Abstract 255: Fatty Acid Binding Protein 4, FABP4, Causes Impaired Wound Healing in Diabetes

Wound healing in diabetes is impaired due to failed resolution of inflammation. 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. Recent studies suggest that a fatty acid binding protein, FABP4, may control macrophage function in diabetes by altering metabolism. Thus, we examined whether FABP4 controls macrophage function and hence inflammation in diabetic wound healing. To investigate this, C57BL/6 mice were fed either a normal (12% saturated fat) diet or a high-fat (60% saturated fat) diet (HFD) for 12 weeks to induce physiologic “pre-diabetes.” Wounds were created and CD3-CD19-NK1.1-CD11b+ cells (macrophages) were isolated each day following injury and FABP4 expression was quantified by qPCR and Western blot. We found that HFD wound macrophages demonstrated a significant increase in FABP4 gene expression and protein production on day 3 post-injury compared with controls. To determine if FABP4 alters inflammatory gene expression in wound macrophages, we isolated wound macrophages with an FABP4 inhibitor, treated them, and analyzed for IL-1β and TNFα expression. IL1β and TNFα gene expression were significantly reduced (P Chromatin immunoprecipitation (ChIP) analysis of the FABP4 promoter in wound macrophages revealed a significant increase in H3K4 trimethylation, an activating mark, on the FABP4 promoter in diabetic wound macrophages suggesting that epigenetic regulation may play an important role in the differential expression of FABP4 in diabetic wounds. In conclusion, FABP4 appears to be upregulated in diabetic wound macrophages and contributes to increased macrophage inflammation. Modulation of FABP4 or its expression may help resolve inflammation in diabetic wounds and promote healing.