Konrad Franziska M, Bury Annette, Schick Martin A, Ngamsri Kristian-Christos, Reutershan Jörg
Department of Anesthesiology and Intensive Care Medicine, University Hospital of Tübingen, Tübingen, Germany.
Department of Anesthesiology and Intensive Care Medicine, University Hospital of Würzburg, Würzburg, Germany.
PLoS One. 2015 Apr 24;10(4):e0121725. doi: 10.1371/journal.pone.0121725. eCollection 2015.
Acute pulmonary inflammation is characterized by migration of polymorphonuclear neutrophils (PMNs) into the different compartments of the lung, passing an endothelial and epithelial barrier. Recent studies showed evidence that phosphodiesterase (PDE)4-inhibitors stabilized endothelial cells. PDE4B and PDE4D subtypes play a pivotal role in inflammation, whereas blocking PDE4D is suspected to cause gastrointestinal side effects. We thought to investigate the particular role of the PDE4-inhibitors roflumilast and rolipram on lung epithelium. Acute pulmonary inflammation was induced by inhalation of LPS. PDE4-inhibitors were administered i.p. or nebulized after inflammation. The impact of PDE4-inhibitors on PMN migration was evaluated in vivo and in vitro. Microvascular permeability, cytokine levels, and PDE4B and PDE4D expression were analyzed. In vivo, both PDE4-inhibitors decreased transendothelial and transepithelial migration even when administered after inflammation, whereas roflumilast showed a superior effect compared to rolipram on the epithelium. Both inhibitors decreased TNFα, IL6, and CXCL2/3. CXCL1, the strong PMN chemoattractant secreted by the epithelium, was significantly more reduced by roflumilast. In vitro assays with human epithelium also emphasized the pivotal role of roflumilast on the epithelium. Additionally, LPS-induced stress fibers, an essential requirement for a direct migration of PMNs into the alveolar space, were predominantly reduced by roflumilast. Expression of PDE4B and PDE4D were both increased in the lungs by LPS, PDE4-inhibitors decreased mainly PDE4B. The topical administration of PDE4-inhibitors was also effective in curbing down PMN migration, further highlighting the clinical potential of these compounds. In pulmonary epithelial cells, both subtypes were found coexistent around the nucleus and the cytoplasm. In these epithelial cells, LPS increased PDE4B and, to a lesser extend, PDE4D, whereas the effect of the inhibitors was prominent on the PDE4B subtype. In conclusion, we determined the pivotal role of the PDE4-inhibitor roflumilast on lung epithelium and emphasized its main effect on PDE4B in hyperinflammation.
急性肺部炎症的特征是多形核中性粒细胞（PMN）迁移至肺的不同区域，穿过内皮和上皮屏障。最近的研究表明，磷酸二酯酶（PDE）4抑制剂可稳定内皮细胞。PDE4B和PDE4D亚型在炎症中起关键作用，而阻断PDE4D被怀疑会引起胃肠道副作用。我们想研究PDE4抑制剂罗氟司特和咯利普兰对肺上皮细胞的特殊作用。通过吸入脂多糖诱导急性肺部炎症。在炎症发生后，经腹腔注射或雾化给予PDE4抑制剂。在体内和体外评估PDE4抑制剂对PMN迁移的影响。分析微血管通透性、细胞因子水平以及PDE4B和PDE4D的表达。在体内，即使在炎症发生后给药，两种PDE4抑制剂均能减少经内皮和经上皮的迁移，而与咯利普兰相比，罗氟司特对上皮细胞显示出更优的效果。两种抑制剂均能降低肿瘤坏死因子α、白细胞介素6和CXCL2/3。上皮细胞分泌的强大PMN趋化因子CXCL1，被罗氟司特显著降低得更多。用人上皮细胞进行的体外试验也强调了罗氟司特对上皮细胞起关键作用。此外，脂多糖诱导的应激纤维是PMN直接迁移至肺泡腔的必要条件，主要被罗氟司特减少。脂多糖使肺中PDE4B和PDE4D的表达均增加，PDE4抑制剂主要降低PDE4B。局部应用PDE4抑制剂在抑制PMN迁移方面也有效，进一步突出了这些化合物的临床潜力。在肺上皮细胞中，两种亚型在细胞核和细胞质周围共存。在这些上皮细胞中，脂多糖增加PDE4B，并在较小程度上增加PDE4D，而抑制剂对PDE4B亚型的作用更为显著。总之，我们确定了PDE4抑制剂罗氟司特对肺上皮细胞的关键作用，并强调了其在炎症反应中对PDE4B的主要作用。
