C. E. Liechty1, J. Hu1, C. Zgheib1, K. W. Liechty1, J. Xu1 1Laboratory For Fetal And Regenerative Biology, Children’s Hospital Colorado And The University Of Colorado Anschutz Medical Campus,Department Of Surgery,Aurora, CO, USA
Introduction:
Macrophages have the ability to dynamically transition between M1 (pro-
inflammatory) and M2 (anti-inflammatory) phenotypes in response to signals from the
surrounding microenvironment. Prolonged M1 macrophage polarization is thought to play a
central role in the chronic inflammation and pathogenesis of diabetic wounds. Recent studies
reveal that long non-coding RNAs (lncRNAs) play important regulatory roles in many biological
processes. However, the role of lncRNAs in macrophage polarization or in diabetic wounds
remains undefined. We have previously shown that lncRNA GAS5 (Growth Arrest-Specific 5) is
up-regulated in diabetic wounds. We hypothesize that increased GAS5 expression contributes
to prolonged M1 macrophage polarization in diabetic wounds.
Methods:
To test our hypothesis, we incubated the murine macrophage cell line RAW264.7
with media containing 5 mM glucose (low glucose), or 25 mM glucose (high glucose) for 4, 8,
and 24 hours and examined GAS5 gene expression by Real-time PCR. In addition, we
examined macrophage polarization and STAT1 gene expression in response to GAS5
overexpression using plasmid transfection.
Results:
High glucose conditions significantly induced macrophage GAS5 gene expression in a
time dependent manner. Plasmid mediated over-expression of GAS5 resulted in significantly
increased gene expression of M1 macrophage markers (iNOS, TNFa, and IL1-Beta), while
demonstrating no change M2 macrophage markers (Arg1, and Mrc1). Mechanistically, GAS5
overexpression promoted M1 macrophage through significantly induced STAT1 expression, the
crucial transcriptional factor for M1 activation.
Conclusion:
These findings provide the first evidence that the lncRNA GAS5 is involved in the
regulation of macrophage polarization. Furthermore, these results suggest a potential role of
lncRNA GAS5 in the pathogenesis of the diabetic wound healing impairment and may represent
a novel therapeutic target to correct the diabetic wound healing impairment.