NKT cells act through third party bone marrow-derived cells to suppress NK cell activity in the liver and exacerbate hepatic melanoma metastases

Role of T cells in liver metastasis

The liver is a major metastatic site (organ) for gastrointestinal cancers (such as colorectal, gastric, and pancreatic cancers) as well as non-gastrointestinal cancers (such as lung, breast, and melanoma cancers). Due to the innate anatomical position of the liver, the apoptosis of T cells in the liver, the unique metabolic regulation of hepatocytes and other potential mechanisms, the liver tends to form an immunosuppressive microenvironment and subsequently form a pre-metastatic niche (PMN), which can promote metastasis and colonization by various tumor cells(TCs). As a result, the critical role of immunoresponse in liver based metastasis has become increasingly appreciated. T cells, a centrally important member of adaptive immune response, play a significant role in liver based metastases and clarifying the different roles of the various T cells subsets is important to guide future clinical treatment. In this review, we first introduce the predisposing factors and related mechanisms of liver metastasis (LM) before introducing the PMN and its transition to LM. Finally, we detail the role of different subsets of T cells in LM and advances in the management of LM in order to identify potential therapeutic targets for patients with LM.

A Comprehensive Pan-cancer Analysis of the Biological Immunomodulatory Function and Clinical Value of CD27

Background: CD27 is an immunological checkpoint gene, plays a critical function inInhibition or activation of cancer immunity. The CD27/CD27L axis is its pathway of action. Therefore, our goal was to examine the predictive role of CD27 in the clinical prognosis of 33 cancer types and its functions in cancer progression, as well as explore the link between pan-cancer CD27 gene expression and immune infiltration. Methods: By comprehensive use of datasets and methods from TCGA, cBioPortal, GTEx, HPA, KM-plotter, Spearman, CellMinerTM, R packages and RT-qPCR, we delved deeper into the potential impact of the CD27 on cancer development. These include expression differences, immune infiltration, matrix infiltration, gene mutations, DNA methylation, signaling pathways, TMB, MSI, and prognosis. Also, we explored CD27 interactions with different drugs. Results: The results showed that, mutated CD27 was highly expressed in most cancers. The CD27 showed strong diagnostic value in 4 cancers and marked a positive prognosis for CESC, intracervical adenocarcinoma, HNSC, and endometrial cancer, and a poor prognosis for UVM. In addition, CD27 affects multiple immune and inflammatory signaling pathways and is positively correlated with immune cell infiltration, T cell differentiation, macrophage M1 polarization, stromal infiltration, and drug sensitivity. DNA methylation is involved in CD27 expression in cancer. Conclusion: CD27, which is mutated in cancers and appears widely highly expressed and altered tumor immune invasion and stromal invasion by affecting multiple immune-related and inflammation signaling pathways, plays a significant role in CESC, HNSC, UCEC and UVM, and may be used as a therapeutic target for related cancers.

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.

Radiotherapy induced immunogenic cell death by remodeling tumor immune microenvironment

Emerging evidence indicates that the induction of radiotherapy(RT) on the immunogenic cell death (ICD) is not only dependent on its direct cytotoxic effect, changes in the tumor immune microenvironment also play an important role in it. Tumor immune microenvironment (TIME) refers to the immune microenvironment that tumor cells exist, including tumor cells, inflammatory cells, immune cells, various signaling molecules and extracellular matrix. TIME has a barrier effect on the anti-tumor function of immune cells, which can inhibit all stages of anti-tumor immune response. The remodeling of TIME caused by RT may affect the degree of immunogenicity, and make it change from immunosuppressive phenotype to immunostimulatory phenotype. It is of great significance to reveal the causes of immune escape of tumor cells, especially for the treatment of drug-resistant tumor. In this review, we focus on the effect of RT on the TIME, the mechanism of RT in reversing the TIME to suppress intrinsic immunity, and the sensitization effect of the remodeling of TIME caused by RT on the effectiveness of immunotherapy.

Lipid metabolic features of T cells in the Tumor Microenvironment

The tumor microenvironment (TME) is characterized by discrete changes in metabolic features of cancer and immune cells, with various implications. Cancer cells take up most of the available glucose to support their growth, thereby leaving immune cells with insufficient nutrients to expand. In the relative absence of glucose, T cells switch the metabolic program to lipid-based sources, which is pivotal to T-cell differentiation and activation in nutrient-stressed TME. Although consumption of lipids should provide an alternative energy source to starving T cells, a literature survey has revealed that it may not necessarily lead to antitumor responses. Different subtypes of T cells behave differently in various lipid overload states, which widely depends upon the kind of free fatty acids (FFA) engulfed. Key lipid metabolic genes provide cytotoxic T cells with necessary nutrients for proliferation in the absence of glucose, thereby favoring antitumor immunity, but the same genes cause immune evasion in T_mem and T_reg. This review aims to detail the complexity of differential lipid metabolism in distinct subtypes of T cells that drive the antitumor or pro-tumor immunity in specific TME states. We have identified key drug targets related to lipid metabolic rewiring in TME.

Imaging α-GalCer-activated iNKT cells in a hepatic metastatic environment

Colorectal cancer patients frequently develop liver metastases after, and perhaps as a consequence of, lifesaving surgical resection of the primary tumor. This creates a potential opportunity for prophylactic metastatic treatment with novel immunostimulatory molecules. Here, we used state-of-the-art intravital imaging of an experimental liver metastasis model to visualize the early behavior and function of invariant (i)NKT cells stimulated with α-galactosylceramide (α-GalCer). Intravenous α-GalCer prior to tumor cell seeding in the liver significantly inhibited tumor growth. However, some seeding tumor cells survived. A multiple dosing regimen reduced tumor burden and prolonged the life of mice, whereas tumors returned within 5 days after a single dose of α-GalCer. With multiple doses of α-GalCer, iNKT cells increased in number and granularity (as did NK cells). As a result, the total number of contacts and time in contact with tumors increased substantially. In the absence of iNKT cells, the beneficial effect of α-GalCer was lost. Robust cytokine production dissipated over time. Repeated therapy, even after cytokine dissipation, led to reduced tumor burden and prolonged survival. Serial transplantation of tumors exposed to α-GalCer-activated iNKT cells did not induce greater resistance, suggesting no obvious epigenetic or genetic immunoediting in tumors exposed to activated iNKT cells. Very few tumor cells expressed CD1d in this model, and as such, adding monomers of CD1d-α-GalCer further reduced tumor growth. The data suggest early and repeated stimulation of iNKT cells with α-GalCer could have direct therapeutic benefit for colorectal cancer patients that develop metastatic liver disease.

Identification of survival-related genes and a novel gene-based prognostic signature involving the tumor microenvironment of uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular malignant tumor in adults and almost fifty percent of patients subsequently develop systemic metastases usually involving the liver. The tumor microenvironment (TME) is crucial to the initiation and progression of tumors. In the present study, we comprehensively evaluated the TME of primary UM samples from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database by using several bioinformatic algorithms. The prognostic value of immune score and infiltrating immune cells in the TME were evaluated. Differentially expressed genes between the low- and high-immune score groups were also identified. The majority of tumor-infiltrating lymphocytes in UM have been determined to be activated CD8 + T cells. Therefore, weighted gene co-expression network analysis (WGCNA) was performed to identify the co-expression modules and genes significantly associated with the level of infiltrating CD8 + T cells in UM. Survival-related genes involved in the TME were identified by univariate Cox regression analysis. Furthermore, an eight-gene-based prognostic signature was established in the training dataset TCGA-UM via Lasso-penalized and multivariate Cox regression analyses. The predictive value of this signature was validated in two testing datasets. Besides, a nomogram was established to serve clinical practice. Moreover, hub genes involved in the infiltrating CD8 + T cells were identified and a potential targeted therapy for preventing metastasis of UM was proposed based on the results. In summary, our results provided a robust gene-based prognostic signature for predicting prognosis of UM patients and proposed a potential targeted therapy for preventing UM metastasis.

Defective FasL expression is associated with increased resistance to melanoma liver metastases and enhanced natural killer cell activity

The objective was to determine if the absence of FasL signaling would affect melanoma liver metastases by influencing the antimelanoma properties of liver natural killer (NK) cells. Melanoma liver metastases were induced in wild-type C57BL/6 mice and the gld/gld mutant C57BL/6 mouse strain that expresses a defective form of FasL (CD95L) that fails to engage and signal via the Fas receptor (CD95). Liver metastases were produced by intrasplenic injection of B16LS9 melanoma cells. Liver NK cell activity directed against murine B16LS9 melanoma cells was determined in a 24 h in-vitro cytotoxicity assay. Liver NK cells, NK T cells, and the NK cell surface activation marker, NKG2D, were measured by flow cytometry. Mice expressing defective FasL displayed reduced, rather than enhanced, melanoma liver metastases that coincided with increased liver NK cell-mediated tumor cell cytotoxicity. Enhanced cytotoxicity was not mediated by perforin, tumor necrosis factor-α, or tumor necrosis-associated apoptosis-inducing ligand but was closely associated with elevated interferon-γ in the tumor-bearing liver. FasL-defective gld/gld mice also displayed reduced numbers of liver NK T cells, which have been previously implicated in suppression on liver NK cell activity. The absence of functional FasL in the liver correlates with a heightened, not diminished, resistance to melanoma liver metastases. The resistance to liver metastases coincides with a significant, albeit transient, increase in liver NK cytotoxicity and elevated levels of interferon-γ in the liver.

Uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. UMs are usually initiated by a mutation in GNAQ or GNA11, unlike cutaneous melanomas, which usually harbour a BRAF or NRAS mutation. The annual incidence in Europe and the USA is ~6 per million population per year. Risk factors include fair skin, light-coloured eyes, congenital ocular melanocytosis, ocular melanocytoma and the BAP1-tumour predisposition syndrome. Ocular treatment aims at preserving the eye and useful vision and, if possible, preventing metastases. Enucleation has largely been superseded by various forms of radiotherapy, phototherapy and local tumour resection, often administered in combination. Ocular outcomes are best with small tumours not extending close to the optic disc and/or fovea. Almost 50% of patients develop metastatic disease, which usually involves the liver, and is usually fatal within 1 year. Although UM metastases are less responsive than cutaneous melanoma to chemotherapy or immune checkpoint inhibitors, encouraging results have been reported with partial hepatectomy for solitary metastases, with percutaneous hepatic perfusion with melphalan or with tebentafusp. Better insight into tumour immunology and metabolism may lead to new treatments.

Immunobiology of Uveal Melanoma: State of the Art and Therapeutic Targets

Uveal Melanoma (UM) represents the most common primary intraocular malignant tumor in adults. Although it originates from melanocytes as cutaneous melanoma, it shows significant clinical and biological differences with the latter, including high resistance to immune therapy. Indeed, UM can evade immune surveillance via multiple mechanisms, such as the expression of inhibitory checkpoints (e.g., PD-L1, CD47, CD200) and the production of IDO-1 and soluble FasL, among others. More in-depth understanding of these mechanisms will suggest potential targets for the design of novel and more effective management strategies for UM patients.

The influence of microenvironment on tumor immunotherapy

Tumor immunotherapy has achieved remarkable efficacy, with immune-checkpoint inhibitors as especially promising candidates for cancer therapy. However, some issues caused by immunotherapy have raised attention, such as limited efficacy for some patients, narrow antineoplastic spectrum, and adverse reactions, suggesting that using regulators of tumor immune response may prove to be more complicated than anticipated. Current evidence indicates that different factors collectively constituting the unique tumor microenvironment promote immune tolerance, and these include the expression of co-inhibitory molecules, the secretion of lactate, and competition for nutrients between tumor cells and immune cells. Furthermore, cancer-associated fibroblasts, the main cellular components of solid tumors, promote immunosuppression through inhibition of T cell function and extracellular matrix remodeling. Here, we summarize the research advances in tumor immunotherapy and the latest insights into the influence of microenvironment on tumor immunotherapy.

Altered Lipid Tumor Environment and Its Potential Effects on NKT Cell Function in Tumor Immunity

Natural killer T (NKT) cells are CD1d restricted T cells that mostly recognize lipid antigens. These cells share characteristics with both adaptive and innate immune cells and have multiple immunoregulatory roles. In a manner similar to innate immune cells, they respond quickly to stimuli and secrete large amounts of cytokines, amplifying and modulating the immune response. As T cells, they express T cell receptors (TCRs) and respond in an antigen-specific manner like conventional T cells. There are at least two subtypes of NKT cells, type I and type II, that differ in the nature of their TCR, either semi-invariant (type I) or diverse (type II). The two sub-types generally have opposing functions in tumor immunity, with type I promoting and type II suppressing tumor immunity, and they cross-regulate each other, forming an immunoregulatory axis. The tumor has multiple mechanisms by which it can evade immune-surveillance. One such mechanism involves alteration in tumor lipid repertoire and accumulation of lipids and fatty acids that favor tumor growth and evade anti-tumor immunity. Since NKT cells mostly recognize lipid antigens, an altered tumor lipid metabolic profile will also alter the repertoire of lipid antigens that can potentially affect their immune-modulatory function. In this review, we will explore the effects of alterations in the lipid metabolites on tumor growth, antigen cross-presentation, and overall effect on anti-tumor immunity, especially in the context of NKT cells.

The influence of microenvironment on tumor immunotherapy

Tumor immunotherapy has achieved remarkable efficacy, with immune-checkpoint inhibitors as especially promising candidates for cancer therapy. However, some issues caused by immunotherapy have raised attention, such as limited efficacy for some patients, narrow antineoplastic spectrum, and adverse reactions, suggesting that using regulators of tumor immune response may prove to be more complicated than anticipated. Current evidence indicates that different factors collectively constituting the unique tumor microenvironment promote immune tolerance, and these include the expression of co-inhibitory molecules, the secretion of lactate, and competition for nutrients between tumor cells and immune cells. Furthermore, cancer-associated fibroblasts, the main cellular components of solid tumors, promote immunosuppression through inhibition of T cell function and extracellular matrix remodeling. Here, we summarize the research advances in tumor immunotherapy and the latest insights into the influence of microenvironment on tumor immunotherapy.

Natural killer cells and pigment epithelial-derived factor control the infiltrative and nodular growth of hepatic metastases in an Orthotopic murine model of ocular melanoma

Background

Metastases account for 90% of all cancer-related deaths, becoming a therapeutic problem. Approximately 50% of all uveal melanoma (UM) patients will develop metastases, mainly in the liver. Post-mortem analyses of livers from metastatic UM patients showed two different metastatic growth patterns: infiltrative and nodular. The infiltrative pattern exhibits tumor infiltration directly to the hepatic lobule and minimal angiogenesis. The nodular pattern shows clusters of tumor cells around the portal venules that efface the liver parenchyma. We recently demonstrated Natural Killer (NK) cells play a pivotal role in the control of hepatic metastases and the pigment epithelial-derived factor (PEDF) controls angiogenesis in the liver using our established ocular melanoma animal model. In this study we investigated the role of NK cells and PEDF in the development of metastatic growth patterns, as this can contribute to the development of novel therapeutics specific towards each growth pattern.

Methods

We utilize our established ocular melanoma animal model by inoculation of B16-LS9 melanoma cells into C57BL/6 J mice (WT), anti-asialo GM1-treated C57BL/6 J mice (NK-depleted), and PEDF^−/− C57BL/6 J mice. Three weeks after inoculation we evaluated the metastatic growth patterns and stratified them based of the numbers of tumor cells. To evaluate angiogenesis the mean vascular density (MVD) was calculated. The immune compartment of the liver was analyzed by flow cytometry.

Results

Our in vivo work showed two distinct metastatic growth patterns, the infiltrative and nodular, recapitulating the post-mortem analyses on human liver tissue. We discovered NK cells control the infiltrative growth. In contrast, PEDF controlled anti-angiogenic responses, showing higher MVD values compared to NK-depleted and WT animals. The myeloid lineage, comprised of monocytes, macrophages, and myeloid-derived suppressor cells, was reduced in the absence of NK cells or PEDF.

Conclusions

Our animal model recapitulates the metastatic growth patterns observed in the human disease. We demonstrated a role for NK cells in the development of the infiltrative growth pattern, and a role for PEDF in the development of the nodular pattern. The understanding of the complexity associated with the metastatic progression has profound clinical implications in the diagnostic and disease-management as we can develop and direct more effective therapies.

The Role of Invariant NKT in Autoimmune Liver Disease: Can Vitamin D Act as an Immunomodulator?

Natural killer T (NKT) cells are a distinct lineage of T cells which express both the T cell receptor (TCR) and natural killer (NK) cell markers. Invariant NKT (iNKT) cells bear an invariant TCR and recognize a small variety of glycolipid antigens presented by CD1d (nonclassical MHC-I). CD1d-restricted iNKT cells are regulators of immune responses and produce cytokines that may be proinflammatory (such as interferon-gamma (IFN-γ)) or anti-inflammatory (such as IL-4). iNKT cells also appear to play a role in B cell regulation and antibody production. Alpha-galactosylceramide (α-GalCer), a derivative of the marine sponge, is a potent stimulator of iNKT cells and has been proposed as a therapeutic iNKT cell activator. Invariant NKT cells have been implicated in the development and perpetuation of several autoimmune diseases such as multiple sclerosis and systemic lupus erythematosus (SLE). Animal models of SLE have shown abnormalities in iNKT cells numbers and function, and an inverse correlation between the frequency of NKT cells and IgG levels has also been observed. The role of iNKT cells in autoimmune liver disease (AiLD) has not been extensively studied. This review discusses the current data with regard to iNKT cells function in AiLD, in addition to providing an overview of iNKT cells function in other autoimmune conditions and animal models. We also discuss data regarding the immunomodulatory effects of vitamin D on iNKT cells, which may serve as a potential therapeutic target, given that deficiencies in vitamin D have been reported in various autoimmune disorders.

The role of hepatic macrophages in liver metastasis

The liver is a major target organ for metastasis of both gastrointestinal and extra-gastrointestinal cancers. Due to its frequently inoperable nature, liver metastasis represents a leading cause of cancer-associated death worldwide. In the past years, the pivotal role of the immune system in this process is being increasingly recognised. In particular, the role of the hepatic macrophages, both recruited monocyte-derived macrophages (Mo-Mfs) and tissue-resident Kupffer cells (KCs), has been shown to be more versatile than initially imagined. However, the lack of tools to easily distinguish between these two macrophage populations has hampered the assignment of particular functionalities to specific hepatic macrophage subsets. In this Review, we highlight the most remarkable findings regarding the origin and functions of hepatic macrophage populations, and we provide a detailed description of their distinct roles in the different phases of the liver metastatic process.

Growth and Metastasis of Intraocular Tumors in Aged Mice

Purpose

Since deterioration of the immune apparatus is closely associated with cancer, we examined the effect of aging on the growth and metastasis of intraocular melanomas in mice.

Methods

Murine B16LS9 melanoma cells were transplanted into the posterior compartment of the eye (vitreous chamber) and intraocular tumor growth and development of liver metastases were evaluated in young (8–10 weeks of age) and old (>18 months of age) mice. Liver metastases were also induced by intrasplenic injection of melanoma cells. Natural killer (NK) cells from the livers of mice harboring liver metastases were evaluated in vitro for their cytolytic activity.

Results

Tumors grew more rapidly in the eyes of young mice than old mice, yet old mice developed significantly more liver metastases. Increased liver metastasis in old mice was evident even when melanoma cells were injected intrasplenically as a means of bypassing the influence of the ocular immunosuppressive environment. Increased liver metastases in old mice correlated with reduced cytolytic activity of liver NK cells. Lethally irradiated young mice reconstituted with bone marrow from old donors developed significantly more liver metastases than young mice reconstituted with bone marrow from young donors, indicating that bone marrow–derived cells were the root cause of the heightened development of metastases in old mice.

Conclusions

Aging affects the growth and metastasis of intraocular melanomas. Even though intraocular melanomas grow slower in old mice, the development of liver metastases is exacerbated and correlates with a reduction in liver NK cell activity in the old mouse.

Natural Killer T Cells Contribute to Neutrophil Recruitment and Ocular Tissue Damage in a Model of Intraocular Tumor Rejection

PURPOSE

Immune privilege of the eye protects the nonregenerative ocular tissues from innate and adaptive immune-mediated inflammation. In the case of intraocular tumors, immune privilege can be arrested to allow for immune-mediated rejection. Activation of innate immune cells can contribute to necrosis of the intraocular tumor and bystander ocular tissue. Identifying the cellular components of the innate immune system that contribute to ocular destruction, but are not needed for tumor rejection, provides insights into the immunopathological sequelae in intraocular tumor rejection.

METHODS

Wild-type (WT), Jα18 knockout (KO) mice lacking type I natural killer T (NKT) cells, and CD1d KO mice lacking all NKT cells, were used to identify the role of type II NKT cells in intraocular tumor rejection immunopathology.

RESULTS

CD1d KO mice had significantly lowered rates of necrotic eye destruction during tumor rejection compared to WT or Jα18 KO mice. Transcriptome and protein analyses revealed that CD1d KO mice had significantly lower expression of CXCL3 compared to WT or Jα18 KO mice, and this was associated with decreased neutrophil recruitment. The presence of type II NKT cells in WT or Jα18 KO mice led to increased CXCL3, which attracted neutrophils to the intraocular tumor and culminated in destruction of the eye.

CONCLUSIONS

We found that type II NKT cells are critical in initiating a damaging inflammatory antitumor response involving the recruitment of neutrophils that compromises the integrity of the eye. Loss of type II NKT cells or depleting neutrophils allows for a productive intraocular tumor response that converts the rejection phenotype to preserve the eye.

Sleep-deprivation reduces NK cell number and function mediated by β-adrenergic signalling

Reduction of sleep time triggers a stress response, leading to augmented levels of glucocorticoids and adrenaline. These hormones regulate components of the innate immune system such as natural killer (NK) and NKT cells. In the present study, we sought to investigate whether and how stress hormones could alter the population and function of NK and NKT cells of mice submitted to different lengths of paradoxical sleep deprivation (PSD, from 24 to 72 h). Results showed that 72h of PSD decreased not only NK and NKT cell counts, but also their cytotoxic activity against B16F10 melanoma cells in vitro. Propranolol treatment during PSD reversed these effects, indicating a major inhibitory role of beta-adrenergic receptors (β-AR) on NK cells function. Moreover, both corticosterone plasma levels and expression of beta 2-adrenergic receptors (β2-AR) in NK cells increased by 48 h of PSD. In vitro incubation of NK cells with dexamethasone augmented the level of β2-AR in the cell surface, suggesting that glucocorticoids could induce β2-AR expression. In summary, we propose that reduction of NK and NKT cell number and cytotoxic activity appears to be mediated by glucocorticoids-induced increased expression of β2-AR in these cells.