Cone Richard A, Hoen Timothy, Wong Xixi, Abusuwwa Raed, Anderson Deborah J, Moench Thomas R
Mucosal Protection Laboratory, Dept. of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA.
BMC Infect Dis. 2006 Jun 1;6:90. doi: 10.1186/1471-2334-6-90.
Microbicides must protect against STD pathogens without causing unacceptable toxic effects. Microbicides based on nonoxynol-9 (N9) and other detergents disrupt sperm, HSV and HIV membranes, and these agents are effective contraceptives. But paradoxically N9 fails to protect women against HIV and other STD pathogens, most likely because it causes toxic effects that increase susceptibility. The mouse HSV-2 vaginal transmission model reported here: (a) Directly tests for toxic effects that increase susceptibility to HSV-2, (b) Determines in vivo whether a microbicide can protect against HSV-2 transmission without causing toxicities that increase susceptibility, and (c) Identifies those toxic effects that best correlate with the increased HSV susceptibility.
Susceptibility was evaluated in progestin-treated mice by delivering a low-dose viral inoculum (0.1 ID50) at various times after delivering the candidate microbicide to detect whether the candidate increased the fraction of mice infected. Ten agents were tested - five detergents: nonionic (N9), cationic (benzalkonium chloride, BZK), anionic (sodium dodecylsulfate, SDS), the pair of detergents in C31G (C14AO and C16B); one surface active agent (chlorhexidine); two non-detergents (BufferGel, and sulfonated polystyrene, SPS); and HEC placebo gel (hydroxyethylcellulose). Toxic effects were evaluated by histology, uptake of a 'dead cell' dye, colposcopy, enumeration of vaginal macrophages, and measurement of inflammatory cytokines.
A single dose of N9 protected against HSV-2 for a few minutes but then rapidly increased susceptibility, which reached maximum at 12 hours. When applied at the minimal concentration needed for brief partial protection, all five detergents caused a subsequent increase in susceptibility at 12 hours of approximately 20-30-fold. Surprisingly, colposcopy failed to detect visible signs of the N9 toxic effect that increased susceptibility at 12 hours. Toxic effects that occurred contemporaneously with increased susceptibility were rapid exfoliation and re-growth of epithelial cell layers, entry of macrophages into the vaginal lumen, and release of one or more inflammatory cytokines (Il-1beta, KC, MIP 1alpha, RANTES). The non-detergent microbicides and HEC placebo caused no significant increase in susceptibility or toxic effects.
This mouse HSV-2 model provides a sensitive method to detect microbicide-induced toxicities that increase susceptibility to infection. In this model, there was no concentration at which detergents provided protection without significantly increasing susceptibility.
杀微生物剂必须能预防性传播疾病病原体，同时又不产生不可接受的毒性作用。基于壬苯醇醚 - 9（N9）和其他去污剂的杀微生物剂会破坏精子、单纯疱疹病毒（HSV）和人类免疫缺陷病毒（HIV）的膜，并且这些制剂是有效的避孕药。但矛盾的是，N9未能保护女性免受HIV和其他性传播疾病病原体的侵害，很可能是因为它会产生增加易感性的毒性作用。本文报道的小鼠HSV - 2阴道传播模型：（a）直接检测增加对HSV - 2易感性的毒性作用；（b）在体内确定一种杀微生物剂能否预防HSV - 2传播，同时又不产生增加易感性的毒性；（c）确定那些与HSV易感性增加最相关的毒性作用。
通过在给候选杀微生物剂后不同时间给予低剂量病毒接种物（0.1半数感染剂量，ID50），在孕激素处理的小鼠中评估易感性，以检测候选物是否增加感染小鼠的比例。测试了十种制剂——五种去污剂：非离子型（N9）、阳离子型（苯扎氯铵，BZK）、阴离子型（十二烷基硫酸钠，SDS）、C31G中的一对去污剂（C14AO和C16B）；一种表面活性剂（洗必泰）；两种非去污剂（缓冲凝胶和磺化聚苯乙烯，SPS）；以及羟乙基纤维素（HEC）安慰剂凝胶。通过组织学、“死细胞”染料摄取、阴道镜检查、阴道巨噬细胞计数和炎性细胞因子测量来评估毒性作用。
单剂量的N9能在几分钟内预防HSV - 2，但随后迅速增加易感性，在12小时时达到最大值。当以短暂部分保护所需的最低浓度应用时，所有五种去污剂在12小时时都会导致易感性随后增加约20 - 30倍。令人惊讶的是，阴道镜检查未能检测到在12小时时增加易感性的N9毒性作用的明显迹象。与易感性增加同时发生的毒性作用是上皮细胞层的快速脱落和重新生长、巨噬细胞进入阴道腔以及一种或多种炎性细胞因子（白细胞介素 - 1β、KC、巨噬细胞炎性蛋白1α、调节激活正常T细胞表达和分泌因子）的释放。非去污剂杀微生物剂和HEC安慰剂未导致易感性或毒性作用显著增加。
这种小鼠HSV - 2模型提供了一种灵敏的方法来检测杀微生物剂诱导的增加感染易感性的毒性。在这个模型中，不存在去污剂在不显著增加易感性的情况下提供保护的浓度。
