Umsumarng Sonthaya, Dissook Sivamoke, Arjsri Punnida, Srisawad Kamonwan, Thippraphan Pilaiporn, Sangphukieo Apiwat, Thongkumkoon Patcharawadee, Dejkriengkraikul Pornngarm
Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai 50100, Thailand.
Center for Research and Development of Natural Products for Health, Chiang Mai University, Chiang Mai 50200, Thailand.
Pharmaceuticals (Basel). 2024 Oct 20;17(10):1402. doi: 10.3390/ph17101402.
BACKGROUND/OBJECTIVES: The global SARS-CoV-2 outbreak has escalated into a critical public health emergency, with the spike glycoprotein S1 subunit of SARS-CoV-2 (spike-S1) linked to inflammation in lung tissue and immune cells. Luteolin, a flavone with anti-inflammatory properties, shows promise, but research on its effectiveness against long-COVID-related inflammation and spike protein-induced responses remains limited. This study aims to elucidate the underlying mechanisms of inflammation in THP-1 cells induced by the spike-S1. Additionally, it seeks to assess the potential of luteolin in mitigating inflammatory responses induced by the spike-S1 in a THP-1 macrophage model.
The gene expression profiles of spike-S1 in THP-1 cells were analyzed by transcriptome sequencing. The inhibitory effect of luteolin on ER stress and inflammation in spike-S1-induced THP-1 cells was investigated using Western blotting, RT-PCR, and ELISA.
The candidate genes (, , , , , , and ) were upregulated in the spike-S1-induced THP-1 group compared to the control group. Among these, calcium/calmodulin-dependent protein kinase II alpha (CAMK2A) was identified as the most promising molecule in spike-S1-induced THP-1 cells. Our results indicate that the spike S1 significantly increased the expression of ER-stress markers at both gene and protein levels. Luteolin significantly reduced ER stress by decreasing the expression of ER-stress marker genes and ER-stress marker proteins ( < 0.01). Additionally, luteolin exhibited anti-inflammatory properties upon spike S1-induction in THP-1 cells by significantly suppressing IL-6, IL-8, and IL-1β cytokine secretion in a dose-dependent manner ( < 0.05). Furthermore, our results revealed that luteolin exhibited the downregulation of the MAPK pathway, as evidenced by modulating the phosphorylation of p-ERK1/2, p-JNK and p-p38 proteins ( < 0.05).
The results from this study elucidate the mechanisms by which the spike S1 induces inflammation in THP-1 cells and supports the use of naturally occurring bioactive compounds, like luteolin, against inflammation-related SARS-CoV-2 infection.
背景/目的：全球严重急性呼吸综合征冠状病毒2（SARS-CoV-2）疫情已升级为重大公共卫生事件，SARS-CoV-2的刺突糖蛋白S1亚基（刺突-S1）与肺组织和免疫细胞中的炎症有关。木犀草素是一种具有抗炎特性的黄酮类化合物，显示出一定前景，但关于其对新冠后遗症相关炎症和刺突蛋白诱导反应有效性的研究仍然有限。本研究旨在阐明刺突-S1诱导THP-1细胞炎症的潜在机制。此外，它试图评估木犀草素在THP-1巨噬细胞模型中减轻刺突-S1诱导的炎症反应的潜力。
通过转录组测序分析刺突-S1在THP-1细胞中的基因表达谱。使用蛋白质印迹法、逆转录-聚合酶链反应（RT-PCR）和酶联免疫吸附测定（ELISA）研究木犀草素对刺突-S1诱导的THP-1细胞内质网应激和炎症的抑制作用。
与对照组相比，刺突-S1诱导的THP-1组中候选基因（、、、、、和）上调。其中，钙/钙调蛋白依赖性蛋白激酶IIα（CAMK2A）被确定为刺突-S1诱导的THP-1细胞中最有前景的分子。我们的结果表明，刺突S1在基因和蛋白质水平上均显著增加内质网应激标志物的表达。木犀草素通过降低内质网应激标志物基因和内质网应激标志物蛋白的表达显著减轻内质网应激（<0.01）。此外，木犀草素在刺突S1诱导的THP-1细胞中表现出抗炎特性，通过以剂量依赖性方式显著抑制白细胞介素-6（IL-6）、白细胞介素-8（IL-8）和白细胞介素-1β（IL-1β）细胞因子分泌（<0.05）。此外，我们的结果显示木犀草素表现出丝裂原活化蛋白激酶（MAPK）途径的下调，这通过调节p-细胞外信号调节激酶（ERK）1/2、p-氨基末端激酶（JNK）和p-p38蛋白的磷酸化得到证明（<0.05）。
本研究结果阐明了刺突S1诱导THP-1细胞炎症的机制，并支持使用天然存在的生物活性化合物，如木犀草素，来对抗与炎症相关的SARS-CoV-2感染。
