Validation of the breathmobile case identification survey for asthma screening in children with sickle cell disease

Screening for asthma in preschool children with sickle cell disease

BACKGROUND

Asthma in preschool children is poorly defined, proving to be a challenge for early detection. The Breathmobile Case Identification Survey (BCIS) has been shown to be a feasible screening tool in older SCD children and could be effective in younger children. We attempted to validate the BCIS as an asthma screening tool in preschool children with SCD.

METHODS

This is a prospective, single-center study of 50 children aged 2-5 years with SCD. BCIS was administered to all patients and a pulmonologist blinded to the results evaluated patients for asthma. Demographic, clinical, and laboratory data were obtained to assess risk factors for asthma and acute chest syndrome in this population.

RESULTS

Asthma prevalence (n = 3/50; 6%) was lower than atopic dermatitis (20%) and allergic rhinitis (32%). Sensitivity (100%), specificity (85%), positive predictive value (30%), and negative predictive value (100%) of the BCIS were high. Clinical demographics, atopic dermatitis, allergic rhinitis, asthma, viral respiratory infection, hematology parameters, sickle hemoglobin subtype, tobacco smoke exposure, and hydroxyurea were not different between patients with or without history of ACS, although eosinophil was significantly lower in the ACS group (p = 0.0093). All those with asthma had ACS, known viral respiratory infection resulting in hospitalization (3 RSV and 1 influenza), and HbSS (homozygous Hemoglobin SS) subtype.

CONCLUSION

The BCIS is an effective asthma screening tool in preschool children with SCD. Asthma prevalence in young children with SCD is low. Previously known ACS risk factors were not seen, possibly from the beneficial effects of early life initiation of hydroxyurea.

Lack of iron, zinc, and vitamins as a contributor to the etiology of atopic diseases

Micronutritional deficiencies are common in atopic children suffering from atopic dermatitis, food allergy, rhinitis, and asthma. A lack of iron, in particular, may impact immune activation with prolonged deficiencies of iron, zinc, vitamin A, and vitamin D associated with a Th2 signature, maturation of macrophages and dendritic cells (DCs), and the generation of IgE antibodies. In contrast, the sufficiency of these micronutrients establishes immune resilience, promotion of regulatory cells, and tolerance induction. As micronutritional deficiencies mimic an infection, the body's innate response is to limit access to these nutrients and also impede their dietary uptake. Here, we summarize our current understanding of the physiological function of iron, zinc, and vitamins A and D in relation to immune cells and the clinical consequences of deficiencies in these important nutrients, especially in the perinatal period. Improved dietary uptake of iron is achieved by vitamin C, vitamin A, and whey compounds, whereas zinc bioavailability improves through citrates and proteins. The addition of oil is essential for the dietary uptake of beta-carotene and vitamin D. As for vitamin D, the major source comes via sun exposure and only a small amount is consumed via diet, which should be factored into clinical nutritional studies. We summarize the prevalence of micronutritional deficiencies of iron, zinc, and vitamins in the pediatric population as well as nutritional intervention studies on atopic diseases with whole food, food components, and micronutrients. Dietary uptake via the lymphatic route seems promising and is associated with a lower atopy risk and symptom amelioration. This review provides useful information for clinical studies and concludes/emphasizes that a healthy, varied diet containing dairy products, fish, nuts, fruits, and vegetables as well as supplementing foods or supplementation with micronutrients as needed is essential to combat the atopic march.

Iron-Deficiency in Atopic Diseases: Innate Immune Priming by Allergens and Siderophores

Although iron is one of the most abundant elements on earth, about a third of the world's population are affected by iron deficiency. Main drivers of iron deficiency are beside the chronic lack of dietary iron, a hampered uptake machinery as a result of immune activation. Macrophages are the principal cells distributing iron in the human body with their iron restriction skewing these cells to a more pro-inflammatory state. Consequently, iron deficiency has a pronounced impact on immune cells, favoring Th2-cell survival, immunoglobulin class switching and primes mast cells for degranulation. Iron deficiency during pregnancy increases the risk of atopic diseases in children, while both children and adults with allergy are more likely to have anemia. In contrast, an improved iron status seems to protect against allergy development. Here, the most important interconnections between iron metabolism and allergies, the effect of iron deprivation on distinct immune cell types, as well as the pathophysiology in atopic diseases are summarized. Although the main focus will be humans, we also compare them with innate defense and iron sequestration strategies of microbes, given, particularly, attention to catechol-siderophores. Similarly, the defense and nutritional strategies in plants with their inducible systemic acquired resistance by salicylic acid, which further leads to synthesis of flavonoids as well as pathogenesis-related proteins, will be elaborated as both are very important for understanding the etiology of allergic diseases. Many allergens, such as lipocalins and the pathogenesis-related proteins, are able to bind iron and either deprive or supply iron to immune cells. Thus, a locally induced iron deficiency will result in immune activation and allergic sensitization. However, the same proteins such as the whey protein beta-lactoglobulin can also transport this precious micronutrient to the host immune cells (holoBLG) and hinder their activation, promoting tolerance and protecting against allergy. Since 2019, several clinical trials have also been conducted in allergic subjects using holoBLG as a food for special medical purposes, leading to a reduction in the allergic symptom burden. Supplementation with nutrient-carrying lipocalin proteins can circumvent the mucosal block and nourish selectively immune cells, therefore representing a new dietary and causative approach to compensate for functional iron deficiency in allergy sufferers.