Endogenous Neurosteroid (3α,5α)3-Hydroxypregnan-20-one Inhibits Toll-like-4 Receptor Activation and Pro-inflammatory Signaling in Macrophages and Brain
Endogenous Neurosteroid (3α,5α)3-Hydroxypregnan-20-one Inhibits Toll-like-4 Receptor Activation and Pro-inflammatory Signaling in Macrophages and Brain
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DOI：
10.1038/s41598-018-37409-6
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发表时间：
2019-02-04
影响因子：
4.6
通讯作者：
Morrow, A. Leslie
中科院分区：
文献类型：
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作者：
Balan, Irina;Beattie, Matthew C.;Morrow, A. Leslie
内源性神经类固醇(3α，5α)3-羟孕酮-20-酮(3α，5α-THP，别孕酮)在酒精中毒、抑郁症、创伤性脑损伤、精神分裂症、多发性硬化症和阿尔茨海默病等动物模型中具有保护活性，但了解较少。由于这些情况涉及通过Toll样受体(TLRs)的促炎信号，我们研究了3α，5αTHP和孕烯醇酮对外周和中枢神经系统(CNS)TLR4激活的影响。我们使用单核/巨噬细胞(RAW264.7)作为外周免疫信号的模型，研究了选择性繁殖的嗜酒(P)大鼠腹侧被盖区(VTA)内天然激活的TLR4。脂多糖激活RAW264.7细胞中的TLR4途径，表现为p-TAK1、TRAF6、核因子-kappaB p50、磷酸化核因子-kappaB-p65、pCREB、HMGB1以及包括MCP-1和TNFα在内的炎症介质水平的增加。3α，5α-THP和孕烯醇酮(0.5-1.0µM)均显著抑制这些效应(与80%相似)，表明TLR4信号被显著抑制。其抑制机制似乎涉及阻断RAW246.7细胞中TLR4/MD-2蛋白的相互作用。在VTA，3α，5α-THP(15 mg/kg，ip)可降低TRAF6(约20%)、CRF(约30%)和MCP-1(约20%)的水平，以及TLR4与GABAA受体a2亚基的结合(约60%)和MyD88(约40%)。这些数据表明，抑制促炎神经免疫信号是3α，5α-THP在免疫细胞和脑内保护作用的基础，显然涉及阻断启动TLR4依赖信号的蛋白质-蛋白质相互作用。抑制促炎因子TLR4的激活代表了3α，5αTHP在外周和脑内发挥作用的新机制。
The endogenous neurosteroid (3 alpha,5 alpha)3-hydroxypregnan-20-one (3 alpha,5 alpha-THP, allopregnanolone) has protective activity in animal models of alcoholism, depression, traumatic brain injury, schizophrenia, multiple sclerosis, and Alzheimer's disease that is poorly understood. Because these conditions involve proinflammatory signaling through toll-like receptors (TLRs), we examined the effects of 3 alpha,5 alpha-THP, and pregnenolone on TLR4 activation in both the periphery and the central nervous system (CNS). We used monocytes/macrophages (RAW264.7) as a model of peripheral immune signaling and studied innately activated TLR4 in the ventral tegmental area (VTA) of selectively bred alcohol-preferring (P) rats. LPS activated the TLR4 pathway in RAW264.7 cells as evidenced by increased levels of p-TAK1, TRAF6, NF-kappa B p50, phospho-NF-kappa B-p65, pCREB, HMGB1, and inflammatory mediators, including MCP-1 and TNF alpha. Both 3 alpha,5 alpha-THP and pregnenolone (0.5-1.0 mu M) substantially (similar to 80%) inhibited these effects, indicating pronounced inhibition of TLR4 signaling. The mechanism of inhibition appears to involve blockade of TLR4/MD-2 protein interactions in RAW246.7 cells. In VTA, 3 alpha,5 alpha-THP (15 mg/kg, IP) administration reduced TRAF6 (similar to 20%), CRF (similar to 30%), and MCP-1 (similar to 20%) levels, as well as TLR4 binding to GABAA receptor a2 subunits (similar to 60%) and MyD88 (similar to 40%). The data suggest that inhibition of proinflammatory neuroimmune signaling underlies protective effects of 3 alpha,5 alpha-THP in immune cells and brain, apparently involving blocking of protein-protein interactions that initiate TLR4-dependent signaling. Inhibition of pro-inflammatory TLR4 activation represents a new mechanism of 3 alpha,5 alpha-THP action in the periphery and the brain.