Follow-up protein profiles in urine samples during the course of obstructive feline idiopathic cystitis G. Treutlein a , C.A. Deeg b , S.M. Hauck c , B. Amann b , K. Hartmann a , R. Dorsch a,⇑ a Clinic of Small Animal Medicine, Center of Clinical Veterinary Medicine, LMU Munich, Germany b Institute of Animal Physiology, Department of Veterinary Sciences, LMU Munich, Germany c Research Unit for Protein Science, Helmholtz Zentrum München, German Research Centre for Environmental Health, Neuherberg, Germany article info Article history: Accepted 11 September 2013 Keywords: Cystitis Fibronectin Feline lower urinary tract disease Thioredoxin Urinary abstract Feline idiopathic cystitis (FIC) is a common lower urinary tract disorder in cats, which often recurs. Pub- lished reports document increased urine fibronectin and thioredoxin concentrations in cats with FIC com- pared with healthy control cats. Therefore, these proteins might be of interest in the pathophysiology of FIC. The purpose of the present study was to evaluate variations in these urine proteins throughout the course of FIC by assessing their concentrations in urine specimens from cats with a history of obstructive FIC. Urine total protein (TP) was measured using the Bradford assay, while urine fibronectin and thiore- doxin concentrations were determined by Western blot analysis. Urine TP was significantly higher in cats with obstructive FIC at presentation (day 0) than in healthy control cats (P < 0.01). There were significant decreases in urine TP in cats with obstructive FIC after 3 months (P < 0.01). Significantly higher urine fibronectin (P < 0.01) and thioredoxin (P < 0.05) concentra- tions were demonstrated in cats with FIC at day 0 compared to control cats, but there was no significant change over time (P > 0.05). Increased concentrations of these proteins over time might reflect ongoing structural and pathological alterations to functional processes in the urinary bladders of cats with obstructive FIC. Ó 2013 Elsevier Ltd. All rights reserved. Introduction Disorders of the lower urinary tract are common in domestic cats, occurring in 1.3–1.7% of all cats examined at private veterinary practices (Lund et al., 1999). Cats with lower urinary tract disorders have similar clinical signs regardless of cause, and these are charac- terised by variable combinations of dysuria, stranguria, pollakiuria, haematuria and periuria (Gunn-Moore, 2003). The most common aetiologies for feline lower urinary tract disorders are feline idio- pathic cystitis (FIC), followed by urolithiasis, bacterial urinary tract infection and urinary tract neoplasia (Lekcharoensuk et al., 2001; Gerber et al., 2005; Saevik et al., 2011). A common clinical sign, par- ticularly in male cats with FIC, is obstruction of the lower urinary tract (Westropp et al., 2005). Urethritis, urethral muscle spasm and/or urethral plug formation have been proposed as causes of obstruction in FIC (Gerber et al., 2005; Westropp et al., 2005). To date, the aetiology of FIC remains obscure, although numer- ous hypotheses have been proposed over the last 30 years (Kruger and Osborne, 1993; Buffington et al., 1996; Lavelle et al., 2000; Buffington et al., 2002; Birder et al., 2005). FIC and human intersti- tial cystitis (IC) share many clinical features, such as bladder pain, urgency, nocturia, the absence of an identifiable pathology, chronic signs, and the tendency to recur (Westropp and Buffington, 2002). The investigation of urine proteins has been applied to research investigating both human IC and FIC. Several potential urine bio- markers have been identified and examined for potential associa- tions with disease severity and response to treatment (Keay et al., 2007; Liu et al., 2009; Goo et al., 2010). In veterinary medicine, only a small number of studies have investigated urine proteins in FIC. Recently, the widely expressed high molecular weight glycoprotein fibronectin was detected in the urine of cats with FIC, both with and without obstruction (Lem- berger et al., 2011). Significantly higher urine fibronectin concentra- tions and lower fibronectin tissue signal intensities were demonstrated in cats with FIC compared to those without urinary tract disease and those with other urinary tract diseases, such as urolithiasis and bacterial urinary tract infection. Marked fibrosis of the bladder muscle layer and vascular walls, with the subsequent detachment and leakage of fibronectin into the urine, was suggested as the cause of increased urine fibronectin concentrations in FIC. Thioredoxin, a low molecular weight redox-regulating protein, was suggested as a novel potential interaction partner with fibronectin and co-precipitation with fibronectin was 1090-0233/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.tvjl.2013.09.015 ⇑ Corresponding author. Tel.: +49 8921802650. E-mail address: R.Dorsch@medizinische-kleintierklinik.de (R. Dorsch). The Veterinary Journal 198 (2013) 625–630 Contents lists available at ScienceDirect The Veterinary Journal journal homepage: www.elsevier.com/locate/tvjl