Heidenreich S, Schmidt M, Bachmann J, Harrach B
Department of Medicine, University of Münster, Germany.
Kidney Int. 1996 Mar;49(3):792-9. doi: 10.1038/ki.1996.110.
Monocyte apoptosis in vitro was studied in patients on long-term hemodialysis, CAPD, and in predialytic uremia to gain insight into the high susceptibility of these patients to infections. Monocytes from dialysis and control subjects were cultured for 24 to 120 hours in vitro to analyze the level and progression of DNA fragmentation as a hallmark of apoptosis. After an incubation time of 48 hours chromatin fragmentation of 48.5 +/- 7.7% was found in monocytes from dialysis patients, which significantly exceeded DNA fragmentation of control monocytes (23.1 +/- 9.1%; N = 12; P < 0.01). Over longer culture periods of up to 5 days, a continuous progression of apoptosis occurred with a similar slope of percent DNA fragmentation in the two studied groups. Monocyte viability was > 95% both in the dialysis and control group. Hemodialysis patients also showed elevated levels of monocyte apoptosis when programmed cell death was evaluated by transmission electron microscopy or DNA electrophoresis of cleaved chromatin. To test the functional relevance of monocyte apoptosis, a significant reduction of Candida growth inhibition by monocytes of dialysis patients was found with a strong linkage between percentage of DNA fragmentation and impaired microbicidal capacity. Monocytes obtained from patients after the hemodialysis session and from CAPD patients showed normal DNA fragmentation levels similar to controls. Differences of monocyte apoptosis between patients on cuprophane and high-flux polysulphone dialysis were not found. Uremic predialytic patients also exerted an increased monocyte DNA fragmentation of 44.2 +/- 1.5% (N = 7; P < 0.05 compared to controls). Enhanced apoptosis of uremic monocytes was accompanied by a reduced formation of TNF-alpha over 48 hours, revealing a significant negative correlation between chromatin fragmentation and monokine synthesis. Supplementation of monocyte cultures from dialysis patients with exogenous TNF-alpha turned increased apoptosis back to baseline levels, suggesting that inflammatory mediators may modulate monocyte senescence. In summary, the elevated degree of monocyte apoptosis in end-stage renal failure may contribute to the impaired cellular host defense seen in these patients.
对长期血液透析患者、持续性不卧床腹膜透析（CAPD）患者以及透析前尿毒症患者的单核细胞体外凋亡情况进行了研究，以深入了解这些患者对感染的高易感性。将透析患者和对照受试者的单核细胞在体外培养24至120小时，以分析作为凋亡标志的DNA片段化水平和进程。孵育48小时后，发现透析患者单核细胞的染色质片段化率为48.5±7.7%，显著超过对照单核细胞的DNA片段化率（23.1±9.1%；N = 12；P < 0.01）。在长达5天的更长培养期内，两个研究组的凋亡持续进展，DNA片段化百分比的斜率相似。透析组和对照组的单核细胞活力均> 95%。当通过透射电子显微镜或裂解染色质的DNA电泳评估程序性细胞死亡时，血液透析患者的单核细胞凋亡水平也升高。为了测试单核细胞凋亡的功能相关性，发现透析患者单核细胞对念珠菌生长抑制的显著降低，且DNA片段化百分比与杀菌能力受损之间存在强关联。血液透析 session 后患者和CAPD患者的单核细胞DNA片段化水平与对照组相似。未发现铜仿膜透析患者和高通量聚砜膜透析患者之间单核细胞凋亡的差异。透析前尿毒症患者的单核细胞DNA片段化也增加，为44.2±1.5%（N = 7；与对照组相比P < 0.05）。尿毒症单核细胞凋亡增强伴随着48小时内肿瘤坏死因子-α（TNF-α）形成减少，表明染色质片段化与单核因子合成之间存在显著负相关。用外源性TNF-α补充透析患者的单核细胞培养物可使增加的凋亡恢复到基线水平，表明炎症介质可能调节单核细胞衰老。总之，终末期肾衰竭中单核细胞凋亡程度升高可能导致这些患者细胞宿主防御受损。
