Interferon e restricts Zika infection at the female reproductive tract. Interferon e restricts Zika infection at the female reproductive tract

Interferon ε (IFNε), a unique type I IFN, is thought to protect the host against sexually transmitted infections. Unlike conventional type I IFNs (e.g., IFNα/β), whose expression is undetectable at baseline, IFNε expression is detectable in the epithelium of mucosal tissues, particularly the female reproductive tract (FRT). We found that IFNε expression was not limited to epithelial cells at the FRT. Importantly, in contrast to previous reports, IFNε expression in plasmacytoid dendritic cells and primary cervical epithelial cells was induced by viral infection and by activation of TLR3 or 4 in PBMCs. Induction of IFNε mRNAs was also found in cervicovaginal tissues (CVT) of Zika virus (ZIKV)-infected mice. Mice with IFNε deficiency (Ifnε-/-) did not have impaired induction of interferon-stimulated genes except IFNl, but had altered epithelial and collagen structure in the CVT. Ifnε-/- mice exhibited increased susceptibility to ZIKV infection via an intravaginal route but not via a subcutaneous route, indicating that the protective effect of IFNe was specific to the FRT. Infected Ifnε-/- mice had higher and more sustained viral loads than infected wild-type (WT) mice. Detection of ZIKV infection by single molecule in situ hybridization confirmed that virus spread faster in Ifnε-/- mice than in WT mice. Recombinant murine IFNε protected Ifnar1-/- mice against ZIKV infection when administered through an intravaginal route but not when administered through a subcutaneous route, indicating that the specific role of IFNe at the FRT is independent of IFNAR1 signaling. Our findings indicate that IFNε mediates a novel FRT-specific protective effect on mucosal immunity that limits Zika virus spread. Overall design: female C57BL/6J (WT) and IFN epsilon deficiency mice generated by using CRISPR-Cas9 at 6-12 weeks were treated with Depo-Provera for 12 days. Cervicovaginal tissues were harvested and total RNAs were prepared for RNAseq analyses.

干扰素ε（Interferon ε, IFNε）是一类独特的I型干扰素，被认为可帮助宿主抵御性传播感染。与常规I型干扰素（如IFNα/β）在基线状态下表达难以检出不同，IFNε可在黏膜组织上皮细胞中被检测到，尤其在雌性生殖道（female reproductive tract, FRT）中。我们的研究发现，IFNε的表达并非仅局限于雌性生殖道的上皮细胞。值得注意的是，与既往研究结论相悖，外周血单个核细胞（peripheral blood mononuclear cells, PBMCs）中的浆细胞样树突状细胞以及原代宫颈上皮细胞内的IFNε表达，可经病毒感染以及TLR3或TLR4的激活而被诱导。寨卡病毒（Zika virus, ZIKV）感染的小鼠宫颈阴道组织（cervicovaginal tissues, CVT）中同样可检测到IFNε mRNA的诱导表达。
IFNε敲除（Ifnε-/-）小鼠除干扰素λ（IFNλ）外，干扰素刺激基因的诱导并未受到损伤，但它们的宫颈阴道组织上皮与胶原结构出现改变。Ifnε-/-小鼠经阴道途径感染寨卡病毒时易感性升高，但经皮下途径感染时则无此现象，这表明IFNε的保护作用具有雌性生殖道特异性。感染后的Ifnε-/-小鼠体内病毒载量较野生型（wild-type, WT）小鼠更高且持续时间更久。单分子原位杂交检测证实，寨卡病毒在Ifnε-/-小鼠体内的扩散速度快于WT小鼠。重组小鼠IFNε经阴道途径给药时，可保护IFNAR1敲除（Ifnar1-/-）小鼠抵御寨卡病毒感染，但经皮下途径给药时则无此保护效果，这表明IFNε在雌性生殖道中的特定作用不依赖于IFNAR1信号通路。我们的研究结果表明，IFNε可介导一种全新的雌性生殖道特异性黏膜免疫保护效应，从而限制寨卡病毒的扩散。
实验整体设计：选取6~12周龄的雌性C57BL/6J野生型小鼠与经CRISPR-Cas9技术构建的IFNε敲除小鼠，给予醋酸甲羟孕酮（Depo-Provera）处理12天。采集宫颈阴道组织，提取总RNA用于RNA测序（RNAseq）分析。