Yang Xudong, Sheares Karen K K, Davie N, Upton Paul D, Taylor Graham W, Horsley Jo, Wharton John, Morrell Nicholas W
Department of Medicine, University of Cambridge School of Clinical Medicine, Addenbrooke's Hospitals, Cambridge, UK.
Am J Respir Cell Mol Biol. 2002 Dec;27(6):688-96. doi: 10.1165/rcmb.2002-0067OC.
Chronic hypoxia-induced pulmonary hypertension results partly from proliferation of smooth muscle cells in small peripheral pulmonary arteries. Therefore, we examined the effect of hypoxia on growth of pulmonary artery smooth muscle cells (PASMCs) from human distal pulmonary arteries. Initial studies identified that serum-induced proliferation of explant-derived PASMCs was inhibited under hypoxic conditions (3-4 kPa in medium). However, selection of hypoxia-stimulated cells was achieved by culturing cells at low density under conditions of prolonged hypoxia (1-2 wk). In hypoxia-inhibited and -stimulated cells, Western blotting revealed hypoxic induction of cyclooxygenase (COX)-2, which was dependent on the activation of p38(MAPK), but not COX-1, inducible nitric oxide synthase (iNOS), or hemoxygenase-1 (HO-1). Hypoxic induction of COX-2 was also observed in the media of pulmonary arteries in lung organ culture. Hypoxia induced a 4- to 5-fold increase (P < 0.001) in prostaglandin (PG)E(2), PGD(2), PGF(2alpha), and 6-keto-PGF(1alpha) release from PASMCs. Hypoxic inhibition of proliferation was attenuated by incubation with indomethacin (10 micro M), or the COX-2 antagonist, NS398 (10 micro M), but not by the COX-1 antagonist, valeryl salicylate (0.5 mM). In conclusion, we have isolated cells from human peripheral pulmonary arteries that are either inhibited or stimulated by culture under hypoxic conditions. In both cell types hypoxia modulates cell proliferation by induction of COX-2 and production of antiproliferative prostaglandins. Induction of COX-2 may contribute to the inhibition of hypoxia-induced pulmonary vascular remodeling.
慢性缺氧诱导的肺动脉高压部分源于外周小肺动脉平滑肌细胞的增殖。因此，我们研究了缺氧对人远端肺动脉平滑肌细胞（PASMCs）生长的影响。初步研究发现，在缺氧条件下（培养基中3 - 4 kPa），血清诱导的外植体来源的PASMCs增殖受到抑制。然而，通过在长期缺氧条件下（1 - 2周）低密度培养细胞，实现了对缺氧刺激细胞的筛选。在缺氧抑制和刺激的细胞中，蛋白质免疫印迹法显示缺氧诱导环氧化酶（COX）-2，这依赖于p38（丝裂原活化蛋白激酶）的激活，但不依赖于COX-1、诱导型一氧化氮合酶（iNOS）或血红素加氧酶-1（HO-1）。在肺器官培养的肺动脉培养基中也观察到了COX-2的缺氧诱导。缺氧使PASMCs中前列腺素（PG）E2、PGD2、PGF2α和6-酮-PGF1α的释放增加了4至5倍（P < 0.001）。用吲哚美辛（10 μM）或COX-2拮抗剂NS398（10 μM）孵育可减轻缺氧对增殖的抑制作用，但COX-1拮抗剂戊酰水杨酸（0.5 mM）则无此作用。总之，我们从人外周肺动脉中分离出了在缺氧条件下培养时受到抑制或刺激的细胞。在这两种细胞类型中，缺氧均通过诱导COX-2和产生抗增殖前列腺素来调节细胞增殖。COX-2的诱导可能有助于抑制缺氧诱导的肺血管重塑。
