Graduate Institute of Health Industry Technology, Research Center for Chinese Herbal Medicine and Research Center for Food and Cosmetic Safety, Chang Gung University of Science and Technology, Taoyuan, Taiwan; Department of Pulmonary Infection and Immunology, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan.
School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan.
Cytokine. 2020 Sep;133:155185. doi: 10.1016/j.cyto.2020.155185. Epub 2020 Jun 29.
Exposure to airborne particulate matter (PM) increases the proportion of oral inflammatory diseases. During the formation of inflammatory conditions, the nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome activation plays an important regulator. Carbon monoxide (CO) arising from heme degradation, catalyzed particularly by heme oxygenase-1 (HO-1), has been shown to own cytoprotective effects including anti-inflammation and antioxidant. Here, we determined the novel mechanisms of carbon monoxide releasing molecule-2 (CORM-2) on PM-induced inflammatory responses in human oral keratinocytes (HOKs).
The effects of CORM-2 on the expression of various inflammatory proteins induced by PM were determined by Western blot, real-time PCR, promoter assay, and ELISA. The involvement of signaling molecules in these responses was studied by using the selective pharmacological inhibitors and siRNAs.
We proved that PM enhanced C-reactive protein (CRP) levels, NLRP3 inflammasome and caspase-1 activation, and IL-1β release, which were reduced by preincubation with CORM-2. Transfection with PKCα siRNA and preincubation with the ROS scavenger (N-acetyl-cysteine, NAC), an inhibitor of NADPH oxidase (diphenyleneiodonium, DPI), or the mitochondria-specific superoxide scavenger (MitoTEMPO) inhibited PM-mediated inflammatory responses. In addition, PM-regulated PKCα and NADPH oxidase activation as well as NADPH oxidase- and mitochondria-derived ROS generation were inhibited by CORM-2, but not inactivate CORM-2 (iCORM-2) pretreatment. At the end, we confirmed that CORM-2 improved PM-induced inflammatory responses via the induction of Nrf2 activation and HO-1 expression.
We suggest that CORM-2 inhibits PM-induced inflammatory responses in HOKs via the inhibition of PKCα/ROS/NLRP3 inflammasome activation combined with the induction of Nrf2/HO-1 expression.
空气中的颗粒物（PM）暴露会增加口腔炎症性疾病的比例。在炎症形成过程中，核苷酸结合域和富含亮氨酸重复蛋白 3（NLRP3）炎症小体的激活起着重要的调节作用。血红素降解产生的一氧化碳（CO），特别是由血红素加氧酶-1（HO-1）催化，已显示出具有细胞保护作用，包括抗炎和抗氧化作用。在这里，我们确定了一氧化碳释放分子-2（CORM-2）对人口腔角质细胞（HOK）中 PM 诱导的炎症反应的新机制。
通过 Western blot、实时 PCR、启动子测定和 ELISA 测定 CORM-2 对 PM 诱导的各种炎症蛋白表达的影响。通过使用选择性药理抑制剂和 siRNA 研究这些反应中信号分子的参与。
我们证明 PM 增强了 C 反应蛋白（CRP）水平、NLRP3 炎症小体和半胱天冬酶-1 的激活以及 IL-1β 的释放，这些反应可通过 CORM-2 预处理来减少。PKCα siRNA 转染和 ROS 清除剂（N-乙酰半胱氨酸，NAC）、NADPH 氧化酶抑制剂（二苯并碘，DPI）或线粒体特异性超氧化物清除剂（MitoTEMPO）预处理抑制 PM 介导的炎症反应。此外，PM 调节 PKCα 和 NADPH 氧化酶的激活以及 NADPH 氧化酶和线粒体衍生的 ROS 的产生被 CORM-2 抑制，但 CORM-2 （iCORM-2）预处理不能使其失活。最后，我们证实 CORM-2 通过诱导 Nrf2 激活和 HO-1 表达来改善 PM 诱导的炎症反应。
我们认为 CORM-2 通过抑制 PKCα/ROS/NLRP3 炎症小体的激活并诱导 Nrf2/HO-1 的表达来抑制 HOK 中 PM 诱导的炎症反应。
