A survey of ficolin-3 activity in Systemic Lupus Erythematosus reveals a link to hematological disease manifestations and autoantibody profile.

The complement system plays a central role in the pathogenesis of Systemic Lupus Erythematosus (SLE), but most studies have focused on the classical pathway. Ficolin-3 is the main initiator of the lectin pathway of complement in humans, but its role in systemic autoimmune disease has not been conclusively determined. Here, we combined biochemical and genetic approaches to assess the contribution of ficolin-3 to SLE risk and disease manifestations. Ficolin-3 activity was measured by a functional assay in serum or plasma samples from Swedish SLE patients (n = 786) and controls matched for age and sex (n = 566). Genetic variants in an extended 300 kb genomic region spanning the FCN3 locus were analyzed for their association with ficolin-3 activity and SLE manifestations in a Swedish multicenter cohort (n = 985). Patients with ficolin-3 activity in the highest tertile showed a strong enrichment in an SLE cluster defined by anti-Sm/DNA/nucleosome antibodies (OR 3.0, p < 0.001) and had increased rates of hematological disease (OR 1.4, p = 0.078) and lymphopenia (OR = 1.6, p = 0.039). Genetic variants associated with low ficolin-3 activity mapped to an extended haplotype in high linkage disequilibrium upstream of the FCN3 gene. Patients carrying the lead genetic variant associated with low ficolin-3 activity had a lower frequency of hematological disease (OR 0.67, p = 0.018) and lymphopenia (OR 0.63, p = 0.031) and fewer autoantibodies (p = 0.0019). Loss-of-function variants in the FCN3 gene were not associated with SLE, but four (0.5 %) SLE patients developed acquired ficolin-3 deficiency where ficolin-3 activity in serum was depleted following diagnosis of SLE. Taken together, our results provide genetic and biochemical evidence that implicate the lectin pathway in hematological SLE manifestations. We also identify lectin pathway activation through ficolin-3 as a factor that contributes to the autoantibody response in SLE.

Plasma interferon-alpha protein levels during pregnancy are associated with lower birth weight in systemic lupus erythematosus.

OBJECTIVES: Adverse pregnancy outcomes are more common in women with systemic lupus erythematosus (SLE) compared with healthy women, but we lack prognostic biomarkers. Plasma interferon alpha (IFNα) protein levels are elevated in a subgroup of pregnant women with SLE, but whether this is associated with pregnancy outcomes is unknown. We investigated the relationship between IFNα, adverse pregnancy outcomes and the presence of autoantibodies in SLE pregnancy. METHODS: We followed 76 women with SLE prospectively. Protein levels of IFNα were quantified in plasma collected in the 2nd and 3rd trimester with single-molecule array. Positivity for antinuclear and antiphospholipid antibodies was assessed during late pregnancy with multiplexed bead assay. Clinical outcomes included the adverse pregnancy outcomes small for gestational age (SGA), preterm birth, and preeclampsia. RESULTS: During SLE pregnancy, women with SGA infants compared with those without had higher levels of plasma IFNα protein, and IFNα positivity was associated with lower birth weight of the infant. Preterm birth was associated with autoantibodies against chromatin. IFNα protein levels associated positively with autoantibodies against chromatin, Smith/ribonucleoprotein (SmRNP) and RNP, but negatively with phospholipid antibodies. CONCLUSION: Elevated IFNα protein in plasma of women with SLE is a potential risk factor for lower birth weight of their infants. The association between IFNα and lower birth weight warrants further investigation regarding the pathophysiological role of IFNα during SLE pregnancy.

Patient global assessment and inflammatory markers in patients with idiopathic inflammatory myopathies - A longitudinal study.

AIM: To explore if patient global assessment (PGA) is associated with inflammation over time and if associations are explained by other measures of disease activity and function in patients with idiopathic inflammatory myopathies (IIM). METHODS: PGA and systemic inflammatory markers prospectively collected over five years were retrieved from the International MyoNet registry for 1200 patients with IIM. Associations between PGA, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and creatine kinase (CK) were analyzed using mixed models. Mediation analysis was used to test if the association between PGA and inflammatory markers during the first year of observation could be explained by measures of disease activity and function. RESULTS: PGA improved, and inflammatory markers decreased during the first year of observation. In the mixed models, high levels of inflammatory markers were associated with worse PGA in both men and women across time points during five years of observation. In men, but not in women, the association between elevated ESR, CRP and poorer PGA was explained by measures of function and disease activity. With a few exceptions, the association between improved PGA and reduced inflammatory markers was partially mediated by improvements in all measures of function and disease activity. CONCLUSION: Increased levels of systemic inflammation are associated with poorer PGA in patients with IIM. In addition to known benefits of lowered inflammation, these findings emphasize the need to reduce systemic inflammation to improve subjective health in patients with IIM. Furthermore, the results demonstrate the importance of incorporating PGA as an outcome measure in clinical practice and clinical trials.

Low CD4 + T cell count is related to specific anti-nuclear antibodies, IFNα protein positivity and disease activity in systemic lupus erythematosus pregnancy.

BACKGROUND: Lymphopenia, autoantibodies and activation of the type I interferon (IFN) system are common features in systemic lupus erythematosus (SLE). We speculate whether lymphocyte subset counts are affected by pregnancy and if they relate to autoantibody profiles and/or IFNα protein in SLE pregnancy. METHODS: Repeated blood samples were collected during pregnancy from 80 women with SLE and 51 healthy controls (HC). Late postpartum samples were obtained from 19 of the women with SLE. Counts of CD4 + and CD8 + T cells, B cells and NK cells were measured by flow cytometry. Positivity for anti-nuclear antibodies (ANA) fine specificities (double-stranded DNA [dsDNA], Smith [Sm], ribonucleoprotein [RNP], chromatin, Sjögren's syndrome antigen A [SSA] and B [SSB]) and anti-phospholipid antibodies (cardiolipin [CL] and ß2 glycoprotein I [ß2GPI]) was assessed with multiplexed bead assay. IFNα protein concentration was quantified with Single molecule array (Simoa) immune assay. Clinical data were retrieved from medical records. RESULTS: Women with SLE had lower counts of all lymphocyte subsets compared to HC throughout pregnancy, but counts did not differ during pregnancy compared to postpartum. Principal component analysis revealed that low lymphocyte subset counts differentially related to autoantibody profiles, cluster one (anti-dsDNA/anti-Sm/anti-RNP/anti-Sm/RNP/anti-chromatin), cluster two (anti-SSA/anti-SSB) and cluster three (anti-CL/anti-ß2GPI), IFNα protein levels and disease activity. CD4 + T cell counts were lower in women positive to all ANA fine specificities in cluster one compared to those who were negative, and B cell numbers were lower in women positive for anti-dsDNA and anti-Sm compared to negative women. Moreover, CD4 + T cell and B cell counts were lower in women with moderate/high compared to no/low disease activity, and CD4 + T cell count was lower in IFNα protein positive relative to negative women. Finally, CD4 + T cell count was unrelated to treatment. CONCLUSION: Lymphocyte subset counts are lower in SLE compared to healthy pregnancies, which seems to be a feature of the disease per se and not affected by pregnancy. Our results also indicate that low lymphocyte subset counts relate differentially to autoantibody profiles, IFNα protein levels and disease activity, which could be due to divergent disease pathways.