Jiawei Yanghe Decoction attenuate allergic airway inflammation by suppressing group 2 innate lymphoid cells responses

ETHNOPHARMACOLOGICAL RELEVANCE

Jiawei Yanghe Decoction (JWYHD) is modified Yanghe Decoction (YHD). YHD historically utilized as a potent medicinal solution for addressing chronic inflammatory conditions, holds promising therapeutic potential in the treatment of asthma. However, the mechanisms underlying JWYHD's effects on allergic asthma remain unclear.

AIM OF THE STUDY

To investigate the therapeutic effect as well as the underlying mechanisms of JWYHD on asthmatic mice.

MATERIALS AND METHODS

The ovalbumin (OVA)-induced mouse model was utilized, followed by the administration of JWYHD to allergic asthmatic mice. Subsequently, inflammatory cells in the bronchoalveolar lavage fluid (BALF) and lung tissues were conducted. The levels of various cytokines including interleukin (IL)-4, IL-5, IL-13, IL-33, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ in BALF, as well as the total immunoglobulin E (IgE) content in serum, were assessed. Lung function and tissue pathology examinations were performed to assess the protective impacts of JWYHD. The chemical components of JWYHD and its lung prototype compounds (referred to the chemical components present in JWYHD that were observed in the lung) were explored by ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS). RNA-seq analysis revealed the regulation mechanisms of JWYHD treating asthma. Furthermore, the effect of JWYHD on type 2 innate lymphoid cells (ILC2s) in asthmatic mice was detected by flow cytometry and Smart-RNA-seq analysis. Then molecular docking analysis was used to show the interaction between identified compounds and key targets.

RESULTS

JWYHD significantly attenuated the airway inflammation of asthmatic mice, reduced the levels of inflammatory cells in BALF, as well the levels of the cytokines IL-4, IL-5, IL-13, IL-33, and TNF-α in BALF and IgE in serum. Airway hyperresponsiveness (AHR) and lung inflammation infiltration were also alleviated by JWYHD. Moreover, RNA-seq analysis revealed that JWYHD attenuated airway inflammation in asthmatic mice via regulating immunity. Flow cytometry confirmed that JWYHD could inhibit ILC2 responses. ILC2 Smart-RNA-seq analysis showed that JWYHD impaired the inflammation reaction-related signaling pathways in ILC2s, and neuropilin-1 (Nrp1), endothelial transcription factor 3 (GATA3) and interleukin 1 receptor like protein 1 (ST2) might be the key targets. The molecular docking analysis investigating the connection between the primary targets and JWYHD's prototype compounds in the lung demonstrated that liquiritin apioside, icariin, glycyrrhizic acid, and uralsaponin B, identified through UPLC-Q-TOF/MS, exhibited significant affinity in binding to the mentioned key targets.

CONCLUSION

Our results suggested that the mechanism of JWYHD in treating asthma might be related to limiting ILC2 responses. Our findings provided some pharmacological evidence for the clinical application of JWYHD in the treatment of asthma.

Tumor cells inhibit the activation of ILC2s through up-regulating PD-1 expression

OBJECTIVE

Up-regulating programmed cell death ligand-1(PD-L1) expressed on tumor cells and tumor-infiltrating myeloid cells interacting with up-regulated programmed cell death-1 (PD-1) expressed on tumor-infiltrating lymphoid cells greatly hinder their tumor-inhibiting effect. It is necessary to explore the deep mechanism of this negative effect, so as to find the potential methods to improve the immunotherapy efficiency.

METHODS AND RESULTS

In this study, we found that the PD-1 expression in lung cancer-infiltrating type II innate lymphoid cells (ILC2s) was highly up-regulated, which greatly restrained the activation and function of ILC2s. Furthermore, anti-PD-1 could restore the inhibition and effective cytokine secretion of ILC2s when co-cultured with tumor cells. In vivo studies proved that anti-PD-1 treatment promoted the activation of tumor-infiltrating ILC2s and inhibited the tumor growth of LLC-bearing nude mice.

DISCUSSION

Our studies demonstrate a new PD-1/PD-L1 axis regulating mechanism on innate immune cells, which provide a useful direction to ILC2s-based immunotherapy to cancer diseases.

New insights into ILC2 memory

Group 2 Innate Lymphoid Cells (ILC2s) are innate lymphocytes involved in type 2 immunity. ILC2s are abundant at the barrier tissues and upon allergen exposure, respond to epithelial-derived alarmins by producing type 2 cytokines (e.g., IL-5 and IL-13). Upon activation, some of these activated ILC2s acquire immunological memory and can mount enhanced responses upon further allergen encounters. Here, we review recent findings of the cellular and molecular mechanisms underlying immune memory in ILC2s both in mice and humans and discuss the implications of memory ILC2s in the context of allergic diseases.

ILC2s: Unraveling the innate immune orchestrators in allergic inflammation

The prevalence rate of allergic diseases including asthma, atopic rhinitis (AR) and atopic dermatitis (AD) has been significantly increasing in recent decades due to environmental changes and social developments. With the study of innate lymphoid cells, the crucial role played by type 2 innate lymphoid cells (ILC2s) have been progressively unveiled in allergic diseases. ILC2s, which are a subset of innate lymphocytes initiate allergic responses. They respond swiftly during the onset of allergic reactions and produce type 2 cytokines, working in conjunction with T helper type 2 (Th2) cells to induce and sustain type 2 immune responses. The role of ILC2s represents an intriguing frontier in immunology; however, the intricate immune mechanisms of ILC2s in allergic responses remain relatively poorly understood. To gain a comphrehensive understanding of the research progress of ILC2, we summarize recent advances in ILC2s biology in pathologic allergic inflammation to inspire novel approaches for managing allergic diseases.

The Prostaglandin D2 Receptor CRTH2 Contributes to Airway Hyperresponsiveness during Airway Inflammation Induced by Sensitization without an Adjuvant in Mice

INTRODUCTION

Prostaglandin D2 (PGD2), which is produced mainly by Th2 cells and mast cells, promotes a type-2 immune response by activating Th2 cells, mast cells, eosinophils, and group 2 innate lymphoid cells (ILC2s) via its receptor, chemoattractant receptor-homologous molecules on Th2 cells (CRTH2). However, the role of CRTH2 in models of airway inflammation induced by sensitization without adjuvants, in which both IgE and mast cells may play major roles, remain unclear.

METHODS

Wild-type (WT) and CRTH2-knockout (KO) mice were sensitized with ovalbumin (OVA) without an adjuvant and then challenged intranasally with OVA. Airway inflammation was assessed based on airway hyperresponsiveness (AHR), lung histology, number of leukocytes, and levels of type-2 cytokines in the bronchoalveolar lavage fluid (BALF).

RESULTS

AHR was significantly reduced after OVA challenge in CRTH2 KO mice compared to WT mice. The number of eosinophils, levels of type-2 cytokines (IL-4, IL-5, and IL-13) in BALF, and IgE concentration in serum were decreased in CRTH2 KO mice compared to WT mice. However, lung histological changes were comparable between WT and CRTH2 KO mice.

CONCLUSION

CRTH2 is responsible for the development of asthma responses in a mouse model of airway inflammation that features prominent involvement of both IgE and mast cells.

The ST2+ Treg/amphiregulin axis protects from immune-mediated hepatitis

Introduction

The alarmin IL-33 has been implicated in the pathology of immune-mediated liver diseases. IL-33 activates regulatory T cells (Tregs) and type 2 innate lymphoid cells (ILC2s) expressing the IL-33 receptor ST2. We have previously shown that endogenous IL-33/ST2 signaling activates ILC2s that aggravate liver injury in murine immune-mediated hepatitis. However, treatment of mice with exogenous IL-33 before induction of hepatitis ameliorated disease severity. Since IL-33 induces expression of amphiregulin (AREG) crucial for Treg function, we investigated the immunoregulatory role of the ST2+ Treg/AREG axis in immune-mediated hepatitis.

Methods

C57BL/6, ST2-deficient (Il1rl1-/-) and Areg-/- mice received concanavalin A to induce immune-mediated hepatitis. Foxp3Cre+ x ST2fl/fl mice were pre-treated with IL-33 before induction of immune-mediated hepatitis. Treg function was assessed by adoptive transfer experiments and suppression assays. The effects of AREG and IL-33 on ST2+ Tregs and ILC2s were investigated in vitro. Immune cell phenotype was analyzed by flow cytometry.

Results and discussion

We identified IL-33-responsive ST2+ Tregs as an effector Treg subset in the murine liver, which was highly activated in immune-mediated hepatitis. Lack of endogenous IL-33 signaling in Il1rl1-/- mice aggravated disease pathology. This was associated with reduced Treg activation. Adoptive transfer of exogenous IL-33-activated ST2+ Tregs before induction of hepatitis suppressed inflammatory T-cell responses and ameliorated disease pathology. We further showed increased expression of AREG by hepatic ST2+ Tregs and ILC2s in immune-mediated hepatitis. Areg-/- mice developed more severe liver injury, which was associated with enhanced ILC2 activation and less ST2+ Tregs in the inflamed liver. Exogenous AREG suppressed ILC2 cytokine expression and enhanced ST2+ Treg activation in vitro. In addition, Tregs from Areg-/- mice were impaired in their capacity to suppress CD4+ T-cell activation in vitro. Moreover, application of exogenous IL-33 before disease induction did not protect Foxp3Cre+ x ST2fl/fl mice lacking ST2+ Tregs from immune-mediated hepatitis. In summary, we describe an immunoregulatory role of the ST2+ Treg/AREG axis in immune-mediated hepatitis, in which AREG suppresses the activation of hepatic ILC2s while maintaining ST2+ Tregs and reinforcing their immunosuppressive capacity in liver inflammation.

Communication between Mast Cells and Group 2 Innate Lymphoid Cells in the Skin

The skin is a dynamic organ with a complex immune network critical for maintaining balance and defending against various pathogens. Different types of cells in the skin, such as mast cells (MCs) and group 2 innate lymphoid cells (ILC2s), contribute to immune regulation and play essential roles in the early immune response to various triggers, including allergens. It is beneficial to dissect cell-to-cell interactions in the skin to elucidate the mechanisms underlying skin immunity. The current manuscript concentrates explicitly on the communication pathways between MCs and ILC2s in the skin, highlighting their ability to regulate immune responses, inflammation, and tissue repair. Furthermore, it discusses how the interactions between MCs and ILC2s play a crucial role in various skin conditions, such as autoimmune diseases, dermatological disorders, and allergic reactions. Understanding the complex interactions between MCs and ILC2s in different skin conditions is crucial to developing targeted treatments for related disorders. The discovery of shared pathways could pave the way for novel therapeutic interventions to restore immunological balance in diseased skin tissues.

Allergen immunotherapy combined with Notch pathway inhibitors improves HDM-induced allergic airway inflammation and inhibits ILC2 activation

Introduction

Group 2 innate lymphoid cells (ILC2s) play a crucial role in house dust mite (HDM)-induced allergic inflammation, and allergen immunotherapy (AIT) holds promise for treating the disease by reducing the frequency of ILC2s. Despite significant progress in AIT for allergic diseases, there remains a need to improve the control of allergic symptoms.

Methods

We investigated the synergistic effect of the Notch signaling pathway and subcutaneous immunotherapy (SCIT) in treating allergic airway inflammation in mice and their impact on the ratio of ILC2s in lung tissues. This was achieved by establishing the HDM-induced airway allergic disorders (HAAD) model and SCIT model. Additionally, we conducted in vitro investigations into the effect of the Notch signaling pathway on the secretory function of activated ILC2s using fluorescence-activated cell sorting. Furthermore, we explored the coactivation of the Notch signaling pathway with SCIT in vitro by sorting ILC2s from the lung tissues of mice after SCIT modeling.

Results

Previously, our group demonstrated that Notch signaling pathway inhibitors can reduce allergic airway inflammation in mice. Notch signaling induces lineage plasticity of mature ILC2s. In this study, we showed that AIT alleviates allergic airway inflammation and suppresses the frequency of ILC2s induced by HDM. Interestingly, AIT combined with a γ-secretase inhibitor (GSI), an inhibitor of the Notch signaling pathway, significantly inhibited the frequency of ILC2s, reduced airway inflammation, and suppressed Th2-type responses in a mouse model. Furthermore, lung ILC2s from HDM-challenged mice with or without AIT were treated with GSI in vitro, and we found that GSI dramatically reduced the secretion of type 2 inflammatory factors in ILC2s.

Discussion

These findings suggest that Notch signaling pathway inhibitors can be used as adjuvant therapy for AIT and may hold potential treatment value in the cooperative control of allergic airway inflammation during early AIT.

Therapeutic application of human type 2 innate lymphoid cells via induction of granzyme B-mediated tumor cell death

The therapeutic potential for human type 2 innate lymphoid cells (ILC2s) has been underexplored. Although not observed in mouse ILC2s, we found that human ILC2s secrete granzyme B (GZMB) and directly lyse tumor cells by inducing pyroptosis and/or apoptosis, which is governed by a DNAM-1-CD112/CD155 interaction that inactivates the negative regulator FOXO1. Over time, the high surface density expression of CD155 in acute myeloid leukemia cells impairs the expression of DNAM-1 and GZMB, thus allowing for immune evasion. We describe a reliable platform capable of up to 2,000-fold expansion of human ILC2s within 4 weeks, whose molecular and cellular ILC2 profiles were validated by single-cell RNA sequencing. In both leukemia and solid tumor models, exogenously administered expanded human ILC2s show significant antitumor effects in vivo. Collectively, we demonstrate previously unreported properties of human ILC2s and identify this innate immune cell subset as a member of the cytolytic immune effector cell family.

DCLK1 and tuft cells: Immune-related functions and implications for cancer immunotherapy

DCLK1, a tuft cell marker, is widely expressed in various tumors. Its high expression levels are closely linked to malignant tumor progression, making it a potential tumor-related marker. Recent studies have shed light on the critical roles of DCLK1 and tuft cells in the immune response and the maintenance of epithelial homeostasis, as well as targeted immune escape mechanisms in the tumor microenvironment. This review aims to comprehensively examine the current understanding of immune-related functions mediated by DCLK1 and tuft cells in epithelial tissues, including the roles of relevant cells and important factors involved. Additionally, this review will discuss recent advances in anti-tumor immunity mediated by DCLK1/tuft cells and their potential as immunotherapeutic targets. Furthermore, we will consider the potential impact of DCLK1 targeted therapy in cancer immunotherapy, particularly DCLK1 kinase inhibitors as potential therapeutic drugs in anti-tumor immunity, providing a new perspective and reference for future research.

Efficient and stable CRISPR/Cas9-mediated genome-editing of human type 2 innate lymphoid cells

Innate lymphoid cells (ILCs) are a family of innate lymphocytes with important roles in immune response coordination and maintenance of tissue homeostasis. The ILC family includes group 1 (ILC1s), group 2 (ILC2s) and group 3 (ILC3s) 'helper' ILCs, as well as cytotoxic Natural Killer (NK) cells. Study of helper ILCs in humans presents several challenges, including their low proportions in peripheral blood or needing access to rare samples to study tissue resident ILC populations. In addition, the lack of established protocols harnessing genetic manipulation platforms has limited the ability to explore molecular mechanism regulating human helper ILC biology. CRISPR/Cas9 is an efficient genome editing tool that enables the knockout of genes of interest, and is commonly used to study molecular regulation of many immune cell types. Here, we developed methods to efficiently knockout genes of interest in human ILC2s. We discuss challenges and lessons learned from our CRISPR/Cas9 gene editing optimizations using a nucleofection transfection approach and test a range of conditions and nucleofection settings to obtain a protocol that achieves effective and stable gene knockout while maintaining optimal cell viability. Using IL-4 as a representative target, we compare different ribonucleoprotein configurations, as well as assess effects of length of time in culture and other parameters that impact CRISPR/Cas9 transfection efficiency. Collectively, we detail a CRISPR/Cas9 protocol for efficient genetic knockout to aid in studying molecular mechanism regulating human ILC2s.

Xiao-qing-long-tang ameliorates OVA-induced allergic rhinitis by inhibiting ILC2s through the IL-33/ST2 and JAK/STAT pathways

BACKGROUND

Allergic rhinitis (AR) is a chronic inflammatory disease of the nasal mucosa that is mediated by immunoglobulin E (IgE). Xiao-qing-long-tang (XQLT) is a traditional Chinese medicine compound that is widely used to treat respiratory diseases such as AR. However, the underlying mechanism of the effect of XQLT on AR remains unclear.

PURPOSE

To elucidate the effect of XQLT on ovalbumin (OVA)-induced AR and the mechanisms of action.

METHODS

The therapeutic efficacy of XQLT was evaluated in a well-established OVA-induced AR mouse model. Nasal symptoms were analyzed, type 2 cytokines and OVA-sIgE levels were measured, nasal mucosa tissues were collected for histological analysis, and the changes of Group 2 innate lymphoid cells (ILC2s) and the IL-33/ST2 and JAK/STAT signaling pathways in the nasal mucosa were observed.

RESULTS

XQLT significantly alleviated the nasal symptoms and histological damage to the nasal mucosa in AR mice, and reduced the levels of type 2 cytokines and OVA-sIgE. In addition, after XQLT treatment, the numbers of ILC2s in the nasal mucosa of AR mice were reduced, and the mRNA levels of the transcription factors GATA3 and ROR-α were decreased. Moreover, IL-33/ST2 signaling pathway was inhibited. The costimulatory cytokine associated JAK/STAT signaling pathway was also inhibited in ILC2s.

CONCLUSION

Our study demonstrated that XQLT regulated ILC2s through the IL-33/ST2 and JAK/STAT pathways to ameliorate type 2 inflammation in OVA-induced AR. These findings suggest that XQLT might be used to treat AR.

Interferons as negative regulators of ILC2s in allergic lung inflammation and respiratory viral infections

Group 2 innate lymphoid cells (ILC2s), characterized by a lack of antigen receptors, have been regarded as an important component of type 2 pulmonary immunity. Analogous to Th2 cells, ILC2s are capable of releasing type 2 cytokines and amphiregulin, thus playing an essential role in a variety of diseases, such as allergic diseases and virus-induced respiratory diseases. Interferons (IFNs), an important family of cytokines with potent antiviral effects, can be triggered by microbial products, microbial exposure, and pathogen infections. Interestingly, the past few years have witnessed encouraging progress in revealing the important role of IFNs and IFN-producing cells in modulating ILC2 responses in allergic lung inflammation and respiratory viral infections. This review underscores recent progress in understanding the role of IFNs and IFN-producing cells in shaping ILC2 responses and discusses disease phenotypes, mechanisms, and therapeutic targets in the context of allergic lung inflammation and infections with viruses, including influenza virus, rhinovirus (RV), respiratory syncytial virus (RSV), and severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2).

Vitamin D3 resolved human and experimental asthma via B lymphocyte-induced maturation protein 1 in T cells and innate lymphoid cells

Background

Vitamin D3 (VitD3) is known to have immunomodulatory functions, and VitD3 deficiency is associated with more severe asthma.

Objective

We aimed to assess the immunoregulatory effects of VitD3 food supplementation on asthma manifestation, with particular focus on T cells and type 2 innate lymphoid cells.

Methods

Preschool children and adult asthmatic cohorts were analyzed in the context of VitD3 supplementation and serum levels. In a murine model of ovalbumin-induced asthma, effects of diet VitD3 sufficiency and deficiency on T cells and type 2 innate lymphoid cells immune mechanisms were investigated.

Results

We found less severe and better-controlled asthma phenotypes along with reduced need for steroid medication in preschool children and asthmatic adults with VitD3 supplementation. VitD3 serum levels correlated with B lymphocyte-induced maturation protein 1 (Blimp-1) expression in blood peripheral mononuclear cells. VitD3-supplement-fed mice showed decreased asthmatic traits, with a decrease in IgE serum levels, reduced airway mucus, and increased IL-10 production by lung cells. Furthermore, we discovered an upregulation of effector T cells and Blimp-1+ lung tissue-resident memory T cells as well as induction of anti-inflammatory Blimp-1+ lung innate lymphoid cells producing IL-10.

Conclusion

Supplementing VitD3 resulted in amelioration of clinical asthma manifestations in human studies as well as in experimental allergic asthma, indicating that VitD3 shifts proinflammatory immune responses to anti-inflammatory immune responses via upregulating Blimp-1 in lung innate lymphoid cells and tissue-resident memory cells.

ILC2s control obesity by regulating energy homeostasis and browning of white fat

Innate lymphoid cells (ILCs) have been a hot topic in recent research, they are widely distributed in vivo and play an important role in different tissues. The important role of group 2 innate lymphoid cells (ILC2s) in the conversion of white fat into beige fat has attracted widespread attention. Studies have shown that ILC2s regulate adipocyte differentiation and lipid metabolism. This article reviews the types and functions of ILCs, focusing on the relationship between differentiation, development and function of ILC2s, and elaborates on the relationship between peripheral ILC2s and browning of white fat and body energy homeostasis. This has important implications for the future treatment of obesity and related metabolic diseases.

Induction of Siglec-FhiCD101hi eosinophils in the lungs following murine hookworm Nippostrongylus brasiliensis infection

Helminth-induced eosinophils accumulate around the parasite at the site of infection, or in parasite-damaged tissues well after the helminth has left the site. The role of helminth-elicited eosinophils in mediating parasite control is complex. While they may contribute to direct parasite-killing and tissue repair, their involvement in long-term immunopathogenesis is a concern. In allergic Siglec-F^hiCD101^hi, eosinophils are associated with pathology. Research has not shown if equivalent subpopulations of eosinophils are a feature of helminth infection. In this study, we demonstrate that lung migration of rodent hookworm Nippostrongylus brasiliensis (Nb) results in a long-term expansion of distinct Siglec-F^hiCD101^hi eosinophil subpopulations. Nb-elevated eosinophil populations in the bone marrow and circulation did not present this phenotype. Siglec-F^hiCD101^hi lung eosinophils exhibited an activated morphology including nuclei hyper-segmentation and cytoplasm degranulation. Recruitment of ST2⁺ ILC2s and not CD4⁺ T cells to the lungs was associated with the expansion of Siglec-F^hiCD101^hi eosinophils. This data identifies a morphologically distinct and persistent subset of Siglec-F^hiCD101^hi lung eosinophils induced following Nb infection. These eosinophils may contribute to long-term pathology following helminth infection.

Crosstalk between ILC2s and Th2 cells varies among mouse models

Type 2 T helper (Th2) cells and group 2 innate lymphoid cells (ILC2s) provide protection against helminth infection and are involved in allergic responses. However, their relative importance and crosstalk during type 2 immune responses are still controversial. By generating and utilizing mouse strains that are deficient in either ILC2s or Th2 cells, we report that interleukin (IL)-33-mediated ILC2 activation promotes the Th2 cell response to papain; however, the Th2 cell response to ovalbumin (OVA)/alum immunization is thymic stromal lymphopoietin (TSLP) dependent but independent of ILC2s. During helminth infection, ILC2s and Th2 cells collaborate at different phases of the immune responses. Th2 cells, mainly through IL-4 production, induce the expression of IL-25, IL-33, and TSLP, among which IL-25 and IL-33 redundantly promote ILC2 expansion. Thus, while Th2 cell differentiation can occur independently of ILC2s, activation of ILC2s may promote Th2 responses, and Th2 cells can expand ILC2s by inducing type 2 alarmins.

Sodium Butyrate Ameliorates Type 2 Diabetes-Related Sarcopenia Through IL-33-Independent ILC2s/IL-13/STAT3 Signaling Pathway

Purpose

Sarcopenia has been described as a new complication of type 2 diabetes mellitus (T2DM). T2DM and sarcopenia impact each other, resulting in a variety of adverse outcomes such as frailty, disability, poor quality of life and increased mortality. Sodium butyrate (NaB) is reported to play a protective role against T2DM. The present study aimed to investigate whether NaB could ameliorate T2DM-related sarcopenia and the underlying mechanisms.

Materials and Methods

The male db/db mice at 7-weeks were used as T2DM-related sarcopenia animal model with C57BL/6J mice as control. Mice were grouped according to whether they received NaB orally as follows: C57BL/6J+water group, C57BL/6J+NaB group, db/db+water group, and db/db+NaB group. Then, db/db mice receiving NaB orally were administered with inhibitors of group 2 innate lymphocytes (ILC2s), anti-CD90.2 by intraperitoneal injection divided into db/db+NaB+PBS group and db/db+NaB+anti-CD90.2 group. NaB dissolved in water at 150 mM. The skeletal muscle mass was measured by dural X-ray (DXA) test. ILC2s in spleen and skeletal muscle were evaluated by flow cytometry. The expressions of IL-33, IL-13, STAT3, P-STAT3, GATA-3 and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) were assessed by ELISA or WB. The morphology of skeletal muscle fibers was assessed by immunofluorescence staining.

Results

The proportion of ILC2s and the expressions of ILC2s markers IL-13 and GATA-3 were all significantly decreased in db/db mice, and these changes were improved by NaB. NaB increased the proportion of slow-twitch fibers in gastrocnemius, thus partially reversing the reduced exercise capacity of db/db mice. The expression of slow-twitch fibers marker PGC-1α induced by NaB was increased via activation of ILC2s/IL-13/STAT3 pathway. On the other way, IL-33 was not necessary for the activation of ILC2s/IL-13/STAT3 pathway. After depletion of ILC2s by anti-CD90.2, the ameliorating effect of NaB on T2DM-related sarcopenia was partially antagonized.

Conclusion

These results indicated that NaB could ameliorate type 2 diabetes-related sarcopenia by activating IL-33-independent ILC2s/IL-13/STAT3 signaling pathway.

Contribution of IL-33/ILC2-mediated Th2 cytokines during the progression of minimal change disease

Minimal change disease (MCD) is a common type of nephrotic syndrome with high recurrence rate. This study aims to explore the impacts of interleukin (IL)-33 in MCD and to discuss its potential mechanism. In adriamycin (ADM) and puromycin aminonucleoside (PAN)-induced MCD rat model, IL-33 was used for treatment. H&E staining was applied for detecting histological changes. Critical proteins were examined by western blot. Corresponding commercial kits tested oxidative stress- and inflammation-related factors. Cell apoptosis was measured by TUNEL assay. ADM-induced podocyte injury model was establish to mimic MCD in vitro. Cell proliferation and apoptosis were detected by CCK-8 and TUNEL assays. Finally, podocyte was stimulated by innate lymphoid type-2 cells-secreted Th2 cytokines (ILC2s: IL-13 and IL-5 respectively), with or without incubation with M1 macrophage medium to further explore the immune-regulation of ILC2s behind the inflammatory environment of MCD. It was found that PAN-induced kidney jury, inflammation, oxidative stress and apoptosis were severer than ADM, and IL-33 treatment significantly alleviated the above injuries in PAN and ADM-induced MCD rat model. Moreover, IL-33 reversed the reduced viability and increased oxidative stress and apoptosis in ADM-induced podocyte injury model. Further, the capacities of IL-13 alone in inducing M1/M2 macrophage polarization, apoptosis, inflammation, kidney injury and reducing cell viability are stronger than IL-5. However, IL-13 reversed reduced cell viability and stimulated apoptosis, inflammation, kidney injury mediated by co-incubation with M1-conditioned medium. Collectively, IL-33 might protect against immunologic injury in MCD via mediating ILC2s-secreted IL-13.

Identification of two migratory colon ILC2 populations differentially expressing IL-17A and IL-5/IL-13

Group 2 innate lymphoid cells (ILC2s) play important tissue resident roles in anti-parasite immunity, allergic immune response, tissue homeostasis, and tumor immunity. ILC2s are considered tissue resident cells with little proliferation at steady state. Recent studies have shown that a subset of small intestinal ILC2s could leave their residing tissues, circulate and migrate to different organs, including lung, liver, mesenteric LN and spleen, upon activation. However, it remains unknown whether other ILC populations with migratory behavior exist. In this study, we find two major colon ILC2 populations with potential to migrate to the lung in response to IL-25 stimulation. One subset expresses IL-17A and resembles inflammatory ILC2s (iILC2s) but lacks CD27 expression, whereas the other expresses CD27 but not IL-17A. In addition, the IL-17A⁺ ILC2s express lower levels of CD127, CD25, and ST2 than CD27⁺ ILC2s, which express higher levels of IL-5 and IL-13. Surprisingly, we found that both colon ILC2 populations still maintained their colonic features of preferential expression of IL-17A and CD27, IL-5/IL-13, respectively. Together, our study identifies two migratory colon ILC2 subsets with unique surface markers and cytokine profiles which are critical in regulating lung and colon immunity and homeostasis.

Current summary of clinical studies on anti-TSLP antibody, Tezepelumab, in asthma

Thymic stromal lymphopoietin (TSLP) is an epithelial cell-derived cytokine that plays a vital role in the induction of type 2 inflammation via both innate and acquired immune cascades. Tezepelumab, a human IgG2 monoclonal antibody that inhibits the binding of TSLP to the TSLP receptor, is the latest biologic for asthma. To evaluate the efficacy and mechanism of tezepelumab in asthma, the PATHWAY, NAVIGATOR, NOZOMI, UPSTREAM, CASCADE, SOURCE, and DESTINATION studies have been conducted. These results suggested that tezepelumab is a broad-target biologic, which is expected to be effective in patients with poorly controlled moderate to severe asthma regardless of the phenotype, although its efficacy in oral corticosteroids-dependent asthma, biological mechanism in non-type 2 phenotype, and long-term safety remain unknown. In this review, we summarize the results of clinical trials of tezepelumab in asthma and discuss the differences between tezepelumab and other biologics.

Group 2 innate lymphoid cells in human asthma

Asthma is characterized by increased airway hyperresponsiveness, reversible airflow limitation, and remodeling due to allergic airway inflammation. Asthma has been proposed to be classified into various phenotypes by cluster analyses integrating clinical information and laboratory data. Recently, asthma has been classified into two major endotypes, Type 2-high and Type 2-low asthma, and various subtypes based on the underlying molecular mechanisms. In Type 2-high asthma, Th2 cells, together with group 2 innate lymphoid cells (ILC2s), produce type 2 cytokines such as IL-4, IL-5, IL-9, and IL-13, which play crucial roles in causing airway inflammation. The roles of ILC2s in asthma pathogenesis have been analyzed primarily in murine models, demonstrating their importance not only in IL-33- or papain-induced innate asthma models but also in house dust mite (HDM)- or ovalbumin (OVA)-induced acquired asthma models evoked in an antigen-specific manner. Recently, evidence regarding the roles of ILC2s in human asthma is also accumulating. This minireview summarizes the roles of ILC2s in asthma, emphasizing human studies.

IL-33 attenuates renal fibrosis via group2 innate lymphoid cells

Renal fibrosis is a common pathway in the progression of various kidney diseases and injuries. Unilateral ureteral obstruction (UUO) induces renal fibrosis, and immune responses profoundly affect its pathogenesis. Group2 innate lymphoid cells (ILC2s) are strongly activated by interleukin (IL) -33, which is a member of IL-1 family and recognize as alarmin. ILC2s quickly produce large amounts of type 2 cytokines including IL-5 and IL-13, which are involved in inflammation, tissue homeostasis, and wound healing. However, the relationship between renal fibrosis and ILC2s has been unclear. In the present study, we investigated the roles of the ILC2/L-33 axis in renal fibrosis using a UUO model. We found that kidney ILC2s decreased in UUO-affected kidneys compared with their counterpart kidneys despite IL-33 upregulation. There was no effect of reactive oxygen species or TGF-β from reduced ILC2 caused by UUO. Pretreatment with IL-33 before UUO induced ILC2s and Tregs in kidneys and alleviated renal fibrosis. Furthermore, this protective effect was maintained even when CD4⁺T cells was depleted. These findings demonstrated that ILC2s play a predominant role in the suppressive function of renal fibrosis mediated by pretreatment with IL-33. In contrast, post-treatment with IL-33 after UUO increased ILC2s in kidneys but had no therapeutic effect on renal fibrosis. Our findings suggest that ILC2s have potential roles in the prevention of renal fibrosis and can serve as a therapeutic and diagnostic target.

Crosstalk between macrophages and innate lymphoid cells (ILCs) in diseases

Innate lymphoid cells (ILCs) and macrophages are tissue-resident cells that play important roles in tissue-immune homeostasis and immune regulation. ILCs are mainly distributed on the barrier surfaces of mammals to ensure immunity or tissue homeostasis following host, microbial, or environmental stimulation. Their complex relationships with different organs enable them to respond quickly to disturbances in environmental conditions and organ homeostasis, such as during infections and tissue damage. Gradually emerging evidence suggests that ILCs also play complex and diverse roles in macrophage development, homeostasis, polarization, inflammation, and viral infection. In turn, macrophages also determine the fate of ILCs to some extent, which indicates that network crossover between these interactions is a key determinant of the immune response. More work is needed to better define the crosstalk of ILCs with macrophages in different tissues and demonstrate how it is affected during inflammation and other diseases. Here, we summarize current research on the functional interactions between ILCs and macrophages and consider the potential therapeutic utility of these interactions for the benefit of human health.

Therapeutic Effect of Renifolin F on Airway Allergy in an Ovalbumin-Induced Asthma Mouse Model In Vivo

Renifolin F is a prenylated chalcone isolated from Shuteria involucrata, a traditional minority ethnic medicine used to treat the respiratory diseases and asthma. Based on the effects of the original medicine plant, we established an in vivo mouse model of allergic asthma using ovalbumin (OVA) as an inducer to evaluate the therapeutic effects of Renifolin F. In the research, mice were sensitized and challenged with OVA to establish an allergic asthma model to evaluate the effects of Renifolin F on allergic asthma. The airway hyper-reactivity (AHR) to methacholine, cytokine levels, ILC2s quantity and mircoRNA-155 expression were assessed. We discovered that Renifolin F attenuated AHR and airway inflammation in the OVA-induced asthmatic mouse model by inhibiting the regulation of ILC2s in the lung, thereby, reducing the upstream inflammatory cytokines IL-25, IL-33 and TSLP; the downstream inflammatory cytokines IL-4, IL-5, IL-9 and IL-13 of ILC2s; and the co-stimulatory factors IL-2 and IL-7; as well as the expression of microRNA-155 in the lung. The findings suggest a therapeutic potential of Renifolin F on OVA-induced airway inflammation.

An Immunoregulatory Role of Interleukin-3 in Allergic Asthma

Background

Allergic asthma is a chronic airway inflammatory disease associated with airway mucus hyper-production. ILC2 cells, which express the Th2 transcription factor GATA3, have been associated with allergic asthma. The cytokine IL-3 is known to support eosinophil, basophil and mucosal mast cell differentiation and survival; however, its role on T regulatory cells as well as on lung ILC2 and in pediatric asthma needs further investigation.

Objectives

To investigate the role of IL-3 in preschool children and to explore its therapeutic role in experimental asthma.

Methods

In a cohort of preschool children with and without asthma, we analyzed the secretion of IL-3 in nasopharyngeal fluid (NPF) and IL-3 receptor (R) alpha chain mRNA expression in peripheral blood mononuclear cells (PBMCs). In a murine model of allergic asthma, we analyzed the phenotype of wild-type untreated and rIL-3 intranasally treated asthmatic mice.

Results

IL-3 was found downregulated in the nasopharyngeal fluid of children with partially controlled asthma, as compared to control children. Moreover, IL-3 was found induced in phytohemagglutinin (PHA)-stimulated PBMCs from children with asthma and treated with steroids. Finally, IL-3 in NPF directly correlated with the anti-inflammatory molecule sST2 in steroid-treated asthmatic children. Intranasal rIL-3 delivery in vivo during the challenge phase decreased airway mucus production and inflammatory eosinophils. Moreover, rIL-3 given during the challenge phase, reduced lung ST2^intGATA3+ILC2, accompanied by an induction of T regulatory cells in the airways.

Conclusions

IL-3 was found associated with steroid-resolved asthma. Moreover, treatment with rIL-3 resulted in amelioration of airway eosinophilia and mucus production, two main pathophysiological conditions associated with asthma in a murine model of allergic asthma. Thus, rIL-3 opens new strategies for immunotherapy of this disease.

Pathogenic changes in group 2 innate lymphoid cells (ILC2s) in a steroid-insensitive asthma model of mice

A certain population of asthma patients is resistant to steroid therapy, whereas the mechanisms remain unclear. One of characteristic features of steroid-resistant asthma patients is severe airway eosinophilia based on type-2 inflammation. Aims of this study were: 1) to develop a murine model of steroid-resistant asthma, 2) to elucidate that predominant cellular source of a type-2 cytokine, IL-5 was group 2 innate lymphoid cells (ILC2s), 3) to analyze pathogenic alteration of ILC2s in the severe asthma, and 4) to evaluate therapeutic potential of anti-IL-5 monoclonal antibody (mAb) on the steroid-resistant asthma. Ovalbumin (OVA)-sensitized BALB/c mice were intratracheally challenged with OVA at 5 or 500 μg/animal 4 times. Development of airway eosinophilia and remodeling in 5-μg OVA model were significantly suppressed by 1 mg/kg dexamethasone, whereas those in 500-μg OVA model were relatively insensitive to the dose of dexamethasone. ILC2s isolated from the lung of the steroid-insensitive model (500-μg OVA) produced significantly larger amounts of IL-5 in response to IL-33/TSLP than ILC2s from the steroid-sensitive model (5-μg OVA). Interestingly, TSLP receptor expression on ILC2s was up-regulated in the steroid-insensitive model. Treatment with anti-IL-5 mAb in combination with dexamethasone significantly suppressed the airway remodeling of the steroid-insensitive model. In conclusion, multiple intratracheal administration of a high dose of antigen induced steroid-insensitive asthma in sensitized mice. IL-5 was mainly produced from ILC2s, phenotype of which had been pathogenically altered probably through the up-regulation of TSLP receptors. IL-5 blockage could be a useful therapeutic strategy for steroid-resistant asthma.

ILC2s induce adaptive Th2-type immunity in different stages of tuberculosis through the Notch-GATA3 pathway

The study is to investigate the roles of group 2 innate lymphoid cells (ILC2s) in different courses of tuberculosis (TB). Serum and PBMCs were respectively isolated from the TST negative, LTBI (latent TB infection), ATB (active TB) and RTB (recurrent TB) patients. Flow cytometry was used to detect Th1, Th2 and ILC2s in the peripheral blood. The mRNA and protein levels of GATA3, RORα, CRTH2, Hes1, Notch1, NF-κB, and ID2 were detected by qRT-PCR and Western blotting. ILC2 cells from ATB and RTB patients were stimulated with rJagged2 or DAPT in vitro, and co-cultured with CD4⁺ T cells from TST negative group. ELISA was used to detect cytokine levels. The results showed that compared with the TST negative or LTBI group, Th2 cells and serum IL-4 in ATB group increased dramatically, accompanied by an increase of Th2/Th1 ratio in ATB patients, especially in RTB group. However, ILC2s in the ATB and RTB group increased significantly, along with increased GATA3, RORα, and CRTH2 levels. After rJagged2 stimulation in vitro, the levels of Hes1, Notch1, NF-κB, RORα, GATA3 and ID2 and those of IL-4, IL-5 and IL-13 were significantly increased. These effects were abrogated by DAPT treatment. Then, ILC2s, especially those from RTB patients, induced Th2-type immune response after co-culturing with CD4⁺ T cells. In conclusion, our results suggest that ILC2s may promote Th2-type immune response in different stages of TB via the Notch-GATA3 pathway.

Effect of parasympathetic inhibition on expression of ILC2 cells in a mouse model of allergic rhinitis

Background

We wanted to investigate whether parasympathetic inhibition affected the expression of type 2 innate lymphoid cells (ILC2s) in the nasal mucosa of a mouse model of allergic rhinitis (AR).

Methods

Thirty male C57BL/6 mice were randomly divided into 3 groups: control group, AR group, AR-treated group. AR nasal symptoms were assessed on a semi-quantitative scale according to the frequencies of nose rubbing and sneezing and the degree of rhinorrhea. The expression of cytokines protein in serum was detected by enzyme linked immunosorbent assay (ELISA). The number of ILC2s in nasal mucosa was detected by immunofluorescence double staining assay. Quantitative real-time Polymerase Chain Reaction (qPCR) was used to detect the expression of ILC2-associated factor in nasal mucosa.

Results

The symptom scores of the AR group were significantly higher than those of the control group and AR-treated group. The expression levels of mouse ovalbumin (OVA) specific IgE, IL4, IL5, and IL13 in the serum of AR group were significantly higher than those in the control group and AR-treated group. The number of ILC2s and the gene expression of ILC2s related factors GATA3, CD25 and CD90 (Thy1) in the nasal mucosa of the AR group were significantly higher than those of the control group and AR-treated group.

Conclusions

We found that parasympathetic inhibition relieved AR symptoms and inhibited immune response of AR mice. ILC2s play an important role in the occurrence and development of AR, and parasympathetic nerve inhibition reduced the number of ILC2s and inhibited the cytokines expression by ILC2s. Our data provide information on the mechanism of action of parasympathetic inhibition in AR.

Group 2 innate lymphoid cells promote TNBC lung metastasis via the IL-13-MDSC axis in a murine tumor model

Group 2 innate lymphoid cells (ILC2s) are reportedly associated with the progression of many tumors. However, the role of ILC2s in triple-negative breast cancer (TNBC) lung metastasis remains unclear. In this study, we found that ILC2s may be a key element in the process of TNBC lung metastasis since the adoptive transfer of pulmonary ILC2s increased the numbers of metastatic lung nodules and reduced the survival of tumor-bearing mice. ILC2-promoted 4 T1 lung metastasis appears to be related to ILC2-derived IL-13. An expansion of IL-13-producing ILC2s and an elevated expression of IL-13 mRNA in pulmonary ILC2s were determined in tumor-bearing mice, in parallel with an increase in the levels of local IL-13 by ILC2 transfer. The neutralization of IL-13 reduced the increased pulmonary metastatic nodules and improved the decreased survival rate caused by ILC2-adoptive transfer. Interestingly, adoptive transfer of ILC2s elevated IL-13Ra1 expression in myeloid-derived suppressor cells (MDSCs). Treatment of ILC2-transferred tumor-bearing mice with anti-IL-13 antibodies significantly diminished the number of pulmonary MDSCs and inhibited MDSC activation. Moreover, when pulmonary MDSCs were cocultured with ILC2s in the presence of an anti-IL-13 mAb, the number and activation of MDSCs were reduced. Depletion of MDSCs may promote the proliferation of CD4+ T cells and CD8+ T cells, but reduce the expansion of regulatory T cells (Tregs) in the lungs of ILC2-transferred tumor-bearing mice. Our results suggest that pulmonary ILC2s may promote TNBC lung metastasis via the ILC2-derived IL-13-activated MDSC pathway.

Roles of Clara cell 10-kD protein and type 2 innate lymphoid cells in allergic rhinitis

This study examined the potential roles of CC10 (Clara cell 10-kD protein) and ILC2s (type 2 innate lymphoid cells) in allergic rhinitis (AR). After ovalbumin was used to construct the AR model, microarray analysis was performed to reveal the key differentially expressed genes. The phenotypic changes of nasal mucosa were examined by H&E staining. Western blot analysis, qRT-PCR, ELISA and immunohistochemistry were performed to identify the levels of cytokines. The lineage markers (CD127 and CD117) of ILC2s were detected using immunofluorescence. The microarray analysis and qRT-PCR results showed that CC10 overexpression inhibited the expression of A20, BAFF, and IL-4 R in vivo. Also, CC10 overexpression was found to ameliorate the damage of nasal mucosa in AR mice. Investigations revealed that the ILC2s were activated in AR mice and AR patients with high levels of IgE, IgG1, IL-4, IL-5, IL-13, IL-25, and IL-33. Moreover, CD127+ was found to activate ILC2s. However, CC10 overexpression suppressed the activation of ILC2s. In conclusion, this research suggested that CC10 could suppress the activation of ILC2s to attenuate the damage of nasal mucosa and that CD127+ may be a biomarker of the activation of ILC2s in AR mice and AR patients.

Single-cell transcriptomic landscape reveals tumor specific innate lymphoid cells associated with colorectal cancer progression

Innate lymphoid cells (ILCs) are tissue-resident lymphocytes differing from conventional T lymphocytes in having no antigen-specific receptors. ILCs include natural killer (NK) cells, helper-like ILC1s, ILC2s, and ILC3s, and lymphoid tissue-inducer (LTi) cells. Tumor ILCs are frequently found in various cancers, but their roles in cancer immunity and immunotherapy remain largely unclear. We report here the single-cell characterization of blood and gut helper-like ILC subsets in healthy conditions and in colorectal cancer (CRC). The healthy gut contains ILC1s, ILC3s, and ILC3/NKs, but no ILC2s. Additional tumor-specific ILC1-like and ILC2 subsets were identified in CRC patients. Signaling lymphocytic activation molecule family member 1 (SLAMF1) was found to be selectively expressed on tumor-specific ILCs, and higher levels of SLAMF1⁺ ILCs were observed in the blood of CRC patients. The SLAMF1-high group of CRC patients had a significantly higher survival rate than the SLAMF1-low group, suggesting that SLAMF1 is an anti-tumor biomarker in CRC.

Healthy gut contains ILC1s, ILC3s, and ILC3/NKs, but no ILC2s

Blood and tumor ILCs from CRC patients have unique transcriptomic features

Tumor tissue from CRC patients contains a tumor specific ILC1-like subset and ILC2s

SLAMF1 is identified as an anti-tumor biomarker in CRC

Neuroimmune regulatory networks of the airway mucosa in allergic inflammatory disease

Communication between the nervous and immune systems serves a key role in host‐protective immunity at mucosal barrier sites including the respiratory tract. In these tissues, neuroimmune interactions operate in bidirectional circuits that can sense and respond to mechanical, chemical, and biologic stimuli. Allergen‐ or helminth‐induced products can produce airway inflammation by direct action on nociceptive afferents and adjacent tissues. The activity of nociceptive afferents can regulate innate and adaptive immune responses via neuropeptides and neurotransmitter signaling. This review will summarize recent work investigating the role of neuropeptides CGRP, VIP, neuromedins, substance P, and neurotransmitters dopamine and the B2‐adrenoceptor agonists epinepherine/norepinepherine, each of which influence type 2 immunity by instructing mast cell, innate lymphoid cell type 2, dendritic cell, and T cell responses, both in the airway and the draining lymph node. Afferents in the airway also contain receptors for alarmins and cytokines, allowing their activity to be modulated by immune cell secreted products, particularly those secreted by mast cells. Taken together, we propose that further investigation of how immunoregulatory neuropeptides shape respiratory inflammation in experimental systems may reveal novel therapeutic targets for addressing the increasing prevalence of chronic airway disease in humans.

Visceral adipose tissue mesenchymal stromal cells in the intersection of immunology and metabolism

Visceral adipose tissue (VAT) is now recognized as an endocrine organ that plays a key role in organismal homeostasis by integrating metabolic and immunological aspects. In healthy individuals, this fat depot participates in the storage and release of lipids as per physiological demand, while maintaining a local anti-inflammatory environment. In this regard, recent findings highlight the pivotal role of distinct subtypes of mesenchymal stromal cells (mSCs) as orchestrators of metabolic homeostasis by engendering adipocytes to sustain adequate lipid storage as well as immune regulators via cross-talk with specialized tissue-resident immunocytes, especially regulatory T cells (Tregs) and group 2 innate lymphoid cells (ILC2s) to prevent the development of local inflammation. In addition, these stromal-immunocyte interactions are influenced by a number of physiological conditions such as aging and sex hormones. Perturbation of VAT equilibrium occurring during obesity appreciably alters the distribution and phenotype of mSCs, immunocytes, and other cell types, thereby promoting the development of chronic, low-grade inflammation locally and systemically. These alterations impair metabolic signaling and substantially contribute to the onset of disease, including type 2 diabetes. The present mini-review discusses the latest advances in this area, with an emphasis on the newly uncovered heterogeneity of mSCs, how they communicate with Tregs and ILC2s under different physio-pathological circumstances and future challenges to face.

High chemokine ligand 11 levels in nasal lavage fluid: A potential predictor of and therapeutic target for murine eosinophilic chronic rhinosinusitis

AIM

We aimed to discover whether group 2 innate lymphoid cells (ILC2s) and cytokines in nasal lavage fluid could be used to predict eosinophilic infiltration in mice with eosinophilic chronic rhinosinusitis (ECRS).

METHODS

Ten mice were divided into two groups. The ECRS group received an intranasal challenge of Aspergillus oryzae protease (AP) and ovalbumin (OVA) to establish disease. A control group received intranasal phosphate-buffered saline. Histopathology of nasal cavities and paranasal sinuses, and cytokine and ILC2s levels in nasal lavage fluid were analyzed and compared between the ECRS and control mouse groups.

KEY FINDINGS

ILC2s numbers were not significantly higher in the nasal lavage fluid of the ECRS group mice compared with those of the control group. Eotaxin/chemokine (CC motif) ligand 11 (CCL11) levels were significantly higher in the nasal lavage fluid of mice in the ECRS group compared with those in the control group. However, no statistical differences were seen in the classic proinflammatory cytokines, IL-33, IL-25, and thymic stromal thymopoietin (TSLP), or the classic type 2 cytokines, IL-4, IL-5, and IL-13 between groups.

SIGNIFICANCE

Eotaxin/CCL11 levels in nasal lavage fluid rather than that of ILC2s and classic proinflammatory and type 2 cytokines were significantly higher in ECRS mice compared with control ones. Eotaxin/CCL11 showed diagnostic and therapeutic value; however, more studies are needed to test and verify its value.

Impact of a Demyelination-Inducing Central Nervous System Virus on Expression of Demyelination Genes in Type 2 Lymphoid Cells

We recently reported the role of type 2 innate lymphoid cells (ILC2s) in central nervous system (CNS) demyelination using a model of CNS demyelination involving recombinant herpes simplex virus 1 (HSV-1) that constitutively expresses mouse interleukin 2 (HSV-IL-2). In this investigation, we studied how ILC2s respond to HSV-IL-2 at the cellular level using cytokine and gene expression profiling. ILC2s infected with HSV-IL-2 expressed higher levels of granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-5, IL-6, IL-13, IP-10, MIP-2, and RANTES, which include proinflammatory cytokines, than did those infected with parental control virus. In contrast, T_H2 cytokines IL-4 and IL-9, which are typically expressed by ILC2s, were not induced upon HSV-IL-2 infection. Transcriptome sequencing (RNA-seq) analysis of HSV-IL-2 infected ILC2s showed significant upregulation of over 350 genes and downregulation of 157 genes compared with parental virus-infected ILC2s. Gene Ontology (GO) term analysis indicated that genes related to "mitosis" and "inflammatory response" were among the upregulated genes, suggesting that HSV-IL-2 infection drives the excessive proliferation and atypical inflammatory response of ILC2s. This change in ILC2 activation state could underlie the pathology of demyelinating diseases.IMPORTANCE Innate lymphocytes have plasticity and can change functionality; type 2 innate lymphoid cells (ILC2s) can convert to ILC1 or ILC3 cells or change their activation state to produce IL-17 or IL-10 depending on environmental cues. In this study, we investigated the gene and cytokine profiles of ILC2s, which play a major role in HSV-IL-2-induced CNS demyelination. ILC2s infected with HSV-IL-2 displayed a massive remodeling of cellular state. Additionally, ILC2s infected with HSV-IL-2 differed from those infected with parental HSV in cellular and viral gene expression profiles and in cytokine/chemokine induction, and they displayed enhanced activation and proinflammatory responses. These changes in ILC2 activation state could underlie the pathology of demyelinating diseases. These results also highlight the possible importance of pathogens as environmental cues to modify innate lymphocyte functionalities.

ILC2-derived IL-9 inhibits colorectal cancer progression by activating CD8+ T cells

Group 2 innate lymphoid cells (ILC2s), characterized by secretion of type 2 cytokines, regulate multiple immune responses. ILC2s are found in different tumor tissues, and ILC2-derived interleukin (IL)-4, IL-5, and IL-13 act on the cells in tumor microenvironment to participate in tumor progression. ILC2s are abundant in colorectal cancer (CRC) tissue, but the role of ILC2s in CRC remains unclear. In this study, we found that the percentage of ILC2s was higher in CRC tissue than in the adjacent normal tissue and that these ILC2s were the dominant IL-9-secreting cell-subsets in CRC tissue, as shown by flow cytometry analysis. ILC2s-derived IL-9 could activate CD8⁺ T cells to inhibit tumor growth, while anti-IL-9 reversed this effect. In vivo experiments showed that neutralizing ILC2s promoted tumor growth, while tumor inhibition occurred by intravenous injection of IL-9. In conclusion, our results demonstrated that ILC2-derived IL-9 could activate CD8⁺ T cells to promote anti-tumor effects in CRC.

Localization and site-specific cell-cell interactions of group 2 innate lymphoid cells

Group 2 innate lymphoid cells (ILC2s) are novel lymphocytes discovered in 2010. Unlike T or B cells, ILC2s are activated non-specifically by environmental factors and produce various cytokines, thus playing a role in tissue homeostasis, diseases including allergic diseases, and parasite elimination. ILC2s were first reported as cells abundantly present in fat-associated lymphoid clusters in adipose tissue. However, subsequent studies revealed their presence in various tissues throughout the body, acting as key players in tissue-specific diseases. Recent histologic analyses revealed that ILC2s are concentrated in specific regions in tissues, such as the lamina propria and perivascular regions, with their function being controlled by the surrounding cells, such as epithelial cells and other immune cells, via cytokine and lipid production or by cell–cell interactions through surface molecules. Especially, some stromal cells have been identified as the niche cells for ILC2s, both in the steady state and under inflammatory conditions, through the production of IL-33 or extracellular matrix factors. Additionally, peripheral neurons reportedly co-localize with ILC2s and alter their function directly through neurotransmitters. These findings suggest that the different localizations or different cell–cell interactions might affect the function of ILC2s. Furthermore, generally, ILC2s are thought to be tissue-resident cells; however, they occasionally migrate to other tissues and perform a new role; this supports the importance of the microenvironment for their function. We summarize here the current understanding of how the microenvironment controls ILC2 localization and function with the aim of promoting the development of novel diagnostic and therapeutic methods.

MicroRNA-375-mediated regulation of ILC2 cells through TSLP in allergic rhinitis

Background

Studies have shown that the number and function of type II innate lymphoid cells (ILC2) in peripheral blood of allergic rhinitis (AR) children increased significantly. This study aims to evaluate the role of miR-375 in the regulation of the differentiation and function of ILC2 through both in vivo and in vitro studies.

Methods

The expression of miR-375, thymic stromal lymphopoietin (TSLP) and the frequency of ILC2 were detected and compared between AR children and controls by real-time polymerase chain reaction (PCR), enzyme-linked immunosorbnent assay (ELISA) and flow cytometry, respectively. The miR-375 mimics or inhibitors were transfected into human nasal epithelial cells (HNECs), and the production of TSLP was detected by ELISA. HNECs and ILC2s were co-cultured to explore the role of miR-375 on ILC2s. AR mice models were established to prove the effect of miR-375 on ILC2s in vivo.

Results

The expression of TSLP, miR-375, and the frequency of ILC2 were significantly higher in AR compared with controls. We found that the TSLP expression by HNECs were significantly higher when transfected with miR-375 mimics than in those transfected with miR-control and miR-375 inhibitor. In the coculture system, HNECs transfected with miR-375 mimics promote the type II cytokines production by ILC2, and this effect was blocked by anti-TSLP. Our results also showed that the miR-375 inhibitors attenuate allergic symptoms and production of type II cytokines in AR mice.

Conclusions

Our findings suggest that miR-375-mediated regulation of ILC2 cells through TSLP, providing new potential treatment target for AR.

Type 2 innate lymphoid cells regulation by regulatory T cells attenuates atherosclerosis

Regulatory T cells (Tregs) have been shown to attenuate the development and progression of atherosclerosis; however, the exact mechanism is still unclear. In our study, Tregs were adoptively transferred into ApoE^-/- mice, and type 2 innate lymphoid cells (ILC2s) were expanded by the IL-2/Jes6-1 complex or depleted by anti-CD90.2 mAb in ApoE^-/-Rag1^-/- mice to study their effects on atherosclerosis. Then, Tregs were cocultured with ILC2s in vitro to analyze ILC2s number and IL-13 production. In vivo, ApoE^-/-Rag1^-/- mice were treated with activated Tregs with or without anti-CD90.2 mAb to explore whether Tregs reduced atherosclerosis through ILC2s. Finally, neutralizing antibodies and Transwell assay were used to investigate how Tregs regulate ILC2s. Our results show that both Tregs and ILC2s reduce atherosclerosis lesions and macrophage infiltration. Moreover, Tregs effectively expanded the number of ILC2s and increased their production of IL-13 in vivo and in vitro. Furthermore, the reductions in plaque size and macrophage infiltration by Tregs were partly reversed by anti-CD90.2 mAb. Mechanistically, our data reveal that IL-10, TGF-β and cell-cell contacts are required for Tregs-ILC2s regulation. These results show that Tregs may play a partial protective role against atherosclerosis by expanding the number of ILC2s and consequently increasing IL-13 production.

Anti-inflammatory mechanisms of the novel cytokine interleukin-38 in allergic asthma

We elucidated the anti-inflammatory mechanisms of IL-38 in allergic asthma. Human bronchial epithelial cells and eosinophils were cocultured upon stimulation with the viral RLR ligand poly (I:C)/LyoVec or infection-related cytokine TNF-α to induce expression of cytokines/chemokines/adhesion molecules. House dust mite (HDM)-induced allergic asthma and humanized allergic asthma NOD/SCID murine models were established to assess anti-inflammatory mechanisms in vivo. IL-38 significantly inhibited induced proinflammatory IL-6, IL-1β, CCL5, and CXCL10 production, and antiviral interferon-β and intercellular adhesion molecule-1 expression in the coculture system. Mass cytometry and RNA-sequencing analysis revealed that IL-38 could antagonize the activation of the intracellular STAT1, STAT3, p38 MAPK, ERK1/2, and NF-κB pathways, and upregulate the expression of the host defense-related gene POU2AF1 and anti-allergic response gene RGS13. Intraperitoneal injection of IL-38 into HDM-induced allergic asthma mice could ameliorate airway hyperreactivity by decreasing the accumulation of eosinophils in the lungs and inhibiting the expression of the Th2-related cytokines IL-4, IL-5, and IL-13 in the bronchoalveolar lavage fluid (BALF) and lung homogenates. Histological examination indicated lung inflammation was alleviated by reductions in cell infiltration and goblet cell hyperplasia, together with reduced Th2, Th17, and innate lymphoid type 2 cell numbers but increased proportions of regulatory T cells in the lungs, spleen, and lymph nodes. IL-38 administration suppressed airway hyperreactivity and asthma-related IL-4 and IL-5 expression in humanized mice, together with significantly decreased CCR3+ eosinophil numbers in the BALF and lungs, and a reduced percentage of human CD4+CRTH2+ Th2 cells in the lungs and mediastinal lymph nodes. Together, our results demonstrated the anti-inflammatory mechanisms of IL-38 and provided a basis for the development of a regulatory cytokine-based treatment for allergic asthma.

Unique Phenotypes of Heart Resident Type 2 Innate Lymphoid Cells

Innate lymphoid cells (ILCs), including ILC1s, ILC2s, and ILC3s, play critical roles in regulating immunity, inflammation, and tissue homeostasis. However, limited attention is focused on the unique phenotype of ILCs in the heart tissue. In this study, we analyzed the ILC subsets in the heart by flow cytometry and found that ILC2s were the dominant population of ILCs, while a lower proportion of type 1 ILCs (including ILC1 and NK cells) and merely no ILC3s in the heart tissue of mice. Our results show that ILC2 development kinetically peaked in heart ILC2s at the age of 4 weeks after birth and later than lung ILC2s. By conducting parabiosis experiment, we show that heart ILC2s are tissue resident cells and minimally replaced by circulating cells. Notably, heart ILC2s have unique phenotypes, such as lower expression of ICOS, CD25 (IL-2Rα), and Ki-67, higher expression of Sca-1 and GATA3, and stronger ability to produce IL-4 and IL-13. In doxorubicin-induced myocardial necroptosis model of mouse heart tissue, IL-33 mRNA expression level and ILC2s were remarkably increased. In addition, IL-4 production by heart ILC2s, but not lung ILC2s, was also dramatically increased after doxorubicin treatment. Our results demonstrate that heart-resident ILC2s showed tissue-specific phenotypes and rapidly responded to heart injury. Thus, further studies are warranted to explore the potential for IL-33-elicited ILC2s response as therapeutics for attenuating heart damage.

Regulating the development of pulmonary Group 2 innate lymphoid cells

Group 2 innate lymphoid cells (ILC2s) are members of the family of innate lymphoid cells and are innately committed to type 2 immune responses. In the lungs, ILC2s are the predominant population of innate lymphoid cells (ILCs) and their development is orchestrated by several different transcription factors ensuring lineage commitment by intrinsic regulation. ILC2s are present in the lungs from the foetal period onwards and are thus exposed to extrinsic regulation due to the airways' continuous morphological changes upon birth. In this review, we will briefly summarise the dependence of ILC2s on transcription factors and discuss recently described characteristics and function of early life ILC2s in the lungs.

Bacteria-Induced Group 2 Innate Lymphoid Cells in the Stomach Provide Immune Protection through Induction of IgA

The intestinal microbiota shapes and directs immune development locally and systemically, but little is known about whether commensal microbes in the stomach can impact their immunological microenvironment. Here, we report that group 2 innate lymphoid cells (ILC2s) were the predominant ILC subset in the stomach and show that their homeostasis and effector functions were regulated by local commensal communities. Microbes elicited interleukin-7 (IL-7) and IL-33 production in the stomach, which in turn triggered the propagation and activation of ILC2. Stomach ILC2s were also rapidly induced following infection with Helicobacter pylori. ILC2-derived IL-5 resulted in the production of IgA, which coated stomach bacteria in both specific pathogen-free (SPF) and H. pylori-infected mice. Our study thus identifies ILC2-dependent IgA response that is regulated by the commensal microbiota, which is implicated in stomach protection by eliminating IgA-coated bacteria including pathogenic H. pylori.

Topical Application of the Quaternary Ammonium Compound Didecyldimethylammonium Chloride Activates Type 2 Innate Lymphoid Cells and Initiates a Mixed-Type Allergic Response

Didecyldimethylammonium chloride (DDAC) is an antimicrobial dialkyl-quaternary ammonium compound used in industrial and commercial products. Clinical data suggest that DDAC exposure elicits multiple types of hypersensitivity reactions; here, we confirm this observation in a BALB/c murine model. To examine the immunological mechanism behind this mixed-type response and the potential involvement of type 2 innate lymphoid cells (ILC2s), we assessed early immune responses in the skin following topical DDAC exposure (0.125% and 0.5%). DDAC exposure resulted in a rapid and dramatic increase in the Th2-skewing and ILC2-activating cytokine thymic stromal lymphopoietin. Correspondingly, dermal ILC2s were activated 24 h after DDAC exposure, resulting in increased expression of CD25, ICOS and KLRG1, and decreased CD127 throughout 7 days of exposure. Following ILC2 activation, the Th2 cytokine IL-4 was elevated compared with control mice in total ear protein lysate (0.5% DDAC). Rag2-/- mice were used to determine a functional role for ILC2s in DDAC-induced sensitization. ILC2s from Rag2-/- mice were similarly activated by DDAC and, importantly, produced significant levels of IL-4 and IL-5 in the skin (0.5% DDAC). These data indicate that ILC2s contribute to early Th2 immune responses following DDAC exposure. ILC2s have been previously implicated in allergic responses, but to our knowledge have not been thoroughly investigated in chemical sensitization. These results indicate that following DDAC exposure, skin ILC2s become activated and produce Th2 cytokines, providing a possible mechanism for the development of the mixed-type allergic responses commonly observed with chemical sensitizers.

Interleukin-33 Induces the Enzyme Tryptophan Hydroxylase 1 to Promote Inflammatory Group 2 Innate Lymphoid Cell-Mediated Immunity

Group 2 innate lymphoid cells (ILC2s) regulate immunity, inflammation, and tissue homeostasis. Two distinct subsets of ILC2s have been described: steady-state natural ILC2s and inflammatory ILC2s, which are elicited following helminth infection. However, how tissue-specific cues regulate these two subsets of ILC2s and their effector functions remains elusive. Here, we report that interleukin-33 (IL-33) promotes the generation of inflammatory ILC2s (ILC2^INFLAM) via induction of the enzyme tryptophan hydroxylase 1 (Tph1). Tph1 expression was upregulated in ILC2s upon activation with IL-33 or following helminth infection in an IL-33-dependent manner. Conditional deletion of Tph1 in lymphocytes resulted in selective impairment of ILC2^INFLAM responses and increased susceptibility to helminth infection. Further, RNA sequencing analysis revealed altered gene expression in Tph1 deficient ILC2s including inducible T cell co-stimulator (Icos). Collectively, these data reveal a previously unrecognized function for IL-33, Tph1, and ICOS in promoting inflammatory ILC2 responses and type 2 immunity at mucosal barriers.

HMGB1-induced ILC2s activate dendritic cells by producing IL-9 in asthmatic mouse model

Asthma is a disease of the respiratory system that is commonly considered a T-helper 2 (Th2) cell-associated inflammatory disease. Group 2 innate lymphoid cells (ILC2s) promote the inflammatory responses in asthma by secreting type 2 cytokines. Interleukin (IL)-9 also serves as a promoting factor in asthma and it is well known that ILC2s have an autocrine effect of IL-9 to sustain their survival and proliferation. However, the specific role of ILC2-derived IL-9 in asthma remains unclear. HMGB1 (High-Mobility Group Box-1) is a nuclear protein, and Previous studies have shown that HMGB1 can regulate the differentiation of T-helper cells and participate in the development of asthma. But whether HMGB1 can regulate the innate lymphocytes in the pathological process of asthma is unknown. In this study we have shown increased presence of HMGB1 protein in the lung of mice with asthma, which was associated with increased secretion of IL-9 by ILC2s. This led to the activation of dendritic cells (DCs) that can accelerate the differentiation of Th2 cells and worsen the severity of asthma. Taken together, our study provides a complementary understanding of the asthma development and highlights a novel inflammatory pathway in the pathogenesis of asthma.

The Involvement of Type 2 Innate Lymphoid Cells in Airway Inflammation of Asthma

The airway inflammatory response is closely associated with asthma. The purpose of this article was to study the roles of innate lymphoid cells (ILCs) in the process of airway inflammatory response in asthma. We established the asthmatic mice model with intraperitoneal injected ovalbumin medium, then with the flow cytometry analysis, we detected the ILCs and their surface proteins in the mice blood samples, besides, we analyzed the amounts of inflammatory cytokines and secreted proteins in the mice bronchoalveolar lavage fluid and blood serum. Moreover, Western blot analyzed the proteins in the mice bronchial epithelial tissues. The ILC2 amounts were obviously increased in young asthmatic mice model. And, the proteins CD25 and CCR10 were highly expressed in the sorted ILC2s. Besides, the cytokines interleukin (IL)-5, IL-13, IL-33, CCL22, and CCL27 were abundant in the bronchoalveolar lavage fluid of asthmatic mice model. And, the secretion of IL-5, IL-13, IL-33, TSLP, and CCL22 in blood serum was much more in asthmatic mice model than in the normal control mice, whereas the secretion of PGD2 was suppressed in asthmatic mice bronchoalveolar lavage fluid and blood serum. Additionally, the guanine nucleotide-binding proteins Gα12 and Gα13 were upregulated in asthmatic mice bronchial tissues, and the protein SERCA2 was downregulated; moreover, the proteins NFAT, IRF4, and its downstream signal STAT6 were all upregulated in the asthmatic mice bronchial tissues. ILC2s were involved in the response of airway inflammation through secretion of proinflammatory cytokines and chemokines to dysregulate the Ca²⁺ homeostasis in airway in the process of asthma. [Figure: see text].

Isolation, Culture, and Induction of Plasticity in ILC2s

Innate lymphoid cells (ILCs) are lymphocytes with critical roles in homeostasis, inflammation, and immunity to pathogens. ILCs are rare relative to other immune cell populations and are primarily defined by lack of expression of markers associated with other immune cell lineages and are predominantly found in mucosal tissues like the gut, lung and skin. They are classified into distinct subsets, ILC1, ILC2, and ILC3, which mirror subsets of CD4⁺ helper T cells. ILC subsets have distinct cytokine and transcription factor profiles which align with their biological functions, although recently it has emerged that ILC subsets are not phenotypically fixed and exhibit considerable heterogeneity and plasticity in different contexts. Here, we describe protocols for the maintenance, expansion, and induction of plasticity in mouse and human ILC2s. The resulting cells can be used for molecular interrogation of ILC function and biology, both in vivo and in vitro.