Autoantibodies associated with congenital heart block

Use of Polynomial Reference Ranges for Atrioventricular Intervals Assessed by Fetal Echocardiography in Anti-Ro/SSA Antibody-Positive Pregnancies to Exclude Fetal Heart Blocks: A Pilot Study

INTRODUCTION

Maternal anti-Ro/SSA antibodies can cause fetal atrioventricular blocks (AVB). This pilot study aims to apply previously published echocardiographic reference ranges of the fetal atrioventricular (AV) intervals in the setting of anti-Ro/SSA antibody-positive pregnancies in order to exclude a 1° AVB.

MATERIALS AND METHODS

Between January 2018 and September 2022, we included all women with known anti-Ro/SSA antibodies followed up at the prenatal ultrasound department of the University Hospital of Bern. AV intervals were serially measured by two previously reported methods and plotted against previously created reference ranges.

RESULTS

We included 23 pregnancies from 17 anti-Ro/SSA antibody-positive women with connective tissue diseases. 443 AV interval measurements were recorded between 16+3 and 38+4 weeks of gestation. 14 (3.2%) AV-intervals measured >150 ms, none measured >170 ms and 8 (1.8%) were found to be >95th percentile. In none of the pregnancies, serial AV-prolongations were noted. The postnatal electrocardiograms demonstrated normal sinus rhythm without AVB in all children.

CONCLUSION

AV intervals of pregnancies followed up for anti-Ro/SSA antibodies without neonatal AVB lie within our published polynomial reference ranges. While diagnosing a 1° AVB remains controversial, more data are needed to prove that our reference ranges are helpful exclude a 1° AVB.

Auxilin is a novel susceptibility gene for congenital heart block which directly impacts fetal heart function

OBJECTIVE

Neonatal lupus erythematosus (NLE) may develop after transplacental transfer of maternal autoantibodies with cardiac manifestations (congenital heart block, CHB) including atrioventricular block, atrial and ventricular arrhythmias, and cardiomyopathies. The association with anti-Ro/SSA antibodies is well established, but a recurrence rate of only 12%-16% despite persisting maternal autoantibodies suggests that additional factors are required for CHB development. Here, we identify fetal genetic variants conferring risk of CHB and elucidate their effects on cardiac function.

METHODS

A genome-wide association study was performed in families with at least one case of CHB. Gene expression was analysed by microarrays, RNA sequencing and PCR and protein expression by western blot, immunohistochemistry, immunofluorescence and flow cytometry. Calcium regulation and connectivity were analysed in primary cardiomyocytes and cells induced from pleuripotent stem cells. Fetal heart performance was analysed by Doppler/echocardiography.

RESULTS

We identified DNAJC6 as a novel fetal susceptibility gene, with decreased cardiac expression of DNAJC6 associated with the disease risk genotype. We further demonstrate that fetal cardiomyocytes deficient in auxilin, the protein encoded by DNAJC6, have abnormal connectivity and Ca²⁺ homoeostasis in culture, as well as decreased cell surface expression of the Ca_v1.3 calcium channel. Doppler echocardiography of auxilin-deficient fetal mice revealed cardiac NLE abnormalities in utero, including abnormal heart rhythm with atrial and ventricular ectopias, as well as a prolonged atrioventricular time intervals.

CONCLUSIONS

Our study identifies auxilin as the first genetic susceptibility factor in NLE modulating cardiac function, opening new avenues for the development of screening and therapeutic strategies in CHB.

Anti-Ro60 and anti-Ro52/TRIM21: Two distinct autoantibodies in systemic autoimmune diseases

As iconic and important diagnostic autoantibodies, anti-Ro60 and anti-Ro52/tri-partite motif-containing 21 (TRIM21) make a common appearance in a number of systemic autoimmune disorders such as systemic lupus erythematosus (SLE). These autoantibodies often co-exist together; yet despite their close relationship, there is no evidence that they are physically linked and probably reflect a convergence of separate processes of failed immunological tolerance. Confusingly, they are sometimes classed together as the "SSA" or "Ro" autoantibody system without clear distinction between the two. In this Short Communication, we discuss the diagnostic merits for separate detection and reporting of these two autoantibodies, and discuss avenues for future research. Indeed, further insight into their fascinating origins and pathogenic roles in autoimmunity will surely shed light on how we can prevent and treat devastating autoimmune disorders.

Pregnancy outcome in women with different rheumatic diseases: a retrospective analysis

Objective: Pregnancy may influence the course of inflammatory rheumatic diseases and, conversely, rheumatic and musculoskeletal diseases (RMDs) can affect the outcome of pregnancy. This study aimed to retrospectively analyse the outcome of pregnancy and disease in women with RMDs.Method: Subjects were patients with high-risk pregnancy and connective tissue diseases (CTDs) or inflammatory joint diseases (IJDs) managed at a specialized rheumatology outpatient clinic from 2007 to 2014. Data from conception to 6 months postpartum were collected from medical records and a questionnaire, and analysed regarding clinical symptoms, medications, pregnancy complications, birth outcomes, and infant development. Generalized estimating equations were used to compare the groups (CTD vs IJD).Results: The eligible 66 pregnancies in 57 RMD patients were divided into two groups by RMD type: CTD (n = 48) or IJD (n = 18). The live birth rate was 97% overall. Pregnancy complications (excluding two twin pregnancies) were incurred in 39.1%: miscarriage (n = 2), premature delivery (n = 12), small-for-gestational-age infants (n = 5), and/or pregnancy-related diseases (n = 14). Three children born to women with CTDs had affected development (autism spectrum disorder, congenital heart disease, bronchopulmonary dysplasia). CTD infants had a significantly lower mean gestational age (in weeks) (p = 0.042), weight (p = 0.009), and length (p = 0.016) at birth than IJD infants.Conclusion: Although the live birth rate was high, complications occurred in 39.1% of pregnancies in this cohort. Therefore, interdisciplinary management of pregnant women with RMDs at specialized clinics is strongly recommended.

The Role of Autoantibodies in Arrhythmogenesis

PURPOSE OF REVIEW

The role of autoantibodies in arrhythmogenesis has been the subject of research in recent times. This review focuses on the rapidly expanding field of autoantibody-mediated cardiac arrhythmias.

RECENT FINDINGS

Since the discovery of cardiac autoantibodies more than three decades ago, a great deal of effort has been devoted to understanding their contribution to arrhythmias. Different cardiac receptors and ion channels were identified as targets for autoantibodies, the binding of which either initiates a signaling cascade or serves as a biomarker of underlying remodeling process. Consequently, the wide spectrum of heart rhythm disturbances may emerge, ranging from atrial to ventricular arrhythmias as well as conduction diseases, irrespective of concomitant structural heart disease or manifest autoimmune disorder. The time has come to acknowledge autoimmune cardiac arrhythmias as a distinct disease entity. Establishing the autoantibody profile of patients will help to develop novel treatment approaches for patients.

Benefits of fetal echocardiographic surveillance in pregnancies at risk of congenital heart block: single-center study of 212 anti-Ro52-positive pregnancies

OBJECTIVES

Assuming that autoimmune congenital heart block (CHB) is a progressive disease amenable to therapeutic modulation, we introduced a surveillance program for at-risk pregnancies with the dual aim of investigating if fetal atrioventricular block (AVB) could be detected and treated before becoming complete and irreversible, and to establish the incidence of AVB I, II and III in a large prospective cohort.

METHODS

This was a prospective study of 212 anti-Ro52 antibody-exposed pregnancies at risk of fetal AVB that were followed weekly between 18 and 24 weeks' gestation at our tertiary fetal cardiology center from 2000 to 2015. A 12-lead electrocardiogram (ECG) was recorded within 1 week after birth. Fetal Doppler atrioventricular (AV) intervals were converted to Z-scores using reference standard values derived from normal pregnancies. Each fetus was represented by the average value of the two recordings, obtained at two consecutive visits, which resulted in the longest AV interval. AV interval values were classified into normal AV conduction (Z-score ≤ 2.0) and three levels of delayed AV conduction: Z-score > 2.0 and ≤ 3.0, Z-score > 3.0 and ≤ 4.0, and Z-score > 4.0.

RESULTS

AVB II or III developed in 6/204 (2.9%) pregnancies without a CHB history and 1/8 (12.5%) of those with a CHB history. AV intervals > 2 and ≤ 3, > 3 and ≤ 4, and > 4 were detected in 16.0%, 7.5% and 2.8% of cases, respectively, and were related to the PR interval on 185 available ECGs. Three of the five cases with AVB III and one of two cases with 2:1 AVB II developed within 1 week of AV interval Z-score of 1.0, 1.9, 2.8 and 1.9, respectively. Transplacental treatment with betamethasone was associated with restoration of 1:1 AV conduction in the two fetuses with AVB II, with a better long-term result (normal ECG vs AVB I or II) observed in the case in which treatment was started within 1 week after AVB developed. Betamethasone treatment did not reverse AVB III, although a temporary effect on AV conduction was observed in 1/5 cases. Notably, the three cases in which treatment was started within 1 week after AVB III development responded with a higher ventricular rate than the other two cases and did not require pacemaker implantation until a later age (2-5 years vs 1.5-2 months).

CONCLUSION

Fetal AV interval is a poor predictor of CHB progression, but CHB surveillance still allows detection of fetuses with AVB II or III shortly after its development, allowing for timely treatment initiation and potentially better outcome. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Prenatal sonographic monitoring of progressive cardiac damages caused by anti-Ro antibodies: A case report

Maternal autoantibodies to Ro/SSA are often linked to congenital heart block and rarely associated with structural defects. We describe the case of a fetus with anti-Ro-mediated second-degree block at 19 weeks, which progressed to a complete block, fibroelastosis, atrioventricular valve insufficiency, and semilunar valve stenosis/insufficiency at 20, 22, 24, and 26 weeks, respectively, although the fetus received transplacental anti-arrhythmic drugs. The 2150-g fetus was vaginally delivered at 35 weeks. An external pacemaker was inserted immediately after birth and replaced with permanent pacemaker at the age of 3 months. The newborn has had a good outcome with well-controlled heart rate.

Environmental and lifestyle factors influencing risk of congenital heart block during pregnancy in anti-Ro/SSA-positive women

OBJECTIVES

Congenital heart block (CHB) occurs in 1%-2% of anti-Ro/SSA antibody-positive pregnancies. A population-based recurrence rate of 12% indicates that factors other than maternal autoantibodies influence CHB development. Here we report the first investigation to identify environmental and lifestyle factors influencing the risk of CHB.

METHODS

A questionnaire focused on environmental and lifestyle factors was distributed to anti-Ro/SSA antibody-positive women who had given birth to at least one child with CHB, and additional data were retrieved from national health registers. Statistical analysis was performed comparing pregnancies resulting in a child with CHB (n=81) and pregnancies resulting in unaffected siblings (n=108).

RESULTS

Analysis of maternal body mass index and weight gain during pregnancy as well as medication intake and sun exposure did not reveal significant differences between CHB-affected and non-CHB pregnancies. By contrast, we found that reports of infections and stressful events were significantly more frequent in CHB-affected pregnancies than in non-CHB affected pregnancies (OR 17.9, 95% CI 4.1 to 162.8, p<0.001 and OR 5.5, 95% CI 1.1 to 55.1, p<0.05, respectively). Notably, outdoor activity a few hours per day emerged as a protective factor (OR 0.52, 95% CI 0.27 to 0.99, p<0.05). The previously reported factor seasonal timing of pregnancy was confirmed (OR 2.2, 95% CI 1.1 to 4.2, p<0.05), and multivariate analysis revealed that this association was partly explained by infection and outdoor activity.

CONCLUSIONS

In this retrospective study, infections, stressful events and time spent with outdoor activities emerged as potential environmental and lifestyle factors influencing the risk of CHB, warranting confirmation in prospective studies.

The clinical spectrum of autoimmune congenital heart block

Autoimmune congenital heart block (CHB) is an immune-mediated acquired disease that is associated with the placental transference of maternal antibodies specific for Ro and La autoantigens. The disease develops in a fetal heart without anatomical abnormalities that could otherwise explain the block, and which is usually diagnosed in utero, but also at birth or within the neonatal period. Autoantibody-mediated damage of fetal conduction tissues causes inflammation and fibrosis and leads to blockage of signal conduction at the atrioventricular (AV) node. Irreversible complete AV block is the principal cardiac manifestation of CHB, although some babies might develop other severe cardiac complications, such as endocardial fibroelastosis or valvular insufficiency, even in the absence of cardiac block. In this Review, we discuss the epidemiology, classification and management of women whose pregnancies are affected by autoimmune CHB, with a particular focus on the autoantibodies associated with autoimmune CHB and how we should test for these antibodies and diagnose this disease. Without confirmed effective preventive or therapeutic strategies and further research on the aetiopathogenic mechanisms, autoimmune CHB will remain a severe life-threatening disorder.

The challenge of pregnancy for patients with SLE

Pregnancy poses an important challenge for doctors looking after women with systemic lupus erythematosus. Knowledge about safety of medications, the effect of pregnancy on such disease, and vice versa, together with multidisciplinary team care, are basic cornerstones needed to provide the best obstetric and medical care to these women. Pre-conceptional counselling constitutes the ideal scenario where a patient's previous obstetric history, organ damage, disease activity, serological profile and additional medical history can be summarized. Important issues regarding medication adjustment, planned scans and visits, and main risks discussion should also be raised at this stage. Planned pregnancies lead to better outcomes for both mothers and babies. Close surveillance throughout pregnancy and the puerperium, and tailored management approach guarantee the highest rates of successful pregnancies in these women.

The HLA locus contains novel foetal susceptibility alleles for congenital heart block with significant paternal influence

OBJECTIVE

The main aim of this study was to identify foetal susceptibility genes on chromosome six for Ro/SSA autoantibody-mediated congenital heart block.

SUBJECTS AND DESIGN

Single nucleotide polymorphism (SNP) genotyping of individuals in the Swedish Congenital Heart Block (CHB) study population was performed. Low-resolution HLA-A, -Cw and -DRB1 allele typing was carried out in 86 families comprising 339 individuals (86 Ro/SSA autoantibody-positive mothers, 71 fathers, 87 CHB index cases and 95 unaffected siblings).

RESULTS

A case-control comparison between index cases and population-based out-of-study controls (n = 1710) revealed association of CHB with 15 SNPs in the 6p21.3 MHC locus at a chromosome-wide significance of P < 2.59 × 10(-6) (OR 2.21-3.12). In a family-based analysis of association of SNP markers as well as distinct MHC class I and II alleles with CHB, HLA-DRB1*04 and HLA-Cw*05 variants were significantly more frequently transmitted to affected individuals (P < 0.03 and P < 0.05, respectively), whilst HLA-DRB1*13 and HLA-Cw*06 variants were significantly less often transmitted to affected children (P < 0.04 and P < 0.03). We further observed marked association of increased paternal (but not maternal) HLA-DRB1*04 transmission to affected offspring (P < 0.02).

CONCLUSIONS

HLA-DRB1*04 and HLA-Cw*05 were identified as novel foetal HLA allele variants that confer susceptibility to CHB in response to Ro/SSA autoantibody exposure, whilst DRB1*13 and Cw*06 emerged as protective alleles. Additionally, we demonstrated a paternal contribution to foetal susceptibility to CHB for the first time.

To B or not to B cells-mediate a healthy start to life

Maternal immune responses during pregnancy are critical in programming the future health of a newborn. The maternal immune system is required to accommodate fetal immune tolerance as well as to provide a protective defence against infections for the immunocompromised mother and her baby during gestation and lactation. Natural immunity and antibody production by maternal B cells play a significant role in providing such immunoprotection. However, aberrations in the B cell compartment as a consequence of maternal autoimmunity can pose serious risks to both the mother and her baby. Despite their potential implication in shaping pregnancy outcomes, the role of B cells in human pregnancy has been poorly studied. This review focuses on the role of B cells and the implications of B cell depletion therapy in pregnancy. It highlights the evidence of an association between aberrant B cell compartment and obstetric conditions. It also alludes to the potential mechanisms that amplify these B cell aberrances and thereby contribute to exacerbation of some maternal autoimmune conditions and poor neonatal outcomes. Clinical and experimental evidence suggests strongly that maternal autoantibodies contribute directly to the pathologies of obstetric and neonatal conditions that have significant implications for the lifelong health of a newborn. The evidence for clinical benefit and safety of B cell depletion therapies in pregnancy is reviewed, and an argument is mounted for further clinical evaluation of B cell-targeted therapies in high-risk pregnancy, with an emphasis on improving neonatal outcomes and prevention of neonatal conditions such as congenital heart block and fetal/neonatal alloimmune thrombocytopenia.

The predictive value of anti-SS-A antibodies titration in pregnant women with fetal congenital heart block

OBJECTIVE

Fetal congenital complete heart block (CHB) is irreversible and is associated with significant mortality and morbidity. Anti-SS-A antibodies in the maternal sera are involved in its pathogenesis; however, the predictive value of the antibody titer and its role in prediction of this complication are controversial. The aim of this study was to determine the predictive value of maternal anti-SS-A antibodies on the development of fetal CHB.

METHODS

A retrospective chart review was performed for 189 cases of positive anti-SS-A antibodies determined by the double immunodiffusion (DID) method, and included 17 patients that developed fetal CHB. The relationship between the appearance of CHB and the anti-SS-A antibodies titer was examined.

RESULTS

An anti-SS-A antibodies titer of 1:32 or higher was identified by analyzing the receiver-operating characteristics (area under curve 0.72) curve. An anti-SS-A antibodies titer of 32 or more times greater than the upper limit by DID was a risk factor for fetal CHB (odds ratio 27.77, 95% confidence interval (CI) 1.91-21.02, P < 0.05) in the multivariate analysis. Among 107 cases of anti-SS-A antibodies titers of 1:32 or higher, 65 patients (60.7%) were treated with oral steroids. Of these, four patients had CHB (6.2%). This rate of CHB was significantly lower (P < 0.01) than the rate in patients not treated with steroids.

CONCLUSION

An anti-SS-A antibodies titer of 1:32 or higher in the maternal sera by DID was an independent risk factor for fetal CHB. In these patients, either antenatally administered prednisolone or betamethasone, was associated with a lower risk of fetal CHB.

A population-based investigation of the autoantibody profile in mothers of children with atrioventricular block

The objective of the study was to investigate the antigen specificity and occurrence of individual autoantibodies in mothers of children diagnosed with atrioventricular (AV) block in a nation-wide setting. Patients with AV block detected before 15 years of age were identified using national quality registries as well as a network of pediatric and adult cardiologists and rheumatologists at the six university hospitals in Sweden. Patients with gross heart malformations, surgically or infectiously induced blocks were excluded. Blood samples were obtained from the mothers and maternal autoantibody profile, including the occurrence of antibodies against Ro52, Ro60, La, SmB, SmD, RNP-70k, RNP-A, RNP-C, CENP-C, Scl-70, Jo-1, ribosomal RNP and histones was investigated in 193 mothers of children with AV block by immunoblotting and ELISA. Autoantibody reactivity was detected in 48% (93/193) of the mothers of children with AV block. In autoantibody-positive mothers, the vast majority, 95% (88/93), had antibodies against Ro52, while 63% (59/93) had autoantibodies to Ro60 and 58% (54/93) had autoantibodies to La. In addition, 13% (12/93) of the autoantibody-positive mothers had antibodies to other investigated antigens besides Ro52, Ro60 and La, and of these anti-histone antibodies were most commonly represented, detected in 8% (7/93) of the mothers. In conclusion, this Swedish population-based study confirms that maternal autoantibodies may associate with heart block in the child. Further, our data demonstrate a dominant role of Ro52 antibodies in association with AV block.