Search

Epithelial-to-mesenchymal transition (EMT) has emerged as a critical event in the pathogenesis of tubulointerstitial fibrosis. EMT is typically induced by transforming growth factor-β1 (TGF-β1) and inhibited by hepatocyte growth factor (HGF). The present study was undertaken to evaluate the potential role of cyclooxygenase (COX)-2-derived PGE2 in regulation of EMT in cultured Madin-Darby canine kidney (MDCK) cells, in the setting of HGF treatment. Exposure to 50 ng/ml HGF significantly induced COX-2 protein expression and PGE2 release, whereas other growth factors, including epidermal growth factor, the insulin-like growth factor I protein, platelet-derived growth factor- BB, and TGF-β1, had no effects on COX-2 expression or PGE2 release. COX-2 induction by HGF was preceded by activation of ERK1/2, and an ERK1/2-specific inhibitor, U-0126 (10 µM), completely abolished HGF-induced COX-2 expression. Exposure of MDCK cells to 10 ng/ml TGF-β1 for 72 h induced EMT as evidenced by conversion to the spindle-like morphology, loss of E-cadherin, and activation of a-smooth muscle actin. In contrast, treatment with 1 µM PGE2 completely blocked EMT, associated with a significant elevation of intracellular cAMP and complete blockade of TGF-β1-induced oxidant production. cAMP-elevating agents, including 8-Br-cAMP, forskolin, and IBMX, inhibited EMT and associated oxidative stress induced by TGF-β1, but inhibition of cAMP pathway with Rp-cAMP, the cAMP analog, and H89, the protein kinase A (PKA) inhibitor, did not block the effect of PGE2. The effect of HGF on EMT was inhibited by ~50% in the presence of a COX-2 inhibitor SC-58635 (10 µM). Therefore, our data suggest that PGE2 inhibits EMT via inhibition of oxidant production and COX-2-derived PGE2 partially accounts for the antifibrotic effect of HGF. [ABSTRACT FROM AUTHOR]

Cytochrome P-450-4A1 (CYP4A1) is an ω-hydroxylase that catalyzes the metabolism of arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE). The goal of this study was to determine the vasomotor consequences of vascular overexpression of CYP4A1. Isolated rat gracilis muscle arterioles transfected ex vivo with an expression plasmid containing CYP4A1 cDNA expressed more CYP4A protein than vessels transfected with the control plasmid. In arterioles pressurized to 80 mmHg, the internal diameter of vessels transfected with CYP4A1 cDNA (55 ± 3 µm) was surpassed (P < 0.05) by that of vessels transfected with control plasmid (97 ± 4 µm). Treatment with a CYP4A inhibitor (N-methylsulfonyl-12,12dibromododec-11-enamide; DDMS) or with an antagonist of 20HETE actions [20-hydroxyeicosa-6(Z), 15(Z)-dienoic acid; 20-HEDE] elicited robust dilation of arterioles transfected with CYP4A1 cDNA, whereas the treatment had little or no effect in vessels transfected with control plasmid. Examination of the intraluminal pressure-internal diameter relationship revealed that pressure increments over the range of 40-100 mmHg elicited a more intense (P < 0.05) myogenic constrictor response in arterioles transfected with CYP4A1 cDNA than in those with control plasmid. Arterioles transfected with CYP4A1 cDNA also displayed enhanced sensitivity to the constrictor action of phenylephrine. Treatment with DDMS or 20-HEDE greatly attenuated the constrictor responsiveness to both constrictor stimuli in vessels overexpressing CYP4A1, whereas the treatment had much less effect in control vessels. These data suggest that CYP4A1 overexpression promotes constriction of gracilis muscle arterioles by intensifying the responsiveness of vascular smooth muscle to constrictor stimuli. This effect of CYP4A1 overexpression appears to be mediated by a CYP4A1 product. [ABSTRACT FROM AUTHOR]

Hydroxyeicosatetraenoic acid (20-HETE), which promotes renal vasoconstriction, is formed in the rat kidney primarily by cytochrome P-450 (CYP) 4A isoforms (4A1, 4A2, 4A3, 4A8). Nitric oxide (NO) has been shown to bind to the heme moiety of the CYP4A2 protein and to inhibit 20-HETE synthesis in renal arterioles of male rats. However, it is not known whether NO interacts with and affects the activity of CYP4A1 and CYP4A3, the major renal CYP4A isoforms in female rats. Incubation of recombinant CYP4A1 and 4A3 proteins with sodium nitroprusside (SNP) shifted the absorbance at 440 nm, indicating the formation of a ferric-nitrosyl-CYP4A complex. The absorbance for CYP4A3 was about twofold higher than that of CYP4A1. Incubation of SNP or peroxynitrite (PN; 0.01-1 mM) with CYP4A recombinant membranes caused a concentration-dependent inhibition of 20-HETE synthesis, with both chemicals having a greater inhibitory effect on CYP4A3-catalyzed activity. Moreover, incubation of CYP4A1 and 4A3 proteins with PN (1 mM) resulted in nitration of tyrosine residues in both proteins. In addition, PN and SNP inhibited 20-HETE synthesis in renal microvessels from female rats by 65 and 59%, respectively. We previously showed that microvessel CYP4A1/CYP4A3 expression and 20-HETE synthesis are decreased in late pregnancy. Therefore, we investigated whether such a decrease is dependent on NO, the synthesis of which has been shown to increase in late pregnancy. Administration of N[sup G]-nitro-L-arginine methyl ester (LNAME) to pregnant rats for 6 days (days 15-20 of pregnancy) caused a significant increase in systolic blood pressure, which was prevented by concurrent treatment with the CYP4A inhibitor 1-aminobenzotriazole (ABT). Urinary NO[sub 2]/NO[sub 3] excretion decreased by 40 and 52% in L-NAMEand L-NAME + ABT-treated groups, respectively. Interestingly, renal microvessel 20-HETE synthesis showed a marked increase following L-NAME treatment, and this increase was diminished with... [ABSTRACT FROM AUTHOR]

20-HETE, a cytochrome P-450 4A (CYP4A1)-derived arachidonic acid metabolite, is a major eicosanoid formed in renal and extrarenal microcirculation. 20-HETE inhibits Ca[sup 2+]-activated K[sup +] channels in vascular smooth muscle cells and thereby may modulate vascular reactivity. We transfected renal interlobar arteries with an expression plasmid containing the cDNA of CYP4A1, the low-K[sub m] arachidonic acid ω-hydroxylase, and examined the consequences of into creasing 20-HETE synthesis on constrictor responses to phenylephrine. CYP4A1-transfected interlobar arteries demonstrated a twofold increase in CYP4A protein levels and 20-HETE production compared with arteries transfected with the empty plasmid; they also showed increased sensitivity to phenylephrine, as evidenced by a decrease in EC[sub 50] from 0.37 ± 0.04 µM in plasmid-transfected arteries to 0.07 ± 0.01 µM in CYP4A1-transfected arteries. The increased sensitivity to phenylephrine was greatly attenuated by N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS), a selective inhibitor of 20-HETE synthesis, and by 20-hydroxyeicosa-6(Z),15(Z)-dienoic acid, a specific 20-HETE antagonist. This effect of DDMS was reversed by addition of 20-HETE, further substantiating the notion that increased levels of 20-HETE contribute to the increased sensitivity to phenylephrine in vessels overexpressing CYP4A1. These data suggest that 20-HETE of vascular origin sensitizes renal vascular smooth muscle to phenylephrine. [ABSTRACT FROM AUTHOR]

Examines the cytochrome P-450 (CYP) isoform expression and 20-hydroxyeicosatetraenoic (HETE) acid synthesis in renal preglomerular arteries. Detection of 20-HETE in preglomerular arterioles; Hydroxylation of arachidonic acid to the 20-HETE; Catalytic properties of CYP isoforms.

Examines whether renal 20-hydoxyeicosatetraenoic acid (20-HETE) synthesis is altered during gestation. Background information on 20-HETE; Comparison of 20-HETE synthesis in renal microvessels and in the isolated thick medullary limb at different days of gestation; Effects of 1-aminobenzotriazole on 20-HETE synthesis.

Examines the effect of cytochrome P-450 4A isoform 1 (CYP4A1) antisense oligonucleotide (ODN) on mesenteric vascular reactivity and blood pressure in spontaneously hypertensive rats (SHR). Decrease in mean arterial blood pressure; Decline of sensitivity of rats treated with antisense ODN to phenylephrine; Observation on pressormechanisms in SHR.

Examines the kinetic profile of the rat cytochrome P-450 (CYP) 4A isoforms and their biological effects on renal tubular and vascular functions and on the control of the arterial pressure. Suggestion that CYP4A1 may constitute the major source of 20-hydroxyeicosatetraenoic acid (HETE) synthesis; Fatty acid hydroxylation; Regulation of vascular tone.

PGE2 has an established role in renal water handling. The present study was undertaken to examine the role of microsomal prostaglandin E synthase-1 (mPGES-1) in the diuretic response to acute and chronic water loading. Compared with wild-type (+/+) controls, mPGES-1 -/- mice exhibited impaired ability to excrete an acute, but not chronic water load. In response to acute water loading, urinary PGE2 excretion in the +/+ mice increased at 2 h, in parallel with increased urine flow. In contrast, the -/- mice exhibited a delayed increase in urinary PGE2 excretion, coinciding with the stimulation of renal medullary mRNA expression of cytosolic prostaglandin E synthase but not mPGES-2. At baseline, renal aquaporin-2 (AQP2) expression in mPGES-1 -/- mice was enhanced compared with the +/+ control. In response to acute water loading, renal AQP2 expression in the +/+ mice was significantly reduced, and this reduction was blunted in the -/- mice. Despite striking changes in AQP2 protein expression, renal AQP2 mRNA in both genotypes largely remained unchanged. Overall, these data support an important role of mPGES-1 in provoking the diuretic response to acute water loading. [ABSTRACT FROM AUTHOR]

Tubular cell apoptosis is involved in ischemic renal failure, but the underlying mechanism is unclear. Bid, a proapoptotic Bcl-2 family protein, may regulate the intrinsic as well as the extrinsic pathway of apoptosis. In vivo, Bid is most abundantly expressed in the kidneys. However, the role played by Bid in renal pathophysiology is unknown. Our recent work demonstrated Bid activation during renal ischemia-reperfusion. The current study has determined the role of Bid in ischemic renal injury and renal failure using Bid-deficient mice. In wild-type C57BL16 mice, Bid was proteolytically processed into active forms during renal ischemia-reperfusion, which subsequently targeted mitochondria. This was accompanied by the development of tissue damage and severe renal failure, showing serum creatinine of 3.0 mg/dl after 48 h of reperfusion. The same ischemic insult induced acute renal failure in Bid-deficient mice, which was nonetheless less severe than the wild-type, showing 1.3 mg/dl serum creatinine. In addition, Bid deficiency attenuated tubular disruption, tubular cell apoptosis, and caspase-3 activation during 48 h of reperfusion. Compared with wild-type, animal death following renal ischemia was delayed in Bid-deficient mice. Collectively, the results suggest a role for Bid in ischemic renal injury and renal failure. [ABSTRACT FROM AUTHOR]

Divalent metal ions such as copper, manganese, and cobalt are essential for cell development, differentiation, function and survival. These essential metal ions are delivered into intracellular domains as cofactors for enzymes involved in europeptide and neurotransmitter synthesis, superoxide metabolism, and other biological functions in a target specific fashion. Altering the homeostasis of these essential metal ions is known to connect to a number of human diseases including Alzheimer disease, amyotrophic lateral sclerosis, and pain. It remains unclear how these essential metal ions are delivered to intracellular targets in mammalian cells. Here we report that rat spinal cord dorsal horn neurons express ACDP4, a member of Ancient Conserved Domain Protein family. By screening a pretransformed human fetal brain cDNA library in a yeast two-hybrid system, we have identified that ACDP4 specifically interacts with COX11, an intracellular metal ion chaperone. Ectopic expression of ACDP4 in HEK293 cells resulted in enhanced toxicity to metal ions including copper, manganese, and cobalt. The metal ion toxicity became more pronounced when ACDP4 and COX11 were co-expressed ectopically in HEK293 cells, suggesting a functional coupling between them. Our results indicate a role of ACDP4 in metal ion homeostasis and toxicity. This is the first report revealing a functional aspect of this ancient conserved domain protein family. We propose that ACDP is a family of transporter protein or chaperone proteins for delivering essential metal ions in different mammalian tissues. The expression of ACDP4 on spinal cord dorsal horn neurons may have implications in sensory neuron functions under physiological and pathological conditions. [ABSTRACT FROM AUTHOR]

Apoptosis has been implicated in ischemic renal injury, Thus one strategy of renal protection is to antagonize apoptosis, However, apoptosis inhibitory approaches remain to be fully explored. Zn2+ has long been implicated in apoptosis inhibition; but systematic analysis of the inhibitory effects of Zn2+ is lacking,Moreover, whether Zn2+ blocks renal cell apoptosis following ischemia is unknown. Here, we demonstrate that n2+ is a potent apoptosis inhibitor in an in vitro model of renal cell ischemia. ATP depletion induced apoptosis in cultured renal tubular cells, which was accompanied by caspase activation. Zn2+ at 10 µm inhibited both apoptosis and caspase activation, whereas Co2+ was without effect. In ATP-depleted cells,n2+ partially prevented Bax activation and cytochrome c release from mitochondria. In isolated cell cytosol, n2+blocked cytochrome c-stimulated caspase activation at low-micromolar concentrations. In addition, Zn2+ could directly antagonize the enzymatic activity of purified recombinant caspases. We conclude that Zn2+ is a potent inhibitor of apoptosis in renal tubular cells following ATP depletion. n2+ blocks apoptosis at multiple steps including Bax activation, cytochrome c release, apoptosome function, and caspase activation. [ABSTRACT FROM AUTHOR]

Bid is a proapoptotic Bcl-2 family protein, which on activation translocates to mitochondria and induces damage to the organelles. Activation of Bid depends on its proteolytic processing into truncated forms of tBid. Bid is highly expressed in the kidneys; however, little is known about its role in renal pathophysiology. In this study, we initially examined Bid activation in cultured rat kidney proximal tubular cells following ATP depletion. The cells were depleted of ATP by azide incubation in the absence of metabolic substrates and then returned to normal culture medium for recovery. Typical apoptosis developed during recovery of ATP-depleted cells. This was accompanied by Bid cleavage, releasing tBid of 15 and 13 kDa. Bid cleavage was abolished in cells overexpressing Bcl-2, an antiapoptotic gene. It was also suppressed by caspase inhibitors. Peptide inhibitors of caspase-9 were more effective in blocking Bid cleavage compared with inhibitors of caspase-8 and caspase-3. Provision of glucose, a glycolytic substrate, during azide incubation inhibited Bid cleavage as well, indicating that Bid cleavage was initiated by ATP depletion. Consistently, Bid cleavage was also induced following ATP depletion by hypoxia or mitochondrial uncoupling. Of significance, cleaved Bid translocated to mitochondria, suggesting a role for Bid in the development of mitochondrial defects in ATP-depleted cells. Finally, Bid cleavage was induced during renal ischemia-reperfusion in the rat. Together, these results provide the first evidence for Bid activation in kidney cells following ATP depletion in vitro and renal ischemia in vivo. [ABSTRACT FROM AUTHOR]

Advanced oxidation protein products (AOPPs) are independent risk factor for various cardiovascular diseases. Cardiomyocyte apoptosis has been implicated as an important mechanism in cardiac remodeling in chronic kidney disease (CKD). However, whether AOPPs affect cardiomyocyte apoptosis and subsequent cardiac remodeling in CKD is still not very clear. Here, we assessed the role of AOPPs in cardiomyocyte apoptosis in CKD. H9C2 rat cardiomyoblast cells were exposed to AOPPs. Apoptotic cells were determined by TUNEL assay. The expression of apoptotic markers (cleaved caspase-3 and Bax), JNK signaling, and endoplasmic reticulum stress were explored. Serum AOPPs were measured in male Sprague-Dawley rats that underwent sham surgery and 5/6 nephrectomy, respectively. In vitro, our findings showed that AOPPs activated JNK signaling and endoplasmic reticulum stress and significantly aggravated H9C2 rat cardiomyoblast cells apoptosis. These effects were partially ameliorated by apocynin with inhibition of oxidative stress. In vivo, serum levels of AOPPs were progressively elevated with the increasing time course in CKD rats compared with sham-operated rats (P < 0.05). Serum AOPP levels were positively associated with cardiomyocyte apoptosis (R² = 0.76, P < 0.01). In conclusion, AOPPs aggravate cardiomyocyte apoptosis in vitro, and these effects are partially prevented by apocynin via suppressing JNK signaling and endoplasmic reticulum stress with oxidative stress inhibition. In vivo, AOPPs are increased in the CKD model and may contribute to the cardiac pathogenesis, but at this point it is unclear if that is true. These results suggest that pharmacological approaches to attenuate AOPP-aggravated cardiomyocyte apoptosis may be beneficial to improve cardiac remodeling in CKD. [ABSTRACT FROM AUTHOR]

20-Hydroxyeicosatetraenoic acid (20-HETE), Cyp4a-derived eicosanoid, is a lipid mediator that promotes tumor growth, as well as causing detrimental effects in cerebral circulation. We determined whether concurrent inhibition of cyclooxygenase-2 (COX-2) and 20-HETE affects colon tumor growth and ischemic stroke outcomes. The expression of Cyp4a and COXs and production of 20-HETE and PGE2 were determined in murine colon carcinoma (MC38) cells. We then examined the effects of combined treatment with rofecoxib, a potent COX-2 inhibitor, and HET0016, a potent Cyp4a inhibitor, on the growth and proliferation of MC38 cells. Subsequently, we tested the effects of HET0016 plus rofecoxib in MC38 tumor and ischemic stroke models. Cyp4a and COXs are highly expressed in MC38 cells. Respectively, HET0016 and rofecoxib inhibited 20-HETE and PGE2 formation in MC38 cells. Moreover, rofecoxib combined with HET0016 had greater inhibitory effects on the growth and proliferation of MC38 cells than did rofecoxib alone. Importantly, rofecoxib combined with HET0016 provided greater inhibition on tumor growth than did rofecoxib alone in MC38 tumor-bearing mice. Prolonged treatment with rofecoxib selectively induced circulating 20-HETE levels and caused cerebrovascular damage after ischemic stroke, whereas therapy with rofecoxib and HET0016 attenuated 20-HETE levels and reduced rofecoxib-induced cerebrovascular damage and stroke outcomes during anti-tumor therapy. Thus these results demonstrate that combination therapy with rofecoxib and HET0016 provides a new treatment of colon tumor, which can not only enhance the anti-tumor efficacy of rofecoxib, but also reduce rofecoxib-induced cerebrovascular damage and stroke outcomes. [ABSTRACT FROM AUTHOR]

Studies suggest that soluble epoxide hydrolase (sEH) inhibition reduces end-organ damage in cardiovascular diseases. We hypothesize that sEH gene (Ephx2) knockout (KO) improves endothelial function and reduces renal injury in streptozotocin-induced diabetes. After 6 wk of diabetes, afferent arteriolar relaxation to acetylcholine was impaired in diabetic wild-type (WT) mice, as the maximum relaxation was 72% of baseline diameter in the WT but only 31% in the diabetic mice. Ephx2 KO improved afferent arteriolar relaxation to acetylcholine in diabetes as maximum relaxation was 58%. Urinary monocyte chemoattractant protein-1 (MCP-1) excretion significantly increased in diabetic WT mice compared with control (868 ± 195 vs. 31.5 ± 7 pg/day), and this increase was attenuated in diabetic Ephx2 KO mice (420 ± 98 pg/day). The renal phospho-IKK-to-IKK ratio and nuclear factor-κB were significantly decreased, and hemeoxygenase-1 (HO-1) expression increased in diabetic Ephx2 KO compared with diabetic WT mice. Renal NADPH oxidase and urinary thiobarbituric acid reactive substances excretion were reduced in diabetic Ephx2 KO compared with diabetic WT mice. Albuminuria was also elevated in diabetic WT mice compared with control (170 ± 43 vs. 37 ± 13 μg/day), and Ephx2 KO reduced this elevation (50 ± 15 μg/day). Inhibition of sEH using trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (tAUCB) also reduced renal inflammation and injury in diabetic WT mice. Furthermore, inhibition of HO with stannous mesoporphyrin negated the reno-protective effects of tAUCB or Ephx2 KO during diabetes. These data demonstrate that Ephx2 KO improves endothelial function and reduces renal injury during diabetes. Additionally, our data also suggest that activation of HO-1 contributes to improved renal injury in diabetic Ephx2 KO mice. [ABSTRACT FROM AUTHOR]

The early stage of diabetic nephropathy (DN) is linked to proteinuria. Transforming growth factor (TGF)-β1 increases glomerular permeability to albumin (Palb), whereas 20-HETE and EETs reduce Palb. To investigate the impact of hyperglycemia and hyperlipidemia on 20-HETE, EETs, and TGF-β1 in the glomeruli, rats were divided into four groups: ND rats were fed a normal diet, HF rats were fed a high-fat diet, STZ rats were treated with 35 mg/kg of streptozotocin, and HF/STZ rats were fed a HF diet and treated with STZ. After 10 wk on these regimens, blood glucose, urinary albumin, serum cholesterol, serum triglyceride levels, and the kidney-to-body weight ratio were significantly elevated in STZ and HF/STZ rats compared with HF and ND rats. STZ and HF/STZ rats had histopathologic changes and abnormal renal hemodynamics. Expression of glomemlar CYP4A, enzymes for 20-HETE production, was significantly decreased in STZ rats, whereas expression of glomerular CYP2C and CYP2J, enzymes for EETs production, was significantly decreased in both STZ and HF/STZ rats. Moreover, glomerular TGF-β1 levels were significantly greater in STZ and HF/STZ rats than in HF and ND rats. Five-week treatment of STZ rats with clofibrate induced glomerular CYP4A expression and 20-HETE production, but reduced glomerular TGF-β1 and urinary protein excretion. These results demonstrate that hyperglycemia increases TGF-β1 but decreases 20-HETE and EETs production in the glomeruli, changes that may be important in causing glomerular damage in the early stage of DN. [ABSTRACT FROM AUTHOR]

Clofibrate, a peroxisome proliferator-activated receptor-α (PPARα) agonist, increases renal tubular cytochrome P450 4a (Cyp4a) expression thereby increasing 20-hydroxyeicosatetraenoic acid (20-HETE) production. To determine if clofibrate affects blood pressure regulation we studied mice with DOCA-salt induced hypertension in wild-type and PPARα knockout mice. Wild-type mice treated with DOCA-salt had higher mean arterial pressures and higher cumulative sodium balance, but lower renal 20-HETE production than did vehicle-treated mice. Treating DOCA-salt mice with clofibrate attenuated the increase in mean arterial pressure and cumulative sodium balance while increasing 20-HETE production and renal Cyp4a expression. In contrast the PPARα knockout mice treated with clofibrate and DOCA-salt showed no attenuation in the increase of blood pressure, cumulative sodium balance, renal 20-HETE production or Cyp4a protein expression. Expression of the PPARα protein was greater in proximal tubules than in renal microvessels. Our results show that PPARα pathway induces renal tubular 20-HETE production which affects sodium retention and blood pressure regulation in DOCA-salt-treated mice.Kidney International (2008) 74, 1040–1048; doi:10.1038/ki.2008.300; published online 2 July 2008 [ABSTRACT FROM AUTHOR]

Nitroalkene derivatives of linoleic acid (nitrolinoleic acid; LNO2) and nitro-oleic acid (OA-NO2) are endogenous lipid products with potent anti-inflammatory properties. The present study was undertaken to evaluate the therapeutic potential of OA-NO2 in a mouse model of renal ischemia-reperfusion (I/R) injury. B6129SF2/J mice were subjected to bilateral renal ischemia for 30 min, followed by 24 h of reperfusion. Fifty minutes after ischemia, mice received intraperitoneal (ip) injections of OA- NO2 (500 µg/kg; I/R OA-NO2), vehicle for OA-NO2 (i.e., 0.8 ml/kg ethanol; I/R veh), or oleic acid (500 µg/kg; I/R OA) every 6 h during the 24-h recovery period. A sham-operated group was not subjected to ischemia and received 0.8 mI/kg ethanol ip every 6 h during the 24-h recovery period (sham veh). While plasma urea and creatinine were elevated (P < 0.05) in I/R veh vs. sham veh mice, the severity was less (P < 0.05) in I/R OA-NO2 animals. Indices of histological damage, polymorphonucleocyte infiltration, together with expression of intracellular adhesion molecule-1, interleukin-1β, and tumor necrosis factor-α, p47phox, and gp91phox were greater in I/R veh vs. sham veh mice, but were attenuated (P < 0.05) in I/R OA-NO2 animals. Because indices of renal dysfunction were similar between I/R veh and I/R OA mice (P > 0.05), but less (P < 0.05) in I/R OA-NO2 animals compared with both groups, protection from bilateral renal ischemia is afforded by the nitrated but not free form of oleic acid. Together, delayed administration of nitrated fatty acid OA-NO2 attenuates renal I/R injury in the mouse likely via inhibition of the inflammatory response. [ABSTRACT FROM AUTHOR]

OBJECTIVE--The implication of innate immunity in type 1 diabetes development has long been proposed. High-mobility group box 1 (HMGB1), an evolutionarily conserved chromosomal protein, was recently recognized to be a potent innate inflammatory mediator when released extracellularly. We sought to test the hypothesis that HMGB1 acts as an innate immune mediator implicated in type 1 diabetes pathogenesis. RESEARCH DESIGN AND METHODS--Eight- and 12-week-old NOD mice were treated with an HMGB1 neutralizing antibody once a week until 25 weeks of age and monitored for insulitis progression and diabetes onset. The underlying mechanisms of HMGB1 regulation of autoimmune response were further explored. RESULTS--During autoimmunity, HMGB1 can be passively released from damaged pancreatic β-cells and actively secreted by islet infiltrated immune cells. Extracellular HMGB1 is potent in inducing NOD dendritic cell maturation and stimulating macrophage activation. Blockade of HMGB1 significantly inhibited insulitis progression and diabetes development in both 8- and 12-week-old NOD mice. HMGB1 antibody treatment decreased the number and maturation of pancreatic lymph node (PLN) CD11c[sup ++]CD11b[sup +] dendritic cells, a subset of dendritic cells probably associated with autoantigen presentation to naive T-cells, but increased the number for PLN CD4[sup +]Foxp3[sup +] regulatory T-cells. Blockade of HMGB1 also decreased splenic dendritic cell allo-stimulatory capability associated with increased tolergenic CD11c[sup +]CD8a[sup +] dendritic cells. Interestingly, the number of CDS[sup +]interferon-γ[sup +] (Tc1) T-cells was increased in the PLNs and spleen after blockade of HMGB1, which could be associated with retarded migration of activated autoreactive T-cells into the pancreatic islets. CONCLUSIONS--Extracellular HMGB1 functions as a potent innate immune mediator contributing to insulitis progression and diabetes onset. Diabetes 57:2118-2127, 2008 [ABSTRACT FROM AUTHOR]

Since epoxyeicosatrienoic acids (EETs) affect sodium reabsorption in renal tubules and dilate the renal vasculature, we have examined their effects on renal hemodynamics and sodium balance in male rats fed a high-fat (HF) diet by fenofibrate, a peroxisome proliferator-activated receptor-α (PPAR-α) agonist and an inducer of cytochrome P-450 (CYP) epoxygenases; by N-methanesulfonyl-6-(2-proparyloxyphenyl)hexanamide (MSPPOH), a selective EET biosynthesis inhibitor; and by 12-(3-adamantane-l-yl-ureido)dodecanoic acid (AUDA), a selective inhibitor of soluble epoxide hydrolase. In rats treated with fenofibrate (30 mg·kg-1·day-1 ig) or AUDA (50 mg/I in drinking water) for 2 wk, mean arterial pressure, renal vascular resistance, and glomerular filtration rate were lower but renal blood flow was higher than in vehicle-treated control rats. In addition, fenofibrate and AUDA decreased cumulative sodium balance in the HF rats. Treatment with MSPPOH (20 mg·kg-1·day-1 iv) + fenofibrate for 2 wk reversed renal hemodynamics and sodium balance to the levels in control HF rats. Moreover, fenofibrate caused a threefold increase in renal cortical CYP epoxygenase activity, whereas the fenofibrate-induced elevation of this activity was attenuated by MSPPOH. Western blot analysis showed that fenofibrate induced the expression of CYP epoxygenases in renal cortex and microvessels and that the induction effect of fenofibrate was blocked by MSPPOH. These results demonstrate that the fenofibrate-induced increase of CYP epoxygenase expression and the AUDA-induced stabilization of EET production in the kidneys cause renal vascular dilation and reduce sodium retention, contributing to the improvement of abnormal renal hemodynamics and hypertension in HF rats. [ABSTRACT FROM AUTHOR]

Experiments were performed to establish the pharmacological profile of purinoceptors and to identify the signal transduction pathways responsible for increases in intracellular calcium concentration ([Ca2+]i) for cultured mouse mesangial cells. Mouse mesangial cells were loaded with fura 2 and examined using fluorescent spectrophotometry. Basal [Ca2+]i averaged 102 ± 2 nM (n = 346). One hundred micromolar concentrations of ATP, ADP, 2′,3′-(benzoyl-4-benzoyl)-ATP (BzATP), ATP-γ-S, and UTP in normal Ca2+ medium evoked peak increases in [Ca2+]i of 866 ± 111, 236 ± 18, 316 ± 26, 427 ± 37, and 808 ± 73 nM, respectively. UDP or 2-methylthio-ATP (2MeSATP) failed to elicit significant increases in [Ca2+]i, whereas identical concentrations of adenosine, AMP, and α,β-methylene ATP (α,β-MeATP) had no detectable effect on [Ca2+]i. Removal of Ca2+ from the extracellular medium had no significant effect on the peak increase in [Ca2+]i induced by ATP, ADP, BzATP, ATP-γ-S, or UTP compared with normal Ca2+ however, Ca2+-free conditions did accelerate the rate of decline in [Ca2+]i in cells treated with ATP and UTP. [Ca2+]i was unaffected by membrane depolarization with 143 mM KCI. Western blot analysis for P2 receptors revealed expression of P2X2, P2X4, P2X7, P2Y2, and P2Y4 receptors. No evidence of P2X1 and P2X3 receptor expression was detected, whereas RT-PCR analysis reveals mRNA expression for P2X1, P2X2, P2X3, P2X4, P2X7, P2Y2, and P2Y4 receptors. These data indicate that receptor-specific P2 receptor activation increases [Ca2+]i by stimulating calcium influx from the extracellular medium and through mobilization of Ca2+ from intracellular stores in cultured mouse mesangial cells. [ABSTRACT FROM AUTHOR]

Previous studies have shown that the synthesis of renal cytochrome P-450 (CYP)-derived eicosanoids is downregulated in genetic or high-fat diet-induced obese rats. Experiments were designed to determine whether fenofibrate, a peroxisome proliferator-activated receptor (PPAR)-α agonist, would induce renal eicosanoid synthesis and improve endothelial function in obese Zucker rats. Administration of fenofibrate (150 mg·kg-1·day-1 for 4 wk) significantly reduced plasma insulin, triglyceride, and total cholesterol levels in obese Zucker rats. CYP2C11 and CYP2C23 proteins were downregulated in renal vessels of obese Zucker rats. Consequently, renal vascular epoxygenase activity decreased by 15% in obese Zucker rats compared with lean controls. Chronic fenofibrate treatment significantly increased renal cortical and vascular CYP2C11 and CYP2C23 protein levels in obese Zucker rats, whereas it had no effect on epoxygenase protein and activity in lean Zucker rats. Renal cortical and vascular epoxygenase activities were consequently in- creased by 54% and 18%, respectively, in fenofibrate-treated obese rats. In addition, acetylcholine (1 µM)-induced vasodilation was significantly reduced in obese Zucker kidneys (37% ± 11%) compared with lean controls (67% ± 9%). Chronic fenofibrate administration increased afferent arteriolar responses to 1 µM of acetylcholine in obese Zucker rats (69% ± 4%). Inhibition of the epoxygenase pathway with 6-(2-propargyloxyphenyl)hexanoic acid attenuated afferent arteriolar diameter responses to acetylcholine to a greater extent in lean compared with obese Zucker rats. These results demonstrate that the PPAR-α agonist fenofibrate increased renal CYP-derived eicosanoids and restored endothelial dilator function in obese Zucker rats. [ABSTRACT FROM AUTHOR]

We previously reported that inhibition of nitric oxide (NO) synthesis by N-nitro-L-arginine methyl ester (L-NAME) during late pregnancy leads to increased production of renal vascular 20-hydroxyeicosatetraenoic acid (20-HETE), a cytochrome P-450 (CYP) 4A-derived vasoconstrictor, in pregnant rats. However, the effect of upregulation of vascular 20-HETE production on renal function after NO inhibition is not known, To test the hypothesis that increased gestational vascular 20-HETE synthesis after NO inhibition is involved in mediating blood pressure and renal functional changes, we first determined the IC50 value of the effect of nitroprusside (SNP), a NO donor, on renal 20-HETE production in cortical microsomes. We then divided pregnant rats and age-matched virgin rats into a vehicle control group, an L-NAME treatment group (0.25 mg/ml in drinking water), and a group treated with L-NAME plus N-methylsulfonyl-12,12-dibromododec-11 enamide (DDMS; CYP4A-selective inhibitor, 10 mg∙kg-1∙day-1 iv). After 4 days of treatment, we measured blood pressure, renal blood flow (RBF), renal vascular resistance (RVR), and glomerular filtration rate (GFR) in each group. The addition of SNP (IC50 = 22 μM) decreased renal cortical 20-H ETE production. In pregnant rats, L-NAME treatment led to significantly higher mean arterial pressure (MAP) and RVR, and lower RBF and GFR. Combined treatment with DDMS and L-NAME significantly attenuated the increases in MAP and RVR and the decrease in GFR, but not the reduction in RBF induced by L-NAME treatment. L-NAME and L-NAME plus DDMS had no significant impact on renal hemodynamics in virgin rats. In addition, chronic treatment with DDMS selectively inhibited cortical 20-HETE production without a significant effect on CYP4A expression in L-NAME-treated pregnant rats. In conclusion, NO effectively inhibits renal cortical microsomal 20-HETE production in female rats. In pregnant rats, the augmentation of renal 20-HETE production after NO inhibition is associated with increased MAP and RVR, whereas decreased GFR is negated by treatment of a selective and competitive CYP4A inhibitor. These results demonstrate that the interaction between renal 20-HETE and NO is important in the regulation of renal function and blood pressure in pregnant rats. [ABSTRACT FROM AUTHOR]

Epoxyeicosatrienoic acids (EETs), which belong to cytochrome P-450 (CYP)-derived eicosanoids, have been implicated to vasodilate renal arterioles, inhibit sodium transport in the nephron, and regulate blood pressure in several animal models. Because pregnancy is associated with changes of blood pressure, the aim of this study was to examine whether renal EET synthesis is altered and whether EETs are involved in blood pressure regulation during pregnancy in rats. Renal microsomal epoxygenase activity increased by 47, 97, and 63% on days 6, 12, and 19 of gestation, respectively. The elevation of epoxygenase activity during pregnancy was associated with an increase in CYP2C11, CYP2C23, and CYP2J2 protein expression on days 6, 12, and 19 of gestation. Moreover, immunohistochemical analysis showed that renal tubular CYP2C11, CYP2C23, and CYP2J2 expression was significantly increased in pregnant rats on days 6, 12, and 19 of gestation. Administration of 6-(2-propargyloxyphenyl)hexanoic acid (PPOH), a selective epoxygenase inhibitor, caused a dose-dependent inhibition of microsomal expoxygenase activity without a significant effect on ω-hydroxylase activity in female rats. Interestingly, administration of PPOH (20 mg·kg-1· day-1 for 4 days starting on day 15 of pregnancy) increased blood pressure by 21 mmHg and caused a significant decrease in the body weight of fetal pups (1.3 ± 0.08 g in control vs. 1.1 ± 0.06 g in PPOH). Moreover, PPOH treatment significantly decreased renal microsomal epoxygenase activity and the expression of CYP2C11, CYP2C23, and CYP2J in pregnant rats. This study demonstrates that EET synthesis in the kidney is elevated during pregnancy, and CYP2C11, 2C23, and CYP2J2 am responsible for the change of renal EET synthesis. The inhibition results demonstrate that the downregulation of renal epoxygenase activity by PPOH causes hypertension in pregnant rats. This study suggests that EETs may contribute to the control of blood pressure during pregnancy. [ABSTRACT FROM AUTHOR]

Previous studies suggest that epoxyeicosatrienoic acids (EETs) are vasodilators of the mesenteric artery; however, the production and regulation of EETs in the mesenteric artery remain unclear. The present study was designed 1) to determine which epoxygenase isoform may contribute to formation of EETs in mesenteric arteries and 2) to determine the regulation of mesenteric artery cytochrome P-450 (CYP) enzymes in obese Zucker rats. Microvessels were incubated with arachidonic acid, and CYP enzyme activity was determined. Mesenteric arteries demonstrate detectable epoxygenase and hydroxylase activities. Next, protein and mRNA expressions were determined in microvessels. Although renal microvessels express CYP2C23 mRNA and protein, mesenteric arteries lacked CYP2C23 expression. CYP2C11 and CYP2J mRNA and protein were expressed in mesenteric arteries and renal microvessels. In addition, mesenteric artery protein expression was evaluated in lean and obese Zucker rats. Compared with lean Zucker rats, mesenteric arterial CYP2C11 and CYP2J proteins were decreased by 38 and 43%, respectively, in obese Zucker rats. In contrast, soluble epoxide hydrolase mRNA and protein expressions were significantly increased in obese Zucker rat mesenteric arteries. In addition, nitric oxide-independent dilation evoked by acetylcholine was significantly attenuated in mesenteric arteries of obese Zucker rats, These data suggest that the main epoxygenase isoforms expressed in mesenteric arteries are different from those expressed in renal microvessels and that decreased epoxygenases and increased soluble epoxide hydrolase are associated with impaired mesenteric artery dilator function in obese Zucker rats. [ABSTRACT FROM AUTHOR]

Presents the findings of a study which identified vasodilatory mechanisms involved in erectile function. Role of epoxyeicosatrienoic acids (EET) from cytochrome P450 (CYP) epoxygenases function in achieving full erection; Detection and localization of CYP epoxygenases; Result of reverse-phase high performance liquid chromatography analysis for metabolites of CYP epoxygenases; Effect of EET inhibition on erectile function in vivo.