Wratten M L, Tetta C, De Smet R, Neri R, Sereni L, Camussi G, Vanholder R
Department of Clinical Research, Bellco SpA, Mirandola, Italy.
Blood Purif. 1999;17(2-3):134-41. doi: 10.1159/000014385.
Several studies have suggested that uremic toxins may adversely affect phagocytic leukocytes of chronic renal failure patients. Platelet-activating factor (PAF) is produced by phagocytic leukocytes and is a potent mediator of inflammation which is produced by leukocytes upon appropriate stimulation.
We added uremic or normal ultrafiltrate, ultrafiltrate fractionated by reverse phase HPLC or compounds eluting at the same retention time as the fractionated ultrafiltrate, to normal leukocytes. Complement-coated baker's yeast spores were added to stimulate phagocytosis. Total PAF was purified by thin layer chromatography and quantified by bioassay on rabbit platelets. The activities of two enzymes involved in the synthesis of PAF, phospholipase A2 (PLA2) and acetyltransferase, were measured in the presence of fractionated ultrafiltrate.
Ultrafiltrate from both healthy and uremic subjects inhibited PAF synthesis, but the inhibitory effect was more substantial for uremic subjects. Ultrafiltrate fractionated by HPLC showed high PAF inhibition for late eluting hydrophobic fractions. Addition of phenol or p-cresol, two uremic toxins with similar elution pattern as the late fractions, also inhibited PAF synthesis. The activity of PLA2 and acetyltransferase was decreased in the presence of uremic ultrafiltrate.
We observed that uremic ultrafiltrate inhibits PAF synthesis upon stimulation with complement coated baker's yeast spores. The decrease in total PAF synthesis appears to be associated with an inhibition of phospholipase A2 and acetyltransferase activity, enzymes involved in the remodelling pathway for PAF synthesis.
多项研究表明，尿毒症毒素可能会对慢性肾衰竭患者的吞噬性白细胞产生不利影响。血小板活化因子（PAF）由吞噬性白细胞产生，是一种强效炎症介质，在适当刺激下由白细胞产生。
我们将尿毒症或正常超滤物、经反相高效液相色谱法分离的超滤物组分或与分离后的超滤物在相同保留时间洗脱的化合物添加到正常白细胞中。添加经补体包被的面包酵母孢子以刺激吞噬作用。通过薄层层析法纯化总PAF，并通过对兔血小板的生物测定进行定量。在存在分离后的超滤物的情况下，测量参与PAF合成的两种酶，即磷脂酶A2（PLA2）和乙酰转移酶的活性。
健康受试者和尿毒症受试者的超滤物均抑制PAF合成，但对尿毒症受试者的抑制作用更强。经高效液相色谱法分离的超滤物对后期洗脱的疏水组分显示出较高的PAF抑制作用。添加苯酚或对甲酚这两种与后期组分洗脱模式相似的尿毒症毒素，也抑制了PAF合成。在存在尿毒症超滤物的情况下，PLA2和乙酰转移酶的活性降低。
我们观察到，尿毒症超滤物在经补体包被的面包酵母孢子刺激后会抑制PAF合成。总PAF合成的减少似乎与磷脂酶A2和乙酰转移酶活性的抑制有关，这两种酶参与PAF合成的重塑途径。
