Metabolomic and biochemical characterization of a new model of the transition of acute kidney injury to chronic kidney disease induced by folic acid.

BACKGROUND: Renal diseases represent a major public health problem. The demonstration that maladaptive repair of acute kidney injury (AKI) can lead to the development of chronic kidney disease (CKD) and end-stage renal disease has generated interest in studying the pathophysiological pathways involved. Animal models of AKI-CKD transition represent important tools to study this pathology. We hypothesized that the administration of multiple doses of folic acid (FA) would lead to a progressive loss of renal function that could be characterized through biochemical parameters, histological classification and nuclear magnetic resonance (NMR) profiling. METHODS: Wistar rats were divided into groups: the control group received a daily intraperitoneal (I.P.) injection of double-distilled water, the experimental group received a daily I.P. injection of FA (250 mg kg body weight-1). Disease was classified according to blood urea nitrogen level: mild (40-80 mg dL-1), moderate (100-200 mg dL-1) and severe (>200 mg dL-1). We analyzed through biochemical parameters, histological classification and NMR profiling. RESULTS: Biochemical markers, pro-inflammatory cytokines and kidney injury biomarkers differed significantly (P < 0.05) between control and experimental groups. Histology revealed that as damage progressed, the degree of tubular injury increased, and the inflammatory infiltrate was more evident. NMR metabolomics and chemometrics revealed differences in urinary metabolites associated with CKD progression. The main physiological pathways affected were those involved in energy production and amino-acid metabolism, together with organic osmolytes. These data suggest that multiple administrations of FA induce a reproducible model of the induction of CKD. This model could help to evaluate new strategies for nephroprotection that could be applied in the clinic.

Estudio metabolómico de la enfermedad renal crónica: del modelo experimental al humano / Metabolomics in chronic kidney disease: from experimental model to human disease

Con una prevalencia global reportada de entre 11-13%, la enfermedad renal crónica (ERC) ha sido reconocida como un gran desafío para los sistemas de salud por sus implicaciones económicas y sociales. Al tratarse de una enfermedad crónica e irreversible, el tratamiento está dirigido a disminuir su progresión. La cuantificación de creatinina sérica es el método de elección para su diagnóstico y clasificación; sin embargo, es conocido que esta prueba tiene una sensibilidad clínica limitada, lo que ha conducido a la búsqueda de nuevos marcadores que permitan un diagnóstico y monitoreo oportuno. Desde esta perspectiva, el empleo de la metabolómica y de modelos animales ha permitido la identificación y estudio de nuevos metabolitos, candidatos a ser utilizados como futuros biomarcadores en la práctica clínica. La presente revisión tuvo como objetivo hacer una análisis de los perfiles metabolómicos reportados para la ERC, tanto en modelos experimentales como en estudios realizados en seres humanos. De acuerdo a los datos obtenidos, los metabolitos implicados en las rutas metabólicas de aminas cuaternarias y aminoácidos como el TMNO, el indoxilsulfato y derivados de la dimetilarginina representan una alternativa prometedora para la identificación, clasificación y pronóstico de la ERC.

Chronic kidney disease (CKD) high global prevalence, estimated between 11 to 13%, has been recognized as a mayor health challenge for healthcare systems due to its relevant economic and social implications. Main medical intervention strategies are directed to delay the progression of CKD and prevent outcomes. Serum creatinine concentration has been used to classify CKD and define its progression stage; however, it is well known the low sensitivity shown by this test. This fact has conducted to the search for new markers in order to improve the disease diagnosis, monitoring and treatment. In this context, metabolomics science and animal models have allowed identification of new metabolites that can be used as future biomarkers into clinical practice. This review aims to summarize the metabolomics profiles reported in different experimental models and clinical research on CKD. According with the data obtained, metabolites related with quaternary amines and aminoacid metabolic pathways like TMNO, indoxyl sulfate and dimethylarginine, suggest a promising alternative for identification, classification and prognosis of CKD.