Tissue resident iNKT17 cells facilitate cancer cell extravasation in liver metastasis via interleukin-22

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

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

GPR34 is a metabolic immune checkpoint for ILC1-mediated antitumor immunity

Type 1 innate lymphoid cells (ILC1s) are a class of tissue-resident cells with antitumor activity, suggesting its possible role in solid tumor immune surveillance, but it is not clear whether manipulating ILC1s can induce potent antitumor immune responses. Here, we found that G-protein-coupled receptor 34 (GPR34), a receptor for lysophosphatidylserine (LysoPS), was highly expressed on ILC1s but not on conventional natural killer cells in the tumor microenvironment. LysoPS was enriched in the tumor microenvironment and could inhibit ILC1 activation via GPR34. Genetic deletion of LysoPS synthase Abhd16a expression in tumors or Gpr34 expression in ILC1s or antagonizing GPR34 enhanced ILC1 antitumor activity. In individuals with cancer, ABHD16A expression in tumors or GPR34 expression in ILC1s was inversely correlated with the antitumor activity of ILC1s or ILC1-like cells. Thus, our results demonstrate that manipulating ILC1s can induce potent antitumor immunity, and GPR34 is a metabolic immune checkpoint that can be targeted to develop ILC1-based immunotherapy.

Multi-stage mechanisms of tumor metastasis and therapeutic strategies

The cascade of metastasis in tumor cells, exhibiting organ-specific tendencies, may occur at numerous phases of the disease and progress under intense evolutionary pressures. Organ-specific metastasis relies on the formation of pre-metastatic niche (PMN), with diverse cell types and complex cell interactions contributing to this concept, adding a new dimension to the traditional metastasis cascade. Prior to metastatic dissemination, as orchestrators of PMN formation, primary tumor-derived extracellular vesicles prepare a fertile microenvironment for the settlement and colonization of circulating tumor cells at distant secondary sites, significantly impacting cancer progression and outcomes. Obviously, solely intervening in cancer metastatic sites passively after macrometastasis is often insufficient. Early prediction of metastasis and holistic, macro-level control represent the future directions in cancer therapy. This review emphasizes the dynamic and intricate systematic alterations that occur as cancer progresses, illustrates the immunological landscape of organ-specific PMN creation, and deepens understanding of treatment modalities pertinent to metastasis, thereby identifying some prognostic and predictive biomarkers favorable to early predict the occurrence of metastasis and design appropriate treatment combinations.

IL-22: A key inflammatory mediator as a biomarker and potential therapeutic target for lung cancer

Lung cancer, one of the most prevalent cancers worldwide, stands as the primary cause of cancer-related deaths. As is well-known, the utmost crucial risk factor contributing to lung cancer is smoking. In recent years, remarkable progress has been made in treating lung cancer, particularly non-small cell lung cancer (NSCLC). Nevertheless, the absence of effective and accurate biomarkers for diagnosing and treating lung cancer remains a pressing issue. Interleukin 22 (IL-22) is a member of the IL-10 cytokine family. It exerts biological functions (including induction of proliferation and anti-apoptotic signaling pathways, enhancement of tissue regeneration and immunity defense) by binding to heterodimeric receptors containing type 1 receptor chain (R1) and type 2 receptor chain (R2). IL-22 has been identified as a pro-cancer factor since dysregulation of the IL-22-IL-22R system has been implicated in the development of different cancers, including lung, breast, gastric, pancreatic, and colon cancers. In this review, we discuss the differential expression, regulatory role, and potential clinical significance of IL-22 in lung cancer, while shedding light on innovative approaches for the future.

Mechanisms of metastatic colorectal cancer

Despite extensive research and improvements in understanding colorectal cancer (CRC), its metastatic form continues to pose a substantial challenge, primarily owing to limited therapeutic options and a poor prognosis. This Review addresses the emerging focus on metastatic CRC (mCRC), which has historically been under-studied compared with primary CRC despite its lethality. We delve into two crucial aspects: the molecular and cellular determinants facilitating CRC metastasis and the principles guiding the evolution of metastatic disease. Initially, we examine the genetic alterations integral to CRC metastasis, connecting them to clinically marked characteristics of advanced CRC. Subsequently, we scrutinize the role of cellular heterogeneity and plasticity in metastatic spread and therapy resistance. Finally, we explore how the tumour microenvironment influences metastatic disease, emphasizing the effect of stromal gene programmes and the immune context. The ongoing research in these fields holds immense importance, as its future implications are projected to revolutionize the treatment of patients with mCRC, hopefully offering a promising outlook for their survival.

Pro- and antitumorigenic functions of γδ T cells

γδ T cells are a subset of T cells that are characterized by the expression of a TCR-γδ instead of a TCR-αβ. Despite being outnumbered by their αβ T cell counterpart in many tissues, studies from the last 20 years underline their important and non-redundant roles in tumor and metastasis development. However, whether a γδ T cell exerts pro- or antitumorigenic effects seems to depend on a variety of factors, many of them still incompletely understood today. In this review, we summarize mechanisms by which γδ T cells exert these seemingly contradictory effector functions in mice and humans. Furthermore, we discuss the current view on inducing and inhibiting factors of γδ T cells during cancer development.

IL-22 activates the PI3K-AKT pathway to promote colorectal cancer cell proliferation and metastasis

BACKGROUND

Colorectal cancer (CRC) is a prevalent malignancy with high morbidity and mortality rates. Previous studies have demonstrated that interleukin (IL)-22 is involved in CRC progression; however, the exact mechanism remains unclear. This study aimed to investigate the effects of IL-22 on CRC cell proliferation and metastasis.

METHODS

IL-22 levels in the serum and tissues of CRC patients were measured using enzyme-linked immunosorbent assay (ELISA). Cell counting kit-8 (CCK-8) assay was used to detect the viability of CRC (HCT116) cells treated with different IL-22 concentrations. Colony formation, Transwell invasion, and scratch assays were employed to assess the effects of IL-22 on cell proliferation, invasion, and migration. Western blotting was performed to measure the expression levels of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), p-PI3K, p-AKT, E-cadherin, matrix metalloproteinase (MMP)-2, MMP-9, SNAI1, and TWIST1 in HCT116 cells treated with IL-22 or a PI3K inhibitor.

RESULTS

ELISA results showed that the expression of IL-22 was significantly increased in the serum and tissues of CRC patients compared to controls. IL-22 treatment increased cell viability and colony formation in a concentration-dependent manner and enhanced cell invasion and migration. Western blotting analysis revealed that IL-22 stimulation upregulated p-PI3K and p-AKT expression, while total PI3K and AKT levels remained unchanged. Additionally, IL-22 also decreased E-cadherin expression and increased the expression of MMP-2, MMP-9, SNAI1, and TWIST1.

CONCLUSIONS

IL-22 activates the PI3K-AKT pathway and promotes HCT116 cell proliferation and metastasis. Targeting the regulation of the PI3K/AKT pathway may be a potential therapeutic strategy for CRC.

N6-methyladenosine-dependent signaling in colorectal cancer: Functions and clinical potential

Colorectal cancer (CRC) ranks as the third most prevalent malignancy worldwide. Despite the gradual expansion of therapeutic options for CRC, its clinical management remains a formidable challenge. And, because of the current dearth of technical means for early CRC screening, most patients are diagnosed at an advanced stage. Therefore, it is imperative to develop novel diagnostic and therapeutic tools for this disease. N6-methyladenosine (m6A), the predominant RNA modification in eukaryotes, can be recognized by m6A-specific methylated reading proteins to modulate gene expression. Studies have revealed that CRC disrupts m6A homeostasis through various mechanisms, thereby sustaining aberrant signal transduction and promoting its own progression. Consequently, m6A-based diagnostic and therapeutic strategies have garnered widespread attention. Although utilizing m6A as a biomarker and drug target has demonstrated promising feasibility, existing observations primarily stem from preclinical models; henceforth necessitating further investigation and resolution of numerous outstanding issues.

A modified orthotopic left lung transplantation model in rats

To enhance the operability of the rat orthotopic left lung transplantation model, we implemented several improvements and meticulously detailed the procedure. One hundred and thirty-one healthy male Sprague Dawley rats, weighing between 250 and 300 g, were utilized, with 64 serving as donors, 64 as recipients, and 3 as sham controls. We employed a modified three-cuff technique for the orthotopic left lung transplantation. Notably, our modified perfusion method could prevent donor lung edema, while waist-shaped cuffs minimized suture slippage during anastomosis. Additionally, positioning the recipient rat in a slightly left-elevated supine position during anastomosis reduced tension on the lung hilum, thus mitigating the risk of vascular laceration. The introduction of a unique two-person anastomosis technique significantly reduced operation time and substantially improved success rates. Furthermore, maximizing inflation of donor lungs both during preservation and surgery minimized the occurrence of postoperative atelectasis. Various other procedural refinements contributed to the enhanced operability of our model. Sixty-four rat orthotopic left lung transplantations were performed with only one surgical failure observed. The acquisition time for donor lungs averaged (19 ± 4) minutes, while (11 ± 1) minutes were allocated for donor lung hilum anatomy and cuff installation. Recipient thoracotomy and left lung hilar anatomy before anastomosis required (24 ± 8) minutes, with anastomosis itself taking (31 ± 6) minutes. Remarkably, the survival rate at the 4-h postoperative mark stood at 96.7 %. Even six months post-operation, transplanted left rat lungs continued to exhibit proper inflation and contraction rhythms, displaying signs of chronic pathological changes. In summary, our modified rat model of orthotopic left lung transplantation demonstrates robust operability, significantly reducing surgical duration, improving operation success rates, and enhancing postoperative survival rates. Furthermore, its long-term survival capacity enables the simulation of acute and chronic disease processes following lung transplantation.

Hepatocyte-derived FGL1 accelerates liver metastasis and tumor growth by inhibiting CD8+ T and NK cells

Fibrinogen-like protein 1 (FGL1) contributes to the proliferation and metabolism of hepatocytes; however, as a major ligand of the immune checkpoint, its role in the liver regional immune microenvironment is poorly understood. Hepatocytes specifically and highly expressed FGL1 under normal physiological conditions. Increases in hepatic CD8+ T and NK cell numbers and functions were found in Fgl1-deficient (Fgl1-/-) mice, but not in the spleen or lymph node, similar to findings in anti-FGL1 mAb-treated wild-type mice. Furthermore, Fgl1 deficiency or anti-FGL1 mAb blockade restrained liver metastasis and slowed the growth of orthotopic tumors, with significantly prolonged survival of tumor-bearing mice. Tumor-infiltrating hepatic CD8+ T and NK cells upregulated the expression of lymphocyte activation gene-3 (LAG-3) and exhibited stronger antitumor activities after anti-FGL1 treatment. The antitumor efficacy of FGL1 blockade depended on cytotoxic T lymphocytes and NK cells, demonstrated by using a cell-deficient mouse model and cell transfer in vivo. In vitro, FGL1 directly inhibited hepatic T and NK cells related to the receptor LAG-3. In conclusion, hepatocyte-derived FGL1 played critical immunoregulatory roles in the liver and contributed to liver metastasis and tumor growth by inhibiting CD8+ T and NK cell functions via the receptor LAG-3, providing a new strategy for liver cancer immunotherapy.

Intersecting Paths: Unraveling the Complex Journey of Cancer to Bone Metastasis

The phenomenon of bone metastases presents a significant challenge within the context of advanced cancer treatments, particularly pertaining to breast, prostate, and lung cancers. These metastatic occurrences stem from the dissemination of cancerous cells into the bone, thereby interrupting the equilibrium between osteoblasts and osteoclasts. Such disruption results in skeletal complications, adversely affecting patient morbidity and quality of life. This review discusses the intricate interplay between cancer cells and the bone microenvironment, positing the bone not merely as a passive recipient of metastatic cells but as an active contributor to cancer progression through its distinctive biochemical and cellular makeup. A thorough examination of bone structure and the dynamics of bone remodeling is undertaken, elucidating how metastatic cancer cells exploit these processes. This review explores the genetic and molecular pathways that underpin the onset and development of bone metastases. Particular emphasis is placed on the roles of cytokines and growth factors in facilitating osteoclastogenesis and influencing osteoblast activity. Additionally, this paper offers a meticulous critique of current diagnostic methodologies, ranging from conventional radiography to advanced molecular imaging techniques, and discusses the implications of a nuanced understanding of bone metastasis biology for therapeutic intervention. This includes the development of targeted therapies and strategies for managing bone pain and other skeletal-related events. Moreover, this review underscores the imperative of ongoing research efforts aimed at identifying novel therapeutic targets and refining management approaches for bone metastases. It advocates for a multidisciplinary strategy that integrates advancements in medical oncology and radiology with insights derived from molecular biology and genetics, to enhance prognostic outcomes and the quality of life for patients afflicted by this debilitating condition. In summary, bone metastases constitute a complex issue that demands a comprehensive and informed approach to treatment. This article contributes to the ongoing discourse by consolidating existing knowledge and identifying avenues for future investigation, with the overarching objective of ameliorating patient care in the domain of oncology.

Deficiency of IL-22-binding protein enhances the ability of the gut microbiota to protect against enteric pathogens

Interleukin 22 (IL-22) promotes intestinal barrier integrity, stimulating epithelial cells to enact defense mechanisms against enteric infections, including the production of antimicrobial peptides. IL-22 binding protein (IL-22BP) is a soluble decoy encoded by the Il22ra2 gene that decreases IL-22 bioavailability, attenuating IL-22 signaling. The impact of IL-22BP on gut microbiota composition and functioning is poorly understood. We found that Il22ra2-/- mice are better protected against Clostridioides difficile and Citrobacter rodentium infections. This protection relied on IL-22-induced antimicrobial mechanisms before the infection occurred, rather than during the infection itself. Indeed, the gut microbiota of Il22ra2-/- mice mitigated infection of wild-type (WT) mice when transferred via cohousing or by cecal microbiota transplantation. Indicator species analysis of WT and Il22ra2-/- mice with and without cohousing disclosed that IL22BP deficiency yields a gut bacterial composition distinct from that of WT mice. Manipulation of dietary fiber content, measurements of intestinal short-chain fatty acids and oral treatment with acetate disclosed that resistance to C. difficile infection is related to increased production of acetate by Il22ra2-/--associated microbiota. Together, these findings suggest that IL-22BP represents a potential therapeutic target for those at risk for or with already manifest infection with this and perhaps other enteropathogens.

Comprehensive pan-cancer analysis identifies the RNA-binding protein LRPPRC as a novel prognostic and immune biomarker

AIMS

RNA-binding proteins (RBPs) play pivotal roles in carcinogenesis and immunotherapy. Leucine-rich pentapeptide repeat-containing protein (LRPPRC) is crucial for RNA polyadenylation, transport, and stability. Although recent studies have suggested LRPPRC's potential role in tumor progression, its significance in tumor prognosis, diagnosis, and immunology remains unclear.

MAIN METHODS

We comprehensively analyzed LRPPRC expression in tumors using various databases, including Human Transcriptome Cell Atlas (HTCA), University of California Santa Cruz (UCSC), Human Protein Atlas (HPA), Sangerbox, TISIDB, GeneMANIA, GSCALite, and CellMiner. We examined the correlation between LRPPRC expression level and prognosis, immune infiltration, immunotherapy, methylation, biological function, and drug sensitivity. Single-cell analysis was performed using Tumor Immune Single Cell Hub (TISCH) and CancerSEA software. Patients with acute myeloid leukemia (AML) were categorized based on LRPPRC levels for functional and immune infiltration analyses. The role of LRPPRC in cancer was validated using in vitro experiments.

KEY FINDINGS

Our findings revealed that LRPPRC was highly expressed in almost all cancer types, indicating its significant prognostic and diagnostic potential. Notably, LRPPRC was associated with diverse immune features, such as immune cell infiltration, immune checkpoint genes, tumor mutational burden, and microsatellite instability, suggesting its value in guiding immunotherapy strategies. Within AML, the high-expression group had lower levels of immune cells, including CD8+ T cells. In vitro experiments confirmed the inhibitory effects of LRPPRC knockdown on AML cell proliferation.

SIGNIFICANCE

This study highlights LRPPRC as a reliable pan-cancer prognostic and immune biomarker, particularly in AML. It lays the groundwork for future research on LRPPRC-targeted cancer therapies.

IL-10 dampens antitumor immunity and promotes liver metastasis via PD-L1 induction

BACKGROUND & AIMS

The liver is one of the organs most commonly affected by metastasis. The presence of liver metastases has been reported to be responsible for an immunosuppressive microenvironment and diminished immunotherapy efficacy. Herein, we aimed to investigate the role of IL-10 in liver metastasis and to determine how its modulation could affect the efficacy of immunotherapy in vivo.

METHODS

To induce spontaneous or forced liver metastasis in mice, murine cancer cells (MC38) or colon tumor organoids were injected into the cecum or the spleen, respectively. Mice with complete and cell type-specific deletion of IL-10 and IL-10 receptor alpha were used to identify the source and the target of IL-10 during metastasis formation. Programmed death ligand 1 (PD-L1)-deficient mice were used to test the role of this checkpoint. Flow cytometry was applied to characterize the regulation of PD-L1 by IL-10.

RESULTS

We found that Il10-deficient mice and mice treated with IL-10 receptor alpha antibodies were protected against liver metastasis formation. Furthermore, by using IL-10 reporter mice, we demonstrated that Foxp3+ regulatory T cells (Tregs) were the major cellular source of IL-10 in liver metastatic sites. Accordingly, deletion of IL-10 in Tregs, but not in myeloid cells, led to reduced liver metastasis. Mechanistically, IL-10 acted on Tregs in an autocrine manner, thereby further amplifying IL-10 production. Furthermore, IL-10 acted on myeloid cells, i.e. monocytes, and induced the upregulation of the immune checkpoint protein PD-L1. Finally, the PD-L1/PD-1 axis attenuated CD8-dependent cytotoxicity against metastatic lesions.

CONCLUSIONS

Treg-derived IL-10 upregulates PD-L1 expression in monocytes, which in turn reduces CD8+ T-cell infiltration and related antitumor immunity in the context of colorectal cancer-derived liver metastases. These findings provide the basis for future monitoring and targeting of IL-10 in colorectal cancer-derived liver metastases.

IMPACT AND IMPLICATIONS

Liver metastasis diminishes the effectiveness of immunotherapy and increases the mortality rate in patients with colorectal cancer. We investigated the role of IL-10 in liver metastasis formation and assessed its impact on the effectiveness of immunotherapy. Our data show that IL-10 is a pro-metastatic factor involved in liver metastasis formation and that it acts as a regulator of PD-L1. This provides the basis for future monitoring and targeting of IL-10 in colorectal cancer-derived liver metastasis.

THE RELATIONSHIP BETWEEN CIRCULATING IMMUNE CELL PHENOTYPES AND SEPSIS: A MENDELIAN RANDOMIZATION STUDY

ABSTRACT

Objective: The role of immune cells in sepsis remains unclear, and there is some controversy. Here, we aim to systematically assess whether distinct immune cell phenotypes impact the susceptibility to sepsis. Methods: In this study, we harnessed publicly available summary-level data from genome-wide association studies (GWASs). The selection of genetic variations strongly associated with 731 phenotypes of circulating immune cells served as instrumental variables (IVs). Using a two-sample Mendelian randomization (MR) analysis, we investigated the relationships between different immunophenotypes and the occurrence of sepsis, as well as the 28-day mortality. The MR study utilized the inverse variance weighting (IVW) method as the main analytical approach. In addition, we incorporated four other MR methods for supplementary causal inference, including weighted median (WME), MR-Egger regression, simple mode, and weighted mode. Furthermore, the robustness of the results was affirmed through multiple sensitivity analyses. Results: The results of the IVW method indicated that a total of 36 immunophenotypes are associated with the risk of sepsis. We also identified 34 immunophenotypes with a causal association with the 28-day mortality. Interestingly, before multiple testing corrections, 11 immunophenotypes were determined to have consistent causal relationships with both the occurrence of sepsis and the 28-day mortality. Notably, after false discovery rate (FDR) correction, four immunophenotypes were found to be significantly correlated with susceptibility to sepsis: CD45RA- CD4+ %CD4+ (odds ratio [OR], 1.355; 95% confidence interval [CI], 1.139~1.611; P < 0.001, PFDR = 0.192), HLA DR on HLA DR+ NK (OR, 0.818; 95% CI, 0.726~0.922; P = 0.001, PFDR = 0.192), IgD+ CD24+ %B cell (OR, 0.626; 95% CI, 0.473~0.828; P = 0.001, PFDR = 0.192), and TD DN (CD4- CD8-) AC (OR, 0.655; 95% CI, 0.510~0.840; P < 0.001, PFDR = 0.192). Following FDR correction, only one immunophenotype was confirmed to be negatively correlated with the 28-day mortality: CD39 on CD39+ CD8br (OR, 0.820; 95% CI, 0.737~0.912; P < 0.001, PFDR = 0.184). Conclusion: This study, for the first time, has uncovered indicative evidence of a causal relationship between circulating immune cell phenotypes and varying degrees of sepsis through genetic means. These findings underscore the significance of immune cells in the pathogenesis of sepsis.

Protocol for generating lung and liver metastasis in mice using models that bypass intravasation

Forced metastasis models, those in which the step of intravasation is bypassed, can be used to investigate the mechanisms underlying metastasis and evaluate potential therapeutic targets. Here, we present a protocol for using three forced models of lung and liver metastasis to generate metastasis within 3-4 weeks in approximately 99% of injected mice. We describe steps for cancer cell preparation, mouse analgesia and anesthesia; injecting through intrasplenic, intraportal, and intravenous techniques; and daily evaluation of metastasis. For complete details on the use and execution of this protocol, please refer to Giannou et al.1.

Mouse models of spontaneous liver and lung metastasis for colorectal cancer

To investigate underlying mechanisms for cancer metastasis and promising therapies in animal models, spontaneous metastasis models can be used to recreate metastasis development. Here, we present three mouse models of spontaneous lung and/or liver metastasis induction. We describe steps for cancer cell preparation, mouse analgesia, and three injection techniques (subcutaneous, intracecal, and intramucosal). We then detail procedures for evaluating metastasis. Most of these models generate metastasis in a time span of 4 weeks in the majority of injected mice. For complete details on the use and execution of this protocol, please refer to Giannou et al.1.

Review of pre-metastatic niches in lung metastasis: From cells to molecules, from mechanism to clinics

Distant metastasis is responsible for high mortality in most cancer cases and the lung is one of the most common target organs, severely affecting the quality of daily life and overall survival of cancer patients. With relevant research breakthroughs accumulating, scientists have developed a deeper understanding of lung metastasis (LM) from the rudimentary "seed and soil" theory to a more vivid concept of the pre-metastatic niche (PMN). Thus, the mechanisms of PMN formation become considerably complicated, involving various types of cells, chemokines, cytokines, and proteins, providing potential biomarkers for improved LM diagnosis and treatment techniques. Here we summarized the latest findings (in 3 years) of lung PMN and systematically collated it from basic research to clinical application, which clearly exhibited the influences of the primary tumor, stromal, and bone marrow-derived cells (BMDCs) and associated molecules in the formation of lung PMN.

Insights into the heterogeneity of iNKT cells: tissue-resident and circulating subsets shaped by local microenvironmental cues

Invariant natural killer T (iNKT) cells are a distinct subpopulation of innate-like T lymphocytes. They are characterized by semi-invariant T cell receptors (TCRs) that recognize both self and foreign lipid antigens presented by CD1d, a non-polymorphic MHC class I-like molecule. iNKT cells play a critical role in stimulating innate and adaptive immune responses, providing an effective defense against infections and cancers, while also contributing to chronic inflammation. The functions of iNKT cells are specific to their location, ranging from lymphoid to non-lymphoid tissues, such as the thymus, lung, liver, intestine, and adipose tissue. This review aims to provide insights into the heterogeneity of development and function in iNKT cells. First, we will review the expression of master transcription factors that define subsets of iNKT cells and their production of effector molecules such as cytokines and granzymes. In this article, we describe the gene expression profiles contributing to the kinetics, distribution, and cytotoxicity of iNKT cells across different tissue types. We also review the impact of cytokine production in distinct immune microenvironments on iNKT cell heterogeneity, highlighting a recently identified circulating iNKT cell subset. Additionally, we explore the potential of exploiting iNKT cell heterogeneity to create potent immunotherapies for human cancers in the future.

Crosstalk between colorectal CSCs and immune cells in tumorigenesis, and strategies for targeting colorectal CSCs

Cancer immunotherapy has emerged as a promising strategy in the treatment of colorectal cancer, and relapse after tumor immunotherapy has attracted increasing attention. Cancer stem cells (CSCs), a small subset of tumor cells with self-renewal and differentiation capacities, are resistant to traditional therapies such as radiotherapy and chemotherapy. Recently, CSCs have been proven to be the cells driving tumor relapse after immunotherapy. However, the mutual interactions between CSCs and cancer niche immune cells are largely uncharacterized. In this review, we focus on colorectal CSCs, CSC-immune cell interactions and CSC-based immunotherapy. Colorectal CSCs are characterized by robust expression of surface markers such as CD44, CD133 and Lgr5; hyperactivation of stemness-related signaling pathways, such as the Wnt/β-catenin, Hippo/Yap1, Jak/Stat and Notch pathways; and disordered epigenetic modifications, including DNA methylation, histone modification, chromatin remodeling, and noncoding RNA action. Moreover, colorectal CSCs express abnormal levels of immune-related genes such as MHC and immune checkpoint molecules and mutually interact with cancer niche cells in multiple tumorigenesis-related processes, including tumor initiation, maintenance, metastasis and drug resistance. To date, many therapies targeting CSCs have been evaluated, including monoclonal antibodies, antibody‒drug conjugates, bispecific antibodies, tumor vaccines adoptive cell therapy, and small molecule inhibitors. With the development of CSC-/niche-targeting technology, as well as the integration of multidisciplinary studies, novel therapies that eliminate CSCs and reverse their immunosuppressive microenvironment are expected to be developed for the treatment of solid tumors, including colorectal cancer.

Lipid metabolism in the immune niche of tumor-prone liver microenvironment

The liver is a common primary site not only for tumorigenesis, but also for cancer metastasis. Advanced cancer patients with liver metastases also show reduced response rates and survival benefits when treated with immune checkpoint inhibitors. Accumulating evidence has highlighted the importance of the liver immune microenvironment in determining tumorigenesis, metastasis-organotropism, and immunotherapy resistance. Various immune cells such as T cells, natural killer and natural killer T cells, macrophages and dendritic cells, and stromal cells including liver sinusoidal endothelial cells, Kupffer cells, hepatic stellate cells, and hepatocytes are implicated in contributing to the immune niche of tumor-prone liver microenvironment. In parallel, as the major organ for lipid metabolism, the increased abundance of lipids and their metabolites is linked to processes crucial for nonalcoholic fatty liver disease and related liver cancer development. Furthermore, the proliferation, differentiation, and functions of hepatic immune and stromal cells are also reported to be regulated by lipid metabolism. Therefore, targeting lipid metabolism may hold great potential to reprogram the immunosuppressive liver microenvironment and synergistically enhance the immunotherapy efficacy in the circumstance of liver metastasis. In this review, we describe how the hepatic microenvironment adapts to the lipid metabolic alterations in pathologic conditions like nonalcoholic fatty liver disease. We also illustrate how these immunometabolic alterations promote the development of liver cancers and immunotherapy resistance. Finally, we discuss the current therapeutic options and hypothetic combination immunotherapies for the treatment of advanced liver cancers.

Effects of Psychological Stress on Multiple Sclerosis via HPA Axis-mediated Modulation of Natural Killer T Cell Activity

The involvement of psychological stress and Natural Killer T (NKT) cells in the pathophysiology of multiple sclerosis has been identified in the progression of this disease. Psychological stress can impact disease occurrence, relapse, and severity through its effects on the Hypothalamic- Pituitary-Adrenal (HPA) axis and immune responses. NKT cells are believed to play a pivotal role in the pathogenesis of multiple sclerosis, with recent evidence suggesting their distinct functional alterations following activation of the HPA axis under conditions of psychological stress. This review summarizes the associations between psychological stress, NKT cells, and multiple sclerosis while discussing the potential mechanism for how NKT cells mediate the effects of psychological stress on this disease.

Porphyromonas gingivalis fuels colorectal cancer through CHI3L1-mediated iNKT cell-driven immune evasion

The interaction between the gut microbiota and invariant Natural Killer T (iNKT) cells plays a pivotal role in colorectal cancer (CRC). The pathobiont Fusobacterium nucleatum influences the anti-tumor functions of CRC-infiltrating iNKT cells. However, the impact of other bacteria associated with CRC, like Porphyromonas gingivalis, on their activation status remains unexplored. In this study, we demonstrate that mucosa-associated P. gingivalis induces a protumour phenotype in iNKT cells, subsequently influencing the composition of mononuclear-phagocyte cells within the tumor microenvironment. Mechanistically, in vivo and in vitro experiments showed that P. gingivalis reduces the cytotoxic functions of iNKT cells, hampering the iNKT cell lytic machinery through increased expression of chitinase 3-like-1 protein (CHI3L1). Neutralization of CHI3L1 effectively restores iNKT cell cytotoxic functions suggesting a therapeutic potential to reactivate iNKT cell-mediated antitumour immunity. In conclusion, our data demonstrate how P. gingivalis accelerates CRC progression by inducing the upregulation of CHI3L1 in iNKT cells, thus impairing their cytotoxic functions and promoting host tumor immune evasion.

New insights into the correlations between circulating tumor cells and target organ metastasis

Organ-specific metastasis is the primary cause of cancer patient death. The distant metastasis of tumor cells to specific organs depends on both the intrinsic characteristics of the tumor cells and extrinsic factors in their microenvironment. During an intermediate stage of metastasis, circulating tumor cells (CTCs) are released into the bloodstream from primary and metastatic tumors. CTCs harboring aggressive or metastatic features can extravasate to remote sites for continuous colonizing growth, leading to further lesions. In the past decade, numerous studies demonstrated that CTCs exhibited huge clinical value including predicting distant metastasis, assessing prognosis and monitoring treatment response et al. Furthermore, increasingly numerous experiments are dedicated to identifying the key molecules on or inside CTCs and exploring how they mediate CTC-related organ-specific metastasis. Based on the above molecules, more and more inhibitors are being developed to target CTCs and being utilized to completely clean CTCs, which should provide promising prospects to administer advanced tumor. Recently, the application of various nanomaterials and microfluidic technologies in CTCs enrichment technology has assisted to improve our deep insights into the phenotypic characteristics and biological functions of CTCs as a potential therapy target, which may pave the way for us to make practical clinical strategies. In the present review, we mainly focus on the role of CTCs being involved in targeted organ metastasis, especially the latest molecular mechanism research and clinical intervention strategies related to CTCs.

Protocol for orthotopic single-lung transplantation in mice as a tool for lung metastasis studies

The transplantation model provides the opportunity to assess the relevance of a molecule of interest for tumor cell extravasation by using a respective genetically modified donor animal. Here, we present a protocol for orthotopic single-lung transplantation in mice as a tool for lung metastasis studies. We describe steps for animal preparation, lung transplantation, and tumor cell injection. We then detail procedures for the direct comparison of tumor cell spreading between the genetically modified left lung and the naive right lung parenchyma. For complete details on the use and execution of this protocol, please refer to Giannou et al. (2023).1.

CD4+ T cell-derived IL-22 enhances liver metastasis by promoting angiogenesis

Metastasis is a cancer-related systemic disease and is responsible for the greatest mortality rate among cancer patients. Interestingly, the interaction between the immune system and cancer cells seems to play a key role in metastasis formation in the target organ. However, this complex network is only partially understood. We previously found that IL-22 produced by tissue resident iNKT17 cells promotes cancer cell extravasation, the early step of metastasis. Based on these data, we aimed here to decipher the role of IL-22 in the last step of metastasis formation. We found that IL-22 levels were increased in established metastatic sites in both human and mouse. We also found that Th22 cells were the key source of IL-22 in established metastasis sites, and that deletion of IL-22 in CD4+ T cells was protective in liver metastasis formation. Accordingly, the administration of a murine IL-22 neutralizing antibody in the establishment of metastasis formation significantly reduced the metastatic burden in a mouse model. Mechanistically, IL-22-producing Th22 cells promoted angiogenesis in established metastasis sites. In conclusion, our findings highlight that IL-22 is equally as important in contributing to metastasis formation at late metastatic stages, and thus, identify it as a novel therapeutic target in established metastasis.

Aging unconventionally: γδ T cells, iNKT cells, and MAIT cells in aging

Unconventional T cells include γδ T cells, invariant Natural Killer T cells (iNKT) cells and Mucosal Associated Invariant T (MAIT) cells, which are distinguished from conventional T cells by their recognition of non-peptide ligands presented by non-polymorphic antigen presenting molecules and rapid effector functions that are pre-programmed during their development. Here we review current knowledge of the effect of age on unconventional T cells, from early life to old age, in both mice and humans. We then discuss the role of unconventional T cells in age-associated diseases and infections, highlighting the similarities between members of the unconventional T cell family in the context of aging.

IL-22BP controls the progression of liver metastasis in colorectal cancer

Background

The immune system plays a pivotal role in cancer progression. Interleukin 22 binding protein (IL-22BP), a natural antagonist of the cytokine interleukin 22 (IL-22) has been shown to control the progression of colorectal cancer (CRC). However, the role of IL-22BP in the process of metastasis formation remains unknown.

Methods

We used two different murine in vivo metastasis models using the MC38 and LLC cancer cell lines and studied lung and liver metastasis formation after intracaecal or intrasplenic injection of cancer cells. Furthermore, IL22BP expression was measured in a clinical cohort of CRC patients and correlated with metastatic tumor stages.

Results

Our data indicate that low levels of IL-22BP are associated with advanced (metastatic) tumor stages in colorectal cancer. Using two different murine in vivo models we show that IL-22BP indeed controls the progression of liver but not lung metastasis in mice.

Conclusions

We here demonstrate a crucial role of IL-22BP in controlling metastasis progression. Thus, IL-22 might represent a future therapeutic target against the progression of metastatic CRC.

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

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

scRNA-Seq and imaging mass cytometry analyses unveil iNKT cells-mediated anti-tumor immunity in pancreatic cancer liver metastasis

Invariant natural killer T (iNKT) cells are innate-like T cells that are abundant in liver sinusoids and play a critical role in tumor immunity. However, the role of iNKT cells in pancreatic cancer liver metastasis (PCLM) has not been fully explored. In this study, we employed a hemi-spleen pancreatic tumor cell injection mouse model of PCLM, a model that closely mimics clinical conditions in humans, to explore the role of iNKT cells in PCLM. Activation of iNKT cells with α-galactosylceramide (αGC) markedly increased immune cell infiltration and suppressed PCLM progression. Via single cell RNA sequencing (scRNA-seq) we profiled over 30,000 immune cells from normal liver and PCLM with or without αGC treatment and were able to characterize the global changes of the immune cells in the tumor microenvironment upon αGC treatment, identifying a total of 12 subpopulations. Upon treatment with αGC, scRNA-Seq and flow cytometry analyses revealed increased cytotoxic activity of iNKT/NK cells and skewing CD4 T cells towards a cytotoxic Th1 profile and CD8 T cells towards a cytotoxic profile, characterized by higher proliferation and reduced exhaustion marker PD1 expression. Moreover, αGC treatment excluded tumor associated macrophages. Lastly, imaging mass cytometry analysis uncovered the reduced epithelial to mesenchymal transition related markers and increased active CD4 and CD8 T cells in PCLM with αGC treatment. Overall, our findings uncover the protective function of activated iNKT cells in pancreatic cancer liver metastasis through increased NK and T cell immunity and decreased tumor associated macrophages.