P-selectin drives complement attack on endothelium during intravascular hemolysis in TLR-4/heme-dependent manner
P-selectin drives complement attack on endothelium during intravascular hemolysis in TLR-4/heme-dependent manner
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DOI：
10.1073/pnas.1814797116
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发表时间：
2019-03-26
影响因子：
11.1
通讯作者：
Roumenina, Lubka T.
中科院分区：
文献类型：
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作者：
Merle, Nicolas S.;Paule, Romain;Roumenina, Lubka T.
溶血性疾病通常与血管损伤后的多器官衰竭有关。阐明溶血事件导致器官损伤的机制可以为治疗提供思路。补体系统激活发生在溶血性疾病，如镰状细胞病，但病理相关性和溶血过程中补体激活表型的获得仍不清楚。在这里，我们发现，血管内溶血，诱导注射苯肼，导致丙氨酸氨基转移酶血浆水平和NGAL表达增加。这种肝损伤至少部分是补体依赖性的，因为它在补体C3（-/-）小鼠和注射C5阻断抗体中减弱。我们证明了C3激活片段沉积在血管内溶血或注射血红素的小鼠以及暴露于血红素的培养的人内皮细胞（EC）的肝内皮上。这一过程是由TLR 4信号传导介导的，如小鼠中的药理学阻断和TLR 4缺乏所揭示的。从机制上讲，TLR 4依赖性表面表达的P-选择素触发了一个非常规的补体激活机制，通过非共价锚定的C3激活片段，包括典型的液相C3（H2O），测量表面等离子体共振和流式细胞术。通过抗体阻断P-选择素阻止了溶血小鼠中的补体沉积并减弱了肝脏应激反应，通过NGAL表达来测量。总之，这些结果揭示了TLR 4/P-选择素/补体三联体在肝损伤中的关键影响及其与溶血性疾病的相关性。我们预期阻断TLR 4、P-选择素或补体系统可以预防溶血性疾病如镰状细胞病的肝损伤。
Hemolytic diseases are frequently linked to multiorgan failure subsequent to vascular damage. Deciphering the mechanisms leading to organ injury upon hemolytic event could bring out therapeutic approaches. Complement system activation occurs in hemolytic disorders, such as sickle cell disease, but the pathological relevance and the acquisition of a complement-activating phenotype during hemolysis remain unclear. Here we found that intravascular hemolysis, induced by injection of phenylhydrazine, resulted in increased alanine aminotransferase plasma levels and NGAL expression. This liver damage was at least in part complement-dependent, since it was attenuated in complement C3(-/-) mice and by injection of C5-blocking antibody. We evidenced C3 activation fragments' deposits on liver endothelium in mice with intravascular hemolysis or injected with heme as well as on cultured human endothelial cells (EC) exposed to heme. This process was mediated by TLR4 signaling, as revealed by pharmacological blockade and TLR4 deficiency in mice. Mechanistically, TLR4-dependent surface expression of P-selectin triggered an unconventional mechanism of complement activation by noncovalent anchoring of C3 activation fragments, including the typical fluid-phase C3(H2O), measured by surface plasmon resonance and flow cytometry. P-selectin blockade by an antibody prevented complement deposits and attenuated the liver stress response, measured by NGAL expression, in the hemolytic mice. In conclusion, these results revealed the critical impact of the triad TLR4/P-selectin/complement in the liver damage and its relevance for hemolytic diseases. We anticipate that blockade of TLR4, P-selectin, or the complement system could prevent liver injury in hemolytic diseases like sickle cell disease.