Effects of mycophenolate mofetil and lisinopril on collagen deposition in unilateral ureteral obstruction in rats

Sulforaphane protects from kidney damage during the release of unilateral ureteral obstruction (RUUO) by activating nuclear factor erythroid 2-related factor 2 (Nrf2): Role of antioxidant, anti-inflammatory, and antiapoptotic mechanisms

Releasing unilateral ureteral obstruction (RUUO) is the gold standard for decreasing renal damage induced during unilateral ureteral obstruction (UUO); however, the complete recovery after RUUO depends on factors such as the time and severity of obstruction and kidney contralateral compensatory mechanisms. Interestingly, previous studies have shown that kidney damage markers such as oxidative stress, inflammation, and apoptosis are present and even increase after removal obstruction. To date, previous therapeutic strategies have been used to potentiate the recovery of renal function after RUUO; however, the mechanisms involving renal damage reduction are poorly described and sometimes focus on the recovery of renal functionality. Furthermore, using natural antioxidants has not been completely studied in the RUUO model. In this study, we selected sulforaphane (SFN) because it activates the nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor that induces an antioxidant response, decreasing oxidative stress and inflammation, preventing apoptosis. Thus, we pre-administrated SFN on the second day after UUO until day five, where we released the obstruction on the three days after UUO. Then, we assessed oxidative stress, inflammation, and apoptosis markers. Interestingly, we found that SFN administration in the RUUO model activated Nrf2, inducing its translocation to the nucleus to activate its target proteins. Thus, the Nrf2 activation upregulated glutathione (GSH) content and the antioxidant enzymes catalase, glutathione peroxidase (GPx), and glutathione reductase (GR), which reduced the oxidative stress markers. Moreover, the improvement of antioxidant response by SFN restored S-glutathionylation in the mitochondrial fraction. Activated Nrf2 also reduced inflammation by lessening the nucleotide-binding domain-like receptor family pyrin domain containing 3 and interleukin 1β (IL-1β) production. Reducing oxidative stress and inflammation prevented apoptosis by avoiding caspase 3 cleavage and increasing B-cell lymphoma 2 (Bcl2) levels. Taken together, the obtained results in our study showed that the upregulation of Nrf2 by SFN decreases oxidative stress, preventing inflammation and apoptosis cell death during the release of UUO.

Effects of mycophenolate mofetil on kidney function and phosphorylation status of renal proteins in Alport COL4A3-deficient mice

Background

We investigated the effects of mycophenolate mofetil (MMF) on kidney function and on protein phosphorylation in a mouse model for the human Alport syndrome.

Methods

COL4A3-deficient (COL4A3−/−) mice were randomly allocated to receive a placebo (PLC COL4A3−/−) or MMF treatment (MMF COL4A3−/−). Wild type mice (WT) were used as controls. Changes in serum creatinine, total protein and blood urea nitrogen (BUN), concentrations of mycophenolic acid (MPA) and its glucuronide metabolite (MPAG), serum protein electrophoresis, urine dipstick chemistry and sediment were measured. Changes in the phosphorylation status of renal proteins and histology were analyzed.

Results

MMF influenced kidney function and protein phosphorylation. Serum creatinine and BUN were lower in MMF treated compared to PLC treated COL4A3−/− mice. Serum albumin and alpha-1 globulins were significantly decreased while serum creatinine, alpha-2 globulins, urine dipstick protein, leukocyte esterase, hemoglobin and red blood cells were all increased in both COL4A3−/− groups compared to WT. Differential 2DE-gel analysis identified six phosphorylated kidney protein spots that were significantly altered by MMF.

Conclusions

These data suggest that the MMF treatment in this murine model moderately improved kidney function and reversed the phosphorylation status of six renal phosphoprotein spots to that seen in WT mice.

Electronic supplementary material

The online version of this article (doi:10.1186/s12953-014-0056-z) contains supplementary material, which is available to authorized users.

Netrin-1 attenuates the progression of renal dysfunction by inhibiting peritubular capillary loss and hypoxia in 5/6 nephrectomized rats

BACKGROUND/AIMS

The aim of this study was to investigate the effect of netrin-1 on peritubular capillary (PTC) loss and hypoxia in 5/6 nephrectomized (Nx) rats.

METHODS

Male Sprague-Dawley rats were divided into three groups (n = 10 rats/group): sham-operated rats treated with control adenovirus; 5/6 Nx rats treated with control adenovirus; and 5/6 Nx rats treated with recombinant adenovirus mediated netrin-1 gene (Ad-netrin-1) therapy. Rats were killed 12 weeks after surgery. Blood urea nitrogen (BUN), serum creatinine (Scr) and 24-h urinary albumin excretion rates were measured. Pathological changes in renal tissues were analyzed histologically. The concentration of netrin-1, CD34, and hypoxia-inducible factor-1α (HIF-1α) were analyzed by immunohistochemistry, Western blotting and real-time PCR.

RESULTS

Renal function and histopathological damage were significantly improved in Adnetrin-1 treated 5/6 Nx rats, compared with rats treated with the control adenovirus in the 5/6 Nx group. Furthermore, Ad-netrin-1 treatment induced a significant increase in renal PTC density, accompanied by a significant decrease in HIF-1α expression.

CONCLUSION

Adenovirus mediated netrin-1 treatment attenuates PTC damage, relieves tissues hypoxia and improves renal function, thus alleviating renal pathological changes and interstitial fibrosis in 5/6 Nx rats.

Anticubilin antisense RNA ameliorates adriamycin-induced tubulointerstitial injury in experimental rats

This study was designed to determine the effects of in vivo anticubilin antisense RNA on the uptake of albumin in tubules and on the tubulointerstitial injury in adriamycin-induced proteinuric rats. Adriamycin-treated rats were subjected to intrarenal delivery of adenoviral vectors encoding empty plasmid, cubilin sense RNA expression vector pAd-CUB or anticubilin antisense RNA expression vector pAd-ACUB on day 3. On days 14 and 28, half of the rats in each group were randomly selected to be killed, and blood samples, kidney tissues and 24-hour urine were collected. The diseased rats treated with pAdEasy-ACUB showed a 60% decrease in serum creatinine and glomerular filtration rate. Interestingly, the anticubilin antisense treatment led to a marked increase in albuminuria. Antisense treatment attenuated the histologic changes on both day 14 and day 28. The antisense treatment induced more than 60% recovery of adriamycin-induced injury, accompanied with 85% knockdown in the expression of cubilin protein and markedly decreased albumin deposition. Adriamycin induced an increase in the expression of monocyte chemoattractant protein-1, transforming growth factor-β and regulated on activation in normal T-cell expressed and secreted and the number of infiltrating cells, which was reversed by the antisense treatment. Anticubilin antisense RNA delivered by an adenoviral vector ameliorates albuminuria-induced glomerulosclerosis and tubulointerstitial damage in adriamycin nephrotic rats, indicating that cubilin could be a potential therapeutic target in proteinuric nephropathy.

Effects of ligustrazine on ureteral obstruction-induced renal tubulointerstitial fibrosis

Ligustrazine (LIG) is a purified and chemically identified component of the Chinese herb Ligusticum wallichii Franchat. It is a potent blocker of vasoconstriction and has strong scavenger of oxygen free radicals. We investigated the effect of LIG on renal tubulointerstitial fibrosis using a rat model of unilateral ureteral obstruction. Ligustrazine treatment significantly reduced the scores of interstitial collagen deposition, amounts of hydroxyproline, the density of myofibroblasts and macrophages, and amounts of transforming growth factor-β1 (TGF-β1) and connective tissue growth factor (CTGF) compared with their level in a saline-treated control group. Using quantitative polymerase chain reaction we found that LIG treatment significantly reduced the mRNA expression of TGF-β1, CTGF, monocyte chemoattractant protein-1 and osteopontin. Moreover, the mRNA expression of hepatocyte growth factor and bone morphogenetic protein-7 were significantly increased by LIG. In vitro, LIG inhibited the TGF-β1-induced loss of cytokeratin-18 expression and de novo increase of the expression of α-smooth muscle actin of HK-2 cells in a dose-dependent manner, which suggested that LIG could restrain the process of epithelial-myofibroblast transition of tubular epithelial cells. This study indicates that LIG can attenuate renal tubulointerstitial fibrosis. It might be useful as a potential candidate in the treatment of chronic renal diseases.

Recoverability of renal function after relief of chronic partial unilateral ureteric obstruction: The effect of an angiotensin-converting enzyme inhibitor (enalapril)

Objectives

We evaluated the effect of an angiotensin-converting enzyme inhibitor (enalapril) on renal function during and after the relief of partial unilateral ureteric obstruction (UUO).

Materials and methods

Thirty-two male mongrel dogs were classified into three groups: sham (eight), control (12; left partial UUO + no medication) and study (12; left partial UUO + enalapril). Dogs in the study and control groups were subjected to 4 weeks of partial UUO. After that, the dogs were re-opened and subjected to Lich-Gregoir vesico-ureteric re-implantation, and were killed humanely by the end of the eighth week after relief of obstruction. The study and control groups were evaluated at baseline, after 4 weeks of obstruction and at 4 and 8 weeks after relief of obstruction, by measuring selective creatinine clearance (CCr), selective renographic clearance (RCr) and renal resistive index (RI). The sham group had sham surgery at 4 and 8 weeks and was evaluated as the other two groups.

Results

Sham surgery showed no significant effect on any of the evaluated variables. Compared with the control, enalapril offset the reductions of CCr and RCr by an extra 11% and 12% of the basal values by the end of the fourth week of obstruction, respectively. Moreover, compared with the control, enalapril enhanced the recovery of CCr by an extra 10% and of RCr by an extra 23% of the basal values at 8 weeks after relief of the 4-week obstruction. In addition, the increase in RI was significantly less in the enalapril group.

Conclusion

Enalapril decreases the deterioration of renal function in partial UUO and enhances the recoverability of renal function after relief of obstruction.

The anti-fibrotic effect of mycophenolic acid-induced neutral endopeptidase

Mycophenolic acid (MPA) appears to have anti-fibrotic effects, but the molecular mechanisms underlying this are unknown. We prospectively studied 35 stable kidney transplant recipients maintained on cyclosporine and azathioprine. We converted 20 patients from azathioprine to enteric-coated mycophenolate sodium (EC-MPS) and continued the remaining 15 patients on azathioprine. Exploratory mRNA expression profiling, performed on five randomly selected EC-MPS patients, revealed significant upregulation of neutral endopeptidase (NEP), which is an enzyme that degrades angiotensin II. We confirmed these microarray data by measuring levels of NEP expression in all subjects; in addition, we found that NEP gene expression correlated inversely with proteinuria. In an additional 33 patients, glomerular and tubular NEP protein levels from renal graft biopsies were significantly higher among the 13 patients receiving cyclosporine + EC-MPS than among the 12 patients receiving cyclosporine + azathioprine or 8 patients receiving cyclosporine alone. Glomerular NEP expression inversely correlated with glomerulosclerosis and proteinuria, and tubular NEP expression inversely correlated with interstitial fibrosis. Incubation of human proximal tubular cells with MPA increased NEP gene expression in a dose- and time-dependent manner. Moreover, MPA reduced angiotensin II-induced expression of the profibrotic factor plasminogen activator inhibitor-1, and a specific NEP inhibitor completely reversed this effect. Taken together, our data suggest that MPA directly induces expression of neutral endopeptidase, which may reduce proteinuria and slow the progression of renal damage in kidney transplant recipients.

Effect of the inosine 5'-monophosphate dehydrogenase inhibitor BMS-566419 on renal fibrosis in unilateral ureteral obstruction in rats

Chronic allograft nephropathy (CAN) is a major cause of late allograft loss. One morphological characteristic of CAN is renal interstitial fibrosis. Mycophenolate mofetil (MMF), the inosine 5'-monophosphate dehydrogenase (IMPDH) inhibitor, has been reported to attenuate the progression of renal interstitial fibrosis. However, the question of whether the newly synthesized IMPDH inhibitors with structures different from MMF have an antifibrotic effect remains unanswered. We evaluated the antifibrotic effects of BMS-566419, a chemically synthesized IMPDH inhibitor, using an experimental rat model, unilateral ureteral obstruction (UUO), in comparison with those of MMF. Expression levels of monocyte chemoattractant protein-1 (MCP-1) and transforming growth factor-beta1 (TGF-β1), which play important roles in UUO-induced renal fibrosis, were also investigated to determine the mechanism by which BMS-566419 affects the progression of renal fibrosis. After 14 days of UUO, interstitial fibrosis was frequently observed in the renal cortex of rats administered vehicle control. BMS-566419 by oral administration showed a significant and dose-dependent suppressive effect on UUO-induced renal fibrosis in histopathological experiments. BMS-566419 treatment also decreased collagen content, as indicated by hydroxyproline concentration, and the expression of collagen type 1 mRNA. BMS-566419 also decreased the expression of mRNA for both MCP-1 and TGF-β1. The antifibrotic effects of treatment with BMS-566419 at 60 mg/kg seemed comparable to those with MMF at 40 mg/kg. These results suggest that BMS-566419 and other chemically synthesized IMPDH inhibitors have beneficial pharmacological effects similar to those of MMF, and are potential pharmaceutical candidates in the treatment of fibrotic renal disease, including CAN.

A reduction of unilateral ureteral obstruction-induced renal fibrosis by a therapy combining valsartan with aliskiren

The protective effect of combination therapy with valsartan and aliskiren against renal fibrosis remains to be defined. This study was undertaken to examine the protective effects of the combination of valsartan and aliskiren against renal fibrosis induced by unilateral ureteral obstruction (UUO). Combination therapy with valsartan (15 mg·kg(-1)·day(-1)) and aliskiren (10 mg·kg(-1)·day(-1)), valsartan monotherapy (30 mg·kg(-1)·day(-1)), and aliskiren monotherapy (20 mg·kg(-1)·day(-1)) all significantly ameliorated the increase in blood urea nitrogen and the degree of hydronephrosis determined by the increase in weight and length of the obstructed kidney. The dose titration study and blood pressure measurement confirmed that the combination therapy provided a greater benefit independent of the vasodilatory effect. There were no significant changes in serum levels of creatinine, sodium, and potassium in UUO rats and any treatment groups. Combination therapy also attenuated UUO-related increases in the scores of tubular dilatation, interstitial volume, interstitial collagen deposition, α-smooth muscle actin, the activation of ERK 1/2, the infiltration of monocytes/macrophages, the mRNA expression of snail-1, and transforming growth factor-β1 to a greater extent compared with aliskiren or valsartan used alone. The mRNA expression of renin and the (pro)renin receptor significantly increased after UUO. Combination therapy and monotherapy of valsartan and aliskiren had a comparable enhancing effect on the mRNA expression of renin, whereas all these treatments did not affect the expression of the (pro)renin receptor. In conclusion, a direct renin inhibitor in conjunction with an angiotensin II receptor blocker exerts increased renal protection against renal fibrosis and inflammation during obstruction over either agent alone.

Pivotal role of CD4+ T cells in renal fibrosis following ureteric obstruction

Tubulointerstitial fibrosis is a common consequence of a diverse range of kidney diseases that lead to end-stage renal failure. The degree of fibrosis is related to leukocyte infiltration. Here, we determined the role of different T cell populations on renal fibrosis in the well-characterized mouse model of unilateral ureteric obstruction. Depletion of CD4(+) T cells in wild-type mice with a monoclonal antibody significantly reduced the amount of interstitial expansion and collagen deposition after 2 weeks of obstruction. Reconstitution of lymphopenic RAG knockout mice with purified CD4(+) but not CD8(+) T cells, prior to ureteric obstruction, resulted in a significant increase in interstitial expansion and collagen deposition. Wild-type mice had significantly greater interstitial expansion and collagen deposition compared with lymphopenic RAG(-/-) mice, following ureteric obstruction; however, macrophage infiltration was equivalent in all groups. Thus, our results suggest that renal injury with subsequent fibrosis is likely to be a multifactorial process, with different arms of the immune system involved at different stages. In this ureteric obstruction model, we found a critical role for CD4(+) T cells in kidney fibrosis. These cells could be a potential target of therapeutic intervention to prevent excessive fibrosis and loss of function due to renal injury.

Bone marrow mononuclear cells shift bioactive lipid pattern in injured kidney towards tissue repair in rats with unilateral ureteral obstruction

BACKGROUND

Bioactive lipids are important in tissue injury and regeneration. Ceramide (Cer) is known for its pro-apoptotic action and sphingosine-1-phosphate (S1P) for inducing proliferation and cell survival; diacylglycerol (DAG) and lysophosphatidic acid (LPA) are involved in various signalling pathways including modulation of ion transport. LPA signalling through its receptor LPA(1) is also related to the progression of fibrosis. This study investigated the modulation of lipid signalling pathways induced by administration of bone marrow-derived mononuclear cells (BMMC) in chronic kidney disease.

METHODS

Unilateral ureteral obstruction (UUO) was followed by intravenous injection of ∼2 × 10(7) BMMC. Controls were UUO group treated with buffered solution and sham-operated group. Animals were killed 14 days after surgery, and lipid phosphorylation assays and immunoblotting were performed on the kidney homogenates.

RESULTS

More DAG was available in the UUO rats (2.4 ± 0.4 and 2.4 ± 0.3 vs 1.0 ± 0.2 pmol (32)PA mg(-)(1) min(-)(1), in UUO and UUO + BMMC vs SHAM). Sphingosine kinase was 150 ± 12% more active in UUO + BMMC than in UUO and SHAM. Cer levels were 76 ± 7% lower in the UUO + BMMC than UUO. LPA receptor type 1 (LPA(1)) expression was 169 ± 7% higher in the UUO group than in UUO + BMMC and SHAM. BMMC maintain control levels of Ca(2+)-ATPase expression altered by UUO by 40%.

CONCLUSIONS

BMMC infusion modulated diverse lipid signalling pathways and protein expression, shifted sphingolipid metabolism toward a regenerative pattern and favourably reduced the levels of a receptor involved in the progression of tissue fibrosis. These results strengthen the benefits of BMMC treatment and give insight into its paracrine mechanisms of action.

Role of inflammation in túbulo-interstitial damage associated to obstructive nephropathy

Obstructive nephropathy is characterized by an inflammatory state in the kidney, that is promoted by cytokines and growth factors produced by damaged tubular cells, infiltrated macrophages and accumulated myofibroblasts. This inflammatory state contributes to tubular atrophy and interstitial fibrosis characteristic of obstructive nephropathy. Accumulation of leukocytes, especially macrophages and T lymphocytes, in the renal interstitium is strongly associated to the progression of renal injury. Proinflammatory cytokines, NF-κB activation, adhesion molecules, chemokines, growth factors, NO and oxidative stress contribute in different ways to progressive renal damage induced by obstructive nephropathy, as they induce leukocytes recruitment, tubular cell apoptosis and interstitial fibrosis. Increased angiotensin II production, increased oxidative stress and high levels of proinflammatory cytokines contribute to NF-κB activation which in turn induce the expression of adhesion molecules and chemokines responsible for leukocyte recruitment and iNOS and cytokines overexpression, which aggravates the inflammatory response in the damaged kidney. In this manuscript we revise the different events and regulatory mechanisms involved in inflammation associated to obstructive nephropathy.

Amitriptyline attenuates interstitial inflammation and ameliorates the progression of renal fibrosis

Amitriptyline is a pleiotropic tricyclic antidepressant, which has anti-oxidant and anti-inflammatory properties. We tested whether amitriptyline might be useful in the treatment of chronic renal disease using the mouse model of unilateral ureteral obstruction. Amitriptyline caused a significant reduction of interstitial fibrosis, determined by Masson's staining, with minimal myofibroblast formation and macrophage infiltration following ureteral obstruction. Using quantitative PCR we found that this treatment significantly reduced the expression of key molecular markers of progressive tubulointerstitial injury such as osteopontin, MCP-1, ICAM-1, and TGF-beta1 compared to their level in a saline-treated control group. Sublethal X-irradiation or mycophenolate mofetil, treatments that reduce inflammation, were comparable to amitriptyline in the reduction of interstitial fibrosis and macrophage infiltration. These studies in animals suggest that amitriptyline is worth testing as a therapeutic agent that might preserve renal function by blocking inflammation and renal fibrosis.

Combined Prednisone and Mycophenolate Mofetil Treatment for Retroperitoneal Fibrosis

PURPOSE

We determined the efficacy of a combination of corticosteroids and mycophenolate mofetil for retroperitoneal fibrosis.

MATERIALS AND METHODS

We performed a prospective observational study of the treatment of 7 patients with biopsy proven retroperitoneal fibrosis. Patients were treated with 40 mg prednisone daily with a gradual taper over 6 months. Mycophenolate mofetil was administered at a starting dose of 1,000 mg twice daily and continued for 6 months following resolution of systemic symptoms and extubation of affected ureters. Outcomes included normalization of laboratory evidence of inflammation, regression of fibrosis by computerized tomography and the ability to discontinue ureteral stents.

RESULTS

Seven patients were treated with mycophenolate mofetil and prednisone. Five of the 7 patients had bilateral ureteral obstruction and 1 had unilateral obstruction requiring ureteral stents. Baseline and followup laboratory values were C-reactive protein 8.9 and 1.3 mg/dl (p=0.07), hemoglobin 10.7 and 12.7 gm/dl (p=0.001), erythrocyte sedimentation rate 76 and 14.5 mm per hour (p=0.015) and serum creatinine 3.32 and 1.08 mg/dl (p=0.07), respectively. Six of the 7 patients had a mean 32% regression of the retroperitoneal mass on computerized tomography. Ten of the 11 obstructed ureters were free of obstruction following ureteral stent removal. The mean time to stent removal was 10.5 months. One patient had a distal ureteral stricture and continued to require decompression. There were no treatment related side affects.

CONCLUSIONS

Mycophenolate mofetil combined with prednisone was safe and efficacious in this small cohort of patients with retroperitoneal fibrosis. Larger trials are needed to confirm these results.

Antifibrotic actions of mycophenolic acid

Mycophenolic acid (MPA) is a highly selective, non-competitive and reversible inhibitor of the inosine monophosphate dehydrogenase (IMPDH), the rate-limiting enzyme in the de novo biosynthesis of guanosine nucleotides. Mycophenolate mofetil (MMF, the ester prodrug of MPA) strongly inhibits both T- and B-lymphocyte proliferation and has now been widely used in the prevention of acute and chronic allograft rejection. Recent evidence, however, suggests that MMF is also capable of inhibiting the proliferation of non-immune cells. In various cell lines, e.g. smooth muscle cells, renal tubular cells, mesangial cells, and fibroblasts, MPA reduced or even abrogated proliferation in response to proliferative stimuli. In animal studies, MMF ameliorated renal lesions in immune-mediated disease, e.g. in the Anti-Thy 1.1 model and experimental lupus nephritis, but was also effective in non-immune-mediated renal damage, e.g. in the rat remnant kidney model or in a model of chronic cyclosporine nephrotoxicity in the rat. In humans, MMF reduced proteinuria in steroid-resistant nephrotic syndrome and had beneficial effects in the prevention and treatment of chronic allograft nephropathy and calcineurin inhibitor toxicity through the reduction of immune- and non-immune-mediated renal damage. MMF is well tolerated and has proven to be a relatively safe drug. Taken together, there is a growing body of evidence pointing to therapeutic applications of MMF other than immunosuppression, in particular the prevention of fibrosis.

Reduction of renal fibrosis as a result of liposome encapsulated clodronate induced macrophage depletion after unilateral ureteral obstruction in rats

BACKGROUND/AIM

Macrophages have been thought to play a role in renal tubulointerstitial fibrosis; recent reports have demonstrated an antifibrotic effect of macrophages in late-stage renal fibrosis. Liposome-encapsulated clodronate (LC) produces a selective and systemic depletion of phagocytic macrophages in vivo. To study the role of initial infiltrating macrophages in renal fibrosis, we compared the effects of pretreatment with LC and a liposome vehicle for control of the severity of renal fibrosis in a unilateral ureteral obstruction (UUO) rat model.

METHODS

One day after a single intravenous injection of LC or liposome vehicle, the rats underwent UUO. Following 1, 5, and 14 days, the kidneys were examined to evaluate macrophage infiltration and renal fibrosis.

RESULTS

LC depleted macrophages systemically and reduced renal fibrosis associated with UUO; this beneficial effect was accompanied by a decrease of transforming growth factor beta mRNA expression. The osteopontin expression was also reduced by pretreatment with LC.

CONCLUSION

Initial interstitial infiltration of macrophages contributes to tubulointerstitial fibrosis in UUO.

The role of purinergic P2X7 receptors in the inflammation and fibrosis of unilateral ureteral obstruction in mice

Receptors of the P2X7 type have been demonstrated in granulocytes, monocytes/macrophages, B and T lymphocytes, and have been involved in several cellular mechanisms including those related to inflammation and immunological response. This study attempted to investigate the role of these receptors on the inflammatory and fibrogenic response in the kidneys of unilateral ureteral obstruction (UUO), by using P2X7 knockout mice (-/-). C57Bl6 mice were submitted to left UUO and killed after 7 and 14 days. Histopathology using hematoxylin-eosin, periodic-acid Schiff and Sirius-red staining, immunohistochemistry for macrophages, myofibroblasts, transforming growth factor-beta (TGF-beta)1 and P2X7, and immunofluorescence for apoptotic cells (terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate nick-end labeling) were performed. Protocols were as follows: (1) control; (2) sham; (3) control P2X7 (-/-); (4) sham P2X7 (-/-); (5) UUO wild type (WT); (6) UUO P2X7 (-/-). Myofibroblasts and Sirius-red staining were significantly lower in UUO P2X7 (-/-) mice at days 7 and 14, compared to UUO WT. Kidneys from UUO P2X7 (-/-) mice showed reduced number of inflammatory cells at day 14 but not at day 7, compared to UUO WT. TGF-beta1 was less in UUO P2X7 (-/-) mice at days 7 and 14 when compared to UUO WT. Macrophage infiltration and tubular apoptosis were lower in UUO P2X7 (-/-) at day 14 but not at day 7, compared to UUO WT. P2X7 was expressed only in tubular epithelial cells at day 7 of UUO WT mice. These findings constitute the first evidence that P2X7 receptors are implicated in macrophage infiltration, collagen deposition and apoptosis in response to ureteral obstruction in mice.

Inhibition of intimal/medial hyperplasia by perindopril in canine vein grafts

We used a canine model to assess the efficacy of an angiotensin-converting enzyme inhibitor (perindopril) at modulating intimal/medial hyperplasia in vein bypass grafts. Fourteen beagle dogs were divided into medicated and control groups and underwent bilateral grafting of external jugular veins into the common carotid artery. Samples of normal veins were obtained from the control group during vein grafting. Vein grafts were harvested 1 week and 4 weeks after surgery in both groups. Subsequently, intimal/medial thickness was measured by staining with hematoxylin and eosin; antibodies for proliferating cell nuclear antigen were employed to determine the degree of cellular proliferation; apoptotic cells were detected using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling method. In the medicated group, the intimal/medial cross-sectional area was significantly smaller and increased 8- to 9-fold in comparison to the control group, which increased 12- to 20-fold. There was a significantly higher rate of cell proliferation in the control group, whereas the medicated group showed a significantly higher rate of apoptotic cells. These data support the efficacy of perindopril at reducing intimal/medial hyperplasia in arterialized vein grafts during a short postoperative period.