Ozone injury to alveolar epithelium in vitro does not reflect loss of antioxidant defenses.
Ozone injury to alveolar epithelium in vitro does not reflect loss of antioxidant defenses.
复制标题
体外臭氧对肺泡上皮的损伤并不反映抗氧化防御能力的丧失。
DOI：
10.1006/taap.1994.1049
复制
发表时间：
1994
影响因子：
3.8
通讯作者：
Plopper,CG
中科院分区：
文献类型：
--
作者：
Cheek,JM;Buckpitt,AR;Li,C;Tarkington,BK;Plopper,CG
本研究的目的是通过评价（1）上皮屏障功能、（2）细胞抗氧化防御的稳定性和（3）肺泡上皮屏障特性对臭氧暴露的反应，使用无血清培养基中维持的肺泡II型细胞原代培养物表征氧化剂气体毒性的体外模型。抗氧化酶活性和谷胱甘肽水平测定大鼠II型细胞，新鲜分离，培养1天的血清补充培养基中，随后生长在无血清的营养培养基。在原代培养第4天测量峰值生物电特性后，将肺泡上皮单层暴露于不同浓度和暴露时间的臭氧中。臭氧引起的单层生物电特性的改变和细胞组织的损伤被用来评估氧化损伤。臭氧暴露的主要影响是单层渗透性的剂量依赖性增加，这是由于细胞间连接的损伤和/或上皮完整性的丧失。广泛和持续的渗透性增加与上皮降解的焦点区域相关。臭氧损伤肺泡上皮细胞在体外的局灶性表明，个别细胞对氧化应激的敏感性可能占屏障功能的整体递减。然而，这种敏感性不会导致与细胞培养相关的抗氧化防御的整体损失，因为这些单层（当在无血清培养基中培养时）保持其抗氧化酶活性和谷胱甘肽含量在新鲜分离的细胞中发现的水平。我们的结论是，这些单层细胞在体外对臭氧损伤的敏感性反映了细胞膜上氧化应激相对于细胞内抗氧化防御的不成比例的程度，即，细胞对氧化损伤的敏感性可能取决于细胞表面积与其细胞质体积的比率。
The objective of this study was to characterize an in vitro model of oxidant gas toxicity, using primary cultures of alveolar type II cells maintained in serum-free medium, by evaluating (1) epithelial barrier function, (2) the stability of cellular antioxidant defenses, and (3) the response of alveolar epithelial barrier properties to ozone exposure. Antioxidant enzyme activities and glutathione levels were measured in rat type II cells that were freshly isolated, cultured for 1 day in serum-supplemented medium, and subsequently grown in serum-free nutrient medium. After measurement of peak bioelectric properties on Day 4 in primary culture, alveolar epithelial monolayers were exposed to ozone at various concentrations and lengths of exposure. Ozone-induced alterations in monolayer bioelectric properties and impairment of cellular organization were used to evaluate oxidant injury. The primary effect of ozone exposure was a dose-dependent increase in monolayer permeability, which resulted from damage to intercellular junctions and/or loss of epithelial integrity. Extensive and persistent permeability increases correlated with focal areas of epithelial degradation. The focal nature of ozone injury to alveolar epithelium in vitro suggests that individual cell susceptibility to oxidant stress may account for the overall decrement in barrier function. However, this sensitivity does not result from overall loss of antioxidant defenses associated with cell culture, as these monolayers (when cultured in serum-free medium) maintained their antioxidant enzyme activities and glutathione content at levels found in freshly isolated cells. We conclude that the sensitivity of these monolayers to ozone injury in vitro reflects a disproportionate degree of oxidant stress on cell membranes relative to intracellular antioxidant defenses, i.e., cellular susceptibility to oxidant injury may depend on the ratio of the surface area of the cell to its cytoplasmic volume.