Update in asthma 2011

Spatial and Temporal Mapping of Human Innate Lymphoid Cells Reveals Elements of Tissue Specificity

Innate lymphoid cells (ILC) play critical roles in regulating immunity, inflammation, and tissue homeostasis in mice. However, limited access to non-diseased human tissues has hindered efforts to profile anatomically-distinct ILCs in humans. Through flow cytometric and transcriptional analyses of lymphoid, mucosal, and metabolic tissues from previously healthy human organ donors, here we have provided a map of human ILC heterogeneity across multiple anatomical sites. In contrast to mice, human ILCs are less strictly compartmentalized and tissue localization selectively impacts ILC distribution in a subset-dependent manner. Tissue-specific distinctions are particularly apparent for ILC1 populations, whose distribution was markedly altered in obesity or aging. Furthermore, the degree of ILC1 population heterogeneity differed substantially in lymphoid versus mucosal sites. Together, these analyses comprise a comprehensive characterization of the spatial and temporal dynamics regulating the anatomical distribution, subset heterogeneity, and functional potential of ILCs in non-diseased human tissues.

Antiasthmatic Effects of Sanglong Pingchuan Decoction through Inducing a Balanced Th1/Th2 Immune Response

Objective

To investigate the antiasthmatic effects of Sanglong pingchuan decoction (SLPCD) and to explore its mechanisms of action.

Methods

The serum, bronchoalveolar lavage fluid (BALF), and lung tissues from OVA-induced allergic asthma mice were collected 24 h after the last administration. Lung pathological changes were observed by H&E staining. The inflammatory cells in BALF were counted by flow cytometry. The levels of total IgE in serum and cytokines in BALF were determined by ELISA. The expression levels of cytokine mRNA in lung were assayed by qRT-PCR.

Results

SLPCD significantly inhibited airway inflammation, reduced inflammatory cells in BALF, reduced the levels of total IgE in serum and Th2 cytokines (IL-10 and IL-13) in BALF, and downregulated the mRNA expression levels of Th2 cytokines (IL-4, IL-5, IL-10, and IL-13) in lung of asthmatic mice. However, SLPCD remarkably elevated the level of Th1 cytokine IFN-γ in BALF and upregulated the mRNA expression levels of Th1 cytokines (IL-2 and IFN-γ) in lung of asthmatic mice.

Conclusion

SLPCD could attenuate airway inflammation and alleviate the pathogenesis in asthma mice through inducing a balanced Th1/Th2 response and could act as an effective drug for treatment of asthma.

Association between Asthma and Autism Spectrum Disorder: A Meta-Analysis

Objective

We conducted a meta-analysis to summarize the evidence from epidemiological studies of the association between asthma and autism spectrum disorder (ASD).

Methods

A literature search was conducted using PubMed, Embase, and Cochrane library for studies published before February 2nd, 2016. Observational studies investigating the association between asthma and ASD were included. A random effects model was used to calculate the pooled risk estimates for the outcome. Subgroup analysis was used to explore potential sources of heterogeneity and publication bias was estimated using Begg's and Egger's tests.

Results

Ten studies encompassing 175,406 participants and 8,809 cases of ASD were included in this meta-analysis. In the cross-sectional studies, the prevalence of asthma in ASD was 20.4%, while the prevalence of asthma in controls was 15.4% (P < 0.001). The pooled odds ratio (OR) for the prevalence of asthma in ASD in the cross-sectional studies was 1.26 (95% confidence interval (CI): 0.98–1.61) (P = 0.07), with moderate heterogeneity (I² = 65.0%, P = 0.02) across studies. In the case-control studies, the pooled OR for the prevalence of asthma in ASD was 0.98 (95% CI: 0.68–1.43) (P = 0.94), and there was no evidence of an association between asthma and ASD. No evidence of significant publication bias on the association between asthma and ASD was found.

Conclusions

In conclusion, the results of this meta-analysis do not suggest an association between asthma and ASD. Further prospective studies ascertaining the association between asthma and ASD are warranted.

Co-occurrence of autism and asthma in a nationally-representative sample of children in the United States

Few large epidemiological studies have examined the co-occurrence of autism and asthma. We performed a cross-sectional study to examine this association using the 2007 National Survey of Children's Health dataset (n = 77,951). We controlled for confounders and tested for autism-secondhand smoke interaction. Prevalence of asthma and autism were 14.5 % (n = 11,335) and 1.81 % (n = 1,412) respectively. Unadjusted odds ratio (OR) for asthma among autistic children was 1.35 (95 % CI 1.18-1.55). Adjusting for covariates (age, gender, body mass index, race, brain injury, secondhand smoke and socio-economic status) attenuated the OR to 1.19 (95 % CI 1.03-1.36). Autism-secondhand smoke interaction was insignificant (p = 0.38). Asthma is approximately 35 % more common in autistic children; screening may be an efficient approach to reduce risk of morbidity due to asthma.

Usefulness of noninvasive methods for the study of bronchial inflammation in the control of patients with asthma

Bronchial asthma is one of the most prevalent respiratory conditions. Although it is defined as an inflammatory disease, the current guidelines for both diagnosis and follow-up of patients are based only on clinical and lung function parameters. Current research is focused on finding markers that can accurately predict future risk, and on assessing the ability of these markers to guide medical treatment and thus improve prognosis. The use of noninvasive methods to study airway inflammation is gaining increasing support. The study of eosinophils in induced sputum has proved useful for the diagnosis of asthma; however, its clinical implementation is complex. Some studies have shown that the measurement of exhaled nitric oxide (FeNO) may also be useful to establish disease phenotypes and improve control. Others have found that the measurement of pH and certain markers of oxidative stress, cytokines and prostanoids in exhaled breath condensate (EBC) may also be useful as well as the measurement of the temperature of exhaled breath and the analysis of volatile organic compounds (VOCs). In conclusion, since asthma is an inflammatory disease, it seems appropriate to try to control it through the study of airway inflammation using noninvasive methods. In this regard, the analysis of induced sputum cells has proved very useful, although the clinical implementation of this technique seems difficult. Other techniques such as temperature measurement, the analysis of FeNO, the analysis of the VOCs in exhaled breath, or the study of certain biomarkers in EBC require further study in order to determine their clinical applicability.

Utility of Asthma Control Questionnaire 7 in the assessment of asthma control

Our objective was to evaluate the reproducibility of Asthma Control Questionnaire 7 (ACQ-7) in asthma patients, comparing our results against those obtained with the Global Initiative for Asthma (GINA) criteria. We evaluated 52 patients. Patients completed the ACQ-7, underwent spirometry, and were clinically assessed to determine the level of asthma control according to the GINA criteria, in two visits, 15 days apart. The ACQ-7 cutoff for uncontrolled asthma was a score of 1.5. The ACQ-7 showed good reproducibility, with a correlation coefficient of 0.73. The ACQ-7 identified a greater number of patients with uncontrolled asthma than did the GINA criteria; according to the GINA criteria, 47 patients (90.4%) presented with partially controlled asthma.

Noninvasive quantification of airway inflammation following segmental allergen challenge with functional MR imaging: a proof of concept study

PURPOSE

To evaluate oxygen-enhanced T1-mapping magnetic resonance (MR) imaging as a noninvasive method for visualization and quantification of regional inflammation after segmental allergen challenge in asthmatic patients compared with control subjects.

MATERIALS AND METHODS

After institutional review board approval, nine asthmatic and four healthy individuals gave written informed consent. MR imaging (1.5 T) was performed by using an inversion-recovery snapshot fast low-angle shot sequence before (0 hours) and 6 hours and 24 hours after segmental allergen challenge by using either normal- or low-dose allergen or saline. The volume of lung tissue with increased relaxation times was determined by using a threshold-based method. As a biomarker for oxygen transfer from the lungs into the blood, the oxygen transfer function ( OTF oxygen transfer function ) was calculated. After the third MR imaging examination, eosinophils in bronchoalveolar lavage fluid were counted. Differences between times and segments were analyzed with nonparametric Wilcoxon matched-pairs test and Spearman correlation.

RESULTS

In lung segments treated with the standard dose of allergen, the OTF oxygen transfer function was decreased at 6 hours in asthmatic patients, compared with saline-treated segments (P = .0078). In asthmatic patients at 24 hours, the volume over threshold was significantly increased in normal allergen dose-treated segments compared with saline-treated segments (P = .004). In corresponding lung segments, the volume over threshold at 24 hours in the asthmatic group showed a positive correlation (r = 0.65, P = .0001) and the OTF oxygen transfer function at 6 hours showed an inverse correlation (r = -0.67, P = .0001) with the percentage of eosinophils in the bronchoalveolar lavage fluid.

CONCLUSION

OTF oxygen transfer function and volume over threshold are noninvasive MR imaging-derived parameters to visualize and quantify the regional allergic reaction after segmental endobronchial allergen challenge.

Impact of endobronchial allergen provocation on macrophage phenotype in asthmatics

Background

The role of M2 polarized macrophages (MΦ) during the allergic airway inflammation has been discussed in various animal models. However, their presence and relevance during the chronic and acute phase of allergic airway inflammation in humans has not been fully elucidated so far. In the present study we phenotypically characterized macrophages with regard to M2 polarization in mice, a human in vitro and a human ex vivo model with primary lung cells after endobronchial provocation.

Results

Macrophages remained polarized beyond clearance of the acute allergic airway inflammation in mice. Alveolar macrophages of asthmatics revealed increased mRNA expression of CCL13, CCL17 and CLEC10A in response to allergen challenge as well as increased surface expression of CD86. Further, mRNA expression of CCL13, CCL17, and CLEC10A was increased in asthmatics at baseline compared to healthy subjects. The mRNA expression of CCL17 and CLEC10A correlated significantly with the degree of eosinophilia (each P < .01). Furthermore, macrophages from asthmatics released significant amounts of CCL17 protein in vitro which was also found increased in BAL fluid after allergen provocation.

Conclusions

This study supports previous findings of M2 macrophage polarization in asthmatic subjects during the acute course of the allergic inflammation and provides evidence for their contribution to the Th2 inflammation.

Allergenicity and toxicology of inhaled silver nanoparticles in allergen-provocation mice models

Silver nanoparticles (AgNP) have been associated with the exacerbation of airway hyperresponsiveness. However, the allergenicity and toxicology of AgNP in healthy and allergic individuals are unclear. We investigated the pathophysiological responses to AgNP inhalation in a murine model of asthma. Continuous and stable levels of 33 nm AgNP were maintained at 3.3 mg/m³ during the experimental period. AgNP exposure concomitant with ovalbumin challenge increased the enhanced pause (Penh) in the control and allergic groups. AgNP evoked neutrophil, lymphocyte and eosinophil infiltration into the airways and elevated the levels of allergic markers (immunoglobulin E [IgE] and leukotriene E₄ [LTE₄]), the type 2 T helper (Th2) cytokine interleukin-13 (IL-13), and oxidative stress (8-hydroxy-2′-deoxyguanosine [8-OHdG]) in healthy and allergic mice. Bronchocentric interstitial inflammation was observed after AgNP inhalation. After inhalation, the AgNP accumulated predominantly in the lungs, and trivial amounts of AgNP were excreted in the urine and feces. Furthermore, the AgNP induced inflammatory responses in the peritoneum. The inhalation of AgNP may present safety concerns in healthy and susceptible individuals.

Human immunodeficiency virus-associated obstructive lung diseases

In the era of effective antiretroviral therapy (ART), epidemiologic studies have found that persons infected with human immunodeficiency virus (HIV) have a higher prevalence and incidence of chronic obstructive pulmonary disease than HIV-uninfected persons. In comparison with HIV-uninfected persons and those with well-controlled HIV disease, HIV-infected persons with poor viral control or lower CD4 cell count have more airflow obstruction, a greater decline in lung function, and possibly more severe diffusing impairment. This article reviews the evidence linking HIV infection to obstructive lung disease, and discusses management issues related to the treatment of obstructive lung disease in HIV-infected patients.

Cyclical mechanical stretch enhances degranulation and IL-4 secretion in RBL-2H3 mast cells

Mast cells are widely distributed in the body and affect their surrounding environment through degranulation and secretion of cytokines. Conversely, mast cells are influenced by environmental stimuli such as cyclical mechanical stretch (CMS), such as that induced by heartbeat and respiration. Peripherally distributed mast cells are surrounded by extracellular matrix, where they bind IgE on their surface by expressing the high-affinity Fc receptor for IgE (FcεRI), and they release mediators after cross-linking of surface-bound IgE by allergen. To analyse how CMS affects mast cell responses, we examined the effect of applying CMS on the behaviour of IgE-bound mast cells (RBL-2H3 cell line) adhering to fibronectin as a substitute for extracellular matrix. We found that CMS enhanced FcεRI-mediated secretion in the presence of antigen (2,4-dinitrophenol-bovine serum albumin). CMS increased expression of IL-4 mRNA and secretion of IL-4 protein. Western blot analysis showed that CMS changes the signal transduction in mitogen-activated protein kinases and AKT, which in turn alters the regulation of IL-4 and increases the secretion of IL-4. These results suggest that CMS modulates the effect of mast cells on inflammation and resultant tissue remodelling. Understanding how CMS affects mast cell responses is crucial for developing therapies to treat mast cell-related diseases.