Clinical and serological associations of autoantibodies in patients with systemic lupus erythematosus

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 β2 glycoprotein I [β2GPI]) 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-β2GPI), 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.

Serological and clinical associations of autoantibodies in Chinese patients with new-onset systemic lupus erythematosus

To study the clinical significance of autoantibodies in Chinese patients with new-onset systemic lupus erythematosus (SLE), we enrolled 526 new-onset patients who met the 1997 Updated American College of Rheumatology SLE Classification Criteria for a retrospective cohort study. Chi-square test and Wilcoxon rank-sum test were used to detect the relationship of autoantibodies with clinical manifestations and serological results respectively. Our results demonstrated that the positive rate of anti-ribosomal P protein (anti-P) antibody in female patients was higher than that in male patients (41.2% vs. 22%, P = 0.008). Patients with anti-SSB (43.95 ± 73.12 vs. 40.92 ± 75.75, P = 0.004; 63.93 ± 103.56 vs. 55.06 ± 120.84, P = 0.008 respectively) antibodies had higher levels of alanine aminotransferase (ALT) and aspartate transaminase (AST), whereas those with anti-P antibody (28.90 ± 25.70 vs. 50.08 ± 93.00, P = 0.014; 38.51 ± 48.19 vs. 69.95 ± 142.67, P = 0.047, respectively) had lower levels of them. Anti-dsDNA antibody (P = 0.021) was associated with pulmonary arterial hypertension (PAH). The patients with anti-Ro60 (P = 0.044), anti-P (P = 0.012) and anti-dsDNA (P = 0.013) antibodies were less likely to develop Interstitial lung disease. Anti-SmRNP antibody was correlated to lower prevalence of neuropsychiatric symptoms (P = 0.037), and patients with anti-centromere antibody (ACA) were more likely to develop serositis (P = 0.016).We identified five clusters of SLE-related autoantibodies, confirmed previously reported associations of autoantibodies, and discovered new associations.

Anti-dsDNA B-Cell ELISpot as a Monitoring and Flare Prediction Tool in SLE Patients

Anti-dsDNA autoantibodies quantification and complement levels are widely used to monitor disease activity in systemic lupus erythematosus (SLE). However, better biomarkers are still needed. We hypothesised whether the dsDNA antibody-secreting B-cells could be a complementary biomarker in disease activity and prognosis of SLE patients. Fifty-two SLE patients were enrolled and followed for up to 12 months. Additionally, 39 controls were included. An activity cut-off (comparing active and non-active patients according to clinical SLEDAI-2K) was established for SLE-ELISpot, chemiluminescence and Crithidia luciliae indirect immunofluorescence tests (≥11.24, ≥374.1 and ≥1, respectively). Assays performances together with complement status were compared regarding major organ involvement at the inclusion and flare-up risk prediction after follow-up. SLE-ELISpot showed the best performance in identifying active patients. High SLE-ELISpot results were associated with haematological involvement and, after follow-up, with an increased hazard ratio for disease flare-up (3.4) and especially renal flare (6.5). Additionally, the combination of hypocomplementemia and high SLE-ELISpot results increased those risks up to 5.2 and 32.9, respectively. SLE-ELISpot offers complementary information to anti-dsDNA autoantibodies to evaluate the risk of a flare-up in the following year. In some cases, adding SLE-ELISpot to the current follow-up protocol for SLE patients can improve clinicians' personalised care decisions.

Lupus band test can be used in combination with anti-chromatin antibodies and complement analysis to predict transition from cutaneous to systemic lupus

The lupus band test (LBT) is frequently performed for patients with lupus erythematosus (LE) but its capacity to discriminate cutaneous (C)LE from systemic (S)LE is debated, as well as its association with serum antinuclear antibodies (ANA) and complement reduction. Among 158 patients, 56 received retrospectively a diagnosis of CLE, 37 have SLE and 65 other skin disorders. Considering 29 clinical, histopathologic, LBT, and serological parameters: 5 parameters were effective in distinguishing LE from other skin disorders (e.g. skin photosensitivity, LBT positivity, basal vacuolar changes, thickening of the basement membrane, and anti-SSA-60 kDa); and 8 parameters were able to separate SLE from CLE (e.g. arthritis, lupus nephritis, hematological manifestations, Raynaud/sicca manifestations, anti-chromatin, anti-dsDNA, and low levels of C3/4). A positive LBT was further determined to be associated with systemic manifestations when associated with anti-chromatin response and complement reduction in the profile of patients evolving to a systemic form of lupus.