Abstract 190: Epigenetic Modifications of Pro-inflammatory Gene Expression in Macrophages by a Demethylase Enzyme, JMJD3, May Promote Chronic Inflammation in Type 2 Diabetic (T2D) Wounds
Introduction Type 2 diabetic(T2D) wounds are characterized by chronic inflammation, maintained by an exaggerated M1(pro-inflammatory) macrophage phenotype response. We seek to define a link between epigenetic modifications of bone marrow(BM) cells in T2D and dysregulated macrophages in wounds. We hypothesized that a chromatin modifying demethylase enzyme, JMJD3, is responsible for the decrease in H3K27me3 repressive methylation at the IL-12 gene promoter and thus drives an M1 macrophage phenotype in T2D wounds.
Methods BM/adipose tissue(AT)/wounds were harvested from 30 diet-induced obese mice(DIO)(MG= 350g/DL) and 30 matched(WT) controls. For chromatin immunoprecipitation(ChIP) analysis, cells were isolated via ferromagnetic columns(CD34+,CD11b+). ChIP to detect histone methylation at the promoter regions of JMJD3 and IL-12(key M1 macrophage gene) was performed and RNA analysis was done with standard primers.
Results JMJD3 mRNA in the BM is significantly increased in the DIO versus WT. ChIP showed increased H3K4me3(gene expression mark) in CD34+ progenitor cells and a corresponding decrease in H3K27me3(repressive mark) in monocytes at the promoter region of JMJD3. These changes correspond with the decrease in H3K27me3 seen at the IL-12 promoter in macrophages(CD11b+) from AT/T2D wounds.
Conclusions Epigenetic changes initiated by JMJD3 in BM progenitor cells result in changes in histone methylation at the IL-12 promoter favoring an M1 phenotype in macrophages and thus contributes to the chronic inflammation seen in T2D wounds and AT. Whether manipulation of epigenetic enzymes could reduce chronic inflammation in T2D wounds requires further work.
- © 2013 by American Heart Association, Inc.