Chaudhary Niraj, Ueno-Shuto Keiko, Ono Tomomi, Ohira Yuko, Watanabe Kenji, Nasu Aoi, Fujikawa Haruka, Nakashima Ryunosuke, Takahashi Noriki, Suico Mary Ann, Kai Hirofumi, Shuto Tsuyoshi
Department of Molecular Medicine, Graduate School of Pharmaceutical Sciences, Kumamoto University.
Program for Leading Graduate School of "HIGO (Health Life Science: Interdisciplinary and Global Oriented) Program," Kumamoto University.
Biol Pharm Bull. 2019 Mar 1;42(3):489-495. doi: 10.1248/bpb.b18-00928. Epub 2019 Jan 10.
Cystic fibrosis (CF), the most common lethal inherited disorder caused by mutation in the gene encoding the CF transmembrane regulator (CFTR), is characterized by chronic inflammation that ultimately leads to death from respiratory failure. In CF patients, up-regulation of toll-like receptor-2 (TLR2), a pattern recognition receptor that senses CF-pathogenic bacteria Staphylococcus aureus peptidoglycan (PGN), in airway epithelial cells is observed, and enhanced proinflammatory responses towards PGN may result in detrimental effects in CF patients. Here, we showed that curcumin, a well known anti-inflammatory agent derived from the curry spice turmeric, inhibits TLR2 expression in CF bronchial epithelial cell line, CFBE41o- cells. Strong suppression of TLR2 gene and protein expression was observed at more than 40 µM of curcumin treatment in CFBE41o- cells. Consistent with decreased expression of TLR2, PGN-dependent interleukin-8 (IL-8) gene up-regulation was markedly reduced by 40 µM of curcumin treatment. Strong reductions of TLR2 gene expression and function were also observed in primary human CF bronchial epithelial cells, but not in human non-CF primary cells. Interestingly, curcumin treatment decreased nuclear expression of transcription factor specificity protein 1 (SP1), a factor that is critical for increased basal TLR2 expression in CF cell line and primary cells. Finally, curcumin-dependent SP1 reduction was diminished by anti-oxidant N-acetylcystein (NAC) and proteasomal inhibitor MG-132, suggesting the crucial roles of oxidative and proteasomal degradation pathways. Taken together, our study shows that curcumin down-regulates TLR2 gene expression and function in CF bronchial epithelial cells possibly by accelerating SP1 degradation via an oxidative process.
囊性纤维化（CF）是由编码CF跨膜调节因子（CFTR）的基因突变引起的最常见的致死性遗传性疾病，其特征是慢性炎症，最终导致呼吸衰竭死亡。在CF患者中，观察到气道上皮细胞中Toll样受体2（TLR2）上调，TLR2是一种模式识别受体，可感知CF致病菌金黄色葡萄球菌肽聚糖（PGN），对PGN增强的促炎反应可能对CF患者产生有害影响。在此，我们表明姜黄素是一种源自咖喱香料姜黄的著名抗炎剂，可抑制CF支气管上皮细胞系CFBE41o-细胞中TLR2的表达。在CFBE41o-细胞中，用超过40μM的姜黄素处理时，观察到TLR2基因和蛋白表达受到强烈抑制。与TLR2表达降低一致，40μM的姜黄素处理可使PGN依赖性白细胞介素8（IL-8）基因上调明显减少。在原代人CF支气管上皮细胞中也观察到TLR2基因表达和功能的强烈降低，但在人非CF原代细胞中未观察到。有趣的是，姜黄素处理降低了转录因子特异性蛋白1（SP1）的核表达，SP1是CF细胞系和原代细胞中基础TLR2表达增加的关键因子。最后，抗氧化剂N-乙酰半胱氨酸（NAC）和蛋白酶体抑制剂MG-132减弱了姜黄素依赖性的SP1降低，表明氧化和蛋白酶体降解途径的关键作用。综上所述，我们的研究表明姜黄素可能通过氧化过程加速SP1降解，从而下调CF支气管上皮细胞中TLR2基因的表达和功能。
