Department of Endocrinology, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China.
Department of Endocrinology, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China.
Exp Eye Res. 2021 Jan;202:108300. doi: 10.1016/j.exer.2020.108300. Epub 2020 Oct 13.
Diabetic retinopathy (DR) is the leading cause of visual impairment and acquired blindness among adults worldwide. Retinal microvascular pericyte deficiency is one of the earliest pathological changes associated with DR, and long noncoding RNA myocardial infarction-associated transcript (MIAT) has been implicated as a crucial regulator of microvascular dysfunction in DR. Pyroptosis is a caspase-1-dependent proinflammatory form of cell death, and in the present study, we investigated the potential pyroptosis of primary human retinal pericytes (HRPCs) and the mechanism by which MIAT is involved in this process. We applied advanced glycation end product modified bovine serum albumin (AGE-BSA) to simulate the DR environment. The results suggested that AGE-BSA induced the active cleavage of caspase-1 and gasdermin D, the release of IL-1β, IL-18 and LDH, and reduced cell viability, which was prevented by the inhibition of caspase-1, indicating the occurrence of caspase-1-mediated pyroptosis in HRPCs. Immunofluorescence images revealed the phenotypic characteristics of pyroptosis, including pyknosis, swelling and hyperpermeability in plasmolemma. MIAT and CASP1 expression were substantially increased, while that of miR-342-3p was decreased in AGE-BSA-treated HRPCs. MIAT knockdown inhibited pyroptosis in HRPCs, which was reinforced by cotreatment with miR-342-3p mimic but relieved by cotreatment with miR-342-3p inhibitor. Furthermore, HRPC pyroptosis was inhibited by treatment with the miR-342-3p mimic alone but enhanced by the miR-342-3p inhibitor. Luciferase reporter assay results demonstrated binding between MIAT and miR-342-3p, as well as between miR-342-3p and CASP1. MIAT antagonized the effect of miR-342-3p on the depression of its target CASP1 and promoted AGE-BSA-induced pericyte pyroptosis. These findings may promote a better understanding of retinal pericyte depletion pathogenesis and the development of new therapeutic strategies for the treatment of diabetic retinopathy.
糖尿病性视网膜病变（DR）是全球成年人视力损害和获得性失明的主要原因。视网膜微血管周细胞缺失是与 DR 相关的最早的病理变化之一，长链非编码 RNA 心肌梗塞相关转录物（MIAT）已被认为是 DR 中小血管功能障碍的关键调节因子。细胞焦亡是一种半胱天冬酶-1 依赖性促炎形式的细胞死亡，在本研究中，我们研究了原发性人视网膜周细胞（HRPC）的潜在细胞焦亡以及 MIAT 参与该过程的机制。我们应用晚期糖基化终产物修饰牛血清白蛋白（AGE-BSA）来模拟 DR 环境。结果表明，AGE-BSA 诱导半胱天冬酶-1 和 gasdermin D 的活性裂解、IL-1β、IL-18 和 LDH 的释放以及细胞活力的降低，这可以通过半胱天冬酶-1 的抑制来预防，表明 HRPC 中发生了半胱天冬酶-1 介导的细胞焦亡。免疫荧光图像显示了细胞焦亡的表型特征，包括核固缩、质膜肿胀和高通透性。AGE-BSA 处理后的 HRPC 中 MIAT 和 CASP1 的表达显著增加，而 miR-342-3p 的表达降低。MIAT 敲低抑制了 HRPC 中的细胞焦亡，miR-342-3p 模拟物的共处理增强了这种作用，而 miR-342-3p 抑制剂的共处理则减轻了这种作用。此外，miR-342-3p 模拟物单独处理抑制了 HRPC 的细胞焦亡，而 miR-342-3p 抑制剂增强了这种作用。荧光素酶报告基因检测结果表明 MIAT 与 miR-342-3p 以及 miR-342-3p 与 CASP1 之间存在结合。MIAT 拮抗了 miR-342-3p 对其靶基因 CASP1 的抑制作用，并促进了 AGE-BSA 诱导的周细胞细胞焦亡。这些发现可能有助于更好地理解视网膜周细胞耗竭的发病机制，并为糖尿病性视网膜病变的治疗开发新的治疗策略。
