Ma T Y, Pedram A
Department of Medicine, Department of Veterans Affairs Medical Center, Long Beach, California 90822, USA.
J Cell Physiol. 1996 May;167(2):204-12. doi: 10.1002/(SICI)1097-4652(199605)167:2<204::AID-JCP3>3.0.CO;2-T.
Prostaglandins prevent gastrointestinal mucosal injury and promote healing following mucosal injury by various noxious agents. Preservation or repair of microvascular function appears to be crucial in these processes. The processes involved in prostaglandin-mediated repair and preservation of endothelial function are unclear. In the present study, we investigated the role of prostaglandins on endothelial paracellular barrier function using the filter-grown bovine aortic endothelial cell monolayers. Endothelial paracellular barrier function as assessed using a paracellular marker, mannitol. Prostaglandin analogs 16,16-dimethyl prostaglandin E2 (DMPGE2) and prostaglandin I2 (PGI2) caused an enhancement of endothelial monolayer paracellular barrier function as evidenced by a dose-dependent decrease in endothelial paracellular permeability. DMPGE2 induced enhancement of endothelial paracellular barrier function correlated directly with increasing intracellular cAMP levels. Agents which increase intracellular cAMP levels at different stages of cAMP amplification cascade including phosphodiesterase inhibitor (3-isobutyl-1 methylxanthine [IBMX]), membrane permeable cAMP (8-bromo cAMP), and adenylate cyclase activators (isoproterenol and forskolin) also produced enhancement in endothelial paracellular barrier function. DMPGE2 enhancement of paracellular barrier function correlated with dense accumulation of actin microfilaments near the intercellular junctions. IBMX, isoproterenol, forskolin, and 8-bromo cAMP also produced similar changes in endothelial actin microfilaments. Cytochalasin B prevented the DMPGE2 enhancement of paracellular barrier function. Indomethacin (INDO), a cyclooxygenase inhibitor, caused a dose-dependent increase in endothelial paracellular permeability. Pharmacologic doses of INDO resulted in condensation and disruption of actin microfilaments with formation of large paracellular openings or gaps between the adjacent cells. Pretreatment of endothelial monolayers with DMPGE2 prevented INDO-induced disturbance of actin microfilaments and paracellular barrier function. IBMX, isoproterenol, forskolin, and 8-bromo cAMP also prevented INDO-induced changes in actin microfilaments and paracellular barrier function. These findings indicate that DMPGE2 has a paracellular barrier enhancing effect on filter-grown endothelial monolayers. This effect appears to be mediated through intracellular cAMP and actin microfilaments.
前列腺素可预防胃肠道黏膜损伤，并促进黏膜在受到各种有害因子损伤后的愈合。微血管功能的维持或修复在这些过程中似乎至关重要。前列腺素介导的内皮功能修复和维持所涉及的过程尚不清楚。在本研究中，我们使用滤器培养的牛主动脉内皮细胞单层，研究了前列腺素对内皮细胞旁细胞屏障功能的作用。内皮细胞旁细胞屏障功能通过细胞旁标志物甘露醇进行评估。前列腺素类似物16,16-二甲基前列腺素E2（DMPGE2）和前列腺素I2（PGI2）可增强内皮细胞单层的旁细胞屏障功能，内皮细胞旁细胞通透性呈剂量依赖性降低即证明了这一点。DMPGE2诱导的内皮细胞旁细胞屏障功能增强与细胞内cAMP水平升高直接相关。在cAMP放大级联反应的不同阶段增加细胞内cAMP水平的试剂，包括磷酸二酯酶抑制剂（3-异丁基-1-甲基黄嘌呤[IBMX]）、膜通透性cAMP（8-溴-cAMP）以及腺苷酸环化酶激活剂（异丙肾上腺素和福斯可林），也可增强内皮细胞旁细胞屏障功能。DMPGE2对旁细胞屏障功能的增强作用与细胞间连接处附近肌动蛋白微丝的密集积累相关。IBMX、异丙肾上腺素、福斯可林和8-溴-cAMP在内皮细胞肌动蛋白微丝中也产生了类似的变化。细胞松弛素B可阻止DMPGE2对旁细胞屏障功能的增强作用。环氧化酶抑制剂吲哚美辛（INDO）可导致内皮细胞旁细胞通透性呈剂量依赖性增加。药理剂量的INDO可导致肌动蛋白微丝凝聚和破坏，相邻细胞之间形成大的细胞旁开口或间隙。用DMPGE2预处理内皮细胞单层可防止INDO诱导的肌动蛋白微丝和旁细胞屏障功能紊乱。IBMX、异丙肾上腺素、福斯可林和8-溴-cAMP也可防止INDO诱导的肌动蛋白微丝和旁细胞屏障功能变化。这些发现表明，DMPGE2对滤器培养的内皮细胞单层具有细胞旁屏障增强作用。这种作用似乎是通过细胞内cAMP和肌动蛋白微丝介导的。
