Expression and activation of the ketone body receptor HCAR2/GPR109A promotes preservation of retinal endothelial cell barrier function.
Expression and activation of the ketone body receptor HCAR2/GPR109A promotes preservation of retinal endothelial cell barrier function.
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DOI：
10.1016/j.exer.2022.109129
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发表时间：
2022-08-01
影响因子：
3.4
通讯作者：
Martin, Pamela M
中科院分区：
文献类型：
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作者：
Abdelrahman, Ammar A;Powell, Folami L;Martin, Pamela M
视网膜屏障功能的保护对于维持视网膜健康至关重要。因此，屏障完整性的丧失是退行性视网膜疾病如糖尿病性视网膜病常见的病理特征并不奇怪。我们先前的研究证明了羟基羧酸受体2/GPR 109 A（HCAR 2/GPR 109 A）在视网膜色素上皮（RPE）中的表达对外部视网膜屏障完整性的重要性。然而，HCAR 2/GPR 109 A是否在视网膜内皮细胞中表达并与内部血液视网膜屏障调节具有类似的关系尚不清楚。在目前的研究中，我们研究了受体表达与内皮细胞依赖性血视网膜屏障完整性的相关性。siRNA技术用于调节人视网膜内皮细胞（HREC）中HCAR 2/GPR 109 A的表达。在存在或不存在VEGF、促炎刺激物和/或各种浓度的HCAR 2/GPR 109 A特异性激动剂β-羟基丁酸酯（BHB）的情况下培养细胞。通过qPCR监测HCAR 2/GPR 109 A表达，并使用电细胞阻抗传感（ECIS）来评估屏障功能。在用脂多糖和/或BHB腹膜内处理的野生型和HCAR 2/GPR 109 A敲除小鼠中进行补充体内研究。使用荧光素血管造影术和蛋白质印迹分析白蛋白外渗监测血管渗漏。此外，通过OptoMotry评价视网膜功能。HCAR 2/GPR 109 A表达的降低（siRNA敲除）或缺失（基因敲除）与体外和体内屏障功能受损相关。BHB治疗提供了一些保护，限制了视网膜屏障完整性和功能的破坏;发现这种作用是受体（HCAR 2/GPR 109 A）依赖性的。总的来说，本研究支持HCAR 2/GPR 109 A在调节血液-视网膜屏障完整性中的关键作用，并突出了受体对预防和治疗视网膜疾病如糖尿病视网膜病变的治疗潜力，其中屏障功能受损是至关重要的。
Preservation of retinal barrier function is critical to maintenance of retinal health. Therefore, it is not surprising that loss of barrier integrity is a pathologic feature common to degenerative retinal diseases such as diabetic retinopathy. Our prior studies demonstrate the importance of hydroxycarboxylic acid receptor 2/GPR109A (HCAR2/GPR109A) expression in the retinal pigment epithelium (RPE) to outer retinal barrier integrity. However, whether HCAR2/GPR109A is expressed in retinal endothelial cells and has a similar relationship to inner blood retinal barrier regulation is not known. In the current study, we examined relevance of receptor expression to endothelial cell dependent-blood retinal barrier integrity. siRNA technology was used to modulate HCAR2/GPR109A expression in human retinal endothelial cells (HRECs). Cells were cultured in the presence or absence of VEGF, a pro-inflammatory stimulus, and/or various concentrations of the HCAR2/GPR109A-specific agonist beta-hydyroxybutyrate (BHB). HCAR2/GPR109A expression was monitored by qPCR and electrical cell impedance sensing (ECIS) was used to evaluate barrier function. Complementary in vivo studies were conducted in wildtype and HCAR2/GPR109A knockout mice treated intraperitoneally with lipopolysaccharide and/or BHB. Vascular leakage was monitored using fluorescein angiography and Western blot analyses of albumin extravasation. Additionally, retinal function was evaluated by OptoMotry. Decreased (siRNA knockdown) or absent (gene knockout) HCAR2/GPR109A expression was associated with impaired barrier function both in vitro and in vivo. BHB treatment provided some protection, limiting disruptions in retinal barrier integrity and function; an effect that was found to be receptor (HCAR2/GPR109A)-dependent. Collectively, the present studies support a key role for HCAR2/GPR109A in regulating blood-retinal barrier integrity and highlight the therapeutic potential of the receptor toward preventing and treating retinal diseases such as diabetic retinopathy in which compromised barrier function is paramount.