Inflammation in allergic asthma: initiating events, immunological response and risk factors

Saururus chinensis-controlled allergic pulmonary disease through NF-κB/COX-2 and PGE2 pathways

Saururus chinensis is a perennial herb found in the northeastern regions of Asia, including Korea, China, and Japan, and is used in traditional medicine. Studies have identified the four major constituents in Saururus chinensis water extract (LHF618^®) as miquelianin (11.75 ± 0.092 mg/g), rutin (1.20 ± 0.008 mg/g), quercitrin (2.38 ± 0.389 mg/g), and quercetin (0.068 ± 0.017 mg/g). Saururus chinensis can improve the symptoms of ovalbumin- or fine dust-induced allergic pulmonary disease by suppressing the effects of WBCs and neutrophils in BALF and IgE in the serum. Saururus chinensis dose-dependently recovered morphological changes such as mucous hyper secretion (from 2.7 ± 0.46 to 0.6 ± 0.65), pulmonary epithelial cell hyperplasia (from 2.4 ± 0.55 to 0.7 ± 0.67), and inflammatory cell infiltration (from 2.3 ± 0.45 to 0.6 ± 0.43), and effectively controlled cDNA levels and protein levels of IL-13. It inhibited NF-κB translocation and COX-2 protein synthesis and suppressed the expression of PGE₂. Our results show that Saururus chinensis controlled allergic pulmonary disease via the anti-inflammatory pathways, NF-κB/COX-2 and PGE₂. Saururus chinensis may be a promising drug candidate against fine dust-induced allergic pulmonary disease.

Lycium barbarum Polysaccharide Extracted from Lycium barbarum Leaves Ameliorates Asthma in Mice by Reducing Inflammation and Modulating Gut Microbiota

This study was designed to explore the impact of Lycium barbarum polysaccharide (LBP) on inflammation and gut microbiota in mice with allergic asthma. Mice were divided into four groups: control group, OVA (ovalbumin) group, Con+LBP group, OVA+LBP group. After 28 days of LBP intervention, mice were euthanized and associated indications were investigated. Histopathological examination demonstrated that LBP reduced lung injury. The results of our current study provide evidence that supplementation with LBP in asthmatic mice decreases TNF, IL-4, IL-6, MCP-1, and IL-17A in plasma and bronchoalveolar lavage fluid (BALF). Sequencing and analysis of gut microbiota indicated that compared with the OVA group, Lactobacillus and Bifidobacterium were increased, but Firmicutes, Actinobacteria, Alistipes, and Clostridiales were decreased in the OVA+LBP group. We also found that gut microbiota were related to inflammation-related factors. Therefore, we speculate that LBP may improve allergic asthma by altering gut microbiota and inhibiting inflammation in mice.

Mangiferin suppresses allergic asthma symptoms by decreased Th9 and Th17 responses and increased Treg response

Mangiferin is the major bioactive ingredient in the leaves of Mangifera indica L., Aqueous extract of such leaves have been traditionally used as an indigenous remedy for respiratory diseases including cough and asthma in Traditional Chinese Medicine. Mangiferin was shown to exert its anti-asthmatic effect by modulating Th1/Th2 cytokines imbalance via STAT6 signaling pathway. However, compelling evidence indicated that subtypes of T helpers and regulatory T cells other than Th1/Th2 were also involved in the pathogenesis of asthma. In current study, we investigated the effects of mangiferin on the differentiation and function of Th9, Th17 and Treg cells in a chicken egg ovalbumin (OVA)-induced asthmatic mouse model. Mangiferin significantly attenuated the symptoms of asthma attacks, reduced the total number of leukocytes, EOS and goblet cells infiltration in lung. Simultaneously, treatment with mangiferin remarkably decreased the proportion of Th9 and Th17 cells; reduced the levels of IL-9, IL-17A; inhibited the expression of PU.1 and RORγt in lung. However, the proportion of Treg cells, the expression of IL-10, TGF-β1 and Foxp3 were increased by mangiferin. Our data suggest that mangiferin exerted anti-asthmatic effect through decreasing Th9 and Th17 responses and increasing Treg response in OVA-induced asthmatic mouse model.

Incidence and risk factors for exacerbations of asthma during pregnancy

Background

Asthma is one of the most common chronic diseases among pregnant women. Acute exacerbations of asthma during pregnancy have an unfavorable impact on pregnancy outcome. This review provides an overview of current knowledge of incidence, mechanisms, and risk factors for acute exacerbations of asthma during pregnancy.

Methods

A narrative literature review was carried out using the PubMed database.

Results

During pregnancy, up to 6% of women with asthma are hospitalized for an acute exacerbation. The maternal immune system is characterized by a very high T-helper-2:T-helper-1 cytokine ratio during pregnancy and thereby provides an environment essential for fetal survival but one that may aggravate asthma. Cells of the innate immune system such as monocytes and neutrophils are also increased during pregnancy, and this too can exacerbate maternal asthma. Severe or difficult-to-control asthma appears to be the major risk factor for exacerbations during pregnancy, but studies also suggest that nonadherence with controller medication and viral infections are important triggers of exacerbations during pregnancy. So far, inconsistent findings have been reported regarding the effect of fetal sex on exacerbations during pregnancy. Other risk factors for exacerbation during pregnancy include obesity, ethnicity, and reflux, whereas atopy does not appear to be a risk factor.

Discussion

The incidence of asthma exacerbations during pregnancy is disturbingly high. Severe asthma – better described as difficult-to-control asthma – nonadherence with controller therapy, viral infections, obesity, and ethnicity are likely to be important risk factors for exacerbations of asthma during pregnancy, whereas inconsistent findings have been reported with regard to the importance of sex of the fetus.

Zinc-rich inhibitor of apoptosis proteins (IAPs) as regulatory factors in the epithelium of normal and inflamed airways

Integrity of the airway epithelium (AE) is important in the context of inhaled allergens and noxious substances, particularly during asthma-related airway inflammation where there is increased vulnerability of the AE to cell death. Apoptosis involves a number of signaling pathways which activate procaspases leading to cleavage of critical substrates. Understanding the factors which regulate AE caspases is important for development of strategies to minimize AE damage and airway inflammation, and therefore to better control asthma. One such factor is the essential dietary metal zinc. Zinc deficiency results in enhanced AE apoptosis, and worsened airway inflammation. This has implications for asthma, where abnormalities in zinc homeostasis have been observed. Zinc is thought to suppress the steps involved in caspase-3 activation. One target of zinc is the family of inhibitor of apoptosis proteins (IAPs) which are endogenous regulators of caspases. More studies are needed to identify the roles of IAPs in regulating apoptosis in normal and inflamed airways and to study their interaction with labile zinc ions. This new information will provide a framework for future clinical studies aimed at monitoring and management of airway zinc levels as well as minimising airway damage and inflammation in asthma.

1'-Acetoxychavicol acetate isolated from Alpinia galanga ameliorates ovalbumin-induced asthma in mice

The World Health Organization reports that 235 million people are currently affected by asthma. This disease is associated with an imbalance of Th1 and Th2 cells, which results in the upregulation of cytokines that promote chronic inflammation of the respiratory system. The inflammatory response causes airway obstruction and can ultimately result in death. In this study we evaluated the effect of 1'-acetoxychavicol acetate (ACA) isolated from Alpinia galanga rhizomes in a mouse model of ovalbumin (OVA)-induced asthma. To generate the mouse model, BALB/c mice were sensitized by intraperitoneal injection of OVA and then challenged with OVA inhalation for 5 days. Mice in the vehicle control group were sensitized with OVA but not challenged with OVA. Treatment groups received dexamethasone, 25 mg/kg/day ACA, or 50 mg/kg/day ACA for 5 days. Asthma-related inflammation was assessed by bronchoalveolar lavage fluid cell counts and histopathological and immunohistochemical analysis of lung tissues. Our results showed that ACA reduced the infiltration of white blood cells (especially eosinophils) and the level of IgE in the lungs of mice challenged with OVA and suppressed histopathological changes such as airway remodeling, goblet-cell hyperplasia, eosinophil infiltration, and glycoprotein secretion. In addition, ACA inhibited expression of the Th2 cytokines interleukin (IL)-4 and IL-13, and Th1 cytokines IL-12α and interferon-γ. Because asthmatic reactions are mediated by diverse immune and inflammatory pathways, ACA shows promise as an antiasthmatic drug candidate.

The Tec family kinase, IL-2-inducible T cell kinase, differentially controls mast cell responses

The Tec family tyrosine kinase, IL-2-inducible T cell kinase (Itk), is expressed in T cells and mast cells. Mice lacking Itk exhibit impaired Th2 cytokine secretion; however, they have increased circulating serum IgE, but exhibit few immunological symptoms of allergic airway responses. We have examined the role of Itk in mast cell function and FcepsilonRI signaling. We report in this study that Itk null mice have reduced allergen/IgE-induced histamine release, as well as early airway hyperresponsiveness in vivo. This is due to the increased levels of IgE in the serum of these mice, because the transfer of Itk null bone marrow-derived cultured mast cells into mast cell-deficient W/W(v) animals is able to fully rescue histamine release in the W/W(v) mice. Further analysis of Itk null bone marrow-derived cultured mast cells in vitro revealed that whereas they have normal degranulation responses, they secrete elevated levels of cytokines, including IL-13 and TNF-alpha, particularly in response to unliganded IgE. Analysis of biochemical events downstream of the FcepsilonRI revealed little difference in overall tyrosine phosphorylation of specific substrates or calcium responses; however, these cells express elevated levels of NFAT, which was largely nuclear. Our results suggest that the reduced mast cell response in vivo in Itk null mice is due to elevated levels of IgE in these mice. Our results also suggest that Itk differentially modulates mast cell degranulation and cytokine production in part by regulating expression and activation of NFAT proteins in these cells.

Differential sensitivity to Itk kinase signals for T helper 2 cytokine production and chemokine-mediated migration

Allergic asthma is dependent on chemokine-mediated Th2 cell migration and Th2 cytokine secretion into the lungs. The inducible T cell tyrosine kinase Itk regulates the production of Th2 cytokines as well as migration in response to chemokine gradients. Mice lacking Itk are resistant to developing allergic asthma. However, the role of kinase activity of Itk in the development of this disease is unclear. In addition, whether distinct Itk-derived signals lead to T cell migration and secretion of Th2 cytokines is also unknown. Using transgenic mice specifically lacking Itk kinase activity, we show that active kinase signaling is required for control of Th2 responses and development of allergic asthma. Moreover, dominant suppression of kinase Itk activity led to normal Th2 responses, but significantly reduced chemokine-mediated migration, resulting in prevention of allergic asthma. These observations indicate that signals required for Th2 responses and migration are differentially sensitive to Itk activity. Manipulation of Itk's activity can thus provide a new strategy to treat allergic asthma by differentially affecting migration of T cells into the lungs, leaving Th2 responses intact.

Immunoglobulin E blockade in the treatment of asthma

Patients with moderate-to-severe asthma often have persistent symptoms despite aggressive pharmacotherapy, enthusiastic patient compliance, and proper technique in using delivery devices. Persistent symptoms have detrimental effects on patients' quality of life and result in a tremendous financial burden because of an increased utilization of health care resources. Guidelines from the National Asthma Education and Prevention Program list symptom prevention, near-normal lung function, and participation in activities (e.g., school, work) as goals of successful asthma therapy. The development of pharmacologic and biologic therapies that target different aspects of airway inflammation will help patients with persistent asthma symptoms achieve these goals. Immunoglobulin E (IgE) is increasingly recognized as a key component of asthma pathophysiology and contributes to both the early- and late-phase inflammatory cascade of the airways by inhibiting allergen-induced activation of mast cells. Both epidemiologic and clinical evidence support the use of IgE blockade for asthma treatment. Omalizumab is currently the only IgE-targeted therapy approved by the United States Food and Drug Administration for asthma treatment. The drug improves symptoms, reduces exacerbations, and improves quality of life in certain patient populations.

Many asthma patients experience persistent symptoms despite appropriate clinical and guideline-based treatment with inhaled corticosteroids

PURPOSE

To review possible reasons for persistence of asthma symptoms despite appropriate use of clinical and guideline-based treatments, including the use of inhaled corticosteroids.

DATA SOURCES

Review of the worldwide scientific literature on factors related to persistent symptoms in patients with asthma.

CONCLUSIONS

Patients with asthma may not respond as expected to therapy because of factors that include poor adherence, improper inhaler technique, persistent exposure to symptom triggers, and limitations of current standard therapy, including steroid insensitivity or the steroid plateau effect. Persistent symptoms may also be associated with IgE-mediated airway inflammation, as current standard asthma therapies do not directly address the IgE-mediated component of the inflammatory cascade. Asthma is a complex disease and its treatment requires the full cooperation and participation of the patient.

IMPLICATIONS FOR PRACTICE

Healthcare professionals can play a key role by educating patients and their family members about the nature of asthma and rationale for treatment, supporting the importance of strict adherence to prevention measures and the prescribed treatment regimen.

The impact of comorbid atopic disease on asthma: clinical expression and treatment

Clinically, asthma and allergic rhinitis involve separate regions of the respiratory tract while representing a common underlying inflammatory syndrome. Much evidence supports an epidemiologic association between the diseases, paranasal sinus involvement in both conditions, and parallel relationship in severity and treatment outcomes. Pathophysiologic mechanisms, including immunoglobulin E (IgE)- mediated inflammation, are also shared. Blocking IgE with the recombinant humanized monoclonal antibody omalizumab demonstrated clinical efficacy in patients with upper and lower airway diseases. IgE blockade, leukotriene modulation, and B-cell depletion therapy have all exhibited success in chronic inflammation, reinforcing and expanding the beneficial role of immunomodulation of global mediators.

Treatment strategies for reducing asthma-related emergency department visits

Acute asthma exacerbations reflect inadequate long-term disease control. Treatment to control acute asthma exacerbations includes: 1) rapid reversal of airflow obstruction with bronchodilators and systemic corticosteroids and reversing hypoxemia with oxygen in the emergency department (ED); 2) preventing early relapse by prescribing beta(2) agonists and oral corticosteroids at discharge and ensuring patients have an adequate supply of their other asthma medications; and 3) preventing future asthma exacerbations and ED visits through effective treatment in primary care. This article discusses each treatment and reviews the role of emergency physicians in treating patients to reverse airflow obstruction and prevent early relapse, future exacerbations, and ED visits by communicating the need for additional asthma control to patients' primary care physicians.

Sexually dimorphic effects of maternal asthma during pregnancy on placental glucocorticoid metabolism and fetal growth

Human pregnancy is associated with sexually dimorphic differences in mortality and morbidity of the fetus with the male fetus experiencing the poorest outcome following complications such as pre-eclampsia, pre-term delivery and infection. The physiological mechanisms that confer these differences have not been well characterised in the human. Work conducted on the effect of maternal asthma during pregnancy, combining data collected from the mother, placenta and fetus has found some significant sex-related mechanistic differences associated with fetal growth in both normal pregnancies and pregnancies complicated by asthma. Specifically, sexually dimorphic differences have been found in placental glucocorticoid metabolism in male and female fetuses of normal pregnancies. In response to the presence of maternal asthma, only the female fetus alters placental glucocorticoid metabolism resulting in decreased growth. The male fetus does not alter placental function or growth in response to maternal asthma. As a result of the alterations in glucocorticoid metabolism in the female, downstream changes occur in pathways regulated by glucocorticoids. These data suggest that the female fetus adjusts placental function and reduces growth to compensate for maternal disease. However, the male fetus continues to grow in response to maternal asthma with no changes in placental function. This response by the male fetus may partially contribute to the increased risk of morbidity and mortality in this sex.