Progression Of Renal Injury Research Articles

Ethanol consumption increases the expression of endothelial nitric oxide synthase, inducible nitric oxide synthase and metalloproteinases in the rat kidney

The effects of longterm ethanol consumption on the levels of nitric oxide (NO) and the expression of endothelial NO synthase (eNOS), inducible NO synthase (iNOS) and metalloproteinase-2 (MMP-2) were studied in rat kidney. Male Wistar rats were treated with 20% ethanol (v/v) for 6 weeks. Nitrite and nitrate generation was measured by chemiluminescence. Protein and mRNA levels of eNOS and iNOS were assessed by immunohistochemistry and quantitative real-time polymerase chain reaction, respectively. MMP-2 activity was determined by gelatin zymography. Histopathological changes in kidneys and indices of renal function (creatinine and urea) and tissue injury (mitochondrial respiration) were also investigated. Chronic ethanol consumption did not alter malondialdehyde levels in the kidney. Ethanol consumption induced a significant increase in renal nitrite and nitrate levels. Treatment with ethanol increased mRNA expression of both eNOS and iNOS. Immunohistochemical assays showed increased immunostaining for eNOS and iNOS after treatment with ethanol. Kidneys from ethanol-treated rats showed increased activity of MMP-2. Histopathological investigation of kidneys from ethanol-treated animals revealed tubular necrosis. Indices of renal function and tissue injury were not altered in ethanol-treated rats. Ethanol consumption increased renal metalloproteinase expression/activity, which was accompanied by histopathological changes in the kidney and elevated NO generation. Since iNOS-derived NO and MMPs contribute to progressive renal injury, the increased levels of NO and MMPs observed in ethanol-treated rats might contribute to progressive renal damage.

Aldosterone stimulates nuclear factor-kappa B activity and transcription of intercellular adhesion molecule-1 and connective tissue growth factor in rat mesangial cells via serum- and glucocorticoid-inducible protein kinase-1

Several clinical and experimental data support the hypothesis that aldosterone contributes to the progression of renal injury. To determine the signaling pathway of aldosterone in relation to fibrosis and inflammation in mesangial cells, we investigated the effects of aldosterone on expression and activation of serum- and glucocorticoid-inducible protein kinase-1 (SGK1), the activation of nuclear factor-kappa B (NF-κB activation, and the expressions of intercellular adhesion molecule-1 (ICAM-1) and connective tissue growth factor (CTGF). Aldosterone stimulated SGK1 expression, phosphorylation (Ser-256), and kinase activity. The increments of phosphorylation and expression of SGK1 induced by aldosterone were inhibited by mineralocorticoid receptor (MR) inhibitor (eplerenone). Aldosterone stimulated NF-κB activity measured by NF-κB responsive elements, luciferase assay, and the levels of inhibitor of kappa B (IκB) phosphorylation. This aldosterone-induced activation of NF-κB was inhibited by the transfection of dominant-negative SGK1. Furthermore, aldosterone augmented the promoter activities and protein expressions of ICAM-1 and CTGF. The effects of aldosterone on ICAM-1 and CTGF promoter activities and protein expressions were inhibited by the transfection of dominant-negative SGK1 and dominant-negative IκBα. We also found that the MR antagonist significantly ameliorated the glomerular injury and enhancements in SGK1, ICAM-1, and CTGF expressions induced by 1% sodium chloride and aldosterone in vivo. In conclusion, our findings suggest that aldosterone stimulates ICAM-1 and CTGF transcription via activation of SGK1 and NF-κB, which may be involved in the progression of aldosterone-induced mesangial fibrosis and inflammation. MR antagonists may serve as useful therapeutic targets for the treatment of glomerular inflammatory disease.

Aggressive Total Parenteral Nutrition is Associated with an Increased Incidence of Nephrocalcinosis in Very Low Birth Weight Infants

Background and Aims:As aggressive total parenteral nutrition (TPN) is replaced as the standard protocol, the aim of our study was to determine the effect of aggressive TPN focusing on the immature kidney. We compared the incidence and natural course of nephrocalcinosis (NC) in premature infants from two different nutrition strategies.Methods: We studied all preterm neonates with a birth weight below 1500g who were born from Jan 2006 to Dec 2010 retropectively. Sequential abdominal ultrasonography was performed in all patients. The clinical parameters, maternal factors, respiratory support and duration of furosemide were analyzed. The change of nutrition strategy was also compared with the incidence of NC.Results: NC was detected in 35 of 101 VLBW infants (34.7%). Low birth weight was significantly associated with NC (P< 0.05). The duration of oxygen use, furosemide treatment and TPN were also strongly associated with NC. Concerning the change in our hospital's nutritional strategy since 2008, such as the increase of protein intake in the first week, the incidence of NC was significantly increased after 2008 (19.5% vs. 43.3%, p< 0.05). NC persisted in four infants (4/35, 11.4%) after 12 months follow-up period and one infant developed urolithiasis. Among these four infants, three infants received aggressive TPN.Conclusions: Though NC resolves spontaneously in most patients, persistent progressive renal injury can develop, especially after aggressive TPN. Therefore, early diagnostic evaluation is crucial and close follow up of NC in preterm neonates are needed.

Microvascular disease precedes the decline in renal function in the streptozotocin-induced diabetic rat

Diabetic nephropathy is a progressive and generalized vasculopathic condition associated with abnormal angiogenesis. We aim to determine whether changes in renal microvascular (MV) density correlate with and play a role in the progressive deterioration of renal function in diabetes. We hypothesize that MV changes represent the early steps of renal injury that worsen as diabetes progresses, initiating a vicious circle that leads to irreversible renal injury. Male nondiabetic (ND) or streptozotocin-induced diabetic (D) Sprague-Dawley rats were followed for 4 or 12 wk. Renal blood flow and glomerular filtration rate (GFR) were measured by PAH and (125)I-[iothalamate], respectively. Renal MV density was quantified ex vivo using three-dimensional micro computed tomography and JG-12 immunoreactivity. Vascular endothelial growth factor (VEGF) levels (ELISA) and expression of VEGF receptors and factors involved in MV remodeling were quantified in renal tissue by Western blotting. Finally, renal morphology was investigated by histology. Four weeks of diabetes was associated with increased GFR, accompanied by a 34% reduction in renal MV density and augmented renal VEGF levels. However, at 12 wk, while GFR remained similarly elevated, reduction of MV density was more pronounced (75%) and associated with increased MV remodeling, renal fibrosis, but unchanged renal VEGF compared with ND at 12 wk. The damage, loss, and subsequent remodeling of the renal MV architecture in the diabetic kidney may represent the initiating events of progressive renal injury. This study suggests a novel concept of MV disease as an early instigator of diabetic kidney disease that may precede and likely promote the decline in renal function.

Successful treatment of progressive renal injury due to granulomatous tubulointerstitial nephritis with uveitis

Acute tubulointerstitial nephritis and bilateral uveitis (TINU) syndrome is a rare disease usually occurring in young women. We report the exceptional case of a 48-year-old man with TINU syndrome who had a 10-month history of interstitial nephritis before the onset of uveitis. Findings from the renal biopsy specimen indicated tubular atrophy, dense infiltration of lymphocytes, granulomatous infiltration with multinucleated giant cells, and disruption of the vessel wall. The patient was initially diagnosed to have chronic kidney disease; interstitial nephritis could not be diagnosed until blurred vision occurred. However, he was successfully treated with steroid pulse and oral maintenance therapy. Steroid therapy may be effective to treat TINU syndrome irrespective of the onset of the disease.

Acute unilateral ischemic renal injury induces progressive renal inflammation, lipid accumulation, histone modification, and "end-stage" kidney disease.

There is an emerging concept in clinical nephrology that acute kidney injury (AKI) can initiate chronic kidney disease (CKD). However, potential mechanisms by which this may occur remain elusive. Hence, this study tested the hypotheses that 1) AKI triggers progressive activation of selected proinflammatory genes, 2) there is a relative failure of compensatory anti-inflammatory gene expression, 3) proinflammatory lipid accumulation occurs, 4) these changes correspond with "gene-activating" histone acetylation, and 5) in concert, progressive renal disease results. CD-1 mice were subjected to 30 min of unilateral renal ischemia. Assessments were made 1 day, 1 wk, or 3 wk later. Results were contrasted to those observed in uninjured contralateral kidneys or in kidneys from normal mice. Progressive renal injury occurred throughout the 3-wk postischemic period, as denoted by stepwise increases in neutrophil gelatinase-associated lipocalin gene induction and ongoing histologic damage. By 3 wk postischemia, progressive renal disease was observed (massive tubular dropout; 2/3rds reduction in renal weight). These changes corresponded with progressive increases in proinflammatory cytokine/chemokine gene expression (MCP-1, TNF-α, TGF-β1), a relative failure of anti-inflammatory enzyme/cytokine (heme oxygenase-1; IL-10) upregulation, and progressive renal lipid (cholesterol/triglyceride) loading. Stepwise increases in collagen III mRNA and collagen deposition (Sirius red staining) indicated a progressive profibrotic response. Postischemic dexamethasone treatment significantly preserved renal mass, indicating functional significance of the observed proinflammatory state. Progressive gene-activating H3 acetylation was observed by ELISA, rising from 5% at baseline to 75% at 3 wk. This was confirmed by chromatin immunoprecipitation assay of target genes. In sum, these results provide experimental support for the clinical concept that AKI can trigger CKD, this is partially mediated by progressive postischemic inflammation, ongoing lipid accumulation results (potentially evoking "lipotoxicity"), and increasing histone acetylation at proinflammatory/profibrotic genes may contribute to this self-sustaining injury-promoting state.

Cardiotonic Steroids, Hypertension and Cardiovascular Disease

It has been known for some time that dietary salt intake correlates with the prevalence of cardiovascular disease. However, the molecular link between dietary salt and cardiovascular disease is poorly understood. On this background, it has been observed that there are a class of hormones called cardiotonic steroids whose concentrations increase in response to increases in dietary salt. We have shown that some of these hormones may be natriuretic, but we have also shown that they may also be responsible for progressive renal and cardiac injury. Based on data summarized in this review, we propose cardiotonic steroids may serve as the molecular link between dietary salt and cardiovascular disease. Keywords: Cardiotonic Steroids, digitalis like factors, Na/K-ATPase, Sodium pump, NaCl-sensitivity, cytosolic calcium, epithelial growth factor, adrenalectomy, natriuretic hormone, spironolactone treatment, MBG-albumin conjugate

Eicosapentaenoic acid regulates IκBα and prevents tubulointerstitial injury in kidney

Fish oil containing n-3 polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is well known to prevent the progression of IgA nephropathy. However, the mechanism through which fish oil prevents the progression of renal injury remains uncertain. We tried to clarify the effects of EPA on tubulointerstitial injury in the kidney both in vivo and in vitro. We examined the effects of EPA, especially to focus on nuclear factor kappa B (NF-κB), using Thy-1 nephritis models. Also the mechanism of EPA was investigated using small-interfering RNA (siRNA) in lipopolysaccharide (LPS)-stimulated proximal tubular epithelial cells (PTECs). In Thy-1 nephritis models, EPA significantly inhibited tubulointerstitial injury and the infiltration of macrophages into tubulointerstitial lesions except severe glomerular injury at early stage. Compared with control animals, NF-κB activation was significantly augmented in the Thy-1 nephritic kidney. However, treatment with EPA significantly reduced NF-κB activation, down-regulated the expressions of NF-κB-dependent molecules. Also in LPS-stimulated PTECs, LPS augmented NF-κB activation and the expression of NF-κB-dependent molecules. As in the case with the Thy-1 nephritis models, treatment with EPA inhibited them, prevented the degradation of IκBα in LPS-stimulated PTECs. Pre-treatment with siRNA for IκBα abolished the inhibitory effect of EPA on LPS-induced NF-κB activation, suggesting that EPA inhibited NF-κB activation by regulating IκBα. Our results indicate that EPA prevents the early progression of tubulointerstitial injury in Thy-1 nephritis models, and the inhibitory effect of EPA on the expression of inflammatory molecules via the regulation of IκBα in cultured cells may explain this mechanism.

Angiotensin II type I receptor blockade suppresses glomerular renin-angiotensin system activation, oxidative stress, and progressive glomerular injury in rat anti-glomerular basement membrane glomerulonephritis

Excessive renin-angiotensin system (RAS) activation within the kidney induces not only renal oxidative stress but also renal scarring and dysfunction. This study examined the effects of an angiotensin II (Ang II) type I receptor (AT1R) blocker (ARB) on the progression of renal injury in rat anti-glomerular basement membrane glomerulonephritis (GN), with a particular focus on the participation of glomerular RAS activation in glomerular structural alterations, inflammation, and oxidative stress. Nephritic rats were divided into 2 groups and treated with vehicle or ARB until day 28. Treatment with ARB improved proteinuria significantly in nephritic rats. Vehicle-treated nephritic rats developed crescentic GN accompanied by marked macrophage infiltration and the enhanced expression of glomerular α-smooth muscle actin (α-SMA), angiotensinogen (AGT), Ang II, AT1R, and NADPH oxidase (Nox2) on days 7 and 28 of GN. ARB improved pathologic alterations such as crescent formation and glomerulosclerosis, and it had a significant inhibitory effect on the levels of these parameters on day 28 of GN. Enhanced superoxide production in nephritic glomeruli was decreased also by ARB. Moreover, Ang II and transforming growth factor beta (TGF-β) in the supernatant of cultured glomeruli was increased significantly in vehicle-treated nephritic rats whereas ARB inhibited the production of these compounds significantly on day 28. These results indicate that increased glomerular RAS activity and the resulting Ang II play important roles in progressive glomerular injury-the induction of oxidative stress and TGF-β expression, and they suggest that AT1R blockade attenuates proteinuria and progressive glomerular remodeling via the suppression of glomerular RAS activation in GN.

Effects of losartan, in monotherapy or in association with hydrochlorothiazide, in chronic nephropathy resulting from losartan treatment during lactation

We recently standardized a model (L(Lact)) of severe chronic kidney disease based on impaired nephrogenesis by suppression of angiotensin II activity during lactation (Machado FG, Poppi EP, Fanelli C, Malheiros DM, Zatz R, Fujihara CK. Am J Physiol Renal Physiol 294: F1345-F1353, 2008). In this new study of the L(Lact) model, we sought to gain further insight into renal injury mechanisms associated with this model and to verify whether the renoprotection obtained with the association of the angiotensin II receptor blocker losartan (L) and hydrochlorothiazide (H), which arrested renal injury in the remnant kidney model, would provide similar renoprotection. Twenty Munich-Wistar dams, each nursing six pups, were divided into control, untreated, and L(Lact) groups, given losartan (L; 250 mg·kg(-1)·day(-1)) until weaning. The male L(Lact) offspring remained untreated until 7 mo of age, when renal functional and structural parameters were studied in 17 of them, used as pretreatment control (L(Lact)Pre), and followed no further. The remaining rats were then divided among groups L(Lact)+V, untreated; L(Lact)+L, given L (50 mg·kg(-1)·day(-1)) now as a therapy; L(Lact)+H, given H (6 mg·kg(-1)·day(-1)); and L(Lact)+LH, given L and H. All parameters were reassessed 3 mo later in these groups and in age-matched controls. At this time, L(Lact) rats exhibited hypertension, severe albuminuria, glomerular damage, marked interstitial expansion/inflammation, enhanced cell proliferation, myofibroblast infiltration, and creatinine retention. L monotherapy normalized albuminuria and prevented hypertension and the progression of renal injury, inflammation, and myofibroblast infiltration. In contrast to the remnant model, the LH combination promoted only slight additional renoprotection, perhaps because of a limited tendency to retain sodium in L(Lact) rats.

Protective effect of mesenchymal stem cells on renal tubular epithelial cells in mice under ischemia/reperfusion

Objective To observe the effects of mesenchymal stem cells (MSCs) on self-repair of renal tubular epithelial cells ( RTECs) in mice under ischemia/reperfusion ( IR). Methods MSCs in C57BL/6 mice were successfully isolated by Percoll density gradient centrifugation and adherence cultivation, then marked with BrdU. Forty-five healthy male C57BL/6 mice were assigned to control group (n =15 ) , I/R group (n = 15 , clamping bilateral renal pedicles and then reopening after 30 min) , I/R + BrdU-MSCs group (n = 15 , clamping bilateral renal pedicles and then reopening after 30 min, meanwhile, BrdU-marked MSCs were injected through caudal vein into the body of model mice). One, 2,3,7 and 14 days later, the mice were killed (n = 3/each group) , and blood and kidneys were obtained. Serum creatinine (Scr) and urea nitrogen (BUN) were determined, and mice kidneys were stained with Hematoxylin and Eosin ( HE) to observe their pathological changes. The distribution of MSCs in mice was observed by using fluorescence histochemistry. The expression of proliferating cell nuclear antigen ( PCNA) in RTECs was assessed by using immunohistological staining. The apoptosis of RTECs was detected by using TUNEL. The protein levels of Caspase-3 and bcl-2 in renal tubules on the day 2 after establishing the model were detected by using Western blotting. Results The positive BrdU marking ratio was (98. 71 ±0. 32) % in MSCs.As compared with I/R group, the levels of BUN and Scr in I/R + BrdU-MSCs group were significantly reduced, and pathological changes in renal tubules were alleviated significantly. BrdU-marked MSCs desposited in the kidneys of I/R + BrdU-MSCs group. The positive PCNA expression of RTECs was increased significantly after intervention of BrdU-MSCs (P ＜0. 05 or P ＜0. 01) , while the apoptosis relieved significantly. Western blotting analysis revealed: as compared with I/R group, the level of Caspase-3 in I/R + BrdU-MSCs group was decreased notably [(1.16±0.33) vs (1.64±0.27), P＜0.01], while the level of bcl-2 increased significantly [(0.94±0.27) vs (0.68±0.15), P＜0.01). Conclusion Acute renal injury by I/R can induce MSCs homing to injured kidney and anchoring here. The anchored MSCs can contribute to RTECs' self-repair of mice under ischemia/reperfusion, inhibit their apoptosis, which is helpful to the RTECs' self-repair and can delay the progression of renal injury. Key words: Mesenchymal stem cells; Ischemia/reperfusion; Renal tubular; Epithelial cells

C-reactive protein promotes acute renal inflammation and fibrosis in unilateral ureteral obstructive nephropathy in mice

Elevated blood level of C-reactive protein (CRP) is associated with increased risk of chronic kidney disease. However, whether this association reflects functional importance of CRP in the pathogenesis of kidney disease remains unclear. In this study, we examined the biological role of CRP in a well-characterized model of progressive kidney disease, unilateral ureteral obstruction (UUO), in mice that express the human CRP gene (CRPtg). Compared with wild-type (Wt) mice at 3 days after UUO, CRPtg mice developed more severe renal inflammation with a significant increase in tubulointerstitial T cells and macrophages, upregulation of proinflammatory cytokines (IL-1β and TNF-α), chemokines (MCP-1), and adhesion molecules (ICAM-1). Renal fibrosis was also significantly enhanced in CRPtg mice as demonstrated by increased expression of tubulointerstitial α-smooth muscle actin and collagen types I and III compared with Wt mice. Interestingly, on days 7 and 14 after UUO, an equal severity of renal inflammation and fibrosis were observed in CRPtg and Wt mice. These findings suggested that CRP may have a role in the initiation of renal inflammation and fibrosis. Further study revealed that enhanced early renal inflammation and fibrosis on day 3 in CRPtg mice was associated with a significant upregulation of endogenous mouse CRP and FcγRI mRNA and increased activation of both NF-κB/p65 and TGF-β/Smad2/3 signaling, while equal severity of progressive renal injury at day 7 and day 14 between CRPtg and Wt mice were attributed to equivalent levels of CRP, FcγRI, phospho-NF-κB/p65, and TGF-β/Smad2/3 signaling. Based on these findings, we conclude that CRP may not only be a biomarker, but also a mediator in the early development of renal inflammation and fibrosis in a mouse model of UUO. Enhanced activation of both NF-κB and TGF-β/Smad signaling pathways may be mechanisms by which CRP promotes early renal inflammation and fibrosis.

Atherosclerotic Renal Artery Stenosis

Occlusive disease of the renal arteries poses a major problem. Most cases result from atherosclerotic disease, and the prevalence of incidental renal artery disease detected during imaging studies for symptomatic coronary, aortic, and peripheral vascular disease ranges from 14% to >35%, increasing with age.1 Although many (perhaps most) of these lesions produce only minor hemodynamic effects, it has long been recognized that when some “critical” level of occlusion is breached, poststenotic renal blood flow and glomerular filtration rate (GFR) fall, especially after lowering systemic arterial pressure. In some cases, kidney function can recover after restoring blood flow with either endovascular or surgical revascularization. Several prospective, randomized trials have examined whether the loss of renal function due to atherosclerotic renal artery stenosis can be managed best by medical therapy alone or would further benefit from renal revascularization.2,3 The study reported by Madder and colleagues4 in this issue of Circulation: Cardiovascular Interventions directly challenges whether conventional criteria for estimating GFR and directional trends in such trials are valid. This matter is important for physicians serious about considering renovascular disease. Article see p 219 Atherosclerotic renal artery stenosis (ARAS) is primarily a disease of older persons, with mean ages for most series >70 years.1 Patient series subjected to renal artery procedures routinely have reduced kidney function, usually expressed as reduced GFR. Despite remarkable improvements for many hypertensive and cardiovascular end points, such as stroke and myocardial infarction, attributable in part to effective medical intervention, the prevalence of end-stage renal disease has continued to increase over the past several decades. These observations raise the possibility that occlusive ARAS may be partly responsible for progressive renal injury. How best to evaluate and characterize kidney function in these trials has been controversial. Previous observational reports of renal revascularization used a …

Dendrin Location in Podocytes Is Associated with Disease Progression in Animal and Human Glomerulopathy

Background: Adriamycin (ADR) nephrosis in mice has been extensively studied and has enabled a greater understanding of the processes underlying the progression of renal injury. Dendrin is a novel component of the slit diaphragm with proapoptotic signaling properties, and it accumulates in the podocyte nucleus in response to glomerular injury in mice. The present study re-evaluated chronic progressive nephropathy in ADR mice and the localization of dendrin in mice and in human glomerulopathy. Methods: To investigate the localization of dendrin, a mouse model of nephrosis and glomerulosclerosis was used, in which ADR was injected once. WT-1-positive cells and apoptotic cells were counted in vivo and in vitro. To check the expression of dendrin in ADR mice, immunostaining and Western blot were performed. A survey of dendrin staining was performed on human kidney biopsy specimens. Results: The injection of ADR induced proteinuria, podocyte loss and glomerulosclerosis. It also caused the relocation of dendrin from the slit diaphragm to the podocyte nucleus. We demonstrated the location of dendrin to podocyte nuclei in several cases of human glomerulopathy. The mean occurrence of dendrin-positive nucleus per glomerulus increased in several cases of human glomerulopathy. Conclusions: These findings suggest that the relocation of dendrin to the podocyte nuclei is useful as a novel marker of podocyte injury in human glomerulopathy.

The SLAM family member CD48 ( Slamf2) protects lupus-prone mice from autoimmune nephritis

Polymorphisms in the SLAM family of leukocyte cell surface regulatory molecules have been associated with lupus-like phenotypes in both humans and mice. The murine Slamf gene cluster lies within the lupus-associated Sle1b region of mouse chromosome 1. Non-autoreactive C57BL/6 (B6) mice that have had this region replaced by syntenic segments from other mouse strains ( i.e. 129, NZB and NZW) are B6 congenic strains that spontaneously produce non-nephritogenic lupus-like autoantibodies. We have recently reported that genetic ablation of the SLAM family member CD48 ( Slamf2) drives full-blown autoimmune disease with severe proliferative glomerulonephritis (CD48GN) in B6 mice carrying 129 sequences of the Sle1b region (B6.129CD48 −/−). We also discovered that BALB/c mice with the same 129-derived CD48-null allele (BALB.129CD48 −/−) have neither nephritis nor anti-DNA autoantibodies, indicating that strain specific background genes modulate the effects of CD48 deficiency. Here we further examine this novel model of lupus nephritis in which CD48 deficiency transforms benign autoreactivity into fatal nephritis. CD48GN is characterized by glomerular hypertrophy with mesangial expansion, proliferation and leukocytic infiltration. Immune complexes deposit in mesangium and in sub-endothelial, sub-epithelial and intramembranous sites along the glomerular basement membrane. Afflicted mice have low-grade proteinuria, intermittent hematuria and their progressive renal injury manifests with elevated urine NGAL levels and with uremia. In contrast to the lupus-like B6.129CD48 −/− animals, neither BALB.129CD48 −/− mice nor B6 × BALB/c F1.129CD48 −/− progeny have autoimmune traits, indicating that B6-specific background genes modulate the effect of CD48 on lupus nephritis in a recessive manner.

Hematopoietic growth factor inducible neurokinin-1 (Gpnmb/Osteoactivin) is a biomarker of progressive renal injury across species

We sought to find a urinary biomarker for chronic kidney disease and tested hematopoietic growth factor inducible neurokinin-1 (HGFIN, also known as Gpnmb/Osteoactivin) as it was found to be a kidney injury biomarker in microarray studies. Here, we studied whether HGFIN is a marker of kidney disease progression. Its increase in kidney disease was confirmed by real-time PCR after 5/6 nephrectomy, in streptozotocin-induced diabetes, and in patients with chronic kidney disease. In the remnant kidney, HGFIN mRNA increased over time reflecting lesion chronicity. HGFIN was identified in the infarct portion of the remnant kidney in infiltrating hematopoietic interstitial cells, and in distal nephron tubules of the viable remnant kidney expressed de novo with increasing time. In vitro, it localized to cytoplasmic vesicles and cell membranes. Epithelial cells lining distal tubules and sloughed luminal tubule cells of patients expressed HGFIN protein. The urine HGFIN-to-creatinine ratio increased over time after 5/6 nephrectomy; increased in patients with proteinuric and polycystic kidney disease; and remained detectable in urine after prolonged freezer storage. The urine HGFIN-to-creatinine ratio compared favorably with the urine neutrophil gelatinase-associated lipocalin (NGAL)-to-creatinine ratio (both measured by commercial enzyme-linked immunosorbent assays (ELISAs)), and correlated strongly with proteinuria, but weakly with estimated glomerular filtration rate and serum creatinine. Thus, HGFIN may be a biomarker of progressive kidney disease.

Long-term administration of the histone deacetylase inhibitor vorinostat attenuates renal injury in experimental diabetes through an endothelial nitric oxide synthase-dependent mechanism.

Epigenetic changes in gene expression play a role in the development of diabetic complications, including nephropathy. Histone deacetylases (HDACs) are a group of enzymes that exert epigenetic effects by altering the acetylation status of histone and nonhistone proteins. In the current study, we investigated the action of the clinically available HDAC inhibitor vorinostat in a mouse model of diabetic nephropathy, with the following aims: to define its effect on the progression of renal injury and to explore its mechanism of action by focusing on its role in regulating the expression of endothelial nitric oxide synthase (eNOS). Control and streptozotocin-diabetic wild-type and eNOS(-/-) mice were treated with vorinostat by daily oral dosing for 18 weeks. Without affecting either blood glucose concentration or blood pressure, vorinostat decreased albuminuria, mesangial collagen IV deposition, and oxidative-nitrosative stress in streptozotocin-wild-type mice. These attenuating effects were associated with a >50% reduction in eNOS expression in mouse kidneys and in cultured human umbilical vein endothelial cells. Vorinostat treatment had no effect on albuminuria, glomerular collagen IV concentration, or mesangiolysis in diabetic mice genetically deficient in eNOS. These observations illustrate the therapeutic efficacy of long-term HDAC inhibition in diabetic nephropathy and emphasize the importance of the interplay between eNOS activity and oxidative stress in mediating these effects.

Endothelin-A receptor blockade slows the progression of renal injury in experimental renovascular disease

Endothelin (ET)-1, a potent renal vasoconstrictor with mitogenic properties, is upregulated by ischemia and has been shown to induce renal injury via the ET-A receptor. The potential role of ET-A blockade in chronic renovascular disease (RVD) has not, to our knowledge, been previously reported. We hypothesized that chronic ET-A receptor blockade would preserve renal hemodynamics and slow the progression of injury of the stenotic kidney in experimental RVD. Renal artery stenosis, a major cause of chronic RVD, was induced in 14 pigs and observed for 6 wk. In half of the pigs, chronic ET-A blockade was initiated (RVD+ET-A, 0.75 mg·kg(-1)·day(-1)) at the onset of RVD. Single-kidney renal blood flow, glomerular filtration rate, and perfusion were quantified in vivo after 6 wk using multidetector computer tomography. Renal microvascular density was quantified ex vivo using three-dimensional microcomputer tomography, and growth factors, inflammation, apoptosis, and fibrosis were determined in renal tissue. The degree of stenosis and increase in blood pressure were similar in RVD and RVD+ET-A pigs. Renal hemodynamics, function, and microvascular density were decreased in the stenotic kidney but preserved by ET-A blockade, accompanied by increased renal expression of vascular endothelial growth factor, hepatocyte growth factor, and downstream mediators such as phosphorilated-Akt, angiopoietins, and endothelial nitric oxide synthase. ET-A blockade also reduced renal apoptosis, inflammation, and glomerulosclerosis. This study shows that ET-A blockade slows the progression of renal injury in experimental RVD and preserves renal hemodynamics, function, and microvascular density in the stenotic kidney. These results support a role for ET-1/ET-A as a potential therapeutic target in chronic RVD.

'Congenital solitary functioning kidneys: which ones warrant follow-up into adult life?'

Congenital anomalies of the kidney and urinary tract (CAKUT) are the leading cause of paediatric end-stage renal failure (ESRF) [1, 3]. The clinical spectrum of CAKUT includes a variety of malformations of the urinary tract. Understanding the rate of progression for the different CAKUT categories and predicting long-term outcome is critical for a correct clinical management of these patients and for the transition of care from paediatric to adult nephrology. Among CAKUT categories, congenital solitary functioning kidney (SFK) has been the object of debate whether it constitutes a benign condition or presents a significant risk of progression to ESRF [2–14]. In the present issue of Nephrology Dialysis and Transplantation, Westland et al. report on the results of the KIMONO-study (REF ID pending). The authors analysed a large cohort of 206 children with SFK of congenital origin to identify indicators of renal injury. Among them, 116 had a primary congenital solitary functioning kidney (pSFK) and 90 had a secondary solitary functioning kidney (sSFK) after unilateral nephrectomy due to congenital anomalies of the kidney or urinary tract. Ipsilateral CAKUT was present in ~30% of children from both groups. Among the patients with pSFK (which encompasses unilateral renal agenesis and multicystic dysplastic kidney), ipsilateral anomalies were significantly more frequent in cases with renal agenesis. Similarly, high blood pressure was present in comparable proportions between pSFK and sSFK, and it was significantly higher in the subgroup with renal agenesis. About 20% of children were using renoprotective agents and ~12% had albuminuria. Overall, >30% of patients with SFK showed evidence of renal injury. These data indicate that a significant fraction of children with congenital solitary kidney show evidence of renal parenchyma damage early in life and can potentially progress to ESRF in adulthood. These numbers are consistent with our previous report on long-term outcome in CAKUT patients, in which 50% of children with solitary kidney reached ESRF by the age of 30 [11]. Westland et al. explored the rate of progression by generalized estimated equation (GEE) analysis (REF ID pending). Microalbuminuric-range proteinuria appeared at the age of 18 years in both pSFK and sSFK, and children with CAKUT showed a more pronounced increment. GEE analyses (to be taken cautiously) point to a slow progression of renal injury during adolescence, which suggests that a significant fraction of patients will progress to renal failure during adulthood. Again, these data seem to be supported by our outcome data, in which the majority of patients with SFK reached ESRF after the age of 18 [11]. Therefore, a large number of children who are diagnosed with congenital solitary kidney in early life will progress to chronic renal failure requiring replacement therapy in adulthood, without a smooth transition from paediatric care. The difficulties of understanding the natural history of congenital solitary kidney stand on several observations that have not been elucidated so far and remain unresolved by the present report. First, a clear definition of the phenotype of the patients investigated is not available. Westland et al. cluster unilateral renal agenesis and the involution of multicystic dysplastic kidney together into one category and all solitary functioning kidneys that result from other congenital anomalies of the urinary tract that require nephrectomy or lead to a complete loss of function of one kidney in another category. This stratification, although potentially useful, is arbitrary in consideration of the possibly different molecular origin and clinical course of the different conditions. Therefore, until molecular genetics can improve the diagnosis, any classification and grouping for statistical purposes is arbitrary and invariably results in

Intra‐renal Administration of VEGF: A Potential Therapeutic Approach for Renovascular Disease

Vascular endothelial growth factor (VEGF) promotes microvascular (MV) proliferation and repair. We have shown that a pre-emptive intra-renal administration of VEGF preserves the function of the stenotic kidney by protecting the renal microcirculation. This study was designed to extend those observations and determine whether intra-renal administration of VEGF can halt the progression and reverse renal injury. Unilateral renal artery stenosis (RAS) was induced in 6 pigs and after 6 weeks of RAS, VEGF-165 was single-infused intra-renally (RAS+VEGF, 0.05 ug/kg) in the stenotic kidney and observed for 4 additional weeks. Additional animals were used as normal and untreated RAS time-controls (n=6 each), and followed for 10 weeks. Single-kidney function was assessed in vivo using ultra-fast CT before (6 weeks) and after VEGF (10 weeks). Pigs were then euthanized, the stenotic kidney removed, and the renal microcirculation quantified using 3D micro-CT. Degree of RAS and hypertension were similar in RAS and RAS+VEGF at 6 and 10 weeks. Renal blood flow (RBF), glomerular filtration rate (GFR), and MV density were similarly decreased in all RAS pigs at 6 weeks compared to normal controls. At 10 weeks, RBF, GFR, and MV density remained unchanged in untreated RAS. However, intra-renal VEGF led to a 20–50% increase in RBF, GFR, and perfusion (p<0.05 vs. pre-VEGF) and augmented cortical MV density (p=NS vs. Normal, p<0.05 vs. RAS). A single intra-renal infusion of VEGF into the stenotic kidney reversed renal dysfunction, which was associated and likely mediated by a targeted effect on the renal microvasculature. This study underscores that the renal MV damage and loss is an important determinant of the progression of renal injury and supports the potential of a novel therapeutic approach to protect the kidney in chronic RAS.