Main Sarah, Handy Rachel, Wilton Jane, Smith Stephen, Williams Liz, Fou Leila Du, Andrews John, Conroy Louise A, May Richard, Anderson Ian, Vaughan Tristan J
Cambridge Antibody Technology, Granta Park CB1 6GH, UK.
J Pharmacol Exp Ther. 2006 Dec;319(3):1395-404. doi: 10.1124/jpet.106.110734. Epub 2006 Sep 14.
The CC chemokine, eotaxin1 (CCL11) is an important regulator of eosinophil function. A marked accumulation of eosinophils in tissues has been correlated with the up-regulation of eotaxin1 expression in several diseases. The potential therapeutic value of neutralizing the effects of eotaxin1 in inflammatory conditions (including asthma) is under investigation. A human single-chain fragment variable antibody that neutralizes human eotaxin1 (CAT-212) was produced using antibody phage display and converted to whole antibody IgG4 format (CAT-213). A novel approach to lead optimization in which the length of the variable heavy chain complementarity-determining region 3 was reduced by one amino acid resulted in an increase in potency of >1000-fold compared with the parent anti-eotaxin1 antibody. The optimized antibody binds eotaxin1 with high affinity (80.4 pM) and specificity. CAT-213 and CAT-212 do not bind or neutralize a range of other human proteins including human monocyte chemoattractant protein-1, a structurally similar chemokine. CAT-213 neutralizes the ability of eotaxin1 to cause an increase in intracellular calcium signaling (with an IC(50) value of 2.86 nM), migration of CCR3-expressing L1.2 cells (with an IC(50) value of 0.48 nM), and inhibition of the eotaxin1-evoked shape change of human eosinophils in vitro (with an IC(50) of 0.71 nM). Local administration of CAT-213 to mice (1-100 microg kg(-1)) attenuates dermal eosinophilia induced by human eotaxin1, achieving >90% inhibition of eosinophil influx. CAT-213 may therefore be of therapeutic value in inhibiting diseases in which eotaxin1 and eosinophils play a major role, for example, severe asthma.
C-C趋化因子嗜酸性粒细胞趋化因子1（CCL11）是嗜酸性粒细胞功能的重要调节因子。在几种疾病中，组织中嗜酸性粒细胞的显著积聚与嗜酸性粒细胞趋化因子1表达上调相关。中和嗜酸性粒细胞趋化因子1在炎症性疾病（包括哮喘）中的作用的潜在治疗价值正在研究中。使用抗体噬菌体展示技术制备了一种中和人嗜酸性粒细胞趋化因子1的人单链可变片段抗体（CAT-212），并将其转化为完整抗体IgG4形式（CAT-213）。一种新的先导优化方法，即将重链可变区互补决定区3的长度减少一个氨基酸，与亲本抗嗜酸性粒细胞趋化因子1抗体相比，其效力增加了1000倍以上。优化后的抗体以高亲和力（80.4 pM）和特异性结合嗜酸性粒细胞趋化因子1。CAT-213和CAT-212不结合或中和一系列其他人类蛋白质，包括人单核细胞趋化蛋白-1，一种结构相似的趋化因子。CAT-213中和嗜酸性粒细胞趋化因子1引起细胞内钙信号增加的能力（IC50值为2.86 nM）、表达CCR3的L1.2细胞的迁移能力（IC50值为0.48 nM）以及体外抑制嗜酸性粒细胞趋化因子1诱发的人嗜酸性粒细胞形态变化的能力（IC50为0.71 nM）。将CAT-213局部给予小鼠（1 - 100 μg kg-1）可减轻人嗜酸性粒细胞趋化因子1诱导的皮肤嗜酸性粒细胞增多，实现对嗜酸性粒细胞流入的>90%抑制。因此，CAT-213在抑制嗜酸性粒细胞趋化因子1和嗜酸性粒细胞起主要作用的疾病（如重度哮喘）中可能具有治疗价值。
