PAF levels and PAF-AH activities in placentas from normal and preeclamptic pregnancies

Role of Platelet Activating Factor as a Mediator of Inflammatory Diseases and Preterm Delivery

Nearly 70% of preterm deliveries occur spontaneously, and the clinical pathways involved include preterm labor and preterm premature rupture of membranes. Prediction of preterm delivery is considered crucial due to the significant effects of preterm birth on health and the economy at both the personal and community levels. Although similar inflammatory processes occur in both term and preterm delivery, the premature activation of these processes or exaggerated inflammatory response triggered by infection or sterile factors leads to preterm delivery. Platelet activating factor (PAF) is a phosphoglycerylether lipid mediator of inflammation that is implicated in infections, cancers, and various chronic diseases and disorders including cardiovascular, renal, cerebrovascular, and central nervous system diseases. In gestational tissues, PAF mediates the inflammatory pathways that stimulate the effector mechanisms of labor, including myometrial contraction, cervical dilation, and fetal membrane rupture. Women with preterm labor and preterm premature rupture of membranes have increased levels of PAF in their amniotic fluid. In mice, the intrauterine or intraperitoneal administration of carbamyl PAF activates inflammation in gestational tissues, thereby eliciting preterm delivery. This review summarizes recent research on PAF as an important inflammatory mediator in preterm delivery and in other inflammatory disorders, highlighting its potential value for prediction, intervention, and prevention of these diseases.

Fetal High-Density Lipoproteins: Current Knowledge on Particle Metabolism, Composition and Function in Health and Disease

Cholesterol and other lipids carried by lipoproteins play an indispensable role in fetal development. Recent evidence suggests that maternally derived high-density lipoprotein (HDL) differs from fetal HDL with respect to its proteome, size, and function. Compared to the HDL of adults, fetal HDL is the major carrier of cholesterol and has a unique composition that implies other physiological functions. Fetal HDL is enriched in apolipoprotein E, which binds with high affinity to the low-density lipoprotein receptor. Thus, it appears that a primary function of fetal HDL is the transport of cholesterol to tissues as is accomplished by low-density lipoproteins in adults. The fetal HDL-associated bioactive sphingolipid sphingosine-1-phosphate shows strong vasoprotective effects at the fetoplacental vasculature. Moreover, lipoprotein-associated phospholipase A2 carried by fetal-HDL exerts anti-oxidative and athero-protective functions on the fetoplacental endothelium. Notably, the mass and activity of HDL-associated paraoxonase 1 are about 5-fold lower in the fetus, accompanied by an attenuation of anti-oxidative activity of fetal HDL. Cholesteryl ester transfer protein activity is reduced in fetal circulation despite similar amounts of the enzyme in maternal and fetal serum. This review summarizes the current knowledge on fetal HDL as a potential vasoprotective lipoprotein during fetal development. We also provide an overview of whether and how the protective functionalities of HDL are impaired in pregnancy-related syndromes such as pre-eclampsia or gestational diabetes mellitus.

Evaluation of maternal plasma platelet activating factor acetylhydrolase activity and mRNA expression in pre-eclampsia: a case control study

Preeclampsia (PE) remains a leading cause of maternal morbidity and mortality all over the world. However, its aetiology and pathophysiology remain elusive. Platelet activating factor (PAF) is produced in response to oxidative stress and is a potent hypotensive agent. PAF acetylhydrolase (PAF-AH) inactivates PAF and is seen to decrease in normotensive women. The role of PAF-AH in preeclampsia has been in investigational literature, so far. The few studies done have shown a positive association of elevated levels of PAF-AH with preeclampsia. However, this marker has not been studied in the Indian population to-date and such studies are needed to elucidate the pathogenesis of this condition. Our study aimed to determine the PAF-AH activity by spectrophotometric assay in maternal plasma of 73 PE patients versus 73 normotensive controls and plasma PAF-AH mRNA expression to know the aberration of PAF-AH activity at the genetic level. Relative mRNA expression was calculated by Δ DCT method and a fold change was calculated by 2^-ΔDCT. We found that the mean plasma PAF-AH activity levels among cases was significantly higher than the normotensive controls. However, the mRNA expression of the PAF-AH gene was similar between the cases and controls, as well as between severe and non-severe preeclampsia (true fold change =1). To conclude, PAF-AH appears to be increased in women with preeclampsia and hence may contribute to pathophysiology and severity. However, a larger sample size will be required to reiterate this association. Recently, PAF-AH inhibitors such as Darapladib has been tested as a therapeutic option in atherosclerosis. After studying the role of PAF-AH in the pathogenesis of PE, PAF-AH inhibitors may be used as a therapeutic tool in the future in PE.IMPACT STATEMENTWhat is already known on this subject? Platelet activating factor (PAF) is produced in response to oxidative stress and is a potent hypotensive agent. PAF acetylhydrolase (PAF-AH) hydrolyses and inactivates PAF and is seen to decrease in normotensive women. The role of platelet activating factor-acetylhydrolase (PAF-AH) in preeclampsia has been investigational so far. Few studies done have shown a positive association of elevated levels of PAF-AH in preeclamptic women.What do the results of this study add? Our study aimed to determine the activity of PAF-AH in maternal plasma of PE patients versus normal pregnancy and plasma PAF-AH mRNA expression to know the aberration of PAF-AH activity at the level of the gene. We found that plasma PAF-AH activity among preeclamptics was significantly higher than in the controls with a possible role in early-onset preeclampsia (<32 weeks), in the Indian population. This marker has never been studied in this population earlier. The results of our study re-emphasised its role in the pathogenesis of preeclampsia.What are the implications of these findings for clinical practice and/or further research? Such studies are important to not only give us a greater understanding of the various pathways involved in this multifactorial dreaded condition, but can also offer us a marker for early identification of women at risk. Recently, PAF-AH inhibitors like Darapladib has been tested as a therapeutic option in atherosclerosis. After studying the role of PAF-AH in the pathogenesis of PE, PAF-AH inhibitors may be used as a therapeutic tool in the future in PE.

Going into labor and beyond: phospholipase A2 in pregnancy

The phospholipase A2(PLA2) family is a very diverse group of enzymes, all serving in the cleavage of phospholipids, thereby releasing high amounts of arachidonic acid (AA) and lysophospholipids. AA serves as a substrate for prostaglandin production, which is of special importance in pregnancy for the onset of parturition. Novel research demonstrates that PLA2action affects the immune response of the mother toward the child and is therefore probably implied in the tolerance of the fetus and prevention of miscarriage. This review presents data on the biochemical and enzymatic properties of PLA2during gestation with a special emphasis on its role for the placental function and development of the fetus. We also critically discuss the possible pathophysiological significance of PLA2alterations and its possible functional consequences. These alterations are often associated with pregnancy pathologies such as preeclampsia and villitis or pregnancy complications such as obesity and diabetes in the mother as well as preterm onset of labor.

Expression profile of C19MC microRNAs in placental tissue in pregnancy-related complications

To demonstrate that pregnancy-related complications are associated with alterations in placental microRNA expression. Gene expression of 15 C19MC microRNAs (miR-512-5p, miR-515-5p, miR-516-5p, miR-517-5p, miR-518b, miR-518f-5p, miR-519a, miR-519d, miR-519e-5p, miR-520a-5p, miR-520h, miR-524-5p, miR-525, miR-526a, and miR-526b) was assessed in placental tissues, compared between groups (21 gestational hypertension [GH], 63 preeclampsia, 36 fetal growth restriction [FGR], and 42 normal pregnancies), and correlated with the severity of the disease with respect to clinical signs, delivery date, and Doppler ultrasound parameters. The expression profile of microRNAs was different between pregnancy-related complications and controls. The downregulation of 4 of 15 (miR-517-5p, miR-519d, miR-520a-5p, and miR-525), 6 of 15 (miR-517-5p, miR-518f-5p, miR-519a, miR-519d, miR-520a-5p, and miR-525), and 11 of 15 (miR-515-5p, miR-517-5p, miR-518b, miR-518f-5p, miR-519a, miR-519d, miR-520a-5p, miR-520h, miR-524-5p, miR-525, and miR-526a) microRNAs was associated with GH, FGR, and preeclampsia, respectively. Sudden onset of severe preeclampsia requiring immediate termination of gestation and mild forms of preeclampsia (persisting for several weeks) were associated with similar microRNA expression profile (downregulation of miR-517-5p, miR-520a-5p, miR-524-5p, and miR-525). In addition, miR-519a was found to be associated with severe preeclampsia. The longer the pregnancy-related disorder lasted, the more extensive was the downregulation of microRNAs (miR-515-5p, miR-518b, miR-518f-5p, miR-519d, and miR-520h). The downregulation of some C19MC microRNAs is a common phenomenon shared between GH, preeclampsia, and FGR. On the other hand, some of the C19MC microRNAs are only downregulated just in preeclampsia.

Why does a high-fat diet induce preeclampsia-like symptoms in pregnant rats

Changes in neurotransmitter levels in the brain play an important role in epilepsy-like attacks after pregnancy-induced preeclampsia-eclampsia. Metabotropic glutamate receptor 1 participates in the onset of lipid metabolism disorder-induced preeclampsia. Pregnant rats were fed with a high-fat diet for 20 days. Thus, these pregnant rats experienced preeclampsia-like syndromes such as tension and proteinuria. Simultaneously, metabotropic glutamate receptor 1 mRNA and protein expressions were upregulated in the rat hippocampus. These findings indicate that increased sion of metabotropic glutamate receptor 1 promotes the occurrence of high-fat diet-induced preeclampsia in pregnant rats.

Maternal and fetal plasma platelet-activating factor acetylhydrolase activity and distribution in pre-eclampsia

BACKGROUND

Distribution of platelet-activating factor acetylhydrolase (PAF-AH) in lipoproteins plays important roles in the onset of inflammation and atherosclerosis. We hypothesized that women with pre-eclampsia (PE), showing signs of inflammation and oxidative stress, and their fetuses have aberrations of PAF-AH activity and distribution.

METHODS

Maternal and fetal plasma PAF-AH activity, high-density lipoprotein (HDL)-associated PAF-AH (H-PAF-AH) and low-density lipoprotein (LDL)-associated PAF-AH (L-PAF-AH) were examined in women with PE (n = 127) and in women with uncomplicated pregnancies (n = 88).

RESULTS

The neonates of women with severe PE (n = 42) had significantly higher plasma PAF-AH, L-PAF-AH activities, and ratio of L-PAF-AH to H-PAF-AH activities than the neonates of women with normal pregnancies (n = 83). The mothers with severe PE (n = 106) and their neonates presented a significantly higher atherogenic index (AI) and triglyceride (TG)/HDL cholesterol (C) ratio than the control mothers and their neonates. The ratio of L-PAF-AH to H-PAF-AH activities correlated positively with TG levels, TG/HDL(C) ratio, and AI and negatively with HDL(C) levels in the neonates of women with PE.

CONCLUSION

The neonates of women with severe PE presented with a chronic inflammation status, increased oxidative stress, and unfavorable lipid changes, which may potentially link to related complications responsible for oxidative stress and inflammation in later life.