Pregnancy-associated plasma protein A in dialysis patients

End-Stage Kidney Disease and Dialysis in Pregnancy

End-stage kidney disease is associated with low fertility, with rates of conception in women on dialysis estimated at 1/100th of the general population. However, live birth rates are increasing over time in women on hemodialysis, whereas they remain lower and static in women on peritoneal dialysis. Intensification of hemodialysis, targeting a serum blood urea nitrogen <35 mg/dL or 36 hours of dialysis per week in women with no residual kidney function, is associated with improved live birth rates and longer gestational age. Even in intensively dialyzed cohorts, rates of prematurity and need for neonatal intensive care are high, upwards of 50%. Although women on peritoneal dialysis in pregnancy do not appear to be at increased risk of delivering preterm compared with those on hemodialysis, their infants are more likely to be small for gestational age. As such, hemodialysis has emerged as the preferred dialysis modality in pregnancy. Provision of specialized nephrology, obstetric, and neonatal care is necessary to manage these complex pregnancies and family planning counseling should be offered to all women with end-stage kidney disease.

Metalloproteinase PAPP-A regulation of IGF-1 contributes to polycystic kidney disease pathogenesis

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic cause of end-stage renal disease (ESRD). The treatment options for ADPKD are limited. We observed an upregulation in several IGF-1 pathway genes in the kidney of Pkd1RC/RC mice, a model of ADPKD. Pregnancy-associated plasma protein A (PAPP-A), a metalloproteinase that cleaves inhibitory IGF binding proteins (IGFBPs), increasing the local bioactivity of IGF-1, was highly induced in the kidney of ADPKD mice. PAPP-A levels were high in cystic fluid and kidneys of humans with ADPKD. Our studies further showed that PAPP-A transcription in ADPKD was mainly regulated through the cAMP/CREB/CBP/p300 pathway. Pappa deficiency effectively inhibited the development of cysts in the Pkd1RC/RC mice. The role of PAPP-A in cystic disease appears to be regulation of the IGF-1 pathway and cellular proliferation in the kidney. Finally, preclinical studies demonstrated that treatment with a monoclonal antibody that blocks the proteolytic activity of PAPP-A against IGFBP4 ameliorated ADPKD cystic disease in vivo in Pkd1RC/RC mice and ex vivo in embryonic kidneys. These data indicated that the PAPP-A/IGF-1 pathway plays an important role in the growth and expansion of cysts in ADPKD. Our findings introduce a therapeutic strategy for ADPKD that involves the inhibition of PAPP-A.

Chronic Kidney Disease and Pregnancy

Chronic kidney disease represents a heterogeneous group of disorders characterized by alterations in the structure and function of the kidney. Chronic kidney disease significantly increases the risk of adverse maternal and perinatal outcomes, and these risks increase with the severity of the underlying renal dysfunction, degree of proteinuria, as well as the frequent coexistence of hypertension. Further, renal anatomic changes result in dilatation of the collecting system, and physiologic adaptations include alterations in the balance of vasodilatory and vasoconstrictive hormones, resulting in decreased systemic and renal vascular resistance, increased glomerular filtration rate, and modifications in tubular function. These alterations have important clinical implications and can make the diagnosis of renal compromise challenging. The effect of pregnancy on kidney disease may manifest as a loss of renal function, particularly in the context of concomitant hypertension and proteinuria, and chronic kidney disease, even when mild, contributes to the high risk of adverse pregnancy outcomes, including increased risks of preeclampsia, preterm delivery, and small-for-gestational age neonates. Strategies for optimization of pregnancy outcomes include meticulous management of hypertension and proteinuria where possible and the initiation of preeclampsia prevention strategies, including aspirin. Avoidance of nephrotoxic and teratogenic medications is necessary, and renal dosing of commonly used medications must also be considered. Mode of delivery in women with chronic kidney disease should be based on usual obstetric indications, although more frequent prenatal assessments by an expert multidisciplinary team are desirable for the care of this particularly vulnerable patient population. Obstetricians represent a critical component of this team responsible for managing each stage of pregnancy to optimize both maternal and neonatal outcomes, but collaboration with nephrology colleagues in combined clinics wherein both specialists can make joint management decisions is typically very helpful.

Pregnancy-Associated Plasma Protein A (PAPP-A) Concentration in Population of Healthy Young People: Interactions with Tobacco Smoke and Anti-oxidative Status

Pregnancy-associated plasma protein A (PAPP-A) is a high-molecular zinc-binding metalloproteinase that was first detected in the serum of pregnant women. It can also be detected in men and non-pregnant women. Recently, a growing interest in determining the concentration of PAPP-A as a marker of oxidative stress and atherosclerotic processes has been observed. Among the factors that could potentially influence the PAPP-A formation is the exposure to tobacco smoke. Some components of tobacco smoke have an immediate effect on the body and also direct influence on the cardiovascular system. The aim of this study was to evaluate the relation between PAPP-A concentration and either passive or active exposure to tobacco smoke in the population of medicine students (n = 152). The relation between PAPP-A concentration and chosen markers of inflammatory response and anti-oxidative processes was analyzed. The samples of serum, urine, and saliva were collected and main nicotine metabolites in urine samples were determined using ELISA technique. Comparison of the PAPP-A concentrations in the study group revealed that in the group of active smokers, the concentration of the protein was significantly higher than in the group of passive smokers (p = .04) and the group of not-exposed students (p = .006). PAPP-A concentration showed significant positive correlation with the values of FRAP and main nicotine metabolites. The evident influence of both active and passive tobacco smoke exposure on PAPP-A levels in the studied population of young people who in general are not included in the group of high-risk cardiovascular incidents, shows how important early prevention of anti-health behaviors is.

Pregnancy and End-Stage Renal Disease

Pregnancy is uncommon in women with end-stage renal disease (ESRD). Fertility rates are low in women on dialysis, and physicians still frequently counsel women with ESRD against pregnancy. Advancements in the delivery of dialysis and obstetric care have led to improved live birth rates in women on dialysis, so pregnancy for young women with ESRD is now more feasible and safer. However, these pregnancies remain high-risk for both maternal and fetal complications, necessitating experienced multidisciplinary care. In this article, we review fertility issues in women with ESRD, discuss pregnancy outcomes in women on dialysis, and provide an approach for management of pregnant women with ESRD.

Intensive dialysis and pregnancy

Pregnancy in women with end stage renal disease on renal replacement therapy is uncommon due to the physiologic changes associated with renal failure as well as the complexities and risk involved in managing these patients. As most of these women had long periods of illness with chronic kidney disease, the effects of their chronic illness together with the current societal trends to delay child bearing to a more advanced maternal age can hamper fertility. For those able to conceive, intensified hemodialysis (HD), through longer and/or more frequent dialysis sessions, offers improved maternal and neonatal outcomes. Intensified HD is most conveniently offered in the patient's home, where possible. This review expands the scope of the Implementing Hemodialysis in the Home website and associated supplement published previously in Hemodialysis International and includes information tailored to women of reproductive age. We describe the necessary counseling that women should receive before conception and before intensification of HD, and provide a detailed management strategy that includes nephrologic and obstetric care, should pregnancy occur.

Pregnancy-associated plasma protein-A and the vulnerable plaque

For more than a decade, pregnancy-associated plasma protein-A (PAPP-A) has been examined for its relation to acute coronary syndrome (ACS) and the vulnerable plaque. This review summarizes the current knowledge of plasma PAPP-A in relation to nonpregnant individuals focusing on patients with ACS, discusses its use as a possible biomarker for diagnosis and prognosis in ACS, briefly describes the challenges in different assay technologies and describes the effect of heparin administration on PAPP-A concentrations in plasma.

Elevated serum free pregnancy-associated plasma protein-A independently predicts mortality in haemodialysis patients but is not associated with recurrent haemodialysis-induced ischaemic myocardial injury

BACKGROUND/AIMS

Pregnancy-associated plasma protein-A (PAPP-A) is a putative marker of atheroma instability and ischaemic myocardial stress prior to necrosis. Total PAPP-A (tPAPP-A) levels in acute coronary syndromes predict adverse outcomes. However, free PAPP-A (fPAPP-A) predominates in the circulation. Ischaemic haemodialysis (HD)-induced cardiac injury (myocardial stunning) is common and is associated with markers of myocardial necrosis, inflammation, cardiovascular events and mortality. Coronary plaque instability in pathophysiology of HD-induced myocardial stunning has not been studied. We aimed to investigate the relationship of fPAPP-A with stunning and mortality.

METHODS

130 prevalent patients from two HD centres (Finland and UK) were studied. Pre-HD free, complexed and total PAPP-A were measured by immunoassay. A subset of 62 patients underwent echocardiography to assess HD-induced myocardial stunning. The mean duration of follow-up was 407 ± 98 days.

RESULTS

fPAPP-A was elevated (median: 3.45 mIU/l) and correlated with dialysis vintage (r = 0.391, p < 0.001), cardiac troponin T (cTnT; r = 0.29, p = 0.001) and cardiac troponin I (cTnI; r = 0.22, p = 0.01). PAPP-A was not related to stunning. Dialysis vintage and cTnT independently predicted Ln fPAPP-A (model R = 0.463). fPAPP-A, cTnT and age independently predicted death (Nagelkerke R(2) = 0.362).

CONCLUSIONS

fPAPP-A, a novel predictor of HD-related mortality, demonstrates better prognostic power than tPAPP-A. Coronary plaque instability may contribute to sub-lethal myocardial injury, but may not be critical in pathogenesis of HD-induced ischaemic cardiac injury.

First-trimester combined screening for trisomy 21 in women with renal disease

OBJECTIVE

To evaluate the results of first-trimester combined screening for Down syndrome in women with chronic renal disease.

METHOD

Fifty-five pregnant women with renal disease were compared with 110 patients matched for maternal age, maternal weight, smoking status, and gestational age. Maternal renal function was assayed at the time of the combined screening, and renal insufficiency was defined by serum creatinine >90 µmol/L and renal clearance <80 mL/min. We defined three groups: kidney disease and normal renal function (group 1), kidney disease and renal insufficiency (group 2), and a control group (group 3). The values of nuchal translucency, pregnancy-associated plasma protein A, human β-chorionic gonadotrophin (hCGβ), and false-positive rates for Down syndrome screening were compared.

RESULTS

There were 39 (71%) and 16 (29%) cases in groups 1 and 2, respectively. Nuchal translucency and multiple of the median (MoM) pregnancy-associated plasma protein A were similar in the three groups. However, MoM hCGβ levels were higher in group 2 than in groups 1 and 3 (5.37 vs 1.1 vs 0.98 MoM, p = 0.0001). The resulting screen-positive rate was also higher in group 2 than in groups 1 and 3 (43.7% vs 10.2% vs 5.5%, p = 0.0001).

CONCLUSION

Trisomy 21 first-trimester screening using hCGβ is not suitable in the case of maternal renal failure. © 2014 John Wiley & Sons, Ltd.

Association of E-selectin gene polymorphism and serum PAPP-A with carotid atherosclerosis in end-stage renal disease

BACKGROUND

Atherosclerotic vascular disease represents a significant cause of morbidity and mortality in patients with end-stage renal disease (ESRD). The endothelium plays a crucial role in vascular inflammation. E-selectin is exclusively expressed on activated endothelial cells and is upregulated following an inflammatory response and oxidative stress, while serum pregnancy-associated plasma protein-A (PAPP-A) concentrations are related to the presence and stability of carotid atherosclerotic plaques.

OBJECTIVE

The aim of this study was to investigate whether there is an association between SELE rs5355C>T gene polymorphism, serum PAPP-A level and the presence of carotid atherosclerosis in ESRD patients.

SUBJECTS AND METHODS

Seventy subjects were recruited into this study; 40 ESRD patients [age (mean ± SD) 43.42 ± 13.94 years] and 30 age- and gender-matched healthy individuals assigned to the control group. Polymerase chain reaction-restriction fragment length polymorphism was performed for the analysis of SELE rs5355C>T gene polymorphism, while serum PAPP-A concentrations were measured using electro-chemiluminescence immunoassay. Routine laboratory tests were measured on an automated chemistry analyzer. Carotid ultrasonographic studies were performed by a bilateral high-resolution B-mode ultrasound.

RESULTS

There was no significant relationship between the SELE rs5355C>T gene polymorphism and ESRD incidence. Serum PAPP-A levels were significantly higher in ESRD patients compared with controls [median (interquartile range) 5.8 (5.1-11.6) and 5.1 (4.1-6.7), respectively; p = 0.005]. Serum PAPP-A correlated positively with urea, creatinine, systolic and diastolic blood pressure (DBP). Serum PAPP-A showed a statistically significant increase in SELE rs5355TT versus CC in both patients and controls. There was no association on comparing right intima-media thickness (IMT), left IMT, right cross-sectional area (CSA) and left CSA with the CC, CT and TT genotypes of SELE rs5355C>T. No correlation between serum PAPP-A with each of the above-mentioned carotid doppler findings was observed. There was a statistically significant increase in DBP in TT genotype carriers when compared with CC genotype carriers (p = 0.009). Serum PAPP-A levels were higher in hypertensive ESRD patients when compared with normotensive ESRD patients. There was a statistically significant decrease in high-density lipoprotein cholesterol (HDL-C) in TT genotype carriers when compared with CT genotype carriers in the whole study group (p = 0.003). Serum PAPP-A correlated negatively with HDL-C.

CONCLUSION

The lack of a direct association between SELE rs5355C>T gene polymorphism, serum PAPP-A level and IMT suggests that their hypothesized association with carotid atherosclerosis might reflect an indirect mechanism of SELE rs5355C>T gene polymorphism and serum PAPP-A with cardiovascular risk factors such as blood pressure and HDL-C rather than a direct effect on the vasculature.

Pregnancy-associated plasma protein A (PAPP-A) and preeclampsia

Pregnancy-associated plasma protein A (PAPP-A) is a key regulator of insulin-like growth factor bioavailability essential for normal fetal development. In maternal blood, this protein increases with gestational age and then rapidly decreases after delivery. It is routinely used for Down syndrome screening in the first trimester of pregnancy, and its decrease compared to a normal pregnancy indicates an increased risk for both chromosomal anomalies and adverse pregnancy outcomes. It belongs to a group of biomarkers that predict later preeclampsia development, primarily early onset preeclampsia; however, it should be combined with a Doppler ultrasonography of the uterine artery (pulsatile index) and other biochemical and maternal factors to achieve a higher detection rate with an acceptable false positivity rate. Some studies have demonstrated an even more pronounced decrease of PAPP-A in the early second trimester of pregnancy in women who subsequently develop preeclampsia compared with women who do not develop preeclampsia. Conversely, during the last trimester of pregnancy, its concentration increases even more in patients with preeclampsia than in patients without. It is also detectable at very low levels in nonpregnant individuals, and a higher concentration indicates an adverse effect in patients with acute coronary syndromes or stable atherosclerotic disease and in patients with end-stage renal disease who are being treated with hemodialysis.

Association between serum pregnancy-associated plasma protein-A and bicarbonate in hemodialysis patients

BACKGROUND

Acidosis is associated with protein-energy malnutrition, inflammation, and bone disease, and low bicarbonate levels have been implicated in higher mortality rates in chronic kidney disease. Recently, the concentration of serum pregnancy-associated plasma protein-A (PAPP-A) has become accepted as a prognostic marker in hemodialysis patients. This study determined the relationship between PAPP-A and bicarbonate levels in these patients.

METHODS

The study enrolled 65 hemodialysis patients (41 males, 24 females) and 26 control subjects (11 males, 15 females). Serum PAPP-A, intact parathormone (iPTH), calcium, phosphorus (P), and bicarbonate levels were measured. Correlations between PAPP-A and bicarbonate, iPTH, calcium, and phosphorus were evaluated.

RESULTS

Median PAPP-A levels were significantly higher in hemodialysis patients [15.1 (<0.03-158.8) ng/ml] than in control subjects [6.6 (<0.03-16.4) ng/ml] (P < 0.05). There were statistically significant correlations between serum PAPP-A and bicarbonate, iPTH, and P in hemodialysis patients but not in control subjects.

CONCLUSION

Elevation of serum PAPP-A has been found in hemodialysis patients and its significant correlation with bicarbonate suggests that it may be a prognostic factor.

Reference interval of pregnancy-associated plasma protein-a in healthy men and non-pregnant women

OBJECTIVE

The serum pregnancy-associated plasma protein-A (PAPP-A) concentration is a predictor of ischemic cardiac events and renal impairment. However, the reference interval of PAPP-A has not been determined. This study determined the reference interval of PAPP-A in men and non-pregnant women.

METHODS

The study enrolled 126 apparently healthy individuals (52 males and 74 females). The mean age of the men and women was 34.7 (range 20-66) years and 34.6 (range 18-65) years, respectively. Serum PAPP-A concentrations were determined using an ultrasensitive enzyme-linked immunoassay kit. Reference intervals were calculated using the bootstrap method.

RESULTS

The results for three subjects were outliers, so the reference interval of PAPP-A was calculated using the data for 123 subjects. PAPP-A was undetectable in 26 subjects. The reference interval of PAPP-A for men and women (with the 90% confidence interval) was <22.9 ng/mL (19.7-23.3) and <33.6 ng/mL (25.2-36.7), respectively. In male subjects, serum PAPP-A levels of smokers [3.10 (UD, 7.30)ng/mL] were significantly lower than that of non-smokers [11.00 (UD, 24.4)ng/mL] (p<0.001) and there was a positive correlation between serum PAPP-A levels and subjects' age (r=0.439; p<0.001).

CONCLUSIONS

The reference interval of PAPP-A differed for men and non-pregnant women. In clinical practice, <22.9 ng/mL for men and <33.6 ng/mL for non-pregnant women may be used as reference intervals for PAPP-A.

Pregnancy in end stage renal disease

The ovulatory menstrual cycle is known to be affected on multiple levels in women with advanced renal disease. Menstrual irregularities, sexual dysfunction, and infertility worsen in parallel with the renal disease. Pregnancy in women with ESRD on dialysis is therefore uncommon. Furthermore, when pregnancy does occur, it can prove hazardous to both mother and baby owing to a multitude of potential complications including accelerated hypertension and preeclampsia, poor fetal growth, anemia, and polyhydramnios. Data are emerging, however, to suggest that pregnancy while on intensified renal replacement regimens may result in better pregnancy outcomes, and emerging trends include the decreased rate of therapeutic abortions probably reflecting a change in counseling practices over time. Nevertheless, a pregnant woman on intensive dialysis requires meticulous follow-up by a dedicated team including nephrology, obstetrics, and a full multidisciplinary staff. In this article, we will address fertility issues in young women with ESRD, review pregnancy outcomes in women on both hemodialysis and peritoneal dialysis, and provide suggestions for the management of the pregnant women on intensive hemodialysis.

Pregnancy-associated plasma protein-A is an independent short-time predictor of mortality in patients on maintenance haemodialysis

AIMS

Mortality of maintenance haemodialysis (HD) patients is very high due to polymorbidity, mostly from metabolic and cardiovascular disease. In order to identify patients with high risk for life-threatening complications, reliable prognostic markers would be helpful. Pregnancy-associated plasma protein-A (PAPP-A) has been shown to predict cardiovascular events and death in patients with stable coronary artery disease as well as in acute coronary syndrome in patients with normal renal function. It was the aim of this study to evaluate PAPP-A as a marker for death in patients on maintenance HD.

METHODS AND RESULTS

PAPP-A serum levels were measured in 170 patients participating in the monitor! trial, a prospective dynamic dialysis cohort multicenter study in Switzerland. Patients were followed up for a median time of 17 months after measuring PAPP-A, and evaluated for death of any cause. Survivors and non-survivors were compared with regard to baseline PAPP-A concentrations. A multivariate logistic regression analysis for death was performed including PAPP-A, age, sex, number of comorbidities, dialysis vintage, Kt/V, IL-6, C-reactive protein, parathyroid hormone (PTH), Ca x PO(4) product, and total serum cholesterol. A cut-off value for PAPP-A was calculated for discrimination between patients with low and high mortality risk, respectively. A total of 23 deaths occurred during follow-up, equalling an incidence rate of 0.1. Baseline median PAPP-A levels were 40% higher in non-survivors vs. survivors (P = 0.023). In a multivariate analysis, only PAPP-A, age, and Ca x PO(4) product were independent predictors of mortality. A cut-off value of 24 mIU/L discriminates significantly (P = 0.015) between patients at low or high risk for death with a negative predictive value of 91%.

CONCLUSION

PAPP-A is a novel and independent short-time predictor of mortality in a maintenance HD population. The pathogenetic relevance of PAPP-A, particularly in the development of cardiovascular disease, remains to be further elucidated.

Pregnancy-associated plasma protein A in non-cardiac conditions

OBJECTIVE

PAPP-A is a promising new marker in coronary heart disease. It is important to investigate its specificity in order to establish its clinical utility as a marker of coronary heart disease.

DESIGN AND METHODS

PAPP-A was measured within 24 h following hospital admission in 1448 consecutive patients admitted with diagnoses other than acute coronary syndromes.

RESULTS

PAPP-A was detectable (> or = 4.0 mIU/L) in 278 (19.2%) patients, among whom the mean level was 6.3 mIU/L (95% C.I., 6.1-6.5 mIU/L). The 95 and 99 percentiles for PAPP-A were 7.3 and 9.4 mIU/L, respectively. There was no difference in the mean PAPP-A of different diagnoses (p=0.33). None of the specific diagnoses known to influence established coronary markers appeared to influence the level of circulating PAPP-A.

CONCLUSION

PAPP-A is low in patients without known coronary heart disease. PAPP-A levels seem to be a potentially highly specific marker for heart disease.