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1.  Genetic variants and disease-associated factors contribute to enhanced IRF-5 expression in blood cells of systemic lupus erythematosus patients 
Arthritis and rheumatism  2010;62(2):562-573.
Genetic variants of the interferon (IFN) regulatory factor 5 (IRF5) gene are associated with systemic lupus erythematosus (SLE) susceptibility. The contribution of these variants to IRF-5 expression in primary blood cells of SLE patients has not been addressed, nor has the role of type I IFN. The aim of this study was to determine the association between increased IRF-5 expression and the IRF5 risk haplotype in SLE patients.
IRF-5 transcript and protein levels in 44 Swedish patients with SLE and 16 healthy controls were measured by quantitative real-time PCR, minigene assay, and flow cytometry. The rs2004640, rs10954213, rs10488631 and the CGGGG indel were genotyped in these patients. Genotypes of these polymorphisms defined a common risk and protective haplotype.
IRF-5 expression and alternative splicing were significantly upregulated in SLE patients versus healthy donors. Enhanced transcript and protein levels were associated with the risk haplotype of IRF5; rs10488631 gave the only significant independent association that correlated with increased transcription from non-coding exon 1C. Minigene experiments demonstrated an important role for rs2004640 and the CGGGG indel, along with type I IFNs in regulating IRF-5 expression.
This study provides the first formal proof that IRF-5 expression and alternative splicing are significantly upregulated in primary blood cells of SLE patients. The risk haplotype is associated with enhanced IRF-5 transcript and protein expression in SLE patients.
PMCID: PMC3213692  PMID: 20112383
2.  A candidate gene study of the type I interferon pathway implicates IKBKE and IL8 as risk loci for SLE 
Systemic Lupus Erythematosus (SLE) is a systemic autoimmune disease in which the type I interferon pathway has a crucial role. We have previously shown that three genes in this pathway, IRF5, TYK2 and STAT4, are strongly associated with risk for SLE. Here, we investigated 78 genes involved in the type I interferon pathway to identify additional SLE susceptibility loci. First, we genotyped 896 single-nucleotide polymorphisms in these 78 genes and 14 other candidate genes in 482 Swedish SLE patients and 536 controls. Genes with P<0.01 in the initial screen were then followed up in 344 additional Swedish patients and 1299 controls. SNPs in the IKBKE, TANK, STAT1, IL8 and TRAF6 genes gave nominal signals of association with SLE in this extended Swedish cohort. To replicate these findings we extracted data from a genomewide association study on SLE performed in a US cohort. Combined analysis of the Swedish and US data, comprising a total of 2136 cases and 9694 controls, implicates IKBKE and IL8 as SLE susceptibility loci (Pmeta=0.00010 and Pmeta=0.00040, respectively). STAT1 was also associated with SLE in this cohort (Pmeta=3.3 × 10−5), but this association signal appears to be dependent of that previously reported for the neighbouring STAT4 gene. Our study suggests additional genes from the type I interferon system in SLE, and highlights genes in this pathway for further functional analysis.
PMCID: PMC3060320  PMID: 21179067
systemic lupus erythematosus; type I interferon system; candidate gene study; single nucleotide polymorphism; IKBKE; IL8
3.  A risk haplotype of STAT4 for systemic lupus erythematosus is over-expressed, correlates with anti-dsDNA and shows additive effects with two risk alleles of IRF5 
Human Molecular Genetics  2008;17(18):2868-2876.
Systemic lupus erythematosus (SLE) is the prototype autoimmune disease where genes regulated by type I interferon (IFN) are over-expressed and contribute to the disease pathogenesis. Because signal transducer and activator of transcription 4 (STAT4) plays a key role in the type I IFN receptor signaling, we performed a candidate gene study of a comprehensive set of single nucleotide polymorphism (SNPs) in STAT4 in Swedish patients with SLE. We found that 10 out of 53 analyzed SNPs in STAT4 were associated with SLE, with the strongest signal of association (P = 7.1 × 10−8) for two perfectly linked SNPs rs10181656 and rs7582694. The risk alleles of these 10 SNPs form a common risk haplotype for SLE (P = 1.7 × 10−5). According to conditional logistic regression analysis the SNP rs10181656 or rs7582694 accounts for all of the observed association signal. By quantitative analysis of the allelic expression of STAT4 we found that the risk allele of STAT4 was over-expressed in primary human cells of mesenchymal origin, but not in B-cells, and that the risk allele of STAT4 was over-expressed (P = 8.4 × 10−5) in cells carrying the risk haplotype for SLE compared with cells with a non-risk haplotype. The risk allele of the SNP rs7582694 in STAT4 correlated to production of anti-dsDNA (double-stranded DNA) antibodies and displayed a multiplicatively increased, 1.82-fold risk of SLE with two independent risk alleles of the IRF5 (interferon regulatory factor 5) gene.
PMCID: PMC2525501  PMID: 18579578
4.  Viral Protein VP4 Is a Target of Human Antibodies Enhancing Coxsackievirus B4- and B3-Induced Synthesis of Alpha Interferon 
Journal of Virology  2005;79(22):13882-13891.
Coxsackievirus B4 (CVB4)-induced production of alpha interferon (IFN-α) by peripheral blood mononuclear cells (PBMC) is enhanced in vitro by nonneutralizing anti-CVB4 antibodies from healthy subjects and, to a higher extent, from patients with insulin-dependent diabetes mellitus. In this study, we focused on identification of the viral target of these antibodies in CVB systems. High levels of IFN-α were obtained in supernatants of PBMC incubated with CVB4E2 or CVB3 and plasma from healthy subjects and, to a higher extent, from patients. The VP4 capsid proteins dissociated by heating at 56°C from CVB4E2 (VP4CVB4) and CVB3 (VP4CVB3) but not H antigen preincubated with plasma from healthy subjects or patients inhibited the plasma-dependent enhancement of CVB4E2- and CVB3-induced IFN-α synthesis. There was no cross-reaction between VP4CVB4 and VP4CVB3 in the inhibiting effect. IFN-α levels in culture supernatants showed dose-dependent correlation with anti-VP4 antibodies eluted from plasma specimens using VP4-coated plates. There were higher index values for anti-VP4 antibodies detected by enzyme-linked immunosorbent assay (ELISA) and higher proportions of positive detection in 40 patients than in 40 healthy subjects (80% versus 15% for anti-VP4CVB4). There was no relationship between the levels of anti-CVB neutralizing antibodies and the detection of anti-VP4 antibodies by ELISA. The CVB plasma-induced IFN-α levels obtained in PBMC cultures in the anti-VP4 antibody-positive groups were significantly higher than those obtained in the anti-VP4 antibody-negative groups regardless of the titers of anti-CVB neutralizing antibodies. These results show that VP4 is the target of antibodies involved in the plasma-dependent enhancement of CVB4E2- and CVB3-induced IFN-α synthesis by PBMC.
PMCID: PMC1280186  PMID: 16254324
5.  Systemic lupus erythematosus and the type I interferon system 
Arthritis Research & Therapy  2003;5(2):68-75.
Patients with systemic lupus erythematosus (SLE) have ongoing interferon-α (IFN-α) production and serum IFN-α levels are correlated with both disease activity and severity. Recent studies of patients with SLE have demonstrated the presence of endogenous IFN-α inducers in such individuals, consisting of small immune complexes (ICs) containing IgG and DNA. These ICs act specifically on natural IFN-α-producing cells (NIPCs), often termed plasmacytoid dendritic cells (PDCs). Given the fact that the NIPC/PDC has a key role in both the innate and adaptive immune response, as well as the many immunoregulatory effects of IFN-α, these observations might be important for the understanding of the etiopathogenesis of SLE. In this review we briefly describe the biology of the type I IFN system, with emphasis on inducers, producing cells (especially NIPCs/PDCs), IFN-α actions and target immune cells that might be relevant in SLE. On the basis of this information and results from studies in SLE patients, we propose a hypothesis that explains how NIPCs/PDCs become activated and have a pivotal etiopathogenic role in SLE. This hypothesis also indicates new therapeutic targets in this autoimmune disease.
PMCID: PMC165035  PMID: 12718746
dendritic cells; interferon-α; lupus; systemic lupus erythematosus; type I interferon
The Journal of Experimental Medicine  1969;129(6):1247-1259.
The effect of bursectomy combined with sublethal X-irradiation in the newly hatched chicken on the immunoglobulin and antibody producing capacity in later life was investigated. The previous findings of a significant incidence of hypogammaglobulinemia in such animals were confirmed. Spleen cells from severely hypogammaglobulinemic animals synthesized and secreted little or no immunoglobulin. Such spleen lymphoid cells contained fewer immunoglobulin antigenic determinants than spleen cells from irradiated control animals as evidenced by their relative inability to respond by an increased DNA synthesis after in vitro culture with rabbit antiserum to chicken immunoglobulin. Therefore, the deficiency in the immunoglobulin synthesis extends not only to actively secreting cells such as plasma cells, but to the entire lymphoid cell population. As expected, most irradiated-bursectomized chickens, irrespective of plasma immunoglobulin levels failed to produce detectable amount of circulating antibodies to Brucella abortus antigen in the primary immune response. Severely hypogammaglobulinemic animals were completely unable to elaborate any plaque forming cells (PFC) in the primary response to sheep red blood cells (SRBC). The results of this investigation support the contention that in the severely hypogammaglobulinemic bursectomized-irradiated chicken the entire antibody producing and immunoglobulin producing cell line is absent. The possibility remains that precursor or stem cells are present but are not appropriately directed to antibody synthesis by other cell types.
PMCID: PMC2138660  PMID: 4181832

Results 1-7 (7)