EN-RAGE (extracellular newly identified receptor for advanced glycation end-products binding protein) and mortality of long-term hemodialysis patients: A prospective observational cohort study Marta Kalousová a, ⁎, Aleš A. Kuběna a , Hana Benáková a , Sylvie Dusilová-Sulková b , Vladimír Tesař c , Tomáš Zima a a Institute of Medical Biochemistry and Laboratory Diagnostics, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, U nemocnice 2, 128 0 Prague, Czech Republic b Department of Nephrology, Institute of Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Prague, Czech Republic c Department of Nephrology, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, U nemocnice 2, 128 0 Prague, Czech Republic abstract article info Article history: Received 3 October 2011 Received in revised form 3 January 2012 Accepted 15 February 2012 Available online 25 February 2012 Keywords: Biomarker Cardiovascular EN-RAGE Hemodialysis Infection Inflammation Mortality Risk S100A12 Objectives: EN-RAGE is extracellular newly identified receptor for advanced glycation end-products binding protein playing a role in inflammation. The aim was to test the relationship of EN-RAGE to prognosis of long-term hemodialysis patients (HD). Design and methods: This is a prospective observational cohort study in 261 HD patients followed up for five years. Laboratory parameters were measured at the beginning of the study. Results: EN-RAGE was slightly but unsignificantly increased in HD patients compared with healthy con- trols and correlated significantly with inflammatory markers. Univariate Cox analysis demonstrated EN- RAGE as a significant predictor for mortality due to infection (HR (95%CI): 1.305 (1.063–1.602), per standard deviation, p = 0.01), but this significance disappeared in multivariate Cox analysis when CRP was included into the model. Conclusions: Our study demonstrates EN-RAGE as an inflammatory biomarker. It is related to mortality of HD patients due to infection, but in our study, it did not provide additional information to CRP. © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved. Introduction EN-RAGE (extracellular newly identified receptor for advanced glycation end- products binding protein, also S100A12 or calgranulin C) is an endogenous ligand of the receptor for advanced glycation end products (RAGE) playing a role in the pathogenesis of inflammatory diseases [1]. Human S100A12 (UniProt ID: P80511) was first described by Guignard et al. in 1995 [2]. It is predominantly expressed and secreted by neutrophil granulocytes and at a lower extent, it was found in monocytes [2]. At an early stage of differentiation, expression of S100A12 was also observed both in epithelial and dendritic cells [3,4]. The S100A12 gene was mapped to 1q21.2-1q22 (1q21.3) and is located between genes of S100A8 and S100A9 [5]. The mature S100A12 consists of 91 amino acids (Mr 10,444 Da) [1]. S100A12 is located intracellularly and is also known to be secreted into extra- cellular compartments [6]. Intracellular S100A12 exists as an anti- parallel homodimer and upon calcium-dependent activation interacts with target proteins to regulate cellular functions [7]. Extracellular S100A12 exists majorly as homodimer and hexamer [8]. It is released from granulocytes in response to cell stress, turns into a danger signal and so belongs to damage-associated molecular pattern molecules or alarmins. It is part of the innate immune response and linked to certain autoimmune reactions [9,10]. Among natural targets of S100A12, the receptor for advanced gly- cation end-products (RAGE) is of significant importance [11,12]. RAGE is a member of the immunoglobulin superfamily and was first described by Neeper in 1993 [13]. It is a multiligand receptor, first characterized as receptor for advanced glycation end products, but binding a variety of ligands as amphoterin (HMGB1), amyloid β- peptide and several S100 proteins. Ligand binding to RAGE activates intracellular signal cascades including MAP-kinase and NKκB which subsequently induces secretion of cytokines, expression of adhesion Clinical Biochemistry 45 (2012) 556–560 ⁎ Corresponding author at: Institute of Medical Biochemistry and Laboratory Diag- nostics, 1st Faculty of Medicine, Charles University and General University Hospital, Central Research Laboratories, Na Bojišti 3, 121 08 Prague 2, Czech Republic. Fax: + 420 224962848. E-mail addresses: marta.kalousova@lf1.cuni.cz, marta.kalousova@vfn.cz, marta.kalousova@seznam.cz (M. Kalousová). 0009-9120/$ – see front matter © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.clinbiochem.2012.02.014 Contents lists available at SciVerse ScienceDirect Clinical Biochemistry journal homepage: www.elsevier.com/locate/clinbiochem