Association analysis of PON2 genetic variants with serum paraoxonase activity and systemic lupus erythematosus.

BACKGROUND: Low serum paraoxonase (PON) activity is associated with the risk of coronary artery disease, diabetes and systemic lupus erythematosus (SLE). Our prior studies have shown that the PON1/rs662 (p.Gln192Arg), PON1/rs854560 (p.Leu55Met), PON3/rs17884563 and PON3/rs740264 SNPs (single nucleotide polymorphisms) significantly affect serum PON activity. Since PON1, PON2 and PON3 share high degree of structural and functional properties, in this study, we examined the role of PON2 genetic variation on serum PON activity, risk of SLE and SLE-related clinical manifestations in a Caucasian case-control sample. METHODS: PON2 SNPs were selected from HapMap and SeattleSNPs databases by including at least one tagSNP from each bin defined in these resources. A total of nineteen PON2 SNPs were successfully genotyped in 411 SLE cases and 511 healthy controls using pyrosequencing, restriction fragment length polymorphism (RFLP) or TaqMan allelic discrimination methods. RESULTS: Our pair-wise linkage disequilibrium (LD) analysis, using an r² cutoff of 0.7, identified 14 PON2 tagSNPs that captured all 19 PON2 variants in our sample, 12 of which were not in high LD with known PON1 and PON3 SNP modifiers of PON activity. Stepwise regression analysis of PON activity, including the known modifiers, identified five PON2 SNPs [rs6954345 (p.Ser311Cys), rs13306702, rs987539, rs11982486, and rs4729189; P = 0.005 to 2.1 × 10⁻6] that were significantly associated with PON activity. We found no association of PON2 SNPs with SLE risk but modest associations were observed with lupus nephritis (rs11981433, rs17876205, rs17876183) and immunologic disorder (rs11981433) in SLE patients (P = 0.013 to 0.042). CONCLUSIONS: Our data indicate that PON2 genetic variants significantly affect variation in serum PON activity and have modest effects on risk of lupus nephritis and SLE-related immunologic disorder.

25-hydroxyvitamin D and cardiovascular risk factors in women with systemic lupus erythematosus.

OBJECTIVE: Low serum levels of 25-hydroxyvitamin D (25[OH]D; vitamin D) are associated with a higher frequency of cardiovascular disease and risk factors in the general population. Vitamin D deficiency has also been noted in systemic lupus erythematosus (SLE). The objective of this study was to evaluate the associations of serum 25(OH)D levels with cardiovascular risk factors in women with SLE. METHODS: Data collected in 181 women with SLE included demographics, SLE activity and damage assessments, cardiovascular risk factors, medications, and laboratory assessments of inflammatory markers and 25(OH)D levels. Multiple linear and logistic regressions were used to estimate the association of 25(OH)D levels with cardiovascular risk factors. RESULTS: The mean age and disease duration were 43.2 and 11.9 years, respectively. The mean 25(OH)D level was 27.1 ng/ml and 62.2% had 25(OH)D levels <30 ng/ml. In unadjusted analyses, lower 25(OH)D levels were significantly associated with higher diastolic blood pressure, low-density lipoprotein cholesterol, lipoprotein(a), body mass index (BMI), and fibrinogen levels, as well as self-reported hypertension and diabetes mellitus. Lower 25(OH)D levels were also significantly associated with higher SLE disease activity and damage scores. After adjustment for age, seasonal variation, and race/ethnicity, lower 25(OH)D levels were also significantly related to higher fasting serum glucose. With further adjustment for BMI, associations between 25(OH)D and cardiovascular risk factors were no longer significant. CONCLUSION: This study demonstrates that vitamin D levels are low in women with SLE and significant associations exist with selected cardiovascular risk factors, although most of these associations can be explained by BMI.

Apolipoprotein H promoter polymorphisms in relation to lupus and lupus-related phenotypes.

OBJECTIVE: Sequence variation in gene promoters is often associated with disease risk. We tested the hypothesis that common promoter variation in the APOH gene (encoding for ss(2)-glycoprotein I) is associated with systemic lupus erythematosus (SLE) risk and SLE-related clinical phenotypes in a Caucasian cohort. METHODS: We used a case-control design and genotyped 345 women with SLE and 454 healthy control women for 8 APOH promoter single-nucleotide polymorphisms (SNP; -1284C>G, -1219G>A, -1190G>C, -759A>G, -700C>A, -643T>C, -38G>A, and -32C>A).Association analyses were performed on single SNP and haplotypes. Haplotype analyses were performed using EH (Estimate Haplotype-frequencies) and Haploview programs. In vitro reporter gene assay was performed in COS-1 cells. Electrophoretic mobility shift assay (EMSA) was performed using HepG2 nuclear cells. RESULTS: Overall haplotype distribution of the APOH promoter SNP was significantly different between cases and controls (p = 0.009). The -643C allele was found to be protective against carotid plaque formation (adjusted OR 0.37, p = 0.013) among patients with SLE. The -643C allele was associated with a ~2-fold decrease in promoter activity as compared to wild-type -643T allele (mean +/- standard deviation: 3.94 +/- 0.05 vs 6.99 +/- 0.68, p = 0.016). EMSA showed that the -643T>C SNP harbors a binding site for a nuclear factor. The -1219G>A SNP showed a significant association with the risk of lupus nephritis (age-adjusted OR 0.36, p = 0.016). CONCLUSION: Our data indicate that APOH promoter variants may be involved in the etiology of SLE, especially the risk for autoimmune-mediated cardiovascular disease.

Differences in subclinical cardiovascular disease between African American and Caucasian women with systemic lupus erythematosus.

Racial differences exist in disease rates and mortality in both cardiovascular disease (CVD) and systemic lupus erythematosus (SLE). The objective of this cross-sectional study was to compare the frequency and risk factors for subclinical CVD in African American (AA) and Caucasian women with SLE and no prior CVD events. Traditional CVD risk factors and SLE-related factors were assessed in 309 SLE women. Subclinical CVD was assessed by carotid ultrasound to measure intimamedial thickness (IMT) and plaque, and electron beam computed tomography (EBCT) was used to measure coronary artery calcium (CAC). AA women had less education and higher levels of body mass index, blood pressure, lipoprotein(a), C-reactive protein (CRP), fibrinogen, and erythrocyte sedimentation rate (ESR). However, AA women had lower albumin, more and longer duration of corticosteroid use, higher SLE disease activity and damage, and more dsDNA antibodies compared with Caucasian women after adjustment for age and study site. More AA women had carotid plaque (adjusted odds ratio [OR], 1.94; 95% confidence interval [CI], 1.03-3.65) and higher carotid IMT (0.620 vs 0.605 mm, P = 0.07) but similar CAC compared with Caucasians. A multivariate analysis revealed that the following risk factor variables were significantly different between the racial groups and associated with plaque: blood pressure, current corticosteroid use, SLE disease activity, and SLE damage. All factors contributed to the result, but no individual risk factor fully accounted for the association between race and plaque. In conclusion, the presence of carotid plaque was higher in AA compared with Caucasian women with SLE, in contrast to studies of non-SLE subjects, in which AA have similar or less plaque than Caucasians. A combination of SLE-related and traditional CVD risk factors explained the racial difference in plaque burden.

Homocysteine, bone mineral density, and fracture risk over 2 years of followup in women with and without systemic lupus erythematosus.

OBJECTIVE: To examine the relationship of baseline homocysteine levels with bone mineral density (BMD) and incidence of fractures over 2 years in women with and without systemic lupus erythematosus (SLE). METHODS: Women with SLE (n = 100) and without SLE (n = 100) were matched according to age (+/- 5 yrs), race, and menopausal status. Data were collected from 1997 to 2004, including hip, lumbar spine (L-spine), and distal forearm BMD, serum homocysteine levels, and a self-administered questionnaire on osteoporosis risk factors, medications and symptomatic fractures at baseline and 2-year followup. Analyses were performed to compare homocysteine levels, BMD, and incident fractures and to evaluate the relationship of homocysteine with BMD and incident fractures in both groups. RESULTS: Mean homocysteine +/- SD was higher (p < 0.001) in women with SLE (9.88 +/- 3.8 micromol/l) than in women without SLE (7.98 +/- 2.6 micromol/l). Women with SLE had significantly lower L-spine BMD Z-scores, while hip BMD Z-scores and distal forearm BMD T-scores were nonsignificantly lower than in women without SLE. No significant correlations were observed between homocysteine and BMD in either group. Thirteen women with SLE experienced new fractures, while 4 women without SLE had new fractures over 2 years (p = 0.035); however, there was no association between homocysteine levels and incident fractures in either group. CONCLUSION: Women with SLE had significantly greater baseline homocysteine, lower L-spine BMD, and more new fractures over 2 years, compared with women without SLE. Homocysteine levels were not significantly associated with BMD and did not predict new fractures in women with or without SLE over 2 years.

Association study of Toll-like receptor 5 (TLR5) and Toll-like receptor 9 (TLR9) polymorphisms in systemic lupus erythematosus.

OBJECTIVE: Toll-like receptors (TLR) play an important role in both adaptive and innate immunity. Variations in TLR genes have been shown to be associated with various infectious and inflammatory diseases. We investigated the association of TLR5 (Arg392Stop, rs5744168) and TLR9 (-1237T-->C, rs5743836) single nucleotide polymorphisms (SNP) with systemic lupus erythematosus (SLE) in Caucasian American subjects. METHODS: We performed a case-control association study and genotyped 409 Caucasian women with SLE and 509 Caucasian healthy female controls using TaqMan allelic discrimination (rs5744168) or polymerase chain reaction-restriction fragment length polymorphism analysis (rs5743836). RESULTS: None of the 2 TLR SNP showed a statistically significant association with SLE risk in our cohort. CONCLUSION: Our results do not indicate a major influence of these putative functional TLR SNP on the susceptibility to (or protection from) SLE.

Premature atherosclerotic disease in systemic lupus erythematosus--role of inflammatory mechanisms.

Mounting evidence from a growing body of epidemiologic studies demonstrates that patients with systemic lupus erythematosus (SLE) are at increased risk for the development of premature cardiovascular disease (CVD). However, awareness of accelerated atherosclerosis in young SLE patients, albeit growing, is still limited, as documented by the brief case presented. Inflammation is thought to play an important role in both the pathogenesis of SLE, as well as atherosclerotic vascular disease. Inflammatory processes that are shared by SLE and atherosclerotic disease include immune complex deposition and fixation, autoantibody binding, complement activation and CD40-CD40 ligand interaction. By examining the inflammatory mechanisms in common between SLE and atherosclerotic disease, we can come to a better understanding of the pathophysiology of the accelerated atherosclerotic process seen in patients with SLE and can gain insights into developing and instituting preventative and treatment strategies. In this article, we present a case of a young woman with SLE who presents with chest pain, followed by a review of inflammation-based pathogenic mechanisms that are shared by SLE and atherosclerotic cardiovascular disease.

Scleroderma renal crisis: new insights and developments.

Scleroderma renal crisis (SRC) was once a uniformly fatal complication of systemic sclerosis (SSc). With the introduction of angiotensin-converting enzyme inhibitors as treatment, outcomes have improved significantly, though 39% to 50% of SSc patients who develop SRC continue to have poor outcomes, including permanent dialysis and death. Early recognition and treatment with angiotensin-converting enzyme inhibitors are important in the effective management of SRC, though given the continuing morbidity and mortality caused by SRC, they are clearly not sufficient. Newer therapies based on the pathophysiologic mechanisms underlying the development and perpetuation of SRC are needed. This article reviews the epidemiology, pathogenesis, risk factors, clinical features, and treatment of SRC, with an emphasis on recent insights and developments.

Sjogren's syndrome in association with Crohn's disease.

SUMMARY: Crohn's disease has many autoimmune extraintestinal manifestations, such as arthritis, polymyositis, and erythema nodosum. However, an association between Crohn's disease and Sjogren's syndrome, an autoimmune disease, has rarely been reported. We describe the fourth case of Sjogren's syndrome in association with Crohn's disease. The patient is a 43-year-old African-American female diagnosed with Crohn's disease in 1981. Twenty years later, she developed abdominal pain, arthralgias, and sicca symptoms. Further evaluation led to a diagnosis of Sjogren's syndrome. Sjogren's syndrome should be considered in patients with underlying Crohn's disease who develop a constellation of constitutional, joint, and sicca symptoms.