Maria Alice Sperto Ferreira Baptista

Loxosceles gaucho venom-induced acute kidney injury--in vivo and in vitro studies.

Background Accidents caused by Loxosceles spider may cause severe systemic reactions, including acute kidney injury (AKI). There are few experimental studies assessing Loxosceles venom effects on kidney function in vivo. Methodology/Principal Findings In order to test Loxosceles gaucho venom (LV) nephrotoxicity and to assess some of the possible mechanisms of renal injury, rats were studied up to 60 minutes after LV 0.24 mg/kg or saline IV injection (control). LV caused a sharp and significant drop in glomerular filtration rate, renal blood flow and urinary output and increased renal vascular resistance, without changing blood pressure. Venom infusion increased significantly serum creatine kinase and aspartate aminotransferase. In the LV group renal histology analysis found acute epithelial tubular cells degenerative changes, presence of cell debris and detached epithelial cells in tubular lumen without glomerular or vascular changes. Immunohistochemistry disclosed renal deposition of myoglobin and hemoglobin. LV did not cause injury to a suspension of fresh proximal tubules isolated from rats. Conclusions/Significance Loxosceles gaucho venom injection caused early AKI, which occurred without blood pressure variation. Changes in glomerular function occurred likely due to renal vasoconstriction and rhabdomyolysis. Direct nephrotoxicity could not be demonstrated in vitro. The development of a consistent model of Loxosceles venom-induced AKI and a better understanding of the mechanisms involved in the renal injury may allow more efficient ways to prevent or attenuate the systemic injury after Loxosceles bite.

Tacrolimus and nonsteroidal anti-inflammatory drugs: an association to be avoided.

Background: Tacrolimus (FK) and nonsteroidal anti-inflammatory drugs (NSAIDs) can cause acute nephrotoxicity. The expanding use of tacrolimus and the intense consumption of NSAIDS increase the chances of their simultaneous use. Methods: Rats receiving a nonselective COX inhibitor (diclofenac, D) and FK or a selective COX-2 inhibitor (rofecoxib, RO) and FK were treated with FK (2 mg/kg/day), D (10 mg/kg/day), RO (3 mg/kg/day), FK+D, FK+RO and vehicle for 7 days on low-salt diet. Results: Both associations significantly impaired glomerular filtration rate (GFR; 0.63 ± 0.06 ml/min/100 g in FK+D, 0.83 ± 0.06 ml/min/100 g in FK+RO) which did not occur with single drug therapy (0.98 ± 0.03 ml/min/100 g in D, 1.06 ± 0.04 ml/min/100 g in RO, 0.99 ± 0.05 ml/min/ 100 g in FK) or vehicle (1.10 ± 0.05 ml/min/100 g). GFR decrease was significantly higher with FK+D. GFR impairment occurred without RBF or RVR major changes. Mild tubular vacuolization and dilatation and acute degenerative changes were observed in tubular cells. FK+D animals showed a marked weight loss, not observed in the other groups. FK+NSAIDs association decreased FK blood levels (1.73 ± 0.3 ng/ml in FK+D, 1.8 ± 0.3 ng/ml in FK+RO, 3.2 ± 0.4 ng/ml in FK, p < 0.05). Conclusions: The association of FK and nonselective or COX-2 selective NSAIDs in salt-depleted animals caused a significant GFR impairment and decreased FK blood levels.

Effect of stem cells seeded onto biomaterial on the progression of experimental chronic kidney disease

Different routes for the administration of bone marrow-derived cells (BMDC) have been proposed to treat the progression of chronic renal failure (CRF). We investigated whether (1) the use of bovine pericardium (BP) as a scaffold for cell therapy would retard the progression of CRF and (2) the efficacy of cell therapy differently impacts distinct degrees of CRF. We used 2/3 and 5/6 models of renal mass reduction to simulate different stages of chronicity. Treatments consisted of BP seeded with either mesenchymal or mononuclear cells implanted in the parenchyma of remnant kidney. Renal function and proteinuria were measured at days 45 and 90 after cell implantation. BMDC treatment reduced glomerulosclerosis, interstitial fibrosis and lymphocytic infiltration. Immunohistochemistry showed decreased macrophage accumulation, proliferative activity and the expression of fibronectin and α-smooth muscle-actin. Our results demonstrate: (1) biomaterial combined with BMDC did retard the progression of experimental CRF; (2) cellular therapy stabilized serum creatinine (sCr), improved creatinine clearance and 1/sCr slope when administered during the less severe stages of CRF; (3) treatment with combined therapy decreased glomerulosclerosis, fibrosis and the expression of fibrogenic molecules; and (4) biomaterials seeded with BMDC can be an alternative route of cellular therapy.

Effect of Cyclosporine A on Glucose Interstitial Concentration in Renal Cortex and Medulla from Rats

Aim: To standardize microdialysis in rat kidneys and address cyclosporine A (CsA) effects on renal cortex and medulla interstitial glucose. Methods: Munich-Wistar rats were treated with vehicle or CsA (15 mg/kg/day) for 3 weeks. Glucose was assessed by spectrophotometry in dialysate samples from cortex, medulla and arterial plasma. Plasma insulin was measured by radioimmunoassay. Renal blood flow (RBF) was measured by Doppler ultrasound. Creatinine and urea were measured by spectrophotometry. Results: CsA significantly increased the plasma levels of urea and creatinine (1.5 ± 0.20 vs. 0.73 ± 0.03 mg/dl in controls, p < 0.05). Medullary glucose in control was 44% lower than arterial glucose (56 ± 6 vs. 101 ± 8 mg/dl, p < 0.05). At the same time, CsA increased arterial (163 ± 35 vs. 101 ± 8 mg/dl in controls, p < 0.05) and medullary interstitial glucose (100 ± 18 vs. 56 ± 6 mg/dl in controls, p < 0.05), but did not affect cortical glucose (114 ± 21 vs. 90 ± 11 mg/dl in controls). These changes occurred in the presence of a decreased plasma insulin level (2.7 ± 0.2 vs. 9.3 ± 0.4 µU/ml in controls, p < 0.05). The increment in medullary glucose in CsA group occurred despite a reduction in RBF (4.6 ± 0.8 vs. 6.5 ± 1.0 ml/min/kidney in controls, p < 0.05). Conclusions: Microdialysis was an adequate tool to investigate in vivo regulation of renal glucose metabolism. Renal glucose uptake was dependent on medullary cells and CsA treatment induced diabetogenic effects on renal medulla in situ.

Preimplantation Kidney Biopsies of Extended Criteria Donors Have a Heavier Inflammatory Burden Than Kidneys From Standard Criteria Donors

Background Donors after brain death develop a systemic proinflammatory state that may predispose the kidneys to injury after transplantation. Because it is not known whether this inflammatory environment similarly affects the kidneys from expanded criteria donor (ECD) and standard criteria donors (SCD), we sought to evaluate differences in the gene expression of inflammatory cytokines in preimplantation biopsies (PIBx) from ECD and SCD kidneys. Methods Cytokines gene expression was measured in 80 PIBx (SCD, 52; ECD, 28) and associated with donor variables. Results Normal histology and chronic histological lesions were not different between both types of kidneys. ECD kidneys showed significant increase in the transcripts of MCP-1, RANTES, TGF-&bgr;1, and IL-10 when compared with SCD. Kidneys presenting normal histology had similar inflammatory profile except by a higher expression of RANTES observed in ECD (P = 0.04). Interstitial fibrosis and tubular atrophy (interstitial fibrosis and tubular atrophy ≥ 1) were associated with higher expression of TGF-&bgr;1, RANTES, and IL-10 in ECD compared with SCD kidneys. Cold ischemia time of 24 hours or longer was significantly associated with upregulation of FOXP3, MCP-1, RANTES, and IL10, whereas longer duration of donor hospitalization significantly increased gene expression of all markers. High FOXP3 expression was also associated with lower level of serum creatinine at 1 year. Donor age was not associated with any of the transcripts studied. Conclusions PIBx of ECD exhibit a higher gene expression of inflammatory cytokines when compared with SCD kidneys. This molecular profile may be a specific ECD kidney response to brain death and may help to predict the posttransplant outcomes of ECD recipients.

Validation of an Experimental Model to Study Less Severe Chronic Renal Failure.

ABSTRACT Purpose: The 5/6 nephrectomy, mimics the stages of human chronic renal failure (CRF), but the procedure causes severe renal functional and morphological damage that could interfere with the evaluation of therapies for slowing the progression of the disease. This study summarizes the results of renal function, histology, and immunohistochemical findings in rats undergoing a 2/3 nephrectomy. Methods: The rats were distributed in groups according to the type of nephrectomy: CRF5/6: induced by a 5/6 renal mass reduction and CRF2/3: less severe CRF. The body weight and blood pressure were monitored, and the serum creatinine (SCr), creatinine clearance (CCr), urine osmolality, and 24-h proteinuria (PT24h) were measured. CRF progression was evaluated by the rate of decline of CCr (RCCr). Histology and immunohistochemistry were performed in the remnant kidneys. Statistical analysis was done by unpaired t-test, and a P-value < 0.05 was taken as a statistical significance. Results: Compared to the CRF5/6 group, the CRF2/3 model had a lower SCr, PT24h, CCr, and variations of the SCr from baseline. The disease progression was also significantly slower. The renal histopathological findings revealed fewer chronic lesions in rats with CRF2/3. Similarly, we observed less macrophage accumulation as well as lower proliferative activity and expression of fibronectin and a-smooth muscle-actin in the CRF2/3 model. Conclusions: The CRF2/3 model presented with a pattern of less severe CRF, functionally and morphologically, compared to the classical CRF5/6 model, and the CRF2/3 model may be useful for evaluating therapeutic interventions that target the early stages of CRF.