Hypoxia-reprogrammed regulatory group 2 innate lymphoid cells promote immunosuppression in pancreatic cancer

Panoramic tumor microenvironment in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is notorious for its resistance to various treatment modalities. The genetic heterogeneity of PDAC, coupled with the presence of a desmoplastic stroma within the tumor microenvironment (TME), contributes to an unfavorable prognosis. The mechanisms and consequences of interactions among different cell types, along with spatial variations influencing cellular function, potentially play a role in the pathogenesis of PDAC. Understanding the diverse compositions of the TME and elucidating the functions of microscopic neighborhoods may contribute to understanding the immune microenvironment status in pancreatic cancer. As we delve into the spatial biology of the microscopic neighborhoods within the TME, aiding in deciphering the factors that orchestrate this intricate ecosystem. This overview delineates the fundamental constituents and the structural arrangement of the PDAC microenvironment, highlighting their impact on cancer cell biology.

Innate immune cells in tumor microenvironment: A new frontier in cancer immunotherapy

Innate immune cells, crucial in resisting infections and initiating adaptive immunity, play diverse and significant roles in tumor development. These cells, including macrophages, granulocytes, dendritic cells (DCs), innate lymphoid cells, and innate-like T cells, are pivotal in the tumor microenvironment (TME). Innate immune cells are crucial components of the TME, based on which various immunotherapy strategies have been explored. Immunotherapy strategies, such as novel immune checkpoint inhibitors, STING/CD40 agonists, macrophage-based surface backpack anchoring, ex vivo polarization approaches, DC-based tumor vaccines, and CAR-engineered innate immune cells, aim to enhance their anti-tumor potential and counteract cancer-induced immunosuppression. The proximity of innate immune cells to tumor cells in the TME also makes them excellent drug carriers. In this review, we will first provide a systematic overview of innate immune cells within the TME and then discuss innate cell-based therapeutic strategies. Furthermore, the research obstacles and perspectives within the field will also be addressed.

Bridging Chronic Inflammation and Digestive Cancer: The Critical Role of Innate Lymphoid Cells in Tumor Microenvironments

The incidence and mortality of digestive system-related cancers have always been high and attributed to the heterogeneity and complexity of the immune microenvironment of the digestive system. Furthermore, several studies have shown that chronic inflammation in the digestive system is responsible for cancer incidence; therefore, controlling inflammation is a potential strategy to stop the development of cancer. Innate Lymphoid Cells (ILC) represent a heterogeneous group of lymphocytes that exist in contrast to T cells. They function by interacting with cytokines and immune cells in an antigen-independent manner. In the digestive system cancer, from the inflammatory phase to the development, migration, and metastasis of tumors, ILC have been found to interact with the immune microenvironment and either control or promote these processes. The conventional treatments for digestive tumors have limited efficacy, therefore, ILC-associated immunotherapies are promising strategies. This study reviews the characterization of different ILC subpopulations, how they interact with and influence the immune microenvironment as well as chronic inflammation, and their promotional or inhibitory role in four common digestive system tumors, including pancreatic, colorectal, gastric, and hepatocellular cancers. In particular, the review emphasizes the role of ILC in associating chronic inflammation with cancer and the potential for enhanced immunotherapy with cytokine therapy and adoptive immune cell therapy.

Exploiting pancreatic cancer metabolism: challenges and opportunities

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive form of pancreatic cancer, known for its challenging diagnosis and limited treatment options. The focus on metabolic reprogramming as a key factor in tumor initiation, progression, and therapy resistance has gained prominence. In this review we focus on the impact of metabolic changes on the interplay among stromal, immune, and tumor cells, as glutamine and branched-chain amino acids (BCAAs) emerge as pivotal players in modulating immune cell functions and tumor growth. We also discuss ongoing clinical trials that explore metabolic modulation for PDAC, targeting mitochondrial metabolism, asparagine and glutamine addiction, and autophagy inhibition. Overcoming challenges in understanding nutrient effects on immune-stromal-tumor interactions holds promise for innovative therapeutic strategies.

Innate and adaptive immune-directed tumour microenvironment in pancreatic ductal adenocarcinoma

One of the most deadly and aggressive cancers in the world, pancreatic ductal adenocarcinoma (PDAC), typically manifests at an advanced stage. PDAC is becoming more common, and by the year 2030, it is expected to overtake lung cancer as the second greatest cause of cancer-related death. The poor prognosis can be attributed to a number of factors, including difficulties in early identification, a poor probability of curative radical resection, limited response to chemotherapy and radiotherapy, and its immunotherapy resistance. Furthermore, an extensive desmoplastic stroma that surrounds PDAC forms a mechanical barrier that prevents vascularization and promotes poor immune cell penetration. Phenotypic heterogeneity, drug resistance, and immunosuppressive tumor microenvironment are the main causes of PDAC aggressiveness. There is a complex and dynamic interaction between tumor cells in PDAC with stromal cells within the tumour immune microenvironment. The immune suppressive microenvironment that promotes PDAC aggressiveness is contributed by a range of cellular and humoral factors, which itself are modulated by the cancer. In this review, we describe the role of innate and adaptive immune cells, complex tumor microenvironment in PDAC, humoral factors, innate immune-mediated therapeutic advances, and recent clinical trials in PDAC.

Innate Lymphoid Cells in Bladder Cancer: From Mechanisms of Action to Immune Therapies

Bladder tumors have a high mutational burden and tend to be responsive to immune therapies; however, response rates remain modest. To date, immunotherapy in bladder cancer has largely focused on enhancing T-cell immune responses in the bladder tumor microenvironment. It is anticipated that other immune cells, including innate lymphoid cells (ILC), which play an important role in bladder oncogenesis and tumor suppression, could be targeted to improve response to existing therapies. ILCs are classified into five groups: natural killer cells, ILC1s, ILC2s, ILC3s, and lymphoid tissue inducer cells. ILCs are pleiotropic and play dual and sometimes paradoxical roles in cancer development and progression. Here, a comprehensive discussion of the current knowledge and recent advancements in understanding the role of ILCs in bladder cancer is provided. We discuss the multifaceted roles that ILCs play in bladder immune surveillance, tumor protection, and immunopathology of bladder cancer. This review provides a rationale for targeting ILCs in bladder cancer, which is relevant for other solid tumors.

Unravelling the immunobiology of innate lymphoid cells (ILCs): Implications in health and disease

Innate lymphoid cells (ILCs), a growing class of immune cells, imitate the appearance and abilities of T cells. However, unlike T cells, ILCs lack acquired antigen receptors, and they also do not undergo clonal selection or proliferation in response to antigenic stimuli. Despite lacking antigen-specific receptors, ILCs respond quickly to signals from infected or damaged tissues and generate an array of cytokines that regulate the development of adaptive immune response. ILCs can be categorized into four types based on their signature cytokines and transcription factors: ILC1, ILC2, ILC3 (including Lymphoid Tissue inducer- LTi cells), and regulatory ILCs (ILCregs). ILCs play key functions in controlling and resolving inflammation, and variations in their proportion are linked to various pathological diseases including cancer, gastrointestinal, pulmonary, and skin diseases. We highlight current advancements in the biology and classification of ILCs in this review. Additionally, we provide a thorough overview of their contributions to several inflammatory bone-related pathologies, including osteoporosis, rheumatoid arthritis, periodontitis, and ankylosing spondylitis. Understanding the multiple functions of ILCs in both physiological and pathological conditions will further mobilize future research towards targeting ILCs for therapeutic purposes.

Hypoxia induces immunosuppression, metastasis and drug resistance in pancreatic cancers

Pancreatic cancer is one of the common malignant tumors of the digestive system and is known as the "king of cancers". It is extremely difficult to diagnose at an early stage, the disease progresses rapidly, and the effect of chemotherapy and radiotherapy is poor, so the prognosis of pancreatic cancer patients is very poor. Numerous studies have suggested that hypoxia is closely related to the development and progression of pancreatic cancer. Inadequate blood supply and desmoplasia in the microenvironment of pancreatic cancer can result in its extreme hypoxia. This hypoxic microenvironment can further contribute to angiogenesis and desmoplasia. Hypoxia is mediated by the complex hypoxia inducible factor (HIF) signaling pathway and plays an important role in the formation of a highly immunosuppressive microenvironment and the metastasis of pancreatic cancer. Further work on the hypoxic microenvironment will help clarify the specific mechanisms of the role of hypoxia in pancreatic cancer and provide a basis for the realization of hypoxia-targeted therapeutic and diagnostic strategies.

Molecular and metabolic regulation of immunosuppression in metastatic pancreatic ductal adenocarcinoma

Immunosuppression is a hallmark of pancreatic ductal adenocarcinoma (PDAC), contributing to early metastasis and poor patient survival. Compared to the localized tumors, current standard-of-care therapies have failed to improve the survival of patients with metastatic PDAC, that necessecitates exploration of novel therapeutic approaches. While immunotherapies such as immune checkpoint blockade (ICB) and therapeutic vaccines have emerged as promising treatment modalities in certain cancers, limited responses have been achieved in PDAC. Therefore, specific mechanisms regulating the poor response to immunotherapy must be explored. The immunosuppressive microenvironment driven by oncogenic mutations, tumor secretome, non-coding RNAs, and tumor microbiome persists throughout PDAC progression, allowing neoplastic cells to grow locally and metastasize distantly. The metastatic cells escaping the host immune surveillance are unique in molecular, immunological, and metabolic characteristics. Following chemokine and exosomal guidance, these cells metastasize to the organ-specific pre-metastatic niches (PMNs) constituted by local resident cells, stromal fibroblasts, and suppressive immune cells, such as the metastasis-associated macrophages, neutrophils, and myeloid-derived suppressor cells. The metastatic immune microenvironment differs from primary tumors in stromal and immune cell composition, functionality, and metabolism. Thus far, multiple molecular and metabolic pathways, distinct from primary tumors, have been identified that dampen immune effector functions, confounding the immunotherapy response in metastatic PDAC. This review describes major immunoregulatory pathways that contribute to the metastatic progression and limit immunotherapy outcomes in PDAC. Overall, we highlight the therapeutic vulnerabilities attributable to immunosuppressive factors and discuss whether targeting these molecular and immunological "hot spots" could improve the outcomes of PDAC immunotherapies.

Targeting Potential of Innate Lymphoid Cells in Melanoma and Other Cancers

Reinvigorating the killing function of tumor-infiltrating immune cells through the targeting of regulatory molecules expressed on lymphocytes has markedly improved the prognosis of cancer patients, particularly in melanoma. While initially thought to solely strengthen adaptive T lymphocyte anti-tumor activity, recent investigations suggest that other immune cell subsets, particularly tissue-resident innate lymphoid cells (ILCs), may benefit from immunotherapy treatment. Here, we describe the recent findings showing immune checkpoint expression on tissue-resident and tumor-infiltrating ILCs and how their effector function is modulated by checkpoint blockade-based therapies in cancer. We discuss the therapeutic potential of ILCs beyond the classical PD-1 and CTLA-4 regulatory molecules, exploring other possibilities to manipulate ILC effector function to further impede tumor growth and quench disease progression.

Tissue-resident CXCR4+ macrophage as a poor prognosis signature promotes pancreatic ductal adenocarcinoma progression

Macrophage is an essential part of the tumor immune microenvironment of pancreatic ductal adenocarcinoma. In our study, we explored the CXCR4+ macrophages subset on its prognosis value, immune profile and distinct function in pancreatic cancer progression. Specimens from 102 postoperative pancreatic patients were analyzed by flow cytometry or immune-fluorescence, and the prognostic value of CXCR4+ macrophages infiltration was further determined by Cox regression. In silico analysis on TCGA, ICGC database and single-cell sequencing of pancreatic ductal adenocarcinoma further validated our findings. We found that high CXCR4+ macrophages infiltration was associated with poor overall survival (P < .01) and disease-free survival (P < .05) as an independent factor. CXCR4+ macrophages exhibited an M2 protumor phenotype with high expression of CD206. The function of CXCR4+ macrophages was further analyzed in the murine orthotopic PDAC model with its tumor promotion effect and inhibition of CD8+ T cells. Mechanistic and RNA-seq analysis showed that CXCR4+ macrophages participated in extracellular matrix remodeling procedures and especially secreted SPARC through CXCR4/PI3K/Akt pathway promoting tumor proliferation and migration. Our study reveals that CXCR4+ macrophages infiltration is an indicator of poor prognosis of PDAC and targeting these cells was potentially crucial in immunotherapy of PDAC.

Hypoxic microenvironment in cancer: molecular mechanisms and therapeutic interventions

Having a hypoxic microenvironment is a common and salient feature of most solid tumors. Hypoxia has a profound effect on the biological behavior and malignant phenotype of cancer cells, mediates the effects of cancer chemotherapy, radiotherapy, and immunotherapy through complex mechanisms, and is closely associated with poor prognosis in various cancer patients. Accumulating studies have demonstrated that through normalization of the tumor vasculature, nanoparticle carriers and biocarriers can effectively increase the oxygen concentration in the tumor microenvironment, improve drug delivery and the efficacy of radiotherapy. They also increase infiltration of innate and adaptive anti-tumor immune cells to enhance the efficacy of immunotherapy. Furthermore, drugs targeting key genes associated with hypoxia, including hypoxia tracers, hypoxia-activated prodrugs, and drugs targeting hypoxia-inducible factors and downstream targets, can be used for visualization and quantitative analysis of tumor hypoxia and antitumor activity. However, the relationship between hypoxia and cancer is an area of research that requires further exploration. Here, we investigated the potential factors in the development of hypoxia in cancer, changes in signaling pathways that occur in cancer cells to adapt to hypoxic environments, the mechanisms of hypoxia-induced cancer immune tolerance, chemotherapeutic tolerance, and enhanced radiation tolerance, as well as the insights and applications of hypoxia in cancer therapy.

Innate immunity in pancreatic cancer: Lineage tracing and function

Increasingly, patients with gastrointestinal tumors can benefit from immunotherapy, but not patients with pancreatic cancer. While this lack of benefit has been attributed to lower T-cell infiltration in pancreatic cancer, other studies have demonstrated the presence of numerous T cells in pancreatic cancer, suggesting another mechanism for the poor efficacy of immunotherapy. Single-cell RNA sequencing studies on the pancreatic cancer immune microenvironment have demonstrated the predominance of innate immune cells (e.g., macrophages, dendritic cells, mast cells, and innate immune lymphoid cells). Therefore, in-depth research on the source and function of innate immune lymphocytes in pancreatic cancer could guide pancreatic cancer immunotherapy.

Hypoxia activated HGF expression in pancreatic stellate cells confers resistance of pancreatic cancer cells to EGFR inhibition

BACKGROUND

Epidermal growth factor receptor (EGFR) is an essential target for cancer treatment. However, EGFR inhibitor erlotinib showed limited clinical benefit in pancreatic cancer therapy. Here, we showed the underlying mechanism of tumor microenvironment suppressing the sensitivity of EGFR inhibitor through the pancreatic stellate cell (PSC).

METHODS

The expression of alpha-smooth muscle actin (α-SMA) and hypoxia marker in human pancreatic cancer tissues were detected by immunohistochemistry, and their correlation with overall survival was evaluated. Human immortalized PSC was constructed and used to investigate the potential effect on pancreatic cancer cell lines in hypoxia and normoxia. Luciferase reporter assay and Chromatin immunoprecipitation were performed to explore the potential mechanisms in vitro. The combined inhibition of EGFR and Met was evaluated in an orthotopic xenograft mouse model of pancreatic cancer.

FINDINGS

We found that high expression levels of α-SMA and hypoxia markers are associated with poor prognosis of pancreatic cancer patients. Mechanistically, we demonstrated that hypoxia induced the expression and secretion of HGF in PSC via transcription factor HIF-1α. PSC-derived HGF activates Met, the HGF receptor, suppressing the sensitivity of pancreatic cancer cells to EGFR inhibitor in a KRAS-independent manner by activating the PI3K-AKT pathway. Furthermore, we found that the combination of EGFR inhibitor and Met inhibitor significantly suppressed tumor growth in an orthotopic xenograft mouse model.

INTERPRETATION

Our study revealed a previously uncharacterized HIF1α-HGF-Met-PI3K-AKT signaling axis between PSC and cancer cells and indicated that EGFR inhibition plus Met inhibition might be a promising strategy for pancreatic cancer treatment.

FUNDING

This study was supported by The National Natural Science Foundation of China.

Development and function of regulatory innate lymphoid cells

Innate lymphoid cells (ILCs) are a critical element of the innate immune system and are potent producers of pro-inflammatory cytokines. Recently, however, the production of the anti-inflammatory cytokine IL-10 has been observed in all ILC subtypes (ILC1s, ILC2s, and ILC3s) suggesting their ability to adopt a regulatory phenotype that serves to maintain lung and gut homeostasis. Other studies advocate a potential therapeutic role of these IL-10-expressing ILCs in allergic diseases such as asthma, colitis, and pancreatic islet allograft rejection. Herein, we review IL-10 producing ILCs, discussing their development, function, regulation, and immunotherapeutic potential through suppressing harmful inflammatory responses. Furthermore, we address inconsistencies in the literature regarding these regulatory IL-10 producing ILCs, as well as directions for future research.

Cancer immunosurveillance by ILC2s

Group 2 innate lymphoid cells (ILC2s) elicit ostensibly paradoxical responses, such as tissue repair and stimulation of tumorigenesis. Given emerging evidence that ILC2s also contribute to cancer immunosurveillance, we reassess the role of ILC2s in tumorigenesis and discuss recent insights into their tumoricidal potential.