The state of asthma epidemiology: an overview of systematic reviews and their quality

Helicobacter pylori Infection Does Not Protect Against Allergic Diseases: Evidence From a Pediatric Cohort From Northern Sardinia, Italy

BACKGROUND

The "hygiene hypothesis" states that reduced exposure to microbial antigens due to an excessively hygienic environment can increase the risk of developing autoimmune diseases, including atopic disorders and asthma. In recent decades, there has been a progressive decline in the prevalence of numerous microorganisms following improved hygienic-sanitary conditions. More specifically, several studies reported an inverse association between the reduction in Helicobacter pylori infection and the rise of asthma and allergic disorders.

AIM

To evaluate the prevalence of atopic disorders in a pediatric population in relation to seropositivity against H. pylori.

METHODS

Children from Northern Sardinia, Italy, referred to the local Children's Hospital for any reason, were investigated to identify risk factors, especially H. pylori infection, associated with atopic disorders. A validated questionnaire, including demographics, house size, history of breastfeeding, residence, school or daycare center attendance, exposure to animals, and a defined diagnosis of atopy-including asthma-was filled out by a trained pediatrician according to parents' answers and child records. A blood sample was collected from each participant and immunoglobulin G against H. pylori was assessed by a locally validated ELISA test.

RESULTS

The seroprevalence of H. pylori infection was 11.7% among 492 children (240 females). Thirty-two children had a confirmed diagnosis of asthma and 12 of allergy. No one child showed both conditions. Statistically significant differences in H. pylori seropositivity were not detected between children with or without atopy (8.4% vs. 12.6; p = 0.233). Although atopic disorders were more frequent in children exposed to traditional atopic risk factors, none of them showed to be significant after adjusting for all covariates.

CONCLUSIONS

Serologically assessed H. pylori infection was not significantly associated with a reduced risk of atopic diseases in children.

Network Pharmacology Combined with Molecular Docking and Experimental Verification Reveals the Bioactive Components and Potential Targets of Danlong Dingchuan Decoction against Asthma

BACKGROUND

Danlong Dingchuan Decoction has a definite effect in the clinical treatment of asthma. This study aimed to explore the material and molecular biological basis of Danlong Dingchuan Decoction in treating asthma through network pharmacology combined with animal experiments.

MATERIALS AND METHODS

First, the chemical constituents of Danlong Dingchuan Decoction were screened from the Traditional Chinese Medicine Systematic Pharmacology Analysis Platform (TCMSP) and the Traditional Chinese Medicine and Chemical Composition Database. Literature reports on asthma targets were obtained from the Online Mendelian Inheritance in Man (OMIM), Therapeutic Targets Database (TTD), and other databases. Then, the protein-protein interaction network was constructed according to the matching results of Danlong Dingchuan Decoction and asthma targets. Furthermore, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed by the Database for Annotation, Visualization, and Integrated Discovery (DAVID). Finally, the interaction between the active compounds of Danlong Dingchuan Decoction and key targets was simulated using molecular docking. In animal experiments, ovalbumin was used to induce asthma in mice. After treating the mice by oral gavage administration of Danlong Dingchuan Decoction, the expression levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were detected in the lung tissue of the mice by enzyme-linked immunosorbent assay kit, whereas TLR4 mRNA expression was detected by quantitative reverse transcription-polymerase chain reaction.

RESULTS

A total of 247 active compounds and 155 potential targets were obtained. Enrichment analysis showed that quercetin, xanthine, lysine, kaempferol, ß-sitosterol, and four other active compounds were the main components of Danlong Dingchuan Decoction; IL-6, TNF, CXCL8, VEGFA, MAPK3, IL-10, PTGS2, IL-1β, IL-4, and TLR4 were the potential targets for therapy. KEGG analysis showed that the cAMP signaling pathway, cGMP-PKG signaling pathway, NF-κB signaling pathway, and PI3K-Akt signaling pathway might play an important role in treating asthma. Molecular docking analysis showed that quercetin combined well with TNF, CXCL8, and TLR4. Animal experiments showed that Danlong Dingchuan Decoction effectively reduced the expression levels of TNF-α, IL-4, TGF-β1, IL-6, IL-8, and IL-1β in the lung tissue of asthmatic mice and inhibited TLR4 mRNA expression.

CONCLUSIONS

Danlong Dingchuan Decoction may act on key targets (such as IL-6, TNF, CXCL8, VEGFA, and MAPK3) with key active ingredients (such as quercetin, xanthine, lysine, kaempferol, and ß-sitosterol) to reduce the expression levels of IL-4, IL-6, IL-8, and other Th2 cytokines. This may be the mechanism by which Danlong Dingchuan Decoction reduces airway inflammation and treats asthma mediated by Th2 cytokines.

Adherence to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist in articles published in EAACI Journals: A bibliographic study

Research data derived from observational studies are accumulating quickly in the field of allergy and immunology and a large amount of observational studies are published every year. The aim of the present study was to evaluate the adherence to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist by papers published in the three European Academy of Allergy and Clinical Immunology journals, during the period 2009-2018. To this end, we conducted a bibliographic study of up to eight randomly selected papers per year per Journal. Our literature search resulted in 223 papers. Amongst those, 80, 80 and 63 records were from Paediatric Allergy and Immunology, Allergy and Clinical and Translational Allergy, respectively; the latter was published only from 2011 on. Prospective, case control and cross-sectional designs were described in 88, 43 and 92 papers, respectively. Full reporting of all STROBE items was present in 47.4%, 45.6% and 41.2% for the cohort, cross-sectional and case-control studies, respectively. Generally, no time trend in adherence of reporting STROBE items was observed, apart from reporting funding, which increased from 60% in 2009/2010 to more than 90% in 2018. We identified a cluster of STROBE items with low proportions of full reporting constituted by the items on reporting study design in the title and methods, variables types along with their measurement/assessment, bias and confounding, study size, and grouping of variables. It appears that the STROBE checklist is a suitable tool in observational allergy epidemiology. However, adherence to the STROBE checklist appeared suboptimal.

Epidemiology of Allergy: Natural Course and Risk Factors of Allergic Diseases

The prevalences of allergic diseases, asthma, atopic dermatitis, allergic rhinitis and lately food allergy have been increasing over the last decades. It has been suggested that the prevalence of allergic diseases has reached a plateau in high income countries, while it is still on the rise in low and middle income countries. Generally, allergic diseases more often set on in childhood than in adulthood and affected children contribute more to the rise in allergic disease prevalence than affected adults. Epidemiological evidence suggests that not all atopic dermatitis and asthma cases are attributable to atopic sensitization. Indeed, mainly genetic association studies have prompted the unravelling of barrier dysfunction as a mainstay in the patho-mechanisms leading to atopic dermatitis and to asthma with atopic sensitization secondary to this dysfunction. Epidemiological research on risk and protective factors for allergic disease, acting against the background of genetic susceptibility, has produced an enormous body of evidence. Prominent observations are the 'sibling effect' and the 'farm effect' which gave rise to the 'hygiene hypothesis' and later the 'biodiversity hypothesis'. Future epidemiological research is required to evaluate and refine these hypotheses in light of the paradigm shift from atopic sensitization to barrier dysfunction with ever increasing options for environmental characterization, currently, e.g., 'omics'-techniques in microbiology and metabolism, and with ever increasing options for phenotyping of allergic techniques, including, e.g., high-resolution time series of symptoms using, e.g., sensing technologies.

Emerging concepts and directed therapeutics for the management of asthma: regulating the regulators

Asthma is a common, heterogeneous and serious disease, its prevalence has steadily risen in most parts of the world, and the condition is often inadequately controlled in many patients. Hence, there is a major need for new therapeutic approaches. Mild-to-moderate asthma is considered a T-helper cell type-2-mediated inflammatory disorder that develops due to abnormal immune responses to otherwise innocuous allergens. Prolonged exposure to allergens and persistent inflammation results in myofibroblast infiltration and airway remodelling with mucus hypersecretion, airway smooth muscle hypertrophy, and excess collagen deposition. The airways become hyper-responsive to provocation resulting in the characteristic wheezing and obstructed airflow experienced by patients. Extensive research has progressed the understanding of the underlying mechanisms and the development of new treatments for the management of asthma. Here, we review the basis of the disease, covering new areas such as the role of vascularisation and microRNAs, as well as associated potential therapeutic interventions utilising reports from animal and human studies. We also cover novel drug delivery strategies that are being developed to enhance therapeutic efficacy and patient compliance. Potential avenues to explore to improve the future of asthma management are highlighted.

Protein S protects against allergic bronchial asthma by modulating Th1/Th2 balance

BACKGROUND

Bronchial asthma is a chronic disease characterized by inflammation, obstruction, and hyperresponsiveness of the airways. There is currently no curative therapy for asthma. Type 2 helper T cell response plays a critical role in the pathogenesis of the disease. Protein S is a glycoprotein endowed with anticoagulant, anti-inflammatory, and anti-apoptotic properties. Whether protein S can suppress bronchial asthma and be useful for its therapy is unknown.

METHODS

To address this question here we compared the development of allergen-associated bronchial asthma between wild type and protein S-overexpressing transgenic mice. Mice were sensitized and challenged with ovalbumin. We also evaluated the circulating levels of total and active protein S in patients with bronchial asthma and healthy controls.

RESULTS

The circulating level of total protein S and of its active form was significantly decreased in patients with bronchial asthma compared to controls. Allergic protein S transgenic mice showed a significant reduction of airway hyperresponsiveness, lung tissue inflammatory cell infiltration, lung levels of Th2 cytokines and IgE compared to their wild-type counterparts. Administration of exogenous human protein S also decreased airway hyperresponsiveness and Th2-mediated lung inflammation in allergic wild-type mice compared with their untreated mouse counterparts. Human protein S significantly shifted the Th1/Th2 balance to Th1 and promoted the secretion of Th1 cytokines (IL-12, tumor necrosis factor-α) from dendritic cells.

CONCLUSIONS

These observations suggest the strong protective activity of protein S against the development of allergic bronchial asthma implicating its potential usefulness for the disease treatment.

Sanfu herbal patch applied at acupoints in patients with bronchial asthma: study protocol for a randomized controlled trial

Background

Bronchial asthma is one of the most common inflammatory airway disorders. As one of the main non-drug therapies, the Sanfu herbal patch (SHP) has been widely used to treat bronchial asthma, although the evidence for its efficacy and associated mechanism are inconclusive. The objective of this trial is to clarify the clinical efficacy and safety of the SHP in the treatment of bronchial asthma in the chronic persistent or clinical remission stage and to provide high-quality data for further research.

Methods

We propose a multicentre, double-blinded, parallel, randomized, placebo-controlled clinical trial involving 4 study hospitals in China. A total of 72 eligible participants will be randomized into an SHP group and a placebo group. They will receive an SHP for 3 treatment sessions. The primary outcome will be changes in forced expiratory volume in 1 s after 3 treatment sessions. Secondary outcomes will include the following: (1) the Asthma Quality of Life Questionnaire, Asthma Control Test, and Asthma Long-term Follow-up Scale; (2) levels of Metallothionein-2 and Transgelin-2 in blood and urine; and (3) levels of IL-5, IL-13, IL-23, IL-25, and thymic stromal lymphopoietin in blood. Analysis of the data will be performed at baseline, at the end of the 2nd and 3rd treatment sessions, and at the 24-week follow-up. The safety of the SHP will be evaluated at each treatment session.

Discussion

The aims of this trial are to determine whether the SHP is more effective than placebo in the treatment of patients with bronchial asthma, as well as whether the SHP works by reducing airway inflammation and reversing bronchoconstriction.

Trial registration

Chinese Clinical Trial Registry (http://www.chictr.org.cn), ChiCTR1900024616. Registered on 19 July 2019.

Inter-review agreement of risk-of-bias judgments varied in Cochrane reviews

OBJECTIVES

The objective of the study was to measure the level of agreement between Cochrane reviews of overlapping randomized controlled trials (RCTs) regarding risk-of-bias (RoB) judgments.

STUDY DESIGN AND SETTING

On November 5, 2017, the Cochrane Database of Systematic Reviews was searched for Cochrane reviews on tobacco. Reviews that included overlapping RCTs were included. RoB judgments were extracted from RoB tables using automated data scraping with manual verification and adjustments. Agreement between the reviews was calculated using Conger's generalized kappa coefficient (κ) and raw agreement (a).

RESULTS

We included 53 Cochrane reviews of 376 RCTs. For the RoB domain "random sequence generation," the level of agreement between the reviews was substantial with κ = 0.63 (95% confidence interval: 0.56 to 0.71; a = 0.80). There was slight-to-moderate agreement between the reviews regarding the domains "allocation concealment": κ = 0.51 (0.41 to 0.61), a = 0.75; "blinding": κ = 0.19 (0.02 to 0.37), a = 0.52; "blinding of outcome assessment": κ = 0.43 (0.14 to 0.72) a = 0.67; and "incomplete outcome data": κ = 0.15 (-0.03 to 0.32), a = 0.64. For "blinding of participants and personnel" and "selective reporting", κ could not be calculated. The raw agreement was 0.40 and 0.42, respectively.

CONCLUSION

The level of agreement between Cochrane reviews regarding RoB judgments ranged from slight to substantial depending on the RoB domain. Further investigations regarding reasons for variation and interventions to improve agreement are needed.

Protective Role of Matrix Metalloproteinase-2 in Allergic Bronchial Asthma

Inflammation, reversible obstruction, and hyperresponsiveness of the airways are characteristic findings of bronchial asthma. Several evidence has demonstrated the involvement of matrix metalloproteinase-2 in allergic airway inflammation. Matrix metalloproteinase-2 may promote aberrant tissue remodeling in late stages of allergic airway inflammation. However, whether matrix metalloproteinase-2 is detrimental or protective in early stages of allergic airway inflammation remains unclear. To evaluate this here we compared the severity of allergic bronchial asthma between mice overexpressing human matrix metalloproteinase-2 and wild type mice. After sensitization and challenge with an allergen, mice overexpressing the human matrix metalloproteinase-2 showed a significant reduction in airway hyperresponsiveness and in the expression of Th2 cytokines and IgE compared to their wild type counterparts. An inhibitor of matrix metalloproteinases abolished this beneficial effect of human matrix metalloproteinase-2 overexpression. Allergen-sensitized and challenged human matrix metalloproteinase-2 transgenic mice had enhanced percentage of M1 macrophages with increased expression of inducible nitric oxide synthase and STAT1 activation in the lungs compared to their wild type counterparts. There was no difference in the percentage of regulatory T cells between mouse groups. The results of this study showed that matrix metalloproteinase-2 is protective in allergic bronchial asthma by promoting polarization of macrophages to M1 phenotype.

Microbiome-focused asthma management strategies

Asthma is a common, heterogeneous and serious disease with high prevalence globally. Poorly controlled, steroid-resistant asthma is particularly important as there are no effective therapies and it exerts substantial healthcare and societal burden. The role of microbiomes, particularly in chronic diseases has generated considerable interest in recent times. Existing evidence clearly demonstrates an association between asthma initiation and the microbiome, both respiratory and gastro-intestinal, although its' roles are poorly understood when assessing the asthma progression or heterogeneity (i.e. phenotypes/endotypes) across different geographical locations. Moreover, modulating microbiomes could be preventive and/or therapeutic in patients with asthma warrants urgent attention. Here, we review recent advances in assessing the role of microbiomes in asthma and present the challenges associated with the potential therapeutic utility of modifying microbiomes in management.

Highlights and recent developments in airway diseases in EAACI journals (2017)

The European Academy of Allergy and Clinical Immunology (EAACI) owns three journals: Allergy, Pediatric Allergy and Immunology and Clinical and Translational Allergy. One of the major goals of EAACI is to support health promotion in which prevention of allergy and asthma plays a critical role and to disseminate the knowledge of allergy to all stakeholders including the EAACI junior members. There was substantial progress in 2017 in the identification of basic mechanisms of allergic and respiratory disease and the translation of these mechanisms into clinics. Better understanding of molecular and cellular mechanisms, efforts for the development of biomarkers for disease prediction, novel prevention and intervention studies, elucidation of mechanisms of multimorbidies, entrance of new drugs in the clinics as well as recently completed phase three clinical studies and publication of a large number of allergen immunotherapy studies and metaanalyses have been the highlights of the last year.

Comparison of methodological quality rating of systematic reviews on neuropathic pain using AMSTAR and R-AMSTAR

Background

Systematic reviews (SRs) in the field of neuropathic pain (NeuP) are increasingly important for decision-making. However, methodological flaws in SRs can reduce the validity of conclusions. Hence, it is important to assess the methodological quality of NeuP SRs critically. Additionally, it remains unclear which assessment tool should be used. We studied the methodological quality of SRs published in the field of NeuP and compared two assessment tools.

Methods

We systematically searched 5 electronic databases to identify SRs of randomized controlled trials of interventions for NeuP available up to March 2015. Two independent reviewers assessed the methodological quality of the studies using the Assessment of Multiple Systematic Reviews (AMSTAR) and the revised AMSTAR (R-AMSTAR) tools. The scores were converted to percentiles and ranked into 4 grades to allow comparison between the two checklists. Gwet’s AC1 coefficient was used for interrater reliability assessment.

Results

The 97 included SRs had a wide range of methodological quality scores (AMSTAR median (IQR): 6 (5–8) vs. R-AMSTAR median (IQR): 30 (26–35)). The overall agreement score between the 2 raters was 0.62 (95% CI 0.39–0.86) for AMSTAR and 0.62 (95% CI 0.53–0.70) for R-AMSTAR. The 31 Cochrane systematic reviews (CSRs) were consistently ranked higher than the 66 non-Cochrane systematic reviews (NCSRs). The analysis of individual domains showed the best compliance in a comprehensive literature search (item 3) on both checklists. The results for the domain that was the least compliant differed: conflict of interest (item 11) was the item most poorly reported on AMSTAR vs. publication bias assessment (item 10) on R-AMSTAR. A high positive correlation between the total AMSTAR and R-AMSTAR scores for all SRs, as well as for CSRs and NCSRs, was observed.

Conclusions

The methodological quality of analyzed SRs in the field of NeuP was not optimal, and CSRs had a higher quality than NCSRs. Both AMSTAR and R-AMSTAR tools produced comparable quality ratings. Our results point out to weaknesses in the methodology of existing SRs on interventions for the management NeuP and call for future improvement by better adherence to analyzed quality checklists, either AMSTAR or R-AMSTAR.

Electronic supplementary material

The online version of this article (10.1186/s12874-018-0493-y) contains supplementary material, which is available to authorized users.

The Burden of Pediatric Asthma

Asthma is the most common chronic disease in children, imposing a consistent burden on health system. In recent years, prevalence of asthma symptoms became globally increased in children and adolescents, particularly in Low-Middle Income Countries (LMICs). Host (genetics, atopy) and environmental factors (microbial exposure, exposure to passive smoking and air pollution), seemed to contribute to this trend. The increased prevalence observed in metropolitan areas with respect to rural ones and, overall, in industrialized countries, highlighted the role of air pollution in asthma inception. Asthma accounts for 1.1% of the overall global estimate of "Disability-adjusted life years" (DALYs)/100,000 for all causes. Mortality in children is low and it decreased across Europe over recent years. Children from LMICs particularly suffer a disproportionately higher burden in terms of morbidity and mortality. Global asthma-related costs are high and are usually are classified into direct, indirect and intangible costs. Direct costs account for 50-80% of the total costs. Asthma is one of the main causes of hospitalization which are particularly common in children aged < 5 years with a prevalence that has been increased during the last two decades, mostly in LMICs. Indirect costs are usually higher than in older patients, including both school and work-related losses. Intangible costs are unquantifiable, since they are related to impairment of quality of life, limitation of physical activities and study performance. The implementation of strategies aimed at early detect asthma thus providing access to the proper treatment has been shown to effectively reduce the burden of the disease.

Hygiene Hypothesis in Asthma Development: Is Hygiene to Blame?

Industrialized countries have registered epidemic rates on allergic diseases, such as hay fever, asthma, eczema, and food allergies. The Hygiene Hypothesis was born from work made by Dr. David Strachan, who observed that younger siblings were less susceptible to eczema and asthma, and proposed that this was a result of increased transmission of infectious agents via unhygienic practices within a household. This initial hypothesis was then reframed as the old friends/microbiota hypothesis, implicating non-pathogenic commensal microorganisms as the source of immunomodulatory signals necessary to prevent immune-mediated chronic disorders. Although the hygiene hypothesis is supported by epidemiological research of allergic diseases in certain industrialized settings, it often fails to explain the incidence of asthma in less affluent regions of the world. In this review, we summarize up-to-date information on genetic and environmental factors associated with asthma in different human populations, and present evidence that calls for caution when associating hygiene with the pathogenesis of asthma and other allergic conditions.