Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, United States of America.
Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, United States of America.
Toxicol Appl Pharmacol. 2020 Dec 1;408:115258. doi: 10.1016/j.taap.2020.115258. Epub 2020 Sep 30.
Previous studies in MRL+/+ mice suggest involvement of oxidative stress (OS) in trichloroethene (TCE)-mediated autoimmunity. However, molecular mechanisms underlying the autoimmunity remain to be fully elucidated. Even though toll-like receptors (TLRs) and Nuclear factor (erythroid-derived 2)-like2 (Nrf2) pathways are implicated in autoimmune diseases (ADs), interplay of OS, TLR and Nrf2 in TCE-mediated autoimmune response remains unexplored. This study was, therefore, undertaken to clearly establish a link among OS, TLR4 and Nrf2 pathways in TCE-induced autoimmunity. Groups of female MRL+/+ mice were treated with TCE, sulforaphane (SFN, an antioxidant) or TCE + SFN (TCE, 10 mmol/kg, i.p., every 4th day; SFN, 8 mg/kg, i.p., every other day) for 6 weeks. TCE exposure led to greater formation of serum 4-hydroxynonenal (HNE)-protein adducts, HNE-specific circulating immune complexes (CICs) and protein carbonyls which were associated with significant increases in serum antinuclear antibodies (ANAs). Moreover, incubation of splenocytes from TCE-treated mice with HNE-modified proteins resulted in enhanced splenocyte proliferation and cytokine release evidenced by increased expression of cyclin D3, Cyclin-dependent kinase 6 (CDK6) and phospho-pRb as well as increased release of IL-6, TNF-α and INF-γ. More importantly, TCE exposure resulted in increased expression of TLR4, MyD88, IRAK4, NF-kB and reduced expression of Nrf2 and HO-1 in the spleen. Remarkably, SFN supplementation not only attenuated TCE-induced OS, upregulation in TLR4 and NF-kB signaling and downregulation of Nrf2, but also ANA levels. These results, in addition to providing further support to a role of OS, also suggest that an interplay among OS, TLR4 and Nrf2 pathways contributes to TCE-mediated autoimmune response. Attenuation of TCE-mediated autoimmunity by SFN provides an avenue for preventive and/or therapeutic strategies for ADs involving OS.
先前在 MRL+/+ 小鼠中的研究表明，三氯乙烯 (TCE) 介导的自身免疫与氧化应激 (OS) 有关。然而，自身免疫的分子机制仍有待充分阐明。尽管 Toll 样受体 (TLRs) 和核因子 (erythroid-derived 2)-样 2 (Nrf2) 途径与自身免疫性疾病 (ADs) 有关，但 OS、TLR 和 Nrf2 途径在 TCE 介导的自身免疫反应中的相互作用仍未得到探索。因此，本研究旨在明确 OS、TLR4 和 Nrf2 途径在 TCE 诱导的自身免疫中的联系。将雌性 MRL+/+ 小鼠分组，用 TCE、萝卜硫素 (SFN，一种抗氧化剂) 或 TCE+SFN (TCE，10mmol/kg，腹腔注射，每 4 天一次；SFN，8mg/kg，腹腔注射，每隔一天一次) 处理 6 周。TCE 暴露导致血清 4-羟基壬烯醛 (HNE)-蛋白加合物、HNE 特异性循环免疫复合物 (CIC) 和蛋白羰基的形成增加，这与血清抗核抗体 (ANA) 的显著增加有关。此外，用 HNE 修饰的蛋白孵育来自 TCE 处理的小鼠的脾细胞导致脾细胞增殖和细胞因子释放增加，这表现为细胞周期蛋白 D3、细胞周期蛋白依赖性激酶 6 (CDK6) 和磷酸化 pRb 的表达增加，以及白介素 6 (IL-6)、肿瘤坏死因子-α (TNF-α) 和干扰素-γ (INF-γ) 的释放增加。更重要的是，TCE 暴露导致脾中 TLR4、MyD88、IRAK4、NF-kB 的表达增加，Nrf2 和 HO-1 的表达减少。值得注意的是，SFN 补充不仅减弱了 TCE 诱导的 OS、TLR4 和 NF-kB 信号的上调以及 Nrf2 的下调，还降低了 ANA 水平。这些结果除了进一步支持 OS 的作用外，还表明 OS、TLR4 和 Nrf2 途径之间的相互作用导致了 TCE 介导的自身免疫反应。SFN 减弱 TCE 介导的自身免疫为涉及 OS 的 ADs 的预防和/或治疗策略提供了一个途径。
