Antibody-induced albuminuria and accelerated focal glomerulosclerosis in the Thy-1.1 transgenic mouse.
BACKGROUND
Podocytes play an important role in the development of proteinuria and focal glomerulosclerosis. Previously we have demonstrated that a combination of two monoclonal antibodies (mAb) against aminopeptidase A (APA), an enzyme present on podocytes, induces a massive acute albuminuria in mice. The present study examined the relationship between the acute antibody-induced albuminuria and the development of focal glomerulosclerosis in the Thy-1.1 transgenic mouse. This mouse expresses a hybrid human-mouse Thy-1.1 antigen on the podocytes, and slowly but spontaneously develops albuminuria and focal glomerulosclerosis.


METHODS
Five-week-old non-albuminuric Thy-1.1 transgenic and non-transgenic control mice were injected with anti-APA and anti-Thy-1.1 mAb or saline. Albuminuria was measured at days 1, 7, 14 and 21. At day 21 kidneys were processed for light microscopy, immunofluorescence, and electron microscopy.


RESULTS
Injection of anti-APA and anti-Thy1.1 mAb in Thy-1.1 transgenic mice induced an albuminuria at day 1 that persisted at day 21. The acute albuminuria after injection of anti-APA mAb was more prominent but transient in non-transgenic mice. In non-trangenic mice no albuminuria could be induced with anti-Thy 1.1 mAb. Light microscopy revealed normal glomeruli at day 1 in all transgenic mice, however, at day 21 advanced glomerulosclerotic lesions were seen in mice injected with either anti-APA mAb (37+/-19% of glomeruli affected) or anti-Thy-1.1 mAb (71+/-5%). Non-transgenic mice did not reveal sclerotic lesions at any time investigated. In the transgenic mice the percentage of focal glomerulosclerosis at day 21 did not correlate with albuminuria at day 21. However, we found a highly significant correlation between percentage of focal glomerulosclerosis and the time-averaged albuminuria over the three-week study period (P < 0.001).


CONCLUSIONS
Injection of a combination of anti-APA or anti-Thy-1.1 mAb into one mo old, non-albuminuric Thy-1.1 transgenic mice induces an acute albuminuria at day 1 that is accompanied by an accelerated focal glomerulosclerosis at day 21. We suggest that the Thy-1.1 transgenic mouse is an excellent model to study specifically the relation between podocytic injury, albuminuria and the development of focal glomerulosclerosis.
Assmann
Karel J M
KJ
Department of Pathology, Division of Nephrology, University Medical Center Nijmegen, PO Box 9101, 6500 HB Nijmegen, The Netherlands. K.Assmann@pathol.azn.nl
van Son
Jacco P H F
JP
Dïjkman
Henry B P M
HB
Mentzel
Stef
S
Wetzels
Jack F M
JF
D000419:Albuminuria / Q000209:etiology* / Q000473:pathology; D000626:Aminopeptidases / Q000502:physiology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D004195:Disease Models, Animal; D005455:Fluorescent Antibody Technique; D005923:Glomerulosclerosis, Focal Segmental / Q000209:etiology* / Q000473:pathology; D043384:Glutamyl Aminopeptidase; D051379:Mice; D008822:Mice, Transgenic; D018800:Thy-1 Antigens / Q000502:physiology*
D000911:Antibodies, Monoclonal; D018800:Thy-1 Antigens; D000626:Aminopeptidases; D043384:Glutamyl Aminopeptidase