Association of polymorphisms in IL-4, IL-5, IL-13 or IL-10 genes and childhood asthma: a systematic review

Objective: The inflammatory reaction observed in asthma is due to the activation of Th2 lymphocytes, the action of cytokines IL-4, IL-5, IL-9 and IL-13 and the production of IgE. It is estimated that different genes and their polymorphisms influence the development of the disease. This study presents the results of systematically selected articles about the association of polymorphisms in genes of cytokines IL-4, IL-5, IL-13, IL-10 and asthma phenotype, the disease severity and atopy in children. Data source: 15 scientific articles published between 1999 and 2008 were selected from major databases. Data synthesis: Regarding the association between polymorphisms in different gene regions and the clinical diagnosis of asthma, 50% (4/8) of the articles about IL-4 stated the existence of a significant association and 80% (4/ 5) of those that studied IL-13 presented the same conclusion. However, in studies about genes of IL-5 and IL-10 no positive associations were found. For the variable levels of severity and/or the existence of atopy, 67% (4/6) and 100% (5/5) of the studies showed an association with genes of IL-4 and IL-13, respectively. Regarding genes of IL-5 and IL-10, a significant association was observed, but it was not possible to point out conclusions, due to the poor number of articles available. Conclusions: The results of this systematic review highlight the role of polymorphisms in genes of IL-4 and IL-13 in the induction of asthma phenotypes, severity of symptoms and/or atopy. Also, this review emphasizes the need for further studies about the participation of polymorphisms of IL-5 and IL-10 in the different asthma phenotypes.