Zhang Jia-Lu, Wang Xue-Fei, Li Jia-Lin, Duan Cong, Wang Jiu-Feng
National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China.
College of Veterinary Medicine, Southwest University, Chongqing, 400715, China.
Vet Res. 2025 Jan 31;56(1):23. doi: 10.1186/s13567-025-01452-9.
25-Hydroxycholesterol (25HC) is a hydroxylated cholesterol with multiple antiviral activities, however, little is known about the mechanisms by which 25HC correlates antiviral ability with lipid droplet (LD) dynamic balance to ensure cholesterol homeostasis. In the present study, 25HC was applied to porcine deltacoronavirus (PDCoV)-infected LLC-PK1 (Lilly Laboratories Culture-Porcine Kidney 1) cells and piglets to explore its antiviral capacity and underlying mechanism. The results revealed that 25HC decreased free cholesterol (FC) levels but increased triglyceride (TG) levels in PDCoV-infected cells and piglets. The accumulation of LDs induced by oleic acid (OA) impedes PDCoV replication. In addition, 25HC administration increases LD accumulation and declines protein expression associated with lipophagy and lysosomes to facilitate LD accumulation. Moreover, 25HC inhibited TFEB (transcription factor-EB) expression, blocked its translocation into the nucleus and reversed Mechanistic Target of Rapamycin Complex 1 (mTORC1) activity, which in turn hindered lipophagy and PDCoV replication. Additionally, 25HC treatment ameliorated the clinical symptoms and intestinal injury of PDCoV-infected piglets. These findings reveal the beneficial effect of lipophagy on PDCoV infection and uncover the antiviral mechanism of 25HC, by which lipophagy and mTOR activity are tightly controlled by 25HC.
25-羟基胆固醇（25HC）是一种具有多种抗病毒活性的羟基化胆固醇，然而，关于25HC将抗病毒能力与脂滴（LD）动态平衡相关联以确保胆固醇稳态的机制，人们知之甚少。在本研究中，将25HC应用于感染猪德尔塔冠状病毒（PDCoV）的LLC-PK1（礼来实验室培养-猪肾1）细胞和仔猪，以探索其抗病毒能力及潜在机制。结果显示，25HC降低了PDCoV感染细胞和仔猪中的游离胆固醇（FC）水平，但提高了甘油三酯（TG）水平。油酸（OA）诱导的脂滴积累会阻碍PDCoV复制。此外，给予25HC会增加脂滴积累，并降低与脂质自噬和溶酶体相关的蛋白质表达，以促进脂滴积累。而且，25HC抑制转录因子EB（TFEB）的表达，阻止其转运至细胞核，并逆转雷帕霉素复合物1（mTORC1）的活性，进而阻碍脂质自噬和PDCoV复制。此外，25HC治疗改善了PDCoV感染仔猪的临床症状和肠道损伤。这些发现揭示了脂质自噬对PDCoV感染的有益作用，并揭示了25HC的抗病毒机制，即25HC可紧密控制脂质自噬和mTOR活性。
