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Purpose: Angiotensin II type 1 receptor blockers (ARBs) are widely used in treating hypertension. In the present study, we tested the hypothesis that a novel ARB, azilsartan medoxomil (AZL-M) will prevent renal and cardiovascular injury in the spontaneously hypertensive obese rat (SHROB), a model of cardiometabolic syndrome., Methods: Male SHROB were treated with vehicle or AZL-M orally for 56 days. Vehicle treated normotensive Wistar-Kyoto (WKY) rats served as controls. The effects of AZL-M on kidney injury, vascular endothelial and heart functions, lipid profile, and glucose tolerance were assessed., Results: AZL-M demonstrated anti-hypertensive effects along with markedly improved vascular endothelial function in SHROB. In these rats, AZL-M demonstrates strong kidney protective effects with lower albuminuria and nephrinuria along with reduced tubular cast formation and glomerular injury. AZL-M treatment also improved left ventricular heart function, attenuated development of left ventricular hypertrophy, and reduced cardiac fibrosis in SHROB., Conclusion: Overall, these findings demonstrate kidney and heart protective effects of AZL-M in SHROB, and these effects were associated with its ability to lower blood pressure and improve endothelial function.

Aims/hypothesis: Obesity and hypertension, known pro-inflammatory states, are identified determinants for increased retinal microvascular abnormalities. However, the molecular link between inflammation and microvascular degeneration remains elusive. Thioredoxin-interacting protein (TXNIP) is recognised as an activator of the NOD-like receptor pyrin domain containing-3 (NLRP3) inflammasome. This study aims to examine TXNIP expression and elucidate its role in endothelial inflammasome activation and retinal lesions., Methods: Spontaneously hypertensive (SHR) and control Wistar (W) rats were compared with groups fed a high-fat diet (HFD) (W+F and SHR+F) for 8-10 weeks., Results: Compared with W controls, HFD alone or in combination with hypertension significantly induced formation of acellular capillaries, a hallmark of retinal ischaemic lesions. These effects were accompanied by significant increases in lipid peroxidation, nitrotyrosine and expression of TXNIP, nuclear factor κB, TNF-α and IL-1β. HFD significantly increased interaction of TXNIP-NLRP3 and expression of cleaved caspase-1 and cleaved IL-1β. Immunolocalisation studies identified TXNIP expression within astrocytes and Müller cells surrounding retinal endothelial cells. To model HFD in vitro, human retinal endothelial (HRE) cells were stimulated with 400 μmol/l palmitate coupled to BSA (Pal-BSA). Pal-BSA triggered expression of TXNIP and its interaction with NLRP3, resulting in activation of caspase-1 and IL-1β in HRE cells. Silencing Txnip expression in HRE cells abolished Pal-BSA-mediated cleaved IL-1β release into medium and cell death, evident by decreases in cleaved caspase-3 expression and the proportion of live to dead cells., Conclusions/interpretation: These findings provide the first evidence for enhanced TXNIP expression in hypertension and HFD-induced retinal oxidative/inflammatory response and suggest that TXNIP is required for HFD-mediated activation of the NLRP3 inflammasome and the release of IL-1β in endothelial cells.

Cardiometabolic syndrome occurs with obesity and consists of pathophysiological factors that increase the risk for cardiovascular events. Soluble epoxide hydrolase inhibition (sEHi) is a novel therapeutic approach that exerts renal and cardiovascular protection. Although sEHi as a therapeutic approach is promising, it could be more effective for the treatment of cardiometabolic syndrome when combined with peroxisome proliferator activated receptor γ (PPARγ) agonists. We hypothesized that the PPARγ agonist, rosiglitazone in combination with a sEHi (tAUCB) will provide synergistic actions to decrease blood pressure, improve vascular function, decrease inflammation, and prevent renal damage in spontaneously hypertensive obese rats (SHROB). SHROB were treated with rosiglitazone, tAUCB or the combination of tAUCB and rosiglitazone for four-weeks and compared with spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats. Blood pressure increased in SHROB (164 ± 7 mmHg) and decreased 10 mmHg when treated with rosiglitazone, tAUCB, or tAUCB and rosiglitazone. Mesenteric artery dilation to the K(ATP) channel opener pinacidil was attenuated in SHROB (E(Max) = 77 ± 7%), compared with WKY (E(Max) = 115 ± 19) and SHR (E(Max) = 93 ± 12%). Vasodilation to pinacidil was improved by rosiglitazone (E(Max) = 92 ± 14%) but not tAUCB. Renal macrophage infiltration increased in SHROB and significantly decreased with rosiglitazone or tAUCB and rosiglitazone treatment. Albuminuria was increased in SHROB (90 ± 20 mg/d) and was significantly decreased by the combination of tAUCB and rosiglitazone (37 ± 9 mg/d). Glomerular injury in SHROB was also significantly decreased by tAUCB and rosiglitazone. These results indicate that even though sEHi or PPARγ agonist have benefits when used individually, the combination is more beneficial for the multidisease features in cardiometabolic syndrome.

Obesity and hypertension are the two major risk factors that contribute to the progression of end-stage renal disease. To examine whether hypertension further exacerbates oxidative stress and vascular dysfunction and inflammation in obese rats, four groups of male Sprague-Dawley rats were fed either a normal (7% fat) or high-fat (36% fat) diet for 6 weeks and osmotic pumps were implanted to deliver ANG (angiotensin II) or vehicle for an additional 4 weeks.Treatment with the high-fat diet did not alter ANG-induced hypertension compared with the normal diet (174 +/- 6 compared with 170 +/- 5 mmHg respectively). Treatment with the high-fat diet increased body weight gain and plasma leptin levels and induced insulin resistance in normotensive and ANG-induced hypertensive rats. Plasma TBARS (thiobarbituric acid-reacting substances), a measure of oxidative stress, were elevated in high-fat diet-fed rats compared with controls (11.2 +/-1 compared with 8.4 +/- nmol/ml respectively) and was increased further in ANG-induced hypertensive rats fed a high-fat diet (18.8 +/-2.2 nmol/ml). Urinary nitrite excretion was also decreased in rats fed a high-fat diet without or with ANG infusion compared with controls. Afferent arteriolar relaxation to acetylcholine was impaired in rats fed the high-fat diet without or with ANG infusion. Renal cortical TNF-alpha(tumour necrosis factor-alpha), COX-2(cyclo-oxygenase-2) and phospho-IKK (inhibitor of nuclear factor k B kinase) expression increased in high-fat diet-fed rats compared with normal diet-fed rats. The increases in phospho-IKK and COX-2 expression were elevated further in ANG-induced hypertensive rats fed the high-fat diet.These results suggest that ANG-induced hypertension exacerbates oxidative stress and renal inflammation without further impairment in vascular dysfunction in high-fat diet-induced obesity.

Obesity and hypertension are risk factors for the development of chronic kidney disease. The mechanisms by which elevated blood pressure and fatty acids lead to the development of renal injury are incompletely understood. Here, we investigated the contributions of cholesterol and oxidative stress to renal endothelial dysfunction and glomerular injury in a model of obesity and hypertension. Male Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) were fed a normal diet, a high-fat diet, a high-fat diet with tempol, or a high-fat diet with simvastatin for up to 10 wk. Blood pressure was not altered by a high-fat diet or treatments. After 3 wk, renal afferent dilatory responses to acetylcholine were impaired in WKY rats and SHR fed a high-fat diet. Tempol treatment prevented this vascular dysfunction in both strains; however, simvastatin treatment demonstrated greater beneficial effects in the SHR. Albuminuria was observed in the SHR and was exacerbated by a high-fat diet. Tempol and simvastatin treatment significantly ameliorated albuminuria in the SHR fed a high-fat diet. Ten weeks on a high-fat resulted in an increase in urinary 8-isoprostane in WKY rats and SHR, and tempol and simvastatin treatment prevented this increase, indicating a reduction in renal oxidative stress. Monocyte chemoattractant protein-1 (MCP-1) excretion was significantly elevated by a high-fat diet in both strains, and tempol prevented this increase. Interestingly, simvastatin treatment had no effect on MCP-1 levels. These data indicate that tempol and simvastatin treatment via a reduction in oxidative stress improve renal endothelial function and decrease glomerular injury in a model of obesity and hypertension.

1. In the present study, we determined the role of hypertension, oxidative stress and inflammation on kidney damage in a rodent model of obesity and diabetes. Hypertension was induced in male obese (db/db) mice and lean (db/m) mice by implantation of deoxycorticosterone acetate (DOCA) pellets and mice were allowed to drink water containing 1% salt. Mice were divided into six groups as follows: obese and lean control, obese and lean 1% salt (salt) and obese and lean DOCA plus 1% salt (DOCA-salt). 2. Blood pressure was significantly increased in lean and obese DOCA-salt groups relative to their respective controls; however, there was no difference in blood pressure between the lean and obese control and salt groups. Urinary 8-isoprostane was increased in obese control compared with lean control mice (1464 +/- 267 vs 493 +/- 53 pg/micromol creatinine, respectively) and this elevation was further increased in the obese DOCA-salt treated mice (2430 +/- 312 pg/micromol creatinine). Urinary monocyte chemoattractant protein-1 excretion and CD68-positive cells were also increased in both obese and lean DOCA-salt groups compared with their respective controls. Furthermore, DOCA-salt treatment increased collagen IV excretion in both obese and lean mice compared with controls, but there was no difference between obese and lean DOCA-salt groups. Urinary albumin excretion was significantly increased in the obese compared with the lean DOCA-salt mice (507 +/- 160 vs 202 +/- 48 microg/day, respectively). 3. These data suggest that obese DOCA-salt hypertensive mice exhibit greater renal injury than lean DOCA-salt hypertensive mice in a manner independent of blood pressure and that this renal injury is associated with obesity related pre-existing renal oxidative stress.

There is a growing body of evidence indicating that obesity and insulin resistance contribute to the progression of renal disease. A low-grade inflammatory response occurs in obesity and insulin resistance that causes an increase in macrophage infiltration into the adipose tissue and the kidney. The infiltration of macrophages gives rise to the production of an array of pro-inflammatory cytokines and downstream elements such as interleukin-6, NFkappaB, and cellular adhesion molecules. In addition, increased adiposity triggers the release of adipokines such as leptin that can cause vascular remodeling and disruption of renal function. Insulin resistance can alter the balance between endogenous vasoactive molecules such as nitric oxide and reactive oxygen species, resulting in altered renal endothelial function. Moreover, hyperinsulinemia has direct renal effects such as induced relaxation of the afferent arteriole, resulting in glomerular hyperfiltration and renal damage. High insulin levels also stimulate angiogenesis and mesangial cell proliferation, associated with the development of diabetic nephropathy. Current evidence indicates a direct link between increased adiposity and insulin resistance with renal vascular injury; however, further investigation into the renal microvascular effects of obesity and insulin resistance are required to better understand this disease process.

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)-alpha 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 increased by 54% and 18%, respectively, in fenofibrate-treated obese rats. In addition, acetylcholine (1 microM)-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 microM 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-alpha agonist fenofibrate increased renal CYP-derived eicosanoids and restored endothelial dilator function in obese Zucker rats.

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.

The present study tested the hypothesis that altered vascular regulation of arachidonic acid enzymes in obese Zucker rats contributes to renal damage. Protein expression of CYP450 (cytochrome P450) and COX (cyclo-oxygenase) enzymes in renal microvessels was studied in obese and lean Zucker rats at 20-21 weeks of age. Body weight and blood glucose averaged 649+/-13 g and 142+/-10 mg/dl in obese Zucker rats compared with 437+/-10 g and 111+/-5 mg/dl in age-matched lean Zucker rats. Renal microvascular CYP4A and COX-2 protein levels were increased and CYP2C protein levels decreased in obese Zucker rats. TX (thromboxane) B2 excretion was 2-fold higher and PG (prostaglandin) E2 excretion significantly lower in obese Zucker rats. Additional studies investigated the ability of the COX-2 inhibitor, rofecoxib, to slow the progression of renal injury in obese Zucker rats. Rofecoxib treatment decreased urinary PGF2alpha and 8-isoprostane levels in obese Zucker rats. Renal microvessel mRNA expression of pro-inflammatory chemokines was decreased in COX-2-inhibitor-treated obese Zucker rats. Urinary albumin excretion, an index of kidney damage, averaged 95+/-11 mg/day in vehicle-treated and 9+/-1 mg/day in rofecoxib-treated obese Zucker rats. Glomerulosclerosis, characterized by mesangial expansion, tubulo-interstitial fibrosis and extracellular matrix accumulation, was prominent in obese Zucker rats compared with a lack of damage in age-matched lean Zucker rats and rofecoxib-treated obese Zucker rats. These results suggest that altered vascular arachidonic acid enzymes contribute to the renal damage, and that COX-2 inhibition decreases glomerular injury in obese Zucker rats.

Objective: To determine cytochrome P450 (CYP450) and cyclooxygenase (COX) expression and metabolite regulation and renal damage in the early stages of obesity-related hypertension and diabetes., Research Methods and Procedures: Obese and lean Zucker rats at 10 to 12 weeks of age were studied. Blood pressure was measured in the conscious state using radiotelemetry. Blood glucose levels and body weight were measured periodically. Protein expression of CYP450 and COX enzymes in the kidney cortex, renal microvessels, and glomeruli was studied. The levels of CYP450 and COX metabolites in urine were measured, and urinary albumin excretion, an indicator of kidney damage, was measured., Results: Body weight and blood glucose averaged 432 +/- 20 grams and 105 +/- 5 mg/dl, respectively, in obese Zucker rats as compared with 320 +/- 8 grams and 91 +/- 5 mg/dl, respectively, in age-matched 10- to 12-week-old lean Zucker rats. Renal microvascular CYP4A and COX-2 protein levels were increased 2.3- and 17.0-fold, respectively, in obese Zucker rats. The protein expression of CYP2C11 and CYP2C23 was decreased 2.0-fold in renal microvessels isolated from obese Zucker rats when compared with lean Zucker rats. The urinary excretion rate of thromboxane B(2) was increased significantly in obese Zucker as compared with lean Zucker rats (22.0 +/- 1.8 vs. 13.4 +/- 1.0 ng/d). Urinary albumin excretion, an index of kidney damage, was increased in the obese Zucker rat at this early age., Discussion: These results suggest that increased CYP4A and COX-2 protein levels and decreased CYP2C11 and CYP2C23 protein levels occur in association with microalbuminuria during the onset of obesity-related hypertension and type 2 diabetes.

The incidence of essential hypertension increases with obesity; however, the mechanisms that link obesity with hypertension are unclear. Renal cytochrome P450 (CYP)-derived eicosanoids--hydroxyeicosatetraenoic acids (HETEs), epoxyeicosatrienoic acids (EETs), and dihydroxyeicosatrienoic acids (DHETs)--have been shown to play an important role in the regulation of renal function, vascular tone, and blood pressure. The objective of this study was to examine CYP-derived eicosanoid synthesis in the different renal zones (cortex, medulla, and papilla) of rats fed a high fat diet (HF). Male Sprague-Dawley rats were fed a HF diet or regular rat chow for 10 weeks. After 10 weeks, HF rats showed significantly higher systolic blood pressure, body weight, and fat:body weight ratio. The renal omega-hydroxylase activity was decreased by 46% in cortex, 43% in medulla, and 46% in papilla of HF rats. The renal epoxygenase activity was decreased by 46% in cortex, 31% in medulla, and 56% in papilla of HF rats. Interestingly, the changes in the rate of 20-HETE and EET formation in different renal zones were consistent with the levels of expression of CYP4A and CYP2C23 proteins, respectively. Furthermore, there were no significant changes in the synthesis of these metabolites in the renal microvessels. These results demonstrate that HF diet causes the downregulation of CYP4A and CYP2C23 in renal tubules, and these proteins are responsible for renal 20-HETE and EET formation. The reduction in the synthesis of these eicosanoids may play an important role in the regulation of renal function and blood pressure in obesity-induced hypertension.

Background and purposeDiabetic nephropathy is a common complications related to high morbidity and mortality in type 2 diabetes. We investigated the action of the dual modulator, PTUPB, a soluble epoxide hydrolase and cyclooxygenase-2 inhibitor against diabetic nephropathy.Experimental approachSixteen-week-old type 2 diabetic and proteinuric obese ZSF1 rats were treated with vehicle, PTUPB or enalapril for 8 weeks. Measurements were made of epoxyeicosatrienoic acids, thromboxane B2 (TBX2 ) and prostaglandin E2 (PGE2 ) in the kidney of these and lean ZSF1 rats along with their blood pressure.Key resultObese ZSF1 rats were diabetic with fivefold higher fasting blood glucose levels and markedly higher HbA1c levels compared with lean ZSF1 rats. PTUPB nor enalapril reduced fasting blood glucose or HbA1c but alleviated the development of diabetic nephropathy. In PTUPB-treated obese ZSF1 rats, glomerular nephrin expression was preserved. Enalapril also alleviated diabetic nephropathy. Diabetic renal injury in obese ZSF1 rats was accompanied by renal inflammation with six to sevenfold higher urinary MCP-1 (CCR2) level and renal infiltration of CD-68 positive cells. PTUPB and enalapril significantly reduced urinary MCP-1 levels and renal mRNA expression of cytokines. Both PTUPB and enalapril lowered blood pressure. PTUPB but not enalapril decreased hyperlipidaemia and liver injury in obese ZSF1 rats.Conclusion and implicationsOverall, the dual modulator PTUPB does not treat hyperglycaemia but can effectively alleviate hypertension, diabetic nephropathy, hyperlipidaemia and liver injury in type 2 diabetic rats. Our data further demonstrate that the renal actions of PTUPB are comparable with a current standard diabetic nephropathy treatment.

Obesity and hypertension have been identified as cardiovascular risk factors that contribute to the progression of end-stage renal disease. To examine the mechanisms by which a high-fat diet and hypertension contribute to endothelial dysfunction and renal injury, 8-week-old male spontaneously hypertensive rats and Wistar rats were fed a high-fat (36% fat) or a normal-fat (7% fat) diet for 10 weeks. The high-fat diet increased body weight in Wistar and hypertensive rats by 25 and 31 g, respectively. Systolic blood pressure was higher in the hypertensive rats compared with Wistar rats; however, blood pressure was unaltered by the high-fat diet. Afferent arteriole response to acetylcholine was impaired in the high-fat groups after just 3 weeks. Renal macrophage infiltration was increased in the hypertensive high-fat group compared with others, and monocyte chemoattractant protein-1 excretion was increased in both of the high-fat-fed groups. Renal PCR arrays displayed significant increases in 2 inflammatory genes in hypertensive rats fed a normal diet, 1 gene was increased in high-fat-fed Wistar rats, whereas 12 genes were increased in high-fat-fed hypertensive rats. Urinary albumin excretion was increased in the hypertensive rats compared with the Wistar rats, which was further exacerbated by the high-fat diet. Glomerular nephrin expression was reduced and desmin was increased by the high-fat diet in the hypertensive rats. Our results indicate that endothelial dysfunction precedes renal injury in normotensive and spontaneously hypertensive rats fed a high-fat diet, and hypertension with obesity induces a powerful inflammatory response and disruption of the renal filtration barrier. [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]

The number of obese people in the world is growing rapidly worldwide and has reached epidemic status. Obesity is often associated with the clustering of metabolic and cardiovascular risk factors that contribute to metabolic syndrome or syndrome X. Likewise, metabolic syndrome and its associated traits are major contributing factors to the increase in nephropathy and end stage renal disease. The specific factors that link the metabolic syndrome traits to the progression of nephropathy remain largely unexplored. Recent studies have demonstrated that an imbalance between cyclooxygenase-2 (COX-2) and cytochrome P450 (CYP450) arachidonic acid metabolizing enzymes in the kidney may contribute to the renal damage associated with obesity. Along these lines, COX-2 inhibition decreases renal cytokine levels and glomerular injury in obese rats. Peroxisome proliferators-activated receptors (PPARs) are transcription factors that also contribute to chronic kidney disease in obesity and metabolic syndrome. Intriguingly, interactions between PPARs and arachidonic acid metabolites could be key determinants of renal damage in metabolic syndrome patients. Therefore, there is a promising future for pharmacological agents that manipulate COX-2 and CYP450 metabolites and PPARs to treat obesity related nephropathy. [ABSTRACT FROM AUTHOR]

Studies suggest that inflammatory cytokines play an important role in the progression of renal dysfunction in obesity and hypertension. Thus, we hypothesize that NFκB signaling activation contributes to insulin resistance and endothelial dysfunction in angiotensin II (ANG) infused rats fed a high fat diet. Two groups of male rats were fed either normal or high fat diet for 6 weeks and osmotic minipumps were implanted to deliver ANG for 4 more weeks. High fat diet treatment did not significantly enhance the increase in blood pressure in ANG infused rats (174±6 vs. 170±5 mmHg), however, body weight gain was higher in rats fed a high fat diet compared with those on a normal diet. Plasma insulin and leptin levels were significantly elevated in ANG/high fat rats compared to ANG/normal (6.8±0.9 vs. 4.3±4 µg/l & 11.5±1 vs. 2.3±0.4 µg/l, respectively). Renal afferent arteriolar dilation to acetylcholine was impaired in ANG hypertension and further impaired in ANG rats fed a high fat diet. Renal cortical Cyp2c23 protein expression decreased in ANG/high fat rats compared to ANG/normal. Renal cortical NFκB activity and phospho-IKKα/β protein expression also increased in ANG rat fed a high fat diet compared to those fed a normal diet. These data suggest that activation of NFκB signaling cascade and down-regulation of Cyp2c23 may contribute to endothelial dysfunction and insulin resistance in ANG hypertensive rats fed a high fat diet. [ABSTRACT FROM AUTHOR]

Obesity and hypertension are cardiovascular risk factors that contribute to the progression of end-stage renal disease. The aim of this study was to elucidate events and mechanisms involved in renal injury in an animal model of obesity and hypertension. Male 8 week-old SHR and WKY rats were fed high fat (HF, 36%) or normal fat diet (NF, 7%) for 10 weeks (n=5 per group). Ten weeks HF increased body weight gain but did not alter blood pressure in SHR or WKY. In euglycemic clamp experiments in both strains, glucose infusion rates of 35 to 40 mg/kg/min were required to maintain blood glucose at 125 mg/dL, indicating insulin sensitivity. Plasma leptin levels were increased by HF from 4.8 ± 0.6 and 4.5 ± 0.9 ng/ml to 13.4 ± 0.7 and 8.2 ± 0.7 ng/ml in WKY and SHR respectively (P<0.05). Albumin excretion, a marker for renal injury, increased to 867 ± 125 in HF SHR compared to 519 ± 63 µg/day in NF SHR (P<0.05). WKY excreted lower levels of albumin which was unaltered by diet. Urinary MCP-1 reached 38 ± 10 and 33 ± 7 ng/day in the HF WKY and SHR compared to 13 ± 4 and 14 ± 4 ng/day in the NF WKY and SHR respectively (P<0.05). Plasma 8-Isoprostane increased with HF from 1008 to 1468 pg/day in WKY and 810 to 952 pg/day in SHR. Our results indicate that ten weeks HF diet exacerbates renal injury in SHR in the absence of changes in blood pressure or insulin sensitivity. We demonstrate that hyperleptinemia, oxidative stress and inflammation may contribute to the renal injury. [ABSTRACT FROM AUTHOR]

Mice deficient in the leptin receptor develop obesity, insulin-resistance, and progress to nephropathy similar to that seen in human diabetes type II with interstitial macrophage infiltration and glomerulosclerosis. Adipocyte secreted cytokines are thought to mediate this progression by altering insulin sensitivity. We hypothesized that increased renal cytokines and inflammatory mediators contribute to renal complications in obesity and diabetes. Thus we profiled renal cortical gene expression with pathway targeted real-time RT-PCR arrays in male 22-week-old obese and lean mice (n=6 each) with body weights of 54.6±0.6 g and 30.9±0.7 g, respectively. Obese mice exhibited albuminuria of 204±57 µg/day vs. 51±9 µg/day in lean and had increased plasma monocyte chemotactic protein-1 (MCP-1) of 89.0±30.7 pg/ml vs. 35.0±7.5 pg/ml in lean. Cytokines that increase insulin resistance were upregulated: interleukin-6 (43-fold), resistin (17-fold), and tumor necrosis factor-a (3.7-fold). Obese mice also had upregulated message for macrophage chemotactic and adhesion molecules such as MCP-1 (3-fold), E-selectin (17-fold), P-selectin (9-fold), vascular cell adhesion molecule-1 (2.5-fold), and intercellular adhesion molecule-1 (2.3-fold). These data suggest that upregulated renal cytokines, chemokines, and adhesion molecules contribute to obesity induced insulin-resistance and renal injury. [ABSTRACT FROM AUTHOR]