Dag Leonard

Systemic sclerosis (SSc) is an autoimmune rheumatic disease characterized by vasculopathy, inflammation, and fibrosis [1,2]. SSc is subclassified into diffuse cutaneous (dcSSc) and limited cutaneou...

Background: Although systemic lupus erythematosus (SLE) pregnancy frequently results in small for gestational age (SGA) infants, the understanding of underlying mechanisms is limited. We aimed to identify specific histological patterns of placental injury in SGA in SLE and to explore whether an altered balance of angiogenesis‐related proteins precedes this outcome. Methods: We prospectively followed 83 SLE and 67 control pregnancies. Placental histological patterns were determined according to the Amsterdam consensus in 63 women with SLE (76%), of whom 10 developed SGA. Soluble fms‐like tyrosine kinase 1 (sFlt‐1) and placental growth factor (PlGF) in plasma were quantified using LEGENDplex in the first, second and third trimesters. Results: SLE patients remain at risk of having an SGA infant, and their placentas and infants had lower weight compared to controls. In placentas from women with SLE and SGA, maternal vascular malperfusion lesions were common (80% vs. 30% in controls; p = 0.010), but inflammatory lesions were not observed. Women with maternal vascular malperfusion gave birth to infants with lower birth weight compared to women without these lesions. The ratio of sFlt‐1:PlGF in the third trimester was elevated in women with SLE with an SGA infant. Conclusion: In a prospective cohort of well‐controlled SLE patients with low disease activity delivering mostly at term, SGA and small placentas remain common. The increased prevalence of placental malperfusion lesions together with an altered balance of pro‐ and anti‐angiogenic proteins suggests that the role of vascular and angiogenesis‐related factors should be further explored in relation to SGA in SLE pregnancy.

Objective: Lupus nephritis (LN) is a potentially severe manifestation of SLE, often resulting in permanent kidney damage. We investigated whether polygenic and/or epigenetic risk is associated with time to LN relapse and whether this association differs by initial therapy. Methods: Caucasian patients with biopsy-verified LN between 1974 and 2022 (n=149) were genotyped using the Illumina Global Screening Array, and DNA methylation was assessed with the Illumina HumanMethylation450k BeadChip. A weighted Polygenic Risk Score (PRS) based on 55 non-Human leukocyte antigen (HLA) SLE risk gene variants and a Methylation Risk Score (MRS) based on the 17 most differentially methylated cytosine-phosphate-guanine sites identified in SLE-control comparison were calculated. Time to LN relapse was analysed using Cox proportional hazards models, adjusted for centre, sex and year of the first LN. Results: Neither PRS nor MRS was associated with time to LN relapse in the overall cohort, irrespective of treatment (PRS: HR=1.00 (0.77–1.30); p=0.99; MRS: HR=1.01 (1.00–1.02); p=0.21). No associations were observed among cyclophosphamide (CYC)-treated patients (PRS: HR=0.81 (0.55–1.20); p=0.29; MRS: HR=1.00 (0.99–1.02); p=0.89). In non-CYC-treated patients, PRS showed a non-significant trend towards shorter time to LN relapse (HR=1.26 (0.88–1.81); p=0.21), with a similar trend for MRS (HR=1.02 (1.00–1.03); p=0.066). Adding MRS to the PRS model improved performance in this subgroup (likelihood ratio test, p=0.028), with significant associations for MRS (PRS: HR=1.56 (0.97–2.50); p=0.066; MRS: HR=1.02 (1.00–1.04); p=0.037). Conclusions: Genetic and epigenetic susceptibility appears to influence LN relapse risk in a treatment-dependent manner. The absence of an association among patients receiving CYC suggests that initial treatment with CYC may attenuate the impact of genetic and epigenetic predisposition on relapse. These findings support the potential of genetic and epigenetic profiling at LN diagnosis to improve relapse risk stratification and individualise selection of treatment.

Objectives: Patients with Systemic lupus erythematosus (SLE) who carry a high genetic burden often experience more severe disease. To understand the molecular consequences of polygenic risk, we analyzed single-cell gene expression profiles in SLE patients stratified by genetic risk. Methods: Single-cell RNA sequencing (scRNA-seq) was performed on fresh peripheral blood mononuclear cells (PBMCs) from 16 female SLE patients, stratified by a weighted polygenic risk score (PRS), and 6 healthy controls (HCs). All patients were in low disease activity (LLDAS) and treated with antimalarials only. We assessed differential gene expression, interferon (IFN) signatures, transcription factor (TF) activity, and pathway enrichment across groups. Results: Patients with High-PRS had significantly elevated IFN scores compared to HCs (p0.05) This pattern held across multiple immune cell types, including T cells, NK cells, and monocytes. Notable genes with increased expression in High-PRS patients included ISG15 and USP18 in plasmacytoid dendritic cells (pDCs), and IFI27 and RSAD2 in monocytes. IFN-related pathways were enriched in pDCs and monocytes in High-PRS patients, and only in monocytes in Low-PRS patients. TF analysis identified IRF7 and BATF3 as key candidate regulators in High-PRS of both cell types. Conclusions: High polygenic risk in SLE is associated with persistent activation of IFN signaling pathways, indicating that antimalarial treatment alone is insufficient to fully suppress IFN activity, even during remission or low disease activity.

Objectives: The aetiopathogenesis of SLE encompasses genetic, environmental and epigenetic factors. We investigated associations between an SLE methylation risk score (MRS), HLA-DRB1*03:01, a non-HLA polygenic risk score (PRS) and clinical and immunological phenotypes. Methods: DNA methylation in whole blood from patients fulfilling ≥4 ACR-82 criteria and controls were investigated using the Illumina HM450K array. The discovery cohort included 311 patients and 400 controls, and the replication cohort comprised 175 patients and 187 controls. Seventeen independent, top differentially methylated CpG sites (Δβ of ≥0.1) from case-control comparisons, were used to calculate the MRS. Genotyping was performed using the Immunochip, and the PRS included 57 non-HLA SLE SNVs. Clinical data were collected from patient charts, and serum IFN-α2 was measured using Simoa. Results: Higher MRS was strongly associated with serum IFN-α2 levels (p=1.04×10 ⁻¹⁴ ). In both cohorts, higher MRS associated with discoid lupus, immunologic involvement, and anti-SSA/SSB/RNP/Sm autoantibodies (all p-15 ) and in HLA-DRB1*03:01 carriers (p-3 ). In contrast, higher PRS was associated with nephritis, anti-dsDNA positivity, and lower prevalence of anti-SSB antibodies (all p<0.05). No correlation was observed between the MRS and the PRS (p=0.35). Conclusion: The MRS defines an interferon-high, HLA-DRB1*03:01-linked SLE subset with multiple autoantibodies, partly distinct from PRS-associated nephritis risk, highlighting potentially divergent pathogenic pathways. These findings underscore the value of integrating genetic and epigenetic data to better understand underlying disease mechanisms in SLE. Key Messages: Higher MRS, but not PRS, correlated with increased levels of serum IFN-α. The MRS was associated with discoid rash, hematologic disorder, hypocomplementemia, antibodies including anti-SSA and HLA-DRB1*03:01. Higher PRS was linked to nephritis and anti-dsDNA positivity, and did not associate with the MRS.

Objective: To examine B cell-activating factor (BAFF) and type I interferon (IFN) activity at the transcriptional and protein levels in blood and placental tissue in SLE compared with healthy pregnancies to assess their relationship and to determine whether BAFF levels are associated with pregnancy outcomes in SLE. Methods: In the SLE-Placenta study, we followed women with SLE (n=83) and healthy controls (n=67) throughout pregnancy. Blood samples were collected in all trimesters and at delivery from peripheral blood, placental intervillous blood and cord blood. Postpartum blood samples were obtained from a subset of women with SLE. Bulk messenger RNA (mRNA) sequencing was performed on peripheral blood mononuclear cells (PBMCs) and placental tissue from a subgroup of women with SLE and healthy controls. BAFF concentrations were measured by ELISA and IFNα protein levels by single-molecule array (Simoa). Results: Women with SLE had upregulated BAFF ( TNFSF13B ) and IFN-stimulated gene expression in PBMCs and placenta compared with controls. BAFF blood levels were consistently and significantly higher in SLE throughout pregnancy and inversely correlated with circulating B cell numbers. SLE pregnancies with IF-ANA or anti-dsDNA positivity displayed higher BAFF levels than antibody-negative pregnancies but BAFF showed no association with disease activity. Both BAFF and IFNα concentrations were higher in placental than peripheral blood in SLE, whereas only BAFF showed additional accumulation in cord blood. Finally, elevated BAFF levels were associated with shorter pregnancy duration in SLE but not in healthy pregnancy. Conclusions: Pregnant women with SLE exhibited persistently elevated BAFF levels, which were associated with lower B cell numbers, SLE-related autoantibody positivity and shorter pregnancy duration. Together with a disease-specific placental enrichment of IFNα, these findings support the presence of an inflammatory and potentially pathogenic IFN-BAFF signature in SLE pregnancy. Further studies are needed to determine the functional consequences of these immunological alterations on maternal-fetal health in SLE.

Objective: SLE is a systemic autoimmune disease in which the complement system plays a key pathogenic role, yet the contribution of the lectin pathway remains unclear. Lectin pathway-dependent complement activation is initiated by pattern-recognition molecules complexed with mannose-binding lectin (MBL)-associated serine proteases (MASPs) and MBL-associated proteins (MAPs). Here, we combined biochemical and genetic analyses to explore associations between MASP/MAP proteins, SLE manifestations and autoantibody specificities. Methods: Serum concentrations of MASP-3, MAP-1 and MASP-2 were measured using ELISA in Swedish patients with SLE (n=522) and population-based matched controls (n=322). Serum type I interferon activity was measured by a cell-based reporter assay. Associations with SLE manifestations and autoantibodies were explored using logistic regression models. Single-nucleotide genetic variants spanning the MASP1 and MASP2 genes were analysed for associations with MASP/MAP levels and SLE manifestations. Results: Patients with MAP-1 serum concentrations in the highest quartile had significantly higher rates of discoid rash (OR 2.8 (95% CI 1.4 to 5.7)), haematological manifestations (OR 2.1 (95% CI 1.1 to 3.7)) and autoantibodies against Sm, RNP, SSA and SSB (ORs 2.4 (95% CI 1.3 to 4.6) to 3.6 (95% CI 1.7 to 7.7)). Patients in the highest quartiles of MAP-1 and MASP-2 had lower rates of anti-β2GP1 and anti-cardiolipin IgG and IgA anti-phospholipid antibodies (ORs 0.29 (95% CI 0.12 to 0.68) to 0.56 (95% CI 0.31 to 1.0)). Serum MAP-1 levels correlated with type I interferon activity (Spearman’s rho 0.34, p<0.0001), which mediated the associations of MAP-1 with haematological manifestations and Sm/RNP autoantibodies. Significant protein quantitative trait loci for MAP-1 and MASP-2 were identified; however, these did not show consistent associations with SLE or specific SLE manifestations. Conclusions: These results demonstrate a distinct clinical and serological SLE profile associated with components of the lectin pathway. The lectin pathway-regulatory protein MAP-1 displayed the strongest associations and may serve as a marker of SLE manifestations with a type I interferon signature.

Background: Systemic lupus erythematosus (SLE) is an autoimmune disease with a heterogenous clinical picture. This study aimed to link genetic SLE predisposition with relevant clinical manifestations. Method: Datasets best corresponding to the 11 American College of Rheumatology 1982 (ACR‐82) classification criteria for SLE in a large, public database (FinnGen consortium, >218,000 individuals) were identified. Mendelian randomization analysis was conducted to evaluate the effect of a high genetic SLE predisposition on each manifestation. Next, validation was conducted in a clinical SLE cohort comprising 1487 genotyped Scandinavian patients with detailed clinical data. Based on the public datasets, genetic risk scores (GRSs) for each relevant manifestation were constructed for each patient. Associations between each GRS and the corresponding ACR‐82 criterion were evaluated using logistic regression. Results: In the FinnGen biobank, the cumulative effect of the 57 SLE risk SNPs was associated with an increased risk of rosacea, OR 1.09 (1.03–1.16), polyarthropathies, OR 1.10 (1.06–1.14), pleural effusions, OR 1.09 (1.04–1.14), and hemolytic anemia, OR 1.32 (1.10–1.58). In the clinical cohort, 5 of the 11 GRSs generated from the public datasets were associated with their corresponding ACR‐82 criterion: arthritis, OR 1.15 (1.02–1.31), renal disorder, OR 1.15 (1.04–1.29), neurologic disorder, OR 1.24 (1.04–1.47), hematologic disorder, OR 1.12 (1.00–1.24), and immunologic disorder, OR 1.37 (1.22–1.56). Conclusion: The findings demonstrate that known SLE risk gene variants play a role in the development of at least half of the ACR‐82 criteria for SLE, indicating a future possibility of using genetics to predict a variety of disease sub‐phenotypes in SLE.