CD2AP mRNA in urinary exosome as biomarker of kidney disease.

Abstract Aims Podocyteinjury plays an important role in the pathogenesis of kidney disease. Urinary exosomesare microvesiclesreleased by tubular epithelial cells and podocytescontaining information of their originated cells. This study investigated for the first time whether podocyterelated mRNA in urinary exosomecould serve as novel biomarkers for kidney disease. Methods Urine samples were collected from 32 patients of kidney diseasewho underwent kidney biopsy and 7 controls. CD2AP, NPHS2 and synaptopodinwere detected by real-time RT-PCR on RNA isolated from urinary exosome. Results The pellet microvesicleswere positively stained with exosomeand podocytemarker, AQP2, CD9 and nephrin. CD2AP mRNA was lower (p = 0.008) in kidney diseasepatients compared with controls and decreased with the increasing severity of proteinuria (p = 0.06). CD2AP correlated with serum creatinine (r = − 0.373, p = 0.035), BUN (r = − 0.445, p = 0.009) and eGFR (r = 0.351, p = 0.046). Neither NPHS2 nor synaptopodincorrelated with parameters of renal function. CD2AP mRNA correlated negatively with 24 hour urine protein (r = − 0.403, p = 0.022), severity of tubulointerstitial fibrosis (r = − 0.394, p = 0.026) and glomerulosclerosis(r = − 0.389, p = 0.031) and could discriminate kidney diseasefrom controls with AUC of 0.821 (p = 0.008). Conclusions Urinary exosomemRNA of CD2AP might be a non-invasive tool for detecting both renal function and fibrosis of kidney disease.