Department of Immunology & Microbiology, Dasman Diabetes Institute, P.O. Box 1180, Dasman 15462, Kuwait.
Department of Translational Research, Dasman Diabetes Institute, P.O. Box 1180, Dasman 15462, Kuwait.
Int J Mol Sci. 2023 Oct 14;24(20):15186. doi: 10.3390/ijms242015186.
Obesity and metabolic syndrome involve chronic low-grade inflammation called metabolic inflammation as well as metabolic derangements from increased endotoxin and free fatty acids. It is debated whether the endoplasmic reticulum (ER) stress in monocytic cells can contribute to amplify metabolic inflammation; if so, by which mechanism(s). To test this, metabolic stress was induced in THP-1 cells and primary human monocytes by treatments with lipopolysaccharide (LPS), palmitic acid (PA), or oleic acid (OA), in the presence or absence of the ER stressor thapsigargin (TG). Gene expression of tumor necrosis factor ()- and markers of ER/oxidative stress were determined by qRT-PCR, TNF-α protein by ELISA, reactive oxygen species (ROS) by DCFH-DA assay, hypoxia-inducible factor 1-alpha (HIF-1α), p38, extracellular signal-regulated kinase (ERK)-1,2, and nuclear factor kappa B (NF-κB) phosphorylation by immunoblotting, and insulin sensitivity by glucose-uptake assay. Regarding clinical analyses, adipose TNF-α was assessed using qRT-PCR/IHC and plasma TNF-α, high-sensitivity C-reactive protein (hs-CRP), malondialdehyde (MDA), and oxidized low-density lipoprotein (OX-LDL) via ELISA. We found that the cooperative interaction between metabolic and ER stresses promoted TNF-α, ROS, CCAAT-enhancer-binding protein homologous protein (), activating transcription factor 6 (), superoxide dismutase 2 (), and nuclear factor erythroid 2-related factor 2 () expression ( ≤ 0.0183),. However, glucose uptake was not impaired. TNF-α amplification was dependent on HIF-1α stabilization and p38 MAPK/p65 NF-κB phosphorylation, while the MAPK/NF-κB pathway inhibitors and antioxidants/ROS scavengers such as curcumin, allopurinol, and apocynin attenuated the TNF-α production ( ≤ 0.05). Individuals with obesity displayed increased adipose TNF-α gene/protein expression as well as elevated plasma levels of TNF-α, CRP, MDA, and OX-LDL ( ≤ 0.05). Our findings support a metabolic-ER stress cooperativity model, favoring inflammation by triggering TNF-α production via the ROS/CHOP/HIF-1α and MAPK/NF-κB dependent mechanisms. This study also highlights the therapeutic potential of antioxidants in inflammatory conditions involving metabolic/ER stresses.
肥胖和代谢综合征涉及慢性低度炎症，称为代谢炎症，以及由于内毒素和游离脂肪酸增加而导致的代谢紊乱。单核细胞中的内质网 (ER) 应激是否可以促进代谢炎症的放大存在争议；如果是这样，通过哪种机制。为了测试这一点，通过用脂多糖 (LPS)、棕榈酸 (PA) 或油酸 (OA) 处理 THP-1 细胞和原代人单核细胞来诱导代谢应激，在存在或不存在内质网应激剂他普西醌 (TG) 的情况下。通过 qRT-PCR 确定肿瘤坏死因子 ()-和 ER/氧化应激标志物的基因表达，通过 ELISA 测定 TNF-α 蛋白，通过 DCFH-DA 测定反应性氧物种 (ROS)，通过免疫印迹测定缺氧诱导因子 1-α (HIF-1α)、p38、细胞外信号调节激酶 (ERK)-1、2 和核因子 kappa B (NF-κB) 磷酸化，通过葡萄糖摄取测定胰岛素敏感性。关于临床分析，使用 qRT-PCR/IHC 评估脂肪组织 TNF-α，通过 ELISA 测定血浆 TNF-α、高敏 C 反应蛋白 (hs-CRP)、丙二醛 (MDA) 和氧化型低密度脂蛋白 (OX-LDL)。我们发现，代谢应激和 ER 应激之间的协同相互作用促进了 TNF-α、ROS、CCAAT 增强子结合蛋白同源蛋白 ()、激活转录因子 6 ()、超氧化物歧化酶 2 () 和核因子红细胞 2 相关因子 2 () 的表达（≤0.0183）。然而，葡萄糖摄取并没有受损。TNF-α 扩增依赖于 HIF-1α 稳定和 p38 MAPK/p65 NF-κB 磷酸化，而 MAPK/NF-κB 通路抑制剂和抗氧化剂/ROS 清除剂，如姜黄素、别嘌醇和阿朴肉桂酸，可减弱 TNF-α的产生（≤0.05）。肥胖个体表现出脂肪组织 TNF-α 基因/蛋白表达增加以及血浆 TNF-α、CRP、MDA 和 OX-LDL 水平升高（≤0.05）。我们的研究结果支持代谢-ER 应激协同模型，通过触发 ROS/CHOP/HIF-1α 和 MAPK/NF-κB 依赖机制促进 TNF-α 产生，从而引发炎症。这项研究还强调了抗氧化剂在涉及代谢/ER 应激的炎症情况下的治疗潜力。
