Faculty Bibliography

OBJECTIVE: Systemic lupus erythematosus (SLE) is associated with the premature development of cardiovascular disease. The platelet-endothelium interaction is important in the pathogenesis of cardiovascular disease. In this study, we investigated the platelet phenotype from patients with SLE and matched controls, and their effect on endothelial cells. APPROACH AND RESULTS: Platelet aggregability was measured in 54 SLE subjects off antiplatelet therapy (mean age 40.1+/-12.8 years; 82% female; 37% white) with age- and sex-matched controls. Platelets were coincubated with human umbilical vein endothelial cells (HUVECs) and changes to gene expression assessed by an RNA array and quantitative reverse transcription polymerase chain reaction. SLE disease activity index ranged from 0 to 22 (mean 5.1+/-3.9). Compared with controls, patients with SLE had significantly increased monocyte and leukocyte-platelet aggregation and platelet aggregation in response to submaximal agonist stimulation. An agnostic microarray of HUVECs cocultured with SLE platelets found a platelet-mediated effect on endothelial gene pathways involved in cell activation. Sera from SLE versus control subjects significantly increased (1) activation of control platelets; (2) platelet adhesion to HUVECs; (3) platelet-induced HUVEC gene expression of interleukin-8, and ICAM-1; and (4) proinflammatory gene expression in HUVECs, mediated by interleukin-1beta-dependent pathway. Incubation of SLE-activated platelets with an interleukin-1beta-neutralizing antibody or HUVECs pretreated with interleukin-1 receptor antibodies attenuated the platelet-mediated activation of endothelial cells. CONCLUSIONS: Platelet activity measurements and subsequent interleukin-1beta-dependent activation of the endothelium are increased in subjects with SLE. Platelet-endothelial interactions may play a role in the pathogenesis of cardiovascular disease in patients with SLE.

The detection of cardiac conduction defects in an 18-24 week old foetus in the absence of structural abnormalities predicts with near certainty the presence of autoantibodies against 60kD and 52kD SSA/Ro in the mother regardless of her health status. Previous studies have emphasized these autoantibodies as key mediators of tissue injury. The aim of this study was to focus on the anti-Ro52 response to determine whether these autoantibodies originate from progenitors that are inherently self-reactive or from B-cells that acquire self-reactivity during an immune response. We traced the evolution of two anti-Ro52 autoantibodies isolated from circulating IgG1-switched B-cells from an asymptomatic mother of a child with third degree congenital heart block. The autoantibodies were expressed as their immune form and as pre-immune ancestors by reverting somatic mutations to germline sequence. The reactivity of pre-immune and immune antibodies for Ro52, Ro60, La and DNA was measured. Both anti-Ro52 autoantibodies exhibited a low frequency of somatic mutations (3-4%) and utilised the same heavy and light chain genes but represented distinct clones based on differing complementarity determining region sequences. Pre- and post-immune antibodies showed specific binding to Ro52 with no measurable reactivity for other autoantigens. Ro52 binding was higher for immune antibodies compared to pre-immune counterparts demonstrating that autoreactivity was enhanced by affinity maturation. These data indicate that Ro52 reactivity is an intrinsic property of the germline antibody repertoire in a mother with a pathogenic antibody defined by cardiac injury in her offspring, and implies defects in both central and peripheral tolerance mechanisms.

Background Several studies have evaluated mortality and shortterm morbidity in neonatal lupus (NL), however there is minimaldata on long term outcomes in children exposed to maternalanti-Ro antibodies in utero. A previous pilot study utilising theResearch Registry for Neonatal Lupus (RRNL) raised concernregarding the development of autoimmune disease in childhood, however the numbers evaluated were small and the patientsstudied were young. This study was initiated to ascertain the current prevalence of autoimmune disease in NL children and theirunaffected siblings, and to evaluate whether fetal or maternal factors associated with the development of future autoimmunity.Materials and methods A retrospective cohort of family membersfrom the RRNL were contacted to evaluate for autoimmune disease. Follow-up questionnaires were completed which included35 items describing symptoms and diagnoses associated withautoimmunity in 138 cardiac NL children, 74 cutaneous NL children, and 134 unaffected siblings. Medical records were obtainedand evaluated from the patient's physicians to confirm diagnoses.Maternal diagnosis of systemic lupus and/or Sjogren's syndromeand fetal cardiac disease severity based on a previously describedseverity score were associated with postnatal autoimmune diseases using chi square and Mann-Whitney analyses.Results Seventeen (8.0%) of NL affected children developed anautoimmune disease at the time of follow up (mean age 11.6+/-9.0 years). These included 3 patients with SLE, 1 with JIA, 3with thyroid disease, 5 with psoriasis, 1 with IBD, 1 with uveitis,1 with UAS and 2 with type 1 DM. Six (4.5%) unaffected siblingsdeveloped an autoimmune disease (mean age 10.6+/-7.1 years),which included 1 with JIA, 1 with Sarcoidosis/ITP, 1 with Myasthenia Gravis/Celiac disease, 1 with psoriasis, 1 with UAS and1 with type 1 DM,. There was a significant association ofbetween having an autoimmune disease and having advancedheart block (11.0% vs. 4.2%, p = 0.03) and a trend towards anassociation with cardiac NL disease severity score (4.43+/-4.89 vs.2.58+/-4.24, p = 0.06). Mother's diagnosis of SLE or Sjogren'sdid not associate with the children's development of autoimmunedisease (p = 0.828).Conclusions Fetuses that develop advanced congenital heartblock as a manifestation of NL may be at greater risk for developing autoimmune diseases later in life. This could potentially relateto a genetic component that makes a Ro exposed fetus both moreprone to inflammatory effects of passive immunity and predisposes to future autoimmunity, independent of the mother's rheumatic disease status