Differential microRNA expression in R213G EC-SOD variant

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. Differential expression analysis identified 92 WT and 235 R213G miRs uniquely dysregulated in their respective genotypes. Subsequent pathway analysis identified that these miRs were predicted to regulate approximately half of the differentially expressed genes previously identified, and the gene targets of these altered miRs indicate suppression of immune and inflammatory pathways in the R213G mice versus activation of these pathways in WT mice. TREM1 signaling was identified as the inflammatory pathway with the most striking difference between WT and R213G lungs. miR 486b-3p was identified as the most dysregulated miR predicted to regulate the TREM1 pathway. We validated the increase in TREM1 signaling using miR 486b-3p antagomir transfection. These findings indicate that differential miR regulation is predicted to regulate the inflammatory gene profile, contributing to the protection against ALI in R213G mice.