Division of Gastroenterology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
J Immunol. 2010 Apr 1;184(7):3648-55. doi: 10.4049/jimmunol.0903346. Epub 2010 Mar 5.
Monostratified epithelial cells translocate HIV type 1 (HIV-1) from the apical to the basolateral surface via vesicular transcytosis. Because acutely transmitted HIV-1 is almost exclusively CCR5-tropic and human intestinal epithelial cells preferentially transcytose CCR5-tropic virus, we established epithelial monolayers using polarized HT-29 cells transduced to express CCR5, and an explant system using normal human rectal mucosa, to characterize biological parameters of epithelial cell transcytosis of HIV-1 and assess antiviral Ab blockade of transcytosis. The amount of cell-free HIV-1 transcytosed through the epithelial monolayer increased linearly in relation to the amount of virus applied to the apical surface, indicating transcytosis efficiency was constant (r(2) = 0.9846; p < 0.0001). The efficiency of HIV-1 transcytosis ranged between 0.05 and 1.21%, depending on the virus strain, producer cell type and gp120 V1-V3 loop signature. Inoculation of HIV-1 neutralizing Abs to the immunodominant region (7B2) or the conserved membrane proximal external region (2F5) of gp41 or to cardiolipin (IS4) onto the apical surface of epithelial monolayers prior to inoculation of virus significantly reduced HIV-1 transcytosis. 2F5 was the most potent of these IgG1 Abs. Dimeric IgA and monomeric IgA, but not polymeric IgM, 2F5 Abs also blocked HIV-1 transcytosis across the epithelium and, importantly, across explanted normal human rectal mucosa, with monomeric IgA substantially more potent than dimeric IgA in effecting transcytosis blockade. These findings underscore the potential role of transcytosis blockade in the prevention of HIV-1 transmission across columnar epithelium such as that of the rectum.
单柱状上皮细胞通过囊泡转胞运输将 HIV 1 型（HIV-1）从顶端转运到基底外侧表面。由于急性传播的 HIV-1 几乎完全是 CCR5 嗜性的，而人类肠道上皮细胞优先转导 CCR5 嗜性病毒，我们建立了使用极化 HT-29 细胞转导表达 CCR5 的上皮单层，以及使用正常人类直肠黏膜的外植体系统，以表征 HIV-1 上皮细胞转胞运输的生物学参数，并评估抗病毒 Ab 对转胞运输的阻断作用。穿过上皮单层的细胞游离 HIV-1 转胞数量与施加到顶端表面的病毒量呈线性增加，表明转胞效率是恒定的（r²=0.9846；p<0.0001）。HIV-1 转胞效率的范围取决于病毒株、生产细胞类型和 gp120 V1-V3 环特征，在 0.05%到 1.21%之间。在接种病毒之前，将针对 gp41 的免疫显性区（7B2）或保守的膜近端外区（2F5）或针对心磷脂（IS4）的 HIV-1 中和 Ab 接种到上皮单层的顶端表面，显著降低了 HIV-1 的转胞作用。在这些 IgG1 Ab 中，2F5 是最有效的。二聚体 IgA 和单体 IgA，但不是多聚体 IgM，2F5 Ab 也可阻断 HIV-1 穿过上皮和重要的是穿过外植的正常人类直肠黏膜的转胞作用，单体 IgA 在阻断转胞作用方面的效力明显大于二聚体 IgA。这些发现强调了转胞运输阻断在预防 HIV-1 穿过柱状上皮（如直肠）传播中的潜在作用。
