Atherosclerosis in Marek's disease virus infected hypercholesterolemic roosters is reduced by HMGCoA reductase and ACE inhibitor therapy

Evaluation of Orally Administered Atorvastatin on Plasma Lipid and Biochemistry Profiles in Hypercholesterolemic Hispaniolan Amazon Parrots (Amazona ventralis)

Atorvastatin is a synthetic statin administered in its active form and used for the treatment of dyslipidemias. In the current study, the effects of atorvastatin were evaluated on plasma lipid profiles and the potential for adverse effects after once daily PO dosing of atorvastatin for 30 days in Hispaniolan Amazon parrots (Amazona ventralis). Sixteen adult parrots (10 female, 6 male) with hypercholesterolemia were used for this study. Birds were assigned to 2 groups (treatment and control) of 8 parrots each (3 male, 5 female) after balancing for age, sex, originating institution, and baseline plasma cholesterol values. Compounded atorvastatin oral suspension (10 mg/kg) was administered PO once daily via gavage into the crop. Equivalent volumes of placebo suspension were administered to the control group. Plasma biochemistry and plasma lipid profile analysis (total cholesterol, high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C], and triglycerides [TGs]) were analyzed on days 0, 14, and 30. Plasma samples and HDL-C fractions were evaluated for cholesterol and TG concentrations via enzymatic assays. Subtraction of HDL-C values from total cholesterol yielded the non-HDL-C concentration for each bird. Birds were routinely assessed for appetite, activity, and urofeces. Plasma atorvastatin concentrations were obtained from 7 of 8 birds in the treatment group from banked samples. Those samples were obtained on days 14 and 30, with drug administration 6 to 8 hours before collection. No significant differences were observed in total cholesterol, HDL-C, non-HDL-C, or TG between treatment and control groups at days 0, 14, and 30. Plasma atorvastatin concentrations were variable on day 14 (0.54-5.41 ng/ mL for 6 of 7 samples, with 1 outlier of 307 ng/mL) and on day 30 (0.79-6.74 ng/mL). No adverse effects were noted in any of the birds during the study period. When dosed PO at 10 mg/kg once daily, atorvastatin did not result in significant changes to plasma lipid profiles (eg, lowering of plasma total or non-HDL-C concentrations) at any time point during this study. Future studies to investigate pharmacokinetic and pharmacodynamic properties of atorvastatin in parrots may require increased doses and/or frequency of administration.

De Novo Cholesterol Biosynthesis and Its Trafficking in LAMP-1-Positive Vesicles Are Involved in Replication and Spread of Marek's Disease Virus

Marek's disease virus (MDV) transforms CD4+ T cells and causes a deadly neoplastic disease that is associated with metabolic dysregulation leading to atherosclerosis in chickens. While MDV-infected chickens have normal serum concentrations of cholesterol, their aortic tissues were found to have elevated concentrations of free and esterified cholesterol. Here, we demonstrate that infection of chicken embryonated fibroblasts (CEFs) with highly pathogenic MDV-RB1B increases the cellular cholesterol content and upregulates the genes involved in cholesterol synthesis and cellular cholesterol homeostasis using comprehensive two-dimensional gas chromatography-mass spectrometry and real-time PCR (RT-PCR), respectively. Using small pharmacological inhibitors and gene silencing, we established an association between MDV-RB1B replication and mevalonic acid, sterol, and cholesterol biosynthesis and trafficking/redistribution. We propose that MDV trafficking is mediated by lysosome-associated membrane protein 1 (LAMP-1)-positive vesicles based on short hairpin RNA (shRNA) gene silencing and the colocalization of LAMP-1, glycoprotein B (gB) of MDV, and cholesterol (filipin III) fluorescence signal intensity peaks. In conclusion, our results demonstrate that MDV hijacks cellular cholesterol biosynthesis and cholesterol trafficking to facilitate cell-to-cell spread in a LAMP-1-dependent mechanism.IMPORTANCE MDV disrupts lipid metabolism and causes atherosclerosis in MDV-infected chickens; however, the role of cholesterol metabolism in the replication and spread of MDV is unknown. MDV-infected cells do not produce infectious cell-free virus in vitro, raising the question about the mechanism involved in the cell-to-cell spread of MDV. In this report, we provide evidence that MDV replication depends on de novo cholesterol biosynthesis and uptake. Interruption of cholesterol trafficking within multivesicular bodies (MVBs) by chemical inhibitors or gene silencing reduced MDV titers and cell-to-cell spread. Finally, we demonstrated that MDV gB colocalizes with cholesterol and LAMP-1, suggesting that viral protein trafficking is mediated by LAMP-1-positive vesicles in association with cholesterol. These results provide new insights into the cholesterol dependence of MDV replication.

Role of nitric oxide and carbon monoxide in N(omega)-Nitro-L-arginine methyl ester-resistant acetylcholine-induced relaxation in chicken carotid artery

The current study examined the hypothesis that acetylcholine-induced N(omega)-Nitro-L-arginine methyl ester (L-NAME)-resistant endothelium-dependent relaxations in the chicken carotid artery are mediated by nitric oxide and carbon monoxide. Acetylcholine (1 nM-3 microM) caused a concentration-dependent relaxation (pD(2) 6.81+/-0.05, R(max) 115+/-3%) of the artery segments precontracted with phenylephrine (3 microM). L-NAME (1 mM) decreased the sensitivity (pD(2) 6.44+/-0.06), but not the efficacy (R(max) 108+/-3%) of acetylcholine. It also partially decreased the acetylcholine (3 microM)-stimulated nitrite release. While treatment with N(omega)-Nitro-L-arginine (l-NNA; 1 mM) plus L-NAME (1 mM) decreased the acetylcholine-stimulated nitrite release to the basal level, it moderately inhibited (R(max) 77+/-3%) the maximal relaxation elicited with the muscarinic agonist. 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO; 100 microM) a specific scavenger of nitric oxide (NO) plus the two NOS inhibitors further decreased the acetylcholine-evoked relaxation (R(max) 34+/-2%). Although soluble guanylyl cyclase (sGC) inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 microM) markedly inhibited the acetylcholine-stimulated increase in tissue cGMP to less than the basal levels, it only decreased the sensitivity, but not the efficacy of the agonist either in the presence or absence of L-NAME (1 mM). Zinc Protoporphyrin-IX (ZnPP; 10 microM), a hemeoxygenase (HO) inhibitor, partially inhibited (R(max) 72+/-3%) the L-NAME-resistant acetylcholine-induced relaxations. A combined treatment of the arterial rings with L-NAME, l-NNA, PTIO and ZnPP nearly abolished (R(max) 7+/-0.9%) the vasodilator responses to acetylcholine. Endothelium removal abolished the relaxation response to acetylcholine. In conclusion, it is suggested that the acetylcholine-induced L-NAME-resistant relaxation is primarily, mediated by NO with a small but significant contribution from endothelium-derived carbon monoxide in the chicken carotid artery.

Transmembrane proteases in cell growth and invasion: new contributors to angiogenesis?

Transmembrane proteases (TPs) are proteins anchored in the plasma membrane with their catalytic site exposed to the external surface of the membrane. TPs are widely expressed, and their dysregulated expression is associated with cancer, infection, inflammation, autoimmune and cardiovascular diseases, all diseases where angiogenesis is part of the pathology. TPs participate in extracellular proteolysis (degradation of extracellular matrix components, regulation of chemokine activity, release of membrane-anchored cytokines, cytokine receptors and adhesion molecules) and influence cell functions (growth, secretion of angiogenic molecules, motility). Recent attention has been focused on the ADAM-17 (a disintegrin and metalloprotease)/TACE/CD156q, the MT1-MMP (membrane-type-1 matrix metallo proteinase)/MMP-14, and the ectopeptidases aminopeptidase N (APN/CD13), dipeptidyl peptidase IV (DPPIV/CD26) and angiotensin-converting enzyme (ACE/CD143), that appear to have a critical role in angiogenesis. This article summarizes current knowledge on these TPs, and reviews recent investigations that document their participation during angiogenic-related events. Through their multiple roles, TPs may thereby provide critical links in angiogenesis.

Avian cardiology

The field of avian cardiology is continually expanding. Although a great deal of the current knowledge base has been derived from poultry data, research and clinical reports involving companion avian species have been published. This article will present avian cardiovascular anatomy and physiology, history and physical examination considerations in the avian cardiac disease patient, specific diagnostic tools, cardiovascular disease processes, and current therapeutic modalities.

Atherogenic high-fat diet reduces bone mineralization in mice

The epidemiological correlation between osteoporosis and cardiovascular disease is independent of age, but the basis for this correlation is unknown. We previously found that atherogenic oxidized lipids inhibit osteoblastic differentiation in vitro and ex vivo, suggesting that an atherogenic diet may contribute to both diseases. In this study, effects of an atherogenic high-fat diet versus control chow diet on bone were tested in two strains of mice with genetically different susceptibility to atherosclerosis and lipid oxidation. After 4 months and 7 months on the diets, mineral content and density were measured in excised femurs and lumbar vertebrae using peripheral quantitative computed tomographic (pQCT) scanning. In addition, expression of osteocalcin in marrow isolated from the mice after 4 months on the diets was examined. After 7 months, femoral mineral content in C57BL/6 atherosclerosis-susceptible mice on the high-fat diet was 43% lower (0.73 +/- 0.09 mg vs. 1.28 +/- 0.42 mg; p = 0.008), and mineral density was 15% lower compared with mice on the chow diet. Smaller deficits were observed after 4 months. Vertebral mineral content also was lower in the fat-fed C57BL/6 mice. These changes in the atherosclerosis-resistant, C3H/HeJ mice were smaller and mostly not significant. Osteocalcin expression was reduced in the marrow of high fat-fed C57BL/6 mice. These findings suggest that an atherogenic diet inhibits bone formation by blocking differentiation of osteoblast progenitor cells.

Animal models of infection-mediated vasculitis: implications for human disease

The human vasculitides including Takayasu's arteritis are idiopathic syndromes for which both autoimmune and infectious etiologies have been proposed. Although proof of a correlation between infection and human vasculitis would aid in patient management, it is difficult to confirm causality. To study infection-mediated vascular disease, different animal models have been developed. Infections with the bacteria C. pneumoniae, an RNA virus, and herpesviruses all cause vascular pathology and will be reviewed here. Many aspects of the human diseases are recapitulated in these models, so further animal studies may help elucidate mechanisms of infection-mediated vasculitis. Such results may improve management, and potentially, prevention of these important human diseases. Importantly, the animal models provide an opportunity to define how the immune and inflammatory processes function in the great vessels and the molecular basis for the selectivity of certain viral infections for the great elastic arteries.

Detection of transplant vasculopathy in a rat aortic allograft model by fluorescence spectroscopic optical analysis

BACKGROUND AND OBJECTIVE

Transplant vasculopathy is a leading cause of late cardiac graft loss. We have examined laser-induced fluorescence (LIF) spectroscopy as an optical diagnostic tool for detection of intimal plaque development and inflammatory cellular invasion in a rat model of aortic allograft transplant.

STUDY DESIGN/MATERIALS AND METHODS

Infrarenal aortic segments were transplanted from Lewis to Sprague Dawley rats. A range of vasculopathy development was produced by treatment with a viral anti-inflammatory protein. LIF spectra were recorded from the intima of aortic implants at 28 days. Fluorescence intensity was analyzed for correlation with vasculopathy development.

RESULTS

Significant differences in LIF intensity at 400-450 nm (P < or = 0.05 by ANOVA) were detected. LIF emission was correlated with plaque growth (R2 = 0.980), vessel narrowing (R2 = 0.964), and cellular invasion (R2 = 0.971) by regression analysis.

CONCLUSION

LIF optical analysis provides a nontraumatic diagnostic approach for detection of atherosclerosis prior to cardiac transplant or during development of vasculopathy after transplant.

Low-density lipoprotein-independent effects of statins

Statins have pleiotropic properties that complement their cholesterol-lowering effects. These properties may partly account for their established benefit in the prevention of coronary artery disease beyond the reduction of LDL-cholesterol levels. The most widely recognized properties are reviewed here. They include: (i) nitric oxide-mediated improvement of endothelial dysfunction and upregulation of endothelin-1 expression; (ii) antioxidant effects; (iii) anti-inflammatory properties; (iv) inhibition of cell proliferation with anticarcinogenic actions in animals; (v) stabilization of atherosclerotic plaques; (vi) anticoagulant effects; and (vii) inhibition of graft rejection after heart and kidney transplantation. As advances are made in our knowledge, new properties are steadily being uncovered. Pleiotropic effects are currently being given consideration when instituting combination therapy for patients at high cardiovascular risk. Some pleiotropic effects are negative, and may account for occasional untoward drug interactions. For many of these new properties, the clinical relevance has not been established. The challenge for the future will be to design and carry out appropriate clinical trials to establish their relative importance in the prevention of coronary artery disease.

Animal models of infection-mediated vasculitis

The human vasculitides are idiopathic syndromes for which both autoimmune and infectious causes have been proposed. Although proof of a correlation between infection and human vasculitis would aid in patient management, it is difficult to confirm causality. To study infection-mediated vascular disease, different animal models have been developed. Infections with the bacterium Chlamydia pneumoniae, an RNA virus, and herpesviruses all cause vascular pathology and are reviewed here. Many aspects of the human diseases are recapitulated in these models, so that further animal studies may help elucidate mechanisms of infection-mediated vasculitis. Such results may improve management, and potentially prevention, of these important human diseases.