Cryptococcus neoformans (Cn) is the leading cause of fungal meningitis, a deadly disease with limited therapeutic options. Dissemination to the central nervous system hinges on the ability of Cn to breach the blood-brain barrier (BBB) and is considered an attribute of Cn virulence. Targeting virulence instead of growth for antifungal drug development has not been fully exploited despite the benefits of this approach. Mpr1 is a secreted fungal metalloprotease not required for fungal growth, but rather, it functions as a virulence factor by facilitating Cn migration across the BBB. This central role for Mpr1, its extracellular location, and lack of expression in mammalian cells make Mpr1 a high-value target for an antivirulence approach aimed at developing therapeutics for cryptococcal meningitis. To test this notion, we devised a large-scale screen to identify compounds that prohibited Cn from crossing the BBB by selectively blocking Mpr1 proteolytic activity, without inhibiting the growth of Cn. A phytochemical natural product-derived library was screened to identify new molecular scaffolds of prototypes unique to a Cn microecosystem. Of the 240 pure natural products examined, 3 lead compounds, abietic acid, diosgenin, and lupinine inhibited Mpr1 proteolytic activity with 50% inhibitory concentration (IC₅₀) values of <10 μM, displayed little to no mammalian cell toxicity, and did not affect Cn growth. Notably, the lead compounds blocked Cn from crossing the BBB, without damaging the barrier integrity, suggesting the bioactive molecules had no off-target effects. We propose that these new drug scaffolds are promising candidates for the development of antivirulence therapy against cryptococcal meningitis.

中文翻译：

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一种通过新的真菌金属蛋白酶天然产物抑制剂防止新隐球菌越过血脑屏障的抗病毒方法。

新型隐球菌（Cn）是真菌性脑膜炎的主要原因，这种真菌性脑膜炎是一种致命的疾病，治疗选择有限。向中枢神经系统的传播取决于Cn突破血脑屏障（BBB）的能力，并且被认为是Cn毒力的属性。尽管使用这种方法有很多好处，但针对毒力而不是针对抗真菌药物开发的生长尚未得到充分利用。Mpr1是一种真菌生长所需的分泌型真菌金属蛋白酶，而是通过促进Cn发挥毒力因子的作用跨BBB迁移。Mpr1的这种中心作用，其在细胞外的位置以及在哺乳动物细胞中的缺乏表达使Mpr1成为旨在开发隐球菌性脑膜炎治疗剂的抗病毒方法的高价值目标。为了验证该概念，我们设计了一个大型屏幕，以通过选择性地阻断Mpr1的蛋白水解活性而不抑制Cn的生长来识别禁止Cn穿过BBB的化合物。筛选了植物化学天然产物来源的文库，以鉴定Cn微生态系统特有的原型的新分子支架。在所检查的240种纯天然产品中，3种先导化合物，松香酸，薯gen皂甙元和羽扇豆碱抑制Mpr1的蛋白水解活性，抑制浓度为50％（IC₅₀）的值<10μM，几乎没有或没有哺乳动物细胞毒性，并且不影响Cn的生长。值得注意的是，先导化合物在不损害屏障完整性的情况下阻止了Cn穿过BBB，这表明生物活性分子没有脱靶作用。我们建议这些新的药物支架有望成为针对隐球菌性脑膜炎的抗病毒治疗的发展候选药物。