| 1. |
- Elbagir, Sahwa, et al.
(författare)
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Accumulation of antinuclear associated antibodies in circulating immune complexes is more prominent in SLE patients from Sudan than Sweden
- 2020
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- The role of anti-nuclear autoantibody (ANA) specificities in immune complexes (IC) formation has been studied to a limited extent in SLE, and not at all in African SLE patients. We compared ANA in IC from Sudanese and Swedish SLE patients. We included 93 Sudanese and 332 Swedish SLE patients fulfilling the 1982 ACR criteria. IC were captured using C1q-coated beads. ANA specificities were quantified in sera and IC. Results were related to modified SLEDAI. Whereas serum levels of anti-Sm, anti-dsDNA and anti-ribosomal P were higher in Swedish patients, IC levels of most ANA specificities were higher among Sudanese patients. This difference was especially prominent for anti-chromatin antibodies, which remained after adjustment for age, disease duration and treatment. Total levels of C1q-binding IC correlated with levels of specific ANA in IC, with highest correlations for anti-chromatin antibodies among Sudanese patients. Whereas occurrence of anti-SSA/Ro60, anti-histone and anti-U1RNP in both serum and IC associated with high SLEDAI score, anti-dsDNA in IC but not in serum associated with high SLEDAI. ANA, especially antibodies targeting chromatin, accumulate more in IC from Sudanese SLE patients. If the autoantibody fraction forming IC is pathogenically important, this might explain the generally described severe SLE in black populations.
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| 2. |
- Elbagir, Sahwa, et al.
(författare)
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Anti-histone and anti-nucleosome rather than anti-dsDNA antibodies associate with IFN-induced biomarkers in Sudanese and Swedish Systemic Lupus Erythematosus patients.
- 2024
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Ingår i: Rheumatology. - : OXFORD UNIV PRESS. - 1462-0324 .- 1462-0332.
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: In SLE, anti-dsDNA can co-occur with autoantibodies against other chromatin components, like histones and nucleosomes. These antibodies induce type-1 interferon production, a hallmark of SLE. We measured antinuclear antibody (ANA) sub-specificities and investigated their associations to inflammatory biomarkers including interferon-regulated chemokines.METHODS: We included 93 Sudanese and 480 Swedish SLE patients and matched controls (N = 104 + 192). Autoantibodies targeting ANA-subspecificites: dsDNA, Sm, Sm/U1RNPcomplex, U1RNP, SSA/Ro52, SSA/Ro60, SSB/La, ribosomal P, PCNA and histones were quantified in all subjects, anti-nucleosome only in the Swedish patients, with a bead-based multiplex immunoassay. Levels of 72 plasma biomarkers were determined with Proximity Extension Assay technique or ELISA.RESULTS: Among Sudanese patients, the investigated antibodies significantly associated with 9/72 biomarkers. Anti-histone antibodies showed the strongest positive correlations with MCP-3 and S100A12 as well as with interferon I-inducible factors MCP-1 and CXCL10. Anti-dsDNA antibodies associated with CXCL10 and S100A12, but in multivariate analyses, unlike anti-histone, associations lost significance.Among Swedish patients, MCP-1, CXCL10, SA100A12 also demonstrated stronger associations to anti-histone and anti-nucleosome antibodies, compared with anti-dsDNA and other ANA sub-specificities. In multiple regression models, anti-histone/nucleosome retained the strongest associations. When excluding anti-histone or anti-nucleosome positive patients, the associations between MCP-1/CXCL10 and anti-dsDNA were lost. In contrast, when excluding anti-dsDNA positive patients, associations with anti-histone and anti-nucleosome remained significant.CONCLUSION: In two cohorts of different ethnical origin, autoantibodies targeting chromatin correlate stronger with IFN-induced inflammatory biomarkers than anti-dsDNA or other ANA sub-specificities. Our results suggest that anti-histone/nucleosome autoantibodies may be main drivers of type-1 interferon activity in SLE.
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| 3. |
- Elbagir, Sahwa, et al.
(författare)
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Anti-phosphatidylserine/prothrombin antibodies and thrombosis associate positively with HLA-DRB1*13 and negatively with HLA-DRB1*03 in SLE
- 2023
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Ingår i: Rheumatology. - : Oxford University Press. - 1462-0324 .- 1462-0332. ; 62:2, s. 924-933
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Emerging evidence demonstrates that aPS-PT associate with thrombotic events. Genetic predisposition, including HLA-DRB1 alleles, is known to contribute to the occurrence of conventional aPL [anti-beta(2)glycoprotein-I (anti-beta(2)GPI) and aCL]. We investigated associations between aPS-PT and HLA-DRB1* alleles and thrombosis in SLE. Conventional aPL were included for comparison.Methods: We included 341 consecutive SLE patients, with information on general cardiovascular risk factors, including blood lipids, LA and thrombotic events. aPS/PT, anti-beta(2)GPI and aCL of IgA/G/M isotypes and LA were quantified.Results: aPS/PT antibodies associated positively with HLA-DRB1*13 [odds ratio (OR) 2.7, P = 0.002], whereas anti-beta(2)GPI and aCL antibodies associated primarily with HLA-DRB1*04 (OR 2.5, P = 0.0005). These associations remained after adjustment for age, gender and other HLA-DRB1* alleles. HLA-DRB1*13, but not DRB1*04, remained as an independent risk factor for thrombosis and APS after adjustment for aPL and cardiovascular risk factors. The association between DRB1*13 and thrombosis was mediated by aPS-PT positivity. HLA-DRB1*03, on the other hand, associated negatively with thrombotic events as well as all aPL using both uni- and multivariate analyses. HLA-DRB1*03 had a thrombo-protective effect in aPL-positive patients. Additionally, HLA-DRB1*03 was associated with a favourable lipid profile regarding high-density lipoprotein and triglycerides.Conclusions: HLA-DRB1*13 confers risk for both aPS-PT and thrombotic events in lupus. The association between HLA-DRB1*13 and thrombosis is largely, but not totally, mediated through aPS-PT. HLA-DRB1*03 was negatively associated with aPL and positively with favourable lipid levels. Thus, HLA-DRB1*03 seems to identify a subgroup of SLE patients with reduced vascular risk.
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| 4. |
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| 5. |
- Elbagir, Sahwa, et al.
(författare)
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Associations with thrombosis are stronger for antiphosphatidylserine/prothrombin antibodies than for the Sydney criteria antiphospholipid antibody tests in SLE
- 2021
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Ingår i: Lupus. - : Sage Publications. - 0961-2033 .- 1477-0962. ; 30:8, s. 1289-1299
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Antiphosphatidylserine/prothrombin complex antibodies (aPS/PT) are risk factors for thrombosis, yet further validation of their clinical relevance in different ethnic groups is required. We investigated the performance of aPS/PT of IgA/G/M isotypes among Sudanese and Swedish systemic lupus erythematosus (SLE) patients.Methods: Consecutive SLE patients/matched controls from Sudan (n = 91/102) and Sweden (n = 332/163) were included. All patients fulfilled the 1982 ACR SLE classification criteria. IgA/G/M of aPS/PT, anti-cardiolipin and anti-beta(2)glycoprotein I (anti-beta(2)GPI) were tested in both cohorts, and lupus anticoagulant (LA) also in the Swedish cohort. Clinical antiphospholipid syndrome-related events and atherosclerosis, measured as carotid plaques were assessed for associations. Univariate and multivariate analyses adjusting for cardiovascular risk factors were performed.Results: Sudanese SLE patients had higher levels of IgM aPS/PT, but using national cut-offs, the frequency of positivity was similar to Swedish patients for all isotypes. Among Swedish patients, all isotypes of aPS/PT associated with venous thromboembolism (VTE), while only IgA aPS/PT associated with arterial thrombosis (AT). aPS/PT antibodies associated strongly with LA and they were, independently, the best predictor for VTE. Double positivity for aPS/PT and anti-beta(2)GPI associated with higher VTE risk than the conventional triple positivity. Carotid plaques did not associate with any antiphospholipid antibody.Conclusions: IgA aPS/PT associated with AT, and the association of IgG/M aPS/PT with VTE outperforms LA and criteria antiphospholipid antibodies in Swedish SLE patients. Furthermore, double positivity for aPS/PT and anti-beta(2)GPI performed better than conventional triple positivity. Future studies need to address if aPS/PT can replace LA, as this would simplify clinical procedures.
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| 6. |
- Elbagir, Sahwa, 1983-
(författare)
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Autoimmunity in Africa: Comparing Systemic Lupus Erythematosus and Anti-phospholipid Antibodies in Sudan and Sweden
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Systemic Lupus Erythematosus (SLE) is a chronic immune complex (IC)-mediated disease with variable prevalence worldwide, reported to be more common in Africans, Hispanics and Asians than in Caucasian populations. Expression of autoantibodies might vary between different ethnic populations due to environmental and genetic factors. Antiphospholipid antibodies (aPL) react with several antigenic targets of negatively charged phospholipids and/or associated plasma proteins. In this thesis we have studied the immunological and clinical characteristics of SLE in patients from Sudan and Sweden using an identical methodology. We have also investigated the occurrence of aPL during healthy pregnancies in both countries.Sudanese patients with SLE were younger, had shorter disease duration and suffered from more organ damage compared to Swedish patients. Neurological involvement, predominantly in young patients, was the main contributor to organ damage among the Sudanese patients. When comparing anti-nuclear antibody (ANA) specificities in IC between Sudanese and Swedish patients, different results from ANA detected in serum was observed. While serum ANA levels were mainly higher in Swedish SLE patients, levels of most ANA specificities in IC, particularly anti-chromatin specificities, were increased in Sudanese patients. In both cohorts, ANA in IC associated with more active SLE. Sudanese SLE patients had a higher prevalence of IgA aPL using common assay cut-off points. However, aPL levels among controls were also higher in Sudan, and when cut-offs were adjusted based on national controls the difference in prevalence between the patient groups was no longer evident. A more recently defined test measuring antibody against the phosphatidylserine/prothrombin complex was the best aPL predictor of thrombosis in Swedish SLE patients, independent of cardiovascular risk factors and antiphospholipid antibody syndrome criteria tests. Levels of IgA aPL, particularly anti-β2 glycoprotein I, were higher in normal pregnancies of healthy women from Sudan. This was not observed in Swedish pregnancies, and it was not due to reactivity against domain 1 of the β2 glycoprotein I molecule.Levels of autoantibodies differed both for patients and healthy individuals from Sudan and Sweden, and the occurrence of antibodies among patients depended on the cut-offs used. Adjustments to national cut-offs revealed more associations between autoantibody occurrence and clinical manifestations in Sudan. We recommend that the evaluation of autoantibody prevalence and clinical significance in autoimmune diseases in populations of African origin should rely on cut-offs based on controls from the same population, both in research and clinical contexts.
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| 7. |
- Elbagir, Sahwa, et al.
(författare)
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High IgA antiphospholipid autoantibodies in healthy Sudanese explain the increased prevalence among Sudanese compared to Swedish systemic lupus erythematosus patients
- 2020
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Ingår i: Lupus. - : SAGE PUBLICATIONS LTD. - 0961-2033 .- 1477-0962. ; 29:11, s. 1412-1422
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: IgA antiphospholipid antibodies (aPL) are prevalent in systemic lupus erythematosus (SLE) patients of African American, Afro-Caribbean and South African origin. Nevertheless, data from North Africa are lacking, and most studies use manufacturer-suggested cut-offs based on Caucasian controls. Therefore, we compared aPL isotypes in Sudanese and Swedish SLE patients using nation-based cut-offs. Methods: Consecutive SLE patients and age- and sex-matched controls from Sudan (N = 115/106) and Sweden (N = 340/318) were included. All patients fulfilled the 1982 American College of Rheumatology SLE classification criteria. Antiphospholipid syndrome-related events were obtained from patients' records. IgA/G/M anticardiolipin and anti-beta(2) glycoprotein I (beta(2) GPI) were analysed with two independent assays. IgA anti-beta(2) GPI domain 1 (D1) was also investigated. Manufacturers' cut-offs and the 95th and 99th percentile cut-offs based on national controls were used. Results: Sudanese patients and controls had higher levels and were more often positive for IgA aPL than Swedes when using manufacturers' cut-offs. In contrast, using national cut-offs, the increase in IgA aPL among Sudanese patients was lost. Occurrence of IgA anti-D1 did not differ between the countries. Venous thromboses were less common among Sudanese patients and did not associate with aPL. No clinical associations were observed with IgA anti-beta(2) GPI in Sudanese patients. Thromboses in Swedes were associated with IgG/M aPL. Fetal loss was associated with aPL in both cohorts. Conclusions: IgA anti-beta(2) GPI prevalence was higher among Sudanese compared to Swedish patients when manufacturers' cut-offs were used. This situation was reversed when applying national cut-offs. Anti-D1 was not increased in Sudanese patients. Previous studies on populations of African origin, which demonstrate a high prevalence of IgA aPL positivity, should be re-evaluated using a similar cut-off approach.
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| 8. |
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| 9. |
- Elbagir, Sahwa, et al.
(författare)
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Sudanese and Swedish patients with systemic lupus erythematosus : immunological and clinical comparisons
- 2020
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Ingår i: Rheumatology. - : Oxford University Press (OUP). - 1462-0324 .- 1462-0332. ; 59:5, s. 968-978
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: SLE is known to have an aggressive phenotype in black populations, but data from African cohorts are largely lacking. We therefore compared immunological and clinical profiles between Sudanese and Swedish patients using similar tools.METHODS: Consecutive SLE patients from Sudan (n = 115) and Sweden (n = 340) and from 106 Sudanese and 318 Swedish age- and sex-matched controls were included. All patients fulfilled the 1982 ACR classification criteria for SLE. Ten ANA-associated specificities and C1q-binding immune complexes (CICs) were measured. Cut-offs were established based on Sudanese and Swedish controls, respectively. Disease activity was measured with a modified SLEDAI and organ damage with the SLICC Damage Index. In a nested case-control design, Swedish and Sudanese patients were matched for age and disease duration.RESULTS: Females constituted 95.6% and 88.1% of Sudanese and Swedish patients, respectively (P = 0.02), with younger age at inclusion (33 vs 47.7 years; P < 0.0001) and shorter disease duration (5 vs 14 years; P < 0.0001) among Sudanese patients. Anti-Sm antibodies were more frequent in Sudanese patients, whereas anti-dsDNA, anti-histone and CICs were higher in Swedish patients. In the matched analyses, there was a trend for higher SLEDAI among Swedes. However, Sudanese patients had more damage, solely attributed to high frequencies of cranial/peripheral neuropathy and diabetes.CONCLUSION: While anti-Sm is more common in Sudan than in Sweden, the opposite is found for anti-dsDNA. Sudanese patients had higher damage scores, mainly because of neuropathy and diabetes. Sudanese patients were younger, with a shorter SLE duration, possibly indicating a more severe disease course with impact on survival rates.
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| 10. |
- Grönwall, Caroline, et al.
(författare)
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A Comprehensive Evaluation of the Relationship Between Different IgG and IgA Anti-Modified Protein Autoantibodies in Rheumatoid Arthritis
- 2021
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Ingår i: Frontiers in Immunology. - : Frontiers Media S.A.. - 1664-3224. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Seropositive rheumatoid arthritis (RA) is characterized by the presence of rheumatoid factor (RF) and anti-citrullinated protein autoantibodies (ACPA) with different fine-specificities. Yet, other serum anti-modified protein autoantibodies (AMPA), e.g. anti-carbamylated (Carb), -acetylated (KAc), and malondialdehyde acetaldehyde (MAA) modified protein antibodies, have been described. In this comprehensive study, we analyze 30 different IgG and IgA AMPA reactivities to Cit, Carb, KAc, and MAA antigens detected by ELISA and autoantigen arrays in N=1985 newly diagnosed RA patients. Association with patient characteristics such as smoking and disease activity were explored. Carb and KAc reactivities by different assays were primarily seen in patients also positive for anti-citrulline reactivity. Modified vimentin (mod-Vim) peptides were used for direct comparison of different AMPA reactivities, revealing that IgA AMPA recognizing mod-Vim was mainly detected in subsets of patients with high IgG anti-Cit-Vim levels and a history of smoking. IgG reactivity to acetylation was mainly detected in a subset of patients with Cit and Carb reactivity. Anti-acetylated histone reactivity was RA-specific and associated with high anti-CCP2 IgG levels, multiple ACPA fine-specificities, and smoking status. This reactivity was also found to be present in CCP2+ RA-risk individuals without arthritis. Our data further demonstrate that IgG autoreactivity to MAA was increased in RA compared to controls with highest levels in CCP2+ RA, but was not RA-specific, and showed low correlation with other AMPA. Anti-MAA was instead associated with disease activity and was not significantly increased in CCP2+ individuals at risk of RA. Notably, RA patients could be subdivided into four different subsets based on their AMPA IgG and IgA reactivity profiles. Our serology results were complemented by screening of monoclonal antibodies derived from single B cells from RA patients for the same antigens as the RA cohort. Certain CCP2+ clones had Carb or Carb+KAc+ multireactivity, while such reactivities were not found in CCP2- clones. We conclude that autoantibodies exhibiting different patterns of ACPA fine-specificities as well as Carb and KAc reactivity are present in RA and may be derived from multireactive B-cell clones. Carb and KAc could be considered reactivities within the "Cit-umbrella" similar to ACPA fine-specificities, while MAA reactivity is distinctly different.
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