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  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.

Sjögren's disease (SjD) is a chronic autoimmune condition marked by lymphocytic infiltration of exocrine glands and production of autoantibodies such as anti-SSA/Ro, anti-SSB/La, and rheumatoid factor. B lymphocytes play a central role in disease pathogenesis, driving autoantibody production and glandular damage, and contributing to lymphomagenesis. Despite promising therapies, no effective treatment is currently available, partly due to the biological and clinical heterogeneity of the disease. While interferon (IFN) signatures and B cell–related markers are used for patient stratification, their integration remains unexplored. This study analyzed B cell transcriptional and metabolic profiles using bulk transcriptomic, clinical, and flow cytometry data from the PRECISESADS consortium, alongside public single-cell RNA-sequencing datasets. A B cell–specific IFN-α signature was established to stratify patients into IFN-positive and IFN-negative groups. Both showed reduced oxidative phosphorylation (OXPHOS) and translation in B cell subsets, suggesting a shared early metabolic reprogramming state. IFN-positive patients, however, displayed additional features, including enhanced glycolysis, amino acid and lipid metabolism, autophagy, and NF-κB signaling. They also showed an expansion of IFN-activated-naïve (naive IFN), Transitional, and double-negative (DN) B cells, particularly DN2 and DN2_CXCR3 subsets, which have been linked in the literature to autoreactivity and lymphoma development. The IFN-signature in naïve B cells and DN2 correlated with elevated anti-SSA/Ro and anti-SSB/La titers, while only naïve B cells showed an association with increased histological focus scores. These findings support B cell–specific IFN signature relevance in stratifying SjD patients and suggest new metabolic and transcriptional targets for disease monitoring and therapeutic development.

Objective: Systemic inflammatory autoimmune diseases (SIADs) such as systemic lupus erythematosus (SLE), primary Sjögren disease (pSS), and idiopathic inflammatory myopathies (myositis) are complex conditions characterized by shared circulating autoantibodies and clinical manifestations, including skin rashes, among others. This study was aimed at elucidating the genetics underlying these common features.

Methods: We performed targeted DNA sequencing of coding and regulatory regions from approximately 1,900 immune-related genes in a large cohort of 2,292 well-characterized Scandinavian patients with SIADs with SLE, pSS, and myositis as well as 1,252 controls. A gene-based functionally weighted genetic score for aggregate testing of all genetic variants, including rare variants, was complemented by in silico functional analyses and in vitro reporter experiments.

Results: Case–control association analysis detected known and potentially novel genetic loci in agreement with previous genetic and transcriptomics findings linked to the SIAD autoimmune background. Intriguingly, case–case comparisons between patient subgroups with and without specific autoantibodies revealed that the subgroups defined by antinuclear antibodies and anti–double-stranded DNA antibodies have unique genetic profiles reflecting their heterogeneity. When focusing on clinical features, we overall showed that dual-specificity phosphatase 1 (DUSP1) protective genetic variants lead to increased gene expression and potentially to anti-inflammatory effects on the SIAD-associated skin phenotype. This is consistent with recent genetic findings on eczema and with the previously reported down-regulation of the MAPK signaling-related gene DUSP1 in other skin disorders.

Conclusion: Together, this suggests common molecular mechanisms potentially underlying overlapping clinical manifestations shared among different disorders and informs clinical heterogeneity, which could be translated to improve disease diagnostic and treatment, also in more generalized disease frameworks.

In the 1980s, my research career begun with microbial DNA diagnostics at Orion Pharmaceutica in Helsinki, Finland, where I was part of an innovative team that developed novel methods based on the polymerase chain reaction (PCR) and the biotin-avidin interaction. One of our key achievements during this time was the invention of the solid-phase minisequencing method for genotyping single nucleotide polymorphisms (SNPs). In the 1990s, I shifted focus to human genetics, investigating mutations of the'Finnish disease heritage'. During this period, I also developed quantitative methods using PCR and minisequencing of mitochondrial mutations and for forensic analyses. In the late 1990s and early 2000s, microarray-based SNP genotyping became a major topic for my research, first in Helsinki and later with my research group at Uppsala University in Sweden. By the mid-2000s, I began collaborating with leading clinicians on genetics of autoimmune disease, specifically systemic lupus erythematosus and later worked on the classification and clinical outcome of pediatric acute lymphoblastic leukemia, when large-scale genomics and epigenomics emerged.These collaborations, which focused on integrating genomics into clinical practice, lasted almost two decades until I retired from research in 2022. In parallel with my research activities, I led the SNP/ DNA Technology Platform in the Wallenberg Consortium North program from 2001 to 2006. I continued as Director of the SNP&SEQ Technology Platform, which expanded rapidly during the 2010s, and became part of Science for Life Laboratory in 2013. Today (in 2024), the SNP&SEQ Technology Platform is one of the largest units of the Swedish National Genomics Infrastructure hosted by SciLifeLab. The present article provides a personal perspective on nearly four decades of research, highlighting projects and methods I found particularly exciting or important.

OBJECTIVE: B cells are important in the pathogenesis of primary Sjögren's syndrome (pSS). Patients positive for SSA/SSB autoantibodies are more prone to systemic disease manifestations and adverse outcomes. We aimed to determine the role of B cell composition, gene expression and B cell receptor (BCR) usage in pSS subgroups stratified for SSA/SSB antibodies.

METHODS: Over 230 000 B cells were isolated from peripheral blood of pSS patients (n = 6 SSA-, n = 8 SSA+ single positive and n = 10 SSA/SSB+ double positive) and four healthy controls, and processed for single cell RNA and VDJ sequencing.

RESULTS: We show that SSA/SSB+ patients present the highest and lowest proportion of naïve and memory B cells respectively, and the highest upregulation of interferon-induced genes across all B cell subtypes. Differential usage of IGHV showed that IGHV1-69 and IGHV4-30-4 were more often used in all pSS subgroups compared with controls. Memory B cells from SSA/SSB+ patients displayed a higher proportion of cells with unmutated VDJ transcripts compared to other pSS patient groups and controls, indicating altered somatic hypermutation processes. Comparison with previous studies revealed heterogeneous clonotype pools, with little overlap in CDR3 sequences. Joint analysis using scRNA-seq and scVDJ-seq data allowed unsupervised stratification pSS patients, and identified novel parameters that correlated to disease manifestations and antibody status.

CONCLUSION: We describe heterogeneity and molecular characteristics in B cells from pSS patients, providing clues to intrinsic differences in B cells that affect the phenotype and outcome, allowing stratification of pSS patients at improved resolution. This article is protected by copyright. All rights reserved.

Background In patients with idiopathic inflammatory myopathies (IIM), autoantibodies are associated with specific clinical phenotypes suggesting a pathogenic role of adaptive immunity. We explored if autoantibody profiles are associated with specific HLA genetic variants and clinical manifestations in IIM. Methods We included 1348 IIM patients and determined the occurrence of 14 myositis-specific or-associated autoantibodies. We used unsupervised cluster analysis to identify autoantibody-defined subgroups and logistic regression to estimate associations with clinical manifestations, HLA-DRB1, HLA-DQA1, HLA-DQB1 alleles, and amino acids imputed from genetic information of HLA class II and I molecules. Findings We identified eight subgroups with the following dominant autoantibodies: anti-Ro52, -U1RNP, -PM/Scl,-Mi2,-Jo1,-Jo1/Ro52,-TIF1 gamma or negative for all analysed autoantibodies. Associations with HLA-DRB1*11, HLA-DRB1*15, HLA-DQA1*03, and HLA-DQB1*03 were present in the anti-U1RNP-dominated subgroup. HLA-DRB1*03, HLA-DQA1*05, and HLA-DQB1*02 alleles were overrepresented in the anti-PM/Scl and anti-Jo1/ Ro52-dominated subgroups. HLA-DRB1*16, HLA-DRB1*07 alleles were most frequent in anti-Mi2 and HLA- DRB1*01 and HLA-DRB1*07 alleles in the anti-TIF1 gamma subgroup. The HLA-DRB1*13, HLA-DQA1*01 and HLA-DQB1*06 alleles were overrepresented in the negative subgroup. Significant signals from variations in class I molecules were detected in the subgroups dominated by anti-Mi2, anti-Jo1/Ro52, anti-TIF1 gamma, and the negative subgroup. Interpretation Distinct HLA class II and I associations were observed for almost all autoantibody-defined subgroups. The associations support autoantibody profiles use for classifying IIM which would likely reflect underlying pathogenic mechanisms better than classifications based on clinical symptoms and/or histopathological features. Funding See a detailed list of funding bodies in the Acknowledgements section at the end of the manuscript. Copyright (c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Introduction The suitability of whole-genome sequencing (WGS) as the sole method to detect clinically relevant genomic aberrations in B-cell acute lymphoblastic leukemia (ALL) was investigated with the aim of replacing current diagnostic methods.

Methods For this purpose, we assessed the analytical performance of 150 bp paired-end WGS (90x leukemia/30x germline). A set of 88 retrospective B-cell ALL samples were selected to represent established ALL subgroups as well as ALL lacking stratifying markers by standard-of-care (SoC), so-called B-other ALL.

Results Both the analysis of paired leukemia/germline (L/N)(n=64) as well as leukemia-only (L-only)(n=88) detected all types of aberrations mandatory in the current ALLTogether trial protocol, i.e., aneuploidies, structural variants, and focal copy-number aberrations. Moreover, comparison to SoC revealed 100% concordance and that all patients had been assigned to the correct genetic subgroup using both approaches. Notably, WGS could allocate 35 out of 39 B-other ALL samples to one of the emerging genetic subgroups considered in the most recent classifications of ALL. We further investigated the impact of high (90x; n=58) vs low (30x; n=30) coverage on the diagnostic yield and observed an equally perfect concordance with SoC; low coverage detected all relevant lesions.

Discussion The filtration of the WGS findings with a short list of genes recurrently rearranged in ALL was instrumental to extract the clinically relevant information efficiently. Nonetheless, the detection of DUX4 rearrangements required an additional customized analysis, due to multiple copies of this gene embedded in the highly repetitive D4Z4 region. We conclude that the diagnostic performance of WGS as the standalone method was remarkable and allowed detection of all clinically relevant genomic events in the diagnostic setting of B-cell ALL.

Genomic analyses have redefined the molecular subgrouping of pediatric acute lymphoblastic leukemia (ALL). Molecular subgroups guide risk-stratification and targeted therapies, but outcomes of recently identified subtypes are often unclear, owing to limited cases with comprehensive profiling and cross-protocol studies. We developed a machine learning tool (ALLIUM) for the molecular subclassification of ALL in retrospective cohorts as well as for up-front diagnostics. ALLIUM uses DNA methylation and gene expression data from 1131 Nordic ALL patients to predict 17 ALL subtypes with high accuracy. ALLIUM was used to revise and verify the molecular subtype of 281 B-cell precursor ALL (BCP-ALL) cases with previously undefined molecular phenotype, resulting in a single revised subtype for 81.5% of these cases. Our study shows the power of combining DNA methylation and gene expression data for resolving ALL subtypes and provides a comprehensive population-based retrospective cohort study of molecular subtype frequencies in the Nordic countries.

Objective Copy number variation of the C4 complement components, C4A and C4B, has been associated with systemic inflammatory autoimmune diseases. This study was undertaken to investigate whether C4 copy number variation is connected to the autoimmune repertoire in systemic lupus erythematosus (SLE), primary Sjogren's syndrome (SS), or myositis.

Methods Using targeted DNA sequencing, we determined the copy number and genetic variants of C4 in 2,290 well-characterized Scandinavian patients with SLE, primary SS, or myositis and 1,251 healthy controls.

Results A prominent relationship was observed between C4A copy number and the presence of SSA/SSB autoantibodies, which was shared between the 3 diseases. The strongest association was detected in patients with autoantibodies against both SSA and SSB and 0 C4A copies when compared to healthy controls (odds ratio [OR] 18.0 [95% confidence interval (95% CI) 10.2-33.3]), whereas a weaker association was seen in patients without SSA/SSB autoantibodies (OR 3.1 [95% CI 1.7-5.5]). The copy number of C4 correlated positively with C4 plasma levels. Further, a common loss-of-function variant in C4A leading to reduced plasma C4 was more prevalent in SLE patients with a low copy number of C4A. Functionally, we showed that absence of C4A reduced the individuals' capacity to deposit C4b on immune complexes.

Conclusion We show that a low C4A copy number is more strongly associated with the autoantibody repertoire than with the clinically defined disease entities. These findings may have implications for understanding the etiopathogenetic mechanisms of systemic inflammatory autoimmune diseases and for patient stratification when taking the genetic profile into account.

By performing whole-genome sequencing in a Swedish cohort of 71 parent-offspring trios, in which the child in each family is affected by systemic lupus erythematosus (SLE, OMIM 152700), we investigated the contribution of de novo variants to risk of SLE. We found de novo single nucleotide variants (SNVs) to be significantly enriched in gene promoters in SLE patients compared with healthy controls at a level corresponding to 26 de novo promoter SNVs more in each patient than expected. We identified 12 de novo SNVs in promoter regions of genes that have been previously implicated in SLE, or that have functions that could be of relevance to SLE. Furthermore, we detected three missense de novo SNVs, five de novo insertion-deletions, and three de novo structural variants with potential to affect the expression of genes that are relevant for SLE. Based on enrichment analysis, disease-affecting de novo SNVs are expected to occur in one-third of SLE patients. This study shows that de novo variants in promoters commonly contribute to the genetic risk of SLE. The fact that de novo SNVs in SLE were enriched to promoter regions highlights the importance of using whole-genome sequencing for identification of de novo variants.