Gravidez e nefrotoxidade causada pela ciclosporina A: um estudo experimental

Abstract

Cyclosporine A (CsA) is a immunosuppressant drug, whose most serious toxic effect is chronic nephrotoxicity, characterized by decreased glomerular filtration rate and the development of irreversible renal fibrosis. It may go through the placenta to the developing fetus. Currently, a great number of women with childbearing potential is treated by CsA, increasing the chances of pregnancy under the effect of this drug. Our objectives were to assess CsA effects on the renal structure and function during pregnancy. The low-salt-diet (0.06%) model was used in pregnant (P/CsA) and virgin (V/CsA) Munich-Wistar female rats receiving CsA; in virgin (V/VH) and pregnant (P/VH) rats with vehicle at a dosage of 15 mg/kg/day of CsA subcutaneously or vehicle. Glomerular filtration rate (GFR, ml/min/100g) , renal blood flow (RBF, Doppler ultrasound, ml/min), renal vascular resistance (RVR, mmHg/ml/min), blood pressure (BP, intracarotid probe, mmHg), blood levels of CsA (BCsA, radioimmunoassay, ng/ml), urinary volume (UV, ml/min), plasma and urinary creatinine (mg/dl), urine sodium excretion (UNa, mEq/l), sodium excretion fraction (FeNa,%) urinary osmolality (UOsm, m/Osm/K), osmolar clearance (COsm, ml/min), urinary nitric-oxide (NO, griess, umol/mgCr), immunohistochemistry for angiotensin II-positive renal cells and renal histology were measured in the middle and at the end of the gestational period (21 days). Results are presented as mean ± standard error of mean and analyzed by ANOVA and Student-Neuman-Keuls test. After 10 days of treatment, the pregnancy caused significant increases of 27% in the GFR (GC; 1.19 ± 0.04 vs 0.94 ± 0.05 in V/C, p<0.05) and of 36% in RBF (G/C; 4.9 ± 0.2 vs 3.6 ± 0.1 in V/C, p< 0.001) and significant decreases of 13% in MBP (GC; 112 ± 4 vs 129 ± 5 in V/C, p<0.05) and of 29% in RVR ( GC; 24 ± 1 vs 34 ± 2 in VC, p<0.05) of vehicle treated animals. In contrast, in CsA-treated animals, there was no significant GFR increase in pregnancy (20%, G/CsA; 0.95 ± 0.07 vs 0.79 ± 0.07 in V/CsA, p>0.05) nor was there a significant MPB decrease (7%, G/CsA; 110 ± 3 vs 118 ± 4 in V/CsA, p>0.05). The significant RBF increase (38%, G/CsA; 3.3 ± 0.2 vs 2.4 ± 0.1 in V/CsA p<0,01) and significant RVR decrease ( 24%, G/CsA 38 ± 3 vs 50 ± 3 in V/CsA, p<0.05) were maintained in this group. Pregnancy caused a significant decrease of CsA serum levels (G/CsA; 544±58 vs 805±71 in V/CsA, p<0.01). CsA treated animals showed a trend to higher urinary nitric oxide levels, however, the difference was not statistically significant. There was no difference in urinary nitric oxide between virgin and pregnant rats. Pregnancy increased the number of angiotensin II-positive cells in the renal interstitium (3.9 ± 0.6 in G/CsA vs 2.5 ± 0.4 in V/CsA and 4 ± 1.4 in G/C vs 1.9 ± 0.86 in V/C), however these differences did not reach statistical significance. The number of angiotensin II-positive cells in the afferent arteriole was greater in pregnant rats when compared to virgin rats (G/C; 1.3 ± 0.3 vs 0.21 ± 0.2 in V/C) and greater in CsA-treated virgin rats when compared to vehicle-treated rats (V/CsA; 1 ± 0.3 vs 0.21 ± 0.2 in V/C), however these differences were not statistically significant. After 20 days, V and P rats had similar (NS) GFR and RBF decreases and CsA vs Control for GFR (p<0.001), for RBF (p<0.01), and a similar RVR increase (NS). MBP values showed similar decreases in V vs P rats (NS) and a decrease in Csa vs C animals (p<0.05). SCsA was lower in P vs V rats (p<0.001). AII expression in the interstice increased for V/CsA vs V/C rats (p<0.001) and for G/CsA vs P/C rats (p<0.05). The same was observed in the afferent arteriole, for V/CsA vs v/C (p<0.01); however it was not statistically significant for pregnant rats. Only the V/CsA group had an IF score of 0.2 ± 0.1 after 20 days. In the middle of normal pregnancy, CsA altered the renal hemodynamics, impairing both the increase of GFR and the decrease of BP, although the blood levels of the drug were lower in pregnant rats than in virgin rats. The NO urinary system does not seem to be connected to this phenomenon. AII expression in the interstice and in the afferent arteriole was greater for CsA treated-pregnant animals vs controls. Pregnancy did not impair CsA-induced interstitial fibrosis.