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BACKGROUND: Asthma and chronic obstructive pulmonary disease (COPD) are common chronic respiratory diseases, and some patients have overlapping disease features, termed asthma-COPD overlap (ACO). Patients characterized with ACO have increased disease severity; however, the mechanisms driving this have not been widely studied. OBJECTIVES: This study sought to characterize the phenotypic and transcriptomic features of experimental ACO in mice induced by chronic house dust mite antigen and cigarette smoke exposure. METHODS: Female BALB/c mice were chronically exposed to house dust mite antigen for 11 weeks to induce experimental asthma, cigarette smoke for 8 weeks to induce experimental COPD, or both concurrently to induce experimental ACO. Lung inflammation, structural changes, and lung function were assessed. RNA-sequencing was performed on separated airway and parenchyma lung tissues to assess transcriptional changes. Validation of a novel upstream driver SPI1 in experimental ACO was assessed using the pharmacological SPI1 inhibitor, DB2313. RESULTS: Experimental ACO recapitulated features of both asthma and COPD, with mixed pulmonary eosinophilic/neutrophilic inflammation, small airway collagen deposition, and increased airway hyperresponsiveness. Transcriptomic analysis identified common and distinct dysregulated gene clusters in airway and parenchyma samples in experimental asthma, COPD, and ACO. Upstream driver analysis revealed increased expression of the transcription factor Spi1. Pharmacological inhibition of SPI1 using DB2313, reduced airway remodeling and airway hyperresponsiveness in experimental ACO. CONCLUSIONS: A new experimental model of ACO featuring chronic dual exposures to house dust mite and cigarette smoke mimics key disease features observed in patients with ACO and revealed novel disease mechanisms, including upregulation of SPI1, that are amenable to therapy.

Innate lymphoid cells (ILCs) are resident in the lung and are involved in both the maintenance of homeostasis and the pathogenesis of respiratory diseases. In this study, murine lung ILCs were characterized using flow cytometry and the impact of mouse age, sex and strain were assessed. Lung ILCs were found as early as postnatal day 4 and numbers peaked at 2 weeks, and then decreased as the lung matured. During postnatal lung development, ILC expressed differential amounts of group 2 ILC (ILC2)-associated cell surface antigens including ST2, CD90.2 and ICOS. Using Il5venus Il13td-tomato dual reporter mice, neonates were found to have increased constitutive interleukin (IL)-13 expression compared with adult mice. Neonates and adults had similar ratios of IL-5+ CD45+ leukocytes; however, these cells were mostly composed of ILCs in neonates and T cells in adults. Sex-specific differences in ILC numbers were also observed, with females having greater numbers of lung ILCs than males in both neonatal and adult mice. Female lung ILCs also expressed higher levels of ICOS and decreased KLRG1. Mouse strain also impacted on lung ILCs with BALB/c mice having more ILCs in the lung and increased expression of ST2 and ICOS compared with C57BL/6J mice. Collectively, these data show that lung ILC numbers, cell surface antigen expression, IL-5 and IL-13 levels differed between neonatal and adult lung ILCs. In addition, cell surface antigens commonly used for ILC2 quantification, such as ST2, CD90.2 and ICOS, differ depending on age, sex and strain and these are important considerations for consistent universal identification of lung ILC2s.

Acute kidney injury (AKI) remains a global challenge and, despite the availability of dialysis and transplantation, can be fatal. Those that survive an AKI are at increased risk of developing chronic kidney disease and end stage renal failure. Understanding the fundamental mechanisms underpinning the pathophysiology of AKI is critical for developing novel strategies for diagnosis and treatment. A growing body of evidence indicates that amplifying type 2 immunity may have therapeutic potential in kidney injury and disease. Of particular interest are the recently described subset of innate immune cells, termed group 2 innate lymphoid cells (ILCs). Group 2 ILCs are crucial tissue-resident immune cells that maintain homeostasis and regulate tissue repair at multiple organ sites, including the kidney. They are critical mediators of type 2 immune responses following infection and injury. The existing literature suggests that activation of group 2 ILCs and production of a local type 2 immune milieu is protective against renal injury and associated pathology. In this review, we describe the emerging role for group 2 ILCs in renal homeostasis and repair. We provide an in-depth discussion of the most recent literature that use preclinical models of AKI and assess the therapeutic effect of modulating group 2 ILC function. We debate the potential for targeting these cells as novel cellular therapies in AKI and discuss the implications for future studies and translation. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Innate lymphoid cells (ILC) are resident in the lung and are involved in both the maintenance of homeostasis and the pathogenesis of respiratory diseases. In this study, murine lung ILC were characterised using flow cytometry and the impact of mouse age, sex and strain were assessed. Lung ILC were found as early as postnatal day 4 and numbers peaked at 2 weeks, and then decreased as the lung matured. During postnatal lung development, ILC expressed differential amounts of ILC2-associated cell surface antigens including ST2, CD90.2 and ICOS. Using Il5venusIl13td-tomato dual reporter mice, neonates were found to have increased constitutive IL-13 expression compared to adult mice. Neonates and adults had similar ratios of IL-5+CD45+ leukocytes, however, these cells were mostly composed of ILC in neonates and T cells in adults. Sex-specific differences in ILC numbers were also observed, with females having greater numbers of lung ILC than males in both neonatal and adult mice. Female lung ILC also expressed higher levels of ICOS and decreased KLRG1. Mouse strain also impacted on lung ILC with BALB/c mice having more ILC in the lung and increased expression of ST2 and ICOS compared with C57BL/6J mice. Collectively, these data show that lung ILC numbers, cell surface antigen expression, IL-5 and IL-13 levels differed between neonatal and adult lung ILC. Additionally, cell surface antigens commonly used for ILC2 quantification, such as ST2, CD90.2, and ICOS, differ depending on age, sex and strain and these are important considerations for consistent universal identification of lung ILC2.

Introduction Cardiac fibrosis is a severe consequence of cardiovascular disease and aging, in which we currently have no effective treatments. The mechanisms underpinning the development of cardiac fibrosis remains poorly understood. Our preliminary data suggested extracellular matrix protein 1 (ECM1) is involved in cardiac fibrosis. We therefore aimed to investigate the role of ECM1 in several fibrotic cardiac diseases. Methods Young and ageing (3m/18m) male C57BL/6 mice, and primary mouse cardiac fibroblast (cFB) cultures, commercial human cardiac fibroblasts (Hu-cFB), human coronary artery endothelial cell (HCAEC)/smooth muscle cell (HCASMC), and human cardiac myocyte (HCM) cell lines were used. Young mice were subject to myocardial infarction (MI, 3-day/28-day, n=6/6), or pressure overload (TAC, 3-day/13-week, n=4/4). Left ventricle (LV) was collected at all time-points, and at 18m (ageing; n=3). Spleen and bone marrow was extracted from young control mice. Hu-cFB cells were treated with recombinant ECM1 (20ng/ml) for either 10, 30 or 50 min, or 48h. Immunoblotting was conducted on all samples, qPCR on LV tissue only, density gradient centrifugation and multicolour flow cytometry coupled with fluorescent ECM1 mRNA in-situ hybridisation (FISH-Flow) on bone marrow cells. Results ECM1 expression was upregulated in ageing LV (mRNA 2.2±0.1-fold, p=0.0002; protein 2.0-fold, p=0.0006), day-3 post-MI (mRNA, 4.9±2.0-fold, p=0.004; protein, 3.0-fold, p=0.004), a trend of ECM1 upregulation was observed at day-28 post-MI (mRNA, 13.2±12.0-fold, p=0.003; protein, 1.8-fold, p=0.2), but no change post-TAC. Both ERK1/2 and AKT phosphorylation was upregulated 10 min post-ECM1 treatment of Hu-cFBs (ERK1/2, 2.0-fold, p Conclusions These data demonstrate that ECM1 plays a role in ageing and post-MI fibrosis. Although ECM1 was not produced by resident cardiac cells, it was highly expressed in spleen and bone marrow; specifically, large, granular bone marrow cell sub-types such as granulocytes and/or macrophages. Our data suggest ECM1 is expressed by cardiac infiltrating leukocytes to provoke fibroblast collagen expression in a disease specific manner; potentially via the ERK1/2 and/or AKT pathway activation. Therefore, ECM1 warrants further investigation, and may be a promising target for the treatment of fibrotic cardiac diseases. Acknowledgement/Funding John hunter hospital charitable trust, Hunter medical research institute (HMRI) grants

Author(s): Hardy, Sean A; Mabotuwana, Nishani S; Murtha, Lucy A; Coulter, Brianna; Sanchez-Bezanilla, Sonia; Al-Omary, Mohammed S; Senanayake, Tharindu; Loering, Svenja; Starkey, Malcolm; Lee, Randall J; Rainer, Peter P; Hansbro, Philip M; Boyle, Andrew J | Abstract: IntroductionThe prevalence of heart failure increases in the aging population and following myocardial infarction (MI), yet the extracellular matrix (ECM) remodeling underpinning the development of aging- and MI-associated cardiac fibrosis remains poorly understood. A link between inflammation and fibrosis in the heart has long been appreciated, but has mechanistically remained undefined. We investigated the expression of a novel protein, extracellular matrix protein 1 (ECM1) in the aging and infarcted heart.MethodsYoung adult (3-month old) and aging (18-month old) C57BL/6 mice were assessed. Young mice were subjected to left anterior descending artery-ligation to induce MI, or transverse aortic constriction (TAC) surgery to induce pressure-overload cardiomyopathy. Left ventricle (LV) tissue was collected early and late post-MI/TAC. Bone marrow cells (BMCs) were isolated from young healthy mice, and subject to flow cytometry. Human cardiac fibroblast (CFb), myocyte, and coronary artery endothelial a smooth muscle cell lines were cultured; human CFbs were treated with recombinant ECM1. Primary mouse CFbs were cultured and treated with recombinant angiotensin-II or TGF-β1. Immunoblotting, qPCR and mRNA fluorescent in-situ hybridization (mRNA-FISH) were conducted on LV tissue and cells.ResultsECM1 expression was upregulated in the aging LV, and in the infarct zone of the LV early post-MI. No significant differences in ECM1 expression were found late post-MI or at any time-point post-TAC. ECM1 was not expressed in any resident cardiac cells, but ECM1 was highly expressed in BMCs, with high ECM1 expression in granulocytes. Flow cytometry of bone marrow revealed ECM1 expression in large granular leucocytes. mRNA-FISH revealed that ECM1 was indeed expressed by inflammatory cells in the infarct zone at day-3 post-MI. ECM1 stimulation of CFbs induced ERK1/2 and AKT activation and collagen-I expression, suggesting a pro-fibrotic role.ConclusionsECM1 expression is increased in ageing and infarcted hearts but is not expressed by resident cardiac cells. Instead it is expressed by bone marrow-derived granulocytes. ECM1 is sufficient to induce cardiac fibroblast stimulation in vitro. Our findings suggest ECM1 is released from infiltrating inflammatory cells, which leads to cardiac fibroblast stimulation and fibrosis in aging and MI. ECM1 may be a novel intermediary between inflammation and fibrosis.

Lung development is a complex process mediated through the interaction of multiple cell types, factors and mediators. In mice, it starts as early as embryonic day 9 and continues into early adulthood. The process can be separated into five different developmental stages: embryonic, pseudoglandular, canalicular, saccular, and alveolar. Whilst lung bud formation and branching morphogenesis have been studied extensively, the mechanisms of alveolarisation are incompletely understood. Aberrant lung development can lead to deleterious consequences for respiratory health such as bronchopulmonary dysplasia (BPD), a disease primarily affecting preterm neonates, which is characterised by increased pulmonary inflammation and disturbed alveolarisation. While the deleterious effects of type 1-mediated inflammatory responses on lung development have been well established, the role of type 2 responses in postnatal lung development remains poorly understood. Recent studies indicate that type 2-associated immune cells, such as group 2 innate lymphoid cells and alveolar macrophages, are increased in number during postnatal alveolarisation. Here, we present the current state of understanding of the postnatal stages of lung development and the key cell types and mediators known to be involved. We also provide an overview of how stem cells are involved in lung development and regeneration, and the negative influences of respiratory infections. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.