Bone marrow-derived mononuclear cells promote improvement in glomerular function in rats with early diabetic nephropathy.

BACKGROUND/AIMS: Diabetic nephropathy is one of the main causes of end-stage renal disease. The present study investigated the effect of mononuclear cell (MC) therapy in rats subjected to diabetic nephropathy. METHODS: Male Wistar rats were divided into control (CTRL), diabetic (DM), CTRL+MC and DM+MC groups. Diabetes was induced by a single injection of streptozotocin (45 mg/kg, i.p.) and, 4 weeks later, 2×10(7) MCs were injected via the jugular vein. RESULTS: The rats in the DM and DM+MC groups showed increased glycemia, glomerular filtration rate and glomerular tuff area versus control groups. The glomerular filtration rate and glomerular tuff area were normalized in the DM+MC group. No alterations were observed in the fractional excretion of electrolytes and proteinuria between the DM and DM+MC groups. TGF-ß1 protein levels in the DM group were significantly increased versus control animals and normalized in the DM+MC group. An increase in ED1(+)/arginase I(+) macrophages and IL-10 renal expression was observed in the DM+MC group versus DM group. CONCLUSIONS: Bone marrow-derived MC therapy was able to prevent glomerular alterations and TGF-ß1 protein overexpression and modulated glomerular arginase I(+) macrophage infiltration in rats subjected to early diabetic nephropathy.

Role of estrogen and progesterone in the modulation of CNG-A1 and Na/K+-ATPase expression in the renal cortex.

The steroid hormones, estrogen and progesterone, are involved mainly in the control of female reproductive functions. Among other effects, estrogen and progesterone can modulate Na(+) reabsorption along the nephron altering the body's hydroelectrolyte balance. In this work, we analyzed the expression of cyclic nucleotide-gated channel A1 (CNG-A1) and α1 Na(+)/K(+)-ATPase subunit in the renal cortex and medulla of female ovariectomized rats and female ovariectomized rats subjected to 10 days of 17ß-estradiol benzoate (2.0 µg/kg body weight) and progesterone (1.7 mg/kg body weight) replacement. Na(+)/K(+) ATPase activity was also measured. Immunofluorescence localization of CNG-A1 in the cortex and medulla was performed in control animals. We observed that CNG-A1 is localized at the basolateral membrane of proximal and distal tubules. Female ovariectomized rats showed low expression of CNG-A1 and low expression and activity of Na(+)/K(+) ATPase in the renal cortex. When female ovariectomized rats were subjected to 17ß-estradiol benzoate replacement, normalization of CNG-A1 expression and Na(+)/K(+) ATPase expression and activity was observed. The replacement of progesterone was not able to recover CNG-A1 expression and Na(+)/K(+) ATPase expression at the control level. Only the activity of Na(+)/K(+) ATPase was able to be recovered at control levels in animals subjected to progesterone replacement. No changes in expression and activity were observed in the renal medulla. The expression of CNG-A1 is higher in cortex compared to medulla. In this work, we observed that estrogen and progesterone act in renal tissues modulating CNG-A1 and Na(+)/K(+) ATPase and these effects could be important in Na(+) and water balance.

Bone marrow mononuclear cells attenuate interstitial fibrosis and stimulate the repair of tubular epithelial cells after unilateral ureteral obstruction.

The growing number of patients suffering from chronic renal disease is a challenge for the development of innovative therapies. Benefits of cell therapy in acute renal diseases in animal models have been reported but seldom for chronic lesions. We present evidence for the improvement of renal morphology in a model of tubulointerstitial fibrosis. Wistar rats were submitted to unilateral ureteral obstruction (UUO), treated with bone-marrow mononuclear cells (UUO+BMMC) infused via the cava vein, and killed on day 14. Labeled BMMC were seen in renal tissue after 7 days in the group UUO+BMMC. UUO+BMMC also showed a reduction in ED1(+) cells and tubular apoptotic cells together with enhanced tubular proliferation. Myofibroblasts were also reduced after BMMC which is consistent with a decrease in collagen deposition (picro Sirius staining) and RT-PCR data showing lower levels of procollagen-I mRNA. Simultaneously, nestin+ cells increased in the interstitium and decreased in the tubules. Double stained nestin(+)/alpha-SMA(+) cells were present only in the interstitium, and their levels did not change after BMMC infusion. These data indicate a renoprotective effect of BMMC through increased tubular cell regeneration, inhibition of tubular cell apoptosis and partially blocking of the inflammatory and fibrotic events that occur after unilateral ureteral obstruction.

Pulmonary lesion induced by low and high positive end-expiratory pressure levels during protective ventilation in experimental acute lung injury.

OBJECTIVE: To investigate the effects of low and high levels of positive end-expiratory pressure (PEEP), without recruitment maneuvers, during lung protective ventilation in an experimental model of acute lung injury (ALI). DESIGN: Prospective, randomized, and controlled experimental study. SETTING: University research laboratory. SUBJECTS: Wistar rats were randomly assigned to control (C) [saline (0.1 mL), intraperitoneally] and ALI [paraquat (15 mg/kg), intraperitoneally] groups. MEASUREMENTS AND MAIN RESULTS: After 24 hours, each group was further randomized into four groups (six rats each) at different PEEP levels = 1.5, 3, 4.5, or 6 cm H2O and ventilated with a constant tidal volume (6 mL/kg) and open thorax. Lung mechanics [static elastance (Est, L) and viscoelastic pressure (DeltaP2, L)] and arterial blood gases were measured before (Pre) and at the end of 1-hour mechanical ventilation (Post). Pulmonary histology (light and electron microscopy) and type III procollagen (PCIII) messenger RNA (mRNA) expression were measured after 1 hour of mechanical ventilation. In ALI group, low and high PEEP levels induced a greater percentage of increase in Est, L (44% and 50%) and DeltaP2, L (56% and 36%) in Post values related to Pre. Low PEEP yielded alveolar collapse whereas high PEEP caused overdistension and atelectasis, with both levels worsening oxygenation and increasing PCIII mRNA expression. CONCLUSIONS: In the present nonrecruited ALI model, protective mechanical ventilation with lower and higher PEEP levels than required for better oxygenation increased Est, L and DeltaP2, L, the amount of atelectasis, and PCIII mRNA expression. PEEP selection titrated for a minimum elastance and maximum oxygenation may prevent lung injury while deviation from these settings may be harmful.

Thyroid hormones stimulate renal expression of CFTR.

CFTR is a multifunctional protein of the ATP binding cassette family that may contribute to overall electrolyte homeostasis by acting as a chloride channel in the kidney. In renal tissues CFTR does not exists only in its full-length form, but also as a kidney-specific, truncated splice variant, TNR-CFTR. In this study we show that both forms of CFTR are regulated by thyroid hormones in rat renal tissue. Four groups of male rats were used: control, hypothyroid, hypothyroid with T(4) treatment and hyperthyroid rats. The hypothyroid rats showed a decrease of both CFTR and TNR-CFTR mRNAs (44%, and 49%, respectively, n=5; p<0.05) and proteins (30% and 37%, respectively, n=5, p<0.05) expressions, compared to control group. In hyperthyroid rats, a significant increase in both CFTR and TRN-CFTR mRNAs expressions (43% and 95%, n=5; p<0.05) and proteins (250% and 38%, respectively, n=5, p<0.05) was observed when compared to control group. Treatment of immortalized rat proximal tubule cells (IRPTC) with T(3) (10(-7)M) produced also an increase of CFTR mRNA expression (95%, n=5, p<0.05). Analysis of the promoter region of CFTR transfected to IRPTC showed that T(3) (10(-7) M) stimulates the CFTR promoter (38%, n=4, p<0.05).