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Objective.Rheumatoid arthritis (RA) is associated with low muscle mass and density. The objective of our study was to evaluate associations between 2 serum biomarkers [insulin-like growth factor 1 (IGF-1) and adiponectin] and skeletal muscle in RA.Methods.Whole-body dual energy X-ray absorptiometry measures of the appendicular lean mass index (ALMI; kg/m2) and total fat mass index (kg/m2), as well as the peripheral quantitative computed tomography measures of the lower leg muscle and fat cross-sectional area (CSA; cm2) and muscle density (an index of fat infiltration) were obtained from 50 participants with RA, ages 18–70 years. Multivariable linear regression analyses evaluated associations between body composition and levels of adiponectin and IGF-1, adjusted for age, sex, and adiposity.Results.Greater age was associated with higher adiponectin (p = 0.06) and lower IGF-1 (p = 0.004). Eight subjects had IGF-1 levels below the reference range for their age and sex. These subjects had significantly lower ALMI and muscle CSA in multivariable models. Lower IGF-1 levels were associated with greater clinical disease activity and severity, as well as low ALMI, muscle CSA, and muscle density (defined as 1 SD below normative mean). After adjusting for age and sex, greater adiponectin levels were associated with lower BMI (p = 0.02) as well as lower ALMI, and lower muscle CSA, independent of adiposity (p < 0.05). Only greater Health Assessment Questionnaire scores were significantly associated with lower adiponectin levels.Conclusion.Low IGF-1 and greater adiponectin levels are associated with lower muscle mass in RA. Lower IGF-1 levels were seen in subjects with greater disease activity and severity.

Objective.To evaluate levels of resistin in female subjects with systemic lupus erythematosus (SLE) compared to age and race-matched controls and to determine the relationship between resistin and systemic inflammation, disease measures, and coronary artery calcification (CAC).Methods.Resistin levels were measured on stored samples from 159 women with SLE and 70 controls as an extension of a previous cross-sectional study. Spearman correlations and multivariable regressions were used to examine whether resistin levels were associated with SLE, disease-specific and inflammatory markers, insulin resistance, and CAC.Results.In a multivariable linear regression model, a diagnosis of SLE was significantly associated with higher resistin levels independent of age, race, renal function, body mass index (BMI), high-sensitivity CRP (hsCRP), hypertension, diabetes, and steroid use. In SLE, resistin levels correlated positively with Systemic Lupus International Collaborating Clinics Damage Index, glomerular filtration rate (GFR), hsCRP, erythrocyte sedimentation rate, homocysteine, and disease duration (all p < 0.03). Resistin level did not correlate with markers of insulin resistance or body adiposity, including homeostatic model assessment or BMI. Resistin levels were significantly elevated in SLE cases with CAC compared to cases without CAC (16.58 vs 13.10 ng/ml, respectively; p = 0.04). In multivariate logistic regression, the association was not present after adjustment for age, race, and GFR.Conclusion.SLE was independently associated with higher resistin levels. Among subjects with SLE, higher resistin level correlated positively with renal dysfunction, inflammatory markers, and disease damage but not with insulin resistance or BMI. SLE cases with CAC had higher resistin levels than cases without CAC; however, this relationship was dependent on other established risk factors.

ObjectiveTo determine if functional polymorphisms of folate/homocysteine pathway enzymes are associated with homocysteine concentrations and/or coronary artery calcification (CAC) scores in patients with systemic lupus erythematosus (SLE) and controls.MethodsWe investigated 163 SLE patients and 160 controls. Functional polymorphisms in 6 genes in the folate/homocysteine pathway were genotyped: 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C>T, MTHFR 1298A>C, cystathionine β-synthase (CBS) 844ins68, methionine synthase (MTR) 2756A>G, methionine synthase reductase (MTRR) 66A>G, thymidylate synthase (TYMS) 1494del6, and dihydrofolate reductase (DHFR) c.86+60_78.ResultsHomocysteine levels were higher in African American SLE patients than Caucasian patients and African American controls. Genotype distributions were significantly different in African American and Caucasian controls for 6 of the 7 polymorphisms. Genotype distributions for each polymorphism did not differ significantly between SLE patients and controls even after stratification by race. Glomerular filtration rate was strongly negatively correlated to homocysteine levels, and was therefore adjusted for as a covariate in the models of the effects of the polymorphisms on homocysteine levels. In SLE patients none of the 7 polymorphisms was associated with homocysteine concentrations. In Caucasian controls only MTHFR 677C>T and 1298A>C showed effects on homocysteine similar to what would be expected from the literature. There were no genotypic associations with median CAC scores in SLE patients or controls with and without stratification by race.ConclusionPolymorphisms in folate/homocysteine metabolizing enzymes do not predict higher homocysteine levels or CAC scores in patients with SLE.

To determine (1) whether the A(-2518)G polymorphism of CCL-2, the gene encoding monocyte chemoattractant protein-1 (MCP-1), is associated with disease, MCP-1 concentration, nephritis, or coronary artery calcification (CAC) in systemic lupus erythematosus (SLE); and (2) whether MCP-1 and homocysteine (Hcy) concentrations are correlated.Statistical tests were applied to determine the relationships between CCL-2 A(-2518)G genotypes, plasma MCP-1 concentrations, and clinical variables in Caucasian and African American patients with SLE and controls.The CCL-2 (-2518)G allele was not significantly associated with SLE in the whole study sample (p = 0.07). Among Caucasians, but not African Americans, G allele carriers had significantly increased risk of SLE (OR 4.2, 95% CI 1.8-9.6, p0.0001). Genotype was not associated with nephritis, CAC, or MCP-1 concentrations when all patients or all controls were considered; however, among recently diagnosed patients, G allele carriers had significantly higher MCP-1 concentrations than AA homozygotes (p = 0.02). SLE patients had higher MCP-1 concentrations than controls (p0.0001), African American patients had higher concentrations than Caucasian patients (p = 0.006), and patients with nephritis had higher concentrations than those without nephritis (p = 0.02). Although not associated with CAC, MCP-1 concentrations were significantly positively correlated with Hcy. CONCLUSION. CCL-2 A(-2518)G genotype is a significant risk factor for SLE among Caucasians but not African Americans, suggesting that genetically mandated differences in MCP-1 expression contribute to SLE etiology in the former. The positive correlation between MCP-1 and Hcy concentrations is consistent with the hypothesis that active inflammation and hyperhomocysteinemia are etiologically linked.