The Therapeutic Potential for Targeting Group 2 Innate Lymphoid Cells in Asthma

Stage-specific GATA3 induction promotes ILC2 development after lineage commitment

Group 2 innate lymphoid cells (ILC2s) are a subset of innate lymphocytes that produce type 2 cytokines, including IL-4, IL-5, and IL-13. GATA3 is a critical transcription factor for ILC2 development at multiple stages. However, when and how GATA3 is induced to the levels required for ILC2 development remains unclear. Herein, we identify ILC2-specific GATA3-related tandem super-enhancers (G3SE) that induce high GATA3 in ILC2-committed precursors. G3SE-deficient mice exhibit ILC2 deficiency in the bone marrow, lung, liver, and small intestine with minimal impact on other ILC lineages or Th2 cells. Single-cell RNA-sequencing and subsequent flow cytometry analysis show that GATA3 induction mechanism, which is required for entering the ILC2 stage, is lost in IL-17RB+PD-1- late ILC2-committed precursor stage in G3SE-deficient mice. Cnot6l, part of the CCR4-NOT deadenylase complex, is a possible GATA3 target during ILC2 development. Our findings implicate a stage-specific regulatory mechanism for GATA3 expression during ILC2 development.

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.

Myeloid-derived suppressor cells in influenza virus-induced asthma exacerbation

Myeloid-derived suppressor cells (MDSCs) are a phenotypically heterogenous group of cells that potently suppress the immune response. A growing body of evidence supports the important role of MDSCs in a variety of lung diseases, such as asthma. However, the role of MDSCs in asthma exacerbation has so far not been investigated. Here, we studied the role of MDSCs in a murine model of influenza virus-induced asthma exacerbation. BALB/c mice were exposed to house dust mite (HDM) three times a week for a total of five weeks to induce a chronic asthmatic phenotype, which was exacerbated by additional exposure to the A/Hamburg/5/2009 hemagglutinin 1 neuraminidase 1 (H1N1) influenza virus. Induction of lung inflammatory features, production of T helper (Th) 1- and Th2- associated inflammatory cytokines in the lavage fluid and an increased airway hyper-responsiveness were observed, establishing the asthma exacerbation model. The number and activity of pulmonary M-MDSCs increased in exacerbated asthmatic mice compared to non-exacerbated asthmatic mice. Furthermore, depletion of MDSCs aggravated airway hyper-responsiveness in exacerbated asthmatic mice. These findings further denote the role of MDSCs in asthma and provide some of the first evidence supporting a potential important role of MDSCs in asthma exacerbation.

Neuroimmune interplay during type 2 inflammation: Symptoms, mechanisms, and therapeutic targets in atopic diseases

Type 2 inflammation is characterized by overexpression and heightened activity of type 2 cytokines, mediators, and cells that drive neuroimmune activation and sensitization to previously subthreshold stimuli. The consequences of altered neuroimmune activity differ by tissue type and disease; they include skin inflammation, sensitization to pruritogens, and itch amplification in atopic dermatitis and prurigo nodularis; airway inflammation and/or hyperresponsiveness, loss of expiratory volume, airflow obstruction and increased mucus production in asthma; loss of sense of smell in chronic rhinosinusitis with nasal polyps; and dysphagia in eosinophilic esophagitis. We describe the neuroimmune interactions that underlie the various sensory and autonomic pathologies in type 2 inflammatory diseases and present recent advances in targeted treatment approaches to reduce type 2 inflammation and its associated symptoms in these diseases. Further research is needed to better understand the neuroimmune mechanisms that underlie chronic, sustained inflammation and its related sensory pathologies in diseases associated with type 2 inflammation.

Effects of biological therapies on patients with Type-2 high asthma and comorbid obesity

Over 20 million adults and 6 million children in the United States (US) have asthma, a chronic respiratory disease characterized by airway inflammation, bronchoconstriction, and mucus hypersecretion. Obesity, another highly prevalent disease in the US, is a major risk factor for asthma and a significant cause of diminished asthma control, increased submucosal eosinophilia, and reduced quality of life. A large subgroup of these patients experiences severe symptoms and recurrent exacerbations despite maximal dosage of standard asthma therapies. In the past two decades, the development of biological therapies has revolutionized the field and advanced our understanding of type 2 inflammatory biomarkers. However, patients with obesity and comorbid asthma are not principally considered in clinical trials of biologics. Large landmark cluster analyses of patients with asthma have consistently identified specific asthma phenotypes that associate with obesity but may be differentiated by age of asthma onset and inflammatory cell profiles in sputum. These patterns suggest that biologic processes driving asthma pathology are heterogenous among patients with obesity. The biological mechanisms driving pathology in patients with asthma and comorbid obesity are not well understood and likely multifactorial. Future research needs to be done to elicit the cellular and metabolic functions in the relationship of obesity and asthma to yield the best treatment options for this multiplex condition. In this review, we explore the key features of type 2 inflammation in asthma and discuss the effectiveness, safety profile, and research gaps regarding the currently approved biological therapies in asthma patients with obesity.

Crocin Inhibits the Type 2 Inflammatory Response Produced by ILC2s in Eosinophilic Nasal Polyps

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is subdivided into type 1 and type 2 inflammatory responses according to the mucosal inflammatory patterns. Crocin can reduce the level of T-helper type 2 cell (Th2) cytokines, such as interleukin-4 (IL-4), and inhibit the nuclear factor kappa-B (NF-κB) signaling pathway.

OBJECTIVE

This study aimed to investigate the role of group 2 innate lymphoid cells (ILC2s) in type 2 inflammation in eosinophilic nasal polyps and the inhibitory effect of crocin on this inflammation.

METHODS

Immunohistochemistry and immunofluorescence were used to detect the expression of transcription factors and the infiltration of ILC2s in tissues. An ILC2 stimulation model in vitro was constructed based on IL-33 stimulation and treated with crocin. The explant models were constructed and treated with crocin to detect the expression of type 2 inflammation-related factors.

RESULTS

Significantly more GATA-binding protein-3 (GATA3)-positive cells and chemoattractant receptor-homologous molecule expressed on T-helper type 2 cell (CRTH2)-positive cells, but fewer T-box expressed in T cell (T-bet)-positive cells, were found in eosinophilic nasal polyps (NPwEos). The expression levels of GATA3 and CRTH2 were significantly higher in NPwEos. Recombinant IL-33 stimulation increased the expression of GATA3, CRTH2, and type 2 cytokines (IL-4, IL-5, and IL-13) in ILC2s. In an IL-33-stimulated in vitro ILC2 culture model, crocin inhibited the type 2 inflammatory response, especially at lower concentrations (10 µM). The explant organoids of NPwEos were constructed in vitro, and Staphylococcus aureus enterotoxin B (SEB) was used to construct the type 2 inflammation model. Crocin at 10 µM concentration inhibited type 2 inflammation induced by SEB-stimulated explants.

CONCLUSION

Crocin inhibited type 2 inflammation induced by ILC2 activation at low concentrations via inhibiting the activation of NF-κB.

Versatile roles of innate lymphoid cells at the mucosal barrier: from homeostasis to pathological inflammation

Innate lymphoid cells (ILCs) are innate lymphocytes that do not express antigen-specific receptors and largely reside and self-renew in mucosal tissues. ILCs can be categorized into three groups (ILC1-3) based on the transcription factors that direct their functions and the cytokines they produce. Their signature transcription factors and cytokines closely mirror those of their Th1, Th2, and Th17 cell counterparts. Accumulating studies show that ILCs are involved in not only the pathogenesis of mucosal tissue diseases, especially respiratory diseases, and colitis, but also the resolution of such diseases. Here, we discuss recent advances regarding our understanding of the biology of ILCs in mucosal tissue health and disease. In addition, we describe the current research on the immune checkpoints by which other cells regulate ILC activities: for example, checkpoint molecules are potential new targets for therapies that aim to control ILCs in mucosal diseases. In addition, we review approved and clinically- trialed drugs and drugs in clinical trials that can target ILCs and therefore have therapeutic potential in ILC-mediated diseases. Finally, since ILCs also play important roles in mucosal tissue homeostasis, we explore the hitherto sparse research on cell therapy with regulatory ILCs. This review highlights various therapeutic approaches that could be used to treat ILC-mediated mucosal diseases and areas of research that could benefit from further investigation.

Long-term mepolizumab treatment reduces relapse rates in super-responders with eosinophilic granulomatosis with polyangiitis

BACKGROUND

The mainstay of treatment for eosinophilic granulomatosis with polyangiitis (EGPA) is systemic corticosteroid therapy; some patients also receive intravenous immunoglobulins, other immunosuppressive agents, and biologics. Mepolizumab, an anti-interleukin-5 monoclonal antibody, induces remission and decreases the daily corticosteroid dose; however, the clinical efficacy of mepolizumab in EGPA and the prognosis with long-term treatment with this drug are unknown.

METHODS

Seventy-one EGPA patients were treated at Hiratsuka City Hospital, Japan, between April 2018 and March 2022. We administered mepolizumab for a mean of 2.8 ± 1.7 years to 43 patients in whom remission could not be induced by conventional treatment. After excluding 18 patients who had received mepolizumab for less than 3 years, we classified 15 patients into a "super-responder group" (the daily dose of corticosteroids or other immunosuppressant could be decreased, or the interval between IVIG treatments could be prolonged) and 10 patients into a "responder group" (neither of these changes was achievable). Eosinophil numbers, serum IgG levels, daily doses of corticosteroids and other immunosuppressants, Birmingham Vasculitis Activity Score (BVAS), and relapse frequency before and after mepolizumab initiation were determined.

RESULTS

Blood eosinophil count at diagnosis and the lowest serum IgG level before mepolizumab treatment were significantly higher in super-responders than in responders (p < 0.05). In super-responders, the prednisolone dose at last visit on mepolizumab treatment was lower than that before treatment (p < 0.01) and lower than that at last visit in the responders (p < 0.01). In both groups, peripheral blood eosinophil numbers and BVAS were lower after starting mepolizumab than before (p < 0.01). BVAS before mepolizumab (p < 0.05) and at last visit (p < 0.01) were lower in super-responders than in responders. Relapse rates every year after the start of mepolizumab were lower in super-responders than in responder groups (p < 0.01). In super-responders, relapse rates were lower during the 3 years following mepolizumab initiation (p < 0.01) and at last visit (p < 0.01) were significantly lower than after 1 year of treatment.

CONCLUSION

Mepolizumab treatment of super-responders sustainably reduced the relapse rate.

Severe Asthmatic Responses: The Impact of TSLP

Asthma is a chronic inflammatory disease that affects the lower respiratory system and includes several categories of patients with varying features or phenotypes. Patients with severe asthma (SA) represent a group of asthmatics that are poorly responsive to medium-to-high doses of inhaled corticosteroids and additional controllers, thus leading in some cases to life-threatening disease exacerbations. To elaborate on SA heterogeneity, the concept of asthma endotypes has been developed, with the latter being characterized as T2-high or low, depending on the type of inflammation implicated in disease pathogenesis. As SA patients exhibit curtailed responses to standard-of-care treatment, biologic therapies are prescribed as adjunctive treatments. To date, several biologics that target specific downstream effector molecules involved in disease pathophysiology have displayed superior efficacy only in patients with T2-high, eosinophilic inflammation, suggesting that upstream mediators of the inflammatory cascade could constitute an attractive therapeutic approach for difficult-to-treat asthma. One such appealing therapeutic target is thymic stromal lymphopoietin (TSLP), an epithelial-derived cytokine with critical functions in allergic diseases, including asthma. Numerous studies in both humans and mice have provided major insights pertinent to the role of TSLP in the initiation and propagation of asthmatic responses. Undoubtedly, the magnitude of TSLP in asthma pathogenesis is highlighted by the fact that the FDA recently approved tezepelumab (Tezspire), a human monoclonal antibody that targets TSLP, for SA treatment. Nevertheless, further research focusing on the biology and mode of function of TSLP in SA will considerably advance disease management.

Biologics for eosinophilic granulomatosis with polyangiitis

PURPOSE OF REVIEW

The link between severe asthma and eosinophilic granulomatosis with polyangiitis (EGPA) in terms of pathophysiological background, clinical manifestations and disease evolution has leaded to investigate the relevance of anti T2 monoclonal antibodies licensed for severe asthma patients as a treatment option for EGPA. The present review aimed to provide un update on EGPA pathophysiology and to critically summarize the most robust evidence coming from trials and real-life setting on the use of anti T2 biologics in EGPA patients.

RECENT FINDINGS

Mepolizumab, an anti-interleukin-5 monoclonal antibody, is the only biologic drug targeting eosinophilic inflammation currently approved for EGPA treatment at the dose of 300 mg/4 weeks. Its use is restricted by the American College of Rheumatology guidelines to specific diseases phases and severity grades. However the most appropriate mepolizumab positioning and dose is still under investigation in the real life practice, which is providing an increasing amount of evidence confirming its efficacy, alone or in combination with other options in different disease stages. The relevance of other monoclonal antibodies interfering with T2 inflammation, including omalizumab and benralizumab, is under investigation but the evidence is still scarce.

SUMMARY

Taking into account the suboptimal medium-long term safety profile of conventional EGPA treatments, the opportunity of selectively targeting eosinophilic inflammation certainly represents a revolutionary approach. However, further real-word evidence is required to effectively position the new treatments in the light of the disease complexity, including different immunological drivers, and individual variability.

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.