Complex Regional Pain Syndrome (CRPS) is a chronic, debilitating pain condition
and neurogenic inflammation known to contribute to persistent pain. MicroRNAs
(miRNAs) are small noncoding RNAs that negatively regulate gene expression by
binding to the 3’untranslated region (3’UTR) of target mRNAs. A previous study in
our lab identified 18 miRNAs and inflammatory markers, including hsa-miR-939,
vascular endothelial growth factor (VEGF) and monocyte chemotactic protein-1
(MCP1), as significantly altered in blood from CRPS patients. In this study, we
investigated whether the downregulation of hsa-miR-939 contributes to the
upregulation of several proinflammatory genes in CRPS. Our goal was to investigate
in vitro, how decreases in miR-939 modulates proinflammatory proteins. Human-
derived monocytic THP-1 cells and human umbilical vein endothelial cells
(HUVECs) were transfected with miR-939 and treated with MCP-1or endotoxin LPS.
Changes in the expression levels of proinflammatory proteins predicted to harbor
miR-939 binding sites in their 3’UTR, including iNOS, TNFAIP1, NFkB, VEGFA,
TNFα, and IL-6, were measured. Additionally, to determine the temporal regulation of
genes by miR-939, western blot and enzyme-linked immunoabsorbant assays were
performed at different time points. Our results show that miR-939 downregulates
iNOS, TNFAIP1and IL-6, supporting that miR-939 does have a role in inhibiting
inflammatory proteins. Moreover, when the transfected cells were treated with MCP-
1, iNOS and TNFAIP1 were restored, indicating that chemotactic responses of MCP-1
overcome the effect of miR-939. Our studies suggest that miR-939 can simultaneously
modulate multiple proinflammatory genes, amplifying the signal transduction cascade
leading to chronic inflammation and pain.
