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Few diseases exemplify the integration of research from bench to bedside as well as neonatal lupus, often referred to as a model of passively acquired autoimmunity. In essence, this disease encompasses two patients, both the mother and her child. The signature histologic lesion of autoimmune-associated congenital heart block is fibrosis of the conducting tissue, and in some cases the surrounding myocardium. It is astounding how rapid and, in most cases, irreversible is the fibrotic response to injury. The mechanism by which maternal anti-SSA/Ro-SSB/La antibodies initiate and perpetuate inflammation, and eventuate in scarring of the atrioventricular node, is not yet defined. In vitro and in vivo studies suggest that one pathologic cascade leading to scarring may be initiated via apoptosis, resulting in translocation of SSA/Ro-SSB/La antigens and subsequent surface binding by maternal autoantibodies. These opsonized cardiocytes are phagocytosed by macrophages, which secrete factors that transdifferentiate fibroblasts into myofibroblasts, a scarring phenotype. Dissecting the individual components in this fibrotic pathway should provide insights into the rarity of irreversible injury and should form the basis of rational approaches to prevention and treatment

The classic old definition of congenital heart block by Yater (1929) is still generally accepted: 'Heart block established in a young patient. There must be some evidence of the existence of the slow pulse at a fairly early age and absence of a history of any infection which might cause the condition after birth: notably diphtheria, rheumatic fever, chorea and congenital syphilis'. However, other definitions are used. We systematically reviewed 1825 cases from 38 separate studies. We conclude that complete AV blocks detected in utero in the absence of structural abnormalities differ from blocks detected later in life with respect to pathogenesis (they are generally associated with maternal anti-Ro/SSA antibodies), poorer childhood prognosis, increased risk of developing late-onset dilated cardiomyopathy, different maternal clinical features and increased risk of recurrence in future pregnancies. For these reasons we propose a new modern definition of congenital complete AV block which might be acceptable to cardiologists, rheumatologists, pediatricians and obstetricians: 'an AV block is defined as congenital if it is diagnosed in utero, at birth or within the neonatal period (0-27 days after birth)'.

OBJECTIVE: To determine in a longitudinal cohort study whether children with varied manifestations of neonatal lupus or their unaffected siblings later develop autoantibodies and/or rheumatic diseases. METHODS: To obtain information on the health of children ages >or=8 years who had manifestations of neonatal lupus (affected group) and their unaffected siblings (unaffected group), questionnaires were sent to mothers (with anti-SSA/Ro and/or anti-SSB/La antibodies) who were enrolled in the National Institute of Arthritis and Musculoskeletal and Skin Diseases/Hospital for Joint Diseases Research Registry for Neonatal Lupus. Children of healthy mothers referred by the Registry enrollees comprised the control group. Further data were provided by review of medical records. RESULTS: Fifty-five mothers enrolled in the Registry returned questionnaires on 49 children with neonatal lupus and their 45 unaffected siblings. Six children with definite rheumatic/autoimmune diseases were identified: 2 with juvenile rheumatoid arthritis, 1 with Hashimoto thyroiditis, 1 with psoriasis and iritis, 1 with diabetes mellitus and psoriasis, and 1 with congenital hypothyroidism and nephrotic syndrome. All had neonatal lupus, and their mothers had manifestations of autoimmune diseases (Sjogren's syndrome in 4, systemic lupus erythematosus/Sjogren's syndrome in 1, and undifferentiated autoimmune disease in 1). Antinuclear antibodies were present in 4 of 55 sera tested (2 of 33 affected children and 2 of 22 unaffected children). No serum contained antibodies reactive with SSA/Ro or SSB/La antigens. CONCLUSION: These data suggest that children with neonatal lupus require continued followup, especially prior to adolescence and if the mother herself has an autoimmune disease. While there was no apparent increased risk of systemic lupus erythematosus, the development of some form of autoimmune disease (systemic or organ-specific) in early childhood may be of concern. During adolescence and young adulthood, individuals with neonatal lupus and their unaffected siblings do not appear to have an increased risk of developing systemic rheumatic diseases