Arroba Ana I, Rodríguez-de la Rosa Lourdes, Murillo-Cuesta Silvia, Vaquero-Villanueva Laura, Hurlé Juan M, Varela-Nieto Isabel, Valverde Ángela M
Alberto Sols Biomedical Research Institute (IIBm) (CSIC/UAM), 28029, Madrid, Spain Spanish Biomedical Research Centre in Diabetes and Associated Metabolic Disorders (CIBERdem), ISCIII, 28029, Madrid, Spain
Alberto Sols Biomedical Research Institute (IIBm) (CSIC/UAM), 28029, Madrid, Spain Biomedical Research Networking Centre on Rare Diseases (CIBERER), ISCIII, 28029, Madrid, Spain IdiPAZ Institute for Health Research, Madrid 28029, Spain.
Dis Model Mech. 2016 Sep 1;9(9):965-74. doi: 10.1242/dmm.026344. Epub 2016 Jul 21.
Insulin-like growth factor-1 (IGF-1) is a growth factor with differentiating, anti-apoptotic and metabolic functions in the periphery, and anti-inflammatory properties in the nervous system. Mice that have mutations in the Igf1 gene, rendering the gene product inactive (Igf1(-/-)), present with age-related visual loss accompanied by structural alterations in the first synapses of the retinal pathway. Recent advances have revealed a crucial role of autophagy in immunity and inflammation. Keeping in mind this close relationship, we aimed to decipher these processes in the context of the defects that occur during ageing in the retina of Igf1(-/-) mice. Tnfa and Il1b mRNAs, and phosphorylation of JNK and p38 MAPK were elevated in the retinas of 6- and 12-month old Igf1(-/-) mice compared to those in age-matched Igf1(+/+) controls. In 6-month-old Igf1(-/-) retinas, increased mRNA levels of the autophagy mediators Becn1, Atg9, Atg5 and Atg4, decreased p62 (also known as SQSTM1) protein expression together with an increased LC3-II:LC3-I ratio reflected active autophagic flux. However, in retinas from 12-month-old Igf1(-/-) mice, Nlrp3 mRNA, processing of the IL1β pro-form and immunostaining of active caspase-1 were elevated compared to those in age-matched Igf1(+/+) controls, suggesting activation of the inflammasome. This effect concurred with accumulation of autophagosomes and decreased autophagic flux in the retina. Microglia localization and status of activation in the retinas of 12-month-old Igf1(+/+) and Igf1(-/-) mice, analyzed by immunostaining of Cd11b and Iba-1, showed a specific distribution pattern in the outer plexiform layer (OPL), inner plexiform layer (IPL) and inner nuclear layer (INL), and revealed an increased number of activated microglia cells in the retina of 12-month-old blind Igf1(-/-) mice. Moreover, reactive gliosis was exclusively detected in the retinas from 12-month-old blind Igf1(-/-) mice. In conclusion, this study provides new evidence in a mouse model of IGF-1 deficiency that autophagy is an adaptive response that might confer protection against persistent inflammation in the retina during ageing.
胰岛素样生长因子-1(IGF-1)是一种生长因子,在外周具有分化、抗凋亡和代谢功能,在神经系统具有抗炎特性。Igf1基因发生突变致使基因产物无活性的小鼠(Igf1(-/-))会出现与年龄相关的视力丧失,并伴有视网膜通路首个突触的结构改变。最近的研究进展揭示了自噬在免疫和炎症中的关键作用。考虑到这种密切关系,我们旨在在Igf1(-/-)小鼠视网膜衰老过程中出现的缺陷背景下解读这些过程。与年龄匹配的Igf1(+/+)对照小鼠相比,6个月和12个月大的Igf1(-/-)小鼠视网膜中Tnfa和Il1b mRNA以及JNK和p38 MAPK的磷酸化水平升高。在6个月大的Igf1(-/-)视网膜中,自噬介质Becn1、Atg9、Atg5和Atg4的mRNA水平升高,p62(也称为SQSTM1)蛋白表达降低,同时LC3-II:LC3-I比值增加,反映出自噬流活跃。然而,在12个月大的Igf1(-/-)小鼠视网膜中,与年龄匹配的Igf1(+/+)对照小鼠相比,Nlrp3 mRNA、IL1β前体形式的加工以及活性半胱天冬酶-1的免疫染色水平升高,表明炎性小体被激活。这种效应与视网膜中自噬体的积累和自噬流的降低同时出现。通过对Cd11b和Iba-1进行免疫染色分析12个月大的Igf1(+/+)和Igf1(-/-)小鼠视网膜中小胶质细胞的定位和激活状态,结果显示在外丛状层(OPL)、内丛状层(IPL)和内核层(INL)呈现特定的分布模式,并揭示12个月大的失明Igf1(-/-)小鼠视网膜中活化小胶质细胞数量增加。此外,仅在12个月大的失明Igf1(-/-)小鼠视网膜中检测到反应性胶质增生。总之,本研究在IGF-1缺乏的小鼠模型中提供了新证据,表明自噬是一种适应性反应,可能在衰老过程中为视网膜抵御持续性炎症提供保护。