β-Casomorphin-7 attenuates the development of nephropathy in type I diabetes via inhibition of epithelial-mesenchymal transition of renal tubular epithelial cells

This study was designed to investigate the putative protective effect of β-casomorphin-7 on diabetic nephropathy in a rat model, and to explore the possible mechanism of this effect. SD rats were randomly divided into the following three groups: control group, diabetes group and β-casomorphin-7-treatment group. All rats were euthanized after 30 days with or without β-casomorphin-7 treatment. Biochemical parameters including blood glucose and renal function were quantified. The concentration of plasma TGF-β1 was measured by ELISA. Histopathological changes to the kidney were studied by Masson and Sirius red staining. Expressions of α-smooth muscle actin (α-SMA), E-cadherin, vimentin, cytokeratin19 and TGF-β1 mRNA in rat renal cortices were analyzed by real-time PCR. Changes in α-SMA and E-cadherin protein expression in rat renal cortices were quantified by Western blot. β-Casomorphin-7 treatment of diabetic rats reduced urinary glucose, urinary protein, serum creatinine, blood urinary nitrogen, plasma TGF-β1 and the ratio of kidney: body weight. Masson and Sirius red staining showed that β-casomorphin-7 treatment attenuated renal interstitial fibrosis in diabetic rats. Compared to the control rats, diabetic rats had elevated expressions of α-SMA, vimentin and TGF-β1 mRNA and α -SMA protein and decreased expression of E-cadherin and cytokeratin19 mRNA, and E-cadherin protein. β-Casomorphin-7 treatment of diabetic rats partially normalized these changes. Our results suggest that administration of β-casomorphin-7 attenuates renal interstitial fibrosis caused by diabetes. This protective effect may be associated, in part, with down regulation of epithelial-mesenchymal transition of renal tubular epithelial cells.     

Phosphodiesterase inhibitor ameliorates senescent changes of renal interstitial pericytes in aging kidney

Pericytes are mesenchymal cells that surround endothelial cells, playing a crucial role in angiogenesis and vessel maturation. Additionally, they are associated with interstitial fibrosis as a major contributor to renal myofibroblasts. In this study, we aim to investigate whether the phosphodiesterase inhibitor, pentoxifylline (PTX), can ameliorate aging-related functional and histological deterioration in the kidney. We subjected aging C57BL/6 mice, dividing into young, aging, and PTX-treated aging groups. Renal function, albuminuria, and histological changes were assessed. Interstitial pericytes were assessed by immunohistochemistry analysis. We examined changes in pericytes in elderly patients using human kidney tissue obtained from healthy kidney donors for kidney transplantation. In vitro experiments with human pericytes and endothelial cells were performed. Aging mice exhibited declined renal function, increased albuminuria, and aging-related histological changes including mesangial expansion and tubulointerstitial fibrosis. Notably, number of pericytes declined in aging kidneys, and myofibroblasts increased. PTX treatment ameliorated albuminuria, histological alterations, and microvascular rarefaction, as well as modulated angiopoietin expression. In vitro experiments showed PTX reduced cellular senescence and inflammation. Human kidney analysis confirmed similar pericyte changes in aging kidneys. The phosphodiesterase inhibitor, PTX preserved microvascular density and improved renal interstitial fibrosis and inflammation in aging mice kidneys. These protective effects were suggested to be associated with the amelioration of pericytes reduction and the transition to myofibroblasts. Additionally, the upregulation of angiopoietin-1 expression may exert potential impacts. To the best of our knowledge, this is the first report on the changes in renal interstitial pericytes in aging human kidneys.     

Collagen-binding proteins in age-dependent changes in renal collagen turnover: microarray analysis of mRNA expression

Aging is associated with progressive structural and functional deterioration of the kidney. Among the morphological changes associated with renal aging is an accumulation of extracellular matrix (ECM) in the glomeruli and tubuloinsterstitium, which may ultimately lead to the development of renal fibrosis. The mechanisms governing the regulation of ECM metabolism during renal aging are only incompletely defined. We present data from a genome-wide mRNA expression study on renal tissue from 90 wk old male Wistar rats and 10 wk old controls using Illumina BeadArray cDNA microarray. Regulation of candidate gene products was verified by real-time PCR. Morphological changes were evaluated by routine histological methods. Activated fibroblasts were identified by their expression of alpha-smooth muscle actin and collagen I. Morphological analysis demonstrated an expansion of the tubulointerstitial compartment with increased amounts of fibrous collagen but no overt glomerular or tubular damage in the aged rats. Activated fibroblasts were readily detectable in the adventitial layer of large renal vessels in controls and were not found in the old animals. In agreement with this finding, gene expression analysis revealed significant downregulation of collagen I mRNA along with numerous other ECM components. Concomitantly, collagen-stabilizing proteins were induced, whereas matrix metalloproteinase 9, an enzyme involved in collagen breakdown, was reduced. In conclusion, our results suggest that ECM expansion during renal aging results from an augmented stabilization in conjunction with a reduced breakdown of collagen fibers. Collagen stabilizing proteins may be essential for the control of renal ECM turnover and the pathogenesis of kidney fibrosis.     

CDC20 inhibition alleviates fibrotic response of renal tubular epithelial cells and fibroblasts by regulating nuclear translocation of β-catenin

Fibrosis is a common pathological phenomenon in progressive kidney disease leading to eventual loss of kidney function. Previous studies demonstrated that CDC20 plays a role in cancers by regulating epithelial-mesenchymal transition (EMT) and the infiltration of fibroblasts, suggesting the potential of CDC20 in regulating fibrotic response. However, the role of CDC20 in renal fibrosis is yet unclear. Herein, we reported that renal CDC20 was remarkably upregulated in renal tubular epithelial cells and fibroblasts in chronic kidney disease (CKD) patients, which was in line with a positive correlation with the severity of kidney fibrosis. In mice with unilateral urinary obstruction, CDC20 was also strikingly enhanced, and treatment with Apcin, an inhibitor of CDC20, ameliorated kidney fibrosis. Consistently, the pharmacological inhibition of CDC20 in mouse proximal tubular epithelial cells and rat fibroblasts attenuated TGF-β1-induced fibrotic responses, while overexpression of CDC20 aggravated such responses. Additional studies revealed that CDC20 induces nuclear translocation of β-catenin, which in turn initiates and promotes the pathological process of fibrosis in CKD. Thus, enhanced CDC20 in renal tubular cells and fibroblasts promotes renal fibrosis by activating β-catenin, and CDC20 inhibition may serve as a promising strategy for the prevention and treatment of renal fibrosis.     

Cell-based therapies for experimental chronic kidney disease: a systematic review and meta-analysis

Cell-based therapy is a promising strategy for treating chronic kidney disease (CKD) and is currently the focus of preclinical studies. We performed a systematic review and meta-analysis to evaluate the efficacy of cell-based therapy in preclinical (animal) studies of CKD, and determined factors affecting cell-based therapy efficacy in order to guide future clinical trials. In total, 71 articles met the inclusion criteria. Standardised mean differences (SMD) and 95% confidence intervals (CI) were calculated for outcome parameters including plasma urea, plasma creatinine, urinary protein, blood pressure, glomerular filtration rate, glomerulosclerosis and interstitial fibrosis. Sub-analysis for each outcome measure was performed for model-related factors (species, gender, model and timing of therapy) and cell-related factors (cell type, condition and origin, administration route and regime of therapy). Overall, meta-analysis showed that cell-based therapy reduced the development and progression of CKD. This was most prominent for urinary protein (SMD, 1.34; 95% CI, 1.00–1.68) and urea (1.09; 0.66–1.51), both P<0.001. Changes in plasma urea were associated with changes in both glomerulosclerosis and interstitial fibrosis. Sub-analysis showed that cell type (bone-marrow-derived progenitors and mesenchymal stromal cells being most effective) and administration route (intravenous or renal artery injection) were significant predictors of therapeutic efficacy. The timing of therapy in relation to clinical manifestation of disease, and cell origin and dose, were not associated with efficacy. Our meta-analysis confirms that cell-based therapies improve impaired renal function and morphology in preclinical models of CKD. Our analyses can be used to optimise experimental interventions and thus support both improved preclinical research and development of cell-based therapeutic interventions in a clinical setting.KEY WORDS: Cell-based therapy, Chronic kidney disease, Meta-analysis     

Experimental mild renal insufficiency mediates early cardiac apoptosis, fibrosis, and diastolic dysfunction: a kidney-heart connection

Impaired renal function with loss of nephron number in chronic renal disease (CKD) is associated with increased cardiovascular morbidity and mortality. However, the structural and functional cardiac response to early and mild reduction in renal mass is poorly defined. We hypothesized that mild renal impairment produced by unilateral nephrectomy (UNX) would result in early cardiac fibrosis and impaired diastolic function, which would progress to a more global left ventricular (LV) dysfunction. Cardiorenal function and structure were assessed in rats at 4 and 16 wk following UNX or sham operation (Sham); (n = 10 per group). At 4 wk, blood pressure (BP), aldosterone, glomerular filtration rate (GFR), proteinuria, and plasma B-type natriuretic peptide (BNP) were not altered by UNX, representing a model of mild early CKD. However, UNX was associated with significantly greater LV myocardial fibrosis compared with Sham. Importantly, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining revealed increased apoptosis in the LV myocardium. Further, diastolic dysfunction, assessed by strain echocardiography, but with preserved LVEF, was observed. Changes in genes related to the TGF-β and apoptosis pathways in the LV myocardium were also observed. At 16 wk post-UNX, we observed persistent LV fibrosis and impairment in LV diastolic function. In addition, LV mass significantly increased, as did LVEDd, while there was a reduction in LVEF. Aldosterone, BNP, and proteinuria were increased, while GFR was decreased. The myocardial, structural, and functional alterations were associated with persistent changes in the TGF-β pathway and even more widespread changes in the LV apoptotic pathway. These studies demonstrate that mild renal insufficiency in the rat results in early cardiac fibrosis and impaired diastolic function, which progresses to more global LV remodeling and dysfunction. Thus, these studies importantly advance the concept of a kidney-heart connection in the control of myocardial structure and function.     

Increased urinary C-type natriuretic peptide excretion may be an early marker of renal tubulointerstitial fibrosis

Although recent major advances have developed a much better understanding of the pathophysiological pathways, tubulointerstitial fibrosis (TIF) is still currently incurable. Therefore, early detection may mean that the condition is more manageable than it was in the past. C-type natriuretic peptide (CNP) has been found to be a potent vasodilator but a weak natriuretic factor. In addition, CNP has also been believed to be produced in tubular cells and presented as a local modulator with anti-inflammatory and anti-proliferative effects. Elimination of CNP occurs by three main mechanisms, neutral endopeptidase, natriuretic peptide receptor-C and urinary excretion. Among them, the status of urinary CNP excretion in nephropathies is not yet fully elucidated. In the present study, subgroups of rats were subjected to unilateral ureteral obstruction (UUO) or sham operation and observed for 24 h to 3 months. Urinary CNP excretion was significantly enhanced in UUO rats from 24 h to 1 month post-ligation compared to sham-operated rats. Urinary CNP excretion was also markedly higher than CNP concentrations both in abdominal aorta and in renal vein, and almost identical concentrations in these two vessels excluded major renal extraction of circulating CNP of systemic origin. Urinary CNP excretion was negatively correlated with urinary protein concentration, blood urea nitrogen and creatinine, while positively correlated with albumin. In conclusion, the increased urinary CNP excretion is strongly associated with TIF progression, and may serve as an early marker of TIF.     

Renal protective effect of chronic inhibition of COX-2 with SC-58236 in streptozotocin-diabetic rats

The induction of renal cyclooxygenase-2 (COX-2) in diabetes has been implicated in the renal functional and structural changes in models where hypertension or uninephrectomy was superimposed. We examined the protective effects of 3 mo treatment of streptozotocin-diabetic rats with a highly selective COX-2 inhibitor (SC-58236) in terms of albuminuria, renal hypertrophy, and the excretion of TNF-α and TGF-β, which have also been implicated in the detrimental renal effects of diabetes. SC-58236 treatment (3 mg·kg(-1)·day(-1)) of diabetic rats resulted in reduced urinary excretion of PGE(2), 6-ketoPGF(1α), and thromboxane B(2), all of which were increased in the diabetic rat compared with age-matched nondiabetic rats. However, serum thromboxane B(2) levels were unchanged, confirming the selectivity of SC-58236 for COX-2. The renal protective effects of treatment of diabetic rats with the COX-2 inhibitor were reflected by a marked reduction in albuminuria, a reduction in kidney weight-to-body weight ratio, and TGF-β excretion and a marked decrease in the urinary excretion of TNF-α. The protective effects of SC-58236 were independent of changes in plasma glucose levels or serum advanced glycation end-product levels, which were not different from those of untreated diabetic rats. In an additional study, the inhibition of COX-2 with SC-58236 for 4 wk in diabetic rats resulted in creatinine clearance rates not different from those of control rats. These results confirm that the inhibition of COX-2 in the streptozotocin-diabetic rat confers renal protection and suggest that the induction of COX-2 precedes the increases in cytokines, TNF-α, and TGF-β.     

Galectin-3 Blockade Reduces Renal Fibrosis in Two Normotensive Experimental Models of Renal Damage

BackgroundGalectin-3 (Gal-3), a β-galactoside-binding lectin, is increased in kidney injury and its pharmacological blockade reduces renal damage in acute kidney injury, hyperaldosteronism or hypertensive nephropathy. We herein investigated the effects of pharmacological Gal-3 inhibition by modified citrus pectin (MCP) in early renal damage associated with obesity and aortic stenosis (AS).ResultsGal-3 was upregulated in kidneys from high fat diet (HFD) rats and in animals with partial occlusion of ascending aorta (AS). Urinary and plasma neutrophil gelatinase-associated lipocalin (NGAL) and urinary albumin were enhanced in HFD and AS rats. In kidney from obese rats, fibrotic markers (collagen, TFG-β), epithelial-mesenchymal transition molecules (α-smooth muscle actin, E-cadherin), inflammatory mediator (osteopontin) and kidney injury marker (kidney injury molecule-1) were modified. In kidney from AS rats, fibrotic markers (collagen, CTGF), epithelial-mesenchymal transition molecules (fibronectin, α-smooth muscle actin, β-catenin, E-cadherin) and kidney injury markers (NGAL, kidney injury molecule-1) were altered. Histologic observations of obese and AS rat kidneys revealed tubulointerstitial fibrosis. The pharmacological inhibition of Gal-3 with MCP normalized renal Gal-3 levels as well as functional, histological and molecular alterations in obese and AS rats.ConclusionsIn experimental models of mild kidney damage, the increase in renal Gal-3 expression paralleled with renal fibrosis, inflammation and damage, while these alterations were prevented by Gal-3 blockade. These data suggest that Gal-3 could be a new player in renal molecular, histological and functional alterations at early stages of kidney damage.     

The human urinary proteome reveals high similarity between kidney aging and chronic kidney disease

Aging induces morphological changes of the kidney and reduces renal function. We analyzed the low molecular weight urinary proteome of 324 healthy individuals from 2–73 years of age to gain insight on human renal aging. We observed age‐related modification of secretion of 325 out of over 5000 urinary peptides. The majority of these changes were associated with renal development before and during puberty, while 49 peptides were related to aging in adults. We therefore focussed the remainder of the study on these 49 peptides. The majority of these 49 peptides were also markers of chronic kidney disease, suggesting high similarity between aging and chronic kidney disease. Blinded evaluation of samples from healthy volunteers and diabetic nephropathy patients confirmed both the correlation of biomarkers with aging and with renal disease. Identification of a number of these aging‐related peptides led us to hypothesize that reduced proteolytic activity is involved in human renal aging. Finally, among the 324 supposedly healthy individuals, some had urinary aging‐related peptide excretion patterns typical of an individual significantly older than their actual age. In conclusion, these aging‐related biomarkers may allow noninvasive detection of renal lesions in healthy persons and show high resemblance between human aging and chronic kidney disease. This similarity has to be taken into account when searching for biomarkers of renal disease.     

Tubular cell-derived exosomal miR-150-5p contributes to renal fibrosis following unilateral ischemia-reperfusion injury by activating fibroblast in vitro and in vivo

Unilateral ischemia reperfusion injury (UIRI) with longer ischemia time is associated with an increased risk of acute renal injury and chronic kidney disease. Exosomes can transport lipid, protein, mRNA, and miRNA to corresponding target cells and mediate intercellular information exchange. In this study, we aimed to investigate whether exosome-derived miRNA mediates epithelial-mesenchymal cell communication relevant to renal fibrosis after UIRI. The secretion of exosomes increased remarkably in the kidney after UIRI and in rat renal tubular epithelium cells (NRK-52E) after hypoxia treatment. The inhibition of exosome secretion by Rab27a knockout or GW4869 treatment ameliorates renal fibrosis following UIRI in vivo. Purified exosomes from NRK-52E cells after hypoxia treatment could activate rat kidney fibroblasts (NRK-49F). The inhibition of exosome secretion in hypoxic NRK-52E cells through Rab27a knockdown or GW4869 treatment abolished NRK-49F cell activation. Interestingly, exosomal miRNA array analysis revealed that miR-150-5p expression was increased after hypoxia compared with the control group. The inhibition of exosomal miR-150-5p abolished the ability of hypoxic NRK-52E cells to promote NRK-49F cell activation in vitro, injections of miR-150-5p enriched exosomes from hypoxic NRK-52E cells aggravated renal fibrosis following UIRI, and renal fibrosis after UIRI was alleviated by miR-150-5p-deficient exosome in vivo. Furthermore, tubular cell-derived exosomal miR-150-5p could negatively regulate the expression of suppressor of cytokine signaling 1 to activate fibroblast. Thus, our results suggest that the blockade of exosomal miR-150-5p mediated tubular epithelial cell-fibroblast communication may provide a novel therapeutic target to prevents UIRI progression to renal fibrosis.     

Predictive Usefulness of Urinary Biomarkers for the Identification of Cyclosporine A-Induced Nephrotoxicity in a Rat Model

The main side effect of cyclosporine A (CsA), a widely used immunosuppressive drug, is nephrotoxicity. Early detection of CsA-induced acute nephrotoxicity is essential for stop or minimize kidney injury, and timely detection of chronic nephrotoxicity is critical for halting the drug and preventing irreversible kidney injury. This study aimed to identify urinary biomarkers for the detection of CsA-induced nephrotoxicity. We allocated salt-depleted rats to receive CsA or vehicle for 7, 14 or 21 days and evaluated renal function and hemodynamics, microalbuminuria, renal macrophage infiltration, tubulointerstitial fibrosis and renal tissue and urinary biomarkers for kidney injury. Kidney injury molecule-1 (KIM-1), tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), fibronectin, neutrophil gelatinase-associated lipocalin (NGAL), TGF-β, osteopontin, and podocin were assessed in urine. TNF-α, IL-6, fibronectin, osteopontin, TGF-β, collagen IV, alpha smooth muscle actin (α -SMA) and vimentin were assessed in renal tissue. CsA caused early functional renal dysfunction and microalbuminuria, followed by macrophage infiltration and late tubulointerstitial fibrosis. Urinary TNF-α, KIM-1 and fibronectin increased in the early phase, and urinary TGF-β and osteopontin increased in the late phase of CsA nephrotoxicity. Urinary biomarkers correlated consistently with renal tissue cytokine expression. In conclusion, early increases in urinary KIM-1, TNF-α, and fibronectin and elevated microalbuminuria indicate acute CsA nephrotoxicity. Late increases in urinary osteopontin and TGF-β indicate chronic CsA nephrotoxicity. These urinary kidney injury biomarkers correlated well with the renal tissue expression of injury markers and with the temporal development of CsA nephrotoxicity.     

Renal function and morphology in aged Beagle dogs before and after hydrocortisone administration

Objectives of this study were to evaluate glomerular filtration rate (GFR), renal structural changes and proteinuria in aged Beagle dogs before and after hydrocortisone (HC) administration. Eleven Beagle dogs ≥10 years old were treated with either hydrocortisone (HC group, n = 6) or placebo (control group, n = 5). Urinary markers, GFR and kidney biopsies were evaluated before (T0), during (T16 wks) and after discontinuing HC administration (T24 wks). Results indicate that HC administration causes a significant increase in GFR. At all time points except T16 wks, proteinuria was higher in the control group than in the HC group, and there was no significant difference in urinary markers between groups. At T16 wks, proteinuria, urinary albumin-to-creatinine (c) ratio, immunoglobulin G/c and retinol-binding protein/c were higher compared to baseline in the HC group. At T0, rare to mild renal lesions were detected in all HC dogs and rare to moderate changes in all control dogs. Glomerulosclerosis progressed in both groups until T24 wks. Tubular atrophy was detected in three HC dogs at T16 wks and T24 wks, but also in five control dogs throughout the study. At every time point, five HC dogs and all control dogs had rare to moderate interstitial inflammation. Rare to mild interstitial fibrosis was found in up to three HC dogs at T16 wks and T24 wks, and severe fibrosis in one HC dog at T24 wks. Up to four control dogs had rare to mild fibrosis at all time points. These findings indicate that clinically healthy, aged Beagle dogs may have considerable renal lesions and proteinuria, which could have implications for experimental or toxicological studies. Additional research is needed to elucidate glucocorticoid effects on renal structure, but functional changes such as hyperfiltration and proteinuria warrant attention to kidney function of canine patients with Cushing''s syndrome or receiving exogenous glucocorticoids.     

Neutral endopeptidase and natriuretic peptide receptors participate in the regulation of C-type natriuretic peptide expression in renal interstitial fibrosis

The initiation and progression of renal interstitial fibrosis (RIF) is a complicated process in which many factors may play an activate role. Among these factors, C-type natriuretic peptide (CNP) is an endothelium-derived hormone and acts in a local, paracrine fashion to regulate vascular smooth muscle tone and proliferation. In this study, we established a rat model of unilateral ureteral obstruction (UUO). CNP expression tends to be higher immediately after ligation and declined at later time points, occurring predominantly in tubular epithelial cells. A high-level CNP may contribute to the elevated expression of natriuretic peptide receptor (NPR)-B in the early phase of UUO. However, the sustained expression of NPR-C and neutral endopeptidase (NEP) observed throughout the study period (that is up to 3 months) helps to, at least partly, explain the subsequent decline of CNP. Thus, NEP and NPRs participate in the regulation of CNP expression in RIF.     

高胱氨酸尿对大鼠肾脏自噬水平的抑制作用

摘要 目的：探讨胱氨酸尿症中高胱氨酸浓度对大鼠肾脏自噬水平的影响。方法：通过液相色谱串联质谱（LC-MS/MS）测定Slc7a9基因敲除大鼠24小时尿液胱氨酸浓度确定高尿胱氨酸;通过IHC（免疫组织化学）染色筛选无结石产生的胱氨酸尿症大鼠、观察肾脏组织结构有无明显变化;通过Western blot测定肾脏组织中的LC3-I、LC3-II、p62和mTOR的蛋白相对表达量,以检测自噬水平的变化,并探索变化原因;通过组织切片Masson染色法检测肾脏髓质纤维化程度。结果：10只无结石胱氨酸尿症大鼠尿液胱氨酸显著高于对照组;未发现有胱氨酸结石的生成与肾脏结构性变化;Masson染色提示胱氨酸尿症大鼠发现轻度肾脏纤维化过程;肾脏组织自噬标记蛋白LC3-I、LC3-II蛋白相对表达量、LC3-II/LC3-I比值以及自噬当量p62相对表达较对照组均显著降低,mTOR相对表达量显著升高。以上差异均有统计学意义（P＜0.05）。结论：在胱氨酸尿症大鼠模型上,发现无结石形成情况下的尿高胱氨酸水平可通过mTOR途径抑制大鼠肾脏组织的自噬水平,自我保护作用减弱,由此参与胱氨酸尿症的肾脏损伤过程。     

Acute treatment with relaxin protects the kidney against ischaemia/reperfusion injury

Although recent preclinical and clinical studies have demonstrated that recombinant human relaxin (rhRLX) may have important therapeutic potential in acute heart failure and chronic kidney diseases, the effects of acute rhRLX administration against renal ischaemia/reperfusion (I/R) injury have never been investigated. Using a rat model of 1‐hr bilateral renal artery occlusion followed by 6‐hr reperfusion, we investigated the effects of rhRLX (5 μg/Kg i.v.) given both at the beginning and after 3 hrs of reperfusion. Acute rhRLX administration attenuated the functional renal injury (increase in serum urea and creatinine), glomerular dysfunction (decrease in creatinine clearance) and tubular dysfunction (increase in urinary excretion of N‐acetyl‐β‐glucosaminidase) evoked by renal I/R. These beneficial effects were accompanied by a significant reduction in local lipid peroxidation, free radical‐induced DNA damage and increase in the expression/activity of the endogenous antioxidant enzymes Mn‐ and CuZn‐superoxide dismutases (SOD). Furthermore, rhRLX administration attenuated the increase in leucocyte activation, as suggested by inhibition of myeloperoxidase activity, intercellular‐adhesion‐molecule‐1 expression, interleukin (IL)‐1β, IL‐18 and tumour necrosis factor‐α production as well as increase in IL‐10 production. Interestingly, the reduced oxidative stress status and neutrophil activation here reported were associated with rhRLX‐induced activation of endothelial nitric oxide synthase and up‐regulation of inducible nitric oxide synthase, possibly secondary to activation of Akt and the extracellular signal‐regulated protein kinase (ERK) 1/2, respectively. Thus, we report herein that rhRLX protects the kidney against I/R injury by a mechanism that involves changes in nitric oxide signalling pathway.     

AT1 receptor antagonism attenuates target organ effects of salt excess in SHRs without affecting pressure

Our recent studies have demonstrated that salt excess in the spontaneously hypertensive rat (SHR) produces a modestly increased arterial pressure while promoting marked myocardial fibrosis and structural damage associated with altered coronary hemodynamics and ventricular function. The present study was designed to determine the efficacy of an angiotensin II type 1 (AT(1)) receptor blocker (ARB) in the prevention of pressure increase and development of target organ damage from high dietary salt intake. Eight-week-old SHRs were given an 8% salt diet for 8 wk; their age- and gender-matched controls received standard chow. Some of the salt-loaded rats were treated concomitantly with ARB (candesartan; 10 mg kg(-1) day(-1)). The ARB failed to reduce the salt-induced rise in pressure, whereas it significantly attenuated left ventricular (LV) remodeling (mass and wall thicknesses), myocardial fibrosis (hydroxyproline concentration and collagen volume fraction), and the development of LV diastolic dysfunction, as shown by longer isovolumic relaxation time, decreased ratio of peak velocity of early to late diastolic waves, and slower LV relaxation (minimum first derivative of pressure over time/maximal LV pressure). Without affecting the increased pulse pressure by high salt intake, the ARB prevented the salt-induced deterioration of coronary and renal hemodynamics but not the arterial stiffening or hypertrophy (pulse wave velocity and aortic mass index). Additionally, candesartan prevented the salt-induced increase in kidney mass index and proteinuria. In conclusion, the ARB given concomitantly with dietary salt excess ameliorated salt-related structural and functional cardiac and renal abnormalities in SHRs without reducing arterial pressure. These data clearly demonstrated that angiotensin II (via AT(1) receptors), at least in part, participated importantly in the pressure-independent effects of salt excess on target organ damage of hypertension.     

Aliskiren prevents the toxic effects of peritoneal dialysis fluids during chronic dialysis in rats

The benefits of long-term peritoneal dialysis (PD) in patients with end-stage renal failure are short-lived due to structural and functional changes in the peritoneal membrane. In this report, we provide evidence for the in vitro and in vivo participation of the renin-angiotensin-aldosterone system (RAAS) in the signaling pathway leading to peritoneal fibrosis during PD. Exposure to high-glucose PD fluids (PDFs) increases damage and fibrosis markers in both isolated rat peritoneal mesothelial cells and in the peritoneum of rats after chronic dialysis. In both cases, the addition of the RAAS inhibitor aliskiren markedly improved damage and fibrosis markers, and prevented functional modifications in the peritoneal transport, as measured by the peritoneal equilibrium test. These data suggest that inhibition of the RAAS may be a novel way to improve the efficacy of PD by preventing inflammation and fibrosis following peritoneal exposure to high-glucose PDFs.