Hoyt D G, Mannix R J, Rusnak J M, Pitt B R, Lazo J S
Department of Pharmacology, University of Pittsburgh School of Medicine, Pennsylvania 15261, USA.
Am J Physiol. 1995 Aug;269(2 Pt 1):L171-7. doi: 10.1152/ajplung.1995.269.2.L171.
Lipopolysaccharide (LPS) causes direct pulmonary endothelial injury that can precipitate cell death. We investigated the ability of LPS to produce apoptosis in sheep pulmonary artery endothelial cells (SPAEC) grown in monolayer on plastic or collagen. When SPAEC were grown on plastic, LPS (100 ng/ml) caused internucleosomal DNA fragmentation (IDF) to 180- to 200-base pair ladders after 4 h. Higher-order chromatin damage, producing 50-kilobase DNA fragments, occurred within 2 h. Significant DNA strand breaks were seen in attached cells within 1 h incubation with > or = 1 ng LPS/ml, using in situ labeling by break extension (ISBE). DNA strand breakage in attached cells peaked after 2 h and remained elevated after 4 h. Detachment of SPAEC from the monolayer did not begin until 4 h. SPAEC cultured on collagen were protected from LPS-induced apoptosis; DNA damage measured by IDF, high-molecular-weight DNA fragmentation, and ISBE were suppressed. The protective effect of collagen was not due to inactivation of LPS. Thus LPS-induced apoptosis occurs in SPAEC after genotoxic damage and this process is suppressed by the extracellular matrix.
脂多糖（LPS）可导致直接的肺内皮损伤，进而引发细胞死亡。我们研究了LPS对在塑料或胶原蛋白上单层生长的绵羊肺动脉内皮细胞（SPAEC）产生凋亡的能力。当SPAEC在塑料上生长时，LPS（100 ng/ml）在4小时后导致核小体间DNA片段化（IDF）形成180至200碱基对的梯状条带。在2小时内出现了产生50千碱基DNA片段的高阶染色质损伤。使用断裂延伸原位标记（ISBE）法，在与≥1 ng LPS/ml孵育1小时内，贴壁细胞中可见明显的DNA链断裂。贴壁细胞中的DNA链断裂在2小时后达到峰值，并在4小时后仍保持升高。SPAEC从单层上脱落直到4小时才开始。在胶原蛋白上培养的SPAEC对LPS诱导的凋亡具有保护作用；通过IDF、高分子量DNA片段化和ISBE测量的DNA损伤均受到抑制。胶原蛋白的保护作用并非由于LPS的失活。因此，LPS诱导的凋亡在遗传毒性损伤后的SPAEC中发生，并且这一过程受到细胞外基质的抑制。
