Peptides in Blood, Urine and Dialysate: Towards Unravelling Renal Peptide Handling.Proteomics Clin Appl. 2020 Jul 03 [Online ahead of print]PC
We investigated the peptidomes of spent hemodialysate, urine, and plasma, to shed light on peptide handling in the kidney.
We collected 15 plasma, 15 urine and 13 spent hemodialysate samples from age and sex-matched subjects with chronic kidney disease. Peptide identification and quantification were performed with capillary electrophoresis-coupled mass spectrometry.
We detected 6278 urinary peptides, 1743 plasma peptides and 1727 peptides from spent hemodialysate. Of these, we could assign sequences to 1580, 419 and 352 peptides respectively. We found a strong correlation in peptide abundance between urine and spent hemodialysate (P = 3e-21, Rho = 0.52), a moderately strong correlation between spent hemodialysate and plasma (P = 4.5e-5, Rho = 0.30), and no significant correlation between urine and plasma (P = 0.11, Rho = 0.094). Collagen and fibrinogen alpha peptides are highly abundant in all three body fluids. In spent hemodialysate, thymosin β4 is one of the most abundant peptides, which is shown to be negatively associated with the estimated glomerular filtration rate (Rho = -0.39, p-value = 3.9e-81).
CONCLUSION AND CLINICAL RELEVANCE
The correlation of peptide abundance in these three body fluids is lower than expected, supporting the hypothesis that tubular reabsorption has a major impact on urinary peptide content. Further investigation of thymosin β4 in hemodialysis is thus warranted. This article is protected by copyright. All rights reserved.