■在早期动脉粥样硬化,循环LDLs(低密度脂蛋白)通过称为胞吞作用的主动过程穿越单个内皮细胞。CANTOS试验使用IL-1β(白介素-1β)的阻断抗体治疗晚期动脉粥样硬化;这显着减少了心血管事件。然而,IL-1β是否调节早期疾病,特别是LDL胞吞作用,仍然未知。
■我们使用全内反射荧光显微镜来定量暴露于IL-1β的人冠状动脉内皮细胞的胞吞作用。为了研究体内转胞吞作用,我们给野生型和基因敲除小鼠注射IL-1β和LDL,观察急性LDL在主动脉弓的沉积.
■暴露于皮摩尔浓度的IL-1β诱导的人冠状动脉内皮细胞的LDL而不是白蛋白的胞吞作用。令人惊讶的是,2种已知的LDL胞吞受体的表达,ALK-1(活化素受体样激酶-1)和SR-BI(清道夫受体BI),不变或减少。相反,IL-1β增加LDLR(LDL受体)的表达;这是出乎意料的,因为LDLR不是LDL转胞吞作用所必需的。LDLR的过表达对基础LDL胞吞没有影响。然而,LDLR的敲低消除了IL-1β对胞吞率的影响,而Cav-1(caveolin-1)的消耗则没有。由于LDLR是必需的,但过表达没有影响,我们认为必须有另一个玩家参与。使用公开的RNAseq数据来整理受IL-1β影响的RabGTP酶列表,我们确认了Rab27a.单独过表达Rab27a对基础胞吞无影响,但它的敲除阻止了IL-1β的诱导。这是由于Rab27a效应子JFC1的耗尽而出现的。在体内,IL-1β增加野生型但不Ldlr-/-或Rab27a缺陷小鼠的主动脉弓中的LDL胞吞作用。JFC1抑制剂nexhibb20还阻断了IL-1β诱导的LDL在主动脉中的积累。
■IL-1β通过需要LDLR和Rab27a的不同途径诱导LDL胞吞;该途径不同于基础胞吞。我们推测,IL-1β诱导胞吞作用可能有助于加速早期疾病的发生。
UNASSIGNED: In early atherosclerosis, circulating LDLs (low-density lipoproteins) traverse individual endothelial cells by an active process termed transcytosis. The CANTOS trial treated advanced atherosclerosis using a blocking antibody for IL-1β (interleukin-1β); this significantly reduced cardiovascular events. However, whether IL-1β regulates early disease, particularly LDL
transcytosis, remains unknown.
UNASSIGNED: We used total internal reflection fluorescence microscopy to quantify transcytosis by human coronary artery endothelial cells exposed to IL-1β. To investigate transcytosis in vivo, we injected wild-type and knockout mice with IL-1β and LDL to visualize acute LDL deposition in the aortic arch.
UNASSIGNED: Exposure to picomolar concentrations of IL-1β induced
transcytosis of LDL but not of albumin by human coronary artery endothelial cells. Surprisingly, expression of the 2 known receptors for LDL
transcytosis, ALK-1 (activin receptor-like kinase-1) and SR-BI (scavenger receptor BI), was unchanged or decreased. Instead, IL-1β increased the expression of the LDLR (LDL receptor); this was unexpected because LDLR is not required for LDL transcytosis. Overexpression of LDLR had no effect on basal LDL
transcytosis. However, knockdown of LDLR abrogated the effect of IL-1β on transcytosis rates while the depletion of Cav-1 (caveolin-1) did not. Since LDLR was necessary but overexpression had no effect, we reasoned that another player must be involved. Using public RNAseq data to curate a list of Rab GTPases affected by IL-1β, we identified Rab27a. Overexpression of Rab27a alone had no effect on basal transcytosis, but its knockdown prevented induction by IL-1β. This was phenocopied by depletion of the Rab27a effector JFC1. In vivo, IL-1β increased LDL transcytosis in the aortic arch of wild-type but not Ldlr-/- or Rab27a-deficient mice. The JFC1 inhibitor nexinhib20 also blocked IL-1β-induced LDL accumulation in the aorta.
UNASSIGNED: IL-1β induces LDL transcytosis by a distinct pathway requiring LDLR and Rab27a; this route differs from basal
transcytosis. We speculate that induction of transcytosis by IL-1β may contribute to the acceleration of early disease.