USC Division of Gastrointestinal and Liver Disease and the USC Research Center for Liver Disease, Keck Medicine of USC, Los Angeles, CA.
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX.
Hepatology. 2020 Nov;72(5):1771-1785. doi: 10.1002/hep.31179. Epub 2020 Oct 22.
This study examined whether enhanced susceptibility of steatotic liver to ischemia-reperfusion (I/R) injury is due to impaired recruitment of bone marrow (BM) progenitors of liver sinusoidal endothelial cells (LSECs, also called sinusoidal endothelial cell progenitor cells [sprocs]) with diminished repair of injured LSECs and whether restoring signaling to recruit BM sprocs reduces I/R injury.
Hepatic vessels were clamped for 1 hour in rats fed a high-fat, high-fructose (HFHF) diet for 5, 10, or 15 weeks. Matrix metalloproteinase 9 (MMP-9) antisense oligonucleotides (ASO) or an MMP inhibitor were used to induce liver-selective MMP-9 inhibition. HFHF rats had mild, moderate, and severe steatosis, respectively, at 5, 10, and 15 weeks. I/R injury was enhanced in HFHF rats; this was accompanied by complete absence of hepatic vascular endothelial growth factor (VEGF)-stromal cell-derived factor 1 (sdf1) signaling, leading to lack of BM sproc recruitment. Liver-selective MMP-9 inhibition to protect against proteolytic cleavage of hepatic VEGF using either MMP-9 ASO or intraportal MMP inhibitor in 5-week and 10-week HFHF rats enhanced hepatic VEGF-sdf1 signaling, increased BM sproc recruitment, and reduced alanine aminotransferase (ALT) by 92% and 77% at 5 weeks and by 80% and 64% at 10 weeks of the HFHF diet, respectively. After I/R injury in 15-week HFHF rats, the MMP inhibitor reduced active MMP-9 expression by 97%, ameliorated histologic evidence of injury, and reduced ALT by 58%, which is comparable to control rats sustaining I/R injury. Rescue therapy with intraportal MMP inhibitor, given after ischemia, in the 5-week HFHF rat reduced ALT by 71% and reduced necrosis.
Lack of signaling to recruit BM sprocs that repair injured LSECs renders steatotic liver more susceptible to I/R injury. Liver-selective MMP-9 inhibition enhances VEGF-sdf1 signaling and recruitment of BM sprocs, which markedly protects against I/R injury, even in severely steatotic rats.
本研究旨在探讨脂肪肝对缺血再灌注（I/R）损伤的易感性增加是否是由于骨髓（BM）肝窦内皮细胞（LSEC，也称为窦内皮细胞前体细胞[sprocs]）祖细胞的募集受损，导致受损的 LSEC 修复减少，以及恢复招募 BM sprocs 的信号是否可以减轻 I/R 损伤。
在给予高脂肪、高果糖（HFHF）饮食 5、10 或 15 周的大鼠中，夹闭肝血管 1 小时。基质金属蛋白酶 9（MMP-9）反义寡核苷酸（ASO）或 MMP 抑制剂用于诱导肝脏选择性 MMP-9 抑制。HFHF 大鼠分别在第 5、10 和 15 周出现轻度、中度和重度脂肪肝。HFHF 大鼠的 I/R 损伤加重；这伴随着肝血管内皮生长因子（VEGF）-基质细胞衍生因子 1（sdf1）信号的完全缺失，导致 BM sproc 募集缺失。在 5 周和 10 周 HFHF 大鼠中，使用 MMP-9 ASO 或门静脉内 MMP 抑制剂进行肝脏选择性 MMP-9 抑制以防止肝脏 VEGF 的蛋白水解裂解，从而保护肝脏免受 MMP-9 抑制，增强了肝 VEGF-sdf1 信号，增加了 BM sproc 的募集，并使丙氨酸氨基转移酶（ALT）在 5 周时降低了 92%和 77%，在 10 周时降低了 80%和 64%HFHF 饮食。在 15 周 HFHF 大鼠的 I/R 损伤后，MMP 抑制剂使活性 MMP-9 表达降低了 97%，改善了损伤的组织学证据，并使 ALT 降低了 58%，与发生 I/R 损伤的对照大鼠相当。在 5 周 HFHF 大鼠中，缺血后门静脉内 MMP 抑制剂的挽救性治疗使 ALT 降低了 71%，并减少了坏死。
缺乏募集修复受损 LSEC 的 BM sprocs 的信号，使脂肪肝对 I/R 损伤更敏感。肝脏选择性 MMP-9 抑制增强了 VEGF-sdf1 信号和 BM sprocs 的募集，即使在严重脂肪肝大鼠中，也能显著保护免受 I/R 损伤。
