白细胞介素22体内外预处理脂肪供肝/老年供肝后可提高肝移植手术存活率并拮抗肝损伤

Liver transplantation (LT) is currently the only curative therapy for chronic end-stage liver disease. However, a critical shortage of organs available for transplant is the limitation for the development of LT. In vitro IL-6 treatment induces hepatoprotection of steatotic liver isografts, but the non-specific effects of IL-6 on almost all cell types limits the clinical usage. Thus, it's necessary to find a more specific and safe method to replace IL-6. Strategies to minimize steatosis/aging and expand the number of donors are critical to meet the growing demand for LT. Our previous work and literature show that IL-22 has a hepatoprotection on ischemia reperfusion injury by selectively targeting hepatocytes. We hypothesize in vitro interleukin-22 treatment prevents mortality associated with fatty/aging liver transplants in rats, in vivo IL-22 therapeutic during perioperative period of LT has a protective effect on liver injury. Therefore, the aim of this project is to characterize whether in vitro adding IL-22 directly to the University of Wisconsin (UW) solution, and in vivo therapeutic IL-22 treatment can prevent the mortality associated with fatty/aging liver transplants in rats and protect liver against injury. We also plan to compare the pharmacodynamics difference between regular recombinant human interleukin 22 (rh-IL-22) and interleukin 22 fusion protein(IL-22-FP) with bigger molecular weight, longer half-life (approximately 24 hours). Moreover, the correlation of IL-22 expression and the outcome of LT will be investigated in clinial serum and liver biopsies. Taken together, the performing of current project will be important to accepte more steatotic/aging liver isografts for transplantation. This project also may provide some evidence to developing a new safe IL-22 therapeutic strategy in surgical LT.

肝移植（LT）是治疗终末期肝病的最有效方法，供肝短缺是影响LT发展的瓶颈。体外IL-6预处理能提高脂肪供肝的存活率，但IL-6作用的非特异性限制了使用。我们前期结果和文献报道IL-22具有很好的肝细胞靶向性，并可保护肝缺血再灌注损伤。我们推测IL-22体外预处理脂肪供肝/老年供肝后可提高肝移植手术存活率，围手术期体内给予IL-22治疗亦可发挥肝脏保护作用。本课题拟考察器官保存液中体外直接加用IL-22对脂肪供肝/老年供肝进行预处理，体内围手术期给予IL-22治疗，是否具有提高LT的成功率及抗肝损伤能力；并比较常规重组IL-22(rh-IL-22)和作用时间更长分子量更大的白介素22融合蛋白(IL-22-FP)之间的药效学差异；最后临床验证LT病人血清和肝脏局部IL-22表达与LT手术预后的关系。本课题的实施将为临床应用扩大供肝选择范围，为IL-22用于LT手术治疗提供有益的实验尝试。

先前的研究表明，骨形态发生蛋白9 (bone morphogenetic protein 9, BMP9)几乎只在肝脏中产生，并作为分泌蛋白到达全身组织。然而，BMP9的作用机制及其在衰老相关肝损伤和炎症中的作用尚不清楚。我们发现衰老显著加重对乙酰氨基酚(APAP)诱导的急性肝损伤(ALI)。CCAAT/增强子结合蛋白α (C/EBPα)和BMP9在老年肝脏和从老年小鼠分离的肝细胞和巨噬细胞(MФs)中表达增加。进一步的分析表明，过量的BMP9与APAP诱导的肝细胞损伤和死亡直接相关，这可以从激活的SMAD1/5/9信号、死亡细胞比例增加、抑制ATG3和ATG7活性、阻滞自噬、衰老相关β-半乳糖苷酶(SA-β-Gal)活性增加以及衰老相关分泌表型(SASP)增加得到证明。相比之下，Bmp9敲除(Bmp9-/-)部分缓解了上述Bmp9过表达的表现。C/EBPα在体内外均可调控BMP9的表达。值得注意的是，BMP9在MΦs中也通过其对自噬相关基因(ATG3和ATG7)的作用下调了自噬，这与肝损伤加重和SASP获得有关。总之，本研究强调了C/EBPα-BMP9串扰在急性肝损伤中发挥的关键作用，并为肝细胞与MΦs之间的相互关系提供了见解。