Department of General Surgery, Second Affiliated Hospital of School of Medicine, Zhejiang University, Hangzhou City, China.
Department of Thyroid and Breast Surgery, Zhejiang University Jinhua Hospital, Zhejiang Province, Jinhua City, China.
Transplantation. 2020 Nov;104(11):2317-2326. doi: 10.1097/TP.0000000000003319.
Graft rejection continues to be a major barrier to long-term engraftment after transplantation. Autophagy plays an important role in cardiac injury pathogenesis. The bromodomain and extraterminal protein inhibitor (S)-tert-butyl2-(4-(4-chlorophenyl)-2,3,9-trimethyl-6H-thieno[3,2-f][1,2,4]triazolo[4,3-a][1,4]diazepin-6-yl)acetate (JQ1) inhibits inflammatory responses. However, the beneficial effect of JQ1 on transplant and the potential role of autophagy in the protective effect of graft survival are yet to be investigated.
Syngeneic or allogeneic heterotopic heart transplantation was performed using C57BL/6 or BALB/c donors for C57BL/6 recipients through different treatments. Some mice were used to observe the survival of the grafts. The other mice were euthanized on the third, fifth, and seventh days after surgery. The graft samples were taken for cytokines and autophagy pathway analyses.
Our study revealed that JQ1 treatment prolonged cardiac allograft survival. JQ1 increased the expression levels of liver kinase beta 1, autophagy-specific gene 5, and microtubule-associated protein light chain3-II (LC3-II) and potentiated the phosphorylation of AMP-activated protein kinase, unc-51-like kinase 1 (ULK1), and autophagy-specific gene 14 in allografts. A conditional autophagy-specific gene 5 deletion donor was utilized to abrogate the effect induced by JQ1. The combined use of JQ1 with bafilomycin A1 partially reversed the effect of JQ1, suggesting that autophagy is involved in the signaling pathway in graft survival. JQ1 downregulated the expression of inflammatory cytokines, such as interleukin-6, interleukin-1β, tumor necrosis factor-α, and interferon-γ, which was abrogated when autophagy was inhibited.
JQ1 prolonged cardiac allograft survival by potentiating myocardial autophagy through the liver kinase beta 1-AMP-activated protein kinase-ULK1 signaling pathway and inhibiting the subsequent release of inflammatory cytokines. This result might provide novel insights for extending transplant survival.
移植物排斥反应仍然是移植后长期植入的主要障碍。自噬在心脏损伤发病机制中起重要作用。溴结构域和末端外蛋白抑制剂（S）-叔丁基 2-（4-（4-氯苯基）-2,3,9-三甲基-6H-噻吩[3,2-f][1,2,4]三唑[4,3-a][1,4]二氮杂卓-6-基）乙酸酯（JQ1）抑制炎症反应。然而，JQ1 对移植的有益影响以及自噬在移植物存活的保护作用中的潜在作用仍有待研究。
使用 C57BL/6 或 BALB/c 供体通过不同的处理对 C57BL/6 受体进行同基因或同种异体异位心脏移植。一些小鼠用于观察移植物的存活情况。另一些小鼠在手术后第 3、5 和 7 天被安乐死。取移植物样本进行细胞因子和自噬途径分析。
我们的研究表明，JQ1 治疗可延长心脏同种异体移植物的存活时间。JQ1 增加了肝激酶β 1、自噬特异性基因 5 和微管相关蛋白轻链 3-II（LC3-II）的表达水平，并增强了 AMP 激活的蛋白激酶、UNC-51 样激酶 1（ULK1）和自噬特异性基因 14 的磷酸化在同种异体移植物中。利用条件性自噬特异性基因 5 缺失供体消除了 JQ1 诱导的作用。JQ1 与巴弗洛霉素 A1 联合使用部分逆转了 JQ1 的作用，表明自噬参与了移植物存活的信号通路。JQ1 下调了白细胞介素 6、白细胞介素 1β、肿瘤坏死因子-α和干扰素-γ等炎症细胞因子的表达，当自噬受到抑制时，这种作用被消除。
JQ1 通过肝激酶β 1-AMP 激活的蛋白激酶-ULK1 信号通路增强心肌自噬，并抑制随后炎症细胞因子的释放，从而延长心脏同种异体移植物的存活时间。这一结果可能为延长移植的存活时间提供新的见解。
