Purpose: Inflammation has been strongly associated with retinal damage in diseases such as diabetic retinopathy. Several studies have reported that high glucose exposure induces damage to the retinal vasculature. We and others have shown that high glucose can activate the NOD-like receptor family, pyrin domain containing family member 3 (NLRP3) pathway, leading to increased levels of cleaved caspase 1 and IL-1β to activate a number of inflammatory pathways in the retina.
Methods: We used retinal endothelial cells grown in normal (5 mM) or high (25 mM) glucose or retinal lysates from endothelial cell-specific knockout mice for exchange protein activated by cAMP 1 (Epac1). Human recombinant protein kinase R (PKR) or C16, a PKR inhibitor, was used on the cells to dissect PKR and NLRP3 signaling.
Results: Using retinal endothelial cells (REC) in high glucose and whole retinal lysates from endothelial cell-specific knockout of Epac1, we demonstrate that Epac1 regulates PKR phosphorylation. Using an Epac1 agonist or PKR inhibition with C16, we demonstrated that loss of PKR resulted in reduced NLRP3, cleaved caspase 1, and IL-1β levels. Furthermore, despite the addition of recombinant human PKR, Epac1 was still able to significantly reduce NLRP3 signaling.
Conclusion: Overall, these studies demonstrated that PKR regulates the NLRP3 inflammasome in REC, and that Epac1 inhibition of PKR can reduce activation of the NLRP3 inflammasome.

Keywords: inflammasome, NLRP3, PKR, retinal endothelial cells



中文翻译：

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Epac1抑制PKR减少视网膜内皮细胞中的NLRP3炎症小体蛋白。

目的：在糖尿病性视网膜病等疾病中，炎症与视网膜损害密切相关。几项研究报道，高葡萄糖暴露会引起视网膜脉管系统损害。我们和其他人已经表明，高血糖可以激活NOD样受体家族，即含有家族成员3（NLRP3）的吡啶结构域，从而导致裂解的半胱天冬酶1和IL-1β的水平升高，从而激活视网膜中的许多炎症途径。 。
方法：我们使用生长在正常（5 mM）或高（25 mM）葡萄糖中的视网膜内皮细胞或来自内皮细胞特异性基因敲除小鼠的视网膜裂解液中的视网膜内皮细胞来交换被cAMP 1（Epac1）激活的蛋白质。人类重组蛋白激酶R（PKR）或C16（一种PKR抑制剂）被用于细胞中以分析PKR和NLRP3信号传导。
结果：使用高糖的视网膜内皮细胞（REC）和内皮细胞特异性敲除Epac1的整个视网膜溶解产物，我们证明Epac1调节PKR磷酸化。使用Epac1激动剂或C16抑制PKR，我们证明了PKR的丧失导致NLRP3降低，胱天蛋白酶1裂解和IL-1β水平降低。此外，尽管添加了重组人PKR，Epac1仍然能够显着降低NLRP3信号传导。
结论：总体而言，这些研究表明PKR调节REC中的NLRP3炎性小体，并且Epac1抑制PKR可以减少NLRP3炎性小体的活化。

关键词：炎性体，NLRP3，PKR，视网膜内皮细胞