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Anti-inflammatory properties of platelet-activating factor acetylhydrolase and reproduction

Platelet-activating factor acetylhydrolase (PAF-AH ; E.C. 3.1.1.47) is an anti-inflammatory and anti-oxidative enzyme which catalyses the hydrolysis of acetyl ester at the sn-2 position of the platelet-activating factor (PAF) as well as the PAF-like oxidatively fragmented phospholipids produced during oxidative stress. PAF-like compounds have similar structure to PAF and provoke the same acute phase responses. PAF is a bioactive phospholipid synthesized by a variety of mammalian cells. In addition to the activation of platelets, its first discovered physiological action, PAF also activates polymorphonuclear leukocytes and monocytes suggesting a pathophysiological role as a mediator of inflammation. On the other hand, PAF is an important mediator for physiological processes associated with reproduction such as ovulation, fertilization, implantation, fetal tissue development and the initiation of parturition. Since the events during ovulation are associated with inflammatory-like changes, PAF may influence on this process. To understand better the potential roles of PAF in the processes of reproduction, it is essential to have information on the variations of PAF-acetylhydrolase during the reproductive cycle and pregnancy. We investigated the PAF-AH activity as well as C-reactive protein concentrations during pregnancy and postpartum period in sera of 114 dairy cows divided to the first (n=21), second (n=17) and third trimester of pregnancy (n=10), early puerperium (1-15 days postpartum, n=23), late puerperium (16-30 days postpartum, n=27) and middle lactation (40-60 days postpartum, n=16). PAF-AH activity was measured by the spectrophotometric assay (Auto PAF-AH, Azwell Inc, Osaka, Japan) while the C-reactive protein concentration was determined by the latex-enhanced immunoturbidimetric assay kit (Full range CRP, Randox Laboratories Ltd., Ardmore, UK). The statistical analysis was provided by Mann-Whitney rank sum-test using SigmaStat 3.0 (SPSS Inc., Chicago, Illinois, USA). Results are presented as the median values and the values P<0.05 are considered statistically significant. A significantly lower PAF-AH activity was found in late pregnancy (140 U/L) compared to the first (234 U/L) and the second trimester of pregnancy (210 U/L). Moreover, there was significantly lower PAF-AH activity in the both early and late puerperium (131 U/L, respectively) compared to the late postpartum period (middle lactation ; 182 U/L). C-reactive protein concentration was significantly lower during the second (2.77 mg/L) and the third trimester of pregnancy (2.29 mg/L) than in the first trimester of pregnancy (3.80 mg/L). There was a significantly lower C-reactive protein concentration in the early puerperium (1.63 mg/L) compared to the late puerperium and middle lactation (2.87 and 3.48 mg/L, respectively). A statistically significant positive correlation was observed between PAF-AH activity and CRP concentration in the late puerperium and middle lactation (r=0.457, P=0.0165 and r=0.810, P=0.00014, respectively). Results show lower PAF-AH activity during the late stage of pregnancy and after delivery with an increased trend in the postpartum period indicating the role of the enzyme in the regulation of PAF concentration during reproduction. In addition, a significant correlation between PAF-AH activity and CRP concentration during lactation shows that serum PAF-AH activity could be useful marker to monitor inflammation.

PAF-AH; CRP; inflammation; reproduction; cows

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