MiR-137-5p Alleviates Inflammation by Upregulating IL-10R1 Expression in Rats with Spinal Cord Injury

Objective: This study aims to explore the potential functions of miR-137-5p and interleukin-10R1 (IL-10R1) in mediating the immune inflammation after spinal cord injury (SCI).

Materials And Methods: Firstly, primary microglia were isolated from the spinal cord of newborn rats. Expression levels of miR-137-5p and IL-10R1 in LPS-induced microglia were determined by quantitative Real-time polymerase chain reaction (qRT-PCR). In addition, mRNA expressions of Janus kinase (Jak1) and signal transducer and activator of transcription 3 (STAT3) were also examined by qRT-PCR. SCI model in rats was established and randomly assigned to three different groups: Sham group, SCI group and miR-137-5p mimic group. Within one week of spinal injury, relative levels of miR-137-5p and IL-10R1 in rats of different groups were detected by qRT-PCR. The mRNA levels of JAK1, tyrosine kinase (Tyk2) and STAT3 in rats were also measured. Moreover, protein expression of IL-1β, TNF-α and IL-6 in rats was measured by Western blotting. Finally, the improvement of locomotor function in three groups of rats within 4 weeks via BBB rating scale.

Results: Transfection of miR-137-5p mimics upregulated relative levels of IL-10R1, JAK1 and STAT3 in in vitro cultured microglia. Similarly, IL-10R1/JAK1/STAT3 pathway was activated in rats administrated with miR-137-5p mimics. Nevertheless, relative levels of classical inflammatory stimulators IL-1β, TNF-α and IL-6 were downregulated accordingly by miR-137-5p overexpression. Moreover, miR-137-5p effectively improved the locomotor function of rats after SCI.

Conclusions: MiR-137-5p exerts an anti-inflammatory response by upregulating IL-10R1, thus improving locomotor function and alleviating spinal cord injury.