Perianayagam M C, Murray S L, Balakrishnan V S, Guo D, King A J, Pereira B J, Jaber B L
Tupper Research Institute, Department of Medicine, New England Medical Center, Boston, MA 02111, USA.
J Lab Clin Med. 2000 Oct;136(4):320-7. doi: 10.1067/mlc.2000.109318.
Apoptosis, or programmed cell death, is an active form of cell death that is initiated by a number of stimuli and is intricately regulated. Apoptosis in both excessive and reduced amounts has pathophysiologic implications. Accelerated programmed cell death has been observed in leukocytes among patients with chronic renal failure (CRF). This has been ascribed in part to the retention of uremic toxins. The Fas/Fas ligand (FasL) system is a key regulatory apoptotic pathway. Membrane-bound Fas is a cell-surface receptor that transduces apoptosis after interaction with membrane-bound or soluble FasL (sFasL). By contrast, soluble Fas (sFas) binds sFasL and inhibits its activity. In an attempt to examine the balance between these soluble factors in uremia, we measured soluble sFas and sFasL levels in the serum of healthy control subjects and patients with various degrees of CRF and examined the distribution of the various molecular mass fractions of these proteins in uremic serum. In brief, serum was obtained from 15 healthy volunteers, 17 patients with CRF, 11 patients undergoing maintenance hemodialysis (HD), and 7 patients undergoing peritoneal dialysis (PD). Serum sFas and sFasL were measured by enzyme-linked immunosorbent assay, and their molecular distribution was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by immunoblot. Compared with results in healthy control subjects, sFas levels were significantly higher in patients with CRF and in patients undergoing dialysis. There was a significant inverse correlation between sFas levels and creatinine clearance. Serum sFasL levels were not different among the four groups. However, the sFas-to-sFasL ratio was significantly lower in healthy control subjects as compared with patients with CRF and patients undergoing dialysis. Immunoblots and densitometric analyses of sFas and sFasL depicted a known 48-kd sFas, a known 27-kd sFasL, and a 60-kd sFas-sFasL protein aggregate signal. In conclusion, serum sFas levels are increased in patients with various degrees of CRF and may bind circulating sFasL, thereby minimizing mediation of cellular apoptosis.
细胞凋亡，即程序性细胞死亡，是一种由多种刺激引发并受到复杂调控的主动形式的细胞死亡。细胞凋亡数量过多或过少均具有病理生理学意义。在慢性肾衰竭（CRF）患者的白细胞中观察到程序性细胞死亡加速。这部分归因于尿毒症毒素的潴留。Fas/Fas配体（FasL）系统是关键的凋亡调控途径。膜结合型Fas是一种细胞表面受体，与膜结合型或可溶性FasL（sFasL）相互作用后可转导细胞凋亡。相比之下，可溶性Fas（sFas）可结合sFasL并抑制其活性。为了研究尿毒症中这些可溶性因子之间的平衡，我们检测了健康对照受试者以及不同程度CRF患者血清中的可溶性sFas和sFasL水平，并研究了这些蛋白质在尿毒症血清中不同分子量组分的分布情况。简而言之，我们采集了15名健康志愿者、17名CRF患者、11名维持性血液透析（HD）患者和7名腹膜透析（PD）患者的血清。采用酶联免疫吸附测定法检测血清sFas和sFasL水平，并通过十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳及免疫印迹法确定其分子分布。与健康对照受试者的结果相比，CRF患者和透析患者的sFas水平显著更高。sFas水平与肌酐清除率之间存在显著负相关。四组之间的血清sFasL水平无差异。然而，与CRF患者和透析患者相比，健康对照受试者的sFas与sFasL比值显著更低。sFas和sFasL的免疫印迹及密度分析显示出已知的48-kd sFas、已知的27-kd sFasL以及60-kd sFas-sFasL蛋白聚集体信号。总之，不同程度CRF患者的血清sFas水平升高，可能会结合循环中的sFasL，从而使细胞凋亡的介导作用降至最低。
