Patient-centered outcomes research to improve asthma outcomes

Asthma is a devastating chronic disease that affects up to 24 million Americans.  It is more severe and prevalent among African Americans and Hispanics, especially Puerto Ricans.  There’s a two-fold increase in asthma mortality in Hispanic children and three-fold among African Americans, compared to Whites.  The causes of these disparities are complex, but are undoubtedly worsened by the observation that they are less likely to be treated according to the National Asthma Education Prevention Program (NAEPP) guidelines, which have been widely available for the past 20 years.  To address these issues, the Patient-Centered Outcomes Research Institute (PCORI) funded 8 studies to help patients and clinicians adhere to the guidelines.  In this month’s issue of the Journal of Allergy and Clinical Immunology, Anise and colleagues review these 8 randomized control trials (J Allergy Clin Immunol 2016; 138(6): 1503-1510).

Among the approaches being used are (1) clinician education, (2) clinical decision support, (3) patient education in the ER and clinic, (4) use of community health workers, and (5) use of long-term and quick-relief medications.    While each study has a distinct focus, all of them overlap in incorporating relevant stakeholders into the projects, and aligning local resources towards overarching, generalizable goals. 

The research projects are still underway, and results will not be available for at least two more years.  But these research projects are pioneering in the way that they are putting research in action in local communities, and embracing multi-faceted approaches with the understanding that single interventions may not be effective.

Home visits are needed to address asthma health disparities in adults

Asthma is a huge public health problem in the United States today.  But all asthmatics are not affected equally – there are a lot of disparities in asthma care.  In this month’s issue of the Journal of Allergy and Clinical Immunology, Bryant-Stephens and colleagues describe the need for home visits to address these asthma health disparities (J Allergy Clin Immunol 2016; 138(6): 1526-1530).  They note that most of the research on asthma so far has been on patients who go to clinics.  This has meant that people who have problems getting to the clinic, like the elderly, disabled, and those with other chronic conditions are often left out.  To help prevent overlooking these blindspots, they advocate for the involvement of community health workers.  In particular, they describe the experiences of three community health workers when they visited patients.  They found that the challenges at home are often overwhelming.  Social stressors in patients’ lives can be major problems interfering with their ability to take care of their asthma and other health problems. Community health workers may be used to provide resources to overcome these barriers and to encourage patients to adopt healthier habits, such as smoking reduction, and better communication with providers.   Even though home visits are not routine in clinical practice and are only rarely used in research settings, Bryant and colleagues suggest that there may be greater room for community health workers.  They recommend examination of the costs as well as benefits, and identifying vulnerable patients who would be best managed in this way.  They conclude that there needs to be better understanding of the barriers to optimal asthma management, so that these disparities can be addressed directly.

Innate lymphoid cells contribute to allergic airway disease exacerbation by obesity

Over the past 25 years, the rates of both obesity and asthma have increased dramatically.  These are related to one another, with a 92% increased risk of asthma in people whose body mass index (BMI) exceeds 30 kg/m². People who do lose weight through bariatric surgery or dietary restriction, tend to show improvement in their bronchial hyperresponsiveness, the major feature of asthma.  The reason for this correlation is not well understood.  IL-33, a intercellular messenger that skews helper T cells towards allergies, is produced by fat cells.  IL33 also induces type 2 and type 3 innate lymphoid cells (ILC2 and ILC3), two more recently identified sets of immune cells in fat and the lungs. 

In this month’s issue of the Journal of Allergy and Clinical Immunology, Everaere and colleagues use mouse models to investigate the roles of innate lymphoid cells in the correlation between asthma and obesity (J Allergy Clin Immunol 2016; 138(5): 1309-1318).  The mice were given a high-fat diet to induce obesity and were then sensitized to dust mites.  Their lung secretions were isolated by bronchoaveolar lavage (BAL) and checked for various proteins, RNA, and cell types by histology and flow cytometry. 

They found that nonsensitized obese mice had increased ILC counts and tissue eosinophils, cells that mediate damage in asthma, compared to lean mice.  These mice also had high IL33 and IL-1-Beta levels.  When ILCs were depleted using an anti-CD90 antibody, there was decreased infiltration by cells that prompt allergic inflammation, such as TH2 and TH17 cells.

Altogether, these results suggest that ILC2s and ILC3s mediate and exacerbate airway inflammation in obese mice.  This opens the possibility of using anti-IL5 antibodies in treating asthma for obese patients.

Allergic skin sensitization promotes eosinophilic esophagitis through the IL-33–basophil axis in mice

Eosinophilic esophagitis (EoE) is an allergic disorder seen in approximately 1 out of 2000 people in the United States.  Young children often present with vomiting and failure to thrive, while older children and adults may have difficulties swallowing, food impaction, or strictures in their esophagus.  Despite increasing awareness and diagnosis, the etiology remains unclear.  Past studies support the role of a subset of Helper T-cells, called TH2 cells, which are also present in many other allergic diseases, including atopic dermatitis (AD).  In fact, approximately half of patients with EoE have AD.  But why is that so?

In this month’s issue of the Journal of Allergy and Clinical Immunology, Venturelli and colleagues investigate the role of abnormal skin barriers in the development of EoE, and, in particular, the role of IL-33, a chemical messenger whose levels are elevated in both EoE and AD (J Allergy Clin Immunol 2016; 138(5): 1367-1380).  They also investigated the role of ST2, an IL-33 receptor found on basophils using a mouse model. They applied ovalbumin to the mechanically injured skin of wild-type mice, and then to the skin of mice lacking filaggrin (ft/ft), which tend to develop AD-like skin lesions.  They then challenged both strains of mice with intra-nasal ovalbumin.  The esophagi of these mice were then examined microscopically and through advanced genetic analytic techniques. 

They found that a disrupted skin barrier (by tape stripping or a Filaggrin gene mutation) promotes the development of EoE, and that this is mediated by IL-33, ST2, and basophils.  They also reported that patients with EoE have increased ST2 in their esophagus. Their findings suggest that IL-33 could be a potential link between AD and EoE.  This is an important step in understanding how patients with AD and filaggrin deficiency tend to develop EoE.  Just as importantly, it may prompt development of new medications that block IL-33 or ST2, which could be effective targets for EoE.

Diversity of TH cytokine profiles in patients with chronic rhinosinusitis: A multicenter study in Europe, Asia, and Oceania

Chronic Rhinosinusitis is a chronic disease of the sinuses that’s seen in up to 27% of adults in Europe and 14% in the United States.  Grouped in two categories, chronic rhinosinusitis with nasal polyposis (CRwNP) and chronic rhinosinusitis without nasal polyposis (CRsNP), chronic rhinosinusitis appears to be mediated by very distinct immune mechanisms.  Interestingly, there are differences in the clinical presentations between ethnic groups as well as in the types and levels of cytokines produced by immune cells. 

Wang and colleagues expand upon this prior knowledge by looking at 435 patients with chronic rhinosinusitis, and comparing them to 138 control subjects (J Allergy Clin Immunol 2016; 138(5): 1344-1353).  They were recruited from six regions covering Europe, Australia, and Asia.  They checked the levels of cytokines, inflammatory mediators and IgE, the antibody mediating allergies, from the mucosa of subjects.  The levels of these parameters were then compared among the different subjects.

They found that there was a large variety of expression of these cytokines among the different subjects in various regions.  This suggests that chronic rhinosinusitis is more of an umbrella term and that there are actually many different endotypes of patients with chronic rhinosinusitis.  

Asthma in the inner city: Three Analyses of the APIC Study

Asthma is an incredibly variable disease with its impact on people and molecular and cellular mechanisms what it does to the lungs and rest of the body.  This month’s issue of JACI features three articles by Zoratti et al (J Allergy Clin Immunol 2016; 138(4): 1016-1029), Pongracic et al (J Allergy Clin Immunol 2016; 138(4): 1030-1041), and Liu et al (J Allergy Clin Immunol 2016; 138(4): 1042-1050), covering asthma among inner city children.  They examine factors that determine the phenotype, severity and disease control, based on data they obtained from the Asthma Phenotypes in the Inner City (APIC) study, which looked at children aged 6 to 17 years and examined them every 2 months for one year.  Even though their techniques are all slightly different, all three analyses determined that allergic inflammation was a very significant contributor to disease.  In addition to rhinitis, pulmonary physiology also influenced severity and ability to control asthma despite guideline-based therapy.  Body mass index and environmental tobacco exposure were also quite significant in explaining severity of and ability to control disease activity, respectively.  Interestingly, Vitamin D did not have a significant effect on the control of asthma.  Altogether, the results of the APIC study provide insights into what strategies can be implemented to bring asthma under better control in inner cities.  Identifying those who are most at risk through the results of these studies, and targeting allergic inflammation, both in the upper or the lower respiratory passages, may help to reduce the burden of asthma.

Early-life gut microbiome composition and milk allergy resolution

Allergy to cow’s milk affects roughly one in fifty children, rendering them at risk for potentially deadly allergic reactions as well as for poor nutrition that comes with avoiding cow’s milk. In this month’s issue of JACI, Bunyavanich and colleagues relay the results of their research on how gut bacteria might influence the course of this disease (J Allergy Clin Immunol 2016; 138(4): 1122-1130).  They looked at the stools of 234 milk allergic children ranging in age from 3 to 16 months. They used 16s rRNA sequencing to profile the different types of gut bacteria and followed the children up to age 8 years.

They found that among children age 3 to 6 months, bacteria in the Firmicutes phylum and Clostridia class were associated with resolution of milk allergy by age 8 years.  This is consistent with preliminary findings from mouse models that also show that Clostridia have a role in regulating sensitization to food allergens.  However, these bacteria appear to have a very short time window to exert their effect, because there was no association in children beyond 6 months of age.  It is possible that the immune systems of infants up to six months of age are easier to tolerize, or that the introduction of solid foods at around age 6 months obscures this association.

It is possible that the fatty acids produced by bacteria may have potent roles in reestablishing tolerance, but the study was not structured to answer that question.  Other questions left to answer include whether supplementation with probiotics can help reestablish tolerance and whether introducing these bacteria would be safe.