Urinary Matrix Metalloproteinase-9 and Nephrin in Idiopathic Membranous Nephropathy: A Cross-Sectional Study.

AIM: Idiopathic membranous nephropathy (IMN) has a varied clinical course that requires accurate prediction as a prerequisite for treatment administration. Currently, its prognosis relies on proteinuria, a clinical parameter whose onset lags behind kidney injury. Increased urinary excretion of matrix metalloproteinase-9 (MMP-9) and nephrin has been reported in a number of IMN-like glomerular diseases in which they reflected disease severity. However, little or nothing is known of the importance of these biomarkers in IMN, a major cause of adult nephrotic syndrome. To highlight their potential, we measured both biomarkers and assessed their relationships with key parameters of renal function in IMN. METHODS: We quantified urinary MMP-9 and nephrin in 107 biopsy-proven IMN patients and 70 healthy subjects by enzyme-linked immunosorbent assay (ELISA). We then compared biomarker levels between patients and healthy subjects and among patients with different clinical features. We also determined the relationship of each biomarker with proteinuria and the estimated glomerular filtration rate (eGFR). RESULTS: Urinary MMP-9 and nephrin were significantly higher in IMN compared to healthy controls. Unlike nephrin, MMP-9 correlated significantly with proteinuria and was significantly higher among patients with nephrotic range proteinuria. Both biomarkers were correlated with eGFR, but only MMP-9 was significantly higher in patients with eGFR less than 90 ml/min/1.73 m2. CONCLUSION: Our findings suggest that urinary MMP-9 holds a greater potential than urinary nephrin in monitoring the severity of IMN.

Urine markers of podocyte dysfunction: a review of podocalyxin and nephrin in selected glomerular diseases.

Urinary podocalyxin and nephrin are urine markers of podocyte dysfunction that may reflect the integrity of kidney's filtration barrier. Studies on their respective roles in glomerular diseases are still underway. However, the isolated and unsystematic manner in which they are being studied does not permit proper identification of their roles in each glomerular disease. As such, there is little or no appreciation of what research has already achieved and what remains to be achieved as the research direction is not clearly defined. We explored the recent studies and outlined the major findings regarding the value of both biomarkers in each of the three glomerular disease entities. Our review covered diabetic nephropathy, membranous nephropathy and IgA nephropathy.