Neonatal lupus syndrome: the heart as a target of the immune system

Neonatal lupus erythematosus manifested as a complete heart block: A case report

Key Clinical Message

Fetal bradycardia and congenital complete heart block could be the presentation of neonatal lupus. A high index of suspicion of this condition helps to identify an asymptomatic mother.

Abstract

Neonatal lupus erythematosus (NLE) is a rare acquired autoimmune disease of newborns due to placental transfer of Ro/SSA or La/SSB autoantibodies. Though cardiac, cutaneous, hematological, and hepatobiliary abnormalities are detected, cardiac defects cause significant morbidity and mortality. We report a case of complete congenital heart block due to NLE.

Current Insights in Cutaneous Lupus Erythematosus Immunopathogenesis

Cutaneous Lupus Erythematosus (CLE) is a clinically diverse group of autoimmune skin diseases with shared histological features of interface dermatitis and autoantibodies deposited at the dermal-epidermal junction. Various genetic and environmental triggers of CLE promote infiltration of T cells, B cells, neutrophils, antigen presenting cells, and NK cells into lesional skin. In this mini-review, we will discuss the clinical features of CLE, insights into CLE immunopathogenesis, and novel treatment approaches.

Neonatal lupus erythematosus

Neonatal lupus erythematosus (NLE) refers to a clinical spectrum of cutaneous, cardiac, and systemic abnormalities observed in newborn infants whose mothers have autoantibodies against Ro/SSA and La/SSB. The condition is rare and usually benign and self-limited but sometimes may be associated with serious sequelae. We review the pathophysiology, clinical features, and management of infants with this condition. Neonates with NLE should be managed at a tertiary care center. Multidisciplinary team involvement may also be indicated. In mothers with anti-Ro/SSA and/or anti-La/SSB antibodies and infants with congenital heart block, the risk of recurrence in subsequent offspring is 17–25%. Therefore, careful monitoring of subsequent pregnancies with serial ultrasonography and echocardiography is essential.

Neonatal lupus erythematosus: clinical character, investigation, and outcome

Neonatal lupus erythematosus is an uncommon maternal auto-antibody-associated disease characterized by cutaneous, cardiac, hepatic, hematological, neurological, and pulmonary involvement. A retrospective study was performed to review clinical manifestations, investigation results, outcomes of neonatal lupus erythematosus patients and their mothers at the Department of Pediatrics, Siriraj Hospital during 1993 to 2008. Seventeen neonatal lupus erythematosus patients (10 girls and seven boys) were identified. Cutaneous, cardiac, hepatobiliary, and hematological involvement was found in 70.6%, 64.7%, 52.9%, and 35.3% of infants, respectively. Skin lesions were erythematous patches (91.7%), subacute cutaneous lupus erythematosus (50%), petechiae (41.7%), persistent cutis marmorata (16.7%), and discoid lesions (8.3%). Congenital heart block was found in nine cases, and structural abnormalities were found in nine cases. All sera of patients were positive for antinuclear antibodies. Patients (87.5%) showed positive antiRo/SSA, and 50% had positive antiLa/SSB antibodies. Most neonatal lupus erythematosus mothers (64.7%) were asymptomatic. Five mothers were diagnosed with systemic lupus erythematosus, and one mother was diagnosed with mixed connective tissue disease. All maternal sera was positive for antinuclear antibodies and antiRo/SSA antibody. Seven patients required pacemaker implantation. The mortality rate was 11.8%, caused by congestive heart failure and pneumonia. Antinuclear antibody tests should be used as one of the screening tests in mothers or patients suspected of having neonatal lupus erythematosus.

Sera from patients with idiopathic dilated cardiomyopathy decrease ICa in cardiomyocytes isolated from rabbits

Autoantibodies against muscarinic and adrenergic receptors have been found in the sera of patients with idiopathic dilated cardiomyopathy (IDC) and Chagas disease, but it is still unclear whether they can functionally interact with their respective receptors to modulate cardiac functions. In this study, our goal was to detect the presence of those antibodies in the sera of patients with IDC and characterize their electrophysiological effects on cardiomyocytes from rabbits. By using ELISA immunoassays, we detected high titers of antibodies against muscarinic M2 receptors in the sera of all IDC patients, whereas the detection of antibodies against the beta1-receptor occurred in 50% of them. Electrophysiological experiments using the whole cell configuration of the patch-clamp technique showed that sera from 43% of IDC patients induced a significant decrease (approximately 26%) in isoproterenol-stimulated L-type Ca2+ currents in rabbit ventricular myocytes, whereas the sera from healthy blood donors failed to do so. As expected, IDC sera also decreased the action potential duration (by 10.5%) due to a shortening of the plateau phase. Sera that reduced isoproterenol-stimulated L-type Ca2+ currents did not cause any effect on K+ currents. We conclude that sera from IDC patients have autoantibodies, which interact with muscarinic M2 receptors of rabbit cardiomyocytes, acting in an agonist-like fashion. This action results in changes in electrogenesis, which, as often observed in patients with IDC, could initiate ventricular arrhythmias that lead to sudden death.

Anti-La/SSB antibodies transported across the placenta bind apoptotic cells in fetal organs targeted in neonatal lupus

OBJECTIVE

To determine whether La and/or Ro epitopes on apoptotic cells in fetal organs that are targeted in neonatal lupus syndrome (NLS) are accessible for binding by autoantibodies in vivo, we traced the fate of transplacental autoantibodies in a murine passive transfer model.

METHODS

Pregnant mice at day 15 of gestation (E15) were injected intraperitoneally with human anti-Ro/La-positive sera or control sera, and transplacental transfer of human autoantibodies was tested by enzyme-linked immunosorbent assay with recombinant antigens. Multiple cryostat sections at the level of the heart of E17 fetuses were visualized simultaneously for human IgG binding and apoptosis (TUNEL) under confocal microscopy. Serial paraffin sections of E17 and E19 fetuses were examined for histologic evidence of inflammation.

RESULTS

Human IgG anti-52-kd Ro, anti-60-kd Ro, and anti-La autoantibodies were transported efficiently into the fetal circulation. Human IgG-apoptotic cell complexes were detected in the heart (atrial trabeculae and atrioventricular node), skin, liver, and newly forming bone of fetuses from mothers injected with anti-Ro/La sera but not control sera. The IgG binding was fetal-specific and organ-specific; transplacental autoantibodies did not bind to apoptotic cells in the fetal thymus, lung, brain, or gut. The complexes were not associated with an inflammatory reaction. Injection of mothers with affinity-purified anti-La autoantibodies (but not anti-Ro/La Ig depleted of anti-La) revealed an identical location of IgG binding to apoptotic cells in the fetuses.

CONCLUSION

This is the first study to demonstrate that transplacental anti-La autoantibodies bind specifically to apoptotic cells in selected fetal organs in vivo, similar to the organ involvement in NLS. We hypothesize that additional factors are required to promote proinflammatory clearance of IgG-apoptotic cell complexes and subsequent tissue damage.

Antinuclear antibody testing

The ANA test is an excellent screening test for patients with SLE and a few other connective tissue diseases. The LE cell preparation is an assay that is subjective and costly. Because of the presence of a superior screening test (the ANA) and superior specific auto-antibody tests, the author recommends that the use of LE cell preparations be discontinued. ANA screening tests may be performed either by indirect microscopic serology (usually IFA) or EIA. The latter technique is readily automated and many new products for this screening test have appeared in the past decade. The products differ, however, and laboratories are cautioned to test each in the context of the clinical needs of their clinicians. Proper use of the ANA test requires each laboratory to determine the cutoff used under their conditions of assay. Although either ANA screening test has a high negative predictive value in numerous studies, proper selection of patients to be tested is key to improving the predictive value of a positive result. The American College of Rheumatism criteria are reviewed and recommended as part of the patient selection process for this testing.