| 1. |
- Bolin, Karin
(författare)
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Lupus Nephritis – Genetic Impact on Clinical Phenotypes, Disease Severity and Renal Outcome
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Systemic lupus erythematosus (SLE) is an autoimmune inflammatory disease that can affect every organ system. Lupus nephritis (LN) is one of the more serious SLE manifestations. Whilst the genetic background of SLE has been thoroughly investigated, less is known about the background of LN. The aim of this thesis was to further elucidate the genetic background of LN, its subtypes and outcome.In paper I, we analysed genetic variations for association with LN, its severe form proliferative nephritis and renal outcome, in two SLE cohorts. Patients and controls were genotyped and association analyses were performed for patients versus controls and for patients with or without a specific clinical manifestation. In the case-control analysis of cohort I, four highly linked risk alleles in the STAT4 gene were associated with LN with genome-wide significance. In the case-only meta-analysis of the two cohorts, a STAT4 risk allele was associated with severe renal insufficiency. We conclude that genetic variations in STAT4 predispose to LN and a worse outcome with severe renal insufficiency.In paper II, we describe a case of severe SLE on the basis of C1q deficiency. By sequencing, a mutation in the C1qC gene leading to a premature stop codon was found. The patient was also found to carry risk alleles in several SLE-associated variants. Interferon alpha (IFN-α) levels were analysed over time in patient serum, and were found to correlate with disease activity. The patient’s serum had a strong interferogenic capacity when stimulating peripheral blood mononuclear cells from healthy individuals. With this study, we further emphasise the role of IFN-α in C1q deficiency and highlight the need to consider inherited impairments in the complement system in SLE with childhood onset.In paper III, we studied the impact of sex on disease manifestations in SLE. Female SLE patients more often presented with malar rash, photosensitivity, oral ulcers and arthritis, whilst the frequency of serositis, renal disorder and immunologic disorder were higher among male patients. Women were younger at LN onset, whereas men had a higher risk for progression into end-stage renal disease.In paper IV, we analysed genetic variations for association with LN and its subtypes in three SLE cohorts. Patients were genotyped and association analyses were performed for patients with versus without different phenotypes. We found genetic variations in the BANK1 gene to be associated with LN.In conclusion, this thesis provides further insight into the genetic background of renal manifestations in patients with SLE.
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| 2. |
- Imgenberg-Kreuz, Juliana
(författare)
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Epigenetic and Gene Expression Signatures in Systemic Inflammatory Autoimmune Diseases
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Autoimmune diseases are clinical manifestations of a loss-of-tolerance of the immune system against the body’s own substances and healthy tissues. Primary Sjögren’s syndrome (pSS) and systemic lupus erythematosus (SLE) are two chronic inflammatory autoimmune diseases characterized by autoantibody production and an activated type I interferon system. Although the precise mechanisms leading to autoimmune processes are not well defined, recent studies suggest that aberrant DNA methylation and gene expression patterns may play a central role in the pathogenesis of these disorders. The aim of this thesis was to investigate DNA methylation and gene expression in pSS and SLE on a genome-wide scale to advance our understanding of how these factors contribute to the diseases and to identify potential biomarkers and novel treatment targets.In study I, differential DNA methylation was analyzed in multiple tissues from pSS patients and healthy controls. We identified thousands of CpG sites with perturbed methylation; the most prominent finding was a profound hypomethylation at regulatory regions of type I interferon induced genes in pSS. In study II, a cases-case study comparing DNA methylation in pSS patients with high fatigue to patients with low fatigue, we found methylation patterns associated to the degree of fatigue. In study III, RNA-sequencing was applied to investigate the transcriptome of B cells in pSS in comparison to controls. Increased expression of type I and type II interferon regulated genes in pSS was observed, indicating ongoing immune activation in B cells. In study IV, the impact of DNA methylation on disease susceptibility and phenotypic variability in SLE was investigated. We identified DNA methylation patterns associated to disease susceptibility, SLE manifestations and different treatments. In addition, we mapped methylation quantitative trait loci and observed evidence for genetic regulation of DNA methylation in SLE. In conclusion, the results presented in this thesis provide new insights into the molecular mechanisms underlying autoimmunity in pSS and SLE. The studies confirm the central role of the interferon system in pSS and SLE and further suggest novel genes and mechanisms to be involved in the pathogenesis these autoimmune diseases.
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| 3. |
- Kristjansdottir, Gudlaug Thora, 1972-
(författare)
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Genetic Variation and Expression of the IRF5 Gene in Autoimmune Diseases
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The interferon regulatory factor 5 (IRF5) gene encodes a transcription factor that plays an important role in the innate as well as in the cell-mediated immune response. The IRF5 gene has received considerable attention since it was shown to be associated with two autoimmune diseases; systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). The aim of this thesis was to examine if IRF5 is associated with other autoimmune diseases and to investigate the role of the genetic variation of IRF5. In the first study a set of common polymorphisms in IRF5 were analyzed for their association with two subgroup of inflammatory bowel disease (IBD); Crohn´s diseases (CD) and ulcerative colitis (UC). A strong signal of association of IRF5 with IBD was found. The most strongly associated polymorphism is a 5 base pair (bp) insertion-deletion (indel) in the promoter region of the IRF5 gene. The association was detected within both UC and CD, and appeared to be stronger in UC. In the second study we investigated the association of IRF5 with multiple sclerosis (MS). A similar set of polymorphisms as in the IBD study were genotyped in a cohort of MS patients and controls. The same polymorphisms that were associated with IBD were also found to be associated with MS. In the third study, we performed a comprehensive investigation of the IRF5 gene to detect most of the polymorphisms in the gene, and to determine to what extent they account for the association signals obtained from the gene. IRF5 was sequenced and 34 new polymorphisms were identified. Twenty seven of these, and 20 previously known SNPs in IRF5 were genotyped in an SLE case-control cohort. We found that only two polymorphisms, the 5bp indel and a SNP downstream of IRF5, account for the association signal from all the remaining markers in the IRF5 gene, and that these two polymorphisms are independently associated with SLE. Interestingly, in our studies on IBD and MS, we only observed the signal from the 5bp indel polymorphism as a risk factor for IBDs. In the fourth study the two independent risk alleles in IRF5, were tested for their association with primary Sjögren´s syndrome (pSS). In this study we also included one SNP in the STAT4 gene, since STAT4 had recently been shown to be associated with SLE. Both risk factors in IRF5 and STAT4 were found to be associated with pSS. The regulation of expression of IRF5 was also investigated in the first three studies. We observed allele-specific differences in protein binding as well as increased binding of the transcription factor SP1 to the 5bp risk allele. We also detected increased expression of the IRF5 mRNA from a promoter containing the risk allele. Taken together, the results of our studies suggest a general function for IRF5 as a regulator of the autoimmune response, where the 5bp indel is associated with IBD, MS, SLE and pSS. The additionally polymorphisms, which account for the remaining association signal obtained with SLE and pSS, may contribute to the disease manifestations that are specific for rheumatic diseases. Our studies add to the evidence that there are genes or pathways that are common in multiple autoimmune diseases, and that the type I interferon system is likely to be involved in the development of these diseases.
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| 4. |
- Leonard, Dag, 1975-
(författare)
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Cardiovascular Disease and Immune Mechanisms in Systemic Lupus Erythematosus
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Systemic lupus erythematosus (SLE) is an autoimmune, inflammatory disease characterized by autoantibody production and an activated type I interferon system. Cardiovascular disease (CVD) is as a major cause of morbidity and mortality. The aim of this thesis was to identify genetic risk factors for CVD in SLE. The role of T cells in regulation of the interferon-α (IFNα) production by plasmacytoid dendritic cells (pDCs) was also investigated. In paper I, a thicker intima, thinner media and increased intima/media ratio was found in young premenopausal women with SLE compared to healthy controls indicating increased cardiovascular risk. As traditional ultrasound assessment of the common carotid intima-media thickness (CCA-IMT) in SLE has given conflicting results separate measurement of the intima and media can be a useful tool to identify SLE patients at increased risk of CVD. In paper II, an association was demonstrated in SLE between a STAT4 risk allele and ischemic cerebrovascular disease and presence of anti-phospholipid antibodies (aPL). The association remained after adjustment for traditional CVD risk factors. A possible mechanism for this association is that the risk allele leads to increased production of aPL, which promotes thromboembolism. In paper III, a genetic locus in IRF8 was identified to be associated to coronary heart disease (CHD) in SLE. The association remained after adjustment of other CHD risk factors. Patients with the IRF8 risk variant had increased CCA-IMT, more carotid plaques and reduced frequency of circulating B cells. Weaker binding of nuclear protein to the risk allele was demonstrated, suggesting a regulatory function of the IRF8 risk variant. In paper IV, activated T cells were found to strongly enhance the IFNα production by pDC stimulated with RNA-containing immune complexes via GM-CSF and IL-3. Activated SLE T cells enhanced the IFNα production to the same extent as T cells from healthy controls. This finding together with previous observations in SLE of increased levels of GM-CSF and IL-3 suggests that T cells contribute to the activated type I interferon system in SLE. In conclusion, this thesis demonstrates that genetic predisposition is important for CVD in SLE and describes a new role for T cells in the pathogenesis of SLE.
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| 5. |
- Nordmark, Gunnel, 1961-
(författare)
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Clinical and Experimental Studies in Primary Sjögren’s Syndrome and Systemic Lupus Erythematosus
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Autoimmune mechanisms and genetic susceptibility contribute to the pathogenesis of primary Sjögren’s syndrome and SLE. These chronic systemic autoimmune diseases have many serological and clinical features in common and have an impact on daily life. The studies in this thesis aim to elucidate their autoimmune mechanisms, define susceptibility genes and evaluate effects of androgen supplement on health-related quality of life. Autoantibodies against α-fodrin, a widely distributed cytoskeletal protein, were detected at similar frequencies in sera from patients with primary and secondary Sjögren’s syndrome and SLE. Consequently, testing for antibodies against α-fodrin would not add diagnostic value compared to conventional serological analysis and does not discriminate between these diseases. The type I interferon (IFN) system was found to be activated in primary Sjögren’s syndrome. IFN-α containing cells were detected in minor salivary gland biopsies, while sera from patients with primary Sjögren’s syndrome induced IFN-α production in the presence of apoptotic and necrotic cell material. This ability of sera correlated with the presence of antibodies against RNA-binding proteins and IFN-α production was dependent on RNA in immune complexes. The natural interferon producing cells/plasmacytoid dendritic cells (NIPC/PDC) were the IFN-α producers and blocking of FcγRIIa inhibited the production. Single nucleotide polymorphisms (SNPs) in two genes in the type I IFN signalling pathway, those for tyrosine kinase 2 and interferon regulatory factor 5, were strongly associated with SLE in a Swedish, Finnish and Icelandic population. The minor allele frequencies were lower in SLE patients than in healthy controls. These SNPs may decrease the function of the type I IFN system, thereby conferring protection against SLE. Supplementation with dehydroepiandrosterone (DHEA) in glucocorticoid treated women with SLE led to mild improvements in health-related quality of life in respect of mental well-being and sexuality, whereas physical well-being was unaffected.
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