The many roles of statins in ischemic stroke

Nanomolar therapeutic concentrations of statins rapidly induce cerebral artery vasoconstriction by stimulating L-type calcium channels

All commonly prescribed statins have been reported to cause reversible memory loss within weeks of therapy, though the exact molecular mechanism remains unknown. However, whether therapeutic concentrations of statins can directly regulate the contractility of resistance cerebral arteries that control cerebrovascular perfusion remains unexplored. Here, we examined the acute vascular effects of statins on rat cerebral arteries and the underlying molecular mechanisms. Our pressure myography data demonstrate that, at therapeutically-relevant nanomolar concentrations, statins produced a robust and rapid vasoconstriction, appearing within 2-3 min of drug application. Interestingly, such vasoconstriction was largely absent in female rat cerebral arteries. Endothelial denudation or mevalonate supplementation did not alter statin-induced vasoconstriction, suggesting an endothelium- and cholesterol-independent mechanism. In contrast, such vasoconstriction was abolished upon removal of extracellular Ca2+, pharmacological blockade of the smooth muscle cell voltage-gated Ca2+ channel, CaV1.2, or siRNA knockdown of CaV1.2 - all of which reduced [Ca2+]i, indicating that Ca2+ entry through CaV1.2 plays a critical role in cerebral artery vasoconstriction. Arterial biotinylation revealed that acute statin exposure did not alter the surface expression, distribution, or function of CaV1.2 channels. Altogether, our data unveil an unexpected role of statins in rapidly inducing constriction of resistance cerebral arteries by directly stimulating CaV1.2 in smooth muscle cells. These findings offer a plausible explanation for statin-associated reversible memory impairment, its mitigation by calcium channel blockers, and why such effects may not be observed in all subjects, particularly those concurrently taking antihypertensive agents.

Simvastatin is delivered to the brain by high-strength intranasal cationic SMEDDS and nanoemulsions

The repurposing of statins as neuroprotective agents and/or anti-brain tumor drugs is limited by challenges in brain bioavailability and systemic off-target effects. Therefore, improved and targeted delivery of statins to the brain is necessary. This study aimed to develop a high-strength liquid formulation of the poorly soluble prodrug simvastatin for intranasal administration, as a strategy to achieve high brain concentrations of the prodrug and/or its active form, tenivastatin. Cationic simvastatin nanoemulsions (c-NE) and self-microemulsifying drug delivery systems (c-SMEDDS) were screened for composition, extensively characterized, and the viscosity of the nanoemulsion was further optimized. The optimized c-NE and c-SMEDDS formulations achieved high drug strengths, approximately 5.5% and 9% (w/w), respectively. They formed highly homogeneous aqueous dispersions (polydispersity index < 0.1) with small droplet sizes (< 120 nm and ~ 25 nm, respectively) and remained stable for at least four months under refrigeration. Neither the c-NE nor the c-SMEDDS induced hemolysis up to concentrations of 40 µg/mL and 450 µg/mL of simvastatin, respectively. The zero-shear viscosity of the c-NE was increased to 186 mPa·s by incorporating 0.25% (w/w) polyvinylpyrrolidone, which approached the viscosity of the c-SMEDDS (~ 126 mPa·s). Following intranasal administration of the optimized formulations to Wistar rats at a dose of 10 mg/kg, simvastatin levels in the brain reached 50 to 150 ng/g between 15 and 60 min post-administration. These findings indicate that the developed c-NE and c-SMEDDS formulations hold promise for simvastatin intranasal delivery and brain targeting, potentially paving the way for the realization of simvastatin's neuroprotective potential.

Evolving Clinical-Translational Investigations of Cerebroprotection in Ischemic Stroke

Ischemic stroke is a highly morbid disease, with over 50% of large vessel stroke (middle cerebral artery or internal carotid artery terminus occlusion) patients suffering disability despite maximal acute reperfusion therapy with thrombolysis and thrombectomy. The discovery of the ischemic penumbra in the 1980s laid the foundation for a salvageable territory in ischemic stroke. Since then, the concept of neuroprotection has been a focus of post-stroke care to (1) minimize the conversion from penumbra to core irreversible infarct, (2) limit secondary damage from ischemia-reperfusion injury, inflammation, and excitotoxicity and (3) to encourage tissue repair. However, despite multiple studies, the preclinical-clinical research enterprise has not yet created an agent that mitigates post-stroke outcomes beyond thrombolysis and mechanical clot retrieval. These translational gaps have not deterred the scientific community as agents are under continuous investigation. The NIH has recently promoted the concept of cerebroprotection to consider the whole brain post-stroke rather than just the neurons. This review will briefly outline the translational science of past, current, and emerging breakthroughs in cerebroprotection and use of these foundational ideas to develop a novel paradigm for optimizing stroke outcomes.

Cross-talk between bioactive lipid mediators and the unfolded protein response in ischemic stroke

Ischemic cerebral stroke is a severe medical condition that affects about 15 million people every year and is the second leading cause of death and disability globally. Ischemic stroke results in neuronal cell death and neurological impairment. Current therapies may not adequately address the deleterious metabolic changes and may increase neurological damage. Oxygen and nutrient depletion along with the tissue damage result in endoplasmic reticulum (ER) stress, including the Unfolded Protein Response (UPR), and neuroinflammation in the affected area and cause cell death in the lesion core. The spatio-temporal production of lipid mediators, either pro-inflammatory or pro-resolving, decides the course and outcome of stroke. The modulation of the UPR as well as the resolution of inflammation promotes post-stroke cellular viability and neuroprotection. However, studies about the interplay between the UPR and bioactive lipid mediators remain elusive and this review gives insights about the crosstalk between lipid mediators and the UPR in ischemic stroke. Overall, the treatment of ischemic stroke is often inadequate due to lack of effective drugs, thus, this review will provide novel therapeutical strategies that could promote the functional recovery from ischemic stroke.

Cardiolipin-Mediated Alleviation of Mitochondrial Dysfunction Is a Neuroprotective Effect of Statin in Animal Model of Ischemic Stroke

In clinical settings, the benefit of statin for stroke is debatable as regular statin users may suffer from myalgia, statin-associated myopathy (SAM), and rarely rhabdomyolysis. Studies suggest that patients on statin therapy show lesser vulnerability toward ischemic stroke and post-stroke frailty. Both pre- and post-treatment benefits of statin have been reported as evident by its neuroprotective effects in both cases. As mitochondrial dysfunction following stroke is the fulcrum for neuronal death, we hereby explore the role of statin in alleviating mitochondrial dysfunction by regulating the mitochondrial dynamics. In the present study, we intend to evaluate the role of statin in modulating cardiolipin-mediated mitochondrial functionality and further providing a therapeutic rationale for repurposing statins either as preventive or an adjunctive therapy for stroke.

Suppressive role of lovastatin in intracerebral hemorrhage through repression of autophagy

Statins possess critical function in the brain. Here, we intended to investigate the role of lovastatin in brain damage after intracerebral hemorrhage (ICH). A collagenase-induced ICH rat model was established followed by lovastatin treatment. Then, the effect of lovastatin on ICH-induced brain damage was explored with cognitive function, learning and memory abilities, and neurological damage of rats analyzed. Besides, brain water content, number of degenerate neurons, Nissl's body, and apoptosis of neurons were detected. Oxidative stress levels, inflammation, and autophagy levels in ICH were measured after treatment of lovastatin. Lovastatin improved the cognitive impairment of rats, enhanced their spatial learning and memory abilities, reduced nervous system damage, lesion area, and brain water content after ICH. Lovastatin was capable of reducing the number of degenerated neurons, the apoptosis level, autophagy level, and increasing the number of Nissl's body. Lovastatin inhibited the oxidative stress response and inflammatory factors in the brain tissue after ICH, and increased the expression of anti-inflammatory factor IL-10. Lovastatin inhibited AMPK/mTOR signaling pathway after ICH. Our study highlighted the suppressive role of lovastatin in ICH-induced brain damage.

Simvastatin alleviates epithelial‑mesenchymal transition and oxidative stress of high glucose‑induced lens epithelial cells in vitro by inhibiting RhoA/ROCK signaling

Diabetic cataracts (DC) is one of the main causes of blindness among patients with diabetes mellitus. The aim of the present study was to examine the effect of simvastatin on lens epithelial cells in DC and the underlying mechanism. The viability of SRA01/04 cells treated with different concentrations of simvastatin was detected using a Cell Counting Kit-8 assay before and after high glucose (HG) treatment. The expression levels of E-cadherin, N-cadherin, Vimentin and α-smooth muscle actin (α-SMA), proteins associated with epithelial-mesenchymal transition (EMT), in addition to RhoA, Rho-associated kinases (ROCK)1 and ROCK2, proteins related to RhoA/ROCK signaling, were also measured in SRA01/04 cells treated with HG and simvastatin, with or without U46619, using western blot analysis. DCFH-DA dyes, superoxide dismutase (SOD) and glutathione (GSH)/glutathione disulfide (GSSG) kits were used to measure the levels of oxidative stress parameters in SRA01/04 cells treated with HG and simvastatin with or without U46619. The cell viability of SRA01/04 cells treated with simvastatin was found to be significantly elevated after HG treatment. The protein expression levels of E-cadherin were increased but those of N-cadherin, Vimentin and α-SMA decreased after HG and simvastatin treatment, and this was reversed by U46619. The levels of SOD and GSH-GSSG were found to be increased whereas reactive oxygen species levels were decreased, effects that were reversed by U46619. Additionally, the protein expression levels of RhoA, ROCK1 and ROCK2 were markedly decreased. These findings provided evidence that simvastatin increased HG-induced SRA01/04 cell viability and exerted inhibitory effects on EMT and oxidative stress that occurs during DC.

Long-Term Use of Statins Lowering the Risk of Rehospitalization Caused by Ischemic Stroke Among Middle-Aged Hyperlipidemic Patients: A Population-Based Study

Background: The long-term effects of statin use on rehospitalization due to ischemic stroke (reHospIS) in hyperlipidemic patients are still unknown. Therefore, we aimed to assess the long-term risks of reHospIS for hyperlipidemic patients who were taking statins and nonstatin lipid-lowering medicines on a regular basis. Methods and Materials: The National Health Insurance Research Database in Taiwan was used to conduct a 6-year cohort study of patients >45 years old (n = 9,098) who were newly diagnosed with hyperlipidemia and hospitalized for the first or second time due to ischemic stroke (IS). The risk of reHospIS was assessed using Cox proportional hazards regression model. Results: Nonstatin lipid-lowering medicines regular users were associated with a higher risk of reHospIS compared to stains users (hazard ratio, HR = 1.29-1.39, p < 0.05). Rosuvastatin was the most preferred lipid-lowering medicine with lower HRs of reHospIS in hyperlipidemic patients whether they developed diabetes or not. Bezafibrate regular users of hyperlipidemic patients developing diabetes (HR = 2.15, p < 0.01) had nearly 50% lower reHospIS risks than those without diabetes (HR = 4.27, p < 0.05). Age, gender, drug dosage, comorbidities of diabetes and heart failure (HF), and characteristics of the first hospitalization due to IS were all adjusted in models. Moreover, increasing trends of HRs of reHospIS were observed from Rosuvastatin, nonstatin lipid-lowering medicines, Lovastatin, and Gemfibrozil to Bezafibrate users. Conclusion: Statins were associated with long-term secondary prevention of reHospIS for hyperlipidemic patients. Rosuvastatin seemed to have the best protective effects. On the other hand, Bezafibrate appears to be beneficial for hyperlipidemic patients developing diabetes. Further research into the combination treatment of statin and nonstatin lipid-lowering medicines in hyperlipidemic patients developing diabetes is warranted.

The Effect of Statins on C-Reactive Protein in Stroke Patients: A Systematic Review of Clinical Trials

BACKGROUND

Statins reportedly have anti-inflammatory effects aside from their lipid-lowering impact. We investigated the effects of statin therapy on the level of C-reactive protein (CRP) or highly sensitive CRP (hs-CRP), a liver-derived marker of systemic inflammation, among stroke patients.

METHODS

An online search was performed in Scopus, PubMed/MEDLINE, ISI Web of Science, and Google Scholar up to November 2020 to recognize clinical trials investigating the effects of statins on the CRP level in stroke patients.

RESULTS

Overall, nine studies (11 treatment arms) with 1659 participants met the inclusion criteria. Six out of 9 studies (8 out of 11 arms) were categorized as studies with a high-quality methodological approach using the Cochrane Collaboration's tool. Data from 5 treatment arms indicated a significant decrease in CRP concentration, and in one treatment arm, CRP concentration did not suggest any considerable alteration following statin therapy. Moreover, two treatment arms showed a significant reduction in hs-CRP concentration and three treatment arms revealed no significant alteration in hs-CRP concentration following statin therapy. Generally, results were heterogeneous and independent of the type of statin, statin dose, treatment duration, and changes in plasma low-density lipoprotein cholesterol concentration.

CONCLUSION

The results suggest that statin therapy could reduce and, therefore, could be considered in these patients as potential anti-inflammatory agents.

Insight into Crosstalk between Ferroptosis and Necroptosis: Novel Therapeutics in Ischemic Stroke

Ferroptosis is a nonapoptotic form of cell death characterized by iron-dependent accumulation of lipid hydroperoxides to lethal levels. Necroptosis, an alternative form of programmed necrosis, is regulated by receptor-interacting protein (RIP) 1 activation and by RIP3 and mixed-lineage kinase domain-like (MLKL) phosphorylation. Ferroptosis and necroptosis both play important roles in the pathological progress in ischemic stroke, which is a complex brain disease regulated by several cell death pathways. In the past few years, increasing evidence has suggested that the crosstalk occurs between necroptosis and ferroptosis in ischemic stroke. However, the potential links between ferroptosis and necroptosis in ischemic stroke have not been elucidated yet. Hence, in this review, we overview and analyze the mechanism underlying the crosstalk between necroptosis and ferroptosis in ischemic stroke. And we find that iron overload, one mechanism of ferroptosis, leads to mitochondrial permeability transition pore (MPTP) opening, which aggravates RIP1 phosphorylation and contributes to necroptosis. In addition, heat shock protein 90 (HSP90) induces necroptosis and ferroptosis by promoting RIP1 phosphorylation and suppressing glutathione peroxidase 4 (GPX4) activation. In this work, we try to deliver a new perspective in the exploration of novel therapeutic targets for the treatment of ischemic stroke.

Omentin-1: Protective impact on ischemic stroke via ameliorating atherosclerosis

Omentin-1, a newly identified adipokine, has recently been revealed as a novel biomarker for ischemic stroke (IS). Low circulating omentin-1 levels could indicate a high risk of IS, and elevated omentin-1 levels exert a favorable impact on cerebral ischemia. Furthermore, omentin-1 has anti-atherosclerotic, anti-inflammatory, and cardiovascular protective capabilities through the intracellular Akt/AMP-activated protein kinase (AMPK)/ nuclear factor-κB (NF-κB) and certain protein kinase (ERK, JNK, and p38) signaling pathways. Omentin-1 also alleviates endothelial cell dysfunction, improves revascularization via the Akt-endothelial nitric-oxide synthase (eNOS) regulatory axis, promotes endothelium-dependent vasodilation through endothelium-derived NO in an eNOS fashion, and inhibits VSMC proliferation by means of AMPK/ERK signaling pathways, VSMC migration via inactivation of the NADPH oxidase (NOX)/ROS/p38/HSP27 pathways and artery calcification via the PI3K-Akt pathway. These findings indicate that omentin-1 may be a negative mediator of IS. Pharmacologically, several lines of clinical evidence indicate that metformin and statins could elevate omentin-1 levels, although the specific mechanism has not been precisely delineated until now. This study is the first to summarize the comprehensive mechanisms between omentin-1 and atherosclerosis and to review the shielding effect of omentin-1 on IS. We shed light on omentin-1 as a novel therapeutic target for combating IS.

Effect of Simvastatin in Serum Interleukin-6 Level in Patients with Acute Ischemic Stroke

Acute ischemic stroke is the leading cause of death and causing permanent disability in adults worldwide. In acute ischemic stroke, IL-6 levels positively correlated to more severe neurological deficits, more extensive brain damage and worse prognoses. The use of statin was associated with milder initial stroke severity, better functional outcome and lower mortality. This clinically randomized controlled trial study was aimed to analyze the serum levels of IL 6 in acute ischemic stroke patients who treated with Simvastatin 20 mg compare to placebo. Samples were taken using consecutive sampling method from hospitalized acute ischemic stroke patients in Neurology Department of Dr. Soetomo Teaching Hospital Surabaya and Airlangga University Hospital Surabayafrom August to November 2017. Total of 44 patients met the inclusion criteria, consisting of 22 patients in treatment group and 22 patients in control group.There were no significant difference in the characteristic of the patients in both groups (p>0.05). Averages of serum IL-6 in the control and the treatment group are 38.594±74.313 and 17.760±25.253(p=0,438) while averages of serum IL-6 post in the control group and the treatment are 46.586±103.484 and 15.275±17.183 (p=0,589). There were no significant level escalation in pre and post of control group (p = 0.205) and also no significant level reduction in pre and post of treatment group (p = 0.411), while the average difference in the control group (-7.992 + 78.912 pg/ml) and in the treatment group (2.485 + 23.738 pg/ml).

CNS and peripheral immunity in cerebral ischemia: partition and interaction

Stroke elicits excessive immune activation in the injured brain tissue. This well-recognized neural inflammation in the brain is not just an intrinsic organ response but also a result of additional intricate interactions between infiltrating peripheral immune cells and the resident immune cells in the affected areas. Given that there is a finite number of immune cells in the organism at the time of stroke, the partitioned immune systems of the central nervous system (CNS) and periphery must appropriately distribute the limited pool of immune cells between the two domains, mounting a necessary post-stroke inflammatory response by supplying a sufficient number of immune cells into the brain while maintaining peripheral immunity. Stroke pathophysiology has mainly been neurocentric in focus, but understanding the distinct roles of the CNS and peripheral immunity in their concerted action against ischemic insults is crucial. This review will discuss stroke-induced influences of the peripheral immune system on CNS injury/repair and of neural inflammation on peripheral immunity, and how comorbidity influences each.

Pharmacological management of cerebral ischemia in the elderly

Introduction: For elderly adults in the United States, stroke is the fifth leading cause of death of which ischemic strokes comprise a vast majority. Optimal pharmacological management of elderly ischemic stroke patients involves both reperfusion and supportive care. Recent research into pharmacological management has focused on vascular, immunomodulatory, cytoprotective, and alternative agents, some of which have shown limited success in clinical trials. However, no treatments have been established as a reliable mode for management of cerebral ischemia for elderly adults beyond acute thrombolysis.Areas covered: The authors conducted a literature search for ischemic stroke management in the elderly and a search for human drug studies for managing ischemic stroke on clinicaltrials.gov. Here, they describe recent progress in the pharmacological management of cerebral ischemia in the elderly.Expert opinion: Many drug classes (antihypertensive, cytoprotective and immunomodulatory, and alternative agents) have been explored with limited success in managing ischemic stroke, though some have shown preventative benefits. We generally observed a broad gap in evidence on elderly patients from studies across all drug classes, necessitating further studies to gain an understanding of effective management of ischemic stroke in this large demographic of patients.

Pleiotropic effects of statins: A focus on cancer

The statin drugs ('statins') potently inhibit hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase by competitively blocking the active site of the enzyme. Statins decrease de novo cholesterol biosynthesis and thereby reduce plasma cholesterol levels. Statins exhibit "pleiotropic" properties that are independent of their lipid-lowering effects. For example, preclinical evidence suggests that statins inhibit tumor growth and induce apoptosis in specific cancer cell types. Furthermore, statins show chemo-sensitizing effects by impairing Ras family GTPase signaling. However, whether statins have clinically meaningful anti-cancer effects remains an area of active investigation. Both preclinical and clinical studies on the potential mechanisms of action of statins in several cancers have been reviewed in the literature. Considering the contradictory data on their efficacy, we present an up-to-date summary of the pleiotropic effects of statins in cancer therapy and review their impact on different malignancies. We also discuss the synergistic anti-cancer effects of statins when combined with other more conventional anti-cancer drugs to highlight areas of potential therapeutic development.

Acute ischemic stroke management: concepts and controversies.A narrative review

INTRODUCTION

Amongst the 25.7 million survivors and 6.5 million deaths from stroke between 1990 and 2013, ischemic strokes accounted for approximately 70% and 50% of the cases, respectively. With patients still suffering from complications and stroke recurrence, more questions have been raised as to how we can better improve patient management.

AREAS COVERED

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and Newcastle-Ottawa Scale (NOS) were adopted to ensure a comprehensive inclusion of quality literature from various sources. PubMed and Embase were searched for evidence on thrombolysis, mechanical thrombectomy, artificial intelligence (AI), antiplatelet therapy, anticoagulation and hypertension management.

EXPERT OPINION

The directions of future research in these areas are dependent on the current level of validation. Endovascular therapy and applications of AI are relatively new compared to the other areas discussed in this review. As such, future studies need to focus on validating their efficacy. As for thrombolysis, antiplatelet and anticoagulation therapy, their efficacy has been well-established and future research efforts should be directed toward adjusting its use according to patient-specific factors, starting with factors with the most clinical relevance and prevalence.

Lipids and Lipid Mediators Associated with the Risk and Pathology of Ischemic Stroke

Stroke is a severe neurological disorder in humans that results from an interruption of the blood supply to the brain. Worldwide, stoke affects over 100 million people each year and is the second largest contributor to disability. Dyslipidemia is a modifiable risk factor for stroke that is associated with an increased risk of the disease. Traditional and non-traditional lipid measures are proposed as biomarkers for the better detection of subclinical disease. In the central nervous system, lipids and lipid mediators are essential to sustain the normal brain tissue structure and function. Pathways leading to post-stroke brain deterioration include the metabolism of polyunsaturated fatty acids. A variety of lipid mediators are generated from fatty acids and these molecules may have either neuroprotective or neurodegenerative effects on the post-stroke brain tissue; therefore, they largely contribute to the outcome and recovery from stroke. In this review, we provide an overview of serum lipids associated with the risk of ischemic stroke. We also discuss the role of lipid mediators, with particular emphasis on eicosanoids, in the pathology of ischemic stroke. Finally, we summarize the latest research on potential targets in lipid metabolic pathways for ischemic stroke treatment and on the development of new stroke risk biomarkers for use in clinical practice.

Post-Ischaemic Immunological Response in the Brain: Targeting Microglia in Ischaemic Stroke Therapy

Microglia, the major endogenous immune cells of the central nervous system, mediate critical degenerative and regenerative responses in ischaemic stroke. Microglia become "activated", proliferating, and undergoing changes in morphology, gene and protein expression over days and weeks post-ischaemia, with deleterious and beneficial effects. Pro-inflammatory microglia (commonly referred to as M1) exacerbate secondary neuronal injury through the release of reactive oxygen species, cytokines and proteases. In contrast, microglia may facilitate neuronal recovery via tissue and vascular remodelling, through the secretion of anti-inflammatory cytokines and growth factors (a profile often termed M2). This M1/M2 nomenclature does not fully account for the microglial heterogeneity in the ischaemic brain, with some simultaneous expression of both M1 and M2 markers at the single-cell level. Understanding and regulating microglial activation status, reducing detrimental and promoting repair behaviours, present the potential for therapeutic intervention, and open a longer window of opportunity than offered by acute neuroprotective strategies. Pharmacological modulation of microglial activation status to promote anti-inflammatory gene expression can increase neurogenesis and improve functional recovery post-stroke, based on promising preclinical data. Cell-based therapies, using preconditioned microglia, are of interest as a method of therapeutic modulation of the post-ischaemic inflammatory response. Currently, there are no clinically-approved pharmacological options targeting post-ischaemic inflammation. A major developmental challenge for clinical translation will be the selective suppression of the deleterious effects of microglial activity after stroke whilst retaining (or enhancing) the neurovascular repair and remodelling responses of microglia.

Transporter-Mediated Delivery of Small Molecule Drugs to the Brain: A Critical Mechanism That Can Advance Therapeutic Development for Ischemic Stroke

Ischemic stroke is the 5th leading cause of death in the United States. Despite significant improvements in reperfusion therapies, stroke patients still suffer from debilitating neurocognitive deficits. This indicates an essential need to develop novel stroke treatment paradigms. Endogenous uptake transporters expressed at the blood-brain barrier (BBB) provide an excellent opportunity to advance stroke therapy via optimization of small molecule neuroprotective drug delivery to the brain. Examples of such uptake transporters include organic anion transporting polypeptides (OATPs in humans; Oatps in rodents) and organic cation transporters (OCTs in humans; Octs in rodents). Of particular note, small molecule drugs that have neuroprotective properties are known substrates for these transporters and include 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (i.e., statins) for OATPs/Oatps and 1-amino-3,5-dimethyladamantane (i.e., memantine) for OCTs/Octs. Here, we review current knowledge on specific BBB transporters that can be targeted for improvement of ischemic stroke treatment and provide state-of-the-art perspectives on the rationale for considering BBB transport properties during discovery/development of stroke therapeutics.

Statin Therapy in Ischemic Stroke Models: A Meta-Analysis

Statins, drugs known for lipid lowering capabilities and reduction of cardiovascular disease, have demonstrated neuroprotective effects following ischemic stroke in retrospective clinical and animal studies. However, dosing (methods, time, type of statin, and quantity) varies across studies, limiting the clinical applicability of these findings. Furthermore, a comprehensive review of statins in edema and blood-brain barrier (BBB) breakdown is needed to provide insight on diverse, less explored neuroprotective effects. In the present study, we conduct a meta-analysis of publications evaluating statin administration in animal models of ischemic stroke. We review statins' most effective dosing regimen in four outcomes-infarct, edema, BBB breakdown, and functional outcome-to characterize several parameters of benefit associated with statin administration. A search term was constructed to identify experimental murine studies exploring statin use after transient middle cerebral artery occlusion (tMCAO) in PubMed, Web of Science, and Embase. Extracted data included statin type, dose, time and method of administration, and the four predetermined outcomes (functional outcome, edema, BBB breakdown, and infarction). A meta-analysis and stratified meta-regression were conducted using the standardized mean difference (SMD) method for continuous measurements. Included publications were assessed for bias using SYRCLE's RoB tool for animal studies. A total of 24 studies were included. Statin administration significantly reduced infarct volume (p < 0.0001), edema volume (p < 0.002), and neurological deficit (p < 0.0001). Simvastatin and pravastatin were most effective in reducing infarct volume when compared with atorvastatin (p = 0.0475, p = 0.0004) and rosuvastatin (p = 0.0036, p < 0.0001). Pravastatin outperformed all others in functional outcome. Subcutaneous (SC) injection was most effective in all outcomes. Statin therapy reduced BBB breakdown according to our systematic review. Mean study quality was 4.6/10. While statin therapy evidently improves neurological outcome following ischemic stroke, this analysis adds to our understanding of dosing and statins' effects on edema and BBB breakdown. These findings will aid the design of future studies investigating statin use and have larger implications for the clinical care of ischemic stroke patients.

Statins and the Brain: More than Lipid Lowering Agents?

BACKGROUND

Statins represent a class of medications widely prescribed to efficiently treat dyslipidemia. These drugs inhibit 3-βhydroxy 3β-methylglutaryl Coenzyme A reductase (HMGR), the rate-limiting enzyme of mevalonate (MVA) pathway. Besides cholesterol, MVA pathway leads to the production of several other compounds, which are essential in the regulation of a plethora of biological activities, including in the central nervous system. For these reasons, statins are able to induce pleiotropic actions, and acquire increased interest as potential and novel modulators in brain processes, especially during pathological conditions.

OBJECTIVE

The purpose of this review is to summarize and examine the current knowledge about pharmacokinetic and pharmacodynamic properties of statins in the brain. In addition, effects of statin on brain diseases are discussed providing the most up-to-date information.

METHODS

Relevant scientific information was identified from PubMed database using the following keywords: statins and brain, central nervous system, neurological diseases, neurodegeneration, brain tumors, mood, stroke.

RESULTS

315 scientific articles were selected and analyzed for the writing of this review article. Several papers highlighted that statin treatment is effective in preventing or ameliorating the symptomatology of a number of brain pathologies. However, other studies failed to demonstrate a neuroprotective effect.

CONCLUSION

Even though considerable research studies suggest pivotal functional outcomes induced by statin therapy, additional investigation is required to better determine the pharmacological effectiveness of statins in the brain, and support their clinical use in the management of different neuropathologies.

Beneficial effect of statins in patients receiving chronic hemodialysis following percutaneous coronary intervention: A nationwide retrospective cohort study

The cardiovascular diseases are the leading cause of mortality in end-stage renal disease (ESRD) patients. However, roles of statins are still controversial in dialysis-dependent ESRD patients regardless of having proven coronary artery occlusive disease. The aim of this study was to examine the benefit of statin following percutaneous coronary intervention (PCI) in ESRD patients who have proven coronary artery occlusive disease. This study was based on the National Health Insurance Service-National Sample Cohort in South Korea. We included 150 ESRD patients on chronic hemodialysis who underwent PCI with stenting between 2002 and 2013. The primary outcome was a composite of myocardial infarction, stroke, and all-cause mortality. Multivariate time-dependent Cox regression analysis were performed, and statin therapy after PCI was treated as a time-dependent variable. During 3.15 ± 2.71 (mean ± standard deviation) years of follow-up, there were 82 patients with primary outcome. The adjusted hazard ratio for statin use was 0.54 [0.33-0.90] compared to no statin use. This study showed that statin has significant benefit on reducing adverse events risk in dialysis-dependent ESRD patients after PCI.

Efficacy of High-Dose and Low-Dose Simvastatin on Vascular Oxidative Stress and Neurological Outcomes in Patient with Acute Ischemic Stroke: A Randomized, Double-Blind, Parallel, Controlled Trial

BACKGROUNDS

Stroke is the leading cause of death and long-term disability. Oxidative stress is elevated during occurrence of acute ischemic stroke (AIS). Soluble LOX-1 (sLOX-1) and NO are used as biomarkers for vascular oxidative stress that can reflect stabilization of atherosclerotic plaque. Previous study showed that simvastatin can reduce oxidative stress and LOX-1 expression.

OBJECTIVES

To evaluate neurological outcomes and serum sLOX-1 and NO levels in patients with AIS treatment with low dose 10 mg/day and high dose 40 mg/day of simvastatin.

METHODS

65 patients with AIS within 24 hours after onset were randomized to treatment with simvastatin 10 mg/day or 40 mg/day for 90 days. Personal data and past history of all patients were recorded at baseline. The blood chemistries were measured by standard laboratory techniques. Serum sLOX-1 and NO levels and neurological outcomes including NIHSS, mRS, and Barthel index were tested at baseline and Day 90 after simvastatin therapy.

RESULTS

Baseline characteristics were not significantly different in both groups except history of hypertension. Serum sLOX-1 and NO levels significantly reduce in both groups (sLOX-1 = 1.19 ± 0.47 and 0.98 ± 0.37 ng/ml; NO = 49.28 ± 7.21 and 46.59 ± 9.36 μmol/l) in 10 mg/day and 40 mg/day simvastatin groups, respectively. Neurological outcomes including NIHSS, mRS, and Barthel index significantly improve in both groups. However, no difference in NO level and neurological outcomes was found at 90 days after treatment as compared between low dose 10 mg/day and high dose 40 mg/day of simvastatin.

CONCLUSION

High-dose simvastatin might be helpful to reduce serum sLOX-1. But no difference in clinical outcomes was found between high- and low-dose simvastatin. Further more intensive clinical trial is needed to confirm the appropriate dosage of simvastatin in patients with acute ischemic stroke. This trial is registered with ClinicalTrials.gov ID: NCT03402204.

Statin therapy exacerbates alcohol-induced constriction of cerebral arteries via modulation of ethanol-induced BK channel inhibition in vascular smooth muscle

Statins constitute the most commonly prescribed drugs to decrease cholesterol (CLR). CLR is an important modulator of alcohol-induced cerebral artery constriction (AICAC). Using rats on a high CLR diet (2% CLR) we set to determine whether atorvastatin administration (10mg/kg daily for 18-23weeks) modified AICAC. Middle cerebral arteries were pressurized in vitro at 60mmHg and AICAC was evoked by 50mM ethanol, that is within the range of blood alcohol detected in humans following moderate-to-heavy drinking. AICAC was evident in high CLR+atorvastatin group but not in high CLR diet+placebo. Statin exacerbation of AICAC persisted in de-endothelialized arteries, and was blunted by CLR enrichment in vitro. Fluorescence imaging of filipin-stained arteries showed that atorvastatin decreased vascular smooth muscle (VSM) CLR when compared to placebo, this difference being reduced by CLR enrichment in vitro. Voltage- and calcium-gated potassium channels of large conductance (BK) are known VSM targets of ethanol, with their beta1 subunit being necessary for ethanol-induced channel inhibition and resulting AICAC. Ethanol-induced BK inhibition in excised membrane patches from freshly isolated myocytes was exacerbated in the high CLR diet+atorvastatin group when compared to high CLR diet+placebo. Unexpectedly, atorvastatin decreased the amount and function of BK beta1 subunit as documented by immunofluorescence imaging and functional patch-clamp studies. Atorvastatin exacerbation of ethanol-induced BK inhibition disappeared upon artery CLR enrichment in vitro. Our study demonstrates for the first time statin's ability to exacerbate the vascular effect of a widely consumed drug of abuse, this exacerbation being driven by statin modulation of ethanol-induced BK channel inhibition in the VSM via CLR-mediated mechanism.

Do statins really cause diabetes? A meta-analysis of major randomized controlled clinical trials

Objectives:

To investigate and establish the relationship between the use of statin therapy and the risk of development of diabetes.

Methods:

PubMed and the Cochrane Central Register of Controlled Trials was searched for randomized controlled end-point trials of statins, with more than 1000 subjects and a minimum of one-year follow-up period, published until August 2015. The odds ratio (OR) of diabetes incidence with overall statin therapy as well as with different statins in question was calculated through random effect meta-analysis model.

Results:

Fourteen studies were included in the analysis with a total of 94,943 participants. Of these, 2392 subjects developed incident diabetes in the statin and 2167 in the placebo groups during a 4-year follow-up. The OR of diabetes incidence with statin therapy was significantly higher as compared with the placebo group (OR=1.11; 95% confidence interval = 1.0 to 1.2; p=0.007). There was an insignificant level of heterogeneity between the included trials (Cochran Q= 19.463, p=0.109, I²=33.20). Subgroup analysis showed that only 2 statins namely, atorvastatin (OR= 1.29; p=0.042) and rosuvastatin (OR = 1.17; px=0.01) were significantly associated.

Conclusion:

Statin therapy can slightly increase risk of incident diabetes in subjects with hypercholesterolemia.

Neural differentiation of human Wharton's jelly-derived mesenchymal stem cells improves the recovery of neurological function after transplantation in ischemic stroke rats

Human Wharton's jelly-derived mesenchymal stem cells (hWJ-MSCs) have excellent proliferative ability, differentiation ability, low immunogenicity, and can be easily obtained. However, there are few studies on their application in the treatment of ischemic stroke, therefore their therapeutic effect requires further verification. In this study, hWJ-MSCs were transplanted into an ischemic stroke rat model via the tail vein 48 hours after transient middle cerebral artery occlusion. After 4 weeks, neurological functions of the rats implanted with hWJ-MSCs were significantly recovered. Furthermore, many hWJ-MSCs homed to the ischemic frontal cortex whereby they differentiated into neuron-like cells at this region. These results confirm that hWJ-MSCs transplanted into the ischemic stroke rat can differentiate into neuron-like cells to improve rat neurological function and behavior.

Reactive Oxygen Species in COPD-Related Vascular Remodeling

The pathogenesis of chronic obstructive pulmonary disease (COPD) is a multifaceted process involving the alteration of pulmonary vasculature. Such vascular remodeling can be associated with inflammation, shear stress, and hypoxia-conditions commonly seen in patients with lung diseases. Particularly, the overproduction of reactive oxygen species (ROS) in the diseased lungs contributes greatly to pulmonary vascular remodeling. ROS play an important role in vascular homeostasis, yet excessive ROS can alter pulmonary vasculature and impair lung function, as implicated in COPD at all stages. Increased inflammatory cell infiltration and endothelial dysfunction both correspond to the severity of COPD. As a byproduct of vascular remodeling, pulmonary hypertension negatively affects the long-term survival rate of COPD patients. While there is currently no cure for COPD, several treatment options have focused on alleviating COPD symptoms. Interventions such as long-term oxygen therapy, endothelium-targeted treatment, and pharmacological therapies show promising results in improving the life span of COPD patients and attenuating the progression of pulmonary hypertension. In this chapter, we aim to discuss the contributing factors of pulmonary vascular remodeling in COPD with an emphasis on the ROS, as well as potential redox treatments for COPD-related vascular remodeling.

Proprotein convertase subtilisin kexin 9 (PCSK9) inhibitors to treat hypercholesterolemia: Effect on stroke risk

BACKGROUND/PURPOSE

A reduction of cardiovascular events has been reported in phase 2 and 3 trials of the proprotein convertase subtilisin kexin 9 (PCSK9) inhibitors alirocumab and evolocumab. We aimed to investigate the effect PCSK9 inhibition on stroke risk in a meta-analysis involving data from randomized studies with alirocumab and evolocumab.

METHODS

Data from pre-specified combined analysis of 4465 patients who completed phase 2 or 3 studies of evolocumab over a period of 1year and a randomized trial on alirocumab including 2341 patients with hyperlipidemia on maximally tolerated statin who were at high risk for coronary heart disease over a period of 1.5years were used.

RESULTS

The number of patients having an ischemic stroke was small in both trials. PCSK9 inhibition showed no significant effect on stroke rate (risk ratio 1.43; 95% CI, 0.45-4.57, p=0.55). No significant differences in stroke risk were evident when transient ischemic attacks were included in the analysis (risk ratio 0.65; 95% CI, 0.25-1.68, p=0.37). No hemorrhagic strokes were reported in either study.

CONCLUSION

Although a benefit towards reduction of cardiovascular events in the overall has been documented, longer exposure is warranted to be able to evaluate the effect on stroke risk.

Lipid Control and Beyond: Current and Future Indications for Statin Therapy in Stroke

OPINION STATEMENT

Statins are a group of lipid-lowering agents that are competitive inhibitors of the enzyme 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase that have been used to reduce cholesterol levels and prevent cardiovascular events. Statins have been also shown to reduce the risk of stroke. In this review, we cover the role of statins in cerebrovascular disease through lipid-lowering mechanisms and other "pleiotropic" effects that provide protection against cerebrovascular events and potentially contribute to improve functional outcome after stroke.