AB0715 POSSIBLE METHODS OF EARLY DIAGNOSIS OF RENAL ALTERATION IN PATIENTS WITH ANKYLOSING SPONDYLITIS

Abstract

Background:kidney damage is one of the extraarticular manifestations and complications of ankylosing spondylitis (AS). Due to some disadvantages of traditional renal function parameters, the search for new markers is actively conducted [1].Objectives:to evaluate urinary excretion of liver type of fatty acid binding protein (L-FABP), which is expressed in cells of proximal tubules, heart type of fatty acid binding protein (H-FABP), which is expressed in cells of distal tubules [2], and trefoil factor-3 (TFF-3), which is expressed in cells of the proximal and distal tubules and collecting duct [3], in patients with AS.Methods:urine samples of 50 patients (37 males, 13 females) were evaluated. Patient inclusion criteria were a diagnosis of AS according to the New York modified criteria (1984) and ASAS 2009 (The Assessment of SpondyloArthritis international Society, 2009) for axial spondyloarthritis and age 18 and over. Median age of patients was 39 [34;56] years, duration of joint syndrome – 10 [7;18] years, glomerular filtration rate (GFR) - 105 [83;119] ml/min/1.73 m2. Patients received nonsteroidal anti-inflammatory drugs (NSAIDs), and tumor necrosis factor alpha inhibitors (TNFα inhibitors). L-FABP, H-FABP, TFF-3 levels were measured by enzyme-linked immunosorbent assay. Urinary excretion was expressed as nanograms per millimol of urinary creatinine. The results were compared with the results of the control group.Results:the values of L-FABP in patients with AS without chronic kidney disease (CKD) exceeded the values in the control group: 0.05 [0.01;0.09] ng/mmol creatinine compared to 0.03 [0.00;0.06] ng/mmol, (р=0.04). H-FABP was detected in only 6 patients, all of them were with CKD. Its level was up to 601.50 ng/mmol. H-FABP level was undetectable in the control group. The level of TFF-3 in patients without CKD was higher than in the control group: 53.42 [20.84;105.71] and 23.31[1.97;62.90] ng/mmol respectively, (p=0.02). A correlation with disease activity (BASDAI and ASDAS) was found for TFF-3 (rs=0.33, p<0.05). This marker in patients receiving NSAIDs is higher compared with TNFα inhibitors: 89.51 [39.82;118.91] and 32.61 [13.51;88.23] ng/mmol respectively, (p=0.04). L-FABP and TFF-3 correlated with each other (rs=0.6, р<0.05). The level of FABPs and TFF-3 did not depend on sex, age, GFR and AS duration.Conclusion:L-FABP and TFF-3 may be of interest for diagnosis pre-clinical renal alteration, including those associated with the NSAIDs toxicity, in patients with AS. L-FABP and H-FABP may be useful in determining stages and levels of tubular injury