Negative Modulation of B Cell Activation by Melanocortin 1 Receptor Signaling Protects against Membranous Nephropathy.

SIGNIFICANCE STATEMENT: Emerging evidence suggests that melanocortin neuropeptides-specifically adrenocorticotropic hormone-offer a novel, steroidogenic-independent therapeutic modality for membranous nephropathy (MN). The molecular mechanism underlying this beneficial effect, however, remains largely elusive. To investigate whether melanocortins modulate humoral immunity, the authors induced passive Heymann nephritis, a model of human MN, in wild-type and melanocortin 1 receptor (MC1R) knockout rats and treated them with melanocortin agents. Additional rats received adoptive transfer of bone marrow-derived cells beforehand from wild-type or MC1R knockout rats. The findings indicate that MC1R signaling plays a key role in negative modulation of B-cell activation and thereby suppresses humoral immune responses in passive Heymann nephritis, and suggest that MC1R signaling might offer a novel B cell-targeted therapeutic strategy for MN. BACKGROUND: Emerging evidence suggests that the pituitary neuropeptide melanocortins-specifically, adrenocorticotropic hormone-offer a novel nonsteroidogenic therapeutic modality for membranous nephropathy (MN). However, the mechanism(s) of action remains elusive. METHODS: To investigate whether melanocortins modulate humoral immunity, we induced passive Heymann nephritis (PHN), a model of MN, in wild-type (WT) and melanocortin 1 receptor (MC1R) knockout (KO) rats. We treated the animals with melanocortin agents-repository corticotropin injection, the nonsteroidogenic pan-melanocortin receptor agonist [Nle 4 , DPhe 7 ]-α-melanocyte stimulating hormone, the selective MC1R agonist MS05, vehicle gel, or phosphate-buffered saline-and evaluated kidney function, histology, and molecular changes. Additional rats received adoptive transfer of syngeneic bone marrow-derived cells beforehand from WT or MC1R KO rats. RESULTS: KO of MC1R worsened PHN and this was associated with increased deposition of autologous immunoglobulin G (IgG) and complement C5b-9 in glomeruli and higher circulating levels of autologous IgG-evidence of a sensitized humoral immune response. Melanocortin therapy ameliorated PHN in WT rats, coinciding with reduced glomerular deposition of autologous IgG and C5b -9. The beneficial efficacy of melanocortins was blunted in KO rats but restored by adoptive transfer of syngeneic bone marrow-derived cells derived from WT rats. Mechanistically, MC1R was expressed in B lymphocytes and was negatively associated with B cell activation. MC1R agonism triggered the expression of microphthalmia-associated transcription factor in activated B cells in a cAMP-dependent mode and also repressed the expression of interferon regulatory factor 4 (a lymphoid transcription factor essential for B-cell development and maturation), resulting in suppressed plasma cell differentiation and IgG production. CONCLUSIONS: MC1R signaling negatively modulates B cell activation and suppresses humoral immune responses in PHN, suggesting that MC1R signaling might offer a novel therapeutic target for MN.

Hematopoietic-specific melanocortin 1 receptor signaling protects against nephrotoxic serum nephritis and mediates the beneficial effect of melanocortin therapy.

The melanocortin hormone system has emerged as a novel therapeutic target for treating refractory glomerular diseases. However, the role of hematopoietic melanocortin 1 receptor (MC1R) signaling remains unknown. Upon insult by rabbit nephrotoxic serum, MC1R null-mutant mice developed more severe crescentic glomerulonephritis than wild-type mice, marked by aggravated proteinuria, kidney dysfunction and histologic lesions. Melanocortin therapy, using Repository Corticotropin Injection (Acthar Gel), the pan-melanocortin receptor agonist NDP-MSH, or the MC1R agonist MS05, ameliorated experimental nephritis in wild-type mice but this effect was blunted in null mice. Exacerbated experimental nephritis in null mice was associated with increased glomerular deposition of autologous IgG and C5b-9, in parallel with higher circulating levels of autologous IgG2c and IgG3. Additionally, the Th1 immune response was potentiated in null mice with experimental nephritis, accompanied by diminished kidney FoxP3+ regulatory T cells. Kidney infiltration of macrophages was also augmented by MC1R deficiency with an enhanced M1 polarization. Moreover, adoptive transfer of syngeneic bone marrow-derived cells from wild-type mice mitigated experimental nephritis in null mice and restored the beneficial efficacy of melanocortins. Mechanistically, MC1R was expressed by diverse subsets of kidney leukocytes, including macrophages, T and B lymphocytes, and was inversely associated with the NFκB pathway, a key player in immune responses. MS05 attenuated the production of rabbit IgG-specific IgG2c and IgG3 in cultured wild-type splenocytes, and promoted M2 polarization in M1-primed wild-type macrophages, associated with NFκB inhibition. In contrast, in null splenocytes or macrophages, this effect of MS05 was barely detectable, but was mimicked by an NFκB inhibitor. Thus, hematopoietic MC1R signaling attenuates experimental nephritis and mediates the beneficial effect of melanocortin therapy via, in part, regulating the immune response.

Retrieval of renal function after renal artery stenting improves event-free survival in a subgroup analysis of the Cardiovascular Outcomes in Renal Atherosclerotic Lesions trial.

OBJECTIVE: The Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial, a multicenter randomized controlled trial with 947 patients, concluded that there was no benefit of renal artery stenting (RAS) over medical therapy. However, patients with chronic kidney disease (CKD) were not analyzed separately in the CORAL trial. CKD is a risk factor for cardiovascular and renal morbidity. We hypothesized that improved renal function after RAS would be associated with increased long-term survival and a lower risk of cardiovascular and renal events in patients with CKD. METHODS: This post hoc analysis of the CORAL trial included 842 patients with CKD stages 2 to 4 at baseline who were randomized to optimal medical therapy alone (OMT; n = 432) or RAS plus OMT (RAS + OMT; n = 410). Patients were categorized as responders or nonresponders based on the change in the estimated glomerular filtration rate (eGFR) from baseline to last follow-up (median, 3.6 years; interquartile range, 2.6-4.6 years). Responders were defined by a 20% or greater increase in eGFR from baseline; all others were designated as nonresponders. Event-free survival was defined as freedom from death and multiple cardiovascular and renal complications. Event-free survival was analyzed using the Kaplan-Meier method and log-rank test. Multivariable Cox proportional hazards regression analysis was used to identify independent predictors of event-free survival. RESULTS: The RAS + OMT group had a higher proportion of patients with improved renal function (≥20% increase in eGFR over baseline), compared with the OMT group (25.6% vs 17.1%; P = .003). However, event-free survival was no different for the two cohorts (P = .18 by the log-rank test). Multivariable Cox proportional hazards regression analysis identified four variables that independently correlated with event-free survival for the stented cohort. Higher preoperative eGFR (hazard ratio, 0.98; 95% confidence interval [CI], 0.96-0.99; P = .002) and being a responder to stenting (hazard ratio, 0.49; 95% CI, 0.26-0.95; P = .033) increased event-free survival, whereas a history of congestive heart failure (hazard ratio, 2.52; 95% CI, 1.46-4.35; P < .001) and a higher preoperative systolic BP (hazard ratio, 1.02; 95% CI, 1.01-1.03; P = .002) decreased event-free survival. Within the stented group, 105 of 410 patients (25.6%) were responders. Event-free survival was superior for responders, compared with nonresponders (P = .009 by log-rank test). The only independent preoperative negative predictor of improved renal function after stenting was diabetes (odds ratio, 0.37; 95% CI, 0.16-0.84; P = .017), which decreased the probability of improved renal function after RAS + OMT. A subset of patients (23.4%) after RAS had worsened renal function, but OMT alone produced an equivalent incidence of worsened renal function. An increased urine albumin/creatinine ratio was an independent predictor of worsened renal function after RAS. CONCLUSIONS: CORAL participants who demonstrated improved kidney function after RAS + OMT demonstrated improved event-free survival. This finding reinforces the need for predictors of outcome to guide patient selection for RAS.

Novel Model of Oxalate Diet-Induced Chronic Kidney Disease in Dahl-Salt-Sensitive Rats.

Diet-induced models of chronic kidney disease (CKD) offer several advantages, including clinical relevance and animal welfare, compared with surgical models. Oxalate is a plant-based, terminal toxic metabolite that is eliminated by the kidneys through glomerular filtration and tubular secretion. An increased load of dietary oxalate leads to supersaturation, calcium oxalate crystal formation, renal tubular obstruction, and eventually CKD. Dahl-Salt-Sensitive (SS) rats are a common strain used to study hypertensive renal disease; however, the characterization of other diet-induced models on this background would allow for comparative studies of CKD within the same strain. In the present study, we hypothesized that SS rats on a low-salt, oxalate rich diet would have increased renal injury and serve as novel, clinically relevant and reproducible CKD rat models. Ten-week-old male SS rats were fed either 0.2% salt normal chow (SS-NC) or a 0.2% salt diet containing 0.67% sodium oxalate (SS-OX) for five weeks.Real-time PCR demonstrated an increased expression of inflammatory marker interleukin-6 (IL-6) (p < 0.0001) and fibrotic marker Timp-1 metalloproteinase (p < 0.0001) in the renal cortex of SS-OX rat kidneys compared with SS-NC. The immunohistochemistry of kidney tissue demonstrated an increase in CD-68 levels, a marker of macrophage infiltration in SS-OX rats (p < 0.001). In addition, SS-OX rats displayed increased 24 h urinary protein excretion (UPE) (p < 0.01) as well as significant elevations in plasma Cystatin C (p < 0.01). Furthermore, the oxalate diet induced hypertension (p < 0.05). A renin-angiotensin-aldosterone system (RAAS) profiling (via liquid chromatography-mass spectrometry; LC-MS) in the SS-OX plasma showed significant (p < 0.05) increases in multiple RAAS metabolites including angiotensin (1-5), angiotensin (1-7), and aldosterone. The oxalate diet induces significant renal inflammation, fibrosis, and renal dysfunction as well as RAAS activation and hypertension in SS rats compared with a normal chow diet. This study introduces a novel diet-induced model to study hypertension and CKD that is more clinically translatable and reproducible than the currently available models.

Emerging Immunotherapeutic and Diagnostic Modalities in Carcinoid Tumors.

Evasion of innate immunity represents a frequently employed method by which tumor cells survive and thrive. Previously, the development of immunotherapeutic agents capable of overcoming this evasion has realized pronounced clinical utility across a variety of cancer types. More recently, immunological strategies have been investigated as potentially viable therapeutic and diagnostic modalities in the management of carcinoid tumors. Classic treatment options for carcinoid tumors rely upon surgical resection or non-immune pharmacology. Though surgical intervention can be curative, tumor characteristics, such as size, location, and spread, heavily limit success. Non-immune pharmacologic treatments can be similarly limited, and many demonstrate problematic side effects. Immunotherapy may be able to overcome these limitations and further improve clinical outcomes. Similarly, emerging immunologic carcinoid biomarkers may improve diagnostic capabilities. Recent developments in immunotherapeutic and diagnostic modalities of carcinoid management are summarized here.

Hemopexin accumulates in kidneys and worsens acute kidney injury by causing hemoglobin deposition and exacerbation of iron toxicity in proximal tubules.

Hemopexin, a heme scavenging protein, accumulates in the kidneys during acute kidney injury (AKI). However, the function of this accumulated hemopexin in the kidney is unclear. In both the cisplatin-induced and the unilateral kidney ischemia-reperfusion injury models of AKI, we found accumulation of hemoglobin and hemopexin in the kidneys localized to the proximal tubules. Next, hemopexin wild-type and knockout mice were compared in both AKI models and hemopexin wild type mice had significantly worse kidney injury. Furthermore, there was increased kidney expression of kidney injury molecule-1 (a biomarker of AKI) and heme oxygenase-1 (an indicator of oxidative stress) in hemopexin wild type compared with knockout mice in both models of AKI. Next, the interaction of hemopexin and hemoglobin in vitro was investigated using cultured proximal tubular cells. Co-incubation of hemopexin with hemoglobin resulted in hemoglobin deposition and exaggerated hemoglobin-induced injury. Deferoxamine, an iron chelator, and ferrostatin-1, a ferroptosis inhibitor, inhibited this deleterious effect of hemoglobin and hemopexin in proximal tubular cells, implicating iron toxicity in the mechanism of hemopexin mediated injury. Furthermore, the protective effect of deferoxamine in cisplatin-induced AKI was apparent in hemopexin wild type, but not in hemopexin knockout mice, further implicating hemopexin as a mediator of iron toxicity in AKI. Thus, our findings demonstrate that hemopexin accumulates in the kidneys and worsens kidney injury in AKI by increasing hemoglobin deposition on proximal tubular cells to exaggerate hemoglobin-induced cell injury.

The ketone body ß-hydroxybutyrate mitigates the senescence response of glomerular podocytes to diabetic insults.

Diabetic kidney disease (DKD) is one of the most common complications of diabetes and is clinically featured by progressive albuminuria, consequent to glomerular destruction that involves podocyte senescence. Burgeoning evidence suggests that ketosis, in particular ß-hydroxybutyrate, exerts a beneficial effect on aging and on myriad metabolic or chronic diseases, including obesity, diabetes and chronic kidney diseases. Its effect on DKD is largely unknown. In vitro in podocytes exposed to a diabetic milieu, ß-hydroxybutyrate treatment substantially mitigated cellular senescence and injury, as evidenced by reduced formation of γH2AX foci, reduced staining for senescence-associated-ß-galactosidase activity, diminished expression of key mediators of senescence signaling like p16INK4A and p21, and preserved expression of synaptopodin. This beneficial action of ß-hydroxybutyrate coincided with a reinforced transcription factor Nrf2 antioxidant response. Mechanistically, ß-hydroxybutyrate inhibition of glycogen synthase kinase 3ß (GSK3ß), a convergent point for myriad signaling pathways regulating Nrf2 activity, seems to contribute. Indeed, trigonelline, a selective inhibitor of Nrf2, or ectopic expression of constitutively active mutant GSK3ß abolished, whereas selective activation of Nrf2 was sufficient for the anti-senescent and podocyte protective effects of ß-hydroxybutyrate. Moreover, molecular modeling and docking analysis revealed that ß-hydroxybutyrate is able to directly target the ATP-binding pocket of GSK3ß and thereby block its kinase activity. In murine models of streptozotocin-elicited DKD, ß-hydroxybutyrate therapy inhibited GSK3ß and reinforced Nrf2 activation in glomerular podocytes, resulting in lessened podocyte senescence and injury and improved diabetic glomerulopathy and albuminuria. Thus, our findings may pave the way for developing a ß-hydroxybutyrate-based novel approach of therapeutic ketosis for treating DKD.

Glycogen synthase kinase 3ß hyperactivity in urinary exfoliated cells predicts progression of diabetic kidney disease.

Burgeoning evidence points to glycogen synthase kinase (GSK)3ß as a key player in diverse kidney diseases. However, as a pivotal transducer of the insulin signaling pathway, the role of GSK3ß in diabetic kidney disease remains uncertain. In db/db mice, renal expression of total and activated GSK3ß was increasingly elevated. This preceded the development of diabetic kidney disease, and correlated with the progression of signs of diabetic kidney injury, including albuminuria and extracellular matrix accumulation in glomeruli and tubulointerstitia. In vitro, exposure of glomerular podocytes, mesangial cells, and renal tubular cells to a diabetic milieu induced GSK3ß overexpression and hyperactivity, which seem essential and sufficient for eliciting diabetic cellular damages in kidney cells, because the cytopathic effect of the diabetic milieu was mitigated by GSK3ß knockdown, but was mimicked by ectopic expression of constitutively active GSK3ß even in the normal milieu. In consistency, kidney biopsy specimens procured from patients with varying stages of diabetic nephropathy revealed an amplified expression of total and activated GSK3ß in glomeruli and renal tubules, associated with the severity of diabetic nephropathy. Moreover, in retrospective cohorts of type 2 diabetic patients that were followed for over five years, the relative activity of GSK3ß in banked urinary exfoliated cells represented an independent risk factor for development or progression of renal impairment. Furthermore, receiver operating characteristic curve analysis demonstrated that GSK3ß activity in urinary exfoliated cells provided much better power than albuminuria in discriminating diabetic patients with progressive renal impairment from those with stable kidney function. Thus, renal expression and activity of GSK3ß are amplified in experimental and clinical diabetic nephropathy. Hence, GSK3ß in urinary exfoliated cells may serve as a novel biomarker for predicting diabetic kidney disease progression.

Relapse of Nephrotic Syndrome after Adrenocorticotropic Hormone-Induced Remission: Implications of Adrenocorticotropic Hormone Antibodies.

BACKGROUND: Prolonged use of corticosteroids continues to be the mainstay in the management of most proteinuric glomerulopathies, but is limited by extensive side effects. Alternative medications such as adrenocorticotropic hormone (ACTH) have been recently used to treat refractory glomerulopathies and have shown superior outcomes when compared with steroids. However, the clinical responsiveness to ACTH therapy varies considerably with a number of patients exhibiting de novo or acquired resistance. The underlying mechanism remains unknown. METHODS: A patient with steroid-dependent focal segmental glomerulosclerosis (FSGS) developed severe steroid side effects impacting quality of life and was converted to repository porcine ACTH therapy. Immediate response in the form of remission of nephrotic syndrome was noted followed by relapse in 10 weeks. Suspecting the role of some ACTH-antagonizing factors, the patient's serum was examined. RESULTS: Immunoblot-based antibody assay revealed high titers of de novo IgG antibodies in the patient's serum that were reactive to the porcine corticotropin with negligible cross-reactivity to human corticotropin. In vitro, in cultured B16 melanoma cells that express abundant melanocortin receptors, addition of the patient's serum substantially abrogated the porcine corticotropin triggered signaling activity of the melanocortinergic pathway, marked by phosphorylation of glycogen synthase kinase 3ß, thus suggesting a mitigating effect on the biological functionality of porcine corticotropin. CONCLUSION: ACTH is a useful alternative therapeutic modality for refractory proteinuric glomerulopathies like FSGS. However, as quintessential therapeutic biologics, natural ACTH, regardless of purity and origin, is inevitably antigenic and may cause the formation of neutralizing antibodies in some sensitive patients, followed by resistance to ACTH therapy. It is imperative to develop ACTH analogues with less immunogenicity for improving its responsiveness in patients with glomerular diseases.

Melanocortin therapy ameliorates podocytopathy and proteinuria in experimental focal segmental glomerulosclerosis involving a podocyte specific non-MC1R-mediated melanocortinergic signaling.

The clinical effectiveness of adrenocorticotropin in inducing remission of steroid-resistant nephrotic syndrome points to a steroidogenic-independent anti-proteinuric activity of melanocortins. However, which melanocortin receptors (MCR) convey this beneficial effect and if systemic or podocyte-specific mechanisms are involved remain uncertain. In vivo, wild-type (WT) mice developed heavy proteinuria and kidney dysfunction following Adriamycin insult, concomitant with focal segmental glomerulosclerosis (FSGS) and podocytopathy, marked by loss of podocin and synaptopodin, podocytopenia and extensive foot process effacement on electron microscopy. All these pathologic findings were prominently attenuated by NDP-MSH, a potent non-steroidogenic pan-MCR agonist. Surprisingly, MC1R deficiency in MC1R-null mice barely affected the severity of Adriamycin-elicited injury. Moreover, the beneficial effect of NDP-MSH was completely preserved in MC1R-null mice, suggesting that MC1R is likely non-essential for the protective action. A direct podocyte effect seems to contribute to the beneficial effect of NDP-MSH, because Adriamycin-inflicted cytopathic signs in primary podocytes prepared from WT mice were all mitigated by NDP-MSH, including apoptosis, loss of podocyte markers, de novo expression of the podocyte injury marker desmin, actin cytoskeleton derangement and podocyte hypermotility. Consistent with in vivo findings, the podoprotective activity of NDP-MSH was fully preserved in MC1R-null podocytes. Mechanistically, MC1R expression was predominantly distributed to glomerular endothelial cells in glomeruli but negligibly noted in podocytes in vivo and in vitro, suggesting that MC1R signaling is unlikely involved in direct podocyte protection. Ergo, melanocortin therapy protects against podocyte injury and ameliorates proteinuria and glomerulopathy in experimental FSGS, at least in part, via a podocyte-specific non-MC1R-mediated melanocortinergic signaling.

Relationship of mildly increased albuminuria and coronary artery revascularization outcomes in patients with diabetes.

BACKGROUND: The aim of this study was to examine the relationship of albuminuria to cardiovascular disease outcomes in diabetic patients undergoing treatment for stable coronary artery disease. METHODS AND RESULTS: We analyzed data from 2176 participants of the Bypass Angioplasty Revascularization Investigation in type-2 diabetes (BARI-2D) trial, a randomized clinical trial comparing Percutaneous coronary intervention/Coronary artery bypass grafting (PCI/CABG) to medical therapy for people with diabetes. The population was stratified by baseline spot urine albumin-creatinine ratio (uACR) into normal (uACR <10 mg/g), mildly (uACR ≥10 mg/g < 30 mg/g), moderately (uACR ≥30 mg/g < 300 mg/g) and severely increased (uACR ≥300 mg/g) groups, and outcomes compared between groups. Death, myocardial infarction (MI) and/or stroke were experienced by 489 patients at a mean follow-up of 4.3 ± 1.5 years. Compared with normal uACR, mildly increased uACR was associated with a 1.4 times (P = 0.042) increase in all-cause mortality. Additionally, nonwhites with type-II diabetes and stable coronary artery disease who had mildly increased albuminuria had a Hazard ratio (HR) of 3.3 times (P = 0.028) for cardiovascular death, 3.1 times for (P = 0.002) all-cause mortality, and two times for (P = 0.015) MI during follow-up. CONCLUSIONS: Mildly increased albuminuria is a significant predictor of all-cause mortality in those with type-II diabetes mellitus and stable coronary artery disease, as well as for cardiovascular events those who are nonwhites.

Residual Renal Function and Obstructive Sleep Apnea in Peritoneal Dialysis: A Pilot Study.

PURPOSE: Obstructive sleep apnea is common in patients with end-stage renal disease, and there is increasing evidence that clinical factors specific to end-stage renal disease contribute pathophysiologically to obstructive sleep apnea. It is not known whether circumstances specific to dialysis modality, in this case peritoneal dialysis, affect obstructive sleep apnea. Our study aimed to investigate the prevalence of obstructive sleep apnea in the peritoneal dialysis population and the relevance of dialysis-specific measures and kidney function in assessing this bidirectional relationship. METHODS: Participants with end-stage renal disease who were treated with nocturnal automated peritoneal dialysis for at least 3 months were recruited from a hospital-based dialysis center. Laboratory measures of dialysis adequacy, peritoneal membrane transporter status, and residual renal function were gathered by chart review. Patients participated in a home sleep apnea test using a level III sleep apnea monitor. RESULTS: Of fifteen participants recruited, 33% had obstructive sleep apnea diagnosed by apnea-hypopnea index ≥ 5 events per hour of sleep. Renal creatinine clearance based upon 24-h urine collection was negatively correlated with apnea-hypopnea index (ρ = - 0.63, p = 0.012). There were no significant associations between anthropometric measures, intra-abdominal dwell volume, or peritoneal membrane transporter status and obstructive sleep apnea measures. CONCLUSIONS: The prevalence of obstructive sleep apnea and sleep disturbances is high in participants receiving peritoneal dialysis. Elevated apnea-hypopnea index is associated with lower residual renal function, whereas dialysis-specific measures such as intra-abdominal dwell volume and peritoneal membrane transporter status do not correlate with severity of obstructive sleep apnea.

Correction to: Residual Renal Function and Obstructive Sleep Apnea in Peritoneal Dialysis: A Pilot Study.

The original version of this article unfortunately contained a mistake in the article title. The correct article title is "Residual Renal Function and Obstructive Sleep Apnea in Peritoneal Dialysis: A Pilot Study".

Stenting and medical therapy for atherosclerotic renal-artery stenosis.

BACKGROUND: Atherosclerotic renal-artery stenosis is a common problem in the elderly. Despite two randomized trials that did not show a benefit of renal-artery stenting with respect to kidney function, the usefulness of stenting for the prevention of major adverse renal and cardiovascular events is uncertain. METHODS: We randomly assigned 947 participants who had atherosclerotic renal-artery stenosis and either systolic hypertension while taking two or more antihypertensive drugs or chronic kidney disease to medical therapy plus renal-artery stenting or medical therapy alone. Participants were followed for the occurrence of adverse cardiovascular and renal events (a composite end point of death from cardiovascular or renal causes, myocardial infarction, stroke, hospitalization for congestive heart failure, progressive renal insufficiency, or the need for renal-replacement therapy). RESULTS: Over a median follow-up period of 43 months (interquartile range, 31 to 55), the rate of the primary composite end point did not differ significantly between participants who underwent stenting in addition to receiving medical therapy and those who received medical therapy alone (35.1% and 35.8%, respectively; hazard ratio with stenting, 0.94; 95% confidence interval [CI], 0.76 to 1.17; P=0.58). There were also no significant differences between the treatment groups in the rates of the individual components of the primary end point or in all-cause mortality. During follow-up, there was a consistent modest difference in systolic blood pressure favoring the stent group (-2.3 mm Hg; 95% CI, -4.4 to -0.2; P=0.03). CONCLUSIONS: Renal-artery stenting did not confer a significant benefit with respect to the prevention of clinical events when added to comprehensive, multifactorial medical therapy in people with atherosclerotic renal-artery stenosis and hypertension or chronic kidney disease. (Funded by the National Heart, Lung and Blood Institute and others; ClinicalTrials.gov number, NCT00081731.).

Enhancer of Zeste Homolog 2 Inhibition Attenuates Renal Fibrosis by Maintaining Smad7 and Phosphatase and Tensin Homolog Expression.

Enhancer of zeste homolog 2 (EZH2) is a methyltransferase that induces histone H3 lysine 27 trimethylation (H3K27me3) and functions as an oncogenic factor in many cancer types. However, the role of EZH2 in renal fibrogenesis remains unexplored. In this study, we found high expression of EZH2 and H3K27me3 in cultured renal fibroblasts and fibrotic kidneys from mice with unilateral ureteral obstruction and humans with CKD. Pharmacologic inhibition of EZH2 with 3-deazaneplanocin A (3-DZNeP) or GSK126 or siRNA-mediated silencing of EZH2 inhibited serum- and TGFß1-induced activation of renal interstitial fibroblasts in vitro, and 3-DZNeP administration abrogated deposition of extracellular matrix proteins and expression of α-smooth muscle actin in the obstructed kidney. Injury to the kidney enhanced Smad7 degradation, Smad3 phosphorylation, and TGFß receptor 1 expression, and 3-DZNeP administration prevented these effects. 3-DZNeP also suppressed phosphorylation of the renal EGF and PDGFß receptors and downstream signaling molecules signal transducer and activator of transcription 3 and extracellular signal-regulated kinase 1/2 after injury. Moreover, EZH2 inhibition increased the expression of phosphatase and tensin homolog (PTEN), a protein previously associated with dephosphorylation of tyrosine kinase receptors in the injured kidney and serum-stimulated renal interstitial fibroblasts. Finally, blocking PTEN with SF1670 largely diminished the inhibitory effect of 3-DZNeP on renal myofibroblast activation. These results uncovered the important role of EZH2 in mediating the development of renal fibrosis by downregulating expression of Smad7 and PTEN, thus activating profibrotic signaling pathways. Targeted inhibition of EZH2, therefore, could be a novel therapy for treating CKD.

Medical Neighborhood Model for the Care of Chronic Kidney Disease Patients.

BACKGROUND: The patient-centered medical home is a popular model of care, but the patient-centered medical neighborhood (PCMN) is rarely described. We developed a PCMN in an academic practice to improve care for patients with chronic kidney disease (CKD). The purpose of this study is to identify the prevalence of CKD in this practice and describe baseline characteristics, develop an interdisciplinary team-based approach to care and determine cost associated with CKD patients. METHODS: Patients with CKD stage 3a with comorbidities through stage 5 were identified. Data collected include demographics, comorbidities and whether patients had a nephrologist. Using a screening tool based on the 2012 Kidney Disease Improving Global Outcomes guidelines, a nurse care manager (NCM) made recommendations about management including indications for referral. A pharmacist reviewed patients' charts and made medication-related recommendations. Blue Cross Blue Shield (BCBS) insurance provided cost data for a subset of patients. RESULTS: A total of 1,255 patients were identified. Half did not have a formal diagnosis of CKD and three-quarters had never seen a nephrologist. Based on the results of the screening tool, the NCM recommended nephrology E-consult or full consult for 85 patients. The subset of BCBS patients had a mean healthcare cost of $1,528.69 per member per month. CONCLUSIONS: We implemented a PCMN that allowed for easy identification of a high-risk, high-cost population of CKD patients and optimized their care to reflect guideline-based standards.

Genetic or pharmacologic blockade of EGFR inhibits renal fibrosis.

Although enhanced activation of the EGF receptor (EGFR) associates with the development and progression of renal fibrosis, the mechanisms linking these observations are not completely understood. Here, after unilateral ureteral obstruction (UUO), wild-type mice exhibited sustained EGFR phosphorylation in the kidney and developed renal fibrosis that was more severe than the renal fibrosis observed in waved-2 mice, which have reduced EGFR tyrosine kinase activity. Waved-2 mice also showed fewer renal tubular cells arrested at G2/M, reduced expression of α-smooth muscle actin (α-SMA), downregulation of multiple genes encoding profibrogenic cytokines, including TGF-ß1, and dephosphorylation of Smad3, STAT3, and ERK1/2. Administration of the specific EGFR inhibitor gefitinib recapitulated this phenotype in wild-type mice after UUO. Furthermore, inactivation of either EGFR or STAT3 reduced UUO-induced expression of lipocalin-2, a molecule associated with the pathogenesis of CKD. In cultured renal interstitial fibroblasts, inhibition of EGFR also abrogated TGF-ß1- or serum-induced phosphorylation of EGFR, STAT3, ERK1/2, and Smad3 as well as expression of α-SMA and extracelluar matrix proteins. Taken together, these data suggest that EGFR may mediate renal fibrogenesis by promoting transition of renal epithelial cells to a profibrotic phenotype, increased production of inflammatory factors, and activation of renal interstitial fibroblasts. Inhibition of EGFR may have therapeutic potential for fibrotic kidney disease.

Antioxidant and Anti-Tumor Effects of Dietary Vitamins A, C, and E.

Oxidative stress, a condition characterized by an imbalance between pro-oxidant molecules and antioxidant defense systems, is increasingly recognized as a key contributor to cancer development. This is because the reactive oxygen species (ROS) generated during oxidative stress can damage DNA, proteins, and lipids to facilitate mutations and other cellular changes that promote cancer growth. Antioxidant supplementation is a potential strategy for decreasing cancer incidence; by reducing oxidative stress, DNA damage and other deleterious cellular changes may be attenuated. Several clinical trials have been conducted to investigate the role of antioxidant supplements in cancer prevention. Some studies have found that antioxidant supplements, such as vitamin A, vitamin C, and vitamin E, can reduce the risk of certain types of cancer. On the other hand, some studies posit an increased risk of cancer with antioxidant supplement use. In this review, we will provide an overview of the current understanding of the role of oxidative stress in cancer formation, as well as the potential benefits of antioxidant supplementation in cancer prevention. Additionally, we will discuss both preclinical and clinical studies highlighting the potentials and limitations of preventive antioxidant strategies.

Impact of renal artery stenosis on acute kidney injury and outcomes after heart failure hospitalization.

BACKGROUND: Renal artery stenosis (RAS) is known to co-exist with heart failure (HF), however the impact of RAS on rates of acute kidney injury during an acute HF hospitalization, and adverse events after acute HF hospitalizations has not been well studied. METHODS: We performed a retrospective cohort study of subjects hospitalized for acute HF at a tertiary academic care center. We identified subjects who had a renal artery duplex ultrasound or other diagnostic study for RAS to categorize heart failure subjects as RAS+ or RAS-. AKI was defined as a rise from admission to peak creatinine of >0.3 mg/dL or >1.5 fold. In-hospital outcomes including rates of AKI were ascertained. Adverse outcomes over a two-year follow up period were also ascertained. RESULTS: A total of 93 subjects with acute HF hospitalization met the inclusion criteria and were enrolled in this study; 27 (29%) were identified as RAS+. At admission, subjects with RAS had higher rates of diabetes and prior PCI. During the HF hospitalization, subjects with RAS were more likely to develop AKI. No significant differences were identified in baseline or hospital medication use among subjects with versus without RAS. Importantly, the rate of ACE-I/ARB use was low in both groups and no significant difference in ACE-I/ARB use was demonstrated. Subjects with RAS had higher rates of recurrent HF hospitalization during the follow-up period. CONCLUSIONS: RAS is prevalent among subjects with acute HF, associated with higher rates of AKI during HF hospitalization, and associated with higher rates of recurrent HF hospitalization during follow-up.

Inhibition of glycogen synthase kinase-3ß prevents NSAID-induced acute kidney injury.

Clinical use of nonsteroidal anti-inflammatory drugs (NSAIDs) like diclofenac (DCLF) is limited by multiple adverse effects, including renal toxicity leading to acute kidney injury. In mice with DCLF-induced nephrotoxicity, TDZD-8, a selective glycogen synthase kinase (GSK)3ß inhibitor, improved acute kidney dysfunction and ameliorated tubular necrosis and apoptosis associated with induced cortical expression of cyclooxygenase-2 (COX-2) and prostaglandin E2. This renoprotective effect was blunted but still largely preserved in COX-2-null mice, suggesting that other GSK3ß targets beyond COX-2 functioned in renal protection. Indeed, TDZD-8 diminished the mitochondrial permeability transition in DCLF-injured kidneys. In vitro, GSK3ß inhibition reinstated viability and suppressed necrosis and apoptosis in DCLF-stimulated tubular epithelial cells. DCLF elicited oxidative stress, enhanced the activity of the redox-sensitive GSK3ß, and promoted a mitochondrial permeability transition by interacting with cyclophilin D, a key component of the mitochondrial permeability transition pore. TDZD-8 blocked GSK3ß activity and prevented GSK3ß-mediated cyclophilin D phosphorylation and the ensuing mitochondrial permeability transition, concomitant with normalization of intracellular ATP. Conversely, ectopic expression of a constitutively active GSK3ß abolished the effects of TDZD-8. Hence, inhibition of GSK3ß ameliorates NSAID-induced acute kidney injury by induction of renal cortical COX-2 and direct inhibition of the mitochondrial permeability transition.