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Direct targeting to the kidneys is a promising strategy to improve drug therapeutic index for the treatment of kidney diseases. We sought to investigate the renal selectivity and safety of kidney-targeted mesoscale nanoparticle technology. We found that direct intravenous administration of these particles resulted in 26-fold renal selectivity and localized negligibly in the liver or other organs. The nanoparticles targeted the renal proximal tubular epithelial cells, as evidenced by intravital microscopy and ex vivo imaging. Mice treated with the nanoparticles exhibited no negative systemic consequences, immune reaction, liver impairment, or renal impairment. The localization of material selectively to the renal tubules is uncommon, and this work portends the development of renal-targeted drugs for the treatment of kidney diseases. [ABSTRACT FROM AUTHOR]

VEGF (vascular endothelial growth factor) receptor tyrosine kinase inhibitors have become first-line therapy for metastatic renal cell carcinoma. Their use commonly leads to hypertension, but their effects on long-term renal function are not known. In addition, it has been suggested that the development of hypertension is linked to treatment efficacy. The objective of this study was to determine the effects of these drugs on long-term renal function, especially in those with renal dysfunction at baseline, and to examine the role of hypertension on these effects. Serum creatinine measurements were used to calculate the estimated glomerular filtration rate for 130 renal cell carcinoma patients who were treated with this class of tyrosine kinase inhibitors. New or worsening hypertension was defined by documented start or addition of antihypertensive medications. Overall, the use of tyrosine kinase inhibitors in patients with estimated glomerular filtration <60 or ≥60 mL/min per 1.73 m2 was not associated with a decline in long-term renal function. During follow-up, 41 patients developed new or worsening hypertension within 30 days from first drug administration, and this was not linked to further reductions in glomerular filtration. These patients seemed to survive longer than those who did not develop hypertension within 30 days, although this was not statistically significant (P=0.07). Our findings suggest that the use of VEGF tyrosine kinase inhibitors does not adversely affect long-term renal function even in the setting of new-onset hypertension or reduced renal function at baseline. [ABSTRACT FROM AUTHOR]

Transcription factor E26 transformation-specific sequence-1 (ETS-1) is a transcription factor that regulates the expression of a variety of genes, including growth factors, chemokines, and adhesion molecules. We recently demonstrated that angiotensin II increases the glomerular expression of ETS-1 and that blockade of ETS-1 ameliorates the profibrotic and proinflammatory effects of angiotensin II. The Dahl salt-sensitive rat is a paradigm of salt-sensitive hypertension associated with local activation of the renin-angiotensin system. In these studies, we determined whether: (1) salt-sensitive hypertension is associated with renal expression of ETS-1 and (2) ETS-1 participates in the development of end-organ injury in salt-sensitive hypertension. Dahl salt-sensitive rats were fed a normal-salt diet (0.5% NaCl diet) or a high-salt diet (4% NaCl) for 4 weeks. Separate groups on high-salt diet received an ETS-1 dominant-negative peptide (10 mg/kg/d), an inactive ETS-1 mutant peptide (10 mg/kg/d), the angiotensin II type 1 receptor blocker candesartan (10 mg/kg/d), or the combination high-salt diet/dominant-negative peptide/angiotensin II type 1 receptor blocker for 4 weeks. High-salt diet rats had a significant increase in the glomerular expression of the phosphorylated ETS-1 that was prevented by angiotensin II type 1 receptor blocker. ETS-1 blockade reduced proteinuria, glomerular injury score, fibronectin expression, urinary transforming growth factor-β excretion, and macrophage infiltration. Angiotensin II type 1 receptor blocker reduced proteinuria, glomerular injury score, and macrophage infiltration, whereas concomitant ETS-1 blockade and angiotensin II type 1 receptor blocker had additive effects and reduced interstitial fibrosis. Our studies demonstrated that salt-sensitive hypertension results in increased glomerular expression of phosphorylated ETS-1 and suggested that ETS-1 plays an important role in the pathogenesis of end-organ injury in saltsensitive hypertension. [ABSTRACT FROM AUTHOR]

The article tests the hypothesis that erythroblastosis virus E26 oncogen homolog-1 (ETS-1) is a common mediator of the renal proinflammatory profibrotic effects of Angiotensis II (Ang II). Studies suggest that ETS-1 is a common mediator of the proinflammatory and profibrotic effects of Ang II-induced hypertensive renal damage. Such mediation may result in the development of novel strategies in the treatment and prevention of end-organ injury in hypertension.

The transcription factor ETS-1 is a critical mediator of vascular inflammation and hypertrophy in hypertension. We tested the hypothesis that ETS-1 is a mediator of proinflammatory responses and neointimal hyperplasia after balloon injury of the carotid artery. For this study, we took advantage of the availability of an ETS-1 dominant-negative (DN) peptide. Sprague-Dawley rats were assigned to treatment with ETS-1 DN, a mutant peptide (ETS-1 MU), or vehicle (Veh) and subjected to balloon injury of the carotid artery. After 2, 24 hours, and 14 days, the rats were euthanized, and both carotid arteries were processed for real-time polymerase chain reaction (2 hours), immunofluorescence and immunohistochemistry (24 hours), and morphometric analysis (14 days). ETS-1 mRNA was up regulated (2.4-fold) in injured carotid arteries. By immunofluorescence, we confirmed increased nuclear expression of ETS-1 24 hours postinjury. The carotid artery mRNA expression of monocyte chemotactic protein-1, cytokine-induced neutrophil chemoattractant-2, P-selectin, E-selectin, vascular cell adhesion molecule, and intercellular adhesion molecule was increased 2 hours after injury. ETS-1 DN but not ETS-1 MU significantly reduced mRNA and protein expression for monocyte chemotactic protein-1, P-selectin, and E-selectin in injured arteries. These changes were accompanied by concomitant reductions in vascular monocyte and leukocyte infiltration. Moreover, treatment with ETS-1 DN but not ETS-1 MU resulted in a 50% reduction in neointima formation at day 14 after balloon injury. This study unveils the role of ETS-1 as a mediator of inflammation and neointima formation in a model of carotid artery balloon injury and may result in the development of novel strategies in the treatment of vascular injury. [ABSTRACT FROM AUTHOR]

The transcription factor ETS-1 regulates the expression of several growth factors, chemokines and cytokines. We have recently shown that ETS-1 is a mediator of the pro-inflammatory and pro-fibrotic effects of Angiotensin II in the kidney (HTN ’12). Herein, we tested the hypothesis that the renal expression of ETS-1 is increased in the Dahl salt-sensitive (DS) rat, a paradigm of salt-sensitive hypertension in humans, and that ETS-1 mediates renal injury in this model of hypertension. DS rats (n=6 per group) were fed a normal salt diet (0.5% NaCl, NS) or a high salt diet (4% NaCl, HS) for 4 weeks. Four additional groups (n=6 per group) on HS diet received: ETS-1 dominant negative peptide (HS/DN, 10mg/kg/day) to block ETS-1, a control ETS-1 mutant peptide (HS/MU, 10mg /kg/day), the AT1 receptor blocker Candesartan (HS/ARB 10 mg/kg/day) or a combination of DN and ARB (HS/DN/ARB). HS rats had a ~ 3 fold increase in the cortical expression of ETS-1 as assessed by western blot (WB). Treatment with DN, MU, ARB or DN/ARB resulted in small and non-significant reductions in BP as compared to HS. (Table). Compared with LS, HS rats had increased proteinuria (Bio-Rad), higher glomerular injury score (GIS), increased fibronectin expression (WB) and urinary TGF-β (ELISA) that were improved by DN but not by MU (table). ARB reduced proteinuria and GIS (table). Treatment with DN/ARB resulted in further improvements in renal injury as compared to DN and ARB (table).In conclusion we have demonstrated that hypertensive DS rats have increased cortical expression of ETS-1 and that blockade of ETS-1 improves renal injury in this model of hypertension. [ABSTRACT FROM AUTHOR]

High prorenin levels in the circulation are associated with the progression of diabetic nephropathy and microvascular changes in diabetes. In spite of high plasma prorenin, the urine of diabetes mellitus patients exhibits very low pH and contains high levels of “active” renin, but low levels of prorenin. Prorenin binding to the prorenin receptor (PRR) results in non-proteolytic activation of prorenin and stimulation of intracellular synthesis of transforming growth factor-beta (TGF-β). Furthermore, the PRR cytosolic domain is associated with the vacuolar H+-ATPase, which is involved in acid-base homeostasis by renal intercalated cells. In diabetes, the collecting duct is the major source of prorenin and PRR is upregulated in the kidneys of diabetic rats. We examined the relationships among urine levels of renin (uRen), prorenin (uPro), soluble PRR (sPRR) and TGF-β (uTGF-β) in 93 subjects, including non-diabetes mellitus (Non-DM: n=64); and type-2 diabetes mellitus (DM; n=29) patients. Urine albumin (uAlb), creatinine (uCr) and pH were also assessed. DM patients showed higher uRen levels (DM: 81±21 vs Non-DM: 29±4.5 ng AngI/mL/hr; p<0.001), which were positively associated with uAlb/uCr (p<0.05, r=0.21) and inversely correlated with urine pH (p<0.01, r=-0.38). These values contrasted with uPro levels, which were no different between groups. DM patients showed increased uTGF-β compared to Non-DM (DM: 22±5.3 vs Non-DM: 5.6±1.5 pg/mg uCr; p<0.0001). Urine sPRR levels were positively correlated with urine pH (p<0.0001, r=0.56). No differences were observed in sPRR plasma and urine levels between non-DM and DM patients. However, the plasma levels of sPRR were 12.5 and 18.5-fold higher than in urine of Non-DM and DM, respectively. Treatment with RAS blockers increased sPRR in plasma (DM with RAS blockade: 24,455±2,151 vs DM without RAS blockade: 17,726±1,255 pg/mL, p<0.001) but not in urine. These data suggest that the cell membrane-bound PRR, not the soluble form, might be responsible for the increases in renin activity and TGF-β, as well as in the low pH in the urine of type-2 DM patients. It is likely that prorenin-mediated activation of membrane bound PRR promotes diabetic nephropathy by increasing urinary formation of TGF-β. [ABSTRACT FROM AUTHOR]

Tobacco smoking is associated with accelerated progression of chronic kidney disease of different etiologies including diabetes and hypertension. However, the mechanisms involved are not well understood. We have previously reported that nicotine, a biologically active compound present in high concentrations in tobacco, induces cell proliferation and fibronectin production in mesangial cells which are prevented by ERK1/2 inhibition (AJP’05). In these studies we determined whether rat mesangial cells (MC) express nicotine receptors and characterized the signaling pathways that lead to ERK1/2 phosphorylation in response to nicotine. MC were grown in DMEM with 15% FBS in the presence of 0.4 mg/ml G418 and starved for 24 hours in DMEM without FBS before treatment. We first demonstrated that MC are endowed with several nicotinic Ach receptor (nAChR) subunits including α2-7 and β1-4 as assessed by western blot. Treatment of rat MC with nicotine at 10-7M caused a time-dependent ERK1/2 phosphorylation which peaked after 10 min of stimulation( N=3). Several protein kinase inhibitors were then used to identify the upstream kinases that mediate nicotine-induced ERK1/2 phosphorylation. The calcium/calmodulin-dependent protein kinase II (CaMKII) inhibitor KN93 (10-7M) decreased the ERK1/2 phosphorylation level by ∼57% (0.41 of 0.95) as compared to nicotine. The PKC inhibitor Go6983 at 10-9M, the PKA inhibitor H89 (10-8 M) and the EGFR inhibitor AG 1478 (10-7 M) also inhibited ERK1/2 phosphorylation by 60% (0.38 of 0.95), 48% (0.63 of 1.20) and 68% (0.40 of 1.23) respectively as compared to nicotine. Given the role of the nicotine receptors as agonist-regulated Ca2+ channels, we determined the effects of Ca2+ channel blockade on nicotine induced ERK1/2 phosphorylation. Treatment of MC with the calcium channel Verapamil (10-9 M) resulted in 33% (0.49 of 0.73) inhibition of ERK1/2 phosphorylation as compared to nicotine. In summary, we have determined in these studies that rat MC are endowed with several nAChR subunits and that ERK1/2 phosphorylation in response to nicotine requires CaMK II, PKA, PKC and EGFR. In addition, we have demonstrated that these effects require Ca2+ consistent with the role of the nAChR as agonist-regulated Ca2+ channels in MC. [ABSTRACT FROM AUTHOR]

Increased generation of Angiotensin II (ANG II) plays a key role in the progression of chronic kidney disease (CKD). Cigarette smoking accelerates the progression of CKD of different etiologies including hypertension and diabetes. We have shown that nicotine (NIC), a biologically active compound present in large amounts in tobacco, worsens the severity of injury in experimental models of CKD. The aim of this study is to determine whether NIC and ANG II have synergistic effects on fibronectin production and proliferation in mesangial cells (MC). Rat MC were exposed to different concentrations of NIC (10-4 M to 10-10 M) and/or ANG II (10-6 M to 10-10 M) for 24 hours. Fibronectin production was measured by western blot and proliferation by EdU incorporation. As shown in Table 1, NIC and ANG II have synergistic effects on the production of fibronectin in MC.Shown in Table 2, NIC and ANG II have additive effects on MC proliferation.These synergistic effects of NIC and ANG II may explain the deleterious effects of smoking in conditions associated with increased activation of the renin angiotensin system. [ABSTRACT FROM AUTHOR]