Plasma levels of ß2-microglobulin are associated with atherosclerosis in patients with systemic lupus erythematosus: a cross-sectional cohort study.

Objective The objective of this paper is to examine the association between plasma levels of ß2-microglobulin (ß2MG), a protein previously associated with atherosclerosis, and the presence of carotid plaque (CP) or coronary artery calcium (CAC) in a cross-sectional cohort study of patients with systemic lupus erythematosus (SLE). Methods Patients with SLE were enrolled between June 2013 and May 2014. The presence of CP and CAC was assessed with ultrasonography and computed tomography scan, respectively. The presence of CP or CAC in the SLE patients was analyzed with respect to plasma levels of ß2MG and renal function expressed as the estimated glomerular filtration rate (eGFR). Results The study cohort consisted of 147 patients, 89% women and 95% Caucasians. The median age was 46 (range: 21-75) years with a median disease duration of 14 years. CP and CAC was observed in 29 (20%) and 57 (39%) of patients, respectively. CP or CAC was seen in 62 (42%) patients and was associated with the highest quartile of plasma ß2MG in patients with eGFR ≥ 90 ml/min/1.73 m2; OR = 18 (95% CI: 1.7-181). ß2MG adjusted for eGFR was also associated with presence of CP or CAC in the total cohort. The exclusion of 25 patients with a prior history of cardiovascular disease did not change the observed associations. Conclusion In this study, we found significant associations between imaging markers of atherosclerosis and high plasma levels of plasma ß2MG. These data suggest that ß2MG is a candidate for further study as a biomarker for atherosclerosis in SLE.

Single nucleotide polymorphisms in genes encoding toll-like receptors 7, 8 and 9 in Danish patients with systemic lupus erythematosus.

Several studies indicate a role for toll-like receptors (TLRs) in the pathogenesis of systemic lupus erythematosus (SLE). We aimed to investigate the risk of SLE and typical clinical and serological manifestations of SLE potentially conferred by selected single nucleotide polymorphisms (SNPs) of genes encoding TLR7, TLR8, and TLR9. Using a multiplexed bead-based assay, we analyzed eight SNPs in a cohort of 142 Danish SLE patients and a gender-matched control cohort comprising 443 individuals. Our results showed an association between the rs3853839 polymorphism of TLR7 and SLE (G vs. C, P = 0.008, OR 1.60, 95 % CI 1.12-2.27 in females; P = 0.02, OR 4.50, 95 % CI 1.18-16.7 in males) confirming recent findings in other populations. Additionally, an association between the rs3764879 polymorphism of TLR8 and SLE (G vs. C, P < 0.05, OR 1.36, 95 % CI 0.99-1.86 in females; P = 0.06, OR 4.00, 95 % CI 0.90-17.3 in males) was found. None of the other investigated SNPs were associated with SLE but several SNPs were associated with clinical and serological manifestations. In summary, a previously shown association between the rs3853839 SNP of TLR7 and SLE in Asian patients was also found in Danish patients. Together with the association of several other SNPs of TLR8 and TLR9 with various clinical and serological manifestations of SLE these findings corroborate the pathogenic significance of TLRs in SLE.

MBL2 gene variants coding for mannose-binding lectin deficiency are associated with increased risk of nephritis in Danish patients with systemic lupus erythematosus.

OBJECTIVES: Autoimmunity may in part result from deficiencies in the processing of apoptotic debris. As mannose-binding lectin (MBL) is involved in such processes, we hypothesized that the variants in the MBL2 gene resulting in MBL deficiency confer an increased risk of nephritis in systemic lupus erythematosus (SLE). METHODS: A total of 171 SLE patients attending a Danish tertiary rheumatology referral center were included. Common variant alleles in exon 1 of the MBL2 gene (R52C, rs5030737; G54D, rs1800450; G57E, rs1800451) were genotyped. The normal allele and variant alleles are termed A and O, respectively. The follow-up period was defined as the time from fulfillment of the ACR 1987 classification criteria for SLE until the occurrence of an event (nephritis, end-stage renal disease (ESRD), or death) or end of follow-up. Cox regression analyses were controlled for gender, age and race. RESULTS: During a median follow-up of 5.7 years, nephritis developed in 94 patients, and ESRD developed in 16 of these patients. Twenty-seven patients died. The distribution of the MBL2 genotypes A/A, A/O and O/O was 58%, 35% and 7.0%, respectively. Compared to the rest, O/O patients had 2.6 times (95% CI: 1.2-5.5) higher risk of developing nephritis, and their risk of death after 10 years was 6.0 times increased (95% CI: 1.0-36). MBL serum levels below 100 ng/ml were associated with a 2.0 (95% CI: 1.2-3.4; p = 0.007) increased risk of developing nephritis. ESRD and histological class of nephritis were not associated with MBL deficiency. CONCLUSIONS: Genetically determined MBL deficiency was associated with development of nephritis in SLE patients, but not with histological class of nephritis or ESRD.

Genetic polymorphisms of dsRNA ligating pattern recognition receptors TLR3, MDA5, and RIG-I. Association with systemic lupus erythematosus and clinical phenotypes.

This study aimed to demonstrate possible associations between genetic polymorphisms in Toll-like receptor 3, interferon induced with helicase C domain 1 (IFIH1) and DEAD (Asp-Glu-Ala-Asp) box polypeptide 58 and systemic lupus erythematosus (SLE), including the phenotypes lupus nephritis and malar rash, as well as the presence of autoantibodies against nucleic acid-containing complexes. Genotyping was carried out in two Danish cohorts [Copenhagen (CPH) and Odense (ODE)] totaling 344 patients and was compared with 641 previously genotyped healthy controls. In the ODE cohort, the patients were only genotyped for the rs1990760 polymorphism of IFIH1. Single nucleotide polymorphisms (SNPs) were determined by a multiplex bead-based assay (CPH cohort) or real-time PCR (ODE cohort). Associations were investigated using the Cochran-Armitage trend test. The odds ratio (OR) for minor allele homozygotes versus major allele homozygotes suggested a protective effect of the IFIH1 rs1990760 SNP for SLE in the ODE cohort [OR 0.52, 95 % confidence intervals (95 % CI) 0.31-0.88, Pcorr. = 0.05] but not in the CPH cohort, although the OR suggested a trend in the same direction, and when combining the two patient cohorts, ORs were 0.57, 95 % CI 0.37-0.88. None of the other investigated polymorphisms showed any association with SLE. Regarding phenotypes, we found a statistically significant association between rs1990760 and malar rash in the CPH cohort, with ORs suggesting a protective effect (OR 0.28, 95 % CI 0.13-0.62 for heterozygotes and OR 0.11, 95 % CI 0.03-0.41 for homozygotes, Pcorr. = 0.0001). There were no significant associations between rs1990760 and presence of anti-dsDNA, anti-U1RNP, or anti-Smith antibodies. Our study supports previous findings of an association between the rs1990760 polymorphism of IFIH1 and SLE and indicates that this SNP may also be associated with malar rash in SLE patients although this finding needs confirmation.

Increased serum ß2-microglobulin is associated with clinical and immunological markers of disease activity in systemic lupus erythematosus patients.

The objective of this study was to explore the relationship between serum levels of ß2-microglobulin (ß2MG), which some studies suggest reflect disease activity in systemic lupus erythematosus (SLE), and various clinical and immunological markers of disease activity in SLE. Twenty-six SLE patients and 10 healthy controls were included. Disease activity was assessed by: SLEDAI, 24 hr-proteinuria, circulating levels of complement C3, anti-double-stranded DNA (anti-dsDNA), ß2MG and various pro-inflammatory and anti-inflammatory cytokines (IL-6, IL-8, IL-10, IL-18) measured with a multiplex assay, IFN-α assessed with a reporter gene assay, and a combined expression score of 12 IFN-α inducible genes in peripheral blood mononuclear cells. Median serum levels of ß2MG were significantly higher in SLE patients vs controls (2.8 mg/L, range: 1.1-21.6 and 1.2 mg/L, range: 0.9-1.7, respectively, p < 0.001). ß2MG was correlated with SLEDAI score (R = 0.68, p < 0.001), 24 hr-proteinuria (R = 0.64, p < 0.001), and complement C3 (R = -0.52, p = 0.007). The cytokines were significantly correlated with ß2MG: IL-6 (R = 0.45, p = 0.02), IL-8 (R = 0.75, p < 0.001), IL-10 (R = 0.67, p < 0.001) and IL-18 (R = 0.71, p < 0.001) as were serum IFN-α (R = 0.45, p = 0.02) and the IFN-α inducible gene-score (R = 0.51, p = 0.01). The results support that ß2MG may serve as a marker of disease activity in SLE. The correlations with the measured cytokines indicate that increased ß2MG in SLE reflects immunological activity.