Functional and metabolomic analysis of urinary extracellular vesicles from juvenile mice with renal compensatory hypertrophy.

Unilateral nephrectomy, a procedure reducing kidney mass, triggers a compensatory response in the remaining kidney, increasing its size and function to maintain a normal glomerular filtration rate (GFR). Recent research has highlighted the role of extracellular vesicles (EVs) in renal physiology and disease, although their involvement in unilateral nephrectomy has been underexplored. In this study, unilateral nephrectomy was performed on young mice, and urinary extracellular vesicles (uEVs) characterization and cargo were analyzed. Kidney volume increased significantly post-nephrectomy, demonstrating compensatory hypertrophy. Serum creatinine, cystatin C, and urinary electrolytes concentrations were similar in both nephrectomized and control groups. Western blot analysis revealed upregulation of sodium-glucose cotransporter 2 (SGLT2) and sodium chloride cotransporter (NCC), and downregulation of sodium­potassium-chloride co-transporter (NKCC2) and epithelial sodium channel (ENaC) in the nephrectomized group. Metabolomic analysis of uEVs showed an enrichment of certain metabolites, including citrate and stachydrine. Interestingly, uEVs from the nephrectomized group demonstrated a protective effect, downregulating signal transducer and activator of transcription 3 (STAT3) and reducing reactive oxygen species (ROS) in renal proximal cells, compared to uEVs from the control group. This study suggests that uEVs contain bioactive components capable of inducing protective, anti-inflammatory, anti-fibrinolytic, and antioxidative effects in renal cells. These findings contribute to our understanding of uEVs' role in renal compensatory mechanisms after unilateral nephrectomy and may hold promise for future therapeutic interventions in renal diseases.

Lipid Profiles of Urinary Extracellular Vesicles Released during the Inactive and Active Phases of Aged Male Mice with Spontaneous Hypertension.

Hypertension remains a major problem, especially in the elderly, as it increases the risk for cardiovascular, coronary artery, cerebrovascular, and kidney diseases. Extracellular vesicles (EVs) play a role in the aging process and contribute to pathophysiology. Our goal was to examine differences in lipid profiles of urinary EVs (uEVs) collected during the inactive and active phases of aged mice and investigate whether these EVs regulate the density of lipid rafts in mouse cortical collecting duct (mpkCCD) principal cells. Here, we demonstrate the epithelial sodium channel (ENaC) inhibitor benzyl amiloride reduced systolic blood pressure in aged male mice during the inactive and active phases. Lipidomics data demonstrate differential enrichment of lipids between the two groups. For example, there are more phosphatidylethanolamine plasmalogens, particularly in the form of alkyl phosphatidylethanolamines, that are enriched in active phase uEVs compared to inactive phase uEVs from the same mice. Amiloride-sensitive transepithelial current increased more in mpkCCD cells challenged with uEVs from the active phase group. Moreover, more ENaC alpha protein was distributed to lipid raft fractions of mpkCCD cells challenged with active phase uEVs. Taken together, the identification of bioactive lipids associated with lipid rafts that are enriched in EVs released during the active phase of aged mice may offer clues to help understand lipid raft organization in recipient principal cells after EV uptake and increased renal ENaC activity, leading to a time-of-day dependent regulation of blood pressure in an aging model.