Division of Clinical Pharmacology (A.P., F.E., C.L.L., M. Saleem, J.K., T.D., L.A.A., D.M.P., A.K.), Vanderbilt University Medical Center, Nashville, TN.
Division of Nephrology (L.A.E., M. Sahinoz), Vanderbilt University Medical Center, Nashville, TN.
Circ Res. 2022 Aug 5;131(4):328-344. doi: 10.1161/CIRCRESAHA.122.320818. Epub 2022 Jul 12.
Salt sensitivity of blood pressure is an independent predictor of cardiovascular morbidity and mortality. The exact mechanism by which salt intake increases blood pressure and cardiovascular risk is unknown. We previously found that sodium entry into antigen-presenting cells (APCs) via the amiloride-sensitive epithelial sodium channel EnaC (epithelial sodium channel) leads to the formation of IsoLGs (isolevuglandins) and release of proinflammatory cytokines to activate T cells and modulate salt-sensitive hypertension. In the current study, we hypothesized that ENaC-dependent entry of sodium into APCs activates the NLRP3 (NOD [nucleotide-binding and oligomerization domain]-like receptor family pyrin domain containing 3) inflammasome via IsoLG formation leading to salt-sensitive hypertension.
We performed RNA sequencing on human monocytes treated with elevated sodium in vitro and Cellular Indexing of Transcriptomes and Epitopes by Sequencing analysis of peripheral blood mononuclear cells from participants rigorously phenotyped for salt sensitivity of blood pressure using an established inpatient protocol. To determine mechanisms, we analyzed inflammasome activation in mouse models of deoxycorticosterone acetate salt-induced hypertension as well as salt-sensitive mice with ENaC inhibition or expression, IsoLG scavenging, and adoptive transfer of wild-type dendritic cells into NLRP3 deficient mice.
We found that high levels of salt exposure upregulates the NLRP3 inflammasome, pyroptotic and apoptotic caspases, and IL (interleukin)-1β transcription in human monocytes. Cellular Indexing of Transcriptomes and Epitopes by Sequencing revealed that components of the NLRP3 inflammasome and activation marker IL-1β dynamically vary with changes in salt loading/depletion. Mechanistically, we found that sodium-induced activation of the NLRP3 inflammasome is ENaC and IsoLG dependent. NLRP3 deficient mice develop a blunted hypertensive response to elevated sodium, and this is restored by the adoptive transfer of NLRP3 replete APCs.
These findings reveal a mechanistic link between ENaC, inflammation, and salt-sensitive hypertension involving NLRP3 inflammasome activation in APCs. APC activation via the NLRP3 inflammasome can serve as a potential diagnostic biomarker for salt sensitivity of blood pressure.
血压的盐敏感性是心血管发病率和死亡率的独立预测因子。目前尚不清楚盐摄入量增加血压和心血管风险的确切机制。我们之前发现，通过阿米洛利敏感的上皮钠通道 EnaC（上皮钠通道），钠进入抗原呈递细胞 (APC) 会导致 IsoLGs（异亮氨酸-葡萄糖醛酸）的形成和促炎细胞因子的释放，从而激活 T 细胞并调节盐敏感型高血压。在目前的研究中，我们假设 APC 中钠的 ENaC 依赖性进入通过 IsoLG 形成激活 NLRP3（NOD [核苷酸结合和寡聚化结构域]样受体家族含有吡喃结构域 3）炎症小体，导致盐敏感型高血压。
我们对体外用高钠处理的人单核细胞进行了 RNA 测序，并对采用既定住院方案严格表型为血压对盐敏感性的参与者的外周血单核细胞进行了转录组和表位细胞指数测序分析。为了确定机制，我们分析了脱氧皮质酮盐诱导的高血压小鼠模型以及 ENaC 抑制或表达、IsoLG 清除以及野生型树突状细胞过继转移到 NLRP3 缺陷型小鼠中盐敏感性小鼠的炎症小体激活。
我们发现，高盐暴露会在上皮细胞中上调 NLRP3 炎症小体、细胞焦亡和凋亡半胱氨酸酶以及 IL（白细胞介素）-1β 的转录。转录组和表位细胞指数测序显示，NLRP3 炎症小体的组成部分和激活标志物 IL-1β 随盐负荷/耗竭的变化而动态变化。在机制上，我们发现钠诱导的 NLRP3 炎症小体的激活依赖于 ENaC 和 IsoLG。NLRP3 缺陷型小鼠对高钠的高血压反应减弱，而过继转移充满 NLRP3 的 APC 可恢复这种反应。
这些发现揭示了 ENaC、炎症和盐敏感型高血压之间的机制联系，涉及 APC 中 NLRP3 炎症小体的激活。APC 通过 NLRP3 炎症小体的激活可以作为血压对盐敏感性的潜在诊断生物标志物。
