Honors & Awards
Outstanding PhD Thesis Award, McMaster University (2018)
Research Fellowship, Canadian Institutes of Health Research (2018-2021)
Doctor of Philosophy, McMaster University (2017)
Bachelor of Science, McMaster University (2011)
Current Research and Scholarly Interests
Currently working on unraveling the mechanisms of Alzheimer's disease progression and resilience utilizing mass cytometry (CyTOF) and high-dimensional imaging (multiplexed ion beam imaging - MIBI).
Previously worked on evaluating the role of immune cells in allergic pathogenesis (IgE+ B cells, regulatory B cells or Bregs, basophils, type 2 innate lymphoid cells, eosinophils).
Collaborated on research projects with a few research groups, which include:
- The Hospital for Sick Children, Division of Pediatric Emergency Medicine and Pediatric Research Academic Initiative in SickKids Emergency (PRAISE) Program
- McMaster Children's Hospital, Division of Urology and the Clinical Urology Research Enterprise (CURE) Program
- St. Joseph's Healthcare Center Hamilton, Division of Otolaryngology and Head and Neck Surgery
Research interests include:
- The immunobiology and pathophysiology of allergic diseases (allergic asthma, allergic rhinitis)
- The role and function of regulatory B cells in disease (autoimmunity, inflammation, cancer)
- The role of immune cells (B cells, T cells, eosinophils, basophils) in the pathogenesis of disease
- Single cell analyses and 'omics' technologies including: RNAseq, CyTOF, flow and imaging cytometry
- Translational immunology, clinical drug development and clinical trials, "big data", and machine learning
- Effectiveness of active learning in undergraduate and graduate level education
Sean Bendall, Bendall Lab (11/16/2017 - 4/30/2021)
Antialarmins for treatment of asthma: future perspectives.
Current opinion in pulmonary medicine
2018; 24 (1): 32–41
Recent studies have highlighted the role of alarmins in asthma pathophysiology and tested the roles of these cytokines in asthmatic patients. This review will discuss the recent advances in the role of alarmins in asthma and the potential of future targeted therapies in asthma.Epithelial-derived cytokines can be released upon exposure to external stimuli, causing damage to the epithelial barrier and resulting in tissue inflammation. Of these cytokines, IL-25, IL-33 and thymic stromal lymphopoeitin (TSLP), have been associated with asthma. These alarmins are all not only overexpressed in asthmatic airways, particularly in airway epithelial cells, but also in other structural and immune cells. Furthermore, all three alarmins drive type-2 pro-inflammatory responses in several immune cells that have been identified as key players in the pathogenesis of asthma, including innate lymphoid type-2 cells. Clinical trials testing therapeutics that block pathways of the alarmins are in progress.To-date, only TSLP blockade has been reported in human clinical trials, and this approach has shown efficacy in asthmatic patients. Current body of evidence suggests that alarmins are useful upstream targets for treatment of asthma.
View details for DOI 10.1097/MCP.0000000000000443
View details for PubMedID 29084017
- Changes in regulatory B-cell levels in bone marrow, blood, and sputum of patients with asthma following inhaled allergen challenge. The Journal of allergy and clinical immunology 2018; 141 (4): 1495–98.e9
- Asthmatic subjects with allergy have elevated levels of IgE+ B cells in the airways. journal of allergy and clinical immunology 2017
- Increased IgE(+) B Cells in Sputum, but Not Blood, Bone Marrow, or Tonsils, after Inhaled Allergen Challenge in Subjects with Asthma. American journal of respiratory and critical care medicine 2017; 196 (1): 107–9
Allergen-induced Changes in Bone Marrow and Airway Dendritic Cells in Subjects with Asthma
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
2016; 194 (2): 169-177
Dendritic cells (DCs) are antigen-presenting cells essential for the initiation of T-cell responses. Allergen inhalation increases the number of airway DCs and the release of epithelial-derived cytokines, such as IL-33 and thymic stromal lymphopoietin (TSLP), that activate DCs.To examine the effects of inhaled allergen on bone marrow production of DCs and their trafficking into the airways in subjects with allergic asthma, and to examine IL-33 and TSPL receptor expression on DCs.Bone marrow, peripheral blood, bronchoalveolar lavage (BAL), and bronchial biopsies were obtained before and after inhalation of diluent and allergen from subjects with asthma that develop allergen-induced dual responses. Classical DCs (cDCs) were cultured from bone marrow CD34(+) cells. cDC1s, cDC2s, and plasmacytoid DCs were measured in bone marrow aspirates, peripheral blood, and BAL by flow cytometry, and cDCs were quantified in bronchial biopsies by immunofluorescence staining.Inhaled allergen increased the number of cDCs grown from bone marrow progenitors, and cDCs and plasmacytoid DCs in bone marrow aspirates 24 hours after allergen. Allergen also increased the expression of the TSLP receptor, but not the IL-33 receptor, on bone marrow DCs. Finally, inhaled allergen increased the percentage of cDC1s and cDC2s in BAL but only cDC2s in bronchial tissues.Inhaled allergen increases DCs in bone marrow and trafficking of DCs into the airway, which is associated with the development airway inflammation in subjects with allergic asthma. Inhaled allergen challenge also increases expression of TSLP, but not IL-33, receptors on bone marrow DCs.
View details for DOI 10.1164/rccm.201508-1623OC
View details for Web of Science ID 000381697500014
View details for PubMedID 26844926
Interleukin-25 and eosinophils progenitor cell mobilization in allergic asthma
CLINICAL AND TRANSLATIONAL ALLERGY
2018; 8: 5
Eosinophil-lineage committed progenitor cells (EoP) migrate from the bone marrow and differentiate locally to provide an ongoing source of mature eosinophils in asthmatic inflammatory responses in the airways. Sputum levels of EoP are increased in asthmatics compared to normal controls suggesting an exaggerated eosinophilopoietic environment in the airways. Understanding what factors promote EoP traffic to the airways is important to understand the diathesis of asthma pathology. Interleukin (IL)-25, is an epithelial-derived cytokine that promotes type 2 inflammatory responses. We have previously shown that levels of IL-25 and expression of the IL-25 receptor (IL-17RA and IL-17RB) on mature eosinophils are greater in allergic asthmatics compared to atopic non-asthmatics and non-atopic normal controls. In addition, these levels were increased significantly increased following allergen inhalation challenge and physiologically relevant levels of IL-25 stimulated eosinophil degranulation, intracellular IL-5 and IL-13 expression and primed migration to eotaxin. The current study, examined the role of IL-25 on allergen-induced trafficking of EoP in atopic asthmatics.Asthmatics (n = 14) who developed allergen-induced early and late responses were enrolled in the study. Blood was collected at pre- and 24 h post-challenge. At each time point, surface expression of IL-17RA and IL-17RB on EoP was evaluated by flow cytometry. Migration assays examined the effect of IL-25 on EoP chemotactic responses, in vitro. In addition, IL-25 knockout ovalbumin (OVA) sensitized and challenged mice were studied to evaluate in vivo mobilization effects of IL-25 on newly formed EoP and mature eosinophils.There was a significant increase in numbers of blood EoP expressing IL-17RB, 24 h post-allergen inhalation challenge in allergic asthmatics. Pre-exposure to IL-25 primed the migrational responsiveness of EoP to stromal cell-derived factor 1α. In OVA-sensitized mice, knocking out IL-25 significantly alleviated OVA-induced eosinophil infiltration in the airway and newly formed eosinophils were reduced in the lung.The findings of this study indicate a potential role for IL-25 in allergen-induced trafficking of EoP to the airways and local differentiation promoting tissue eosiniophilia in asthmatic responses.
View details for DOI 10.1186/s13601-018-0190-2
View details for Web of Science ID 000425297500001
View details for PubMedID 29456832
View details for PubMedCentralID PMC5809891
IL-33 and Its Receptor ST2 after Inhaled Allergen Challenge in Allergic Asthmatics.
International archives of allergy and immunology
2018; 176 (2): 133–42
Previous murine models have demonstrated interleukin (IL)-33 to be an important mediator of type-2 inflammation and to promote airway hyperresponsiveness in allergic asthma. A number of inflammatory cells produce IL-33 and eosinophils express ST2 mRNA. The relationship between IL-33 and eosinophils in allergic asthma, however, remains unclear.The aim of this work was to evaluate in vitro the effect of allergen inhalation on IL-33 levels and expression of its receptor (ST2L) on eosinophils in allergic asthmatics, and the effect of IL-33 stimulation on eosinophil activity.Plasma and sputum IL-33, soluble ST2 (sST2) levels, and ST2L expression on eosinophils were measured in 10 healthy controls and 10 allergic asthmatics. Asthmatics underwent allergen and diluent inhalation challenges. Blood and sputum samples were collected to measure IL-33, sST2, and ST2L eosinophil expression before and 24 h after allergen inhalation. Purified blood eosinophils from allergic asthmatics were incubated overnight with IL-33 to assess ST2 and intracellular IL-5 expression.Baseline levels of IL-33 in sputum and sST2 in plasma and sputum were similar in allergic asthmatics compared to healthy controls. In addition, there was no difference in blood or sputum eosinophil ST2L expression in healthy controls versus allergic asthmatics. Eosinophil ST2L expression was significantly increased 24 h postallergen inhalation in allergic asthmatics. In vitro stimulation of human eosinophils with IL-33 and LPS significantly increased eosinophil ST2L expression and IL-33 stimulation increased intracellular IL-5 expression, which was attenuated by treatment with sST2 and ST2 blockade.In mild asthmatics, there was a significant upregulation of ST2 surface expression on eosinophils from blood and sputum following allergen inhalation challenge. In vitro, IL-33 stimulation of eosinophils increases both ST2 membrane expression and IL-5 production. These results support a role for IL-33 in causing allergen-induced eosinophilia. Blockade of IL-33 and ST2 signaling may present a novel therapeutic avenue for asthma treatment.
View details for DOI 10.1159/000488015
View details for PubMedID 29694974
Allergen-induced Increases in Sputum Levels of Group 2 Innate Lymphoid Cells in Asthmatic Subjects.
American journal of respiratory and critical care medicine
Group 2 innate lymphoid cells (ILC2), a major source of type 2 cytokines, initiate eosinophilic inflammatory responses in murine models of asthma.To investigate the role of ILC2 in allergen-induced airway eosinophilic responses in subjects with atopy and asthma.Using a diluent-controlled allergen challenge crossover study, where all subjects (n = 10) developed allergen-induced early and late responses, airway eosinophilia, and increased methacholine airway responsiveness, bone marrow, blood, and sputum samples were collected before and after inhalation challenge.ILC2 (lin(-)FcεRI(-)CD45(+)CD127(+)ST2(+)) and CD4(+)T lymphocytes were enumerated by flow cytometry, as well as intracellular IL-5 and IL-13 expression. Steroid sensitivity of ILC2 and CD4(+) T cells was investigated in vitro. A significant increase in total, IL-5(+), IL-13(+), and CRTH2(+) ILC2 was found in sputum, 24 hours after allergen, coincident with a significant decrease in blood ILC2. Total, IL-5(+), and IL-13(+), but not CRTH2(+), CD4(+) T cells significantly increased at 24 and 48 hours after allergen in sputum. In blood and bone marrow, only CD4(+) cells demonstrated increased activation after allergen. Airway eosinophilia correlated with IL-5(+) ILC2 at all time points and allergen-induced changes in IL-5(+) CD4(+) cells at 48 hours after allergen. Dexamethasone significantly attenuated IL-2- and IL-33-stimulated IL-5 and IL-13 production by both cell types.Innate and adaptive immune cells are increased in the airways associated with allergic asthmatic responses. Total and type 2 cytokine-positive ILC2 are increased only within the airways, whereas CD4(+) T lymphocytes demonstrated local and systemic increases. Steroid sensitivity of both cells may explain effectiveness of this therapy in those with mild asthma.
View details for DOI 10.1164/rccm.201612-2427OC
View details for PubMedID 28422515
Glucagon-like peptide-1 receptor expression on human eosinophils and its regulation of eosinophil activation
CLINICAL AND EXPERIMENTAL ALLERGY
2017; 47 (3): 331-338
Glucagon-like peptide-1 (GLP-1) and its receptor are part of the incretin family of hormones that regulate glucose metabolism. GLP-1 also has immune modulatory roles.To measure the expression of the GLP-1 receptor (GLP-1R) on eosinophils and neutrophils in normal and asthmatic subjects and evaluate effects of a GLP-1 analog on eosinophil function.Peripheral blood samples were taken from 10 normal and 10 allergic asthmatic subjects. GLP-1R expression was measured on eosinophils and neutrophils. Subsequently, the asthmatic subjects underwent allergen and diluent inhalation challenges, and GLP-1R expression was measured. Purified eosinophils, collected from mild asthmatic subjects, were stimulated with lipopolysaccharide (LPS) and a GLP-1 analog to evaluate eosinophil cell activation markers CD11b and CD69 and cytokine (IL-4, IL-5, IL-8 and IL-13) production.Glucagon-like peptide-1 receptor is expressed on human eosinophils and neutrophils. Eosinophil, but not neutrophil, expression of GLP-1R is significantly higher in normal controls compared to allergic asthmatics. The expression of GLP-1R did not change on either eosinophils or neutrophils following allergen challenge. A GLP-1 analog significantly decreased the expression of eosinophil-surface activation markers following LPS stimulation and decreased eosinophil production of IL-4, IL-8 and IL-13, but not IL-5.Glucagon-like peptide-1 receptor is expressed on human eosinophils and neutrophils. A GLP-1 analog attenuates LPS-stimulated eosinophil activation. GLP-1 agonists may have additional adjunctive indications in treating persons with concomitant type 2 diabetes mellitus and asthma.
View details for DOI 10.1111/cea.12860
View details for Web of Science ID 000397337400005
View details for PubMedID 27928844
Comparative Outcome Analysis of Children Who Underwent Pyeloplasty for Ureteropelvic Junction Obstruction Associated With or Without Supranormal Differential Renal Function
2017; 99: 210-214
To compare pyeloplasty outcomes in children with and without "supra-normal" differential renal function (SNDRF) defined as >55% differential renal function (DRF) in children with ureteropelvic junction obstruction.Our prospectively collected pyeloplasty database (2008-2015) was reviewed (n = 151). A total of 140/151 (93%) patients had preoperative renograms and 26/140 (19%) were found to have SNDRF (DRF ≥ 55%). Of 151 patients, 51 (34%) had pre- and postoperative renograms allowing determination of change ≥5% in function. After excluding 2 patients with solitary kidneys, a total of 49 patients defined the study group.Of 49 patients, 12 had SNDRF and 37 did not. Baseline characteristics were similar including mean age at surgery (47.3 months vs 45.4 months) and time to surgery (8.7 months vs 9.8 months). Mean preoperative anteroposterior diameter was significantly different between groups (23.2 mm vs 31.0 mm; P = .04), but postoperative was similar (9.0 mm vs 12.1 mm; P = .14). Mean preoperative DRF was 60.2% in the SNDRF group vs 44.3% in the non-SNDRF. Mean postoperative DRF was 52.4% and 45.3%, respectively (P = .04). There were 9/12 (75%) SNDRF patients who experienced ≥5% loss in function compared to 2/37 (5%) in the non-SNDRF group (P < .01).Three-quarters of SNDRF patients demonstrated a decline of ≥5%DRF postoperatively when compared to non-SNDRF. This finding may not reflect true elevated renal function, but rather hyperfiltration in the setting of obstruction, which-if unrecognized as such-could result in postponing an otherwise beneficial surgical intervention.
View details for DOI 10.1016/j.urology.2016.07.016
View details for Web of Science ID 000396525000065
View details for PubMedID 27450350
Human Bronchial Epithelial Cell-Derived Factors from Severe Asthmatic Subjects Stimulate Eosinophil Differentiation.
American journal of respiratory cell and molecular biology
Activated bronchial epithelial cells release alarmins, including thymic stromal lymphopoietin (TSLP) that drive type 2 inflammatory responses. We hypothesize that bronchial epithelial-derived factors enhance in situ eosinophil differentiation and maturation from myeloid precursors, a process that is driven by an IL-5 rich micro-environment within asthma airways.To assess the eosinophilopoietic potential of epithelial-derived factors, eosinophil/basophil colony forming units (Eo/B-CFU) were enumerated in 14-day methylcellulose cultures of blood-derived mononuclear cells (NAMNCs) incubated with bronchial epithelial cell supernatants (BECSN) from healthy non-atopic controls (NC; n = 8), mild atopic asthmatics (MA; n = 9) and severe asthmatics (SA; n = 5). Receptor blocking antibodies were used to evaluate the contribution of alarmins. Modulation of mRNA expression of transcription factors crucial for eosinophil differentiation was evaluated.BECSN stimulated the clonogenic expansion of eosinophil progenitors, in vitro. In the presence of IL-5, Eo/B-CFU growth was significantly greater in co-cultures of BESCN from SA, compared to MA and NC. This effect was attenuated by a TSLP receptor blocking antibody but not by an ST2 antibody. Recombinant human TSLP (optimal at 100 pg/ml) stimulated significant Eo/B-CFU growth, which was significantly enhanced in presence of IL-5 (1 ng/ml). Overnight culture of CD34+ cells with IL-5 and TSLP synergistically increased GATA-2 and CEBP-alpha mRNA expression.The eosinophilopoietic potential of factors derived from bronchial epithelial cells is increased in severe asthma. Our data suggest that TSLP is a key alarmin produced by bronchial epithelial cells, which promotes in situ eosinophilopoiesis in a type 2 rich microenvironment.
View details for DOI 10.1165/rcmb.2016-0262OC
View details for PubMedID 28853918
Percent improvement in renal pelvis antero-posterior diameter (PI-APD): Prospective validation and further exploration of cut-off values that predict success after pediatric pyeloplasty supporting safe monitoring with ultrasound alone
JOURNAL OF PEDIATRIC UROLOGY
2016; 12 (4)
Renograms are frequently obtained post-pyeloplasty in patients with residual hydronephrosis to confirm adequate drainage. Recent evidence suggests that percent improvement in antero-posterior diameter (PI-APD) ≥38 is predictive of success. We sought to further explore PI-APD ranges that would allow identification of patients who would benefit from ultrasound (US) monitoring alone vs. post-operative renal scan, and those more likely to develop recurrent ureteropelvic junction obstruction (rUPJO).A single-center prospectively-collected pyeloplasty database (2008-2015) was queried (n = 151). Only patients with both pre- and post-operative APD measurements were included (n = 138). PI-APD was divided into 3 categories: <20%; 20-39%; ≥40%. The following variables were collected post-operatively: patients monitored with US alone, renogram and US, rUPJO and minimal or resolved hydronephrosis (SFU ≤2; UTD ≤1; APD ≤15 mm).Mean age at first and last follow-up were 4.8 (median 4.0; range 0-60) months and 26.6 (median 20.5; range 1-77) months, respectively. Of 138 patients, 84 (61%) had US alone, 54 (39%) had a renogram and US post-operatively, and 6 (4%) developed rUPJO. Of 84 patients who had US alone, 71 (84%; p < 0.01) demonstrated ≥40% PI-APD. Of 54 patients with renogram and US 46 (85%; p < 0.01) had ≥40 PI-APD. Of the 6 patients who developed rUPJO, all were in the <20 PI-APD group (100%; p < 0.01). Resolution of hydronephrosis according to SFU, UTD and APD occurred in 96/138 (70%), 89/138 (64%) and 113/138 (82%) patients respectively. Of these, 87 (91%), 81 (91%), and 108 (95%) occurred in >40% PI-APD group.≥40% PI-APD at the first post-operative visit strongly predicts pyeloplasty success, as up to 82% of these patients showed resolved hydronephrosis and 61% underwent non-invasive monitoring by US alone. Our data suggests that up to 85% of renograms may have been unnecessary. Finally, <20% PI-APD permitted identification of all rUPJO cases. Stratification of patients based in PI-APD is a promising strategy for further minimizing radiation exposure while safely detecting children at risk for rUPJO.
View details for DOI 10.1016/j.jpurol.2016.04.003
View details for Web of Science ID 000384668400034
View details for PubMedID 27448846
- Expression of activation markers in circulating basophils and the relationship to allergen-induced bronchoconstriction in subjects with mild allergic asthma JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY 2016; 137 (3): 936-938
IL-25 and IL-33 induce Type 2 inflammation in basophils from subjects with allergic asthma
The alarmin cytokines IL-25 and IL-33 are key promoters of type 2 inflammation. Basophils respond to alarmin cytokines, however the relationship of these cytokines with basophil activation and recruitment in human studies of allergic asthma has not been well characterized. This study investigated the effect of IL-25 and IL-33 on basophils in a model of allergic asthma.10 mild allergic asthmatics underwent allergen and diluent inhalation challenges. Bone marrow aspirates were collected at pre-challenge and 24 h (h) post challenge. Peripheral blood and sputum samples were collected at pre-challenge, 7 h, and 24 h post-challenge to measure basophil expression of IL-17RB, ST2, and intracellular IL-25. Freshly isolated peripheral blood basophils from allergic donors were incubated overnight with IL-25 and IL-33, or sputum supernatant collected post-allergen to assess pro-inflammatory effects of mediators released in the airways.There were increased percentage of basophils expressing IL-17RB, ST2, and intracellular IL-25 collected from bone marrow, peripheral blood, and sputum after allergen inhalation challenge. In vitro stimulation with IL-25 and IL-33 increased the percentage of basophils expressing intracellular type 2 cytokines and surface activation markers, and primed eotaxin-induced migratory potential of basophils, which was mediated directly through IL-17RB and ST2, respectively. Stimulation of basophils with sputum supernatants collected post-allergen challenge up-regulated the percentage of basophils expressing markers of activation and intracellular type 2 cytokines, which was reversed following blockade of the common β chain (βc).Our findings indicate that the alarmin cytokines IL-33 and IL-25 increase basophil activation and migratory potential, and may pose as a novel therapeutic targets for the treatment of allergic asthma.
View details for DOI 10.1186/s12931-016-0321-z
View details for Web of Science ID 000368122900001
View details for PubMedID 26762527
View details for PubMedCentralID PMC4712475
Increased numbers of activated group 2 innate lymphoid cells in the airways of patients with severe asthma and persistent airway eosinophilia
JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY
2016; 137 (1): 75-?
In patients with severe eosinophilic asthma, local maturation rather than systemic recruitment of mature cells might contribute to persistent airway eosinophilia. Group 2 innate lymphoid cells (ILC2s) are a major source of type 2 cytokines (IL-5 and IL-13) and can facilitate eosinophilic inflammatory responses in mouse models of asthma in the absence of CD4+ lymphocytes. This study investigated the potential role of ILC2s in driving chronic airway eosinophilia in patients with severe asthma, despite regular high-dose oral corticosteroid therapy.In a cross-sectional study we enumerated blood and sputum ILC2s (lin(-)CD45(+)127(+)ST2(+)) and levels of intracellular IL-5 and IL-13 in patients with severe asthma (n = 25), patients with steroid-naive mild atopic asthma (n = 19), and nonatopic control subjects (n = 5). Results were compared with numbers of CD4+ lymphocytes, eosinophil lineage-committed progenitors (eosinophilopoietic progenitor cells [EoPs]), and mature eosinophils.Significantly greater numbers of total and type 2 cytokine-producing ILC2s were detected in blood and sputum of patients with severe asthma compared to mild asthmatics. In contrast, intracellular cytokine expression by CD4 cells and EoPs within the airways did not differ between the asthmatic groups. In patients with severe asthma, although sputum CD4+ cells were more abundant than ILC2s and EoPs, proportionally, ILC2s were the predominant source of type 2 cytokines. In addition, there were significantly greater numbers of sputum IL-5(+)IL-13(+) ILC2s in patients with severe asthma whose airway eosinophilia was greater than 3%, despite normal blood eosinophil numbers (<300/μL).Our findings suggest that ILC2s can promote the persistence of airway eosinophilia in patients with severe asthma through uncontrolled localized production of the type 2 cytokines IL-5 and IL-13, despite high-dose oral corticosteroid therapy.
View details for DOI 10.1016/j.jaci.2015.05.037
View details for Web of Science ID 000367724300046
View details for PubMedID 26194544
Allergen-Induced Increases in Interleukin-25 and Interleukin-25 Receptor Expression in Mature Eosinophils from Atopic Asthmatics
INTERNATIONAL ARCHIVES OF ALLERGY AND IMMUNOLOGY
2016; 170 (4): 234-242
Interleukin (IL)-25 plays a pivotal role in type 2 immune responses. In a baseline cross-sectional study, we previously showed that IL-25 plasma levels and IL-25 receptor (IL-25R: IL-17RA, IL-17RB, and IL-17RA/RB) expression on mature blood eosinophils are increased in atopic asthmatics compared to normal nonatopic controls. This study investigated allergen-induced changes in IL-25 and IL-25R expression in eosinophils from asthmatics.Dual responder atopic asthmatics (n = 14) were enrolled in this randomized diluent-controlled crossover allergen challenge study. Blood was collected before and 24 h after the challenge. The surface expression of IL-25R was evaluated by flow cytometry on eosinophils and Th2 memory cells. In addition, plasma levels of IL-25 were measured by ELISA, and functional responses to IL-25 including type 2 cytokine expression, degranulation, and the migrational responsiveness of eosinophils were evaluated in vitro.Following the allergen but not the diluent inhalation challenge, significant increases in the expression of IL-17RB and IL-17RA/B were found on eosinophils but not on Th2 memory cells. IL-25 plasma levels and the number of eosinophils but not of Th2 memory cells expressing intracellular IL-25 increased significantly in response to the allergen but not the diluent challenge. Stimulation with physiologically relevant concentrations of IL-25 in vitro caused (i) degranulation of eosinophils (measured by eosinophil peroxidase release), (ii) enhanced intracellular expression of IL-5 and IL-13, and (iii) priming of eosinophil migration to eotaxin. IL-25 stimulated intracellular cytokine expression, and the migration of eosinophils was blocked in the presence of a neutralizing IL-25 antibody.Our findings suggest that the IL-25/IL-25R axis may play an important role in promoting the recruitment and proinflammatory function of eosinophils in allergic asthma.
View details for DOI 10.1159/000449248
View details for Web of Science ID 000388066200002
View details for PubMedID 27685606
Thymic stromal lymphopoietin activation of basophils in patients with allergic asthma is IL-3 dependent
JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY
2015; 136 (6): 1636-1644
Thymic stromal lymphopoietin (TSLP) released after antigenic stimulation of allergic asthmatic airways is a key initiator of type 2 inflammation. Basophils are important effectors of allergic inflammation in the airways. Murine basophils have been shown to respond to TSLP independently of IL-3 by increasing functional thymic stromal lymphopoietin receptor (TSLPR) expression.The purpose of this study was to investigate the effect of TSLP stimulation on human basophil function.Ten patients with mild allergic asthma underwent diluent and allergen inhalation challenges. Peripheral blood and sputum samples were collected at baseline and 7 and 24 hours after challenge, and bone marrow samples were collected at baseline and 24 hours after challenge to measure basophil TSLPR expression. In vitro experiments were conducted on purified human basophils to measure the effect of TSLP on degranulation, expression of activation markers and TH2 cytokines, and eotaxin-induced shape change.Allergen inhalation increased basophil numbers in the airways and significantly upregulated the expression of activation markers, TH2 intracellular cytokines, and receptors for TSLP, IL-3, and eotaxin in blood, bone marrow, and sputum basophils. In vitro stimulation with TSLP primed basophil migration to eotaxin and induced rapid and sustained basophil activation mediated directly through TSLPR and indirectly through an IL-3-mediated basophil autocrine loop. Basophils responded to TSLP at a similar magnitude and potency as the well-described basophil-activating stimuli IL-3 and anti-IgE.Our findings indicate that basophil activation during early- and late-phase responses to inhaled allergen might be driven at least in part by TSLP.
View details for DOI 10.1016/j.jaci.2015.03.039
View details for Web of Science ID 000366044300026
View details for PubMedID 25962901
Thymic stromal lymphopoietin and IL-33 modulate migration of hematopoietic progenitor cells in patients with allergic asthma
JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY
2015; 135 (6): 1594-1602
Thymic stromal lymphopoietin (TSLP) and IL-33 are considered important initiators of type 2 immunity. In asthmatic patients allergic inflammatory responses are associated with increased lung homing of bone marrow-derived CD34(+) hematopoietic progenitor cells (HPCs), which include eosinophil lineage-committed progenitor cells. In this study we investigated the role of TSLP and IL-33 in the recruitment of progenitor cells to the airways in asthmatic subjects.We sought (i) to examine the effect of allergen inhalation challenge on expression levels of receptors for TSLP (thymic stromal lymphopoietin receptor [TSLPR] and CD127) and IL-33 (ST2) and (ii) investigate the functional effects of these cytokines on HPCs.Consenting patients with mild atopic asthma (n = 19) with an FEV1 of 70% or greater and methacholine PC20 of 16 mg/mL or less were recruited. Blood- and sputum-extracted progenitors were phenotyped by flow cytometry before and 24 hours after allergen challenge. Functional responses, including cytokine production and migration to TSLP and IL-33, were assessed in vitro.Significant increases in mature eosinophil, HPC, and eosinophil lineage-committed progenitor cell counts in sputum were observed 24 hours after allergen and were associated with a significant allergen-induced increase in HPCs expressing TSLPR, CD127, and ST2. Pre-exposure to TSLP and IL-33 primed the migration of HPCs to a potent progenitor cell chemoattractant, stromal cell-derived factor 1α (CXCL12). Incubation with TSLP and IL-33 stimulated significant production of IL-5 and IL-13, but not IL-4, by HPCs. This priming effect was inhibited by blocking antibodies to TSLPR and ST2, respectively, and IL-13 receptor α1 in both scenarios.In allergic asthmatic responses increased lung homing of HPCs may be orchestrated by TSLP and IL-33 through an IL-13-dependent axis.
View details for DOI 10.1016/j.jaci.2014.12.1918
View details for Web of Science ID 000355933400023
View details for PubMedID 25656998
THE PROFESSIONAL BENEFITS FOR VOLUNTEER RESEARCH ASSISTANTS IN A PEDIATRIC EMERGENCY DEPARTMENT
JOURNAL OF EMERGENCY MEDICINE
2015; 48 (3): 287-293
Emergency departments (EDs) have utilized university student volunteers to facilitate enrollment of patients into prospective studies; however, the impact of this experience on participant careers is relatively unknown.We determined the proportion of successful postgraduate school/research job applications supported by our program reference letter. We also examined participant satisfaction.This was a prospective cohort study of volunteer research assistants in a tertiary care pediatric ED from September 2011 to July 2013. Students volunteered one 5-h shift per week for at least 6 months. They completed three surveys: 1) Entrance - demographics and goals for entering the ED research assistant program; 2) Exit - program satisfaction, reasons for leaving the program, and future career goals; 3) Follow-up - survey and e-mails were sent to record positions secured since leaving the program.There were a total of 920 applicants over the study period, and 127 volunteers were selected to participate in the program. Response rates for entrance, exit, and follow-up surveys were 100%, 84.9%, and 96.2%, respectively. Of the participants who left and responded, 89/101 (88.9%) obtained school/research positions supported by our program reference letter. Further, 72.6% ranked their satisfaction with the program at least a 7 on a 10-point categorical scale, and 82.9% reported that they "agreed/strongly agreed" that the program helped with their career goals.A volunteer student program is in high demand for university students interested in health sciences/research and potentially has a beneficial career impact for its participants.
View details for DOI 10.1016/j.jemermed.2014.06.038
View details for Web of Science ID 000350581300009
View details for PubMedID 25271184
THE EFFECTIVENESS OF A STUDENT VOLUNTEER PROGRAM FOR RESEARCH IN A PEDIATRIC EMERGENCY DEPARTMENT
JOURNAL OF EMERGENCY MEDICINE
2015; 48 (1): 19-25
Emergency Department (ED) student-based research assistant programs have been shown to be effective in enrolling patients when the students receive university course credit or pay. However, the impact on research outcomes when university students act as volunteers in this role is relatively unknown.The main objective of this study was to determine how often potentially eligible children were accurately identified by volunteer research assistants for enrollment into prospective research in the ED. We also examined the frequency of successful enrollments and the accuracy of data capture.This was a prospective cross-sectional study of university student volunteer research assistant performance in a tertiary care pediatric ED between March 2011 and July 2013. The participant's primary role was to screen and facilitate enrollment of ED patients into clinical research. For each volunteer, we recorded demographics, number of screenings, enrollments, and data capture accuracy.Over five 6-month sessions, 151 student volunteers participated. Of these, 77.3% were female, 58.8% were undergraduate students, and 61.1% were interested in medical school. Student volunteers accurately screened 11,362/13,067 (87.0%) children, and they accurately identified 4407/4984 (88.4%) potentially eligible children for study enrollment. Of the 3805 eligible for enrollment exclusively by the students, 3228 (84.8%) families/children consented and completed all study procedures. Furthermore, students correctly entered 11,660/12,567 (92.8%) data points.Utilizing university student volunteers to facilitate research enrollment in the ED is effective and allows for the capture of a high percentage of potentially eligible patients into prospective clinical research studies.
View details for DOI 10.1016/j.jemermed.2014.06.039
View details for Web of Science ID 000346857000011
View details for PubMedID 25271177
Evaluation of peroxisome proliferator-activated receptor agonists on interleukin-5-induced eosinophil differentiation
2014; 142 (3): 484-491
Peroxisome proliferator-activated receptor (PPAR) agonists have been suggested as novel therapeutics for the treatment of inflammatory lung disease, such as allergic asthma. Treatment with PPAR agonists has been shown to inhibit airway eosinophilia in murine models of allergic asthma, which can occur through several mechanisms including attenuated generation of chemoattractants (e.g. eotaxin) and decreased eosinophil migrational responses. In addition, studies report that PPAR agonists can inhibit the differentiation of several cell types. To date, no studies have examined the effects of PPAR agonists on interleukin-5 (IL-5) -induced eosinophil differentiation from haemopoietic progenitor cells. Non-adherent mononuclear cells or CD34(+) cells isolated from the peripheral blood of allergic subjects were grown for 2 weeks in Methocult(®) cultures with IL-5 (10 ng/ml) and IL-3 (25 ng/ml) in the presence of 1-1000 nm PPARα agonist (GW9578), PPARβ/δ agonist (GW501516), PPARγ agonist (rosiglitazone) or diluent. The number of eosinophil/basophil colony-forming units (Eo/B CFU) was quantified by light microscopy. The signalling mechanism involved was assessed by phosphoflow. Blood-extracted CD34(+) cells cultured with IL-5 or IL-5 + IL-3 formed Eo/B CFU, which were significantly inhibited by rosiglitazone (100 nm, P < 0·01) but not GW9578 or GW501516. In addition, rosglitazone significantly inhibited IL-5-induced phosphorylation of extracellular signal-regulated kinase 1/2. We observed an inhibitory effect of rosiglitazone on eosinophil differentiation in vitro, mediated by attenuation of the extracellular signal-regulated kinase 1/2 signalling pathway. These findings indicate that the PPARγ agonist can attenuate tissue eosinophilia by interfering with local differentiative responses.
View details for DOI 10.1111/imm.12280
View details for Web of Science ID 000337600500017
View details for PubMedID 24628018
View details for PubMedCentralID PMC4080964
Do obese children experience more severe fractures than nonobese children? A cross-sectional study from a paediatric emergency department
PAEDIATRICS & CHILD HEALTH
2014; 19 (5): 251-255
To determine whether there is an association between childhood obesity and severe extremity fractures. Associations between obesity and complications related to the fracture and/or fracture management were also examined.The present study was a retrospective, cross-sectional study conducted at a tertiary care children's emergency department. Eligible cases for review were children (two to 17 years of age) with an extremity fracture. Severe extremity fractures were defined as those requiring manipulation under anesthesia, open operative repair and/or admission to hospital. The primary outcome was the proportion of severe extremity fractures and the secondary outcome was the proportion of complications.A total of 1340 charts of children who presented with extremity fracture from January 2008 to December 2010 were reviewed. The mean (± SD) age of the study population was 9.1±4.0 years and 62.1% were male. Overall, 19.9% (95% CI 17.8% to 22.0%) were obese and 39.6% (95% CI 36.7% to 39.1%) sustained a severe extremity fracture. The OR of severe extremity fractures among obese versus nonobese children was 1.00 (95% CI 0.76 to 1.32), adjusted for age, sex and mechanism of injury. In addition, the OR of experiencing complications among obese relative to nonobese children was 1.12 (95% CI 0.68 to 1.85).The results of the present study demonstrated that in children with extremity fractures, obese children were not at increased risk for sustaining more severe extremity fractures or subsequent complications compared with nonobese children.
View details for Web of Science ID 000336047600007
View details for PubMedID 24855428
View details for PubMedCentralID PMC4029229
Inhibition of Allergen-Induced Basophil Activation by ASM-024, a Nicotinic Receptor Ligand
INTERNATIONAL ARCHIVES OF ALLERGY AND IMMUNOLOGY
2014; 165 (4): 255-264
Nicotinic acetylcholine receptors (nAChRs) were identified on eosinophils and shown to regulate inflammatory responses, but nAChR expression on basophils has not been explored yet.We investigated surface receptor expression of nAChR α4, α7 and α1/α3/α5 subunits on basophils. Furthermore, we examined the effects of ASM-024, a synthetic nicotinic ligand, on in vitro anti-IgE and in vivo allergen-induced basophil activation.Basophils were enriched from the peripheral blood of allergic donors and the expression of nAChR subunits and muscarinic receptors was determined. Purified basophils were stimulated with anti-IgE in the presence of ASM-024 with or without muscarinic or nicotinic antagonists for the measurement of CD203c expression and histamine release. The effect of 9 days of treatment with 50 and 200 mg ASM-024 on basophil CD203c expression was examined in the blood of mild allergic asthmatics before and after allergen inhalation challenge.nAChR α4, α7 and α1/α3/α5 receptor subunit expression was detected on basophils. Stimulation of basophils with anti-IgE increased CD203c expression and histamine release, which was inhibited by ASM-024 (10(-5) to 10(-)(3) M, p < 0.05). The effect of ASM-024 was reversed in the presence of muscarinic and nicotinic antagonists. In subjects with mild asthma, ASM-024 inhalation significantly inhibited basophil CD203c expression measured 24 h after allergen challenge (p = 0.03).This study shows that ASM-024 inhibits IgE- and allergen-induced basophil activation through both nicotinic and muscarinic receptors, and suggests that ASM-024 may be an efficacious agent for modulating allergic asthma responses.
View details for DOI 10.1159/000370068
View details for Web of Science ID 000349233000005
View details for PubMedID 25660404