Chang Mei-Chi, Hung Hsiu-Pin, Lin Li-Deh, Shyu Yow-Chyun, Wang Tong-Mei, Lin Hsueh-Jen, Chan Chiu-Po, Huang Chih-Chia, Jeng Jiiang-Huei
Biomedical Science Team, Chang Gung University of Science and Technology, Taoyuan, Taiwan.
Clin Oral Investig. 2015 Jan;19(1):117-26. doi: 10.1007/s00784-014-1227-0. Epub 2014 Mar 20.
Interleukin-1β (IL-1β) is an important inflammatory mediator of the dental pulp. IL-1β stimulates cyclooxygenase-2 (COX-2) expression and prostanoid production of pulp cells and affects the inflammatory and healing processes of the dental pulp. There are two interleukin-1 (IL-1) receptors, IL-1RI and IL-1RII, with opposing effect after activation. However, the expression of IL-1Rs, the effects of IL-1β on intercellular adhesion molecule-1 (ICAM-1) of dental pulp cells, and its relation to protein kinase B (Akt) signaling and COX activation are not clear.
Human dental pulp cells were treated with IL-1β with/without pretreatment and co-incubation by LY294002 (a PI3K/Akt inhibitor), U0126 [a mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (MEK/ERK) inhibitor], aspirin (a COX inhibitor), or eugenol (a COX inhibitor) for different time periods. The expression of ICAM-1, IL-1RI, and IL-1RII messenger RNA (mRNA) was evaluated by reverse transcriptase-polymerase chain reaction (RT-PCR). ICAM-1 protein expression was examined by western blotting. Soluble ICAM-1 (sICAM-1) level in the culture medium was determined by enzyme-linked immunosorbent assay (ELISA). Activation of Akt and ERK by IL-1β was measured by Pathscan p-Akt ELISA or western blot. Viable cell number was evaluated by 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay.
Dental pulp cells expressed IL-1RI, but little IL-1RII. IL-1β stimulated COX-2 and ICAM-1 mRNA and protein expression as well as sICAM-1 production of pulp cells. Aspirin and eugenol enhanced the IL-1β-induced sICAM-1 production and ICAM-1 expression. IL-1β rapidly activated Akt and ERK. LY294002 and U0126 attenuated IL-1β-induced ICAM-1 expression and sICAM-1 production.
These results reveal that IL-1β may be involved in the pulpal inflammatory processes by stimulating ICAM-1 expression and secretion. These events are associated with IL-1RI expression and differential activation of PI3K/Akt and MEK/ERK and COX.
Pharmacological inhibition of IL-1β, IL-1RI, COX-2, ICAM-1, and related signaling pathways (MEK/ERK and PI3K/Akt) may be useful for the control of pulpal inflammation.
白细胞介素-1β（IL-1β）是牙髓重要的炎症介质。IL-1β刺激牙髓细胞中环氧化酶-2（COX-2）的表达和前列腺素的产生，并影响牙髓的炎症和愈合过程。白细胞介素-1（IL-1）有两种受体，即IL-1RI和IL-1RII，激活后具有相反的作用。然而，IL-1受体的表达、IL-1β对牙髓细胞细胞间黏附分子-1（ICAM-1）的影响及其与蛋白激酶B（Akt）信号传导和COX激活的关系尚不清楚。
人牙髓细胞用IL-1β处理，有或无预处理，并与LY294002（一种PI3K/Akt抑制剂）、U0126 [一种丝裂原活化蛋白激酶激酶/细胞外信号调节激酶（MEK/ERK）抑制剂]、阿司匹林（一种COX抑制剂）或丁香酚（一种COX抑制剂）共同孵育不同时间段。通过逆转录聚合酶链反应（RT-PCR）评估ICAM-1、IL-1RI和IL-1RII信使核糖核酸（mRNA）的表达。通过蛋白质印迹法检测ICAM-1蛋白表达。采用酶联免疫吸附测定（ELISA）法测定培养基中可溶性ICAM-1（sICAM-1）水平。通过Pathscan p-Akt ELISA或蛋白质印迹法检测IL-1β对Akt和ERK的激活作用。通过3-(4,5-二甲基噻唑-2-基)-2,5-二苯基溴化四氮唑（MTT）法评估活细胞数量。
牙髓细胞表达IL-1RI，但IL-1RII表达很少。IL-1β刺激牙髓细胞COX-2和ICAM-1的mRNA及蛋白表达以及sICAM-1的产生。阿司匹林和丁香酚增强了IL-1β诱导的sICAM-1产生和ICAM-1表达。IL-1β迅速激活Akt和ERK。LY294002和U0126减弱了IL-1β诱导的ICAM-1表达和sICAM-1产生。
这些结果表明，IL-1β可能通过刺激ICAM-1的表达和分泌参与牙髓炎症过程。这些事件与IL-1RI表达以及PI3K/Akt和MEK/ERK及COX的不同激活有关。
对IL-1β、IL-1RI、COX-2、ICAM-1及相关信号通路（MEK/ERK和PI3K/Akt）进行药理抑制可能有助于控制牙髓炎症。
