Inflammation potentiates miR-939 expression and packaging into small extracellular vesicles.

Area of Science:

• Cell Biology
• Molecular Biology
• Immunology

Background:

• Extracellular RNA, including microRNAs (miRNAs), mediates intercellular communication.
• Small extracellular vesicles (sEVs) transport miRNAs in bodily fluids, influencing recipient cell gene expression.
• Complex regional pain syndrome (CRPS) involves chronic inflammation, with prior studies showing decreased hsa-miR-939 in CRPS whole blood but increased levels in serum-derived sEVs.

Purpose of the Study:

• To investigate the packaging of miR-939 into sEVs under inflammatory conditions.
• To explore the role of miR-939 and sEVs in the pathophysiology of CRPS.
• To identify mechanisms of miR-939 sorting into sEVs.

Main Methods:

• Monocyte chemoattractant protein-1 (MCP-1) was used to induce inflammation in THP-1 monocytes.
• Exosome secretion inhibitors were employed to study miR-939 packaging.
• Mutation analysis of miR-939's EXOmotif was performed.
• RNA sequencing was used to analyze gene expression changes in recipient cells after sEV uptake.
• Analysis of miR-939 levels in sEVs derived from primary immune cells of CRPS patients and controls.

Main Results:

• MCP-1 stimulation elevated miR-939 levels in sEVs, an effect inhibited by exosome secretion inhibitors.
• miR-939's EXOmotif was identified as a potential mechanism for its packaging into sEVs.
• Uptake of miR-939-enriched sEVs altered gene expression in recipient cells.
• While B cell-, T cell-, and NK cell-derived sEVs showed higher relative miR-939 than monocyte-derived sEVs in controls, only B cell-derived sEVs had significantly higher miR-939 in CRPS patients.

Conclusions:

• Inflammation induces miR-939 packaging into sEVs, potentially via EXOmotifs.
• Differential sorting of miR-939 into specific immune cell-derived sEVs, particularly B cells, may contribute to CRPS pathophysiology.
• miR-939 carried by sEVs can functionally impact recipient cells, highlighting their role in intercellular communication in CRPS.