Purpose To examine the prevalence of isolated IgA anti-β2Glycoprotein I (anti-β2GPI) positivity and the association of these antibodies, and a subgroup that bind specifically to domain IV/V of β2GPI, with clinical manifestations of the Antiphospholipid Syndrome (APS) in three patients groups. The pathogenicity of IgA anti-β2GPI was also evaluated in a mouse model of thrombosis. Methods Patients with systemic lupus erythematosus (SLE) from a multiethnic, multicenter cohort (LUpus in MInorities, NAture versus nurture [LUMINA]) (n=558), patients with SLE from the Hopkins Lupus Cohort (n=215), and serum samples referred to the Antiphospholipid Standardization Laboratory (APLS) (n=5,098) were evaluated. IgA anti-β2GPI titers and binding to domain IV/V of β2GPI were examined by enzyme-linked immunosorbent assay (ELISA). CD1 mice were inoculated with purified IgA anti- β2GPI antibodies, and surgical procedures and ELISAs were performed to evaluate thrombus development and tissue factor (TF) activity. Results A total of 198 patients were found to be positive for IgA anti-β2GPI isotype, and 57 patients were positive exclusively for IgA anti-β2GPI antibodies. Of these, 13 of 23 patients (56.5%) in the LUMINA cohort, 17 of 17 patients (100%) in the Hopkins cohort, and 10 of 17 patients (58.9%) referred to APLS had at least one APS-related clinical manifestation. Fifty-four percent of all the IgA anti-β2GPI positive serum samples reacted with domain IV/V of anti-β2GPI, and 77% of those had clinical features of APS. Isolated IgA anti-β2GPI positivity was associated with an increased risk for arterial thrombosis (p<0.001), venous thrombosis (p=0.015) and all thrombosis (p<0.001). The association between isolated IgA anti-β2GPI and arterial thrombosis (p=0.0003) and all thrombosis (p=0.0003) remained significant after adjusting for other risk factors for thrombosis. In vivo mouse studies demonstrated that IgA anti-β2GPI antibodies induced significantly larger thrombi and higher TF levels compared to controls. Conclusion Isolated IgA anti-β2GPI positive titers may identify additional patients with clinical features of APS. Testing for these antibodies when other antiphospholipid (aPL) tests are negative and APS is suspected is recommended. IgA anti-β2GPI antibodies directed to domain IV/V of β2GPI represent an important subgroup of clinically relevant antiphospholipids.

Fluvastatin has been shown to revert proinflammatory/prothrombotic effects of antiphospholipid antibodies (aPL) in vitro and in mice. Here, we examined whether fluvastatin affects the levels of proinflammatory/prothrombotic markers in antiphospholipid syndrome (APS) patients. Vascular endothelial growth factor (VEGF), soluble tissue factor (sTF), tumor necrosis factor-alpha (TNF-alpha), soluble intercellular adhesion molecule-1 (sICAM-1), sE-selectin (E-sel), C-reactive protein (CRP), and soluble vascular cell adhesion molecule (sVCAM-1), were measured in the sera of 93 APS patients and 60 controls and in the sera of nine patients with APS before and after 30 days of treatment with fluvastatin. Elevated levels of VEGF, sTF, and TNF-alpha were found in APS patients. Fluvastatin significantly reduced those markers in the majority of treated subjects. The data from this study show that statins may be beneficial in aPL-positive patients and warrant larger clinical trials to confirm the efficacy of the drug for the treatment of APS clinical manifestations.

Background The abnormal biological activity of cytokines plays an important role in the pathophysiology of both systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). Several studies have highlighted the association of vitamin D and certain pro-inflammatory cytokines with disease activity in SLE. However, there are limited data on the association of vitamin D and antiphospholipid antibodies (aPL) with various proinflammatory biomarkers in these patients and their relative impact on clinical outcomes. Methods The serum levels of several aPL, 25-hydroxy vitamin D, pro-inflammatory cytokines including IFNα, IL-1β, IL-6, IL-8, IP10, sCD40L, TNFα and VEGF were measured in 312 SLE patients from the Jamaican (n-=45) and Hopkins (n=267) Lupus cohorts using commercial Milliplex and ELISA assays. Oxidized LDL/β2glycoprotein antigenic complexes (oxLβ2Ag) and their associated antibodies were also measured in the Jamaican cohort. Healthy controls for oxidative marker and cytokine testing were utilized. Results Abnormally low vitamin D levels were present in 61.4% and 73.3% of Hopkins and Jamaican SLE patients respectively. Median concentrations of IP10, TNFα, sCD40L and VEGF were elevated in both cohorts, oxLβ2Ag and IL-6 were elevated in the Jamaican cohort and IFNα, IL-1β and IL-8 were the same or lower in both cohorts compared to controls. IP10 and VEGF were independent predictors of disease activity, aPL, IP10 and IL-6 were independent predictors of thrombosis and IL-8 and low vitamin D were independent predictors of pregnancy morbidity despite there being no association of vitamin D with pro-inflammatory cytokines. Conclusions Our results indicate that aPL-mediated pro-inflammatory cytokine production is likely a major mechanism of thrombus development in SLE patients. We provide presumptive evidence of the role IL-8 and hypovitaminosis D play in obstetric pathology in SLE but further studies are required to characterize the subtle complexities of vitamin D’s relationship with cytokine production and disease activity in these patients.

Increasing titers of APhL, anti-PS, and anti-PI antibodies could indicate an increased risk of thrombotic and/or obstetric aPL-related manifestations. These assays may be promising biomarkers for particular APS manifestations.