Effect of Calcitriol on the Renal Microvasculature Differentiation Disturbances Induced by AT1 Blockade During Nephrogenesis in Rats.

Alterations in the renal vasculature during fetal programming can cause disturbances in renal structure and function that persist into adulthood. Calcitriol can affect cellular differentiation and proliferation, and promote endothelial cell maintenance, each of which is a key event in nephrogenesis. Calcitriol is a negative endocrine regulator of the renin gene. Rats exposed to renin-angiotensin system (RAS) antagonists during lactation have been shown to develop renal disorders, which demonstrated that the RAS may play an important role in mammalian kidney development. We evaluated the effects of calcitriol administration on losartan [angiotensin II receptor antagonist (ANGII), AT1]-induced changes in renal differentiation in rats during lactation. Rats treated with losartan showed alterations in renal function and structure that persisted into adulthood. These disruptions included hydronephrosis, papillary atrophy, endothelial dysfunction, and aberrant endothelial structure. These changes were mitigated by treatment with calcitriol. The results of our study showed that animals exposed to AT1 blockade during lactation exhibited altered renal microvasculature differentiation in adulthood that was attenuated by treatment with calcitriol.

Effects of previous physical training on adriamycin nephropathy and its relationship with endothelial lesions and angiogenesis in the renal cortex.

AIMS: Adriamycin (ADR)-induced nephropathy is one of the most experimental models used in progressive kidney disease. A single dose of this drug induces a progressive and irreversible proteinuria that progresses to focal segmental glomerulosclerosis and tubulointerstitial lesions. Regular physical activity has been considered as a therapeutic intervention in several diseases. This study evaluated the influence of previous physical training in renal damage induced by ADR and the role of endothelial lesions and angiogenesis in this process. MAIN METHODS: Male Wistar rats were subjected or not to treadmill running for 4weeks and then injected with ADR (2.5mg/kg, i.v.) or saline. Twenty-four-hour urine samples were collected for albuminuria measurement, and blood samples were collected to measure plasma creatinine 60days after the injections. The kidneys were removed for histological, immunohistochemical, Western blot and ELISA studies. KEY FINDINGS: ADR-treated rats presented increases in plasma creatinine levels, albuminuria, podocyte damage, and enlargement of the tubular interstitial relative area, as well as higher macrophage numbers in the renal cortex, interleukin (IL)-1ß levels in renal tissue and urinary monocyte chemoattractant protein (MCP)-1, which were associated with reduction in vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS) expressions and peritubular capillary (PTC) density in renal cortex. These alterations were less intense in the animals subjected to previous exercise training. SIGNIFICANCE: Physical training prior to ADR injection reduced the renal damage induced by this drug. This effect was related to angiogenesis and reduction in the endothelial lesions and inflammatory process in the renal cortex of these animals.

Cecropia pachystachya extract attenuated the renal lesion in 5/6 nephrectomized rats by reducing inflammation and renal arginase activity.

ETHNOPHARMACOLOGICAL RELEVANCE: The plant Cecropia pachystachya Trécul has been used in Brazilian folk medicine to treat hypertension, bladder and kidney inflammation and renal diseases. The aim of this study was to evaluate the potential of the aqueous fraction from the ethanolic extract of Cecropia pachystachya (FCP) in the management of hypertension, inflammation and progressive renal disease in rats submitted to 5/6 nephrectomy. MATERIALS AND METHODS: Thirty male Wistar rats submitted to 5/6 nephrectomy (5/6 NE) were untreated (NE) or treated (NE+FCP) with the FCP (0.5g/kg/day). The treatment started 15 days after surgery, and the rats were followed for a period of 60 days. Systolic blood pressure (SBP) and albuminuria were evaluated from 15-60 days after the surgical procedure. Function and estructural renal changes, TGF-ß (transforming growth factor ß), MCP-1 (monocyte chemoattractant protein-1) and nitric oxide (NO) urinary excretion were analyzed. Expression and activity of the renal enzymes arginase (ARG), angiotensin converting enzyme (ACE), and MAP kinase p-JNK expression also were analyzed. RESULTS: The nephrectomized rats developed progressive albuminuria and increased SBP that was less intense in the treated group. There was a reduction in the glomerular filtration rate (GFR) in the nephrectomized rats, which was attenuated by treatment with FCP extract. The treatment with FCP also attenuated the histological changes, reduced the expression and activity of renal arginase, the number of macrophages (ED-1 positive cells) and the p-JNK expression in the renal cortex of the rats submitted to 5/6 NE. The urinary excretion of TGF-ß was less intense in the treated group and was associated with the reduction of the expression and activity of the renal arginase. CONCLUSIONS: These results suggest that the reduction of renal arginase activity, p-JNK and TGF-ß expression can explain the mechanism by which the treatment with C. pachystachya reduced the inflammation and improved renal function. This study presents the potential use of Cecropia pachystachya in the treatment of chronic renal diseases.

Brazilian embauba (Cecropia pachystachya) extract reduces renal lesions in 5/6 nephrectomized rats.

INTRODUCTION: Cecropia pachystachya (CP) is a plant rich in polyphenols which inhibits the angiotensin-converting enzyme (ACE) in vitro. Angiotensin II (AII) has an important role in the renal lesion provoked by 5/6 nephrectomy (NE). This study evaluated the CP extract effect on renal lesions provoked by 5/6 NE. MATERIALS AND METHODS: Male Wistar rats submitted to 5/6 NE were treated or not treated with CP extract and followed for 90 days. Systemic blood pressure (SBP), albuminuria, renal functional and structural parameters, ACE activity, urinary levels of monocyte chemoattrant protein-1 (MCP-1) and transforming growth factor ß (TGF-ß) were evaluated. RESULTS: Albuminuria and hypertension were less intense in the treated (NE+CP) group compared to the untreated (NE) group. CP extract treatment reduced the fall in glomerular filtration rate observed in NE rats. Glomerulosclerosis, tubulointerstitial lesions, increase of macrophages and AII positive cells in the renal cortex, as well as increases in renal ACE activity, urinary levels of MCP-1 and TGF-ß were attenuated in NE rats by CP treatment. CONCLUSIONS: The treatment with CP extract reduced the SBP and functional and structural renal changes in 5/6 NE rats. These effects were associated with decreased AII expression, ACE activity and inflammation in the renal cortex.

Macrophage depletion attenuates chronic cyclosporine A nephrotoxicity.

BACKGROUND: Cyclosporine A (CsA)-induced chronic nephrotoxicity is characterized by renal dysfunction and interstitial fibrosis. Early and progressive renal macrophage influx, correlating with latter interstitial fibrotic areas, has been associated with CsA treatment. This study investigated the role of macrophages, the nitric oxide (NO) pathway, and the oxidative stress on chronic CsA nephrotoxicity. METHODS: The macrophages were depleted by clodronate liposomes. Animals were distributed into four groups: vehicle (olive oil for 21 days), CsA 7.5 mg/kg per day (21 days), CsA plus clodronate (5 mg/mL intraperitoneally on days -4, 1, 4, 11, and 18 of CsA treatment), or vehicle plus clodronate. On day 22, glomerular filtration rate, renal blood flow, renal tubulointerstitial fibrosis, CsA blood levels, serum malondialdehyde and renal tissue immunohistochemistry for macrophages, inducible NO synthase, transforming growth factor-beta, nuclear factor-kbeta, alpha-smooth muscle actin, vimentin, and nitrotyrosine were assessed. RESULTS: CsA-induced increase in the macrophage was prevented by clodronate. Macrophage depletion attenuated the reductions in the glomerular filtration rate and renal blood flow, the development of tubulointerstitial fibrosis, malondialdehyde increase and increases in nuclear factor-kbeta, transforming growth factor-beta, vimentin, inducible NO synthase, and nitrotyrosine expression provoked by CsA. Clodronate did not affect alpha-smooth muscle actin expression and CsA blood levels. CONCLUSIONS: Renal macrophage influx plays an important role in CsA-induced chronic nephrotoxicity. The NO pathway and oxidative stress are likely mechanisms involved in the genesis of this form of renal injury.

Treatment with a p38 MAPK inhibitor attenuates cisplatin nephrotoxicity starting after the beginning of renal damage.

AIMS: Cisplatin (CP) promotes increased production of reactive oxygen species, which can activate p38 mitogen activated protein kinases (p38 MAPKs) leading to apoptosis and increased expression of proinflammatory mediators that intensify the cytotoxic effects of CP. We investigated the effect of the treatment with SB203580, a p38 MAPKs inhibitor, on oxidative stress, on the oxidation-associated signal, p38 MAPK and on apoptosis in CP-injected rats, starting after the beginning of the renal damage. MAIN METHODS: Rats (n=21) were injected with CP (5 mg/kg, i.p.) and 3 and 4 days after some of them (n=8) were treated with SB203580 (0.5 mg/kg, i.p.). Controls (n=6) received saline (i.p.). Two or five days after saline or CP injections, plasma creatinine, urinary volume, sodium and potassium fractional excretions, blood urea nitrogen and urinary lipid peroxidation were measured. The kidneys were removed for histological, apoptosis, immunohistochemical and Western blot studies. KEY FINDINGS: CP caused abnormalities in kidney functions and structure associated with raised urinary peroxidation levels and higher number of apoptotic cells in the outer medulla. The immunostaining studies showed increased numbers of macrophages/monocytes and p-p38 MAPKs positive cells in the renal outer medulla. The increase of p-p38 MAPKs expression was confirmed by Western blot analysis. All of these alterations were attenuated by treatment with SB203580. SIGNIFICANCE: These data suggest that the beneficial effect of SB203580 on CP-induced renal damage might be related, in part, to the blockade of p38 MAPK activation with reduction of the inflammatory process, oxidative stress and apoptotic cell death.

Treatment with a p38 MAPK inhibitor attenuates cisplatin nephrotoxicity starting after the beginning of renal damage.

AIMS: Cisplatin (CP) promotes increased production of reactive oxygen species, which can activate p38 mitogen activated protein kinases (p38 MAPKs) leading to apoptosis and increased expression of proinflammatory mediators that intensify the cytotoxic effects of CP. We investigated the effect of the treatment with SB203580, a p38 MAPKs inhibitor, on oxidative stress, on the oxidation-associated signal, p38 MAPK and on apoptosis in CP-injected rats, starting after the beginning of the renal damage. MAIN METHODS: Rats (n = 21) were injected with CP (5 mg/kg, i.p.) and 3 and 4 days after some of them (n = 8) were treated with SB203580 (0.5 mg/kg, i.p.). Controls (n = 6) received saline (i.p.). Two or five days after saline or CP injections, plasma creatinine, urinary volume, sodium and potassium fractional excretions, blood urea nitrogen and urinary lipid peroxidation were measured. The kidneys were removed for histological, apoptosis, immunohistochemical and Western blot studies. KEY FINDINGS: CP caused abnormalities in kidney functions and structure associated with raised urinary peroxidation levels and higher number of apoptotic cells in the outer medulla. The immunostaining studies showed increased numbers of macrophages/monocytes and p-p38 MAPKs positive cells in the renal outer medulla. The increase of p-p38 MAPKs expression was confirmed by Western blot analysis. All of these alterations were attenuated by treatment with SB203580. SIGNIFICANCE: These data suggest that the beneficial effect of SB203580 on CP-induced renal damage might be related, in part, to the blockade of p38 MAPK activation with reduction of the inflammatory process, oxidative stress and apoptotic cell death.

Effects of resveratrol on glycerol-induced renal injury.

Glycerol-induced renal lesions can have many causes, including increased oxidative stress and inflammation. Resveratrol, a polyphenolic phytoalexin found in grapes and red wine, is an antioxidant agent with anti-inflammatory effects. In the present study, we investigated the possible protective effect of resveratrol on glycerol-induced nephrotoxicity. Male Wistar rats were injected intramuscularly with 8 ml/kg of either 50% glycerol (n=18), glycerol+resveratrol (n=22), 0.15 M saline (n=14), saline+carboxymethylcellulose (n=10) or saline+resveratrol (n=8). The rats were killed 3 days after the injections, at which time the kidneys were removed for histological and immunohistochemical studies and lipid peroxidation determination. Blood and urine samples were collected in order to quantify sodium and creatinine. The results of the histological and immunohistochemical studies were scored according to the extent of damage and immunostaining, respectively, in the cortical tubulointerstitium. Lipid peroxidation was estimated by measuring malondialdehyde in renal tissue samples collected from control rats and glycerol-injected rats. By postinjection day 3, glycerol-only treated rats presented increases in plasma creatinine levels, as well as in fractional excretion of sodium and potassium (P<0.001). These increases were less pronounced in glycerol+resveratrol-treated rats (P<0.05). Cortical expression of macrophages, lymphocytes, nuclear factor-kappa B, heme oxygenase-1 and nitrotyrosine was greater in glycerol-treated rats than in controls (P<0.001). In addition, the histological findings for glycerol-treated rats were characteristic of acute tubular necrosis. Resveratrol attenuated all of these alterations (P<0.001). We conclude that resveratrol ameliorates glycerol-induced renal injury by suppressing the inflammatory process and by inhibiting lipid peroxidation.

Enalapril reduces the expression of nuclear factor-kappaB and c-Jun N-terminal kinase in the renal cortices of five-sixths-nephrectomized rats.

BACKGROUND/AIM: Five-sixths-nephrectomized rats present renal functional and histological abnormalities which are attenuated by enalapril treatment. c-Jun N-terminal kinase (JNK), a mitogen-activated protein kinase, and nuclear factor-kappaB (NF-kappaB) pathways can be activated by angiotensin II which has been implicated in renal injury. The aim of this study was to investigate the effect of enalapril on the expression of NF-kappaB and JNK in renal cortices of five-sixths-nephrectomized rats. METHODS: Of the 65 rats studied, 25 underwent five-sixths nephrectomy and received no treatment, 15 underwent five-sixths nephrectomy and received enalapril, 15 were sham operated and received no treatment, and 10 were sham operated and received enalapril. On postoperative days 15 and 90, systolic blood pressure, glomerular filtration rate, and albumin excretion were determined. The rats were then killed and the kidneys removed for histology and immunohistochemistry. RESULTS: In five-sixths-nephrectomized rats, we observed functional and structural renal alterations, as well as greater NF-kappaB/JNK expression and higher macrophage counts. Enalapril treatment reduced all of these changes. CONCLUSION: The protective effect of enalapril on the kidney of five-sixths-nephrectomized rats might be related to the inhibition of NF-kappaB and JNK activation.

Inhibition of nuclear factor-kappaB activation attenuates tubulointerstitial nephritis induced by gentamicin.

BACKGROUND: Animals treated with gentamicin can show residual areas of interstitial fibrosis in the renal cortex. This study investigated the expression of nuclear factor-kappaB (NF-kappaB), mitogen-activated protein (MAP) kinases and macrophages in the renal cortex and structural and functional renal changes of rats treated with gentamicin or gentamicin + pyrrolidine dithiocarbamate (PDTC), an NF-kappaB inhibitor. METHODS: 38 female Wistar rats were injected with gentamicin, 40 mg/kg, twice a day for 9 days, 38 with gentamicin + PDTC, and 28 with 0.15 M NaCl solution. The animals were killed 5 and 30 days after these injections and the kidneys were removed for histological and immunohistochemical studies. The results of the immunohistochemical studies were scored according to the extent of staining. The fractional interstitial area was determined by morphometry. RESULTS: Gentamicin-treated rats presented a transitory increase in plasma creatinine levels. Increased ED-1, MAP kinases and NF-kappaB staining were also observed in the renal cortex from all gentamicin-treated rats compared to control (p < 0.05). The animals killed on day 30 also presented fibrosis in the renal cortex despite the recovery of renal function. Treatment with PDTC reduced the functional and structural changes induced by gentamicin. CONCLUSIONS: These data show that inhibition of NF-kappaB activation attenuates tubulointerstitial nephritis induced by gentamicin.

Long-term evolution of the acute tubular necrosis (ATN) induced by glycerol: role of myofibroblasts and macrophages.

Late structural changes such as interstitial fibrosis in the renal cortex and tubular atrophy have been detected after severe acute tubular necrosis (ATN). The aim of this study was to investigate the expression of fibronectin, alpha-smooth muscle actin and macrophages during the evolution of the ATN induced by glycerol and their relationship with the late structural changes observed in the kidneys of these animals. Forty-nine male Wistar rats were injected with a 50% glycerol solution, 8 mL/kg (4 mL/kg applied i.m. to each hind leg) and 14 with 0.15 m NaCl solution. Before glycerol injection on day 1, water was removed for 17 h. Blood and urine samples were collected 1 day after the injection to quantify sodium and creatinine. The animals were killed 5, 30 and 60 days after the injections and the kidneys removed for histological and immunohistochemical studies. The results of the histological and immunohistochemical studies were scored according to the extent of lesion or staining in the cortical tubulointerstitium, respectively. The percentage of tubulointerstitial lesions was determined by morphometry. Glycerol-injected rats presented a transitory increase in plasma creatinine levels and in fractional sodium excretion. The immunohistochemical studies showed increased fibronectin, alpha-smooth muscle actin (alpha-SM-actin), TGF-beta and ED-1 (macrophages) staining in the renal cortex from rats killed 5, 30 and 60 days after glycerol injection (P < 0.05) compared to control. The animals killed on day 30 and 60 also presented chronic lesions (fibrosis, tubular dilatation and atrophy) in the renal cortex, despite the recovery of renal function. Macrophages, TGF-beta and myofibroblasts may have contributed to the development of renal fibrosis in these rats.