Regression and stabilization of advanced murine atherosclerotic lesions: a comparison of LDL lowering and HDL raising gene transfer strategies

Both reductions in atherogenic lipoproteins and increases in high-density lipoprotein (HDL) levels may affect atherosclerosis regression. Here, the relative potential of low-density lipoprotein (LDL) lowering and HDL raising gene transfer strategies to induce regression of complex murine atherosclerotic lesions was directly compared. Male C57BL/6 LDL receptor (LDLr)−/− mice were fed an atherogenic diet (1.25% cholesterol and 10% coconut oil) to induce advanced atherosclerotic lesions. A baseline group was killed after 6 months and remaining mice were randomized into a control progression (Adnull or saline), an apolipoprotein (apo) A-I (AdA-I), an LDLr (AdLDLr), or a combined apo A-I/LDLr (AdA-I/AdLDLr) adenoviral gene transfer group and followed-up for another 12 weeks with continuation of the atherogenic diet. Gene transfer with AdLDLr decreased non-HDL cholesterol levels persistently by 95% (p < 0.001) compared with baseline. This drastic reduction of non-HDL cholesterol levels induced lesion regression by 28% (p < 0.001) in the aortic root and by 25% (p < 0.05) in the brachiocephalic artery at 12 weeks after transfer. Change in lesion size was accompanied by enhanced plaque stability, as evidenced by increased collagen content, reduced lesional macrophage content, a drastic reduction of necrotic core area, and decreased expression of inflammatory genes. Elevated HDL cholesterol following AdA-I transfer increased collagen content in lesions, but did not induce regression. Apo A-I gene transfer on top of AdLDLr transfer resulted in additive effects, particularly on inflammatory gene expression. In conclusion, drastic lipid lowering induced by a powerful gene transfer strategy leads to pronounced regression and stabilization of advanced murine atherosclerosis

Transcriptome Alteration in the Diabetic Heart by Rosiglitazone: Implications for Cardiovascular Mortality

BACKGROUND: Recently, the type 2 diabetes medication, rosiglitazone, has come under scrutiny for possibly increasing the risk of cardiac disease and death. To investigate the effects of rosiglitazone on the diabetic heart, we performed cardiac transcriptional profiling and imaging studies of a murine model of type 2 diabetes, the C57BL/KLS-lepr(db)/lepr(db) (db/db) mouse. METHODS AND FINDINGS: We compared cardiac gene expression profiles from three groups: untreated db/db mice, db/db mice after rosiglitazone treatment, and non-diabetic db/+ mice. Prior to sacrifice, we also performed cardiac magnetic resonance (CMR) and echocardiography. As expected, overall the db/db gene expression signature was markedly different from control, but to our surprise was not significantly reversed with rosiglitazone. In particular, we have uncovered a number of rosiglitazone modulated genes and pathways that may play a role in the pathophysiology of the increase in cardiac mortality as seen in several recent meta-analyses. Specifically, the cumulative upregulation of (1) a matrix metalloproteinase gene that has previously been implicated in plaque rupture, (2) potassium channel genes involved in membrane potential maintenance and action potential generation, and (3) sphingolipid and ceramide metabolism-related genes, together give cause for concern over rosiglitazone's safety. Lastly, in vivo imaging studies revealed minimal differences between rosiglitazone-treated and untreated db/db mouse hearts, indicating that rosiglitazone's effects on gene expression in the heart do not immediately turn into detectable gross functional changes. CONCLUSIONS: This study maps the genomic expression patterns in the hearts of the db/db murine model of diabetes and illustrates the impact of rosiglitazone on these patterns. The db/db gene expression signature was markedly different from control, and was not reversed with rosiglitazone. A smaller number of unique and interesting changes in gene expression were noted with rosiglitazone treatment. Further study of these genes and molecular pathways will provide important insights into the cardiac decompensation associated with both diabetes and rosiglitazone treatment

Killer immunoglobulin-like Receptors (KIR) haplogroups A and B track with Natural Killer Cells and Cytokine Profile in Aged Subjects: Observations from Octo/Nonagenarians in the Belfast Elderly Longitudinal Free-living Aging STudy (BELFAST)

BACKGROUND: Natural Killer Cells (NK) play an important role in detection and elimination of virus-infected, damaged or cancer cells. NK cell function is guided by expression of Killer Immunoglobulin-like Receptors (KIRs) and contributed to by the cytokine milieu. KIR molecules are grouped on NK cells into stimulatory and inhibitory KIR haplotypes A and B, through which NKs sense and tolerate HLA self-antigens or up-regulate the NK-cytotoxic response to cells with altered HLA self-antigens, damaged by viruses or tumours. We have previously described increased numbers of NK and NK-related subsets in association with sIL-2R cytokine serum levels in BELFAST octo/nonagenarians. We hypothesised that changes in KIR A and B haplotype gene frequencies could explain the increased cytokine profiles and NK compartments previously described in Belfast Elderly Longitudinal Free-living Aging STudy (BELFAST) octo/nonagenarians, who show evidence of ageing well. RESULTS: In the BELFAST study, 24% of octo/nonagenarians carried the KIR A haplotype and 76% KIR B haplotype with no differences for KIR A haplogroup frequency between male or female subjects (23% v 24%; p=0.88) or for KIR B haplogroup (77% v 76%; p=0.99). Octo/nonagenarian KIR A haplotype carriers showed increased NK numbers and percentage compared to Group B KIR subjects (p=0.003; p=0.016 respectively). There were no KIR A/ B haplogroup-associated changes for related CD57+CD8 ((high or low)) subsets. Using logistic regression, KIR B carriers were predicted to have higher IL-12 cytokine levels compared to KIR A carriers by about 3% (OR 1.03, confidence limits CI 0.99–1.09; p=0.027) and 14% higher levels for TGF-β (active), a cytokine with an anti-inflammatory role, (OR 1.14, confidence limits CI 0.99–1.09; p=0.002). CONCLUSION: In this observational study, BELFAST octo/nonagenarians carrying KIR A haplotype showed higher NK cell numbers and percentage compared to KIR B carriers. Conversely, KIR B haplotype carriers, with genes encoding for activating KIRs, showed a tendency for higher serum pro-inflammatory cytokines compared to KIR A carriers. While the findings in this study should be considered exploratory they may serve to stimulate debate about the immune signatures of those who appear to age slowly and who represent a model for good quality survivor-hood

Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular "reactive oxygen species" (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation). The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible. This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference

Effect of the stromelysin-1 promoter on efficacy of pravastatin in coronary atherosclerosis and restenosis

It has proved difficult to identify high-risk patients for atherosclerosis and to determine how they might respond to medication. Recently, a common promoter variant of the human stromelysin-1 gene has been reported, which has been shown to affect the transcription. We investigated whether this polymorphism had any impact on the risk of events, especially restenosis and progression of coronary artery disease and whether the effect was modulated by treatment with pravastatin. The stromelysin-1 genotype was determined for 496 men with coronary artery disease and cholesterol levels between 4.0 and 8.0 mmol/L, participating in the Regression Growth Evaluation Statin Study (REGRESS) study, a clinical trial assessing the effect of the lipid-lowering drug pravastatin on the progression of atherosclerosis. Patients in the placebo group with 5A6A or 6A6A genotypes had more clinical events than patients with the 5A5A genotype (26% and 12%, respectively, p = 0.03). In the pravastatin group, the risk of clinical events in patients with 5A6A or 6A6A genotypes was lower, compared with placebo, whereas it was unchanged in those with a 5A5A genotype (p value for interaction: 0.038). Also, the incidence of repeat angioplasty in the placebo group was greater in patients with the 6A6A or 5A6A genotypes, compared with 5A homozygotes (38% and 40%, respectively, vs 11%, p = 0.09). Again, treatment substantially reduced the incidence in heterozygotes and 6A homozygotes (0% and 15%, respectively), whereas it was unchanged in 5A homozygotes (28%, p for interaction: 0.002). These effects were independent of the effects of pravastatin on the lipid levels. Thus, this study suggests that the stomelysin-1 promoter polymorphism confers a genotype-specific response to medication in determining clinical event-free survival and the risk for symptom-driven repeat angioplasty. This variant may therefore act as a predictor, not only of disease progression, but also of response to therapy and risk of restenosi