Protein-bound uremic toxins, such as p-cresol sulfate (PCS), can be accumulated with declined renal function and aging and is closely linked with central nervous system (CNS) diseases. In the periphery, PCS has effects on oxidative stress and inflammation. Since oxidative stress and inflammation have substantial roles in the pathogenesis of neurological disorders, the CNS effects of PCS were investigated in unilateral nephrectomized C57/BL/6 mice. Unlike intact mice, unilateral nephrectomized mice showed increased circulating levels of PCS after exogenous administration. Upon PCS exposure, the unilateral nephrectomized mice developed depression-like, anxiety-like, and cognitive impairment behaviors with brain PCS accumulation in comparison with the nephrectomy-only group. In the prefrontal cortical tissues, neuronal cell survival and neurogenesis were impaired along with increased apoptosis, oxidative stress, and neuroinflammation. Circulating brain-derived neurotrophic factors (BDNF) and serotonin were decreased in association with increased corticosterone and repressor element-1 silencing transcription factor (REST), regulators involved in neurological disorders. On the contrary, these PCS-induced changes were alleviated by uremic toxin absorbent AST-120. Taken together, PCS administration in mice with nephrectomy contributed to neurological disorders with increased oxidative stress and neuroinflammation, which were alleviated by PCS chelation. It is suggested that PCS may be a therapeutic target for chronic kidney disease-associated CNS diseases.

Protein-bound uremic toxins impaired mitochondrial dynamics and functions Protein-bound uremic toxins impaired mitochondrial dynamics and functions

Neutrophil gelatinase-associated lipocalin (NGAL) and liver-type fatty acid binding protein (L-FABP) are emerging as excellent biomarkers in the urine and plasma for the early prediction of acute and chronic kidney injury. The aims of this prospective study were to determine the role of albuminuria, and that of serum and urine levels of NGAL and L-FABP as predictors of a decline in the glomerular filtration rate (GFR) in patients with type 2 diabetes. A longitudinal cohort study with one hundred forty type 2 diabetic patients was conducted. Serum and urine levels of NGAL and L-FABP, and the urine albumin excretion rate were determined. The correlation between the kidney injury biomarkers and rate of GFR decline was analyzed. The eGFR of study subjects decreased significantly as the study progressed (86.4±31.1 vs. 74.4±27.3 ml/min/1.73 m², P<0.001), and the urine albumin excretion rate increased significantly (264.9±1060.3 vs. 557.7±2092.5 mg/day, P = 0.009). The baseline urine albumin excretion rate and serum L-FABP level were significantly correlated with baseline eGFR (P<0.05). The results of regression analysis for the correlations between the rate of eGFR change and the baseline levels of NGAL and L-FABP, and the urine albumin excretion rate showed that only the urine albumin excretion rate was significantly correlated with the rate of eGFR change (standardized coefficients: −0.378; t: −4.298; P<0.001). Tubular markers, such as NGAL and L-FABP, may not be predictive factors associated with GFR decline in type 2 diabetic patients.