Korade Zeljka, Tallman Keri A, Kim Hye-Young H, Balog Marta, Genaro-Mattos Thiago C, Pattnaik Aryamav, Mirnics Károly, Pattnaik Asit K, Porter Ned A
Department of Pediatrics, Biochemistry and Molecular Biology, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States.
Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States.
ACS Pharmacol Transl Sci. 2022 Oct 25;5(11):1086-1096. doi: 10.1021/acsptsci.2c00051. eCollection 2022 Nov 11.
Cholesterol is ubiquitous in cells; it plays a critical role in membrane structure and transport as well as in intracellular trafficking processes. There are suggestions that cholesterol metabolism is linked to innate immunity with inhibitors of DHCR7, the last enzyme in the cholesterol pathway, suggested to have potential as viral therapeutics nearly a decade ago. In fact, there are a number of highly prescribed pharmaceuticals that are off-target inhibitors of DHCR7, causing increased cellular levels of 7-dehydrodesmosterol (7-DHD) and 7-dehydrocholesterol (7-DHC). We report here dose-response studies of six such inhibitors on late-stage cholesterol biosynthesis in Neuro2a cells as well as their effect on infection of vesicular stomatitis virus (VSV). Four of the test compounds are FDA-approved drugs (cariprazine, trazodone, metoprolol, and tamoxifen), one (ifenprodil) has been the object of a recent Phase 2b COVID trial, and one (AY9944) is an experimental compound that has seen extensive use as a DHCR7 inhibitor. The three FDA-approved drugs inhibit replication of a GFP-tagged VSV with efficacies that mirror their effect on DHCR7. Ifenprodil and AY9944 have complex inhibitory profiles, acting on both DHCR7 and DHCR14, while tamoxifen does not inhibit DHCR7 and is toxic to Neuro2a at concentrations where it inhibits the Δ7-Δ8 isomerase of the cholesterol pathway. VSV itself affects the sterol profile in Neuro2a cells, showing a dose-response increase of dehydrolathosterol and lathosterol, the substrates for DHCR7, with a corresponding decrease in desmosterol and cholesterol. 7-DHD and 7-DHC are orders of magnitude more vulnerable to free radical chain oxidation than other sterols as well as polyunsaturated fatty esters, and the effect of these sterols on viral infection is likely a reflection of this fact of Nature.
胆固醇在细胞中无处不在；它在膜结构与运输以及细胞内运输过程中发挥着关键作用。有迹象表明胆固醇代谢与先天免疫相关，近十年前就有人提出胆固醇途径中的最后一种酶——DHCR7的抑制剂具有作为病毒治疗药物的潜力。事实上，有一些高处方量的药物是DHCR7的脱靶抑制剂，会导致细胞内7-脱氢去氢胆甾醇（7-DHD）和7-脱氢胆固醇（7-DHC）水平升高。我们在此报告六种此类抑制剂对Neuro2a细胞晚期胆固醇生物合成的剂量反应研究，以及它们对水疱性口炎病毒（VSV）感染的影响。四种受试化合物是美国食品药品监督管理局（FDA）批准的药物（卡立普唑、曲唑酮、美托洛尔和他莫昔芬），一种（艾芬地尔）是近期一项2b期新冠试验的研究对象，另一种（AY9944）是一种实验性化合物，已被广泛用作DHCR7抑制剂。三种FDA批准的药物抑制带有绿色荧光蛋白（GFP）标记的VSV复制，其效力反映了它们对DHCR7的作用。艾芬地尔和AY9944具有复杂的抑制模式，对DHCR7和DHCR14均有作用，而他莫昔芬不抑制DHCR7，且在抑制胆固醇途径的Δ7-Δ8异构酶的浓度下对Neuro2a细胞有毒性。VSV本身会影响Neuro2a细胞中的甾醇谱，表现出7-脱氢胆甾醇和胆甾烯醇（DHCR7的底物）的剂量反应性增加，同时去氢胆甾醇和胆固醇相应减少。7-DHD和7-DHC比其他甾醇以及多不饱和脂肪酸酯更容易受到自由基链氧化的影响，这些甾醇对病毒感染的影响可能反映了这一自然事实。
