Modulation of urinary peptidome in humans exposed to high altitude hypoxia

The exposure of healthy subjects to high altitude represents a model to explore the pathophysiology of diseases related to tissue hypoxia and to evaluate pharmacological approaches potentially useful as a therapy for chronic diseases related to hypoxia. We explored the urinary peptidome to detect alterations induced by the exposure of subjects to different altitudes (sea level, high altitude = 3500 m, very high altitude = 5400 m) and to pharmacological treatment. Urine samples were collected from 47 subjects, randomly and blindly assigned to placebo (n = 24) or Telmisartan (n = 23). Samples were purified by the use of magnetic beads, then analysed by MALDI-TOF MS. Results showed that the urinary peptidome is not affected by the administration of Telmisartan, neither at the sea level nor at high and very high altitudes. In contrast, the urinary protein profiles are modified when subjects are exposed to high and very high altitudes, and we detected six peptides differentially expressed in hypobaric hypoxia at high or very high altitude compared to the sea level. Two of them were identified as fragments of the glycoprotein uromodulin and of the α1-antitrypsin. This is the first proteomic study showing that hypobaric hypoxia conditions affect the urinary peptidome.