Tweak/Fn14 system is involved in rhabdomyolysis-induced acute kidney injury.

BACKGROUND: Rhabdomyolysis is a severe clinical syndrome associated to acute kidney injury (AKI) and chronic kidney disease (CKD). TWEAK/Fn14 signaling axis regulates renal inflammation and tubular cell death. However, the functional role of TWEAK/Fn14 in rhabdomyolysis remains unknown. METHODS: Rhabdomyolysis was induced in wild-type, TWEAK- and Fn14-deficient mice or mice treated with TWEAK blocking antibody. Renal injury, inflammation, fibrosis and cell death were assessed. Additionally, we performed in vivo and in vitro studies to explore the possible signalling pathways involved in Fn14 regulation. FINDINGS: Fn14 renal expression was increased in mice with rhabdomyolysis, correlating with decline of renal function. Mechanistically, myoglobin (Mb) induced Fn14 expression via ERK and p38 pathway, whereas Nrf2 activation diminished Mb-mediated Fn14 upregulation in cultured renal cells. TWEAK or Fn14 genetic depletion ameliorated rhabdomyolysis-associated loss of renal function, histological damage, tubular cell death, inflammation, and expression of both tubular and endothelial injury markers. Deficiency of TWEAK or Fn14 also decreased long-term renal inflammation and fibrosis in mice with rhabdomyolysis. Finally, pharmacological treatment with a blocking TWEAK antibody diminished the expression of acute renal injury markers and cell death and lessened residual kidney fibrosis and chronic inflammation in rhabdomyolysis. INTERPRETATION: TWEAK/Fn14 axis participates in the pathogenesis of rhabdomyolysis-AKI and subsequent AKI-CKD transition. Blockade of this signaling pathway may represent a promising therapeutic strategy for reducing rhabdomyolysis-mediated renal injury. FUNDING: Spanish Ministry of Science and Innovation, ISCIII and Junta de Andalucía.

Malondialdehyde-modified HDL particles elicit a specific IgG response in abdominal aortic aneurysm.

High Density Lipoprotein (HDL) plays a protective role in abdominal aortic aneurysm (AAA); however, recent findings suggest that oxidative modifications could lead to dysfunctional HDL in AAA. This study aimed at testing the effect of oxidized HDL on aortic lesions and humoral immune responses in a mouse model of AAA induced by elastase, and evaluating whether antibodies against modified HDL can be found in AAA patients. HDL particles were oxidized with malondialdehyde (HDL-MDA) and the changes were studied by biochemical and proteomics approaches. Experimental AAA was induced in mice by elastase perfusion and then mice were treated with HDL-MDA, HDL or vehicle for 14 days. Aortic lesions were studied by histomorphometric analysis. Levels of anti-HDL-MDA IgG antibodies were measured by an in-house immunoassay in the mouse model, in human tissue-supernatants and in plasma samples from the VIVA cohort. HDL oxidation with MDA was confirmed by enhanced susceptibility to diene formation. Proteomics demonstrated the presence of MDA adducts on Lysine residues of HDL proteins, mainly ApoA-I. MDA-modification of HDL abrogated the protective effect of HDL on cultured endothelial cells as well as on AAA dilation in mice. Exposure to HDL-MDA elicited an anti-HDL-MDA IgG response in mice. Anti-HDL-MDA were also detected in tissue-conditioned media from AAA patients, mainly in intraluminal thrombus. Higher plasma levels of anti-HDL-MDA IgG antibodies were found in AAA patients compared to controls. Anti-HDL-MDA levels were associated with smoking and were independent predictors of overall mortality in AAA patients. Overall, MDA-oxidized HDL trigger a specific humoral immune response in mice. Besides, antibodies against HDL-MDA can be detected in tissue and plasma of AAA patients, suggesting its potential use as surrogate stable biomarkers of oxidative stress in AAA.

Fcγ receptor activation mediates vascular inflammation and abdominal aortic aneurysm development.

BACKGROUND: Abdominal aortic aneurysm (AAA), a degenerative vascular pathology characterized by permanent dilation of the aorta, is considered a chronic inflammatory disease involving innate/adaptive immunity. However, the functional role of antibody-dependent immune response against antigens present in the damaged vessel remains unresolved. We hypothesized that engagement of immunoglobulin G (IgG) Fc receptors (FcγR) by immune complexes (IC) in the aortic wall contributes to AAA development. We therefore evaluated FcγR expression in AAA lesions and analysed whether inhibition of FcγR signaling molecules (γ-chain and Syk kinase) influences AAA formation in mice. METHODS: FcγR gene/protein expression was assessed in human and mouse AAA tissues. Experimental AAA was induced by aortic elastase perfusion in wild-type (WT) mice and γ-chain knockout (γKO) mice (devoid of activating FcγR) in combination with macrophage adoptive transfer or Syk inhibitor treatment. To verify the mechanisms of FcγR in vitro, vascular smooth muscle cells (VSMC) and macrophages were stimulated with IgG IC. RESULTS: FcγR overexpression was detected in adventitia and media layers of human and mouse AAA. Elastase-perfused γKO mice exhibited a decrease in AAA incidence, aortic dilation, elastin degradation, and VSMC loss. This was associated with (1) reduced infiltrating leukocytes and immune deposits in AAA lesions, (2) inflammatory genes and metalloproteinases downregulation, (3) redox balance restoration, and (4) converse phenotype of anti-inflammatory macrophage M2 and contractile VSMC. Adoptive transfer of FcγR-expressing macrophages aggravated aneurysm in γKO mice. In vitro, FcγR deficiency attenuated inflammatory gene expression, oxidative stress, and phenotypic switch triggered by IC. Additionally, Syk inhibition prevented IC-mediated cell responses, reduced inflammation, and mitigated AAA formation. CONCLUSION: Our findings provide insight into the role and mechanisms mediating IgG-FcγR-associated inflammation and aortic wall injury in AAA, which might represent therapeutic targets against AAA disease.

Macrophage Cholesterol Efflux Downregulation Is Not Associated with Abdominal Aortic Aneurysm (AAA) Progression.

Recent studies have raised the possibility of a role for lipoproteins, including high-density lipoprotein cholesterol (HDLc), in abdominal aortic aneurysm (AAA). The study was conducted in plasmas from 39 large size AAA patients (aortic diameter > 50 mm), 81 small/medium size AAA patients (aortic diameter between 30 and 50 mm) and 38 control subjects (aortic diameter < 30 mm). We evaluated the potential of HDL-mediated macrophage cholesterol efflux (MCE) to predict AAA growth and/or the need for surgery. MCE was impaired in the large aortic diameter AAA group as compared with that in the small/medium size AAA group and the control group. However, no significant difference in HDL-mediated MCE capacity was observed in 3 different progression subgroups (classified according to growth rate < 1 mm per year, between 1 and 5 mm per year or >5 mm per year) in patients with small/medium size AAA. Moreover, no correlation was found between MCE capacity and the aneurysm growth rate. A multivariate Cox regression analysis revealed a significant association between lower MCE capacity with the need for surgery in all AAA patients. Nevertheless, the significance was lost when only small/medium size AAA patients were included. Our results suggest that MCE, a major HDL functional activity, is not involved in AAA progression.

The TNF-like weak inducer of the apoptosis/fibroblast growth factor-inducible molecule 14 axis mediates histamine and platelet-activating factor-induced subcutaneous vascular leakage and anaphylactic shock.

BACKGROUND: Anaphylaxis includes mast cell (MC) activation, but less is known about downstream mechanisms (ie, vascular permeability controlled by endothelial cells [ECs]). The TNF-like weak inducer of apoptosis (TWEAK) and its sole receptor, fibroblast growth factor-inducible molecule 14 (Fn14), belong to the TNF superfamily and are involved in proinflammatory responses. OBJECTIVE: We sought to investigate the role of TWEAK/Fn14 axis in anaphylaxis. METHODS: In vivo vascular permeability and mouse models of passive systemic anaphylaxis (PSA) and active systemic anaphylaxis were applied to wild-type (WT), TWEAK- and Fn14-deficient mice (TWEAK-/- and Fn14-/-, respectively). Primary bone marrow-derived mast cells (BMMCs) and ECs from WT and Fn14-/- or TWEAK-/- mice were studied. The TWEAK/Fn14 axis was also investigated in human samples. RESULTS: Mice with PSA and active systemic anaphylaxis had increased Fn14 and TWEAK expression in lung tissues and increased serum soluble TWEAK concentrations. TWEAK and Fn14 deficiencies prevent PSA-related symptoms, resulting in resistance to decreased body temperature, less severe reactions, and maintained physical activity. Numbers of MCs after PSA are similar between genotypes in different tissue regions, such as ear skin and the trachea, tongue, peritoneum, lungs, and bone marrow. Moreover, in vitro studies revealed no differences in degranulation or mediator release between WT and Fn14-/- BMMCs after IgE-FcεRI stimulation. In vivo and in vitro histamine and platelet-activating factor administration increases Fn14 receptor expression in lungs and ECs. Moreover, Fn14 deficiency in ECs maintained in vitro impermeability when stimulated by mediators or activated BMMCs but not by TWEAK-/- BMMCs, indicating that Fn14 is crucial for endothelial barrier function. TWEAK/Fn14 deletion or TWEAK-blocking antibody prevented histamine/platelet-activating factor-induced vascular subcutaneous permeability. Circulating soluble TWEAK levels were increased in patients with anaphylaxis, and plasma from those patients increased Fn14 expression in ECs. CONCLUSION: The TWEAK/Fn14 axis participates in anaphylactic reactions. Inhibition of TWEAK/Fn14 interaction could be efficacious in anaphylaxis therapy.

Impaired HDL (High-Density Lipoprotein)-Mediated Macrophage Cholesterol Efflux in Patients With Abdominal Aortic Aneurysm-Brief Report.

Objective- The ability of HDL (high-density lipoprotein) to promote macrophage cholesterol efflux is considered the main HDL cardioprotective function. Abdominal aortic aneurysm (AAA) is usually characterized by cholesterol accumulation and macrophage infiltration in the aortic wall. Here, we aim to evaluate the composition of circulating HDL particles and their potential for promoting macrophage cholesterol efflux in AAA subjects. Approach and Results- First, we randomly selected AAA and control subjects from Spain. The AAA patients in the Spanish cohort showed lower plasma apoA-I levels concomitantly associated with low levels of plasma HDL cholesterol and the amount of preß-HDL particles. We determined macrophage cholesterol efflux to apoB-depleted plasma, which contains mature HDL, preß-HDL particles and HDL regulatory proteins. ApoB-depleted plasma from AAA patients displayed an impaired ability to promote macrophage cholesterol efflux. Next, we replicated the experiments with AAA and control subjects derived from Danish cohort. Danish AAA patients also showed lower apoA-I levels and a defective HDL-mediated macrophage cholesterol efflux. Conclusions- AAA patients show impaired HDL-facilitated cholesterol removal from macrophages, which could be mechanistically linked to AAA.

Increased galectin-3 levels are associated with abdominal aortic aneurysm progression and inhibition of galectin-3 decreases elastase-induced AAA development.

Abdominal aortic aneurysm (AAA) evolution is unpredictable and no specific treatment exists for AAA, except surgery to prevent aortic rupture. Galectin-3 has been previously associated with CVD, but its potential role in AAA has not been addressed. Galectin-3 levels were increased in the plasma of AAA patients (n=225) compared with the control group (n=100). In addition, galectin-3 concentrations were associated with the need for surgical repair, independently of potential confounding factors. Galectin-3 mRNA and protein expression were increased in human AAA samples compared with healthy aortas. Experimental AAA in mice was induced via aortic elastase perfusion. Mice were treated intravenously with the galectin-3 inhibitor modified citrus pectin (MCP, 10 mg/kg, every other day) or saline. Similar to humans, galectin-3 serum and aortic mRNA levels were also increased in elastase-induced AAA mice compared with control mice. Mice treated with MCP showed decreased aortic dilation, as well as elastin degradation, vascular smooth muscle cell (VSMC) loss, and macrophage content at day 14 postelastase perfusion compared with control mice. The underlying mechanism(s) of the protective effect of MCP was associated with a decrease in galectin-3 and cytokine (mainly CCL5) mRNA and protein expression. Interestingly, galectin-3 induced CCL5 expression by a mechanism involving STAT3 activation in VSMC. Accordingly, MCP treatment decreased STAT3 phosphorylation in elastase-induced AAA. In conclusion, increased galectin-3 levels are associated with AAA progression, while galectin-3 inhibition decreased experimental AAA development. Our data suggest the potential role of galectin-3 as a therapeutic target in AAA.

Paraoxonase-1 overexpression prevents experimental abdominal aortic aneurysm progression.

Abdominal aortic aneurysm (AAA) is a permanent dilation of the aorta due to excessive proteolytic, oxidative and inflammatory injury of the aortic wall. We aimed to identify novel mediators involved in AAA pathophysiology, which could lead to novel therapeutic approaches. For that purpose, plasma from four AAA patients and four controls were analysed by a label-free proteomic approach. Among identified proteins, paraoxonase-1 (PON1) was decreased in plasma of AAA patients compared with controls, which was further validated in a bigger cohort of samples by ELISA. The phenylesterase enzymatic activity of PON1 was also decreased in serum of AAA patients compared with controls. To address the potential role of PON1 as a mediator of AAA, experimental AAA was induced by aortic elastase perfusion in wild-type (WT) mice and human transgenic PON1 (HuTgPON1) mice. Similar to humans, PON1 activity was also decreased in serum of elastase-induced AAA mice compared with healthy mice. Interestingly, overexpression of PON1 was accompanied by smaller aortic dilation and higher elastin and vascular smooth muscle cell (VSMC) content in the AAA of HuTgPON1 compared with WT mice. Moreover, HuTgPON1 mice display decreased oxidative stress and apoptosis, as well as macrophage infiltration and monocyte chemoattractant protein-1 (MCP1) expression, in elastase-induced AAA. In conclusion, decreased circulating PON1 activity is associated with human and experimental AAA. PON1 overexpression in mice protects against AAA progression by reducing oxidative stress, apoptosis and inflammation, suggesting that strategies aimed at increasing PON1 activity could prevent AAA.

Targeted gold-coated iron oxide nanoparticles for CD163 detection in atherosclerosis by MRI.

CD163 is a membrane receptor expressed by macrophage lineage. Studies performed in atherosclerosis have shown that CD163 expression is increased at inflammatory sites, pointing at the presence of intraplaque hemorrhagic sites or asymptomatic plaques. Hence, imaging of CD163 expressing macrophages is an interesting strategy in order to detect atherosclerotic plaques. We have prepared a targeted probe based on gold-coated iron oxide nanoparticles vectorized with an anti-CD163 antibody for the specific detection of CD163 by MRI. Firstly, the specificity of the targeted probe was validated in vitro by incubation of the probe with CD163(+) or (-) macrophages. The probe was able to selectively detect CD163(+) macrophages both in human and murine cells. Subsequently, the targeted probe was injected in 16 weeks old apoE deficient mice developing atherosclerotic lesions and the pararenal abdominal aorta was imaged by MRI. The accumulation of probe in the site of interest increased over time and the signal intensity decreased significantly 48 hours after the injection. Hence, we have developed a highly sensitive targeted probe capable of detecting CD163-expressing macrophages that could provide useful information about the state of the atheromatous lesions.

Hemoglobin induces monocyte recruitment and CD163-macrophage polarization in abdominal aortic aneurysm.

BACKGROUND: Increased hemoglobin (Hb) accumulation was reported in abdominal aortic aneurysms (AAAs). CD163 is a macrophage receptor involved in tissue Hb clearance, however its role in AAA has not been reported. We investigated the role of Hb on monocyte recruitment and differentiation towards CD163 expressing macrophages ex vivo, in vitro and in human AAA. METHODS AND RESULTS: CD163 mRNA and protein expression was significantly higher in human AAA (n=7) vs. healthy wall (n=6). CD163 was predominantly found in adventitia of AAA, coinciding with areas rich in hemosiderin and adjacent to neoangiogenic microvessels. Dual CD14/CD163 expression was observed in recently infiltrated monocytes surrounding microvessels. A higher release of soluble CD163 was observed in the conditioned medium from AAA (AAA-CM, n=10), mainly in the adventitial layer. Similar to Hb, AAA-CM induced CD163-dependent monocyte chemotaxis, especially on circulating monocytes from AAA patients. Hb or AAA-CM promoted differentiation towards CD163(high)/HLA-DR(low)-expressing macrophages, with enhanced Hb uptake, increased anti-inflammatory IL-10 secretion and decreased pro-inflammatory IL-12p40 release. All these effects were partially suppressed when Hb was removed from AAA-CM. Separate analysis on circulating monocytes reported increased percentage of pre-infiltrating CD14(++)CD16(+) monocytes in patients with AAA (n=21), as compared to controls (n=14). A significant increase in CD163 expression in CD14(++)CD16(+) monocyte subpopulation was observed in AAA patients. CONCLUSIONS: The presence of Hb in the adventitial AAA-wall promotes the migration and differentiation of activated circulating monocytes in AAA patients, explaining the existence of a protective CD163-macrophage phenotype that could take up the Hb present in the AAA-wall, avoiding its injurious effects.

TWEAK/Fn14 interaction promotes oxidative stress through NADPH oxidase activation in macrophages.

AIM: The interaction between TNF-like weak inducer of apoptosis (TWEAK, Tnfsf12) and the receptor, fibroblast growth factor-inducible 14 (Fn14), regulates vascular damage through different mechanisms, including inflammation. Oxidative stress plays a major role in inflammation and the development of atherosclerosis, but the relationship between TWEAK and oxidative stress is, however, poorly understood. METHODS AND RESULTS: In this study, we found that TWEAK and Fn14 are co-localized with the NADPH subunits, p22phox and Nox2, in human advanced atherosclerotic plaques. Using primary human macrophages and a murine macrophage cell line, we demonstrate that TWEAK promotes ROS production and enhances NADPH oxidase activity. Hence, we show a direct involvement of the TWEAK-Fn14 axis in oxidative stress, as genetic silencing of Fn14 or Nox2 abrogates the TWEAK-induced ROS production. Furthermore, our results point at Rac1 as an upstream mediator of TWEAK during oxidative stress. Finally, using an in vivo murine model we confirmed the major role of TWEAK in oxidative stress, as genetic silencing of Tnfsf12 in an ApoE(-/-) background reduces the number of DHE and 8-hydroxydeoxyguanosine-positive macrophages by 50%. CONCLUSIONS: Our results suggest that TWEAK regulates vascular damage by stimulating ROS production in an Nox2-dependent manner. These new insights into the TWEAK/Fn14 axis underline their potential use as therapeutic targets in atherosclerosis.

Thioredoxin-1/peroxiredoxin-1 as sensors of oxidative stress mediated by NADPH oxidase activity in atherosclerosis.

To assess the potential association between TRX-1/PRX-1 and NADPH oxidase (Nox) activity in vivo and in vitro, TRX-1/PRX-1 levels were assessed by ELISA in 84 asymptomatic subjects with known phagocytic NADPH oxidase activity and carotid intima-media thickness (IMT). We found a positive correlation between TRX-1/PRX-1 and NADPH oxidase-dependent superoxide production (r=0.48 and 0.47; p<0.001 for both) and IMT (r=0.31 and 0.36; p<0.01 for both) adjusted by age and sex. Moreover, asymptomatic subjects with plaques have higher PRX-1 and TRX plasma levels (p<0.01 for both). These data were confirmed in a second study in which patients with carotid atherosclerosis showed higher PRX-1 and TRX plasma levels than healthy subjects (p<0.001 for both). In human atherosclerotic plaques, the NADPH oxidase subunit p22phox colocalized with TRX-1/PRX-1 in macrophages (immunohistochemistry). In monocytes and macrophages, phorbol 12-myristate 13-acetate (PMA) induced NADPH activation and TRX-1/PRX-1 release to the extracellular medium, with a concomitant decrease in their intracellular levels, which was reversed by the NADPH inhibitor apocynin (Western blot). In loss-of-function experiments, genetic silencing of the NADPH oxidase subunit Nox2 blocked PMA-induced intracellular TRX-1/PRX-1 downregulation in macrophages. Furthermore, the PMA-induced release of TRX-1/PRX-1 involves the modulation of their redox status and exosome-like vesicles. TRX-1/PRX-1 levels are associated with NADPH oxidase-activity in vivo and in vitro. These data could suggest a coordinated antioxidant response to oxidative stress in atherothrombosis.

ApoA-I/HDL-C levels are inversely associated with abdominal aortic aneurysm progression.

Abdominal aortic aneurysm (AAA) evolution is unpredictable, and there is no therapy except surgery for patients with an aortic size> 5 cm (large AAA). We aimed to identify new potential biomarkers that could facilitate prognosis and treatment of patients with AAA. A differential quantitative proteomic analysis of plasma proteins was performed in AAA patients at different stages of evolution [small AAA (aortic size=3-5 cm) vs large AAA] using iTRAQ labelling, high-throughput nano-LC-MS/MS and a novel multi-layered statistical model. Among the proteins identified, ApoA-I was decreased in patients with large AAA compared to those with small AAA. These results were validated by ELISA on plasma samples from small (n=90) and large AAA (n=26) patients (150± 3 vs 133± 5 mg/dl, respectively, p< 0.001). ApoA-I levels strongly correlated with HDL-Cholesterol (HDL-C) concentration (r=0.9, p< 0.001) and showed a negative correlation with aortic size (r=-0.4, p< 0.01) and thrombus volume (r=-0.3, p< 0.01), which remained significant after adjusting for traditional risk factors. In a prospective study, HDL-C independently predicted aneurysmal growth rate in multiple linear regression analysis (n=122, p=0.008) and was inversely associated with need for surgical repair (Adjusted hazard ratio: 0.18, 95 % confidence interval: 0.04-0.74, p=0.018). In a nation-wide Danish registry, we found lower mean HDL-C concentration in large AAA patients (n=6,560) compared with patients with aorto-iliac occlusive disease (n=23,496) (0.89± 2.99 vs 1.59± 5.74 mmol/l, p< 0.001). Finally, reduced mean aortic AAA diameter was observed in AngII-infused mice treated with ApoA-I mimetic peptide compared with saline-injected controls. In conclusion, ApoA-I/HDL-C systemic levels are negatively associated with AAA evolution. Therapies targeting HDL functionality could halt AAA formation.

Galectin-3, a biomarker linking oxidative stress and inflammation with the clinical outcomes of patients with atherothrombosis.

BACKGROUND: Galectin-3 (Gal-3) participates in different mechanisms involved in atherothrombosis, such as inflammation, proliferation, or macrophage chemotaxis. Thus, there have been committed intensive efforts to elucidate the function of Gal-3 in cardiovascular (CV) diseases. The role of Gal-3 as a circulating biomarker has been demonstrated in patients with heart failure, but its importance as a biomarker in atherothrombosis is still unknown. METHODS AND RESULTS: Because Gal-3 is involved in monocyte-to-macrophage transition, we used fresh isolated monocytes and the in vitro model of macrophage differentiation of THP-1 cells stimulated with phorbol myristate acetate (PMA). Gal-3 release is increased by PMA in human monocytes and macrophages, a process involving exosomes and regulated by reactive oxygen species/NADPH oxidase activity. In asymptomatic subjects (n=199), Gal-3 plasma levels are correlated with NADPH oxidase activity in peripheral blood mononuclear cells (r=0.476; P<0.001) and carotid intima-media thickness (r=0.438; P<0.001), a surrogate marker of atherosclerosis. Accordingly, Gal-3 plasma concentrations are increased in patients with carotid atherosclerosis (n=158), compared to control subjects (n=115; 14.3 [10.7 to 16.9] vs. 10.4 [8.6 to 12.5] ng/mL; P<0.001). Finally, on a 5-year follow-up study in patients with peripheral artery disease, Gal-3 concentrations are significantly and independently associated with an increased risk for CV mortality (hazard ratio=2.24, 95% confidence interval: 1.06 to 4.73, P<0.05). CONCLUSIONS: Gal-3 extracellular levels could reflect key underlying mechanisms involved in atherosclerosis etiology, development, and plaque rupture, such as inflammation, infiltration of circulating cells and oxidative stress. Moreover, circulating Gal-3 concentrations are associated with clinical outcomes in patients with atherothrombosis.

Phase IV prospective clinical study to evaluate the effect of taurine on liver function in postsurgical adult patients requiring parenteral nutrition.

BACKGROUND: Taurine's role in bile acid metabolism and anti-inflammatory activity could exert a protective effect on hepatobiliary complications associated with parenteral nutrition (PN). In this study, the effects of 2 amino acid solutions, with and without taurine, on liver function administered to nonacutely ill postsurgical patients as part of a short-term PN regimen were prospectively compared. METHODS: Adult patients randomly received (double-blind) Tauramin 10% or a standard PN solution without taurine as the control (1.5 g amino acid/kg body weight [bw]/d; infusion rate of ≤4 mg glucose/kg bw/d) for a period of 5-30 days. γ-Glutamyl transpeptidase (GGT) and other indicators of liver function, glucose metabolism, lipid profile, inflammation markers, and treatment safety data were collected. RESULTS: Thirty-five patients receiving taurine PN and 39 receiving control PN were enrolled (intention-to-treat [ITT] population). Most patients (n = 62) discontinued after day 7 of follow-up (per-protocol [PP] population: n = 24 and n = 27, respectively). ITT patients with high GGT values after 5 days of PN comprised 68.6% and 64.1%, respectively. The mean change in GGT values with respect to the baseline values was 167 ± 192 and 157 ± 185 IU/L, respectively. Low-density lipoprotein (LDL) cholesterol levels after 7 days of PN were significantly decreased in the taurine PN group of PP patients (-2.83 ± 30.9 vs 23.9 ± 27.0 mg/dL for control PN; P < .05). None of the adverse events reported (taurine PN: n = 6; control PN: n = 7) were treatment related. CONCLUSION: PN solutions with and without taurine had similar effects on liver function parameters, except for an LDL reduction in PN with taurine, when administered to nonacutely ill postsurgical patients in the short term (5-7 days).

TWEAK promotes peritoneal inflammation.

Peritoneal dialysis (PD) is complicated by peritonitis episodes that cause loss of mesothelium and eventually sclerosing peritonitis. An improved understanding of the molecular contributors to peritoneal injury and defense may increase the therapeutic armamentarium to optimize peritoneal defenses while minimizing peritoneal injury. There is no information on the expression and function of the cytokine TWEAK and its receptor Fn14 during peritoneal injury. Fn14 expression and soluble TWEAK levels were measured in human PD peritoneal effluent cells or fluids with or without peritonitis. Fn14 expression was also analyzed in peritoneal biopsies from PD patients. Actions of intraperitoneal TWEAK were studied in mice in vivo. sTWEAK levels were increased in peritoneal effluent in PD peritonitis. Effluent sTWEAK levels correlated with the number of peritoneal macrophages (r=0.491, p=0.002). Potential TWEAK targets that express the receptor Fn14 include mesothelial cells and macrophages, as demonstrated by flow cytometry of peritoneal effluents and by analysis of peritoneal biopsies. Peritoneal biopsy Fn14 correlated with mesothelial injury, fibrosis and inflammation, suggesting a potential deleterious effect of TWEAK/Fn14. In this regard, intraperitoneal TWEAK administration to mice promoted peritoneal inflammation characterized by increased peritoneal effluent MCP-1, Fn14 and Gr1+ macrophages, increased mesothelial Fn14, MCP-1 and CCL21 expression and submesothelial tissue macrophage recruitment. Taken together these data suggest that the TWEAK/Fn14 system may promote inflammation and tissue injury during peritonitis and PD.

Oxidative stress, macrophage infiltration and CD163 expression are determinants of long-term renal outcome in macrohematuria-induced acute kidney injury of IgA nephropathy.

BACKGROUND: Macroscopic hematuria (MH) may cause acute kidney injury (AKI) in IgA nephropathy. Up to 25% of patients with MH-associated AKI do not recover baseline renal function. Our objective was to identify subjects at high risk for an adverse renal function. METHODS: We examined macrophages, oxidative stress markers (NADPH-p22 and HO-1) and the hemoglobin scavenger receptor (CD163) in renal biopsy specimens from 33 MH-AKI patients with complete recovery (CR, n = 17) or incomplete recovery (IR, n = 16) of renal function after 6.72 (range 0.5-21.5) years of follow-up. RESULTS: CD163-expressing macrophages, HO-1 and NADPH-p22 expression were located in areas surrounding tubules with iron deposits and filled with erythrocyte casts. CD163-positive macrophages score and HO-1- and p22-positive staining correlated positively with percentage of tubules with erythrocyte casts and tubular necrosis. Macrophage infiltration, CD163-positive macrophage score, NADPH-p22- and HO-1-positive staining areas were significantly greater in IR patients when compared with CR patients. The CD163-positive macrophage score and oxidative stress markers (p22 and HO-1) were negatively correlated with renal function outcome, as determined by estimated glomerular filtration rate (eGFR) and proteinuria, at the end of the follow-up period. In multivariate analysis, the CD163-positive macrophage score remained significantly associated with final eGFR and proteinuria after adjustment by age, gender, duration of MH, initial eGFR and proteinuria. CONCLUSIONS: Increased macrophage infiltration, CD163 expression and oxidative stress are significant prognostic factors for an IR of renal function in patients with MH-associated AKI. These molecular pathways may be involved in the renal response to injury and could be useful to improve diagnosis and therapeutics.

HSP90 inhibition by 17-DMAG attenuates oxidative stress in experimental atherosclerosis.

AIMS: Reactive oxygen species (ROS) participate in atherogenesis through different mechanisms including oxidative stress and inflammation. Proteins implicated in both processes, such as mitogen-activated protein kinase kinase (MEK) and some NADPH oxidase (NOX) subunits, are heat shock protein-90 (HSP90) client proteins. In this work, we investigated the antioxidant properties of the HSP90 inhibitor, 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG) in experimental atherosclerosis. METHODS AND RESULTS: Treatment of ApoE(-/-) mice with 17-DMAG (2 mg/kg every 2 days for 10 weeks) decreased ROS levels and extracellular signal-regulated kinase (ERK) activation in aortic plaques compared with control animals. Accordingly, treatment of rat vascular smooth muscle cells (VSMCs) with 17-DMAG increased HSP27 and HSP70 and inhibited ERK activation. Interestingly, 17-DMAG diminished NADPH oxidase dependent ROS production in VSMCs and monocytes. In addition, a marked reduction in NADPH oxidase dependent ROS production was observed with HSP90siRNA and the opposite pattern with HSP70siRNA. 17-DMAG also diminished the expression of Nox1 and Nox organizer-1 (Noxo1) in VSMCs and monocytes. Interestingly, 17-DMAG was able to modulate ROS-induced monocyte to macrophage differentiation. Finally, higher expression of Nox1 and Noxo1 was found in the inflammatory region of human atherosclerotic plaques, colocalizing with VSMCs, macrophages, and ROS-producing cells. CONCLUSION: Our results suggest that HSP90 inhibitors interfere with oxidative stress and modulate experimental atherosclerosis development through reduction in pro-oxidative factors.

Increased plasma levels of NGAL, a marker of neutrophil activation, in patients with abdominal aortic aneurysm.

OBJECTIVE: Neutrophil gelatinase-associated lipocalin (NGAL) plasma concentrations have been associated with cardiovascular diseases. We aimed to assess the association of NGAL with abdominal aortic aneurysm (AAA). METHODS: NGAL concentrations were analyzed by Western blotting in conditioned medium of polymorphonuclear neutrophils (PMNs) from AAA patients (n=22) and controls (n=11), and also in aortic biopsies from AAA patients and healthy controls (n=10). Plasma NGAL concentrations were measured by ELISA in three groups of subjects from France (n=60), Spain (n=75) and Australia (n=100) and associated with AAA presence and growth. RESULTS: PMNs isolated from AAA patients secreted significantly greater amounts of NGAL than PMNs from controls. Luminal thrombus released large amounts of NGAL compared to abluminal AAA thrombus, AAA wall and healthy aortic media. Plasma NGAL concentrations were significantly higher in patients with AAA than controls from France [115 (78-200) vs. 94 (72-114) ng/ml, p<0.001]. NGAL plasma concentrations in AAA patients from Spain correlated with other markers of thrombus activity (plasmin-antiplasmin complexes and D-dimer). Furthermore, a positive correlation between plasma NGAL and retrospective AAA growth (rho=0.4, p=0.01) was observed, which remained significant after adjusting for other risk factors. Plasma NGAL was only weakly associated with prospective growth in both Spanish and Australian patients. CONCLUSIONS: NGAL is released by PMNs and by the luminal part of AAA thrombus. NGAL plasma levels were increased in AAA patients compared with healthy subjects and correlated with retrospective AAA growth. Further studies in larger subjects groups are needed to confirm the association between NGAL and AAA presence and growth.