Background Asymmetric dimethylarginine (ADMA) levels in AS patients were found to be higher than controls (1).The relationship between vitamin D level and disease activity was shown in AS (2). But the effects of vitamin D replacement on the disease acitivity, inflammatory parameters and ADMA pathway were not investigated in AS.

Objectives To determine the effects of vitamin D replacement on the disease activity, inflammatory parameters and ADMA pathway in AS.

Methods All AS patients with vitamin D level of <20 ng/ml who consecutively attended the outpatient rheumatology clinic were enrolled.C-reactive protein, erythrocyte sedimentation rate, Bath AS disease activity index (BASDAI), Bath AS Functional Index (BASFI) TNF-α, IL-1, IL-6, ADMA, symmetric dimethylarginine (SDMA), NG-monomethyl-L-arginine (LNMMA), arginine, arginine/ADMA ratio and citrulline levels were analyzed when vitamin D level was <20 ng/ml and ≥20 ng/ml, after replacement.

Results The study population was represented by 82 patients, 48 women (58.5%), mean age 39 years old and mean disease duration 5.5 years. When vitamin D levels were increased to normal levels, levels of IL-1 (4.8±9.7 and 3.1±4.0 p<0.001), IL-6 (7.1±14.1 and 4.7±2.1 p=0.009), ADMA (0.8±0.2 and 0.4±0.1 p<0.001), SDMA (0.9±0.2 and 0.4±0.2 p<0.001), LNMM (0.08±0.02 and 0.06±0.02 p<0.001), arginine (385.8±106.4 and 269.2±79.0 p<0.001) and citrulline (91,1±34,3 and 75,3±23,5 p<0,001) were reduced. Levels of arginine/ADMA ratio was increased (498.7±136.5 and 576.7±170.7 p<0.001) (Table 1). Also BASDAI, BASFI and erythrocyte sedimentation rate were decreased but it was statistically meaningless. In pearson correlation analysis, ADMA, SDMA, LNMMA, arginine and citrulline were negatively correlated with vitamin D levels.Multiple regression analysis showed that SDMA, arginine and citrulline were significantly related with vitamin D levels. Negative correlation between ADMA and vitamin D levels was shown in Figure 1

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Conclusions Vitamin D replacement in AS with low vitamin D levels improves antioxidant status via ADMA pathway and shows anti-inflammatory effects on IL-1 and IL-6. In literature, there is no other study investigating the effects of increased vitamin D levels on disease activity, inflammatory parameters and ADMA pathway in AS.

References

1. Sari I, Kebapcilar L, et al: Increased levels of asymmetric dimethylarginine (ADMA) in patients with ankylosing spondylitis. Intern Med 2009, 48(16):1363–1368.

2. Lange U, Teichmann J, et al: Association of 1.25 vitamin D3 deficiency, disease activity and low bone mass in ankylosing spondylitis. Osteoporos Int 2005, 16(12):1999–2004.

References

Disclosure of Interest None declared