Faculty Bibliography

Based on the consistent demonstration of fibrosis of the atrioventricular node surrounded by macrophages and multinucleated giant cells in anti-Ro antibody exposed fetuses dying with heart block, this study focuses on macrophage signaling stimulated by ssRNA associated with the Ro60 protein and the impact of antagonizing innate cell drivers such as TLR7/8. Transcriptome and epigenetic modifications which affect transcription factors, NF-kappaB and STAT1, were selected to evaluate the phenotype of macrophages in which TLR7/8 was ligated following treatment with either anti-Ro60/Ro60/hY3 RNA immune complexes or transfection with hY3. Based on microarray, TNF and IL6 were among the most highly upregulated genes in both stimulated conditions, each of which was significantly inhibited by preincubation with hydroxychloroquine (HCQ). In contrast, following stimulation of macrophages with either TNF-alpha or IFN-alpha, which do not signal through TLR, the resultant gene expression was refractory to HCQ. Ligation of TLR7/8 resulted in increased histone methylation as measured by increased H3K4me2, a requirement for binding of NF-kappaB at certain promoters, specifically the kB1 region in the TNF promoter (ChIP-qPCR), which was significantly decreased by HCQ. In summary, these results support that the HCQ-sensitive phenotype of hY3 stimulated macrophages reflects the bifurcation of TLR downstream signals involving NF-kappaB and STAT 1 pathways and for the former dimethylation of H3K4. Accordingly, HCQ may act more as a preventive measure in downregulating the initial production of IFN-alpha or TNF-alpha and not affect the resultant autocoid stimulation reflected in TNF-alpha and IFN-alpha responsive genes. The beneficial scope of antimalarials in the prevention of organ damage, inclusive of heart block in an anti-Ro offspring or more broadly SLE, may include in part, a mechanism targeting TLR-dependent epigenetic modification.

OBJECTIVES: To evaluate the efficacy and safety of tabalumab, a human IgG4 monoclonal antibody that neutralises membrane and soluble B-cell activating factor (BAFF). METHODS: This randomised, placebo-controlled study enrolled 1124 patients with moderate-to-severe systemic lupus erythematosus (SLE) (Safety of Estrogens in Lupus Erythematosus National Assessment- SLE Disease Activity Index >/=6 at baseline). Patients received standard of care plus subcutaneous study drug, starting with a loading dose (240 mg) at week 0 and followed by 120 mg every 2 weeks (120 Q2W), 120 mg every 4 weeks (120 Q4W) or placebo. Primary endpoint was proportion achieving SLE Responder Index 5 (SRI-5) improvement at week 52. RESULTS: Clinical characteristics were balanced across groups. The primary endpoint was met with 120 Q2W (38.4% vs 27.7%, placebo; p=0.002), but not with the less frequent 120 Q4W regimen (34.8%, p=0.051). Although key secondary endpoints (time to severe flare, corticosteroid sparing and fatigue) were not met, patients treated with tabalumab had greater SRI-5 response rates in a serologically active subset and improvements in more stringent SRI cut-offs, SELENA-SLEDAI, Physician's Global Assessment, anti-double-stranded DNA antibodies, complement, total B cells and immunoglobulins. The incidences of deaths, serious adverse events (AEs), and treatment-emergent AEs were similar in the 120 Q2W, 120 Q4W and placebo groups, but depression and suicidal ideation, albeit rare events, were more commonly reported with tabalumab. CONCLUSION: SRI-5 was met with 120 Q2W and although key secondary endpoints were not met, numerous other secondary endpoints significantly improved in addition to pharmacodynamic evidence of BAFF pathway blockade. The safety profile for tabalumab was similar to placebo, except for depression and suicidality, which were uncommon. TRIAL REGISTRATION NUMBER: NCT01205438.