Serum irisin concentrations and osteoporotic vertebral fractures in women with rheumatoid arthritis: A cross-sectional study.

ABSTRACT: Irisin stimulates osteoblast differentiation increasing bone mass a decreasing in irisin levels might contribute to osteoporotic fractures in inflammatory diseases. To date, there is controverted whether irisin levels are associated with osteoporotic fractures in rheumatoid arthritis (RA). Therefore, we evaluate the association of serum irisin with osteoporotic Vertebral Fractures (VFs) in women with RA.A total of 148 women with RA was included in the study.Clinical characteristics and risk factors of VFs was evaluated. For measurement of bone mineral density we included the assessment of lumbar spine (AP L1-L4) and Femoral Neck by dual-energy X-ray absorptiometry (DXA). VFs were evaluated by lateral vertebral assessment (LVA) of the dorsal and lumbar regions using X-ray and digital vertebral morphometry by DXA, using the Genant scale. Serum irisin levels were measured by ELISA. A reference group of 97 women with non-rheumatic diseases were included to compare irisin levels.RA patients had a median age of 59 years and 41% had osteoporosis. Seventy three (49%) had VFs. Lower irisin levels were observed in RA patients compared to controls (94 ±â€Š74 vs 135 ±â€Š103, P < .001). Irisin concentrations were lower in RA + VFs than RA non-VFs (74 ±â€Š42 vs 113 ±â€Š92 ng/mL, P = .001). In the multivariable logistic regression analysis the low 50 percentile irisin levels < 73 ng/mL (OR:3.1, 95% CI:1.55-6.2, P = .001), and disease duration of RA (OR:1.04, 95% CI:1.001-1.08, P = .04) were associated with an increase in the risk of VFs.A decrease of irisin levels is associated to VFs in RA. These results are valuable to consider that RA patients with low levels of irisin are in a potential risk of VFs.

The Effect of Visceral Abdominal Fat Volume on Oxidative Stress and Proinflammatory Cytokines in Subjects with Normal Weight, Overweight and Obesity.

PURPOSE: The increase of visceral abdominal fat (VAF) and oxidative stress (OS) are independent predictors for cardiovascular risk. This study aimed to determine the association of VAF with proinflammatory cytokines, oxidants, antioxidants, and oxidative damage to DNA in subjects with normal weight, overweight, and obesity. PATIENTS AND METHODS: A cross-sectional study that included 21 men and 71 women who attended for a medical check-up was conducted. Dual-energy X-ray absorptiometry (DXA) was used to measure the VAF volume. ELISA and colorimetric techniques were used for chemical analysis. RESULTS: Low activity of superoxide dismutase (SOD) was found in overweight and obese subjects compared to the normal weight group (p=0.005). In contrast, the activity of glutathione peroxidase (GPx) was higher in the overweight and obesity groups compared to the normal weight subjects (p=0.017). The total antioxidant capacity (TAC) was also increased in the overweight group compared to the normal weight group (p=0.04). According to the volume of VAF, the levels of tumor necrosis factor alfa and interleukin 6 showed no differences between subjects with normal and high VAF. Subjects with high VAF show higher levels of 8-isoprostans compared to normal VAF group (p=0.039). Less concentration of 8-oxoguanine-DNA-N-glycosylase-1 (hOGG1) was found in the high VAF group (p=0.032) compared to the normal VAF subjects. VAF was positively correlated with lipoperoxides (LPO) (r=0.27, p<0.05) and 8-isoprostanes (r=0.25, p<0.05). We also found correlations between oxidative stress markers and anthropometric ratios for intra-abdominal fat. The waist-hip ratio was positively correlated with LPO (r=0.30, p<0.05) and TAC (r=0.24, p<0.05). CONCLUSION: These findings suggest that the predominantly oxidative damage associated with VAF in overweight or obesity is lipoperoxidation and oxidative DNA damage. Alterations in endogenous antioxidant defenses may not be linked to the amount of VAF.