Induction of Proteinuria by Adriamycin or Bovine Serum Albumin in the Mouse

To establish models of proteinuria in the mouse, BALB/c mice were injected with puromycin aminonucleoside (PAN, 1.5 or 4.5 mg/l0 g body weight), adriamycin (AD, 0.2 mg/l0 g body weight) intravenously or bovine serum albumin (BSA, 100 mg/l0 g body weight) intraperitoneally. Proteinuria was measured as the ratio of urinary albumin (μg/ml) to creatinine (mg/dl) and further characterized by isotyping the immunoglobulin. Although not obtained with PAN (followed for 4 weeks), proteinuria was readily attained in the mouse after treatment with AD or BSA. Most AD-treated mice (5/7) developed an abrupt increase of proteinuria at day 2 after injection, with the ratio of urinary albumin to creatinine in the range 0.28-0.45. The degree of proteinuria increased with time and all mice tested (7/7) showed overt proteinuria at day 4. These mice became anuric at day 5 and died at days 6 and 7. For BSA, 4 h after administration, four of seven mice showed enhanced proteinuria, lasting 8 h with urinary albumin and creatinine in a ratio < 0.05. Isotyping of urine samples collected at the time of heavy proteinuria (ratio of urinary albumin to creatinine: > 0.40 for AD-treated mice, > 0.15 for BSA-treated mice) showed that all of the mice (7/7) with AD-induced proteinuria (ADp) and three of four mice with BSA-induced proteinuria (BSAp) revealed urinary IgG2b and IgA, while only one of seven control mice showed IgG2b alone in urine. The mice were sacrificed at the time they presented with heavy proteinura for pathologic and anionic studies on renal tissues. Under the light microscope the glomeruli showed shrunken tufts with mesangial widening in ADp mice. In BSAp or PAN-treated mice, no histological alterations were observed by light microscopy. An electron microscope kinetic study on the effacement of epithelial foot processes was also performed. In ADp mice, obliteration of epithelial foot processes increased with the time after AD administration and, in a small proportion of glomeruli, mesangial vacuolization was observed. In contrast, all glomeruli examined in BSAp or PAN-treated mice were normal. The glomerular capillary and mesangium in all ADp and BSAp mice showed intact charge expression. In summary, two mouse models of proteinuria induced with AD or BSA showed combined albuminuria and immunoglobulinuria (IgG2b and IgA), accompanied by intact glomerular polyanions but distinct histological and ultrastructural alterations. Data from these experiments indicate that a change in size-dependent, but not charge-dependent, glomerular permselectivity might contribute to the induced proteinuria. These models may be useful to explore the mechanism of proteinuria and relevant glomerulonephropathies in mice.