Immunology of Skin and Reactivity
Heather A.E. Benson, Michael S. Roberts, Vânia Rodrigues Leite-Silva, Kenneth A. Walters in Cosmetic Formulation, 2019
Innate lymphoid cells (ILCs) are a newly described and diverse group of immune cells which coordinate inflammatory responses in the skin and other tissues by cytokine production. ILCs in a range of tissues are divided into three subsets (ILC1, ILC2 and ILC3) based on their expression of cytokines and transcription factors. ILC1 consists of natural killer (NK) cells and other ILC1 cells that participate in viral immunity and are triggered by IL-12 and IL-18. The NK cells are the only ILC1 subset identified in healthy human skin and in increased number in psoriasis skin (Ebert et al., 2006). ILC2 cells were recently identified in human skin, and are reported to accumulate in the skin of atopic dermatitis and play a role in the induction of TH2 type dermatitis (Roediger et al., 2013). ILC3 is the dominant type of ILC present in the skin, and natural cytotoxicity triggering receptor positive ILC3 was found in circulation in healthy skin and in increased number in non-lesional psoriatic skin (Villanova et al., 2014).
Diagnostic tests in respiratory medicine
Vibeke Backer, Peter G. Gibson, Ian D. Pavord in The Asthmas, 2023
Asthma has long been considered a prototypical Th2-cell-mediated disease; thus, besides Th2 cells, other innate immune cells like basophils, B cells, mast cells and type-2 innate lymphoid cells (ILC2s) can produce Th2-cell-associated cytokines in asthma. The terminology has gradually shifted from ‘Th2-cell-high’ asthma to ‘type-2-high’ asthma, including both Th2 cells and ILC2s. Th2 cells are involved in producing IL4, IL5, IL10 and IL13, as well as antigen-specific IgE and IgG1. The role of ILC2s, as a source of type-2 cytokines and regulators of disease severity in human asthma, is an area of active research. Currently, IL5 and IL13 are predominant cytokines, whereas IL4 is less important. The best-known endotype of asthma is type-2-high asthma, characterised by airway and blood eosinophilia and the presence of biomarkers that depend on the type-2 cytokine IL13, such as periostin in serum and NO in exhaled breath (FeNO). Periostin and nitric oxide are both mainly produced by airway epithelial cells that express IL4Rα, and thus, respond to IL4 and/or IL13. Furthermore, TSLP is an epithelial cell–derived cytokine synthesised in response to various stimuli, an upstream alarmin, including protease allergens and microorganisms like viruses and bacteria. It is considered a master regulator of type-2 immune responses at the barrier surfaces of skin and the respiratory/gastrointestinal tract.
Overview of the mucosal immune system structure
Phillip D. Smith, Richard S. Blumberg, Thomas T. MacDonald in Principles of Mucosal Immunology, 2020
The innate lymphoid cells (ILS) have been studied recently in more detail (e.g. Penny et al. 2018). A major problem is that the localization within the lamina propria e.g. crypt or villous part has not been identified because these cells are characterized functionally but not by a cell surface marker to do immunohistology (Kortekaas Krohn et al. 2018). The composition of ILS subsets differs in their localization of different parts of the intestine and are significantly altered in HIV-infected patients (Krämer et al. 2017). Sometimes, natural killer cells are included in the ILS family. During the first years of life of human being, the number of NK cells decreased gradually. These cells were characterized by Eosomes, perforin, and granzyme B expression (Sagebiel et al. 2019).
Pregnancy immune tolerance at the maternal-fetal interface
Published in International Reviews of Immunology, 2020
Xiaopeng Li, Jiayi Zhou, Min Fang, Bolan Yu
Innate lymphoid cells (ILCs) are divided into five major groups based on their cytokine production patterns and developmental transcription factor requirements: NK cells, ILC1s, ILC2s, ILC3s, and lymphoid tissue-inducer (LTi) cells.61 Fetal LTi cells and postnatal ILC3s depend on the transcription factor RORγt. ILC3s are abundant in mucosal tissues where they contribute to defenses against pathogens and tissue homeostasis.62 Moreover, ILC3s with dominantly NCR positive phenotype are also identified in human decidua during early pregnancy, suggesting NCR+ILC3s may play a role in maintenance of pregnancy.63 ILC3s mainly produce CXCL8, which plays a role in decidual tissue building/remodeling.12 Decidual NCR+ ILC3s also produce IL-22, IL-8 and GM-CSF.64 GM-CSF was found to induce the expression of heparin-binding EGF-like growth factor (HB-EGF) and IL-1 receptor antagonist (IL-1Ra) in neutrophils.65 HB-EGF is a fibrogenic cytokine contributing to a successful pregnancy by regulating the interactions between endometrium and blastocyst, and promoting the angiogenesis at maternal-fetal interface.66 IL1Ra is involved in the trophoblasts invasion during early pregnancy.67 The crosstalk between NCR+ ILC3s and neutrophils at the maternal-fetal interface play a crucial role in maintaining a successful pregnancy.65
Role of IL-22 in acute asthma mouse model
Published in Journal of Asthma, 2023
Kyu Yean Kim, Jung Hur, Hwa Young Lee, Sook Young Lee
There are three major types of innate and adaptive cell-mediated effector immunities. Type 1 immunity involves protection against intracellular microbes through the activation of mononuclear phagocytes; it consists of the T-bet+ IFN-γ producing group 1 innate lymphoid cell (ILC) 1 and natural killer (NK) cells, CD8+ cytotoxic T cells (Tc1), and CD4+ Th1 cells. Type 2 immunity refers to protection against helminthes and venoms through IgE antibody production and activation of the mast cells, basophils, and eosinophils; it consists of the GATA-3+ ILC2s, Tc2 cells, and Th2 cells producing IL-4, IL-5, and IL-13. Type 3 immunity includes protection against extracellular bacteria and fungi by the activation of mononuclear phagocytes and recruitment of neutrophils; it is mediated by retinoic-acid-related orphan receptor γt+ ILC3s, Tc17 cells, and Th17 cells producing IL-17 and, IL-22 (6). The Th17 cells represent a distinct population of the CD4+ Th cells that mediate neutrophilic inflammation (7). IL-22 is produced during both the innate and adaptive phases of immune responses by various cells, such as the NK cells, ILCs, Th17 cells, and Th22 cells (8). IL-22 induces epithelial cell proliferation and expression of anti-apoptotic genes, thereby promoting tissue repair activity and protection of stem cells from injury. At the same time, it has been reported that the IL-22 signaling pathway participates in inflammatory diseases.
Targeting interleukin 4 and interleukin 13: a novel therapeutic approach in bullous pemphigoid
Published in Annals of Medicine, 2023
Fangyuan Chen, Yiman Wang, Xinyi Chen, Nan Yang, Li Li
ILC2 cells are innate lymphoid cells that can produce large amounts of type 2 cytokines. Considerable research has been conducted regarding the role of ILC2s in asthma. In mouse studies regarding the pathogenesis of asthma, it was revealed that ILC2s are major sources of IL-5 and IL-13 [63]. Interestingly, the authors found that when patients with asthma were treated with corticosteroids, cytokines produced by Th2 cells decreased but cytokines of ILC2s were not suppressed. These findings may explain the corticosteroid resistance in asthma patients [63]. The study from Bartemes et al. revealed that ILC2s were abundant in the peripheral blood of patients with allergic asthma, and ILC2s could be recruited to mucosal tissues through peripheral blood circulation. Furthermore, ILC2s also have the ability to induce eosinophil acumination in tissue [64]. However, allergic rhinitis, another Th2-dominant immune response disease, did not show an increase in ILC2s [64]. In skin diseases, ILC2s have been proven to be involved in AD [65], but there has been no research concerning ILC2s in BP. Although ILC2s may not able to be markers for Th2 immune response, further studies are needed to fully elucidate their role.
Related Knowledge Centers
- Innate Immune System
- Lymphopoiesis
- Myelocyte
- Lymphatic System
- Lymphocyte
- Cytokine
- Homeostasis
- T-Cell Receptor
- B-Cell Receptor
- Recombination-Activating Gene