Functions of Group 2 Innate Lymphoid Cells in Tumor Microenvironment

Orchestration of immune response by innate lymphoid cell subtype 2 at various tumor microenvironment, a suitable target for cancer immunotherapy

Innate lymphoid cells are a mixed population of cells and critical regulators of our innate immune system. According to recent scientific literature, tissue resident innate lymphoid cell subtype 2 has been recognized as an important player of type 2 inflammatory responses, involved in different human malignancies like pancreatic, lung, acute myeloid leukemia, gastrointestinal tract cancer, etc. The current reports have revealed that, among the three main ILC sub types, subtype 2 (ILC 2), as the key regulator of initiating the type 2 inflammatory responses at the tumor microenvironment (TME). This activation of ILC-2 is a very important step for the specific downstream functioning of ILC-2. Priming of ILC-2 with different chemokines involves different cytokine secretion from the activated ILC-2 like IL-4, IL-5, IL-13, IL-9 which induce type 2 inflammatory responses involved in the complex interaction with other immune cells like NK cell, Cytotoxic T cell, MDSC and Treg cell. At the initial stage, ILC-2 activation through IL-33 may induce the anti-tumorigenic effect mediated by ILC-2/eosinophil axis. However, it is also evident that PDG2 (Prostaglandin D2)-mediated activation of ILC-2 induces the ILC-2/MDSC immune suppressive pro-tumorigenic niche at the TME. Here, in this review, we have summarized the function of ILC-2 on cancer immunity based on recent scientific work which indicates ILC-2 plays a dual role and orchestrates the immune responses toward type 2 immunity in different cancer settings.

Emerging Concepts in Innate Lymphoid Cells, Memory, and Reproduction

Members of the innate immune system, innate lymphoid cells (ILCs), encompass five major populations (Natural Killer (NK) cells, ILC1s, ILC2s, ILC3s, and lymphoid tissue inducer cells) whose functions include defense against pathogens, surveillance of tumorigenesis, and regulation of tissue homeostasis and remodeling. ILCs are present in the uterine environment of humans and mice and are dynamically regulated during the reproductive cycle and pregnancy. These cells have been repurposed to support pregnancy promoting maternal immune tolerance and placental development. To accomplish their tasks, immune cells employ several cellular and molecular mechanisms. They have the capacity to remember a previously encountered antigen and mount a more effective response to succeeding events. Memory responses are not an exclusive feature of the adaptive immune system, but also occur in innate immune cells. Innate immune memory has already been demonstrated in monocytes/macrophages, neutrophils, dendritic cells, and ILCs. A population of decidual NK cells characterized by elevated expression of NKG2C and LILRB1 as well as a distinctive transcriptional and epigenetic profile was found to expand during subsequent pregnancies in humans. These cells secrete high amounts of interferon-γ and vascular endothelial growth factor likely favoring placentation. Similarly, uterine ILC1s in mice upregulate CXCR6 and expand in second pregnancies. These data provide evidence on the development of immunological memory of pregnancy. In this article, the characteristics, functions, and localization of ILCs are reviewed, emphasizing available data on the uterine environment. Following, the concept of innate immune memory and its mechanisms, which include epigenetic changes and metabolic rewiring, are presented. Finally, the emerging role of innate immune memory on reproduction is discussed. Advances in the comprehension of ILC functions and innate immune memory may contribute to uncovering the immunological mechanisms underlying female fertility/infertility, placental development, and distinct outcomes in second pregnancies related to higher birth weight and lower incidence of complications.

Suppressive Myeloid Cells Shape the Tumor Immune Microenvironment

Cancer is the outcome of the conflict between the host immune system and cancer cells. The crosstalk between immune cells and tumor cells within the tumor microenvironment (TME) influences tumor progression and metastasis. Many studies have clarified the cellular and molecular events that can induce cancer cells to escape immune surveillance, including those involving tumor-induced myeloid cell-mediated immunosuppression. Emerging evidence indicates that tumor-infiltrating myeloid cells (TIMs) accelerate tumor growth and induce angiogenesis, metastasis, and therapy resistance once converted into potent immunosuppressive cells. Here, how tumor infiltrating myeloid cells participate in tumor immune evasion and the prospects of these cells in cancer immunotherapy are discussed.

ILC in chronic inflammation, cancer and targeting with biologicals

Since their discovery, Innate Lymphoid Cells (ILC) have emerged as important effector cells, serving multiple roles in maintaining tissue homeostasis and responding to tissue insults. As such, dysregulations of their function and distribution have been observed in a variety of immune-mediated diseases, suggesting a specific role for ILC in the pathophysiology of several disorders including chronic inflammation and cancer. Here, we provide an updated view on ILC biology dissecting their pathological or protective contribution in chronic inflammatory diseases such as multiple sclerosis, inflammatory bowel diseases, psoriasis, rheumatoid arthritis, asthma and COPD, atherosclerosis, also exploring ILC role in tumor surveillance and progression. Throughout the review, we will also highlight how the potential dual role of these cells for protective or pathogenic immunity in many inflammatory diseases makes them interesting targets for the development of novel therapeutic strategies, particularly promising.