Heat shock protein (HSP) 20 is a molecular chaperone that exerts multiple protective functions in various kinds of tissues. However, the expression of HSP20 and its specific functions in airway epithelial cells (AECs) remain elusive. In current study, we first confirmed the inducible expression of HSP20 in mouse AECs and in a human bronchial epithelial cell line BEAS-2B cells, under different oxidant stressors. Then by establishing a HSP20-abundant mouse model with repeated low-level-ozone exposures and stimulating this model with a single high-level ozone exposure, we found that the HSP20 abundance along with its enhanced phosphorylation potentially contributed to the alleviation of oxidative injuries, evidenced by the decreases in the bodyweight reduction, the BAL neutrophil accumulation, the AECs shedding, and the BAL concentrations of albumin and E-cadherin. The biological function of HSP20 and its molecular mechanisms were further investigated in BEAS-2B cells that were transfected with HSP20-, unphosphorylatable HSP20(Ala) or empty vector plasmids prior to the stimulation of H2O2, of which its oxidant capacity has been proved to be similar with those of ozone in an air–liquid culture system. We found that the H2O2-induced intracellular ROS level and the early cell apoptosis were attenuated in the HSP20- but not HSP20(Ala)- transfected cells. The intracellular expression of NQO-1 (mRNA and protein) and the intranuclear content of Nrf2 were significantly increased in the HSP20- transfected cells but not in the HSP20(Ala)- and empty vector-transfected cells after the stimulation of H2O2. The inducible expression of HSP20 in AECs by oxidative stress exerts protective roles against oxidative damages, which may involve the activation of the Nrf2-NQO-1 pathway.

中文翻译：

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热休克蛋白 20 的诱导表达可保护气道上皮细胞免受涉及 Nrf2-NQO-1 通路的氧化损伤

热休克蛋白（HSP）20是一种分子伴侣，在多种组织中发挥多种保护功能。然而，HSP20 在气道上皮细胞 (AEC) 中的表达及其具体功能仍然不清楚。在当前的研究中，我们首先证实了在不同的氧化应激源下，小鼠AEC和人支气管上皮细胞系BEAS-2B细胞中HSP20的诱导表达。然后，通过重复低水平臭氧暴露建立HSP20丰富的小鼠模型，并用单次高水平臭氧暴露刺激该模型，我们发现HSP20丰度及其增强的磷酸化可能有助于减轻氧化损伤，体重减少、BAL 中性粒细胞积累、AEC 脱落以及 BAL 中白蛋白和 E-钙粘蛋白浓度的降低证明了这一点。在H2O2刺激前转染HSP20-、不可磷酸化的HSP20(Ala)或空载体质粒的BEAS-2B细胞中进一步研究了HSP20的生物学功能及其分子机制，其氧化能力已被证明与气液培养系统中的臭氧类似。我们发现 H2O2 诱导的细胞内 ROS 水平和早期细胞凋亡在 HSP20 转染细胞中减弱，但在 HSP20(Ala) 转染细胞中没有减弱。H2O2刺激后，HSP20转染细胞中NQO-1（mRNA和蛋白）的胞内表达（mRNA和蛋白）和核内Nrf2含量显着增加，但HSP20（Ala）和空载体转染细胞中则没有显着增加。氧化应激诱导 AEC 中 HSP20 的表达，发挥抗氧化损伤的保护作用，这可能涉及 Nrf2-NQO-1 通路的激活。