Urinary
proteome was analyzed and quantified by tandem mass tag (TMT) labeling followed by bioinformatics analysis to study
diabetic nephropathy (DN) pathophysiology and to identify
biomarkers of a clinical outcome. We included type 2 diabetic normotensive non-obese males with (n = 9) and without (n = 11) incipient DN (microalbuminuria). Sample collection included blood and urine at baseline (control and DN basal) and, in DN patients, after 3 months of
losartan treatment (DN treated). Urinary
proteome analysis identified 166 differentially abundant
proteins between controls and DN patients, 27 comparing DN-treated and DN-basal patients, and 182 between DN-treated patients and controls. The mathematical modeling analysis predicted 80 key
proteins involved in DN pathophysiology and 15 in
losartan effect, a total of 95
proteins. Out of these 95, 7 are involved in both processes.
VCAM-1 and
neprilysin stand out of these 7 for being differentially expressed in the urinary
proteome. We observed an increase of
VCAM-1 urine levels in DN-basal patients compared to diabetic controls and an increase of urinary
neprilysin in DN-treated patients with persistent
albuminuria; the latter was confirmed by ELISA. Our results point to
neprilysin and
VCAM-1 as potential candidates in DN pathology and treatment.