Circulating heparin oligosaccharides rapidly target the hippocampus in sepsis, potentially impacting cognitive functions
Circulating heparin oligosaccharides rapidly target the hippocampus in sepsis, potentially impacting cognitive functions
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DOI：
10.1073/pnas.1902227116
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发表时间：
2019-05-07
影响因子：
11.1
通讯作者：
Linhardt, Robert J.
中科院分区：
文献类型：
--
作者：
Zhang, Xing;Han, Xiaorui;Linhardt, Robert J.
脓毒症诱导乙酰肝素酶介导的内皮糖萼（一种对血管稳态至关重要的富含硫酸乙酰肝素的血管内层）降解，将硫酸乙酰肝素的高度硫酸化结构域释放到循环中。这些结构域是富含肝素样三硫酸化二糖重复单元的寡糖。使用化学酶促方法，在对硝基苯基葡萄糖醛酸苷受体上合成含有均匀C-13标记的内部2-磺基艾杜糖醛酸残基的十一糖。选择性高碘酸盐裂解得到具有天然结构的肝素九糖。将这种C-13标记的九糖静脉内给予脓毒症（由盲肠结扎和穿刺诱导，多微生物腹膜炎诱导的脓毒症模型）和非脓毒症（假手术）小鼠。在4小时内的不同时间点收获来自小鼠的选定组织和生物流体，回收C-13标记的九糖并用肝素裂解酶消化。所得的C-13-标记的三硫酸化二糖进行定量，没有来自内源性小鼠硫酸乙酰肝素/肝素的干扰，使用液相色谱-质谱法与灵敏和选择性的多反应监测。C-13标记的肝素九糖立即出现在血液中，并迅速通过尿液清除。脓毒症小鼠的血浆九糖清除率仅略微延长（t（1/2）与90分钟相似）。在脓毒症小鼠中，九糖渗透到海马，但不是大脑皮质;在假手术小鼠中没有海马或皮质脑渗透发生。这项研究的结果表明，循环硫酸乙酰肝素在脓毒症期间从血浆中迅速清除，并选择性地穿透海马，在那里它们可能具有功能性后果。
Sepsis induces heparanase-mediated degradation of the endothelial glycocalyx, a heparan sulfate-enriched endovascular layer critical to vascular homeostasis, releasing highly sulfated domains of heparan sulfate into the circulation. These domains are oligosaccharides rich in heparin-like trisulfated disaccharide repeating units. Using a chemoenzymatic approach, an undecasaccharide containing a uniformly C-13-labeled internal 2-sulfoiduronic acid residue was synthesized on a p-nitrophenylglucuronide acceptor. Selective periodate cleavage afforded a heparin nonasaccharide having a natural structure. This C-13-labeled nonasaccharide was intravenously administered to septic (induced by cecal ligation and puncture, a model of polymicrobial peritonitis-induced sepsis) and nonseptic (sham) mice. Selected tissues and biological fluids from the mice were harvested at various time points over 4 hours, and the C-13-labeled nonasaccharide was recovered and digested with heparin lyases. The resulting C-13-labeled trisulfated disaccharide was quantified, without interference from endogenous mouse heparan sulfate/heparin, using liquid chromatography-mass spectrometry with sensitive and selective multiple reaction monitoring. The C-13-labeled heparin nonasaccharide appeared immediately in the blood and was rapidly cleared through the urine. Plasma nonasaccharide clearance was only slightly prolonged in septic mice (t(1/2) similar to 90 minutes). In septic mice, the nonasaccharide penetrated into the hippocampus but not the cortex of the brain; no hippocampal or cortical brain penetration occurred in sham mice. The results of this study suggest that circulating heparan sulfates are rapidly cleared from the plasma during sepsis and selectively penetrate the hippocampus, where they may have functional consequences.