Abstract 144: Bone-Marrow Chimeras Demonstrate that the Epigenetic Signature in the Bone Marrow Myeloid Cells Influences the Peripheral Wound M1-Dominant Macrophage Phenotype
Introduction: Diabetic wounds are characterized by a chronic inflammatory state that is maintained by overexpression of pro-inflammatory cytokines generated by macrophages. In normal wound healing, macrophages mobilized from the circulation initially exhibit an M1 phenotype and secrete pro-inflammatory mediators (i.e., IL-12) followed by a prolonged M2 anti-inflammatory phase. In type 2 diabetes (T2D), this M1 to M2 switch appears to be markedly attenuated. We have previously demonstrated that post-translational histone methylation changes in BM cells are maintained in peripheral macrophages and promote an M1 dominant phenotype in T2D wounds that result in impaired wound healing. We hypothesize that chimeric mice reconstituted with bone marrow from our T2D murine model will demonstrate delayed wound healing and expression of this epigenetic signature in peripheral wound macrophages.
Methods: BM chimeras were created using GFP+ mice on a C57BL/6 background. GFP+ mice were fed a high-fat diet (HFD, 60% fat) for 14 weeks and BM from these mice and normal diet (ND, 12% fat) mice was transferred into irradiated recipients. Change in wound area compared to initial wound size using Image J software (NIH) at day 3 post-wounding. Levels of the demethylase enzyme, Jmjd3, in macrophages (CD11b+) MACS isolated from wounds at day 3 were quantified by RT-PCR in ND→ND and HFD→ND GFP+ chimeric mice. (N=8) Data are expressed as mean ± S.E.
Results: Peripheral blood analysis was performed weekly and at 8 weeks confirmed 96.5% donor chimerism. Wound healing was significantly delayed in HFD→ND GFP+ chimeric mice compared to controls and analysis of wound tissue macropahges in mice at day 3 post-wounding demonstrated increased Jmjd3 and IL-12 production.
Discussion: Epigenetic changes in BM cells appear to be maintained in peripheral wound macrophages and contribute to increased M1 macrophages and impaired wound healing in T2D wounds.
Author Disclosures: K.A. Gallagher: None. A. Joshi: None. E. Hogikyan: None. D. Coleman: None. W. Carson: None. S. Kunkel: None.
- © 2014 by American Heart Association, Inc.