State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China.
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China.
Exp Eye Res. 2024 Apr;241:109851. doi: 10.1016/j.exer.2024.109851. Epub 2024 Mar 5.
The accumulation of oleic acid (OA) in the meibum from patients with meibomian gland dysfunction (MGD) suggests that it may contribute to meibomian gland (MG) functional disorder, as it is a potent stimulator of acne-related lipogenesis and inflammation in sebaceous gland. Therefore, we investigate whether OA induces lipogenesis and inflammasome activation in organotypic cultured mouse MG and human meibomian gland epithelial cells (HMGECs). Organotypic cultured mouse MG and HMGECs were exposed to OA or combinations with specific AMPK agonists 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR). Lipogenic status, ductal keratinization, squamous metaplasia, NLRP3/ASC/Caspase-1 inflammasome activation, proinflammatory cytokine IL-1β production, and AMPK pathway phosphorylation in MG were subsequently examined by lipid staining, immunofluorescence staining, immunohistochemical staining, ELISA assay, and Western blot analyses. We found that OA significantly induced lipid accumulation, ductal keratinization, and squamous metaplasia in organotypic cultured MG, as evidenced by increased lipids deposition within acini and duct, upregulated expression of lipogenic proteins (SREBP-1 and HMGCR), and elevation of K10/Sprr1b. Additionally, OA induced NLRP3/ASC/Caspase-1 inflammasome activation, cleavage of Caspase-1, and production of downstream proinflammatory cytokine IL-1β. The findings of lipogenesis and NLRP3-related proinflammatory response in OA-stimulated HMGECs were consistent with those in organotypic cultured MG. OA exposure downregulated phospho-AMPK in two models, while AICAR treatment alleviated lipogenesis by improving AMPK/ACC phosphorylation and SREBP-1/HMGCR expression. Furthermore, AMPK amelioration inhibited activation of the NLRP3/ASC/Caspase-1 axis and secretion of IL-1β, thereby relieving the OA-induced proinflammatory response. These results demonstrated that OA induced lipogenic disorder and NLRP3 inflammasome activation in organotypic cultured mouse MG and HMGECs by suppressing the AMPK signaling pathway, indicating OA may play an etiological role in MGD.
油酸（OA）在患有睑板腺功能障碍（MGD）的患者的睑板腺分泌物中的积累表明，它可能导致睑板腺（MG）功能障碍，因为它是皮脂腺中与痤疮相关的脂肪生成和炎症的有效刺激物。因此，我们研究了 OA 是否会诱导器官培养的小鼠 MG 和人睑板腺上皮细胞（HMGEC）中的脂肪生成和炎性体激活。将器官培养的小鼠 MG 和 HMGEC 暴露于 OA 或与特定 AMPK 激动剂 5-氨基咪唑-4-甲酰胺核苷酸（AICAR）的组合中。随后通过脂质染色、免疫荧光染色、免疫组织化学染色、ELISA 测定和 Western blot 分析检查 MG 中的脂肪生成状态、导管角化、鳞状化生、NLRP3/ASC/Caspase-1 炎性体激活、促炎细胞因子 IL-1β的产生以及 AMPK 途径的磷酸化。我们发现，OA 显著诱导器官培养的 MG 中的脂质积累、导管角化和鳞状化生，这表现在腺泡内和导管内脂质沉积增加、脂肪生成蛋白（SREBP-1 和 HMGCR）的表达上调以及 K10/Sprr1b 的升高。此外，OA 诱导 NLRP3/ASC/Caspase-1 炎性体激活、Caspase-1 的切割和下游促炎细胞因子 IL-1β的产生。在 OA 刺激的 HMGECs 中观察到的脂肪生成和 NLRP3 相关的促炎反应与器官培养的 MG 中的反应一致。OA 暴露降低了两种模型中的磷酸化 AMPK，而 AICAR 处理通过改善 AMPK/ACC 磷酸化和 SREBP-1/HMGCR 表达来减轻脂肪生成。此外，AMPK 改善抑制了 NLRP3/ASC/Caspase-1 轴的激活和 IL-1β的分泌，从而缓解了 OA 诱导的促炎反应。这些结果表明，OA 通过抑制 AMPK 信号通路在器官培养的小鼠 MG 和 HMGEC 中诱导脂肪生成障碍和 NLRP3 炎性体激活，表明 OA 可能在 MGD 中起病因作用。
