PhD Student

Credits: None available.

Itaconate regulates responses to inhaled aeroallergen

Gesa J. Albers1, Patricia P. Ogger1, Simone A. Walker1, John M. Halket2, Robert Gray2, Clare M. Lloyd1, Adam Byrne1
1National Heart and Lung Institute, Imperial College London, UK
2Mass Spectrometry Facility, King’s College London, UK

Background: Asthma is a chronic disease characterised by airway remodelling and hyperresponsiveness, mucus production and inflammation. Airway macrophages (AMs) are key sentinels of lung homeostasis and form the first line of defence against inhaled allergen. Increasing evidence suggests that changes in AM phenotype are underpinned by alterations in AM metabolism. The TCA cycle-derived metabolite itaconic acid (IA), synthesised by the enzyme aconitate decarboxylase (ACOD)-1, is a key regulator of macrophage function. Recently, we showed in human and murine models that IA limits pulmonary fibrosis, yet its role in regulating pulmonary responses to inhaled allergen is unknown. Here, we aimed to study the role of IA in murine models of allergic airway disease (AAD).
Methods: To characterise the kinetics of the Acod1/IA pathway in response to allergen, we measured lung Acod1 expression and BAL-IA levels after house dust mite (HDM) challenge. Next, we assessed Acod1 expression in murine AMs exposed to HDM ex vivo. Finally, to determine the role of IA in allergic airway responses, we treated WT or Acod1-/- mice with inhaled HDM and assessed disease pathology and inflammation.
Results: Continuous HDM exposure in mice resulted in augmented levels of BAL-IA and increased expression of lung Acod1. Ex vivo culture of AMs with HDM revealed enhanced Acod1 expression and a shift towards a more glycolytic phenotype. Finally, exposure of Acod1-/- mice to allergen led to an increased neutrophil-to-eosinophil ratio, compared to more eosinophilic WT controls, which was rescued by inhaled IA.
Conclusion: Our data indicate that the Acod1/IA pathway is highly induced during AAD and regulates the balance between neutrophil and eosinophil recruitment in response to inhaled allergen.

Research Associate Professor

Credits: None available.

Asthma-associated variants induce IL33 differential expression through a novel regulatory region

Ivy Aneas1, Donna C. Decker2, Débora R. Sobreira1, Noboru J. Sakabe1, Kelly M. Blaine2, Kevin M. Magnaye1, Selene M. Clay1, Carole Ober1, Anne I. Sperling2,3, Marcelo A. Nobrega1.
1- Department of Human Genetics, University of Chicago, Chicago, IL; 2- Department of Medicine, Section of Pulmonary and Critical Care Medicine, University of Chicago, Chicago, IL, 3- Committee on Immunology, University of Chicago, Chicago IL
Genome-wide association studies (GWAS) have implicated the IL33 locus in asthma, but the underlying mechanisms remain unclear. Here, we identify a 5 kb region within the GWAS-defined segment that acts as a strong regulatory element in vivo and in vitro. Chromatin conformation capture showed that this 5 kb region loops to the IL33 promoter, potentially regulating its expression. We show that genotype at the asthma-associated SNP rs1888909, located within the 5 kb region, is associated with IL33 gene expression in human airway epithelial cells and IL-33 protein expression in human plasma, potentially through differential binding of OCT-1 (POU2F1) to the asthma-risk allele. Our data demonstrate that asthma-associated variants at the IL33 locus mediate allele-specific regulatory activity and IL33 expression, providing a novel mechanism through which a regulatory SNP contributes to genetic risk of asthma.

Research associate

Credits: None available.

Evidence for an alternative IL13/IL13R mediated allergen response in lung in the absence of ILC2 cells and IL5

Jennifer Fraszczak*, Thannina Hamadou and Tarik Möröy*#&

* Institut de recherches cliniques de Montréal, québec, Canada
# Département de microbiologie, infectiologie et immunologie, Faculty of Medicine, Université de Montréal, Montreal, Canada
& Division of Experimental Medicine, McGill University, Montreal, Canada

Asthma is an inflammatory disease of the bronchial airways and is mainly caused by environmental factors such as air pollution and allergens. The development of resistance to existing therapies and increasing air pollution and exposure to allergens have made asthma a major health problem. The molecular mechanisms underlying an asthmatic reaction in the lung caused by airborne allergens are not well understood, but recent experimental evidence exists indicating that this reaction is mainly driven by type 2 innate lymphoid cells (ILC2) and CD4+ type 2 T helper cells (Th2). These cells support allergic reactions by producing cytokines such as IL4 or IL5 leading to eosinophilia. It has been shown that GFI1, a zinc finger transcription factor involved in hematopoiesis and inflammation, regulates many cells involved in the Th2 type immune response including ILC2 or Th2 T cells. Although Gfi1 deficient mice lack functional ILC2 and Th2 T cells and fail to produce IL5, they still show a robust response to allergens with features such as increased expression of mucus-associated genes and lung fibrosis. In particular, GFI1 KO mice still have an accumulation of  CD11c+SiglecFhigh eosinophils to the lungs in response to allergen. In addition, Gfi1 KO mice have a higher expression of Il13 mRNA in the lungs after allergen stimulation and Gfi1 null CD11c+SiglecFhigh eosinophils express Il13ra1. These data suggests that GFI1 KO mice can adapt their response to the allergen by using a different mechanism than WT mice. These findings may have implications for the currently used allergy therapies using anti-IL5 antibodies and may explain the occurrence of resistance towards this treatment.    


Credits: None available.

Pre-existing asthma does not enhance cytokine response and disease severity of COVID-19

Background: Both COVID-19 and asthma involve pulmonary inflammation, damage and dysfunction, and can result in respiratory failure and death.(1) A significant portion of COVID-19 sufferers have asthma comorbidity,(2) however, the impact of COVID-19 infections on patients with asthma is still unclear. In this study, we investigated the roles of pre-existing asthma as a comorbidity in disease severities of COVID-19 by measuring immune response in circulating cytokines.

Methods: Plasma samples and clinical information were collected from patients (total 80) with mild (25), severe (36) or critical (19) cases of COVID-19 at the John Radcliffe Hospital, Oxford, UK. The concentrations of 51 proteins in the plasma samples were measured with Luminex Kits (Bio-techne) using a Bio-Rad Bio-Plex® 200 Systems.

Results: A total of 16 pre-existing asthma patients were found (3 in mild, 10 in severe, and 3 in critical COVID-19).
In the comparison of circulating cytokines enrichment, no significant difference between COVID-19 patients with and without asthma was found in different disease severities and age groups. Indeed, a trend of slightly lower levels of CXCL10, CCL2, and IL-8 were observed in patients with asthma.
In comparing clinical traits within the same COVID-19 severity group, also no differences were observed between patients with or without asthma in terms of oxygen level, CRP, neutrophil counts, and length of hospital stay. Although the age distribution showed a slight increase with severity of COVID-19 (37.33±17.04 in mild, 55.60±16.12 in severe and 70.00±11.36 in critical) in the patients with asthma but not in the patients without asthma (69.91±20.15 in mild, 66.69±15.51 in severe and 55.38±12.47 in critical), the prevalence of asthma in COVID-19 severity groups (12.0% in mild, 27.8% in severe and 15.8% in critical) did not exhibit a clear correlation between asthma and the severities of COVID-19. Furthermore, the mortality ratio in the COVID-19 patients with asthma (12.5%) was not higher than that in patients without asthma (17.2%).

Conclusions: Based on this cohort study, pre-existing asthma was not associated with an enhanced cytokine storm after COVID-19 infection, and did not have strong effects on COVID-19 progression.

1. Menter T, et al. Postmortem examination of COVID-19 patients reveals diffuse alveolar damage with severe capillary congestion and variegated findings in lungs and other organs suggesting vascular dysfunction. Histopathology. 2020 May 4.
2. Docherty AB, et al. Features of 20133 UK patients in hospital with covid-19 using the ISARIC WHO Clinical Characterisation Protocol: prospective observational cohort study. BMJ. 2020;369:m1985.

Assistant Professor

Credits: None available.

Asthma and comorbidities, a harmful association, especially during COVID-19
Leila Laouar1,2,*, Sarah Boukellal2, Ali Adib Yaici2, Med Taib Makhloufi1,2, and Samya Taright1,2
1University Benyoucef Benkhedda, School of Medicine, Algiers, Algeria.
2Department of Pulmonary Diseases, Center Hospitalo-Universitaire Mustapha Pasha, Algiers, Algeria
* Correspondence should be addressed to:
Asthma management cannot depend solely on medication; instead, it requires the control of environmental exposures as well as the comorbidities that have a poor impact on the overall prognosis. Among these comorbidities, cardiovascular manifestations and metabolic disorders such as diabetes and obesity, are reminiscent of the risk factors underlying COVID-19 severity. Management of such comorbidities is critical in asthmatic patients during a pandemic, and particularly during the confinement period in which sedentary lifestyle, depression and eating disorders significantly intensify, contributing to weight gain and induction of cardiovascular diseases in asthmatic patients. The goal from this study is to determine the frequency of comorbidities and their impact on asthma control. To this aim, we have conducted a study using a cohort of 51 asthmatic patients monitored in the Tuberculosis and Chronic Respiratory Diseases Control Unit at Mustapha Pasha Hospital in Algiers, Algeria. In agreement with data studies published in the literature, we observed that women are at significantly increased risk of developing asthma with a male to female ratio of 0.31 and a median patient age of 58 years. Our data revealed a poor control of asthma in 35% of our cohort patients compared to 25-65% of cases reported in the literature, but a higher frequency of comorbidities in 88.2% of our patients compared to 15-86% of cases reported in the literature. Specifically, we report the following medical conditions in our cohort patients: 30% obesity (among obese patients, 47% exhibited poor asthma control); 60% allergic rhinitis (among patients with rhinitis, 25% exhibited poor control); 27% gastroesophageal reflux disease or GERD (among patients with GERD, 35% exhibited poor control); 30% hypertension (among hypertensive patients, 38% exhibited poor control); and 12% type 2 diabetes (among diabetic patients, 54% exhibited poor control). It should be noted that asthma control is largely conditioned by the proper use of the inhalation device, which remains a problem for the majority of asthmatic patients. However, this is not the case for our cohort patients, since most of them (> 75%) were properly trained for the use of such a medical device. Finally, in agreement with data studies published in the literature, we observed that smoking -whether passive or active- caused further exacerbations of asthma with lesser disease control. Although asthma is not among the top conditions associated with COVID-19 deaths (unlike cardio-metabolic disorders which are more frequently reported in severe COVID-19 cases); we cannot rule out the possibility that infection by COVID-19 could be responsible for an exacerbation of asthma, in particular in the presence of comorbidities which are reminiscent of the risk factors of severity and mortality by COVID-19. In this regard, recent published data on Algerian patients hospitalized for severe forms of COVID-19 reported a frequency of 8% of asthmatics among COVID-19 patients. Notably, these COVID-19 asthmatics suffered from a severe form of asthma associated with cardiovascular comorbidities. Therefore, achieving an optimal level of asthma control should be among the primary goals to attenuate COVID-19 severity. However, such a control is arduous due to the many associated factors involved in a cause-effect relationship with asthma including allergic rhinitis, GERD and obesity, in addition to the most common comorbidities such as diabetes. With all data considered, it remains unsolved whether the reported severity of COVID-19 in asthmatics is due to asthma manifestation itself or is the result of its underlying comorbidities. Future studies in this direction will elucidate the bias of causal links of asthma with certain comorbidities in COVID-19 patients.

Associate Professional Researcher

Credits: None available.

IL-13 regulates transcriptional changes in SARS-CoV-2-associated genes in asthma

Luke R Bonser1*, Walter L Eckalbar1,2,3*, Stephanie A Christenson2, Jiangshan Shen1, Kyung Duk Koh1, Lorna T Zlock4, Walter E Finkbeiner4, and David J Erle1,3,5,6

*These authors contributed equally.
1Lung Biology Center and 2Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, Department of Medicine; 3UCSF CoLabs; 4Department of Pathology; 5Cardiovascular Research Institute; and 6ImmunoX Initiative; University of California, San Francisco

Rationale: SARS-CoV-2, the virus that causes COVID-19, exhibits an ACE2-dependent airway epithelial tropism, and exploits host cell proteins to replicate and evade detection. The impact of asthma on COVID-19 susceptibility and severity is unclear.

Objectives: We sought to discover how genes encoding SARS-CoV-2-associated host proteins are expressed in primary human bronchial epithelial cells (HBECs), and how these genes are regulated by cytokines important in asthma.

Methods: We cultured primary HBECs at air-liquid interface in the absence of cytokine, or with IL-13, IL-17, IFN-a, or IFN-g. We used bulk RNA-seq and single cell RNA-sequencing to identify changes in gene expression. We correlated cytokine-regulated changes in SARS-CoV-2-associated transcripts with gene expression changes in transcriptomic profiling datasets derived from individuals with mild-to-moderate asthma and chronic obstructive pulmonary disease (COPD).

Measurements and Main Results: Transcripts encoding 332 of 342 (97%) SARS-CoV-2-associated proteins were detected in HBECs (≥1 RPM in 50% samples). 85 (26%) of these mRNAs were regulated by at least one cytokine (>1.5-fold change, FDR < 0.05). 21 and 19 of the 41 SARS-CoV-2-associated genes regulated by IL-13 in HBECs were correlated with type 2 inflammatory gene signature scores in transcriptomic profiling datasets derived from individuals with mild-to-moderate asthma and COPD (p < 0.05). Few IL-17 or interferon-responsive genes were correlated with their respective signatures in either dataset. Single cell RNA-sequencing revealed that 143 of the 332 (43%) SARS-CoV-2-associated transcripts detected in HBECs were differentially expressed between cell types (FDR < 0.05); some of these genes were associated with SARS-CoV-2 proteins predicted to co-opt host trafficking pathways. 11 SARS-CoV-2-associated genes were modulated by IL-13 in a cell type-specific manner (>1.25-fold change, FDR < 0.05).

Conclusions: Many genes encoding proteins associated with SARS-CoV-2 infection are expressed in HBECs, with substantial differences among cell subsets. IL-13 induces extensive changes in the expression of SARS-CoV-2-related genes that correlated with a measure of type-2 inflammation in vivo, providing a plausible basis for differences in outcome of COVID-19 in individuals with asthma.

Instructor in Medicine

Credits: None available.

Defining the functions of tissue-resident and circulating memory Th2 cells in allergic asthma

Rod A. Rahimi1,2,3, Keshav Nepal1,2,4, Murat Cetinbas5,6, Ruslan I. Sadreyev5,7, and Andrew D. Luster1,2,4

1Airway Immunity Research Program, 2Center for Immunology and Inflammatory Diseases, 3Division of Pulmonary and Critical Care Medicine, 4Division of Rheumatology, Allergy, and Immunology, 5Department of Molecular Biology, 6Department of Genetics, 7Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA

Tissue-resident memory T (Trm) cells are a unique population of memory T cells that are durably parked in non-lymphoid tissues and play an important role in host defense against recurrent infection and malignancy. CD4+ T helper type 2 (Th2) cells play a central role in allergic diseases, including asthma, but the biology of Th2 Trm cells in recurrent allergic inflammation is not well defined. Specifically, the mechanisms whereby Th2 Trm cells and circulating memory Th2 cells promote allergic asthma pathogenesis remain unclear. Using a house dust mite (HDM) model of allergic asthma and parabiosis, we demonstrate that Th2 Trm cells and circulating memory Th2 cells perform distinct functions in vivo. Upon HDM rechallenge, circulating memory Th2 cells trafficked into the lung parenchyma and ignited perivascular inflammation to promote inflammatory cell recruitment, including CD4+ T cells, eosinophils, and dendritic cells. In contrast, Th2 Trm cells proliferated near airways and were critical in promoting mucus metaplasia, airway hyperresponsiveness, and airway eosinophil activation. Transcriptional analysis revealed that Th2 Trm cells and circulating memory Th2 cells share a core Th2 gene signature, but also exhibit distinct transcriptional profiles. Th2 Trm cells express a tissue-adaptation signature, including genes involved in extracellular matrix biology and lipid metabolism. Our findings demonstrate that Th2 Trm cells and circulating memory Th2 cells are functionally and transcriptionally distinct subsets with unique roles in vivo, with the establishment of Th2 Trm cells being critical for the full manifestation of allergic airway disease. Defining the unique mechanisms regulating the development and maintenance of Th2 Trm cells within the lungs has the potential to yield novel therapeutic approaches for allergic asthma.

PhD Student

Credits: None available.

Butyrate selectively inhibits metabolic reprogramming of inflammatory eosinophils in allergic asthma

Rossana Azzoni1, Tara Sutherland1, Tracy Hussell1, Joanne Konkel1, Yashaswini Kannan2, Edith Hessel3 and John Grainger1

1Faculty of Medicine, Biology and Health, University of Manchester, Lydia Becker Institute, Manchester,UK
2Adaptive Immunity Research Unit, Glaxosmithkline, Stevenage, UK
3 Mestag Therapeutics, London, UK

Background: Allergic asthma is characterised by dominant Th2 responses to innocuous environmental antigens, such as house dust mite (HDM), resulting in significant airway eosinophilia. Eosinophil activation exerts a central role in asthma pathogenesis through the release of cytotoxic granules and cytokines. As well as these effector functions, eosinophils have been shown to promote homeostatic responses at steady-state and disease, which may explain why eosinophil-targeted therapies have had mixed results. Two different populations of eosinophils have recently been identified in the lungs of murine models of allergic inflammation, and have been described as Siglec-FintCD11bint and Siglec-FhiCD11bhi eosinophils. 

Aims: It is still not clear how Siglec-FintCD11bint and Siglec-FhiCD11bhi eosinophils originate, and further develop during allergic disease, how they are maintained, what their phenotype is and if specific factors mediate these processes. Therefore, our aim was to better define these mechanisms to understand whether we could bias towards targeting one population or the other from a therapeutic standpoint. 

Methods: We have used a murine model of acute allergic airway inflammation induced by intranasal exposure to HDM. Sensitisation (day 0) with HDM was followed by 5 consecutive challenges (day 7-11) and euthanasia 24 hours after the last challenge.     

Results: We detected Siglec-FintCD11bint and Siglec-FhiCD11bhi eosinophils in the lungs and blood of HDM-treated mice. We found that Siglec-FhiCD11bhi but not Siglec-FintCD11bint eosinophils contributed to the inflammatory response. This was mediated via enhanced CD98 expression and metabolic activity, which represented universal features of Th2 inflammatory responses. We also established that, following HDM administration, the short-chain fatty butyrate could specifically decrease levels of Siglec-FhiCD11bhi eosinophils as well as their metabolic activity in the lung and that this mechanism may be mediated by GPR109a. Thus, selective targeting of Siglec-FhiCD11bhi eosinophils and their metabolism may be beneficial in ameliorating allergic lung inflammation. 


Credits: None available.

B cell IgM isotype regulates airway smooth muscle contraction in allergic asthma
Authors and Affiliations: 
Sabelo Hadebe*1, Jermaine Khumalo1,2, Katelyn Jones1, Anca Savulescu4, Sandisiwe Mangali1,2, Amkele Ngomti1,2,Martyna Scibiorek1,2, Frank Kirstein1, Frank Brombacher*1,2,3  
1Division of Immunology, and South African Medical Research Council (SAMRC) Immunology of Infectious Diseases, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa  
2International Centre for Genetic Engineering and Biotechnology (ICGEB) and Institute of Infectious Diseases and Molecular Medicine (IDM), Division of Immunology, Health Science Faculty, University of Cape Town, Cape Town, South Africa  
3Wellcome Centre for Infectious Diseases Research in Africa (CIDRI-Africa), Institute of Infectious Diseases and Molecular Medicine (IDM), Faculty of Health Sciences, University of Cape Town, Cape Town, 7925, South Africa 
4Division of Chemical, Systems & Synthetic Biology, Faculty of Health Sciences, Institute of Infectious Disease & Molecular Medicine, University of Cape Town, Cape Town, South Africa
Allergic asthma is a disease driven by T helper 2 (TH2)-type cells secreting interleukin (IL-) 4, 5 and 13. It is characterized by eosinophils, airway hyperresponsiveness (AHR) and IgE secreting B cells. B cells play a role in allergic asthma in an allergen load dependent manner. IgM isotype secreted by naïve B cells is important for class switching. It is currently unclear how IgM isotype contributes in the development of allergic asthma. We investigated the role of IgM isotype in a house dust mite (HDM)-induced TH2 allergic asthma model. We sensitised wild type (wt), IgM-deficient (IgM-/-) and B cell-deficient (uMT-/-) mice with high (>10 ug) and low (<3 ug) dose of HDM extracts. We found IgM to be essential in IgE production and in AHR, but not in TH2 airway inflammation or eosinophilia. Transfer of wild type serum, but not B cells into IgM-/-mice could restore class switching but not AHR. RNA seq suggested that IgM regulated AHR through modulating airway smooth muscle (ASM) genes, particularly those associated with acetylcholine and contraction. Using single cell force cytometry (FLECS) and CRISPR-Cas9 technology we validate the importance of some of these genes in human ASM contraction. These unprecedented findings suggest that IgM has a unique function in allergic asthma and regulates AHR by interacting with structural cells.

Associate Professor, Internal Medicine, Division Chief, Allergy Immunology, Ann Arbor VA

Credits: None available.

RNA binding protein HuR posttranscriptionally regulates CD4+ T cell inflammatory gene expression in asthma
Ulus Atasoy1, Fatemeh Fattahi1, Jason Ellis1, Kristin Bahleda1, Nerissa Reister1, Njira Lugogo1,
1 University of Michigan, Ann Arbor, MI.

Due to poor correlation between steady-state mRNA levels and protein product, transcriptomic analyses may miss critical genes controlling inflammation. Many genes are regulated posttranscriptionally at levels of mRNA stability and translation by RNA-binding proteins (RBPs) and miRNAs, however this is not well understood. Pro-inflammatory genes which play pivotal roles in airway inflammation usually have labile mRNA transcripts and are regulated posttranscriptionally. Using novel RIP-Seq methods, we have uncovered how RBP HuR (elavl1) regulates key genes involved in CD4+ Th subset differentiation since it binds to and regulates gata3 and Th2 cytokine mRNAs. HuR regulates inflammatory genes allowing for lung inflammation in asthma. We previously demonstrated that HuR overexpression in CD4+ T cells results in increases in Th2 cytokine production. Conditional ablation of HuR in T cells (distal Lck-cre HuRfl/fl), abrogates Th2 differentiation, cytokine production and lung inflammation in ova challenge model. We hypothesized that HuR may similarly regulate lung inflammation in human asthma. We discovered that HuR protein expression is greatly increased (100%) in peripheral CD4+ T cells from asthmatics (both type 2 high and low) compared with healthy individuals. Asthmatic PBLs have increased frequency and production of both Th2/Th17 signature cytokines. Using a drug (acadesine aka AICAR) which interferes with HuR function, we show that CD4+ T cells treated with acadesine have decreases in Th2/17 cytokine expression. Taken together, these data suggest that HuR plays a permissive role in both allergen and non-allergen driven airway inflammation by regulating key genes and that interfering with its function may be a novel way to treat asthma.