macrocyclic inhibitors targeting kinases, HDAC, and protein-protein interactions. Finally, some macrocyclic agents targeting tumor microenvironments are illustrated.

Inhibition of MER proto-oncogene tyrosine kinase by an antisense oligonucleotide enhances treatment efficacy of immunoradiotherapy

BACKGROUND

The combination of radiotherapy and immunotherapy (immunoradiotherapy) has been increasingly used for treating a wide range of cancers. However, some tumors are resistant to immunoradiotherapy. We have previously shown that MER proto-oncogene tyrosine kinase (MerTK) expressed on macrophages mediates resistance to immunoradiotherapy. We therefore sought to develop therapeutics that can mitigate the negative impact of MerTK. We designed and developed a MerTK specific antisense oligonucleotide (ASO) and characterized its effects on eliciting an anti-tumor immune response in mice.

METHODS

344SQR cells were injected into the right legs on day 0 and the left legs on day 4 of 8-12 weeks old female 129sv/ev mice to establish primary and secondary tumors, respectively. Radiation at a dose of 12 Gy was given to the primary tumors on days 8, 9, and 10. Mice received either anti-PD-1, anti-CTLA-4 or/and MerTK ASO starting from day 1 post tumor implantation. The composition of the tumor microenvironment and the level of MerTK on macrophages in the tumor were evaluted by flow cytometry. The expression of immune-related genes was investigated with NanoString. Lastly, the impact of MerTK ASO on the structure of the eye was histologically evaluated.

RESULTS

Remarkably, the addition of MerTK ASO to XRT+anti-PD1 and XRT+anti-CTLA4 profoundly slowed the growth of both primary and secondary tumors and significantly extended survival. The ASO significantly reduced the expression of MerTK in tumor-associated macrophages (TAMs), reprograming their phenotype from M2 to M1. In addition, MerTK ASO increased the percentage of Granzyme B+ CD8+ T cells in the secondary tumors when combined with XRT+anti-CTLA4. NanoString results demonstrated that the MerTK ASO favorably modulated immune-related genes for promoting antitumor immune response in secondary tumors. Importantly, histological analysis of eye tissues demonstrated that unlike small molecules, the MerTK ASO did not produce any detectable pathology in the eyes.

CONCLUSIONS

The MerTK ASO can significantly downregulate the expression of MerTK on TAMs, thereby promoting antitumor immune response. The combination of MerTK ASO with immunoradiotherapy can safely and significantly slow tumor growth and improve survival.

Nano-enhanced immunotherapy: Targeting the immunosuppressive tumor microenvironment

The tumor microenvironment (TME), which is mostly composed of tumor cells, immune cells, signaling molecules, stromal tissue, and the vascular system, is an integrated system that is conducive to the formation of tumors. TME heterogeneity makes the response to immunotherapy different in different tumors, such as "immune-cold" and "immune-hot" tumors. Tumor-associated macrophages, myeloid-derived suppressor cells, and regulatory T cells are the major suppressive immune cells and their different phenotypes interact and influence cancer cells by secreting different signaling factors, thus playing a key role in the formation of the TME as well as in the initiation, growth, and metastasis of cancer cells. Nanotechnology development has facilitated overcoming the obstacles that limit the further development of conventional immunotherapy, such as toxic side effects and lack of targeting. In this review, we focus on the role of three major suppressive immune cells in the TME as well as in tumor development, clinical trials of different drugs targeting immune cells, and different attempts to combine drugs with nanomaterials. The aim is to reveal the relationship between immunotherapy, immunosuppressive TME and nanomedicine, thus laying the foundation for further development of immunotherapy.

Signaling Pathways of AXL Receptor Tyrosine Kinase Contribute to the Pathogenetic Mechanisms of Glioblastoma

Brain tumors are a diverse collection of neoplasms affecting the brain with a high prevalence rate in people of all ages around the globe. In this pathological context, glioblastoma, a form of glioma that belongs to the IV-grade astrocytoma group, is the most common and most aggressive form of the primary brain tumors. Indeed, despite the best treatments available including surgery, radiotherapy or a pharmacological approach with Temozolomide, glioblastoma patients' mortality is still high, within a few months of diagnosis. Therefore, to increase the chances of these patients surviving, it is critical to keep finding novel treatment opportunities. In the past, efforts to treat glioblastoma have mostly concentrated on customized treatment plans that target specific mutations such as epidermal growth factor receptor (EGFR) mutations, Neurotrophic Tyrosine Receptor Kinase (NTRK) fusions, or multiple receptors using multi-kinase inhibitors like Sunitinib and Regorafenib, with varying degrees of success. Here, we focused on the receptor tyrosine kinase AXL that has been identified as a mediator for tumor progression and therapy resistance in various cancer types, including squamous cell tumors, small cell lung cancer, and breast cancer. Activated AXL leads to a significant increase in tumor proliferation, tumor cell migration, and angiogenesis in different in vitro and in vivo models of cancer since this receptor regulates interplay with apoptotic, angiogenic and inflammatory pathways. Based on these premises, in this review we mainly focused on the role of AXL in the course of glioblastoma, considering its primary biological mechanisms and as a possible target for the application of the most recent treatments.

Mrc1+ macrophage-derived IGF1 mitigates crystal nephropathy by promoting renal tubule cell proliferation via the AKT/Rb signaling pathway

Rationale: The present understanding of the cellular characteristics and communications in crystal nephropathy is limited. Here, molecular and cellular studies combined with single-cell RNA sequencing (scRNA-seq) were performed to investigate the changes in cell components and their interactions in glyoxylate-induced crystallized kidneys to provide promising treatments for crystal nephropathy. Methods: The transcriptomes of single cells from mouse kidneys treated with glyoxylate for 0, 1, 4, or 7 days were analyzed via 10× Genomics, and the single cells were clustered and characterized by the Seurat pipeline. The potential cellular interactions between specific cell types were explored by CellChat. Molecular and cellular findings related to macrophage-to-epithelium crosstalk were validated in sodium oxalate (NaOx)-induced renal tubular epithelial cell injury in vitro and in glyoxylate-induced crystal nephropathy in vivo. Results: Our established scRNA atlas of glyoxylate-induced crystalline nephropathy contained 15 cell populations with more than 40000 single cells, including relatively stable tubular cells of different segments, proliferating and injured proximal tubular cells, T cells, B cells, and myeloid and mesenchymal cells. In this study, we found that Mrc1+ macrophages, as a subtype of myeloid cells, increased in both the number and percentage within the myeloid population as crystal-induced injury progresses, and distinctly express IGF1, which induces the activation of a signal pathway to dominate a significant information flow towards injured and proliferating tubule cells. IGF1 promoted the repair of damaged tubular epithelial cells induced by NaOx in vitro, as well as the repair of damaged tubular epithelial cells and the recovery of disease outcomes in glyoxylate-induced nephrolithic mice in vivo. Conclusion: After constructing a cellular atlas of glyoxylate-induced crystal nephropathy, we found that IGF1 derived from Mrc1+ macrophages attenuated crystal nephropathy through promoting renal tubule cell proliferation via the AKT/Rb signaling pathway. These findings could lead to the identification of potential therapeutic targets for the treatment of crystal nephropathy.

Discovery of a 1,6-naphthyridin-4-one-based AXL inhibitor with improved pharmacokinetics and enhanced in vivo antitumor efficacy

The receptor tyrosine kinase AXL has emerged as an attractive target in anticancer drug discovery. Herein, we described the discovery of a new series of 1,6-naphthyridin-4-one derivatives as potent AXL inhibitors. Starting from a low in vivo potency compound 9 which was previously reported by our group, we utilized structure-based drug design and scaffold hopping strategies to discover potent AXL inhibitors. The privileged compound 13c was a highly potent and orally bioavailable AXL inhibitor with an IC50 value of 3.2 ± 0.3 nM. Compound 13c exhibited significantly improved in vivo antitumor efficacy in AXL-driven tumor xenograft mice, causing tumor regression at well-tolerated dose, and demonstrated favorable pharmacokinetic properties (MRT = 16.5 h, AUC0-∞ = 59,815 ng h/mL) in Sprague-Dawley rats. These results suggest that 13c is a promising therapeutic candidate for AXL-targeting cancer treatment.

Ningetinib plus gefitinib in EGFR-mutant non-small-cell lung cancer with MET and AXL dysregulations: A phase 1b clinical trial and biomarker analysis

BACKGROUND

MET and AXL dysregulations are implicated in acquired resistance to EGFR-TKIs in NSCLC. But consensus on the optimal definition for MET/AXL dysregulations in EGFR-mutant NSCLC is lacking. Here, we investigated the efficacy and tolerability of ningetinib (a MET/AXL inhibitor) plus gefitinib in EGFR-mutant NSCLC, and evaluated the clinical relevance of MET/AXL dysregulations by different definitions.

METHODS

Patients in this phase 1b dose-escalation/dose-expansion trial received ningetinib 30 mg/40 mg/60 mg plus gefitinib 250 mg once daily. Primary endpoints were tolerability (dose-escalation) and objective response rate (dose-expansion). MET/AXL status were analyzed using FISH and IHC.

RESULTS

Between March 2017 and January 2021, 108 patients were enrolled. The proportion of MET focal amplification, MET polysomy, MET overexpression, AXL amplification and AXL overexpression is 18.1 %, 5.6 %, 55.8 %, 8.1 % and 45.3 %, respectively. 6.8 % patients have concurrent MET amplification and AXL overexpression. ORR is 30.8 % for tumors with MET amplification, 0 % for MET polysomy, 24.1 % for MET overexpression, 20 % for AXL amplification and 27.6 % for AXL overexpression. For patients with concurrent MET amplification and AXL overexpression, ningetinib plus gefitinib provides an ORR of 80 %, DCR of 100 % and median PFS of 4.7 months. Tumors with higher MET copy number and AXL expression tend to have higher likelihood of response. Biomarker analyses show that MET focal amplification and overexpression are complementary in predicting clinical benefit from MET inhibition, while AXL dysregulations defined by an arbitrary level may dilute the efficacy of AXL blockade.

CONCLUSIONS

This study demonstrates that combined blockade of MET, AXL and EGFR is a feasible strategy for a subset of EGFR-mutant NSCLC.

TRIAL REGISTRATION

Chinadrugtrials.org.cn, CTR20160875.

The power and the promise of CAR-mediated cell immunotherapy for clinical application in pancreatic cancer

BACKGROUND

Pancreatic cancer, referred to as the "monarch of malignancies," is a neoplastic growth mostly arising from the epithelial cells of the pancreatic duct and acinar cells. This particular neoplasm has a highly unfavorable prognosis due to its marked malignancy, inconspicuous initial manifestation, challenging early detection, rapid advancement, and limited survival duration. Cellular immunotherapy is the ex vivo culture and expansion of immune effector cells, granting them the capacity to selectively target malignant cells using specialized techniques. Subsequently, these modified cells are reintroduced into the patient's organism with the purpose of eradicating tumor cells and providing therapeutic intervention for cancer.

PRESENT SITUATION

Presently, the primary cellular therapeutic modalities employed in the treatment of pancreatic cancer encompass CAR T-cell therapy, TCR T-cell therapy, NK-cell therapy, and CAR NK-cell therapy.

AIM OF REVIEW

This review provides a concise overview of the mechanisms and primary targets associated with various cell therapies. Additionally, we will explore the prospective outlook of cell therapy in the context of treating pancreatic cancer.

From MASH to HCC: the role of Gas6/TAM receptors

Metabolic dysfunction-associated steatohepatitis (MASH) is the replacement term for what used to be called nonalcoholic steatohepatitis (NASH). It is characterized by inflammation and injury of the liver in the presence of cardiometabolic risk factors and may eventually result in the development of hepatocellular carcinoma (HCC), the most common form of primary liver cancer. Several pathogenic mechanisms are involved in the transition from MASH to HCC, encompassing metabolic injury, inflammation, immune dysregulation and fibrosis. In this context, Gas6 (Growth Arrest-Specific 6) and TAM (Tyro3, Axl, and MerTK) receptors may play important roles. The Gas6/TAM family is involved in the modulation of inflammation, lipid metabolism, fibrosis, tumor progression and metastasis, processes which play an important role in the pathophysiology of acute and chronic liver diseases. In this review, we discuss MASH-associated HCC and the potential involvement of the Gas6/TAM system in disease development and progression. In addition, since therapeutic strategies for MASH and HCC are limited, we also speculate regarding possible future treatments involving the targeting of Gas6 or TAM receptors.

Macrophage plasticity and function in cancer and pregnancy

As the soil of life, the composition and shaping process of the immune microenvironment of the uterus is worth exploring. Macrophages, indispensable constituents of the innate immune system, are essential mediators of inflammation and tissue remodeling as well. Recent insights into the heterogeneity of macrophage subpopulations have renewed interest in their functional diversity in both physiological and pathological settings. Macrophages display remarkable plasticity and switch from one phenotype to another. Intrinsic plasticity enables tissue macrophages to perform a variety of functions in response to changing tissue contexts, such as cancer and pregnancy. The remarkable diversity and plasticity make macrophages particularly intriguing cells given their dichotomous role in either attacking or protecting tumors and semi-allogeneic fetuses, which of both are characterized functionally by immunomodulation and neovascularization. Here, we reviewed and compared novel perspectives on macrophage biology of these two settings, including origin, phenotype, differentiation, and essential roles in corresponding microenvironments, as informed by recent studies on the heterogeneity of macrophage identity and function, as well as their mechanisms that might offer opportunities for new therapeutic strategies on malignancy and pregnancy complications.

MICA+ Tumor Cell Upregulated Macrophage-Secreted MMP9 via PROS1-AXL Axis to Induce Tumor Immune Escape in Advanced Hepatocellular Carcinoma (HCC)

BACKGROUND

tumor-associated macrophages (TAMs) constitute a significant proportion of non-cancerous cells within the intricate tumor microenvironment (TME) of hepatocellular carcinoma (HCC). Understanding the communication between macrophages and tumor cells, as well as investigating potential signaling pathways, holds promise for enhancing therapeutic responses in HCC.

METHODS

single-cell RNA-sequencing data and bulk RNA-sequencing data were derived from open source databases Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA). Through this analysis, we elucidated the interactions between MICA+ tumor cells and MMP9+ macrophages, primarily mediated via the PROS1-AXL axis in advanced HCC. Subsequently, we employed a range of experimental techniques including lentivirus infection, recombinant protein stimulation, and AXL inhibition experiments to validate these interactions and unravel the underlying mechanisms.

RESULTS

we presented a single-cell atlas of advanced HCC, highlighting the expression patterns of MICA and MMP9 in tumor cells and macrophages, respectively. Activation of the interferon gamma (IFN-γ) signaling pathway was observed in MICA+ tumor cells and MMP9+ macrophages. We identified the existence of an interaction between MICA+ tumor cells and MMP9+ macrophages mediated via the PROS1-AXL axis. Additionally, we found MMP9+ macrophages had a positive correlation with M2-like macrophages. Subsequently, experiments validated that DNA damage not only induced MICA expression in tumor cells via IRF1, but also upregulated PROS1 levels in HCC cells, stimulating macrophages to secrete MMP9. Consequently, MMP9 led to the proteolysis of MICA.

CONCLUSION

MICA+ HCC cells secreted PROS1, which upregulated MMP9 expression in macrophages through AXL receptors. The increased MMP9 activity resulted in the proteolytic shedding of MICA, leading to the release of soluble MICA (sMICA) and the subsequent facilitation of tumor immune escape.

A Bispecific Modeling Framework Enables the Prediction of Efficacy, Toxicity, and Optimal Molecular Design of Bispecific Antibodies Targeting MerTK

Inhibiting MerTK on macrophages is a promising therapeutic strategy for augmenting anti-tumor immunity. However, blocking MerTK on retinal pigment epithelial cells (RPEs) results in retinal toxicity. Bispecific antibodies (bsAbs) containing an anti-MerTK therapeutic and anti-PD-L1 targeting arm were developed to reduce drug binding to MerTK on RPEs, since PD-L1 is overexpressed on macrophages but not RPEs. In this study, we present a modeling framework using in vitro receptor occupancy (RO) and pharmacokinetics (PK) data to predict efficacy, toxicity, and therapeutic index (TI) of anti-MerTK bsAbs. We first used simulations and in vitro RO data of anti-MerTK monospecific antibody (msAb) to estimate the required MerTK RO for in vivo efficacy and toxicity. Using these estimated RO thresholds, we employed our model to predict the efficacious and toxic doses for anti-MerTK bsAbs with varying affinities for MerTK. Our model predicted the highest TI for the anti-MerTK/PD-L1 bsAb with an attenuated MerTK binding arm, which was consistent with in vivo efficacy and toxicity observations. Subsequently, we used the model, in combination with sensitivity analysis and parameter scans, to suggest an optimal molecular design of anti-MerTK bsAb with the highest predicted TI in humans. Our prediction revealed that this optimized anti-MerTK bsAb should contain a MerTK therapeutic arm with relatively low affinity, along with a high affinity targeting arm that can bind to a low abundance target with slow turnover rate. Overall, these results demonstrated that our modeling framework can guide the rational design of bsAbs.

Taurine Inhibits Ferroptosis Mediated by the Crosstalk between Tumor Cells and Tumor-Associated Macrophages in Prostate Cancer

Tumor-associated macrophages (TAMs) play an essential role in tumor therapeutic resistance. Although the lethal effect of ferroptosis on tumor cells is well reported, how TAMs inhibit the effect of ferroptosis in tumors has not been clearly defined. In this study, it is demonstrated that TAM-secreted taurine suppresses ferroptosis in prostate cancer (PCa) by activating the Liver X receptor alpha/Stearoyl-Coenzyme A desaturase 1 (LXRα/SCD1) pathway. Blocking taurine intake via inhibition of taurine transporter TauT restores the sensitivity to ferroptosis in tumors. Furthermore, LXRα activates the transcription of both miR-181a-5p and its binding protein FUS to increase the recruitment of miR-181a-5p in tumor-derived extracellular vesicles (EVs). It is observed that macrophages appear to be recipient cells of the miR-181a-5p-enriched EVs. Intake of miR-181a-5p in macrophages promotes their M2 polarization and enhances the taurine export by inhibiting expression of its target gene lats1, which in turn inactivates the hippo pathway and results in a Yes-associated protein (YAP) nuclear translocation for transcriptional activation of both M2 polarization-related genes such as ARG1 and CD163 and the taurine transport gene TauT. Taken together, the findings indicate a reciprocal interaction between PCa cells and TAMs as a positive feedback-loop to repress ferroptosis in PCa, mediated by TAM-secreted taurine and tumor EV-delivered miR-181a-5p.

Significant response from fruquintinib plus anti-PD-1 immunotherapy for microsatellite stable metastatic colorectal cancer with liver and lung metastasis in the third line: case report

Background

There are limited treatment options available for patients with metastatic colorectal cancer (mCRC). About 95% of CRC patients have mismatch repair proficient/microsatellite stable (pMMR/MSS) tumors are virtually unresponsive to programmed cell death protein 1 (PD-1) antibody treatment. This report shows that a patient with pMMR/MSS mCRC achieved significant response and the longest progression-free survival (PFS) of 28 months currently reported from tyrosine kinase inhibitors (TKIs) targeting vascular endothelial growth factor receptor (VEGFR) family (VEGFR-1,2,3) (fruquintinib) plus anti-PD-1 immunotherapy in the third line, providing a new and promising treatment option for some MSS mCRC patients.

Case Description

This case details a 65-year-old male with CRC who was diagnosed with pT4aN2bM0, IIIC, and pMMR/MSS after curative surgery in August 2018. Subsequently, he received adjuvant chemotherapy [FOLFOX (folinic acid, fluorouracil, and oxaliplatin) for 5 cycles], first-line treatment (pelvic radiation plus capecitabine), and second-line treatment [TOMIRI (raltitrexed and irinotecan) plus cetuximab for 2 cycles]. Lung, liver, and pelvic cavity metastases worsened in October 2019. He began receiving the fruquintinib plus PD-1 inhibitor (FP) regimen as third-line treatment and after 3 cycles, the size of the lung lesions was significantly reduced and evaluated as partial response (PR), whereas the liver and pelvic cavity lesions remained stable. As of December 2021, he had received a total of 33 courses of FP regimen. In February 2022, liver metastases progressed. In brief, he achieved a long PFS of 28 months and an overall survival (OS) of 40 months from the third-line treatment. Additionally, the patient only experienced mild proteinuria after the combined treatment and tolerated well.

Conclusions

Fruquintinib combined with immunotherapy could exert good therapeutic effects with safety in MSS mCRC patients. And patients with lung metastasis may be the principal beneficiaries.

The Role of TAM Receptors in Bone

The TAM (TYRO3, MERTK, and AXL) family of receptor tyrosine kinases are pleiotropic regulators of adult tissue homeostasis maintaining organ integrity and self-renewal. Disruption of their homeostatic balance fosters pathological conditions like autoinflammatory or degenerative diseases including rheumatoid arthritis, lupus erythematodes, or liver fibrosis. Moreover, TAM receptors exhibit prominent cell-transforming properties, promoting tumor progression, metastasis, and therapy resistance in various cancer entities. Emerging evidence shows that TAM receptors are involved in bone homeostasis by regulating osteoblastic bone formation and osteoclastic bone resorption. Therefore, TAM receptors emerge as new key players of the regulatory cytokine network of osteoblasts and osteoclasts and represent accessible targets for pharmacologic therapy for a broad set of different bone diseases, including primary and metastatic bone tumors, rheumatoid arthritis, or osteoporosis.

Activity of cabozantinib in further line treatment of metastatic clear cell renal cell carcinoma. Real-world experience in a single-center retrospective study

Introduction

Cabozantinib is an oral inhibitor of MET, AXL, and vascular endothelial growth factor receptors. It has an immunomodulatory effect and may influence the tumor's microenvironment and make mutated cells more sensitive to immune-mediated killing. These properties have made cabozantinib an effective drug for first-line or subsequent-line treatment after progression of metastatic renal cell carcinoma (mRCC), even after immunotherapy.

Material and methods

Seventy-one patients with mRCC were treated with second or further lines of cabozantinib at the Department of Genitourinary Oncology, Maria Sklodowska-Curie National Research Institute of Oncology. This study retrospectively evaluated the effectiveness of cabozantinib in subsequent lines of treatment. Progression-free survival (PFS) and overall survival (OS) were the primary endpoints. The best overall response (BOR) to cabozantinib was the secondary endpoint. For this purpose, Cox's proportional hazard model was used.

Results

The median PFS was 11 months (5; 23) and the median OS was 16 months (10; 42) and differed significantly in the second and further lines of treatment. Progression in the second and further lines was observed in 28 (93%) and 27 (66%) patients, respectively (p = 0.006). Partial response as the BOR was observed in one patient (3%) in the second line and 13 patients (32%) in the further lines (p = 0.012).

Conclusions

Cabozantinib has antitumor effects in the second and further lines of treatment. In this study we observed high efficiency of cabozantinib in further lines of treatment.

Tumor immune microenvironment-modulated nanostrategy for the treatment of lung cancer metastasis

ABSTRACT

As one of the most malignant tumors worldwide, lung cancer, fueled by metastasis, has shown rising mortality rates. However, effective clinical strategies aimed at preventing metastasis are lacking owing to its dynamic multi-step, complicated, and progressive nature. Immunotherapy has shown promise in treating cancer metastasis by reversing the immunosuppressive network of the tumor microenvironment. However, drug resistance inevitably develops due to inadequate delivery of immunostimulants and an uncontrolled immune response. Consequently, adverse effects occur, such as autoimmunity, from the non-specific immune activation and non-specific inflammation in off-target organs. Nanocarriers that improve drug solubility, permeability, stability, bioavailability, as well as sustained, controlled, and targeted delivery can effectively overcome drug resistance and enhance the therapeutic effect while reducing adverse effects. In particular, nanomedicine-based immunotherapy can be utilized to target tumor metastasis, presenting a promising therapeutic strategy for lung cancer. Nanotechnology strategies that boost the immunotherapy effect are classified based on the metastatic cascade related to the tumor immune microenvironment; the breaking away of primary tumors, circulating tumor cell dissemination, and premetastatic niche formation cause distant secondary site colonization. In this review, we focus on the opportunities and challenges of integrating immunotherapy with nanoparticle formulation to establish nanotechnology-based immunotherapy by modulating the tumor microenvironment for preclinical and clinical applications in the management of patients with metastatic lung cancer. We also discuss prospects for the emerging field and the clinical translation potential of these techniques.

Gas6 Promotes Microglia Efferocytosis and Suppresses Inflammation Through Activating Axl/Rac1 Signaling in Subarachnoid Hemorrhage Mice

Early brain injury (EBI) following  subarachnoid hemorrhage (SAH) is characterized by rapid development of neuron apoptosis and dysregulated inflammatory response. Microglia efferocytosis plays a critical role in the clearance of apoptotic cells, attenuation of inflammation, and minimizing brain injury in various pathological conditions. Here, using a mouse SAH model, we aim to investigate whether microglia efferocytosis is involved in post-SAH inflammation and to determine the underlying signaling pathway. We hypothesized that TAM receptors and their ligands regulate this process. To prove our hypothesis, the expression and cellular location of TAM (Tyro3, Axl, and Mertk) receptors and their ligands growth arrest-specific 6 (Gas6) and Protein S (ProS1) were examined by PCR, western blots, and fluorescence immunostaining. Thirty minutes after SAH, mice received an intraventricular injection of recombinant Gas6 (rGas6) or recombinant ProS1 (rPros1) and underwent evaluations of inflammatory mediator expression, neurological deficits, and blood-brain barrier integrity at 24 h. Microglia efferocytosis of apoptotic neurons was analyzed in vivo and in vitro. The potential mechanism was determined by inhibiting or knocking down TAM receptors and Rac1 by specific inhibitors or siRNA. SAH induced upregulation of Axl and its ligand Gas6. The administration of rGas6 but not rPros1 promoted microglia efferocytosis, alleviated inflammation, and ameliorated SAH-induced BBB breakdown and neurological deficits. The beneficial effects of rGas6 were arrogated by inhibiting or knocking down Axl and Rac1. We concluded that rGas6 attenuated the development of early brain injury in mice after SAH by facilitating microglia efferocytosis and preventing inflammatory response, which is partly dependent on activation of Axl and Rac1.

Novel roles of PIWI proteins and PIWI-interacting RNAs in human health and diseases

Non-coding RNA has aroused great research interest recently, they play a wide range of biological functions, such as regulating cell cycle, cell proliferation, and intracellular substance metabolism. Piwi-interacting RNAs (piRNAs) are emerging small non-coding RNAs that are 24-31 nucleotides in length. Previous studies on piRNAs were mainly limited to evaluating the binding to the PIWI protein family to play the biological role. However, recent studies have shed more lights on piRNA functions; aberrant piRNAs play unique roles in many human diseases, including diverse lethal cancers. Therefore, understanding the mechanism of piRNAs expression and the specific functional roles of piRNAs in human diseases is crucial for developing its clinical applications. Presently, research on piRNAs mainly focuses on their cancer-specific functions but lacks investigation of their expressions and epigenetic modifications. This review discusses piRNA's biogenesis and functional roles and the recent progress of functions of piRNA/PIWI protein complexes in human diseases. Video Abstract.

Tumor-associated macrophages: an effective player of the tumor microenvironment

Cancer progression is primarily caused by interactions between transformed cells and the components of the tumor microenvironment (TME). TAMs (tumor-associated macrophages) make up the majority of the invading immune components, which are further categorized as anti-tumor M1 and pro-tumor M2 subtypes. While M1 is known to have anti-cancer properties, M2 is recognized to extend a protective role to the tumor. As a result, the tumor manipulates the TME in such a way that it induces macrophage infiltration and M1 to M2 switching bias to secure its survival. This M2-TAM bias in the TME promotes cancer cell proliferation, neoangiogenesis, lymphangiogenesis, epithelial-to-mesenchymal transition, matrix remodeling for metastatic support, and TME manipulation to an immunosuppressive state. TAMs additionally promote the emergence of cancer stem cells (CSCs), which are known for their ability to originate, metastasize, and relapse into tumors. CSCs also help M2-TAM by revealing immune escape and survival strategies during the initiation and relapse phases. This review describes the reasons for immunotherapy failure and, thereby, devises better strategies to impair the tumor-TAM crosstalk. This study will shed light on the understudied TAM-mediated tumor progression and address the much-needed holistic approach to anti-cancer therapy, which encompasses targeting cancer cells, CSCs, and TAMs all at the same time.

Efferocytosis: An accomplice of cancer immune escape

The clearance of apoptotic cells by efferocytes such as macrophages and dendritic cells is termed as "efferocytosis", it plays critical roles in maintaining tissue homeostasis in multicellular organisms. Currently, available studies indicate that efferocytosis-related molecules and pathways are tightly associated with cancer development, metastasis and treatment resistance, efferocytosis also induces an immunosuppressive tumor microenvironment and assists cancer cells escape from immune surveillance. In this study, we reviewed the underlying mechanisms of efferocytosis in mediating the occurrence of cancer immune escape, and then emphatically summarized the strategies of using efferocytosis as therapeutic target to enhance the anti-tumor efficacies of immune checkpoint inhibitors, hoping to provide powerful evidences for more effective therapeutic regimens of malignant tumors.

Imidazopyridine-based kinase inhibitors as potential anticancer agents: A review

Considering the fundamental role of protein kinases in the mechanism of protein phosphorylation in critical cellular processes, their dysregulation, especially in cancers, has underscored their therapeutic relevance. Imidazopyridines represent versatile scaffolds found in abundant bioactive compounds. Given their structural features, imidazopyridines have possessed pivotal potency to interact with different protein kinases, inspiring researchers to carry out numerous structural variations. In this comprehensive review, we encompass an extensive survey of the design and biological evaluations of imidazopyridine-based small molecules as potential agents targeting diverse kinases for anticancer applications. We describe the structural elements critical to inhibitory potency, elucidating their key structure-activity relationships (SAR) and mode of actions, where available. We classify these compounds into two groups: Serine/threonine and Tyrosine inhibitors. By highlighting the promising role of imidazopyridines in kinase inhibition, we aim to facilitate the design and development of more effective, targeted compounds for cancer treatment.

Depletion of slow-cycling PDGFRα+ADAM12+ mesenchymal cells promotes antitumor immunity by restricting macrophage efferocytosis

The capacity to survive and thrive in conditions of limited resources and high inflammation is a major driver of tumor malignancy. Here we identified slow-cycling ADAM12+PDGFRα+ mesenchymal stromal cells (MSCs) induced at the tumor margins in mouse models of melanoma, pancreatic cancer and prostate cancer. Using inducible lineage tracing and transcriptomics, we demonstrated that metabolically altered ADAM12+ MSCs induced pathological angiogenesis and immunosuppression by promoting macrophage efferocytosis and polarization through overexpression of genes such as Gas6, Lgals3 and Csf1. Genetic depletion of ADAM12+ cells restored a functional tumor vasculature, reduced hypoxia and acidosis and normalized CAFs, inducing infiltration of effector T cells and growth inhibition of melanomas and pancreatic neuroendocrine cancer, in a process dependent on TGF-β. In human cancer, ADAM12 stratifies patients with high levels of hypoxia and innate resistance mechanisms, as well as factors associated with a poor prognosis and drug resistance such as AXL. Altogether, our data show that depletion of tumor-induced slow-cycling PDGFRα+ MSCs through ADAM12 restores antitumor immunity.

Inflammation-Responsive Hydrogel Spray for Synergistic Prevention of Traumatic Heterotopic Ossification via Dual-Homeostatic Modulation Strategy

Traumatic heterotopic ossification (THO) represents one of the most prominent contributors to post-traumatic joint dysfunction, which currently lacks an effective and definitive preventative approach. Inflammatory activation due to immune dyshomeostasis during the early stages of trauma is believed to be critical in initiating the THO disease process. This study proposes a dual-homeostatic modulation (DHM) strategy to synergistically prevent THO without compromising normal trauma repair by maintaining immune homeostasis and inducing stem cell homeostasis. A methacrylate-hyaluronic acid-based hydrogel spray device encapsulating a curcumin-loaded zeolitic imidazolate framework-8@ceric oxide (ZIF-8@CeO2, CZC) nanoparticles (CZCH) is designed. Photo-crosslinked CZCH is used to form hydrogel films fleetly in periosteal soft tissues to achieve sustained curcumin and CeO2 nanoparticles release in response to acidity and reactive oxygen species (ROS) in the inflammatory microenvironment. In vitro experiments and RNA-seq results demonstrated that CZCH achieved dual-homeostatic regulation of inflammatory macrophages and stem cells through immune repolarization and enhanced efferocytosis, maintaining immune cell homeostasis and normal differentiation. These findings of the DHM strategy are also validated by establishing THO mice and rat models. In conclusion, the CZCH hydrogel spray developed based on the DHM strategy enables synergistic THO prevention, providing a reference for a standard procedure of clinical operations.

Subverted macrophages in the triple-negative breast cancer ecosystem

Tumor-associated macrophages (TAMs) are the most critical effector cells of innate immunity and the most abundant tumor-infiltrating immune cells. They play a key role in the clearance of apoptotic bodies, regulation of inflammation, and tissue repair to maintain homeostasis in vivo. With the progression of triple-negative breast cancer（TNBC）, TAMs are "subverted" from tumor-promoting immune cells to tumor-promoting immune suppressor cells, which play a significant role in tumor development and are considered potential targets for cancer therapy. Here, we explored how macrophages, as the most important part of the TNBC ecosystem, are "subverted" to drive cancer evolution and the uniqueness of TAMs in TNBC progression and metastasis. Similarly, we discuss the rationale and available evidence for TAMs as potential targets for TNBC therapy.