Cross-correlation of plasma concentrations of branched-chain amino acids: A comparison between healthy participants and patients with chronic kidney disease

The metabolic pathway regulation in kidney injury and repair

Kidney injury and repair are accompanied by significant disruptions in metabolic pathways, leading to renal cell dysfunction and further contributing to the progression of renal pathology. This review outlines the complex involvement of various energy production pathways in glucose, lipid, amino acid, and ketone body metabolism within the kidney. We provide a comprehensive summary of the aberrant regulation of these metabolic pathways in kidney injury and repair. After acute kidney injury (AKI), there is notable mitochondrial damage and oxygen/nutrient deprivation, leading to reduced activity in glycolysis and mitochondrial bioenergetics. Additionally, disruptions occur in the pentose phosphate pathway (PPP), amino acid metabolism, and the supply of ketone bodies. The subsequent kidney repair phase is characterized by a metabolic shift toward glycolysis, along with decreased fatty acid β-oxidation and continued disturbances in amino acid metabolism. Furthermore, the impact of metabolism dysfunction on renal cell injury, regeneration, and the development of renal fibrosis is analyzed. Finally, we discuss the potential therapeutic strategies by targeting renal metabolic regulation to ameliorate kidney injury and fibrosis and promote kidney repair.

Changes in plasma-concentration ratios of branched-chain amino acids in acute and convalescent phases of bacterial pneumonia

Branched-chain amino acids (BCAAs) have different immunity-related functions. Thus, BCAAs require evaluation in terms of their plasma concentration ratio. Eighty healthy participants and 57 patients with community-acquired pneumonia were enrolled. Samples from the healthy participants were collected after 12-h fasting; samples from the community-acquired pneumonia group were collected 2–3 h after lunch, during the acute (day 0) and convalescent (day 7) phases. The coefficient “a” of the regression line (Y = aX + b) of each BCAA plasma concentration was calculated from healthy participants and fixed, and each intercept “b” was calculated from the plasma concentration of each BCAA pair. Isoleucine levels increased; no significant changes in leucine concentrations were observed between healthy participants and pneumonia patients on days 0 and 7. In female participants in the pneumonia group, valine concentrations decreased on day 0. The isoleucine concentration was relatively higher than the leucine concentration on day 7 when evaluated with “b”. Changes in “b” on days 0 and 7 differed between men and women. There were sex-related differences in the plasma concentration ratios of BCAAs evaluated by “b”, which indicates a possible sex-related difference in the metabolic response to bacterial infection.

Uremic encephalopathy

Uremic encephalopathy encompasses a wide range of central nervous system abnormalities associated with poor kidney function occurring with either progressive chronic kidney disease or acute kidney injury. The syndrome is likely caused by retention of uremic solutes, alterations in hormonal metabolism, changes in electrolyte and acid-base homeostasis, as well as changes in vascular reactivity, blood-brain barrier transport, and inflammation. There are no defining clinical, laboratory, or imaging findings, and the diagnosis is often made retrospectively when symptoms improve after dialysis or transplantation. The diagnosis is also made difficult because of the many confounding and overlapping conditions seen in patients with chronic kidney disease and acute kidney injury. Thus, institution of kidney replacement therapy should be considered as a trial to improve symptoms in the right clinical context. Neurological symptoms that do not improve after improvement in clearance should prompt a search for other explanations. Further knowledge linking possible uremic retention solutes with neurological symptoms is needed to better understand this syndrome as well as to develop more tailored treatments that aim to improve cognitive function.