Interferon-epsilon is a novel regulator of NK cell responses in the uterus

The uterus is a unique mucosal site where immune responses are balanced to be permissive of a fetus, yet protective against infections. Regulation of natural killer (NK) cell responses in the uterus during infection is critical, yet no studies have identified uterine-specific factors that control NK cell responses in this immune-privileged site. We show that the constitutive expression of IFNε in the uterus plays a crucial role in promoting the accumulation, activation, and IFNγ production of NK cells in uterine tissue during Chlamydia infection. Uterine epithelial IFNε primes NK cell responses indirectly by increasing IL-15 production by local immune cells and directly by promoting the accumulation of a pre-pro-like NK cell progenitor population and activation of NK cells in the uterus. These findings demonstrate the unique features of this uterine-specific type I IFN and the mechanisms that underpin its major role in orchestrating innate immune cell protection against uterine infection.

TACTICS VR Stroke Telehealth Virtual Reality Training for Health Care Professionals Involved in Stroke Management at Telestroke Spoke Hospitals: Module Design and Implementation Study

BACKGROUND

Stroke management in rural areas is more variable and there is less access to reperfusion therapies, when compared with metropolitan areas. Delays in treatment contribute to worse patient outcomes. To improve stroke management in rural areas, health districts are implementing telestroke networks. The New South Wales Telestroke Service provides neurologist-led telehealth to 23 rural spoke hospitals aiming to improve treatment delivery and patient outcomes. The training of clinical staff was identified as a critical aspect for the successful implementation of this service. Virtual reality (VR) training has not previously been used in this context.

OBJECTIVE

We sought to develop an evidence-based VR training module specifically tailored for stroke telehealth. During implementation, we aimed to assess the feasibility of workplace deployment and collected feedback from spoke hospital staff involved in stroke management on training acceptability and usability as well as perceived training impact.

METHODS

The TACTICS VR Stroke Telehealth application was developed with subject matter experts. During implementation, both quantitative and qualitative data were documented, including VR use and survey feedback. VR hardware was deployed to 23 rural hospitals, and use data were captured via automated Wi-Fi transfer. At 7 hospitals in a single local health district, staff using TACTICS VR were invited to complete surveys before and after training.

RESULTS

TACTICS VR Stroke Telehealth was deployed to rural New South Wales hospitals starting on April 14, 2021. Through August 20, 2023, a total of 177 VR sessions were completed. Survey respondents (n=20) indicated a high level of acceptability, usability, and perceived training impact (eg, accuracy and knowledge transfer; mean scores 3.8-4.4; 5=strongly agree). Furthermore, respondents agreed that TACTICS VR increased confidence (13/18, 72%), improved understanding (16/18, 89%), and improved awareness (17/18, 94%) regarding stroke telehealth. A comparison of matched pre- and posttraining responses revealed that training improved the understanding of telehealth workflow practices (after training: mean 4.2, SD 0.6; before training: mean 3.2, SD 0.9; P<.001), knowledge on accessing stroke telehealth (mean 4.1, SD 0.6 vs mean 3.1, SD 1.0; P=.001), the awareness of stroke telehealth (mean 4.1, SD 0.6 vs mean 3.4, SD 0.9; P=.03), ability to optimally communicate with colleagues (mean 4.2, SD 0.6 vs mean 3.7, SD 0.9; P=.02), and ability to make improvements (mean 4.0, SD 0.6 vs mean 3.5, SD 0.9; P=.03). Remote training and deployment were feasible, and limited issues were identified, although uptake varied widely (0-66 sessions/site).

CONCLUSIONS

TACTICS VR Stroke Telehealth is a new VR application specifically tailored for stroke telehealth workflow training at spoke hospitals. Training was considered acceptable, usable, and useful and had positive perceived training impacts in a real-world clinical implementation context. Additional work is required to optimize training uptake and integrate training into existing education pathways.

Upper Respiratory Tract OC43 Infection Model for Investigating Airway Immune-Modifying Therapies

Respiratory virus infections initiate and transmit from the upper respiratory tract (URT). Coronaviruses, including OC43, are a major cause of respiratory infection and disease. Failure to mount an effective antiviral immune response in the nasal mucosa increases the risk of severe disease and person-to-person transmission, highlighting the need for URT infection models to support the development of nasal treatments that improve coronavirus antiviral immunity. We aimed to determine if OC43 productively infected the mouse URT and would therefore be a suitable model to assess the efficacy and mechanism of action of nasal-targeting immune-modifying treatments. We administered OC43 via intranasal inoculation to wild-type Balb/c mice and assessed virus airway tropism (by comparing total respiratory tract vs. URT-only virus exposure) and characterized infection-induced immunity by quantifying specific antiviral cytokines and performing gene array assessment of immune genes. We then assessed the effect of immune-modulating therapies, including an immune-stimulating TLR2/6 agonist (INNA-X) and the immune-suppressing corticosteroid fluticasone propionate (FP). OC43 replicated in nasal respiratory epithelial cells, with peak viral RNA observed 2 days after infection. Prophylactic treatment with INNA-X accelerated expression of virus-induced IFN-λ and IFN-stimulated genes. In contrast, intranasal FP treatment increased nasal viral load by 2.4 fold and inhibited virus-induced IFN and IFN-stimulated gene expression. Prior INNA-X treatment reduced the immune-suppressive effect of FP. We demonstrate that the mouse nasal epithelium is permissive to OC43 infection and strengthen the evidence that TLR2 activation is a β-coronavirus innate immune determinant and therapeutic target.

Correction: Evaluation of a Virtual Reality Platform to Train Stress Management Skills for a Defense Workforce: Multisite, Mixed Methods Feasibility Study

[This corrects the article DOI: 10.2196/46368.].

Evaluation of a Virtual Reality Platform to Train Stress Management Skills for a Defense Workforce: Multisite, Mixed Methods Feasibility Study

BACKGROUND

Psychological stress-related injuries within first-responder organizations have created a need for the implementation of effective stress management training. Most stress management training solutions have limitations associated with scaled adoption within the workforce. For instance, those that are effective in civilian populations often do not align with the human performance culture embedded within first-responder organizations. Programs involving expert-led instructions that are high in quality are often expensive.

OBJECTIVE

This study sought to evaluate a tailored stress management training platform within the existing training schedule of the Australian Defense Force (ADF). The platform, known as Performance Edge (PE), is a novel virtual reality (VR) and biofeedback-enabled stress management skills training platform. Focusing on practical training of well-established skills and strategies, the platform was designed to take advantage of VR technology to generate an immersive and private training environment. This study aimed to assess the feasibility of delivering the VR platform within the existing group-based training context and intended training population. In this setting, the study further aimed to collect data on critical predictors of user acceptance and technology adoption in education, including perceived usability, usefulness, and engagement, while also assessing training impacts.

METHODS

This study used a mixed methods, multisite approach to collect observational, self-reported, and biometric data from both training staff and trainers within a real-world "on-base" training context in the ADF. Validated scales include the Presence Questionnaire and User Engagement Scale for perceived usefulness, usability, and engagement, as well as the State Mindfulness Scale and Relaxation Inventory, to gain insights into immediate training impacts for specific training modules. Additional surveys were specifically developed to assess implementation feedback, intention to use skills, and perceived training impact and value.

RESULTS

PE training was delivered to 189 ADF trainees over 372 training sessions. The platform was easy to use at an individual level and was feasible to deliver in a classroom setting. Trainee feedback consistently showed high levels of engagement and a sense of presence with the training content and environment. PE is overall perceived as an effective and useful training tool. Self-report and objective indices confirmed knowledge improvement, increased skill confidence, and increased competency after training. Specific training elements resulted in increased state mindfulness, increased physical relaxation, and reduced breathing rate. The ability to practice cognitive strategies in a diverse, private, and immersive training environment while in a group setting was highlighted as particularly valuable.

CONCLUSIONS

This study found the VR-based platform (PE) to be a feasible stress management training solution for group-based training delivery in a defense population. Furthermore, the intended end users, both trainers and trainees, perceive the platform to be usable, useful, engaging, and effective for training, suggesting end-user acceptance and potential for technology adoption.

Comparing approaches for selection, development, and deployment of extended reality (XR) teaching applications: A case study at The University of Newcastle Australia

The use of extended reality (XR) technology in education offers many advantages for transferring knowledge and practical skills training at the higher education level. As a result, many Universities over the past 5 + years have undertaken pilot programs to both develop XR content and assess how to best implement it within existing teaching and learning systems. Unfortunately, very few of these efforts have included structured evaluation or documentation. As such, limited published evidence exists to inform processes and approaches that may assist or hinder broad scale implementation. This leads many Universities to unnecessarily commit significant time and resources to testing identical or similar approaches, resulting in repeated identification of the same or similar challenges. In response to this situation, The University of Newcastle, Australia decided to systematically document the approach for selection, development and implementation of four new virtual-reality (VR) teaching applications. The current paper contains a detailed intrinsic case study, outlining the process and critical elements that shaped the selection of suitable teaching content, software development, hardware solutions and implementation. Details are provided on how decisions were made, what components were considered helpful, challenges identified, and important lessons outlined. These findings will be useful to organisations and individuals as they look to develop pathways and processes to integrate XR technology, particularly within their existing training and educational frameworks.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10639-022-11364-2.

Toll-like receptor-agonist-based therapies for respiratory viral diseases: thinking outside the cell

Respiratory virus infections initiate in the upper respiratory tract (URT). Innate immunity is critical for initial control of infection at this site, particularly in the absence of mucosal virus-neutralising antibodies. If the innate immune response is inadequate, infection can spread to the lower respiratory tract (LRT) causing community-acquired pneumonia (as exemplified by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)/coronavirus disease 2019). Vaccines for respiratory viruses (influenza and SARS-CoV-2) leverage systemic adaptive immunity to protect from severe lung disease. However, the URT remains vulnerable to infection, enabling viral transmission and posing an ongoing risk of severe disease in populations that lack effective adaptive immunity.

Innate immunity is triggered by host cell recognition of viral pathogen-associated molecular patterns via molecular sensors such as Toll-like receptors (TLRs). Here we review the role of TLRs in respiratory viral infections and the potential of TLR-targeted treatments to enhance airway antiviral immunity to limit progression to severe LRT disease and reduce person-to-person viral transmission. By considering cellular localisation and antiviral mechanisms of action and treatment route/timing, we propose that cell surface TLR agonist therapies are a viable strategy for preventing respiratory viral diseases by providing immediate, durable pan-viral protection within the URT.

Respiratory virus infections are a significant disease burden and new treatment options are required. Treatments that stimulate innate immunity in the upper respiratory tract by targeting Toll-like receptors may provide rapid, pan-viral protection.https://bit.ly/3BNH2Em

TACTICS - Trial of Advanced CT Imaging and Combined Education Support for Drip and Ship: evaluating the effectiveness of an 'implementation intervention' in providing better patient access to reperfusion therapies: protocol for a non-randomised controlled stepped wedge cluster trial in acute stroke

INTRODUCTION

Stroke reperfusion therapies, comprising intravenous thrombolysis (IVT) and/or endovascular thrombectomy (EVT), are best practice treatments for eligible acute ischemic stroke patients. In Australia, EVT is provided at few, mainly metropolitan, comprehensive stroke centres (CSC). There are significant challenges for Australia's rural and remote populations in accessing EVT, but improved access can be facilitated by a 'drip and ship' approach. TACTICS (Trial of Advanced CT Imaging and Combined Education Support for Drip and Ship) aims to test whether a multicomponent, multidisciplinary implementation intervention can increase the proportion of stroke patients receiving EVT.

METHODS AND ANALYSIS

This is a non-randomised controlled, stepped wedge trial involving six clusters across three Australian states. Each cluster comprises one CSC hub and a minimum of three primary stroke centre (PSC) spokes. Hospitals will work in a hub and spoke model of care with access to a multislice CT scanner and CT perfusion image processing software (MIStar, Apollo Medical Imaging). The intervention, underpinned by behavioural theory and technical assistance, will be allocated sequentially, and clusters will move from the preintervention (control) period to the postintervention period.

PRIMARY OUTCOME

Proportion of all stroke patients receiving EVT, accounting for clustering.

SECONDARY OUTCOMES

Proportion of patients receiving IVT at PSCs, proportion of treated patients (IVT and/or EVT) with good (modified Rankin Scale (mRS) score 0-2) or poor (mRS score 5-6) functional outcomes and European Quality of Life Scale scores 3 months postintervention, proportion of EVT-treated patients with symptomatic haemorrhage, and proportion of reperfusion therapy-treated patients with good versus poor outcome who presented with large vessel occlusion at spokes.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the Hunter New England Human Research Ethics Committee (18/09/19/4.13, HREC/18/HNE/241, 2019/ETH01238). Trial results will be disseminated widely through published manuscripts, conference presentations and at national and international platforms regardless of whether the trial was positive or neutral.

TRIAL REGISTRATION NUMBER

ACTRN12619000750189; UTNU1111-1230-4161.

Development and Pilot Implementation of TACTICS VR: A Virtual Reality-Based Stroke Management Workflow Training Application and Training Framework

Delays in acute stroke treatment contribute to severe and negative impacts for patients and significant healthcare costs. Variability in clinical care is a contributor to delayed treatment, particularly in rural, regional and remote (RRR) areas. Targeted approaches to improve stroke workflow processes improve outcomes, but numerous challenges exist particularly in RRR settings. Virtual reality (VR) applications can provide immersive and engaging training and overcome some existing training barriers. We recently initiated the TACTICS trial, which is assessing a "package intervention" to support advanced CT imaging and streamlined stroke workflow training. As part of the educational component of the intervention we developed TACTICS VR, a novel VR-based training application to upskill healthcare professionals in optimal stroke workflow processes. In the current manuscript, we describe development of the TACTICS VR platform which includes the VR-based training application, a user-facing website and an automated back-end data analytics portal. TACTICS VR was developed via an extensive and structured scoping and consultation process, to ensure content was evidence-based, represented best-practice and is tailored for the target audience. Further, we report on pilot implementation in 7 Australian hospitals to assess the feasibility of workplace-based VR training. A total of 104 healthcare professionals completed TACTICS VR training. Users indicated a high level of usability, acceptability and utility of TACTICS VR, including aspects of hardware, software design, educational content, training feedback and implementation strategy. Further, users self-reported increased confidence in their ability to make improvements in stroke management after TACTICS VR training (post-training mean ± SD = 4.1 ± 0.6; pre-training = 3.6 ± 0.9; 1 = strongly disagree, 5 = strongly agree). Very few technical issues were identified, supporting the feasibility of this training approach. Thus, we propose that TACTICS VR is a fit-for-purpose, evidence-based training application for stroke workflow optimisation that can be readily deployed on-site in a clinical setting.

T-helper 22 cells develop as a distinct lineage from Th17 cells during bacterial infection and phenotypic stability is regulated by T-bet

CD4+ T-helper 22 (Th22) cells are a phenotypically distinct lymphocyte subset that produces high levels of interleukin (IL)-22 without co-production of IL-17A. However, the developmental origin and lineage classification of Th22 cells, their interrelationship to Th17 cells, and potential for plasticity at sites of infection and inflammation remain largely undefined. An improved understanding of the mechanisms underpinning the outgrowth of Th22 cells will provide insights into their regulation during homeostasis, infection, and disease. To address this knowledge gap we generated 'IL-17A-fate-mapping IL-17A/IL-22 reporter transgenic mice' and show that Th22 cells develop in the gastrointestinal tract and lung during bacterial infection without transitioning via an Il17a-expressing intermediate, although in some compartments alternative transition pathways exist. Th22-cell development was not dependent on T-bet; however, this transcription factor functioned as a promiscuous T-cell-intrinsic regulator of IL-17A and IL-22 production, in addition to regulating the outgrowth, phenotypic stability, and plasticity of Th22 cells. Thus, we demonstrate that at sites of mucosal bacterial infection Th22 cells develop as a distinct lineage independently of Th17 cells; though both lineages exhibit bidirectional phenotypic flexibility within infected tissues and their draining lymph nodes, and that T-bet plays a critical regulatory role in Th22-cell function and identity.

TLR2-mediated innate immune priming boosts lung anti-viral immunity

BACKGROUND

We assessed whether Toll-like receptor (TLR)2 activation boosts the innate immune response to rhinovirus infection, as a treatment strategy for virus-induced respiratory diseases.

METHODS

We employed treatment with a novel TLR2 agonist (INNA-X) prior to rhinovirus infection in mice, and INNA-X treatment in differentiated human bronchial epithelial cells derived from asthmatic-donors. We assessed viral load, immune cell recruitment, cytokines, type I and III interferon (IFN) production, as well as the lung tissue and epithelial cell immune transcriptome.

RESULTS

We show, in vivo, that a single INNA-X treatment induced innate immune priming characterised by low-level IFN-λ, Fas ligand, chemokine expression and airway lymphocyte recruitment. Treatment 7 days before infection significantly reduced lung viral load, increased IFN-β/λ expression and inhibited neutrophilic inflammation. Corticosteroid treatment enhanced the anti-inflammatory effects of INNA-X. Treatment 1 day before infection increased expression of 190 lung tissue immune genes. This tissue gene expression signature was absent with INNA-X treatment 7 days before infection, suggesting an alternate mechanism, potentially via establishment of immune cell-mediated mucosal innate immunity. In vitro, INNA-X treatment induced a priming response defined by upregulated IFN-λ, chemokine and anti-microbial gene expression that preceded an accelerated response to infection enriched for nuclear factor (NF)-κB-regulated genes and reduced viral loads, even in epithelial cells derived from asthmatic donors with intrinsic delayed anti-viral immune response.

CONCLUSION

Airway epithelial cell TLR2 activation induces prolonged innate immune priming, defined by early NF-κB activation, IFN-λ expression and lymphocyte recruitment. This response enhanced anti-viral innate immunity and reduced virus-induced airway inflammation.

Severe asthma assessment, management and the organisation of care in Australia and New Zealand: expert forum roundtable meetings

Severe asthma imposes a significant burden on individuals, families and the healthcare system. Treatment is complex, due to disease heterogeneity, comorbidities and complexity in care pathways. New approaches and treatments improve health outcomes for people with severe asthma. However, emerging multidimensional and targeted treatment strategies require a reorganisation of asthma care. Consensus is required on how reorganisation should occur and what areas require further research. The Centre of Excellence in Severe Asthma convened three forums between 2015 and 2018, hosting experts from Australia, New Zealand and the UK. The forums were complemented by a survey of clinicians involved in the management of people with severe asthma. We sought to: (i) identify areas of consensus among experts; (ii) define activities and resources required for the implementation of findings into practice; and (iii) identify specific priority areas for future research. Discussions identified areas of unmet need including assessment and diagnosis of severe asthma, models of care and treatment pathways, add-on treatment approaches and patient perspectives. We recommend development of education and training activities, clinical resources and standards of care documents, increased stakeholder engagement and public awareness campaigns and improved access to infrastructure and funding. Further, we propose specific future research to inform clinical decision-making and develop novel therapies. A concerted effort is required from all stakeholders (including patients, healthcare professionals and organisations and government) to integrate new evidence-based practices into clinical care and to advance research to resolve questions relevant to improving outcomes for people with severe asthma.

Rhinovirus-induced CCL17 and CCL22 in Asthma Exacerbations and Differential Regulation by STAT6

The interplay of type-2 inflammation and antiviral immunity underpins asthma exacerbation pathogenesis. Virus infection induces type-2 inflammation-promoting chemokines CCL17 and CCL22 in asthma; however, mechanisms regulating induction are poorly understood. By using a human rhinovirus (RV) challenge model in human airway epithelial cells in vitro and mice in vivo, we assessed mechanisms regulating CCL17 and CCL22 expression. Subjects with mild to moderate asthma and healthy volunteers were experimentally infected with RV and airway CCL17 and CCL22 protein quantified. In vitro airway epithelial cell- and mouse-RV infection models were then used to define STAT6- and NF-κB-mediated regulation of CCL17 and CCL22 expression. Following RV infection, CCL17 and CCL22 expression was higher in asthma, which differentially correlated with clinical and immunological parameters. Air-liquid interface-differentiated primary epithelial cells from donors with asthma also expressed higher levels of RV-induced CCL22. RV infection boosted type-2 cytokine-induced STAT6 activation. In epithelial cells, type-2 cytokines and STAT6 activation had differential effects on chemokine expression, increasing CCL17 and suppressing CCL22, whereas NF-κB promoted expression of both chemokines. In mice, RV infection activated pulmonary STAT6, which was required for CCL17 but not CCL22 expression. STAT6-knockout mice infected with RV expressed increased levels of NF-κB-regulated chemokines, which was associated with rapid viral clearance. Therefore, RV-induced upregulation of CCL17 and CCL22 was mediated by NF-κB activation, whereas expression was differentially regulated by STAT6. Together, these findings suggest that therapeutic targeting of type-2 STAT6 activation alone will not block all inflammatory pathways during RV infection in asthma.

Development of a modular stress management platform (Performance Edge VR) and a pilot efficacy trial of a bio-feedback enhanced training module for controlled breathing

This paper describes the conceptual design of a virtual reality-based stress management training tool and evaluation of the initial prototype in a pilot efficacy study. Performance Edge virtual-reality (VR) was co-developed with the Australian Defence Force (ADF) to address the need for practical stress management training for ADF personnel. The VR application is biofeedback-enabled and contains key stress management techniques derived from acceptance and commitment and cognitive behavioural therapy in a modular framework. End-user-provided feedback on usability, design, and user experience was positive, and particularly complimentary of the respiratory biofeedback functionality. Training of controlled breathing delivered across 3 sessions increased participants' self-reported use of breath control in everyday life and progressively improved controlled breathing skills (objectively assessed as a reduction in breathing rate and variability). Thus the data show that a biofeedback-enabled controlled breathing protocol delivered through Performance Edge VR can produce both behaviour change and objective improvement in breathing metrics. These results confirm the validity of Performance Edge VR platform, and its Controlled Breathing module, as a novel approach to tailoring VR-based applications to train stress management skills in a workplace setting.

Airway Epithelial Cell Immunity Is Delayed During Rhinovirus Infection in Asthma and COPD

Respiratory viral infections, particularly those caused by rhinovirus, exacerbate chronic respiratory inflammatory diseases, such as asthma and chronic obstructive pulmonary disease (COPD). Airway epithelial cells are the primary site of rhinovirus replication and responsible of initiating the host immune response to infection. Numerous studies have reported that the anti-viral innate immune response (including type I and type III interferon) in asthma is less effective or deficient leading to the conclusion that epithelial innate immunity is a key determinant of disease severity during a rhinovirus induced exacerbation. However, deficient rhinovirus-induced epithelial interferon production in asthma has not always been observed. We hypothesized that disparate in vitro airway epithelial infection models using high multiplicity of infection (MOI) and lacking genome-wide, time course analyses have obscured the role of epithelial innate anti-viral immunity in asthma and COPD. To address this, we developed a low MOI rhinovirus model of differentiated primary epithelial cells obtained from healthy, asthma and COPD donors. Using genome-wide gene expression following infection, we demonstrated that gene expression patterns are similar across patient groups, but that the kinetics of induction are delayed in cells obtained from asthma and COPD donors. Rhinovirus-induced innate immune responses were defined by interferons (type-I, II, and III), interferon response factors (IRF1, IRF3, and IRF7), TLR signaling and NF-κB and STAT1 activation. Induced gene expression was evident at 24 h and peaked at 48 h post-infection in cells from healthy subjects. In contrast, in cells from donors with asthma or COPD induction was maximal at or beyond 72–96 h post-infection. Thus, we propose that propensity for viral exacerbations of asthma and COPD relate to delayed (rather than deficient) expression of epithelial cell innate anti-viral immune genes which in turns leads to a delayed and ultimately more inflammatory host immune response.

Severe Asthma Toolkit: an online resource for multidisciplinary health professionals-needs assessment, development process and user analytics with survey feedback

OBJECTIVES

Severe asthma imposes a significant burden on individuals, families and the healthcare system. New treatment and management approaches are emerging as effective options for severe asthma. Translating new knowledge to multidisciplinary healthcare professionals is a priority. We developed 'The Severe Asthma Toolkit' (https://toolkit.severeasthma.org.au) to increase awareness of severe asthma, provide evidence-based resources and support decisionmaking by healthcare providers.

SETTING

Roundtable discussions and a survey of Australians clinicians were conducted to determine clinician preferences, format and content for a severe asthma resource.

PARTICIPANTS

A reference group from stakeholder and consumer bodies and severe asthma experts provided advice and feedback. A multidisciplinary team of international experts was engaged to develop content. Written content was based on up-to-date literature. Peer and editorial review were performed to finalise content and inform web design. Website design focused on user experience, navigation, engagement, interactivity and tailoring of content for a clinical audience.

RESULTS

A web-based resource was developed. Roundtable discussions and a needs assessment survey identified the need for dedicated severe asthma management resources to support skills training. The end-product, which launched 26 March 2018, includes an overview of severe asthma, diagnosis and assessment, management, medications, comorbidities, living with severe asthma, establishing a clinic, paediatrics/adolescents and clinical resources. Analytics indicate access by users worldwide (32 169 users from 169 countries). User survey results (n=394) confirm access by the target audience (72% health professionals), who agreed the toolkit increased their knowledge (73%) and confidence in managing severe asthma (66%), and 75% are likely to use the resource in clinic.

CONCLUSIONS

The Severe Asthma Toolkit is a unique, evidence-based internet resource to support healthcare professionals providing optimal care for people with severe asthma. It is a comprehensive, accessible and independent resource developed by leading severe asthma experts to improve clinician knowledge and skills in severe asthma management.

Lipopolysaccharide induces steroid-resistant exacerbations in a mouse model of allergic airway disease collectively through IL-13 and pulmonary macrophage activation

BACKGROUND

Acute exacerbations of asthma represent a major burden of disease and are often caused by respiratory infections. Viral infections are recognized as significant triggers of exacerbations; however, less is understood about the how microbial bioproducts such as the endotoxin (lipopolysaccharide (LPS)) trigger episodes. Indeed, increased levels of LPS have been linked to asthma onset, severity and steroid resistance.

OBJECTIVE

The goal of this study was to identify mechanisms underlying bacterial-induced exacerbations by employing LPS as a surrogate for infection.

METHODS

We developed a mouse model of LPS-induced exacerbation on the background of pre-existing type-2 allergic airway disease (AAD).

RESULTS

LPS-induced exacerbation was characterized by steroid-resistant airway hyperresponsiveness (AHR) and an exaggerated inflammatory response distinguished by increased numbers of infiltrating neutrophils/macrophages and elevated production of lung inflammatory cytokines, including TNFα, IFNγ, IL-27 and MCP-1. Expression of the type-2 associated inflammatory factors such as IL-5 and IL-13 were elevated in AAD but not altered by LPS exposure. Furthermore, AHR and airway inflammation were no longer suppressed by corticosteroid (dexamethasone) treatment after LPS exposure. Depletion of pulmonary macrophages by administration of 2-chloroadenosine into the lungs suppressed AHR and reduced IL-13, TNFα and IFNγ expression. Blocking IL-13 function, through either IL-13-deficiency or administration of specific blocking antibodies, also suppressed AHR and airway inflammation.

CONCLUSIONS & CLINICAL RELEVANCE

We present evidence that IL-13 and innate immune pathways (in particular pulmonary macrophages) contribute to LPS-induced exacerbation of pre-existing AAD and provide insight into the complex molecular processes potentially underlying microbial-induced exacerbations.

Platelet activating factor receptor regulates colitis-induced pulmonary inflammation through the NLRP3 inflammasome

Extra-intestinal manifestations (EIM) are common in inflammatory bowel disease (IBD). One such EIM is sub-clinical pulmonary inflammation, which occurs in up to 50% of IBD patients. In animal models of colitis, pulmonary inflammation is driven by neutrophilic infiltrations, primarily in response to the systemic bacteraemia and increased bacterial load in the lungs. Platelet activating factor receptor (PAFR) plays a critical role in regulating pulmonary responses to infection in conditions, such as chronic obstructive pulmonary disease and asthma. We investigated the role of PAFR in pulmonary EIMs of IBD, using dextran sulfate sodium (DSS) and anti-CD40 murine models of colitis. Both models induced neutrophilic inflammation, with increased TNF and IL-1β levels, bacterial load and PAFR protein expression in mouse lungs. Antagonism of PAFR decreased lung neutrophilia, TNF, and IL-1β in an NLRP3 inflammasome-dependent manner. Lipopolysaccharide from phosphorylcholine (ChoP)-positive bacteria induced NLRP3 and caspase-1 proteins in human alveolar epithelial cells, however antagonism of PAFR prevented NLRP3 activation by ChoP. Amoxicillin reduced bacterial populations in the lungs and reduced NLRP3 inflammasome protein levels, but did not reduce PAFR. These data suggest a role for PAFR in microbial pattern recognition and NLRP3 inflammasome signaling in the lung.

In vivo experimental models of infection and disease

Human and animal models continue to play a crucial role in research to understand host immunity to rhinovirus (RV) and identify disease mechanisms. Human models have provided direct evidence that RV infection is capable of exacerbating chronic respiratory diseases and identified immunological processes that correlate with clinical disease outcomes. Mice are the most commonly used nonhuman experimental RV infection model. Although semipermissive, under defined experimental conditions sufficient replication occurs to induce host immune responses that recapitulate immunity and disease during human infection. The capacity to use genetically modified mouse strains and drug interventions has shown the mouse model to be an invaluable research tool defining causal relationships between host immunity and disease and supporting development of new treatments. Used in combination the insights achieved from human and animal experimental infection models provide complementary insights into RV biology and yield novel therapeutic options to reduce the burden of RV-induced disease.

Modeling TH 2 responses and airway inflammation to understand fundamental mechanisms regulating the pathogenesis of asthma

In this review, we highlight experiments conducted in our laboratories that have elucidated functional roles for CD4⁺ T-helper type-2 lymphocytes (T_H 2 cells), their associated cytokines, and eosinophils in the regulation of hallmark features of allergic asthma. Notably, we consider the complexity of type-2 responses and studies that have explored integrated signaling among classical T_H 2 cytokines (IL-4, IL-5, and IL-13), which together with CCL11 (eotaxin-1) regulate critical aspects of eosinophil recruitment, allergic inflammation, and airway hyper-responsiveness (AHR). Among our most important findings, we have provided evidence that the initiation of T_H 2 responses is regulated by airway epithelial cell-derived factors, including TRAIL and MID1, which promote T_H 2 cell development via STAT6-dependent pathways. Further, we highlight studies demonstrating that microRNAs are key regulators of allergic inflammation and potential targets for anti-inflammatory therapy. On the background of T_H 2 inflammation, we have demonstrated that innate immune cells (notably, airway macrophages) play essential roles in the generation of steroid-resistant inflammation and AHR secondary to allergen- and pathogen-induced exacerbations. Our work clearly indicates that understanding the diversity and spatiotemporal role of the inflammatory response and its interactions with resident airway cells is critical to advancing knowledge on asthma pathogenesis and the development of new therapeutic approaches.

Advancing the management of obstructive airways diseases through translational research

Obstructive airways diseases (OAD) represent a huge burden of illness world-wide, and in spite of the development of effective therapies, significant morbidity and mortality related to asthma and COPD still remains. Over the past decade, our understanding of OAD has improved vastly, and novel treatments have evolved. This evolution is the result of successful translational research, which has connected clinical presentations of OAD and underlying disease mechanisms, thereby enabling the development of targeted treatments. The next challenge of translational research will be to position these novel treatments for OAD for optimal clinical use. At the same time, there is great potential in these treatments providing even better insights into disease mechanisms in OAD by studying the effects of blocking individual immunological pathways. To optimize this potential, there is a need to ensure that translational aspects are added to randomized clinical trials, as well as real-world studies, but also to use other trial designs such as platform studies, which allow for simultaneous assessment of different interventions. Furthermore, demonstrating clinical impact, that is research translation, is an increasingly important component of successful translational research. This review outlines concepts of translational research, exemplifying how translational research has moved management of obstructive airways diseases into the next century, with the introduction of targeted, individualized therapy. Furthermore, the review describes how these therapies may be used as research tools to further our understanding of disease mechanisms in OAD, through translational, mechanistic studies. We underline the current need for implementing basic immunological concepts into clinical care in order to optimize the use of novel targeted treatments and to further the clinical understanding of disease mechanisms. Finally, potential barriers to adoption of novel targeted therapies into routine practice and how these may be overcome are described.

Osteoblasts Are Rapidly Ablated by Virus-Induced Systemic Inflammation following Lymphocytic Choriomeningitis Virus or Pneumonia Virus of Mice Infection in Mice

A link between inflammatory disease and bone loss is now recognized. However, limited data exist on the impact of virus infection on bone loss and regeneration. Bone loss results from an imbalance in remodeling, the physiological process whereby the skeleton undergoes continual cycles of formation and resorption. The specific molecular and cellular mechanisms linking virus-induced inflammation to bone loss remain unclear. In the current study, we provide evidence that infection of mice with either lymphocytic choriomeningitis virus (LCMV) or pneumonia virus of mice (PVM) resulted in rapid and substantial loss of osteoblasts from the bone surface. Osteoblast ablation was associated with elevated levels of circulating inflammatory cytokines, including TNF-α, IFN-γ, IL-6, and CCL2. Both LCMV and PVM infections resulted in reduced osteoblast-specific gene expression in bone, loss of osteoblasts, and reduced serum markers of bone formation, including osteocalcin and procollagen type 1 N propeptide. Infection of Rag-1-deficient mice (which lack adaptive immune cells) or specific depletion of CD8+ T lymphocytes limited osteoblast loss associated with LCMV infection. By contrast, CD8+ T cell depletion had no apparent impact on osteoblast ablation in association with PVM infection. In summary, our data demonstrate dramatic loss of osteoblasts in response to virus infection and associated systemic inflammation. Further, the inflammatory mechanisms mediating viral infection-induced bone loss depend on the specific inflammatory condition.

Identification of IFN-γ and IL-27 as Critical Regulators of Respiratory Syncytial Virus-Induced Exacerbation of Allergic Airways Disease in a Mouse Model

Respiratory syncytial virus (RSV) infection induces asthma exacerbations, which leads to worsening of clinical symptoms and may result in a sustained decline in lung function. Exacerbations are the main cause of morbidity and mortality associated with asthma, and significantly contribute to asthma-associated healthcare costs. Although glucocorticoids are used to manage exacerbations, some patients respond to them poorly. The underlying mechanisms associated with steroid-resistant exacerbations remain largely unknown. We have previously established a mouse model of RSV-induced exacerbation of allergic airways disease, which mimics hallmark clinical features of asthma. In this study, we have identified key roles for macrophage IFN-γ and IL-27 in the regulation of RSV-induced exacerbation of allergic airways disease. Production of IFN-γ and IL-27 was steroid-resistant, and neutralization of IFN-γ or IL-27 significantly suppressed RSV-induced steroid-resistant airway hyperresponsiveness and airway inflammation. We have previously implicated activation of pulmonary macrophage by TNF-α and/or MCP-1 in the mechanisms of RSV-induced exacerbation. Stimulation of pulmonary macrophages with TNF-α and/or MCP-1 induced expression of both IFN-γ and IL-27. Our findings highlight critical roles for IFN-γ and IL-27, downstream of TNF-α and MCP-1, in the mechanism of RSV-induced exacerbation. Thus, targeting the pathways that these factors activate may be a potential therapeutic approach for virus-induced asthma exacerbations.

Mouse models of severe asthma: Understanding the mechanisms of steroid resistance, tissue remodelling and disease exacerbation

Severe asthma has significant disease burden and results in high healthcare costs. While existing therapies are effective for the majority of asthma patients, treatments for individuals with severe asthma are often ineffective. Mouse models are useful to identify mechanisms underlying disease pathogenesis and for the preclinical assessment of new therapies. In fact, existing mouse models have contributed significantly to our understanding of allergic/eosinophilic phenotypes of asthma and facilitated the development of novel targeted therapies (e.g. anti-IL-5 and anti-IgE). These therapies are effective in relevant subsets of severe asthma patients. Unfortunately, non-allergic/non-eosinophilic asthma, steroid resistance and disease exacerbation remain areas of unmet clinical need. No mouse model encompasses all features of severe asthma. However, mouse models can provide insight into pathogenic pathways that are relevant to severe asthma. In this review, as examples, we highlight models relevant to understanding steroid resistance, chronic tissue remodelling and disease exacerbation. Although these models highlight the complexity of the immune pathways that may underlie severe asthma, they also provide insight into new potential therapeutic approaches.

Th22 Cells Form a Distinct Th Lineage from Th17 Cells In Vitro with Unique Transcriptional Properties and Tbet-Dependent Th1 Plasticity

Th22 cells are a major source of IL-22 and have been found at sites of infection and in a range of inflammatory diseases. However, their molecular characteristics and functional roles remain largely unknown because of our inability to generate and isolate pure populations. We developed a novel Th22 differentiation assay and generated dual IL-22/IL-17A reporter mice to isolate and compare pure populations of cultured Th22 and Th17 cells. Il17a fate-mapping and transcriptional profiling provide evidence that these Th22 cells have never expressed IL-17A, suggesting that they are potentially a distinct cell lineage from Th17 cells under in vitro culture conditions. Interestingly, Th22 cells also expressed granzymes, IL-13, and increased levels of Tbet. Using transcription factor-deficient cells, we demonstrate that RORγt and Tbet act as positive and negative regulators of Th22 differentiation, respectively. Furthermore, under Th1 culture conditions in vitro, as well as in an IFN-γ-rich inflammatory environment in vivo, Th22 cells displayed marked plasticity toward IFN-γ production. Th22 cells also displayed plasticity under Th2 conditions in vitro by upregulating IL-13 expression. Our work has identified conditions to generate and characterize Th22 cells in vitro. Further, it provides evidence that Th22 cells develop independently of the Th17 lineage, while demonstrating plasticity toward both Th1- and Th2-type cells.

Severe asthma: Current management, targeted therapies and future directions-A roundtable report

Asthma is a chronic respiratory disease characterized by respiratory symptoms, airway inflammation, airway obstruction and airway hyper-responsiveness. Asthma is common and directly affects 10% of Australians, 1-5% of adults in Asia and 300 million people worldwide. It is a heterogeneous disorder with many clinical, molecular, biological and pathophysiological phenotypes. Current management strategies successfully treat the majority of patients with asthma who have access to them. However, there is a subset of an estimated 5-10% of patients with asthma who have severe disease and are disproportionately impacted by symptoms, exacerbations and overall illness burden. The care required for this relatively small proportion of patients is also significant and has a major impact on the healthcare system. A number of new therapies that hold promise for severe asthma are currently in clinical trials or are entering the Australian and international market. However, recognition of severe asthma in clinical practice is variable, and there is little consensus on the best models of care or how to integrate emerging and often costly therapies into current practice. In this article, we report on roundtable discussions held with severe asthma experts from around Australia, and make recommendations about approaches for better patient diagnosis and assessment. We assess current models of care for patient management and discuss how approaches may be optimized to improve patient outcomes. Finally, we propose mechanisms to assess new therapies and how to best integrate these approaches into future treatment.

Omalizumab Treatment Response in a Population With Severe Allergic Asthma and Overlapping COPD

BACKGROUND

Asthma and COPD are common airway diseases. Individuals with overlapping asthma and COPD experience increased health impairment and severe disease exacerbations. Efficacious treatment options are required for this population. Omalizumab (anti-IgE) therapy is effective in patients with severe persistent asthma, but limited data are available on efficacy in populations with overlapping asthma and COPD.

METHODS

Data from the Australian Xolair Registry were used to compare treatment responses in individuals with asthma-COPD overlap with responses in patients with severe asthma alone. Participants were assessed at baseline and after 6 months of omalizumab treatment. We used several different definitions of asthma-COPD overlap. First, we compared participants with a previous physician diagnosis of COPD to participants with no COPD diagnosis. We then made comparisons based on baseline lung function, comparing participants with an FEV₁ < 80% predicted to those with an FEV₁ > 80% predicted after bronchodilator use. In the population with an FEV₁< 80%, analysis was further stratified based on smoking history.

RESULTS

Omalizumab treatment markedly improved asthma control and health-related quality of life in all populations assessed based on the Asthma Control Questionnaire and Asthma Quality of Life Questionnaire scores. Omalizumab treatment did not improve lung function (FEV₁, FVC, or FEV₁/FVC ratio) in populations that were enriched for asthma-COPD overlap (diagnosis of COPD or FEV₁ < 80%/ever smokers).

CONCLUSIONS

Our study suggests that omalizumab improves asthma control and health-related quality of life in individuals with severe allergic asthma and overlapping COPD. These findings provide real-world efficacy data for this patient population and suggest that omalizumab is useful in the management of severe asthma with COPD overlap.

Bromodomain and Extra Terminal (BET) Inhibitor Suppresses Macrophage-Driven Steroid-Resistant Exacerbations of Airway Hyper-Responsiveness and Inflammation

BACKGROUND

Exacerbations of asthma are linked to significant decline in lung function and are often poorly controlled by corticosteroid treatment. Clinical investigations indicate that viral and bacterial infections play crucial roles in the onset of steroid-resistant inflammation and airways hyperresponsiveness (AHR) that are hallmark features of exacerbations. We have previously shown that interferon γ (IFNγ) and lipopolysaccharide (LPS) cooperatively activate pulmonary macrophages and induce steroid-resistant airway inflammation and AHR in mouse models. Furthermore, we have established a mouse model of respiratory syncytial virus (RSV)-induced exacerbation of asthma, which exhibits macrophage-dependent, steroid-resistant lung disease. Emerging evidence has demonstrated a key role for bromo- and extra-terminal (BET) proteins in the regulation of inflammatory gene expression in macrophages. We hypothesised that BET proteins may be involved in the regulation of AHR and airway inflammation in our steroid-resistant exacerbation models.

METHODOLOGY/PRINCIPAL FINDINGS

We investigated the effects of a BET inhibitor (I-BET-762) on the development of steroid-resistant AHR and airway inflammation in two mouse models. I-BET-762 administration decreased macrophage and neutrophil infiltration into the airways, and suppressed key inflammatory cytokines in both models. I-BET treatment also suppressed key inflammatory cytokines linked to the development of steroid-resistant inflammation such as monocyte chemoattractant protein 1 (MCP-1), keratinocyte-derived protein chemokine (KC), IFNγ, and interleukin 27 (IL-27). Attenuation of inflammation was associated with suppression of AHR.

CONCLUSIONS/SIGNIFICANCE

Our results suggest that BET proteins play an important role in the regulation of steroid-resistant exacerbations of airway inflammation and AHR. BET proteins may be potential targets for the development of future therapies to treat steroid-resistant inflammatory components of asthma.

TNF-α and Macrophages Are Critical for Respiratory Syncytial Virus-Induced Exacerbations in a Mouse Model of Allergic Airways Disease

Viral respiratory infections trigger severe exacerbations of asthma, worsen disease symptoms, and impair lung function. To investigate the mechanisms underlying viral exacerbation, we established a mouse model of respiratory syncytial virus (RSV)-induced exacerbation after allergen sensitization and challenge. RSV infection of OVA-sensitized/challenged BALB/c mice resulted in significantly increased airway hyperresponsiveness (AHR) and macrophage and neutrophil lung infiltration. Exacerbation was accompanied by increased levels of inflammatory cytokines (including TNF-α, MCP-1, and keratinocyte-derived protein chemokine [KC]) compared with uninfected OVA-treated mice or OVA-treated mice exposed to UV-inactivated RSV. Dexamethasone treatment completely inhibited all features of allergic disease, including AHR and eosinophil infiltration, in uninfected OVA-sensitized/challenged mice. Conversely, dexamethasone treatment following RSV-induced exacerbation only partially suppressed AHR and failed to dampen macrophage and neutrophil infiltration or inflammatory cytokine production (TNF-α, MCP-1, and KC). This mimics clinical observations in patients with exacerbations, which is associated with increased neutrophils and often poorly responds to corticosteroid therapy. Interestingly, we also observed increased TNF-α levels in sputum samples from patients with neutrophilic asthma. Although RSV-induced exacerbation was resistant to steroid treatment, inhibition of TNF-α and MCP-1 function or depletion of macrophages suppressed features of disease, including AHR and macrophage and neutrophil infiltration. Our findings highlight critical roles for macrophages and inflammatory cytokines (including TNF-α and MCP-1) in viral-induced exacerbation of asthma and suggest examination of these pathways as novel therapeutic approaches for disease management.

Diagnosis and investigation in the severe asthma clinic

Severe asthma is recognised as an important and emerging area of unmet need in asthma. The assessment of severe asthma should include three steps; (1) determining the diagnosis of asthma, including verification that the disease is severe asthma, (2) assessing comorbidities and contributing factors that will impact on clinical severity, as well as (3) assessing asthma phenotypes. These steps recognize the importance of heterogeneity in asthma as a key factor that determines the disease course and increasingly the choice of successful therapy. This assessment should be undertaken systematically and is best done by an expert multidisciplinary team. Here, we will outline the important aspects that should be included in the clinical assessment of the patient in the severe asthma clinic, including diagnosis, clinical history, the assessment of important comorbidities and the key investigations needed to support them.

Targeting MicroRNA Function in Respiratory Diseases: Mini-Review

MicroRNAs (miRNAs) are small non-coding RNA molecules that modulate expression of the majority of genes by inhibiting protein translation. Growing literature has identified functional roles for miRNAs across a broad range of biological processes. As such, miRNAs are recognized as potential disease biomarkers and novel targets for therapies. While several miRNA-targeted therapies are currently in clinical trials (e.g., for the treatment of hepatitis C virus infection and cancer), no therapies have targeted miRNAs in respiratory diseases in the clinic. In this mini-review, we review the current knowledge on miRNA expression and function in respiratory diseases, intervention strategies to target miRNA function, and considerations specific to respiratory diseases. Altered miRNA expression profiles have been reported in a number of respiratory diseases, including asthma, chronic obstructive pulmonary disease, cystic fibrosis, and idiopathic pulmonary fibrosis. These include alterations in isolated lung tissue, as well as sputum, bronchoalveolar lavage fluids and peripheral blood or serum. The observed alterations in easily accessible body fluids (e.g., serum) have been proposed as new biomarkers that may inform disease diagnosis and patient management. In a subset of studies, miRNA-targeted interventions also improved disease outcomes, indicating functional roles for altered miRNA expression in disease pathogenesis. In fact, direct administration of miRNA-targeting molecules to the lung has yielded promising results in a number of animal models. The ability to directly administer compounds to the lung holds considerable promise and may limit potential off-target effects and side effects caused by the systemic administration required to treat other diseases.

Potential mechanisms regulating pulmonary pathology in inflammatory bowel disease

Inflammatory bowel disease is associated with a number of comorbidities that arise at extraintestinal sites, including the lung. Pulmonary manifestations reported in inflammatory bowel disease include bronchiectasis, chronic bronchitis and importantly, a range of subclinical respiratory abnormalities that are often overlooked in routine clinical evaluation. Whereas evidence for the pulmonary manifestations of Inflammatory bowel disease is increasing, little is known about the immunologic and physiologic mechanisms regulating cross-talk between the gut and lung during disease. This review examines reported lung involvement in Inflammatory bowel disease and discusses the possible immune pathways that underlie pulmonary pathologies. These mechanisms include dysfunctional immune-cell homing, systemic inflammation, and microbial dysbiosis; all of which may contribute to Inflammatory bowel disease-induced pulmonary inflammation. These mechanisms are discussed in the context of our current knowledge of the shared mucosal immune system and the immunology of Inflammatory bowel disease.

MicroRNA function in mast cell biology: protocols to characterize and modulate microRNA expression

MicroRNAs (miRNAs) are small noncoding RNA molecules that can modulate mRNA levels through RNA-induced silencing complex (RISC)-mediated degradation. Recognition of target mRNAs occurs through imperfect base pairing between an miRNA and its target, meaning that each miRNA can target a number of different mRNAs to modulate gene expression. miRNAs have been proposed as novel therapeutic targets and many studies are aimed at characterizing miRNA expression patterns and functions within a range of cell types. To date, limited research has focused on the function of miRNAs specifically in mast cells; however, this is an emerging field. In this chapter, we will briefly overview miRNA synthesis and function and the current understanding of miRNAs in hematopoietic development and immune function, emphasizing studies related to mast cell biology. The chapter will conclude with fundamental techniques used in miRNA studies, including RNA isolation, real-time PCR and microarray approaches for quantification of miRNA expression levels, and antagomir design to interfere with miRNA function.

Antagonism of miR-328 increases the antimicrobial function of macrophages and neutrophils and rapid clearance of non-typeable Haemophilus influenzae (NTHi) from infected lung

Pathogenic bacterial infections of the lung are life threatening and underpin chronic lung diseases. Current treatments are often ineffective potentially due to increasing antibiotic resistance and impairment of innate immunity by disease processes and steroid therapy. Manipulation miRNA directly regulating anti-microbial machinery of the innate immune system may boost host defence responses. Here we demonstrate that miR-328 is a key element of the host response to pulmonary infection with non-typeable haemophilus influenzae and pharmacological inhibition in mouse and human macrophages augments phagocytosis, the production of reactive oxygen species, and microbicidal activity. Moreover, inhibition of miR-328 in respiratory models of infection, steroid-induced immunosuppression, and smoke-induced emphysema enhances bacterial clearance. Thus, miRNA pathways can be targeted in the lung to enhance host defence against a clinically relevant microbial infection and offer a potential new anti-microbial approach for the treatment of respiratory diseases.

MicroRNAs regulate pathogen recognition pathways by modulating translation. In the immune system, miRNAs have been identified as important regulators of gene expression programs, which regulate differentiation, growth and function of innate and adaptive immune cells. Using miRNA microarray, we demonstrated that lung miRNAs were differentially expressed following non-typeable Haemophilus Influenzae (NTHi) infection in mice. To study the role of a specific miRNA in macrophages, we used antagomir (chemically modified single-stranded RNA analogues, complementary to the target miRNA) to block miRNA function. Interestingly, inhibition of microRNA-328 in mouse and human macrophages increases microbicidal activity by amplifying phagocytosis and production of reactive oxygen species. Inhibition of mR-328 in the lung enhanced bacterial clearance in mouse models of immunosuppression and emphysema. Our study provides proof of principle that miRNA pathways can be targeted in the lung and offer a potential new anti-microbial approach for the treatment of respiratory infection.

Production and differentiation of myeloid cells driven by proinflammatory cytokines in response to acute pneumovirus infection in mice

Respiratory virus infections are often pathogenic, driving severe inflammatory responses. Most research has focused on localized effects of virus infection and inflammation. However, infection can induce broad-reaching, systemic changes that are only beginning to be characterized. In this study, we assessed the impact of acute pneumovirus infection in C57BL/6 mice on bone marrow hematopoiesis. We hypothesized that inflammatory cytokine production in the lung upregulates myeloid cell production in response to infection. We demonstrate a dramatic increase in the percentages of circulating myeloid cells, which is associated with pronounced elevations in inflammatory cytokines in serum (IFN-γ, IL-6, CCL2), bone (TNF-α), and lung tissue (TNF-α, IFN-γ, IL-6, CCL2, CCL3, G-CSF, osteopontin). Increased hematopoietic stem/progenitor cell percentages (Lineage(-)Sca-I(+)c-kit(+)) were also detected in the bone marrow. This increase was accompanied by an increase in the proportions of committed myeloid progenitors, as determined by colony-forming unit assays. However, no functional changes in hematopoietic stem cells occurred, as assessed by competitive bone marrow reconstitution. Systemic administration of neutralizing Abs to either TNF-α or IFN-γ blocked expansion of myeloid progenitors in the bone marrow and also limited virus clearance from the lung. These findings suggest that acute inflammatory cytokines drive production and differentiation of myeloid cells in the bone marrow by inducing differentiation of committed myeloid progenitors. Our findings provide insight into the mechanisms via which innate immune responses regulate myeloid cell progenitor numbers in response to acute respiratory virus infection.

Targeting translational control as a novel way to treat inflammatory disease: the emerging role of microRNAs

Chronic inflammatory diseases (e.g. asthma and chronic obstructive pulmonary disease)are leading causes of morbidity and mortality world-wide and effective treatments are limited. These disorders can often be attributed to abnormal immune responses to environmental stimuli and infections. Mechanisms leading to inflammation are complex,resulting from interactions of structural cells and activation of both the adaptive and innate arms of the immune system. The activation of structural and immune cells involves both temporary and permanent changes in gene expression in these cells, which underpin chronic inflammation and tissue dysfunction. miRNAs are small non-coding RNAs increasingly being recognized to play important roles in the post-transcriptional regulation of gene expression in mammalian cells by regulating translation. Individual miRNA scan exert their effects by directly inhibiting the translation or stability of multiple mRNAs simultaneously. Thus, the expression or blockade of function of a single miRNA (miR) can result in pronounced alterations in protein expression within a given cell. Dysregulation of miRNA expression may subsequently alter cellular function, and in certain situations predispose to disease. Our current understanding of the role of miRNA in the regulation of inflammatory disease (e.g. allergic diseases) remains limited. In this review, we provide an overview of the current understanding of miRNA biogenesis and function, the roles miRNA play in the regulation of immune cell function and their potential contribution to inflammatory diseases. We also highlight strategies to alter miRNA function for experimental or therapeutic gain, and discuss the potential utility and limitations of targeting these molecules as anti-inflammatory strategies.

IL-7Rα and L-selectin, but not CD103 or CD34, are required for murine peanut-induced anaphylaxis

Background

Allergy to peanuts results in severe anaphylactic responses in affected individuals, and has dramatic effects on society and public policy. Despite the health impacts of peanut-induced anaphylaxis (PIA), relatively little is known about immune mechanisms underlying the disease. Using a mouse model of PIA, we evaluated mice with deletions in four distinct immune molecules (IL7Rα, L-selectin, CD34, CD103), for perturbed responses.

Methods

PIA was induced by intragastric sensitization with peanut antigen and cholera toxin adjuvant, followed by intraperitoneal challenge with crude peanut extract (CPE). Disease outcome was assessed by monitoring body temperature, clinical symptoms, and serum histamine levels. Resistant mice were evaluated for total and antigen specific serum IgE, as well as susceptibility to passive systemic anaphylaxis.

Results

PIA responses were dramatically reduced in IL7Rα^−/− and L-selectin^−/− mice, despite normal peanut-specific IgE production and susceptibility to passive systemic anaphylaxis. In contrast, CD34^−/− and CD103^−/− mice exhibited robust PIA responses, indistinguishable from wild type controls.

Conclusions

Loss of L-selectin or IL7Rα function is sufficient to impair PIA, while CD34 or CD103 ablation has no effect on disease severity. More broadly, our findings suggest that future food allergy interventions should focus on disrupting sensitization to food allergens and limiting antigen-specific late-phase responses. Conversely, therapies targeting immune cell migration following antigen challenge are unlikely to have significant benefits, particularly considering the rapid kinetics of PIA.

Opposing roles for CD34 in B16 melanoma tumor growth alter early stage vasculature and late stage immune cell infiltration

Tumor growth and metastasis are determined by the complex interplay of factors, including those intrinsic to tumor cells and extrinsic factors associated with the tumor microenvironment. Our previous work demonstrated key roles for CD34 in the maintenance of vascular integrity and eosinophil and mast cell homing. Since both of these functions affect tumor development, we characterized the effect of CD34 ablation on tumor growth using the B16F1 melanoma model. Intriguingly, we found that CD34 plays a biphasic role in tumor progression. In early growth, both subcutaneous-injected tumors and intravenous-injected lung metastases grew more slowly in Cd34^−/− mice. This correlated with abnormal vessel morphology and increased vascular permeability in these mice. Bone marrow transplantation experiments confirmed that this reflects a non-hematopoietic function of CD34. At later stages, subcutaneous tumor growth was accelerated in Cd34^−/− mice and surpassed growth in wildtype mice. Bone marrow chimera experiments demonstrated this difference was due to a hematopoietic function for CD34 and, correspondingly we found reduced intra-tumor mast cell numbers in Cd34^−/− mice. In aggregate, our analysis reveals a novel role for CD34 in both early and late tumor growth and provides novel insights into the role of the tumor microenvironment in tumor progression.

A novel ENU-generated truncation mutation lacking the spectrin-binding and C-terminal regulatory domains of Ank1 models severe hemolytic hereditary spherocytosis

OBJECTIVE

Hereditary spherocytosis (HS) is a heterogeneous group of spontaneously arising and inherited red blood cell disorders ranging from very mild subclinical cases to severe and life-threatening cases, with symptoms linked directly to the severity of the mutation at the molecular level. We investigated a novel mouse model in which the heterozygotes present with the diagnostic hallmarks of mild HS and surviving homozygotes phenocopy severe hemolytic HS.

MATERIALS AND METHODS

We used N-ethyl-N-nitrosourea mutagenesis to generate random point mutations in the mouse genome and a dominant screen to identify mouse models of human hematopoietic disease. Gene mapping of the HS strain revealed a unique in-frame nonsense mutation arising from a single base transversion in exon 27 of Ank1 (strain designation: Ank1(E924X)). Employing conventional hematopoietic, pathological, biochemical, and cell biology assays, we characterized heterozygous and homozygous Ank1(E924X) mice at the biochemical, cellular, and pathophysiological levels.

RESULTS

Although Ank1(E924X/E924X) red blood cell ghosts lack abundant full-length ankyrin-1 isoforms, N-terminal epitope ankyrin-1 antibodies reveal a band consistent with the theoretical size of a truncated mutant ankyrin-1. Using domain-specific antibodies, we further show that this protein lacks both a spectrin-binding domain and a C-terminal regulatory domain. Finally, using antisera that detect C-terminal residues of the products of alternative Ank1 transcripts, we find unique immunoreactive bands not observed in red blood cell ghosts from wild-type or Ank1(E924X) heterozygous mice, including a band similar in size to full-length ankyrin-1.

CONCLUSIONS

The Ank1(E924X) strain provides a novel tool to study Ank1 and model HS.