Genetic risk factors for thrombosis in systemic lupus erythematosus

OBJECTIVE

Thrombosis is a serious complication of systemic lupus erythematosus (SLE). We investigated whether genetic variants implicated in thrombosis pathways are associated with thrombosis among 2 ethnically diverse SLE cohorts.

METHODS

Our discovery cohort consisted of 1698 patients with SLE enrolled in the University of California, San Francisco, Lupus Genetics Project and our replication cohort included 1361 patients with SLE enrolled in the PROFILE cohort. Patients fulfilled American College of Rheumatology SLE criteria, and data relevant to thrombosis were available. Thirty-three single nucleotide polymorphisms (SNP) previously shown to be associated with risk of deep venous thrombosis in the general population or implicated in thrombosis pathways were genotyped and tested for association with thrombosis in bivariate allelic analyses. SNP with p < 0.1 in the bivariate analyses were further tested in multivariable logistic regression models adjusted for age, sex, disease duration, antiphospholipid antibody status, smoking, nephritis, and medications.

RESULTS

In the discovery cohort, 23% of patients with SLE experienced a thrombotic event. SNP in the following genes demonstrated association with thrombosis risk overall in the discovery or replication cohorts and were assessed using metaanalytic methods: factor V Leiden (FVL) rs6025 (OR 1.85, p = 0.02) and methylenetetrahydrofolate reductase (MTHFR) rs1801133 (OR 0.75, p = 0.04) in whites, and fibrinogen gamma (FGG) rs2066865 (OR 1.91, p = 0.01) in Hispanic Americans. SNP in these genes showed association with venous thrombosis risk in whites: MTHFR rs1801131 (OR 1.51, p = 0.01), MTHFR rs1801133 (OR 0.70, p = 0.04), FVL rs6025 (OR 2.69, p = 0.002), and FGG rs2066865 (OR 1.49, p = 0.02) in whites. A SNP in FGG rs2066865 (OR 2.19, p = 0.003) demonstrated association with arterial thrombosis risk in Hispanics.

CONCLUSION

Our results implicate specific genetic risk factors for thrombosis in patients with SLE and suggest that genetic risk for thrombosis differs across ethnic groups.

Association of discoid lupus erythematosus with clinical manifestations and damage accrual in a multiethnic lupus cohort

OBJECTIVE

To determine the clinical manifestations and disease damage associated with discoid rash in a large multiethnic systemic lupus erythematosus (SLE) cohort.

METHODS

SLE patients (per American College of Rheumatology [ACR] criteria) ages ≥16 years with a disease duration of ≤10 years at enrollment and defined ethnicity (African American, Hispanic, or white) from a longitudinal cohort were studied. Socioeconomic-demographic features, clinical manifestations, and disease damage (per the Systemic Lupus International Collaborating Clinics/ACR Damage Index) were determined. The association of discoid lupus erythematosus (DLE) with clinical manifestations and disease damage was examined using multivariable logistic regression.

RESULTS

A total of 2,228 SLE patients were studied. The mean ± SD age at diagnosis was 34.3 ± 12.8 years and the mean ± SD disease duration was 7.9 ± 6.0 years; 91.8% were women. DLE was observed in 393 patients with SLE (17.6%). In the multivariable analysis, patients with DLE were more likely to be smokers and of African American ethnicity and to have malar rash, photosensitivity, oral ulcers, leukopenia, and vasculitis. DLE patients were less likely to be of Hispanic (from Texas) ethnicity and to have arthritis, end-stage renal disease, and antinuclear, anti-double-stranded DNA, and antiphospholipid antibodies. Patients with DLE had more damage accrual, particularly chronic seizures, scarring alopecia, scarring of the skin, and skin ulcers.

CONCLUSION

In this cohort of SLE patients, DLE was associated with several clinical features, including serious manifestations such as vasculitis and chronic seizures.

Analysis of autosomal genes reveals gene-sex interactions and higher total genetic risk in men with systemic lupus erythematosus

OBJECTIVES

Systemic lupus erythematosus (SLE) is a sexually dimorphic autoimmune disease which is more common in women, but affected men often experience a more severe disease. The genetic basis of sexual dimorphism in SLE is not clearly defined. A study was undertaken to examine sex-specific genetic effects among SLE susceptibility loci.

METHODS

A total of 18 autosomal genetic susceptibility loci for SLE were genotyped in a large set of patients with SLE and controls of European descent, consisting of 5932 female and 1495 male samples. Sex-specific genetic association analyses were performed. The sex-gene interaction was further validated using parametric and non-parametric methods. Aggregate differences in sex-specific genetic risk were examined by calculating a cumulative genetic risk score for SLE in each individual and comparing the average genetic risk between male and female patients.

RESULTS

A significantly higher cumulative genetic risk for SLE was observed in men than in women. (P=4.52x10-8) A significant sex-gene interaction was seen primarily in the human leucocyte antigen (HLA) region but also in IRF5, whereby men with SLE possess a significantly higher frequency of risk alleles than women. The genetic effect observed in KIAA1542 is specific to women with SLE and does not seem to have a role in men.

CONCLUSIONS

The data indicate that men require a higher cumulative genetic load than women to develop SLE. These observations suggest that sex bias in autoimmunity could be influenced by autosomal genetic susceptibility loci.

Variation in the ICAM1-ICAM4-ICAM5 locus is associated with systemic lupus erythematosus susceptibility in multiple ancestries

OBJECTIVE

Systemic lupus erythematosus (SLE; OMIM 152700) is a chronic autoimmune disease for which the aetiology includes genetic and environmental factors. ITGAM, integrin α(M) (complement component 3 receptor 3 subunit) encoding a ligand for intracellular adhesion molecule (ICAM) proteins, is an established SLE susceptibility locus. This study aimed to evaluate the independent and joint effects of genetic variations in the genes that encode ITGAM and ICAM.

METHODS

The authors examined several markers in the ICAM1-ICAM4-ICAM5 locus on chromosome 19p13 and the single ITGAM polymorphism (rs1143679) using a large-scale case-control study of 17 481 unrelated participants from four ancestry populations. The single-marker association and gene-gene interaction were analysed for each ancestry, and a meta-analysis across the four ancestries was performed.

RESULTS

The A-allele of ICAM1-ICAM4-ICAM5 rs3093030, associated with elevated plasma levels of soluble ICAM1, and the A-allele of ITGAM rs1143679 showed the strongest association with increased SLE susceptibility in each of the ancestry populations and the trans-ancestry meta-analysis (OR(meta)=1.16, 95% CI 1.11 to 1.22; p=4.88×10(-10) and OR(meta)=1.67, 95% CI 1.55 to 1.79; p=3.32×10(-46), respectively). The effect of the ICAM single-nucleotide polymorphisms (SNPs) was independent of the effect of the ITGAM SNP rs1143679, and carriers of both ICAM rs3093030-AA and ITGAM rs1143679-AA had an OR of 4.08 compared with those with no risk allele in either SNP (95% CI 2.09 to 7.98; p=3.91×10(-5)).

CONCLUSION

These findings are the first to suggest that an ICAM-integrin-mediated pathway contributes to susceptibility to SLE.

Effect of hydroxychloroquine treatment on pro-inflammatory cytokines and disease activity in SLE patients: data from LUMINA (LXXV), a multiethnic US cohort

OBJECTIVE

We sought to determine the effect of hydroxychloroquine therapy on the levels proinflammatory/prothrombotic markers and disease activity scores in patients with systemic lupus erythematosus (SLE) in a multiethnic, multi-center cohort (LUMINA).

METHODS

Plasma/serum samples from SLE patients (n = 35) were evaluated at baseline and after hydroxychloroquine treatment. Disease activity was assessed using SLAM-R scores. Interferon (IFN)-α2, interleukin (IL)-1β, IL-6, IL-8, inducible protein (IP)-10, monocyte chemotactic protein-1, tumor necrosis factor (TNF)-α and soluble CD40 ligand (sCD40L) levels were determined by a multiplex immunoassay. Anticardiolipin antibodies were evaluated using ELISA assays. Thirty-two frequency-matched plasma/serum samples from healthy donors were used as controls.

RESULTS

Levels of IL-6, IP-10, sCD40L, IFN-α and TNF-α were significantly elevated in SLE patients versus controls. There was a positive but moderate correlation between SLAM-R scores at baseline and levels of IFN-α (p = 0.0546). Hydroxychloroquine therapy resulted in a significant decrease in SLAM-R scores (p = 0.0157), and the decrease in SLAM-R after hydroxychloroquine therapy strongly correlated with decreases in IFN-α (p = 0.0087).

CONCLUSIONS

Hydroxychloroquine therapy resulted in significant clinical improvement in SLE patients, which strongly correlated with reductions in IFN-α levels. This indicates an important role for the inhibition of endogenous TLR activation in the action of hydroxychloroquine in SLE and provides additional evidence for the importance of type I interferons in the pathogenesis of SLE. This study underscores the use of hydroxychloroquine in the treatment of SLE.

Evidence for gene-gene epistatic interactions among susceptibility loci for systemic lupus erythematosus

OBJECTIVE

Several confirmed genetic susceptibility loci for lupus have been described. To date, no clear evidence for genetic epistasis in lupus has been established. The aim of this study was to test for gene-gene interactions in a number of known lupus susceptibility loci.

METHODS

Eighteen single-nucleotide polymorphisms tagging independent and confirmed lupus susceptibility loci were genotyped in a set of 4,248 patients with lupus and 3,818 normal healthy control subjects of European descent. Epistasis was tested by a 2-step approach using both parametric and nonparametric methods. The false discovery rate (FDR) method was used to correct for multiple testing.

RESULTS

We detected and confirmed gene-gene interactions between the HLA region and CTLA4, IRF5, and ITGAM and between PDCD1 and IL21 in patients with lupus. The most significant interaction detected by parametric analysis was between rs3131379 in the HLA region and rs231775 in CTLA4 (interaction odds ratio 1.19, Z = 3.95, P = 7.8 × 10(-5) [FDR ≤0.05], P for multifactor dimensionality reduction = 5.9 × 10(-45)). Importantly, our data suggest that in patients with lupus, the presence of the HLA lupus risk alleles in rs1270942 and rs3131379 increases the odds of also carrying the lupus risk allele in IRF5 (rs2070197) by 17% and 16%, respectively (P = 0.0028 and P = 0.0047, respectively).

CONCLUSION

We provide evidence for gene-gene epistasis in systemic lupus erythematosus. These findings support a role for genetic interaction contributing to the complexity of lupus heritability.

Long-term membranous glomerulonephritis as the presenting manifestation of systemic lupus erythematosus in a patient with human immunodeficiency virus infection

The coexistence of human immunodeficiency virus (HIV) infection and systemic lupus erythematosus (SLE) is unusual, but the occurrence of SLE after HIV infection is even less common. Both conditions share similar clinical features including constitutional symptoms, facial rash, oral ulcers, alopecia, arthralgias, arthritis, seizures, cytopenias, glomerulonephritis, and antinuclear and antiphospholipid antibodies. This clinical overlap makes the diagnosis of SLE in a patient with pre-existing HIV infection difficult. Furthermore, immune complex glomerulonephritis with features resembling lupus nephritis has been described in HIV-positive patients. We present the case of a 45-year-old Hispanic woman with long-standing HIV infection who developed membranous glomerulonephritis with histological features of lupus nephritis. Five years after onset of renal disease she developed clinically evident SLE.

Evaluation of TRAF6 in a large multiancestral lupus cohort

OBJECTIVE

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease with significant immune system aberrations resulting from complex heritable genetics as well as environmental factors. We undertook to study the role of TRAF6 as a candidate gene for SLE, since it plays a major role in several signaling pathways that are important for immunity and organ development.

METHODS

Fifteen single-nucleotide polymorphisms (SNPs) across TRAF6 were evaluated in 7,490 SLE patients and 6,780 control subjects from different ancestries. Population-based case-control association analyses and meta-analyses were performed. P values, false discovery rate q values, and odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated.

RESULTS

Evidence of associations was detected in multiple SNPs. The best overall P values were obtained for SNPs rs5030437 and rs4755453 (P = 7.85 × 10(-5) and P = 4.73 × 10(-5) , respectively) without significant heterogeneity among populations (P = 0.67 and P = 0.50, respectively, in Q statistic). In addition, SNP rs540386, which was previously reported to be associated with rheumatoid arthritis (RA), was found to be in linkage disequilibrium with these 2 SNPs (r(2) = 0.95) and demonstrated evidence of association with SLE in the same direction (meta-analysis P = 9.15 × 10(-4) , OR 0.89 [95% CI 0.83-0.95]). The presence of thrombocytopenia improved the overall results in different populations (meta-analysis P = 1.99 × 10(-6) , OR 0.57 [95% CI 0.45-0.72], for rs5030470). Finally, evidence of family-based association in 34 African American pedigrees with the presence of thrombocytopenia was detected in 1 available SNP (rs5030437) with a Z score magnitude of 2.28 (P = 0.02) under a dominant model.

CONCLUSION

Our data indicate the presence of association of TRAF6 with SLE, consistent with the previous report of association with RA. These data provide further support for the involvement of TRAF6 in the pathogenesis of autoimmunity.

Identification of novel genetic susceptibility loci in African American lupus patients in a candidate gene association study

OBJECTIVE

Candidate gene and genome-wide association studies have identified several disease susceptibility loci in lupus patients. These studies have largely been performed in lupus patients who are Asian or of European ancestry. This study was undertaken to examine whether some of these same susceptibility loci increase lupus risk in African American individuals.

METHODS

Single-nucleotide polymorphisms tagging 15 independent lupus susceptibility loci were genotyped in a set of 1,724 lupus patients and 2,024 healthy controls of African American descent. The loci examined included PTPN22, FCGR2A, TNFSF4, STAT4, CTLA4, PDCD1, PXK, BANK1, MSH5 (HLA region), CFB (HLA region), C8orf13-BLK region, MBL2, KIAA1542, ITGAM, and MECP2/IRAK1.

RESULTS

We found the first evidence of genetic association between lupus in African American patients and 5 susceptibility loci (C8orf13-BLK, BANK1, TNFSF4, KIAA1542, and CTLA4; P = 8.0 × 10⁻⁶, P = 1.9 × 10⁻⁵, P = 5.7 × 10⁻⁵, P = 0.00099, and P = 0.0045, respectively). Further, we confirmed the genetic association between lupus and 5 additional lupus susceptibility loci (ITGAM, MSH5, CFB, STAT4, and FCGR2A; P = 7.5 × 10⁻¹¹, P = 5.2 × 10⁻⁸, P = 8.7 × 10⁻⁷ , P = 0.0058, and P = 0.0070, respectively), and provided evidence, for the first time, of genome-wide significance for the association between lupus in African American patients and ITGAM and MSH5 (HLA region).

CONCLUSION

These findings provide evidence of novel genetic susceptibility loci for lupus in African Americans and demonstrate that the majority of lupus susceptibility loci examined confer lupus risk across multiple ethnicities.

Phenotypic associations of genetic susceptibility loci in systemic lupus erythematosus

OBJECTIVE

Systemic lupus erythematosus is a clinically heterogeneous autoimmune disease. A number of genetic loci that increase lupus susceptibility have been established. This study examines if these genetic loci also contribute to the clinical heterogeneity in lupus.

MATERIALS AND METHODS

4001 European-derived, 1547 Hispanic, 1590 African-American and 1191 Asian lupus patients were genotyped for 16 confirmed lupus susceptibility loci. Ancestry informative markers were genotyped to calculate and adjust for admixture. The association between the risk allele in each locus was determined and compared in patients with and without the various clinical manifestations included in the ACR criteria.

RESULTS

Renal disorder was significantly correlated with the lupus risk allele in ITGAM (p=5.0 × 10(-6), OR 1.25, 95% CI 1.12 to 1.35) and in TNFSF4 (p=0.0013, OR 1.14, 95% CI 1.07 to 1.25). Other significant findings include the association between risk alleles in FCGR2A and malar rash (p=0.0031, OR 1.11, 95% CI 1.17 to 1.33), ITGAM and discoid rash (p=0.0020, OR 1.20, 95% CI 1.06 to 1.33), STAT4 and protection from oral ulcers (p=0.0027, OR 0.89, 95% CI 0.83 to 0.96) and IL21 and haematological disorder (p=0.0027, OR 1.13, 95% CI 1.04 to 1.22). All these associations are significant with a false discovery rate of <0.05 and pass the significance threshold using Bonferroni correction for multiple testing.

CONCLUSION

Signifi cant associations were found between clinical manifestations and the FCGR2A, ITGAM, STAT4, TNSF4 and IL21 genes. The findings suggest that genetic profiling might be a useful tool to predict disease manifestations in lupus patients in the future.

Association of PPP2CA polymorphisms with systemic lupus erythematosus susceptibility in multiple ethnic groups

OBJECTIVE

T cells from patients with systemic lupus erythematosus (SLE) express increased amounts of PP2Ac, which contributes to decreased production of interleukin-2 (IL-2). Because IL-2 is important in the regulation of several aspects of the immune response, it has been proposed that PP2Ac contributes to the expression of SLE. This study was designed to determine whether genetic variants of PPP2AC are linked to the expression of SLE and specific clinical manifestations and account for the increased expression of PP2Ac.

METHODS

We conducted a trans-ethnic study of 8,695 SLE cases and 7,308 controls of 4 different ancestries. Eighteen single-nucleotide polymorphisms (SNPs) across PPP2CA were genotyped using an Illumina custom array. PPP2CA expression in SLE and control T cells was analyzed by real-time polymerase chain reaction.

RESULTS

A 32-kb haplotype comprising multiple SNPs of PPP2CA showed significant association with SLE in Hispanic Americans, European Americans, and Asians, but not in African Americans. Conditional analyses revealed that SNP rs7704116 in intron 1 showed consistently strong association with SLE across Asian, European American, and Hispanic American populations (odds ratio 1.3 [95% confidence interval 1.14-1.31], meta-analysis P=3.8×10(-7)). In European Americans, the largest ethnic data set studied, the risk A allele of rs7704116 was associated with the presence of renal disease, anti-double-stranded DNA, and anti-RNP antibodies. PPP2CA expression was ∼2-fold higher in SLE patients carrying the rs7704116 AG genotype than those carrying the GG genotype (P=0.007).

CONCLUSION

Our data provide the first evidence of an association between PPP2CA polymorphisms and elevated PP2Ac transcript levels in T cells, which implicates a new molecular pathway for SLE susceptibility in European Americans, Hispanic Americans, and Asians.

Fine-mapping and transethnic genotyping establish IL2/IL21 genetic association with lupus and localize this genetic effect to IL21

OBJECTIVE

Genetic association of the IL2/IL21 region at chromosome 4q27 has previously been reported in lupus and a number of autoimmune and inflammatory diseases. This study was undertaken to determine whether this genetic effect could be localized, using a very large cohort of lupus patients and controls.

METHODS

We genotyped 45 tag single-nucleotide polymorphisms (SNPs) across the IL2/IL21 locus in 2 large independent lupus sample sets. We studied a set of subjects of European descent consisting of 4,248 lupus patients and 3,818 healthy controls, and an African American set of 1,569 patients and 1,893 healthy controls. Imputation in 3,004 additional controls from the Wellcome Trust Case Control Consortium was also performed. Genetic association between the genotyped markers was determined, and pairwise conditional analysis was performed to localize the independent genetic effect in the IL2/IL21 locus in lupus.

RESULTS

We established and confirmed the genetic association between IL2/IL21 and lupus. Using conditional analysis and transethnic mapping, we localized the genetic effect in this locus to 2 SNPs in high linkage disequilibrium: rs907715 located within IL21 (odds ratio 1.16 [95% confidence interval 1.10-1.22], P=2.17×10(-8)) and rs6835457 located in the 3'-untranslated flanking region of IL21 (odds ratio 1.11 [95% confidence interval 1.05-1.17], P=9.35×10(-5)).

CONCLUSION

Our findings establish the genetic association between lupus and IL2/IL21 with a genome-wide level of significance. Further, our findings indicate that this genetic association within the IL2/IL21 linkage disequilibrium block is localized to IL21. If other autoimmune IL2/IL21 genetic associations are similarly localized, then the IL21 risk alleles would be predicted to operate by a fundamental mechanism that influences the course of a number of autoimmune disease processes.

Genetic analyses of interferon pathway-related genes reveal multiple new loci associated with systemic lupus erythematosus

OBJECTIVE

The overexpression of interferon (IFN)-inducible genes is a prominent feature of systemic lupus erythematosus (SLE); it serves as a marker for active and more severe disease, and is also observed in other autoimmune and inflammatory conditions. This study was undertaken to investigate the genetic variations responsible for sustained activation of IFN-responsive genes in SLE.

METHODS

We systematically evaluated association of SLE with a total of 1,754 IFN pathway-related genes, including IFN-inducible genes known to be differentially expressed in SLE patients and their direct regulators. We used a 3-stage study design in which 2 cohorts (total of 939 SLE cases and 3,398 controls) were analyzed independently and jointly for association with SLE, and the results were adjusted for the number of comparisons.

RESULTS

A total of 15,166 single-nucleotide polymorphisms (SNPs) passed all quality control filters; 305 of these SNPs demonstrated replicated association with SLE in both cohorts. Nine variants were further genotyped for confirmation in an average of 1,316 independent SLE cases and 3,215 independent controls. Association with SLE was confirmed for several genes, including those for the transmembrane receptor CD44 (CD44 [rs507230]; P = 3.98 × 10⁻¹²), the cytokine pleiotrophin (PTN [rs919581]; P = 5.38 × 10⁻⁴), the heat-shock protein DnaJ (DNAJA1 [rs10971259]; P = 6.31 × 10⁻³), and the nuclear import protein karyopherin α1 (KPNA [rs6810306]; P = 4.91 × 10⁻²).

CONCLUSION

This study expands the number of candidate genes that have been shown to be associated with SLE and highlights potential of pathway-based approaches for gene discovery. Identification of the causal alleles will help elucidate the molecular mechanisms responsible for activation of the IFN system in SLE.

Association of genetic variants in complement factor H and factor H-related genes with systemic lupus erythematosus susceptibility

Systemic lupus erythematosus (SLE), a complex polygenic autoimmune disease, is associated with increased complement activation. Variants of genes encoding complement regulator factor H (CFH) and five CFH-related proteins (CFHR1-CFHR5) within the chromosome 1q32 locus linked to SLE, have been associated with multiple human diseases and may contribute to dysregulated complement activation predisposing to SLE. We assessed 60 SNPs covering the CFH-CFHRs region for association with SLE in 15,864 case-control subjects derived from four ethnic groups. Significant allelic associations with SLE were detected in European Americans (EA) and African Americans (AA), which could be attributed to an intronic CFH SNP (rs6677604, in intron 11, P_meta = 6.6×10⁻⁸, OR = 1.18) and an intergenic SNP between CFHR1 and CFHR4 (rs16840639, P_meta = 2.9×10⁻⁷, OR = 1.17) rather than to previously identified disease-associated CFH exonic SNPs, including I62V, Y402H, A474A, and D936E. In addition, allelic association of rs6677604 with SLE was subsequently confirmed in Asians (AS). Haplotype analysis revealed that the underlying causal variant, tagged by rs6677604 and rs16840639, was localized to a ∼146 kb block extending from intron 9 of CFH to downstream of CFHR1. Within this block, the deletion of CFHR3 and CFHR1 (CFHR3-1Δ), a likely causal variant measured using multiplex ligation-dependent probe amplification, was tagged by rs6677604 in EA and AS and rs16840639 in AA, respectively. Deduced from genotypic associations of tag SNPs in EA, AA, and AS, homozygous deletion of CFHR3-1Δ (P_meta = 3.2×10⁻⁷, OR = 1.47) conferred a higher risk of SLE than heterozygous deletion (P_meta = 3.5×10⁻⁴, OR = 1.14). These results suggested that the CFHR3-1Δ deletion within the SLE-associated block, but not the previously described exonic SNPs of CFH, might contribute to the development of SLE in EA, AA, and AS, providing new insights into the role of complement regulators in the pathogenesis of SLE.

Systemic lupus erythematosus (SLE) is a complex autoimmune disease, associated with increased complement activation. Previous studies have provided evidence for the presence of SLE susceptibility gene(s) in the chromosome 1q31-32 locus. Within 1q32, genes encoding complement regulator factor H (CFH) and five CFH-related proteins (CFHR1-CFHR5) may contribute to the development of SLE, because genetic variants of these genes impair complement regulation and predispose to various human diseases. In this study, we tested association of genetic variants in the region containing CFH and CFHRs with SLE. We identified genetic variants predisposing to SLE in European American, African American, and Asian populations, which might be attributed to the deletion of CFHR3 and CFHR1 genes but not previously identified disease-associated exonic variants of CFH. This study provides the first evidence for consistent association between CFH/CFHRs and SLE across multi-ancestral SLE datasets, providing new insights into the role of complement regulators in the pathogenesis of SLE.

Factors predictive of thrombotic events in LUMINA, a multi-ethnic cohort of SLE patients (LXXII)

OBJECTIVE

Thrombosis is an important cause of morbidity and mortality in SLE. We have explored the factors associated with time to the occurrence of thrombotic events in SLE patients to expand our cohort's previous observations.

METHOD

SLE patients (ACR criteria), age >or=16 years, disease duration

RESULTS

A total of 643 patients were studied; mean (s.d.) age was 36.4 (12.6) years and disease duration at T0 was 1.4 (1.3) years; 90% were female. After T0, 81 (12.6%) patients had developed a thrombotic event. In the MV model, age [hazard ratio (HR) = 1.06; 95% CI 1.03, 1.08; P < 0.0001], health insurance (HR = 0.53; 95% CI 0.30, 0.94; P = 0.029), smoking (HR = 1.85; 95% CI 1.01, 3.40; P = 0.048), damage (T0) (HR = 1.44; 95% CI 1.20, 1.71; P < 0.0001), aPL (HR = 2.12; 95% CI 1.19, 3.76; P = 0.011) and glucocorticoid (highest dose) (HR = 1.01; 95% CI 1.01, 1.02; P < 0.0001) were significant.

CONCLUSIONS

Age, poverty, smoking, damage accrual, aPL and higher doses of glucocorticoids were independently associated with a shorter time to the first thrombotic event; health insurance had a protective effect. Acting upon modifiable risk factors at the personal (smoking, high-dose glucocorticoids) and societal (poverty, health insurance) levels may prevent these events and improve the long-term outcome of SLE patients.

Collapse

Key Words

• systemic lupus erythematosus
• thrombotic events
• risk factors

Collapse

MESH Headings

• Adult
• Black or African American
• Female
• Hispanic or Latino
• Humans
• Longitudinal Studies
• Lupus Erythematosus, Systemic/complications
• Lupus Erythematosus, Systemic/ethnology
• Lupus Erythematosus, Systemic/mortality
• Male
• Middle Aged
• Proportional Hazards Models
• Risk Factors
• Severity of Illness Index
• Socioeconomic Factors
• Thrombosis/ethnology
• Thrombosis/etiology
• Thrombosis/mortality
• United States
• White People
• Young Adult

Collapse

Grants

• P20 RR011126 NCRR NIH HHS
• P01 AR049084 NIAMS NIH HHS
• M01-RR00032 NCRR NIH HHS
• P01 AR49084 NIAMS NIH HHS
• M01-RR02558 NCRR NIH HHS
• M01 RR002558 NCRR NIH HHS
• 1P20RR11126 NCRR NIH HHS
• M01 RR000032 NCRR NIH HHS

Collapse

Is familial lupus different from sporadic lupus? Data from LUMINA (LXXIII), a multiethnic US cohort

The aim of this study was to characterize the clinical features of familial lupus, and determine its influence on damage accrual and survival using data from LUMINA, a longitudinal multiethnic US cohort. Familial lupus was defined as patients with a first-degree relative with systemic lupus erythematosus. Relative risks were estimated by logistic regression; odds ratios (ORs) and their 95% confidence intervals (CIs) were the measure of association for familial lupus. Hazard ratios were calculated using Cox proportional hazards adjusted for potential confounders for damage and survival. Of 644 patients, 32 had familial and 612 had sporadic lupus; both groups were of comparable age (~36 years). Patients with familial lupus were, in decreasing order of frequency, siblings, parents and children. In multivariable analyses, mucosal ulcers (OR = 1.92, 95% CI 0.65-5.70), mitral valve prolapse (OR = 1.74, 95% CI 0.50-6.10), cerebrovascular disease (OR = 4.18, 95% CI 0.98-17.76) and oral contraceptive use (ever/never; OR = 2.51, 95% CI 0.88-7.19) were more likely in familial lupus, but a history of low platelet count (<150,000/mm(3); OR=0.31, 95% CI 0.08-1.17) and pulmonary disease activity (OR=0.39, 95% CI 0.14-1.20) were less likely. However, none of these associations reached statistical significance. Familial lupus was not significantly associated with a shorter time to either damage accrual or death (HR = 0.77, 95% CI 0.37-1.59, p = 0.4746 and HR = 0.20, 95% CI 0.03-1.47, p = 0.2020, respectively). We conclude that although some clinical differences were observed between patients with familial and sporadic lupus, familial lupus was not associated with a significantly greater disease burden (damage, survival) than sporadic lupus.

The non-muscle Myosin heavy chain 9 gene (MYH9) is not associated with lupus nephritis in African Americans

BACKGROUND

African Americans (AA) disproportionately develop lupus nephritis (LN) relative to European Americans and familial clustering supports causative genes. Since MYH9 underlies approximately 40% of end-stage renal disease (ESRD) in AA, we tested for genetic association with LN.

METHODS

Seven MYH9 single nucleotide polymorphisms (SNPs) and the E1 risk haplotype were tested for association with LN in three cohorts of AA.

RESULTS

A preliminary analysis revealed that the MYH9 E1 risk haplotype was associated with ESRD in 25 cases with presumed systemic lupus erythematosus (SLE)-associated ESRD, compared to 735 non-SLE controls (odds ratio 3.1; p = 0.010 recessive). Replication analyses were performed in 583 AA with SLE in the PROFILE cohort (318 with LN; 265 with SLE but without nephropathy) and 60 AA from the NIH (39 with LN; 21 with SLE but without nephropathy). Analysis of the NIH and larger PROFILE cohorts, as well as a combined analysis, did not support this association.

CONCLUSIONS

These results suggest that AA with ESRD and coincident SLE who were recruited from dialysis clinics more likely have kidney diseases in the MYH9-associated spectrum of focal segmental glomerulosclerosis. PROFILE and NIH participants, recruited from rheumatology practices, demonstrate that MYH9 does not contribute substantially to the development of LN in AA.

Possible protective effect of hydroxychloroquine on delaying the occurrence of integument damage in lupus: LXXI, data from a multiethnic cohort

OBJECTIVE

To determine the features predictive of time to integument damage in patients with systemic lupus erythematosus (SLE) from a multiethnic cohort (LUpus in MInorities, NAture versus nurture [LUMINA]).

METHODS

LUMINA SLE patients (n = 580) age > or =16 years, with a disease duration of < or =5 years at baseline (T0), of African American, Hispanic, and Caucasian ethnicity were studied. Integument damage was defined per the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (scarring alopecia, extensive skin scarring, and skin ulcers lasting at least 6 months); factors associated with time to its occurrence were examined by Cox proportional univariable and multivariable (main model) hazards regression analyses. Two alternative models were also examined: in model 1, all patients, regardless of when integument damage occurred (n = 94), were included; in model 2, a time-varying approach (generalized estimating equation) was employed.

RESULTS

Thirty-nine (6.7%) of 580 patients developed integument damage over a mean +/- SD total disease duration of 5.9 +/- 3.7 years, and were included in the main multivariable regression model. After adjusting for discoid rash, nailfold infarcts, photosensitivity, and Raynaud's phenomenon (significant in the univariable analyses), disease activity over time (hazard ratio [HR] 1.17, 95% confidence interval [95% CI] 1.09-1.26) was associated with a shorter time to integument damage, whereas hydroxychloroquine use (HR 0.23, 95% CI 0.12-0.47) and Texan-Hispanic (HR 0.35, 95% CI 0.14-0.87) and Caucasian ethnicities (HR 0.37, 95% CI 0.14-0.99) were associated with a longer time. Results of the alternative models were consistent with those of the main model, although in model 2, the association with hydroxychloroquine was not significant.

CONCLUSION

Our data indicate that hydroxychloroquine use is possibly associated with a delay in integument damage development in patients with SLE.

Predictors of the rate of change in disease activity over time in LUMINA, a multiethnic US cohort of patients with systemic lupus erythematosus: LUMINA LXX

The objectives of the present study were (1) to clarify and quantify the relationship between age and disease duration with the rate of change in disease activity over time in patients with systemic lupus erythematosus (SLE) and (2) to explore other possible factors associated with this rate of change. To this end, SLE patients from LUMINA were studied if they had at least three visits in which disease activity (Systemic Lupus Activity Measure-Revised [SLAM-R]) had been ascertained. Variables associated with the rate (slope) of change in disease activity (obtained by regressing the SLAM-R score against the length of time from diagnosis to visit date) were examined by univariable and multivariable analyses. Five hundred and forty two of the 632 patients had at least three SLAM-R score. In multivariable analyses, Whites exhibited the fastest decline in disease activity, Texan Hispanics exhibited the slowest, trailed by the African Americans. Longer disease duration and HLA-DRB1*1503 positivity were associated with a slower decline whereas a greater number of American College of Rheumatology criteria and abnormal laboratory parameters (white blood cell counts, hematocrit and serum creatinine) were associated with a faster decline. These findings complement existing knowledge on SLE disease activity and are potentially useful to clinicians managing these patients.

Validation of the Spanish, Portuguese and French versions of the Lupus Damage Index questionnaire: data from North and South America, Spain and Portugal

We have previously developed and validated a self-administered questionnaire, modelled after the Systemic Lupus International Collaborating Clinics Damage Index (SDI), the Lupus Damage Index Questionnaire (LDIQ), which may allow the ascertainment of this construct in systemic lupus erythematosus (SLE) patients followed in the community and thus expand observations made about damage. We have now translated, back-translated and adapted the LDIQ to Spanish, Portuguese and French and applied it to patients followed at academic and non-academic centres in North and South America, Portugal and Spain while their physicians scored the SDI. A total of 887 patients (659 Spanish-speaking, 140 Portuguese-speaking and 80 French-speaking patients) and 40 physicians participated. Overall, patients scored all LDIQ versions higher than their physicians (total score and all domains). Infrequent manifestations had less optimal clinimetric properties but overall agreement was more than 95% for the majority of items. Higher correlations were observed among the Spanish-speaking patients than the Portuguese-speaking and French-speaking patients; further adjustments may be needed before the Portuguese and French versions of the LDIQ are applied in community-based studies. The relationship between the LDIQ and other outcome parameters is currently being investigated in a different patient sample.

Factors associated with arterial vascular events in PROFILE: a Multiethnic Lupus Cohort

The objective of this study was to determine the factors associated with the occurrence of arterial vascular events in a multiethnic systemic lupus erythematosus (SLE) cohort. The PROFILE cohort, comprised SLE patients (n = 1333) of defined ethnicity from five different US institutions, was studied to determine demographic, clinical and biological variables associated with vascular events. An arterial vascular event (first episode) was either a myocardial infarction, angina pectoris and/or a vascular procedure for myocardial infarction, stroke, claudication and/or evidence of gangrene. Patient characteristics were analyzed by univariable and multivariable Cox proportional hazards regression analyses. One-hundred twenty-three (9.8%) patients had at least one incident arterial event. Age at cohort enrollment (HR = 1.04, 95% CI 1.03-1.06), smoking (HR = 2.20, 95% CI 1.40-3.46) and the CRP2* C alleles (HR = 1.91, 95% CI 1.04-3.49) were associated with a shorter time-to-the occurrence of arterial vascular events. Some clinical manifestations of disease activity were associated with a shorter time-to-occurrence [psychosis (HR = 2.21, 95% CI 1.10-4.44), seizures (HR = 1.85, 95% CI 1.00-3.24) and anaemia (HR = 1.83, 95% CI 1.02-3.31)], but others were not [arthritis (HR = 0.32, 95% CI 0.18-0.58)]. In conclusion, older patients, especially in the context of a predisposing environmental factor (smoking) and severe clinical manifestations, are at higher risk of having arterial vascular events. The genetic contribution of the variation at the CRP locus was not obscured by demographic or clinical variables. Awareness of these factors should lead to more effective management strategies of patients at risk for arterial vascular events.

Impact of age on clinical manifestations and outcome in Puerto Ricans with rheumatoid arthritis

INTRODUCTION

Disease expression and outcomes in rheumatoid arthritis (RA) vary among different ethnic groups. There are limited data on the impact of age on disease severity and outcomes among Hispanics. Thus, we determined the demographic characteristics, clinical manifestations, comorbidities, pharmacologic profile, and functional status among Puerto Ricans with RA of different age groups.

METHODS

A cross-sectional study was conducted in 214 Puerto Rican patients with RA (per American College of Rheumatology classification criteria). Demographic features, health-related behaviors, cumulative RA manifestations, treatment profiles, disease activity (Disease Activity Score 28), comorbid conditions, and functional status (Health Assessment Questionnaire) were determined at study visit. Three age groups were studied: <40, 40-59, and > or =60 years. Data were examined using univariable and multivariable (logistic regression) analyses.

RESULTS

The mean (SD) age of the study population was 56.5 (13.6) years with a mean disease duration (SD) of 10.8 (9.7) years; 180 patients (84.1%) were women. In the multivariable analyses, patients aged > or =60 years were more likely to have joint deformities, extra-articular manifestations, and comorbidities such as dyslipidemia, arterial hypertension, diabetes mellitus, vascular events, osteoarthritis, low back pain, and osteoporosis. In addition, older patients used corticosteroids more frequently. No differences were found for the use of disease-modifying anti-rheumatic drugs or biologic agents.

CONCLUSIONS

Puerto Rican RA patients aged > or =60 years present a severe type of disease having more joint damage, extra-articular manifestations, and comorbidities than younger patients. These disparities must be considered when establishing effective therapy for older RA patients.