miR-369-3p Modulates LRRK2-Mediated Inflammation and Autophagy in RAW264.7 Macrophages.

Leucine-rich-repeat kinase 2 (LRRK2) is a multidomain protein highly expressed in immune cells and implicated in the regulation of immune functions including immune signaling, cytokine release and autophagy. LRRK2 is one of the therapeutic targets in Parkinson's Disease (PD). Aberrant activation of LRRK2 can also contribute to intestinal inflammation, mainly in inflammatory bowel disease (IBD). Hence the modulation of LRRK2 may influence gut inflammation providing an improvement in disease outcomes. Over the years, microRNAs (miRNAs) have acquired much attention thanks to their potential as therapeutic targets in several pathological conditions, including inflammatory disorders. In this study, we aimed to examine the ability of miR-369-3p in the modulation of autophagy targeting LRRK2 expression. Bioinformatics analysis revealed that Lrrk2 is a target gene of miR-369-3p, and LRRK2 expression was increased in ulcerative colitis patients compared with that in a healthy control. In in vitro analysis, we validated that mimic transfection with miR-369-3p in Raw264.7 significantly reduced the expression of LRRK2 both in basal and inflammatory conditions. Moreover, the inhibition of LRRK2 limited the nuclear translocation of Nuclear factor kappa B (NF-κB) induced by lipopolysaccharide (LPS) stimulation. In turn, we found that, in inflammatory conditions, the intracellular increase in miR-369-3p precluded the inhibition of autophagy by LRRK2 by restoring autophagy marker light chain 3 (LC3)II/I ratio, BECLIN-1 and decreasing p62 expression. Furthermore, we detected that the upregulation of miR-369-3p decreased the release of pro-inflammatory mediators Tumor necrosis factor (TNF), C-C motif ligand 2/Monocyte chemoattractant protein-1 (CCL2/MCP-1), C-C motif ligand 3/Macrophage inflammatory protein-1 alpha (CCL3/MIP-1α) and C-C motif ligand 5/Regulated on activation, normal T-cell expressed and secreted (CCL5/RANTES) and increased the anti-inflammatory cytokine interleukin 10 (IL-10) in response to LPS. This study supports the anti-inflammatory potential of miR-369-3p in immune cells and suggests the potential of miR-369-3p as a therapeutic agent in the treatment of acute intestinal inflammatory conditions such as ulcerative colitis.