Comparative Analysis of Novel Complement-Targeted Inhibitors, MiniFH, and the Natural Regulators Factor H and Factor H-like Protein 1 Reveal Functional Determinants of Complement Regulation.
Comparative Analysis of Novel Complement-Targeted Inhibitors, MiniFH, and the Natural Regulators Factor H and Factor H-like Protein 1 Reveal Functional Determinants of Complement Regulation.
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DOI：
10.4049/jimmunol.1501919
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发表时间：
2016-01-15
期刊：
影响因子：
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通讯作者：
Schmidt CQ
中科院分区：
文献类型：
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作者：
Harder MJ;Anliker M;Höchsmann B;Simmet T;Huber-Lang M;Schrezenmeier H;Ricklin D;Lambris JD;Barlow PN;Schmidt CQ
由20个补体控制蛋白模块（CCP）组成的血清蛋白H因子（FH）及其剪接产物H因子样蛋白1（FHL-1;由CCP 1-7组成）是补体激活的旁路途径（AP）的主要调节剂。FH的工程化版本miniFH仅包含通过优化肽连接的FH的N-和C-末端部分，并且显示出约10倍的离体效力。我们探索了这样的假设，即通过暴露C-末端CCP（19-20）中的配体结合位点（其在全长天然FH中是隐蔽的）来增强调节效力。因此，我们产生了缺乏中心结构域10-15的FH变体（FHΔ10-15）。为了探索亲合力如何影响监管强度，我们生成了miniFH的复制版本，称为midiFH。我们比较了FHΔ10-15和midiFH与miniFH、FH和FHL-1的活性。相对于FH，FHΔ10-15表现出对C3活化产物的改变的结合特征和对PNH患者红细胞的5倍增强的补体调节。与教条相反，FHL-1和FH表现出相同的调节活性，表明FHL-1在AP调节中的作用被低估了。出乎意料的是，如在midiFH中所见，对补体调理素的亲合力显著增加，并没有增强对宿主细胞的抑制潜力。总之，工程化和天然的基于FH的调节剂的比较已经确定了确定宿主细胞上的高AP调节活性的特征。FH CCP 19-20的不受限制的可用性和N-和C-末端FH区域之间的最佳空间取向是关键。
The serum proteins Factor H (FH), consisting of 20 complement control protein modules (CCPs), and its splice product Factor H-like protein 1 (FHL-1; consisting of CCPs 1–7) are major regulators of the alternative pathway (AP) of complement activation. The engineered version of FH, miniFH, contains only the N- and C-terminal portions of FH linked by an optimized peptide and shows ~10-fold higher ex vivo potency. We explored the hypothesis that regulatory potency is enhanced by unmasking of a ligand-binding site in the C-terminal CCPs (19–20) that is cryptic in full-length native FH. Therefore we produced a FH variant lacking the central domains 10–15 (FHΔ10–15). To explore how avidity affects regulatory strength, we generated a duplicated version of miniFH, termed midiFH. We compared activities of FHΔ10–15 and midiFH to miniFH, FH and FHL-1. Relative to FH, FHΔ10–15 exhibited an altered binding profile toward C3 activation products and a 5-fold-enhanced complement regulation on PNH patient’s erythrocytes. Contrary to dogma, FHL-1 and FH exhibited equal regulatory activity, suggesting that the role of FHL-1 in AP regulation has been underestimated. Unexpectedly, a substantially increased avidity for complement opsonins, as seen in midiFH, did not potentiate the inhibitory potential on host cells. In conclusion, comparisons of engineered and native FH-based regulators have identified features that determine high AP regulatory activity on host cells. Unrestricted availability of FH CCPs 19–20 and an optimal spatial orientation between the N- and C-terminal FH regions are key.