The Influence Of RAGE-Macrophages On Diabetic Wound Healing

OBJECTIVEOn the basis of clarifying the influence of AGEs-RAGE on inflammation/repair balance during diabetic wound healing,the changes of macrophage infiltration and functional status in diabetic wound healing process were observed.Thus to reveal the relationship of AGEs-RAGE——macrophages——abnormal inflammatory response and delayed tissue repair on diabetic wound healing which may help to find a therapeutic target for improving diabetic wound healing.METHODS1.Effect of AGEs-RAGE on inflammatory response during diabetic wound healing.Diabetic C57BL/6J mice were induced by intraperitoneal multiple injection of streptozotocin with low dose manner.After blocking RAGE by anti-RAGE antibody applied topically on the full-thickness skin wounds,we compared the wound healing rate,neutrophils infiltration and inflammatory factor secretion of diabetic and normal wounds.2.Changes of macrophage infiltration and functional status during diabetic wound healing.We observed macrophages infiltration,neutrophils phagocytized by macrophages and macrophages polarization during diabetic wound healing.3.Influence of AGEs-RAGE on macrophage functional status.In vitro,after blocking RAGE by transfection of siRNA,we explored phagocytosis,polarization and cytokines secretion of macrophages.In vivo,blockade of RAGE was realized by anti-RAGE antibody applied topically on diabetic full-thickness skin wounds.Then we detected macrophages infiltration,neutrophils phagocytized by macrophages and macrophages polarization during diabetic wound healing.RESULTS1.Compared to normal wounds,diabetic wounds was characterized as AGEs accumulation in wound tissue.Neutrophils infiltration was sustained on 3 days after wound and the secretion of proinflammatory factors(TNF-?,IL-1?,IL-6)are insufficient on 1 day after wound while resolved sluggishly on 3 days after wound on diabetic wounds,which had a tight relationship with AGEs-RAGE.2.Compared to normal wounds,neutrophils phagocytized by macrophages were lacked on 3 days after wound and the number of M1 was increased while M2 decreased on 7 days after wound on diabetic wound.3.In vitro,AGEs-RAGE impaired phagocytosis of M0 and M1,inhibited the polarization to M2,improved proinflammatory factors secretion of M1 and inhibited growth factors secretion of M2.In vivo,blockade of RAGE improved macrophages infiltration in the early inflammatory stage and increased neutrophils phagocytized by macrophages on 3 days after wound in diabetic mice.What's more,the number of M1 was decresed while M2 increased on 7 days after wound.CONCLUSIONSAGEs that accumulated in the diabetic wound participated in the inflammation/repair imbalance through RAGE pathway during wound healing.Macrophage functional status were damaged by AGEs-RAGE.An essential inflammtional response helped to impove diabetic wound healing.Compared to the repair stage during which macrophages had a much more complex functional status,inflammatory phase is a relatively more ideal target to improve diabetic wound healing based on regulation of macrophage functions.