Citations

Objective— Endothelial outgrowth cells (EOC) decrease inflammation and improve endothelial repair. Inflammation aggravates kidney injury in renal artery stenosis (RAS), and may account for its persistence upon revascularization. We hypothesized that EOC would decrease inflammatory (M1) macrophages and improve renal recovery in RAS. Approach and Results— Pigs with 10 weeks of RAS were studied 4 weeks after percutaneous transluminal renal angioplasty (PTRA+stenting) or sham, with or without adjunct intrarenal delivery of autologous EOC (10×10 6 ), and compared with similarly treated normal controls (n=7 each). Single-kidney function, microvascular and tissue remodeling, inflammation, oxidative stress, and fibrosis were evaluated. Four weeks after PTRA, EOC were engrafted in injected RAS-kidneys. Stenotic-kidney glomerular filtration rate was restored in RAS+EOC, RAS+PTRA, and RAS+PTRA+EOC pigs, whereas stenotic-kidney blood flow and angiogenesis were improved and fibrosis attenuated only in EOC-treated pigs. Furthermore, EOC increased cell proliferation and decreased the ratio of M1 (inflammatory)/M2 (reparative) macrophages, as well as circulating levels and stenotic-kidney release of inflammatory cytokines. Cultured-EOC released microvesicles in vitro and induced phenotypic switch (M1-to-M2) in cultured monocytes, which was inhibited by vascular endothelial growth factor blockade. Finally, a single intrarenal injection of rh-vascular endothelial growth factor (0.05 μg/kg) in 7 additional RAS pigs also restored M1/M2 ratio 4 weeks later. Conclusions— Intrarenal infusion of EOC after PTRA induced a vascular endothelial growth factor–mediated attenuation in macrophages inflammatory phenotype, preserved microvascular architecture and function, and decreased inflammation and fibrosis in the stenotic kidney, suggesting a novel mechanism and therapeutic potential for adjunctive EOC delivery in experimental RAS to improve PTRA outcomes.

RAS is an oncogene frequently mutated in human cancer. RAS mutations have been reported in 10–15% of cases of acute myeloid leukemia (AML) but they appear to be less frequent among patients with myelodysplastic syndrome (MDS). The impact of RAS mutations in patients with MDS is unclear. We conducted a retrospective study in 1,067 patients with newly diagnosed MDS for whom RAS mutational analysis was available. Overall, 4% of patients carried mutant RAS alleles. Notably, FLT3 mutations, which were found in 2% of patients, were mutually exclusive with RAS mutations. Patients with RAS mutations had a higher white blood cell count as well as bone marrow blasts compared with patients carrying wild‐type RAS. However, no differences were observed between both groups regarding the risk of AML transformation (9% vs. 7%) and overall survival (395 days vs. 500 days, P = 0.057). In summary, RAS mutations are infrequent in patients with MDS and do not appear to negatively impact their outcome. Am. J. Hematol. 88:365–369, 2013. © 2013 Wiley Periodicals, Inc.

Background— The selection of patients with renal artery stenosis (RAS) likely to improve glomerular filtration rate (GFR) after percutaneous transluminal renal angioplasty is difficult. We examined basal hemodynamic and inflammatory factors linked to improved stenotic kidney (STK) function after percutaneous transluminal renal angioplasty in swine RAS. Methods and Results— Fifteen pigs after 6 weeks of hemodynamically significant RAS were studied before and 4 weeks after technically successful percutaneous transluminal renal angioplasty+stenting. STK and contralateral kidney hemodynamics and function were evaluated by multidetector computed-tomography before and after acetylcholine challenge. Single-kidney deoxyhemoglobin (R2*, reciprocal to blood relaxation) and energy-dependent tubular function were assessed using blood-oxygen-level–dependent magnetic resonance imaging before and after furosemide. Baseline renal vein and inferior vena cava levels of inflammatory markers were measured and their gradient and net release calculated. Baseline parameters were compared with normal (n=7) and sham-RAS (n=7) pigs and correlated with the change in STK-GFR after revascularization (ΔGFR). Four weeks after percutaneous transluminal, renal angioplasty blood pressure was normalized in all animals, but STK-GFR improved in 10 of 15 (ΔGFR =+22.0±8.5 mL/min). ΔGFR correlated inversely with basal STK-GFR, renal release of inflammatory markers, and medullary R2* response to furosemide, but directly with GFR response to acetylcholine. Basal contralateral kidney GFR correlated directly with ΔGFR. Conclusions— Low basal STK-GFR with preserved response to acetylcholine may predict benefit from revascularization in RAS, whereas renal inflammation and robust STK-R2* responses to furosemide (possibly reflecting avid tubular oxygen consumption) are associated with less favorable outcomes. These tools may be useful for identification of patients likely to improve renal function after revascularization.

Revascularization improves blood pressure but not renal function in most patients with atherosclerotic renal artery stenosis (ARAS), possibly related to injury incurred during renal reperfusion. Bendavia, a novel tetrapeptide that inhibits mitochondrial permeability transition pore opening, reduces apoptosis, oxidative stress, and ischemia-reperfusion injury in experimental models. However, its potential for improving renal response to revascularization of chronic ARAS is unknown. We hypothesized that adjunct Bendavia would improve renal structure and function after percutaneous transluminal renal angioplasty (PTRA). Pigs were treated after 6 weeks of ARAS or control with PTRA+stenting (or sham), adjunct continuous 4-hour infusion of Bendavia (0.05 mg/kg IV) or vehicle (n=7 each) during PTRA. Single-kidney renal blood flow and glomerular filtration rate were studied 4 weeks later and renal mitochondrial biogenesis, microvascular architecture, and injurious pathways evaluated ex vivo. Monocyte chemoattractant protein-1 levels rose after PTRA, suggesting inflammatory injury. Bendavia did not immediately affect inflammatory cytokine levels, yet 4 weeks later, stenotic kidney renal blood flow and glomerular filtration rate both improved (44.00 ± 0.21% and 36.40 ± 10.21%, respectively) in ARAS+PTRA+Bendavia compared with ARAS+PTRA+vehicle. Renal mitochondrial biogenesis was restored after PTRA+Bendavia, and microvascular rarefaction, apoptosis, oxidative stress, tubular injury, and fibrosis decreased. Infusion of Bendavia during PTRA preserved mitochondrial biogenesis, renal hemodynamics, and function, and attenuated tissue injury in swine ARAS. Thus, functional mitochondrial injury during renal reperfusion may sustain renal inflammatory injury and limit kidney recovery after PTRA. Potent antiapoptotic and antioxidant effects provide Bendavia a novel therapeutic potential for improving kidney outcomes after PTRA in experimental ARAS.

Renal artery stenosis (RAS) promotes microvascular rarefaction and fibrogenesis, which may eventuate in irreversible kidney injury. We have shown that percutaneous transluminal renal angioplasty (PTRA) or endothelial progenitor cells (EPC) improve renal cortical hemodynamics and function in the poststenotic kidney. The renal medulla is particularly sensitive to hypoxia, yet little is known about reversibility of medullary injury on restoration of renal blood flow. This study was designed to test the hypothesis that PTRA, with or without adjunct EPC delivery to the stenotic kidney, may improve medullary remodeling and tubular function. RAS was induced in 21 pigs using implantation of irritant coils, while another group served as normal controls ( n = 7 each). Two RAS groups were then treated 6 wk later with PTRA or both PTRA and EPC. Four weeks later, medullary hemodynamics, microvascular architecture, and oxygen-dependent tubular function of the stenotic kidneys were examined using multidetector computed tomography, microcomputed tomography, and blood oxygenation level-dependent MRI, respectively. Medullary protein expression of vascular endothelial growth factor, endothelial nitric oxide synthase, hypoxia-inducible factor-1α, and NAD(P)H oxidase p47 were determined. All RAS groups showed decreased medullary vascular density and blood flow. However, in RAS+PTRA+EPC animals, EPC were engrafted in tubular structures, oxygen-dependent tubular function was normalized, and fibrosis attenuated, despite elevated expression of hypoxia-inducible factor-1α and sustained downregulation of vascular endothelial growth factor. In conclusion, EPC delivery, in addition to PTRA, restores medullary oxygen-dependent tubular function, despite impaired medullary blood and oxygen supply. These results support further development of cell-based therapy as an adjunct to revascularization of RAS.

Percutaneous transluminal renal stenting (PTRS) does not consistently improve renal function in patients with atherosclerotic renovascular disease, but the mechanisms underlying irreversible kidney injury have not been fully elucidated. We hypothesized that renal dysfunction after PTRS is linked to ongoing renal microvascular (MV) remodeling. Pigs were studied after 10 wk of atherosclerosis and renal artery stenosis (ARAS), ARAS treated with PTRS 4 wk earlier, and normal controls ( n = 10 each). Renal blood flow (RBF) and glomerular filtration rate (GFR) were studied using multidetector computer tomography. Renal microvascular architecture (micro-CT), angiogenic activity, oxidative stress, and fibrosis were evaluated ex vivo. Four weeks after PTRS, blood pressure was normalized. However, GFR and RBF remained similarly decreased in untreated ARAS and ARAS+PTRS ( P < 0.05 vs. normal). MV rarefaction was unaltered after revascularization, and the spatial density of outer cortical microvessels correlated with residual GFR. Interstitial fibrosis and altered expression of proangiogenic and profibrotic factors persisted after PTRS. Tubulointerstitial injury in ARAS persisted 4 wk after mechanically successful PTRS, and vessel loss correlated with residual renal dysfunction. MV loss and fibrosis in swine ARAS might account for persistent renal dysfunction after PTRS and underscore the need to assess renal parenchymal disease before revascularization.

Abstract HSulf-1 modulates the sulfation states of heparan sulfate proteoglycans critical for heparin binding growth factor signaling. In the present study, we show that HSulf-1 is transcriptionally deregulated under hypoxia in breast cancer cell lines. Knockdown of HIF-1α rescued HSulf-1 downregulation imposed by hypoxia, both at the RNA and protein levels. Chromatin immunoprecipitation with HIF-1α and HIF-2α antibodies confirmed recruitment of HIF-α proteins to the two functional hypoxia-responsive elements on the native HSulf-1 promoter. HSulf-1 depletion in breast cancer cells resulted in an increased and sustained bFGF2 (basic fibroblast growth factor) signaling and promoted cell migration and invasion under hypoxic conditions. In addition, FGFR2 (fibroblast growth factor receptor 2) depletion in HSulf-1–silenced breast cancer cells attenuated hypoxia-mediated cell invasion. Immunohistochemical analysis of 53 invasive ductal carcinomas and their autologous metastatic lesions revealed an inverse correlation for the expression of HSulf-1 to CAIX in both the primary tumors (P ≥ 0.0198) and metastatic lesions (P ≥ 0.0067), respectively, by χ2 test. Finally, HSulf-1 expression levels in breast tumors by RNA in situ hybridization showed that high HSulf-1 expression is associated with increased disease-free and overall survival (P ≥ 0.03 and P ≥ 0.0001, respectively). Collectively, these results reveal an important link between loss of HSulf-1 under hypoxic microenvironment and increased growth factor signaling, cell migration, and invasion. Cancer Res; 71(6); 2152–61. ©2011 AACR.

Abstract Hamartin and tuberin are products of the tumor suppressor genes TSC1 and TSC2, respectively. Mutations affecting either gene result in the tuberous sclerosis syndrome, a neurologic genetic disorder characterized by the formation of multiple benign tumors or hamartomas. In this study, we report the identification of TSC2, but not TSC1, as a substrate of HtrA1, a member of the human HtrA family proteins of serine proteases. We show the direct interaction and colocalization in the cytoplasm of HtrA1 and TSC2 and that HtrA1 cleaves TSC2 both in vitro and in vivo. Finally, we show that alterations in HtrA1 expression cause modifications in phosphorylation status of two downstream targets of TSC2: 4E-BP1 and S6K. Our data suggest that, under particular physiologic or pathologic conditions, HtrA1 degrades TSC2 and activates the downstream targets. Considering that HtrA1 levels are significantly increased during embryogenesis, we speculate that one of the targets of HtrA1 activity during fetal development is the TSC2-TSC1 pathway. Mol Cancer Res; 8(9); 1248–60. ©2010 AACR.