Tetramethylpyrazine activated PPARγ in resuscitating the liver graft donated after cardiac death
Fu Zhen1, Fan Lin1, Ye Shao Jun1, Wang Yan Feng1, Zhou Li Hua1, Chen Yong1, Liang Wen Jing1, Ye Qi Fa1,2.
1Zhongnan Hospital of Wuhan University, Institute of Hepatobiliary Diseases of Wuhan University, Wuhan, People's Republic of China; 2The 3rd Xiangya Hospital of Central South University, Research Center of National Health Ministry on Transplantation Medicine Engineering and Technology, Changsha, People's Republic of China
Liver grafts from donation after cardiac death (DCD) are discarded for transplantation because of their poor tolerance to ischemia reperfusion injury (IRI). The aim of this study was to identify whether Tetramethylpyrazine (TMP) pretreatment can protect DCD grafts preserved during cold storage or/and HMP and transplanted. The protective mechanisms of TMP were also examined. A single dose of TMP (50mg/kg) or its vehicle was injected by dorsal vein of the penis in rats, 1h before DCD. DCD Livers were subjected to 30 min in situ warm schemia, without application of heparin, mimicking DCD organ procurement, followed by conventional organ transport. Grafts were then cold stored for 4h (control group) or treated after 3 h cold storage with 1h hypothermic machine perfusion (HMP) through the portal vein, and then transplanted, the liver grafts were reperfused for 6 h, the blood and tissue samples were obtained and kept until further analysis. TMP treatment up-regulated the expression of peroxisome proliferator activated receptor-γ (PPARγ) and nuclear transcription factor 2 (NRF2）in HMP group compared to SCS(n=4, p<0.05), PPARγ agonist Rosiglitazone (Ro) and antagonist GW9662 (GW) treatment, protein expression level of PPARγ, NRF2 reached the peak in TMP+Ro group, and up-regulated the level of inflammatory cytokines (TNF-a, IL-6) in serum to alleviate the inflammation reaction, and increased the KEAP1, NQO1 and HO-1 protein expression indicated that Not only PPARγ agonist activated the NRF2 signaling and then prevented oxidative damage, but mediated TLR4 signaling and TRIF domain-containing-adaptor inducing IFNβ (TRIF), but MyD88 expression no changed. When PPARγ was suppressed by GW, TMP did not reduce damage, it indicated that TMP activated the PPARγ and this in turn down-regulated the TLR-4/TRIF pathway to reduce immune response. In conclusion, TMP activated the PPARγ and NRF2, thus protecting DCD liver grafts. Pretreatment of DCD livers with TMP shortly before procurement of the liver graft strongly alleviated IRI after liver transplantation, may represent a new therapeutic administration for DCD.
the Fundamental Research Funds for the Central Universities (No 2042019kf0133).
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