RESUMEN
There is no unequivocal definition of exacerbation in asthma. These are defined as episodes of increased or aggravated respiratory symptoms or as use of oral corticosteroid therapy. Viral infection is the most frequent cause of exacerbations. Inflammation during exacerbations is heterogeneous. It may be associated with bronchial hypereosinophilia, which is used as a predictive marker for exacerbation, and with neutrophilia, which is more resistant to corticosteroids. During viral infection, an inappropriate Th1 antiviral inflammation develops, associated with the intrinsic Th2 activity that leads to an aberrant immune response. Exacerbations secondary to allergen exposure are classically described as due to a Th2-type inflammation; but Th1 response also seems to play a role. Exposure to air pollutants appears able not only to induce bronchial inflammation but also to potentiate the inflammatory reactions of patients with exacerbations.
Asunto(s)
Asma/complicaciones , Asma/inmunología , Asma/virología , HumanosRESUMEN
Appeared at the beginning of the 20th century, allergen-specific immunotherapy (SIT) has long been used in allergic rhinitis and asthma without any knowledge of its mechanisms of action or any tangible proof of its efficacy. However, from the beginning of the era of evidence-based medicine, a number of placebo-controlled studies have been published and reached a sufficient number to assess the cellular events induced by SIT and allow meta-analysis to provide guidelines based on proofs. Controlled studies and meta-analysis concerned not only subcutaneous immunotherapy but also the sublingual route, demonstrating an effect of SIT on symptoms and medication use. Most recently sublingual tablets were proposed in allergic rhinitis. This paper reviews the mechanisms of SIT, the evidence of efficacy of SIT from the injective to the sublingual route and reminds the current guidelines.