An Overview of Asthma and COVID-19: Protective Factors Against SARS-COV-2 in Pediatric Patients

Abstract

Coronavirus disease 2019 (COVID-19) is a pandemic infectious disease caused by severe acute respiratory syndrome coronavirus SARS-COV-2. Aberrant innate immunity response and cytokine storm are responsible for the syndrome. Apparently, in asthmatic patients, the inadequate antiviral immune response and the tendency for asthma exacerbation evoked by common respiratory viruses could explain increased susceptibility to SARS-COV-2 infection. However, asthma has not been suggested to be a risk factor in COVID-19 patients. Therefore, in asthmatic patients some potential protective mechanisms against SARS-COV-2 have been hypothesized, like type 2 immune response, number of eosinophils, overproduction of mucus, and asthma treatment, along with behavioral factors not strictly related to asthma, such as social distancing, hygiene measures and wearing facemasks, that contribute to reduce the individual susceptibility to SARS-COV-2 infection. In this mini-review, we will describe the current literature regarding potential protective factors against COVID-19 in children with asthma based on the evidence available so far.

Facts and Challenges about Asthma and COVID-19 among the Paediatric Population: A Systematic Literature Review

“…Children have a lower concentration of ACE2 receptors and a high eosinophil concentration, which that could further contribute to protection against a COVID-19 infection [21,23,30,35]. Sensitisation to allergens among asthmatic children appears to de-crease the number of ACE2 receptors present in the airway [16,28,42]. Glycoproteins in the mucus such as Muc5ac play a role in making more difficult to COVID-19 to arrive to the distal airway and to cause an infection [28].…”

“…Two studies show that constant exposure to allergens and the consequent allergic sensitisation of asthmatic children also decrease these receptors [16,28]. In one of the studies, it is noted that the production of mucus and glycoproteins such as Muc5ac could prevent SARS-CoV-2 from reaching the distal airway and causing pathology [28,42].…”

“…Combined pharmacological treatment with nebulised budesonide, systemic steroids and nebulised salbutamol improves spirometric indices in the paediatric asthma population [43]. According to the Severe Asthma Research Program-3, inhaled corticosteroid treatment has been shown to decrease the number of ACE2 receptors and TMPRSS2 gene expression in sputum, both of which are associated with a reduced likelihood of SARS-CoV-2 entry through the airway [22,42]. Moreover, the combination of inhaled corticosteroids with bronchodilators in vitro decreases coronavirus replication and cytokine production [23].…”

COVID-19 Pandemic and Reduced Physical Activity: Is There an Impact on Healthy and Asthmatic Children?

“…Noteworthy, social distancing and facemasks have been proposed to reduce respiratory viral infection, leading to less hospital admission for asthma exacerbation in adults. Wearing facemasks has been proved to be protective against respiratory infections which are a common trigger of asthma exacerbation ( 39 ). Indeed, a large study in Hong Kong reported that the number of admissions for asthma exacerbation was reduced by 53.2% (95% CI 50.4–55.8%, p < 0.0001) in 2020 compared with past 5 years; admissions for asthma exacerbation decreased by 0.8% with every 1% increase in masking (95% CI 0.8–0.9%, p < 0.0001) ( 40 ).…”

Interleukin role in the regulation of endothelial cell pathological activation

“…So far, only indirect evidence is reported on expression of IL36 in SARS-CoV-2 infected patients ( 59 ). It should be also considered that IL36 is highly expressed in the lungs of allergic and asthma-affected patients, but studies have shown that asthma is not a risk factor in SARS-CoV-2-infected patients ( 60 ). Therefore, there is the possibility that IL36 inflammatory circuit contributes to protect patients with asthma against detrimental outcomes of SARS-CoV-2 infection.…”