Effect of paricalcitol on the urinary peptidome of kidney transplant patients

Disorders in bone mineral metabolism are common after kidney transplantation, covering, among other pathologic conditions, secondary hyperparathyroidism. Paricalcitol, a selective vitamin D receptor activator, is indicated in the prevention and treatment of secondary hyperparathyroidism. Recent evidence suggests that paricalcitol is also associated, by mechanisms not yet clarified, with improved patient survival. To clarify these unknown mechanisms, the aim of this study was to determine whether 3 months of treatment with paricalcitol modified the urinary peptidome of kidney transplant patients.

This prospective study included 42 stable kidney transplant patients, randomized in 2 groups: a group treated with 1 μg/d paricalcitol (n=25) and a control group that did not receive paricalcitol (n=17). Urine samples of all patients were collected at baseline and after 3 months. The proteomic approach was based on magnetic bead technology coupled to MALDI-TOF mass spectrometry.

Paricalcitol treatment produced significant changes in urinary peptidome of kidney transplant patients. Variations in urinary peptides were independent of the degree of proteinuria and of the decrease in parathyroid hormone levels.

With this preliminary study, we obtained a profile of urinary peptides in which changes occurred due to treatment with paricalcitol. The identification of proteins to which these peptides belong may improve our knowledge about the possible pleiotropic effects of paricalcitol.