脂氧素A4通过ERK1/2通路调控气道上皮细胞上皮间质转化

目的：研究脂氧素A4（LXA4）对气道上皮细胞上皮间质转化（EMT）和卵清蛋白（OVA）诱导的哮喘小鼠模型气道重塑的影响及其可能机制。方法：将BALB/c小鼠分为4组：对照组、OVA组、LXA4组和OVA+LXA4 组，HE和PAS染色观察肺组织病理改变。将BEAS-2B细胞分为6 组：对照组、白介素（IL）-4 组、IL-13组、转化生长因子β1（TGF-β1）组、IL-4/IL-13/TGF-β1联合刺激组和LXA4 预处理组。实时定量聚合酶链反应（RT-qPCR）检测α-平滑肌肌动蛋白（α-SMA）、E-钙黏附蛋白（E-cadherin）mRNA水平；Western blot检测α-SMA、E-cadherin及ERK1/2、pERK1/2蛋白表达水平。结果：小鼠体内实验中，与对照组相比，OVA诱导哮喘小鼠模型出现肺泡壁增厚、间质水肿、炎性细胞浸润和肺组织破坏，肺组织PAS染色强阳性，提示杯状细胞化生和气道黏液分泌增加，而LXA4预处理可以明显改善述OVA诱导的小鼠气道病变。BEAS-2B细胞实验中，TGF-β1组与对照组相比，细胞连接变得松散，细胞间隙增加，形态呈长梭形；IL-4/IL-13/TGF-β1联合刺激组较TGF-β1组细胞形态改变更为明显；与对照组相比，TGF-β1组细胞E-cadherin mRNA和蛋白表达显著降低，α-SMA mRNA和蛋白表达明显升高，pERK蛋白表达增加；与TGF-β1 组比，IL-4/IL-13/TGF-β1联合刺激组α-SMA mRNA和蛋白表达明显升高，E-cadherin mRNA和蛋白表达明显降低，pERK蛋白表达增加更为明显；而LXA4能抑制TGF-β1和IL-4、IL-13共刺激诱导的Beas 2B细胞α-SMA mRNA和蛋白表达升高，E-cadherin mRNA和蛋白表达降低以及pERK表达增加。结论：LXA4可以抑制OVA诱导哮喘小鼠的气道重塑。Th2源性细胞因子IL-4和IL-13提供的慢性炎症环境有利于TGF-β1诱导气道上皮细胞发生EMT。LXA4能抑制气道上皮细胞EMT，这一过程可能依赖于阻断ERK1/2磷酸化。

Lipoxin A4 regulates epithelial-mesenchymal transition in epithelial cell through inhibiting activation of ERK1/2 pathway

Objective: To investigate the effects of lipoxin A4 (LXA4) on transforming growth factor β1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) in BEAS-2B (human normal bronchial epithelial cell) and ovalbumin (OVA)-induced airway remodeling in asthmatic mice and its possible mechanism. Methods: The BALB/c mice were randomly divided into 4 groups: control group, OVA group, LXA4 group and OVA+ LXA4 group. The pathological changes of lung tissues were observed by HE and PAS staining. BEAS-2B cells were divided into 6 groups: control group, interleukin (IL)-4 group, IL-13 group, TGF-β1 group, IL-4/IL-13/TGF-β1 co-stimulation group and LXA4 pretreatment group. The mRNA expression of α-smooth muscle actin (α-SMA), E-cadherin were detected by quantitative real time PCR. α-SMA, E-cadherin, ERK1/2 and pERK1/2 protein expressions were measured by Western blot. Results: Compared with the control group, the lungs in themodel group exhibited observable lung histopathologic changes, including alveolar wall thickening, interstitial edema, inflammatory infiltration, hemorrhage, and lung tissue destruction. In addition, mice in the OVA group showed strong AB/PAS-positive staining in their bronchial epithelial tissues, which indicated goblet cell hyperplasia and mucus production, but LXA4 significantly improved the above-mentioned pathological changes.In BEAS-2B, compared with control group, cells treated with TGF-β1 for 72 hours became spindle-shaped, loosely attached, and cell intercellular spaces-enlarged. Cells stimulated by a combination of TGF-β1, IL-4 and IL-13 exhibited increased morphological alterations, compared with the TGF-β1 group. Compared with controlgroup, the expression of α-SMA mRNA and protein and pERK protein increased, while expression of E-cadherinmRNA and protein decreased in TGF-β1 group. α-SMA and pERK increased while E-cadherin decreased in theTGF-β1/IL-4/IL-13 co-stimulation group more significantly than the TGF-β1 group. Meanwhile, LXA4 inhibitedthe increase of TGF-β1, IL-4, IL-13 co-stimulation-induced α-SMA and the decrease of E-cadherin, and reducedERK phosphorylation in BEAS 2B cells. Conclusion: LXA4 could inhibit OVA-induced airway remodeling inasthma mouse models. Th2 cytokines IL-4 and IL-13 are condusive to EMT in BEAS-2B cells. LXA4 inhibitsEMT in airway epithelial cells, which may depend on the blocking of ERK1/2 pathway phosphorylation.