Effects of anti-beta 2-glycoprotein 1 antibodies and its association with pregnancy-related morbidity in antiphospholipid syndrome

The effects of hydroxychloroquine and its promising use in refractory obstetric antiphospholipid syndrome

Hydroxychloroquine (HCQ) is obtained by hydroxylation of chloroquine (CQ) and the first indication was malaria. Nowadays, HCQ is commonly used in systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) with favorable results. Antiphospholipid syndrome (APS) is an autoimmune disease characterized by thrombosis and/or pregnancy morbidity and persistent positivity of antiphospholipid antibodies. Around 20-30% of pregnant women with APS develop adverse pregnancy outcomes despite conventional treatment with aspirin and heparin, called refractory obstetric APS. Interestingly, HCQ has shown positive effects on top of the standard of care in some refractory obstetric APS patients. HCQ mechanisms of action in APS comprise its ability to bind sialic acid present in cell membranes, its capacity to block the binding of antiphospholipid antibodies to the cell and the induced increase of pH in extracellular and intracellular compartments. However, the precise mechanisms of HCQ in the specific situation of refractory APS still need to be fully clarified. Therefore, this review summarizes the known modulating effects of HCQ and CQ, their side effects and use in APS and different pathologies to understand the benefit effects and the mechanism of action of HCQ in refractory obstetric APS.

The pathogenesis of obstetric APS: a 2023 update

The antiphospholipid syndrome (APS) is an autoimmune disease characterized by the persistent presence of antibodies directed against phospholipids and phospholipid-binding proteins that are associated with thrombosis and pregnancy-related morbidity. The latter includes fetal deaths, premature birth and maternal complications. In the early 1990s, a distinct set of autoantibodies, termed collectively antiphospholipid antibodies (aPL), were identified as the causative agents of this disorder. Subsequently histological analyses of the placenta from APS pregnancies revealed various abnormalities, including inflammation at maternal-fetal interface and poor placentation manifested by reduced trophoblast invasion and limited uterine spiral artery remodeling. Further preclinical investigations identified the molecular targets of aPL and the downstream intracellular pathways of key placental cell types. While these discoveries suggest potential therapeutics for this disorder, definitive clinical trials have not been completed. This concise review focuses on the recent developments in the field of basic and translational research pursuing novel mechanisms underlying obstetric APS.

Preconception clinical factors related to adverse pregnancy outcomes in patients with systemic lupus erythematosus or primary Sjögren's syndrome: a retrospective cohort study

OBJECTIVE

To identify preconception clinical factors associated with adverse pregnancy outcomes (APO) in patients with systemic lupus erythematosus (SLE) or primary Sjögren's syndrome (pSS).

METHODS

A single-centre, retrospective cohort study was conducted, which included pregnant women treated at the University Medical Center Groningen between January 2010 and August 2021 who fulfilled classification criteria for SLE or pSS. Demographic data, relevant comorbidities, disease duration, disease activity before and during pregnancy, APO, laboratory parameters and treatment regimens were recorded. Associations between the presence of APO and preconception characteristics were evaluated.

RESULTS

Our study population included 48 (70%) SLE and 21 (30%) pSS pregnancies concerning 70 fetuses (one twin). Preterm birth (n=9, 19%) was the most frequent APO in SLE pregnancies, while in pSS pregnancies this was miscarriages (n=3, 14%). There were no associations between the presence of APO in SLE pregnancies and clinical parameters, laboratory parameters or medication use prior to conception. In the pSS group, significant associations were found between the presence of APO and body mass index (p=0.010), parity (p=0.046), C4 (p=0.021) and low C4 levels (p=0.002).

CONCLUSIONS

No preconception risk factors related to APO were found in SLE pregnancies, whereas preconception complement levels were associated with APO development in patients with pSS.

Metastasis-associated lung adenocarcinoma transcript 1 induces methyl-CpG-binding domain protein 4 in mice with recurrent spontaneous abortion caused by anti-phospholipid antibody positivity

INTRODUCTION

Antiphospholipid syndrome is an autoimmune disease characterized by pregnancy-related morbidity, related to persistent positivity of antiphospholipid antibodies (APL). One of the characteristics of pregnancy-related morbidity in patients with antiphospholipid syndrome is recurrent spontaneous abortion (RSA). This study aimed to examine the mechanism through which metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) regulates methyl-CpG-binding domain protein 4 (MBD4) expression in APL-positive RSA.

METHODS

Clinical samples were subjected to microarray analysis to filter differentially expressed genes. RSA mice with APL positivity were generated, followed by adenoviral vector injection to artificially upregulate MALAT1. The effects of MALAT1 on the biological behavior of trophoblast cells were assessed. The downstream mechanism of MALAT1 was analyzed using subcellular fractionation and bioinformatics prediction, and the relationship between MALAT1 and CREB binding protein (CREBBP) or MBD4 was investigated in trophoblast cells.

RESULTS

MALAT1 was downregulated in APL-positive RSA patients. MALAT1 was predominantly localized in the nucleus and recruited CREBBP to mediate the MBD4 transcription. In the APL-positive RSA mice overexpressing MALAT1, the expression of soluble Fms-related tyrosine kinase 1 and anticardiolipin antibody and the embryonic resorption rate were decreased, indicating that MALAT1 reduced the occurrence of RSA in mice. Moreover, MALAT1 enhanced proliferation, migration, and invasion of trophoblast cells through recruiting CREBBP to promote MBD4 expression. Silencing of CREBBP or MBD4 increased embryonic resorption rate in RSA mice overexpressing MALAT1.

DISCUSSION

MALAT1 suppresses APL-positive RSA by promoting MBD4 transcription through recruitment of CREBBP to the MBD4 promoter region.

Inactivation of Yes-Associated Protein Mediates Trophoblast Dysfunction: A New Mechanism of Pregnancy Loss Associated with Anti-Phospholipid Antibodies?

Pregnancy morbidity induced by anti-phospholipid antibodies (aPL+/PM+) is mainly thought to arise from placental abnormalities. We attempted to investigate the effect of aPL on the activity of Yes-associated protein (YAP) in the trophoblast and how YAP regulated human trophoblasts function. Thus, HTR-8 cells were treated with IgG purified from aPL+/PM+ women or normal controls. We found that aPL+/PM+ IgG impacted YAP activity via abrogating YAP expression. Further investigation of the anti-β2GPI-IgG/β2GPI complex showed an inhibition of nuclear YAP level and translocation in a dose-dependent manner, which might be rescued by progesterone in HTR-8 cells. YAP overexpression or knockdown HTR-8 cells were established for the evaluation of cell function and related gene expression in vitro. Loss of YAP arrested cell cycles in the G2/M phase, accelerated cell apoptosis by increasing the ratio of Bax/Bcl2, and disrupted MMP2/9-mediated cell migration and angiogenesis tube formation by VEGF. These findings support a new mechanism of PM associated with aPL through which YAP inactivation induced by aPL perturbs the trophoblast cell cycle, apoptosis, migration, and angiogenesis, finally developing into pregnancy failure.

Epigenetics-mediated pathological alternations and their potential in antiphospholipid syndrome diagnosis and therapy

APS (antiphospholipid syndrome) is a systematic autoimmune disease accompanied with venous or arterial thrombosis and poor pregnant manifestations, partly attributing to the successive elevated aPL (antiphospholipid antibodies) and provoked prothrombotic and proinflammatory molecules production. Nowadays, most researches focus on the laboratory detection and clinic features of APS, but its precise etiology remains to be deeply explored. As we all know, the dysfunction of ECs (endothelial cells), monocytes, platelets, trophoblasts and neutrophils are key contributors to APS progression. Especially, their epigenetic variations, mainly including the promoter CpGs methylation, histone PTMs (post-translational modifications) and ncRNAs (noncoding RNAs), result in genes expression or silence engaged in inflammation initiation, thrombosis formation, autoimmune activation and APOs (adverse pregnancy outcomes) in APS. Given the potential of epigenetic markers serving as diagnostic biomarkers or therapeutic targets of APS, and the encouraging advancements in epigenetic drugs are being made. In this review, we would systematically introduce the epigenetic underlying mechanisms for APS progression, comprehensively elucidate the functional mechanisms of epigenetics in boosting ECs, monocytes, platelets, trophoblasts and neutrophils. Lastly, the application of epigenetic alterations for probing novel diagnostic, specific therapeutic and prognostic strategies would be proposed.

Risk of Thrombosis, Pregnancy Morbidity or Death in Antiphospholipid Syndrome

The antiphospholipid syndrome is an autoimmune disease characterized by thrombosis and pregnancy morbidity. The manifestations are caused by antibodies targeting cell membrane phospholipids and/or associated proteins. The triggers leading to these antibodies' production are unknown but recent work suggests cross-reactivity between the autoantigens and peptides produced by the intestinal microbiome. Work on how the autoantibodies could cause clinical manifestations implicates different mechanisms. Binding to surface proteins of different cell types can induce intracellular signaling leading to cell activation and tissue factor expression. Complement activation and neutrophil extracellular-traps are also involved, and recent evidence implicates endothelial protein C receptor-lysobisphosphatidic acid complex. Pregnancy is a high-risk situation for antiphospholipid syndrome patients due to the increased risk of thrombosis and obstetric complications. Epidemiological and clinical research on APS is hampered by heterogeneity in populations, testing and treatment strategies. About one in 10 to one in fifty APS pregnancies is complicated by thrombosis, despite treatment. Pregnant patients with prior thrombosis are prescribed therapeutic dose heparins and low dose aspirin. Without prior thrombosis a prophylactic dose is used. The most frequent obstetrical manifestation is recurrent early pregnancy loss. The association of APS antibodies with late pregnancy loss is stronger, however. Prevention of recurrence is achieved with aspirin and prophylactic dose heparin, although the evidence is of low certainty. The third obstetrical classifying manifestation comprises preterm delivery due to placenta-mediated complications and is treated in subsequent pregnancies with aspirin with or without prophylactic dose heparin, again based on low quality evidence. New therapies are under investigation.