Marco Hatem-Vaquero1, Sergio de Frutos1, Alicia Luengo2, Alba González Abajo3, Mercedes Griera1, Manuel Rodríguez-Puyol2, Diego Rodríguez-Puyol4, Laura Calleros5. 1. Departamento de Biología de Sistemas, Universidad de Alcalá, Alcalá de Henares, Madrid, España; Fundación Renal Íñigo Álvarez de Toledo (FRIAT), Madrid, España; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, España; Red de Investigación Renal (REDinREN), Instituto de Salud Carlos III, Madrid, España. 2. Departamento de Biología de Sistemas, Universidad de Alcalá, Alcalá de Henares, Madrid, España; Fundación Renal Íñigo Álvarez de Toledo (FRIAT), Madrid, España; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, España. 3. Fundación Renal Íñigo Álvarez de Toledo (FRIAT), Madrid, España; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, España; Red de Investigación Renal (REDinREN), Instituto de Salud Carlos III, Madrid, España; Sección de Nefrología y Fundación para la Investigación, Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Madrid, España. 4. Fundación Renal Íñigo Álvarez de Toledo (FRIAT), Madrid, España; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, España; Red de Investigación Renal (REDinREN), Instituto de Salud Carlos III, Madrid, España; Sección de Nefrología y Fundación para la Investigación, Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Madrid, España; Departamento de Medicina y Especialidades Médicas, Universidad de Alcalá, Alcalá de Henares, Madrid, España. 5. Departamento de Biología de Sistemas, Universidad de Alcalá, Alcalá de Henares, Madrid, España; Fundación Renal Íñigo Álvarez de Toledo (FRIAT), Madrid, España; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, España; Red de Investigación Renal (REDinREN), Instituto de Salud Carlos III, Madrid, España. Electronic address: laura.calleros@uah.es.
Abstract
BACKGROUND: Patients with chronic kidney disease present with an accumulation of uraemic toxins, which have been identified as pathogenic agents associated with cardiovascular mortality, which is very high is this patient group. A phenomenon common to the progressive renal dysfunction and associated vascular damage, is the abnormal accumulation of extracellular matrix (ECM) proteins in the renal or vascular structures. OBJECTIVE: To determine the contribution of uraemia or the uraemic toxins to the production of cytokinins and ECM in aortas of uraemic animals or human aortic smooth muscle cells (HASMCs). MATERIALS AND METHODS: Mice were used with uraemia induced by a diet rich in adenine (0.2%) for 2, 4 or 6 weeks. Kidney function was evaluated by means of urine volume, plasma levels of creatinine, urea, fractional excretion of sodium, and vascular damage using histology, as well as protein expression using RT-qPCR. The HASMCs were incubated in vitro with uraemic toxins: p-cresol 10-100 (μg/ml) and indoxyl-sulphate25-100 (μg/ml) alone or simultaneously. The protein expression was evaluated using Western blot and confocal microscopy. RESULTS: The administration of adenine produced progressive kidney damage in the mice, thickening of the aortic wall, and increasing the expression of TGF-β1 and ECM proteins. The toxins at high doses and combined also induced the expression of TGF-β1 and ECM proteins by the HASMCs. CONCLUSIONS: The uraemia produced by an adenine rich diet or high doses of uraemic toxins induced the abnormal deposit of ECM proteins in the vascular wall or its production by HASMCs. The understanding of the mechanisms that underlie this pathophysiological process may be useful in the prevention of cardiovascular damage associated with the progress of chronic kidney disease, a disease, at the moment that is irreversible and occasional silent until its diagnosis in advanced stages.
BACKGROUND:Patients with chronic kidney disease present with an accumulation of uraemic toxins, which have been identified as pathogenic agents associated with cardiovascular mortality, which is very high is this patient group. A phenomenon common to the progressive renal dysfunction and associated vascular damage, is the abnormal accumulation of extracellular matrix (ECM) proteins in the renal or vascular structures. OBJECTIVE: To determine the contribution of uraemia or the uraemic toxins to the production of cytokinins and ECM in aortas of uraemic animals or human aortic smooth muscle cells (HASMCs). MATERIALS AND METHODS:Mice were used with uraemia induced by a diet rich in adenine (0.2%) for 2, 4 or 6 weeks. Kidney function was evaluated by means of urine volume, plasma levels of creatinine, urea, fractional excretion of sodium, and vascular damage using histology, as well as protein expression using RT-qPCR. The HASMCs were incubated in vitro with uraemic toxins: p-cresol 10-100 (μg/ml) and indoxyl-sulphate25-100 (μg/ml) alone or simultaneously. The protein expression was evaluated using Western blot and confocal microscopy. RESULTS: The administration of adenine produced progressive kidney damage in the mice, thickening of the aortic wall, and increasing the expression of TGF-β1 and ECM proteins. The toxins at high doses and combined also induced the expression of TGF-β1 and ECM proteins by the HASMCs. CONCLUSIONS: The uraemia produced by an adenine rich diet or high doses of uraemic toxins induced the abnormal deposit of ECM proteins in the vascular wall or its production by HASMCs. The understanding of the mechanisms that underlie this pathophysiological process may be useful in the prevention of cardiovascular damage associated with the progress of chronic kidney disease, a disease, at the moment that is irreversible and occasional silent until its diagnosis in advanced stages.