A. E. Boniakowski1, A. Kimball1, A. Joshi1, S. Kunkel1, K. A. Gallagher1 1University Of Michigan,Ann Arbor, MI, USA
Introduction: Wound healing in chronic inflammatory diseases, such as diabetes, is impaired due to failed resolution of inflammation. Innate immune cells, particularly macrophages, play a significant role in the establishment of a regulated inflammatory response during wounding. Macrophage function is dictated by metabolism, which alters gene expression. The mitochondrial deacytlase enzyme, SIRT3, was recently shown to suppress inflammatory signaling and decrease reactive oxygen species; therefore we investigated the role of SIRT3 in inflammation in wound macrophages.
Methods: SIRT3 knockout (KO) mice and their littermate controls were either fed a normal diet or a high fat diet (HFD) for 12 weeks. They subsequently underwent 4mm hindlimb wounds, and CD3-CD19-NK1.1-CD11b+ (macrophages) were isolated from mouse wounds on days 1, 3, 5, and 7 using magnetic bead sorting. SIRT3 expression was quantified by qPCR.
Results: Utilizing a murine model of wound healing, CD3-CD19-NK1.1-CD11b+ (macrophages) isolated from wounds demonstrated a significant three fold increase in SIRT3 gene expression during the intermediate stage (day 3-5) of wound healing. Additionally, when we examined wound macrophages from our diet-induced obese (DIO) model of diabetes, we found that they did not upregulate SIRT3. To directly examine the role of SIRT3 in diabetic wound healing, we wounded our SIRT3KO on HFD and compared them to HFD littermate controls. We found our SIRT3KO animals on HFD demonstrated significantly delayed wound healing compared to HFD controls. (Fig 1)
Conclusion: SIRT3 is important in macrophages for normal wound healing and is decreased in macrophages from wounds of diabetic mice. These results suggest an important role for SIRT3 in regulating inflammation in wound healing.
