Epigenetic Regulation of Tolerance to Toll-Like Receptor Ligands in Alveolar Epithelial Cells
Epigenetic Regulation of Tolerance to Toll-Like Receptor Ligands in Alveolar Epithelial Cells
复制标题
DOI：
10.1165/rcmb.2015-0057oc
复制
发表时间：
2015-12-01
影响因子：
6.4
通讯作者：
Ballinger, Megan N.
中科院分区：
文献类型：
--
作者：
Neagos, Jacqueline;Standiford, Theodore J.;Ballinger, Megan N.
为了保护宿主免受旺盛的炎症和损伤反应，细胞有能力对微生物和非微生物的反复刺激变得低反应或“耐受”。肺空域不断暴露于各种外源性和内源性toll样受体（TLR）配体，但肺泡上皮细胞（AECs）的耐受性能力尚未得到检验。我们假设II型aec在反复接触TLR激动剂后会产生耐受性表型。为了验证这一假设，从小鼠肺部分离的原代AEC和小鼠AEC细胞系（MLE-12）分别用载体对照或TLR配体刺激18小时，清洗，然后用载体或TLR配体再刺激6小时。通过测量TLR配体刺激的趋化因子（单核细胞趋化蛋白[MCP]-1/CCL2、角化细胞趋化蛋白[KC]/CXCL1和巨噬细胞炎症蛋白[MIP]-2/CXCL2）的产生来评估耐受性。用TLR激动剂序贯治疗原代aec或MLE-12细胞可诱导耐受或交叉耐受。诱导耐受性不是由于TLR信号的特异性负调节因子（白介素-1受体相关激酶[IRAK]-M， toll相互作用蛋白[Tollip]，单个Ig il -1相关受体[SIGIRR]或细胞因子信号抑制因子[SOCS]），抑制性microrna （mir，特别是miR-155和miR146a）的表达，或抑制性或调节性可溶性介质（前列腺素E2， IL-10，转化生长因子b或IFN-a/b）的分泌。此外，抑制组蛋白去甲基化或DNA甲基化并不能阻止耐受性的发展。然而，用组蛋白去乙酰化酶抑制剂trichostatin A或亚eroylanilide hyrozamine治疗aec可导致耐受性表型逆转。这些发现表明表观遗传修饰调控aec耐受诱导的新机制。
To protect the host against exuberant inflammation and injury responses, cells have the ability to become hyporesponsive or "tolerized" to repeated stimulation by microbial and nonmicrobial insults. The lung airspace is constantly exposed to a variety of exogenous and endogenous Toll-like receptor (TLR) ligands, yet the ability of alveolar epithelial cells (AECs) to be tolerized has yet to be examined. We hypothesize that type II AECs will develop a tolerance phenotype upon repeated TLR agonist exposure. To test this hypothesis, primary AECs isolated from the lungs of mice and a murine AEC cell line (MLE-12) were stimulated with either a vehicle control or a TLR ligand for 18 hours, washed, then restimulated with either vehicle or TLR ligand for an additional 6 hours. Tolerance was assessed by measurement of TLR ligand-stimulated chemokine production (monocyte chemoattractant protein [MCP]-1/CCL2, keratinocyte chemoattractant [KC]/CXCL1, and macrophage inflammatory protein [MIP]-2/CXCL2). Sequential treatment of primary AECs or MLE-12 cells with TLR agonists resulted in induction of either tolerance or cross-tolerance. The induction of tolerance was not due to expression of specific negative regulators of TLR signaling (interleukin-1 receptor associated kinase [IRAK]-M, Toll-interacting protein [Tollip], single Ig IL-1-related receptor [SIGIRR], or suppressor of cytokine signaling [SOCS]), inhibitory microRNAs (miRs; specifically, miR-155 and miR146a), or secretion of inhibitory or regulatory soluble mediators (prostaglandin E2, IL-10, transforming growth factor-b, or IFN-a/b). Moreover, inhibition of histone demethylation or DNA methylation did not prevent the development of tolerance. However, treatment of AECs with the histone deacetylase inhibitors trichostatin A or suberoylanilide hyrozamine resulted in reversal of the tolerance phenotype. These findings indicate a novel mechanism by which epigenetic modification regulates the induction of tolerance in AECs.