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Papers by Nitin Puri

Research paper thumbnail of Protective Effects of HPP593, a Novel PPAR Delta Agonist, in the Goldblatt Model of Renal Hypertension

Research paper thumbnail of Fructose Mediated Non-Alcoholic Fatty Liver Is Attenuated by HO-1-SIRT1 Module in Murine Hepatocytes and Mice Fed a High Fructose Diet

PloS one, 2015

Oxidative stress underlies the etiopathogenesis of nonalcoholic fatty liver disease (NAFLD), obes... more Oxidative stress underlies the etiopathogenesis of nonalcoholic fatty liver disease (NAFLD), obesity and cardiovascular disease (CVD). Heme Oxygenase-1 (HO-1) is a potent endogenous antioxidant gene that plays a key role in decreasing oxidative stress. Sirtuin1 (SIRT1) belongs to the family of NAD-dependent de-acyetylases and is modulated by cellular redox. We hypothesize that fructose-induced obesity creates an inflammatory and oxidative environment conducive to the development of NAFLD and metabolic syndrome. The aim of this study is to determine whether HO-1 acts through SIRT1 to form a functional module within hepatocytes to attenuate steatohepatitis, hepatic fibrosis and cardiovascular dysfunction. We examined the effect of fructose, on hepatocyte lipid accumulation and fibrosis in murine hepatocytes and in mice fed a high fructose diet in the presence and absence of CoPP, an inducer of HO-1, and SnMP, an inhibitor of HO activity. Fructose increased oxidative stress markers and...

Research paper thumbnail of Allele-Specific regulation of the human angiotensinogen gene by dexamethasone: implications for human hypertension

Journal of the American Society of Hypertension, 2015

Research paper thumbnail of Peroxisome Proliferator-Activated Receptor δ Agonist, HPP593, Prevents Renal Necrosis under Chronic Ischemia

Research paper thumbnail of Reciprocal Effects of Oxidative Stress on Heme Oxygenase Expression and Activity Contributes to Reno-Vascular Abnormalities in EC-SOD Knockout Mice

International journal of hypertension, 2012

Heme oxygenase (HO) system is one of the key regulators of cellular redox homeostasis which respo... more Heme oxygenase (HO) system is one of the key regulators of cellular redox homeostasis which responds to oxidative stress (ROS) via HO-1 induction. However, recent reports have suggested an inhibitory effect of ROS on HO activity. In light of these conflicting reports, this study was designed to evaluate effects of chronic oxidative stress on HO system and its role in contributing towards patho-physiological abnormalities observed in extracellular superoxide dismutase (EC-SOD, SOD3) KO animals. Experiments were performed in WT and EC-SOD((-/-)) mice treated with and without HO inducer, cobalt protoporphyrin (CoPP). EC-SOD((-/-)) mice exhibited oxidative stress, renal histopathological abnormalities, elevated blood pressure, impaired endothelial function, reduced p-eNOS, p-AKT and increased HO-1 expression; although, HO activity was significantly (P < 0.05) attenuated along with attenuation of serum adiponectin and vascular epoxide levels (P < 0.05). CoPP, in EC-SOD((-/-)) mice,...

Research paper thumbnail of Cobalt-protoporphyrin improves heart function by blunting oxidative stress and restoring NO synthase equilibrium in an animal model of experimental diabetes

Myocardial dysfunction and coronary macro/microvascular alterations are the hallmarks of diabetic... more Myocardial dysfunction and coronary macro/microvascular alterations are the hallmarks of diabetic cardiomyopathy and are ascribed to increased oxidative stress and altered nitric oxide synthase (NOS) activity. We hypothesize that pre-treatment by cobalt-protoporphyrin IX (CoPP) ameliorates both myocardial function and coronary circulation in streptozotocin (STZ)-induced diabetic rats. Isolated hearts from diabetic rats in Langendorff configuration displayed lower left ventricular function and higher coronary resistance (CR) compared to hearts from control animals. CoPP treatment of diabetic animals (0.3 mg/100 g body weight i.p., once a week for 3 weeks) significantly increased all the contractile/relaxation indexes (p < 0.01), while decreasing CR (p < 0.01). CoPP enhanced HO-1 protein levels and reduced oxidative stress in diabetic animals, as indicated by the significant (p < 0.05) decrease in heart % GSSG, O − 2 , and malondialdehyde (MDA) levels. CoPP increased adiponectin levels and phosphorylation of AKT and AMPK and reversed the eNOS/iNOS expression imbalance observed in the untreated diabetic heart. Furthermore, after CoPP treatment, a rise in malonyl-CoA as well as a decrease in acetyl-CoA was observed in diabetic hearts. In this experimental model of diabetic cardiomyopathy, CoPP treatment improved both cardiac function and coronary flow by blunting oxidative stress, restoring eNOS/iNOS expression balance and increasing HO-1 levels, thereby favoring improvement in both endothelial function and insulin sensitivity.

Research paper thumbnail of Increased HO-1 levels ameliorate fatty liver development through a reduction of heme and recruitment of FGF21

Obesity, 2013

Objective-Obese leptin deficient (ob/ob) mice are a model of adiposity that displays increased le... more Objective-Obese leptin deficient (ob/ob) mice are a model of adiposity that displays increased levels of fat, glucose and liver lipids. Our hypothesis is that HO-1 overexpression ameliorates fatty liver development.

Research paper thumbnail of Variable Transcriptional Regulation of the Human Aldosterone Synthase Gene Causes Salt-Dependent High Blood Pressure in Transgenic Mice

Circulation. Cardiovascular genetics, Jan 12, 2014

Background-Aldosterone, synthesized in the adrenal cortex by the enzyme CYP11B2, induces positive... more Background-Aldosterone, synthesized in the adrenal cortex by the enzyme CYP11B2, induces positive sodium balance and predisposes to hypertension. Various investigators, using genomic DNA analyses, have linked -344T polymorphism in the human CYP11B2 (hCYP11B2) gene to human hypertension. hCYP11B2 gene promoter has 3 single-nucleotide polymorphisms in linkage disequilibrium: T/A at -663, T/C at -470, and C/T at -344. Variants ACT occur together and form the haplotype-I (Hap-I), whereas variants TTC constitute Hap-II. We hypothesize that these single-nucleotide polymorphisms, when present together, will lead to haplotype-dependent differences in the transcriptional regulation of the hCYP11B2 gene and affect blood pressure regulation. Methods and Results-We evaluated differences in tissue expression in vivo and consequential effects on blood pressure stemming from the 2 haplotypes. Novel transgenic mice with the hCYP11B2 gene, targeted to the mouse HPRT locus, with either Hap-II or Hap-I variant are used in this study. Our results show increased adrenal and renal expression of hCYP11B2 in transgenic mice with Hap-I when compared with mice with Hap-II. Importantly, we observed increased baseline blood pressure in Hap-I transgenic mice, an effect accentuated by a high-salt diet. Pathophysiological effects of elevated aldosterone were corroborated by our results showing upregulation of proinflammatory markers in renal tissues from the transgenic mice with Hap-I. Conclusions-These findings characterize the haplotype-dependent regulation of the hCYP11B2 gene where -344T serves as a reporter polymorphism and show that Hap-I leads to increased expression of hCYP11B2, with permissive effects on blood pressure and inflammatory milieu.

Research paper thumbnail of Dexamethasone Promotes Hypertension By Allele-Specific Regulation Of The Human Angiotensinogen Gene

Journal of Biological Chemistry, 2015

The human angiotensinogen gene (hAGT) gene has polymorphisms in its 2.5Kb promoter that form two ... more The human angiotensinogen gene (hAGT) gene has polymorphisms in its 2.5Kb promoter that form two haplotype (Hap) blocks: -6A/G (-1670A/G, -1562C/T, -1561T/C) and -217A/G (-532T/C, -793A/G, -1074T/C, and -1178G/A). Hap -6A/-217A is associated with human hypertension whereas Hap -6G/-217G reduce cardiovascular risk. Hap -6A/-217A has increased promoter activity with enhanced transcription factor binding including, the glucocorticoid receptor (GR). Glucocorticoid therapy frequently causes hypertension, the mechanisms for which are incompletely understood. We have engineered double transgenic (TG) mice containing human renin gene with either Hap of the hAGT gene and examined the physiological significance of glucocorticoid-mediated allele-specific regulation of the hAGT gene. We have also studied consequential effects on the renin angiotensin system (RAS) and blood pressure. TG mice with Hap -6A and -6G were treated with and without low dose of a GR agonist, dexamethasone (DEX, 2.5μg/mL), for 72 hours. We find greater chromatin-GR binding with increased GR agonist-induced hAGT expression in liver and renal tissues of Hap -6A mice. Additionally, DEX treatment increased circulating hAGT and angiotensin II levels in Hap -6A mice, as compared to -6G mice. Importantly, GR agonist significantly increased blood pressure and redox markers in TG mice with Hap-6A of the hAGT gene. Taken together, our results show, for the first time, that glucocorticoids affect hAGT expression in a haplotype-dependent fashion with SNPs in Hap -6A favoring agonist-induced GR binding. This leads to increased expression of the hAGT, up-regulation of the RAS, and increased blood pressure and oxidative stress in Hap -6A mice.

Research paper thumbnail of Increased heme-oxygenase 1 expression in mesenchymal stem cell-derived adipocytes decreases differentiation and lipid accumulation via upregulation of the canonical Wnt signaling cascade

Stem Cell Research & Therapy, 2013

Introduction: Heme oxygenase (HO), a major cytoprotective enzyme, attenuates oxidative stress and... more Introduction: Heme oxygenase (HO), a major cytoprotective enzyme, attenuates oxidative stress and obesity. The canonical Wnt signaling cascade plays a pivotal role in the regulation of adipogenesis. The present study examined the interplay between HO-1and the Wnt canonical pathway in the modulation of adipogenesis in mesenchymal stem cell (MSC)-derived adipocytes. Methods: To verify the role of HO-1 in generating small healthy adipocytes, cobalt protoporphyrin (CoPP), inducer of HO-1, was used during adipocyte differentiation. Lipid accumulation was measured by Oil red O staining and lipid droplet size was measured by BODIPY staining.

Research paper thumbnail of Apo A1 Mimetic Rescues the Diabetic Phenotype of HO-2 Knockout Mice via an Increase in HO-1 Adiponectin and LKBI Signaling Pathway

International journal of hypertension, 2012

Insulin resistance, with adipose tissue dysfunction, is one of the hallmarks of metabolic syndrom... more Insulin resistance, with adipose tissue dysfunction, is one of the hallmarks of metabolic syndrome. We have reported a metabolic syndrome-like phenotype in heme oxygenase (HO)-2 knockout mice, which presented with concurrent HO-1 deficiency and were amenable to rescue by an EET analog. Apo A-I mimetic peptides, such as L-4F, have been shown to induce HO-1 expression and decrease oxidative stress and adiposity. In this study we aimed to characterize alleviatory effects of HO-1 induction (if any) on metabolic imbalance observed in HO-2 KO mice. In this regard, HO-2((-/-)) mice were injected with 2 mg/kg/day L-4F, or vehicle, i.p., for 6 weeks. As before, compared to WT animals, the HO-2 null mice were obese, displayed insulin resistance, and had elevated blood pressure. These changes were accompanied by enhanced tissue (hepatic) oxidative stress along with attenuation of HO-1 expression and activity and reduced adiponectin, pAMPK, and LKB1 expression. Treatment with L-4F restored HO-1...

Research paper thumbnail of EET agonist prevents adiposity and vascular dysfunction in rats fed a high fat diet via a decrease in Bach 1 and an increase in HO-1 levels

Prostaglandins & Other Lipid Mediators, 2012

Recent reports have shown interplay between EETs (epoxides) and the heme oxygenase (HO) system in... more Recent reports have shown interplay between EETs (epoxides) and the heme oxygenase (HO) system in attenuating adipogenesis in cell culture models; prompting an examination of the effectiveness of EET agonist on obesity and associated cardio-metabolic dysfunction. Patho-physiological effects of an EET agonist (NUDSA) were contrasted in the absence and in the presence of stannous mesoporphyrin (an HO inhibitor) in SD rats fed a high fat (58%, HF) for 16 weeks. Animals on HF diet exhibited enhanced oxidative stress, increased levels of inflammatory cytokines and decreased levels of adiponectin along with reduced vascular and adipose tissue levels of EETs, HO-1; as compared to control rats (11% dietary fat). Treatment with NUDSA not only reversed serum adiponectin and vascular and adipose tissue levels of EETs and HO-1, but also, decreased blood pressure, subcutaneous and visceral fat content and serum TNFα and IL-6 levels in rats on HF diet. Aortic endothelial function, peNOS expression and adipose tissue markers of energy homeostasis i.e. pAMPK, Sirt1 and FAS, impaired in rats fed a HF diet, were restored in animals treated with this EET agonist. That NUDSA enhanced HO-1 expression, was accompanied by increase in p-GSK-3β and pAKT levels along with attenuation of adipose tissue levels of Bach 1--the transcriptional suppresser of HO-1 expression. Prevention of these beneficial effects of NUDSA, in animals on HF diet and concurrently exposed to NUDSA and SnMP, supports the role of EET-HO interaction in mediating such effects. Taken together, our findings suggest that the EETs stimulate HO-1 expression via suppression of Bach 1 and interplay of these two systems affords vascular and metabolic protection in diet induced obesity.

Research paper thumbnail of High-Fat Diet Exacerbates Renal Dysfunction in SHR: Reversal by Induction of HO-1–Adiponectin Axis

Research paper thumbnail of Heme Oxygenase-Mediated Increases in Adiponectin Decrease Fat Content and Inflammatory Cytokines Tumor Necrosis Factor-  and Interleukin-6 in Zucker Rats and Reduce Adipogenesis in Human Mesenchymal Stem Cells

Journal of Pharmacology and Experimental Therapeutics, 2008

Adiponectin, an abundant adipocyte-derived plasma protein that modulates vascular function in typ... more Adiponectin, an abundant adipocyte-derived plasma protein that modulates vascular function in type 2 diabetes, has been shown to provide cytoprotection to both pancreatic and vascular systems in diabetes. Therefore, we examined whether up-regulation of heme oxygenase (HO)-1 ameliorates the levels of inflammatory cytokines and influences serum adiponectin in Zucker fat (ZF) rats. ZF rats displayed a decrease in both HO activity and HO-1 and HO-2 protein levels and an increase in tumor necrosis factor (TNF)-␣ and interleukin (IL)-6 compared with Zucker lean (ZL) rats. Treatment of ZF animals with 2 mg/kg cobalt protoporphyrin IX (CoPP) increased protein levels of HO-1 and HO activity, but HO-2 was unaffected. The increase in HO-1 was associated with a decrease in superoxide levels (p Ͻ 0.05) and an increase in plasma adiponectin (p Ͻ 0.005), compared with untreated ZF rats. CoPP treatment de-This work was supported by National Institutes of Health Grants DK068134, HL55601, and HL34300.

Research paper thumbnail of Heme Oxygenase-2 Deletion Causes Endothelial Cell Activation Marked by Oxidative Stress, Inflammation, and Angiogenesis

Journal of Pharmacology and Experimental Therapeutics, 2009

In previous studies, we have shown that heme oxygenase (HO)-2 null [HO-2(Ϫ/Ϫ)] mice exhibit a fau... more In previous studies, we have shown that heme oxygenase (HO)-2 null [HO-2(Ϫ/Ϫ)] mice exhibit a faulty response to injury; chronic inflammation and massive neovascularization replaced resolution of inflammation and tissue repair. Endothelial cells play an active and essential role in the control of inflammation and the process of angiogenesis. We examined whether HO-2 deletion affects endothelial cell function. Under basal conditions, HO-2(Ϫ/Ϫ) aortic endothelial cells (mAEC) showed a 3-fold higher expression of vascular endothelial growth factor receptor 1 and a marked angiogenic response compared with wild-type (WT) cells. Compared with WT cells, HO-2(Ϫ/Ϫ) mAEC showed a 2-fold reduction in HO activity and marked increases in levels of gp91 phox /NADPH oxidase isoform, superoxide, nuclear factor B activation, and expression of inflammatory cytokines, including interleukin (IL)-1␣ and IL-6. HO-2 deletion transforms endothelial cells from a "normal" to an "activated" phenotype characterized by increases in inflammatory, oxidative, and angiogenic factors. This switch may be the result of reduced HO activity and the associated reduction in the cytoprotective HO products, carbon monoxide and biliverdin/bilirubin, because addition of biliverdin to HO-2(Ϫ/Ϫ) cells attenuated angiogenesis and reduced superoxide production. This transformation underscores the importance of HO-2 in the regulation of endothelial cell homeostasis. Article, publication date, and citation information can be found at

Research paper thumbnail of Cyclooxygenase-2 dependent metabolism of 20-HETE increases adiposity and adipocyte enlargement in mesenchymal stem cell-derived adipocytes

The Journal of Lipid Research, 2013

20-Hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE), a product of the cytochrome P450 (CYP)-cata... more 20-Hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE), a product of the cytochrome P450 (CYP)-catalyzed ω-hydroxylation of arachidonic acid, induces oxidative stress and, in clinical studies, is associated with increased body mass index (BMI) and the metabolic syndrome. This study was designed to examine the effects of exogenous 20-HETE on mesenchymal stem cell (MSC)-derived adipocytes. The expression levels of CYP4A11 and CYP4F2 (major 20-HETE synthases in humans) in MSCs decreased during adipocyte differentiation; however, exogenous administration of 20-HETE (0.1-1 μM) increased adipogenesis in a dose-dependent manner in these cells (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05). The inability of a 20-HETE analog to reproduce these effects suggested the involvement of a metabolic product of 20-HETE in mediating its pro-adipogenic effects. A cyclooxygenase (COX)-1 selective inhibitor enhanced, whereas a COX-2 selective or a dual COX-1/2 inhibitor attenuated adipogenesis induced by 20-HETE. The COX-derived metabolite of 20-HETE, 20-OH-PGE₂, enhanced adipogenesis and lipid accumulation in MSCs. The pro-adipogenic effects of 20-HETE and 20-OH-PGE₂ resulted in the increased expression of the adipogenic regulators PPARγ and β-catenin in MSC-derived adipocytes. Taken together we show for the first time that 20-HETE-derived COX-2-dependent 20-OH-PGE₂ enhances mature inflamed adipocyte hypertrophy in MSC undergoing adipogenic differentiation.

Research paper thumbnail of The L-4F mimetic peptide prevents insulin resistance through increased levels of HO-1, pAMPK, and pAKT in obese mice

The Journal of Lipid Research, 2009

We investigated the mechanisms by which L-4F, an apolipoprotein A-1 mimetic peptide, reduces obes... more We investigated the mechanisms by which L-4F, an apolipoprotein A-1 mimetic peptide, reduces obesity and diabetes in obese (ob) diabetic mice. We hypothesized that L-4F reduces vascular dysfunction via an increase in pAMPK and pAKT in both ob diabetic mice and human stem cells. Mice, ob and lean, were fed a normal diet until 9 weeks of age, when all ob mice had established diabetes treated with L-4F. Food intake, blood insulin, glucose levels, adipocyte stem cells and pAMPK, pAKT, SREBP-1 and insulin receptors were determined.

Research paper thumbnail of Heme induced oxidative stress attenuates sirtuin1 and enhances adipogenesis in mesenchymal stem cells and mouse pre-adipocytes

Journal of Cellular Biochemistry, 2012

Patho-physiological conditions with high oxidative stress, such as conditions associated with inc... more Patho-physiological conditions with high oxidative stress, such as conditions associated with increased denatured heme-proteins, are associated with enhanced adipogenic response. This effect predominantly manifests as adipocyte hypertrophy characterized by dysfunctional, proinflammatory adipocytes exhibiting reduced expression of anti-inflammatory hormone, adiponectin. To understand how increased levels of cellular heme, a pro-oxidant molecule, modulates adipogenesis; the following study was designed to evaluate effects of heme on adipogenesis in human mesenchymal stem cells (hMSCs) and mouse pre-adipocytes (3T3L1). Experiments were conducted in the absence and in the presence of a superoxide dismutase mimetic (tempol, 100μM). Heme (10μM) increased (p<0.05) adipogenesis in hMSCs and mouse pre-adipocytes, where tempol alone (100μmol/l) attenuated adipogenesis in these cells (p<0.05). Tempol also reversed heme-induced increase in adipogenesis in both hMSCs and mouse preadipocytes (p<0.05). In addition, heme exposed 3T3L1 exhibited reduced (p<0.05) expression of transcriptional regulator-sirtuin 1 (Sirt1), along with, increased (p<0.05) expression of adipogenic markers PPARγ, C/EBPα and aP2. These effects of heme were rescued (p<0.05) in cells concurrently treated with heme and tempol (p<0.05) and prevented in cells over-expressing Sirt1. Taken together, our results indicate that heme-induced oxidative stress inhibits Sirt1, thus uninhibiting adipogenic regulators such as PPARγ and C/EBPα; which in turn induce increased adipogenesis along with adipocyte hypertrophy in pre-adipocytes. Anti-oxidant induced offsetting of these effects of heme supports the role of heme-dependent oxidative stress in mediating such events.

Research paper thumbnail of A Haplotype of Angiotensin Receptor Type 1 Associated with Human Hypertension Increases Blood Pressure in Transgenic Mice

Journal of Biological Chemistry, 2013

Background: AT 1 R activation induces oxidative stress, promotes inflammation, and increases bloo... more Background: AT 1 R activation induces oxidative stress, promotes inflammation, and increases blood pressure. Results: SNPs in AT 1 R-promoter occur in linkage disequilibrium forming two haplotypes. Transgenic mice with haplotype-I have USF-2-dependent AT 1 R over-expression, increased oxidative stress and blood pressure. Conclusion: Haplotype-I leads to enhanced expression and patho-physiological effects of AT 1 R. Significance: Polymorphisms in AT 1 R provide for genetic predisposition to hypertension.

Research paper thumbnail of HO-1 Induction Improves The Type-1 Cardiorenal Syndrome in Mice With Impaired Angiotensin II-Induced Lymphocyte Activation

Hypertension, 2013

Type-1 cardiorenal syndrome, characterized by acute kidney dysfunction secondary to cardiac failu... more Type-1 cardiorenal syndrome, characterized by acute kidney dysfunction secondary to cardiac failure and renal arteriolar vasoconstriction, is mediated by the renin-angiotensin-aldosterone axis and sympathetic nervous system activation. Previous reports indicate that angiotensin II modulates immune function and causes recruitment and activation of T-lymphocytes. The goal of this study was to evaluate the effects of postischemic heart failure on renal morphology and circulation and the beneficial effects of heme oxygenase-1 (HO-1) induction in T-lymphocyte-suppressed severe combined immune deficiency (SCID) mice. Mice were divided into 4 groups: sham, myocardial infarction (MI), MI treated with an HO-1 inducer, cobalt protoporphyrin, and with or without stannous mesoporphyrin, an inhibitor of HO activity. Heart and kidney function were studied 30 days after surgery. Fractional area change was reduced 30 days after surgery in both the C57 and SCID MI-groups as compared with their respective controls (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01). Renal Pulsatility Index and renal injury were increased in C57 and SCID MI-groups compared with the sham group. HO-1 induction improved renal vasoconstriction as well as ameliorated renal injury in both the SCID and C57 MI-groups (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01). However, improvement was more evident in SCID mice. In addition, our results showed that plasma creatinine, angiotensin II, and renin were significantly increased in the C57 and SCID MI-groups as compared with their respective controls. HO-1 induction decreased these parameters in both MI groups. Stannous mesoporphyrin reversed the beneficial effect of cobalt protoporphyrin in both mouse strains. The study demonstrates that T-lymphocyte suppression facilitated the HO-1-dependent improvement in the attenuation of type-1 cardiorenal syndrome.

Research paper thumbnail of Protective Effects of HPP593, a Novel PPAR Delta Agonist, in the Goldblatt Model of Renal Hypertension

Research paper thumbnail of Fructose Mediated Non-Alcoholic Fatty Liver Is Attenuated by HO-1-SIRT1 Module in Murine Hepatocytes and Mice Fed a High Fructose Diet

PloS one, 2015

Oxidative stress underlies the etiopathogenesis of nonalcoholic fatty liver disease (NAFLD), obes... more Oxidative stress underlies the etiopathogenesis of nonalcoholic fatty liver disease (NAFLD), obesity and cardiovascular disease (CVD). Heme Oxygenase-1 (HO-1) is a potent endogenous antioxidant gene that plays a key role in decreasing oxidative stress. Sirtuin1 (SIRT1) belongs to the family of NAD-dependent de-acyetylases and is modulated by cellular redox. We hypothesize that fructose-induced obesity creates an inflammatory and oxidative environment conducive to the development of NAFLD and metabolic syndrome. The aim of this study is to determine whether HO-1 acts through SIRT1 to form a functional module within hepatocytes to attenuate steatohepatitis, hepatic fibrosis and cardiovascular dysfunction. We examined the effect of fructose, on hepatocyte lipid accumulation and fibrosis in murine hepatocytes and in mice fed a high fructose diet in the presence and absence of CoPP, an inducer of HO-1, and SnMP, an inhibitor of HO activity. Fructose increased oxidative stress markers and...

Research paper thumbnail of Allele-Specific regulation of the human angiotensinogen gene by dexamethasone: implications for human hypertension

Journal of the American Society of Hypertension, 2015

Research paper thumbnail of Peroxisome Proliferator-Activated Receptor δ Agonist, HPP593, Prevents Renal Necrosis under Chronic Ischemia

Research paper thumbnail of Reciprocal Effects of Oxidative Stress on Heme Oxygenase Expression and Activity Contributes to Reno-Vascular Abnormalities in EC-SOD Knockout Mice

International journal of hypertension, 2012

Heme oxygenase (HO) system is one of the key regulators of cellular redox homeostasis which respo... more Heme oxygenase (HO) system is one of the key regulators of cellular redox homeostasis which responds to oxidative stress (ROS) via HO-1 induction. However, recent reports have suggested an inhibitory effect of ROS on HO activity. In light of these conflicting reports, this study was designed to evaluate effects of chronic oxidative stress on HO system and its role in contributing towards patho-physiological abnormalities observed in extracellular superoxide dismutase (EC-SOD, SOD3) KO animals. Experiments were performed in WT and EC-SOD((-/-)) mice treated with and without HO inducer, cobalt protoporphyrin (CoPP). EC-SOD((-/-)) mice exhibited oxidative stress, renal histopathological abnormalities, elevated blood pressure, impaired endothelial function, reduced p-eNOS, p-AKT and increased HO-1 expression; although, HO activity was significantly (P < 0.05) attenuated along with attenuation of serum adiponectin and vascular epoxide levels (P < 0.05). CoPP, in EC-SOD((-/-)) mice,...

Research paper thumbnail of Cobalt-protoporphyrin improves heart function by blunting oxidative stress and restoring NO synthase equilibrium in an animal model of experimental diabetes

Myocardial dysfunction and coronary macro/microvascular alterations are the hallmarks of diabetic... more Myocardial dysfunction and coronary macro/microvascular alterations are the hallmarks of diabetic cardiomyopathy and are ascribed to increased oxidative stress and altered nitric oxide synthase (NOS) activity. We hypothesize that pre-treatment by cobalt-protoporphyrin IX (CoPP) ameliorates both myocardial function and coronary circulation in streptozotocin (STZ)-induced diabetic rats. Isolated hearts from diabetic rats in Langendorff configuration displayed lower left ventricular function and higher coronary resistance (CR) compared to hearts from control animals. CoPP treatment of diabetic animals (0.3 mg/100 g body weight i.p., once a week for 3 weeks) significantly increased all the contractile/relaxation indexes (p < 0.01), while decreasing CR (p < 0.01). CoPP enhanced HO-1 protein levels and reduced oxidative stress in diabetic animals, as indicated by the significant (p < 0.05) decrease in heart % GSSG, O − 2 , and malondialdehyde (MDA) levels. CoPP increased adiponectin levels and phosphorylation of AKT and AMPK and reversed the eNOS/iNOS expression imbalance observed in the untreated diabetic heart. Furthermore, after CoPP treatment, a rise in malonyl-CoA as well as a decrease in acetyl-CoA was observed in diabetic hearts. In this experimental model of diabetic cardiomyopathy, CoPP treatment improved both cardiac function and coronary flow by blunting oxidative stress, restoring eNOS/iNOS expression balance and increasing HO-1 levels, thereby favoring improvement in both endothelial function and insulin sensitivity.

Research paper thumbnail of Increased HO-1 levels ameliorate fatty liver development through a reduction of heme and recruitment of FGF21

Obesity, 2013

Objective-Obese leptin deficient (ob/ob) mice are a model of adiposity that displays increased le... more Objective-Obese leptin deficient (ob/ob) mice are a model of adiposity that displays increased levels of fat, glucose and liver lipids. Our hypothesis is that HO-1 overexpression ameliorates fatty liver development.

Research paper thumbnail of Variable Transcriptional Regulation of the Human Aldosterone Synthase Gene Causes Salt-Dependent High Blood Pressure in Transgenic Mice

Circulation. Cardiovascular genetics, Jan 12, 2014

Background-Aldosterone, synthesized in the adrenal cortex by the enzyme CYP11B2, induces positive... more Background-Aldosterone, synthesized in the adrenal cortex by the enzyme CYP11B2, induces positive sodium balance and predisposes to hypertension. Various investigators, using genomic DNA analyses, have linked -344T polymorphism in the human CYP11B2 (hCYP11B2) gene to human hypertension. hCYP11B2 gene promoter has 3 single-nucleotide polymorphisms in linkage disequilibrium: T/A at -663, T/C at -470, and C/T at -344. Variants ACT occur together and form the haplotype-I (Hap-I), whereas variants TTC constitute Hap-II. We hypothesize that these single-nucleotide polymorphisms, when present together, will lead to haplotype-dependent differences in the transcriptional regulation of the hCYP11B2 gene and affect blood pressure regulation. Methods and Results-We evaluated differences in tissue expression in vivo and consequential effects on blood pressure stemming from the 2 haplotypes. Novel transgenic mice with the hCYP11B2 gene, targeted to the mouse HPRT locus, with either Hap-II or Hap-I variant are used in this study. Our results show increased adrenal and renal expression of hCYP11B2 in transgenic mice with Hap-I when compared with mice with Hap-II. Importantly, we observed increased baseline blood pressure in Hap-I transgenic mice, an effect accentuated by a high-salt diet. Pathophysiological effects of elevated aldosterone were corroborated by our results showing upregulation of proinflammatory markers in renal tissues from the transgenic mice with Hap-I. Conclusions-These findings characterize the haplotype-dependent regulation of the hCYP11B2 gene where -344T serves as a reporter polymorphism and show that Hap-I leads to increased expression of hCYP11B2, with permissive effects on blood pressure and inflammatory milieu.

Research paper thumbnail of Dexamethasone Promotes Hypertension By Allele-Specific Regulation Of The Human Angiotensinogen Gene

Journal of Biological Chemistry, 2015

The human angiotensinogen gene (hAGT) gene has polymorphisms in its 2.5Kb promoter that form two ... more The human angiotensinogen gene (hAGT) gene has polymorphisms in its 2.5Kb promoter that form two haplotype (Hap) blocks: -6A/G (-1670A/G, -1562C/T, -1561T/C) and -217A/G (-532T/C, -793A/G, -1074T/C, and -1178G/A). Hap -6A/-217A is associated with human hypertension whereas Hap -6G/-217G reduce cardiovascular risk. Hap -6A/-217A has increased promoter activity with enhanced transcription factor binding including, the glucocorticoid receptor (GR). Glucocorticoid therapy frequently causes hypertension, the mechanisms for which are incompletely understood. We have engineered double transgenic (TG) mice containing human renin gene with either Hap of the hAGT gene and examined the physiological significance of glucocorticoid-mediated allele-specific regulation of the hAGT gene. We have also studied consequential effects on the renin angiotensin system (RAS) and blood pressure. TG mice with Hap -6A and -6G were treated with and without low dose of a GR agonist, dexamethasone (DEX, 2.5μg/mL), for 72 hours. We find greater chromatin-GR binding with increased GR agonist-induced hAGT expression in liver and renal tissues of Hap -6A mice. Additionally, DEX treatment increased circulating hAGT and angiotensin II levels in Hap -6A mice, as compared to -6G mice. Importantly, GR agonist significantly increased blood pressure and redox markers in TG mice with Hap-6A of the hAGT gene. Taken together, our results show, for the first time, that glucocorticoids affect hAGT expression in a haplotype-dependent fashion with SNPs in Hap -6A favoring agonist-induced GR binding. This leads to increased expression of the hAGT, up-regulation of the RAS, and increased blood pressure and oxidative stress in Hap -6A mice.

Research paper thumbnail of Increased heme-oxygenase 1 expression in mesenchymal stem cell-derived adipocytes decreases differentiation and lipid accumulation via upregulation of the canonical Wnt signaling cascade

Stem Cell Research & Therapy, 2013

Introduction: Heme oxygenase (HO), a major cytoprotective enzyme, attenuates oxidative stress and... more Introduction: Heme oxygenase (HO), a major cytoprotective enzyme, attenuates oxidative stress and obesity. The canonical Wnt signaling cascade plays a pivotal role in the regulation of adipogenesis. The present study examined the interplay between HO-1and the Wnt canonical pathway in the modulation of adipogenesis in mesenchymal stem cell (MSC)-derived adipocytes. Methods: To verify the role of HO-1 in generating small healthy adipocytes, cobalt protoporphyrin (CoPP), inducer of HO-1, was used during adipocyte differentiation. Lipid accumulation was measured by Oil red O staining and lipid droplet size was measured by BODIPY staining.

Research paper thumbnail of Apo A1 Mimetic Rescues the Diabetic Phenotype of HO-2 Knockout Mice via an Increase in HO-1 Adiponectin and LKBI Signaling Pathway

International journal of hypertension, 2012

Insulin resistance, with adipose tissue dysfunction, is one of the hallmarks of metabolic syndrom... more Insulin resistance, with adipose tissue dysfunction, is one of the hallmarks of metabolic syndrome. We have reported a metabolic syndrome-like phenotype in heme oxygenase (HO)-2 knockout mice, which presented with concurrent HO-1 deficiency and were amenable to rescue by an EET analog. Apo A-I mimetic peptides, such as L-4F, have been shown to induce HO-1 expression and decrease oxidative stress and adiposity. In this study we aimed to characterize alleviatory effects of HO-1 induction (if any) on metabolic imbalance observed in HO-2 KO mice. In this regard, HO-2((-/-)) mice were injected with 2 mg/kg/day L-4F, or vehicle, i.p., for 6 weeks. As before, compared to WT animals, the HO-2 null mice were obese, displayed insulin resistance, and had elevated blood pressure. These changes were accompanied by enhanced tissue (hepatic) oxidative stress along with attenuation of HO-1 expression and activity and reduced adiponectin, pAMPK, and LKB1 expression. Treatment with L-4F restored HO-1...

Research paper thumbnail of EET agonist prevents adiposity and vascular dysfunction in rats fed a high fat diet via a decrease in Bach 1 and an increase in HO-1 levels

Prostaglandins & Other Lipid Mediators, 2012

Recent reports have shown interplay between EETs (epoxides) and the heme oxygenase (HO) system in... more Recent reports have shown interplay between EETs (epoxides) and the heme oxygenase (HO) system in attenuating adipogenesis in cell culture models; prompting an examination of the effectiveness of EET agonist on obesity and associated cardio-metabolic dysfunction. Patho-physiological effects of an EET agonist (NUDSA) were contrasted in the absence and in the presence of stannous mesoporphyrin (an HO inhibitor) in SD rats fed a high fat (58%, HF) for 16 weeks. Animals on HF diet exhibited enhanced oxidative stress, increased levels of inflammatory cytokines and decreased levels of adiponectin along with reduced vascular and adipose tissue levels of EETs, HO-1; as compared to control rats (11% dietary fat). Treatment with NUDSA not only reversed serum adiponectin and vascular and adipose tissue levels of EETs and HO-1, but also, decreased blood pressure, subcutaneous and visceral fat content and serum TNFα and IL-6 levels in rats on HF diet. Aortic endothelial function, peNOS expression and adipose tissue markers of energy homeostasis i.e. pAMPK, Sirt1 and FAS, impaired in rats fed a HF diet, were restored in animals treated with this EET agonist. That NUDSA enhanced HO-1 expression, was accompanied by increase in p-GSK-3β and pAKT levels along with attenuation of adipose tissue levels of Bach 1--the transcriptional suppresser of HO-1 expression. Prevention of these beneficial effects of NUDSA, in animals on HF diet and concurrently exposed to NUDSA and SnMP, supports the role of EET-HO interaction in mediating such effects. Taken together, our findings suggest that the EETs stimulate HO-1 expression via suppression of Bach 1 and interplay of these two systems affords vascular and metabolic protection in diet induced obesity.

Research paper thumbnail of High-Fat Diet Exacerbates Renal Dysfunction in SHR: Reversal by Induction of HO-1–Adiponectin Axis

Research paper thumbnail of Heme Oxygenase-Mediated Increases in Adiponectin Decrease Fat Content and Inflammatory Cytokines Tumor Necrosis Factor-  and Interleukin-6 in Zucker Rats and Reduce Adipogenesis in Human Mesenchymal Stem Cells

Journal of Pharmacology and Experimental Therapeutics, 2008

Adiponectin, an abundant adipocyte-derived plasma protein that modulates vascular function in typ... more Adiponectin, an abundant adipocyte-derived plasma protein that modulates vascular function in type 2 diabetes, has been shown to provide cytoprotection to both pancreatic and vascular systems in diabetes. Therefore, we examined whether up-regulation of heme oxygenase (HO)-1 ameliorates the levels of inflammatory cytokines and influences serum adiponectin in Zucker fat (ZF) rats. ZF rats displayed a decrease in both HO activity and HO-1 and HO-2 protein levels and an increase in tumor necrosis factor (TNF)-␣ and interleukin (IL)-6 compared with Zucker lean (ZL) rats. Treatment of ZF animals with 2 mg/kg cobalt protoporphyrin IX (CoPP) increased protein levels of HO-1 and HO activity, but HO-2 was unaffected. The increase in HO-1 was associated with a decrease in superoxide levels (p Ͻ 0.05) and an increase in plasma adiponectin (p Ͻ 0.005), compared with untreated ZF rats. CoPP treatment de-This work was supported by National Institutes of Health Grants DK068134, HL55601, and HL34300.

Research paper thumbnail of Heme Oxygenase-2 Deletion Causes Endothelial Cell Activation Marked by Oxidative Stress, Inflammation, and Angiogenesis

Journal of Pharmacology and Experimental Therapeutics, 2009

In previous studies, we have shown that heme oxygenase (HO)-2 null [HO-2(Ϫ/Ϫ)] mice exhibit a fau... more In previous studies, we have shown that heme oxygenase (HO)-2 null [HO-2(Ϫ/Ϫ)] mice exhibit a faulty response to injury; chronic inflammation and massive neovascularization replaced resolution of inflammation and tissue repair. Endothelial cells play an active and essential role in the control of inflammation and the process of angiogenesis. We examined whether HO-2 deletion affects endothelial cell function. Under basal conditions, HO-2(Ϫ/Ϫ) aortic endothelial cells (mAEC) showed a 3-fold higher expression of vascular endothelial growth factor receptor 1 and a marked angiogenic response compared with wild-type (WT) cells. Compared with WT cells, HO-2(Ϫ/Ϫ) mAEC showed a 2-fold reduction in HO activity and marked increases in levels of gp91 phox /NADPH oxidase isoform, superoxide, nuclear factor B activation, and expression of inflammatory cytokines, including interleukin (IL)-1␣ and IL-6. HO-2 deletion transforms endothelial cells from a "normal" to an "activated" phenotype characterized by increases in inflammatory, oxidative, and angiogenic factors. This switch may be the result of reduced HO activity and the associated reduction in the cytoprotective HO products, carbon monoxide and biliverdin/bilirubin, because addition of biliverdin to HO-2(Ϫ/Ϫ) cells attenuated angiogenesis and reduced superoxide production. This transformation underscores the importance of HO-2 in the regulation of endothelial cell homeostasis. Article, publication date, and citation information can be found at

Research paper thumbnail of Cyclooxygenase-2 dependent metabolism of 20-HETE increases adiposity and adipocyte enlargement in mesenchymal stem cell-derived adipocytes

The Journal of Lipid Research, 2013

20-Hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE), a product of the cytochrome P450 (CYP)-cata... more 20-Hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE), a product of the cytochrome P450 (CYP)-catalyzed ω-hydroxylation of arachidonic acid, induces oxidative stress and, in clinical studies, is associated with increased body mass index (BMI) and the metabolic syndrome. This study was designed to examine the effects of exogenous 20-HETE on mesenchymal stem cell (MSC)-derived adipocytes. The expression levels of CYP4A11 and CYP4F2 (major 20-HETE synthases in humans) in MSCs decreased during adipocyte differentiation; however, exogenous administration of 20-HETE (0.1-1 μM) increased adipogenesis in a dose-dependent manner in these cells (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05). The inability of a 20-HETE analog to reproduce these effects suggested the involvement of a metabolic product of 20-HETE in mediating its pro-adipogenic effects. A cyclooxygenase (COX)-1 selective inhibitor enhanced, whereas a COX-2 selective or a dual COX-1/2 inhibitor attenuated adipogenesis induced by 20-HETE. The COX-derived metabolite of 20-HETE, 20-OH-PGE₂, enhanced adipogenesis and lipid accumulation in MSCs. The pro-adipogenic effects of 20-HETE and 20-OH-PGE₂ resulted in the increased expression of the adipogenic regulators PPARγ and β-catenin in MSC-derived adipocytes. Taken together we show for the first time that 20-HETE-derived COX-2-dependent 20-OH-PGE₂ enhances mature inflamed adipocyte hypertrophy in MSC undergoing adipogenic differentiation.

Research paper thumbnail of The L-4F mimetic peptide prevents insulin resistance through increased levels of HO-1, pAMPK, and pAKT in obese mice

The Journal of Lipid Research, 2009

We investigated the mechanisms by which L-4F, an apolipoprotein A-1 mimetic peptide, reduces obes... more We investigated the mechanisms by which L-4F, an apolipoprotein A-1 mimetic peptide, reduces obesity and diabetes in obese (ob) diabetic mice. We hypothesized that L-4F reduces vascular dysfunction via an increase in pAMPK and pAKT in both ob diabetic mice and human stem cells. Mice, ob and lean, were fed a normal diet until 9 weeks of age, when all ob mice had established diabetes treated with L-4F. Food intake, blood insulin, glucose levels, adipocyte stem cells and pAMPK, pAKT, SREBP-1 and insulin receptors were determined.

Research paper thumbnail of Heme induced oxidative stress attenuates sirtuin1 and enhances adipogenesis in mesenchymal stem cells and mouse pre-adipocytes

Journal of Cellular Biochemistry, 2012

Patho-physiological conditions with high oxidative stress, such as conditions associated with inc... more Patho-physiological conditions with high oxidative stress, such as conditions associated with increased denatured heme-proteins, are associated with enhanced adipogenic response. This effect predominantly manifests as adipocyte hypertrophy characterized by dysfunctional, proinflammatory adipocytes exhibiting reduced expression of anti-inflammatory hormone, adiponectin. To understand how increased levels of cellular heme, a pro-oxidant molecule, modulates adipogenesis; the following study was designed to evaluate effects of heme on adipogenesis in human mesenchymal stem cells (hMSCs) and mouse pre-adipocytes (3T3L1). Experiments were conducted in the absence and in the presence of a superoxide dismutase mimetic (tempol, 100μM). Heme (10μM) increased (p<0.05) adipogenesis in hMSCs and mouse pre-adipocytes, where tempol alone (100μmol/l) attenuated adipogenesis in these cells (p<0.05). Tempol also reversed heme-induced increase in adipogenesis in both hMSCs and mouse preadipocytes (p<0.05). In addition, heme exposed 3T3L1 exhibited reduced (p<0.05) expression of transcriptional regulator-sirtuin 1 (Sirt1), along with, increased (p<0.05) expression of adipogenic markers PPARγ, C/EBPα and aP2. These effects of heme were rescued (p<0.05) in cells concurrently treated with heme and tempol (p<0.05) and prevented in cells over-expressing Sirt1. Taken together, our results indicate that heme-induced oxidative stress inhibits Sirt1, thus uninhibiting adipogenic regulators such as PPARγ and C/EBPα; which in turn induce increased adipogenesis along with adipocyte hypertrophy in pre-adipocytes. Anti-oxidant induced offsetting of these effects of heme supports the role of heme-dependent oxidative stress in mediating such events.

Research paper thumbnail of A Haplotype of Angiotensin Receptor Type 1 Associated with Human Hypertension Increases Blood Pressure in Transgenic Mice

Journal of Biological Chemistry, 2013

Background: AT 1 R activation induces oxidative stress, promotes inflammation, and increases bloo... more Background: AT 1 R activation induces oxidative stress, promotes inflammation, and increases blood pressure. Results: SNPs in AT 1 R-promoter occur in linkage disequilibrium forming two haplotypes. Transgenic mice with haplotype-I have USF-2-dependent AT 1 R over-expression, increased oxidative stress and blood pressure. Conclusion: Haplotype-I leads to enhanced expression and patho-physiological effects of AT 1 R. Significance: Polymorphisms in AT 1 R provide for genetic predisposition to hypertension.

Research paper thumbnail of HO-1 Induction Improves The Type-1 Cardiorenal Syndrome in Mice With Impaired Angiotensin II-Induced Lymphocyte Activation

Hypertension, 2013

Type-1 cardiorenal syndrome, characterized by acute kidney dysfunction secondary to cardiac failu... more Type-1 cardiorenal syndrome, characterized by acute kidney dysfunction secondary to cardiac failure and renal arteriolar vasoconstriction, is mediated by the renin-angiotensin-aldosterone axis and sympathetic nervous system activation. Previous reports indicate that angiotensin II modulates immune function and causes recruitment and activation of T-lymphocytes. The goal of this study was to evaluate the effects of postischemic heart failure on renal morphology and circulation and the beneficial effects of heme oxygenase-1 (HO-1) induction in T-lymphocyte-suppressed severe combined immune deficiency (SCID) mice. Mice were divided into 4 groups: sham, myocardial infarction (MI), MI treated with an HO-1 inducer, cobalt protoporphyrin, and with or without stannous mesoporphyrin, an inhibitor of HO activity. Heart and kidney function were studied 30 days after surgery. Fractional area change was reduced 30 days after surgery in both the C57 and SCID MI-groups as compared with their respective controls (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01). Renal Pulsatility Index and renal injury were increased in C57 and SCID MI-groups compared with the sham group. HO-1 induction improved renal vasoconstriction as well as ameliorated renal injury in both the SCID and C57 MI-groups (P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01). However, improvement was more evident in SCID mice. In addition, our results showed that plasma creatinine, angiotensin II, and renin were significantly increased in the C57 and SCID MI-groups as compared with their respective controls. HO-1 induction decreased these parameters in both MI groups. Stannous mesoporphyrin reversed the beneficial effect of cobalt protoporphyrin in both mouse strains. The study demonstrates that T-lymphocyte suppression facilitated the HO-1-dependent improvement in the attenuation of type-1 cardiorenal syndrome.