HLA-DPB1 alleles association of anticardiolipin and anti-beta2GPI antibodies in a large series of European patients with systemic lupus erythematosus

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.

Antiphospholipid syndrome's genetic and epigenetic aspects

Studies on last genetic and epigenetic predisposition to APS are summarized. It is well known that genetic predisposition is in HLA system (DR4 and DRw53) and that lupus anticoagulant (LA) and anticardiolipin antibodies (aCL) are both associated with the same HLA antigens. Other genes, outside the MHC, give their contribution to the development of this autoimmune syndrome, such as IRF5, STAT4 and those related to inherited thrombophilia - factor V Leiden and G20210A prothrombin polymorphisms. Finally, post-transcriptional modifications of anti-beta2GPI antibodies could be implicated too. The most important discovery of last years is that altered microRNAs' expression is linked to autoimmunity, thrombosis, early atherosclerosis, and oxidative stress in APS.

Insights into the diagnosis and pathogenesis of the antiphospholipid syndrome

The Antiphospholipid syndrome (APS), formerly known as Anticardiolipin or Hughes syndrome, is a systemic autoimmune disorder characterized by obstetrical complications and thrombotic events affecting almost every organ-system in patients persistently testing positive for antiphospholipid antibodies (aPL). The contribution of the extra-criteria aPL to the pathogenesis of APS have exceeded the expectations of a simple, direct pathologic 'hit' leading to thrombogenesis or obstetrical complications, and more pathologic pathways are being linked directly or indirectly to aPL. The value of extra-criteria aPL is on the rise, and these antibodies are nowadays evaluated as markers for risk assessment in the diagnostic approach to APS. A diagnosis of APS should be considered in pediatric patients with suggestive clinical and laboratory picture. Management of APS remains mostly based on anticoagulation, while other drugs are being tested for efficacy and side effects. Low-dose aspirin may have a role in the management of thrombotic and obstetric APS. Due to the high variability in disease severity and complication recurrence outcomes, new tools are being developed and validated to assess the damage index and quality of life of APS patients.

Is HLA class II susceptibility to primary antiphospholipid syndrome different from susceptibility to secondary antiphospholipid syndrome?

To assess whether the major histocompatibility complex (MHC) profile of patients presenting with primary antiphospholipid syndrome (PAPS) is different from that of patients with secondary antiphospholipid syndrome (SAPS), we studied 123 patients, 34 of whom presented PAPS and 35 SAPS due to systemic lupus erythematosus (SLE), 54 SLE patients without antiphospholipid syndrome (APS), and 166 controls. HLA-DRB1 and DQB1 alleles were typed using amplified DNA hybridized with sequence-specific primers. Compared to controls, PAPS patients exhibited a nonsignificantly increased frequency of DR53-associated alleles, and SAPS patients presented an increased frequency of HLA-DRB1* 03 alleles (corrected P 0.05). In addition, HLA-DRB1* 03 alleles were over-represented in SAPS patients presenting anticardiolipin antibody (aCL) (Pc 0.02), in SLE patients as a whole (Pc < 0.0001), and in SLE patients without APS (Pc 0.02). The frequency of aCL among SLE patients presenting or not HLA-DRB1* 03 alleles was closely similar. A trend to an increase in the frequency of the DQB1* 0604 allele (14.3 versus 4.2%, P 0.03) and of the DQB1*0302 allele (31.4 versus 12.7%, P 0.01) was observedin SAPS. Taken together, these results indicate that the association of SAPS with HLA-DRB1* 03 is due to the association with SLE and is not due to aCL, and suggest that the HLA class II profile of PAPS is different from that of SAPS.

Catastrophic Antiphospholipid Syndrome

Catastrophic antiphospholipid syndrome is a rapidly progressive life-threatening disease that causes multiple organ thromboses and dysfunction in the presence of antiphospholipid antibodies. A high index of clinical suspicion and careful investigation are required to make an early diagnosis so that treatment with anticoagulation and corticosteroids can be initiated; plasma exchange and/or intravenous immunoglobulins can be added if the life-threatening condition persists. Despite aggressive treatment and intensive care unit management, patients with catastrophic antiphospholipid syndrome have a 48% mortality rate, primarily attributable to cardiopulmonary failure. This article reviews the current information on the etiopathogenesis, clinical manifestations, diagnosis, management, and prognosis of catastrophic antiphospholipid syndrome.

LDLR and PCSK9 Are Associated with the Presence of Antiphospholipid Antibodies and the Development of Thrombosis in aPLA Carriers

Introduction

The identification of the genetic risk factors that could discriminate non- thrombotic from thrombotic antiphospholipid antibodies (aPLA) carriers will improve prognosis of these patients. Several human studies have shown the presence of aPLAs associated with atherosclerotic plaque, which is a known risk factor for thrombosis. Hence, in order to determine the implication of atherosclerosis in the risk of developing thrombosis in aPLA positive patients, we performed a genetic association study with 3 candidate genes, APOH, LDLR and PCSK9.

Material & Methods

For genetic association study we analyzed 190 aPLA carriers -100 with non-thrombotic events and 90 with thrombotic events- and 557 healthy controls. Analyses were performed by χ2 test and were corrected by false discovery rate. To evaluate the functional implication of the newly established susceptibility loci, we performed expression analyses in 86 aPLA carrier individuals (43 with thrombotic manifestations and 43 without it) and in 45 healthy controls.

Results

Our results revealed significant associations after correction in SNPs located in LDLR gene with aPLA carriers and thrombotic aPLA carriers, when compared with healthy controls. The most significant association in LDLR gene was found between SNP rs129083082 and aPLA carriers in recessive model (adjusted P-value = 2.55 x 10⁻³; OR = 2.18; 95%CI = 1.49–3.21). Furthermore, our work detected significant allelic association after correction between thrombotic aPLA carriers and healthy controls in SNP rs562556 located in PCSK9 gene (adjusted P-value = 1.03 x 10⁻²; OR = 1.60; 95%CI = 1.24–2.06). Expression level study showed significantly decreased expression level of LDLR gene in aPLA carriers (P-value <0.0001; 95%CI 0.16–2.10; SE 0.38–1.27) in comparison to the control group.

Discussion

Our work has identified LDLR gene as a new susceptibility gene associated with the development of thrombosis in aPLA carriers, describing for the first time the deregulation of LDLR expression in individuals with aPLAs. Besides, thrombotic aPLA carriers also showed significant association with PCSK9 gene, a regulator of LDLR plasma levels. These results highlight the importance of atherosclerotic processes in the development of thrombosis in patients with aPLA.

Genetic aspects of the antiphospholipid syndrome: An update

Studies on the immunogenetic predisposition to antiphospholipid syndrome (APS) and on other non-genetic and epigenetic factors are summarised and discussed. Family studies suggest a genetic predisposition to APS. It appears that this genetic predisposition is in part accounted for by the HLA system, the most consistent associations being those with DR4 and DRw53. Furthermore, it appears that lupus anticoagulant (LA) and anticardiolipin (aCL) antibodies are both associated with the same HLA antigens. Population studies suggest that HLA genes have a role in conferring susceptibility to develop primary APS, with some differences in different ethnic groups. Other genes, outside the MHC, give their contribution to the development of this autoimmune syndrome, such as IRF5, STAT4 and those related to inherited thrombophilia--factor V Leiden and G20210A prothrombin polymorphisms. Finally, post-transcriptional modifications of anti-beta2GPI antibodies could be implicated too.

14th International Congress on Antiphospholipid Antibodies Task Force Report on Catastrophic Antiphospholipid Syndrome

The 'Task Force on Catastrophic Antiphospholipid Syndrome (CAPS)' was developed on the occasion of the 14th International Congress on Antiphospholipid Antibodies. The objectives of this Task Force were to assess the current knowledge on pathogenesis, clinical and laboratory features, diagnosis and classification, precipitating factors and treatment of this condition in order to address recommendations for future research. This article summarizes the studies analyzed by the Task Force, its recommendations and the future research agenda.

Epigenetic modulation of RFC1, MHC2TA and HLA-DR in systemic lupus erythematosus: association with serological markers and six functional polymorphisms of one-carbon metabolic pathway

The current study was conducted to elucidate the effect of genetic variations in one-carbon metabolism on the epigenetic regulation of major histocompatibility complex II transactivator (MHC2TA), reduced folate carrier 1 (RFC1/SLC19A1) and human leukocyte antigen (HLA)-DR in systemic lupus erythematosus (SLE). PCR-RFLP/AFLP, bisulfite-sequencing and real-time PCR approaches were used for genetic, epigenetic and expression analysis respectively. SLE cases exhibited elevated plasma homocysteine levels compared to healthy controls (24.93 ± 1.3 vs. 11.67 ± 0.48 μmol/l), while plasma folate levels showed no association (7.10 ± 2.49 vs. 7.64 ± 2.09 ng/ml). The RFC1 80G>A polymorphism showed 1.32-fold risk (95% CI: 1.02-1.72) for SLE, while glutamate carboxypeptidase II (GCPII) 1561C>T showed reduced risk (OR: 0.47, 95% CI: 0.24-0.90). The expression of RFC1 (0.37 ± 0.09 vs. 0.60 ± 0.17) and HLA-DR (0.68 ± 0.17 vs. 0.98 ± 0.02) was down regulated in the SLE cases. The hypermethylation of RFC1 as observed in the current study may contribute for its down regulation. Plasma folate and thymidylate synthase (TYMS) 5'-UTR 28 bp tandem repeat showed an inverse association with methylation of RFC1 and MHC2TA. SLE cases with hypocomplementemia showed hypermethylation of RFC1, hypomethylation/up regulation of MHC2TA and down regulation of HLA-DR. The hypermethylation of MHC2TA and down regulation of RFC1, MHC2TA and HLA-DR were observed in anti-cardiolipin antibody positive SLE cases. The up regulation of RFC1 and HLA-DR was observed in anti-dsDNA antibody positive SLE cases. The hypomethylation/upregulation of RFC1 and MHC2TA was observed in anti-RNP antibody positive cases. To conclude, one-carbon genetic variants influence epigenetic of MHC2TA and RFC1, thus contributing to phenotypic heterogeneity of SLE.

Classical HLA-DRB1 and DPB1 alleles account for HLA associations with primary biliary cirrhosis

Susceptibility to primary biliary cirrhosis (PBC) is strongly associated with HLA region polymorphisms. To determine if associations can be explained by classical HLA determinants we studied Italian 676 cases and 1440 controls with genotyped with dense single nucleotide polymorphisms (SNPs) for which classical HLA alleles and amino acids were imputed. Although previous genome-wide association studies and our results show stronger SNP associations near DQB1, we demonstrate that the HLA signals can be attributed to classical DRB1 and DPB1 genes. Strong support for the predominant role of DRB1 is provided by our conditional analyses. We also demonstrate an independent association of DPB1. Specific HLA-DRB1 genes (*08, *11 and *14) account for most of the DRB1 association signal. Consistent with previous studies, DRB1*08 (p = 1.59 × 10⁻¹¹) was the strongest predisposing allele where as DRB1*11 (p = 1.42 × 10⁻¹⁰) was protective. Additionally DRB1*14 and the DPB1 association (DPB1*03:01) (p = 9.18 × 10⁻⁷) were predisposing risk alleles. No signal was observed in the HLA class 1 or class 3 regions. These findings better define the association of PBC with HLA and specifically support the role of classical HLA-DRB1 and DPB1 genes and alleles in susceptibility to PBC.

Proteomic analysis in monocytes of antiphospholipid syndrome patients: deregulation of proteins related to the development of thrombosis

OBJECTIVE

Antiphospholipid antibodies (aPL) are closely related to the development of thrombosis, but the exact mechanism(s) leading to thrombotic events remains unknown. In this study, using proteomic techniques, we evaluated changes in protein expression of monocytes from patients with antiphospholipid syndrome (APS) related to the pathophysiology of the syndrome.

METHODS

Fifty-one APS patients were included. They were divided into 2 groups: patients with previous thrombosis, and patients with recurrent spontaneous abortion. As controls, we studied patients with thrombosis but without aPL, and age- and sex-matched healthy subjects.

RESULTS

The proteins that were more significantly altered among monocytes from APS patients with thrombosis (annexin I, annexin II, protein disulfide isomerase, Nedd8, RhoA proteins, and Hsp60) were functionally related to the induction of a procoagulant state as well as to autoimmune-related responses. Proteins reported to be connected to recurrent spontaneous abortion (e.g., fibrinogen and hemoglobin) were also determined to be significantly deregulated in APS patients without thrombosis. In vitro treatment with IgG fractions purified from the plasma of APS patients with thrombosis changed the pattern of protein expression of normal monocytes in the same way that was observed in vivo for monocytes from APS patients with thrombosis.

CONCLUSION

For the first time, proteomic analysis has identified novel proteins that may be involved in the pathogenic mechanisms of APS, thus providing potential new targets for pathogenesis-based therapies for the disease.

Proteomics in antiphospholipid syndrome: a review

The presence of antiphospholipid antibodies (aPL) has been closely related to the development of thrombosis and complications in pregnancy. However, not all patients with aPL will develop those clinical features. The exact pathogenic mechanisms leading to thrombosis and/or pregnancy morbidity are poorly understood. Currently, biomarkers which enable one to predict the prognosis of patients with positive aPL are not readily available. Current advances in genomics and proteomics provide the opportunity to discover novel biomarkers based on changes in concentration levels or post-translational modifications of proteins and peptides. These techniques are now being applied in various areas of medicine with very promising results. This review covers recent studies that have used this approach for a better understanding of the pathogenic mechanisms involved in the development of thrombosis in patients with antiphospholipid syndrome (APS). Although, there are very few qualified biomarkers that have arisen as a result of efforts in proteomics, it is expected that these techniques will deliver biomarkers that might ultimately identify different subgroups of APS patients with various prognoses that might have implications with respect to management and prognosis. Lupus (2010) 19, 385—388.

Infection—genetics relationship in systemic lupus erythematosus

Genetic, environmental, and hormonal factors contribute to disease susceptibility in systemic lupus erythematosus. Among environmental factors, infectious agents play a major role. When considering the complex relationship between genetic predisposition and infections in the pathogenesis of systemic lupus erythematosus, we have to consider that infectious agents can interact with the immune system in several ways. For example, molecular mimicry, altered apoptosis of the host cells, exposure of as yet masked antigens to the immune system by a given microorganism, and direct viral invasion of immunocompetent cells are all mechanisms that may give rise to dysfunction of the immune system; in addition, some genetically determined deficit of the immune system, such as complement deficiency or deficit of mannose binding lectine, may cause insufficient clearance of infectious agents, whose persistence in the host may determine autoimmunity. Finally, evidence has been emerging suggesting that the production of autoantibodies, by infected B-lymphocytes, may be drawn by altered expression of particular microRNA in these cells. In this paper, we review some of the distinct scenarios that can account for the role of infectious agents, acting on a genetically prone host, in determining systemic lupus erythematosus.

Immunogenetic studies on systemic lupus erythematosus

Understanding the pathogenesis of systemic lupus erythematosus (SLE) remains a considerable challenge. Multiple abnormalities of both the innate and adaptive immune system have been described and, furthermore, immunological dysfunction precedes clinical presentation by many years. There is a strong genetic basis to SLE, which means that genetic studies can play a key role in furthering our understanding of this disease. Because susceptibility variants are present from birth and are unaffected by the course of the disease, or by its treatment, genetic analysis is, perhaps uniquely, capable of identifying fundamental, causative, disease mechanisms. In this article, we review our SLE immunogenetic studies performed in collaboration with the European Working Party on Systemic Lupus Erythematosus. By considering the results of our research and the recent advances obtained by genome-wide associations' studies, we can begin to understand how dysregulation at a number of key immunological steps may predispose to the development of SLE.

European Working Party on Systemic Lupus Erythematosus: A 15-year report

The "European Working Party on Systemic Lupus Erythematosus" was created 15 years ago in order to promote research in Europe on the different problems related to this disease. Nowadays, more than 50 European centres are collaborating in this venture, 9 large multicentre studies are ongoing and 10 workshops have been organized.

Ethnic and geographical variation in antiphospholipid (Hughes) syndrome

Investigation of the clinical epidemiology of the antiphospholipid syndrome (APS) is in its early stages. During the past 20 years, studies of antiphospholipid antibodies (aPL) and APS have been made in many countries and ethno-geographical groups. aPL appear to occur in all populations studied, with some variations noted in their frequency and in the clinical complications. Environmental and genetic factors contribute to ethnic variation and susceptibility to APS and thus inter-ethnic differences in disease patterns may be due to environmental or genetic factors, or both.

Genetics of antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by recurrent arterial or venous thrombosis or fetal loss and the presence of antiphospholipid antibodies (aPL). Genetic factors are thought to play a role in the susceptibility to APS. Similar to many other polygenic autoimmune diseases, human leukocyte antigen associations have been reported. The genetics of b(2)-glycoprotein I, one of the most representative target antigens of aPL, has been extensively studied. Additional genetic risk factors for the development of thrombosis in patients with aPL have also been discussed. However, the genes involved in APS have not been identified because antigen specificity of aPL and the pathophysiology of APS are highly heterogeneous and multifactorial. Genome-wide linkage analysis and larger cohort studies would lead to better understanding of the genes that might be involved in APS.