Serum podocalyxin for early detection of preeclampsia at 11–13 weeks of gestation

Kidney injury molecule-1 and podocalyxin dysregulation in an arginine vasopressin induced rodent model of preeclampsia

OBJECTIVE

To assess renal injury in an arginine vasopressin (AVP) rodent model of preeclampsia.

STUDY DESIGN

Urinary expression of kidney injury molecule-1 (KIM-1), urinary protein and creatinine was determined in rodents (n = 24; pregnant AVP, pregnant saline, non-pregnant AVP and non-pregnant saline), which received a continuous dose of either AVP or saline via subcutaneous mini osmotic pumps for 18 days, using a Multiplex kidney toxicity immunoassay. Renal morphology was assessed using haematoxylin and eosin staining and transmission electron microscopy. The immunolocalization of KIM-1 and podocalyxin was qualitatively evaluated using immunohistochemistry.

RESULTS

Urinary KIM-1 and urinary protein levels were significantly increased in treated vs. untreated rats on gestational days 8 (p < 0.05), 14 (p < 0.001) and 18 (p < 0.001). The pregnant rats displayed a lower trend of creatinine compared to the non-pregnant groups, albeit non-significantly. KIM-1 was immunolocalized in the proximal convoluted tubules in AVP treated vs. untreated groups. In contrast, podocalyxin was weakly immunostained within glomeruli of pregnant AVP treated vs. pregnant untreated rats. Histological evaluation revealed reduced Bowman's space, with some tubular and blood vessel necrosis in the pregnant treated group. Ultrastructural observations included effacement and fusion of podocyte foot processes, glomerular basement membrane abnormalities, podocyte nuclear crenations, mitochondrial oedema and cristae degeneration with cytoplasmic lysis within treated tissue.

CONCLUSION

Our findings demonstrate region-specific kidney injury particularly glomerular impairment and endothelial injury in AVP-treated rats. The findings highlight the utility of this model in studying the mechanisms driving renal damage in a rodent model of preeclampsia.

Levels of serum podocalyxin in preeclampsia and relationship with maternal echocardiographic and Doppler ultrasound parameters

INTRODUCTION

Podocalyxin (PCX) is an indicator of glomerular injury. Aside from the kidney, it is expressed in the endothelial cells of various organs. Echographic examinations are useful in assessing the alterations in cardiovascular structure and function during pregnancy.

OUP accepted manuscript

Preeclampsia is a pregnancy-specific disease that can have serious effects on the health of both mothers and their offspring. Predicting which women will develop preeclampsia in early pregnancy with high accuracy will allow for improved management. The clinical symptoms of preeclampsia are well recognized, however, the precise molecular mechanisms leading to the disorder are poorly understood. This is compounded by the heterogeneous nature of preeclampsia onset, timing and severity. Indeed a multitude of poorly defined causes including genetic components implicates etiologic factors, such as immune maladaptation, placental ischemia and increased oxidative stress. Large datasets generated by microarray and next-generation sequencing have enabled the comprehensive study of preeclampsia at the molecular level. However, computational approaches to simultaneously analyze the preeclampsia transcriptomic and network data and identify clinically relevant information are currently limited. In this paper, we proposed a control theory method to identify potential preeclampsia-associated genes based on both transcriptomic and network data. First, we built a preeclampsia gene regulatory network and analyzed its controllability. We then defined two types of critical preeclampsia-associated genes that play important roles in the constructed preeclampsia-specific network. Benchmarking against differential expression, betweenness centrality and hub analysis we demonstrated that the proposed method may offer novel insights compared with other standard approaches. Next, we investigated subtype specific genes for early and late onset preeclampsia. This control theory approach could contribute to a further understanding of the molecular mechanisms contributing to preeclampsia.

The role of serum podocalyxin levels in recurrent pregnancy loss

OBJECTIVE

To measure serum levels of podocalyxin (PODXL) in recurrent miscarriages as a marker of vascular endothelial dysfunction.

STUDY DESIGN

In this case-control study, women who were hospitalized for singleton first-trimester pregnancy terminations due to missed abortion, anembryonic pregnancy, and inevitable abortion were included. There were 24 patients who were admitted for the first pregnancy termination, 39 patients who were admitted for recurrent pregnancy loss (RPL), and 25 fetal cardiac activity positive patients as the control group. Demographic features, medical and obstetric histories were recorded. The measurements of serum PODXL were done by a human enzyme-linked immunosorbent assay kit.

RESULTS

Serum PODXL levels were found to be significantly higher in the RPL group than the control group and the first time miscarriage group (13.82 [10.09-113.54] vs. 11.78 [9.25-48.80], p = 0.016 and 13.82 [10.09-113.54] vs. 11.99 [8.20-20.47], p = 0.003; respectively). Serum PODXL levels were not statistically significantly different between the first miscarriage and the control group (p = 0.62). There were positive correlation between serum PODXL levels and the number of gravida and the number of miscarriages (r = 0.217, p = 0.042, and r = 0.291, p = 0.006; respectively).

CONCLUSION

Recurrent miscarriage patients had higher serum levels of PODXL than both normal pregnancies and first-time miscarriages. Our results suggest that maternal endothelial dysfunction might have a role in recurrent pregnancy losses.

Regulation of the Actin Cytoskeleton in Podocytes

Podocytes are an integral part of the glomerular filtration barrier, a structure that prevents filtration of large proteins and macromolecules into the urine. Podocyte function is dependent on actin cytoskeleton regulation within the foot processes, structures that link podocytes to the glomerular basement membrane. Actin cytoskeleton dynamics in podocyte foot processes are complex and regulated by multiple proteins and other factors. There are two key signal integration and structural hubs within foot processes that regulate the actin cytoskeleton: the slit diaphragm and focal adhesions. Both modulate actin filament extension as well as foot process mobility. No matter what the initial cause, the final common pathway of podocyte damage is dysregulation of the actin cytoskeleton leading to foot process retraction and proteinuria. Disruption of the actin cytoskeleton can be due to acquired causes or to genetic mutations in key actin regulatory and signaling proteins. Here, we describe the major structural and signaling components that regulate the actin cytoskeleton in podocytes as well as acquired and genetic causes of actin dysregulation.

Recent progress in human placental transcriptomics

The placenta serves as a metabolic, respiratory, excretory, and endocrine organ that provides appropriate conditions required for adequate fetal development during pregnancy. The development of particular structures and proper functioning of the placenta are under the influence of sophisticated pathways controlled by the expression of substantial genes that are additionally regulated by long non-coding ribonucleic acids (RNAs). Disruptions to adaptive changes in the placental transcriptome as a response to alterations in the feto-maternal environment may be associated with pregnancy complications and compromised fetal outcomes. The aim of the current paper was to present recent findings in transcriptomics of the human placenta. Different approaches in bioinformatic analyses of the RNA-sequencing results were presented. Novel knowledge about the genes and mechanisms that are crucial for the proper development of the placenta is essential for the understanding what stands behind both the normal and complicated pregnancy.

Serum podocalyxin at 11-13 weeks of gestation in the prediction of small for gestational age neonates

OBJECTIVE

To investigate a potential new marker for the prediction of small for gestational age (SGA) infants.

STUDY DESIGN

Nested case-control study involving 280 uncomplicated pregnancies and 70 cases of SGA without pre-eclampsia. Serum podocalyxin was measured at 11-13 weeks of gestation and results were expressed in multiples of the median (MoM). The performance of screening by a combination of maternal history and podocalyxin levels was assessed with ROC curves.

RESULTS

SGA was predicted by maternal age, height, South Asian ethnicity, and previous delivery without pre-eclampsia. Median podocalyxin levels were higher in affected than uncomplicated pregnancies (1.303 versus 0.994 MoM, p < 0.001). At a 10% false-positive rate, maternal history identified 40.0% of the cases (AUC = 0.74, 95%CI 0.671-0.809). The addition of podocalyxin increased the detection to 54.3% (AUC = 0.78, 95%CI 0.771-0.842, p = 0.027 for the difference in ROC curves).

CONCLUSION

First-trimester podocalyxin may be useful in screening for SGA infants.

Placenta Transcriptome Profiling in Intrauterine Growth Restriction (IUGR)

Intrauterine growth restriction (IUGR) is a serious pathological complication associated with compromised fetal development during pregnancy. The aim of the study was to broaden knowledge about the transcriptomic complexity of the human placenta by identifying genes potentially involved in IUGR pathophysiology. RNA-Seq data were used to profile protein-coding genes, detect alternative splicing events (AS), single nucleotide variant (SNV) calling, and RNA editing sites prediction in IUGR-affected placental transcriptome. The applied methodology enabled detection of 37,501 transcriptionally active regions and the selection of 28 differentially-expressed genes (DEGs), among them 10 were upregulated and 18 downregulated in IUGR-affected placentas. Functional enrichment annotation indicated that most of the DEGs were implicated in the processes of inflammation and immune disorders related to IUGR and preeclampsia. Additionally, we revealed that some genes (S100A13, GPR126, CTRP1, and TFPI) involved in the alternation of splicing events were mainly implicated in angiogenic-related processes. Significant SNVs were overlapped with 6533 transcripts and assigned to 2386 coding sequence (CDS), 1528 introns, 345 5' untranslated region (UTR), 1260 3'UTR, 918 non-coding RNA (ncRNA), and 10 intergenic regions. Within CDS regions, 543 missense substitutions with functional effects were recognized. Two known mutations (rs4575, synonymous; rs3817, on the downstream region) were detected within the range of AS and DEG candidates: PA28β and PINLYP, respectively. Novel genes that are dysregulated in IUGR were detected in the current research. Investigating genes underlying the IUGR is crucial for identification of mechanisms regulating placental development during a complicated pregnancy.