Increased levels of soluble TNF-like cytokine 1A in ankylosing spondylitis

Objective. To determine the expression of soluble TNF-like cytokine 1A (sTL1A), a new member of the TNF superfamily, in patients with AS. Methods. Seventy-five consecutive patients with AS [61 males, mean (s.d.) age: 47.2 (15.5) years, disease duration: 20.3 (13.9) years] were included in this study. Forty-four patients were anti-TNF treatment naive, whereas the remaining patients were on infliximab (n = 21), adalimumab (n = 3) or etanercept (n = 7). The patients' perceived disease activity was recorded by BASDAI and AS DAS using serum CRP levels (ASDAS-CRP), whereas functional status was assessed by BASFI and measurements of spinal mobility (AS Metrology). Serum concentrations of TL1A were measured by ELISA. Twenty-five age- and sex-matched healthy individuals served as controls. Results. Anti-TNF treatment-naive patients demonstrated a 2.6-fold higher sTL1A average value [mean (s.e.m.) 581 (157.5) pg/ml] compared with healthy controls [226.7 (48.24) pg/ml, P = 0.042]. The sTL1A levels of anti-TNF-treated patients [178 (42)] were significantly lower than anti-TNF treatment-naive patients (3.3-fold decrease, P = 0.0038) and comparable to those of healthy controls. No significant association was found between sTL1A level and functional status (BASFI score, AS Metrology parameters) or CRP measured in the same sera; however, a positive correlation was observed between individual levels of sTL1A and both BASDAI (P = 0.008) and ASDAS-CRP (P = 0.058) scores suggesting that sTL1A levels may reflect disease activity in patients with AS. Conclusion. TL1A is up-regulated in AS, associates with disease activity and is influenced by anti-TNF treatment, suggesting that TL1A may be of pathogenic and potentially of therapeutic importance in AS patients.