Ikezaki H, Paul S, Alkan-Onyüksel H, Patel M, Gao X P, Rubinstein I
Department of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612, USA.
Am J Physiol. 1998 Jul;275(1):R56-62. doi: 10.1152/ajpregu.1998.275.1.R56.
The purpose of this study was to determine whether a monoclonal anti-vasoactive intestinal peptide (VIP) antibody, which binds VIP with high affinity and specificity and catalyzes cleavage of the peptide in vitro, attenuates VIP vasorelaxation in vivo and, if so, whether insertion of VIP on the surface of sterically stabilized liposomes (SSL), which protects the peptide from trypsin- and plasma-catalyzed cleavage in vitro, curtails this response. Using intravital microscopy, we found that suffusion of monoclonal anti-VIP antibody (clone c23.5, IgG2ak), but not of nonimmune antibody (myeloma cell line UPC10, IgG2ak) or empty SSL, significantly attenuates VIP-induced vasodilation in the in situ hamster cheek pouch (P < 0.05). By contrast, anti-VIP antibody has no significant effects on vasodilation elicited by isoproterenol, nitroglycerin, and calcium ionophore A-23187, agonists that activate intracellular effector systems in blood vessels that mediate, in part, VIP vasoreactivity. Suffusion of VIP on SSL, but not of empty SSL, restores the vasorelaxant effects of VIP in the presence of anti-VIP antibody. Collectively, these data suggest that VIP catalysis by high affinity and specific VIP autoantibodies displaying protease-like activity constitutes a novel mechanism whereby VIP vasoreactivity is regulated in vivo.
本研究的目的是确定一种单克隆抗血管活性肠肽（VIP）抗体，其能以高亲和力和特异性结合VIP并在体外催化该肽的裂解，是否会在体内减弱VIP介导的血管舒张作用；如果是，那么将VIP插入空间稳定脂质体（SSL）表面，这种在体外可保护该肽免受胰蛋白酶和血浆催化裂解的方式，是否会抑制这种反应。通过活体显微镜观察，我们发现灌注单克隆抗VIP抗体（克隆c23.5，IgG2ak），而非非免疫抗体（骨髓瘤细胞系UPC10，IgG2ak）或空的SSL，能显著减弱原位仓鼠颊囊内VIP诱导的血管舒张（P<0.05）。相比之下，抗VIP抗体对异丙肾上腺素、硝酸甘油和钙离子载体A-23187引发的血管舒张无显著影响，这些激动剂激活血管内的细胞内效应系统，部分介导VIP的血管反应性。在存在抗VIP抗体的情况下，将VIP灌注到SSL表面（而非空的SSL）可恢复VIP的血管舒张作用。总体而言，这些数据表明，具有蛋白酶样活性的高亲和力和特异性VIP自身抗体对VIP的催化作用构成了一种体内调节VIP血管反应性的新机制。
