Cardiac Manifestations Of Neonatal Lupus Research Articles

Maternal Anti-Ro Antibody Titers Obtained With Commercially Available Immunoassays Are Strongly Associated With Immune-Mediated Fetal Heart Disease.

Anti-Ro antibody-positive mothers are frequently referred for serial echocardiography due to the fetal risk of developing heart block and endocardial fibroelastosis. Little is known why only some and not all offspring develop these cardiac manifestations of neonatal lupus (CNL). This prospective study examined associations between anti-Ro antibody titers and fetal CNL. Antibody-positive mothers referred since 2018 for fetal echocardiography at risk of CNL (group 1; n=240) or with CNL (group 2; n=18) were included. Maternal antibody titers were measured with a chemiluminescent immunoassay (CIA). Additional testing on diluted serum samples was used to quantify anti-Ro 60 antibody titers above the analytical measuring range (AMR) of the standard CIA (≥1,375 chemiluminescent units [CU]). Among 27 total mothers with a fetal diagnosis of CNL, all displayed anti-Ro 60 antibody titers that exceeded the AMR of the CIA at least 10-fold. Of 122 mothers in group 1 who underwent additional anti-Ro 60 antibody testing, event rates of CNL (n=9) were 0% (0 of 45) among mothers with anti-Ro 60 antibody titers from 1,375-10,000 CU, 5% (3 of 56) among mothers with titers from 10,000-50,000 CU, but 29% (6 of 21) among mothers with titers >50,000 CU (odds ratio 13.1, P = 0.0008). Of mothers in group 2 with a primary diagnosis of CNL, 0% (0 of 18 mothers) had anti-Ro 60 antibody titers <10,000 CU, 44% (8 of 18 mothers) had titers from 10,000-50,000 CU, and 56% (10 of 18 mothers) had titers >50,000 CU. CNL is associated with substantially higher anti-Ro antibody titers than are obtained using a standard CIA. Enhancing the assay measuring range allows an improved specificity of identifying pregnancies at risk of CNL.

Contribution of S100A4-expressing fibroblasts to anti-SSA/Ro-associated atrioventricular nodal calcification and soluble S100A4 as a biomarker of clinical severity.

Fibrosis and dystrophic calcification disrupting conduction tissue architecture are histopathological lesions characterizing cardiac manifestations of neonatal lupus (cardiac-NL) associated with maternal anti-SSA/Ro antibodies. Increased appreciation of heterogeneity in fibroblasts encourages re-examination of existing models with the consideration of multiple fibroblast subtypes (and their unique functional differences) in mind. This study addressed fibroblast heterogeneity by examining expression of α-Smooth Muscle Actin (myofibroblasts) and of S100 Calcium-Binding Protein A4 (S100A4). Using a previously established model of rheumatic scarring/fibrosis in vitro, supported by the evaluation of cord blood from cardiac-NL neonates and their healthy (anti-SSA/Ro-exposed) counterparts, and autopsy tissue from fetuses dying with cardiac-NL, the current study was initiated to more clearly define and distinguish the S100A4-positive fibroblast in the fetal cardiac environment. S100A4 immunostaining was observed in 4 cardiac-NL hearts with positional identity in the conduction system at regions of dystrophic calcification but not fibrotic zones, the latter containing only myofibroblasts. In vitro, fibroblasts cultured with supernatants of macrophages transfected with hY3 (noncoding ssRNA) differentiated into myofibroblasts or S100A4+ fibroblasts. Myofibroblasts expressed collagen while S100A4+ fibroblasts expressed pro-angiogenic cytokines and proteases that degrade collagen. Cord blood levels of S100A4 in anti-SSA/Ro-exposed neonates tracked disease severity and, in discordant twins, distinguished affected from unaffected. These findings position the S100A4+ fibroblast alongside the canonical myofibroblast in the pathogenesis of cardiac-NL. Neonatal S100A4 levels support a novel biomarker of poor prognosis.

ANTENATAL DIAGNOSIS OF FETAL HEART RHYTHM DISORDERS IN WOMEN WITH LUPUS WITH POSITIVE ANTI-SSA AND ANTI-SSB ANTIBODIES: ABOUT TWO CASES

Lupus erythematosus is a nonorgan-specific autoimmune disease predominantly affecting young women of childbearing age, as well as neonatal lupus is a complication related to the presence of anti-SSA/Ro or anti-SSb/La antibodies in the mother. Cardiac manifestations of neonatal lupus include anti-SSA/Ro-SSB/La-mediated conduction system disease and endocardial/myocardial damage resulting in cardiomyopathy. Pregnancy is a complicating factor in lupus erythematosus in 60% of cases. These complications do not seem to be related to the number of pregnancies or to the duration of remission, but stopping the hydroxychloroquine treatment could be the cause of relapses. Obstetrical complications due to lupus are dominated by intrauterine growth retardation and prematurity in 30% of cases, abortion or fetal death in utero in 20% of cases, especially in the presence of anti-phospholipid antibodies and/or anti-cardiolipin antibodies in the mother, and complete atrioventricular block in 1.6% of cases due to trans-placental passage of anti-SSA antibodies. Some treatments, including hydroxychloroquine, corticosteroids, and certain immunosuppressants (azathioprine) are safe, and can and should be maintained if necessary during pregnancy.

NOTCH4 is a possible novel susceptibility gene for dilated cardiomyopathy in the Chinese population: A case-control study.

The incidence of dilated cardiomyopathy (DCM) has increased in recent years, and many studies have sought to further improve the general understanding of this condition. Previous studies have demonstrated that some single nucleotide polymorphisms (SNPs) associated with systemic lupus erythematosus also affect susceptibility to DCM, suggesting that immune-related diseases may share similar genetic susceptibility. Recent large-scale and genome-wide association studies have identified NCR3, NOTCH4, CYP1A2, ITGA1, OPRM1, ST8SIA2, and LINC00704 as genetic risk factors associated with cardiac manifestations of neonatal lupus. Here, we aimed to determine whether these SNPs conferred susceptibility to DCM in the Chinese Han population. We investigated the relationship between these polymorphisms and DCM risk in 273 patients with DCM and 548 healthy controls. Genotyping was performed using MassArray iPLEX system. Logistic regression analysis indicated that the T allele of rs3134942 in NOTCH4 gene increased the risk of DCM by 61% compared with the G allele (Pa =6.57×10-3 ). The SNP rs3134942 was also significantly associated with increased DCM risk in the additive (Pa =6.57×10-3 ) and dominant models (Pa =1.01×10-2 ). Additionally, rs2472299 in CYP1A2 gene showed suggestive association with reduced risk of DCM in the dominant model (Pa =4.24×10-2 ) and was correlated with smoking status in patients with DCM (Pa =1.56×10-2 ). Our findings suggested that rs3134942 in NOTCH4 may be involved in DCM risk. Further, studies in larger and ethnically diverse populations are required to confirm the results reported in this study.

Progress in the pathogenesis and treatment of cardiac manifestations of neonatal lupus.

To provide new insights into pathogenesis, prevention and management of cardiac manifestations of neonatal lupus (cardiac neonatal lupus) and issues pertinent to all anti-SSA/Ro positive individuals of childbearing age. Antibody specificity with high risk for cardiac neonatal lupus remains elusive, but high titers of Ro60, Ro52 or Ro52p200 antibodies appear to be required. Varying antibody specificities to the p200 region of Ro52 can induce first-degree block in a rodent model. In consideration of the contribution of macrophages to inflammation and fibrosis in cardiac neonatal lupus, hydroxychloroquine (HCQ) is being considered as preventive therapy. Cord blood biomarkers support the association of fetal reactive inflammatory and fibrotic components with the development and morbidity of cardiac neonatal lupus. Data from U.S. and French registries do not provide evidence that the prompt use of fluorinated steroids in cases of isolated block significantly alters fetal/neonatal morbidity or mortality. The search for a high-risk cardiac neonatal lupus antibody profile remains, but high-titer antibodies to Ro60 and R052 are a consistent finding, and this may guide the need for fetal echocardiographic surveillance. The uniform use of fluorinated steroids to prevent progression of cardiac neonatal lupus or reduce mortality does not appear justified. HCQ, based on diminishing an inflammatory component of cardiac neonatal lupus, is under consideration as a potential preventive approach.

Neonatal lupus erythematosus.

Neonatal lupus (NL), a passively-acquired autoimmune disease associated with maternal anti-SSA antibody, presents both cardiac manifestations such as cardiac NL and non-cardiac manifestations including rashes, cytopenia, and hepatic abnormalities. Cardiac NL, occurring in 1-2% of anti-SS-A antibody-positive mothers, is a life-threatening complication with a mortality rate of 20% and a pacemaker implantation rate of 70%. In contrast, cutaneous NL, which is more common than cardiac NL, usually resolves in six months. Since half of NL cases occur in asymptomatic mothers, if an infant presents characteristic cutaneous or cardiac manifestations of NL, the mother should be tested for anti-SS-A antibody. In mothers positive for anti-SS-A antibody, the risk of having a child with cardiac NL increases ten-fold and five-fold for a previous child with cardiac NL and cutaneous NL, respectively. A joint American, British, and French retrospective study of NL registries showed that hydroxychloroquine (HCQ) reduced the cardiac NL risk in subsequent pregnancies in mothers who previously had a child with cardiac NL. A prospective open-label study to confirm this effect is being undertaken in the USA. A similar prospective multi-center study will be undertaken in Japan. Establishing a Japanese registry of children with NL and subsequent pregnancies of their mothers will help promote clinical research in NL in Japan.

Circulation Editors’ Picks

<i>Circulation</i> Editors’ Picks

Circulation Editors’ Picks

<i>Circulation</i> Editors’ Picks

Ro60 Requires Y3 RNA for Cell Surface Exposure and Inflammation Associated with Cardiac Manifestations of Neonatal Lupus

Cardiac neonatal lupus (NL) is presumed to arise from maternal autoantibody targeting an intracellular ribonucleoprotein, Ro60, which binds noncoding Y RNA and only becomes accessible to autoantibodies during apoptosis. Despite the importance of Ro60 trafficking in the development of cardiac NL, the mechanism underlying cell surface exposure is unknown. To evaluate the influence of Y RNA on the subcellular location of Ro60 during apoptosis and activation of macrophages, stable Ro60 knockout murine fibroblasts expressing wild-type or mutated FLAG-Ro60 were assessed. FLAG3-Ro60(K170A R174A) binds Y RNA, whereas FLAG3-Ro60(H187S) does not bind Y RNA; fibroblasts expressing these constructs showed equivalent intracellular expression of Ro60. In contrast, apoptotic fibroblasts containing FLAG3-Ro60(K170A R174A) were bound by anti-Ro60, whereas FLAG3-Ro60(H187S) was not surface expressed. RNA interference of mY3 RNA in wild-type fibroblasts inhibited surface translocation of Ro60 during apoptosis, whereas depletion of mY1 RNA did not affect Ro60 exposure. Furthermore, Ro60 was not exposed following overexpression of mY1 in the mY3-depleted fibroblasts. In an in vitro model of anti-Ro60-mediated injury, Y RNA was shown to be an obligate factor for TLR-dependent activation of macrophages challenged with anti-Ro60-opsonized apoptotic fibroblasts. Murine Y3 RNA is a necessary factor to support the surface translocation of Ro60, which is pivotal to the formation of immune complexes on apoptotic cells and a TLR-dependent proinflammatory cascade. Accordingly, the Y3 RNA moiety of the Ro60 ribonucleoprotein imparts a critical role in the pathogenicity of maternal anti-Ro60 autoantibodies.

Brief Report: Enrichment of associations in genes with fibrosis, apoptosis, and innate immunity functions with cardiac manifestations of neonatal lupus

The proposed pathogenesis of the cardiac manifestations of neonatal lupus (cardiac-NL) involves maternal autoantibodies to the RNPs SSA/Ro and SSB/La, enhanced by as-yet-unknown factors that likely involve dysregulation of both inflammatory and fibrotic fetal responses. This study was designed to improve the power to detect specific associations in genes with candidate biologic functions. Using data from our genome-wide association study of 116 Caucasian children with cardiac-NL and 3,351 Caucasian controls, we tested for enrichment of single-nucleotide polymorphism (SNP) associations in genes with candidate biologic functions related to fibrosis, immune function, apoptosis, T cell function, cell infiltration, innate immune cell function, interferon, Toll-like receptors, and calcium channels. After linkage disequilibrium pruning and exclusion of the extended HLA region, a total of 15,103 SNPs in 3,068 genes remained. A highly significant enrichment of P values was observed for genes related to fibrosis (P = 2.27 × 10(-9) ), apoptosis (P = 7.67 × 10(-7) ), and innate immune cell (P = 2.53 × 10(-6) ), immune (P = 5.01 × 10(-4) ), T cell (P = 2.23 × 10(-4) ), and interferon functions (P = 1.64 × 10(-3) ). The most significant non-HLA associations included the sialyltransferase gene ST8SIA2 (rs1487982; odds ratio 2.20 [95% confidence interval 1.52-3.19], P = 3.37 × 10(-5) ), the integrin gene ITGA1 (rs2432143; odds ratio 2.31 [95% confidence interval 1.54-3.45], P = 4.54 × 10(-5) ), and the complement regulator gene CSMD1 (rs7002001; odds ratio 2.41 [95% confidence interval 1.57-3.72], P = 6.33 × 10(-5) ). This study identified novel candidate genes associated with cardiac-NL and highlights the value of studying this cohort for advancing knowledge regarding the genetic etiology of this syndrome. Identification of causal alleles is expected to provide critical insight into the molecular mechanisms responsible for linking maternal autoantibodies to cardiac scarring in these fetuses/neonates.

Connecting the molecular dots from inaccessible antigen to organ injury in the pathogenesis of cardiac manifestations of neonatal lupus

Only 2% of fetuses exposed to anti-SSA/Ro antibodies have cardiac manifestations of neonatal lupus (cardiac NL, referred to herein as congenital heart block), yet these antibodies are present in >85% of mothers whose fetuses are identified with conduction abnormalities in a structurally normal heart. This disparity implies that the antibodies are necessary but insufficient to cause disease, and that the final pathway to fibrosis may be variable: kept totally in check in most fetuses (normal sinus rhythm), subclinical in others (first-degree block) and fully executed in very few (advanced block). A further challenge to defining the pathology of disease is the intracellular location of the target antigens, thus raising questions regarding accessibility to maternal antibodies. Our research has incorporated three components in the presumed cascade from antibody to tissue injury: apoptosis to provide the antigenic complex; macrophage uptake and secretion to drive inflammation and scarring; and persistence of the myofibroblast to drive replacement of healthy cardiac tissue. The totality of experimental data in the last 2 years supports that the watershed may involve conformational properties of Ro60 that influence its surface translocation to an apoptotic cardiocyte surface, its capacity to bind Y RNA and its effect on the biology of the urokinase plasminogen activator (uPA)/urokinase plasminogen activator receptor (uPAR) system. By exploiting murine fibroblast cell lines transfected with Ro60 modified to alter RNA binding sites, very recent data suggest that ssRNA (probably hY3 RNA) is required for surface translocation during apoptosis. However, the accessibility of Ro60 to cognate maternal antibody may be influenced by additional factors. In this regard, Ro60 expressed on the surface of an apoptotic cardiocyte binds domain V of β2GPI with high affinity and effectively blocks binding of anti-Ro60 antibodies. In an important translational step to humans, significantly lower levels of circulating β2GPI are associated with disease as assessed with umbilical cord blood comparing affected and unaffected fetuses. The importance of intact β2GPI as a protective factor became increasingly evident as we continued our search for the molecular explanation of a critical observation that anti-Ro60 antibodies inhibit the uptake of apoptotic cardiocytes by healthy cardiocytes. Although a counter-receptor for Ro60 on the healthy cardiocyte was considered, experiments revealed that anti-Ro60 binding to Ro60 (opsonization, formation of immune complexes) is associated with a conformational change of uPAR resulting in two functional consequences, one of which is a 'don't eat me' signal to healthy cardiocytes. The other is uPA activation leading to proteolytic cleavage of plasminogen and the generation of plasmin. The latter cleaves β2GPI, which renders it incapable of binding to Ro60 thus favoring the continued formation of immune complexes on the apoptotic surface. Moreover, the generation of plasmin also promotes the activation of TGF-β. Accordingly, the uPAR/uPA system plays a profibrotic role in the early and expansive phases of disease and the levels of uPAR, uPA, and plasminogen are increased in affected fetuses compared with healthy siblings. The potential of ssRNA to perpetuate an inflammatory step via a Toll-like receptor (TLR)7 pathway has been experimentally substantiated by the transdifferentiation of human fetal cardiac fibroblasts to a scarring phenotype following exposure to supernatants generated by incubation of macrophages with surrogate immune complexes comprised of Ro60, hY3 and affinity-purified anti-Ro60 antibody. Further evidence for a macrophage contribution to injury was provided by immunohistochemistry, which demonstrated not only a macrophage infiltrate in three hearts from anti-Ro-exposed fetuses dying with cardiac NL, but the formation of multinucleated giant cells. With regard to the fibroblast, we posit that these cells are themselves a major source of TGF-β and that endothelin-1 is one of the components responsible for the profibrosing effects generated by TLR signaling in the macrophages. The potential pathologic role of TLR signaling prompted the initiation of a case-control study in which we demonstrated that the use of hydroxychloroqine, which inhibits endosomal acidification, decreases the risk of cardiac NL. A prospective study to prevent recurrent disease has just been initiated.

Neonatal lupus

Cardiac manifestations of neonatal lupus include anti-SSA/Ro-SSB/La-mediated conduction system disease and endocardial/myocardial damage resulting in cardiomyopathy. This review will focus on recent data regarding updates on the proposed pathogenesis of disease, morbidity and mortality, and preventive and treatment therapies. Evidence from animal models suggests that reactivity to the p200 region of the Ro52 protein, as well as antibody targeting of L-type calcium channels may be important in the development of cardiac neonatal lupus. In-vitro studies support a protective role of β-2 glycoprotein 1 (prevents anti-Ro binding to apoptotic cells) and pathologic roles of the urokinase-plasminogen activator/receptor system (leads to activation of TGF-β), and endothelin-1 secretion by macrophages in mediating tissue injury. Genetic studies highlight the fetal major histocompatibility complex in the development of disease, and a multigenerational study demonstrates that mothers of neonatal lupus children accumulate genetic risk factors preferentially from the neonatal lupus child's grandparents. Retrospective studies identify demographic and echocardiographic risk factors for morbidity and mortality and address the role of fluorinated steroids, intravenous immunoglobulin and hydroxychloroquine for prevention and treatment of disease. Animal studies, in-vitro experiments, genetic analysis and clinical-translational research in cardiac neonatal lupus reveal novel insights and targets for therapy in this often devastating disease.

Umbilical cord blood levels of maternal antibodies reactive with p200 and full‐length Ro 52 in the assessment of risk for cardiac manifestations of neonatal lupus

Maternal anti-Ro autoantibodies are associated with cardiac manifestations of neonatal lupus (cardiac NL), yet only 2% of women with this reactivity have an affected child. Identification of a more specific marker would channel intense monitoring to fetuses at greater risk. This study aimed to determine whether autoantibodies against Ro 52 amino acids 200-239 (p200) confer added risk over autoantibodies to full-length Ro 52, Ro 60, or La. Anti-Ro-exposed pregnancies resulting in cardiac NL or no cardiac manifestations were identified from the Research Registry for Neonatal Lupus and the PR Interval and Dexamethasone Evaluation study. Umbilical cord (n = 123) and maternal (n = 115) samples were evaluated by enzyme-linked immunosorbent assay. The frequencies of p200, Ro 52, Ro 60, and La autoantibodies were not significantly different between affected and unaffected children. However, neonatal anti-Ro 52 and Ro 60 titers were highest in cardiac NL and their unaffected siblings compared to unaffected neonates without a cardiac NL sibling. Although both maternal anti-Ro 52 and p200 autoantibodies were less than 50% specific for cardiac NL, anti-p200 was the least likely of the Ro autoantibodies to be false-positive in mothers who have never had an affected child. Titers of anti-Ro 52 and p200 did not differ during a cardiac NL or unaffected pregnancy from the same mother. Maternal reactivity to p200 does not confer an added risk to fetal conduction defects over full-length Ro 52 or Ro 60 autoantibodies. Mothers who may never be at risk for having an affected child have lower anti-Ro 60 titers and may require less stringent echocardiographic monitoring compared to women with high-titer autoantibodies.

Maternal Use of Hydroxychloroquine Is Associated With a Reduced Risk of Recurrent Anti-SSA/Ro-Antibody–Associated Cardiac Manifestations of Neonatal Lupus

A recent case-control study suggested a benefit of hydroxychloroquine (HCQ) in lowering the risk of cardiac manifestations of neonatal lupus (cardiac-NL) in pregnancies of anti-SSA/Ro-positive patients with systemic lupus erythematosus. A historical cohort assembled from 3 international databases was used to evaluate whether HCQ reduces the nearly 10-fold increase in risk of recurrence of cardiac-NL independently of maternal health status. Two hundred fifty-seven pregnancies of anti-SSA/Ro-positive mothers (40 exposed and 217 unexposed to HCQ) subsequent to the birth of a child with cardiac-NL were identified from 3 databases (United States, England, and France). Exposure was defined as the sustained use of HCQ throughout pregnancy with initiation before 10 weeks of gestation. The recurrence rate of cardiac-NL in fetuses exposed to HCQ was 7.5% (3 of 40) compared with 21.2% (46 of 217) in the unexposed group (P=0.050). Although there were no deaths in the exposed group, the overall case fatality rate of the cardiac-NL fetuses in the unexposed group was 21.7%. In a multivariable analysis that adjusted for database source, maternal race/ethnicity, and anti-SSB/La status, HCQ use remained significantly associated with a decreased risk of cardiac-NL (odds ratio, 0.23; 95% confidence interval, 0.06-0.92; P=0.037). Similar results were obtained with propensity score analysis, an alternative approach to adjust for possible confounding by indication. Aggregate data from a multinational effort show that in mothers at high risk of having a child with cardiac-NL, the use of HCQ may protect against recurrence of disease in a subsequent pregnancy.

Cardiac Manifestations of Neonatal Lupus

Within the last decade the prevalence of adult patients living with congenital heart disease equals that seen in children. This expanding population poses a challenge to clinical cardiologists who will be caring for patients with the clinical manifestations of this condition. Neonatal lupus is a model of passively acquired autoimmunity and is responsible for the majority of clinical cases of congenital heart block (CHB). This review will focus on the presentation, pathophysiology, and the long-term follow-up of CHB associated with neonatal lupus, and discuss important diagnostic tests, familial implications, and pacemaker issues associated with the care of an adult with CHB.

Anatomical and pathological findings in hearts from fetuses and infants with cardiac manifestations of neonatal lupus

The autopsy and clinical information on children dying with anti-SSA/Ro-associated cardiac manifestations of neonatal lupus (cardiac NL) were examined to identify patterns of disease, gain insight into pathogenesis and enhance the search for biomarkers and preventive therapies. A retrospective analysis evaluating reports from 18 autopsies of cardiac NL cases and clinical data from the Research Registry for Neonatal Lupus was performed. Of the 18 cases with autopsies, 15 had advanced heart block, including 3 who died in the second trimester, 9 in the third trimester and 3 post-natally. Three others died of cardiomyopathy without advanced block, including two dying pre-natally and one after birth. Pathological findings included fibrosis/calcification of the atrioventricular (AV) node, sinoatrial (SA) node and bundle of His, endocardial fibroelastosis (EFE), papillary muscle fibrosis, valvular disease, calcification of the atrial septum and mononuclear pancarditis. There was no association of pathology with the timing of death except that in the third-trimester deaths more valvular disease and/or extensive conduction system abnormalities were observed. Clinical rhythm did not always correlate with pathology of the conduction system, and the pre-mortem echocardiograms did not consistently detect the extent of pathology. Fibrosis of the AV node/distal conduction system is the most characteristic histopathological finding. Fibrosis of the SA node and bundle of His, EFE and valve damage are also part of the anti-Ro spectrum of injury. Discordance between echocardiograms and pathology findings should prompt the search for more sensitive methods to accurately study the phenotype of antibody damage.

Discordant spectrum of cardiac manifestations of neonatal lupus in twins

Congenital complete heart block associated with transplacental passage of maternal autoantibodies reactive with SSA/Ro and SSB/La is a rare disease with significant fetal, neonatal, and childhood morbidity and mortality. We present the case of dichorionic, diamniotic twins (female twin A and male twin B) exposed to maternal Ro and La autoantibodies with different disease expression. Twin A (female) had Mobitz type I second degree atrioventricular (AV) block (Wenckebach); twin B (male) had normal sinus rhythm. Both twins had structurally normal hearts but demonstrated echocardiographic evidence of endocardial fibroelastosis (EFE). Following maternal dexamethasone 4 mg once daily, twin A reverted to sinus rhythm in utero; twin B remained in sinus rhythm throughout pregnancy. Echocardiograms after delivery demonstrated resolution of EFE in both fetuses, and EKGs confirmed sinus rhythm. However, at five months of age, Holter monitor demonstrated first degree AV block and intermittent Wenckebach in twin A. Twin B remains in sinus rhythm. This case is one of only three in the literature that describes Mobitz type I second degree atrioventricular block presenting in fetuses exposed to maternal SSA and SSB autoantibodies and is the first case that we have seen reported in twins. Importantly, this case also adds to the growing body of literature describing EFE as a presentation of neonatal lupus with or without conduction system abnormalities, emphasizes the spectrum of cardiac conduction abnormalities in neonatal lupus syndrome, and raises interesting questions about discordant disease expression in twins.

Circulation: Clinical Summaries

Circulation: Clinical Summaries

β2-Glycoprotein I and Protection from Anti-SSA/Ro60–Associated Cardiac Manifestations of Neonatal Lupus

One mechanism to molecularly explain the strong association of maternal anti-Ro60 Abs with cardiac disease in neonatal lupus (NL) is that these Abs initiate injury by binding to apoptotic cardiomyocytes in the fetal heart. Previous studies have demonstrated that β(2)-glycoprotein I (β(2)GPI) interacts with Ro60 on the surface of apoptotic Jurkat cells and prevents binding of anti-Ro60 IgG. Accordingly, the current study was initiated to test two complementary hypotheses, as follows: 1) competition between β(2)GPI and maternal anti-Ro60 Abs for binding apoptotic induced surface-translocated Ro60 occurs on human fetal cardiomyocytes; and 2) circulating levels of β(2)GPI influence injury in anti-Ro60-exposed fetuses. Initial flow cytometry experiments conducted on apoptotic human fetal cardiomyocytes demonstrated dose-dependent binding of β(2)GPI. In competitive inhibition experiments, β(2)GPI prevented opsonization of apoptotic cardiomyocytes by maternal anti-Ro60 IgG. ELISA was used to quantify β(2)GPI in umbilical cord blood from 97 neonates exposed to anti-Ro60 Abs, 53 with cardiac NL and 44 with no cardiac disease. β(2)GPI levels were significantly lower in neonates with cardiac NL. Plasmin-mediated cleavage of β(2)GPI prevented binding to Ro60 and promoted the formation of pathogenic anti-Ro60 IgG-apoptotic cardiomyocyte complexes. In aggregate these data suggest that intact β(2)GPI in the fetal circulation may be a novel cardioprotective factor in anti-Ro60-exposed pregnancies.

Identification of candidate loci at 6p21 and 21q22 in a genome‐wide association study of cardiac manifestations of neonatal lupus

Cardiac manifestations of neonatal lupus, comprising atrioventricular conduction defects and cardiomyopathy, occur in fetuses exposed to anti-Ro/SSA antibodies, and carry substantial mortality. There is strong evidence of a genetic contribution to the risk. This study was undertaken to evaluate single-nucleotide polymorphisms (SNPs) for associations with cardiac neonatal lupus. Children of European ancestry with cardiac neonatal lupus (n = 116) were genotyped using the Illumina 370K SNP platform and merged with 3,351 controls. Odds ratios (ORs) and 95% confidence intervals (95% CIs) for association with cardiac neonatal lupus were determined. The 17 most significant associations with cardiac neonatal lupus were found in the HLA region. The region near the MICB gene showed the strongest variant (rs3099844; P(dom) = 4.52 × 10(-10) , OR 3.34 [95% CI 2.29-4.89]), followed by a missense variant within C6orf10 (rs7775397; P(dom) = 1.35 × 10(-9) , OR 3.30), which lies between NOTCH4 and BTNL2, and several SNPs near the tumor necrosis factor α gene, including rs2857595 (P(add) = 1.96 × 10(-9) , OR 2.37), rs2230365 (P(add) = 1.00 × 10(-3) , OR 0.46), and rs3128982 (P(add) = 6.40 × 10(-6) , OR 1.86). Outside the HLA region, an association was detected at 21q22, upstream of the transcription regulator ets-related isoform 1 (rs743446; P = 5.45 × 10(-6) , OR 2.40). HLA notwithstanding, no individual locus previously implicated in autoimmune diseases achieved genome-wide significance. These results suggest that variation near genes related to inflammatory and apoptotic responses may promote cardiac injury initiated by passively acquired autoantibodies.