IL-33 and Its Receptor ST2 after Inhaled Allergen Challenge in Allergic Asthmatics

BACKGROUND

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.

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION AND CLINICAL RELEVANCE

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.

Allergen-induced Increases in Sputum Levels of Group 2 Innate Lymphoid Cells in Subjects with Asthma

RATIONALE

Group 2 innate lymphoid cells (ILC2), a major source of type 2 cytokines, initiate eosinophilic inflammatory responses in murine models of asthma.

OBJECTIVES

To investigate the role of ILC2 in allergen-induced airway eosinophilic responses in subjects with atopy and asthma.

METHODS

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.

MEASUREMENTS AND MAIN RESULTS

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.

CONCLUSIONS

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.

Allergen-induced Changes in Bone Marrow and Airway Dendritic Cells in Subjects with Asthma

RATIONALE

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.

OBJECTIVES

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.

METHODS

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.

MEASUREMENTS AND MAIN RESULTS

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.

CONCLUSIONS

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.

Utilising magnetic resonance imaging as the gold-standard in management of suspected scaphoid fractures in the emergency department setting

Scaphoid fractures are the most common carpal bone fracture. Up to 40% of scaphoid fractures can be missed at initial presentation and investigation. Follow-up plain film radiograph has overall poor sensitivity and reliability. MRI has been shown to have an almost 100% sensitivity and specificity and so is the gold standard in scaphoid fracture diagnosis. Additionally, early specialist involvement is recommended. We proposed that following a designated pathway, there would be no significant increase in MRI requests. Following implementation of a pathway for the management of suspected scaphoid fractures in St James's Hospital in 2012 re-auditing demonstrated that management changed to either MRI directly after initial x-ray (16/145, 11%), MRI after second x-ray (9/28, 32%) or orthopaedic follow-up (19/28, 68%). The number of MRIs requested was consistent with our predictors of demand. Thus, our new protocol maximises diagnostics, cost effectiveness and quality of patient care.

Glucagon-like peptide-1 receptor expression on human eosinophils and its regulation of eosinophil activation

BACKGROUND

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.

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSION AND CLINICAL RELEVANCE

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.

Comparison of arterial and venous blood gases and the effects of analysis delay and air contamination on arterial samples in patients with chronic obstructive pulmonary disease and healthy controls

BACKGROUND

Arterial blood gases (ABGs) are often sampled incorrectly, leading to a 'mixed' or venous sample. Delays in analysis and air contamination are common.

OBJECTIVES

We measured the effects of these errors in patients with chronic obstructive pulmonary disease (COPD) exacerbations and controls.

METHODS

Arterial and venous samples were analyzed from 30 patients with COPD exacerbation and 30 controls. Venous samples were analysed immediately and arterial samples separated into non-air-contaminated and air-contaminated specimens and analysed at 0, 30, 60, 90 and 180 min.

RESULTS

Mean venous pH was 7.371 and arterial pH was 7.407 (p < 0.0001). There was a correlation between venous and arterial pH (r = 0.5347, p < 0.0001). The regression equation to predict arterial pH was: arterial pH = 4.2289 + 0.43113 · venous pH. There were no clinically significant differences in arterial PO₂ associated with analysis delay. A statistically significant decline in pH was detected at 30 min in patients with COPD exacerbation (p = 0.0042) and 90 min in controls (p < 0.0001). A clinically significant decline in pH emerged at 73 min in patients with COPD exacerbation and 87 min in controls. Air contamination was associated with a clinically significant increase in PO₂ in all samples, including those that were immediately analyzed.

CONCLUSIONS

Arterial and venous pH differ significantly. Venous pH cannot accurately replace arterial pH. Temporal delays in ABG analysis result in a significant decline in measured pH. ABGs should be analysed within 30 min. Air contamination leads to an immediate increase in measured PO₂, indicating that air-contaminated ABGs should be discarded.

Characteristics of patients presenting with erythema nodosum and sarcoidosis

We explored the relationship between erythema nodosum (EN) and sex, age, serum angiotensin converting enzyme (ACE), bronchoalveolar lavage lymphocytosis (BAL-I), interstitial granulomas and radiological stage in patients presenting with pulmonary sarcoidosis in Ireland. Sixty-nine patients diagnosed with sarcoidosis between 2003 and 2006 were studied. Forty one patients (59%) were male. Sixteen patients (23%) presented with EN. Forty one patients of 65 (63%) had transbronchial biopsies demonstrating non-caseating granulomas. Patients with sarcoidosis presenting with EN were more likely to be female (p=0.042), younger (p=0.012) and have earlier stage pulmonary disease (p=0.02). There were no correlations between serum ACE, interstitial granulomas and disease stage. BAL-I did however predict increasing disease radiological stage (p=0.042). In this study, one quarter of patients with sarcoidosis presented with EN among their presenting features. These patients were more likely to be young females with early stage radiological disease.

Further evidence for the rising incidence of childhood Type 1 diabetes in Kuwait

AIMS

To provide age-gender standardized incidence rate, temporal trend and seasonal variation of Type 1 diabetes in Kuwaiti children aged < or = 14 years.

METHODS

Data were prospectively collected over a period of 6 years (1992-1997) according to the DiaMond Project protocol using the capture-recapture method of ascertainment.

RESULTS

Data ascertainment varied between 90% and 96%. The incidence rate of Type 1 diabetes was 20.1 per 100,000 children 0-14 years (95% confidence interval (CI) 18.0-22.1); age-standardized incidence rate 20.9 (95% CI 18.8-23.0). The incidence rate among boys, 21.1 per 100,000 (95% CI 18.1-24.1) was slightly higher than that among girls, 19.0 per 100,000 (95% CI 16.1-21.8). The age-standardized incidence rate was 21.9 (95% CI 18.9-24.8) in boys, and 19.9 (95 CI 17.1-22.8) in girls. Incidence rates increased with age in both sexes (boys chi(2) for linear trend = 13.5, P < 0.001; and for girls chi(2) = 27.8, P < 0.0001). There was a significant trend towards increase in overall incidence during the 6-year period (chi(2) = 6.210, P = 0.013), and in age group 5-9 (chi(2) = 10.8, P = 0.001). Seasonality was demonstrated overall, in boys and girls (P < 0.001).

CONCLUSION

The incidence of Type 1 diabetes in Kuwait is high compared with the neighbouring Arab countries, and it appears to be increasing as in many European populations.

Evaluation of the clinical usefulness of C. difficile toxin testing in hospitalized patients with diarrhea

Although numerous studies have evaluated the sensitivity and specificity of different assays for Clostridium difficile toxin, none has evaluated how physicians utilize these tests or respond to test results. Therefore, we assessed patient characteristics, clinical findings, and physician responses to positive and negative assay results at two university-affiliated hospitals, one of which used a cell cytotoxicity assay to test for C. difficile toxin and the other of which used an enzyme immunoassay. Two hundred one patient samples at Hospital A and 199 samples at Hospital B were assessed. Positive toxin assays were more frequent at Hospital A than at Hospital B (p < 0.001), at least in part due to the fact that patients tested at Hospital A were more likely to have fever (p < 0.001), an abnormal abdominal exam (p < 0.001), an abnormal leukocyte count (p < 0.001), and a history of prior antibiotic use (p < 0.001). Empiric therapy for C. difficile before results of the toxin assay was more common (p < 0.001) at Hospital A (83/201, 41. 3%) than at Hospital B (25/199, 12.5%). Once empiric therapy was started, most physicians continued therapy despite negative test results (Hospital A, 76%; Hospital B, 69%). Patients who were treated empirically were more likely than patients not treated empirically to have positive toxin assay results and to have fever (p < 0.001), an abnormal abdominal exam (p = 0.003), or an abnormal leukocyte count (p < 0.05). Physicians seldom ordered repeat toxin assays (Hospital A, 14%; Hospital B, 10%) if the initial assay result was negative. In logistic regression analysis, predictors of a positive toxin assay were prior antibiotic therapy, an abnormal abdominal exam, residence at Hospital A, and age >/= 60 years. Predictors of empiric therapy were residence at Hospital A and prior antibiotic therapy. Because physicians electing to empirically treat inpatients with diarrhea rarely alter therapy based on C. difficile toxin assay results, a more cost-effective management strategy may be not to obtain a toxin assay at all in such situations. Testing should be limited to patients who have received antibiotics within the prior month and who have significant diarrhea and/or abdominal pain.

RANTES chemokine expression is related to acute cardiac cellular rejection and infiltration by CD45RO T-lymphocytes and macrophages

BACKGROUND

Despite the advances made in immunosuppression therapy, episodes of acute cellular rejection may affect graft function and survival. We investigated the role of RANTES in cellular recruitment and in cardiac allograft rejection.

METHODS

Endomyocardial biopsies (n = 65) from 30 patients were taken at various times after transplantation. In 4 subjects who died of acute cellular rejection, the profile of RANTES expression was monitored in all biopsy specimens and in postmortem tissue. Myocardial tissue from 10 other transplants was also analyzed. Sections were stained with an anti-human RANTES antibody with the streptavidin-biotin technique. RANTES-positive cells were related to macrophage, CD45RO "memory" T-cell, and eosinophil infiltration.

RESULTS

RANTES-positive cells were identified within the cellular infiltrate in 95% of biopsies with moderate/severe rejection and 28% with mild rejection. RANTES-positive, CD45RO-positive, and macrophage cell numbers were higher in subjects who died of acute cellular rejection than of other causes. A highly significant difference in RANTES-positive cell number was observed between moderate/severe, mild, and nonrejection groups (p = .0001) and correlated significantly with macrophage number in both right and left ventricles (r = .693, p < .01; r = .599, p < .05, respectively) and with the number of "memory" T cells (r = .829, p < .001; r = .779, p < .01, respectively).

CONCLUSIONS

These findings suggest that local release of RANTES is important in the recruitment of both macrophages and CD45RO T cells in cardiac allograft rejection. RANTES may be an important chemokine to target for therapeutic intervention in heart rejection.