The Preliminary Study Of HMGB1 Participate In Heart Xenotransplantation Acute Vascular Rejection

Objective:To study the role of HMGB1 in heart xenotransplantation acute vascular rejection(AVR),through blocking the extracellular HMGB1 by EP.Methods:Heart transplantation model from mice to rat cervical is an animal model for the research of AVR.The heterotopic heart transplantation model was built through modified cuff method to establish, including SD rats were receptor and ICR mice were donors.The experiment was divided into two groups: the control group(n=5): rats were intraperitoneally injected with the same dose of normal saline every 6 hours after heart transplantation; ethyl pyruvate(EP) treatment group(n=5): HMGB1 antagonist EP(40mg/kg body weight) was intraperitoneally injected immediately every 6 hours after until the end of the experiment. When the cardiac allograft stop beating,time piont were regard as the end of the transplantation. The survival time of cardiac allograft were observed between two groups. The pathological change of cardiac allograft in each group was observed by hematoxylin and eosin(H&E) staining.The expression of interferon γ(IFN-γ)、interleukin 17A(IL-17A)in the serum of rat of each group were examined using Elisa method. Using The expression of HMGB1, receptor for advanced glycation end products(RAGE), Toll like receptor 4(TLR4), Interleukin 6(IL- 6),IL-17 A, IFN-γ were examined through PCR method.The infiltration of inflammatory cells were observed by immunohistochemical staining using Anti-Myeloperoxidase antibody, Anti-CD3 antibodies and Anti-Cytokeratin 20 antibodies.Results: 1. The mean survival time of cardiac allograft in control group is 38.80 ±13.16 h, while mean survival time is 91.20 ± 18.20 h in EP treated cardiac allograft. The survival time of EP treatment was significantly prolonged compared with the control group(P<0.05). 2. Xenografts in the control group developed a predominantly AVR at the endpoint, The main changes were characterized by massive interstitial hemorrhage,intravascular thrombosis and moderate infiltration of mononuclear cells. In contrast, micetreated with EP demonstrated significant attenuation of these pathological changes in xenografts at posttransplant Day2, although acute vascular and cellular rejection eventually developed at the endpoint. 3. IFN-γ of rat serum in the control group was64.89±23.81pg/ml at the end of transplant.The mean concentration of IFN-γ in EP treatment group was48.77±5.88pg/ml after the transplant of 48 h.It was significantly reduced compared with the contrast group(P<0.05).IL-17 A of rat serum in the control group was 5.62±1.14pg/ml at the end of transplant.IL-17 A of rat serum in the EP treatment group was 3.42±0.67pg/ml after the transplant of 48 h. It was significantly reduced compared with the contrast group(P<0.05). 4. Rats HMGB1,RAGE and TLR4 in the mice heart xenografts treated by EP at posttransplant 48 h were relatively lower than the expression in control group(P <0.01). Rats inflammatory cytokines IL-17 A, IFN-γ, IL-6 of the mice heart xenografts were reduced in EP treatment group compared with control group(P<0.01). 5. Infiltration of neutrophil(MPO+cells), T cells(CD3+cells), and B cells(CD20+cells) were inhibited in mice cardiac allograft treated with EP.Conclusion:1.The extracellular HMGB1 is an important initiation medium of AVR in a mouse-to-rat xenotransplantation model.2. Blocking HMGB1 prolonged survival time of cardiac xenograft through reduced infiltration of inflammatory cells, less expression of inflammatory cytokines.