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1.  HDL anti-oxidant function associates with LDL level in young adults 
Atherosclerosis  2013;232(1):165-170.
The primary objective was to evaluate predictors of HDL anti-oxidant function in young adults.
High-density lipoprotein (HDL) cholesterol is considered a protective factor for cardiovascular disease (CVD). However, increased levels are not always associated with decreased cardiovascular risk. A better understanding of the importance of HDL functionality and how it affects CVD risk is needed.
Fifty non-Hispanic white subjects from the Testing Responses on Youth (TROY) study were randomly selected to investigate whether differences in HDL anti-oxidant function are associated with traditional cardiovascular risk factors, including carotid intima media thickness (CIMT), arterial stiffness and other inflammatory/metabolic parameters. HDL anti-oxidant capacity was evaluated by assessing its ability to inhibit low-density lipoprotein (LDL) cholesterol oxidation by air using a DCF-based fluorescent assay and expressed as a HDL oxidant index (HOI). The associations between HOI and other variables were assessed using both linear and logistic regression.
Eleven subjects (25%) had an HOI ≥ 1, indicating a pro-oxidant HDL. Age, LDL, high sensitivity C-reactive protein (hsCRP), and paraoxonase activity (PON1), but not HDL, were all associated with HOI level in univariate linear regression models. In multivariate models that mutually adjusted for these variables, LDL remained the strongest predictor of HOI (0.13 increase in HOI per 1 SD increase in LDL, 95% CI 0.04, 0.22).
Atherogenic index of plasma, pulse pressure, homocysteine, glucose, insulin, CIMT and measurements of arterial stiffness were not associated with HOI in this population.
These results suggest LDL, hsCRP and DBP might predict HDL anti-oxidant function at an early age.
PMCID: PMC4039385  PMID: 24401232
high density lipoprotein; antioxidant; paraoxonase; atherosclerosis
2.  Network for Activation of Human Endothelial Cells by Oxidized Phospholipids: A Critical Role of Heme Oxygenase 1 
Circulation research  2011;109(5):e27-e41.
Ox-PAPC accumulates in atherosclerotic lesions, is pro-atherogenic, and influences the expression of over 1000 genes in endothelial cells.
To elucidate the major pathways involved in Ox-PAPC action, we conducted a systems analysis of endothelial cell gene expression after exposure to Ox-PAPC.
Methods and Results
We used the variable responses of primary endothelial cells from 149 individuals exposed to Ox-PAPC to construct a network consisting of 11 groups of genes or modules. Modules were enriched for a broad range of GO pathways, some of which have not been previously identified as major Ox-PAPC targets. Further validating our method of network construction, modules were consistent with relationships established by cell biology studies of Ox-PAPC effects on endothelial cells. This network provides novel hypotheses about molecular interactions, as well as candidate molecular regulators of inflammation and atherosclerosis. We validate several hypotheses based on network connections and genomic association. Our network analysis predicted that the hub gene CHAC1 was regulated by the ATF4 arm of the unfolded protein response pathway and here we showed that ATF4 directly activates an element in the CHAC1 promoter. We show that variation in basal levels of HMOX1 contribute to the response to Ox-PAPC, consistent with its position as a hub in our network. We also identified GPR39 as a regulator of HMOX1 levels and showed that it modulates the promoter activity of HMOX1. We further showed that OKL38/OSGN1, the hub gene in the blue module, is a key regulator of both inflammatory and anti-inflammatory molecules.
Our systems genetics approach has provided a broad view of the pathways involved in the response of endothelial cells to Ox-PAPC and also identified novel regulatory mechanisms.
PMCID: PMC3163234  PMID: 21737788
Endothelial Cells; Oxidized Phospholipids; Gene Expression; Heme Oxygenase; Network; Systems Genetics; Genome-Wide Association Studies
3.  Heme Oxygenase-1, Oxidation, Inflammation, and Atherosclerosis 
Atherosclerosis is an inflammatory process of the vascular wall characterized by the infiltration of lipids and inflammatory cells. Oxidative modifications of infiltrating low-density lipoproteins and induction of oxidative stress play a major role in lipid retention in the vascular wall, uptake by macrophages and generation of foam cells, a hallmark of this disorder. The vasculature has a plethora of protective resources against oxidation and inflammation, many of them regulated by the Nrf2 transcription factor. Heme oxygenase-1 (HO-1) is a Nrf2-regulated gene that plays a critical role in the prevention of vascular inflammation. It is the inducible isoform of HO, responsible for the oxidative cleavage of heme groups leading to the generation of biliverdin, carbon monoxide, and release of ferrous iron. HO-1 has important antioxidant, antiinflammatory, antiapoptotic, antiproliferative, and immunomodulatory effects in vascular cells, most of which play a significant role in the protection against atherogenesis. HO-1 may also be an important feature in macrophage differentiation and polarization to certain subtypes. The biological effects of HO-1 are largely attributable to its enzymatic activity, which can be conceived as a system with three arms of action, corresponding to its three enzymatic byproducts. HO-1 mediated vascular protection may be due to a combination of systemic and vascular local effects. It is usually expressed at low levels but can be highly upregulated in the presence of several proatherogenic stimuli. The HO-1 system is amenable for use in the development of new therapies, some of them currently under experimental and clinical trials. Interestingly, in contrast to the HO-1 antiatherogenic actions, the expression of its transcriptional regulator Nrf2 leads to proatherogenic effects instead. This suggests that a potential intervention on HO-1 or its byproducts may need to take into account any potential alteration in the status of Nrf2 activation. This article reviews the available evidence that supports the antiatherogenic role of HO-1 as well as the potential pathways and mechanisms mediating vascular protection.
PMCID: PMC3400084  PMID: 22833723
heme oxygenase; bilirubin; carbon monoxide; iron; oxidative stress; inflammation; atherosclerosis
4.  NF-E2–Related Factor 2 Promotes Atherosclerosis by Effects on Plasma Lipoproteins and Cholesterol Transport That Overshadow Antioxidant Protection 
To test the hypothesis that NF-E2–related factor 2 (Nrf2) expression plays an antiatherogenic role by its vascular antioxidant and anti-inflammatory properties.
Methods and Results
Nrf2 is an important transcription factor that regulates the expression of phase 2 detoxifying enzymes and antioxidant genes. Its expression in vascular cells appears to be an important factor in the protection against vascular oxidative stress and inflammation. We developed Nrf2 heterozygous (HET) and homozygous knockout (KO) mice on an apolipoprotein (apo) E–null background by sequential breeding, resulting in Nrf2−/−, apoE−/− (KO), Nrf2−/+, apoE−/− (HET) and Nrf2+/+, and apoE−/− wild-type littermates. KO mice exhibited decreased levels of antioxidant genes with evidence of increased reactive oxygen species generation compared with wild-type controls. Surprisingly, KO males exhibited 47% and 53% reductions in the degree of aortic atherosclerosis compared with HET or wild-type littermates, respectively. Decreased atherosclerosis in KO mice correlated with lower plasma total cholesterol in a sex-dependent manner. KO mice also had a decreased hepatic cholesterol content and a lower expression of lipogenic genes, suggesting that hepatic lipogenesis could be reduced. In addition, KO mice exhibited atherosclerotic plaques characterized by a lesser macrophage component and decreased foam cell formation in an in vitro lipid-loading assay. This was associated with a lower rate of cholesterol influx, mediated in part by decreased expression of the scavenger receptor CD36.
Nrf2 expression unexpectedly promotes atherosclerotic lesion formation in a sex-dependent manner, most likely by a combination of systemic metabolic and local vascular effects.
PMCID: PMC3037185  PMID: 20947826
atherosclerosis; cytokines; lipoproteins; reactive oxygen species; foam cell formation; lipogenesis; Nrf2
5.  Differential Roles of Cardiomyocyte and Macrophage Peroxisome Proliferator–Activated Receptor γ in Cardiac Fibrosis 
Diabetes  2008;57(9):2470-2479.
OBJECTIVE—Cardiac fibrosis is an important component of diabetic cardiomyopathy. Peroxisome proliferator–activated receptor γ (PPARγ) ligands repress proinflammatory gene expression, including that of osteopontin, a known contributor to the development of myocardial fibrosis. We thus investigated the hypothesis that PPARγ ligands could attenuate cardiac fibrosis.
RESEARCH DESIGN AND METHODS—Wild-type cardiomyocyte- and macrophage-specific PPARγ−/− mice were infused with angiotensin II (AngII) to promote cardiac fibrosis and treated with the PPARγ ligand pioglitazone to determine the roles of cardiomyocyte and macrophage PPARγ in cardiac fibrosis.
RESULTS—Cardiomyocyte-specific PPARγ−/− mice (cPPARγ−/−) developed spontaneous cardiac hypertrophy with increased ventricular osteopontin expression and macrophage content, which were exacerbated by AngII infusion. Pioglitazone attenuated AngII-induced fibrosis, macrophage accumulation, and osteopontin expression in both wild-type and cPPARγ−/− mice but induced hypertrophy in a PPARγ-dependent manner. We pursued two mechanisms to explain the antifibrotic cardiomyocyte-PPARγ–independent effects of pioglitazone: increased adiponectin expression and attenuation of proinflammatory macrophage activity. Adenovirus-expressed adiponectin had no effect on cardiac fibrosis and the PPARγ ligand pioglitazone did not attenuate AngII-induced cardiac fibrosis, osteopontin expression, or macrophage accumulation in monocyte-specific PPARγ−/− mice.
CONCLUSIONS—We arrived at the following conclusions: 1) both cardiomyocyte-specific PPARγ deficiency and activation promote cardiac hypertrophy, 2) both cardiomyocyte and monocyte PPARγ regulate cardiac macrophage infiltration, 3) inflammation is a key mediator of AngII-induced cardiac fibrosis, 4) macrophage PPARγ activation prevents myocardial macrophage accumulation, and 5) PPARγ ligands attenuate AngII-induced cardiac fibrosis by inhibiting myocardial macrophage infiltration. These observations have important implications for potential interventions to prevent cardiac fibrosis.
PMCID: PMC2518499  PMID: 18511847
6.  Cigarette smoking is associated with dose-dependent adverse effects on paraoxonase activity and fibrinogen in young women 
Inhalation Toxicology  2014;26(14):861-865.
Smoking is associated with increased fibrinogen and decreased paraoxonase (PON) activity, markers of inflammation and oxidative stress, in patients with coronary artery disease.
We tested the hypothesis that the adverse effect of smoking on these biomarkers of inflammation and oxidative stress would be detectable in otherwise healthy young female habitual smokers.
Materials and methods
Thirty-eight young women participated in the study (n = 20 habitual smokers, n = 18 non-smokers). Fibrinogen, PON-1 activity and HDL oxidant index (HOI) were measured.
Mean values of fibrinogen, PON-1 activity and log HOI were not different between the groups. Importantly, however, decreased PON-1 activity (r s = −0.51, p = 0.03) and increased fibrinogen (rs = 0.49, p = 0.04) were significantly correlated with increasing number of cigarettes smoked per day in habitual smokers.
Discussion and conclusion
Cigarette smoking is associated with a dose-dependent adverse effect on PON-1 activity and fibrinogen in young women, which may have implications for future cardiovascular risk.
PMCID: PMC4266070  PMID: 25472476
Fibrinogen; paraoxonase activity; smoking; women

Results 1-6 (6)