Pregnancy-associated plasma protein A in a large cohort of Type 1 diabetic patients with and without diabetic nephropathy-a prospective follow--up study

Pregnancy-associated plasma protein A as a predictor of all-cause mortality and cardiovascular events in patients with chronic kidney disease: a meta-analysis of prospective studies

INTRODUCTION

The aim of the study was to assess the association of elevated serum pregnancy associated plasma protein A (PAPP-A) and the risk of all-cause mortality, cardiovascular events and mortality due to infection in patients with chronic kidney disease (CKD).

MATERIAL AND METHODS

We systematically searched the Medline database up to March 2017. A random effects model was used to pool the relative risks (RRs) and their 95% confidence intervals (CIs). Sensitivity analysis and subgroup analysis were performed to explore the potential sources of heterogeneity.

RESULTS

Six studies involving 2034 subjects were included. The pooled RRs for the risk of all-cause mortality and cardiovascular events were 1.50 (95% CI: 1.17-1.92), 1.26 (95% CI: 0.95-1.69), respectively. Sensitivity analysis by excluding each individual study showed no influence on the main results. Subgroup analysis showed that age, male proportion, follow-up term, and assay methods were not modifiable factors.

CONCLUSIONS

Our study suggests that elevated serum PAPP-A is associated with the risk of all-cause mortality in patients with CKD.

Pregnancy associated plasma protein-A as a prognostic biomarker of all-cause mortality and cardiovascular events in patients presenting with chest pain: a systematic review

AIM

Novel biomarkers have been proposed for identification of patients at greater risk of future adverse events among those presenting with chest pain. In this review, we aim to elucidate the ability of pregnancy associated plasma protein-A (PAPP-A) to predict mortality and other cardiovascular events in this patient population.

METHODS

A literature search of the electronic databases Medline, Scopus, Cochrane Library and ClinicalTrials.gov was performed in order to identify studies investigating the utility of PAPP-A to predict mortality and adverse cardiovascular events in patients with chest pain.

RESULTS

Eight studies met our inclusion criteria. Five of these studies pertained to patients with confirmed ischemic chest pain, while the rest included patients presenting with chest pain possibly due to acute coronary syndrome, irrespectively of the underlying cause. Although the results for long-term events were inconclusive in both groups of patients, higher PAPP-A concentrations were found to be a significant predictor of short-term adverse events in patients with confirmed ischemic chest pain.

CONCLUSIONS

PAPP-A appears to be a potentially useful biomarker for short-term risk stratification of patients presenting with chest pain of ischemic origin. However, there is an eminent need for more standardized clinical studies investigating the prognostic value of this biomarker.

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.

The effect of heparin on pregnancy associated plasma protein-A concentration in healthy, non-pregnant individuals

OBJECTIVES

The objective of this study was to determine the differences in pregnancy associated plasma protein-A (PAPP-A) concentrations in heparin naive and heparin treated healthy men and non-pregnant women, to find a possible difference in different age groups, and to determine the response in PAPP-A concentration to repeated injections of unfractionated heparin.

DESIGN AND METHODS

Twenty-five healthy, non-pregnant volunteers divided into five groups (determined by gender and age) received 5000 IU unfractionated heparin intravenously. Five young men received an additional 5000 IU after 90 and 180 min. Blood samples to determine PAPP-A concentration and APTT were drawn at different time points.

RESULTS

Injection of heparin elicited increase in and rapid normalization of PAPP-A concentrations in all subjects. The group of 20-30-year-old never-pregnant women had lower responses than the individuals of the four other groups. The difference was not significant (p > 0.05). Repeated injections of heparin caused additional peaks in PAPP-A concentration of about the same sizes as the first peak. We observed an increase in time to normalization of PAPP-A concentration (from 75-90 min to 90-150 min) and APTT levels with repeated injections.

CONCLUSIONS

We observed a rapid normalization of PAPP-A. Our result has a great similarity to the half-life of unfractionated heparin. This result combined with the finding of equally sized peaks in PAPP-A concentration, and that all of this was found in healthy, non-pregnant individuals, suggests that heparin might compete for a binding-site on PAPP-A or with PAPP-A itself for a common receptor in healthy arterial vessels.

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.

Tissue-specific changes in pregnancy associated plasma protein-A expression with age in mice

Pregnancy-associated plasma protein-A (PAPP-A) is a novel zinc metalloproteinase that functions in many systems outside of pregnancy. Data in both humans and mice suggest a role for PAPP-A in aging and age-related diseases. However, our knowledge of tissue-specific PAPP-A expression and possible changes in this expression with age is limited. Thus, the aim of this study was to determine PAPP-A mRNA expression in multiple tissues with age in both male and female mice using real-time PCR. These included the heart, liver, kidney, bone, fat, skeletal muscle, gonads, brain, thymus and spleen. In young mice, PAPP-A mRNA was expressed at relatively high levels in all tissues examined except for liver. The only difference in expression between males and females was seen in the kidney, subcutaneous fat and gonads. The highest PAPP-A mRNA expression levels were found in visceral fat and these were 10-fold higher than in subcutaneous fat. PAPP-A expression significantly increased with age in kidney, brain and gonads. PAPP-A expression significantly deceased with age in bone and skeletal muscle. In the thymus, PAPP-A mRNA showed a biphasic response with age. There were no age-related changes in PAPP-A expression seen in any of the other tissues examined. Expression of IGFBP-5 mRNA, a marker of insulin-like growth factor-I (IGF-I) bioactivity known to be regulated by PAPP-A, paralleled the changes in PAPP-A expression with age in kidney, bone, skeletal muscle and thymus. Thus, tissue-specific PAPP-A expression in mice is differentially affected during aging, and may regulate local IGF-I bioactivity in certain tissues.

Mice deficient in PAPP-A show resistance to the development of diabetic nephropathy

We investigated pregnancy-associated plasma protein-A (PAPP-A) in diabetic nephropathy. Normal human kidney showed specific staining for PAPP-A in glomeruli, and this staining was markedly increased in diabetic kidney. To assess the possible contribution of PAPP-A in the development of diabetic nephropathy, we induced diabetes with streptozotocin in 14-month-old WT and Papp-A knockout (KO) mice. Renal histopathology was evaluated after 4 months of stable hyperglycemia. Kidneys from diabetic WT mice showed multiple abnormalities including thickening of Bowman's capsule (100% of mice), increased glomerular size (80% of mice), tubule dilation (80% of mice), and mononuclear cell infiltration (90% of mice). Kidneys of age-matched non-diabetic WT mice had similar evidence of tubule dilation and mononuclear cell infiltration to those of diabetic WT mice, indicating that these changes were predominantly age-related. However, thickened Bowman's capsule and increased glomerular size appeared specific for the experimental diabetes. Kidneys from diabetic Papp-A KO mice had significantly reduced or no evidence of changes in Bowman's capsule thickening and glomerular size. There was also a shift to larger mesangial area and increased macrophage staining in diabetic WT mice compared with Papp-A KO mice. In summary, elevated PAPP-A expression in glomeruli is associated with diabetic nephropathy in humans and absence of PAPP-A is associated with resistance to the development of indicators of diabetic nephropathy in mice. These data suggest PAPP-A as a potential therapeutic target for diabetic nephropathy.

Pregnancy-associated plasma protein A as an independent mortality predictor in long-term hemodialysis patients

BACKGROUND/AIMS

Pregnancy-associated plasma protein A (PAPP-A) is a biomarker related to vascular damage. The aim of the study was to focus on PAPP-A and related parameters and their relationship to the prognosis of long-term hemodialysis (HD) patients.

METHODS

This is a prospective observational cohort study which included 261 long-term HD patients followed up for 5 years and 66 healthy subjects. PAPP-A, placental growth factor (PlGF), matrix metalloproteinase 2 and 9 (MMP-2, MMP-9), insulin-like growth factor 1 (IGF-1), insulin-like growth factor binding protein-4 (IGFBP-4), and cardiac, nutritional and inflammatory parameters were measured at the beginning of the study and tested as predictors of mortality.

RESULTS

PAPP-A, PlGF, IGF-1, IGFBP-4 and MMP-2 were significantly increased in HD patients compared to controls (PAPP-A 27.6 ± 15.5 mIU/l in HD vs. 9.4 ± 2.5 mIU/l in controls, p < 0.001). Increased PAPP-A was a significant independent predictor of overall mortality and mortality due to infection in the multivariate Cox analysis [HR (95% CI): 1.237 (1.060-1.444), p = 0.007, and 1.416 (1.115-1.798), p = 0.004, per standard deviation, respectively]. PAPP-A was not related to cardiovascular mortality.

CONCLUSION

Increased PAPP-A is a significant independent predictor of overall mortality and mortality due to infection but it was not related to cardiovascular mortality in this study.