Serum platelet-activating factor acetylhydrolase activity in long-term hemodialysis patients

Background: The platelet-activating factor acetylhydrolase (PAF-AH) catalyzes hydrolysis of the sn-2-ester bond of platelet-activating factor (PAF) and oxidized phospholipids on LDL that are structurally similar to PAF and that are closely associated with atherosclerosis. The aim of this study was to investigate the serum PAF-AH activity and its relation to lipid status in uremic patients under long-term hemodialysis and in control subjects, both from the Slavonski Brod area, Croatia, where a high prevalence Of endemic nephropathy was documented. Materials and Methods: The patient group included 75 uremic patients on long-term hemodialysis with polysulfone membranes. The control group comprised 70 age- and sex-matched, apparently healthy individuals, volunteer blood donors. PAF-AH activity was measured with the new automated spectrophotometric assay (Auto PAF-AH, Alfresa Pharma Corporation, Osaka, Japan). Cholesterol, triglycerides, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol were determined by standard methods used in medical biochemstry laboratories. Results: Serum PAF-AH measurements did not demonstrate a difference between men and women, and therefore common mean value was calculated (326 U/L). The mean of PAF-AH activity in serum of hemodialyzed patients (416 U/L) represented 128% (p < 0.001) of the control value. Serum PAF-AH activity correlated in the control group and the group of hemodialyzed uremic patients with total cholesterol (r=0.64, P < 0.001; r=0.40, p=0.001, respectively) and LDL-cholesterol (r=0.63, p < 0.001; r=0.27 p=0.024, respectively). PAF-AH activity was proportional to serum triglycerides only in the group of hemodialyzed uremic patients (r=0.23, p=0.049). Conclusion: We confirmed that serum PAF-AH activity was increased in hemodialyzed uremic patients probably as a compensatory response to degrade PAF-like oxidized phospholipids that are generated at inflammatory sites and to prevent the modification of LDL. We could also recommend the application of this new spectrophotometric method for further investigation of the role of serum PAF-AH activity in other clinical trials.