Obesity is an important global health issue for both children and adults. Obesity increases the prevalence and incidence of asthma and also increases the risk for severe asthma. Here we describe the features of severe asthma phenotypes for which obesity is a defining characteristic, including steroid resistance, airway inflammation, and co-morbidities. We also review current concepts regarding the mechanistic basis for the impact of obesity in severe asthma, including possible roles for vitamin D deficiency, systemic inflammation, and the microbiome. Finally, we describe data indicating a role for diet, weight loss, and exercise in the treatment of severe asthma with obesity. Better understanding of the mechanistic basis for the role of obesity in severe asthma could lead to new therapeutic options for this population.
Asthma is a highly prevalent heterogeneous inflammatory disorder of the airways. Not all patients respond to anti-inflammatory treatment with corticosteroids, leading to significant morbidity in severe asthma. Much attention has been paid to defining the cellular and molecular mechanisms of type 2 inflammation that are operative in asthma. Development of targeted therapies for pathologic type 2 inflammation is opening a new approach to asthma treatment; however, not all asthmatics have type 2 airway inflammation, especially those with severe corticosteroid-refractory asthma. Much less is known about non-type 2 immunological mechanisms in asthma. In health, inflammation triggers resolution mechanisms that control immune (type 1 and type 2) responses and enable the restoration of tissue homeostasis. The resolution response is comprised of cellular and molecular events, including production of specialized pro-resolving mediators (SPMs). SPMs halt leukocyte recruitment, promote macrophage efferocytosis, and restore epithelial barrier integrity, all of which are critical to resolution of inflammation in the lungs. Here, we review recent insights into the disruption of these homeostatic mechanisms and their contributions to non-type 2 inflammation in severe asthma immunopathogenesis.
Severe asthma in children is associated with significant morbidity. Children with severe asthma are at increased risk for adverse outcomes including medication-related side effects, life-threatening exacerbations, and impaired quality of life. It is important to differentiate between severe therapy resistant asthma and difficult-to-treat asthma due to comorbidities. The most common problems that need to be excluded before a diagnosis of severe asthma can be made are poor medication adherence, poor medication technique or incorrect diagnosis of asthma. Difficult to treat asthma is a much more common reason for persistent symptoms and exacerbations and can be managed if comorbidities are clearly addressed. Children with persistent symptoms and exacerbations despite correct inhaler technique and good medical adherence to standard Step 4 asthma therapies according to the guidelines1,2, should be referred to an asthma specialist with expertise in severe asthma.
Asthma is a heterogeneous disease with considerable variability noted in disease severity, patterns of airway inflammation, and achievement of disease control on current medications. An absence of disease control is most frequently noted in patients with severe asthma, and is defined as a lack of control while on high dose inhaled corticosteroids (ICS) plus a second controller medication. In part, this lack of control may relate to a diminished effect of current guideline-directed care on the existing pattern of airway inflammation in severe asthma.
Airway inflammation in severe asthma has been arbitrarily divided into T (type) 2 high and T2 low. T2 high is characterized by the generation of key cytokines, interleukin (IL)-4, −5 and −13, which generate and regulate airway inflammation. Biomarkers to mark the presence of T2-high inflammation include eosinophils, fractional exhaled nitric oxide (FeNO) and immunoglobulin (Ig) E, whose presence arises from the action of IgE, IL-5, IL-4, and IL-13. In this review, treatment of severe asthma with monoclonal antibodies, i.e. biologics, which are directed against these inflammation generated pathways are reviewed. The available monoclonal antibodies include omalizumab (anti-IgE); mepolizumab, reslizumab and benralizumab (anti-IL-5 pathways), and dupilumab (anti-IL-4/IL-13).
The use of these T2-high interventions has led to significant reductions in asthma symptoms, a decreased frequency of exacerbations, and improved lung function in many patients. Not only has the use of these monoclonal antibodies led to improved asthma control in patients with severe disease, their use has provided insight into mechanisms of severe asthma.
The characteristic phenotype of severe asthma in Japan seems to be distilled into the following two features: low incidence of obesity and high prevalence of patients with type 2 inflammation. Only 5–7% of Japanese severe asthma patients had a body mass index (BMI) ≥30 kg/m2, and more than 80% of patients with severe asthma exhibited type 2 inflammation. Although the relationship between obesity and non-type 2 inflammation is complex, the low incidence of obesity might explain the prevalence of type 2 inflammation.
Some asthma cohorts in Japan have investigated the roles of type 2 biomarkers extensively, including periostin, to identify a severe phenotype, suggesting the utility of combining biomarkers to identify an exacerbation-prone subgroup.
Although the prevalence of severe asthma is comparable to Western countries, the rate of asthma death and disease burden seems to be lower in Japan. These trends might be due to the system of public health insurance for the whole nation, leading to good access to hospital and asthma specialists due to the geographically narrow country.
In this review article, we will discuss the definition, epidemiology, comorbidities, biomarkers, specific phenotype, and current treatment for severe asthma in Japan.
The season of birth and ultraviolet B exposure have been related to the occurrence of food allergy. The levels of vitamin D produced from skin by ultraviolet B exposure might reflect this relationship. Vitamin D is known to induce antimicrobial peptides, protect intestinal flora, enhance the gut epithelial barrier, suppress mast cell activation and IgE synthesis from B cells, and increase the number of tolerogenic dendritic cells and IL-10-producing regulatory T cells. Vitamin D deficiency has been shown to exacerbate sensitization and allergic symptoms in a murine model of food allergy. However, in clinical situations, contradictory observations have been reported regarding the relationship between food allergy and vitamin D deficiency/supplementation. In this review, we have explored the links between food allergy and vitamin D levels. One explanation for the discrepant findings is confounding factors such as race, age, residency, skin color, and epigenetic changes that contribute to vitamin D levels. In addition, the season of birth influences the development of atopic dermatitis, which could lead to food sensitization. Finally, ultraviolet radiation could lead to regulatory T cell expansion and immunosuppression, irrespective of vitamin D status. Based on our current understanding, we believe that correction of vitamin D deficiency by supplementation, appropriate skin care, and sufficient ultraviolet radiation exposure could alter the prognosis of food allergy. To identify potential treatment strategies for food allergy, it is essential to gain a better understanding of the appropriate levels of vitamin D and ultraviolet radiation exposure.
Background: Non-IgE-mediated gastrointestinal food allergies (non-IgE-GI-FAs) are one type of food allergy found in neonates and infants. Few reports have defined the severity of non-IgE-GI-FAs in these populations.
Methods: Grading scales of the severity of non-IgE-GI-FAs according to extra-GI symptoms, such as poor weight gain, as well as systemic symptoms, including fever and shock, were developed and retrospectively applied to patients with non-IgE-GI-FAs. The relationship between the severity of non-IgE-GI-FAs and both clinical and laboratory findings were examined.
Results: Elevation of C-reactive protein levels and a decrease in total protein and albumin were observed in accordance with allergy severity. In an endoscopic examination, inflammatory findings were confirmed in large areas of the colonic mucosa in case of higher severity levels, and infiltration of inflammatory cells other than eosinophils was found in the severest grade. Extensively hydrolyzed milk or amino acid-based milk was required for all patients with the severest grade. In addition, the timing of acquiring tolerance tended to be late for this grade.
Conclusions: Classification and determination of the severity of non-IgE-GI-FAs in neonates and infants may not only contribute to elucidation of the pathogenesis but may also be useful in the clinical setting.
Background: Atopic dermatitis (AD) influences a child's emotional and social well-being, as well as his or her physical health. The influence of AD on the daily lives of parents and caregivers has also been documented. This study examined how parenting stress is affected by demographic background, characteristics of children's AD, and their family systems.
Methods: The participants were mothers of children, aged 2–6 years old, who had been diagnosed with AD. The predictive power of a model of parenting stress was examined using multiple regression analysis (stepwise), with parenting stress (PSI-SF) as the dependent variable, and children's demographics, including characteristics of AD; parents' demographics; QoL of families of children with AD (JCMV-CADIS); and family functioning (FAI) as independent variables. We handled missing values using a multiple imputation method.
Results: The pooled coefficients obtained from the multiple regression analysis after multiple imputation indicated that “family cohesion,” “family system flexibility,” “emotions related to social factors” and “occupation of mother” determined parenting stress. Lower family cohesion and family system flexibility predicted higher parenting stress. The high impact of “emotions related to social factors” on families' QoL predicted higher parenting stress. Full-time work by mothers predicted lower parenting stress.
Conclusions: The current results reveal that “family cohesion,” “family system flexibility,” “emotions related to social factors” and “full-time work by mothers” predicted parenting stress of mothers who had children with AD.
Background: We obtain summary estimates of the accuracy of additional objective tests for the diagnosis of adult asthma using systematic review and meta-analysis of diagnostic test accuracy studies.
Methods: Medline, Embase, and other relevant electronic databases were searched for papers published between January 1989 and December 2016. Studies were included if they evaluated the diagnostic accuracy of objective tests, including airway reversibility (AR), airway hyperresponsiveness (AHR), and fractionated exhaled nitric oxide (FeNO) for the diagnosis of adult asthma in patients with symptoms suggestive of asthma. If papers were assessed appropriate using the adapted QUADAS-2 tool, meta-analysis was conducted using the hierarchical bivariate model. This hierarchical model accounts for both within and between study variability.
Results: Sixteen studies reported the performance of the evaluated objective tests at presentation. For diagnosis of adult asthma, overall sensitivity and specificity for AR were 0.39 (95% confidence interval [CI] 0.18 to 0.66) and 0.95 (95% CI 0.86 to 1.00); for AHR, 0.86 (95% CI 0.61 to 1.00) and 0.95 (95% CI 0.77 to 1.00); for FeNO, 0.65 (95% CI 0.53 to 0.77) and 0.83 (95% CI 0.75 to 0.90). Comprehensive comparison of three diagnostic tools for adult asthma using the back-calculated likelihood rate (LR) showed that AR and AHR corresponded to a higher LR+, and AHR gave a lower LR-.
Conclusions: In the current situation of no gold standard for diagnosis of adult asthma, AR and AHR are appropriate for ruling-in the true diagnosis, and AHR is superior for ruling-out a diagnosis. Since each objective test had a specific characteristic, it should be chosen depending on the situation, such as the capacity of the institution and the conditions of patients.
Background: Although non-IgE-mediated gastrointestinal food allergy has increased rapidly in Japan, a small number of reports has evaluated B-mode and Doppler ultrasonographic findings in the acute phase of infantile gastrointestinal milk allergy. The aim of the present study was to compare the diagnostic utility of ultrasonographic findings and laboratory allergic data in non-IgE-mediated infantile gastrointestinal milk allergy.
Methods: Sixteen cases of active non-IgE-mediated infantile gastrointestinal milk allergy, diagnosed by food elimination tests and oral food challenge tests (OFCTs) (group A), 15 cases of acute viral gastroenteritis (AGE) (group B), and 15 controls (group C) were enrolled. 1) B-mode abdominal ultrasound findings, 2) laboratory allergic data including eosinophil counts (Eos), serum IgE, and the antigen-specific lymphocyte proliferation test (ALPT) against milk protein, and 3) vessel density (VD) indirectly quantified by gastrointestinal Doppler flow at jejunum, ileum, and sigmoid colonic mucosae were evaluated and compared among the groups.
Results: In the small intestine, wall thickening, dilation, mesenteric thickening, and poor peristalsis were found in 100%, 62.5%, 93.7%, and 100%, respectively, in group A. Eos, IgE, ALPT, and VD were positive in 25.0%, 0%, 87.5%, and 100%, respectively, in group A. Small intestinal VD was significantly greater in group A than in groups B (jejunum p < .001; ileum p < .001) and C (jejunum p < .001; ileum p < .001), with no significant differences between groups B and C (jejunum: p = .74; ileum: p = .73).
Conclusions: Abdominal Doppler ultrasonography and small intestinal VD at symptomatic state can support the diagnosis and evaluation of non-IgE-mediated infantile gastrointestinal milk allergy with symptoms of vomiting, diarrhea, and failure to thrive.
Background: Rupatadine is a novel non-sedating second-generation H1-antihistamine with antiplatelet-activating factor activity, first marketed in Spain in 2003. It is used for treating allergic rhinitis in more than 80 countries. This study investigated its efficacy and safety in Japanese patients with seasonal allergic rhinitis (SAR).
Methods: This was a randomized, placebo-controlled, double-blind study conducted at 4 medical institutions in Japan (JapicCTI-152785). Adolescent and adult SAR outpatients aged 12–64 years entered a 1-week placebo run-in period. After eligibility was confirmed, patients orally received placebo, rupatadine 10 mg, or 20 mg once daily for 2 weeks. The primary endpoint was a change from baseline to second week of treatment in total 4 nasal symptom score (T4NSS).
Results: Nine hundred patients were randomly assigned to placebo, rupatadine 10 mg, or rupatadine 20 mg (302, 298, and 300 patients, respectively). The least squares mean difference in the primary endpoint between rupatadine and placebo was −1.085 for 10 mg, and −1.415 for 20 mg (analysis of covariance, both P < 0.001). The rates of adverse events were 6.6%, 14.1%, and 15.0% for placebo, rupatadine 10 mg, and rupatadine 20 mg, respectively. Somnolence was most frequently reported: 7.0% for rupatadine 10 mg and 7.3% for rupatadine 20 mg. No serious adverse drug reactions were observed, and no adverse events resulted in premature discontinuation.
Conclusions: Rupatadine 10 and 20 mg were significantly superior to placebo in improving nasal and ocular symptoms of SAR, and were well tolerated.
Background: IgG4 production is regulated by type 2 (IL-4 and IL-13) and regulatory (IL-10) cytokines involved in the pathophysiology of chronic rhinosinusitis (CRS). We sought to determine the pathophysiological characteristics of IgG4-positive cells in sinonasal tissues in CRS, especially eosinophilic CRS (ECRS).
Methods: IgG4-positive cells in uncinate tissues (UT) and nasal polyps (NP) were examined by immunohistochemistry. Associations between the number of IgG4-positive cells and clinicopathological factors were analyzed. Receiver operating characteristics (ROC) analysis was performed to determine the cut-off value of IgG4-positive cells in tissue that can predict the post-operative course.
Results: IgG4 was mainly expressed in infiltrating plasma and plasmacytoid cells, and the number of IgG4-positive cells was significantly higher in NP, especially those from severe ECRS patients, than in UT. In CRS patients, the number of IgG4-positive cells significantly and positively correlated with blood and tissue eosinophilia, radiological severity, and serum level of total IgE. The number of infiltrating IgG4-positive cells was significantly higher in patients with a poor post-operative course (sustained sinus shadow 6 months after surgery) than in those with a good one. The number of IgG4-positive cells in NP could discriminate patients with a good or a poor post-operative course (area under the curve: 0.769). Also, 73.3% sensitivity and 82.5% specificity were achieved when the cut-off value was set at 17 cells/high-power field.
Conclusions: Our results suggest that the local expression of IgG4 on cells may be used as a biomarker that reflects the pathophysiology of CRS, including the post-operative course.
Background: In Eosinophilic chronic rhinosinusitis (ECRS), it is difficult to estimate the refractoriness and recurrence risk for each patient. Fraction of exhaled nitric oxide (FeNO) is known as a biomarker of eosinophilic inflammation in lower airway. It has been reported that nasal NO has some crucial functions in the upper and lower airways. However, in upper airway, paranasal sinuses, the usefulness of NO measurement remains controversial. The purpose of this study is to identify the usefulness of nasal NO measurement in ECRS and the involvement of nasal NO in the pathogenesis of ECRS.
Methods: We compared the nasal NO levels of ECRS, non-ECRS, and normal control groups. Correlation between nasal NO levels and clinical findings were observed. Then, we compared nasal NO levels before and after endoscopic sinus surgery (ESS). We also examine whether nasal NO levels might discriminate ECRS by the receiver operating characteristic (ROC) curve analysis.
Results: Nasal NO levels were significantly decreased in ECRS compared to the other two groups. Moreover, nasal NO levels in ECRS significantly and negatively correlated with eosinophil levels and CT score. However, they did not correlate with the nasal polyp score. Nasal NO levels were not upregulated soon after opening the sinus ostium by ESS. The ROC curves for nasal NO levels were used to discriminate all CRS patients and ECRS patients from normal controls.
Conclusions: Nasal NO may be useful as a marker of ECRS severity and low nasal NO levels in ECRS may contribute to its pathogenesis.
Background: To investigate the potential roles of periostin (POSTN), an extracellular matrix preferentially expressed in Th2-skewed conditions in the pathophysiology of allergic conjunctivitis.
Methods: The roles of POSTN in ragweed-induced experimental allergic conjunctivitis (RW-EAC) were evaluated using both POSTN-knockout (KO) and congenic BALB/c wild-type mice. Histological analysis was carried out to enumerate eosinophils/basophils in the conjunctival tissue. Th2 cytokine expression was evaluated by quantitative polymerase chain reaction (Q-PCR), and microarray analysis was performed to elucidate genes differentially expressed in POSTN-KO and wild-type mice in the RW-EAC model.
Results: Upregulation of POSTN expression and eosinophil infiltration was observed in subconjunctival tissue of RW-EAC in the wild-type mice. The number of infiltrating eosinophils in the conjunctivae of RW-EAC was diminished in POSTN-KO mice compared to wild-type mice. Q-PCR analysis of conjunctival tissue showed induction of Th2 cytokine (Ccl5, Il4, Il5, Il13) expression in the RW-EAC and attenuated Ccl5, Il4, Il13 mRNA expression in the conjunctivae of the RW-EAC using POSTN-KO mice. Microarray analysis and immunohistochemical analysis showed diminished basophil marker (Mcpt8) expression and reduced numbers of infiltrating basophils in the conjunctivae of RW-EAC in POSTN-KO mice.
Conclusions: POSTN expression in conjunctival tissue plays an indispensable role in the late-phase reaction of the RW-EAC model by facilitating eosinophil/basophil infiltration and augmenting Th2 cytokine expression.
Background: Several cross-sectional studies have suggested an association between obesity and asthma. However, few studies have investigated this relationship longitudinally, especially in middle-aged subjects. Although metabolic syndrome is a well-known risk factor for many non-communicable diseases, its contribution to asthma remains controversial.
Methods: From 2008, specific health checkups for metabolic syndrome have been conducted throughout Japan. To seek relationships of obesity and metabolic syndrome with late-onset asthma in Japan, we analyzed data collected from health insurance claims and specific health checkups for metabolic syndrome at three large health insurance societies. Among subjects aged 40–64 years (n = 9888), multivariate logistic regression analyses were performed to investigate the relationships of obesity and metabolic syndrome in fiscal year 2012 (from April 2012 to March 2013) with the incidence of late-onset asthma in the following two years (from April 2013 to March 2015).
Results: In women, BMI 25–29.9 kg/m2 or ≥30 kg/m2, waist circumference ≥90 cm, and waist-to-height ratio ≥0.5 were shown to be significant risk factors for asthma, with adjusted odds ratios (95% CI) of 1.92 (1.35–2.75), 2.24 (1.23–4.09), 1.89 (1.30–2.75), and 1.53 (1.15–2.03), respectively. Significance was retained even after adjustment for metabolic syndrome, and there were no significant relationships between metabolic syndrome itself and the incidence of asthma in men or women.
Conclusions: Only the obesity measures, not metabolic syndrome, were shown to be significant risk factors for the incidence of late-onset asthma but only in middle-aged Japanese women, and not in men.
Background: Aspirin enhances food allergy symptoms by increasing absorption of ingested allergens. The objective of this study is to elucidate the role of aspirin in facilitating intestinal absorption of the wheat allergen, gliadin, in rats.
Methods: Plasma concentrations of gliadin were determined after oral administration by gavage or administration into a closed intestinal loop in rats. We used an in situ intestinal re-circulating perfusion experiment to examine the effect of pepsin on aspirin-facilitated gliadin absorption. Fluorescein isothiocyanate (FITC)-labeled dextran-40 (FD-40) was used as a marker of non-specific absorption. The molecular size of gliadin and its allergenicity in plasma were examined using immunoblot analysis and intradermal reaction tests with Evans blue dye (EBD) extravasation, respectively.
Results: Aspirin increased plasma concentrations of gliadin after oral administration but had no effect in the closed intestinal loop study. An in situ intestinal re-circulating perfusion study showed that FITC-labeled gliadin was absorbed similarly to FD-40. Aspirin increased absorption of both intact and pepsin-digested gliadin, with a more significant effect on absorption of pepsin-treated gliadin. Immunoblotting showed that most gliadin was absorbed in intact form. When the gliadin fraction was extracted from rat plasma after gavage and injected intradermally into gliadin-sensitized rats, EBD extravasation was observed at injection sites in a gliadin dose-dependent manner.
Conclusions: Aspirin increased the absorption of intact and pepsin-digested gliadin via the paracellular pathway, maintaining their allergenicity. Moreover, the effect of aspirin on gliadin absorption was enhanced by modification and digestion of gliadin in the stomach.
Background: Patch testing of contact allergens to diagnose allergic contact dermatitis (ACD) is a traditional, useful tool. The most important decision is the distinction between allergic and irritant reactions, as this has direct implications on diagnosis and management. Our objective was to evaluate a new method of non-contact infrared reading of patch tests. Secondary objectives included a possible correlation between the intensity of the patch test reaction and temperature change.
Methods: 420 positive reactions from patients were included in our study. An independent patch test reader assessed the positive reactions and classified them as allergic (of intensity + to +++) or irritant (IR). At the same time, a forward-looking infrared (FLIR) camera attachment for an iPhone was used to acquire infrared thermal images of the patch tests, and images were analyzed using the FLIR ONE app.
Results: Allergic patch test reactions were characterized by temperature increases of 0.72 ± 0.67 °C compared to surrounding skin. Irritant reactions only resulted in 0.17 ± 0.31 °C temperature increase. The mean temperature difference between the two groups was highly significant (p < 0.0001) and therefore was used to predict the type of contact dermatitis.
Conclusions: Thermography is a reliable and effective way to distinguish between allergic and irritant contact dermatitis.