MicroRNAs (miRNAs) have been implicated in the pathogenesis of many diseases including atopy and asthma. We investigated whether we could identify serum microRNAs in early childhood that could be used to predict the development of wheezing in children.
The study protocol was approved by the Committee on Human Research of Chiba University. Preliminary microarray analysis revealed the dysregulation of several miRNAs including hsa-miR-185-5p. The samples used in this study were from the birth cohort samples consisting of cord blood, 1-year and 2-year samples. The samples were categorized according to wheezing status and allergen-specific IgE levels at 2 years. Children with more than 3 episodes of wheezing during the preceding 12 months were considered "wheezers", while those without were "non-wheezers". MiRNAs were extracted from the serum of birth cohort samples using a commercial column-based kit. The hsa-miR-185-5p levels were quantified using real-time PCR. Ce_miR-39_1 was used as the spike-in-control and the difference in expression level of the hsa-miR-185-5p and Ce_miR-39_1 was used as the cycle threshold (ΔCt). The data was analyzed using non-parametric tests on GraphPad Prism version 6.0.
The hsa-miR-185-5p levels were significantly elevated between the ages of 1 and 2 years in non-wheezers at the age of 2 years, while the levels were consistent in wheezers. This suggests that increase of hsa-miR-185-5p levels may be a negative indicator of recurrent wheezing and potentially asthma in later childhood. We did not see any correlation between allergen-specific igE levels and hsa-miR-185-5p.
Hsa-miR-185-5p may be a useful to identify potential wheezing during the first years of life. The target genes and the regulators of this miRNA are being verified.