Ureña P, Herbelin A, Zingraff J, Lair M, Man N K, Descamps-Latscha B, Drüeke T
INSERM U 90, Hôpital Necker, Paris, France.
Nephrol Dial Transplant. 1992;7(1):16-28.
The possibility of endotoxin transfer across haemodialysis membranes remains a controversial issue. Additional concern has arisen because of the recent introduction in clinical practice of highly permeable, synthetic dialysis membranes and of bacteria-contaminated bicarbonate concentrate with potential short-term and long-term hazards for haemodialysis (HD) patients. Therefore, we performed experiments in an in-vitro dialysis recirculation system using three different types of HD membranes, namely standard regenerated cellulose (Cuprophan, CU), polyacrylonitrile AN-69 (PAN), and polysulphone F-60 (PS). When radiolabelled lipopolysaccharide (125I M-LPS) from E. coli, together with 10 micrograms/ml unlabelled LPS, was added to the recirculating solution in the dialysis compartment, radioactivity could be detected in the blood compartment after 15 min and increased progressively with time up to respectively 6.7% (CU), 10.3% (PAN), and 10.3% (PS) of initial activity on the dialysate side. The addition of albumin to the solution on the blood side led to a decreased permeability of radioactivity (7.3% vs 10.3%), compared to the absence of albumin (tested only for PS membrane). Furthermore, 73% of 125I M-LPS transferred across the PS membrane in the presence of albumin was TCA-precipitable. In contrast, free iodine (Na 125I) incubated in an albumin-containing solution did not precipitate with albumin after the addition of TCA (precipitation of only 0.6%). Moreover, kinetics of transmembranous transfer of Na-125I were strikingly different from that of 125I M-LPS. Analysis by the method of sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of the blood side solution, after LPS addition in the dialysis solution and 30 min of back-filtration, revealed the presence of several silver-stainable and autoradiographic bands of low-molecular-weight range, probably LPS fragments. Finally, the presence of LPS in the dialysate compartment led to a moderate increase in interleukin 1 (IL-1) and tumour necrosis factor alpha (TNF) concentrations in plasma as well as in monocyte culture supernatants after isolation from recirculating normal human whole blood exposed to CU, PAN, or PS membrane. In conclusion, our study provides evidence for the permeation of low-molecular-weight LPS subunits across cellulosic and non-cellulosic HD membranes. The clinical significance, if any, of such a transfer has, however, still to be demonstrated.
内毒素通过血液透析膜转移的可能性仍然是一个有争议的问题。由于临床实践中最近引入了高通透性的合成透析膜以及被细菌污染的碳酸氢盐浓缩液，这对血液透析（HD）患者存在潜在的短期和长期危害，因此引发了更多关注。所以，我们在体外透析循环系统中使用三种不同类型的血液透析膜进行了实验，即标准再生纤维素（铜仿膜，CU）、聚丙烯腈AN - 69（PAN）和聚砜F - 60（PS）。当将来自大肠杆菌的放射性标记脂多糖（125I M - LPS）与10微克/毫升未标记的LPS添加到透析隔室的循环溶液中时，15分钟后在血液隔室中可检测到放射性，并且随着时间的推移逐渐增加，直至分别达到透析液侧初始活性的6.7%（CU）、10.3%（PAN）和10.3%（PS）。与血液侧溶液中不存在白蛋白（仅针对PS膜进行测试）相比，向血液侧溶液中添加白蛋白导致放射性通透性降低（7.3%对10.3%）。此外，在白蛋白存在的情况下，通过PS膜转移的125I M - LPS中有73%可被三氯乙酸沉淀。相比之下，在含白蛋白的溶液中孵育的游离碘（Na 125I）在添加三氯乙酸后不会与白蛋白沉淀（沉淀率仅为0.6%）。而且，Na - 125I的跨膜转移动力学与125I M - LPS的跨膜转移动力学显著不同。在透析溶液中添加LPS并进行30分钟回滤后，通过十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS - PAGE）方法对血液侧溶液进行分析，发现存在几条低分子量范围的可被银染和放射自显影的条带，可能是LPS片段。最后，在透析隔室中存在LPS会导致从暴露于CU、PAN或PS膜的循环正常人全血中分离后，血浆以及单核细胞培养上清液中的白细胞介素1（IL - 1）和肿瘤坏死因子α（TNF）浓度适度增加。总之，我们的研究为低分子量LPS亚基通过纤维素和非纤维素血液透析膜的渗透提供了证据。然而，这种转移的临床意义（如果有的话）仍有待证实。
