Altered expression of aquaporin-2 in human explants with chronic renal allograft dysfunction.
OBJECTIVE
To investigate the distribution of aquaporins, a recently discovered family of transmembrane water channels, in human renal explants, with specific reference to chronic renal allograft dysfunction (CRAD).


METHODS
Immunohistochemistry for aquaporin-1 and -2 was used in 11 explants, of which five had clinically and histologically confirmed CRAD. Controls were taken from the six explants unaffected by CRAD and from histologically normal areas of six kidneys excised for renal tumours.


RESULTS
In the renal tumour control group, aquaporin-1 immunoreactivity was detected in the glomerular endothelium, Bowman's capsule, the proximal convoluted tubules and the thin limb of the loop of Henle, whereas immunoreactivity for aquaporin-2 was detected in the collecting ducts only. Of the explants without CRAD, where architecture was preserved, immunoreactivity for aquaporin-1 and -2 was the same as in the renal tumour controls. In the two explants with no CRAD and loss of collecting ducts, there was no aquaporin-2 immunoreactivity. In five explants with CRAD, immunoreactivity for aquaporin-2 was decreased or absent from the medulla to the cortex. The apparent decreased immunoreactivity of aquaporin-1 in this group was secondary to a decrease in the number of viable proximal tubules.


CONCLUSIONS
There was less aquaporin-2 immunoreactivity in human renal explants diagnosed with CRAD, starting from the medullary region. In explants with no CRAD and viable collecting ducts, or in normal controls, aquaporin-2 immunoreactivity remained unchanged. Aquaporins might be useful as markers for CRAD.
Ho
Kossen M T
KM
Department of Surgery, Queen Mary Hospital, University of Hong Kong, Hong Kong SAR, China. lmh0232@yahoo.com.hk
Li
Amy Z L
AZ
Yiu
Ming K
MK
Lee
Kam C
KC
Lui
Vincent C H
VC
Fung
Peter C W
PC
Yiu
Tim F
TF
Tam
Paul K H
PK
D051399:Aquaporin 2; D020346:Aquaporins / Q000378:metabolism*; D016022:Case-Control Studies; D002908:Chronic Disease; D006801:Humans; D007150:Immunohistochemistry; D007668:Kidney / Q000378:metabolism*; D007680:Kidney Neoplasms / Q000378:metabolism / Q000601:surgery; D016030:Kidney Transplantation / Q000473:pathology; D007687:Kidney Tubules, Proximal / Q000378:metabolism; D011183:Postoperative Complications / Q000209:etiology / Q000378:metabolism*; D014184:Transplantation, Homologous
C496023:AQP2 protein, human; D051399:Aquaporin 2; D020346:Aquaporins