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Introduction The glomerulus is the basic filtering unit of the kidney. Its sieving action is made possible by highly specialized cells, termed podocytes, that reside within it. Arising from the [...], Histone protein modifications control fate determination during normal development and dedifferentiation during disease. Here, we set out to determine the extent to which dynamic changes to histones affect the differentiated phenotype of ordinarily quiescent adult glomerular podocytes. To do this, we examined the consequences of shifting the balance of the repressive histone H3 lysine 27 trimethylation (H3K27me3) mark in podocytes. Adriamycin nephrotoxicity and subtotal nephrectomy (SNx) studies indicated that deletion of the histone methylating enzyme EZH2 from podocytes decreased H3K27me3 levels and sensitized mice to glomerular disease. H3K27me3 was enriched at the promoter region of the Notch ligand Jag1 in podocytes, and derepression of Jag1 by EZH2 inhibition or knockdown facilitated podocyte dedifferentiation. Conversely, inhibition of the Jumonji C domain-containing demethylases Jmjd3 and UTX increased the H3K27me3 content of podocytes and attenuated glomerular disease in adriamycin nephrotoxicity, SNx, and diabetes. Podocytes in glomeruli from humans with focal segmental glomerulosclerosis or diabetic nephropathy exhibited diminished H3K27me3 and heightened UTX content. Analogous to human disease, inhibition of Jmjd3 and UTX abated nephropathy progression in mice with established glomerular injury and reduced H3K27me3 levels. Together, these findings indicate that ostensibly stable chromatin modifications can be dynamically regulated in quiescent cells and that epigenetic reprogramming can improve outcomes in glomerular disease by repressing the reactivation of developmental pathways.

Introduction Epoxyeicosatrienoic acids (EETs) are cytochrome P450 (CYP) epoxygenase metabolites of arachidonic acid (AA); potent intracellular lipid signaling molecules that exist as 4 regioisomeric metabolites: 5,6-, 8,9-, 11,12-, and 14,15-EETs [...], Epoxyeicosatrienoic acids (EETs) are active metabolites of arachidonic acid that are inactivated by soluble epoxide hydrolase enzyme (sEH) to dihydroxyeicosatrienoic acid. EETs are known to render cardioprotection against ischemia reperfusion (IR) injury by maintaining mitochondrial function. We investigated the effect of a novel sEH inhibitor (sEHi) in limiting IR injury. Mouse hearts were perfused in Langendorff mode for 40 min and subjected to 20 min of global no-flow ischemia followed by 40 min of reperfusion. Hearts were perfused with 0.0, 0.1, 1.0 and 10.0 µmol-[L.sup.-1] of the sEHi N-(2chloro-4-methanesulfonyl-benzyl)-6-(2,2,2-trifluoro-ethoxy)-nicotinamide (BI00611953). Inhibition of sEH by BI00611953 significantly improved postischemic left-ventricular-developed pressure and reduced infarct size following IR compared with control hearts, and similar to hearts perfused with 11,12-EETs (1 µmol*[L.sup.-1]) and sE[H.sup.-/-] mice. Perfusion with the putative EET receptor antagonist 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EEZE, 10 µmol*[L.sup.-1),] or the plasma membrane [K.sub.ATP] channels (pm[K.sub.ATP)] inhibitor (glibenclamide, 10 µmol*[L.sup.-1)] abolished the improved recovery by BI00611953 (1 µmol*[L.sup.-1]). Mechanistic studies in H9c2 cells demonstrated that BI0611953 decreased ROS generation, caspase-3 activity, proteasome activity, increased HIF-1[varies] DNA binding, and delayed the loss of mitochondrial membrane potential (Δ[Ψ.sub.m]) caused by anoxia-reoxygenation. Together, our data demonstrate that the novel sEHi BI00611953, a nicotinamide-based compound, provides significant cardioprotection against ischemia reperfusion injury. Key words: epoxyeicosatrienoic acid, soluble epoxide hydrolase, ischemia-reperfusion, pm[K.sub.ATP] channels and sEH inhibitors. Les acides epoxyeicosatrienoiques (EET) sont des metabolites actifs de l'acide arachidonique qui sont inactives par l'epoxyde hydrolase soluble (sEH) en acide dihydroxyeicosatrienoi'que. Les EET sont connus pour conferer une cardioprotection contre les dommages causes par l'ischemie reperfusion (IR) en maintenant la fonction mitochondriale. Nous avons examine l'effet d'un nouvel inhibiteur de la sEH (sEHi) sur le controle du dommage cause par l'IR. Des coeurs de souris ont ete perfuses dans le systeme de Langendorff pendant 40 min et soumis a une ischemie statique globale de 20 min, suivie d'une reperfusion de 40 min. Les coeurs ont ete perfuses avec le sEHi, le BI00611953 (N-(2-chloro-4-methanesulfonyl-benzyl)-6(2,2,2-trifluoro-ethoxy)-nicotinamide) (0, 0,1, 1,0, et 10,0 µmol*[L.sup.-1]). L'inhibition de la sEH par le BI00611953 ameliorait significativement la pression ventriculaire gauche post-ischemique et reduisait la taille de l'infarctus apres l'IR comparativement aux coeurs controles et similairement aux coeurs perfuses avec des 11,12-EET (1 µmol*[L.sup.-1]) et aux souris sE[H.sup.-/-]. La perfusion avec un antagoniste presume du recepteur des EET, l'acide 14,15-epoxyei'cosa-5(Z)-enoi'que (14,15-EEZE, 10 µmol*[L.sup.-1]), ou avec un inhibiteur des canaux KATP de la membrane plasmique (pm[K.sub.ATP)] (glibenclamide, 10 µmol*[L.sup.-1]) supprimait l'amelioration de la recuperation induite par le BI00611593. Des etudes mecanistiques realisees chez les cellules H9c2 ont demontre que le BI00611593 diminuait la generation d'ERO, la caspase-3 et l'activite du proteasome, augmentait la liaison du HIF-1 a l'ADN, et retardait la perte de potentiel membranaire mitochondrial (Δ[Ψ.sub.m]) causee par l'anoxie-reoxygenation. L'ensemble de ces donnees demontre que ce nouvel sEHi, le BI00611953, un compose a base de nicotinamide, confere une cardioprotection significative contre les dommages causes par l' ischemie reperfusion Mots-cles : acide epoxyei'cosatrienoi'que, epoxyde hydrolase soluble, ischemie-reperfusion, canaux pm[K.sub.ATP,] inhibiteurs de la sEH.

Blood glucose-lowering therapies can positively or negatively affect heart function in type 2 diabetes, or they can have neutral effects. Dipeptidyl peptidase 4 (DPP-4) inhibitors lower blood glucose by preventing the proteolytic inactivation of glucagon-like peptide 1 (GLP-1). However, GLP-1 is not the only peptide substrate of DPP-4. Here, we investigated the GLP-1-independent cardiac effects of DPP-4 substrates. Pointing to GLP-1 receptor (GLP-1R)-independent actions, DPP-4 inhibition prevented systolic dysfunction equally in pressure-overloaded wild-type and GLP-1R knockout mice. Likewise, DPP-4 inhibition or the DPP-4 substrates substance P or C-X-C motif chemokine ligand 12 (CXCL12) improved contractile recovery after no-flow ischemia in the hearts of otherwise healthy young adult mice. Either DPP-4 inhibition or CXCL12 increased phosphorylation of the Ca2+ regulatory protein phospholamban (PLN), and CXCL12 directly enhanced cardiomyocyte Ca2+ flux. In contrast, hearts of aged obese diabetic mice (which may better mimic the comorbid patient population) had diminished levels of PLN phosphorylation. In this setting, CXCL12 paradoxically impaired cardiac contractility in a phosphoinositide 3-kinase γ-dependent manner. These findings indicate that the cardiac effects of DPP-4 inhibition primarily occur through GLP-1R-independent processes and that ostensibly beneficial DPP-4 substrates can paradoxically worsen heart function in the presence of comorbid diabetes. [ABSTRACT FROM AUTHOR]

Introduction: Carotid intima formation is a significant risk factor for cardiovascular disease. C3H/FeJ (C3H/F) and SJL/J (SJL) inbred mouse strains differ in susceptibility to immune and vascular traits. Using a congenic approach we demonstrated that the Intima modifier 2 (Im2) locus on chromosome 11 regulates leukocyte infiltration. We sought to determine whether inflammation was due to changes in circulating immune cells or activation of vascular wall cells in genetically pure Im2 (C3H/F.SJL.11.1) mice.Methods and Results: Complete blood counts showed no differences in circulating cells between C3H/F and C3H/F.SJL.11.1 compared to SJL mice. Aortic vascular cell adhesion molecule-1 (VCAM-1) total protein levels were dramatically increased in SJL and C3H/F.SJL.11.1 compared to C3H/F mice. Immunostaining of aortic endothelial cells (EC) showed a significant increase in VCAM-1 expression area (um2) in SJL (0.18±0.02) and C3H/F.SJL.11.1 (0.19±0.02) compared to C3H/F (0.09±0.02) under steady flow conditions. In regions of disturbed flow we observed a significant decrease in EC area, measured by membrane staining, in SJL (500±50) and C3H/F.SJL.11.1 (500±30) versus C3H/F (800±50). Vascular permeability measured by the Miles assay (Evans’ blue dye ug per mg of aorta) was significantly higher in SJL (0.043±0.006) compared to C3H/F (0.010±0.005). In C3H/F.SJL.11.1 congenic mice vascular permeability varied from 0.006 to 0.665 but the average trended toward SJL values.Conclusions: Our results indicate that Im2 regulation of leukocyte infiltration is mediated by EC inflammation and permeability. Comparative analysis of gene polymorphisms in human regions syntenic with the mouse Im2 locus provides new insights into candidate genes that regulate vascular wall inflammation. [ABSTRACT FROM AUTHOR]

Introduction: Our laboratory has shown that Axl, a receptor tyrosine kinase, is important in both vascular and immune functions during deoxycorticosterone acetate (DOCA)-salt hypertension. We hypothesized that Axl activity specifically in T lymphocytes could explain the dependence of hypertension on Axl.Methods and Results: We did adoptive transfers of either Axl+/+ or Axl-/- CD4+ T cells to RAG1-/- mice that lack mature T cells. Once CD4+ T cell repopulations were confirmed, we induced DOCA-salt hypertension for 6 weeks. Systolic blood pressure (BP, mmHg) increased by 20±5 in Axl+/+RAG-/- mice after DOCA-salt, but Axl-/- RAG-/- mice had increases in BP by only 6+3 after 6 weeks of DOCA-salt. We isolated naïve CD4+ T cells from both Axl+/+ and Axl-/- littermates and primed them under either Th1 or Th2 polarizing conditions in culture. Production of interferon gamma (IFN-γ ng/mL) was significantly decreased (-23%, p<0.05) in Axl-/- (396±23) compared to Axl+/+ (512±42) under Th1-priming. However, Axl had no effect on interleukin 4 (IL-4, ng/mL) production under Th2 polarizing conditions. Intracellular staining of the Th1/Th2 cells with IFN-γ and IL-4 antibodies by flow cytometry confirmed expression of cytokines in culture media. Complete blood counts showed that Axl-/- mice had significantly lower white blood cells due to decreased numbers of lymphocytes (4.5±0.7x109) compared to Axl+/+ mice (7.8±0.7x109). We found a higher population of AnnexinV (marker of early apoptosis)-positive peripheral leukocytes in Axl-/- mice (10±1%) compared to Axl+/+ (4±1%) by flow cytometry; while the percentages of dead cells (~10%) were similar between Axl+/+ and Axl-/- mice.Conclusions: Altogether we show that expression of Axl by T cells drives salt-induced hypertension. The mechanism of Axl-dependent effects on T cells occurs via T-cell-dependent expression of the pro-inflammatory cytokine IFN-γ. In addition, Axl plays a role in inhibiting lymphocyte apoptosis in the circulation. Future work will focus on how Axl expression in T cells affects T cell-dependent vascular remodeling during hypertension. [ABSTRACT FROM AUTHOR]

The pathophysiological mechanisms of the immune activation of smooth muscle cells are not well understood. Increased expression of Axl, a receptor tyrosine kinase, was recently found in arteries from patients after coronary bypass grafts. In the present study, we hypothesized that Axl-dependent immune activation of smooth muscle cells regulates vein graft remodeling. We observed a twofold decrease in intimal thickening after vascular and systemic depletion of Axl in vein grafts. Local depletion of Axl had the greatest effect on immune activation, whereas systemic deletion of Axl reduced intima due to an increase in apoptosis in vein grafts. Primary smooth muscle cells isolated from Axl knockout mice had reduced proinflammatory responses by prevention of the STAT1 pathway. The absence of Axl increased suppressor of cytokine signaling (SOCS)1 expression in smooth muscle cells, a major inhibitory protein for STAT1. Ultrasound imaging suggested that vascular depletion of Axl reduced vein graft stiffness. Axl expression determined the STAT1-SOCS1 balance in vein graft intima and progression of the remodeling. The results of this investigation demonstrate that Axl promotes STAT1 signaling via inhibition of SOCS1 in activated smooth muscle cells in vein graft remodeling., (Copyright © 2015 the American Physiological Society.)