The 15-Epilipoxin-A4 Pathway with Prophylactic Aspirin in Preventing Preeclampsia: A Longitudinal Cohort Study

The great obstetrical syndromes and the placenta

Although historically pre-eclampsia, preterm birth, abruption, fetal growth restriction and stillbirth have been viewed as clinically distinct entities, a growing body of literature has demonstrated that the placenta and its development is the root cause of many cases of these conditions. This has led to the term 'the great obstetrical syndromes' being coined to reflect this common origin. Although these conditions mostly manifest in the second half of pregnancy, a failure to complete deep placentation (the transition from histiotrophic placentation to haemochorial placenta at 10-18 weeks of gestation via a second wave of extravillous trophoblast invasion), is understood to be key to the pathogenesis of the great obstetrical syndromes. While the reasons that the placenta fails to achieve deep placentation remain active areas of investigation, maternal inflammation and thrombosis have been clearly implicated. From a clinical standpoint these mechanisms provide a biological explanation of how low-dose aspirin, which affects the COX-1 receptor (thrombosis) and the COX-2 receptor (inflammation), prevents not just pre-eclampsia but all the components of the great obstetrical syndromes if initiated early in pregnancy. The optimal dose of low-dose aspirin that is maximally effective in pregnancy remains a question open for further research. Additionally, other candidate medications have been identified that may also prevent pre-eclampsia, and further study of them may offer therapeutic options beyond low-dose aspirin. Interestingly, three of the eight identified compounds (hydroxychloroquine, metformin and pravastatin) are known to decrease inflammation.

Cell-free fetal DNA impairs trophoblast migration in a TLR9-dependent manner and can be reversed by hydroxychloroquine

Growing evidence suggests a relationship between elevated circulating placental-derived cell-free fetal DNA (cffDNA) and preeclampsia. Hypomethylation of CpG motifs, a hallmark of cffDNA, allows it to activate Toll-like receptor 9 (TLR9). Using an in vitro human first trimester extravillous trophoblast cell model, we sought to determine if trophoblast-derived cffDNA and ODN 2216, a synthetic unmethylated CpG oligodeoxynucleotide, directly impacted spontaneous trophoblast migration. The role of the DNA sensors TLR9, AIM2, and cGAS was assessed using the inhibitor A151. To test whether any effects could be reversed by therapeutic agents, trophoblasts were treated with or without cffDNA or ODN 2216 with or without aspirin (ASA; a known cGAS inhibitor), aspirin-triggered lipoxin (ATL), or hydroxychloroquine (HCQ; a known TLR9 inhibitor). Trophoblast-derived cffDNA and ODN 2216 reduced trophoblast migration without affecting cell viability. Reduced trophoblast migration in response to cffDNA or ODN 2216 was reversed by A151. cffDNA inhibition of trophoblast migration was reversed by HCQ, while ASA or ATL had no effect. In contrast ODN 2216 inhibition of trophoblast migration was reversed by ASA, ATL and HCQ. Our findings suggest that cffDNA can exert a local effect on placental function by impairing trophoblast migration through activation of innate immune DNA sensors. HCQ, a known TLR9 inhibitor, reversed the effects of cffDNA on trophoblast migration. Greater insights into the molecular underpinnings of how cffDNA impacts placentation can aid in our understanding of the pathogenesis of preeclampsia, and in the development of novel therapeutic approaches for preeclampsia therapy.

The effect of low-dose aspirin on platelet function during pregnancy compared to placebo: An explorative study

OBJECTIVES

To evaluate the effect of aspirin 80 mg compared to placebo on platelet function tests in the second and third trimester of pregnancy.

STUDY DESIGN

An explorative study was performed to assess laboratory platelet function in a subpopulation of the APRIL trial: a randomized double-blind trial comparing aspirin 80 mg once daily to placebo for the prevention of recurrent preterm birth. Platelet function was measured between 18 and 22, and between 28 and 32 weeks gestational age with three platelet function tests: VerifyNow®, Chronolog light transmission aggregometry (Chronolog LTA) and serum thromboxane B₂ (TxB₂). Medication adherence was evaluated by pill counts, self-reported diaries and structured interviews.

RESULTS

We included 11 women, six in the aspirin and five in the placebo group. In women receiving aspirin, platelet function was significantly lower compared to women receiving placebo for all three tests: VerifyNow® Aspirin Reaction Units (450.5 vs 648.0, p = 0.017); Chronolog LTA (9.5% vs 94.5%, p = 0.009); serum TxB₂ levels (11.9 ng/mL versus 175.9 ng/mL, p = 0.030). For all three tests, platelet function did not differ between the second and third trimester of pregnancy in the aspirin group. In the placebo group, serum TxB₂ levels were significantly higher in the third trimester. One non-adherent participant in the aspirin group showed results similar to the placebo group.

CONCLUSION

Aspirin 80 mg has a clear inhibitory effect on laboratory platelet function during pregnancy compared to placebo. This effect is similar in the second and third trimester of pregnancy.

Prediction of pregnancy-related hypertensive disorders using metabolomics: a systematic review

OBJECTIVE

To determine the accuracy of metabolomics in predicting hypertensive disorders in pregnancy.

DESIGN

Systematic review of observational studies.

DATA SOURCES AND STUDY ELIGIBILITY CRITERIA

An electronic literature search was performed in June 2019 and February 2022. Two researchers independently selected studies published between 1998 and 2022 on metabolomic techniques applied to predict the condition; subsequently, they extracted data and performed quality assessment. Discrepancies were dealt with a third reviewer. The primary outcome was pre-eclampsia. Cohort or case-control studies were eligible when maternal samples were taken before diagnosis of the hypertensive disorder.

STUDY APPRAISAL AND SYNTHESIS METHODS

Data on study design, maternal characteristics, how hypertension was diagnosed, metabolomics details and metabolites, and accuracy were independently extracted by two authors.

RESULTS

Among 4613 initially identified studies on metabolomics, 68 were read in full text and 32 articles were included. Studies were excluded due to duplicated data, study design or lack of identification of metabolites. Metabolomics was applied mainly in the second trimester; the most common technique was liquid-chromatography coupled to mass spectrometry. Among the 122 different metabolites found, there were 23 amino acids and 21 fatty acids. Most of the metabolites were involved with ammonia recycling; amino acid metabolism; arachidonic acid metabolism; lipid transport, metabolism and peroxidation; fatty acid metabolism; cell signalling; galactose metabolism; nucleotide sugars metabolism; lactose degradation; and glycerolipid metabolism. Only citrate was a common metabolite for prediction of early-onset and late-onset pre-eclampsia. Vitamin D was the only metabolite in common for pre-eclampsia and gestational hypertension prediction. Meta-analysis was not performed due to lack of appropriate standardised data.

CONCLUSIONS AND IMPLICATIONS

Metabolite signatures may contribute to further insights into the pathogenesis of pre-eclampsia and support screening tests. Nevertheless, it is mandatory to validate such methods in larger studies with a heterogeneous population to ascertain the potential for their use in clinical practice.

PROSPERO REGISTRATION NUMBER

CRD42018097409.

Age and genotype dependent erythropoietin protection in COVID-19

Erythropoietin (EPO) is the main mediator of erythropoiesis and an important tissue protective hormone that appears to mediate an ancestral neuroprotective innate immune response mechanism at an early age. When the young brain is threatened-prematurity, neonatal hyperbilirubinemia, malaria- EPO is hyper-secreted disproportionately to any concurrent anemic stimuli. Under eons of severe malarial selection pressure, neuroprotective EPO augmenting genetic determinants such as the various hemoglobinopathies, and the angiotensin converting enzyme (ACE) I/D polymorphism, have been positively selected. When malarial and other cerebral threats abate and the young child survives to adulthood, EPO subsides. Sustained high ACE and angiotensin II (Ang II) levels through the ACE D allele in adulthood may then become detrimental as witnessed by epidemiological studies. The ubiquitous renin angiotensin system (RAS) influences the α-klotho/fibroblast growth factor 23 (FGF23) circuitry, and both are interconnected with EPO. Here we propose that at a young age, EPO augmenting genetic determinants through ACE D allele elevated Ang II levels in some or HbE/beta thalassemia in others would increase EPO levels and shield against coronavirus disease 2019, akin to protection from malaria and dengue fever. Human evolution may use ACE2 as a “bait” for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) to gain cellular entry in order to trigger an ACE/ACE2 imbalance and stimulate EPO hypersecretion using tissue RAS, uncoupled from hemoglobin levels. In subjects without EPO augmenting genetic determinants at any age, ACE2 binding and internalization upon SARS-CoV-2 entry would trigger an ACE/ACE2 imbalance, and Ang II oversecretion leading to protective EPO stimulation. In children, low nasal ACE2 Levels would beneficially augment this imbalance, especially for those without protective genetic determinants. On the other hand, in predisposed adults with the ACE D allele, ACE/ACE2 imbalance, may lead to uncontrolled RAS overactivity and an Ang II induced proinflammatory state and immune dysregulation, with interleukin 6 (IL-6), plasminogen activator inhibitor, and FGF23 elevations. IL-6 induced EPO suppression, aggravated through co-morbidities such as hypertension, diabetes, obesity, and RAS pharmacological interventions may potentially lead to acute respiratory distress syndrome, cytokine storm and/or autoimmunity. HbE/beta thalassemia carriers would enjoy protection at any age as their EPO stimulation is uncoupled from the RAS system. The timely use of rhEPO, EPO analogs, acetylsalicylic acid, bioactive lipids, or FGF23 antagonists in genetically predisposed individuals may counteract those detrimental effects.

Low-dose aspirin increases 15-epi-lipoxins A4 in pregnancies at high-risk for developing preeclampsia

BACKGROUND

LDA triggers biosynthesis of endogenous anti-inflammatory molecules, aspirin-triggered 15-epi-lipoxin A₄ (15-epi-LXA₄), which may counteract inflammatory process of preeclampsia (PE), and play role in LDA's mechanism of action in PE prevention in high-risk patients.

OBJECTIVE

Investigate the effects of daily LDA on levels of 15-epi-LXA₄ in pregnancies at high-risk for developing PE.

MATERIALS AND METHODS

Secondary analysis of multi-centered randomized controlled trial investigating effects of daily LDA (60 mg) in high-risk pregnancies. Maternal samples were drawn at three points: before LDA initiation (13-26 weeks' gestation), 24-28 weeks' gestation (at least two weeks after LDA) and 34-36 weeks' gestation. 15-epi-LXA₄ levels were measured by ELISA.

RESULTS

Analysis included 82 patients: 63 receiving daily LDA and 29 receiving daily placebo starting between 13 and 25 weeks gestation. Prior to randomization, baseline 15-epi-LXA₄ levels were similar between both groups (75.9 pg/mL [IQR; 63.8-114.0] vs 136.2 pg/mL [52.4-476.2]; p = 0.10). Patients receiving daily LDA were noted to have significantly increased levels of 15-epi-LXA₄ after LDA administration (136.2 pg/mL [IQR; 52.4-476.2] vs 1758.2 pg/mL [905.4-6638.5]; p < 0.001). They also had higher 15-epi-LXA₄ levels compared to those receiving placebo at 24-28 weeks' (50.3 [38.1-94.2] vs 1758.2 [905.4-6638.5]; p < 0.001 and 34-38 weeks' gestation (57.9 [41.9-76.7] vs 2310.3 pg/mL [656.9-10609.4]; p < 0.001). After LDA administration in the second trimester, patients who developed PE had decrease in 15-epi-LXA₄ levels compared to those without PE (942 pg/mL [348.3-1810.3] vs 1758.2 pg/mL [905.4-6638.5]; p = 0.129).

CONCLUSION

Daily LDA administration increases 15-epi-LXA₄ levels in high-risk pregnancies for PE. In LDA group, pregnancies complicated by PE have lower levels of 15-epi-LXA₄ compared to pregnancies without PE.

Longitudinal assessment of leukotriene B4, lipoxin A4, and resolvin D1 plasma levels in pregnant women with risk factors for preeclampsia

OBJECTIVES

We carried out a longitudinal study to compare leukotriene B4 (LTB4), lipoxin A4 (LXA4), and resolvin D1 (RvD1) levels in pregnant women with risk factors for PE - who did (N = 11) or did not develop (N = 17) this clinical condition.

DESIGN & METHODS

For both groups, plasma levels of the lipid mediators were measured using immunoassays at 12-19, 20-29, and 30-34 weeks of gestation.

RESULTS

LTB4 tended to be upregulated throughout gestation in women who developed PE. Moreover, this increase was significant at 30-34 weeks. Although LXA4 levels also tended to be higher in the PE group, this difference was not significant for the evaluated gestational periods. Pregnant women with PE had lower RvD1 levels and a low RvD1/LTB4 ratio at 30-34 weeks, compared to those in the normotensive pregnant women. Contrarily, RvD1 levels increased at weeks 12-19 in pregnant women who developed PE. Particularly, LXA4 and RvD1 levels were higher at 30-34 weeks than those at 20-29 weeks considering both groups of women. We observed an interaction between the gestational outcome and the gestational period in case of RvD1.

CONCLUSIONS

The imbalance among LTB4, LXA4, and RvD1 levels in these preeclamptic women is consistent with the excessive inflammation that underlies the pathogenesis of PE. Although our data highlight the potential for the use of these lipid mediators as clinical markers for PE development, future longitudinal studies must be carried out to confirm these findings.