School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China.
Department of Neurology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 200437, China.
Environ Pollut. 2021 Jan 1;268(Pt B):115961. doi: 10.1016/j.envpol.2020.115961. Epub 2020 Oct 29.
Ambient fine particulate matter (PM) can change the expression profile of microRNAs (miRs), which may play important roles in mediating inflammatory responses. The present study attempts to investigate the roles of miR-146a-5p in regulating cytokine expression in a human monocytic leukemia cell line (THP-1). Four types of PM extracts obtained from Beijing, China, were subjected to cytotoxic tests in THP-1 cells. These four PM extracts included two water extracts collected from non-heating and heating season (WN and WH), and two organic extracts from non-heating and heating season (DN and DH). Firstly, the four PM extracts caused cytotoxicity, oxidative stress responses, cytokine gene expressions and interleukin 8 (IL-8) release in THP-1 cells, with WH showing the highest cytotoxicity, WN showing the highest oxidative stress and inflammatory responses. Additionally, we observed expression of miR-146a-5p was significantly increased, with the maximal response of six folds in WN group. Cellular autophagy was initiated by PM indicated by related protein and gene expressions. Both RNA interference and autophagy inhibitor were applied to interrupt autophagy process in THP-1 cells. Autophagy dysfunction could alleviate IL-8 expression, suggesting autophagy process regulated cytokine expression and inflammatory response caused by PM. A chemical inhibitor was applied to inhibit the function of miR-146a-5p, and then the expressions of IL-8 and autophagic genes were significantly aggravated. Meanwhile, two target genes of miR-146a-5p, interleukin-1 associated-kinase-1 (IRAK1) and tumor-necrosis factor receptor-associated factor-6 (TRAF6) were increased dramatically, which also played important roles in regulation of autophagy. These data suggested miR-146a-5p negatively modulated cytokine expression caused by PM via autophagy process through the target genes of IRAK1 and TRAF6. Our findings raised the concerns of the changes of miR expression profile and following responses caused by PM.
环境细颗粒物 (PM) 可以改变 microRNAs (miRs) 的表达谱，miRs 可能在介导炎症反应中发挥重要作用。本研究试图探讨 miR-146a-5p 在调节人单核白血病细胞系 (THP-1) 中细胞因子表达中的作用。将从中国北京采集的四种 PM 提取物用于 THP-1 细胞的细胞毒性试验。这四种 PM 提取物包括两个非加热季和加热季采集的水提取物（WN 和 WH），以及两个非加热季和加热季采集的有机提取物（DN 和 DH）。首先，四种 PM 提取物均导致 THP-1 细胞的细胞毒性、氧化应激反应、细胞因子基因表达和白细胞介素 8 (IL-8) 释放，其中 WH 提取物的细胞毒性最高，WN 提取物的氧化应激和炎症反应最高。此外，我们观察到 miR-146a-5p 的表达显著增加，WN 组的最大反应为六倍。PM 诱导的细胞自噬通过相关蛋白和基因表达来表示。在 THP-1 细胞中应用 RNA 干扰和自噬抑制剂来阻断自噬过程。自噬功能障碍可以减轻 IL-8 表达，提示自噬过程调节 PM 引起的细胞因子表达和炎症反应。应用化学抑制剂抑制 miR-146a-5p 的功能，然后显著加重 IL-8 和自噬基因的表达。同时，miR-146a-5p 的两个靶基因，白细胞介素-1 相关激酶-1 (IRAK1) 和肿瘤坏死因子受体相关因子-6 (TRAF6) 显著增加，它们在调节自噬中也发挥重要作用。这些数据表明，miR-146a-5p 通过 IRAK1 和 TRAF6 的靶基因，通过自噬过程负调控 PM 引起的细胞因子表达。我们的研究结果引起了人们对 PM 引起的 miR 表达谱变化及其后续反应的关注。
