Innate lymphoid cells in normal and disease: An introductory overview

Activation of CD81+ skin ILC2s by cold-sensing TRPM8+ neuron-derived signals maintains cutaneous thermal homeostasis

As the outermost barrier tissue of the body, the skin harbors a large number of innate lymphoid cells (ILCs) that help maintain local homeostasis in the face of changing environments. How skin-resident ILCs are regulated and function in local homeostatic maintenance is poorly understood. We here report the discovery of a cold-sensing neuron-initiated pathway that activates skin group 2 ILCs (ILC2s) to help maintain thermal homeostasis. In stearoyl-CoA desaturase 1 (SCD1) knockout mice whose skin is defective in heat maintenance, chronic cold stress induced excessive activation of CCR10^-CD81⁺ST2⁺ skin ILC2s and associated inflammation. Mechanistically, stimulation of the cold-sensing receptor TRPM8 expressed in sensory neurons of the skin led to increased production of IL-18, which, in turn, activated skin ILC2s to promote thermogenesis. Our findings reveal a neuroimmune link that regulates activation of skin ILC2s to support thermal homeostasis and promotes skin inflammation after hyperactivation.

Research progress on inflammatory mechanism of primary Sjögren syndrome

Primary Sjögren syndrome is an autoimmune disease, in which a large number of lymphocytes infiltrate the exocrine glands and cause gland dysfunction. Its pathogenesis is related to the chronic inflammation of the exocrine glands caused by genetic factors, immunodeficiency or viral infection. Long-term inflammation leads to accelerated apoptosis of epithelial cells, disordered gland structure, increased expression of proinflammatory cytokine such as CXC subfamily ligand (CXCL) 12, CXCL13, B cell-activating factor (BAF), interleukin (IL)-6, interferon (IFN)-γ and tumor necrosis factor (TNF)-α in submandibular gland. With the action of antigen-presenting cells such as dendritic cells and macrophages, lymphocytes (mainly B cells) are induced to mature in secondary lymphoid organs and migrate to the submandibular gland to promotes the formation of germinal centers and the synthesis of autoantibodies. Meanwhile, innate lymphocytes, vascular endothelial cells and mucosa-associated constant T cells as important immune cells, also participated in the inflammatory response of the submandibular gland in primary Sjögren syndrome through different mechanisms. This process involves the activation of multiple signal pathways such as JAK/STAT, MAPK/ERK, PI3K/AKT/mTOR, PD-1/PD-L1, TLR/MyD88/NF-κB, BAF/BAF-R and IFN. These signaling pathways interact with each other and are intricately complex, causing lymphocytes to continuously activate and invade the submandibular glands. This article reviews the latest literature to clarify the mechanism of submandibular gland inflammation in primary Sjögren syndrome, and to provide insights for further research.

The use of biologics in food allergy

BACKGROUND

Food allergy continues to pose problems due to its increased frequency and its increasingly high severity. In this context, alongside the traditional avoidance strategies of allergenic foods and desensitization through the cautious progression of exposure to foods in the context of oral immunotherapy (OIT), alternative strategies have made their way in the last decades. We review the possibilities of intervention in food allergy with the use of biological drugs capable of interfering with the synthesis of IgE, with their mechanisms of action, or with complex biological mechanisms that lead to the establishment of a food allergy.

METHODS

Repeated Entrez PubMed searches using the template algorithm "Food allergy" and "biologics" or "Omalizumab" or "Dupilumab" or "milk desensitization" or "oral tolerance induction" or "oral immunotherapy" or "Etokimab" or "Tezepelumab" or "Quilizumab" or "Ligelizumab" or "Tralokinumab" or "Nemolizumab" or "Mepolizumab" or "Reslizumab" or "Benralizumab". The authors' clinical experience in paediatric allergy units of University hospitals was also drawn upon.

RESULTS

The landscape in this context has changed dramatically over the past 10 years. We have acquired knowledge mainly on the effect of different types of anti-IgE treatments in poliallergic patients with food allergy, and in patients treated with OIT. However, other mediators are being targeted by specific biologic treatments. Among them, the alarmins Il-33 and TSLP, IL-4 and IL-13, eosinophil-related molecules as IL-6, IL-8, IL-10, IL-12, and mostly IL-5, and integrins involved in the pathogenesis of eosinophilic gastrointestinal diseases (EGIDs), as SIGLEC-8.

CONCLUSIONS

The ever-better knowledge of the mechanisms of food allergy allowing these developments will improve not only the perspective of patients with the most serious immediate food allergies such as anaphylaxis, but also those of patients with related diseases such as atopic dermatitis, eosinophilic esophagitis, and EGIDs. Biologics are also intended to complement OIT strategies that have developed over the years.

Humanized Mouse Models for the Advancement of Innate Lymphoid Cell-Based Cancer Immunotherapies

Innate lymphoid cells (ILCs) are a branch of the immune system that consists of diverse circulating and tissue-resident cells, which carry out functions including homeostasis and antitumor immunity. The development and behavior of human natural killer (NK) cells and other ILCs in the context of cancer is still incompletely understood. Since NK cells and Group 1 and 2 ILCs are known to be important for mediating antitumor immune responses, a clearer understanding of these processes is critical for improving cancer treatments and understanding tumor immunology as a whole. Unfortunately, there are some major differences in ILC differentiation and effector function pathways between humans and mice. To this end, mice bearing patient-derived xenografts or human cell line-derived tumors alongside human genes or human immune cells represent an excellent tool for studying these pathways in vivo. Recent advancements in humanized mice enable unparalleled insights into complex tumor-ILC interactions. In this review, we discuss ILC behavior in the context of cancer, the humanized mouse models that are most commonly employed in cancer research and their optimization for studying ILCs, current approaches to manipulating human ILCs for antitumor activity, and the relative utility of various mouse models for the development and assessment of these ILC-related immunotherapies.

Enteroviral Pathogenesis of Type 1 Diabetes: The Role of Natural Killer Cells

Enteroviruses, especially group B coxsackieviruses (CV-B), have been associated with the development of chronic diseases such as type 1 diabetes (T1D). The pathological mechanisms that trigger virus-induced autoimmunity against islet antigens in T1D are not fully elucidated. Animal and human studies suggest that NK cells response to CV-B infection play a crucial role in the enteroviral pathogenesis of T1D. Indeed, CV-B-infected cells can escape from cytotoxic T cells recognition and destruction by inhibition of cell surface expression of HLA class I antigen through non-structural viral proteins, but they can nevertheless be killed by NK cells. Cytolytic activity of NK cells towards pancreatic beta cells persistently-infected with CV-B has been reported and defective viral clearance by NK cells of patients with T1D has been suggested as a mechanism leading to persistence of CV-B and triggering autoimmunity reported in these patients. The knowledge about host antiviral defense against CV-B infection is not only crucial to understand the susceptibility to virus-induced T1D but could also contribute to the design of new preventive or therapeutic approaches for individuals at risk for T1D or newly diagnosed patients.

Immune Evasion of Enteroviruses Under Innate Immune Monitoring

As a major component of immunological defense against a great variety of pathogens, innate immunity is capable of activating the adaptive immune system. Viruses are a type of pathogen that proliferate parasitically in cells and have multiple strategies to escape from host immune pressure. Here, we review recent studies of the strategies and mechanisms by which enteroviruses evade innate immune monitoring.

Type 1 Diabetes and Its Multi-Factorial Pathogenesis: The Putative Role of NK Cells

Type 1 diabetes (T1D) affects millions of people worldwide and is the prevalent form of all pediatric diabetes diagnoses. T1D is recognized to have an autoimmune etiology, since failure in specific self-tolerance mechanisms triggers immune reactions towards self-antigens and causes disease onset. Among all the different immunocytes involved in T1D etiopathogenesis, a relevant role of natural killer cells (NKs) is currently emerging. NKs represent the interface between innate and adaptive immunity; they intervene in the defense against infections and present, at the same time, typical features of the adaptive immune cells, such as expansion and generation of memory cells. Several recent studies, performed both in animal models and in human diabetic patients, revealed aberrations in NK cell frequency and functionality in the peripheral blood and in damaged tissues, suggesting their possible redirection towards affected tissues. NKs oscillate from a quiescent to an activated state through a delicate balance of activating and inhibitory signals transduced via surface receptors. Further accurate investigations are needed to elucidate the exact role of NKs in T1D, in order to develop novel immune-based therapies able to reduce the disease risk or delay its onset.

Update on Aspirin-Exacerbated Respiratory Disease

Aspirin-exacerbated respiratory disease (AERD) is an acquired disease characterized by chronic eosinophilic airway inflammation with underlying dysregulation of arachidonic acid metabolism. The purpose of this paper is to review the latest developments in our understanding of the underlying pathophysiology including the role of eosinophils, mast cells, innate lymphoid cells (ILC₂), and platelets. Clinical features such as respiratory reactions induced by alcohol, aggressive nasal polyposis, and anosmia will allow for earlier recognition of these patients in clinical practice. The current state of the art management of AERD will be addressed including the ongoing central role for aspirin desensitization and high-dose aspirin therapy.

Diet-induced reconstruction of mucosal microbiota associated with alterations of epithelium lectin expression and regulation in the maintenance of rumen homeostasis

It is unknown whether lectins of the rumen epithelium contribute to the recognition of mucosal microbes and activation of tolerogenic cytokines in ruminant animals. We applied an integrated method of RNA-seq and 16S rRNA gene sequencing to investigate alterations of epithelial lectin expression and regulation with a diet-induced reconstruction of the mucosal microbiota in the goat rumen. Our results showed that the diversity and richness of the rumen mucosal microbiota were promoted by the dietary concentrate. Meantime, in the rumen epithelium, five lectin genes, namely, sialic acid-binding Ig-like lectin 14 (LOC102180073), C-type lectin domain family 4, member E (CLEC4E), C-type lectin domain family 7, member A (CLEC7A), C-type lectin domain family 16, member A (CLEC16A), and lectin, mannose-binding 2 (LMAN2), were indicated to promote the expression of 8 tolerogenic cytokines, transforming growth factor beta 1 (TGFB1) and 4 enzyme genes involved in retinoic acid biosynthesis via 6 signaling pathways. Analysis of the combined data showed that 9 microbial genera (Clostridium_IV, Desulfobulbus, Eubacterium, Ochrobactrum, Propionibacterium, Pseudomonas, Slackia, Staphylococcus and Subdivision5_genera_IS) were highly related to the expression of functional lectins. These findings provide new insights into the interactions between the rumen epithelium and mucosal microbiota in the maintenance of rumen homeostasis.