Vol.:(0123456789) 1 3 International Urology and Nephrology https://doi.org/10.1007/s11255-017-1748-y NEPHROLOGY - ORIGINAL PAPER From bench to the hemodialysis clinic: protein‑bound uremic toxins modulate NF‑κB/Nrf2 expression Milena B. Stockler‑Pinto 1,2  · Christophe O. Soulage 3  · Natália A. Borges 1  · Ludmila F. M. F. Cardozo 1  · Carla J. Dolenga 4  · Lia S. Nakao 4  · Roberto Pecoits‑Filho 5  · Denis Fouque 6  · Denise Mafra 1,2 Received: 31 August 2017 / Accepted: 11 November 2017 © Springer Science+Business Media B.V., part of Springer Nature 2017 Abstract Purpose Uremic toxins produced by gut microbiota (indoxyl sulfate—IS, p-cresyl sulfate—p-CS, and indole-3-acetic acid— IAA) accumulate in hemodialysis (HD) patients and exhibit potent infammatory efects. However, the impact of these toxins on nuclear E2-related factor 2 (Nrf2) and nuclear factor-kappa B (NF-κB) expression in HD patients remains poorly defned. The aim of this study was to evaluate the association between uremic toxins and Nrf2/NF-κB expression in vitro (RAW 264.7 macrophage-like cells) and in peripheral blood mononuclear cells from HD patients. Methods Uremic toxins, C-reactive protein (CRP), interleukin-6 (IL-6) and malondialdehyde (MDA) levels were measured in ffteen HD patients and nine healthy individuals. RAW 264.7 macrophage-like cells were incubated with IS, as a prototype of protein-bound uremic toxin. Nrf2 and NF-κB expressions were analyzed by RT-qPCR. Results HD patients presented high levels of infammatory markers, MDA and uremic toxins. In addition, they presented high NF-κB and low Nrf2 expression. Uremic toxins were positively correlated with NF-κB expression (IS, ρ = 0.58, p < 0.003; p-CS, ρ = 0.71, p < 0.001; IAA, ρ = 0.62, p < 0.001) and negatively with Nrf2 (IS, ρ = − 0.48, p = 0.01; p-CS, ρ = − 0.46, p < 0.02). Uremic toxins also exhibited positive correlations with CRP and MDA levels. Multivariate analysis revealed that p-CS is a determinant factor of NF-κB expression. In RAW 264.7 culture, NF-κB mRNA expression was stimulated by IS, while Nrf2 was downregulated. Conclusions Thus, uremic toxins may stimulate NF-κB mRNA and decrease Nrf2 expression in HD patients and, conse- quently, trigger infammation and oxidative stress. Keywords Chronic kidney disease · Infammation · Oxidative stress · NF-κB · Nrf2 · Uremic toxins Introduction Studies in chronic kidney disease (CKD) patients have identifed an imbalance of the gut microbiota (the so-called dysbiosis) as a new factor that may contribute to cardiovas- cular disease (CVD) [1, 2]. Some uremic toxins produced by the altered gut such as indoxyl sulfate (IS), p-cresyl sulfate (p-CS) and indole-3-acetic acid (IAA) are accumulated in CKD patients and can lead to pathological conditions such as infammation and oxidative stress which explain in part the risk of CVD in these patients [3, 4]. IS is an organic anion metabolized in the liver from indole, produced by the intestinal bacteria as a metabo- lite of tryptophan derived from dietary proteins [5]. This toxin is known to exert a wide range of toxic activities such as endothelial dysfunction and is independently associated with cardiovascular disease in CKD patients. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11255-017-1748-y) contains supplementary material, which is available to authorized users. * Milena B. Stockler-Pinto milbarcza@gmail.com 1 Graduate Program in Cardiovascular Sciences, Fluminense Federal University (UFF), Niterói, RJ, Brazil 2 Graduate Program in Nutrition Sciences, Fluminense Federal University (UFF), Niterói, RJ, Brazil 3 Univ-Lyon, CarMeN Laboratory, Inserm U1060, INSA Lyon, INRA U1397, Université Claude Bernard Lyon 1, Villeurbanne, France 4 Departamento de Patologia Básica, Federal University of Paraná (UFPR), Curitiba, PR, Brazil 5 Pontifícia Universidade Católica do Paraná, Curitiba, PR, Brazil 6 Department of Nephrology, Centre Hopitalier Lyon Sud, INSERM 1060, CENS, Université de Lyon, Lyon, France