Wang H-W, Kok S-H, Yang C-N, Hong C-Y, Chi C-W, Chen M-H, Cheng S-J, Shun C-T, Yang H, Lin S-K
Department of Dentistry, National Taiwan University Hospital, Taipei, Taiwan.
Graduate Institute of Clinical Dentistry, School of Dentistry, College of Medicine, National Taiwan University, Taipei, Taiwan.
Int Endod J. 2021 Jun;54(6):902-915. doi: 10.1111/iej.13468. Epub 2021 Jan 17.
To examine the role of palmitic acid in lipopolysaccharide (LPS)-stimulated chemotaxis of macrophages and the potential contribution of saturated fatty acid in signalling during the pathogenesis of apical periodontitis.
J774, a mouse macrophage cell line, was used in the experiments. After treatment with LPS, proteolytic maturation of sterol regulatory element-binding protein-1c (SREBP-1c) and expression of fatty acid synthase (FASN) were examined by Western analysis. Levels of palmitic acid were measured by reverse phase-high performance liquid chromatography-mass spectrometry. Knockdown of SREBP-1c and FASN was accomplished by small interfering RNA technology. Secretion of CC-chemokine ligand 2 (CCL2) and cellular chemotaxis were assessed by enzyme-linked immunosorbent assay and transwell migration assay, respectively. Sulfo-N-succinimidyl oleate (SSO) treatment was used to inhibit fatty acid signalling in vitro and also in a rat model of apical periodontitis. All data were first subjected to Levene's test. In vitro data were then analysed using ANOVA followed by Tukey's multiple comparison test. Data from animal experiments were analysed by independent t-tests. The significant level was set at 0.05.
LPS stimulated proteolytic maturation of SREBP-1c and FASN expression in macrophages and significantly enhanced palmitic acid synthesis (P < 0.05). Knockdown of SREBP-1c attenuated LPS-enhanced FASN expression. Knockdown of FASN significantly suppressed LPS-enhanced palmitic acid synthesis (P < 0.05). LPS and exogenous palmitic acid significantly enhanced CCL2 secretion and macrophage chemotaxis (all P < 0.05). Inhibition of FASN expression significantly alleviated LPS-augmented CCL2 secretion (P < 0.05). SSO significantly suppressed CCL2 secretion and macrophage chemotaxis augmented by LPS and palmitic acid (all P < 0.05). In a rat model of induced apical periodontitis, SSO treatment significantly attenuated progression of apical periodontitis and macrophage recruitment (all P < 0.05).
LPS/SREBP-1c/FASN/palmitic acid signalling contributed to tissue destruction caused by bacterial infection. Modulation of lipid metabolism and signalling may be helpful for the management of apical periodontitis.
探讨棕榈酸在脂多糖（LPS）刺激的巨噬细胞趋化作用中的作用，以及饱和脂肪酸在根尖周炎发病机制信号传导中的潜在作用。
实验采用小鼠巨噬细胞系J774。用LPS处理后，通过蛋白质印迹分析检测固醇调节元件结合蛋白-1c（SREBP-1c）的蛋白水解成熟和脂肪酸合酶（FASN）的表达。通过反相高效液相色谱-质谱法测定棕榈酸水平。采用小干扰RNA技术敲低SREBP-1c和FASN。分别通过酶联免疫吸附测定和Transwell迁移试验评估CC趋化因子配体2（CCL2）的分泌和细胞趋化作用。使用磺基-N-琥珀酰亚胺油酸酯（SSO）处理在体外以及在根尖周炎大鼠模型中抑制脂肪酸信号传导。所有数据首先进行Levene检验。然后使用方差分析（ANOVA）和Tukey多重比较检验分析体外数据。动物实验数据通过独立t检验进行分析。显著性水平设定为0.05。
LPS刺激巨噬细胞中SREBP-1c的蛋白水解成熟和FASN表达，并显著增强棕榈酸合成（P<0.05）。敲低SREBP-1c减弱了LPS增强的FASN表达。敲低FASN显著抑制LPS增强的棕榈酸合成（P<0.05）。LPS和外源性棕榈酸显著增强CCL2分泌和巨噬细胞趋化作用（所有P<0.05）。抑制FASN表达显著减轻LPS增强的CCL2分泌（P<0.05）。SSO显著抑制LPS和棕榈酸增强的CCL2分泌和巨噬细胞趋化作用（所有P<0.05）。在诱导性根尖周炎大鼠模型中，SSO处理显著减轻根尖周炎的进展和巨噬细胞募集（所有P<0.05）。
LPS/SREBP-1c/FASN/棕榈酸信号传导导致细菌感染引起的组织破坏。调节脂质代谢和信号传导可能有助于根尖周炎的治疗。
