| 1. |
- Diaz-Gallo, Lina-Marcela, et al.
(author)
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Four Systemic Lupus Erythematosus Subgroups, Defined by Autoantibodies Status, Differ Regarding HLA-DRB1 Genotype Associations and Immunological and Clinical Manifestations
- 2022
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In: ACR Open Rheumatology. - : John Wiley & Sons. - 2578-5745. ; 4:1, s. 27-39
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Journal article (peer-reviewed)abstract
- Objective: The heterogeneity of systemic lupus erythematosus (SLE) constitutes clinical and therapeutical challenges. We therefore studied whether unrecognized disease subgroups can be identified by using autoantibody profiling together with HLA-DRB1 alleles and immunological and clinical data.Methods: An unsupervised cluster analysis was performed based on detection of 13 SLE-associated autoantibodies (double-stranded DNA, nucleosomes, ribosomal P, ribonucleoprotein [RNP] 68, RNPA, Smith [Sm], Sm/RNP, Sjögren's syndrome antigen A [SSA]/Ro52, SSA/Ro60, Sjögren's syndrome antigen B [SSB]/La, cardiolipin [CL]-Immunoglobulin G [IgG], CL-Immunoglobulin M [IgM], and β2 glycoprotein I [β2 GPI]-IgG) in 911 patients with SLE from two cohorts. We evaluated whether each SLE subgroup is associated with HLA-DRB1 alleles, clinical manifestations (n = 743), and cytokine levels in circulation (n = 446).Results: Our analysis identified four subgroups among the patients with SLE. Subgroup 1 (29.3%) was dominated by anti-SSA/Ro60/Ro52/SSB autoantibodies and was strongly associated with HLA-DRB1*03 (odds ratio [OR] = 4.73; 95% confidence interval [CI] = 4.52-4.94). Discoid lesions were more common for this disease subgroup (OR = 1.71, 95% CI = 1.18-2.47). Subgroup 2 (28.7%) was dominated by anti-nucleosome/SmRNP/DNA/RNPA autoantibodies and associated with HLA-DRB1*15 (OR = 1.62, 95% CI = 1.41-1.84). Nephritis was most common in this subgroup (OR = 1.61, 95% CI = 1.14-2.26). Subgroup 3 (23.8%) was characterized by anti-ß2 GPI-IgG/anti-CL-IgG/IgM autoantibodies and a higher frequency of HLA-DRB1*04 compared with the other patients with SLE. Vascular events were more common in Subgroup 3 (OR = 1.74, 95% CI = 1.2-2.5). Subgroup 4 (18.2%) was negative for the investigated autoantibodies, and this subgroup was not associated with HLA-DRB1. Additionally, the levels of eight cytokines significantly differed among the disease subgroups.Conclusion: Our findings suggest that four fairly distinct subgroups can be identified on the basis of the autoantibody profile in SLE. These four SLE subgroups differ regarding associations with HLA-DRB1 alleles and immunological and clinical features, suggesting dissimilar disease pathways.
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| 2. |
- Lundström, Emeli
(author)
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Genetic studies of the HLA locus in rheumatic diseases
- 2010
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Doctoral thesis (other academic/artistic)abstract
- Rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) share a complex etiology consisting of both genetic and environmental components. Stimulation of lymphocytes and various other immune cells, release of cytokines, activation of complement and production of autoantibodies due to loss of tolerance to self-antigens, contributes to the pathogenesis of both RA and SLE. These two complex diseases also share genetic factors such as those in the HLA, PTPN22, STAT4 and 6q23 loci, but their respective clinical phenotypes are clearly different. RA is characterized by symmetric arthritis of peripheral joints, which is chronic and progressive. In contrast, arthritis is only one among several clinical manifestations of SLE. Malar rash, photosensitivity, serositis and nephritis are a few indicatives of SLE but not of RA. The two clinical diseases seldom overlap and it is therefore thought that different etiological factors lie behind these two complex diseases. Such etiologic factors could be genetic factors with some being specific for SLE and others being specific for RA or alternatively the differential factors could be environmental. To scrutinize the genetic and environmental factors as well as the clinical characteristics within RA and SLE may allow us to easier characterize important subgroups within these two heterogeneous diseases. The overall aim of this thesis was to re-evaluate the contribution of the HLA loci in rheumatic diseases in view of new data regarding autoantibody status in RA and SLE. We provide novel data for RA in two different disease subtypes, i.e. with presence or absence of anti-citrullinated peptide antibodies (ACPA). Our data supports different genetic and etiological backgrounds for these two subsets by demonstrating distinct associations of risk and/or protection conferred by different genes/alleles within the extended HLA locus. For ACPA-positive RA we demonstrate a new finding where HLA-DPB1 was shown to associate with this subset only. Further, we confirm the protective effect from HLA-DRB1*13 which also seem to neutralize the effect observed from the shared epitope alleles in ACPA-positive disease. In addition, by scrutinizing the gene environment interaction between HLA-DRB1 shared epitope alleles and smoking in ACPA-positive RA we observed that even though the different shared epitope alleles are associated with different magnitudes of increased risk of ACPA-positive RA, the shared epitope-smoking interaction was found to be uniform. Concerning ACPA-negative RA, we observe that the previously associated DRB1*03 allele did not by itself increase the risk for development of the disease, rather in the combination with DRB1*13. For SLE, we confirm in two Caucasian cohorts, that low copy number variation (CNV) of C4A together with HLA-DRB1*03 associates with development of the disease. In addition, we define three different subgroups of SLE characterized by presence of the SSA/SSB and antiphopsholipid (aPL) autoantibodies and the HLA-DRB1 alleles *03, *04 and *15. These findings are similar to what we previously demonstrated for RA regarding definition of different subgroups correlating to autoantibody profiles and HLA-DRB1 alleles. Based on our observations, we suggest that these three subgroups of the disease should be considered in future studies of genetic and environmental risk factors of SLE. With these data, we hope to add on to the previous knowledge of how to be able to more clearly define distinct subgroups and by that, contribute to better prediction of disease development and improve targeted therapy for RA and SLE.
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| 3. |
- Lundström, Emeli, et al.
(author)
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HLA-DRB1*04/*13 alleles are associated with vascular disease and antiphospholipid antibodies in systemic lupus erythematosus
- 2013
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In: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 72:6, s. 1018-1025
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Journal article (peer-reviewed)abstract
- BACKGROUND AND OBJECTIVES:Vascular disease is common in systemic lupus erythematosus (SLE) and patients with antiphospholipid antibodies (aPL) are at high risk to develop arterial and venous thrombosis. Since HLA class II genotypes have been linked to the presence of pro-thrombotic aPL, we investigated the relationship between HLA-DRB1 alleles, aPL and vascular events in SLE patients.METHODS:665 SLE patients of Caucasian origin and 1403 controls were included. Previous manifestations of ischaemic heart disease, ischaemic cerebrovascular disease (ICVD) and venous thromboembolism (together referred to as any vascular events (AVE)) were tabulated. aPL were measured with ELISA. Two-digit HLA-DRB1 typing was performed by sequence-specific primer-PCR.RESULTS: HLA-DRB1*04 was more frequent among SLE patients with ICVD compared to unaffected patients. This association remained after adjustment for known traditional cardiovascular risk factors. HLA-DRB1*13 was associated with AVE. All measured specificities of aPL—cardiolipin IgG and IgM, β2-glycoprotein-1 IgG, prothrombin (PT) IgG and a positive lupus anticoagulant test were associated with HLA-DRB1*04—while HLA-DRB1*13 was associated with IgG antibodies (β2-glycoprotein-1, cardiolipin and PT). In patients with the combined risk alleles, HLA-DRB1*04/*13, there was a significant additive interaction for the outcomes AVE and ICVD.CONCLUSIONS:The HLA-DRB1*04 and HLA-DRB1*13 alleles are associated with vascular events and an aPL positive immune-phenotype in SLE. Results demonstrate that a subset of SLE patients is genetically disposed to vascular vulnerability.
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| 4. |
- Lundström, Emeli, et al.
(author)
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Opposing effects of HLA-DRB1*13 alleles on the risk of developing anti-citrullinated protein antibody-positive and anti-citrullinated protein antibody-negative rheumatoid arthritis
- 2009
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In: Arthritis and Rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 60:4, s. 924-930
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Journal article (peer-reviewed)abstract
- OBJECTIVE: The effect of non-shared epitope HLA-DRB1 alleles on rheumatoid arthritis (RA) is poorly understood. This study was undertaken to investigate the effects of several HLA-DRB1 alleles, independent of the shared epitope, on the risk of developing anti-citrullinated protein antibody (ACPA)-positive or ACPA-negative RA in a large case-control study. METHODS: HLA typing for the DRB1 gene was performed in 1,352 patients with RA and 922 controls from the Swedish Epidemiological Investigation of Rheumatoid Arthritis study. Relative risks (RRs) and 95% confidence intervals (95% CIs) were calculated. RESULTS: DRB1*13 was found to protect against ACPA-positive RA when stratifying for the shared epitope and using a dominant genetic model (RR 0.41 [95% CI 0.26-0.64]). Furthermore, DRB1*13 neutralized the effect of the shared epitope in ACPA-positive RA (RR 3.91 [95% CI 3.04-5.02] in patients who had the shared epitope but not DRB1*13, and RR 1.22 [95% CI 0.81-1.83] in patients with both the shared epitope and DRB1*13, as compared with patients negative for both the shared epitope and DRB1*13). However, we did not replicate the previous published risk of ACPA-negative RA conferred by DRB1*03 when a dominant genetic model was used (RR 1.29 [95% CI 0.91-1.82]). Similarly, no significant effect of DRB1*03 on RR for ACPA-negative RA was seen using the recessive genetic model (RR 1.18 [95% CI 0.6-2.4]). In contrast, the combination of DRB1*03 and DRB1*13 was significantly associated with increased risk of developing ACPA-negative RA (RR 2.07 [95% CI 1.17-3.67]). CONCLUSION: Our findings indicate that the DRB1*13 allele plays a dual role in the development of RA, by protecting against ACPA-positive RA but, in combination with DRB1*03, increasing the risk of ACPA-negative RA
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| 5. |
- Lundtoft, Christian, et al.
(author)
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Combined genetic deficiencies of the classical complement pathway are strongly associated with both systemic lupus erythematosus and primary Sjögren's syndrome
- 2022
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In: Arthritis & Rheumatology. - : Wiley. - 2326-5205 .- 2326-5191. ; 74:11, s. 1842-1850
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Journal article (peer-reviewed)abstract
- ObjectiveComplete genetic deficiency of the complement component C2 is a strong risk factor for monogenic systemic lupus erythematosus (SLE), but whether heterozygous C2 deficiency adds to the risk of SLE or primary Sjögren's syndrome (pSS) has not been studied systematically. Here we investigated heterozygous C2 deficiency and C4 copy number variation in relation to clinical manifestations in SLE and pSS.MethodsThe presence of the common 28-bp C2 deletion rs9332736 and C4 copy number variation was examined in Scandinavian patients diagnosed with SLE (n=958) or pSS (n=911), and 2,262 controls using DNA sequencing. Plasma concentration of complement proteins and classical complement function was analysed in a subgroup of patients.ResultsHeterozygous C2 deficiency – when present in combination with a low C4A copy number – substantially increased the risk of SLE (OR=10.2, CI95%: 3.5-37.0) and pSS (OR=13.0, CI95%: 4.5-48.4) when compared to individuals with two C4A copies and normal C2. For patients heterozygous for rs9332736 with one C4A copy, the median age of diagnosis was 7 years and 12 years earlier in SLE and pSS, respectively. Reduced plasma C2 (p=2x10-9) and impaired function of the classical complement pathway (p=0.03) was detected in SLE patients with heterozygous C2 deficiency. Finally, we describe a pSS patient with homozygous C2 deficiency.ConclusionWe demonstrate that the combination of partial deficiencies of C2 and C4A in the classical complement pathway is a strong risk factor for SLE and pSS. Our results emphasise the central role of the complement system in the pathogenesis of both diseases.
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