Magee-Womens Research Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
PLoS One. 2010 Feb 19;5(2):e9310. doi: 10.1371/journal.pone.0009310.
Tenofovir gel has entered into clinical trials for use as a topical microbicide to prevent HIV-1 infection but has no published data regarding pre-clinical testing using in vitro and ex vivo models. To validate our findings with on-going clinical trial results, we evaluated topical tenofovir gel for safety and efficacy. We also modeled systemic application of tenofovir for efficacy.
Formulation assessment of tenofovir gel included osmolality, viscosity, in vitro release, and permeability testing. Safety was evaluated by measuring the effect on the viability of vaginal flora, PBMCs, epithelial cells, and ectocervical and colorectal explant tissues. For efficacy testing, PBMCs were cultured with tenofovir or vehicle control gels and HIV-1 representing subtypes A, B, and C. Additionally, polarized ectocervical and colorectal explant cultures were treated apically with either gel. Tenofovir was added basolaterally to simulate systemic application. All tissues were challenged with HIV-1 applied apically. Infection was assessed by measuring p24 by ELISA on collected supernatants and immunohistochemistry for ectocervical explants. Formulation testing showed the tenofovir and vehicle control gels were >10 times isosmolar. Permeability through ectocervical tissue was variable but in all cases the receptor compartment drug concentration reached levels that inhibit HIV-1 infection in vitro. The gels were non-toxic toward vaginal flora, PBMCs, or epithelial cells. A transient reduction in epithelial monolayer integrity and epithelial fracture for ectocervical and colorectal explants was noted and likely due to the hyperosmolar nature of the formulation. Tenofovir gel prevented HIV-1 infection of PBMCs regardless of HIV-1 subtype. Topical and systemic tenofovir were effective at preventing HIV-1 infection of explant cultures.
These studies provide a mechanism for pre-clinical prediction of safety and efficacy of formulated microbicides. Tenofovir was effective against HIV-1 infection in our algorithm. These data support the use of tenofovir for pre-exposure prophylaxis.
替诺福韦凝胶已进入临床试验，作为一种局部杀微生物剂用于预防 HIV-1 感染，但尚无使用体外和离体模型进行临床前测试的相关数据。为了验证我们与正在进行的临床试验结果的一致性，我们评估了替诺福韦凝胶的安全性和有效性。我们还建立了替诺福韦的全身应用模型来评估其疗效。
替诺福韦凝胶的配方评估包括渗透压、粘度、体外释放和渗透性测试。安全性通过测量对阴道菌群、PBMC、上皮细胞以及宫颈和结直肠外植体组织活力的影响来评估。为了进行疗效测试，将 PBMC 与替诺福韦或载体对照凝胶以及代表 A、B 和 C 亚型的 HIV-1 共培养。此外，还将极化的宫颈和结直肠外植体培养物用凝胶进行顶端处理。将替诺福韦添加到底部来模拟全身应用。所有组织均用顶端施加的 HIV-1 进行挑战。通过收集上清液的 ELISA 法测量 p24 以及对宫颈外植体的免疫组织化学来评估感染。配方测试表明，替诺福韦和载体对照凝胶的渗透压均超过 10 倍。穿过宫颈组织的渗透性是可变的，但在所有情况下，受体腔室中的药物浓度达到了抑制体外 HIV-1 感染的水平。凝胶对阴道菌群、PBMC 或上皮细胞无毒。宫颈和结直肠外植体的上皮单层完整性和上皮断裂出现短暂减少，这可能是由于配方的高渗透压性质所致。替诺福韦凝胶可防止 PBMC 感染 HIV-1，而与 HIV-1 亚型无关。局部和全身应用替诺福韦均可有效预防外植体培养物感染 HIV-1。
这些研究为配方杀微生物剂的临床前安全性和有效性预测提供了一种机制。替诺福韦在我们的算法中对 HIV-1 感染有效。这些数据支持使用替诺福韦进行暴露前预防。
