Differential microRNA expression of R213G extracellular superoxide dismutase mice in the setting of inflammation resolution and attenuated acute lung injury

Purpose: Oxidative stress is a key contributor to the development of dysregulated inflammation in acute lung injury (ALI). A naturally occurring single nucleotide polymorphism in the key extracellular antioxidant enzyme, extracellular superoxide dismutase (EC-SOD), results in an arginine to glycine substitution (R213G) which promotes resolution of inflammation and protection against bleomycin-induced ALI. Previously we found that mice with the R213G mutation in EC-SOD have an inflammation-resolving transcriptomic profile at 7 days post-bleomycin However, the epigenetic differences between WT and R213G EC-SOD lungs have not been examined. Therefore, we used Next Generation microRNA (miR) Sequencing of lung tissue to identify dysregulated miRs 7 days after bleomycin in wild-type (WT) and R213G mice. Methods: WT and homozygous R213G EC-SOD (rs1799895) mice received one intratracheal administration of bleomycin in phosphate-buffered saline (PBS) (100 uL at 1 U/mL) or PBS at 8-12 weeks old. Lungs were harvested and frozen. Frozen lungs were homogenized, placed in Qiazol, and RNA was isolated using the miRNeasy Mini Kit (Qiagen). Samples underwent 1x150, directional, single-end sequencing using the Illumina hiSEQ 4000 system. Results: 1424 microRNAs were detected. Up/Down regulated microRNAs were defined as havinga FC > 1.2 and p <0.05. microRNAs "unique" to a genotype were defined as meeting the prevoius criteria in only one strain, or in both with a fold change 1.5x greater in one over the other. This method identified 92 WT and 235 R213G miRs uniquely dysregulated in their respective genotypes. Overall design: Lung microRNA profiles of 11-week-old WT and R213G mice with intratracheal PBS (control) or bleomycin-induced lung injury from Illumina sequencing.