| Objective:As has been known, ionizing radiation can induce impaired immune function injury and immune imbalance. At present, however, the researches about the healing mechanism of the combined radiation-wound injury (CRW) were limited to the processes of wound healing. The effect of radiation-induced immunomodulation function damage on wound healing is still indefinite. Therefore, the changes of immune modulation function in CRW rats and its impact on wound healing will be investigated in this part, expecting to provide some data for the research on refractory mechanism of CRW and promoting wound healing therapy.Methods:In this part,66Wistar female rats (body weight200±20g), were divided into normal group, simple wound (SW) group, wound+5Gy total body y-irradiation (WTR) group and wound+25Gy local γ-irradiation (WLR) group. Two animal models of WTR and WLR were used.3d、7d、14d and28d after CRW, the peripheral white blood cells (WBC) and lymphocytes (LYM) were counted, and the percentages of the peripheral CD4+, CD8+T lymphocytes and splenic regulatory T cells (Tregs), Th17cells were analyzed by flow cytometry. Contents of IFN-y and IL-4in serum were estimated by ELISA assay.Results:(1) Wound healing in total body irradiation (WTR) and local irradiation (WLR) groups was significantly delayed, and the collagen contents in WTR and WLR groups were prominent lower compared with simple wound (SW) group.(2) The indexes of thymus and spleen in WTR and WLR groups were obviously lower than that in SW group.(3) The peripheral WBC and LYM counts in SW group were and lower than in normal group3d and7d after CRW. WBC and LYM counts in WTR and WLR groups were much lower than those in normal group and SW group3d to14d after CRW.(4) Percentages of CD4+and CD8+in WTR and WLR groups were much lower than that in normal group7d to28d after CRW. The CD4+/CD8+ratio in WTR and WLR groups were significantly higher than that in normal group and SW group,while the ratio in WLR group was lower than that in WTR group3d after CRW.(5) Percentages of splenic Tregs in WTR were significantly higher than those in normal group and SW group3d and7d after CRW, while Tregs in WLR increased significantly only3d after CRW. Percentages of splenic Th17in WTR and WLR groups increased obviously and their Treg/Th17ratio reduced evidently compared with normal and SW groups3d to7d after CRW.(6) Serum IFN-γ content in WTR and WLR groups obviously decreased compared with normal and SW groups3d to7d after CRW. There were no significant changes of serum IL-4in all treated groups at different times after CRW. However, IFN-y/IL-4ratio evidently reduced in WTR and WLR groups compared with normal and SW groups3d to7d after CRW, it means Th1/Th2balance drifted to the immune reaction of Th2.Conclusions:(1) Wound healing in WTR and WLR groups were significantly delayed and their poor healing were observed compared with normal group.(2)Simple skin wound did not cause immunomodu-latory function change.(3) After CRW, the percentages of CD4+, CD8+T lymphocyte subsets in WTR and WLR groups reduced evidently, while the CD4+/CD8+ratio increased significantly compared with normal group; the proportions of Tregs and Th17increased distinctively, Treg/Th17balance drifted to the immune reaction of Th17; Th1/Th2imbalance; while these changes were more evidently in WTR group, causing immune function disorders and homeostasis imbalance, which is an important immunological mechanism of delayed wound healing after CRW. Our previous study showed that recombinant plasmid carrying with human hepatocyte growth factor (pHGF) can promote CRW healing, however, the mechanism of promoting CRW healing by pHGF has not completely elucidated. Therefore, we want to explore the mechanism on promotion CRW healing by pHGF from view of immune in this part, expecting to provide further experimental evidence for pHGF clinical application studies.Methods:In this part,66Wistar female rats (body weight200±20g), were divided into four grups, that is, normal (Normal) group, wound+25Gy local y-irradiation+PBS (PBS) group, wound+25Gy local γ-irradiation+JYT (JYT) group and wound+25Gy local γ-irradiation+pHGF (pHGF) group.25Gy local irradiation combined rat skin wound model was used in this section.3d、7d、14d and28d after CRW, the peripheral white blood cells (WBC) and lymphocytes (LYM) were counted, and the percentages of peripheral CD4+and CD8+lymphocytes and splenic Tregs and Th17were analyzed by flow cytometry.Results:(1)The wound in pHGF group has been completely healed, while that in PBS group and JYT group has not yet fully healed28d after CRW.(2) Compared with the PBS and JYT groups, wound in pHGF group showed more exudation of inflammatory cells, abundant granulation tissue and angiogenesis and higher content of collagen fiber.(3)Numbers of peripheral WBC and LYM in pHGF group were significantly higher than those in PBS group7d and14d after CRW.(4) Compared with PBS group, the percentage of peripheral CD8+T lymphocytes significantly increased, causing CD4+/CD8+ratio reduced evidently in pHGF group3d after CRW.(5) The proportions of splenic Treg and Th17in pHGF group decreased than those in PBS goup3d and 7d after CRW, and the splenic Treg/Th17ratio increased significantly7d after CRW.Conclusions:(1) pHGF could obviously promote wound healing in rats with CRW, including accelerating growth of granulation tissue, fibroblast proliferation and capillary production of granulation tissue in wound region, and facilitating formation of horny layer of epidermis and reepithelization processes.(2) pHGF could improve CD8+T cells proportion in peripheral blood, and be beneficial to Treg/Th17balance restoring in rats with CRW. So that the immune function can be improved and the body homeostasis can be gradually reinstated, that may be an important immunological mechanism of promoting wound healing by pHGF.35charts,2tables,51references. |
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