Clusterin protects against oxidative stress in vitro through aggregative and nonaggregative properties

Clusterin protects against oxidative stress in vitro through aggregative and nonaggregative properties. Perturbations of cell interactions, an early event in acute renal injury, have important pathophysiologic consequences. We hypothesized that promotion of cell interactions protects cells from injury. To test this hypothesis, a single cell suspension of LLC-PK1 cells (porcine proximal tubular cell line) treated with albumin (control) was compared to cells aggregated with fibrinogen or purified human clusterin (aggregation graded 0 to 4). Following aggregation, the cells were injured with 1.5 mM hydrogen peroxide (H2O2) for three hours. Cell aggregation induced by clusterin but not fibrinogen protected against oxidant injury by H2O2. Complete abrogation of cytotoxicity occurred at a clusterin concentration of 2.5 μg/ml, which resulted in an aggregation score of 1. In the absence of aggregation, clusterin at concentrations of 20 and 50 μg/ml, but not lower doses, partially protected against injury induced by H2O2. Cell aggregation induced by both clusterin and fibrinogen partially protected against endogenously generated oxidant stress induced by incubating LLC-PK1 cells with aminotriazole and 1-chloro-2,4-dinitrobenzene (CDNB). In conclusion, clusterin protects against models of oxidant stress in vitro, whether generated by exogenously administered hydrogen peroxide, or from endogenously produced peroxide, and such protective effects can accrue from aggregative and nonaggregative properties of clusterin

Laparoscopic Sleeve Gastrectomy: Our First 100 Patients

Laparoscopic sleeve gastrectomy appears to be a safe, reproducible method to manage morbidly obese patients

Intracellular targets in heme protein-induced renal injury

Intracellular targets in heme protein-induced renal injury. We examined two potential intracellular targets in the glycerol model of acute renal failure, namely, the mitochondrion and the nucleus. Within three hours, alterations in mitochondrial function are already apparent. With either glutamate/malate or succinate/rotenone, state 3 and uncoupled respirations were decreased at three hours, and at 24 hours, such decrements were quite pronounced; in the presence of glutamate/malate, state 2 respiration was also depressed at 24 hours, while with succinate/rotenone state 2 was increased. Marked ultrastructural changes were observed in mitochondria studied at three hours, including the novel finding of degenerate mitochondria in autophagic vacuoles. Since the heme content in mitochondria was increased some tenfold within three hours, mitochondrial function was studied after exposure to concentrations of heme that reproduced such contents of heme: mitochondria initially displayed increased respiration, and subsequently, a persistent decline in oxygen consumption until oxygen consumption was virtually undetectable. With higher concentrations of heme, the early increase in oxygen consumption was blunted and the progressive decline in oxygen consumption was hastened. The antioxidant iron chelator, deferoxamine, prevented the early rise in oxygen consumption but did not prevent or delay the subsequent decline. We also assessed nuclear damage as a potential lesion in the glycerol model. DNA laddering was not observed at any time point. At 3 and 24 hours there was DNA injury by the TUNEL technique in the distal nephron but not in the proximal nephron. The 8-hydroxydeoxyguanosine/deoxyguanosine content was increased in the glycerol kidneys at 24 hours but not at three hours. At neither time point was evidence of apoptosis observed by light or electron microscopy. In studies undertaken in cell culture models, heme, at concentrations of 10 μM, failed to evince any such changes in LLC-PK1 cells, a cell line from the proximal tubule, or in MDCK cells, a cell line derived from the distal tubule. At concentrations of 50 μM, heme induced approximately 20% positivity in MDCK cells but none in LLC-PK1 cells by the TUNEL technique. We conclude that mitochondria and nuclei are prominent targets for injury in the glycerol model of acute renal failure. The presence of TUNEL-positive cells in the distal nephron but not at proximal sites in vivo underscores the increasing appreciation of the distinct responses of these nephron sites to nephrotoxic insults

The Modulatory Role of Heme Oxygenase on Subpressor Angiotensin II-Induced Hypertension and Renal Injury

Angiotensin II (AngII) causes hypertension (HTN) and promotes renal injury while simultaneously inducing reno-protective enzymes like heme oxygenase-1 (HO-1). We examined the modulatory role of HO on sub-pressor angiotensin II (SP-AngII) induced renal inflammation and injury. We first tested whether the SP-AngII-induced renal dysfunction, inflammation and injury are exacerbated by either preventing (chronic HO-1 inhibition) or reversing (late HO-1 inhibition) SP-AngII-induced HO (using tin protoporphyrin; SnPP). We next examined whether additional chronic or late induction of SP-AngII-induced HO (using cobalt protoporphyrin; CoPP), prevents or ameliorates renal damage. We found that neither chronic nor late SnPP altered blood pressure. Chronic SnPP worsened SP-AngII-induced renal dysfunction, inflammation, injury and fibrosis, whereas late SnPP worsened renal dysfunction but not inflammation. Chronic CoPP prevented HTN, renal dysfunction, inflammation and fibrosis, but surprisingly, not the NGAL levels (renal injury marker). Late CoPP did not significantly alter SP-AngII-induced HTN, renal inflammation or injury, but improved renal function. Thus, we conclude (a) endogenous HO may be an essential determining factor in SP-AngII induced renal inflammation, injury and fibrosis, (b) part of HO's renoprotection may be independent of blood pressure changes; and (c) further induction of HO-1 protects against renal injury, suggesting a possible therapeutic target

H-ferritin ferroxidase induces cytoprotective pathways and inhibits microvascular stasis in transgenic sickle mice

Hemolysis, oxidative stress, inflammation, vaso-occlusion and organ infarction are hallmarks of sickle cell disease (SCD). We have previously shown that increases in heme oxygenase-1 (HO-1) activity detoxify heme and inhibit vaso-occlusion in transgenic mouse models of SCD. HO-1 releases Fe2+ from heme, and the ferritin heavy chain (FHC) ferroxidase oxidizes iron to catalytically-inactive Fe3+ inside ferritin. FHC overexpression has been shown to be cytoprotective. In this study, we hypothesized that overexpression of FHC and its ferroxidase activity will inhibit inflammation and microvascular stasis in transgenic sickle mice in response to stroma-free hemoglobin. We utilized a Sleeping Beauty transposase plasmid to deliver a human wild-type-ferritin heavy chain (wt-hFHC) transposable element by hydrodynamic tail vein injections to NY1DD SCD mice. Control mice were infused with the same volume of lactated Ringer's solution (LRS) or a triple missense human FHC (ms-hFHC) plasmid with no ferroxidase activity. Eight weeks later, LRS-injected mice had ~40% microvascular stasis (% non-flowing venules) when infused with stroma-free hemoglobin at 1 h, while mice overexpressing wt-hFHC had only 5% stasis (p< 0.05), and ms-hFHC mice had 33% stasis suggesting vascular protection by ferroxidase active wt-hFHC. The wt-hFHC SCD mice had marked increases in splenic hFHC mRNA and hepatic hFHC protein, light chain ferritin, 5-aminolevulinic acid synthase (5-ALA-synthase), heme content, ferroportin, nuclear factor erythroid 2-related factor 2 (Nrf2), nuclear hFHC, and microsomal HO-1 activity and protein, and a decrease in activated nuclear phosho-nuclear factor-kappa B (NF-κB) p65. HO-1 activity was not essential for the protection by FHC. We conclude that wt-hFHC ferroxidase activity enhances cytoprotective Nrf2-regulated proteins including HO-1, thereby resulting in decreased NF-κB-activation, inflammation and microvascular stasis in transgenic SCD mice

Cyclophilins A and B oppositely regulate renal tubular epithelial cell phenotype

Altres ajuts: E.S. and M.D. were supported by the generous contribution of Asdent Patients Association. This work was supported in part by grants from Ministerio de Ciencia e Innovación, the Fundación Senefro (SEN2019 to A.M.), and Red de Investigación Renal REDinREN (12/0021/0013). K.A.N. is supported by National Institutes of Health (NIH) DK 47060. A.M. group holds the Quality Mention from the Generalitat de Catalunya.Restoration of kidney tubular epithelium following sublethal injury sequentially involves partial epithelial-mesenchymal transition (pEMT), proliferation, and further redifferentiation into specialized tubule epithelial cells (TECs). Because the immunosuppressant cyclosporine-A produces pEMT in TECs and inhibits the peptidyl-prolyl isomerase (PPIase) activity of cyclophilin (Cyp) proteins, we hypothesized that cyclophilins could regulate TEC phenotype. Here we demonstrate that in cultured TECs, CypA silencing triggers loss of epithelial features and enhances transforming growth factor β (TGF β)-induced EMT in association with upregulation of epithelial repressors Slug and Snail. This pro-epithelial action of CypA relies on its PPIase activity. By contrast, CypB emerges as an epithelial repressor, because CypB silencing promotes epithelial differentiation, prevents TGF β -induced EMT, and induces tubular structures in 3D cultures. In addition, in the kidneys of CypB knockout mice subjected to unilateral ureteral obstruction, inflammatory and pro-fibrotic events were attenuated. CypB silencing/knockout leads to Slug, but not Snail, downregulation. CypB support of Slug expression depends on its endoplasmic reticulum location, where it interacts with calreticulin, a calcium-buffering chaperone related to Slug expression. As CypB silencing reduces ionomycin-induced calcium release and Slug upregulation, we suggest that Slug expression may rely on CypB modulation of calreticulin-dependent calcium signaling. In conclusion, this work uncovers new roles for CypA and CypB in modulating TEC plasticity and identifies CypB as a druggable target potentially relevant in promoting kidney repair

A monocyte-TNF-endothelial activation axis in sickle transgenic mice: Therapeutic benefit from TNF blockade

Elaboration of tumor necrosis factor (TNF) is a very early event in development of ischemia/reperfusion injury pathophysiology. Therefore, TNF may be a prominent mediator of endothelial cell and vascular wall dysfunction in sickle cell anemia, a hypothesis we addressed using NY1DD, S+SAntilles, and SS‐BERK sickle transgenic mice. Transfusion experiments revealed participation of abnormally activated blood monocytes exerting an endothelial activating effect, dependent upon Egr‐1 in both vessel wall and blood cells, and upon NFκB(p50) in a blood cell only. Involvement of TNF was identified by beneficial impact from TNF blockers, etanercept and infliximab, with less benefit from an IL‐1 blocker, anakinra. In therapeutic studies, etanercept ameliorated multiple disturbances of the murine sickle condition: monocyte activation, blood biomarkers of inflammation, low platelet count and Hb, vascular stasis triggered by hypoxia/reoxygenation (but not if triggered by hemin infusion), tissue production of neuro‐inflammatory mediators, endothelial activation (monitored by tissue factor and VCAM‐1 expression), histopathologic liver injury, and three surrogate markers of pulmonary hypertension (perivascular inflammatory aggregates, arteriolar muscularization, and right ventricular mean systolic pressure). In aggregate, these studies identify a prominent—and possibly dominant—role for an abnormal monocyte‐TNF‐endothelial activation axis in the sickle context. Its presence, plus the many benefits of etanercept observed here, argue that pilot testing of TNF blockade should be considered for human sickle cell anemia, a challenging but achievable translational research goal

Octet magnetic moments and the Coleman-Glashow sum rule violation in the chiral quark model

Baryon octet magnetic moments when calculated within the chiral quark model, incorporating the orbital angular momentum as well as the quark sea contribution through the Cheng-Li mechanism, not only show improvement over the non relativistic quark model results but also gives a non zero value for the right hand side of Coleman-Glashow sum rule. When effects due to spin-spin forces between constituent quarks as well as `mass adjustments' due to confinement are added, it leads to an excellent fit for the case of p, \Sigma^+, \Xi^o and violation of Coleman-Glashow sum rule, whereas in almost all the other cases the results are within 5% of the data.Comment: 5 RevTeX pages, accepted for publication in PRD(Rapid Communication