Background Serum and urinary pentosidine, an advanced glycation end-product (AGE), levels were increased in patients with rheumatoid arthritis (RA) when compared with healthy controls. Antirheumatic medications including prednisolone, methotrexate and anti-tumor necrosis factor agents affect the serum and urinary pentosidine levels. In long-standing RA patients who were taking above medications, it might be difficult to evaluate whether disease activity or inflammation of arthritis affect pentosidine levels. To date no study to characterize pentosidine levels in untreated RA patients is currently available. Therefore, we studied urinary pentosidine levels in untreated RA patients and evaluated associations with RA disease-related variables.
Objectives To evaluate the effects of RA disease activity on urinary pentosidine levels.
Methods Consecutive nineteen patients, 63% women, with newly diagnosed RA according to 2010 American College of Rheumatology/European League Against Rheumatism classification criteria were included. Urinary levels of pentosidine were measured by HPLC after extraction of urine and normalised to the urinary creatinine. We calculated the correlations between pentosidine levels and the disease activity (DAS28, SDAI, CDAI), age, disease duration, mHAQ, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), matrix metalloproteinase-3 (MMP-3), rheumatoid factor (RF) and anti-CCP antibody, respectively.
Results Two patients with diabetes mellitus and/or renal disorder were excluded. Backgrounds of the remaining seventeen patients were median age 60 years old, median disease duration 0.3 year, mean DAS28-ESR 4.56 and positive anti-CCP antibody 70.6%. Urinary pentosidine levels correlated significantly to swollen joint counts (68) (r=0.583, P=0.014). In patients of whom disease durations were less than one year, urinary pentosidine levels showed a tendency of correlation to DAS28-ESR (r=0.524, P=0.081), DAS28-CRP (r=0.499, P=0.099), SDAI (r=0.562, P=0.072). Moreover, pentosidine levels showed a tendency of correlation to MMP-3 (r=0.507, P=0.093) although the levels correlated neither to ESR, CRP nor RF, anti-CCP antibody.
Conclusions Our study is the first to investigate associations of pentosidine levels with RA disease activity in newly diagnosed RA patients taking no antirheumatic medications. In untreated RA patients, we found positive correlations between urinary pentosidine levels and clinical disease activity and marker of inflammation. Inflammation and oxidative stress of RA may affect the accumulation of AGE.
Disclosure of Interest None declared