Conclusion
miRNA research, thus far, has led to a breadth of information and long lists of potentially interesting miRNAs, but mechanistic studies of miRNA targeting and function are only beginning to emerge. Furthermore, it is unlikely that one miRNA alone holds the key to explain the pathology of asthma or allergic diseases, as it is not possible to outline a single trigger. More likely, there are numerous players and complex networks of interactions that lead not only to disease pathogenesis, but also to heterogeneity, making mechanistic insight into the roles of miRNAs all the more important going forward. We propose that understanding common triggers for changes in miRNA expression in distinct cell populations, at defined disease stages and in specific phenotypes, together with assessing the net effects of miRNAs will help to decipher the pathophysiological consequences of altered miRNA expression in allergic diseases. Nonetheless, we have provided important evidence highlighting a crucial role of miRNA in the pathogenesis of asthma and allergic disease, making them interesting targets for clinical investigations. Besides therapeutic strategies to target single miRNA123,124,134,156-158, there is increasing interest in using miRNA profiles as biomarkers for (lung) disease48,58,62,159-163, which we will address in detail in a future review.