Urinary Sediment Podocalyxin in Children with Glomerular Diseases

Abstract

Background: In an immunofluorescence study using antibody to podocalyxin, we reported that urinary excretion of podocytes reflected podocyte injury in glomeruli. However, this method has some problems, since it is basically urine cytology. To overcome problems with this test, we measured whole podocalyxin content in urine sediment by enzyme-linked immunosorbent assay (ELISA). Methods: Urinary sediment podocalyxin (u-sed-PCX) content of the first morning urine was quantified by ELISA after solubilization by detergent. We measured urine samples from children with various glomerular diseases and from healthy volunteers as controls. The glomerular diseases were classified into two categories: group I (inflammatory glomerular, 5 diseases) and group II (non-inflammatory glomerular, 3 diseases). Results: (1) The level of u-sed-PCX was significantly higher in the urine from patients with glomerular diseases (groups I and II, median (interquartile range (IQR)): 2 (0.6–18.5), n = 111) compared with controls (0 (0–0.4), n = 135), and the level of u-sed-PCX in group I diseases (3.4 (0.6–27.2), n = 90) was significantly higher than those in group II diseases (0.9 (0.1–2.5), n = 21). (2) The presence of PCX in urine sediment was confirmed by Western blot analysis. (3) The degree of proteinuria was significantly correlated with the level of u-sed-PCX in group I (r_s = 0.539, p < 0.001), but not in group II. (4) In group I, the level of u-sed-PCX was significantly higher in the acute phase than in the chronic phase (p < 0.01). (5) Comparison of histological findings of renal biopsies with u-sed-PCX showed a significant correlation in acute extracapillary lesions (p < 0.05). (6) Persistent high level of u-sed-PCX paralleled good histological progression in renal biopsies. Conclusion: Quantification of urinary sediment podocalyxin by ELISA is a reliable and useful laboratory marker for the estimation of the severity of active glomerular injury and a urinary index of acute extracapillary changes.

Relationships between Levels of Urinary Podocalyxin, Number of Urinary Podocytes, and Histologic Injury in Adult Patients with IgA Nephropathy

“…Kanno et al measured levels of u-PCX in children with glomerular diseases such as IgAN and concluded that u-PCX was a useful biomarker for estimating the severity of active glomerular injury and urinary index of acute extracapillary abnormalities in children (21). Habara et al reported that levels of u-PCX in adults with various forms of active GN were significantly higher than those in patients with chronic GN in long-term remission (10).…”

“…The epitopes on mAbs were characterized using PCX-Intra. The hybridomas were produced in immunized BALB/C mice as previously described by Tsutsumi et al (20), and then selected and subcloned according to the immunofluorescence pattern that was assayed on human renal cortex or ELISA using plates coated with wheat germ agglutinin-binding as reported elsewhere (21). Among the positive clones, mAb no.…”

“…Isolated human glomeruli were obtained as positive control on the basis of a previous report (8). Detection of protein in human glomerular lysate and urine sediment lysate was analyzed by Western blot according to the procedures described elsewhere (21).…”

Urinary FSP1 Is a Biomarker of Crescentic GN

“…There have been a few studies of potential biomarkers for crescentic GN. Kanno and colleagues 12 showed that levels of urinary sediment podocalyxin are elevated in children with cellular crescents. Levels of urinary macrophage migration inhibitory factor and matrix metalloproteinase activity are reportedly higher in patients with crescentic GN and ANCA-associated GN than in healthy controls, 13,14 but the levels are not significantly higher than in patients with other glomerular diseases.…”

Serum and Urinary Biomarkers Determination and Their Significance in Diagnosis of Kidney Diseases

“…Increased urine sediment levels of nephrin and podocin have been detected in patients with diabetic nephropathy and active lupus nephritis (27,28). Similarly, increased levels of podocalyxin have been found in the urine sediment of patients with IgA nephropathy, lupus nephritis and post-streptococcal glomerulonephritis (29).…”