Anti-annexin A5 antibodies in women with spontaneous pregnancy loss

Preconception anti-annexin A5 antibodies are associated with subsequent live birth in women with recurrent miscarriage: A retrospective study from China

PROBLEM

To evaluate the correlation between the antiannexin A5 antibodies (aAnxA5) multiples of median (MOM) and subsequent pregnancy outcomes in women with recurrent miscarriage (RM).

METHODS

Totally, 310 RM women were included in this study and grouped into tertiles according to their MOM of preconception aAnxA5 circulating levels determined by ELISA. The effect of aAnxA5 on the pregnancy outcomes was performed using multiple logistic regression. The outcomes included early miscarriage (before 10 weeks of gestation), late miscarriage (between 10 and 24 weeks), ongoing pregnancy (beyond 10 weeks), and live birth (after 24 weeks) characterized by pregnancy with fetal heartbeat.

RESULTS

For each unit increase in aAnxA5 MOM, the odds of live birth after 24 weeks and ongoing pregnancy were reduced by 40.2% (OR = .598; 95%CI 0.406-0.882, P = .010) and 38.1% (OR = .619; 95%CI 0.424-0.904, P = .013), respectively, after adjusting for demographic and clinical characteristics. The rise in aAnxA5 MOM was associated with an increased risk of early miscarriage (OR = 1.616; 95%CI 1.106-2.361, P = .013) and miscarriage (early + late miscarriage) (OR = 1.671; 95%CI 1.134-2.464, P = .010). Further subgroup analyses showed a decreased risk of live birth rates after 24 weeks of gestation in the two subgroups: maternal age ≥35 years (OR = .131; 95%CI 0.026-0.652), and previous pregnancy loss ≥ 3 (OR = .381; 95%CI 0.173-0.837).

CONCLUSIONS

Higher preconception aAnxA5 MOM levels in women with RM may be linked with a decreased risk of live birth after 24 weeks and an increased risk of early miscarriage, especially in individuals aged ≥35 years or with previous pregnancy losses ≥3.

The role of the annexin A protein family at the maternal-fetal interface

Successful pregnancy requires the tolerance of the maternal immune system for the semi-allogeneic embryo, as well as a synchrony between the receptive endometrium and the competent embryo. The annexin family belongs to calcium-regulated phospholipid-binding protein, which functions as a membrane skeleton to stabilize the lipid bilayer and participate in various biological processes in humans. There is an abundance of the annexin family at the maternal-fetal interface, and it exerts a crucial role in embryo implantation and the subsequent development of the placenta. Altered expression of the annexin family and dysfunction of annexin proteins or polymorphisms of the ANXA gene are involved in a range of pregnancy complications. In this review, we summarize the current knowledge of the annexin A protein family at the maternal-fetal interface and its association with female reproductive disorders, suggesting the use of ANXA as the potential therapeutic target in the clinical diagnosis and treatment of pregnancy complications.

Research progress on ANXA5 in recurrent pregnancy loss

The incidence of recurrent pregnancy loss (RPL) in fertile women ranges from 1% to 5%, of which about 50% of them are due to unknown causes. The possible pathogenesis of RPL is an urgent problem to be solved in the clinical. Mutations or polymorphisms of certain genes in the coagulation mechanism are associated with susceptibility to thrombotic diseases and are one of the main reasons for the occurrence of RPL. Among them, the ANXA5 gene was newly studied and some single nucleotide polymorphisms (SNPs) in the promoter region of ANXA5 have been reported to be associated with RPL in multiple races. In this review, we summarized the research progress on the correlation between the SNPs in ANXA5 and RPL, hoping to provide some valuable guidance for the future studies.

Non-criteria Antiphospholipid Antibodies: a narrative review

SUMMARY The 2006 Revised Sapporo Classification Criteria for Definite Antiphospholipid Syndrome included as laboratory criteria the tests for antiphospholipid antibodies whose accuracy was regarded as satisfactory according to the evidence available at that time. In practice, however, the sensitivity and specificity of these “criteria” of antiphospholipid antibodies are sometimes insufficient for identifying or ruling out antiphospholipid syndrome. It has been studied whether the accuracy of the laboratory diagnosis of the syndrome could be improved by testing for non-criteria antiphospholipid antibodies. In this work, we review evidence on the clinical associations and diagnostic value of the most commonly studied non-criteria antibodies, namely: antiphosphatidylethanolamine, anti-annexin A5, anti-prothrombin, anti-phosphatidylserine/prothrombin complex, IgA anticardiolipin, and IgG anti-domain I of the β2 glycoprotein antibodies.

Anti-phospholipid antibodies and reproductive failures

Anti-phospholipid syndrome (APS) recapitulates the link between autoimmunity and pregnancy failure: Acquired anti-phospholipid antibodies (aPL) play a pathogenic role in pregnancy complications. The diagnosis of obstetric APS can easily be pursued when women present with laboratory and clinical features fulfilling the international classification criteria. Standard therapeutic approach to obstetric APS consists in the association of anti-platelet agents and anticoagulants. Most patients achieve a live birth thanks to conventional treatment; however, approximately 20% fail to respond and are managed with additional therapeutic tools added on the top of conventional treatment. Surely, a refinement of risk stratification tools would allow early identification of high-risk pregnancies that warrant tailored treatment. In real life, obstetricians and rheumatologists face complex diagnostic scenarios including women with pregnancy morbidities other than those mentioned in classification criteria such as one or two early losses and premature birth after 34 weeks due to preeclampsia or placental insufficiency, women with low-titer aPL not fulfilling criteria laboratory requirements, women with positive non-criteria aPL, asymptomatic aPL carriers, and infertile women found to be aPL-positive. This review focuses on some of the several unanswered questions related to diagnostic, prognostic, and therapeutic aspects in obstetric APS.

Detection of non-criteria autoantibodies in women without apparent causes for pregnancy loss

Background

Some of the non‐criteria autoantibodies, especially non‐conventional antiphospholipid (aPL) antibodies, were present with high prevalence in sporadic miscarriages and recurrent pregnant loss. However, whether these autoantibodies are associated with miscarriage patients without apparent causes remain unclear.

Methods

The subjects were recruited from the female patients visiting the Infertility Center at the Beijing Obstetrics and Gynecology Hospital from January 2017 to March 2018. The women who experienced one sporadic miscarriage (n = 89) or recurrent pregnancy loss (n = 125) were enrolled. The control participants (n = 59) were those women with normal pregnancy history and with no miscarriage or thrombosis experience. The collected serum specimens from above patients and controls were subjected to the 13 non‐criteria autoantibody examinations, targeting non‐conventional phospholipids, thyroid, sperm, endometrial, and anti‐nuclear antigens.

Results

When compared with the controls, the following non‐criteria antibodies stood out in present study with significantly increased frequency and were listed in the order of decreasing positive rates: aPE IgM (40.0%), ANA (15.2%), aEM IgG (13.6%), aPE IgG (12.8%), and aPT IgM (10.4%). Except for ANA, the presence of aPE IgM, aEM IgG, aPE IgG, and aPT IgM was not associated with positivity of LA tests. In receiver operating characteristic analyses, the combined aPE IgG and aEM IgG biomarker panel had the best discriminating power between miscarriage patients and healthy controls.

Conclusion

Our findings suggested that the non‐criteria could be included as part of the pregnancy loss evaluation when apparent causes are absent, and the conventional aPLs tests failed to provide interpretations.

Antiphospholipid and antioangiogenic activity in females with recurrent miscarriage and antiphospholipid syndrome

Background Antiphospholipid syndrome is an autoimmune disease characterized by thrombosis, fetal losses and thrombocytopenia associated to antiphospholipid antibodies. They are directed to phospholipids, such as cardiolipins (anticardiolipin) and lupus anticoagulant or to complexes formed by phospholipids and protein cofactors, such as β2 glycoprotein 1 (a-β2GP1) and annexin V (a-annexin V). These auto-antibodies may be considered as a family of antibodies involved in thrombotic events and antiphospholipid activity. On the other hand, some proangiogenic factors are involved in the normal development of placental vasculature, such as the vascular endothelial growth factor. Overexpression of vascular endothelial growth factor receptor in its soluble form (sVEGFR-1) has been associated to a higher antiangiogenic activity. Our aim was to analyse the association between anticardiolipin, lupus anticoagulant, a-β2GP1, a-annexin V and sVEGFR-1 with recurrent miscarriage before week 10 of gestation in females with antiphospholipid syndrome. Methods We studied 24 females (primary or secondary antiphospholipid syndrome), who were divided into two groups: females with recurrent miscarriage before week 10 of gestation (M; n = 12) and females with no history of fetal loss (NM; n = 12). Anticardiolipin, a-β2GP1, a-annexin V and sVEGF-R1 concentrations were assessed by ELISA, while lupus anticoagulant was assessed by screening and confirmatory tests. Results A significant association was observed between the number of positive biomarkers and the belonging group ( P < 0.05). Besides, a positive result for lupus anticoagulant and a-β2GP1 was found to be significantly associated to the M group ( P < 0.05). Conclusions Lupus anticoagulant and a-β2GP1 may be implicated in pregnancies complicated by recurrent miscarriage in females with antiphospholipid syndrome.

Obstetric antiphospholipid syndrome: a recent classification for an old defined disorder

Obstetric antiphospholipid syndrome (APS) is now being recognized as a distinct entity from vascular APS. Pregnancy morbidity includes >3 consecutive and spontaneous early miscarriages before 10weeks of gestation; at least one unexplained fetal death after the 10th week of gestation of a morphologically normal fetus; a premature birth before the 34th week of gestation of a normal neonate due to eclampsia or severe pre-eclampsia or placental insufficiency. It is not well understood how antiphospholipid antibodies (aPLs), beyond their diagnostic and prognostic role, contribute to pregnancy manifestations. Indeed aPL-mediated thrombotic events cannot explain the obstetric manifestations and additional pathogenic mechanisms, such as a placental aPL mediated complement activation and a direct effect of aPLs on placental development, have been reported. Still debated is the possible association between aPLs and infertility and the effect of maternal autoantibodies on non-vascular manifestations in the babies. Combination of low dose aspirin and unfractionated or low molecular weight heparin is the effective treatment in most of the cases. However, pregnancy complications, in spite of this therapy, can occur in up to 20% of the patients. Novel alternative therapies able to abrogate the aPL pathogenic action either by interfering with aPL binding at the placental level or by inhibiting the aPL-mediated detrimental effect are under active investigation.

Loss of maternal annexin A5 increases the likelihood of placental platelet thrombosis and foetal loss

Antiphospholipid syndrome is associated with an increased risk of thrombosis and pregnancy loss. Annexin A5 (Anxa5) is a candidate autoantigen. It is not known, however, whether endogenous Anxa5 prevents foetal loss during normal pregnancy. We found significant reductions in litter size and foetal weight in Anxa5-null mice (Anxa5-KO). These changes occurred even when only the mother was Anxa5-KO. A small amount of placental fibrin deposition was observed in the decidual tissues, but did not noticeably differ between wild-type and Anxa5-KO mice. However, immunoreactivity for integrin beta 3/CD61, a platelet marker, was demonstrated within thrombi in the arterial canals only in Anxa5-KO mothers. Subcutaneous administration of the anticoagulant heparin to pregnant Anxa5-KO mice significantly reduced pregnancy loss, suggesting that maternal Anxa5 is crucial for maintaining intact placental circulation. Hence, the presence of maternal Anxa5 minimises the risk of thrombosis in the placental circulation and reduces the risk of foetal loss.

Hereditary thrombophilia, anti-beta2 glycoprotein 1 IgM, and anti-annexin V antibodies in recurrent pregnancy loss

PROBLEM

We investigated the beta2-glycoprotein I and anti-annexin V antibodies as anti-phospholipid-cofactor antibodies; and factor V G1691A Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase (MTHFR) C677T mutations as hereditary thrombophilia in recurrent pregnancy losses (RPL).

METHOD OF STUDY

Study group consisted of 84 women with recurrent pregnancy loss and control group consisted of 84 women having at least one live birth.

RESULTS

Methylenetetrahydrofolate reductase C677T homozygous mutation was detected in 28.5% of the study group and in 14.2% of the controls, and the difference was highly significant (P < 0.001). Heterozygous mutation of this gene was found in 64.3% of the study population and in 38.1% of the controls, and difference in heterozygous mutation frequency was also significant (P < 0.001). Both homozygous and heterozygous mutations of PT G20210A and factor V G1691A were not different between the groups. There was no significant difference in anti-annexin V levels and anti-beta2-gp 1 levels of the groups.

CONCLUSION

We concluded that both homozygous and heterozygous mutations of MTHFR C677T were related with RPL in Caucasian women.

Prevalence and clinical usefulness of antiphospholipid and anticofactor antibodies in different Spanish preeclampsia subsets

Objective: To study the prevalence and clinical usefulness of antiphospholipid antibodies in different preeclampsia subsets. Design: Observational cross-sectional study. Setting: Tertiary teaching hospital. Patients: Ninety-nine women with preeclampsia versus 83 healthy pregnant women as controls. Interventions: We analysed anticardiolipin IgG/IgM, anti-ß2glycoprotein IgG/IgM, antiphosphatidylserine IgG/IgM, antiAnnexin-A5 IgG/IgM, and lupus anticoagulant. Main outcome measure: Comparison of antiphospholipid antibody positivity between groups. Results: Antiphospholipid antibody prevalence was 14.14% in the study group vs. 7.23% in controls. Excluding antiAnnexin-A5-positive women, overall antiphospholipid prevalence was 13.19% vs. 3.61% ( p = 0.034). Only IgM-anticardiolipin positivity showed significant differences between preeclampsia group and controls (8.1% vs. 1.20%, p = 0.041). Comparing a severe preeclampsia subset vs. controls, we obtained these significant results: for two or more positive antiphospholipid tests: 9.09% vs. 1.20 ( p = 0.037); IgM-anticardiolipin 10.91% vs. 1.20% ( p = 0.016); IgG/IgM-anti-ß2glycoprotein-I 10.91% vs. 1.90% ( p = 0.016), IgM-anti-ß2glycoprotein-I 9.09% vs.1.20 ( p = 0.037). When comparing early-onset preeclampsia vs. controls we found IgM-anticardiolipin 11.11% vs. 1.20% ( p = 0.029). Conclusions: Prevalence of antiphospholipid antibodies in preeclampsia patients is twice that in healthy pregnant women. Multipositive aPL test, IgM-anticardiolipin and IgM-anti-ß2glycoprotein-I isotypes showed an association with severe and early-onset preeclampsia. Larger studies are needed to establish the usefulness of antiphospholipid tests as risk markers for severe and early onset preeclampsia.

Anti-annexins autoantibodies: their role as biomarkers of autoimmune diseases

Annexins are a group of 12 highly conserved proteins which exert several regulatory functions on cell biology. There are involved in numerous cell processes including vesicle trafficking, calcium signaling, cell growth, division, and apoptosis. Autoantibodies directed toward annexin I, II, V and XI have been reported, but their role and their clinical correlates are controversial. Annexin I exerts an anti-inflammatory effect by suppressing the generation of inflammatory mediators and anti-annexin I antibodies were detected in patients affected with rheumatoid arthritis, systemic (SLE) and cutaneous lupus erythematosus. Annexin II and V have a high affinity for phospholipids playing a pivotal role in the regulation of coagulation cascade. Anti-annexin II and anti-annexin V antibodies were found in patients with arterial or venous thrombosis, especially in those with autoimmune rheumatic diseases (ARD) such as SLE, primary antiphospholipid syndrome (APS) or systemic sclerosis. Anti-annexin V antibodies were also found in patients with pregnancy loss with or without APS. Annexin XI is involved in several biological pathways, particularly apoptosis and cell proliferation. Anti-annexin XI antibodies have been found in patients with SLE, undifferentiated connective tissue disease, rheumatoid arthritis, Sjögren's syndrome and APS. The metanalysis of studies published up to now showed that the Odds Ratio for having an ARD in anti-annexin XI positive patients was 5.08 (95% CI 2.06-12.58).

Anti-annexin V IgM and IgG autoantibodies and the risk of idiopathic recurrent spontaneous miscarriage

Anti-annexin V antibodies have been identified as risk factors for recurrent spontaneous miscarriage (RSM) in some, but not all previous studies. We investigated the association between anti-annexin IgM and IgG in RSM cases and control women. Blood samples from 244 women with idiopathic RSM, and 283 multi-parous control women were tested for anti-annexin V antibodies by ELISA. A significant elevation in anti-annexin V IgM and IgG was seen in the RSM cases. An increased prevalence of elevated anti-annexin V IgM and to a lesser extent anti-annexin V IgG was seen in RSM patients. Receiver operating characteristic analysis indicated that the area under the curve for anti-annexin V IgM was 0.916, and for anti-annexin V IgG was 0.725. A systematic shift in anti-annexin V IgM and IgG distributions toward higher values occurred in RSM women, which was confirmed by percentile analysis. For each of the anti-annexin V isotypes, the adjusted odds ratio increased as the percentile value increased; the strongest risk was for anti-annexin V IgM, in which the 99th percentile (P99) was associated with a 165-fold higher risk than P50, and for anti-annexin V IgG where P99 was associated with a 38-fold higher risk than P50. In addition, a higher prevalence of elevated anti-annexin V IgM and anti-annexin V IgG was seen in RSM cases than in control women. We conclude that anti-annexin V IgM and IgG antibody positivity are independent risk factors for RSM.