Antibodies to phosphatidylserine/prothrombin (aPS/PT) enhanced the diagnostic performance in Chinese patients with antiphospholipid syndrome

[Obstetric Antiphospholipid Syndrome: Insights on the Diagnosis, Treatment, and Hot Issues]

Obstetric antiphospholipid syndrome (OAPS) is an autoimmune disorder associated with various pathological pregnancies, such as recurrent miscarriage, stillbirth, severe pre-eclampsia and severe placental insufficiency. The persistent presence of antiphospholipid antibodies (aPLs) is the most important laboratory characteristic of OAPS. OAPS severely affects the reproductive health of women of childbearing age in China. Reports indicate that approximately 9.6% stillbirths, 11.5% severe pre-eclampsia, and 54% recurrent miscarriages are associated with OAPS or aPLs. However, the pathogenesis of OAPS remains unclear. Previously, thrombosis at the maternal-fetal interface (MFI) was considered the main mechanism of OAPS-related pathological pregnancies. Consequently, the use of low molecular weight heparin and aspirin throughout pregnancy was recommended to improve outcomes in OAPS patient. In recent years, many studies have found that thrombosis in MFI is uncommon, but various inflammatory factors are significantly increased in the MFI of OAPS patients. Based on these findings, some clinicians have started using anti-inflammatory treatments for OAPS, which have preliminarily improved the pregnancy outcomes. Nevertheless, there is no consensus on these second-line treatments of OAPS. Another troubling issue is the clinical diagnosis of OAPS. Similar to other autoimmune diseases, there are only classification criteria for OAPS, and clinical diagnosis of OAPS depends on the clinicians' experience. The present classification criteria of OAPS were established for clinical and basic research purposes, not for patient clinical management. In clinical practice, many patients with both positive aPLs and pathological pregnancy histories do not meet the strict OAPS criteria. This has led to widespread issues of incorrect diagnosis and treatment. Timely and accurate diagnosis of OAPS is crucial for effective treatment. In this article, we reviewed the epidemiological research progress on OAPS and summarized its classification principles, including: 1) the persistent presence of aPLs in circulation; 2) manifestations of OAPS, excluding other possible causes. For the first point, accurate assessment of aPLs is crucial; for the latter, previous studies regarded only placenta-related pregnancy complications as characteristic manifestations of OAPS. However, recent studies have indicated that adverse pregnancy outcomes related to trophoblast damage, such as recurrent miscarriage and stillbirth, also need to be considered in OAPS. We also discussed several key issues in the diagnosis and treatment of OAPS. First, we addressed the definition of non-standard OAPS and offered our opinion on defining non-standard OAPS within the framework of the 2023 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) APS criteria. Then, we discussed the advantages and disadvantages of different aPL testing methods, emphasizing that harmonizing results across platforms and establishing specific reference values are keys to resolving controversies in aPL testing results. We also introduced the application of non-criteria aPLs, especially anti-phosphatidylserine/prothrombin antibody (aPS/PT) and anti-β2 glycoprotein Ⅰ domain Ⅰ antibody (aβ2GPⅠDⅠ). Additionally, we discussed aPL-based OAPS risk classification strategies. Finally, we proposed potential treatment methods for refractory OAPS. The goal is to provide a reference for the clinical management of OAPS.

Added value of antiphosphatidylserine/prothrombin antibodies in the workup of obstetric antiphospholipid syndrome: communication from the ISTH SSC Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibodies

BACKGROUND

The added value of antiphosphatidylserine/prothrombin antibodies (aPS/PT) in the diagnostic workup of antiphospholipid syndrome (APS) is unclear. Currently, diagnosis of thrombotic APS (TAPS) and obstetric APS (OAPS) requires persistent presence of lupus anticoagulant (LAC), anticardiolipin (aCL) immunoglobulin (Ig) G/IgM, or anti-β2-glycoprotein I (aβ2GPI) IgG/IgM antibodies.

OBJECTIVES

To evaluate the role of aPS/PT IgG and IgM in OAPS.

METHODS

aPS/PT IgG/IgM, aCL IgG/IgM, aβ2GPI IgG/IgM, and LAC were determined in 653 patients (OAPS, TAPS, and controls). In-house aPS/PT cut-off values were calculated, titers and prevalence were compared between OAPS, TAPS, and controls and type of pregnancy morbidity. Sensitivity, specificity, likelihood ratios, and odds ratios (OR) with 95% CI were calculated.

RESULTS

In OAPS, aPS/PT IgG and IgM showed an OR of 4.32 (95% CI, 2.54-7.36) and 3.37 (95% CI, 1.93-5.89), respectively, but the association was not independent of LAC. Prevalence and titers of aPS/PT IgG and IgM were lower in OAPS than in patients with TAPS. aPS/PT were more prevalent and showed higher titers in patients with late pregnancy loss than in patients with early pregnancy loss with a positivity of 86.4% and 39.3%, respectively. Higher aPS/PT titers did not increase the likelihood of having OAPS.

CONCLUSION

The added value of aPS/PT testing in the current diagnostic workup of OAPS seems limited compared with LAC, aCL, and aβ2GPI. aPS/PT might be useful in specific subsets of patients with OAPS. However, future multicentric studies are needed to elucidate the risk of less frequent and most severe obstetrical manifestations.

Relevance of non-criteria antiphospholipid antibodies titers among patients with antiphospholipid syndrome and patients with systemic lupus erythematosus

BACKGROUND

There is an increasing interest in the study of non-criteria antiphospholipid antibodies (aPL) including antibodies targeting domain 1 of the B2 glycoprotein 1 (anti-D1 B2GP1) and antibodies anti phosphatidylserine/ prothrombin (PS/PT).

OBJECTIVES

Our aim was to analyze a panel of conventional and non-criteria aPL in a cohort of patients with systemic lupus erythematosus (SLE) and primary antiphospholipid syndrome (APS), to describe if there are differences in aPL titers among groups, to evaluate clinical associations including risk of recurrent events of novel aPL.

METHODS

Observational study that evaluated at baseline antibodies against anti-D1 B2GP1 and anti PS/PT. Anti-D1 B2GP1 antibodies were tested using a chemiluminescent immunoassay. IgG and IgM anti PS/PT, aCL and anti B2GP1 by ELISA techniques. Therefore, patients were followed in order to identify new thrombotic events.

RESULTS

133 patients with SLE and 23 with primary APS patients were included. Main APS manifestations were DVT (27%), obstetric morbidity (22%) and arterial thrombosis (10.1%). IgM anti PS/PT antibodies levels were (20.6 - 127) vs 21.9 (11.2 - 39.2) U/ml, p<0.001 in primary APS vs SLE with APS, respectively. Anti-D1 B2GP1, IgG and IgM anti PS/PT were associated with thrombotic and non-thrombotic manifestations. During follow-up, IgG B2GP1 were related with a significant cumulative risk of thrombosis.

CONCLUSIONS

We found significant differences in serum titers of non-criteria aPL among patients with primary APS vs SLE with APS. Whether non-criteria aPL antibodies titers are useful to differentiate patients with primary and secondary APS requires further analysis in other populations.

Added value of antiphosphatidylserine/prothrombin antibodies in the workup of thrombotic antiphospholipid syndrome: Communication from the ISTH SSC Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibodies

BACKGROUND

Diagnosis of antiphospholipid syndrome (APS) requires persistent presence of lupus anticoagulant (LAC), anticardiolipin (aCL) IgG/IgM, or anti-β2 glycoprotein I (aβ2GPI) IgG/IgM antibodies. Other antiphospholipid antibodies (aPL) such as antiphosphatidylserine/prothrombin antibodies (aPS/PT) are promising in assessment of thrombotic APS (TAPS).

AIM

To evaluate the added value of aPS/PT IgG and IgM in TAPS.

MATERIAL AND METHODS

aPS/PT IgG/IgM, aCL IgG/IgM, aβ2GPI IgG/IgM, and LAC were determined in 757 patients (TAPS and controls). aPS/PT cut-off values were calculated, and aPS/PT titers and positivity were compared between TAPS and controls, type of thrombosis, and antibody profiles. Likelihood ratios (LR), odds ratios (OR), and aPL score were determined.

RESULTS

aPS/PT IgG and IgM were associated with TAPS and triple positivity. In-house calculated cut-offs were higher for IgM (43 units), compared to manufacturer's cut-off (30 units). Thresholds of 90 (IgG) and 200 (IgM) units were determined as high-titer cut-off. Higher aPS/PT titers were observed in triple positive patients and showed higher LR and OR for TAPS. aPS/PT was independently associated with TAPS when adjusted for aCL/aβ2GPI, but not when adjusted for LAC. In isolated LAC positive patients, aPS/PT was positive in 27.1% TAPS patients and in 77.3% patients with autoimmune disease. Diagnostic value of aPL score did not differ with and without including aPS/PT.

CONCLUSION

aPS/PT positivity, especially with high antibody titer, is associated with TAPS diagnosis. Analysis on top of current laboratory criteria is not essential in TAPS diagnosis, but aPS/PT could be useful in patients with thrombosis and a double positive aPL profile (aCL+/aβ2GPI+).

Prevalence of autoantibodies directed against prothrombin in unprovoked venous thromboembolism

The anti-phospholipid syndrome (APS) is defined by the laboratory detection of at least one of three anti-phospholipid autoantibodies (lupus anticoagulant, or anti-cardiolipin or anti-β₂-glycoprotein I antibodies) in the clinical setting of thrombosis or pregnancy morbidity in a patient. Recognising APS and administering appropriate secondary thromboprophylaxis is important to reduce risk of recurrent thrombosis and/or pregnancy morbidity. In some instances, patients having clinical manifestations highly suggestive of APS are persistently negative for these antibodies but instead have other autoantibodies. Autoantibodies directed against prothrombin (PT) have been associated with increased thrombotic risk and comprise anti-prothrombin (aPT) and anti-phosphatidylserine/prothrombin (aPS/PT) antibodies. Detection of aPT and aPS/PT may help stratify patients for more effective treatment, however, their prevalence among patients with unprovoked venous thromboembolism (VTE) is unknown and determination of their frequencies is the objective of this study. Sera from 148 patients with unprovoked VTE were analysed. Autoantibodies directed against PT collectively, aPT and aPS/PT were present in 24.3%, 14.9% and 13.5%, respectively. Prevalence of these autoantibodies in unprovoked VTE is much lower compared to cohorts comprising mainly patients with systemic autoimmune disorders. Detection of these autoantibodies in unprovoked VTE has potential therapeutic implications for patients including the duration of anticoagulation and administration, or otherwise, of direct oral anticoagulants. Data from this study will assist in the design of future clinical studies to estimate risk of recurrent VTE and to determine optimal management.

Antiphospholipid Antibodies in Critically Ill Patients With COVID-19

OBJECTIVE

Coagulopathy is one of the characteristics observed in critically ill patients with coronavirus disease 2019 (COVID-19). Antiphospholipid antibodies (aPLs) contribute to coagulopathy, though their role in COVID-19 remains unclear. This study was undertaken to determine the prevalence and characteristics of aPLs in patients with COVID-19.

METHODS

Sera collected from 66 COVID-19 patients who were critically ill and 13 COVID-19 patients who were not critically ill were tested by chemiluminescence immunoassay for anticardiolipin antibodies (aCLs), anti-β₂ -glycoprotein I (anti-β₂ GPI) (IgG, IgM, and IgA), and IgG anti-β₂ GPI-domain 1 (anti-β₂ GPI-D1) and IgM and IgG anti-phosphatidylserine/prothrombin (anti-PS/PT) antibodies were detected in the serum by enzyme-linked immunosorbent assay.

RESULTS

Of the 66 COVID-19 patients in critical condition, aPLs were detected in 31 (47% ). Antiphospholipid antibodies were not present among COVID-19 patients who were not in critical condition. The IgA anti-β₂ GPI antibody was the most commonly observed aPL in patients with COVID-19 and was present in 28.8% (19 of 66) of the critically ill patients, followed by IgA aCLs (17 of 66, or 25.8%) and IgG anti-β₂ GPI (12 of 66, or 18.2%). For multiple aPLs, IgA anti-β₂ GPI + IgA aCLs was the most common antibody profile observed (15 of 66, or 22.7%), followed by IgA anti-β₂ GPI + IgA aCL + IgG anti-β₂ GPI (10 of 66, or 15.2%). Antiphospholipid antibodies emerge ~35-39 days after disease onset. A dynamic analysis of aPLs revealed 4 patterns based on the persistence or transient appearance of the aPLs. Patients with multiple aPLs had a significantly higher incidence of cerebral infarction compared to patients who were negative for aPLs (P = 0.023).

CONCLUSION

Antiphospholipid antibodies were common in critically ill patients with COVID-19. Repeated testing demonstrating medium to high titers of aPLs and the number of aPL types a patient is positive for may help in identifying patients who are at risk of developing cerebral infarction. Antiphospholipid antibodies may be transient and disappear within a few weeks, but in genetically predisposed patients, COVID-19 may trigger the development of an autoimmune condition similar to the antiphospholipid syndrome (APS), referred to as "COVID-19-induced APS-like syndrome." Long-term follow-up of COVID-19 patients who are positive for aPLs would be of great importance in understanding the pathogenesis of this novel coronavirus.

Hyperoside attenuates pregnancy loss through activating autophagy and suppressing inflammation in a rat model

AIMS

Recurrent pregnancy loss (RPL) is one of the most common obstetrical diseases, which is a manifestation of antiphospholipid syndrome (APS) with no effective therapy methods. Autophagy and inflammatory responses both play an important role in the pathogenesis of RPL and hyperoside has been demonstrated to have multifarious bioactivities including enhancing autophagy and anti-inflammation. This study aims to investigate the effect of hyperoside on anticardiolipin (aCL)-IgG fractions-induced pregnancy loss.

MAIN METHODS

In the present study, the effect of hyperoside was evaluated in a rat model of pregnancy loss induced by aCL-IgG fractions isolated from serum of APS patients. The fetuses were counted and the placentas were weighted and the protein expressions of inflammation and autophagy were measured by western blot analysis.

KEY FINDINGS

Treatment with hyperoside (40 mg/kg) improved pregnancy outcome manifest as increasing the weight of fetuses and decreasing the fetal resorption rate. In addition, hyperoside treatment downregulated the expressions of phosphorylated mammalian target of rapamycin (mTOR), phosphorylated p70S6 Kinase (S6K) and inhibited the expressions of Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88) and NF-kB p-p65 in pregnancy loss animal models.

SIGNIFICANCE

Hyperoside attenuated pregnancy loss through regulating mTOR/S6K and TLR4/MyD88/NF-kB signaling pathways, which may provide a potential drug candidate for recurrent pregnancy loss therapy.

Clinical performance of non-criteria antibodies to phospholipids in Chinese patients with antiphospholipid syndrome

BACKGROUND

Increasing evidence suggests the role of non-criteria aPLs as important supplements to the current criteria aPLs in APS. In this study, we evaluated the clinical performance of a panel of non-criteria antibodies to phospholipid antigens, including, phosphatidylserine (aPS), phosphatidylinositol (aPI), sphingomyelin (aSM), phosphatidylcholine (aPC) and phosphatidylethanolamine (aPE) in a well-defined Chinese APS cohort.

METHODS

A total of 229 subjects were tested, including 86 patients with APS, 104 disease controls (DCs) and 39 healthy controls (HCs). Serum IgG/IgM aCL, IgG/IgM aβ2GP1, IgG/IgM aPS, IgG/IgM aPI, IgG/IgM aSM, IgG/IgM aPC, and IgG/IgM aPE were tested by ELISA.

RESULTS

The presence of aPE, aPS, aPI, aPC, and aSM in patients with APS and Disease Controls were 8.1% (7/86) and 1.0% (1/104), 37.2% (32/86) and 9.6% (10/104), 50.0% (43/86) and 8.7% (9/104), 23.3% (20/86) and 1.0% (1/104), and 18.6% (16/86) and 1.9% (2/104), respectively. In criteria aPLs, aCL IgG demonstrated the highest positive likelihood ratio (LR+) of 35.75, followed by LA (LR+ of 13.51) and aCL IgM (LR+ of 11.64). In non-criteria aPLs, aPC IgG demonstrated the highest LR+ of 24.94 followed by aSM IgM (LR+ of 14.97). Importantly, the non-criteria aPLs were detected in 18.8% (3/16) of seronegative APS patients. The criteria aPLs, including LA, IgG aCL and IgG aβ2GPI, were significantly correlated with both arterial thrombosis and venous thrombosis, while the non-criteria aPLs, including IgG aPS, IgM aPS, IgG aPI and IgG aPC were significantly associated with arterial thrombosis but not venous thrombosis.

CONCLUSIONS

In summary, our findings indicate that those non-criteria aPLs may be particularly helpful for patients in whom APS is highly suspected, but conventional aPLs are repeatedly negative as well as for predicting APS patients with arterial thrombosis.