Eosinophilic airway inflammation in asthmatic patients is associated with an altered airway microbiome

Until a few years ago, it was thought that microbes don’t live in the lung’s passages.  But now we know that there is a diverse range of microbiota that lives there.  In this month’s issue of JACI, Sverrild and colleagues examine the relationship between these microbes and patterns of airway inflammation in healthy patients and in asthmatics who have not taken steroids (J Allergy Clin Immunol 2017; 140(2): 407-417).  In order to do so, they took 10 healthy participants and 23 nonsmoking steroid-free asthmatics and had them undergo bronchoscopy so that they could get fluid from the lower passageways.  They then sequenced bacterial DNA and looked at the number and type of immune cells.  The 33 participants also had their asthma better characterized through other standardized measures of disease severity like airway hyperresponsiveness to mannitol and fraction of exhaled nitric oxide.

They found that patients with eosinophilic asthma and those with hyperresponsiveness to mannitol, had  changes in microbial composition.  This was in contrast to patients with neutrophilic asthma.  Those asthmatics with the lowest numbers of eosinophils also had differences compared to healthy controls; they had more Neisseria, Bacteroides, and Rothia species while having less Sphingomonas, Halomonas, and Aeribacillus species.  These results suggest that the level of eosinophilic inflammation correlates with variations in bacterial composition.  This may point the way to newer diagnostic tools and therapies to help better identify and control asthma.

A single intervention for cockroach control reduces cockroach exposure and asthma morbidity in children

Cockroaches are small, scurrying insects that we just don’t like to think about.  But as small as they are, they have a large impact on asthma and allergies.  In this month’s issue of JACI, Rabito and colleagues look at the effect of cockroach elimination on asthma outcomes (J Allergy Clin Immunol 2017; 140(2): 565-570).  They build on previous work showing that integrated pest management (IPM) reduces cockroach levels.  But because IPM is s costly and requires special expertise, it is generally not practical for low-income families.  Instead, the authors looked at the efficacy of insecticidal bait, which is much cheaper and can be done by almost anybody. 

They followed 102 children (between the ages of 5 and 17) who live in New Orleans. At the beginning of the study, field technicians laid traps for cockroaches.  Over the next 12 months, 53 of the children’s houses were visited six times to place the bait, and asthma was evaluated every 2 months by standardized questionnaires. The remaining 49 were in the control group, meaning that they did not get the insecticidal bait placed in their houses.

After 12 months, they found that cockroach levels were reduced in both groups, although the intervention had near complete elimination.  Compared to the control group, the group that had the baits place had 47 fewer days with symptoms over the year, and a 17% reduction in unscheduled Emergency room and unscheduled clinic visits.  Although benefit was mostly seen in children with cockroach allergy, the benefits were also seen in children without cockroach allergies, suggesting that irritation may also be a large part of why cockroach exposure drives asthma symptoms.

The investigators conclude by noting that because insecticidal bait is inexpensive and placement has a measurable impact on asthma outcomes, this could be a promising way to help reduce the burden of childhood asthma in other settings.  However, more studies are needed to replicate the findings on a larger scale.

Impact of school peanut-free policies on epinephrine administration

Food allergies are seen in up to 1 in 12 school-age children in the United States today, and peanut is one of the most common allergens.  In response, many schools have started to have peanut-free policies, but the effect of these policies has not yet been rigorously assessed.  In this month’s issue of JACI, Bartnikas and colleagues examine how peanut-free policies affect the rate of potentially fatal allergic reactions to peanut (J Allergy Clin Immunol 2017; 140(2): 465-473).  They looked at 2,223 public schools in Massachusetts during a five-year period, of which 6.3-10.3% banned peanuts from being brought from home, 56.6-59.1% banned peanuts from being served in school, 90.1-91.1% had peanut-free tables and 65.6-67.4% had peanut-free classrooms.  Among these schools, 46 (1.5-2.9%) self-designated as being a “peanut-free school,” but there was considerable variability in how these schools defined a self-designated “peanut-free school,” with 28.9% still allowing peanuts to be brought from home and 4.4% not providing peanut-free tables or classrooms. In the five-year study, 149 students had peanut or tree-nut exposure that required epinephrine, of which two were in self-designated peanut-free schools and one was in a school that did not self-designate as peanut-free but banned peanuts from both being brought from home and served by school.

What they found is that schools with peanut-free tables have lower rates of epinephrine administration, presumably because of fewer life-threatening allergic reactions.  Epinephrine administration rates were not significantly different in schools that had policies restricting peanuts from home, served in schools, or having peanut-free classrooms compared to those that didn’t have such policies. No policy resulted in complete absence of allergic reactions.

The investigators do note that there are limitations to their study.  There may be variability in how policies are interpreted and enforced and not all allergic reactions may have been accounted for if they were not treated with epinephrine.  Nevertheless, this study provides the first evidence to help guide schools in drafting policies regarding peanuts to help better safeguard children with peanut allergy.