Relationships between levels of urinary podocalyxin, number of urinary podocytes, and histologic injury in adult patients with IgA nephropathy.
OBJECTIVE
Podocalyxin (PCX) is present on the apical cell membrane of podocytes and is shed in urine from injured podocytes. Urinary podocalyxin (u-PCX) is associated with severity of active glomerular injury in patients with glomerular diseases. This study examined the relationship between number of urinary podocytes, levels of u-PCX, and glomerular injury in adults with IgA nephropathy (IgAN).


METHODS
Urine samples voided in the morning on the day of biopsy were obtained from 51 patients with IgAN (18 men and 33 women; mean age, 31 years). All renal biopsy specimens were analyzed histologically. Pathologic variables of IgAN were analyzed per Shigematsu classification, the Oxford classification of IgAN, and the Clinical Guidelines of IgAN in Japan. Levels of u-PCX were measured by sandwich ELISA.


RESULTS
Histologic analysis based on Shigematsu classification revealed a significant correlation between levels of u-PCX and severity of acute extracapillary abnormalities (r=0.72; P<0.001), but levels of urinary protein excretion did not correlate with acute glomerular abnormalities. Levels of urinary protein excretion in patients with segmental sclerosis (n=19) were higher than in patients without (n=22) (0.49 [interquartile range (IQR), 0.20-0.88] g/g creatinine versus 0.20 [IQR, 0.10-0.33] g/g creatinine; P<0.01). The number of urinary podocytes in patients with segmental sclerosis was higher than in patients without (1.05 [IQR, 0.41-1.67] per mg creatinine versus 0.28 [IQR, 0.10-0.66] per mg creatinine; P<0.01).


CONCLUSIONS
Levels of u-PCX and the number of urinary podocytes are associated with histologic abnormalities in adults with IgAN.
Division of Nephrology, Juntendo University Faculty of Medicine, Tokyo, Japan.
Rin
R
Asao
Katsuhiko
K
Asanuma
Fumiko
F
Kodama
Miyuki
M
Akiba-Takagi
Yoshiko
Y
Nagai-Hosoe
Takuto
T
Seki
Yukihiko
Y
Takeda
Isao
I
Ohsawa
Satoshi
S
Mano
Kiyoshi
K
Matsuoka
Hiroyuki
H
Kurosawa
Shinya
S
Ogasawara
Yoshiaki
Y
Hirayama
Sakari
S
Sekine
Satoshi
S
Horikoshi
Masanori
M
Hara
Yasuhiko
Y
Tomino
D000328:Adult; D015415:Biomarkers / Q000097:blood / Q000652:urine; D001706:Biopsy; D003404:Creatinine / Q000097:blood / Q000652:urine; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005922:Glomerulonephritis, IGA / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000473:pathology / Q000652:urine; D005923:Glomerulosclerosis, Focal Segmental / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology / Q000652:urine; D006801:Humans; D007564:Japan; D008297:Male; D050199:Podocytes / Q000378:metabolism* / Q000473:pathology*; D011237:Predictive Value of Tests; D011507:Proteinuria / Q000175:diagnosis / Q000209:etiology / Q000652:urine; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D012795:Sialoglycoproteins / Q000652:urine*; D014556:Urine / Q000166:cytology; D055815:Young Adult
D015415:Biomarkers; D012795:Sialoglycoproteins; C001643:podocalyxin; D003404:Creatinine