Atorvastatin treatment increases plasma bilirubin but not HMOX1 expression in stable angina patients

SLCO1B1 Exome Sequencing and Statin Treatment Response in 64,000 UK Biobank Patients

The solute carrier organic anion transporter family member 1B1 (SLCO1B1) encodes the organic anion-transporting polypeptide 1B1 (OATP1B1 protein) that transports statins to liver cells. Common genetic variants in SLCO1B1, such as *5, cause altered systemic exposure to statins and therefore affect statin outcomes, with potential pharmacogenetic applications; yet, evidence is inconclusive. We studied common and rare SLCO1B1 variants in up to 64,000 patients from UK Biobank prescribed simvastatin or atorvastatin, combining whole-exome sequencing data with up to 25-year routine clinical records. We studied 51 predicted gain/loss-of-function variants affecting OATP1B1. Both SLCO1B1*5 alone and the SLCO1B1*15 haplotype increased LDL during treatment (beta*5 = 0.08 mmol/L, p = 6 × 10-8; beta*15 = 0.03 mmol/L, p = 3 × 10-4), as did the likelihood of discontinuing statin prescriptions (hazard ratio*5 = 1.12, p = 0.04; HR*15 = 1.05, p = 0.04). SLCO1B1*15 and SLCO1B1*20 increased the risk of General Practice (GP)-diagnosed muscle symptoms (HR*15 = 1.22, p = 0.003; HR*20 = 1.25, p = 0.01). We estimated that genotype-guided prescribing could potentially prevent 18% and 10% of GP-diagnosed muscle symptoms experienced by statin patients, with *15 and *20, respectively. The remaining common variants were not individually significant. Rare variants in SLCO1B1 increased LDL in statin users by up to 1.05 mmol/L, but replication is needed. We conclude that genotype-guided treatment could reduce GP-diagnosed muscle symptoms in statin patients; incorporating further SLCO1B1 variants into clinical prediction scores could improve LDL control and decrease adverse events, including discontinuation.

The physiology of bilirubin: health and disease equilibrium

Bilirubin has several physiological functions, both beneficial and harmful. In addition to reactive oxygen species-scavenging activities, bilirubin has potent immunosuppressive effects associated with long-term pathophysiological sequelae. It has been recently recognized as a hormone with endocrine actions and interconnected effects on various cellular signaling pathways. Current studies show that bilirubin also decreases adiposity and prevents metabolic and cardiovascular diseases. All in all, the physiological importance of bilirubin is only now coming to light, and strategies for increasing plasma bilirubin levels to combat chronic diseases are starting to be considered. This review discusses the beneficial effects of increasing plasma bilirubin, incorporates emerging areas of bilirubin biology, and provides key concepts to advance the field.

Targeting Heme Oxygenase-1 in the Arterial Response to Injury and Disease

Heme oxygenase-1 (HO-1) catalyzes the degradation of heme into carbon monoxide (CO), iron, and biliverdin, which is rapidly metabolized to bilirubin. The activation of vascular smooth muscle cells (SMCs) plays a critical role in mediating the aberrant arterial response to injury and a number of vascular diseases. Pharmacological induction or gene transfer of HO-1 improves arterial remodeling in animal models of post-angioplasty restenosis, vascular access failure, atherosclerosis, transplant arteriosclerosis, vein grafting, and pulmonary arterial hypertension, whereas genetic loss of HO-1 exacerbates the remodeling response. The vasoprotection evoked by HO-1 is largely ascribed to the generation of CO and/or the bile pigments, biliverdin and bilirubin, which exert potent antioxidant and anti-inflammatory effects. In addition, these molecules inhibit vascular SMC proliferation, migration, apoptosis, and phenotypic switching. Several therapeutic strategies are currently being pursued that may allow for the targeting of HO-1 in arterial remodeling in various pathologies, including the use of gene delivery approaches, the development of novel inducers of the enzyme, and the administration of unique formulations of CO and bilirubin.

Effect of statin treatment on circulating malondialdehyde concentrations: a systematic review and meta-analysis

Background

The effect of statins on oxidative stress markers, such as malondialdehyde (MDA), is still a matter of debate. We sought to address this issue by conducting a systematic review and meta-analysis of published data on the effect of statin treatment on systemic MDA concentrations.

Methods

A literature search was conducted on MEDLINE/PubMed, ISI Web of Sciences and Scopus. Data were pooled using a random-effects model.

Results

A total of 35 studies assessing MDA concentrations before and after statin treatment in 1512 participants (mean age 53.6 years, 48.7% males) were identified. Extreme between-study heterogeneity was observed (I² = 96.0%, p < 0.001). Pooled standardized mean difference (SMD) showed a significant reduction in plasma MDA concentrations after treatment (SMD = -1.47 µmol/l, 95% confidence interval = -1.89 to -1.05 μmol/l; p < 0.001). Similarly, a subgroup analysis of 10 studies that also included a placebo group showed a significant reduction in plasma MDA concentrations with statins (-1.03 μmol/l, 95% confidence interval = -1.52 to -0.29 μmol/l; p = 0.036).

Conclusions

This systematic review and meta-analysis showed that statin treatment significantly reduces systemic MDA concentrations. However, the results should be interpreted with caution because of extreme between-study heterogeneity, which warrants further intervention studies.

Determination of the Predictive Value of Serum Bilirubin in Patients with Ischemic Stroke: A Prospective Descriptive Analytical Study

Purpose: In all types of ischemic stroke, especially in the acute phase, excessive oxidative stress causes structural and functional damage to the brain. This may play a major role in the pathophysiology of the brain damage. Higher serum levels of bilirubin have therapeutic effects in oxidative stress-induced stroke. Nevertheless, role of increased serum levels of bilirubin in the acute phase of ischemic stroke is ccontroversial.

Methods: This study was a cross-sectional prospective descriptive study conducted in the Emergency Department (ED) of Imam Reza hospital, Tabriz University of Medical Sciences, Tabriz, Iran, throughout six months. 275 ischemic stroke patients were evaluated based on their brain CT scan infarct size, NIHSS, MRS, and serum levels of bilirubin. Later, data were analyzed using SPSS software.

Results: Results: Total, direct and indirect bilirubin levels were significantly higher in expired patients (p < 0.0001). Total (p< 0.0001), direct (p< 0.0001) and indirect (p< 0.0001) bilirubin levels, NIHSS score (p< 0.0001), and ischemic area (p< 0.0001) significantly predicted the outcome in these patients.

Conclusion: Total, direct and indirect bilirubin levels was significantly associated with mortality in the acute phase of ischemic stroke patients.

Heme Oxygenase-1: Clinical Relevance in Ischemic Stroke

Stroke is the second-leading cause of death and a leading cause of serious long-term disability worldwide, with an increasing global burden due to the growing and aging population. However, strict eligibility criteria for current treatment opportunities make novel therapeutic approaches desirable. Oxidative stress plays a pivotal role during cerebral ischemia, eventually leading to neuronal injury and cell death. The significant correlation between redox imbalance and ischemic stroke has led to various treatment strategies targeting the endogenous antioxidant system in order to ameliorate the adverse prognosis in patients with cerebral infarction. One of the most extensively investigated cellular defense pathway in this regard is the Nrf2-heme oxygenase-1 (HO-1) axis. In this review, our aim is to focus on the potential clinical relevance of targeting the HO-1 pathway in ischemic stroke.

The effects of additional ezetimibe treatment to baseline rosuvastatin on circulating PCSK9 among patients with stable angina

BACKGROUND

Blood lipid management is one of the effective strategies for coronary heart disease, and statins are the first-line lipid-lowering drugs. Low density lipoprotein cholesterol (LDL-C) drop brings about cardioprotective effects. Proprotein convertase subtilisin kexin type 9 (PCSK9) is known to increase LDL-C, thus hazarding LDL-C reduction-induced benefits. To date, how PCSK9 responds to various lipid-lowering strategies has not been fully clarified.

METHODS

This study involves patients with stable angina and aims to explore and clarify the short-term impacts of rosuvastatin and ezetimibe, alone or in combination, on circulating PCSK9. A total of 68 patients with stable angina were enrolled and 60 eligible patients were randomly assigned into 3 groups (20 subjects in each). Patients in different groups were treated for a period of 14 days with rosuvastatin 10 mg/d, ezetimibe 10 mg/d, and rosuvastatin 10 mg/d plus ezetimibe 10 mg/d, respectively. Concentrations of blood LDL-C and PCSK9 levels were measured at baseline and at the 14^th day after treatment.

RESULTS

Both rosuvastatin and ezetimibe could reduce the LDL-C levels, and rosuvastatin displayed a stronger cholesterol-lowering effect than ezetimibe. Moreover, when combined, they yielded even greater efficacy in lowering LDL-C, as compared with either rosuvastatin or ezetimibe mono-treatment (P<0.05). Rosuvastatin therapy (alone or combined with ezetimibe) caused significant rise in circulating PCSK9. Nevertheless, no significant growth of PCSK9 levels (P=0.558) was observed during ezetimibe treatment. At the 14^th day, no difference in PCKS9 levels was observed between the rosuvastatin group and the combination-therapy group (P=0.906).

CONCLUSIONS

Rosuvastatin plus ezetimibe therapy is more effective in reducing LDL-C levels as compared with either rosuvastatin or ezetimibe mono-medication. Meanwhile, such combination strategy does not further increase the levels of circulating PCSK9 compared to rosuvastatin mono-intervention, thus maintaining maximal clinical benefits from lipid-lowering.

Heme Oxygenases in Cardiovascular Health and Disease

Heme oxygenases are composed of two isozymes, Hmox1 and Hmox2, that catalyze the degradation of heme to carbon monoxide (CO), ferrous iron, and biliverdin, the latter of which is subsequently converted to bilirubin. While initially considered to be waste products, CO and biliverdin/bilirubin have been shown over the last 20 years to modulate key cellular processes, such as inflammation, cell proliferation, and apoptosis, as well as antioxidant defense. This shift in paradigm has led to the importance of heme oxygenases and their products in cell physiology now being well accepted. The identification of the two human cases thus far of heme oxygenase deficiency and the generation of mice deficient in Hmox1 or Hmox2 have reiterated a role for these enzymes in both normal cell function and disease pathogenesis, especially in the context of cardiovascular disease. This review covers the current knowledge on the function of both Hmox1 and Hmox2 at both a cellular and tissue level in the cardiovascular system. Initially, the roles of heme oxygenases in vascular health and the regulation of processes central to vascular diseases are outlined, followed by an evaluation of the role(s) of Hmox1 and Hmox2 in various diseases such as atherosclerosis, intimal hyperplasia, myocardial infarction, and angiogenesis. Finally, the therapeutic potential of heme oxygenases and their products are examined in a cardiovascular disease context, with a focus on how the knowledge we have gained on these enzymes may be capitalized in future clinical studies.

Changes in oxidized lipids drive the improvement in monocyte activation and vascular disease after statin therapy in HIV

BACKGROUND

Oxidative stress plays a significant role in atherosclerosis development. HIV infection has been linked with heightened cardiovascular disease risk. HMG-CoA reductase inhibitors may reduce oxidative stress and subsequently subclinical vascular disease in HIV.

DESIGN/METHODS

This is a randomized, placebo-controlled trial to evaluate the effect of rosuvastatin in HIV-infected adults on stable antiretroviral therapy with low-density lipoprotein less than 130  mg/dl and increased inflammation or T-cell activation on subclinical vascular disease. Changes over 48 weeks in oxidative stress markers, oxidized low-density lipoprotein (oxLDL) and F2-isoprostane/creatinine ratio (F2-IsoP/Cr), were compared between groups. Spearman correlation and multivariable linear regression were used to evaluate relationships between changes in markers of oxidative stress, inflammation and monocyte activation and carotid intima media thickness (CIMT).

RESULTS

One hundred and forty-seven adults enrolled (72 to rosuvastatin and 75 to placebo). In the rosuvastatin group, oxLDL decreased significantly over 24 weeks compared to placebo [mean absolute change in log-oxLDL for rosuvastatin -0.2  ±  0.468 log U/l (P < 0.001 within-group) vs. placebo -0.018  ±  0.456 log U/l (P = 0.83 within-group); P = 0.004 between groups] and this change was linked with changes in soluble CD14 and proportion of patrolling monocytes (CD14dimCD16). Although oxLDL levels increased after initially declining and were not different from placebo at week 48, the early improvement in oxLDL was associated with improved CIMT at week 48. Changes in F2-IsoP/Cr were not significant between groups.

CONCLUSION

Rosuvastatin decreases oxLDL levels early after initiation and is associated with decreased monocyte activation. Early improvement in oxLDL is linked with improved CIMT in treated HIV infection.