C. Audu1, S. Wolf-Fortune2, W. J. Melvin1, F. Davis1, A. DenDekker2, S. Sharma1, K. Mangum1, E. Barrett1, A. Joshi2, A. Obi1,2, B. Moore2, K. A. Gallagher1,2 1University Of Michigan,Vascular Surgery,Ann Arbor, MI, USA 2University Of Michigan,Microbiology & Immunology,Ann Arbor, MI, USA
Introduction: CD4+T-cells are vital for normal wound repair but the factors that control T-cell activation and plasticity in wounds in vivo are not clear. Our group and others have found increased Th17 activation in diabetic wounds results in increased IL17a and pathologic inflammation that prevents tissue repair. Plasmacytoid dendritic cells (pDC) are antigen presenting cells (APCs) that are present in early diabetic wound tissue and may play a key role in modulating CD4+T cell phenotype. Hence, we hypothesized that pDCs in diabetic wounds may activate CD4+ T-cells towards a Th17 phenotype.
Methods: Wild type C57BL/6 mice were fed normal chow diet (13.5% kcal fat) or high fat diet chow (60% kcal fat) for 12-14 weeks to generate the diet-induced obesity (DIO) model of glucose intolerance/insulin resistance. These mice were subsequently wounded with 6 mm punch biopsies, and wound pDCs were examined by flow cytometry daily for 5 days. In another cohort of mice, wounds were created and pDCs were harvested on day 1. These cells were co-cultured with wild type, naïve CD4+ T-cells for 5 days, after which T-cell phenotype was determined by flow cytometry for established transcription factors and extracellular markers.
Results: Following exposure to DIO pDCs, wild type activated CD4+ T-cells were polarized towards a Th17 phenotype, demonstrating increased I17a production. Further, DIO pDC recruited to wounds resulted in decreased Th2/IL-4 producing T-cells, that are important for normal wound repair. Further, there were kinetic differences seen in pDC recruitment to DIO versus control wounds following injury.
Conclusion: Diabetic pDCs play an important role in wound Th17 CD4+ T-cell activation and may act to increase inflammation in diabetic wounds.