The statin-iron nexus: anti-inflammatory intervention for arterial disease prevention

Atorvastatin exerts dual effects of lesion regression and ovarian protection in the prevention and treatment of endometriosis

Endometriosis is a frequent, chronic, estrogen-dependent and inflammatory gynecological disease leading to pain and infertility. Clinical and metabolic studies reveal that patients with endometriosis are susceptible to hyperlipemia and lipid dysfunction, putting them at ascending risk of cardiovascular diseases. Statins constitute a group of cholesterol-lowering drugs with pleiotropic effects. A plethora of researches have proved their ability to inhibit the growth of ectopic lesions in endometriosis. However, concerns exist about their possible adverse effects on ovarian function. This study aimed to investigate the possible effect of atorvastatin on the ovarian endocrine function and fertility capacity in the prevention and treatment of endometriosis. Here, 5 mg/kg atorvastatin was intraperitoneally injected to the endometriosis mice once a day for consecutive fourteen days during and after the development of endometriotic implants. The results indicated that atorvastatin not only led to regression of the ectopic lesions, but also caused no discernible harm to the ovary for both the preventive and the therapeutic models. In addition, it elicited a protective effect on the ovarian reserve and fertility possibly by reducing inflammation in the ovary. Hence, atorvastatin could be a promising drug for endometriosis prevention and treatment.

Possible link between statin and iron deficiency anemia: A South Korean nationwide population-based cohort study

An extensive evaluation of disease occurrence after statin use based on a "hypothesis-free" approach remains scarce. To examine the effect of statin use on the potential risk of developing diseases, a propensity score-matched cohort study was executed using data from the National Sample Cohort in South Korea. A total of 7847 statin users and 39,235 nonstatin users were included in the final analysis. The period of statin use was defined as our main time-dependent exposure and was divided into three periods: current, recent, and past. The main outcomes were defined as new-onset diseases with ≥100 events based on the International Statistical Classification of Diseases, 10th Revision. We calculated the adjusted hazard ratios and 95% confidence intervals (CIs) using Cox regression. We found that statin use significantly increased the risk of developing iron deficiency anemia up to 5.04 times (95% CI, 2.11 to 12.03). Therefore, the iron levels of patients using statins should be monitored carefully.

Prevalence of Anemia and Associated All-Cause Mortality Among Adults With Diabetes: The Role of Chronic Kidney Disease

AIMS

Among adults with diabetes in the United States, we evaluated anemia prevalence by CKD status as well as the role of CKD and anemia, as potential risk factors for all-cause mortality.

METHODS

In a retrospective cohort study, we included 6,718 adult participants with prevalent diabetes from the 2003-March 2020 National Health and Nutrition Examination Survey (NHANES), a nationally representative sample of the non-institutionalized civilian population in the United States. Cox regression models evaluated the role of anemia and CKD, alone or combined, as predictors of all-cause mortality.

RESULTS

Anemia prevalence among adults with diabetes and CKD was 20%. Having anemia or CKD alone, compared with having neither condition, was significantly associated with all-cause mortality (anemia: HR=2.10 [1.49-2.96], CKD: HR=2.24 [1.90-2.64]). Having both conditions conferred a greater potential risk (HR=3.41 [2.75-4.23]).

CONCLUSIONS

Approximately one-quarter of the adult US population with diabetes and CKD also has anemia. The presence of anemia, with or without CKD, is associated with a two- to threefold increased risk of death by compared with adults who have neither condition, suggesting that anemia may be a strong predictor of death among adults with diabetes.

Ironing out macrophages in atherosclerosis

<p indent="0mm">The most common cause of death worldwide is atherosclerosis and related cardiovascular disorders. Macrophages are important players in the pathogenesis of atherosclerosis and perform critical functions in iron homeostasis due to recycling iron by phagocytosis of senescent red blood cells and regulating iron availability in the tissue microenvironment. With the growth of research on the "iron hypothesis" of atherosclerosis, macrophage iron has gradually become a hotspot in the refined iron hypothesis. Macrophages with the M1, M2, M(Hb), Mox, and other phenotypes have been defined with different iron-handling capabilities related to the immune function and immunometabolism of macrophages, which influence the progression of atherosclerosis. In this review, we focus on macrophage iron and its effects on the development of atherosclerosis. We also cover the contradictory discoveries and propose a possible explanation. Finally, pharmaceutical modulation of macrophage iron is discussed as a promising target for atherosclerosis therapy.</p>.

The Effects of Statin Treatment on Serum Ferritin Levels: A Systematic Review and Meta-Analysis

BACKGROUND

Statins are the most widely used drugs for decreasing elevated serum LDL-cholesterol (LDL-C) and thus for the prevention of atherosclerotic cardiovascular disease (ASCVD), but they have also some pleiotropic effects, including anti-inflammatory properties. Atherosclerosis is a low-grade inflammatory disease, and elevated ferritin is considered to be one of the markers of inflammation. Since the results of studies on the effects of statins on serum ferritin levels are conflicting, this meta-analysis was performed.

METHODS

A literature search was performed using major electronic databases (MEDLINE/PubMed, Scopus, Embase, and ISI Web of Science) from inception up to 5 March 2022 to find studies evaluating the effect of different statins on serum ferritin levels. The effect size was determined using weighted mean differences (WMDs) and the corresponding 95% confidence intervals (CIs).

RESULTS

The meta-analysis of nine studies (1611 patients) analyzing the effects of statins on serum ferritin levels that were included showed a significant decrease in circulating ferritin levels caused by statins. The results did not suggest any significant association between the changes in concentrations of serum ferritin and the duration of treatment with statins.

CONCLUSIONS

Statin therapy decreases the circulating concentrations of ferritin, which might be beneficial for the prevention and/or progression of ASCVD. This effect might be explained by the anti-inflammatory effects and maybe some other pleiotropic effects of statins and not by their lipid-lowering effects.

Associations between Genetically Proxied Inhibition of Lipid-Lowering Drug Targets and Serum Micronutrients among Individuals of European Descent: A Mendelian Randomization Study

BACKGROUND

Limited and inconclusive data exist concerning the associations between lipid-lowering drugs and serum micronutrient concentrations.

METHODS

We conducted Mendelian randomization (MR) analyses to explore the associations between lipid-lowering drug targets and serum micronutrients. Single-nucleotide polymorphisms in genes encoding molecular targets of LDL cholesterol-lowering therapies were selected as instrumental variables for 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR; target of statins), proprotein convertase subtilisin/kexin type 9 (PCSK9; target of PCSK9 inhibitors), and Niemann-Pick C1-Like 1 (NPC1L1; target of ezetimibe). Exposure data were extracted from a published genome-wide association study (GWAS) of lipids in 188,577 European individuals, with outcome data obtained from the Integrative Epidemiology Unit (IEU) GWAS database (https://gwas.mrcieu.ac.uk). Overall, age and sex information were not calculable from the summary-level GWAS data. MR analyses were performed using the inverse-variance weighted method and MR sensitivity analysis methods.

RESULTS

We found genetically proxied inhibition of HMGCR to lower iron (effect, -0.16; 95% CI: -0.27, -0.06; P value = 0.003), zinc (effect, -0.83; 95% CI: -1.36, -0.31; P value = 0.002), magnesium (effect, -0.17; 95% CI: -0.27, -0.06; P value = 0.003), potassium (effect, -0.17; 95% CI: -0.27, -0.06; P value = 0.002), genetically proxied inhibition of NPC1L1 to increase calcium (effect, 0.28; 95% CI: 0.10, 0.46; P value = 0.003), retinol (effect, 0.25; 95% CI: 0.07, 0.44; P value = 0.01), and genetically proxied inhibition of PCSK9 to increase vitamin D (effect, 0.10; 95% CI: 0.07, 0.12; P value = 1.8 × 10-19). These associations were robust in MR sensitivity analyses. However, the associations between genetically proxied inhibition of HMGCR and NPC1L1 and the micronutrients were not consistent in multiple comparisons.

CONCLUSIONS

Our results provide evidence that statin use may lower serum concentrations of iron, zinc, magnesium, and potassium, PCSK9 inhibitors may increase serum vitamin D, and ezetimibe may increase serum calcium and retinol concentrations.

Optimal serum ferritin level range: iron status measure and inflammatory biomarker

This report provides perspectives concerning dual roles of serum ferritin as a measure of both iron status and inflammation. We suggest benefits of a lower range of serum ferritin as has occurred for total serum cholesterol and fasting blood glucose levels. Observations during a prospective randomized study using phlebotomy in patients with peripheral arterial disease offered unique insights into dual roles of serum ferritin both as an iron status marker and acute phase reactant. Robust positive associations between serum ferritin, interleukin 6 [IL-6], tissue necrosis factor-alpha, and high sensitivity C-reactive protein were discovered. Elevated serum ferritin and IL-6 levels associated with increased mortality and with reduced mortality at ferritin levels <100 ng mL-1. Epidemiologic studies demonstrate similar outcomes. Extremely elevated ferritin and IL-6 levels also occur in individuals with high mortality due to SARS-CoV-2 infection. Disordered iron metabolism reflected by a high range of serum ferritin level signals disease severity and outcomes. Based upon experimental and epidemiologic data, we suggest testing the hypotheses that optimal ferritin levels for cardiovascular mortality reduction range from 20 to 100 ng mL-1 with % transferrin levels from 20 to 50%, to ensure adequate iron status and that ferritin levels above 194 ng mL-1 associate with all-cause mortality in population cohorts.

Fatty acids: facts vs. fiction

During the last 100 years official dietary guidelines have recommended an increased consumption of fats derived from seeds while decreasing the consumption of traditional fats, especially saturated fats. These recommendations are being challenged by recent studies. Furthermore, the increased use of refining processes in fat production had deleterious health effects. Today, the number of high-quality studies on fatty acids is large enough to make useful recommendations on clinical application and everyday practice. Saturated fats have many beneficial functions and palmitic acid appears to be problematic only when it is synthesized due to excess fructose consumption. Trans fatty acids were shown to be harmful when they are manmade but beneficial when of natural origin. Conjugated linoleic acid has many benefits but the isomer mix that is available in supplement form differs from its natural origin and may better be avoided. The ω3 fatty acid linolenic acid has rather limited use as an anti-inflammatory agent - a fact that is frequently overlooked. On the other hand, the targeted use of long chain ω3 fatty acids based on blood analysis has great potential to supplement or even be an alternative to various pharmacological therapies. At the same time ω6 fatty acids like linoleic acid and arachidonic acid have important physiological functions and should not be avoided but their consumption needs to be balanced with long chain ω3 fatty acids. The quality and quantity of these fats together with appropriate antioxidative protection are critical for their positive health effects.

Potential hazards of recent trends in liberal iron use for renal anemia

A randomized controlled trial,the Proactive IV Iron Therapy in Haemodialysis Patients (PIVOTAL), has recently shown that a high-dose (‘proactive’) intravenous iron regimen was superior to a low-dose (‘reactive’) regimen for hemodialysis patient outcomes and overall safety. However, even in the low-dose group, a substantial amount of iron was administered to maintain serum ferritin >200 ng/mL. This type of comparison may have strongly affected the safety results. Iron has two opposite effects on erythropoiesis: it activates erythroid differentiation directly by supplying iron but inhibits it indirectly by stimulating hepcidin and enhancing oxidative stress. Hepcidin plays an essential role not only in iron homeostasis and the anemia of chronic kidney disease, but also in its complications such as atherosclerosis and infection. Its main stimulation by iron—and to a lesser degree by inflammation—should urge clinicians to avoid prescribing excessive amounts of iron. Furthermore, as serum ferritin is closely correlated with serum hepcidin and iron storage, it would seem preferable to rely mainly on serum ferritin to adjust iron administration, defining an upper limit for risk reduction. Based on our estimations, the optimal range of serum ferritin is ∼50–150 ng/mL, which is precisely within the boundaries of iron management in Japan. Considering the contrasting ranges of target ferritin levels between end-stage renal disease patients in Japan and the rest of the world, the optimal range proposed by us will probably be considered as unacceptable by nephrologists abroad. Only well-balanced, randomized controlled trials with both erythropoiesis-stimulating agents and iron will allow us to settle this controversy.

Impact of trial design and patient heterogeneity on the identification of clinically effective therapies for progressive MS

Clinically effective immunomodulatory therapies have been developed for relapsing-remitting multiple sclerosis (RRMS), but they have generally not translated to a corresponding slowing of disability accumulation in progressive forms of multiple sclerosis (MS). Since disability is multifaceted, progressive patients are heterogeneous, and the drivers of disease progression are still unclear, it has been difficult to identify the most informative outcome measures for progressive trials. Historically, secondary outcome measures have focused on inflammatory measures, which contributed to the recent identification of immunomodulatory therapies benefiting younger patients with more inflammatory progressive MS. Meanwhile, agents capable of treating late-stage disease have remained elusive. Consequently, measures of neurodegeneration are becoming common. Here, we review completed clinical trials testing immunomodulatory therapies in primary progressive multiple sclerosis (PPMS) or secondary progressive multiple sclerosis (SPMS) and discuss the features contributing to trial design variability in relation to trial outcomes, and how efforts toward better patient stratification and inclusion of reliable progression markers could improve outcomes.

Iron reduction response and demographic differences between diabetics and non-diabetics with cardiovascular disease entered into a controlled clinical trial

Filings of elemental iron separated magnetically from a homogenate of breakfast cereal implicated in the risk of cardiovascular disease and diabetes.

Deferoxamine stimulates LDLR expression and LDL uptake in HepG2 cells

SCOPE

Iron overload contributes to the pathogenesis of atherosclerosis and iron chelators are beneficial through their antioxidant properties. Hepatic iron loading increases cholesterol synthesis. Whether iron depletion could affect hepatic cholesterol metabolism is unknown.

METHODS AND RESULTS

We examined the effect of the iron chelator deferoxamine (DFO) on mRNA expression of genes involved in cholesterol metabolism and/or cholesterol uptake. Our results revealed that DFO increases LDL receptor (LDLR) mRNA levels in human hepatocyte-derived cell lines HepG2 and Huh7 cells, and in K562 cells. In HepG2 cells, we observed that DFO increases (i) LDLR-mRNA levels in a time- and dose-dependent manner, (ii) LDLR-protein levels; (iii) cell surface LDLR; and (iv) LDL uptake. In contrast, the mRNA levels of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, sterol regulatory element-binding proteins, and the mRNA/protein levels of proprotein convertase subtilisin-kexin 9 were not modulated by DFO, suggesting that the LDLR regulation by DFO is not at the transcriptional or posttranslational levels. Since LDLR-mRNA was stabilized by DFO, a posttranscriptional mechanism is suggested for the DFO-mediated upregulation of LDLR.

CONCLUSION

DFO induced an increase in LDLR expression by a posttranscriptional mechanism resulting in an enhancement of LDL uptake in HepG2 cells, suggesting increased LDLR activity as one of the underlying causes of the hypocholesterolemic effect of iron reduction.

Iron and noncontrast magnetic resonance T2* as a marker of intraplaque iron in human atherosclerosis

OBJECTIVE

Iron has been implicated in atherogenesis and plaque destabilization, whereas less is known about iron-related proteins in this disease. We compared ex vivo quantities with in vivo vessel wall T2*, which is a noncontrast magnetic resonance relaxation time that quantitatively shortens with increased tissue iron content. We also tested the hypothesis that patients with carotid atherosclerosis have abnormal T2* times vs controls that would help support a role for iron in human atherosclerosis.

METHODS

Forty-six patients undergoing carotid endarterectomy and 14 subjects without carotid disease were prospectively enrolled to undergo carotid magnetic resonance imaging. Ex vivo measurements were performed on explanted plaque and 17 mammary artery samples.

RESULTS

Plaques vs normal arteries had higher levels of ferritin (median, 7.3 [interquartile range (IQR), 4-13.8] vs 1.0 [IQR, 0.6-1.3] ng/mg; P < .001) and oxidized low-density lipoprotein (median, 0.17 [IQR, 0.12-0.30] vs 0.01 [IQR, 0.003-0.03] ng/mg; P < .001) as well as hepcidin (median, 8.7 [IQR, 4.6-12.4] vs 2.6 [IQR, 1.3-7.0] ng/mL; P = .03); serum hepcidin levels did not distinguish atherosclerosis patients from controls (median, 40.6 [IQR, 18.8-88.6] vs 33.9 [IQR, 17.6-55.2]; P = .42). Shorter in vivo T2* paralleled larger plaque volume (ρ = -.44; P = .01), and diseased arteries had shorter T2* values compared with controls (median, 17.7 ± 4.3 vs 23.0 ± 2.4 ms; P < .001).

CONCLUSIONS

Diseased arteries have greater levels of iron-related proteins ex vivo and shorter T2* times in vivo. Further studies should help define the role of T2* as a biomarker of iron and atherosclerosis.

Iron, inflammation and atherosclerosis risk in men vs. perimenopausal women

OBJECTIVE

Age at first atherosclerotic event is typically older for women vs. men; monthly iron loss has been postulated to contribute to this advantage. We investigated the relationship between an MRI-based arterial wall biomarker and the serum inflammatory biomarker high-sensitivity C-reactive protein (hsCRP) in perimenopausal women vs. men.

METHODS AND RESULTS

Women without evident atherosclerotic disease were prospectively enrolled and observed over 24 months of menopause transition, indicated by hormone levels and reduction in median number of menstrual cycles from 4 [3-6] per year to 0 [0-1] per year (P < 0.01). Higher hsCRP predicted shorter carotid artery wall T2* in women entering the menopause transition (r = -0.3139, P = 0.0014); this relationship weakened after 24 months of perimenopause in women (r = -0.1718, P = 0.0859) and was not significant in a cohort of men matched for age and cardiovascular risk category (r = -0.0310, P = 0.8362). Serum ferritin increased from baseline to 24-month follow-up during women's menopause transition (37 [20-79] to 67 [36-97] ng/mL, P < 0.01), but still remained lower compared to men (111 [45-220] ng/mL, P < 0.01). Circulating ferritin levels correlated with arterial wall T2* values in women at baseline (r = -0.3163, P = 0.0013) but not in women after 24 months (r = -0.0730, P = 0.4684) of menopause transition nor in men (r = 0.0862, P = 0.5644).

CONCLUSIONS

An arterial wall iron-based imaging biomarker reflects degree of systemic inflammation in younger women, whereas this relationship is lost as women transition through menopause to become more similar to men. Iron homeostasis and inflammation in the arterial wall microenvironment warrants further investigation as a potential early target for interventions that mitigate atherosclerosis risk.

Metabolic alterations, HFE gene mutations and atherogenic lipoprotein modifications in patients with primary iron overload

HFE gene mutations contributed to a decrease of insulin secretion, an atherogenic LDL subfraction distribution and altered LDL and HDL particles in patients with iron overload. It remains to be determined whether these alterations contribute to cardiovascular risk.

Serum ferritin is an important inflammatory disease marker, as it is mainly a leakage product from damaged cells

"Serum ferritin" presents a paradox, as the iron storage protein ferritin is not synthesised in serum yet is to be found there. Serum ferritin is also a well known inflammatory marker, but it is unclear whether serum ferritin reflects or causes inflammation, or whether it is involved in an inflammatory cycle. We argue here that serum ferritin arises from damaged cells, and is thus a marker of cellular damage. The protein in serum ferritin is considered benign, but it has lost (i.e. dumped) most of its normal complement of iron which when unliganded is highly toxic. The facts that serum ferritin levels can correlate with both disease and with body iron stores are thus expected on simple chemical kinetic grounds. Serum ferritin levels also correlate with other phenotypic readouts such as erythrocyte morphology. Overall, this systems approach serves to explain a number of apparent paradoxes of serum ferritin, including (i) why it correlates with biomarkers of cell damage, (ii) why it correlates with biomarkers of hydroxyl radical formation (and oxidative stress) and (iii) therefore why it correlates with the presence and/or severity of numerous diseases. This leads to suggestions for how one might exploit the corollaries of the recognition that serum ferritin levels mainly represent a consequence of cell stress and damage.

Evidence that multiple defects in lipid regulation occur before hyperglycemia during the prodrome of type-2 diabetes

BACKGROUND

Blood-vessel dysfunction arises before overt hyperglycemia in type-2 diabetes (T2DM). We hypothesised that a metabolomic approach might identify metabolites/pathways perturbed in this pre-hyperglycemic phase. To test this hypothesis and for specific metabolite hypothesis generation, serum metabolic profiling was performed in young women at increased, intermediate and low risk of subsequent T2DM.

METHODS

Participants were stratified by glucose tolerance during a previous index pregnancy into three risk-groups: overt gestational diabetes (GDM; n = 18); those with glucose values in the upper quartile but below GDM levels (UQ group; n = 45); and controls (n = 43, below the median glucose values). Follow-up serum samples were collected at a mean 22 months postnatally. Samples were analysed in a random order using Ultra Performance Liquid Chromatography coupled to an electrospray hybrid LTQ-Orbitrap mass spectrometer. Statistical analysis included principal component (PCA) and multivariate methods.

FINDINGS

Significant between-group differences were observed at follow-up in waist circumference (86, 95%CI (79-91) vs 80 (76-84) cm for GDM vs controls, p<0.05), adiponectin (about 33% lower in GDM group, p = 0.004), fasting glucose, post-prandial glucose and HbA1c, but the latter 3 all remained within the 'normal' range. Substantial differences in metabolite profiles were apparent between the 2 'at-risk' groups and controls, particularly in concentrations of phospholipids (4 metabolites with p ≤ 0.01), acylcarnitines (3 with p ≤ 0.02), short- and long-chain fatty acids (3 with p<  = 0.03), and diglycerides (4 with p ≤ 0.05).

INTERPRETATION

Defects in adipocyte function from excess energy storage as relatively hypoxic visceral and hepatic fat, and impaired mitochondrial fatty acid oxidation may initiate the observed perturbations in lipid metabolism. Together with evidence from the failure of glucose-directed treatments to improve cardiovascular outcomes, these data and those of others indicate that a new, quite different definition of type-2 diabetes is required. This definition would incorporate disturbed lipid metabolism prior to hyperglycemia.

Iron and atherosclerosis: nailing down a novel target with magnetic resonance

Iron is an essential mineral in many proteins and enzymes in human physiology, with limited means of iron elimination to maintain iron balance. Iron accrual incurs various pathological mechanisms linked to cardiovascular disease. In atherosclerosis, iron catalyzes the creation of reactive oxygen free radicals that contribute to lipid modification, which is essential to atheroma formation. Inflammation further fuels iron-related pathologic processes associated with plaque progression. Given iron's role in atherosclerosis development, in vivo detection techniques sensitive iron are needed for translational studies targeting iron for earlier diagnosis and treatment. Magnetic resonance imaging is uniquely able to quantify iron in human tissues noninvasively and without ionizing radiation, offering appealing for longitudinal and interventional studies. Particularly intriguing is iron's complementary biology vs. calcium, which is readily detectable by computed tomography. This review summarizes the role of iron in atherosclerosis with considerable implications for novel diagnostic and therapeutic approaches.

Iron: protector or risk factor for cardiovascular disease? Still controversial

Iron is the second most abundant metal in the Earth’s crust. Despite being present in trace amounts, it is an essential trace element for the human body, although it can also be toxic due to oxidative stress generation by the Fenton reaction, causing organic biomolecule oxidation. This process is the basis of numerous pathologies, including cardiovascular diseases (CVD). The relationship between iron and cardiovascular disease was proposed in 1981 by Jerome Sullivan. Since then, numerous epidemiological studies have been conducted to test this hypothesis. The aim of this review is to present the main findings of the chief epidemiological studies published during the last 32 years, since Sullivan formulated his iron hypothesis, suggesting that this element might act as a risk factor for cardiovascular disease. We have analyzed 55 studies, of which 27 supported the iron hypothesis, 20 found no evidence to support it and eight were contrary to the iron hypothesis. Our results suggest that there is not a high level of evidence which supports the hypothesis that the iron may be associated with CVD. Despite the large number of studies published to date, the role of iron in cardiovascular disease still generates a fair amount of debate, due to a marked disparity in results.