Lau B H, Li L, Yoon P
Department of Microbiology, School of Medicine, Loma Linda University, CA 92350.
Life Sci. 1993;52(22):1787-96. doi: 10.1016/0024-3205(93)90468-i.
Oxidant injury of the vascular endothelium is considered an early event in the pathogenesis of atherosclerosis. In this study, the antioxidant effect of a 6-kDa thymic peptide (TP), isolated from calf thymus, was investigated in vitro using vascular endothelial cells. Confluent monolayers of bovine pulmonary artery endothelial cells (PAEC) were preincubated with different concentrations of TP for 24 h, washed, and then exposed to hydrogen peroxide (H2O2) for 2 or 4 h. Cell injury was assessed by measuring cell viability with methylthiazol tetrazolium (MTT) assay, and by determining the release of intracellular lactate dehydrogenase (LDH). Lipid peroxidation products of PAEC were monitored as malondialdehyde (MDA) with a thiobarbituric acid fluorometric assay. H2O2 (120 or 240 microM) incubated with PAEC decreased cell viability, increased LDH release, and elevated MDA production. Preincubation of PAEC with TP (25-150 micrograms/ml) before H2O2 exposure significantly increased cell viability, decreased LDH release, and reduced MDA production. These results demonstrate that TP can protect vascular endothelial cells from oxidant injury. The data thus suggest that TP may be useful for the prevention and/or treatment of atherosclerosis, and further suggest that immune modulating agents may directly or indirectly influence the functions of vascular endothelium.
血管内皮的氧化损伤被认为是动脉粥样硬化发病机制中的早期事件。在本研究中，使用血管内皮细胞在体外研究了从小牛胸腺分离的一种6 kDa胸腺肽（TP）的抗氧化作用。将汇合的牛肺动脉内皮细胞（PAEC）单层与不同浓度的TP预孵育24小时，洗涤后，再暴露于过氧化氢（H2O2）中2或4小时。通过用甲基噻唑四氮唑（MTT）法测量细胞活力以及测定细胞内乳酸脱氢酶（LDH）的释放来评估细胞损伤。用硫代巴比妥酸荧光法将PAEC的脂质过氧化产物作为丙二醛（MDA）进行监测。与PAEC孵育的H2O2（120或240 microM）降低了细胞活力，增加了LDH释放，并提高了MDA生成。在H2O2暴露前用TP（25 - 150微克/毫升）预孵育PAEC可显著提高细胞活力，降低LDH释放，并减少MDA生成。这些结果表明TP可以保护血管内皮细胞免受氧化损伤。因此，数据表明TP可能对动脉粥样硬化的预防和/或治疗有用，并且进一步表明免疫调节剂可能直接或间接影响血管内皮的功能。
