IL-4Rα expression by airway epithelium and smooth muscle accounts for nearly all airway hyperresponsiveness in murine allergic airway disease

Development of a novel humanized anti-TSLP monoclonal antibody, QX008N, and exploration of combination therapy of anti-TSLP antibody and anti-IL-4R antibody

BACKGROUND

Severe asthma is a complex and chronic respiratory disease, and current conventional treatments are not effective in controlling the patients' condition. Thymic stromal lymphopoietin (TSLP) is a key regulatory factor in the initiation and maintenance of asthma. Thus, blocking TSLP during allergic inflammation emerges as a promising therapeutic approach; however, novel anti-TSLP therapies remain to be developed. Furthermore, the importance of other signaling molecules, such as IL-4 and IL-13, should be considered. Moreover, to the best of our knowledge, the inhibitory effect of binding upstream and downstream signaling molecules has not been assessed.

PURPOSE

This study aimed to develop a novel, humanized anti-TSLP antibody and explore the enhancement in its efficacy when combined with anti-IL-4R antibodies to treat asthma.

RESULTS

QX008N, derived from a rabbit antibody platform, exhibits a high affinity for TSLP and superior efficacy in blocking TSLP-induced signaling pathways and inflammation in vitro compared with Tezepelumab. In a cynomolgus monkey asthma model, QX008N ameliorated lung function and reduced the levels of eosinophils and IgE. Moreover, the coadministration of QX008N with anti-IL-4R antibodies enhanced the inhibition of inflammatory mediator production triggered via costimulation in vitro. In mouse asthma models, the simultaneous blockade of TSLP and IL-4R using anti-TL4R and anti-TSLP surrogates surpassed the efficacy of monotherapy. To the best of our knowledge, the therapeutic effect of a combination of anti-TSLP and IL-4R antibodies in an asthma model has not yet been reported.

CONCLUSION

These results furnish comprehensive preclinical evidence for QX008N as an innovative anti-TSLP therapeutic agent and provide a preliminary rationale for the development of combination therapies that simultaneously target the TSLP and IL-4R signaling pathways.

STAT6-induced production of mucus and resistin-like molecules in lung Club cells does not protect against helminth or influenza A virus infection

Airway epithelial cells contribute to a variety of lung diseases including allergic asthma, where IL-4 and IL-13 promote activation of the transcription factor STAT6. This leads to goblet cell hyperplasia and the secretion of effector molecules by epithelial cells. However, the specific effect of activated STAT6 in lung epithelial cells is only partially understood. Here, we created a mouse strain to selectively investigate the role of constitutively active STAT6 in Club cells, a subpopulation of airway epithelial cells. CCSP-Cre_STAT6vt mice and bronchiolar organoids derived from these show an enhanced expression of the chitinase-like protein Chil4 (Ym2) and resistin-like molecules (Relm-α, -β, -γ). In addition, goblet cells of these mice spontaneously secrete mucus into the bronchi. However, the activated epithelium resulted neither in impaired lung function nor conferred a protective effect against the migrating helminth Nippostrongylus brasiliensis. Moreover, CCSP-Cre_STAT6vt mice showed similar allergic airway inflammation induced by live conidia of the fungus Aspergillus fumigatus and similar recovery after influenza A virus infection compared to control mice. Together these results highlight that STAT6 signaling in Club cells induces the secretion of Relm proteins and mucus without impairing lung function, but this is not sufficient to confer protection against helminth or viral infections.

Interleukin 31 receptor α promotes smooth muscle cell contraction and airway hyperresponsiveness in asthma

Asthma is a chronic inflammatory airway disease characterized by airway hyperresponsiveness (AHR), inflammation, and goblet cell hyperplasia. Multiple cytokines, including IFNγ, IL-4, and IL-13 are associated with asthma; however, the mechanisms underlying the effects of these cytokines remain unclear. Here, we report a significant increase in the expression of IL-31RA, but not its cognate ligand IL-31, in mouse models of allergic asthma. In support of this, IFNγ, IL-4, and IL-13 upregulated IL-31RA but not IL-31 in both human and mice primary airway smooth muscle cells (ASMC) isolated from the airways of murine and human lungs. Importantly, the loss of IL-31RA attenuated AHR but had no effect on inflammation and goblet cell hyperplasia in mice challenged with allergens or treated with IL-13 or IFNγ. We show that IL-31RA functions as a positive regulator of muscarinic acetylcholine receptor 3 expression, augmenting calcium levels and myosin light chain phosphorylation in human and murine ASMC. These findings identify a role for IL-31RA in AHR that is distinct from airway inflammation and goblet cell hyperplasia in asthma.

Delayed Microbial Maturation Durably Exacerbates Th17-driven Asthma in Mice

Microbial maturation disrupted by early-life dysbiosis has been linked with increased asthma risk and severity; however, the immunological mechanisms underpinning this connection are poorly understood. We sought to understand how delaying microbial maturation drives worsened asthma outcomes later in life and its long-term durability. Drinking water was supplemented with antibiotics on Postnatal Days 10-20. To assess the immediate and long-term effects of delaying microbial maturation on experimental asthma, we initiated house dust mite exposure when bacterial diversity was either at a minimum or had recovered. Airway hyperresponsiveness, histology, pulmonary leukocyte recruitment, flow cytometric analysis of cytokine-producing lymphocytes, and assessment of serum IgG1 (Immunoglobulin G1) and IgE (Immunoglobulin E) concentrations were performed. RT-PCR was used to measure IL-13 (Interleukin 13)-induced gene expression in sequentially sorted mesenchymal, epithelial, endothelial, and leukocyte cell populations from the lung. Delayed microbial maturation increased allergen-driven airway hyperresponsiveness and Th17 frequency compared with allergen-exposed control mice, even when allergen exposure began after bacterial diversity recovered. Blockade of IL-17A (Interleukin 17A) reversed the airway hyperresponsiveness phenotype. In addition, allergen exposure in animals that experienced delayed microbial maturation showed signs of synergistic signaling between IL-13 and IL-17A in the pulmonary mesenchymal compartment. Delaying microbial maturation in neonates promotes the development of more severe asthma by increasing Th17 frequency, even if allergen exposure is initiated weeks after microbial diversity is normalized. In addition, IL-17A-aggravated asthma is associated with increased expression of IL-13-induced genes in mesenchymal, but not epithelial cells.

Lymphotoxin beta receptor signaling directly controls airway smooth muscle deregulation and asthmatic lung dysfunction

BACKGROUND

Dysregulation of airway smooth muscle cells (ASM) is central to the severity of asthma. Which molecules dominantly control ASM in asthma is unclear. High levels of the cytokine LIGHT (aka TNFSF14) have been linked to asthma severity and lower baseline predicted FEV1 percentage, implying that signals through its receptors might directly control ASM dysfunction.

OBJECTIVE

Our study sought to determine whether signaling via lymphotoxin beta receptor (LTβR) or herpesvirus entry mediator from LIGHT dominantly drives ASM hyperreactivity induced by allergen.

METHODS

Conditional knockout mice deficient for LTβR or herpesvirus entry mediator in smooth muscle cells were used to determine their role in ASM deregulation and airway hyperresponsiveness (AHR) in vivo. Human ASM were used to study signals induced by LTβR.

RESULTS

LTβR was strongly expressed in ASM from normal and asthmatic subjects compared to several other receptors implicated in smooth muscle deregulation. Correspondingly, conditional deletion of LTβR only in smooth muscle cells in smMHCCreLTβRfl/fl mice minimized changes in their numbers and mass as well as AHR induced by house dust mite allergen in a model of severe asthma. Intratracheal LIGHT administration independently induced ASM hypertrophy and AHR in vivo dependent on direct LTβR signals to ASM. LIGHT promoted contractility, hypertrophy, and hyperplasia of human ASM in vitro. Distinguishing LTβR from the receptors for IL-13, TNF, and IL-17, which have also been implicated in smooth muscle dysregulation, LIGHT promoted NF-κB-inducing kinase-dependent noncanonical nuclear factor kappa-light-chain enhancer of activated B cells in ASM in vitro, leading to sustained accumulation of F-actin, phosphorylation of myosin light chain kinase, and contractile activity.

CONCLUSIONS

LTβR signals directly and dominantly drive airway smooth muscle hyperresponsiveness relevant for pathogenesis of airway remodeling in severe asthma.

Interleukin 31 receptor alpha augments muscarinic acetylcholine receptor 3-driven calcium signaling and airway hyperresponsiveness in asthma

Asthma is a chronic inflammatory airway disease characterized by airway hyperresponsiveness (AHR), inflammation, and goblet cell hyperplasia. Both Th1 and Th2 cytokines, including IFN-γ, IL-4, and IL-13 have been shown to induce asthma; however, the underlying mechanisms remain unclear. We observed a significant increase in the expression of IL-31RA, but not its cognate ligand IL-31 during allergic asthma. In support of this, IFN-γ and Th2 cytokines, IL-4 and IL-13, upregulated IL-31RA but not IL-31 in airway smooth muscle cells (ASMC). Importantly, the loss of IL-31RA attenuated AHR but had no effects on inflammation and goblet cell hyperplasia in allergic asthma or mice treated with IL-13 or IFN-γ. Mechanistically, we demonstrate that IL-31RA functions as a positive regulator of muscarinic acetylcholine receptor 3 expression and calcium signaling in ASMC. Together, these results identified a novel role for IL-31RA in AHR distinct from airway inflammation and goblet cell hyperplasia in asthma.

Cysteinyl-maresin 3 inhibits IL-13 induced airway hyperresponsiveness through alternative activation of the CysLT1 receptor

BACKGROUND

Cysteinyl-maresins, also known as maresin-conjugates in tissue regeneration (MCTRs), are recently discovered lipid mediators proposed to reduce airway inflammation.

OBJECTIVE

To investigate the influence of MCTRs on IL-13-induced airway hyperresponsiveness in isolated human and mice airways.

METHODS

Before responsiveness to contractile agonists were assessed in myographs, human small bronchi were cultured for 2 days and mouse tracheas were cultured for 1-4 days. During the culture procedure airways were exposed to interleukin (IL)-13 in the presence or absence of MCTRs. Signalling mechanisms were explored using pharmacologic agonists and antagonists, and genetically modified mice.

RESULTS

IL-13 treatment increased contractions to histamine, carbachol and leukotriene D₄ (LTD₄) in human small bronchi, and to 5-hydroxytryptamine (5-HT) in mouse trachea. In both preparations, co-incubation of the explanted tissues with MCTR3 reduced the IL-13 induced enhancement of contractions. In mouse trachea, this inhibitory effect of MCTR3 was blocked by three different CysLT₁ receptor antagonists (montelukast, zafirlukast and pobilukast) during IL-13 exposure. Likewise, MCTR3 failed to reduce the IL-13-induced 5-HT responsiveness in mice deficient of the CysLT₁ receptor. However, co-incubation with the classical CysLT₁ receptor agonist LTD₄ did not alter the IL-13-induced 5-HT hyperreactivity.

CONCLUSIONS

MCTR3, but not LTD₄, decreased the IL-13-induced airway hyperresponsiveness by activation of the CysLT₁ receptor. The distinct actions of the two lipid mediators on the CysLT₁ receptor suggest an alternative signalling pathway appearing under inflammatory conditions, where this new action of MCTR3 implicates potential to inhibit airway hyperresponsiveness in asthma.

IL-13 Regulates Orai1 Expression in Human Bronchial Smooth Muscle Cells and Airway Remodeling in Asthma Mice Model via LncRNA H19

Background

Increased proliferation and hypertrophy of airway smooth muscle cells (ASMCs) contribute substantially to airway remodeling in asthma. Interleukin (IL)-13 regulates ASMC proliferation by increasing Orai1 expression, the pore-forming subunit of store-operated Ca²⁺ entry (SOCE). The underlying mechanisms of this effect are not fully understood.

Methods

Bioinformatic analysis identified an interaction between microRNA 93-5p (miR-93-5p) and long non-coding RNA (lncRNA) H19, and between miR-93-5p and Orai1. RNA interference was used to investigate H19 knockdown on IL-13-induced proliferation and migration of in vitro cultured human bronchial smooth muscle cells (hBSMCs). Functional relevance of H19 in airway inflammation and airway remodeling was investigated in murine models of acute and chronic asthma.

Results

IL-13 concentration-dependently increased the expression of H19 and Orai1 and decreased the expression of miR-93-5p in hBSMCs. H19 knockdown partly reversed the effects of IL-13 on the expression of miR-93-5p and Orai1 and attenuated the proliferation and migration of hBSMCs promoted by IL-13. IL-13-promoted expression of Orai1 was attenuated by miR-93-5p mimic and increased by miR-93-5p inhibitor. IL-13-promoted proliferation of hBSMCs was increased by miR-93-5p inhibitor but not affected by miR-93-5p mimic, whereas IL-13-promoted migration of hBSMCs was increased by miR-93-5p inhibitor and attenuated by miR-93-5p mimic. The inhibiting effect of H19 knockdown on IL-13-induced Orai1 expression and the proliferation and migration of hBSMCs was counteracted by miR-93-5p inhibitor but only marginally or not impacted by miR-93-5p mimic. The expression of H19 and Orai1 was higher in the lungs of asthmatic mice than in control mice. In asthmatic mice, H19 siRNA reduced Orai1 expression, inflammatory cell infiltration, goblet cell hyperplasia, collagen deposition and smooth muscle mass in the lungs.

Conclusion

H19 may mediate the effects of IL-13 on Orai1 expression by inhibition of miR-93-5p in hBSMCs. H19 may be a therapeutic target for airway inflammation and airway remodeling.

Modulation of IL-4/IL-13 cytokine signaling in the context of allergic disease

Aberrant activation of CD4 T_H2 cells and excessive production of T_H2 cytokines such as IL-4 and IL-13 have been implicated in the pathogenesis of allergic diseases. Generally, IL-4 and IL-13 utilize Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathways for induction of inflammatory gene expression and the effector functions associated with disease pathology in many allergic diseases. However, it is increasingly clear that JAK/STAT pathways activated by IL-4/IL-13 can themselves be modulated in the presence of other intracellular signaling programs, thereby changing the overall tone and/or magnitude of IL-4/IL-13 signaling. Apart from direct activation of the canonic JAK/STAT pathways, IL-4 and IL-13 also induce proinflammatory gene expression and effector functions through activation of additional signaling cascades. These alternative signaling cascades contribute to several specific aspects of IL-4/IL-13-associated cellular and molecular responses. A more complete understanding of IL-4/IL-13 signaling pathways, including the precise conditions under which noncanonic signaling pathways are activated, and the impact of these pathways on cellular- and host-level responses, will better allow us to design agents that target specific pathologic outcomes or tailor therapies for the treatment of uncommon disease endotypes.

Finding a Niche: Tissue Immunity and Innate Lymphoid Cells

The immune system plays essential roles in maintaining homeostasis in mammalian tissues that extend beyond pathogen clearance and host defense. Recently, several homeostatic circuits comprised of paired hematopoietic and non-hematopoietic cells have been described to influence tissue composition and turnover in development and after perturbation. Crucial circuit components include innate lymphoid cells (ILCs), which seed developing organs and shape their resident tissues by influencing progenitor fate decisions, microbial interactions, and neuronal activity. As they develop in tissues, ILCs undergo transcriptional imprinting that encodes receptivity to corresponding signals derived from their resident tissues but ILCs can also shift their transcriptional profiles to adapt to specific types of tissue perturbation. Thus, ILC functions are embedded within their resident tissues, where they constitute key regulators of homeostatic responses that can lead to both beneficial and pathogenic outcomes. Here, we examine the interactions between ILCs and various non-hematopoietic tissue cells, and discuss how specific ILC-tissue cell circuits form essential elements of tissue immunity.

Cellular mechanism underlying the facilitation of contractile response induced by IL-25 in mouse tracheal smooth muscle

Asthma is a common heterogeneous respiratory disease characterized by airway inflammation and airway hyperresponsiveness (AHR) which is associated with abnormality in smooth muscle contractility. The epithelial cell-derived cytokine IL-25 is implicated in type 2 immune pathology including asthma, whereas the underlying mechanisms have not been fully elucidated. This study aims to investigate the effects of IL-25 on mouse tracheal smooth muscle contractility and elucidate the cellular mechanisms. Incubation with IL-25 augmented the contraction of mouse tracheal smooth muscles, which could be suppressed by the L-type voltage-dependent Ca²⁺ channel (L-VDCC) blocker nifedipine. Furthermore, IL-25 enhanced the cytosolic Ca²⁺ signals and triggered up-regulation of α1C L-VDCC (Ca_V1.2) in primary cultured mouse tracheal smooth muscle cells. Knocking down IL-17RA/IL-17RB receptors or inhibiting the transforming growth factor-β-activated kinase 1 (TAK1)-tumor progression locus 2 (TPL2)-MAPK kinase 1/2 (MEK1/2)-ERK1/2-activating protein-1 (AP-1) signaling pathways suppressed the IL-25-elicited up-regulation of Ca_V1.2 and hyperreactivity in tracheal smooth muscles. Moreover, inhibition of TPL2, ERK1/2 or L-VDCC alleviated the AHR symptom induced by IL-25 in a murine model. This study revealed that IL-25 potentiated the contraction of tracheal smooth muscle and evoked AHR via activation of TPL2-ERK1/2-Ca_V1.2 signaling, providing novel targets for the treatment of asthma with a high-IL-25 phenotype.

JAK inhibitors for asthma

Asthma is an inflammatory disease of the airways characterized by intermittent episodes of wheezing, chest tightness, and cough. Many of the inflammatory pathways implicated in asthma involve cytokines and growth factors that activate Janus kinases (JAKs). The discovery of the JAK/signal transducer and activator of transcription (STAT) signaling pathway was a major breakthrough that revolutionized our understanding of cell growth and differentiation. JAK inhibitors are under active investigation for immune and inflammatory diseases, and they have demonstrated clinical efficacy in diseases such as rheumatoid arthritis and atopic dermatitis. Substantial preclinical data support the idea that inhibiting JAKs will ameliorate airway inflammation and hyperreactivity in asthma. Here, we review the rationale for use of JAK inhibitors in different asthma endotypes as well as the preclinical and early clinical evidence supporting such use. We review preclinical data from the use of systemic and inhaled JAK inhibitors in animal models of asthma and safety data based on the use of JAK inhibitors in other diseases. We conclude that JAK inhibitors have the potential to usher in a new era of anti-inflammatory treatment for asthma.

Smooth Muscle Hypocontractility and Airway Normoresponsiveness in a Mouse Model of Pulmonary Allergic Inflammation

The contractility of airway smooth muscle (ASM) is labile. Although this feature can greatly modulate the degree of airway responsiveness in vivo, the extent by which ASM's contractility is affected by pulmonary allergic inflammation has never been compared between strains of mice exhibiting a different susceptibility to develop airway hyperresponsiveness (AHR). Herein, female C57BL/6 and BALB/c mice were treated intranasally with either saline or house dust mite (HDM) once daily for 10 consecutive days to induce pulmonary allergic inflammation. The doses of HDM were twice greater in the less susceptible C57BL/6 strain. All outcomes, including ASM contractility, were measured 24 h after the last HDM exposure. As expected, while BALB/c mice exposed to HDM became hyperresponsive to a nebulized challenge with methacholine in vivo, C57BL/6 mice remained normoresponsive. The lack of AHR in C57BL/6 mice occurred despite exhibiting more than twice as much inflammation than BALB/c mice in bronchoalveolar lavages, as well as similar degrees of inflammatory cell infiltrates within the lung tissue, goblet cell hyperplasia and thickening of the epithelium. There was no enlargement of ASM caused by HDM exposure in either strain. Unexpectedly, however, excised tracheas derived from C57BL/6 mice exposed to HDM demonstrated a decreased contractility in response to both methacholine and potassium chloride, while tracheas from BALB/c mice remained normocontractile following HDM exposure. These results suggest that the lack of AHR in C57BL/6 mice, at least in an acute model of HDM-induced pulmonary allergic inflammation, is due to an acquired ASM hypocontractility.

Airway Remodeling in Asthma

Asthma is an inflammatory disease of the airways that may result from exposure to allergens or other environmental irritants, resulting in bronchoconstriction, wheezing, and shortness of breath. The structural changes of the airways associated with asthma, broadly referred to as airway remodeling, is a pathological feature of chronic asthma that contributes to the clinical manifestations of the disease. Airway remodeling in asthma constitutes cellular and extracellular matrix changes in the large and small airways, epithelial cell apoptosis, airway smooth muscle cell proliferation, and fibroblast activation. These pathological changes in the airway are orchestrated by crosstalk of different cell types within the airway wall and submucosa. Environmental exposures to dust, chemicals, and cigarette smoke can initiate the cascade of pro-inflammatory responses that trigger airway remodeling through paracrine signaling and mechanostimulatory cues that drive airway remodeling. In this review, we explore three integrated and dynamic processes in airway remodeling: (1) initiation by epithelial cells; (2) amplification by immune cells; and (3) mesenchymal effector functions. Furthermore, we explore the role of inflammaging in the dysregulated and persistent inflammatory response that perpetuates airway remodeling in elderly asthmatics.