sFlt-1 Research Articles

Would the utilization of sFlt-1/PlGF ratio in clinical practice prevent unnecessary hospital admissions of cases with preeclampsia?

ABSTRACT Objectives Preeclampsia (PET) is a serious pregnancy complication with potential adverse maternal and fetal outcomes. Recent research has examined the soluble fms-like tyrosine kinase 1 (sFlt-1)/placental growth factor (PlGF) ratio for predicting PET. The study aimed to assess the efficacy of the sFlt-1/PlGF ratio in ruling out unnecessary hospital admission and PET. Methods sFlt-1/PlGF ratio was performed in patients as clinically indicated. Results The sFlt-1/PlGF ratio at a cutoff value of 51 predicted hospital admission with AUC, PPV, NPV, sensitivity, and specificity of 85%, 44%, 98%, 88%, and 85%, respectively. Additionally, at a cutoff value of 38, the sFlt-1/PlGF ratio predicted the short-term development of PET with PPV, NPV, sensitivity, and specificity of 42%, 100%, 100%, and 81%, respectively. The PlGF alone at a cutoff value of 193.36 predicted hospital admission with AUC, PPV, NPV, sensitivity, and specificity of 87%, 80%, 97%, 67%, and 98%, respectively. Moreover, at a cutoff value of 51.35, the PlGF alone predicted the development of PET with PPV, NPV, sensitivity, and specificity of 54%, 98%, 88%, and 90%, respectively. There was a significant association between a high sFlt-1/PlGF ratio and developing PET. Conclusion The sFlt-1/PlGF ratio and PlGF are promising for ruling out PET and hospital admission in pregnant women.

Immunoexpression of placental growth factor (PlGF) and soluble FMS-like tyrosine kinase 1 (sFlt-1) in the placental bed of preeclamptic women of African ancestry living with HIV infection

Preeclampsia, a severe pregnancy complication linked to defective placentation, poses significant maternal risks and is characterized by dysregulated angiogenic factors, including placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1). Women with HIV/AIDS and receiving ART may face an increased susceptibility to preeclampsia development due to immunological and angiogenic imbalance. This study investigates the immunoexpression of these factors in the context of HIV-associated preeclampsia, utilizing morphometric image analysis. The study cohort comprised 180 women, including 60 normotensive and 120 preeclamptic participants, further stratified by HIV status and gestational age (early-onset PE [EOPE] < 34 weeks and late-onset PE [LOPE] ≥ 34 weeks). Placental bed tissues were immunostained with mouse anti-human sFlt-1 and PlGF antibodies, and the results were analyzed using Zeiss Axio-Vision and GraphPad Prism software. sFlt-1 levels showed no significant overall difference between preeclamptic and normotensive women (p = 0.8661), though slightly increased in the preeclamptic myometrium, independent of HIV status. However, sFlt-1 levels were significantly higher in EOPE compared to both normotensive and LOPE groups. PlGF immunostaining also showed no significant overall difference (p = 0.7387) but was notably lower in preeclamptic pregnancies and significantly higher in EOPE compared to LOPE. HIV status did not significantly impact sFlt-1 or PlGF levels, although sFlt-1 was slightly higher in HIV-negative women, while PlGF was marginally higher in HIV-positive women. These findings highlight the complex role of angiogenic factors in preeclampsia pathophysiology and suggest that antiretroviral therapies (ARTs) may contribute to the dysregulation of these factors due to a heightened immune milieu.

Mid-Trimester Uterine Artery Doppler for Aspirin Discontinuation in Pregnancies at High Risk for Preterm Preeclampsia: Post Hoc Analysis of StopPRE Trial

(BJOG. 2024;131(3):334–342. doi: 10.1111/1471-0528.17631) Preeclampsia (PEC) is characterized by hypertension and proteinuria or organ dysfunction after 20 weeks of gestation. The cause of the condition has not been fully elucidated; however, PEC is associated with a defect in the development of the placenta in early-onset patients. In unaffected individuals, uterine artery flow impedance (UtA) decreases during early gestation through week 24. However, if pulsatility index (PI) in UtA remains high, it is a sign of maladaptation and is commonly found in patients with preterm PEC. An additional consequence of impaired placentation is uteroplacental ischemia, during which the levels of placental growth factor (PIGF) are decreased and soluble fms-like tyrosine kinase-1 (sFlt-1) increases. In screening first trimester patients for risk of PEC, UtAPI and PIGF may be used. Clinicians prescribe aspirin daily as a preventative measure in patients who screen at risk for PEC. Although the incidence of PEC greatly decreases with this treatment, it is also noteworthy that screening for risk of PEC during the first trimester results in a high false positive rate. Thus, most women pre-emptively receiving aspirin for PEC are false positives. The authors previously performed a study where aspirin was discontinued in patients between 24 and 28 weeks of gestation with a normal sFlt-1/PlGF ratio of ≤38, identifying false positives cases. Although this study showed promising results, the ratio may not be available for use in every clinic. Thus, in this study, the authors examine whether UtAPI can be a correlate for these angiogenic factors and act as an alternative screening measure at 24 to 28 weeks of gestation with the same purpose to discontinue aspirin and assess incidence of preterm PEC.

Current preeclampsia prediction model and biomarker

Preeclampsia (PE) is a serious hypertensive disorder that occurs during pregnancy and is often accompanied by proteinuria (excessive protein in the urine), posing significant risks to both maternal and neonatal health worldwide. PE is a leading cause of maternal and neonatal morbidity and mortality and is notably challenging to predict due to its unpredictable nature and steadily rising incidence rates globally. As a result, substantial efforts have been directed toward developing predictive models and identifying biomarkers to assess the risk and progression of PE. However, existing models vary widely in their design, methodologies, and efficacy. Current prediction models recommended by notable organizations, including the National Institute for Health and Care Excellence (NICE), the American College of Obstetricians and Gynecologists (ACOG), the Fetal Medicine Foundation (FMF), and the World Health Organization (WHO), generally involve screening based on maternal characteristics and known risk factors. These include parameters such as maternal age, body mass index (BMI), number of pregnancies and births, blood pressure, and uterine arterial pulse index (UtA-PI). Additionally, biomarkers like mean arterial pressure (MAP), UtA-PI, and the ratio of soluble fms-like tyrosine kinase-1 to placental growth factor (sFlt-1/PlGF) are employed to improve predictive accuracy. Despite the diversity of predictive models and biomarkers, there is no consensus on the optimal model for PE prediction, largely due to the limitations in comparative studies and the challenges involved in cross-study comparisons. However, literature suggests that the FMF model demonstrates superior detection capacity compared to other predictive models.

Modified lipoprotein-induced sFlt1 production in human placental trophoblasts is mediated by protein kinase C

BackgroundPreeclampsia is prevalent in women with diabetes, but the mechanism is unclear. We previously found that oxidized, glycated lipoproteins robustly upregulated soluble fms-like tyrosine kinase-1 (sFlt1), a key mediator of preeclampsia. Here, we determined the role of protein kinase C (PKC) and its subtypes in sFlt1 regulation in placental trophoblasts, and whether this mechanism might mediate the effect of modified lipoproteins. MethodsCultured human HTR8/SVneo and BeWo trophoblasts were treated with the PKC activator phorbol-12-myristate-13-acetate (PMA) for 24h, ± PKC inhibitors GF109203X (general), Ro31-8220 (PKCα-selective), LY333531 (PKCβ-selective) and rottlerin (PKCδ-selective). The effect of ‘heavily oxidized, glycated’ low-density lipoproteins (HOG-LDL) vs. native LDL (N-LDL), ± high glucose (30 mM), was evaluated in HTR8/SVneo cells. sFlt1 secretion (ELISA), mRNA expression (RT-qPCR), and cellular PKC activity were measured. ResultsPMA stimulated robust sFlt1 release and mRNA expression in both cell lines; these effects were inhibited by GF109203X, Ro31-8220 and LY333531 in a concentration-dependent manner. Rottlerin inhibited sFlt1 in BeWo, but modestly enhanced it in HTR8/SVneo cells. HOG-LDL enhanced PKC activity vs. N-LDL in HTR8/SVneo cells. Also, HOG-LDL, but not high glucose, significantly increased sFlt1 secretion and mRNA expression; this response was inhibited by GF109203X, Ro31-8220 and LY333531 at concentrations comparable to those that blocked PMA induction of sFlt1. ConclusionModified lipoproteins upregulate sFlt1 in trophoblasts via a PKC-mediated mechanism, involving at least α and β isoforms. The data suggest potential therapeutic targets to reduce the risk of preeclampsia in women with diabetes.

Irisin Improves Preeclampsia by Promoting Embryo Implantation and Vascular Remodeling.

Preeclampsia is a pregnancy-specific disorder with unclear pathogenesis. Irisin, a recently identified exercise-induced factor, significantly influences lipid metabolism and cardiovascular function. Nonetheless, its role in trophoblast development during human placentation and the related intracellular signaling pathways remain poorly understood. We assessed peripheral blood irisin expression in early pregnancy among patients with preeclampsia and its correlation with key clinical indicators. In trophoblast cell lines and mice, we used exogenous irisin and viral knockdown to investigate functional changes. Phosphorylation-specific antibody arrays and dual-luciferase reporter assays were used to explore downstream molecular mechanisms, which were subsequently validated in trophoblast cell lines and relevant gene knockout mice. In early pregnancy, patients with preeclampsia exhibit decreased peripheral blood irisin levels, occurring earlier than traditional predictive markers, such as PLGF (placental growth factor) and sFlt-1 (soluble fms-like tyrosine kinase-1). Furthermore, irisin concentration is positively correlated with proteinuria and abnormal blood pressure during pregnancy. Exogenous irisin significantly enhanced trophoblast cell migration, invasion, and proliferation while inhibiting apoptosis. It also increased STAT (signal transducers and activators of transcription) 4 phosphorylation and its binding to the GLUT (glucose transporter)-3 promoter, resulting in elevated GLUT-3 expression and glucose uptake in trophoblast cells. In vivo, increased peripheral irisin promoted embryo implantation, vascular remodeling, and enhanced glucose uptake, whereas reduced irisin resulted in a preeclampsia-like phenotype characterized by elevated blood pressure, proteinuria, renal-placental dysfunction, adipose accumulation, and restricted fetal growth. Peripheral irisin improves preeclampsia by promoting embryo implantation and vascular remodeling through the activation of the STAT4/GLUT-3 pathway. Reduced peripheral irisin may contribute to preeclampsia-like pathologies. This study supports the advocacy for appropriate exercise during early pregnancy and provides new insights for preeclampsia prevention.

Effect of aspirin on biomarker profile in women at high-risk for preeclampsia

There is limited evidence in the literature regarding the temporal changes of preeclampsia-related biomarkers during pregnancy in high-risk women who develop preeclampsia despite the administration of aspirin prophylaxis. To compare the temporal changes in mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), placental growth factor (PlGF), and soluble fms-like tyrosine kinase-1 (sFlt-1) across gestation in women screened high-risk for preterm preeclampsia receiving aspirin prophylaxis and low-risk women without aspirin treatment. This was a prospective longitudinal nested case-control study of 2007 women with singleton pregnancies who participated in the first-trimester screen-and-prevent program for preeclampsia at the Prince of Wales Hospital, Hong Kong SAR, China, between January 2020 and May 2023. The risk of developing preterm preeclampsia was determined using the Fetal Medicine Foundation triple test (maternal factors, MAP, UtA-PI and PlGF). High-risk women (adjusted risk ≥1:100) were administered a daily dose of aspirin at either 100 or 160 mg according to maternal weight, starting before 16 weeks until 36 weeks or until delivery or the onset of preeclampsia before 36 weeks. Low-risk women were matched based on maternal age, weight, and the date of the scan. The participants were followed up at 12-15+6, 20-24+6 and 30-37+6 weeks to measure MAP, UtA-PI, PlGF and sFlt-1 at each visit. The level of biomarker was expressed as multiple of median (MoM). Log10 transformation was applied to make the data Gaussian distribution prior to statistical analysis. A linear mixed-effects analysis was performed to compare the longitudinal changes of these biomarkers across gestation between the study groups. Our study involved 403 low-risk women without preeclampsia, 1471 high-risk women without preeclampsia, and 133 high-risk women who developed preeclampsia. The low-risk group had significantly lower estimated marginal mean log10 MAP MoM, log10 UtA-PI MoM, log10 sFlt-1 MoM and higher estimated marginal mean log10 PlGF MoM across gestation than the high-risk groups (p values <0.001). Among high-risk women, those who developed preeclampsia experienced a significantly higher estimated marginal mean log10 MAP MoM (0.06378 vs 0.02985; p<0.001), log10 UtA-PI MoM (0.08651 vs 0.02226; p<0.001), log10 sFlt-1 MoM (0.13204 vs 0.01234; p<0.001) and lower estimated marginal mean log10 PlGF MoM (-0.33504 vs -0.16388; p<0.001) across gestation in comparison to those without preeclampsia. In the individual gestational timepoint analysis, compared to high-risk women without preeclampsia, those who developed preeclampsia experienced higher log10 MAP MoM in all three trimesters, higher log10 UtA-PI MoM and lower log10 PlGF MoM in the second- and third-trimesters, and higher log10 sFlt-1 MoM in the third-trimester. The study has demonstrated that high-risk women who develop preeclampsia experience consistently high MAP level from the first-trimester and remain unchanged during pregnancy, high UtA-PI level and low PlGF level starting from the second-trimester, and high sFlt-1 level in the third-trimester compared to those who do not develop preeclampsia despite the administration of low-dose aspirin. These findings underscore the role of these biomarkers in further risk stratification for the development of preeclampsia among high-risk women following aspirin administration.

Placental histopathology in early-onset fetal growth restriction with use of sildenafil, a secondary analysis of the Dutch STRIDER study

ObjectivesPlacental pathology lesions are common in early-onset fetal growth restriction (eoFGR). Therapeutic interventions to improve eoFGR outcomes are needed. In the international STRIDER trials (Sildenafil Therapy In Dismal prognosis Early-onset intrauterine growth Restriction) sildenafil didn't improve perinatal outcomes of eoFGR. We aimed to study the underlying placental pathology in the Dutch STRIDER trial and the effects of sildenafil on placental histopathology by describing the associations with sildenafil treatment, placental-dysfunction serum biomarkers and markers of oxidative stress. MethodsThe Dutch STRIDER trial was a randomized controlled trial of sildenafil versus placebo in 216 singleton pregnancies complicated by eoFGR, included between 20+0- and 29+6-weeks’ gestation. In 158 cases, placental histology was available. Lesions were classified independently by three perinatal pathologists blinded for clinical data, according to the international criteria of the Amsterdam Placental Workshop Group Consensus Statement. Blood samples taken at inclusion were analyzed for free thiols (FT), placental growth factor (PlGF) and soluble FMS-like tyrosine kinase-1 (sFlt-1, n = 85). ResultsThe ‘big four’ placental lesions (maternal and fetal vascular malperfusion, and chronic or acute inflammatory lesions) were equally distributed in both groups. However, massive perivillous fibrin deposition (MPFD) and chronic histiocytic intervillositis (CHIV) were less common in the sildenafil-treated group compared to the placebo-treated group (p = 0.026 and p = 0.043). FT, PlGF and sFlt-1 at inclusion were not discriminative for placental lesions. ConclusionsSildenafil had no effect on common placental lesions. The lower incidence of MPFD and CHIV after sildenafil exposure merits more research on the interaction between sildenafil and the immune system.

β3-adrenergic agonist counters oxidative stress and Na+-K+ pump inhibitory S-glutathionylation of placental cells: implications for preeclampsia.

Oxidative stress from placental ischemia/reperfusion and hypoxia/reoxygenation (H/R) in preeclampsia is accompanied by Na+-K+ pump inhibition and S-glutathionylation of its β1 subunit (GSS-β1), a modification that inhibits the pump. β3-adrenergic receptor (β3-AR) agonists can reverse GSS-β1. We examined the effects of the agonist CL316,243 on GSS-β1 and sources of H/R-induced oxidative stress in immortalized first-trimester human trophoblast (HTR-8/SVneo) and freshly isolated placental explants from normal-term pregnancies. H/R increased GSS-β1 and, reflecting compromised α1/β1 subunit interaction, reduced α1/β1 pump subunit coimmunoprecipitation. H/R increased p47phox/p22phox NADPH oxidase subunit coimmunoprecipitation, reflecting membrane translocation of cytosolic p47phox that is needed to activate NADPH oxidase. Fluorescence of O2•--sensitive dihydroethidium increased in parallel. H/R increased S-glutathionylation of endothelial nitric oxide synthase (GSS-eNOS) that uncouples nitric oxide synthesis toward the synthesis of O2•- and reduced trophoblast migration. Oxidative stress induced by tumor necrosis factor α increased soluble fms-like tyrosine kinase receptor 1 (sFlt-1) trophoblast release, a marker of preeclampsia, and reduced trophoblast integration into endothelial cellular networks. CL316,243 eliminated H/R-induced GSS-β1 and decreases of α1/β1 subunit coimmunoprecipitation, eliminated NADPH oxidase activation and increases in GSS-eNOS, restored trophoblast migration, eliminated increased sFlt-1 release, and restored trophoblast integration in endothelial cell networks. H/R-induced GSS-β1, α1/β1 subunit coimmunoprecipitation, and NADPH oxidase activation of placental explants reflected effects of H/R for trophoblasts and CL316,243 eliminated these changes. We conclude a β3-AR agonist counters key pathophysiological features of preeclampsia in vitro. β3 agonists already in human use for another purpose are potential candidates for repurposing to treat preeclampsia.NEW & NOTEWORTHY H/R-induced oxidative stress and deficient NO-dependent placentation are features of preeclampsia, yet nonspecific antioxidants and NO donors are ineffective. Here, activation of the microdomain-confined signaling pathway with an agonist for the eNOS-coupled β3-AR eliminates inhibitory glutathionylation of the Na+-K+ pump's β1 subunit, uncoupling of eNOS, and activation of NADPH oxidase that are sources of H/R-induced oxidative stress. The agonist also eliminates H/R-induced inhibition of trophoblast migration and their integration into an endothelial network.

Soluble FLT-1 in angiogenesis: pathophysiological roles and therapeutic implications.

Fine-tuning angiogenesis, the development of new blood vessels, is essential for maintaining a healthy circulatory and lymphatic system. The small glycoprotein vascular endothelial growth factors (VEGF) are the key mediators in this process, binding to their corresponding membrane-bound VEGF receptors (VEGFRs) to activate angiogenesis signaling pathways. These pathways are crucial throughout human life as they are involved in lymphatic and vascular endothelial cell permeability, migration, proliferation, and survival. Neovascularization, the formation of abnormal blood vessels, occurs when there is a dysregulation of angiogenesis and can result in debilitating disease. Hence, VEGFRs have been widely studied to understand their role in disease-causing angiogenesis. VEGFR1, also known as Fms-like tyrosine kinase-1 (FLT-1), is also found in a soluble form, soluble FLT-1 or sFLT-1, which is known to act as a VEGF neutralizer. It is incorporated into anti-VEGF therapy, designed to treat diseases caused by neovascularization. Here we review the journey of sFLT-1 discovery and delve into the alternative splicing mechanism that creates the soluble receptor, its prevalence in disease states, and its use in current and future potential therapies.

Neutrophil pyroptosis regulates corneal wound healing and post-injury neovascularisation.

The cornea is a unique structure that maintains its clarity by remaining avascular. Corneal injuries can lead to neovascularisation (CNV) and fibrosis and are the third most common cause of blindness worldwide. Corneal injuries induce an immune cell infiltration to initiate reparative processes. However, inflammation caused by sustained immune cell infiltration is known to be detrimental and can delay the healing process. This study was designed to understand the potential role of neutrophil and epithelial cell crosstalk in post-injury CNV. Western blotting and immunostaining assays demonstrated that neutrophils infiltrated corneas and underwent pyroptosis following acute alkali injury. In vivo studies showed that genetic ablation of Gasdermin D (GsdmD), a key effector of pyroptosis, enhanced corneal re-epithelialisation and suppressed post-injury CNV. In vitro co-culture experiments revealed that interleukin-1β (IL-1β) was released from pyroptotic neutrophils which suppressed migration of murine corneal epithelial cells. Real-time RT-PCR and immunostaining assays identified two factors, Wnt5a and soluble fms-like tyrosine kinase-1 (sflt-1), highly expressed in newly healed epithelial cells. sflt-1 is known to promote corneal avascularity. Bone marrow transplantation, antibody mediated neutrophil depletion, and pharmacological inhibition of pyroptosis promoted corneal wound healing and inhibited CNV in an in vivo murine corneal injury model. Taken together, our study reveals the importance of neutrophil/epithelium crosstalk and neutrophil pyroptosis in response to corneal injuries. Inhibition of neutrophil pyroptosis may serve as a potential treatment to promote corneal healing without CNV. Neutrophil pyroptosis delays re-epithelialization after corneal injury Compromised re-epithelialization promotes corneal neovascularization after injury Inhibition of post-injury pyroptosis could be an effective therapy to promote corneal wound healing.

Investigation of PLGF, sFlt-1 expression in Plasenta Previa, Plasenta Accreta and Normotensive Plasentas in the 3rd Trimester of Pregnancy

Background: We aimed to immunohistochemically examine the expression level of Placental growth factor (PLGF) and Soluble FMS-like tyrosine kinase-1 (sFlt-1) proteins in normotensive, Placenta accreta (PA) and Placenta previa (PP). Materials and Methods: Three groups were created for the study: 20 Nomotensive placentas, 20 PP and 20 PA from women diagnosed with placenta samples. 4-6 μm thick sections were taken from the placentas, PLGF and sFlt-1 immunostaining were applied to the obtained sections, and their expression intensities and localizations in the tissues were determined. Results: As a result of our observations, normotensive placenta group; sFlt-1 expression was observed in hofbauer cells and syncytial nodes and PLGF positive expression was observed in nuclei of muscle cells in some tunica media region. PP and PA group; sFlt-1 expression was positive in decidua cells, hofbauer cells and dilated vascular endothelium. PP and PA group; negative PLGF expression was observed in syncytial nodes and positive PLGF expression was observed in hofbauer cells and endothelial cells. There was a significant difference between normotensive, PP and PA groups (p&amp;lt;0.05). Conclusions: It can be thought that sFlt-1 and PLGF may be important signal stimulators and markers in the trophoblastic degeneration, apoptotic cells, increase in angiogenesis and imbalance in implanta-tion seen in cases of PP and PA.

Impaired Endothelium-Dependent Vasodilation and Increased Levels of Soluble Fms-like Tyrosine Kinase-1 Induced by Reduced Uterine Perfusion Pressure in Pregnant Rats: Evidence of Protective Effects with Sodium Nitrite Treatment in Preeclampsia.

Preeclampsia (PE) is a hypertensive disorder of pregnancy and is associated with increases in soluble fms-like tyrosine kinase-1 (sFlt-1) and reductions in nitric oxide (NO) levels. Placental ischemia and hypoxia are hypothesized as initial pathophysiological events of PE. Nitrite (NO metabolite) may be recycled back to NO in ischemic and hypoxic tissues. Therefore, this study examined the sodium nitrite effects in an experimental model of PE. Pregnant rats received saline (Preg group) or sodium nitrite (Preg + Na-Nitrite group). Pregnant rats submitted to the placental ischemia received saline (RUPP group) or sodium nitrite (RUPP + Na-Nitrite group). Blood pressure, placental and fetal weights, and the number of pups were recorded. Plasma levels of NO metabolites and sFlt-1 were also determined. Vascular and endothelial functions were also measured. Blood pressure, placental and fetal weights, the number of pups, NO metabolites, sFlt-1 levels, vascular contraction, and endothelium-dependent vasodilation in the RUPP + Na-Nitrite rats were brought to levels comparable to those in Preg rats. In conclusion, sodium nitrite may counteract the reductions in NO and increases in sFlt-1 levels induced by the placental ischemia model of PE, thus suggesting that increased blood pressure and vascular and endothelial dysfunctions may be attenuated by sodium nitrite-derived NO.

Placenta may exert fetal protection against maternal high salt diet intake via renin-angiotensin-aldosterone system

ObjectiveThis study investigated the effects of high compared to normal dietary salt intake on fetoplacental vascular function, activity of renin-angiotensin-aldosterone system (RAAS), placental pro- and anti-angiogenic factors and biomarkers of placental remodeling and oxidative stress during healthy uncomplicated pregnancy. Materials and methodsBased on their 24-h sodium excretion pregnant women (37–40 weeks’ gestation) were categorized into three groups: normal salt (NS, <5.75 g/day, N = 12), high salt (HS, 5.75–10.25 g/day, N = 36), and very high salt (VHS, >10.25 g/day, N = 17). Pulsatility (PI) and resistive index of middle cerebral artery (MCA) and umbilical artery, plasma renin activity (PRA), serum aldosterone, soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) concentrations, as well as placental vascular endothelial growth factor C (VEGF-C), oxidative/antioxidative stress markers (TBARS/FRAP) and matrix metalloproteinase 9 (MMP-9) concentration were measured. ResultsPI MCA was significantly decreased in HS/VHS groups compared to NS group. HS/VHS intake did not suppress PRA and aldosterone concentration. Serum PlGF concentration was significantly increased while sFlt-1 concentration and sFlt-1/PlGF ratio were significantly decreased in VHS group compared to NS group. MMP-9, VEGF-C concentration, TBARS and FRAP in placental tissue were similar between study groups. ConclusionsHS/VHS diet does not suppress RAAS during pregnancy; however, it is associated with decreased PI MCA, a significantly decreased sFlt-1/PlGF ratio and unchanged biomarkers of placental remodeling or oxidative stress in healthy pregnant women, suggesting the presence of a possible protective or compensatory mechanism aimed at preserving placental function and pregnancy outcome itself in terms of maternal HS intake.

Maternal Thyroid Function and Biochemical Markers of Placental Function in Early Pregnancy.

A link between maternal thyroid function and the placental biomarkers, soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF), has been brought forward. This study aimed to describe their association in early pregnancy. Retrospective cohort study. Eight hundred and fifty-eight pregnant women from the North Denmark Region, 2013, with blood samples drawn in early pregnancy. Thyroid-stimulating hormone (TSH), free thyroxine (fT4), thyroid-peroxidase antibodies (TPO-Ab), thyroglobulin antibodies (Tg-Ab) (ADVIA Centaur XPT, Siemens Healthineers), sFlt-1 and PlGF (Kryptor Compact, ThermoFisher Scientific) were measured. The association between maternal TSH and fT4 and percentile (pc) levels of sFlt-1 and PlGF (< 25th pc, 25-75th pc, > 75th pc) was evaluated using regression analysis and reported as adjusted beta coefficient (aβ). The frequency of maternal thyroid autoantibodies (TPO-Ab > 60 U/mL or Tg-Ab > 33 U/mL) by pc levels of sFlt-1 and PlGF was compared using chi-squared test. Higher levels (> 75th pc) of sFlt-1 associated with lower TSH (aβ 0.62, 95% CI: 0.51-0.76) and higher fT4 (aβ 1.03, 95% CI: 1.01-1.05). Higher levels of PlGF associated with lower TSH (aβ 0.82, 95% CI: 0.69-0.98), but not with levels of fT4 (aβ 1.00, 95% CI: 0.97-1.02). No association with maternal thyroid autoantibodies was found (TPO-Ab: sFlt-1: p-value 0.5 and PlGF: p-value 0.1; Tg-Ab: sFlt-1: p-value 0.7 and PlGF: p-value 0.1). In a large cohort of Danish pregnant women, higher levels of sFlt-1 and PlGF associated with maternal thyroid function in early pregnancy, while there was no association with maternal thyroid autoantibodies.

A-311 Evaluating the Predictive Value of the sFlt-1/PlGF Ratio in Hypertensive Pregnancies for Preeclampsia

Abstract Background Preeclampsia (PE) is a hypertensive pregnancy disorder affecting around 5% of all pregnancies, and it continues to be a leading cause of maternal and neonatal morbidity and mortality in the United States. The incidence of hypertensive pregnancies is on the rise, attributed to the increasing prevalence of obesity and chronic hypertension. The development of a straightforward diagnostic test to accurately differentiate PE from gestational or chronic hypertension is crucial to avoid unnecessary hospitalizations. Despite the ongoing development of prediction models for PE, conventional clinical and laboratory measures have not been effective in predicting disease progression. Recent research has focused on the ratio of two serum biomarkers: soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF), particularly in patients with a clinical suspicion of PE in acute settings. These studies have shown promise, with many indicating that the sFlt-1/PlGF ratio can effectively predict the presence or absence of PE. This study was conducted to assess the predictive value of the sFlt-1/PlGF ratio in pregnancies complicated by hypertension, aiming to contribute to the early detection and management of PE. Methods Pregnant individuals with hypertensive disorders at or above the age of 18 receiving prenatal care at NewYork-Presbysterian-Weill Cornell Hospital were enrolled in this study. We measured the levels of sFlt-1 and PlGF using fully automated Elecsys immunoassays (Roche Diagnostics). Subsequently, a prospective analysis of the serum sFlt-1/PlGF ratio was performed. A receiver operating characteristic (ROC) curve was used to calculate the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the ratio in predicting PE. To assess the prognostic accuracy of the sFlt-1/PlGF ratio, patients were randomly assigned to a development and a validation cohort at a ratio of 30:70. Results We collected a total of 137 serum samples of hypertensive pregnancies, with all ≥20 weeks of gestational age (GA). Of these, 47 (34.3%) developed PE within 2 weeks. The samples were divided into two cohorts: 98 were included in the development cohort, and 39 in the validation cohort. Within these groups, 34 (34.7%) of the development cohort and 13 (33.3%) of the validation cohort developed PE within 2 weeks, respectively. In the development cohort, the median sFlt-1/PlGF ratio was 85 (Interquartile range, [IQR], 44-164) among pregnant women who developed PE within 2 weeks. This was significantly higher compared to a median ratio of 8 (IQR, 3-35) observed in those who did not develop PE (p&amp;lt;0.001). The area under the ROC curve was 0.87, indicating good discriminative ability. An optimized cutoff ratio of 38 was determined, based on the max of combined sensitivity and specificity. When applied into the validation cohort, this cutoff yields a 90% (95% confidence interval [CI], 70-97) NPV and 58% (95%CI, 37-76) PPV with an 85% sensitivity (95%CI, 58-96) and a 69% specificity (95%CI, 50-83). Conclusions In women with a hypertensive disorder of pregnancy presenting GA≥20 weeks of gestation, the measurement of serum sFlt-1/PlGF ratio demonstrated clinical value in predicting the development of PE.

A-313 Use of the Preeclampsia Ratio in the Prognosis of Preterm Delivery and Adverse Outcomes

Abstract Background Preeclampsia (PE) is a hypertensive disorder of pregnancy that is characterized by high blood pressure and end-organ dysfunction with or without proteinuria after 20 weeks gestation. PE occurs in 6-8% of pregnancies and contributes to significant fetal, neonatal, and maternal morbidity and mortality. The ratio of two angiogenic placental proteins, soluble fms-like tyrosine kinase 1 (sFlt-1) and placental growth factor (PlGF), are used in the management of PE. The purpose of this study was to evaluate use of the sFlt-1/PlGF ratio (PE ratio) generated using the ADVIA Centaur® and Atellica® IM sFlt-1 assay and the ADVIA Centaur and Atellica IM PlGF assays in the prognosis of preterm delivery and adverse outcomes in women presenting with signs and symptoms of PE. Methods A total of 654 females with singleton pregnancies between gestational weeks 20+0 days and 35+6 days and who had signs and symptoms of PE, but without severe features of PE were enrolled at 24 collection sites and followed prospectively for two weeks. Serum samples were collected at enrollment and adverse outcomes that included preterm delivery were prospectively collected within the two weeks after enrollment. Serum samples from approximately half of the population (n=316) were tested in singlicate using the sFlt-1 and PlGF assays on the ADVIA Centaur system in a derivation study that determined the optimal cutoff of the PE ratio in relation to adverse outcome. The remaining serum samples (n=338) were subsequently tested on the ADVIA Centaur system in a cut-off validation study that evaluated the clinical performance (sensitivity [SE], specificity [SP], positive predictive value [PPV], negative predictive value [NPV]) of the PE ratio at the derived cutoff in relation to adverse outcome. Method comparison studies were performed between the ADVIA Centaur versus the Roche Elecsys sFlt-1 and PlGF assays (n=255) and the ADVIA Centaur versus the Atellica IM sFlt-1 and PlGF assays (n=316). Results The rate of maternal adverse outcomes within two weeks was similar in the derivation study (32.3%) and validation study (28.1%). Using a receiver operating characteristic (ROC) curve analysis with the derivation cohort, a derived cutoff of 38 showed optimal clinical performance of the PE ratio in relation to adverse outcome (SE=72.5%, SP=94.7%, PPV=84.6%, NPV=89.5%). Similar clinical performance results of the PE ratio at the cutoff of 38 in relation to adverse outcome were found with the verification cohort (SE=88.42%, SP=87.65%, PPV=73.68%, NPV=95.09%). Weighted Deming regression analysis demonstrated equivalency between the Centaur, Roche, and Atellica PE ratios with correlation coefficients (r) of 0.9242 (Centaur vs Roche) and 0.995 (Centaur vs Atellica). Conclusions Measurement of sFlt-1 and PlGF to determine PE ratio can be performed on either the ADVIA Centaur or Atellica Analyzer and can be used to identify women presenting with PE or signs and symptoms of PE who are at high risk of experiencing an adverse event in the subsequent two weeks. Not available for sale in the U.S.A. The products/features mentioned herein are not commercially available in all countries. Their future availability cannot be guaranteed.

A-308 Placental Growth Factor Kryptor Immunoassay Reveals Quality Control Imprecision and Drift

Abstract Background The utility and value of determining the soluble fms-like tyrosine kinase-1 to placental growth factor (sFlt-1/PlGF) ratio for predicting the likelihood of progression to pre-eclampsia in pregnant women admitted with hypertension are increasingly becoming widely recognized. A key finding of the multi-center PRAECIS trial (NEJM Evid 2022;1(12)) is the observation that sFlt-1/PlGF ratios ≥ 40 correlate with higher risk for adverse maternal outcomes. The sFlt-1 and PlGF immunoassays performed on the ThermoFisher Scientific B·R·A·H·M·S Kryptor autoanalyzer became the first FDA-approved tests in 2023 for determining sFlt-1/PlGF ratio. In this study, an evaluation of the analytical performance of the sFlt-1 and PlGF KRYPTOR immunoassays was performed, which included analyte measuring range (AMR), accuracy, precision, and stability studies. Methods Calibration and QC materials (consisting of lyophilized recombinant human proteins), test reagents and solutions, and consumables were purchased and provided by ThermoFisher Scientific. Analytical runs were performed according to vendor’s instructions by trained medical laboratory scientists. Between-day precision of our two instruments for both immunoassays was assessed by assaying all three levels of sFlt-1 and PlGF QC materials, as well as patient serum pools with low PlGF concentration, once to twice daily for multiple consecutive days. Results While the analytical performance of the sFlt-1 immunoassay was robust and performed according to expectation (within-day CV &amp;lt;1% and between-day CV &amp;lt;3%), the PlGF immunoassay was surprisingly less reliable. Imprecision and inaccuracy of the PlGF immunoassay at the low end of its analytical measurement range was reflected by both sporadically out-of-control between-day measurements of all three QC levels (with target ranges of 24 - 36 pg/mL, 80 - 120 pg/mL, and 320 - 480 pg/mL), as well as slow downward drifts of particularly the low level QC material. In one instance, a downtrend was observed from 28 pg/mL to 14 pg/mL over 6 days, even with fresh reagents, solutions, and calibration. Such shortened stability of the PlGF assay does not meet the vendor’s claims of calibration stability of 15 days and onboard kit stability of 29 days. Using vendor’s provided material, the AMR of both sFlt-1 and PlGF were adequately verified and showed excellent linearity (r2&amp;gt; 0.99). Conclusions Despite low level QC imprecision and drift, the sFlt-1/PlGF ratios determined using the B·R·A·H·M·S Kryptor analyzers are acceptable for clinical use but with the caveat that we will perform batch testing with bracketing QCs and conduct stringent QC monitoring, frequent calibrations, and reduce the onboard kit stability as defined by ThermoFisher Scientific. Our findings serve as a reminder that FDA approval does not preclude thorough verification studies of any assay prior to implementation for clinical use.

Advancing diagnostics: integrating microRNA profiling and protein markers in ectopic pregnancy detection

IntroductionEctopic pregnancy (EP) poses significant health risks, particularly in developing nations, necessitating improved diagnostic methods. This study aimed to explore potential biomarkers for EP diagnosis.MethodsA case–control study was conducted at...

Can Peripheral Arterial Tonometry and Biomarkers Help Identify Women Who Will Have Progressively Worsening Hypertensive Disorders of Pregnancy?

This study aimed to (1) evaluate whether endothelial dysfunction, as measured by peripheral arterial tonometry (PAT) indices and biomarker (soluble fms-like tyrosine kinase-1 [sFLT], brain natriuretic peptide [BNP]) levels at 34 weeks gestation, can predict progression from nonsevere to severe hypertensive disorders of pregnancy (HDPs); and (2) develop a clinical risk model for prediction of progression from nonsevere to severe HDP. We prospectively enrolled patients with a singleton gestation carrying a nonsevere HDP diagnosis. Forty-five participants were enrolled for PAT evaluation and serum collection between 340/7 and 366/7 weeks. PAT indices (e.g., Augmentation Index normalized to a heart rate of 75 bpm [AI75]) and biomarker concentrations were assessed at enrollment. The primary outcome was progression from a nonsevere diagnosis in the late preterm period to a diagnosis of preeclampsia with severe features or superimposed preeclampsia. Statistical analyses included two-sample t-tests, Fisher's exact tests, and multivariate modeling. Thirteen subjects (30%) progressed to severe disease. No significant differences in mean PAT indices between the outcome groups were found. We found a significant difference in mean sFLT values between the two groups (p = 0.02, area under the curve [AUC] of 0.609), but not in mean BNP values. An endothelial dysfunction index (presence of fetal growth restriction, "high" AI75, and positive systolic blood pressure slope) discriminated between progression and nonprogression (p = 0.03, AUC of 0.707). sFLT level was a marker of progression from nonsevere to severe HDP. Further, a novel endothelial dysfunction index discriminated between progression and nonprogression to severe disease with good performance. · HDPs are important causes of morbidity and mortality.. · The sequelae of HDPs are not limited to pregnancy.. · Developing accurate tools to predict severe HDPs is of great clinical importance.. · Our index shows promising performance for predicting progression from nonsevere to severe HDPs..