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Adriamycin-induced proteinuria in nude mice: an immune-system-mediated toxic effect
A Amore1, G Mazzucco, F Cavallo
1Nephrology and Dialysis, Regina Margherita Children's Hospital, Torino, Italy.
Background:
The renal minimal lesion disease induced in rats by adriamycin (ADR) is generally thought to be consequent to a direct cytotoxic effect of this drug on glomerular epithelial cells. Only recently an altered synthesis of mediators, including reactive oxygen species and monocyte-macrophage cytokines, has been hypothesized.
Methods:
A mouse strain (nude) bearing a congenital thymic aplasia is a suitable experimental animal to evaluate the role of immune reactions in the development of the ADR nephropathy, provided mouse susceptibility to its toxic effect. Therefore, experimental mice were divided into three groups (G) each receiving adriamycin 7.5 mg/kg b.w.: GA (15 heterozygous nu/O mice with normal immune system); GB (15 homozygous nu/nu athymic mice); GC (15 homozygous nu/nu mice which were also splenectomized, irradiated, and treated with anti-asialo Gm1 antibody to abolish NK and decrease macrophage activity). All animals were maintained under pathogen-free conditions. Urinary proteins, albumin and TNF-alpha excretion were measured.
Results:
After 14 days the proteinuria was 43.8+/-1.7 microg/min in GA, 30.2+/-2.9 microg/min in GB (P<0.05) and 12.2+/-2.8 microg/min in GC (GA vs GC, P<0.0001; GB vs GC, P<0.05). Albuminuria gave a similar profile. TNG-alpha urinary excretion was significantly higher in GA (17.3+/-3.2 mU/min) than in GB (5+/-0.6 mU/min, P<0.001) and GC (3.2+/-0.9 mU/min, P<0.001). A significant correlation was found in GA between urinary TNF-alpha and protein losses (r2=0.63 P<0.0001). Kidney tissue homogenates failed to show in each experimental group any evidence of mRNA encoding for TNF-alpha, which was detectable in peripheral mononuclear cells from GA and GB, but undetectable in GC mice. Segmental effacements of glomerular epithelial cell foot process were observed by electron-microscopy in GA only, while they were minimal in GB and absent in GC. Iron colloidal staining for anionic sites on frozen sections always showed a normal pattern.
Conclusions:
Nude mice bearing cellular immunity deficiency are protected from proteinuria following ADR toxicity. An impaired synthesis and release of lymphomonocyte mediators including TNF-alpha could be envisaged.
Insights
Adriamycin (ADR) induced nephropathy is linked to immune responses. Nude mice with cellular immunity deficiency showed protection from ADR toxicity, suggesting impaired mediator release contributes to this protection.
Area of Science:
- Nephrology
- Immunology
- Toxicology
Background:
- Adriamycin (ADR) nephropathy in rats is typically attributed to direct glomerular epithelial cell toxicity.
- Recent hypotheses suggest altered mediator synthesis, including reactive oxygen species and cytokines, plays a role.
Purpose of the Study:
- To evaluate the role of immune reactions in Adriamycin (ADR) nephropathy development.
- To assess the protective effect of cellular immunity deficiency against ADR-induced kidney damage.
Main Methods:
- Used three groups of mice: normal immune system (GA), athymic nude mice (GB), and athymic nude mice with depleted NK and macrophage activity (GC).
- Administered ADR (7.5 mg/kg) to all groups and measured urinary proteins, albumin, and TNF-alpha.
- Assessed glomerular epithelial cell foot process effacement via electron microscopy and TNF-alpha mRNA in tissues and peripheral blood cells.
Main Results:
- Proteinuria and albuminuria were significantly lower in immune-deficient mice (GB and GC) compared to normal mice (GA).
- Urinary TNF-alpha excretion was highest in GA, lower in GB, and lowest in GC, correlating with protein loss in GA.
- TNF-alpha mRNA was detected in peripheral mononuclear cells of GA and GB but not in GC, while kidney tissue showed no TNF-alpha mRNA in any group.
Conclusions:
- Cellular immunity deficiency protects mice from Adriamycin (ADR) induced proteinuria.
- Impaired synthesis and release of lymphomonocyte mediators, such as TNF-alpha, likely contribute to this protection.