POLYMERIC IMMUNOGLOBULIN RECEPTOR TARGETING OF AIRWAYS

描述（由申请人提供）：聚合免疫球蛋白受体（plgR）在气道上皮细胞和粘膜下腺的浆液细胞中表达。它的正常功能是与基底外侧表面的聚合免疫球蛋白结合，并将其转移到根尖表面（管腔），在那里它们被释放，仍然与受体的一部分（现在称为分泌成分，或SC）结合，作为分泌性免疫球蛋白。它特别适合于在上皮上转移大量货物，并且在气道中的细胞类型中表达，其中囊性纤维化跨膜传导调节因子也表达。因此，从治疗的角度来看，这种受体有两个候选目的：一是将基因从基底外侧入路传递到气道上皮，二是将治疗药物从血液输送到管腔。针对这种受体制备了抗体，并进行了二级筛选，要求它们也与分泌性免疫球蛋白反应（即在天然配体使用的位点以外的位点结合）。这些抗体分为两类。一类细胞经历快速胞吞作用。另一种被迅速吸收，但保留在细胞内的膜包围的核周囊泡中。这一建议是基于这样的假设，即“快速胞吞”抗体将产生优越的胞吞治疗载体，而“细胞保留”抗体将优越于基因转移，因为它们将使其货物在细胞中停留更长时间，允许逃逸和核进入。单链Fvs将由两类抗体的代表制备，并比较它们从压缩DNA的非病毒基因转移载体中增强基因转移的能力，以及它们作为融合蛋白，将潜在的治疗分子1-抗胰蛋白酶运输到气道管腔的能力。测试系统将是在培养中转染人类plgR的极化细胞系；人气道上皮细胞生长在气液界面，表达plgR；通过CC-10启动子驱动的人plgR转基因小鼠，使受体仅在气道上皮中表达。如果研究成功，囊性纤维化和其他气道疾病的新疗法可以从这个基础上开发出来。

DESCRIPTION (provided by applicant): The polymeric immunoglobulin receptor (plgR) is expressed in airway epithelial cells and in the serous cells of the submucosal glands. Its normal function is to bind to polymeric immunoglobulins on the basolateral surface and transfer them to the apical surface (the lumen) where they are released, still bound to a portion of the receptor (now called secretory component, or SC) as secretory immunoglobulins. It is specifically adapted to transfer large amounts of cargo across the epithelium, and it is expressed in the cell types in the airway in which the cystic fibrosis transmembrane conductance regulator is also expressed. Thus, from the therapeutic perspective, this receptor is a candidate for two purposes - one, to deliver genes to airway epithelium from the basolateral approach, and two, to ferry therapeutics across the airway from the blood to the lumen. Antibodies have been prepared against this receptor, and a secondary screen requiring them to react with secretory immunoglobulin as well (that is, to bind at a site other than that used by the natural ligand) was applied. These antibodies fall into two categories. One class undergoes rapid transcytosis. The other undergoes rapid uptake, but is retained within the cell in membrane-bounded perinuclear vesicles. This proposal is based on the hypothesis that the "rapid transcytosis" antibodies will produce superior transcytotic therapeutic carriers, whereas the "cell retention" antibodies will be superior for gene transfer, for they will keep their cargo in the cells longer, allowing for escape and nuclear entry. Single chain Fvs will be prepared from representatives of both classes of antibodies and compared for their ability to enhance gene transfer from nonviral gene transfer vectors of compacted DNA, and for their ability to transport, as a fusion protein, a potential therapeutic molecule, 1-antitrypsin, into the airway lumen. Test systems will be both polarized cell lines in culture transfected with the human plgR; human airway epithelial cells grown at the air-liquid interface, which express plgR; and mice transgenic for the human plgR driven by the CC-10 promoter, so that the receptor is expressed only in airway epithelium. If the studies are successful, new therapeutics for cystic fibrosis and other airway diseases can be developed from this base.