Advances in pediatric asthma in 2012: moving toward asthma prevention

Multiancestral polygenic risk score for pediatric asthma

BACKGROUND

Asthma is the most common chronic condition in children and the third leading cause of hospitalization in pediatrics. The genome-wide association study catalog reports 140 studies with genome-wide significance. A polygenic risk score (PRS) with predictive value across ancestries has not been evaluated for this important trait.

OBJECTIVES

This study aimed to train and validate a PRS relying on genetic determinants for asthma to provide predictions for disease occurrence in pediatric cohorts of diverse ancestries.

METHODS

This study applied a Bayesian regression framework method using the Trans-National Asthma Genetic Consortium genome-wide association study summary statistics to derive a multiancestral PRS score, used one Electronic Medical Records and Genomics (eMERGE) cohort as a training set, used a second independent eMERGE cohort to validate the score, and used the UK Biobank data to replicate the findings. A phenome-wide association study was performed using the PRS to identify shared genetic etiology with other phenotypes.

RESULTS

The multiancestral asthma PRS was associated with asthma in the 2 pediatric validation datasets. Overall, the multiancestral asthma PRS has an area under the curve (AUC) of 0.70 (95% CI, 0.69-0.72) in the pediatric validation 1 and AUC of 0.66 (0.65-0.66) in the pediatric validation 2 datasets. We found significant discrimination across pediatric subcohorts of European (AUC, 95% CI, 0.60 and 0.66), African (AUC, 95% CI, 0.61 and 0.66), admixed American (AUC, 0.64 and 0.70), Southeast Asian (AUC, 0.65), and East Asian (AUC, 0.73) ancestry. Pediatric participants with the top 5% PRS had 2.80 to 5.82 increased odds of asthma compared to the bottom 5% across the training, validation 1, and validation 2 cohorts when adjusted for ancestry. Phenome-wide association study analysis confirmed the strong association of the identified PRS with asthma (odds ratio, 2.71, PFDR = 3.71 × 10-65) and related phenotypes.

CONCLUSIONS

A multiancestral PRS for asthma based on Bayesian posterior genomic effect sizes identifies increased odds of pediatric asthma.

IL‑27 suppresses airway inflammation, hyperresponsiveness and remodeling via the STAT1 and STAT3 pathways in mice with allergic asthma

Type 2 cytokine-associated immunity may be involved in the pathogenesis of allergic asthma. Although interleukin 27 (IL-27) has been reported as an initiator and suppressor of T-helper 1 (Th1) and T-helper 2 (Th2) responses, respectively, its effects on the development of asthma remain unclear. In the present study, mice were induced and challenged with ovalbumin and received subsequent intranasal administration of IL-27. Total and differential cell counts were determined from Wright-Giemsa-stained cytospins, whereas the cytokine levels were detected using ELISA. In addition, the expression levels of signal transducer and activator of transcription (STAT) 1, STAT3, GATA-binding protein-3 (GATA3) and T-bet (T-box transcription factor) were analyzed in T cells by western blot analysis. Their corresponding mRNA expression levels were determined by quantitative PCR. Airway remodeling was assessed by conventional pathological techniques. The results indicated that intranasal administration of IL-27 ameliorated airway inflammation and hyperresponsiveness in an acute model of asthma. Furthermore, IL-27 prevented airway remodeling in a chronic model of asthma. Following administration of IL-27, the mRNA expression levels of STAT1 and T-bet were upregulated, while those of GATA3 were downregulated. Moreover, the phosphorylation levels of STAT1 and STAT3 were increased. Taken together, these findings demonstrated that intranasal administration of IL-27 ameliorated Th2-related allergic lung inflammation and remodeling in mouse models of asthma by repairing both the STAT1 and STAT3 pathways.

Dose Matters: A Smartphone Application to Improve Asthma Control Among Patients at an Urban Pediatric Primary Care Clinic

Objective: As the most common chronic condition of childhood, asthma is a frequent target for family education. However, current educational strategies rarely tailor to learning style or literacy level. Thus, we developed and implemented a smartphone application (app) leveraging gamified features entitled CHANGE Asthma ("Clinic, Home, And on the Go Education for Asthma"). We subsequently assessed its impact on asthma control. Methods: Patients aged 4-11 years with a previously documented childhood asthma control test (C-ACT) score of <20, indicating poor control, were recruited to participate in this randomized control pilot study. The intervention group downloaded CHANGE Asthma; asthma control was assessed at enrollment and at follow-up. The changes in C-ACT score in both groups were compared using analysis of covariance (primary outcome). App usage was monitored for 4 months following download, and the relationship between usage time, and the change in C-ACT score was assessed via linear regression. Results: The control and intervention groups both included 20 caregivers with 75% of participants completing follow-up. Although C-ACT scores among intervention participants significantly improved at follow-up, compared to their own baseline (P = 0.04), the change of C-ACT score did not significantly differ from that of the control group (P = 0.78). Among the intervention participants, there was a positive, dose-dependent relationship between app usage time and positive change in C-ACT score (P = 0.03). Conclusion: Usage of a gamified app was associated with a dose-dependent improvement in asthma control over time, suggesting that further evaluation of apps for asthma education, and perhaps for other chronic conditions, is warranted.

A Clinical Pathway for the Care of Critically Ill Patients With Asthma in the Community Hospital Setting

OBJECTIVES

The management of severe pediatric asthma exacerbations is variable. The use of clinical pathways has been shown to decrease time to clinical recovery and length of stay (LOS) for critically ill patients with asthma in freestanding children's hospitals. We sought to determine if implementing a clinical pathway for pediatric patients who are on continuous albuterol in a community hospital would decrease time to clinical recovery and LOS.

METHODS

A clinical pathway for guiding the initiation, escalation, and weaning of critical asthma therapies was adapted to a community hospital without a PICU. There were 2 years of baseline data collection (from September 2014 to August 2016) and 16 months of intervention data collection. Segmented regression analysis of interrupted time series was used to evaluate the pathway's impact on LOS and time to clinical recovery.

RESULTS

There were 129 patients in the study, including 69 in the baseline group and 60 in the intervention group. After pathway implementation, there was an absolute reduction of 10.2 hours (SD 2.0 hours) in time to clinical recovery (P ≤ .001). There was no significant effect on LOS. There was a significant reduction in the transfer rate (27.5% of patients in the baseline period versus 11.7% of patients in the intervention period; P = .025). There was no increase in key adverse events, which included the percentage of patients who required ICU-specific therapies while awaiting transfer (7.3% of patients in the baseline period versus 1.7% of patients in the intervention period; P = .215).

CONCLUSIONS

The implementation of a clinical pathway for the management of critically ill children with asthma and on continuous albuterol in a community hospital was associated with a significant reduction in time to clinical recovery without an increase in key adverse events.

Critical role of Toll-like receptors in pathophysiology of allergic asthma

Allergic asthma is an airway disease, characterized by reversible bronchoconstriction, chronic inflammation of the airway, and thickness of smooth muscle in the respiratory tract. Asthma is orchestrated by an excessive Th2-adaptive immune response, in which innate immunity plays a key role. Recently TLRs have received more and more attention as they are central to orchestrate the innate immune responses. TLRs are localized as integral membrane or intracellular glycoproteins with those on the cell surface sensing microbial antigens and the ones, localized in intracellular vesicles, sensing microbial nucleic acid species. Having recognized microbial antigens, TLRs conduct the immune response towards a pro- or anti-allergy response. As a double-edged sword, they could initiate either harmful or helpful responses by the immune system in case of allergic asthma. In the current review, we will describe the role of TLRs and their signaling pathways in allergic asthma.

Farnesol, a sesquiterpene alcohol in essential oils, ameliorates serum allergic antibody titres and lipid profiles in ovalbumin-challenged mice

BACKGROUND

Farnesol, a natural sesquiterpene alcohol in essential oils, was found to have potential for alleviating massive inflammation, oxidative stress and lung injury. However, effects of farnesol supplementation on allergic asthma remain unclear.

OBJECTIVES

To clarify the puzzle, this work investigates the effects of farnesol on allergic asthma using an ovalbumin (OVA)-sensitised and challenged mouse model.

METHODS

Farnesol was administered to OVA-sensitised and challenged mice for 5 weeks. Three farnesol doses, namely 5, 25 and 100mg farnesol/kg BW/day, non-sensitised control, dietary control, and positive control (dexamethasone 3mg/kg BW by gavage) were included. Sera and bronchoalveolar lavage fluids from the experimental mice were collected to measure farnesol concentrations, serum lipid profiles, antibody titres, differential cell counts or Th1/Th2 cytokines levels.

RESULTS

The results showed that farnesol supplementation increased serum farnesol concentration dose-dependently, significantly increased (P<0.05) OVA-specific IgG2a/IgE antibody titre ratios, but decreased total IgE levels. Farnesol supplementation markedly reversed the aberrated LDL-c/HDL-c and HDL-c/TC ratios in the sera of asthmatic mice, suggesting that farnesol supplementation might ameliorate serum lipid profiles in the OVA-sensitised and challenged mice.

CONCLUSION

Our results evidenced that farnesol supplementation might improve serum allergic antibody titres and lipid profiles in asthmatic mice.

New and future strategies to improve asthma control in children

Symptomatic asthma in childhood has lifelong effects on lung function and disease severity, emphasizing the need for improved pediatric asthma control. Control of pediatric risk and impairment domains can be achieved through increased medication adherence or new therapeutic strategies. Developing electronic monitoring device technology with reminders might be a key noninvasive resource to address poor adherence in children and adolescents in a clinical setting. In patients who have persistently poor control despite optimal medication compliance, newly emerging pharmaceuticals, including inhaled therapies and biologics, might be key to their treatment. However, barriers exist to their development in the pediatric population, and insights must be drawn from adult studies, which has its own unique limitations. Biomarkers to direct the use of such potentially expensive therapies to those patients most likely to benefit are imperative. In this review the current literature regarding strategies to improve pediatric asthma control is addressed with the goal of exploring the potential and pitfalls of strategies that might be available in the near future.

Dose-response relationship of specific allergen exposure-induced immunological tolerance: a mouse model

BACKGROUND

It is believed that adequate allergen preimmunization exposure could induce immunologic tolerance. The purpose of this study was to investigate the dose-dependent mechanisms related to antigen-specific tolerance induction in a mouse model.

METHODS

Mice were assigned to 5 groups: the control (Cont) group received phosphate-buffered saline (PBS) preimmunization exposure and PBS sham immunization; the other 4 groups were exposed preimmunization to PBS (PBS group) or ovalbumin (OVA) (first mucosal doses: 1.25%, 2.5%, or 5% wt/vol aerosol from days -3 to -1) prior to OVA immunization. The OVA-immunized mice received intraperitoneal doses of 20 μg OVA (on days 1, 7, and 14), and then a second set of mucosal doses with 0.5% wt/vol OVA aerosol (on days 18 to 20). After assessment of airway hyperresponsiveness (AHR), the mice were euthanized and their blood, bronchoalveolar lavage fluids (BALFs), and lung tissues were collected for further analyses.

RESULTS

OVA-immunized mice exposed to OVA preimmunization had reduced AHR and immunoglobulin E production when compared to the PBS group. OVA preimmunization exposure inhibited eosinophilic inflammation in lung tissues. The proportions of BALF eosinophil counts from the groups exposed to OVA preimmunization were significantly decreased when compared with those exposed to PBS preimmunization. The balance of T helper 2 (Th2) and T regulatory (Treg) cytokines in BALFs were additionally observed in this mouse model.

CONCLUSION

Our results suggest that preimmunization exposure to an appropriate dose of a specific antigen could suppress allergic airway inflammation by induction of immunological tolerance.

Farnesol, a sesquiterpene alcohol in herbal plants, exerts anti-inflammatory and antiallergic effects on ovalbumin-sensitized and -challenged asthmatic mice

To investigate the effect of farnesol on allergic asthma, three farnesol doses were extra-added into AIN-76 feed consumed by ovalbumin- (OVA-) sensitized and -challenged mice continuously for 5 weeks, at approximately 5, 25, and 100 mg farnesol/kg, BW/day. The results showed that there were no significant differences in body weight, feed intake, and visceral organ weights between the farnesol supplementation and dietary control groups. Farnesol supplementation decreased interleukin (IL)-6/IL-10 level ratios in bronchoalveolar lavage fluid (BALF). Farnesol supplementation significantly (P < 0.05) restored the cytokine secretion ability of peritoneal macrophages that was suppressed as a result of OVA sensitization and challenge and slightly decreased tumor necrosis factor (TNF-α)/IL-10 cytokine secretion ratios. Farnesol supplementation slightly (P > 0.05) decreased IL-4 but significantly (P < 0.05) increased IL-2 levels secreted by the splenocytes in the presence of OVA, implying that farnesol might have a systemic antiallergic effect on allergic asthmatic mice. Farnesol supplementation significantly (P < 0.05) increased IL-10 levels secreted by the splenocytes in the presence of OVA, suggesting that farnesol might have an anti-inflammatory potential to allergic asthmatic mice. Overall, our results suggest that farnesol supplementation may be beneficial to improve the Th2-skewed allergic asthmatic inflammation.

Using public policy to improve outcomes for asthmatic children in schools

School-based services to improve asthma management need to be accompanied by public policies that can help sustain services, scale effective interventions, create greater equity across schools, and improve outcomes for children. Several national organizations, including the Centers for Disease Control and Prevention, have recommended specific public policies the adoption of which in school settings can improve asthma outcomes for children. Although many states and school districts have adopted some of these policies, adoption is not universal, and implementation is not always successful, leaving inequities in children's access to asthma services and supports. These issues can be addressed by changing public policy. Policy change is a complex process, but it is one that will benefit from greater involvement by asthma experts, including the researchers who generate the knowledge base on what services, supports, and policies have the best outcomes for children. Asthma experts can participate in the policy process by helping to build awareness of the need for school-based asthma policy, estimating the costs associated with policy options and with inaction, advocating for the selection of specific policies, assisting in implementation (including providing feedback), conducting the research that can evaluate the effectiveness of implementation, and ultimately providing information back into the policy process to allow for improvements to the policies.

Agreement between the skin prick test and specific serum IgE for egg white and cow's milk allergens in young infant with atopic dermatitis

BACKGROUND

The skin prick test (SPT) for detecting atopic sensitization is not preferred in young infants with atopic dermatitis (AD) because of concerns about poor skin reactivity. This study aimed to evaluate whether the results of SPT agreed well with those of specific serum immunoglobulin E (sIgE) antibody test in young infants with AD.

METHODS

This study included 2,077 eligible infants (age, <12 months) with AD who were tested by either SPT or sIgE between 2007 and 2011. Among them, 199 infants tested for egg white (EW) and 192 infants tested for cow's milk (CM), by both SPT and sIgE on the same day were identified and reviewed retrospectively. Kappa statistics and tests for equal kappa statistics were used to evaluate the agreement between the SPT and sIgE.

RESULTS

The mean wheal diameter and the allergen-to-histamine ratio of SPT showed substantial agreement with those of sIgE for EW (κ = 0.62, 0.69) and CM (κ = 0.34, 0.47). The agreement for EW was significantly higher <6-month-old than in ≥6-month-old infants (κ = 0.79 vs. 0.54, P = 0.02), and that for CM was similar (P = 0.60). The mean wheal diameters for EW and CM were evenly distributed, and did not show increasing trends regardless of age in months (Ptrend = 0.13 and 0.06, respectively).

CONCLUSIONS

The results of SPT agreed well with those of sIgE. This finding provides a rationale for using SPT, and suggests that SPT can be used along with sIgE to detect food sensitization in young infants with AD.

Advances in pediatric asthma in 2013: coordinating asthma care

Last year's "Advances in pediatric asthma: moving toward asthma prevention" concluded that "We are well on our way to creating a pathway around wellness in asthma care and also to utilize new tools to predict the risk for asthma and take steps to not only prevent asthma exacerbations but also to prevent the early manifestations of the disease and thus prevent its evolution to severe asthma." This year's summary will focus on recent advances in pediatric asthma on prenatal and postnatal factors altering the natural history of asthma, assessment of asthma control, and new insights regarding potential therapeutic targets for altering the course of asthma in children, as indicated in Journal of Allergy and Clinical Immunology publications in 2013 and early 2014. Recent reports continue to shed light on methods to understand factors that influence the course of asthma, methods to assess and communicate levels of control, and new targets for intervention, as well as new immunomodulators. It will now be important to carefully assess risk factors for the development of asthma, as well as the risk for asthma exacerbations, and to improve the way we communicate this information in the health care system. This will allow parents, primary care physicians, specialists, and provider systems to more effectively intervene in altering the course of asthma and to further reduce asthma morbidity and mortality.

Advances in adult asthma diagnosis and treatment in 2013

In 2013, several themes emerged: (1) a dedicated search for new therapies using new mechanisms; (2) the importance of the plasticity of the immune system (eg, that molecules that mediate inflammation in one setting can promote its resolution and return to homeostasis in other circumstances); (3) the complex role of viruses in asthma exacerbations; (4) the similarities and differences among asthma, asthma in smokers, and chronic obstructive pulmonary disease; and (5) the importance of understanding asthma phenotypes and their stability over time. Once new therapeutics pass the initial clinical trials, patient-oriented and real-world research will be needed.

Researching asthma across the ages: insights from the National Heart, Lung, and Blood Institute's Asthma Network

Clinical asthma studies across different age groups (ie, cross-age studies) can potentially offer insight into the similarities, differences, and relationships between childhood and adult asthma. The National Institutes of Health's Asthma Research Network (AsthmaNet) is unique and innovative in that it has merged pediatric and adult asthma research into a single clinical research network. This combination enhances scientific exchange between pediatric and adult asthma investigators and encourages the application of cross-age studies that involve participants from multiple age groups who are generally not studied together. The experience from AsthmaNet in the development of cross-age protocols highlights some of the issues in the evaluation of cross-age research in asthma. The aim of this review is to summarize these challenges, including the selection of parallel cross-age clinical interventions, identification of appropriate controls, measurement of meaningful clinical outcomes, and various ethical and logistic issues.

Designed nanocage displaying ligand-specific Peptide bunches for high affinity and biological activity

Protein-cage nanoparticles are promising multifunctional platforms for targeted delivery of imaging and therapeutic agents owing to their biocompatibility, biodegradability, and low toxicity. The major advantage of protein-cage nanoparticles is the ability to decorate their surfaces with multiple functionalities through genetic and chemical modification to achieve desired properties for therapeutic and/or diagnostic purposes. Specific peptides identified by phage display can be genetically fused onto the surface of cage proteins to promote the association of nanoparticles with a particular cell type or tissue. Upon symmetrical assembly of the cage, peptides are clustered on the surface of the cage protein in bunches. The resulting PBNC (peptide bunches on nanocage) offers the potential of synergistically increasing the avidity of the peptide ligands, thereby enhancing their blocking ability for therapeutic purposes. Here, we demonstrated a proof-of-principle of PBNCs, fusing the interleukin-4 receptor (IL-4R)-targeting peptide, AP-1, identified previously by phage display, with ferritin-L-chain (FTL), which undergoes 24-subunit assembly to form highly stable AP-1-containing nanocage proteins (AP1-PBNCs). AP1-PBNCs bound specifically to the IL-4R-expressing cell line, A549, and their binding and internalization were specifically blocked by anti-IL-4R antibody. AP1-PBNCs exhibited dramatically enhanced binding avidity to IL-4R compared with AP-1 peptide, measured by surface plasmon resonance spectroscopy. Furthermore, treatment with AP1-PBNCs in a murine model of experimental asthma diminished airway hyper-responsiveness and eosinophilic airway inflammation along with decreased mucus hyperproduction. These findings hold great promise for the application of various PBNCs with ligand-specific peptides in therapeutics for different diseases, such as cancer.

Urine Leukotriene E4 Levels in Children with Nonspecific Isolated Chronic Dry Cough

Chronic cough is the most common complaint during childhood. Various pathophysiologic mechanisms may cause cough. Knowledge of the mechanisms underlying chronic cough plays an important role in the choice of treatment to evaluate the role of leukotrienes in children with nonspecific isolated chronic dry cough. The patient group consisted of children with isolated chronic dry cough persisting for >4 weeks and the control group included healthy children. Medical histories were elicited and physical examinations were performed, then respiratory function testing was done and chest X-rays were obtained. Patients were given inhaled corticosteroid. The urine leukotriene E4 (uLTE4) levels in the patient and control groups was measured by enzyme immunoassay. The patient group included 55 patients, 25 of them were males between 6 and 12 years old. The control group included 25 healthy children between 6 and 12 years old, 12 of them were males. There were no pathologic findings on physical examinations, pulmonary function testing, and chest X-rays. The complaints of cough in 50 patients were resolved after treatment. The median level of uLTE4 was 73.1 ng/mmol creatinine (range, 15.59-787.55 ng/mmol creatinine) in the patient group, and 64.2 ng/mmol creatinine (range, 12-282 ng/mmol creatinine) in the control group. No significant difference was detected between the 2 groups with respect to age, gender, and uLTE4 levels. Different pathophysiologic mechanisms are known to influence nonspecific isolated chronic dry cough. Various mechanisms, other than leukotrienes, may also give rise to dry cough.

Neuroimmune semaphorin 4A as a drug and drug target for asthma

Neuroimmune semaphorin 4A (Sema4A) has been shown to play an important costimulatory role in T cell activation and regulation of Th1-mediated diseases such as multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE), and experimental autoimmune myocarditis (EAM). Sema4A has three functional receptors, Tim-2 expressed on CD4+ T cells, Th2 cells in particular, and Plexin B1 and D1 predominantly expressed on epithelial and endothelial cells, correspondingly. We recently showed that Sema4A has a complex expression pattern in lung tissue in a mouse model of asthma. We and others have shown that corresponding Plexin expression can be found on immune cells as well. Moreover, we demonstrated that Sema4A-deficient mice displayed significantly higher lung local and systemic allergic responses pointing to its critical regulatory role in the disease. To determine the utility of Sema4A as a novel immunotherapeutic, we introduced recombinant Sema4A protein to the allergen-sensitized WT and Sema4A(-/-) mice before allergen challenge. We observed significant reductions in the allergic inflammatory lung response in Sema4A-treated mice as judged by tissue inflammation including eosinophilia and mucus production. Furthermore, we demonstrated that in vivo administration of anti-Tim2 Ab led to a substantial upregulation of allergic inflammation in WT mouse lungs. These data highlight the potential to develop Sema4A as a new therapeutic for allergic airway disease.

What is new in the prevention of atopy and asthma?

PURPOSE OF REVIEW

Increasing understanding of mechanisms and influencing factors in the development of uncontrolled inflammatory responses in atopy and asthma should serve for the introduction of new preventive measures. This review tries to present the current state of the art and resumes that until now, no really effective concept can be offered to families at risk.

RECENT FINDINGS

In addition to modified feeding regimes (hydrolysed formula feeding in infancy), timing of the introduction of solids (avoidance of allergens versus early induction of tolerance), immune modulation using prebiotics or probiotics, a new target of potential intervention could be the human microbiome as a key player in the development of inflammatory diseases such as allergy and asthma. However, during the last 5 years, this concept could not yet be verified in interventional trials. There are new trials ongoing, studying the effect of microbial compounds in early infancy, vitamin D and polyunsaturated fatty acid supplementation during late pregnancy and the effect of azithromycin in children with recurrent wheeze. Results are to be expected within the next couple of years.

SUMMARY

New data on multifaceted intervention and the analysis of the human microbiome are to be expected. The recommendation for atopy and asthma prevention still focuses on avoidance of tobacco smoke exposure and food allergens during the first 4 months of life and feeding of hydrolysed formula if breast-feeding is not possible in high-risk infants, potentially early feeding of prebiotic sugars and/or certain strains of probiotic bacteria or bacterial compounds in certain subpopulations.