CD2AP mRNA in urinary exosome as biomarker of kidney disease

• Pellet microvesicles were positively stained with markers of exosome and podocyte.
• CD2AP mRNA in urine exosome was decreased significantly in kidney disease compared with controls.
• CD2AP mRNA in urine exosome correlated with levels of blood urea nitrogen, serum creatinine, eGFR and proteinuria.
• CD2AP mRNA in urine exosome correlated with both severity of tubulointerstitial fibrosis and glomerulosclerosis.
• CD2AP mRNA in urine exosome could discriminate kidney disease from controls.

AimsPodocyte injury plays an important role in the pathogenesis of kidney disease. Urinary exosomes are microvesicles released by tubular epithelial cells and podocytes containing information of their originated cells. This study investigated for the first time whether podocyte related mRNA in urinary exosome could serve as novel biomarkers for kidney disease.MethodsUrine samples were collected from 32 patients of kidney disease who underwent kidney biopsy and 7 controls. CD2AP, NPHS2 and synaptopodin were detected by real-time RT-PCR on RNA isolated from urinary exosome.ResultsThe pellet microvesicles were positively stained with exosome and podocyte marker, AQP2, CD9 and nephrin. CD2AP mRNA was lower (p = 0.008) in kidney disease patients 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 synaptopodin correlated 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 disease from controls with AUC of 0.821 (p = 0.008).ConclusionsUrinary exosome mRNA of CD2AP might be a non-invasive tool for detecting both renal function and fibrosis of kidney disease.