Pahwa R, Devaraj S, Jialal I
Laboratory for Atherosclerosis and Metabolic Research, Department of Pathology, Division of Endocrinology, Diabetes and Metabolism, University of California Davis Medical Center, Sacramento, CA, USA.
Medical Services, VA Medical Center, Mather, CA, USA.
Int J Obes (Lond). 2016 Jun;40(6):907-11. doi: 10.1038/ijo.2016.32. Epub 2016 Feb 16.
There is a growinge body of evidence pointing towards an important role for Toll-like receptors (TLR) especially TLR4 in obesity and metabolic syndrome.
Owing to the paucity of data on the effect of the accessory proteins, lipopolysaccharide (LPS)-binding protein (LBP) and soluble CD14 (sCD14) on TLR4 activation, the present study was undertaken to examine the effect of sCD14 and LBP on TLR4 activation in pivotal cells of meta-inflammation, monocytes and adipocytes.
The dose-response effects of sCD14 and LBP on TLR4 protein abundance in monocytes obtained from normal human volunteers was determined by flow cytometry and in human-differentiated adipocytes by western blotting. Additionally, the nuclear factor-kappaB (NF-κB) p65 and downstream biomediators interleukin (IL)-1β, IL-8, IL-6 and tumor necrosis factor (TNF)-α were measured in the cell culture supernatants by ELISA (enzyme-linked immunosorbent assay).
In LPS-primed monocytes, sCD14 but not LBP, augments both TLR4 abundance and inflammatory biomediators (IL-1β, IL-8, IL-6 and TNF-α).sCD14 also showed a similar effect in LPS-primed human adipocytes by augmenting TLR4 protein expression and activity in terms of NF-κB p65 and downstream biomediators (IL-1β, IL-8, IL-6 and TNF-α). LBP at the highest concentration only promoted secretion of IL-8 and TNF-α. However in both monocytes and adipocytes, the effect of sCD14 was superior to LBP.
In the present report, we make the novel observation that sCD14 compared with LBP, offers a preferred target to ameliorate TLR especially TLR4-induced inflammation and insulin resistance in human obesity and metabolic syndrome.
越来越多的证据表明，Toll样受体（TLR）尤其是TLR4在肥胖和代谢综合征中发挥重要作用。
由于关于辅助蛋白脂多糖（LPS）结合蛋白（LBP）和可溶性CD14（sCD14）对TLR4激活作用的数据较少，本研究旨在探讨sCD14和LBP对代谢性炎症关键细胞（单核细胞和脂肪细胞）中TLR4激活的影响。
通过流式细胞术测定sCD14和LBP对从正常人类志愿者获取的单核细胞中TLR4蛋白丰度的剂量反应效应，并通过蛋白质印迹法测定对人分化脂肪细胞中TLR4蛋白丰度的剂量反应效应。此外，通过酶联免疫吸附测定法（ELISA）检测细胞培养上清液中的核因子-κB（NF-κB）p65以及下游生物介质白细胞介素（IL）-1β、IL-8、IL-6和肿瘤坏死因子（TNF）-α。
在经LPS预处理的单核细胞中，sCD14而非LBP可增加TLR4丰度以及炎症生物介质（IL-1β、IL-8、IL-6和TNF-α）。sCD14在经LPS预处理的人脂肪细胞中也显示出类似作用，可增加TLR4蛋白表达以及NF-κB p65和下游生物介质（IL-1β、IL-8、IL-6和TNF-α）相关的活性。最高浓度的LBP仅促进IL-8和TNF-α的分泌。然而，在单核细胞和脂肪细胞中，sCD14的作用均优于LBP。
在本报告中，我们有一个新发现，即与LBP相比，sCD14为改善人类肥胖和代谢综合征中TLR尤其是TLR4诱导的炎症和胰岛素抵抗提供了一个更优靶点。
