Callaghan Patrick J, Rybakovsky Elizabeth, Ferrick Bryan, Thomas Sunil, Mullin James M
Lankenau Institute for Medical Research, Wynnewood, PA, United States of America.
Department of Biomedical Engineering, Drexel University, Philadelphia, PA, United States of America.
PLoS One. 2020 Dec 10;15(12):e0242536. doi: 10.1371/journal.pone.0242536. eCollection 2020.
Retinoic acid (RA) has been shown to improve epithelial and endothelial barrier function and development and even suppress damage inflicted by inflammation on these barriers through regulating immune cell activity. This paper thus sought to determine whether RA could improve baseline barrier function and attenuate TNF-α-induced barrier leak in the human bronchial epithelial cell culture model, 16HBE14o- (16HBE). We show for the first time that RA increases baseline barrier function of these cell layers indicated by an 89% increase in transepithelial electrical resistance (TER) and 22% decrease in 14C-mannitol flux. A simultaneous, RA-induced 70% increase in claudin-4 attests to RA affecting the tight junctional (TJ) complex itself. RA was also effective in alleviating TNF-α-induced 16HBE barrier leak, attenuating 60% of the TNF-α-induced leak to 14C-mannitol and 80% of the leak to 14C-inulin. Interleukin-6-induced barrier leak was also reduced by RA. Treatment of 16HBE cell layers with TNF-α resulted in dramatic decrease in immunostaining for occludin and claudin-4, as well as a downward "band-shift" in occludin Western immunoblots. The presence of RA partially reversed TNF-α's effects on these select TJ proteins. Lastly, RA completely abrogated the TNF-α-induced increase in ERK-1,2 phosphorylation without significantly decreasing the TNF-driven increase in total ERK-1,2. This study suggests RA could be effective as a prophylactic agent in minimizing airway barrier leak and as a therapeutic in preventing leak triggered by inflammatory cascades. Given the growing literature suggesting a "cytokine storm" may be related to COVID-19 morbidity, RA may be a useful adjuvant for use with anti-viral therapies.
维甲酸(RA)已被证明可改善上皮和内皮屏障功能及发育,甚至通过调节免疫细胞活性来抑制炎症对这些屏障造成的损伤。因此,本文旨在确定RA是否能改善人支气管上皮细胞培养模型16HBE14o-(16HBE)中的基线屏障功能,并减轻肿瘤坏死因子-α(TNF-α)诱导的屏障渗漏。我们首次表明,RA可增加这些细胞层的基线屏障功能,表现为跨上皮电阻(TER)增加89%,14C-甘露醇通量降低22%。同时,RA诱导claudin-4增加70%,证明RA影响紧密连接(TJ)复合体本身。RA还能有效减轻TNF-α诱导的16HBE屏障渗漏,使TNF-α诱导的14C-甘露醇渗漏减少60%,14C-菊粉渗漏减少80%。RA也能减少白细胞介素-6诱导的屏障渗漏。用TNF-α处理16HBE细胞层导致闭合蛋白和claudin-4的免疫染色显著降低,以及闭合蛋白Western免疫印迹出现向下的“条带移位”。RA的存在部分逆转了TNF-α对这些特定TJ蛋白的影响。最后,RA完全消除了TNF-α诱导的细胞外信号调节激酶1,2(ERK-1,2)磷酸化增加,而没有显著降低TNF驱动的总ERK-1,2增加。这项研究表明,RA作为预防剂可有效减少气道屏障渗漏,作为治疗剂可预防炎症级联反应引发的渗漏。鉴于越来越多的文献表明“细胞因子风暴”可能与2019冠状病毒病(COVID-19)的发病有关,RA可能是抗病毒治疗的有用佐剂。