Июн
18,
2020
Июн 18, 2020
As we’re entering the summer season, we’re facing a host of allergens that can trigger respiratory disorders. «Summer allergies can cause severe symptoms for some sufferers, and can be just as bad as the spring and fall seasons,» said allergist Michael Foggs, MD, president of the American College of Allergy, Asthma and Immunology (ACAAI).[1]
Allergies may start in patient with genetic predisposition and exposition to allergens. They are the consequence of an immune system dysfunction: it unwittingly fights against substances that are not normally deemed harmful, allergens. Pollens, mites, pollen allergens, animal protein, atmospheric molds are susceptible to enhance allergic reactions.
Allergic reactions may cause inflammation that, in turn, can be exacerbated by respiratory infections.
The number of people developing allergies has considerably increased over the past few decades. Allergies affect 25% to 30% of the world population.
The same allergens that trigger allergic reactions with some people can cause asthma attacks in others. Allergic asthma is the most common type of asthma : 90% of children with childhood asthma have allergies.
Asthma is an extremely common chronic and potentially life-threatening condition that affects 300 millions of people worldwide and nearly 10% of children.[2] It is a chronic inflammatory airways condition and people with asthma find it harder to breathe in and out, because the airways in their lungs become narrower.
The main symptoms of asthma are a whistling sound when breathing (wheezing), breathlessness, a tight chest and coughing.
In asthma, the airway wall thickens in proportion to disease severity and duration. This remodeling involves an increase in airway smooth muscle, thickening of the subepithelial reticular lamina, matrix deposition throughout the airway wall, angiogenesis, neuronal proliferation and epithelial mucous metaplasia — a process that involves the appearance of mucous cells in new areas of the airways and increased production of mucus.
Through a continuing cycle of epithelial injury and repair, chronic inflammation and airway remodeling occur in parallel to create the disease chronicity that is characteristic of asthma. Superimposed on this chronicity is the acute worsening of asthma (also termed asthma exacerbation), which is most often driven by common respiratory viruses, allergen exposure and air pollutants. [3]
Figure : Cross section of a severe asthmatic airway (right) compared with a normal airway (left). Asthma involves mucosal inflammation that most frequently consists of activated eosinophils, mast cells and T lymphocytes within the context of a remodelled airway with mucous metaplasia, an increase in smooth muscle (Sm), fibrosis and angiogenesis. Bm, basement membrane; Bv, blood vessel; Ep, epithelium. Republished with permission of Dove Medical Press, from Clinical update on the use of biomarkers of airway inflammation in the management of asthma. Wadsworth, S., Sin, D. & Dorscheid, D., 4, 2011; permission conveyed through Copyright Clearance Center, Inc.
Prevention for allergic asthmatic people presents many advantages, in particular to avoid other infections and to limit the consequences of asthma attacks to protect airways tracts. Prevention can be a course of allergy desensitization treatments in association with treatments against RTI.
If we cannot do anything about our age or genetics, the external risk factors can be acted upon. A large part of keeping asthma under control and preventing ‘asthma attacks’ involves preventative measures like avoiding known triggers. A healthy lifestyle based on regular exercise, balance diet, avoiding polluted environments, tobacco smoke, drugs and alcohol consumption etc. is recommended to maintain a good level of natural defenses and remain healthy.
If these methods can be sufficient for most adults with no particular susceptibility to respiratory diseases, it can be insufficient for various at-risk populations. For most of these patient groups, immunisation is recommended as a safe and effective preventive method.
Combination medications can also be prescribed: a corticosteroid plus a bronchodilator. The bronchodilator opens the airways, making it easier to breathe. The inhaled corticosteroid reduces inflammation in the airways.
A recent clinical study EOLIA study (Efficiency Of Lysate In Asthmatic children) highlighted that immunostimulation with bacterial lysate, could also help control the course of asthma and represent an interesting tool for asthma management. Indeed the « administration of PMBL® Tablet represents a safe and effective means for significantly reducing the rate of exacerbations in school-aged allergic asthmatic children. » [4]
In fact asthma is the most common chronic disease of childhood. Asthma also has 1 of the top 10 highest rankings for disability-adjusted life years in school-aged children. « Although inhaled corticosteroids are recommended as first-line therapy, it has less efficacy in controlling intermittent wheeze due to viral-induced symptoms in early childhood. (…) Bacterial lysates work at multiple stages in the innate and adaptive immune response and have been shown to decrease mean wheeze duration in particular in the preschool age. More research is required although both therapies offer a promising future approach, in particular in the nonatopic preschool wheezer, as we move toward a more personalized approach to childhood asthma. » [5]
Polyvalent bacterial lysates (PBL) have been used for many years to prevent respiratory tract infections in children and adults. Another study conducted in 2019 demonstrated that « PMBL was able to significantly improve Seasonal allergic rhinitis (SAR) symptoms in children. »[6]
In another recent article, the administration of bacterial lysates as another immunomodulatory strategy, particularly appealing in pediatric asthma, is positively reviewed : « Two main therapies have been described: polyvalent mechanical bacterial lysates (PMBL®) and Broncho-Vaxom OM-85 BV. They contain lysates of 8 pathogenic bacteria including H. influenzae and S. pneumoniae. Both PMBL® and OM-85 administration have proven to be efficient in preventing respiratory tract infections in adult and pediatric patients with chronic bronchitis and/or history of recurrent chronic infections » [7]
REFERENCES :
[1] https://acaai.org/news/ugly-truth-about-summer-allergies
[2] Dharmage SC, Perret JL, Custovic A. Epidemiology of Asthma in Children and Adults. Front Pediatr. 2019;7:246. Published 2019 Jun 18. doi:10.3389/fped.2019.00246
[3] https://www.nature.com/articles/nrdp201525#MOESM529
[4] Emeryk A, Bartkowiak-Emeryk M, Raus Z, Braido F, Ferlazzo G, Melioli G. Mechanical bacterial lysate administration prevents exacerbation in allergic asthmatic children—The EOLIA study. Pediatr Allergy Immunol. 2018;29:394–401. https://doi.org/10.1111/pai.12894
[5] Elissa M. Abrams, MD, FRCPC and Hengameh H. Raissy. Emerging Therapies in the Treatment of Early Childhood Wheeze.
[6] Kamil P. Janeczek, Andrzej Emeryk, Piotr Rapiejko, « Effect of polyvalent bacterial lysate on the clinical course of pollen allergic rhinitis in children », Advances in Dermatology and Allergology 4, August / 2019
[7] L.Stéphanie, D. Antoine, L. Rouzic Olivier, E. Ilka, D. Rodrigue, P. Muriel, G., Philippe, Childhood asthma heterogeneity at the era of precision medicine: Modulating the immune response or the microbiota for the management of asthma attack, Biochemical Pharmacology (2020), doi: https://doi.org/10.1016/j.bcp.2020.114046