Autophagic adaptation to oxidative stress alters peritoneal residential macrophage survival and ovarian cancer metastasis

Immunometabolism of tumor-associated macrophages: A therapeutic perspective

Tumor-associated macrophages (TAMs) play a pivotal role in the tumor microenvironment (TME), actively contributing to the formation of an immunosuppressive niche that fosters tumor progression. Consequently, there has been a growing interest in targeting TAMs as a promising avenue for cancer therapy. Recent advances in the field of immunometabolism have shed light on the influence of metabolic adaptations on macrophage physiology in the context of cancer. Here, we discuss the key metabolic pathways that shape the phenotypic diversity of macrophages. We place special emphasis on how metabolic reprogramming impacts the activation status of TAMs and their functions within the TME. Additionally, we explore alterations in TAM metabolism and their effects on phagocytosis, production of cytokines/chemokines and interaction with cytotoxic T and NK immune cells. Moreover, we examine the application of nanomedical approaches to target TAMs and assess the clinical significance of modulating the metabolism of TAMs as a strategy to develop new anti-cancer therapies. Taken together, in this comprehensive review article focusing on TAMs, we provide invaluable insights for the development of effective immunotherapeutic strategies and the enhancement of clinical outcomes for cancer patients.

VSIG4-Expressing Macrophages Contribute to Antiparasitic and Antimetastatic Responses in the Peritoneal Cavity

Large peritoneal macrophages (LPMs) play a role as gatekeepers of peritoneal homeostasis by providing a first line of defense against pathogens. A third of the LPMs express the surface receptor VSIG4, but it is unclear whether these cells differ from their VSIG4-negative counterparts and perform dedicated functions. We demonstrate that VSIG4+, but not VSIG4-, LPMs are in the majority derived from embryonal precursors, and their occurrence is largely independent of sex and microbiota but increases with age. Although their transcriptome and surface proteome are indistinguishable from VSIG4- LPMs at steady-state, VSIG4+ LPMs are superior in phagocytosing S. aureus bioparticles and colorectal carcinoma (CRC) cells. Anti-VSIG4 nanobody constructs that are ADCC-enabled allowed a selective elimination of the VSIG4+ LPM subset without affecting overall LPM abundance. This strategy uncovered a role for VSIG4+ LPMs in lowering the first peak of parasitemia in a Trypanosoma brucei brucei infection model and in reducing CRC outgrowth in the peritoneal cavity, a prime metastatic site in CRC patients. Altogether, our data uncover a protective role for VSIG4+ LPMs in infectious and oncological diseases in the peritoneal cavity.

The interaction between IL-33 and TRIM28 in the regulation of macrophage polarization in an ST2-independent manner

The tumor microenvironment provides optimal condition for the growth of ovarian cancer. Macrophages display a highly functional plasticity to respond various signals. Switching macrophages' phenotype is a potential therapeutic strategy for the treatment of cancer. We used RNA-sequencing(RNA-Seq) and Chromatin immunoprecipitation-sequencing(ChIP-Seq) analyses in bone-marrow-derived macrophages (BMDMs) from wild-type (WT) and its receptor interleukin-1 receptor like-1 (IL1RL1 or ST2) knockout(ST2-/-) mice revealed that the interaction between IL-33 and TRIM28, which plays an antioxidant role, regulates glycolysis in BMDMs by promoting the PI3K/Akt pathway in ST2-independent manner, thereby reducing M2 polarization of macrophages is a way to inhibit ovarian cancer growth.

Harnessing Macrophages in Cancer Therapy: from Immune Modulators to Therapeutic Targets

Macrophages, as the predominant phagocytes, play an essential role in pathogens defense and tissue homeostasis maintenance. In the context of cancer, tumor-associated macrophages (TAMs) have evolved into cunning actors involved in angiogenesis, cancer cell proliferation and metastasis, as well as the construction of immunosuppressive microenvironment. Once properly activated, macrophages can kill tumor cells directly through phagocytosis or attack tumor cells indirectly by stimulating innate and adaptive immunity. Thus, the prospect of targeting TAMs has sparked significant interest and emerged as a promising strategy in immunotherapy. In this review, we summarize the diverse roles and underlying mechanisms of TAMs in cancer development and immunity and highlight the TAM-based therapeutic strategies such as inhibiting macrophage recruitment, inhibiting the differentiation reprogramming of TAMs, blocking phagocytotic checkpoints, inducing trained macrophages, as well as the potential of engineered CAR-armed macrophages in cancer therapy.

VSIG4+ tumor-associated macrophages mediate neutrophil infiltration and impair antigen-specific immunity in aggressive cancers through epigenetic regulation of SPP1

V-set and immunoglobulin domain-containing 4 (VSIG4) positive tumor-associated macrophage (VSIG4+ TAM) is an immunosuppressive subpopulation newly identified in aggressive cancers. However, the mechanism how VSIG4+ TAMs mediate immune evasion in aggressive cancers have not been fully elucidated. In our study, we found targeting VSIG4+ TAMs by VSIG4 deficiency or blockade remarkably limited tumor growth and metastasis, especially those derived from anaplastic thyroid cancer (ATC) and pancreatic cancer, two extremely aggressive types. Moreover, the combination of VSIG4 blockade with a BRAF inhibitor synergistically enhanced anti-tumor activity in ATC-tumor bearing mice. VSIG4 deficiency recovered the antigen presentation (B2m, H2-k1, H2-d1) of TAMs and activated antigen-specific CD8+ T cells by promoting their in vivo proliferation and intratumoral infiltration. Notably, loss of VSIG4 in TAMs significantly reduced the production of lactate and histone H3 lysine 18 lactylation, resulting the decreased transcription of SPP1 mediated by STAT3, which collectively disrupted the cell-cell interactions between TAMs and neutrophils. Further combination of VSIG4 with SPP1 blockade synergistically boosted anti-tumor activity. Overall, our studies demonstrate the epigenetic regulation function of VSIG4 confers on TAMs an alternative pattern, beyond the checkpoint role of VSIG4, to shape the immunosuppressive tumor microenvironment and impair antigen-specific immunity against aggressive cancers.

Epidermal maintenance of Langerhans cells relies on autophagy-regulated lipid metabolism

Macroautophagy (often-named autophagy), a catabolic process involving autophagy-related (Atg) genes, prevents the accumulation of harmful cytoplasmic components and mobilizes energy reserves in long-lived and self-renewing cells. Autophagy deficiency affects antigen presentation in conventional dendritic cells (DCs) without impacting their survival. However, previous studies did not address epidermal Langerhans cells (LCs). Here, we demonstrate that deletion of either Atg5 or Atg7 in LCs leads to their gradual depletion. ATG5-deficient LCs showed metabolic dysregulation and accumulated neutral lipids. Despite increased mitochondrial respiratory capacity, they were unable to process lipids, eventually leading them to ferroptosis. Finally, metabolically impaired LCs upregulated proinflammatory transcripts and showed decreased expression of neuronal interaction receptors. Altogether, autophagy represents a critical regulator of lipid storage and metabolism in LCs, allowing their maintenance in the epidermis.

The interplay between probiotics and host autophagy: mechanisms of action and emerging insights

Autophagy, a lysosome-dependent protein degradation mechanism, is a highly conserved catabolic process seen in all eukaryotes. This cell protection system, which is present in all tissues and functions at a basic level, can be up- or downregulated in response to various stresses. A disruption in the natural route of the autophagy process is frequently followed by an interruption in the inherent operation of the body's cells and organs. Probiotics are live bacteria that protect the host through various mechanisms. One of the processes through which probiotics exert their beneficial effects on various cells and tissues is autophagy. Autophagy can assist in maintaining host homeostasis by stimulating the immune system and affecting numerous physiological and pathological responses. In this review, we particularly focus on autophagy impairments occurring in several human illnesses and investigate how probiotics affect the autophagy process under various circumstances.Abbreviation: AD: Alzheimer disease; AKT: AKT serine/threonine kinase; AMPK: 5'AMP-activated protein kinase; ATG: autophagy related; CCl4: carbon tetrachloride; CFS: cell-free supernatant; CMA: chaperone-mediated autophagy; CRC: colorectal cancer; EPS: L. plantarum H31 exopolysaccharide; HD: Huntington disease; HFD: high-fat diet; HPV: human papillomavirus; IFNG/IFN-γ: interferon gamma; IL6: interleukin 6; LGG: L. rhamnosus GG; LPS: lipopolysaccharide; MTOR: mechanistic target of rapamycin kinase; MTORC1: MTOR complex 1; NAFLD: non-alcoholic fatty liver disease; NASH: non-alcoholic steatohepatitis; PD: Parkinson disease; Pg3G: pelargonidin-3-O-glucoside; PI3K: phosphoinositide 3-kinase; PolyQ: polyglutamine; ROS: reactive oxygen species; SCFAs: short-chain fatty acids; SLAB51: a novel formulation of lactic acid bacteria and bifidobacteria; Slp: surface layer protein (of acidophilus NCFM); SNCA: synuclein alpha; ULK1: unc-51 like autophagy-activating kinase 1; YB: B. longum subsp. infantis YB0411; YFP: yeast fermentate prebiotic.

Linking macrophage metabolism to function in the tumor microenvironment

Macrophages are present at high frequency in most solid tumor types, and their relative abundance negatively correlates with therapy responses and survival outcomes. Tissue-resident macrophages are highly tuned to integrate tissue niche signals, and multiple factors within the idiosyncratic tumor microenvironment (TME) drive macrophages to polarization states that favor immune suppression, tumor growth and metastasis. These diverse functional states are underpinned by extensive and complex rewiring of tumor-associated macrophage (TAM) metabolism. In this Review, we link distinct and specific macrophage functional states within the TME to major, phenotype-sustaining metabolic programs and discuss the metabolic impact of macrophage-modulating therapeutic interventions.

Molecular regulation of mitophagy signaling in tumor microenvironment and its targeting for cancer therapy

Aberrations emerging in mitochondrial homeostasis are restrained by mitophagy to control mitochondrial integrity, bioenergetics signaling, metabolism, oxidative stress, and apoptosis. The mitophagy-accompanied mitochondrial processes that occur in a dysregulated condition act as drivers for cancer occurrence. In addition, the enigmatic nature of mitophagy in cancer cells modulates the cellular proteome, creating challenges for therapeutic interventions. Several reports found the role of cellular signaling pathways in cancer to modulate mitophagy to mitigate stress, immune checkpoints, energy demand, and cell death. Thus, targeting mitophagy to hinder oncogenic intracellular signaling by promoting apoptosis, in hindsight, might have an edge against cancer. This review highlights the receptors and adaptors, and the involvement of many proteins in mitophagy and their role in oncogenesis. It also provides insight into using mitophagy as a potential target for therapeutic intervention in various cancer types.

RBM47 promotes cell proliferation and immune evasion by upregulating PDIA6: a novel mechanism of pancreatic cancer progression

BACKGROUND

Pancreatic cancer (PC) is a lethal malignancy characterized by poor prognosis and high mortality. We found the highly expressed RNA-binding motif protein 47 (RBM47) in PC progression. The RBM47 expression was negatively correlated with natural killer (NK) cell infiltrate in PC. Moreover, RBM47 was predicted to bind to the 3'-UTR region of Protein Disulfide Isomerase Family A Member 6 (PDIA6), an oncogene of the development of PC. Therefore, we supposed that RBM47 might affect PC progression by regulating PDIA6.

METHODS

Bioinformatics analysis was performed to screen the candidate gene affecting PC progression using public databases. Loss- and gain-of-function effects of RBM47 on cell proliferation, tumor growth, and immune evasion were determined by CCK-8, EdU incorporation, colony formation assays, the xenogeneic tumor model, and co-culture system of PC and NK-92 cells. RBM47-RNA immunoprecipitation (RIP) followed by PCR and dual luciferase reporter assay were used to detect whether RBM47 could interact with the PDIA6 mRNA and how RBM47 would regulate the transcriptional activity of PDIA6, respectively. Simultaneous overexpression of PDIA6 in RBM47 knockdown PC cells was conducted to clarify whether PDIA6 would mediated effects of RBM47. Given the important role of cellular metabolism in cells proliferation and immune evasion, PC cells with RBM47 knockdown were subjected to metabolomics analysis to further investigate how RBM47 regulate PC progression.

RESULTS

RBM47 overexpression drove PC progression by promoting cell proliferation and xenografted tumor growth. Consistently, our results showed that RBM47 overexpression weakened sensitivity of PC cells to cytotoxic NK cells. However, RBM47 knockdown exhibited the opposite effects on proliferation and immune evasion of PC cells. RBM47 was able to bind to the 3'-UTR region of PDIA6, maintained PDIA6 mRNA stability, and increased the PDIA6 expression in PC cells. Rescue experiments supported that PDIA6 overexpression reversed the suppressing effects of RBM47 knockdown on cell proliferation and immune evasion. RBM47 knockdown significantly changed metabolites of PC cells.

CONCLUSIONS

In summary, our findings demonstrate that RBM47 contributes to PC progression, which might be mediated by the upregulated PDIA6 expression and the altered cellular metabolites in PC cells, offering a potential therapeutic target for PC treatment.

Reactive oxygen species: Janus-faced molecules in the era of modern cancer therapy

Oxidative stress, that is, an unbalanced increase in reactive oxygen species (ROS), contributes to tumor-induced immune suppression and limits the efficacy of immunotherapy. Cancer cells have inherently increased ROS production, intracellularly through metabolic perturbations and extracellularly through activation of NADPH oxidases, which promotes cancer progression. Further increased ROS production or impaired antioxidant systems, induced, for example, by chemotherapy or radiotherapy, can preferentially kill cancer cells over healthy cells. Inflammatory cell-derived ROS mediate immunosuppressive effects of myeloid-derived suppressor cells and activated granulocytes, hampering antitumor effector cells such as T cells and natural killer (NK) cells. Cancer therapies modulating ROS levels in tumors may thus have entirely different consequences when targeting cancer cells versus immune cells. Here we discuss the possibility of developing more efficient cancer therapies based on reduction-oxidation modulation, as either monotherapies or in combination with immunotherapy. Short-term, systemic administration of antioxidants or drugs blocking ROS production can boost the immune system and act in synergy with immunotherapy. However, prolonged use of antioxidants can instead enhance tumor progression. Alternatives to systemic antioxidant administration are under development where gene-modified or activated T cells and NK cells are shielded ex vivo against the harmful effects of ROS before the infusion to patients with cancer.

Mitophagy in gynecological malignancies: roles, advances, and therapeutic potential

Mitophagy is a process in which impaired or dysfunctional mitochondria are selectively eliminated through the autophagy mechanism to maintain mitochondrial quality control and cellular homeostasis. Based on specific target signals, several mitophagy processes have been identified. Defects in mitophagy are associated with various pathological conditions, including neurodegenerative disorders, cardiovascular diseases, metabolic diseases, and cancer. Mitophagy has been shown to play a critical role in the pathogenesis of gynecological malignancies and the development of drug resistance. In this review, we have summarized and discussed the role and recent advances in understanding the therapeutic potential of mitophagy in the development of gynecological malignancies. Therefore, the valuable insights provided in this review may serve as a basis for further studies that contribute to the development of novel treatment strategies and improved patient outcomes.

Myeloid activation clears ascites and reveals IL27-dependent regression of metastatic ovarian cancer

Patients with metastatic ovarian cancer (OvCa) have a 5-year survival rate of <30% due to the persisting dissemination of chemoresistant cells in the peritoneal fluid and the immunosuppressive microenvironment in the peritoneal cavity. Here, we report that intraperitoneal administration of β-glucan and IFNγ (BI) induced robust tumor regression in clinically relevant models of metastatic OvCa. BI induced tumor regression by controlling fluid tumor burden and activating localized antitumor immunity. β-glucan alone cleared ascites and eliminated fluid tumor cells by inducing intraperitoneal clotting in the fluid and Dectin-1-Syk-dependent NETosis in the omentum. In omentum tumors, BI expanded a novel subset of immunostimulatory IL27+ macrophages and neutralizing IL27 impaired BI efficacy in vivo. Moreover, BI directly induced IL27 secretion in macrophages where single agent treatment did not. Finally, BI extended mouse survival in a chemoresistant model and significantly improved chemotherapy response in a chemo-sensitive model. In summary, we propose a new therapeutic strategy for the treatment of metastatic OvCa.

CD47 predominates over CD24 as a macrophage immune checkpoint in cancer

Macrophages hold tremendous promise as effectors of cancer immunotherapy, but the best strategies to provoke these cells to attack tumors remain unknown. Here, we evaluated the therapeutic potential of targeting two distinct macrophage immune checkpoints: CD47 and CD24. We found that antibodies targeting these antigens could elicit maximal levels of phagocytosis when combined together in vitro. However, to our surprise, via unbiased genome-wide CRISPR screens, we found that CD24 primarily acts as a target of opsonization rather than an immune checkpoint. In a series of in vitro and in vivo genetic validation studies, we found that CD24 was neither necessary nor sufficient to protect cancer cells from macrophage phagocytosis in most mouse and human tumor models. Instead, anti-CD24 antibodies exhibit robust Fc-dependent activity, and as a consequence, they cause significant on-target hematologic toxicity in mice. To overcome these challenges and leverage our findings for therapeutic purposes, we engineered a collection of 77 novel bispecific antibodies that bind to a tumor antigen with one arm and engage macrophages with the second arm. We discovered multiple novel bispecifics that maximally activate macrophage-mediated cytotoxicity and reduce binding to healthy blood cells, including bispecifics targeting macrophage immune checkpoint molecules in combination with EGFR, TROP2, and CD71. Overall, our findings indicate that CD47 predominates over CD24 as a macrophage immune checkpoint in cancer, and that the novel bispecifics we created may be optimal immunotherapies to direct myeloid cells to eradicate solid tumors.

Macrophage diversity in cancer dissemination and metastasis

Invasion and metastasis are hallmarks of cancer. In addition to the well-recognized hematogenous and lymphatic pathways of metastasis, cancer cell dissemination can occur via the transcoelomic and perineural routes, which are typical of ovarian and pancreatic cancer, respectively. Macrophages are a universal major component of the tumor microenvironment and, in established tumors, promote growth and dissemination to secondary sites. Here, we review the role of tumor-associated macrophages (TAMs) in cancer cell dissemination and metastasis, emphasizing the diversity of myeloid cells in different tissue contexts (lungs, liver, brain, bone, peritoneal cavity, nerves). The generally used models of lung metastasis fail to capture the diversity of pathways and tissue microenvironments. A better understanding of TAM diversity in different tissue contexts may pave the way for tailored diagnostic and therapeutic approaches.

Tissue-Resident Macrophages in Cancer: Friend or Foe?

INTRODUCTION

Macrophages are essential in maintaining homeostasis, combating infections, and influencing the process of various diseases, including cancer. Macrophages originate from diverse lineages: Notably, tissue-resident macrophages (TRMs) differ from hematopoietic stem cells and circulating monocyte-derived macrophages based on genetics, development, and function. Therefore, understanding the recruited and TRM populations is crucial for investigating disease processes.

METHODS

By searching literature databses, we summarized recent relevant studies. Research has shown that tumor-associated macrophages (TAMs) of distinct origins accumulate in tumor microenvironment (TME), with TRM-derived TAMs closely resembling gene signatures of normal TRMs.

RESULTS

Recent studies have revealed that TRMs play a crucial role in cancer progression. However, organ-specific effects complicate TRM investigations. Nonetheless, the precise involvement of TRMs in tumors is unclear. This review explores the multifaceted roles of TRMs in cancer, presenting insights into their origins, proliferation, the latest research methodologies, their impact across various tumor sites, their potential and strategies as therapeutic targets, interactions with other cells within the TME, and the internal heterogeneity of TRMs.

CONCLUSIONS

We believe that a comprehensive understanding of the multifaceted roles of TRMs will pave the way for targeted TRM therapies in the treatment of cancer.

Identification and validation of efferocytosis-related biomarkers for the diagnosis of metabolic dysfunction-associated steatohepatitis based on bioinformatics analysis and machine learning

Background

Metabolic dysfunction-associated steatohepatitis (MASH) is a highly prevalent liver disease globally, with a significant risk of progressing to cirrhosis and even liver cancer. Efferocytosis, a process implicated in a broad spectrum of chronic inflammatory disorders, has been reported to be associated with the pathogenesis of MASH; however, its precise role remains obscure. Thus, we aimed to identify and validate efferocytosis linked signatures for detection of MASH.

Methods

We retrieved gene expression patterns of MASH from the GEO database and then focused on assessing the differential expression of efferocytosis-related genes (EFRGs) between MASH and control groups. This analysis was followed by a series of in-depth investigations, including protein-protein interaction (PPI), correlation analysis, and functional enrichment analysis, to uncover the molecular interactions and pathways at play. To screen for biomarkers for diagnosis, we applied machine learning algorithm to identify hub genes and constructed a clinical predictive model. Additionally, we conducted immune infiltration and single-cell transcriptome analyses in both MASH and control samples, providing insights into the immune cell landscape and cellular heterogeneity in these conditions.

Results

This research pinpointed 39 genes exhibiting a robust correlation with efferocytosis in MASH. Among these, five potential diagnostic biomarkers-TREM2, TIMD4, STAB1, C1QC, and DYNLT1-were screened using two distinct machine learning models. Subsequent external validation and animal experimentation validated the upregulation of TREM2 and downregulation of TIMD4 in MASH samples. Notably, both TREM2 and TIMD4 demonstrated area under the curve (AUC) values exceeding 0.9, underscoring their significant potential in facilitating the diagnosis of MASH.

Conclusion

Our study comprehensively elucidated the relationship between MASH and efferocytosis, constructing a favorable diagnostic model. Furthermore, we identified potential therapeutic targets for MASH treatment and offered novel insights into unraveling the underlying mechanisms of this disease.

Advances in natural products modulating autophagy influenced by cellular stress conditions and their anticancer roles in the treatment of ovarian cancer

Autophagy is a conservative catabolic process that typically serves a cell-protective function. Under stress conditions, when the cellular environment becomes unstable, autophagy is activated as an adaptive response for self-protection. Autophagy delivers damaged cellular components to lysosomes for degradation and recycling, thereby providing essential nutrients for cell survival. However, this function of promoting cell survival under stress conditions often leads to malignant progression and chemotherapy resistance in cancer. Consequently, autophagy is considered a potential target for cancer therapy. Herein, we aim to review how natural products act as key modulators of autophagy by regulating cellular stress conditions. We revisit various stressors, including starvation, hypoxia, endoplasmic reticulum stress, and oxidative stress, and their regulatory relationship with autophagy, focusing on recent advances in ovarian cancer research. Additionally, we explore how polyphenolic compounds, flavonoids, alkaloids, terpenoids, and other natural products modulate autophagy mediated by stress responses, affecting the malignant biological behavior of cancer. Furthermore, we discuss their roles in ovarian cancer therapy. This review emphasizes the importance of natural products as valuable resources in cancer therapeutics, highlighting the need for further exploration of their potential in regulating autophagy. Moreover, it provides novel insights and potential therapeutic strategies in ovarian cancer by utilizing natural products to modulate autophagy.

PTPRC Inhibits Ferroptosis of Osteosarcoma Cells via Blocking TFEB/FTH1 Signaling

Protein tyrosine phosphatase receptor type C (PTPRC) is reported to function as an oncogenic role in various cancer. However, the studies on the roles of PTPRC in osteosarcoma (OS) are limited. This study aimed to explore the potentials of PTPRC in OS. mRNA levels were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Protein expression was detected by western blot. Lysosome biogenesis was determined using immunofluorescence. The binding sites of transcription factor EB (TFEB) on the promoter of ferritin heavy chain 1 (FTH1) were predicted by the online dataset JASPAR and confirmed by luciferase and chromatin immunoprecipitation (ChIP) assays. Cell death was determined using propidium iodide (PI) and TdT-mediated dUTP nick-end labeling (TUNEL) staining. The results showed that PTPRC was significantly overexpressed in OS tissues and cells. PTPRC knockdown promoted the phosphorylation and nuclear translocation of TFEB. Moreover, PTPRC knockdown markedly promoted lysosome biogenesis and the accumulation of ferrous ion (Fe2+), whereas decreased the release of glutathione (GSH). Besides, PTPRC knockdown significantly promoted autophagy and downregulated mRNA expression of FTH1 and ferritin light chain (FTL). Additionally, TFEB transcriptionally inactivated FTH1. PTPRC knockdown significantly promoted the ferroptosis of OS cells, which was markedly alleviated by TFEB shRNA. Taken together, PTPRC knockdown-mediated TFEB phosphorylation and translocation dramatically promoted lysosome biogenesis, ferritinophagy, as well as the ferroptosis of OS cells via regulating FTH1/FTL signaling. Therefore, PTPRC/TFEB/FTH1 signaling may be a potential target for OS.

A new perspective on the therapeutic potential of tumor metastasis: targeting the metabolic interactions between TAMs and tumor cells

Tumor-associated macrophages (TAMs) undergo metabolic reprogramming, encompassing glucose, amino acid, fatty acid metabolism, tricarboxylic acid (TCA) cycle, purine metabolism, and autophagy, within the tumor microenvironment (TME). The metabolic interdependencies between TAMs and tumor cells critically influence macrophage recruitment, differentiation, M2 polarization, and secretion of epithelial-mesenchymal transition (EMT)-related factors, thereby activating intratumoral EMT pathways and enhancing tumor cell invasion and metastasis. Tumor cell metabolic alterations, including hypoxia, metabolite secretion, aerobic metabolism, and autophagy, affect the TME's metabolic landscape, driving macrophage recruitment, differentiation, M2 polarization, and metabolic reprogramming, ultimately facilitating EMT, invasion, and metastasis. Additionally, macrophages can induce tumor cell EMT by reprogramming their aerobic glycolysis. Recent experimental and clinical studies have focused on the metabolic interactions between macrophages and tumor cells to control metastasis and inhibit tumor progression. This review highlights the regulatory role of TAM-tumor cell metabolic codependencies in EMT, offering valuable insights for TAM-targeted therapies in highly metastatic tumors. Modulating the metabolic interplay between tumors and TAMs represents a promising therapeutic strategy for treating patients with metastatic cancers.

Immunometabolism in cancer: A journey into innate and adaptive cells

In recent years, mostly spanning the past decade, the concept of immunometabolism has ushered with a novel perspective on carcinogenesis, tumor progression, and tumor response to therapy. It has become clear that the metabolic state of immune cells plays a significant role in shaping their antitumor or protumor activities within the cancer microenvironment. Consequently, the examination of tumor metabolic heterogeneity, including an exploration of immunometabolism, proves indispensable for enhancing prognostic tools and advancing the quest for personalized treatments. Here we have delved into how metabolic reprogramming profoundly influences the acquisition and maintenance of functional states, spanning from effector and cytotoxic profiles to regulatory and immunosuppressive phenotypes in both innate and adaptive immunity. These alterations wield considerable influence over tumor evolution and affect the outcome of cancer. Furthermore, we explore some of the cellular signaling mechanisms that underpin the metabolic and phenotypic flexibility of immune cells in response to external stimuli.

Macrophages and tertiary lymphoid structures as indicators of prognosis and therapeutic response in cancer patients

Tertiary lymphoid structures (TLS) can reflect cancer prognosis and clinical outcomes in various tumour tissues. Tumour-associated macrophages (TAMs) are indispensable components of the tumour microenvironment and play crucial roles in tumour development and immunotherapy. TAMs are associated with TLS induction via the modulation of the T cell response, which is a major component of the TLS. Despite their important roles in cancer immunology, the subtypes of TAMs that influence TLS and their correlation with prognosis are not completely understood. Here, we provide novel insights into the role of TAMs in regulating TLS formation. Furthermore, we discuss the prognostic value of these TAM subtypes and TLS, as well as the current antitumour therapies for inducing TLS. This study highlights an entirely new field of TLS regulation that may lead to the development of an innovative perspective on immunotherapy for cancer treatment.

The involvement of peritoneal GATA6+ macrophages in the pathogenesis of endometriosis

Endometriosis is a chronic inflammatory disease that causes debilitating pelvic pain in women. Macrophages are considered to be key players in promoting disease progression, as abundant macrophages are present in ectopic lesions and elevated in the peritoneum. In the present study, we examined the role of GATA6+ peritoneal macrophages on endometriosis-associated hyperalgesia using mice with a specific myeloid deficiency of GATA6. Lesion induction induced the disappearance of TIM4hi MHCIIlo residential macrophages and the influx of increased Ly6C+ monocytes and TIM4lo MHCIIhi macrophages. The recruitment of MHCIIhi inflammatory macrophages was extensive in Mac Gata6 KO mice due to the severe disappearance of TIM4hi MHCIIlo residential macrophages. Ki67 expression confirmed GATA6-dependent proliferative ability, showing different proliferative phenotypes of TIM4+ residential macrophages in Gata6f/f and Mac Gata6 KO mice. Peritoneal proinflammatory cytokines were elevated after lesion induction. When cytokine levels were compared between Gata6f/f and Mac Gata6 KO mice, TNFα at day 21 in Gata6f/f mice was higher than in Mac Gata6 KO mice. Lesion induction increased both abdominal and hind paw sensitivities. Gata6f/f mice tended to show higher sensitivity in the abdomen after day 21. Elevated expression of TRPV1 and CGRP was observed in the dorsal root ganglia after ELL induction in Gata6f/f mice until days 21 and 42, respectively. These results support that peritoneal GATA6+ macrophages are involved in the recruitment and reprogramming of monocyte-derived macrophages. The extensive recruitment of monocyte-derived macrophages in Mac Gata6 KO mice might protect against inflammatory stimuli during the resolution phase, whereas GATA6 deficiency did not affect lesion initiation and establishment at the acute phase of inflammation. GATA6+ residential macrophages act to sustain local inflammation in the peritoneum and sensitivities in the neurons, reflecting endometriosis-associated hyperalgesia.

From monocyte-derived macrophages to resident macrophages-how metabolism leads their way in cancer

Macrophages are innate immune cells that play key roles during both homeostasis and disease. Depending on the microenvironmental cues sensed in different tissues, macrophages are known to acquire specific phenotypes and exhibit unique features that, ultimately, orchestrate tissue homeostasis, defense, and repair. Within the tumor microenvironment, macrophages are referred to as tumor-associated macrophages (TAMs) and constitute a heterogeneous population. Like their tissue resident counterpart, TAMs are plastic and can switch function and phenotype according to the niche-derived stimuli sensed. While changes in TAM phenotype are known to be accompanied by adaptive alterations in their cell metabolism, it is reported that metabolic reprogramming of macrophages can dictate their activation state and function. In line with these observations, recent research efforts have been focused on defining the metabolic traits of TAM subsets in different tumor malignancies and understanding their role in cancer progression and metastasis formation. This knowledge will pave the way to novel therapeutic strategies tailored to cancer subtype-specific metabolic landscapes. This review outlines the metabolic characteristics of distinct TAM subsets and their implications in tumorigenesis across multiple cancer types.

Intraperitoneal activation of myeloid cells clears ascites and reveals IL27-dependent regression of metastatic ovarian cancer

Patients with metastatic ovarian cancer (OvCa) have a 5-year survival rate of less than 30% due to persisting dissemination of chemoresistant cells in the peritoneal fluid and the immunosuppressive microenvironment in the peritoneal cavity. Here, we report that intraperitoneal administration of β-glucan and IFNγ (BI) induced robust tumor regression in clinically relevant models of metastatic OvCa. BI induced tumor regression by controlling fluid tumor burden and activating localized antitumor immunity. β-glucan alone cleared ascites and eliminated fluid tumor cells by inducing intraperitoneal clotting in the fluid and Dectin-1-Syk-dependent NETosis in the omentum. In omentum tumors, BI expanded a novel subset of immunostimulatory IL27+ macrophages and neutralizing IL27 impaired BI efficacy in vivo. Moreover, BI directly induced IL27 secretion in macrophages where single agent treatment did not. Finally, BI extended mouse survival in a chemoresistant model and significantly improved chemotherapy response in a chemo-sensitive model. In summary, we propose a new therapeutic strategy for the treatment of metastatic OvCa.

Recent advances in understanding the immune microenvironment in ovarian cancer

The occurrence of ovarian cancer (OC) is a major factor in women's mortality rates. Despite progress in medical treatments, like new drugs targeting homologous recombination deficiency, survival rates for OC patients are still not ideal. The tumor microenvironment (TME) includes cancer cells, fibroblasts linked to cancer (CAFs), immune-inflammatory cells, and the substances these cells secrete, along with non-cellular components in the extracellular matrix (ECM). First, the TME mainly plays a role in inhibiting tumor growth and protecting normal cell survival. As tumors progress, the TME gradually becomes a place to promote tumor cell progression. Immune cells in the TME have attracted much attention as targets for immunotherapy. Immune checkpoint inhibitor (ICI) therapy has the potential to regulate the TME, suppressing factors that facilitate tumor advancement, reactivating immune cells, managing tumor growth, and extending the survival of patients with advanced cancer. This review presents an outline of current studies on the distinct cellular elements within the OC TME, detailing their main functions and possible signaling pathways. Additionally, we examine immunotherapy rechallenge in OC, with a specific emphasis on the biological reasons behind resistance to ICIs.

Redox regulation of macrophages

Redox signaling, a mode of signal transduction that involves the transfer of electrons from a nucleophilic to electrophilic molecule, has emerged as an essential regulator of inflammatory macrophages. Redox reactions are driven by reactive oxygen/nitrogen species (ROS and RNS) and redox-sensitive metabolites such as fumarate and itaconate, which can post-translationally modify specific cysteine residues in target proteins. In the past decade our understanding of how ROS, RNS, and redox-sensitive metabolites control macrophage function has expanded dramatically. In this review, we discuss the latest evidence of how ROS, RNS, and metabolites regulate macrophage function and how this is dysregulated with disease. We highlight the key tools to assess redox signaling and important questions that remain.

Mitochondrial quality control in human health and disease

Mitochondria, the most crucial energy-generating organelles in eukaryotic cells, play a pivotal role in regulating energy metabolism. However, their significance extends beyond this, as they are also indispensable in vital life processes such as cell proliferation, differentiation, immune responses, and redox balance. In response to various physiological signals or external stimuli, a sophisticated mitochondrial quality control (MQC) mechanism has evolved, encompassing key processes like mitochondrial biogenesis, mitochondrial dynamics, and mitophagy, which have garnered increasing attention from researchers to unveil their specific molecular mechanisms. In this review, we present a comprehensive summary of the primary mechanisms and functions of key regulators involved in major components of MQC. Furthermore, the critical physiological functions regulated by MQC and its diverse roles in the progression of various systemic diseases have been described in detail. We also discuss agonists or antagonists targeting MQC, aiming to explore potential therapeutic and research prospects by enhancing MQC to stabilize mitochondrial function.

Comprehensive analysis and experimental verification of the mechanism of action of T cell-mediated tumor-killing related genes in Colon adenocarcinoma

BACKGROUND

Colorectal cancer (CRC) is a prevalent malignancy of the digestive tract. A new prognostic scoring model for colon adenocarcinoma (COAD) is developed in this study based on the genes involved in tumor cell-mediated killing of T cells (GSTTKs), accurately stratifying COAD patients, thus improving the current status of personalized treatment.

METHOD

The GEO and TCGA databases served as the sources of the data for the COAD cohort. This study identified GSTTKs-related genes in COAD through single-factor Cox analysis. These genes were used to categorize COAD patients into several subtypes via unsupervised clustering analysis. The biological pathways and tumor microenvironments of different subgroups were compared. We performed intersection analysis between different subtypes to obtain intersection genes. Single-factor Cox regression analysis and Lasso-Cox analysis were conducted to establish clinical prognostic models. Two methods are used to assess the accuracy of model predictions: ROC and Kaplan-Meier analysis. Next, the prediction model was further validated in the validation cohort. Differential immune cell infiltration between various risk categories was identified via single sample gene set enrichment analysis (ssGSEA). The COAD model's gene expression was validated via single-cell data analysis and experiments.

RESULT

We established two distinct GSTTKs-related subtypes. Biological processes and immune cell tumor invasion differed significantly between various subtypes. Clinical prognostic models were created using five GSTTKs-related genes. The model's risk score independently served as a prognostic factor. COAD patients were classified as low- or high-risk depending on their risk scores. Patients in the low-risk category recorded a greater chance of surviving. The outcomes from the validation cohort match those from the training set. Risk scores and several tumor-infiltrating immune cells were strongly correlated, according to ssGSEA. Single-cell data illustrated that the model's genes were linked to several immune cells. The experimental results demonstrated a significant increase in the expression of HOXC6 in colon cancer tissue.

CONCLUSION

Our research findings established a new gene signature for COAD. This gene signature helps to accurately stratify the risk of COAD patients and improve the current status of individualized care.

Tim4 enables large peritoneal macrophages to cross-present tumor antigens at early stages of tumorigenesis

Receptors controlling the cross-presentation of tumor antigens by macrophage subsets in cancer tissues are poorly explored. Here, we show that TIM4+ large peritoneal macrophages efficiently capture and cross-present tumor-associated antigens at early stages of peritoneal infiltration by ovarian cancer cells. The phosphatidylserine (PS) receptor TIM4 promotes maximal uptake of dead cells or PS-coated artificial targets and triggers inflammatory and metabolic gene programs in combination with cytoskeletal remodeling and upregulation of transcriptional signatures related to antigen processing. At the cellular level, TIM4-mediated engulfment induces nucleation of F-actin around nascent phagosomes, delaying the recruitment of vacuolar ATPase, acidification, and cargo degradation. In vivo, TIM4 deletion blunts induction of early anti-tumoral effector CD8 T cells and accelerates the progression of ovarian tumors. We conclude that TIM4-mediated uptake drives the formation of specialized phagosomes that prolong the integrity of ingested antigens and facilitate cross-presentation, contributing to immune surveillance of the peritoneum.

Gene expression prognostic of early relapse risk in low-risk B-cell acute lymphoblastic leukaemia in children

ETV6::RUNX1 is the most common fusion gene in childhood acute lymphoblastic leukaemia (ALL) and is associated with favorable outcomes, especially in low-risk children. However, as many as 10% of children relapse within 3 years, and such early relapses have poor survival. Identifying children at risk for early relapse is an important challenge. We interrogated data from 87 children with low-risk ETV6::RUNX1-positive B-cell ALL and with available preserved bone marrow samples (discovery cohort). We profiled somatic point mutations in a panel of 559 genes and genome-wide transcriptome and single-nucleotide variants. We found high TIMD4 expression (> 85th-percentile value) at diagnosis was the most important independent prognostic factor of early relapse (hazard ratio [HR] = 5.07 [1.76, 14.62]; p = 0.03). In an independent validation cohort of low-risk ETV6::RUNX1-positive B-cell ALL (N = 68) high TIMD4 expression at diagnosis had an HR = 4.78 [1.07, 21.36] (p = 0.04) for early relapse. In another validation cohort including 78 children with low-risk ETV6::RUNX1-negative B-cell ALL, high TIMD4 expression at diagnosis had an HR = 3.93 [1.31, 11.79] (p = 0.01). Our results suggest high TIMD4 expression at diagnosis in low-risk B-cell ALL in children might be associated with high risk for early relapse.

PAD4 controls tumor immunity via restraining the MHC class II machinery in macrophages

Tumor-associated macrophages (TAMs) shape tumor immunity and therapeutic efficacy. However, it is poorly understood whether and how post-translational modifications (PTMs) intrinsically affect the phenotype and function of TAMs. Here, we reveal that peptidylarginine deiminase 4 (PAD4) exhibits the highest expression among common PTM enzymes in TAMs and negatively correlates with the clinical response to immune checkpoint blockade. Genetic and pharmacological inhibition of PAD4 in macrophages prevents tumor progression in tumor-bearing mouse models, accompanied by an increase in macrophage major histocompatibility complex (MHC) class II expression and T cell effector function. Mechanistically, PAD4 citrullinates STAT1 at arginine 121, thereby promoting the interaction between STAT1 and protein inhibitor of activated STAT1 (PIAS1), and the loss of PAD4 abolishes this interaction, ablating the inhibitory role of PIAS1 in the expression of MHC class II machinery in macrophages and enhancing T cell activation. Thus, the PAD4-STAT1-PIAS1 axis is an immune restriction mechanism in macrophages and may serve as a cancer immunotherapy target.

Comprehensive analyses of mitophagy-related genes and mitophagy-related lncRNAs for patients with ovarian cancer

BACKGROUND

Both mitophagy and long non-coding RNAs (lncRNAs) play crucial roles in ovarian cancer (OC). We sought to explore the characteristics of mitophagy-related gene (MRG) and mitophagy-related lncRNAs (MRL) to facilitate treatment and prognosis of OC.

METHODS

The processed data were extracted from public databases (TCGA, GTEx, GEO and GeneCards). The highly synergistic lncRNA modules and MRLs were identified using weighted gene co-expression network analysis. Using LASSO Cox regression analysis, the MRL-model was first established based on TCGA and then validated with four external GEO datasets. The independent prognostic value of the MRL-model was evaluated by Multivariate Cox regression analysis. Characteristics of functional pathways, somatic mutations, immunity features, and anti-tumor therapy related to the MRL-model were evaluated using abundant algorithms, such as GSEA, ssGSEA, GSVA, maftools, CIBERSORT, xCELL, MCPcounter, ESTIMATE, TIDE, pRRophetic and so on.

RESULTS

We found 52 differentially expressed MRGs and 22 prognostic MRGs in OC. Enrichment analysis revealed that MRGs were involved in mitophagy. Nine prognostic MRLs were identified and eight optimal MRLs combinations were screened to establish the MRL-model. The MRL-model stratified patients into high- and low-risk groups and remained a prognostic factor (P < 0.05) with independent value (P < 0.05) in TCGA and GEO. We observed that OC patients in the high-risk group also had the unfavorable survival in consideration of clinicopathological parameters. The Nomogram was plotted to make the prediction results more intuitive and readable. The two risk groups were enriched in discrepant functional pathways (such as Wnt signaling pathway) and immunity features. Besides, patients in the low-risk group may be more sensitive to immunotherapy (P = 0.01). Several chemotherapeutic drugs (Paclitaxel, Veliparib, Rucaparib, Axitinib, Linsitinib, Saracatinib, Motesanib, Ponatinib, Imatinib and so on) were found with variant sensitivity between the two risk groups. The established ceRNA network indicated the underlying mechanisms of MRLs.

CONCLUSIONS

Our study revealed the roles of MRLs and MRL-model in expression, prognosis, chemotherapy, immunotherapy, and molecular mechanism of OC. Our findings were able to stratify OC patients with high risk, unfavorable prognosis and variant treatment sensitivity, thus improving clinical outcomes for OC patients.

Metabolic regulation of tumor-associated macrophage heterogeneity: insights into the tumor microenvironment and immunotherapeutic opportunities

Tumor-associated macrophages (TAMs) are a heterogeneous population that play diverse functions in tumors. Their identity is determined not only by intrinsic factors, such as origins and transcription factors, but also by external signals from the tumor microenvironment (TME), such as inflammatory signals and metabolic reprogramming. Metabolic reprogramming has rendered TAM to exhibit a spectrum of activities ranging from pro-tumorigenic to anti-tumorigenic, closely associated with tumor progression and clinical prognosis. This review implicates the diversity of TAM phenotypes and functions, how this heterogeneity has been re-evaluated with the advent of single-cell technologies, and the impact of TME metabolic reprogramming on TAMs. We also review current therapies targeting TAM metabolism and offer new insights for TAM-dependent anti-tumor immunotherapy by focusing on the critical role of different metabolic programs in TAMs.

METTL3-mediated m6A methylation regulates ovarian cancer progression by recruiting myeloid-derived suppressor cells

BACKGROUND

Ovarian cancer (OC) typically develops an immunosuppressive microenvironment by funtional changes of host immune cells. Dysregulated m6A level is associated with cancer progression via the intrinsic oncogenic pathways. However, the role of m6A in regulating host immune cell function during anti-tumor immunity needs comprehensive analysis. This study aimed to investigate the role of METTL3, a catalytic subunit of the methyltransferase complex, in regulating host immune cell response against OC.

METHODS

In this study, myeloid-specific Mettl3 gene knockout (Mettl3-cKO) mice were bred using the Cre-LoxP system. Intraperitoneally injection of ID8 cells was used as a syngeneic OC model. Furthermore, the compositions of immune cell populations were analyzed by flow cytometry and single-cell sequencing. Moreover, chemokines and cytokines secretion were assessed using ELISA. Lastly, the role of METTL3 in regulating IL-1β secretion and inflammasome activation in bone marrow-derived macrophages cocultured with ID8 cells was specified by ELISA and immunoblotting.

RESULTS

It was revealed that OC cell growth was enhanced in Mettl3-cKO mice. Furthermore, a shift of decreased M1 to increased M2 macrophage polarization was observed during OC progression. Moreover, Mettl3 depletion in myeloid lineage cells increased secretion of CCL2 and CXCL2 in peritoneal lavage fluild. Interestingly, Mettl3 deficiency enhanced IL-1β secretion induced by viable ID8 cells independent of inflammasome activation and cell death. Therefore, OC cells in tumor-bearing mice trigger a slight inflammatory response with a low-to-moderate secretion of pro-inflammatory cytokines and chemokines.

CONCLUSION

This study provides new insights into METTL3-mediated m6A methylation, which regulates host immune response against OC.

Machine learning-based metabolism-related genes signature, single-cell RNA sequencing, and experimental validation in hypersensitivity pneumonitis

Metabolism is involved in the pathogenesis of hypersensitivity pneumonitis. To identify diagnostic feature biomarkers based on metabolism-related genes (MRGs) and determine the correlation between MRGs and M2 macrophages in patients with hypersensitivity pneumonitis (HP). We retrieved the gene expression matrix from the Gene Expression Omnibus database. The differentially expressed MRGs (DE-MRGs) between healthy control (HC) and patients with HP were identified using the "DESeq2" R package. The "clusterProfiler" R package was used to perform "Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses" on DE-MRGs. We used machine learning algorithms for screening diagnostic feature biomarkers for HP. The "receiver operating characteristic curve" was used to evaluate diagnostic feature biomarkers' discriminating ability. Next, we used the "Cell-type Identification by Estimating Relative Subsets of RNA Transcripts" algorithm to determine the infiltration status of 22 types of immune cells in the HC and HP groups. Single-cell sequencing and qRT-PCR were used to validate the diagnostic feature biomarkers. Furthermore, the status of macrophage polarization in the peripheral blood of patients with HP was determined using flow cytometry. Finally, the correlation between the proportion of M2 macrophages in peripheral blood and the diagnostic biomarker expression profile in HP patients was determined using Spearman analysis. We identified a total of 311 DE-MRGs. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that DE-MRGs were primarily enriched in processes like steroid hormone biosynthesis, drug metabolism, retinol metabolism, etc. Finally, we identified NPR3, GPX3, and SULF1 as diagnostic feature biomarkers for HP using machine learning algorithms. The bioinformatic results were validated using the experimental results. The CIERSORT algorithm and flow cytometry showed a significant difference in the proportion of M2 macrophages in the HC and HP groups. The expression of SULF1 was positively correlated with the proportion of M2-type macrophages. In addition, a positive correlation was observed between SULF1 expression and M2 macrophage proportion. Finally, we identified NPR3, GPX3, and SULF1 as diagnostic feature biomarkers for HP. Further, a correlation between SULF1 and M2 macrophages was observed, providing a novel perspective for treating patients with HP and future studies.

Redox Dysregulation in the Tumor Microenvironment Contributes to Cancer Metastasis

Significance: Redox dysregulation under pathological conditions results in excessive reactive oxygen species (ROS) accumulation, leading to oxidative stress and cellular oxidative damage. ROS function as a double-edged sword to modulate various types of cancer development and survival. Recent Advances: Emerging evidence has underlined that ROS impact the behavior of both cancer cells and tumor-associated stromal cells in the tumor microenvironment (TME), and these cells have developed complex systems to adapt to high ROS environments during cancer progression. Critical Issues: In this review, we integrated current progress regarding the impact of ROS on cancer cells and tumor-associated stromal cells in the TME and summarized how ROS production influences cancer cell behaviors. Then, we summarized the distinct effects of ROS during different stages of tumor metastasis. Finally, we discussed potential therapeutic strategies for modulating ROS for the treatment of cancer metastasis. Future Directions: Targeting the ROS regulation during cancer metastasis will provide important insights into the design of effective single or combinatorial cancer therapeutic strategies. Well-designed preclinical studies and clinical trials are urgently needed to understand the complex regulatory systems of ROS in the TME. Antioxid. Redox Signal. 39, 472-490.

Efficacy evaluation of chimeric antigen receptor-modified human peritoneal macrophages in the treatment of gastric cancer

BACKGROUND

Gastric cancer is one of the most common cancers. Peritoneal carcinomatosis (PC) appears to be the most common pattern of recurrence, and more than half of the GC patients eventually die from PC. Novel strategies for the management of patients with PC are urgently needed. Recently, rapid progress has been made in adoptive transfer therapy by using macrophages as the effector cells due to their capabilities of phagocytosis, antigen presentation, and high penetration. Here, we generated a novel macrophage-based therapy and investigated anti-tumoral effects on GC and potential toxicity.

METHODS

We developed a novel Chimeric Antigen Receptor-Macrophage (CAR-M) based on genetically modifying human peritoneal macrophages (PMs), expressing a HER2-FcεR1γ-CAR (HF-CAR). We tested HF-CAR macrophages in a variety of GC models in vitro and in vivo.

RESULTS

HF-CAR-PMs specifically targeted HER2-expressed GC, and harboured the FcεR1γ moieties to trigger engulfment. Intraperitoneal administration of HF-CAR-PMs significantly facilitated the HER2-positive tumour regression in PC mouse model and prolonged the overall survival rate. In addition, the combined use of oxaliplatin and HF-CAR-PMs exhibited significantly augment anti-tumour activity and survival benefit.

CONCLUSIONS

HF-CAR-PMs could represent an exciting therapeutic option for patients with HER2-positive GC cancer, which should be tested in carefully designed clinical trials.

Beggars banquet: Metabolism in the tumor immune microenvironment and cancer therapy

Metabolic programming in the tumor microenvironment (TME) alters tumor immunity and immunotherapeutic response in tumor-bearing mice and patients with cancer. Here, we review immune-related functions of core metabolic pathways, key metabolites, and crucial nutrient transporters in the TME, discuss their metabolic, signaling, and epigenetic impact on tumor immunity and immunotherapy, and explore how these insights can be applied to the development of more effective modalities to potentiate the function of T cells and sensitize tumor cell receptivity to immune attack, thereby overcoming therapeutic resistance.

miR-210 promotes hepatocellular carcinoma progression by modulating macrophage autophagy through PI3K/AKT/mTOR signaling

BACKGROUND

Tumor-associated macrophages (TAMs) play an important role in tumor development. Increasing research suggests that miR-210 may promote the progression of tumor virulence, but whether its pro-carcinogenic effect in primary hepatocellular carcinoma (HCC) is via an action on M2 macrophages has not been examined.

METHODS

Differentiation of THP-1 monocytes into M2-polarized macrophages was induced with phorbol myristate acetate (PMA) and IL-4, IL-13. M2 macrophages were transfected with miR-210 mimics or miR-210 inhibitors. Flow cytometry was used to identify macrophage-related markers and apoptosis levels. The autophagy level of M2 macrophages, expression of PI3K/AKT/mTOR signaling pathway-related mRNAs and protein were detected by qRT-PCR and Western blot. HepG2 and MHCC-97H HCC cell lines were cultured with M2 macrophages conditioned medium to explore the effects of M2 macrophage-derived miR-210 on the proliferation, migration, invasion and apoptosis of HCC cells.

RESULTS

qRT-PCR showed increased expression of miR-210 in M2 macrophages. Autophagy-related gene and protein expression was enhanced in M2 macrophages transfected with miR-210 mimics, while apoptosis-related proteins were decreased. MDC staining and transmission electron microscopy observed the accumulation of MDC-labeled vesicles and autophagosomes in M2 macrophages in the miR-210 mimic group. The expression of PI3K/AKT/mTOR signaling pathway in M2 macrophages was reduced in miR-210 mimic group. HCC cells co-cultured with M2 macrophages transfected with miR-210 mimics exhibited enhanced proliferation and invasive ability as compared to the control group, while apoptosis levels were reduced. Moreover, promoting or inhibiting autophagy could enhance or abolish the above observed biological effects, respectively.

CONCLUSIONS

miR-210 can promote autophagy of M2 macrophages via PI3K/AKT/mTOR signaling pathway. M2 macrophage-derived miR-210 promotes the malignant progression of HCC via autophagy, suggesting that macrophage autophagy may serve as a new therapeutic target for HCC, and targeting miR-210 may reset the effect of M2 macrophages on HCC.

Phagocytosis increases an oxidative metabolic and immune suppressive signature in tumor macrophages

Phagocytosis is a key macrophage function, but how phagocytosis shapes tumor-associated macrophage (TAM) phenotypes and heterogeneity in solid tumors remains unclear. Here, we utilized both syngeneic and novel autochthonous lung tumor models in which neoplastic cells express the fluorophore tdTomato (tdTom) to identify TAMs that have phagocytosed neoplastic cells in vivo. Phagocytic tdTompos TAMs upregulated antigen presentation and anti-inflammatory proteins, but downregulated classic proinflammatory effectors compared to tdTomneg TAMs. Single-cell transcriptomic profiling identified TAM subset-specific and common gene expression changes associated with phagocytosis. We uncover a phagocytic signature that is predominated by oxidative phosphorylation (OXPHOS), ribosomal, and metabolic genes, and this signature correlates with worse clinical outcome in human lung cancer. Expression of OXPHOS proteins, mitochondrial content, and functional utilization of OXPHOS were increased in tdTompos TAMs. tdTompos tumor dendritic cells also display similar metabolic changes. Our identification of phagocytic TAMs as a distinct myeloid cell state links phagocytosis of neoplastic cells in vivo with OXPHOS and tumor-promoting phenotypes.

Metabolic dependencies and targets in ovarian cancer

Reprogramming of cellular metabolism is a hallmark of cancer. Cancer cells undergo metabolic adaptations to maintain tumorigenicity and survive under the attack of immune cells and chemotherapy in the tumor microenvironment. Metabolic alterations in ovarian cancer in part overlap with findings from other solid tumors and in part reflect unique traits. Altered metabolic pathways not only facilitate ovarian cancer cells' survival and proliferation but also endow them to metastasize, acquire resistance to chemotherapy, maintain cancer stem cell phenotype and escape the effects of anti-tumor immune defense. In this review, we comprehensively review the metabolic signatures of ovarian cancer and their impact on cancer initiation, progression, and resistance to treatment. We highlight novel therapeutic strategies targeting metabolic pathways under development.

Intraperitoneal metastasis of ovarian cancer: new insights on resident macrophages in the peritoneal cavity

Ovarian cancer metastasis occurs primarily in the peritoneal cavity. Orchestration of cancer cells with various cell types, particularly macrophages, in the peritoneal cavity creates a metastasis-favorable environment. In the past decade, macrophage heterogeneities in different organs as well as their diverse roles in tumor settings have been an emerging field. This review highlights the unique microenvironment of the peritoneal cavity, consisting of the peritoneal fluid, peritoneum, and omentum, as well as their own resident macrophage populations. Contributions of resident macrophages in ovarian cancer metastasis are summarized; potential therapeutic strategies by targeting such cells are discussed. A better understanding of the immunological microenvironment in the peritoneal cavity will provide a stepping-stone to new strategies for developing macrophage-based therapies and is a key step toward the unattainable eradication of intraperitoneal metastasis of ovarian cancer.

Mouse Tissue-Resident Peritoneal Macrophages in Homeostasis, Repair, Infection, and Tumor Metastasis

Large peritoneal macrophages (LPMs) are long-lived, tissue-resident macrophages, formed during embryonic life, developmentally and functionally confined to the peritoneal cavity. LPMs provide the first line of defense against life-threatening pathologies of the peritoneal cavity, such as abdominal sepsis, peritoneal metastatic tumor growth, or peritoneal injuries caused by trauma, or abdominal surgery. Apart from their primary phagocytic function, reminiscent of primitive defense mechanisms sustained by coelomocytes in the coelomic cavity of invertebrates, LPMs fulfill an essential homeostatic function by achieving an efficient clearance of apoptotic, that is crucial for the maintenance of self-tolerance. Research performed over the last few years, in mice, has unveiled the mechanisms by which LPMs fulfill a crucial role in repairing peritoneal injuries and controlling microbial and parasitic infections, reflecting that the GATA6-driven LPM transcriptional program can be modulated by extracellular signals associated with pathological conditions. In contrast, recent experimental evidence supports that peritoneal tumors can subvert LPM metabolism and function, leading to the acquisition of a tumor-promoting potential. The remarkable functional plasticity of LPMs can be nevertheless exploited to revert tumor-induced LPM protumor potential, providing the basis for the development of novel immunotherapeutic approaches against peritoneal tumor metastasis based on macrophage reprogramming.

Chitosan derivative composite nanoparticles as adjuvants enhance the cellular immune response via activation of the cGAS-STING pathway

Chitosan and its derivatives are widely used in vaccine adjuvants and delivery systems. Vaccine antigens encapsulated in or conjugated onto N-2-hydroxypropyl trimethyl ammonium chloride chitosan/N,O-carboxymethyl chitosan nanoparticles (N-2-HACC/CMCS NPs) induce strong cellular, humoral, and mucosal immune responses, but the mechanism of action is not fully understood. Therefore, the purpose of this study was to explore the molecular mechanism of composite NPs by upregulating the cGAS-STING signalling pathway to enhance the cellular immune response. We showed that the N-2-HACC/CMCS NPs could be taken up by RAW264.7 cells and produced high levels of IL-6, IL-12p40, and TNF-α. The N-2-HACC/CMCS NPs activated BMDCs, promoted Th1 responses, and enhanced the expression of cGAS, TBK1, IRF3, and STING, as further demonstrated by qRT-PCR and western blotting. Moreover, the NP-induced expression of I-IFNs, IL-1β, IL-6, IL-10 and TNF-α in macrophages was closely related to cGAS-STING. These findings provide a reference for chitosan derivative nanomaterials as vaccine adjuvants and delivery systems and demonstrate that N-2-HACC/CMCS NPs can engage the STING-cGAS pathway to trigger the innate immune response.

Targeting tumor-associated macrophages for successful immunotherapy of ovarian carcinoma

Epithelial ovarian cancer (EOC) is among the top five causes of cancer-related death in women, largely reflecting early, prediagnosis dissemination of malignant cells to the peritoneum. Despite improvements in medical therapies, particularly with the implementation of novel drugs targeting homologous recombination deficiency, the survival rates of patients with EOC remain low. Unlike other neoplasms, EOC remains relatively insensitive to immune checkpoint inhibitors, which is correlated with a tumor microenvironment (TME) characterized by poor infiltration by immune cells and active immunosuppression dominated by immune components with tumor-promoting properties, especially tumor-associated macrophages (TAMs). In recent years, TAMs have attracted interest as potential therapeutic targets by seeking to reverse the immunosuppression in the TME and enhance the clinical efficacy of immunotherapy. Here, we review the key biological features of TAMs that affect tumor progression and their relevance as potential targets for treating EOC. We especially focus on the therapies that might modulate the recruitment, polarization, survival, and functional properties of TAMs in the TME of EOC that can be harnessed to develop superior combinatorial regimens with immunotherapy for the clinical care of patients with EOC.

TIM-4 orchestrates mitochondrial homeostasis to promote lung cancer progression via ANXA2/PI3K/AKT/OPA1 axis

Mitochondrial function and homeostasis are critical to the proliferation of lung cancer cells. T-cell immunoglobulin and mucin domain-containing molecule 4 (TIM-4) promotes the development and progression of lung cancer. However, the role of TIM-4 in mitochondria homeostasis in tumor cells remains completely unknown. In this study, we found that TIM-4 promoted growth and proliferation of lung cancer cells by the oxidative phosphorylation (OXPHOS) pathway. Consistently, inhibition of OXPHOS reversed TIM-4-induced proliferation of lung cancer cells. Notably, TIM-4 promoted mitochondrial fusion via enhancing L-OPA1 protein expression. Mechanistically, TIM-4 regulated protein of L-OPA1 through the PI3K/AKT pathway, and TIM-4 interacted with ANXA2 to promote the activation of PI3K/AKT signaling. Collectively, TIM-4 promotes oxidative phosphorylation of lung cancer cells to accelerate tumor progress via ANXA2/PI3K/AKT/OPA1 axis, which sheds significant new lights on the potential role of TIM-4 in regulating tumor cell metabolism.

Gata6+ large peritoneal macrophages: an evolutionarily conserved sentinel and effector system for infection and injury

There are striking similarities between the sea urchin cavity macrophage-like phagocytes (coelomocytes) and mammalian cavity macrophages in not only their location, but also their behaviors. These cells are crucial for maintaining homeostasis within the cavity following a breach, filling the gap and functioning as a barrier between vital organs and the environment. In this review, we summarize the evolving literature regarding these Gata6⁺ large peritoneal macrophages (GLPMs), focusing on ontogeny, their responses to perturbations, including their rapid aggregation via coagulation, as well as scavenger receptor cysteine-rich domains and their potential roles in diseases, such as cancer. We challenge the 50-year old phenomenon of the 'macrophage disappearance reaction' (MDR) and propose the new term 'macrophage disturbance of homeostasis reaction' (MDHR), which may better describe this complex phenomenon.

Control of tumor-associated macrophage responses by nutrient acquisition and metabolism

Metazoan tissue specification is associated with integration of macrophage lineage cells in sub-tissular niches to promote tissue development and homeostasis. Oncogenic transformation, most prevalently of epithelial cell lineages, results in maladaptation of resident tissue macrophage differentiation pathways to generate parenchymal and interstitial tumor-associated macrophages that largely foster cancer progression. In addition to growth factors, nutrients that can be consumed, stored, recycled, or converted to signaling molecules have emerged as crucial regulators of macrophage responses in tumor. Here, we review how nutrient acquisition through plasma membrane transporters and engulfment pathways control tumor-associated macrophage differentiation and function. We also discuss how nutrient metabolism regulates tumor-associated macrophages and how these processes may be targeted for cancer therapy.

Adipose tissue macrophages: implications for obesity-associated cancer

Obesity is one of the most serious global health problems, with an incidence that increases yearly and coincides with the development of cancer. Adipose tissue macrophages (ATMs) are particularly important in this context and contribute to linking obesity-related inflammation and tumor progression. However, the functions of ATMs on the progression of obesity-associated cancer remain unclear. In this review, we describe the origins, phenotypes, and functions of ATMs. Subsequently, we summarize the potential mechanisms on the reprogramming of ATMs in the obesity-associated microenvironment, including the direct exchange of dysfunctional metabolites, inordinate cytokines and other signaling mediators, transfer of extracellular vesicle cargo, and variations in the gut microbiota and its metabolites. A better understanding of the properties and functions of ATMs under conditions of obesity will lead to the development of new therapeutic interventions for obesity-related cancer.