IDENTIFICATION OF A NEW VASCULAR PERMEABILITY ENHANCING PEPTIDE FROM KININOGENS BY HUMAN NEUTROPHIL ELASTASE AND THE MECHANISM OF THE ACTIVITY.

中性粒细胞是主要的炎症细胞，参与各种炎症事件。嗜中性粒细胞依赖的血管通透性增强（VPE）就是其中之一，但其机制尚不清楚。因此，研究了由中性粒细胞弹性蛋白酶（NE）（一种由炎症刺激释放的溶酶体酶）诱导的VPE。NE从人血浆中产生VPE活性，尤其是氧化血浆，而从激肽原缺陷血浆中不产生VPE活性。NE从激肽原产生VPE活性，分离激肽原片段，检测VPE活性。只有一种肽SLMKRPPGFSPFRSSRI（E-kinin）具有VPE活性。E-激肽诱导的VPE活性与缓激肽（BK）相当，对BK B2受体拮抗剂敏感。E-kinin对大鼠子宫无收缩作用，但其desSSRI的活性只有BK的1/3，其羧基端序列与BK相同。两种肽均以BK B2受体依赖性方式降低大鼠血压。这些结果表明，E-激肽在体内转化为E-激肽desSSRI，并与受体相互作用。激肽酶II在羧基末端切割BK，但对E-激肽无效。为了检测E-激肽，在小鼠中使用与KLH结合的E-激肽的6或8个氨基端肽作为抗原产生单克隆抗体。四种抗体与E-激肽反应，但它们都与BK交叉反应。

Neutrophils are the major inflammatory cells and involved in various inflammatory events. The neutrophil-dependent vascular permeability enhancement (VPE) is one of them, however, the mechanism has not been known. The VPE induced by neutrophil elastase (NE), a lysosomal enzyme released by inflammatory stimuli, was, therefore, investigated. NE produced VPE activity from human plasma, especially oxidized plasma and no VPE activity was produced from kininogen-deficient plasma. NE generated VPE activity from kininogens and the kininogen fragments were separated, being examined for VPE activity. Only a peptide, SLMKRPPGFSPFRSSRI, named as E-kinin, showed a VPE activity. VPE activity induced by E-kinin was comparable to that of bradykinin (BK) and sensitive to a BK B2-receptor antagonist. No rat uterus constriction was induced by E-kinin but E-kinin desSSRI, which has the same carboxy-terminal sequence as BK, exhibited the activity of 1/3 of BK activity. Both peptides lowered rat blood pressure in a BK B2-receptor-dependent manner. These results indicated that E-kinin was converted to E-kinin desSSRI in vivo and interacted with the receptor. Kininase II cleaves BK at the carboxy-terminal but it was ineffective for E-kinin. To detect E-kinin, monoclonal antibodies were produced in mice using 6 or 8 amino-terminal peptide of E-kinin bound to KLH as antigens. Four antibodies reacted with E-kinin but all of them cross-reacted with BK.