Objectives To study whether clinical remission (CR) and Low Lupus Disease Activity State (LLDAS) are achievable goals in childhood-onset SLE. Methods Data on medication use and disease activity were prospectively collected. LLDAS was defined as Safety of Estrogen in Lupus Erythematosus National Assesment-SLE disease Activity Index (SELENA-SLEDAI) ≤4 with zero scores for renal, Central Nervous System (CNS), serositis, vasculitis and constitutional components, no increase in any SLEDAI component since the previous visit, PGA ≤1, and prednisone dose ≤7.5 mg/day. CR on treatment (Tx) was defined as a Physician Global Assessment 50% of time. 52.9% children achieved CR on Tx, and only 21.6% children achieved CR off Tx. Conclusions LLDAS is an attainable treat-to-target goal in contrast to CR on and off Tx. Even more, LLDAS can be reached with limited use of corticosteroids with early introduction of immunosuppressives.

To study the association of serum IFNα2 levels measured by ultrasensitive single-molecule array (Simoa) and the IFN-I gene signature (IGS) with disease activity and determine whether these assays can mark disease activity states in a longitudinal cohort of childhood-onset SLE (cSLE) patients. Serum IFNα2 levels were measured in 338 samples from 48 cSLE patients and 67 healthy controls using an IFNα Simoa assay. Five-gene IGS was measured by RT-PCR in paired whole blood samples. Disease activity was measured by clinical SELENA-SLEDAI and BILAG-2004. Low disease activity was defined by Low Lupus Disease Activity State (LLDAS) and flares were characterized by SELENA-SLEDAI flare index. Analysis was performed using linear mixed models. A clear positive correlation was present between serum IFNα2 levels and the IGS (r = 0.78, P < 0.0001). Serum IFNα2 levels and IGS showed the same significant negative trend in the first 3 years after diagnosis. In this timeframe, mean baseline serum IFNα2 levels decreased by 55.1% (Δ 201 fg/ml, P < 0.001) to a mean value of 164 fg/ml, which was below the calculated threshold of 219.4 fg/ml that discriminated between patients and healthy controls. In the linear mixed model, serum IFNα2 levels were significantly associated with both cSELENA-SLEDAI and BILAG-2004, while the IGS did not show this association. Both IFN-I assays were able to characterize LLDAS and disease flare in receiver operating characteristic analysis. Serum IFNα2 levels measured by Simoa technology are associated with disease activity scores and characterize disease activity states in cSLE.

Clinical phenotyping and predicting treatment responses in SLE patients is challenging. Extensive blood transcriptional profiling has identified various gene modules that are promising for stratification of SLE patients. We aimed to translate existing transcriptomic data into simpler gene signatures suitable for daily clinical practice. Real-time PCR of multiple genes from the IFN M1.2, IFN M5.12, neutrophil (NPh) and plasma cell (PLC) modules, followed by a principle component analysis, was used to identify indicator genes per gene signature. Gene signatures were measured in longitudinal samples from two childhood-onset SLE cohorts (n = 101 and n = 34, respectively), and associations with clinical features were assessed. Disease activity was measured using Safety of Estrogen in Lupus National Assessment (SELENA)-SLEDAI. Cluster analysis subdivided patients into three mutually exclusive fingerprint-groups termed (1) all-signatures-low, (2) only IFN high (M1.2 and/or M5.12) and (3) high NPh and/or PLC. All gene signatures were significantly associated with disease activity in cross-sectionally collected samples. The PLC-signature showed the highest association with disease activity. Interestingly, in longitudinally collected samples, the PLC-signature was associated with disease activity and showed a decrease over time. When patients were divided into fingerprints, the highest disease activity was observed in the high NPh and/or PLC group. The lowest disease activity was observed in the all-signatures-low group. The same distribution was reproduced in samples from an independent SLE cohort. The identified gene signatures were associated with disease activity and were indicated to be suitable tools for stratifying SLE patients into groups with similar activated immune pathways that may guide future treatment choices.

The origin and mechanisms of autoantigen generation in systemic lupus erythematosus (SLE) are poorly understood. Here, we identified SLE neutrophils activated in vivo by IFN as a prominent source of Ro52, also known as tripartite motif–containing protein 21 (TRIM21), a critical autoantigen historically thought to be primarily generated by keratinocytes in SLE. Different from mononuclear cells and keratinocytes, SLE neutrophils are enriched in several unique Ro52 species containing a core sequence encoded by exon 4 (Ro52Ex4) in TRIM21. Ro52Ex4 is the main target of anti-Ro52 antibodies and is found in 2 Ro52 variants (Ro52α and an isoform termed Ro52γ) upregulated in SLE neutrophils. Further analysis of Ro52γ revealed a subset of autoantibodies against a unique C-terminal domain (Ro52γCT) generated from a frameshift due to the lack of exon 6 in Ro52γ. Antibodies to Ro52Ex4 and Ro52γCT distinguish SLE patient subsets characterized by distinct clinical, laboratory, treatment, and transcriptional profiles that are not discerned by the “classical” anti-Ro52 antibodies. These studies uncover IFN-activated neutrophils as a key source of unique immunogenic forms of Ro52 in SLE. Moreover, the finding of Ro52Ex4 and Ro52γCT as core targets of anti-Ro52 antibodies focus interest on Ro52γ as the potential isoform toward which immunological tolerance is initially lost in SLE.

Objective To combine targeted transcriptomic and proteomic data in an unsupervised hierarchical clustering method to stratify patients with childhood-onset SLE (cSLE) into similar biological phenotypes, and study the immunological cellular landscape that characterises the clusters. Methods Targeted whole blood gene expression and serum cytokines were determined in patients with cSLE, preselected on disease activity state (at diagnosis, Low Lupus Disease Activity State (LLDAS), flare). Unsupervised hierarchical clustering, agnostic to disease characteristics, was used to identify clusters with distinct biological phenotypes. Disease activity was scored by clinical SELENA-SLEDAI (Safety of Estrogens in Systemic Lupus Erythematosus National Assessment-Systemic Lupus Erythematosus Disease Activity Index). High-dimensional 40-colour flow cytometry was used to identify immune cell subsets. Results Three unique clusters were identified, each characterised by a set of differentially expressed genes and cytokines, and by disease activity state: cluster 1 contained primarily patients in LLDAS, cluster 2 contained mainly treatment-naïve patients at diagnosis and cluster 3 contained a mixed group of patients, namely in LLDAS, at diagnosis and disease flare. The biological phenotypes did not reflect previous organ system involvement and over time, patients could move from one cluster to another. Healthy controls clustered together in cluster 1. Specific immune cell subsets, including CD11c+ B cells, conventional dendritic cells, plasmablasts and early effector CD4+ T cells, differed between the clusters. Conclusion Using a targeted multiomic approach, we clustered patients into distinct biological phenotypes that are related to disease activity state but not to organ system involvement. This supports a new concept where choice of treatment and tapering strategies are not solely based on clinical phenotype but includes measuring novel biological parameters.

Objectives In childhood-onset SLE (cSLE), patients have an increased risk of premature atherosclerosis. The pathophysiological mechanisms for this premature atherosclerosis are not yet completely understood, but besides traditional risk factors, the endothelium plays a major role. The first aim of this study was to measure levels of SLE-associated markers involved in endothelial cell (EC) function and lipids in a cSLE cohort longitudinally in comparison with healthy controls (HC). Next aim was to correlate these levels with Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and nailfold capillaroscopic patterns. Methods Blood serum samples, videocapillaroscopy images and patient characteristics were collected in a multicentre longitudinal cSLE cohort and from age and sex comparable HC. Disease activity was evaluated by SLEDAI. A total of 15 EC markers and six lipids were measured in two longitudinal cSLE samples (minimum interval of 6 months) and in HC. Nailfold videocapillaroscopy images were scored according to the guidelines from the EULAR Study Group on Microcirculation in Rheumatic Diseases. Results In total, 47 patients with cSLE and 42 HCs were analysed. Median age at diagnosis was 15 years (IQR 12–16 years). Median time between t=1 and t=2 was 14.5 months (IQR 9–24 months). Median SLEDAI was 12 (IQR 6–18) at t=1 and 2 (IQR 1–4) at t=2. Serum levels of angiopoietin-2, CCL2, CXCL10, GAS6, pentraxin-3, thrombomodulin, VCAM-1 and vWF-A2 were elevated in cSLE compared with HC at t=1. While many elevated EC markers at t=1 normalised over time after treatment, several markers remained significantly increased compared with HC (angiopoietin-2, CCL2, CXCL10, GAS6, thrombomodulin and VCAM-1). Conclusion In serum from patients with cSLE different markers of endothelial activation were dysregulated. While most markers normalised during treatment, others remained elevated in a subset of patients, even during low disease activity. These results suggest a role for the dysregulated endothelium in early and later phases of cSLE, possibly also during lower disease activity. Trial registration number NL60885.018.17.