Interleukin-13 augments bronchial smooth muscle contractility with an up-regulation of RhoA protein

Clara cell 10 (CC10) protein attenuates allergic airway inflammation by modulating lung dendritic cell functions

Allergic asthma is a complex inflammatory disorder predominantly orchestrated by T helper 2 (Th2) lymphocytes. The anti-inflammatory protein Clara Cell 10-kDa (CC10), also known as secretoglobin family 1A member 1 (SCGB1A1), shows promise in modulating respiratory diseases. However, its precise role in asthma remains unclear. This study examines the potential of CC10 to suppress allergic asthma inflammation, specifically assessing its regulatory effects on Th2 cell responses and dendritic cells (DCs). Lower CC10 levels in asthma were observed and correlated with increased IgE and lymphocytes. Cc10-/- mice exhibited exacerbated allergic airway inflammation marked by increased inflammatory cell infiltration, Th2 cytokines, serum antigen-specific IgE levels, and airway hyperresponsiveness (AHR) in house dust mite (HDM)-induced models. Conversely, recombinant CC10 significantly attenuated these inflammatory responses. Intriguingly, CC10 did not directly inhibit Th cell activation but significantly downregulated the population of CD11b+CD103- DCs subsets in lungs of asthmatic mice and modulated the immune activation functions of DCs through NF-κB signaling pathway. The mixed lymphocyte response assay revealed that DCs mediated the suppressive effect of CC10 on Th2 cell responses. Collectively, CC10 profoundly mitigates Th2-type allergic inflammation in asthma by modulating lung DC phenotype and functions, highlighting its therapeutic potential for inflammatory airway conditions and other related immunological disorders.

Extracellular acidification attenuates bronchial contraction via an autocrine activation of EP2 receptor: Its diminishment in murine experimental asthma

PURPOSE

Extracellular acidification is a major component of tissue inflammation, including airway inflammation in asthmatics. However, its physiological/pathophysiological significance in bronchial function is not fully understood. Currently, the functional role of extracellular acidification on bronchial contraction was explored.

METHODS

Left main bronchi were isolated from male BALB/c mice. Epithelium-removed tissues were exposed to acidic pH under submaximal contraction induced by 10-5 M acetylcholine in the presence or absence of a COX inhibitor indomethacin (10-6 M). Effects of AH6809 (10-6 M, an EP2 receptor antagonist), BW A868C (10-7 M, a DP receptor antagonist) and CAY10441 (3×10-6 M, an IP receptor antagonist) on the acidification-induced change in tension were determined. The release of prostaglandin E2 (PGE2) from epithelium-denuded tissues in response to acidic pH was assessed using an ELISA.

RESULTS

In the bronchi stimulated with acetylcholine, change in the extracellular pH from 7.4 to 6.8 caused a transient augmentation of contraction followed by a sustained relaxing response. The latter inhibitory response was abolished by indomethacin and AH6809 but not by BW A868C or CAY10441. Both indomethacin and AH6809 significantly increased potency and efficacy of acetylcholine at pH 6.8. Stimulation with low pH caused an increase in PGE2 release from epithelium-denuded bronchi. Interestingly, the acidic pH-induced bronchial relaxation was significantly reduced in a murine asthma model that had a bronchial hyperresponsiveness to acetylcholine.

CONCLUSION

Taken together, extracellular acidification could inhibit the bronchial contraction via autocrine activation of EP2 receptors. The diminished acidic pH-mediated inhibition of bronchial tone may contribute to excessive bronchoconstriction in inflamed airways such as asthma.

IL-13 and IL-17A Activate β1 Integrin through an NF-kB/Rho kinase/PIP5K1γ pathway to Enhance Force Transmission in Airway Smooth Muscle

Integrin activation resulting in enhanced adhesion to the extracellular matrix plays a key role in fundamental cellular processes. Although G-protein coupled receptor-mediated integrin activation has been extensively studied in non-adherent migratory cells such as leukocytes and platelets, much less is known about the regulation and functional impact of integrin activation in adherent stationary cells such as airway smooth muscle. Here we show that two different asthmagenic cytokines, IL-13 and IL-17A, activate type I and IL-17 cytokine receptor families respectively, to enhance adhesion of muscle to the matrix. These cytokines also induce activation of β1 integrins as detected by the conformation-specific antibody HUTS-4. Moreover, HUTS-4 binding is significantly increased in the smooth muscle of patients with asthma compared to healthy controls, suggesting a disease-relevant role for aberrant integrin activation. Indeed, we find integrin activation induced by a β1 activating antibody, the divalent cation manganese, or the synthetic peptide β1-CHAMP, dramatically enhances force transmission in collagen gels, mouse tracheal rings, and human bronchial rings even in the absence of cytokines. We further demonstrate that cytokine-induced activation of β1 integrins is regulated by a common pathway of NF-κB-mediated induction of RhoA and its effector Rho kinase, which in turn stimulates PIP5K1γ-mediated synthesis of PIP2 resulting in β1 integrin activation. Taken together, these data identify a previously unknown pathway by which type I and IL-17 cytokine receptor family stimulation induces functionally relevant β1 integrin activation in adherent smooth muscle and help explain the exaggerated force transmission that characterizes chronic airways diseases such as asthma.

German cockroach extract prevents IL-13-induced CCL26 expression in airway epithelial cells through IL-13 degradation

Inhaled aeroallergens can directly activate airway epithelial cells (AECs). Exposure to cockroach allergens is a strong risk factor for asthma. Cockroach allergens mediate some of their effects through their serine protease activity; protease activity is also a major contributor to allergenicity. The Th2 cytokine interleukin-13 (IL-13) induces upregulation of the eosinophil chemotactic factor CCL26. CCL26 induces eosinophil migration in allergic inflammation. In this work, we studied the effect of cockroach proteases on IL-13-induced effects. Immersed cultures of the human bronchial epithelial cell line BEAS-2B and air-liquid interface (ALI) cultures of primary normal human bronchial epithelial (NHBE) cells were stimulated with IL-13, Blattella Germanica cockroach extract (CE), or both. IL-13-induced genes were analyzed with qRT-PCR. IL-13 induced upregulation of CCL26, periostin, and IL-13Rα2 in bronchial epithelial cells which were decreased by CE. CE was heat-inactivated (HICE) or pre-incubated with protease inhibitors. HICE and CE preincubated with serine protease inhibitors did not prevent IL-13-induced CCL26 upregulation. CE-degraded IL-13 and specific cleavage sites were identified. CE also decreased IL-4-induced CCL26 upregulation and degraded IL-4. Other serine proteases such as bovine trypsin and house dust mite (HDM) serine proteases did not have the same effects on IL-13-induced CCL26. We conclude that CE serine proteases antagonize IL-13-induced effects in AECs, and this CE effect is mediated primarily through proteolytic cleavage of IL-13. IL-13 cleavage by cockroach serine proteases may modulate CCL26-mediated effects in allergic airway inflammation by interfering directly with the pro-inflammatory effects of IL-13 in vivo.

Rho-Kinase Inhibition of Active Force and Passive Tension in Airway Smooth Muscle: A Strategy for Treating Airway Hyperresponsiveness in Asthma

Rho-kinase inhibitors have been identified as a class of potential drugs for treating asthma because of their ability to reduce airway inflammation and active force in airway smooth muscle (ASM). Past research has revealed that, besides the effect on the ASM's force generation, rho-kinase (ROCK) also regulates actin filament formation and filament network architecture and integrity, thus affecting ASM's cytoskeletal stiffness. The present review is not a comprehensive examination of the roles played by ROCK in regulating ASM function but is specifically focused on passive tension, which is partially determined by the cytoskeletal stiffness of ASM. Understanding the molecular basis for maintaining active force and passive tension in ASM by ROCK will allow us to determine the suitability of ROCK inhibitors and its downstream enzymes as a class of drugs in treating airway hyperresponsiveness seen in asthma. Because clinical trials using ROCK inhibitors in the treatment of asthma have yet to be conducted, the present review focuses on the in vitro effects of ROCK inhibitors on ASM's mechanical properties which include active force generation, relaxation, and passive stiffness. The review provides justification for future clinical trials in the treatment of asthma using ROCK inhibitors alone and in combination with other pharmacological and mechanical interventions.

Human germline gain-of-function in STAT6: from severe allergic disease to lymphoma and beyond

Signal transducer and activator of transcription (STAT)-6 is a transcription factor central to pro-allergic immune responses, although the function of human STAT6 at the whole-organism level has long remained unknown. Germline heterozygous gain-of-function (GOF) rare variants in STAT6 have been recently recognized to cause a broad and severe clinical phenotype of early-onset, multi-system allergic disease. Here, we provide an overview of the clinical presentation of STAT6-GOF disease, discussing how dysregulation of the STAT6 pathway causes severe allergic disease, and identifying possible targeted treatment approaches. Finally, we explore the mechanistic overlap between STAT6-GOF disease and other monogenic atopic disorders, and how this group of inborn errors of immunity (IEIs) powerfully inform our fundamental understanding of common human allergic disease.

Altered renin-angiotensin system gene expression in airways of antigen-challenged mice: ACE2 downregulation and unexpected increase in angiotensin 1-7

OBJECTIVE

Evidence suggest that the renin-angiotensin system (RAS) is activated in people with asthma, although its pathophysiological role is unclear. Angiotensin-converting enzyme 2 (ACE2) is the major enzyme that converts angiotensin II to angiotensin 1-7 (Ang-1-7), and is also known as a receptor of SARS-CoV-2. The current study was conducted to identify the change in RAS-related gene expression in airways of a murine asthma model.

METHODS

The ovalbumin (OA)-sensitized mice were repeatedly challenged with aerosolized OA to induce asthmatic reaction. Twenty-four hours after the last antigen challenge, the main bronchial smooth muscle (BSM) tissues were isolated.

RESULTS

The KEGG pathway analysis of differentially expressed genes in our published microarray data revealed a significant change in the RAS pathway in the antigen-challenged mice. Quantitative RT-PCR analyses showed significant increases in the angiotensin II-generating enzymes (Klk1, Klk1b3 and Klk1b8) and a significant decrease in Ace2. Surprisingly, ELISA analyses revealed a significant increase in Ang-1-7 levels in bronchoalveolar lavage (BAL) fluids of the antigen-challenged animals, while no significant change in angiotensin II was observed. Application of Ang-1-7 to the isolated BSMs had no effect on their isometrical tension.

CONCLUSION

The expression of Ace2 was downregulated in the BSMs of OA-challenged mice, while Klk1, Klk1b3 and Klk1b8 were upregulated. Despite the downregulation of ACE2, the level of its enzymatic product, Ang-1-7, was increased in the inflamed airways, suggesting the existence of an unknown ACE2-independent pathway for Ang-1-7 production. The functional role of Ang-1-7 in the airways remains unclear.

Air Pollution and microRNAs: The Role of Association in Airway Inflammation

Air pollution exposure plays a key role in the alteration of gene expression profiles, which can be regulated by microRNAs, inducing the development of various diseases. Moreover, there is also evidence of sensitivity of miRNAs to environmental factors, including tobacco smoke. Various diseases are related to specific microRNA signatures, suggesting their potential role in pathophysiological processes; considering their association with environmental pollutants, they could become novel biomarkers of exposure. Therefore, the aim of the present work is to analyse data reported in the literature on the role of environmental stressors on microRNA alterations and, in particular, to identify specific alterations that might be related to the development of airway diseases so as to propose future preventive, diagnostic, and therapeutic strategies.

Fenofibrate Attenuates Asthma Features in an Ovalbumin-induced Mouse Model Via Suppressing NF-κB Binding Activity

BACKGROUND/AIM

Asthma is a chronic inflammatory disease of the airways with a high prevalence. Asthma has a complex pathophysiology and about 5-10% of patients are not fully responsive to the currently available treatments. The aim of this study is to investigate the involvement of NF-κB in the effects of fenofibrate on a mouse model of allergic asthma.

MATERIALS AND METHODS

A total of 49 BALB/c mice were randomly distributed into 7 groups (n=7). Allergic asthma model was created by administering i.p. injections of ovalbumin on days 0, 14 and 21, followed by provocation with inhaled ovalbumin on days 28, 29 and 30. Fenofibrate was orally given in 3 different doses; 1, 10 and 30mg/kg through days 21 to 30 of the experiment. On day 31, pulmonary function test using whole body plethysmography was performed. The mice were sacrificed 24hours later. Blood samples were obtained, and serum of each sample was separated for IgE determination. Bronchoalveolar lavage fluid (BALF) and lung tissues were collected to measure IL-5 and IL-13 levels. Nuclear extracts of lung tissues were employed to assess nuclear factor kappa B (NF-κB) p65 binding activity.

RESULTS

Enhanced Pause (Penh) values were significantly increased in ovalbumin-sensitized and challenged mice (p<0.01). Administration of fenofibrate (10 and 30mg/kg) resulted in improved pulmonary function as shown by significantly lower Penh values (p<0.01). Interleukin (IL) -5 and IL-13 levels in BALF and lung tissues and immunoglobulin E (IgE) levels in serum were significantly elevated in the allergic mice. IL-5 levels in the lung tissues of mice treated with 1mg/kg fenofibrate (FEN1) group were significantly reduced (p<0.01). BALF and lung tissue IL-5 and IL-13 levels in mice treated with 10 and 30mg/kg fenofibrate, FEN10 and FEN30, respectively, were significantly diminished when compared to the ovalbumin-treated (OVA) group, whereas treatment with 1mg/kg fenofibrate resulted in insignificant changes. IgE levels in the serum of FEN30 group mice have shown a prominent reduction (p<0.01). NF-κB p65 binding activity was higher in mice sensitized and challenged with ovalbumin (p<0.01). NF-κB p65 binding activity was significantly reduced in allergic mice treated with 30mg/kg (p<0.01) fenofibrate.

CONCLUSIONS

In this study, we showed that administration of 10 and 30mg/kg fenofibrate effectively attenuated airway hyperresponsiveness and inflammation in a mouse model of allergic asthma, possibly through inhibition of NF-κB binding activity.

The Functional Role of Group 2 Innate Lymphoid Cells in Asthma

Asthma is a heterogeneous disease characterized by chronic airway inflammation. Group 2 innate lymphoid cells (ILC2) play an important role in the pathogenesis of asthma. ILC2s lack antigen-specific receptors and respond to epithelial-derived cytokines, leading to the induction of airway eosinophilic inflammation in an antigen-independent manner. Additionally, ILC2s might be involved in the mechanism of steroid resistance. Numerous studies in both mice and humans have shown that ILC2s induce airway inflammation through inflammatory signals, including cytokines and other mediators derived from immune or non-immune cells. ILC2s and T helper type 2 (Th2) cells collaborate through direct and indirect interactions to organize type 2 immune responses. Interestingly, the frequencies or numbers of ILC2 are increased in the blood and bronchoalveolar lavage fluid of asthma patients, and the numbers of ILC2s in the blood and sputum of severe asthmatics are significantly larger than those of mild asthmatics. These findings may contribute to the regulation of the immune response in asthma. This review article highlights our current understanding of the functional role of ILC2s in asthma.

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.

A lncRNA MALAT1 is a positive regulator of RhoA protein expression in bronchial smooth muscle cells

AIMS

Augmented smooth muscle contractility of the airways associated with an increased expression of RhoA, a monomeric GTPase responsible for Ca²⁺ sensitization of contraction, is one of the causes of airway hyperresponsiveness. However, the mechanism of the altered properties of airway smooth muscle cells, including the RhoA upregulation, is not fully understood. This study aims to define functional role of a long non-coding RNA MALAT1 in the RhoA expression and development of bronchial smooth muscle (BSM) hyper-contractility.

MAIN METHODS

Cultured human BSM cells were transfected with MALAT1 antisense oligonucleotide (AS), miR-133a-3p mimic, and/or inhibitor, and then stimulated with interleukin-13 (IL-13). In animal experiments, the ovalbumin (OA)-sensitized mice were repeatedly challenged with aerosolized OA to induce asthmatic reaction.

KEY FINDINGS

Treatment of the cells with IL-13 induced an increase in RhoA protein. Either MALAT1 AS or miR-133a-3p mimic transfection inhibited the IL-13-induced upregulation of RhoA. The inhibitory effect of MALAT1 AS was abolished by co-transfection with miR-133a-3p inhibitor. In BSMs of the murine asthma model, upregulations of Malat1 and RhoA protein were observed concomitantly with downregulation of miR-133a-3p.

SIGNIFICANCE

These findings suggest that MALAT1 positively regulates RhoA protein expression by inhibiting miR-133a-3p in BSM cells, and that its upregulation causes the RhoA upregulation, resulting in an augmented BSM contractility.

The Role of Staphylococcus aureus and Its Toxins in the Pathogenesis of Allergic Asthma

Bronchial asthma is one of the most common chronic diseases worldwide and affects more than 300 million patients. Allergic asthma affects the majority of asthmatic children as well as approximately 50% of adult asthmatics. It is characterized by a Th2-mediated immune response against aeroallergens. Many aspects of the overall pathophysiology are known, while the underlying mechanisms and predisposing factors remain largely elusive today. Over the last decade, respiratory colonization with Staphylococcus aureus (S. aureus), a Gram-positive facultative bacterial pathogen, came into focus as a risk factor for the development of atopic respiratory diseases. More than 30% of the world’s population is constantly colonized with S. aureus in their nasopharynx. This colonization is mostly asymptomatic, but in immunocompromised patients, it can lead to serious complications including pneumonia, sepsis, or even death. S. aureus is known for its ability to produce a wide range of proteins including toxins, serine-protease-like proteins, and protein A. In this review, we provide an overview of the current knowledge about the pathophysiology of allergic asthma and to what extent it can be affected by different toxins produced by S. aureus. Intensifying this knowledge might lead to new preventive strategies for atopic respiratory diseases.

Bronchial smooth muscle cell in asthma: where does it fit?

Asthma is a frequent respiratory condition whose pathophysiology relies on altered interactions between bronchial epithelium, smooth muscle cells (SMC) and immune responses. Those leads to classical hallmarks of asthma: airway hyper-responsiveness, bronchial remodelling and chronic inflammation. Airway smooth muscle biology and pathophysiological implication in asthma are now better understood. Precise deciphering of intracellular signalling pathways regulating smooth muscle contraction highlighted the critical roles played by small GTPases of Rho superfamily. Beyond contractile considerations, active involvement of airway smooth muscle in bronchial remodelling mechanisms is now established. Not only cytokines and growth factors, such as fibroblats growth factor or transforming growth factor-β, but also extracellular matrix composition have been demonstrated as potent phenotype modifiers for airway SMC. Although basic science knowledge has grown significantly, little of it has translated into improvement in asthma clinical practice. Evaluation of airway smooth muscle function is still limited to its contractile activity. Moreover, it relies on tools, such as spirometry, that give only an overall assessment and not a specific one. Interesting technics such as forced oscillometry or specific imagery (CT and MRI) give new perspectives to evaluate other aspects of airway muscle such as bronchial remodelling. Finally, except for the refinement of conventional bronchodilators, no new drug therapy directly targeting airway smooth muscle proved its efficacy. Bronchial thermoplasty is an innovative and efficient therapeutic strategy but is only restricted to a small proportion of severe asthmatic patients. New diagnostic and therapeutic strategies specifically oriented toward airway smooth muscle are needed to improve global asthma care.

Hyperresponsiveness to Extracellular Acidification-Mediated Contraction in Isolated Bronchial Smooth Muscles of Murine Experimental Asthma

PURPOSE

Extracellular acidification is a major component of tissue inflammation, including airway inflammation. The extracellular proton-sensing mechanisms are inherent in various cells including airway structural cells, although their physiological and pathophysiological roles in bronchial smooth muscles (BSMs) are not fully understood. In the present study, to explore the functional role of extracellular acidification on the BSM contraction, the isolated mouse BSMs were exposed to acidic pH under contractile stimulation.

METHODS AND RESULTS

The RT-PCR analyses revealed that the proton-sensing G protein-coupled receptors were expressed both in mouse BSMs and cultured human BSM cells. In the mouse BSMs, change in the extracellular pH from 8.0 to 6.8 caused an augmentation of contraction induced by acetylcholine. Interestingly, the acidic pH-induced BSM hyper-contraction was further augmented in the mice that were sensitized and repeatedly challenged with ovalbumin antigen. In this animal model of asthma, upregulations of G protein-coupled receptor 68 (GPR68) and GPR65, that were believed to be coupled with Gq and Gs proteins respectively, were observed, indicating that the acidic pH could cause hyper-contraction probably via an activation of GPR68. However, psychosine, a putative antagonist for GPR68, failed to block the acidic pH-induced responses.

CONCLUSION

These findings suggest that extracellular acidification contributes to the airway hyperresponsiveness, a characteristic feature of bronchial asthma. Further studies are required to identify the receptor(s) responsible for sensing extracellular protons in BSM cells.

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.

Down-regulation of miR-140-3p is a cause of the interlukin-13-induced up-regulation of RhoA protein in bronchial smooth muscle cells

The current study aimed to determine the role of a microRNA (miRNA), miR-140-3p, in the control of RhoA expression in bronchial smooth muscle cells (BSMCs). In cultured human BSMCs, incubation with interleukin-13 (IL-13) caused an up-regulation of RhoA protein concurrently with a down-regulation of miR-140-3p. Transfection of the cells with a miR-140-3p inhibitor caused an increase in basal RhoA protein level. Although a mimic of miR-140-3p had little effect on the basal RhoA level, its treatment inhibited the IL-13-induced up-regulation of RhoA. These findings suggest that RhoA expression is negatively regulated by miR-140-3p, and that the negative regulation is inhibited by IL-13 to cause an up-regulation of RhoA protein in BSMCs.

Cancer-associated fibroblasts as cellular vehicles in endometrial cancer cell migration

Cell motility is a critical step in the metastasis cascade. However, the role of cancer-associated fibroblasts (CAFs) in facilitating endometrial cancer (EC) cell motility remains unclear. The present study aimed to investigate the role of CAFs in EC motility in a 3D environment. A co-culture model was established using an EC cell line (ECC-1) and CAFs on a Matrigel^® matrix and compared to the respective individual monocultures. It was demonstrated that endometrial CAFs increased the motility of the EC cell line, compared with the monoculture. Using live cell imaging, CAFs were observed to form cell projections that served as contact guidance for ECC-1 cell locomotion in the spheroid formation process. These effects were specific to CAFs, as fibroblasts isolated from benign endometrial tissue samples did not form cell projections. Molecular analysis revealed that RhoA/Rho-associated, coiled-coil containing protein kinase 1 (ROCK1) signaling activation partly contributed to CAF-mediated ECC-1 cell migration. The presence of Matrigel^® increased the mRNA expression of RhoA, and the mRNA and protein expression levels of its downstream effectors, ROCK1 and p-MLC, respectively, in the ECC-1 and CAF co-culture, as well as the ECC-1 and CAF monocultures. Interestingly, high phosphorylation levels of myosin light chain mediated the activation of RhoA/ROCK1 signaling in the ECC-1 and CAF co-culture. The ROCK1 inhibitor Y-27632 attenuated the motility of tumor cells in ECC-1 and CAF co-cultures. However, similar treatment led to a significant inhibition in the motility of the CAF monoculture, but not the ECC-1 monoculture. Moreover, tumor spheroid formation was inhibited due to a reduction in stress fiber formation in ECC-1 and CAF co-cultures. Altogether, these findings suggest that the regulation of the RhoA/ROCK1 signaling pathway is required for CAFs to serve as cellular vehicles in order for EC cells to migrate and form spheroids in a 3D environment.

Differential Regulation of the Asthmatic Phenotype by the Aryl Hydrocarbon Receptor

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that regulates the metabolism of xenobiotics. There is growing evidence that the AhR is implicated in physiological processes such proliferation, differentiation, and immune responses. Recently, a role of the AhR in regulating allergic asthma has been suggested, but whether the AhR also regulates other type of asthma, particularly occupational/irritant-induced asthma, remains unknown. Using AhR-deficient (Ahr^−/−) mice, we compared the function of the AhR in the response to ovalbumin (OVA; allergic asthma) vs. chlorine (Cl₂; irritant-induced asthma) exposure. Lung inflammation and airway hyperresponsiveness were assessed 24h after exposure to Cl₂ or OVA challenge in Ahr^−/− and heterozygous (Ahr^+/−) mice. After OVA challenge, absence of AhR was associated with significantly enhanced eosinophilia and lymphocyte influx into the airways of Ahr^−/− mice. There were also increased levels of interleukin-4 (IL-4) and IL-5 in the airways. However, OVA-induced airway hyperresponsiveness was not affected. In the irritant-induced asthma model caused by exposure to Cl₂, the AhR did not regulate the inflammatory response. However, absence of AhR reduced Cl₂-induced airway hyperresponsiveness. Collectively, these results support a differential role for the AhR in regulating asthma outcomes in response to diverse etiological agents.

Role of miR-185-5p as modulator of periostin synthesis and smooth muscle contraction in asthma

Asthma is a chronic respiratory disease produced by an aberrant immune response that originates with breathing difficulties and cough, through airway remodeling. The above pathophysiological events of asthma emerge the regulators of effectors, like epigenetics, which include microRNAs (miRNAs) who perform post‐transcriptional regulation, controlling diverse pathways in respiratory diseases. The objective of the study was to determine how miR‐185‐5p regulates the secretion of periostin by airway structural cells, and smooth muscle cells contraction, both related to airway remodeling in asthma. We used miR‐185‐5p mimic and inhibitors in bronchial smooth muscle cells (BSMCs) and small airway epithelial cells (SAECs) from healthy subjects. Gene expression and protein levels of periostin (POSTN), CDC42, and RHOA were analyzed by RT‐PCR and ELISA/Western blot, respectively. BSMC contractility was analyzed using cell‐embedded collagen gels and measurement of intracellular calcium was performed using Fura‐2. Additionally, miR‐185‐5p and periostin expression were evaluated in sputum from healthy and asthmatics. From these experiments, we observed that miR‐185‐5p modulation regulates periostin mRNA and protein in BSMCs and SAECs. A tendency for diminished miR‐185‐5p expression and higher periostin levels was seen in sputum cells from asthmatics compared to healthy, with an inverse correlation observed between POSTN and miR‐185‐5p. Inhibition of miR‐185‐5p produced higher BSMCs contraction induced by histamine. Calcium mobilization was not modified by miR‐185‐5p, showing that miR‐185‐5p role in BSMC contractility is performed by regulating CDC42 and RhoA pro‐contractile factors instead. In conclusion, miR‐185‐5p is a modulator of periostin secretion by airway structural cells and of smooth muscle contraction, which can be related to asthma pathophysiology, and thus, might be a promising therapeutic target.

Anti-interleukin-13 and anti-interleukin-4 agents versus placebo, anti-interleukin-5 or anti-immunoglobulin-E agents, for people with asthma

BACKGROUND

Targeting the immunoglobulin E pathway and the interleukin-5 pathway with specific monoclonal antibodies directed against the cytokines or their receptors is effective in patients with severe asthma. However, there are patients who have suboptimal responses to these biologics. Since interleukin-4 and interleukin-13, signalling through the interleukin-4 receptor, have multiple effects on the biology of asthma, therapies targeting interleukin-4 and -13 (both individually and combined) have been developed.

OBJECTIVES

To assess the efficacy and safety of anti-interleukin-13 or anti-interleukin-4 agents, compared with placebo, anti-immunoglobulin E agents, or anti-interleukin-5 agents, for the treatment of children, adolescents, or adults with asthma.

SEARCH METHODS

We identified studies from the Cochrane Airways Trials Register, which is maintained by the Information Specialist for the Group and through searches of the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform. The search was carried out on the 16 October 2020.

SELECTION CRITERIA

We included parallel-group randomised controlled trials that compared anti-interleukin-13 or -4 agents (or agents that target both interleukin-13 and interleukin-4) with placebo in adolescents and adults (aged 16 years or older) or children (younger than 16 years), with a diagnosis of asthma; participants could receive their usual short- or long-acting medications (e.g. inhaled corticosteroids (ICS), long-acting beta adrenoceptor agonists (LABA), long-acting muscarinic antagonists (LAMA), and/or leukotriene receptor antagonists) provided that they were not part of the randomised treatment.

DATA COLLECTION AND ANALYSIS

We used standard methods expected by Cochrane.

MAIN RESULTS

We identified and included 41 RCTs. Of these, 29 studies contributed data to the quantitative analyses, randomly assigning 10,604 people with asthma to receive an anti-interleukin-13 (intervention) or anti-interleukin-4 agent (intervention), or placebo (comparator). No relevant studies were identified where the comparator was an anti-immunoglobulin agent or an anti-interleukin-5 agent. Studies had a duration of between 2 and 52 (median 16) weeks. The mean age of participants across the included studies ranged from 22 to 55 years. Only five studies permitted enrolment of children and adolescents, accounting for less than 5% of the total participants contributing data to the present review. The majority of participants had moderate or severe uncontrolled asthma. Concomitant ICS use was permitted or required in the majority (21 of 29) of the included studies. The use of maintenance systemic corticosteroids was not permitted in 19 studies and was permitted or required in five studies (information not reported in five studies). Regarding the most commonly assessed anti-interleukin-13/-4 agents, four studies evaluated dupilumab (300 mg once every week (Q1W), 200 mg once every two weeks (Q2W), 300 mg Q2W, 200 mg once every four weeks (Q4W), 300 mg Q4W, each administered by subcutaneous (SC) injection); eight studies evaluated lebrikizumab (37.5 mg Q4W, 125 mg Q4W, 250 mg Q4W each administered by SC injection); and nine studies (3259 participants) evaluated tralokinumab (75 mg Q1W, 150 mg Q1W, 300 mg Q1W, 150 mg Q2W, 300 mg Q2W, 600 mg Q2W, 300 mg Q4W, each administered by SC injection; 1/5/10 mg/kg administered by intravenous (IV) injection); all anti-interleukin-13 or-4 agents were compared with placebo. The risk of bias was generally considered to be low or unclear (insufficient detail provided); nine studies were considered to be at high risk for attrition bias and three studies were considered to be at high risk for reporting bias. The following results relate to the primary outcomes. The rate of exacerbations requiring hospitalisation or emergency department (ED) visit was probably lower in participants receiving tralokinumab versus placebo (rate ratio 0.68, 95% CI 0.47 to 0.98; moderate-certainty evidence; data available for tralokinumab (anti-interleukin-13) only). In participants receiving an anti-interleukin-13/-4 agent, the mean improvement versus placebo in adjusted asthma quality of life questionnaire score was 0.18 units (95% CI 0.12 to 0.24; high-certainty evidence); however, this finding was deemed not to be a clinically relevant improvement. There was likely little or no difference between groups in the proportion of patients who reported all-cause serious adverse events (anti-interleukin-13/-4 agents versus placebo, OR 0.91, 95% CI 0.76 to 1.09; moderate-certainty evidence). In terms of secondary outcomes, there may be little or no difference between groups in the proportion of patients who experienced exacerbations requiring oral corticosteroids (anti-interleukin-13/-4 agents versus placebo, rate ratio 0.98, 95% CI 0.72 to 1.32; low-certainty evidence). Anti-interleukin-13/-4 agents probably improve asthma control based on asthma control questionnaire score (anti-interleukin-13/-4 agents versus placebo, mean difference -0.19; 95% CI -0.24 to -0.14); however, the magnitude of this result was deemed not to be a clinically relevant improvement. The proportion of patients experiencing any adverse event was greater in those receiving anti-interleukin-13/-4 agents compared with those receiving placebo (OR 1.16, 95% CI 1.04 to 1.30; high-certainty evidence); the most commonly reported adverse events in participants treated with anti-interleukin-13/-4 agents were upper respiratory tract infection, nasopharyngitis, headache and injection site reaction. The pooled results for the exploratory outcome, the rate of exacerbations requiring oral corticosteroids (OCS) or hospitalisation or emergency department visit, may be lower in participants receiving anti-interleukin-13/-4 agents versus placebo (rate ratio 0.71, 95% CI 0.65 to 0.77; low-certainty evidence). Results were generally consistent across subgroups for different classes of agent (anti-interleukin-13 or anti-interleukin-4), durations of study and severity of disease. Subgroup analysis based on category of T helper 2 (TH2) inflammation suggested greater efficacy in patients with higher levels of inflammatory biomarkers (blood eosinophils, exhaled nitric oxide and serum periostin).

AUTHORS' CONCLUSIONS

Based on the totality of the evidence, compared with placebo, anti-interleukin-13/-4 agents are probably associated with a reduction in exacerbations requiring hospitalisation or ED visit, at the cost of increased adverse events, in patients with asthma. No clinically relevant improvements in health-related quality of life or asthma control were identified. Therefore, anti-interleukin-13 or anti-interleukin-4 agents may be appropriate for adults with moderate-to-severe uncontrolled asthma who have not responded to other treatments. These conclusions are generally supported by moderate or high-certainty evidence based on studies with an observation period of up to one year.

The Impact of Monoclonal Antibodies on Airway Smooth Muscle Contractility in Asthma: A Systematic Review

Airway hyperresponsiveness (AHR) represents a central pathophysiological hallmark of asthma, with airway smooth muscle (ASM) being the effector tissue implicated in the onset of AHR. ASM also exerts pro-inflammatory and immunomodulatory actions, by secreting a wide range of cytokines and chemokines. In asthma pathogenesis, the overexpression of several type 2 inflammatory mediators including IgE, IL-4, IL-5, IL-13, and TSLP has been associated with ASM hyperreactivity, all of which can be targeted by humanized monoclonal antibodies (mAbs). Therefore, the aim of this review was to systematically assess evidence across the literature on mAbs for the treatment of asthma with respect to their impact on the ASM contractile tone. Omalizumab, mepolizumab, benralizumab, dupilumab, and tezepelumab were found to be effective in modulating the contractility of the ASM and preventing the AHR, but no available studies concerning the impact of reslizumab on the ASM were identified from the literature search. Omalizumab, dupilumab, and tezepelumab can directly modulate the ASM in asthma, by specifically blocking the interaction between IgE, IL-4, and TSLP, and their receptors are located on the surface of ASM cells. Conversely, mepolizumab and benralizumab have prevalently indirect impacts against AHR by targeting eosinophils and other immunomodulatory effector cells promoting inflammatory processes. AHR has been suggested as the main treatable trait towards precision medicine in patients suffering from eosinophilic asthma, therefore, well-designed head-to-head trials are needed to compare the efficacy of those mAbs that directly target ASM contractility specifically against the AHR in severe asthma, namely omalizumab, dupilumab, and tezepelumab.

Ding Chuan Tang Attenuates Airway Inflammation and Eosinophil Infiltration in Ovalbumin-Sensitized Asthmatic Mice

Asthma is a T helper 2 (Th2) cell-associated chronic inflammatory diseases characterized with airway obstruction, increased mucus production, and eosinophil infiltration. Conventional medications for asthma treatment cannot fully control the symptoms, and potential side effects are also the concerns. Thus, complement or alternative medicine (CAM) became a new option for asthma management. Ding Chuan Tang (DCT) is a traditional Chinese herbal decoction applied mainly for patients with coughing, wheezing, chest tightness, and asthma. Previously, DCT has been proved to improve children airway hyperresponsiveness (AHR) in a randomized and double-blind clinical trial. However, the mechanisms of how DCT alleviates AHR remain unclear. Since asthmatic features such as eosinophil infiltration, IgE production, and mucus accumulation are relative with Th2 responses, we hypothesized that DCT may attenuate asthma symptoms through regulating Th2 cells. Ovalbumin (OVA) was used as a stimulant to sensitize BALB/c mice to establish an asthmatic model. AHR was detected one day before sacrifice. BALF and serum were collected for immune cell counting and antibody analysis. Splenocytes were cultured with OVA in order to determine Th2 cytokine production. Lung tissues were collected for histological and gene expression analyses. Our data reveal that DCT can attenuate AHR and eosinophil accumulation in the 30-day sensitization asthmatic model. Histological results demonstrated that DCT can reduce cell infiltration and mucus production in peribronchial and perivascular site. In OVA-stimulated splenocyte cultures, a significant reduction of IL-5 and IL-13 in DCT-treated mice suggests that DCT may alleviate Th2 responses. In conclusion, the current study demonstrates that DCT has the potential to suppress allergic responses through the reduction of mucus production, eosinophil infiltration, and Th2 activity in asthma.

Carbazole Derivatives as STAT Inhibitors: An Overview

The carbazole class is made up of heterocyclically structured compounds first isolated from coal tar. Their structural motif is preponderant in different synthetic materials and naturally occurring alkaloids extracted from the taxonomically related higher plants of the genus Murraya, Glycosmis, and Clausena from the Rutaceae family. Concerning the biological activity of these compounds, many research groups have assessed their antiproliferative action of carbazoles on different types of tumoral cells, such as breast, cervical, ovarian, hepatic, oral cavity, and small-cell lung cancer, and underlined their potential effects against psoriasis. One of the principal mechanisms likely involved in these effects is the ability of carbazoles to target the JAK/STATs pathway, considered essential for cell differentiation, proliferation, development, apoptosis, and inflammation. In this review, we report the studies carried out, over the years, useful to synthesize compounds with carbazole moiety designed to target these kinds of kinases.

Intrauterine growth restriction predisposes to airway inflammation without disruption of epithelial integrity in postnatal male mice

Evidence from animal models demonstrate that intrauterine growth restriction (IUGR) alters airway structure and function which may affect susceptibility to disease. Airway inflammation and dysregulated epithelial barrier properties are features of asthma which have not been examined in the context of IUGR. This study used a maternal hypoxia-induced IUGR mouse model to assess lung-specific and systemic inflammation and airway epithelial tight junctions (TJs) protein expression. Pregnant BALB/c mice were housed under hypoxic conditions (10.5% O2) from gestational day (GD) 11 to 17.5 (IUGR group; term, GD 21). Following hypoxic exposure, mice were returned to a normoxic environment (21% O2). A Control group was housed under normoxic conditions throughout pregnancy. Offspring weights were recorded at 2 and 8 weeks of age and euthanized for bronchoalveolar lavage (BAL) and peritoneal cavity fluid collection for inflammatory cells counts. From a separate group of mice, right lungs were collected for Western blotting of TJs proteins. IUGR offspring had greater inflammatory cells in the BAL fluid but not in peritoneal fluid compared with Controls. At 8 weeks of age, interleukin (IL)-2, IL-13, and eotaxin concentrations were higher in male IUGR compared with male Control offspring but not in females. IUGR had no effect on TJs protein expression. Maternal hypoxia-induced IUGR increases inflammatory cells in the BAL fluid of IUGR offspring with no difference in TJs protein expression. Increased cytokine release, specific to the lungs of IUGR male offspring, indicates that both IUGR and sex can influence susceptibility to airway disease.

ORMDL3 expression in ASM regulates hypertrophy, hyperplasia via TPM1 and TPM4, and contractility

ORM1-like 3 (ORMDL3) has strong genetic linkage to childhood onset asthma. To determine whether ORMDL3 selective expression in airway smooth muscle (ASM) influences ASM function, we used Cre-loxP techniques to generate transgenic mice (hORMDL3Myh11eGFP-cre), which express human ORMDL3 selectively in smooth muscle cells. In vitro studies of ASM cells isolated from the bronchi of hORMDL3Myh11eGFP-cre mice demonstrated that they developed hypertrophy (quantitated by FACS and image analysis), developed hyperplasia (assessed by BrdU incorporation), and expressed increased levels of tropomysin proteins TPM1 and TPM4. siRNA knockdown of TPM1 or TPM4 demonstrated their importance to ORMDL3-mediated ASM proliferation but not hypertrophy. In addition, ASM derived from hORMDL3Myh11eGFP-cre mice had increased contractility to histamine in vitro, which was associated with increased levels of intracellular Ca2+; increased cell surface membrane Orai1 Ca2+ channels, which mediate influx of Ca2+ into the cytoplasm; and increased expression of ASM contractile genes sarco/endoplasmic reticulum Ca2+ ATPase 2b and smooth muscle 22. In vivo studies of hORMDL3Myh11eGFP-cre mice demonstrated that they had a spontaneous increase in ASM and airway hyperreactivity (AHR). ORMDL3 expression in ASM thus induces changes in ASM (hypertrophy, hyperplasia, increased contractility), which may explain the contribution of ORMDL3 to the development of AHR in childhood onset asthma, which is highly linked to ORMDL3 on chromosome 17q12-21.

Increased Gene expression of CCL2/CCR2 axis in bronchial smooth muscles of allergen-challenged mice

PURPOSE

Augmented bronchial smooth muscle (BSM) contraction is a cause of airway hyperresponsiveness (AHR) in asthma. Increasing evidence suggest that C-C motif chemokine 2 (CCL2) modulates smooth muscle contractility by activating its binding partner C-C chemokine receptor type 2 (CCR2). In the present study, changes in the gene expression of CCL2/CCR2 axis were determined in the BSMs of a murine model of allergic asthma.

MATERIALS AND METHODS

The ovalbumin (OA)-sensitized mice were repeatedly challenged with aerosolized OA to induce asthmatic reaction. Twenty-four hours after the last antigen challenge, total RNAs of the main BSM tissues and bronchoalveolar lavage fluids (BALFs) were obtained.

RESULTS

Our published microarray data (GEO accession No. GSE116504) detected changes in gene expression associated with the chemokine signaling pathway (KEGG Map ID: 04062) in BSMs of mice with AHR induced by antigen exposure. Among them, quantitative RT-PCR analyses showed significant increase in mRNA expression of Ccl2 and Ccr2. Analysis of BALFs also revealed a significant increase in Ccl2 protein in the airways of the diseased animals.

CONCLUSION

It is thus possible that, in association with the AHR, the CCL2/CCR2 axis is enhanced in the airways of allergic bronchial asthma.

[Non-coding RNAs and bronchial smooth muscle hyperresponsiveness in allergic bronchial asthma]

Non-coding RNAs, such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), play important roles in normal and diseased cell functions. A small GTPase RhoA is a key protein of bronchial smooth muscle (BSM) contraction, and an up-regulation of RhoA has been demonstrated in BSMs of experimental asthma. Our previous study also demonstrated that RhoA translation was controlled by a miRNA, miR-133a, in BSMs. In human BSM cells (hBSMCs), an up-regulation of RhoA was observed when the function of endogenous miR-133a was inhibited by its antagomir. Treatment of hBSMCs with interleukin-13 (IL-13) caused an up-regulation of RhoA and a down-regulation of miR-133a. In a murine experimental asthma, increased expression of IL-13 and RhoA and the BSM hyperresponsiveness were observed. Interestingly, the level of miR-133a was significantly decreased in BSMs of the diseased animals. These findings suggest that RhoA expression is negatively regulated by miR-133a in BSMs, and that the miR-133a down-regulation causes an up-regulation of RhoA, resulting in an augmentation of the contraction. Recent studies also revealed an inhibitory effect of lncRNA Malat1 on the miR-133a function. Thus, lncRNAs/miRNAs might be key regulators of BSM hyperresponsiveness, and provide us a new insight into the treatment of airway hyperresponsiveness in asthmatics.

The roles of post-translational modifications and coactivators of STAT6 signaling in tumor growth and progression

Signal transducers and activators of transcription 6 (STAT6) are highly expressed in various tumors and associated with tumorigenesis, immunosuppression, proliferation, metastasis and poor prognosis in human cancers. In response to IL-4/13, STAT6 is phosphorylated, dimerizes and triggers transcriptional regulation after recruitment of coactivators to transcriptosome, such as CBP/p300, SRC-1, PARP-14 and PSF. Post-translational modifications, including phosphorylation, ubiquitination, ADP-ribosylation and acetylation, have been explored for molecular mechanisms of STAT6 in tumor development and management. STAT6 has been developed as a specific biomarker for distinguishing and diagnosing tumor phenotypes, although it is observed to be frequently mutated in metastatic tumors. In this article, we focus mainly on the structural characteristics of STAT6 and its role in tumor growth and progression.

Downregulation of miR-140-3p Contributes to Upregulation of CD38 Protein in Bronchial Smooth Muscle Cells

In allergic bronchial asthma, an increased smooth muscle contractility of the airways is one of the causes of the airway hyperresponsiveness (AHR). Increasing evidence also suggests a possible involvement of microRNAs (miRNAs) in airway diseases, including asthma, although their roles in function and pathology largely unknown. The current study aimed to determine the role of a miRNA, miR-140-3p, in the control of protein expression of CD38, which is believed to regulate the contraction of smooth muscles, including the airways. In bronchial smooth muscles (BSMs) of the mice that were actively sensitized and repeatedly challenged with ovalbumin antigen, an upregulation of CD38 protein concurrently with a significant reduction of miR-140-3p was observed. In cultured human BSM cells (hBSMCs), transfection with a synthetic miR-140-3p inhibitor caused an increase in CD38 protein, indicating that its basal protein expression is regulated by endogenous miR-140-3p. Treatment of the hBSMCs with interleukin-13 (IL-13), an asthma-related cytokine, caused both an upregulation of CD38 protein and a downregulation of miR-140-3p. Transfection of the hBSMCs with miR-140-3p mimic inhibited the CD38 protein upregulation induced by IL-13. On the other hand, neither a CD38 product cyclic ADP-ribose (cADPR) nor its antagonist 8-bromo-cADPR had an effect on the BSM contraction even in the antigen-challenged mice. Taken together, the current findings suggest that the downregulation of miR-140-3p induced by IL-13 might cause an upregulation of CD38 protein in BSM cells of the disease, although functional and pathological roles of the upregulated CD38 are still unclear.

Attenuation of relaxing response induced by pituitary adenylate cyclase-activating polypeptide in bronchial smooth muscle of experimental asthma

Bronchomotor tone is regulated by contraction and relaxation of airway smooth muscle (ASM). A weakened ASM relaxation might be a cause of airway hyperresponsiveness (AHR), a characteristic feature of bronchial asthma. Pituitary adenylyl cyclase-activating polypeptide (PACAP) is known as a mediator that causes ASM relaxation. To date, whether or not the PACAP responsiveness is changed in asthmatic ASM is unknown. The current study examined the hypothesis that relaxation induced by PACAP is reduced in bronchial smooth muscle (BSM) of allergic asthma. The ovalbumin (OA)-sensitized mice were repeatedly challenged with aerosolized OA to induce asthmatic reaction. Twenty-four hours after the last antigen challenge, the main bronchial smooth muscle (BSM) tissues were isolated. Tension study showed a BSM hyperresponsiveness to acetylcholine in the OA-challenged mice. Both quantitative RT-PCR and immunoblot analyses revealed a significant decrease in PAC₁ receptor expression in BSMs of the diseased mice. Accordingly, in the antigen-challenged group, the PACAP-induced PAC₁ receptor-mediated BSM relaxation was significantly attenuated, whereas the relaxation induced by vasoactive intestinal polypeptide was not changed. These findings suggest that the relaxation induced by PACAP is impaired in BSMs of experimental asthma due to a downregulation of its binding partner PAC₁ receptor. Impaired BSM responsiveness to PACAP might contribute to the AHR in asthma.

Cytokine-induced molecular responses in airway smooth muscle cells inform genome-wide association studies of asthma

BACKGROUND

A challenge in the post-GWAS era is to assign function to disease-associated variants. However, available resources do not include all tissues or environmental exposures that are relevant to all diseases. For example, exaggerated bronchoconstriction of airway smooth muscle cells (ASMCs) defines airway hyperresponsiveness (AHR), a cardinal feature of asthma. However, the contribution of ASMC to genetic and genomic studies has largely been overlooked. Our study aimed to address the gap in data availability from a critical tissue in genomic studies of asthma.

METHODS

We developed a cell model of AHR to discover variants associated with transcriptional, epigenetic, and cellular responses to two AHR promoting cytokines, IL-13 and IL-17A, and performed a GWAS of bronchial responsiveness (BRI) in humans.

RESULTS

Our study revealed significant response differences between ASMCs from asthma cases and controls, including genes implicated in asthma susceptibility. We defined molecular quantitative trait loci (QTLs) for expression (eQTLs) and methylation (meQTLs), and cellular QTLs for contractility (coQTLs) and performed a GWAS of BRI in human subjects. Variants in asthma GWAS were significantly enriched for ASM QTLs and BRI-associated SNPs, and near genes enriched for ASM function, many with small P values that did not reach stringent thresholds of significance in GWAS.

CONCLUSIONS

Our study identified significant differences between ASMCs from asthma cases and controls, potentially reflecting trained tolerance in these cells, as well as a set of variants, overlooked in previous GWAS, which reflect the AHR component of asthma.

Sustained exposure to prostaglandin D2 augments the contraction induced by acetylcholine via a DP1 receptor-mediated activation of p38 in bronchial smooth muscle of naive mice

Prostaglandin D₂ (PGD₂), one of the key lipid mediators of allergic airway inflammation, is increased in the airways of asthmatics. However, the role of PGD₂ in the pathogenesis of asthma is not fully understood. In the present study, effects of PGD₂ on smooth muscle contractility of the airways were determined to elucidate its role in the development of airway hyperresponsiveness (AHR). In a murine model of allergic asthma, antigen challenge to the sensitized animals caused a sustained increase in PGD₂ levels in bronchoalveolar lavage (BAL) fluids, indicating that smooth muscle cells of the airways are continually exposed to PGD₂ after the antigen exposure. In bronchial smooth muscles (BSMs) isolated from naive mice, a prolonged incubation with PGD₂ (10⁻⁵ M, for 24 h) induced an augmentation of contraction induced by acetylcholine (ACh): the ACh concentration-response curve was significantly shifted upward by the 24-h incubation with PGD₂. Application of PGD₂ caused phosphorylation of ERK1/2 and p38 in cultured BSM cells: both of the PGD₂-induced events were abolished by laropiprant (a DP₁ receptor antagonist) but not by fevipiprant (a DP₂ receptor antagonist). In addition, the BSM hyperresponsiveness to ACh induced by the 24-h incubation with PGD₂ was significantly inhibited by co-incubation with SB203580 (a p38 inhibitor), whereas U0126 (a ERK1/2 inhibitor) had no effect on it. These findings suggest that prolonged exposure to PGD₂ causes the BSM hyperresponsiveness via the DP₁ receptor-mediated activation of p38. A sustained increase in PGD₂ in the airways might be a cause of the AHR in allergic asthmatics.

Implications of immune-inflammatory responses in smooth muscle dysfunction and disease

In the past few decades, solid evidence has been accumulated for the pivotal significance of immunoinflammatory processes in the initiation, progression, and exacerbation of many diseases and disorders. This groundbreaking view came from original works by Ross who first described that excessive inflammatory-fibroproliferative response to various forms of insult to the endothelium and smooth muscle of the artery wall is essential for the pathogenesis of atherosclerosis (Ross, Nature 1993; 362(6423): 801–9). It is now widely recognized that both innate and adaptive immune reactions are avidly involved in the inflammation-related remodeling of many tissues and organs. When this state persists, irreversible fibrogenic changes would occur often culminating in fatal insufficiencies of many vital parenchymal organs such as liver, lung, heart, kidney and intestines. Thus, inflammatory diseases are becoming the common life-threatening risk for and urgent concern about the public health in developed countries (Wynn et al., Nature Medicine 2012; 18(7): 1028–40). Considering this timeliness, we organized a special symposium entitled “Implications of immune/inflammatory responses in smooth muscle dysfunction and disease” in the 58th annual meeting of the Japan Society of Smooth Muscle Research. This symposium report will provide detailed synopses of topics presented in this symposium; (1) the role of inflammasome in atherosclerosis and abdominal aortic aneurysms by Fumitake Usui-Kawanishi and Masafumi Takahashi; (2) Mechanisms underlying the pathogenesis of hyper-contractility of bronchial smooth muscle in allergic asthma by Hiroyasu Sakai, Wataru Suto, Yuki Kai and Yoshihiko Chiba; (3) Vascular remodeling in pulmonary arterial hypertension by Keizo Hiraishi, Lin Hai Kurahara and Ryuji Inoue.

RhoA/Rho-kinases in asthma: from pathogenesis to therapeutic targets

Asthma is a chronic and heterogeneous disease characterised by airway inflammation and intermittent airway narrowing. The key obstacle in the prevention and treatment of asthma has been our incomplete understanding of its aetiology and biological mechanisms. The ras homolog family member A (RhoA) of the Rho family GTPases has been considered to be one of the most promising and novel therapeutic targets for asthma. It is well known that RhoA/Rho‐kinases play an important role in the pathophysiology of asthma, including airway smooth muscle contraction, airway hyper‐responsiveness, β‐adrenergic desensitisation and airway remodelling. However, recent advances have suggested novel roles for RhoA in regulating allergic airway inflammation. Specifically, RhoA has been shown to regulate allergic airway inflammation through controlling Th2 or Th17 cell differentiation and to regulate airway remodelling through regulating mesenchymal stem cell (MSC) differentiation. In this review, we evaluate the literature regarding the recent advances in the activation of RhoA/Rho‐kinase, cytokine and epigenetic regulation of RhoA/Rho‐kinase, and the role of RhoA/Rho‐kinase in regulating major features of asthma, such as airway hyper‐responsiveness, remodelling and inflammation. We also discuss the importance of the newly identified role of RhoA/Rho‐kinase signalling in MSC differentiation and bronchial epithelial barrier dysfunction. These findings indicate the functional significance of the RhoA/Rho‐kinase pathway in the pathophysiology of asthma and suggest that RhoA/Rho‐kinase signalling may be a promising therapeutic target for the treatment of asthma.

Rhinovirus C15 Induces Airway Hyperresponsiveness via Calcium Mobilization in Airway Smooth Muscle

Rhinovirus (RV) exposure evokes exacerbations of asthma that markedly impact morbidity and mortality worldwide. The mechanisms by which RV induces airway hyperresponsiveness (AHR) or by which specific RV serotypes differentially evoke AHR remain unknown. We posit that RV infection evokes AHR and inflammatory mediator release, which correlate with degrees of RV infection. Furthermore, we posit that rhinovirus C-induced AHR requires paracrine or autocrine mediator release from epithelium that modulates agonist-induced calcium mobilization in human airway smooth muscle. In these studies, we used an ex vivo model to measure bronchoconstriction and mediator release from infected airways in human precision cut lung slices to understand how RV exposure alters airway constriction. We found that rhinovirus C15 (RV-C15) infection augmented carbachol-induced airway narrowing and significantly increased release of IP-10 (IFN-γ-induced protein 10) and MIP-1β (macrophage inflammatory protein-1β) but not IL-6. RV-C15 infection of human airway epithelial cells augmented agonist-induced intracellular calcium flux and phosphorylation of myosin light chain in co-cultured human airway smooth muscle to carbachol, but not after histamine stimulation. Our data suggest that RV-C15-induced structural cell inflammatory responses are associated with viral load but that inflammatory responses and alterations in agonist-mediated constriction of human small airways are uncoupled from viral load of the tissue.

Contractile Properties of Intrapulmonary Airway Smooth Muscle in Cystic Fibrosis

Cystic fibrosis (CF) is an autosomal-recessive disease caused by mutations in the CF transmembrane conductance regulator gene. Many patients with CF have asthma-like symptoms and airway hyperresponsiveness, which are potentially associated with altered airway smooth muscle (ASM) contractility. Our goal in this study was to assess the contractility of the CF intrapulmonary ASM. ASM strips were dissected from human control and CF intrapulmonary airways, and assessed for methacholine-induced shortening velocity, maximal force, and stress. We also assessed isoproterenol responses in maximally methacholine-contracted ASM. ASM strips were then incubated for 16 hours with IL-13 and measurements were repeated. Myosin light chain kinase (MLCK) expression was assessed by Western blotting. Airways were immunostained for morphometry. ASM mass was increased in CF airways, which likely contributes to airway hyperresponsiveness. Although ASM contractile properties were not intrinsically different between patients with CF and control subjects, CF ASM responded differently in the presence of the inflammatory mediator IL-13, showing impairment in β-adrenergic-induced relaxation. Indeed, the percentage of relaxation measured at maximal isoproterenol concentrations in the CF ASM was significantly lower after incubation with IL-13 (46.0% ± 6.7% relaxation) than without IL-13 (74.0% ± 7.7% relaxation, P = 0.018). It was also significantly lower than that observed in control ASM incubated with IL-13 (68.8% ± 4.9% relaxation, P = 0.048) and without IL-13 (82.4% ± 9.9%, P = 0.0035). CF ASM incubated with IL-13 also expressed greater levels of MLCK. Thus, our data suggest that the combination of an increase in ASM mass, increased MLCK expression, and inflammation-induced β-adrenergic hyporesponsiveness may contribute to airway dysfunction in CF.

Integrating Selective Targeted Monoclonal Antibody Therapies for Improved Outcomes in Uncontrolled Asthma

Asthma is one of the most common chronic diseases, with ≤25% of patients experiencing uncontrolled disease.1Patients with uncontrolled, moderate-to-severe asthma are at increased risk of recurrent exacerbations, accelerated decline in lung function, fixed airway obstruction, and have increased utilisation of health care resources.2,3Furthermore, reduced lung function, as assessed by measures such as forced expiratory volume in 1 second (FEV1), is a strong independent predictor of exacerbations, progressive decline in lung function, and all-cause pulmonary and cardiovascular mortality in patients with asthma.2 Achieving asthma control in these patients is therefore critical. The recognition of distinct inflammatory phenotypes within this population has been instrumental in addressing this need. In these patients, there is robust evidence of the pathogenic role of Th2 cytokines, such as IL-4 and IL-13, in the eosinophilic and allergic inflammatory processes.4This in turn has driven the development of targeted biological therapies, particularly selective targeted monoclonal antibodies such as dupilumab which inhibit the biological effects of both IL-4 and IL-13.5 This article reviews four posters displayed at the European Respiratory Society (ERS) International Congress 2019 that presented results demonstrating the efficacy and safety of dupilumab, an anti-IL-4 receptor human monoclonal antibody, compared to placebo for the treatment of uncontrolled, moderate-to-severe asthma, as measured by a range of outcomes.

IL-13 and IL-4, but not IL-5 nor IL-17A, induce hyperresponsiveness in isolated human small airways

BACKGROUND

Specific inflammatory pathways are indicated to contribute to severe asthma, but their individual involvement in the development of airway hyperresponsiveness remains unexplored.

OBJECTIVE

This experimental study in human small bronchi aimed to provide insight into which of the type 2 and type 17 cytokines cause hyperresponsiveness of airway smooth muscle.

METHODS

Explanted small bronchi isolated from human lung tissue and human airway smooth muscle cells were treated for 2 and 1 day(s), respectively, with 100 ng/mL of IL-4, IL-5, IL-13, or IL-17A, and contractile responses, Ca²⁺ mobilization, and receptor expression were assessed.

RESULTS

Treatment with IL-13 increased the potency of histamine, carbachol, and leukotriene D₄ as contractile agonists. IL-4, but not IL-5 or IL-17A, also increased the potency of histamine. In human airway smooth muscle cells, IL-13 and IL-4, but not IL-5 and IL-17A, enhanced the histamine-induced Ca²⁺ mobilization that was accompanied with increased mRNA expression of histamine H₁ and cysteinyl leukotriene CysLT₁ receptors. RNA sequencing of isolated bronchi confirmed the IL-13-mediated upregulation of H₁ and CysLT₁ receptors, without showing an alteration of muscarinic M₃ receptors. Dexamethasone had no effects on IL-13-induced hyperresponsiveness in human bronchi, the increased Ca²⁺ mobilization, or the enhanced receptor expression. In contrast, antagonism of the common receptor for IL-13 and IL-4 by the biologic dupilumab prevented the effects of both IL-13 and IL-4 in human bronchi and human airway smooth muscle cells.

CONCLUSIONS

The glucocorticoid-insensitive hyperrresponsiveness in isolated human airways induced by IL-13 and IL-4 provides further evidence that the IL-4Rα pathway should be targeted as a new strategy for the treatment of airway hyperresponsiveness in asthma.

Targeting cell signaling in allergic asthma

Asthma is chronic inflammation of the airways characterized by airway hyper-responsiveness, wheezing, cough, and dyspnea. Asthma affects >350 million people worldwide. The Th2 immune response is a major contributor to the pathophysiology of asthma. Targeted therapy modulating cell signaling pathways can be a powerful strategy to design new drugs to treat asthma. The potential molecular pathways that can be targeted include IL-4-IL-13-JAK-STAT-MAP kinases, adiponectin-iNOS-NF-κB, PGD2-CRTH2, IFNs-RIG, Wnt/β-catenin-FAM13A, FOXC1-miR-PI3K/AKT, JNK-Gal-7, Nrf2-ROS, Foxp3-RORγt, CysLTR, AMP, Fas-FasL, PTHrP/PPARγ, PAI-1, FcɛRI-LAT-SLP-76, Tim-3-Gal-9, TLRs-MyD88, PAR2, and Keap1/Nrf2/ARE. Therapeutic drugs can be designed to target one or more of these pathways to treat asthma.

Bitter Taste Receptors: an Answer to Comprehensive Asthma Control?

PURPOSE OF REVIEW

Asthma is marked by peculiar pathological features involving airway contraction, an impinging inflammation in the lungs, and an inexorably progressive remodeling of pulmonary architecture. Current medications for management of asthma exacerbations fail to optimally mitigate these pathologies, which is partly due to the intrinsic heterogeneity in the development and progression of asthma within different populations. In recent years, the discovery of the ectopic expression of TAS2Rs in extraoral tissues and different cell types, combined with significant strides in gaining mechanistic understanding into receptor signaling and function, has revealed the potential to target TAS2Rs for asthma relief.

RECENT FINDINGS

TAS2R activation leads to relaxation of airway smooth muscle cells and bronchodilation. In addition, findings from preclinical studies in murine model of asthma suggest that TAS2R agonists inhibit allergen-induced airway inflammation, remodeling, and hyperresponsiveness. In this review, we expand on the opportunity presented by TAS2Rs in the development of a comprehensive asthma treatment that overcomes the limitations set forth by current asthma therapeutics.

Mechanisms underlying TNFα-induced enhancement of force generation in airway smooth muscle

Airway diseases such as asthma are triggered by inflammation and mediated by proinflammatory cytokines such as tumor necrosis factor alpha (TNFα). Our goal was to systematically examine the potential mechanisms underlying the effect of TNFα on airway smooth muscle (ASM) contractility. Porcine ASM strips were incubated for 24 h with and without TNFα. Exposure to TNFα increased maximum ASM force in response to acetylcholine (Ach), with an increase in ACh sensitivity (hyperreactivity), as reflected by a leftward shift in the dose-response curve (EC50 ). At the EC50 , the [Ca2+ ]cyt response to ACh was similar between TNFα and control ASM, while force increased; thus, Ca2+ sensitivity appeared to increase. Exposure to TNFα increased the basal level of regulatory myosin light chain (rMLC) phosphorylation in ASM; however, the ACh-dependent increase in rMLC phosphorylation was blunted by TNFα with no difference in the extent of rMLC phosphorylation at the EC50 ACh concentration. In TNFα-treated ASM, total actin and myosin heavy chain concentrations increased. TNFα exposure also enhanced the ACh-dependent polymerization of G- to F-actin. The results of this study confirm TNFα-induced hyperreactivity to ACh in porcine ASM. We conclude that the TNFα-induced increase in ASM force, cannot be attributed to an enhanced [Ca2+ ]cyt response or to an increase in rMLC phosphorylation. Instead, TNFα increases Ca2+ sensitivity of ASM force generation due to increased contractile protein content (greater number of contractile units) and enhanced cytoskeletal remodeling (actin polymerization) resulting in increased tethering of contractile elements to the cortical cytoskeleton and force translation to the extracellular matrix.

The airway epithelium in asthma

Asthma is a genetically and phenotypically complex disease that has a major impact on global health. Signs and symptoms of asthma are caused by the obstruction of airflow through the airways. The epithelium that lines the airways plays a major role in maintaining airway patency and in host defense. The epithelium initiates responses to inhaled or aspirated substances, including allergens, viruses, and bacteria, and epithelial-derived cytokines are important in the recruitment and activation of immune cells in the airway. Changes in the structure and function of the airway epithelium are a prominent feature of asthma. Approximately half of individuals with asthma have evidence of active type 2 immune responses in the airway. In these individuals, epithelial cytokines promote type 2 responses, and responses to type 2 cytokines result in increased epithelial mucus production and other effects that cause airway obstruction. Recent work also implicates other epithelial responses, including interleukin-17, interferon and ER stress responses, that may contribute to asthma pathogenesis and provide new targets for therapy.

Potential Mechanisms of T Cell-Mediated and Eosinophil-Independent Bronchial Hyperresponsiveness

Bronchial asthma is a chronic disease characterized by reversible airway obstruction, mucus production, and bronchial hyperresponsiveness (BHR). Although Th2 cell-mediated eosinophilic inflammation is an important disease mechanism in the majority of patients with bronchial asthma, recent studies suggest the possible development of Th2-independent airway inflammation and BHR. These non-Th2 endotype patients seem to consist of multiple subgroups, and often do not respond to inhaled corticosteroids. Therefore, to understand the pathogenesis of asthma, it is important to characterize these non-Th2 subgroups. Recently, we demonstrated that Th9 cells induce eosinophil infiltration and eosinophil-independent BHR, and Th9 cells-mediated BHR may be resistant to glucocorticoid. In this review, we summarize the contribution of several T cell subsets in the development of bronchial asthma and introduce our recent study demonstrating Th9 cell-mediated and eosinophil-independent BHR.

The Safety and Efficacy of Anti-IL-13 Treatment with Tralokinumab (CAT-354) in Moderate to Severe Asthma: A Systematic Review and Meta-Analysis

BACKGROUND

Several clinical studies have evaluated the use of tralokinumab (CAT-354) administration in patients with moderate to severe asthma; no consensus on tralokinumab efficacy and safety was reached. Thus, further analysis is required on the efficacy and safety of tralokinumab as an asthma biologic.

OBJECTIVE

To assess the efficacy and safety of subcutaneous injection of tralokinumab in patients with moderate to severe asthma.

METHODS

Clinical trials were identified from MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov from their inception to November 4, 2018. Only randomized clinical trials (RCTs) with tralokinumab versus placebo treatment in patients with moderate to severe asthma were evaluated. Efficacy and safety outcomes were extracted, and a meta-analysis was performed using a random-effects model. The Cochrane Collaboration's risk-of-bias assessment tool was used to assess the risk of bias.

RESULTS

Five studies describing 6 RCTs (including 2928 adults with moderate to severe asthma) were pooled and analyzed in this study. Absolute FEV₁ was statistically improved in patients receiving tralokinumab at 300 mg every 2 weeks (mean difference [MD], 0.14 L; 95% CI, 0.08-0.21) and 600 mg every 2 weeks (MD, 0.20 L; 95% CI, 0.01-0.39), as well as FEV₁% changes (MD, 5.82%, 95% CI, 3.58-8.06, and MD, 11.8%, 95% CI, 0.79-22.81, respectively). Also, absolute forced vital capacity volume changes (MD, 0.11 L; 95% CI, 0.01-0.21) and percentage changes (MD, 4.44%; 95% CI, 0.84-8.04) improved in tralokinumab at 300 mg every 2 weeks. Asthma Quality of Life Questionnaire scores were not significantly different, and absolute Asthma Control Questionnaire 6 scores were statistically improved but did not reach the clinically meaningful difference. Tralokinumab treatment did not decrease annualized asthma exacerbation rate in unselected patients with moderate to severe asthma, but it was associated with improved annualized asthma exacerbation rate in patients with severe asthma with high fractional exhaled nitric oxide levels (rate ratio, 0.72; 95% CI, 0.53-0.97). Tralokinumab was not associated with an increased incidence of serious adverse events, but it did show an increase in mild injection-site reactions (odds ratio, 5.92; 95% CI, 1.61-21.76).

CONCLUSION

This pooled analysis of 6 RCTs suggested that tralokinumab was well tolerated and it modestly improved FEV₁ and forced vital capacity in patients with moderate to severe asthma. It did not render clinically important improvements in asthma-related quality of life, and nor did it reduce asthma exacerbations.

Modulation of Bronchomotor Tone Pathways in Airway Smooth Muscle Function and Bronchomotor Tone in Asthma

Airway smooth muscle is the primary cell mediating bronchomotor tone. The milieu created in the asthmatic lung modulates airway smooth muscle contractility and relaxation. Experimental findings suggest intrinsic abnormalities in airway smooth muscle derived from patients with asthma in comparison with airway smooth muscle from those without asthma. These changes to excitation-contraction pathways may underlie airway hyperresponsiveness and increased airway resistance associated with asthma.

Tralokinumab for severe, uncontrolled asthma (STRATOS 1 and STRATOS 2): two randomised, double-blind, placebo-controlled, phase 3 clinical trials

BACKGROUND

Tralokinumab is an anti-interleukin-13 human monoclonal antibody developed for the treatment of severe, uncontrolled asthma. These clinical trials aimed to assess the efficacy and safety of tralokinumab in this population.

METHODS

STRATOS 1 and STRATOS 2 were randomised, double-blind, parallel-group, placebo-controlled, phase 3 clinical trials that enrolled participants aged 12-75 years with severe asthma that was inadequately controlled despite use of inhaled corticosteroids (≥500 μg per day fluticasone or equivalent) and a long-acting β₂ agonist (but not oral corticosteroids). STRATOS 1 was done at 246 sites in 14 countries, and STRATOS 2 was done at 242 sites in 13 countries. In STRATOS 1, participants were randomly assigned (2:1) to receive tralokinumab 300 mg or matching placebo subcutaneously every 2 weeks or every 4 weeks for 52 weeks. In STRATOS 2, participants were randomly assigned (1:1) to receive tralokinumab 300 mg or matching placebo subcutaneously every 2 weeks for 52 weeks. STRATOS 1 attempted to identify a biomarker-positive population with enhanced tralokinumab benefit, which was then tested in STRATOS 2. The primary endpoint was the annualised asthma exacerbation rate (AAER) reduction at week 52 in the all-comers population for STRATOS 1 and in the biomarker-positive population for STRATOS 2. All efficacy analyses for both trials were done on the full analysis set by an intention-to-treat approach. The safety analysis set comprised any participant who received the investigational drug and was categorised by treatment received. These trials are registered with ClinicalTrials.gov, numbers NCT02161757 (STRATOS 1) and NCT02194699 (STRATOS 2), and with the EU Clinical Trials Register, EudraCT 2013-005614-35 (STRATOS 1) and EudraCT 2013-005615-27 (STRATOS 2).

FINDINGS

STRATOS 1 was done between June 13, 2014, and Feb 28, 2017. 1207 participants were randomly assigned and 1202 treated as follows: tralokinumab every 2 weeks (n=398), tralokinumab every 4 weeks (n=404), or placebo (n=400). STRATOS 2 was done between Oct 30, 2014, and Sept 21, 2017. 856 participants were randomly assigned and 849 treated as follows: tralokinumab every 2 weeks (n=427) and placebo every 2 weeks (n=422). In the STRATOS 1 all-comers population, tralokinumab every 2 weeks did not significantly reduce AAER compared with placebo (7·0% reduction [95% CI -20·8 to 28·4]; rate ratio 0·93 [95% CI 0·72 to 1·21]; p=0·59). Baseline fractional exhaled nitric oxide (FENO) 37 ppb or greater was identified as the preferred biomarker in STRATOS 1; in FENO-high participants, tralokinumab every 2 weeks (n=97) reduced AAER by 44·0% (95% CI 6·0 to 66·0; rate ratio 0·56 [95% CI 0·34 to 0·94]; p=0·028) compared with placebo (n=102). In the STRATOS 2 FENO-high population, tralokinumab every 2 weeks (n=108) did not significantly improve AAER (15·8% reduction [95% CI -33·7 to 47·0]; rate ratio 0·84 [95% CI 0·53 to 1·34]; p=0·47) compared with placebo (n=121). The safety profile was consistent with that of previous tralokinumab trials.

INTERPRETATION

Tralokinumab reduced AAER in participants with severe asthma with baseline FENO 37 ppb or higher in STRATOS 1, but not in STRATOS 2. These inconsistent effects on AAER do not support a key role for interleukin 13 in severe asthma exacerbations.

FUNDING

AstraZeneca.

The Mfge8-α8β1-PTEN pathway regulates airway smooth muscle contraction in allergic inflammation

Asthma affects ∼300 million people worldwide. Despite multiple treatment options, asthma treatment remains unsatisfactory in a subset of patients. Airway obstruction is a hallmark of allergic asthma and is largely due to airway smooth muscle hypercontractility induced by airway inflammation. Identification of molecular pathways that regulate airway smooth muscle hypercontractility is of considerable therapeutic interest. We previously identified roles for milk fat globule epidermal growth factor-like 8 (Mfge8) in opposing the effects of allergic inflammation on increasing airway smooth muscle contractile force. In this study, we delineate the signaling pathway by which Mfge8 mediates these effects. By using genetic and pharmacologic approaches, we show that the α8β1 integrin and the phosphatase and tensin homolog (PTEN) mediate the effects of Mfge8 on preventing IL-13-induced increases in airway contractility. Tracheal rings from mice with smooth muscle-specific deletion of α8β1 or PTEN have enhanced contraction in response to treatment with IL-13. Enhanced IL-13-induced tracheal ring contraction in Mfge8-/- mice was abolished by treatment with the PI3K inhibitor. Mechanistically, IL-13 induces ubiquitination and degradation of PTEN protein. Our findings identify a role for the Mfge8-α8β1-PTEN pathway in regulating the force of airway smooth muscle contraction in the setting of allergic inflammation.-Khalifeh-Soltani, A., Gupta, D., Ha, A., Podolsky, M. J., Datta, R., Atabai, K. The Mfge8-α8β1-PTEN pathway regulates airway smooth muscle contraction in allergic inflammation.

Tralokinumab for the treatment of severe, uncontrolled asthma: the ATMOSPHERE clinical development program

Tralokinumab, a fully human IgG₄ monoclonal antibody, specifically neutralizes IL-13. The ATMOSPHERE clinical development program comprised four randomized, placebo-controlled clinical trials and an open-label study that aimed to assess the efficacy and safety of tralokinumab for the treatment of severe, uncontrolled asthma. The two pivotal trials (STRATOS 1 and STRATOS 2; NCT02161757 and NCT02194699) evaluated the efficacy and safety of tralokinumab, with STRATOS 1 identifying a subgroup most likely to demonstrate enhanced response to treatment. Further trials have assessed the ability of tralokinumab to reduce oral corticosteroid use (TROPOS; NCT02281357) and determined its mechanistic effects (MESOS; NCT02449473). An open-label study in Japanese individuals (NCT02902809) assessed the long-term safety and tolerability of tralokinumab in this population.