The placenta plays a key role in several adverse obstetrical outcomes, such as preeclampsia, intrauterine growth restriction and gestational diabetes mellitus. The early identification of at-risk pregnancies could significantly improve the management, therapy and prognosis of these pregnancies, especially if these at-risk pregnancies are identified in the first trimester. The aim of this review was to summarize the possible biomarkers that can be used to diagnose early placental dysfunction and, consequently, at-risk pregnancies. We divided the biomarkers into proteins and non-proteins. Among the protein biomarkers, some are already used in clinical practice, such as the sFLT1/PLGF ratio or PAPP-A; others are not yet validated, such as HTRA1, Gal-3 and CD93. In the literature, many studies analyzed the role of several protein biomarkers, but their results are contrasting. On the other hand, some non-protein biomarkers, such as miR-125b, miR-518b and miR-628-3p, seem to be linked to an increased risk of complicated pregnancy. Thus, a first trimester heterogeneous biomarkers panel containing protein and non-protein biomarkers may be more appropriate to identify and discriminate several complications that can affect pregnancies.

BACKGROUND: Small-for-gestational-age (SGA), commonly caused by poor placentation, is a major contributor to global perinatal mortality and morbidity. Maternal serum levels of placental protein and angiogenic factors are changed in SGA. Using data from a population-based pregnancy cohort, we estimated the relationships between levels of second-trimester pregnancy-associated plasma protein-A (PAPP-A), placental growth factor (PlGF), and serum soluble fms-like tyrosine kinase-1 (sFlt-1) with SGA.
METHODS: Three thousand pregnant women were enrolled. Trained health workers prospectively collected data at home visits. Maternal blood samples were collected, serum aliquots were prepared and stored at -80℃. Included in the analysis were 1,718 women who delivered a singleton live birth baby and provided a blood sample at 24-28 weeks of gestation. We used Mann-Whitney U test to examine differences of the median biomarker concentrations between SGA (< 10th centile birthweight for gestational age) and appropriate-for-gestational-age (AGA). We created biomarker concentration quartiles and estimated the risk ratios (RRs) and 95% confidence intervals (CIs) for SGA by quartiles separately for each biomarker. A modified Poisson regression was used to determine the association of the placental biomarkers with SGA, adjusting for potential confounders.
RESULTS: The median PlGF level was lower in SGA pregnancies (934 pg/mL, IQR 613-1411 pg/mL) than in the AGA (1050 pg/mL, IQR 679-1642 pg/mL; p < 0.001). The median sFlt-1/PlGF ratio was higher in SGA pregnancies (2.00, IQR 1.18-3.24) compared to AGA pregnancies (1.77, IQR 1.06-2.90; p = 0.006). In multivariate regression analysis, women in the lowest quartile of PAPP-A showed 25% higher risk of SGA (95% CI 1.09-1.44; p = 0.002). For PlGF, SGA risk was higher in women in the lowest (aRR 1.40, 95% CI 1.21-1.62; p < 0.001) and 2nd quartiles (aRR 1.30, 95% CI 1.12-1.51; p = 0.001). Women in the highest and 3rd quartiles of sFlt-1 were at reduced risk of SGA delivery (aRR 0.80, 95% CI 0.70-0.92; p = 0.002, and aRR 0.86, 95% CI 0.75-0.98; p = 0.028, respectively). Women in the highest quartile of sFlt-1/PlGF ratio showed 18% higher risk of SGA delivery (95% CI 1.02-1.36; p = 0.025).
CONCLUSIONS: This study provides evidence that PAPP-A, PlGF, and sFlt-1/PlGF ratio measurements may be useful second-trimester biomarkers for SGA.

Preeclampsia is a common complication of pregnancy. It is a multi-organ disorder that remains one of the main causes of maternal morbidity and mortality. Additionally, preeclampsia leads to many complications that can occur in the fetus or newborn. Preeclampsia occurs in about 1 in 20 pregnant women. This review focuses on the prediction of preeclampsia in women, using various biomarkers, in particular, a factor combining the use of soluble FMS-like tyrosinokinase-1 (sFlt-1) and placental growth factor (PlGF). A low value of the sFlt-1/PlGF ratio rules out the occurrence of preeclampsia within 4 weeks of the test result, and its high value predicts the occurrence of preeclampsia within even 1 week. The review also highlights other factors, such as pregnancy-associated plasma protein A, placental protein 13, disintegrin and metalloprotease 12, ß-human chorionic gonadotropin, inhibin-A, soluble endoglin, nitric oxide, and growth differentiation factor 15. Biomarker testing offers reliable and cost-effective screening methods for early detection, prognosis, and monitoring of preeclampsia. Early diagnosis in groups of women at high risk for preeclampsia allows for quick intervention, preventing the undesirable effects of preeclampsia. However, further research is needed to validate and optimize the use of biomarkers for more accurate prediction and diagnosis. This article aims to review the role of biomarkers, including the sFlt1/PlGF ratio, in the prognosis and management of preeclampsia.

OBJECTIVE: This study aimed to determine the association of first-trimester maternal serum biomarkers with preterm birth (PTB), fetal growth restriction (FGR) and hypertensive disorders of pregnancy (HDP) in twin pregnancies.
METHODS: This is a retrospective cohort study of twin pregnancies followed at Maternidade Dr. Alfredo da Costa, Lisbon, Portugal, between January 2010 and December 2022. We included women who completed first-trimester screening in our unit and had ongoing pregnancies with two live fetuses, and delivered after 24 weeks. Maternal characteristics, pregnancy-associated plasma protein-A (PAPP-A) and β-human chorionic gonadotropin (β-hCG) levels were analyzed for different outcomes: small for gestational age (SGA), gestational hypertension (GH), early and late-onset pre-eclampsia (PE), as well as the composite outcome of PTB associated with FGR and/or HDP. Univariable, multivariable logistic regression analyses and receiver-operating characteristic curve were used.
RESULTS: 466 twin pregnancies met the inclusion criteria. Overall, 185 (39.7%) pregnancies were affected by SGA < 5th percentile and/or HDP. PAPP-A demonstrated a linear association with gestational age at birth and mean birth weight. PAPP-A proved to be an independent risk factor for SGA and PTB (< 34 and < 36 weeks) related to FGR and/or HDP. None of the women with PAPP-A MoM > 90th percentile developed early-onset PE or PTB < 34 weeks.
CONCLUSIONS: A high serum PAPP-A (> 90th percentile) ruled out early-onset PE and PTB < 34 weeks. Unless other major risk factors for hypertensive disorders are present, these women should not be considered candidates for aspirin prophylaxis. Nevertheless, close monitoring of all TwP for adverse obstetric outcomes is still recommended.

BACKGROUND: Children with pregnancy-associated plasma protein-A2 (PAPP-A2) mutations resulting in low levels of bioactive insulin-like growth factor-1 (IGF1) and progressive postnatal growth retardation have improved growth velocity and height following recombinant human (rh)IGF1 treatment. The present study aimed to evaluate whether Pappa2 deficiency and pharmacological manipulation of GH/IGF1 system are associated with sex-specific differences in growth-related signaling pathways.
METHODS: Plasma, hypothalamus, pituitary gland and liver of Pappa2ko/ko mice of both sexes, showing reduced skeletal growth, and liver of these mice treated with rhGH, rhIGF1 and rhPAPP-A2 from postnatal day (PND) 5 to PND35 were analyzed.
RESULTS: Reduced body and femur length of Pappa2ko/ko mice was associated with increases in: (1) components of IGF1 ternary complexes (IGF1, IGFBP5/Igfbp5, Igfbp3, Igfals) in plasma, hypothalamus and/or liver; and (2) key signaling regulators (phosphorylated PI3K, AKT, mTOR, GSK3β, ERK1/2 and AMPKα) in hypothalamus, pituitary gland and/or liver, with Pappa2ko/ko females having a more prominent effect. Compared to rhGH and rhIGF1, rhPAPP-A2 specifically induced: (1) increased body and femur length, and reduced plasma total IGF1 and IGFBP5 concentrations in Pappa2ko/ko females; and (2) increased Igf1 and Igf1r levels and decreased Ghr, Igfbp3 and Igfals levels in the liver of Pappa2ko/ko females. These changes were accompanied by lower phospho-STAT5, phospho-AKT and phospho-ERK2 levels and higher phospho-AMPK levels in the liver of Pappa2ko/ko females.
CONCLUSIONS: Sex-specific differences in IGF1 system and signaling pathways are associated with Pappa2 deficiency, pointing to rhPAPP-A2 as a promising drug to alleviate postnatal growth retardation underlying low IGF1 bioavailability in a female-specific manner.
Understanding the physiological role of pregnancy-associated plasma protein-A2 (PAPP-A2), a proteinase involved in the insulin-like growth factor-1 (IGF1) availability to regulate growth, could provide insight into new treatments for patients with short stature and skeletal abnormalities. Although progressive postnatal growth retardation in patients with PAPP-A2 mutations can differ between males and females, we do not know the underlying differences in IGF1 system and signaling, and their response to treatment that contribute to growth improvement. The present study examines whether Pappa2 deficiency and pharmacological administration of rhGH, rhIGF1 and rhPAPP-A2 are associated with sex-specific differences in IGF1 ternary complexes and IGF1 signaling pathways. Reduced body and femur length of Pappa2-deficient mice was associated with sex- and tissue-specific alteration of IGF ternary/binary complexes and IGF1 signaling pathways. rhPAPP-A2 treatment induced female-specific increase in body and femur length and reduction in IGF ternary/binary complexes through STAT5-AKT-ERK2-AMPK signaling pathways in liver. The involvement of PAPP-A2 in sex-based growth physiology supports the use of promising drugs to alleviate postnatal growth retardation underlying low IGF1 bioavailability in a female-specific manner.

Pregnancy-associated plasma protein-A (PAPP-A) and PAPP-A2 modulate insulin-like growth factor (IGF) action and are inhibited by the stanniocalcins (STC1 and STC2). We previously demonstrated increased PAPP-A and IGF activity in ascites from women with ovarian carcinomas. In this prospective, longitudinal study of 107 women with ovarian cancer and ascites accumulation, we determined corresponding serum and ascites levels of IGF-1, IGF-2, PAPP-A, PAPP-A2, STC1, and STC2 and assessed their relationship with mortality. As compared to serum, we found highly increased ascites levels of PAPP-A (51-fold) and PAPP-A2 (4-fold). Elevated levels were also observed for IGF-1 (12%), STC1 (90%) and STC2 (68%). In contrast, IGF-2 was reduced by 29% in ascites. Patients were followed for a median of 38.4 months (range: 45 days to 8.9 years), during which 73 patients (68.2%) died. Overall survival was longer for patients with high serum IGF-1 (hazard ratio (HR) per doubling in protein concentration: 0.60, 95% CI: 0.40-0.90). However, patients with high ascites levels of IGF-1 showed a poorer prognosis (HR: 2.00 (1.26-3.27)). High serum and ascites IGF-2 levels were associated with increased risk of mortality (HR: 2.01 (1.22-3.30) and HR: 1.78 (1.24-2.54), respectively). Similarly, serum PAPP-A2 was associated with mortality (HR: 1.26 (1.08-1.48)). Our findings demonstrate the presence and activity of the IGF system in the local tumor ecosystem, which is likely a characteristic feature of malignant disease and plays a role in its peritoneal dissemination. The potential clinical implications are supported by our finding that serum levels of the proteins are associated with patient prognosis.

Pregnancy associated plasma protein-A (PAPP-A) plays an integral role in breast cancer (BC), especially triple negative breast cancer (TNBC). This subtype accounts for the most aggressive BC, possesses high tumor heterogeneity, is least responsive to standard treatments and has the poorest clinical outcomes. There is a critical need to address the lack of effective targeted therapeutic options available. PAPP-A is a protein that is highly elevated during pregnancy. Frequently, higher PAPP-A expression is detected in tumors than in healthy tissues. The increase in expression coincides with increased rates of aggressive cancers. In BC, PAPP-A has been demonstrated to play a role in tumor initiation, progression, metastasis including epithelial-mesenchymal transition (EMT), as well as acting as a biomarker for predicting patient outcomes. In this review, we present the role of PAPP-A, with specific focus on TNBC. The structure and function of PAPP-A, belonging to the pappalysin subfamily, and its proteolytic activity are assessed. We highlight the link of BC and PAPP-A with respect to the IGFBP/IGF axis, EMT, the window of susceptibility and the impact of pregnancy. Importantly, the relevance of PAPP-A as a TNBC clinical marker is reviewed and its influence on immune-related pathways are explored. The relationship and mechanisms involving PAPP-A reveal the potential for more treatment options that can lead to successful immunotherapeutic targets and the ability to assist with better predicting clinical outcomes in TNBC.

OBJECTIVE: This study aimed to investigate the effects of low-dose radiation on the abdominal aorta of mice and vascular endothelial cells.
METHODS: Wild-type and tumor-bearing mice were exposed to 15 sessions of low-dose irradiation, resulting in cumulative radiation doses of 187.5, 375, and 750 mGy. The effect on the cardiovascular system was assessed. Immunohistochemistry analyzed protein expressions of PAPP-A, CD62, P65, and COX-2 in the abdominal aorta. Microarray technology, Gene Ontology analysis, and pathway enrichment analysis evaluated gene expression changes in endothelial cells exposed to 375 mGy X-ray. Cell viability was assessed using the Cell Counting Kit 8 assay. Immunofluorescence staining measured γ-H2AX levels, and real-time polymerase chain reaction quantified mRNA levels of interleukin-6 (IL-6), ICAM-1, and Cx43.
RESULTS: Hematoxylin and eosin staining revealed thickening of the inner membranes and irregular arrangement of smooth muscle cells in the media membrane at 375 and 750 mGy. Inflammation was observed in the inner membranes at 750 mGy, with a clear inflammatory response in the hearts of tumor-bearing mice. Immunohistochemistry indicated increased levels of PAPP-A, P65, and COX-2 post-irradiation. Microarray analysis showed 425 up-regulated and 235 down-regulated genes, associated with processes like endothelial cell-cell adhesion, IL-6, and NF-κB signaling. Cell Counting Kit 8 assay results indicated inhibited viability at 750 mGy in EA.hy926 cells. Immunofluorescence staining demonstrated a dose-dependent increase in γ-H2AX foci. Reverse transcription quantitative PCR results showed increased expression of IL6, ICAM-1, and Cx43 in EA.hy926 cells post 750 mGy X-ray exposure.
CONCLUSIONS: Repeated low-dose ionizing radiation exposures triggered the development of pro-atherosclerotic phenotypes in mice and damage to vascular endothelial cells.

Miscarriages affect 50-70% of all conceptions and 15-20% of clinically recognized pregnancies. Recurrent pregnancy loss (RPL, ≥2 miscarriages) affects 1-5% of recognized pregnancies. Nevertheless, our knowledge about the etiologies and pathophysiology of RPL is incomplete, and thus, reliable diagnostic/preventive tools are not yet available. Here, we aimed to define the diagnostic value of three placental proteins for RPL: human chorionic gonadotropin free beta-subunit (free-β-hCG), pregnancy-associated plasma protein-A (PAPP-A), and placental growth factor (PlGF). Blood samples were collected from women with RPL (n = 14) and controls undergoing elective termination of pregnancy (n = 30) at the time of surgery. Maternal serum protein concentrations were measured by BRAHMS KRYPTOR Analyzer. Daily multiple of median (dMoM) values were calculated for gestational age-specific normalization. To obtain classifiers, logistic regression analysis was performed, and ROC curves were calculated. There were differences in changes of maternal serum protein concentrations with advancing healthy gestation. Between 6 and 13 weeks, women with RPL had lower concentrations and dMoMs of free β-hCG, PAPP-A, and PlGF than controls. PAPP-A dMoM had the best discriminative properties (AUC = 0.880). Between 9 and 13 weeks, discriminative properties of all protein dMoMs were excellent (free β-hCG: AUC = 0.975; PAPP-A: AUC = 0.998; PlGF: AUC = 0.924). In conclusion, free-β-hCG and PAPP-A are valuable biomarkers for RPL, especially between 9 and 13 weeks. Their decreased concentrations indicate the deterioration of placental functions, while lower PlGF levels indicate problems with placental angiogenesis after 9 weeks.

The pappalysins pregnancy associated plasma protein-A (PAPP-A) and -A2 (PAPP-A2) act as proteinases of insulin-like growth factor-1 (IGF-1) binding proteins, while stanniocalcin-2 (STC2) was identified as a pappalysin inhibitor. While there is some evidence from studies in children and adolescents, it is unclear whether these molecules are related to concentrations of IGF-1 and its binding proteins in adults. We investigated cross-sectionally the association of circulating PAPP-A, PAPP-A2 and STC2 with IGF-1 and its binding proteins (IGFBPs) in 394 adult pretest participants (20-69 years) of the German National Cohort Berlin North study center. Plasma PAPP-A, PAPP-A2, total and free IGF-1, IGFBP-1, IGFBP-2, IGFBP-3, IGFBP-5 and STC2 were measured by ELISAs. The associations of PAPP-A, PAPP-A2 and STC2 with IGF-1 or IGFBPs were investigated using multivariable linear regression analyses adjusting for age, sex, body mass index and pretest phase. We observed significant inverse associations of PAPP-A2 (difference in concentrations per 0.5 ng/mL higher PAPP-A2 levels) with total IGF-1 (- 4.3 ng/mL; 95% CI - 7.0; - 1.6), the IGF-1:IGFBP-3 molar ratio (- 0.34%; 95%-CI - 0.59; - 0.09), but not free IGF-1 and a positive association with IGFBP-2 (11.9 ng/mL; 95% CI 5.0; 18.8). PAPP-A was not related to total or free IGF-1, but positively associated with IGFBP-5. STC2 was inversely related to total IGF-1, IGFBP-2 and IGFBP-3 and positively to IGFBP-1. This first investigation of these associations in a general adult population supports the hypothesis that PAPP-A2 as well as STC2 play a role for IGF-1 and its binding proteins, especially for total IGF-1. The role of PAPP-A2 and STC2 for health and disease in adults warrants further investigation.