Statin treatment in multiple sclerosis: a systematic review and meta-analysis

Dysregulated lipid metabolism networks modulate T-cell function in people with relapsing-remitting multiple sclerosis

Altered cholesterol, oxysterol, sphingolipid, and fatty acid concentrations are reported in blood, cerebrospinal fluid, and brain tissue of people with relapsing-remitting multiple sclerosis (RRMS) and are linked to disease progression and treatment responses. CD4 + T cells are pathogenic in RRMS, and defective T-cell function could be mediated in part by liver X receptors (LXRs)-nuclear receptors that regulate lipid homeostasis and immunity. RNA-sequencing and pathway analysis identified that genes within the 'lipid metabolism' and 'signalling of nuclear receptors' pathways were dysregulated in CD4 + T cells isolated from RRMS patients compared with healthy donors. While LXRB and genes associated with cholesterol metabolism were upregulated, other T-cell LXR-target genes, including genes involved in cellular lipid uptake (inducible degrader of the LDL receptor, IDOL), and the rate-limiting enzyme for glycosphingolipid biosynthesis (UDP-glucosylceramide synthase, UGCG) were downregulated in T cells from patients with RRMS compared to healthy donors. Correspondingly, plasma membrane glycosphingolipids were reduced, and cholesterol levels increased in RRMS CD4 + T cells, an effect partially recapitulated in healthy T cells by in vitro culture with T-cell receptor stimulation in the presence of serum from RRMS patients. Notably, stimulation with LXR-agonist GW3965 normalized membrane cholesterol levels, and reduced proliferation and IL17 cytokine production in RRMS CD4 + T-cells. Thus, LXR-mediated lipid metabolism pathways were dysregulated in T cells from patients with RRMS and could contribute to RRMS pathogenesis. Therapies that modify lipid metabolism could help restore immune cell function.

Stroke risk in multiple sclerosis: a critical appraisal of the literature

Observational studies suggest that the occurrence of stroke on multiple sclerosis (MS) patients is higher compared to the general population. MS is a heterogeneous disease that involves an interplay of genetic, environmental and immune factors. The occurrence of stroke is subject to a wide range of both modifiable and non-modifiable, short- and long-term risk factors. Both MS and stroke share common risk factors. The immune mechanisms that underlie stroke are similar to neurodegenerative diseases and are attributed to neuroinflammation. The inflammation in autoimmune diseases may, therefore, predispose to an increased risk for stroke or potentiate the effect of conventional stroke risk factors. There are, however, additional determinants that contribute to a higher risk and incidence of stroke in MS. Due to the challenges that are associated with their differential diagnosis, the objective is to present an overview of the factors that may contribute to increased susceptibility or occurrence of stroke in MSpatients by performing a review of the available to date literature. As both MS and stroke can individually detrimentally affect the quality of life of afflicted patients, the identification of factors that contribute to an increased risk for stroke in MS is crucial for the prompt implementation of preventative therapeutic measures to limit the additive burden that stroke imposes.

Navigating the landscape of Rho GTPase signalling system in autoimmunity: A bibliometric analysis spanning over three decades (1990 to 2023)

Ras-homologous (Rho) guanosine triphosphatases (GTPases) are considered a central player in regulating various biological processes, extending to immune regulation. Perturbations in Rho GTPase signalling have been implicated in immune-related dysregulation, contributing to the development of autoimmunity. This study presents a scientometric analysis exploring the interlink between the Rho GTPase signalling system and autoimmunity, while also delving into the trends of past studies. A total of 967 relevant publications from 1990 to 2023 were retrieved from the Web of Science Core Collection database after throrough manual filtering of irrelevant articles. The findings show an upward trajectory in publications related to this field since 2006. Over the past three decades, the United States of America (41.68%) emerged as the primary contributor in advancing our understanding of the association between the Rho GTPase signalling system and autoimmunity. Research in autoimmunity has mainly centered around therapeutic interventions, with an emphasis on studying leukocyte (macrophage) and endothelial remodelling. Interestingly, within the domains of multiple sclerosis and rheumatoid arthritis, the current focus has been directed towards comprehending the role of RhoA, Rac1, and Cdc42. Notably, certain subfamilies of Rho (such as RhoB and RhoC), Rac (including Rac2 and RhoG), Cdc42 (specifically RhoJ), and other atypical Rho GTPases (like RhoE and RhoH) consistently demonstrating compelling link with autoimmunity, but still warrants emphasis in the future study. Hence, strategic manipulation of the Rho signalling system holds immense promise as a pivotal approach to addressing the global challenge of autoimmunity.

A review on the efficacy and safety of lipid-lowering drugs in neurodegenerative disease

There is a train of thought that lipid therapies may delay or limit the impact of neuronal loss and poor patient outcomes of neurodegenerative diseases (NDDs). A variety of medicines including lipid lowering modifiers (LLMs) are prescribed in NDDs. This paper summarizes the findings of clinical and observational trials including systematic reviews and meta-analyses relating to LLM use in NDDs published in the last 15 years thus providing an up-to-date evidence pool. Three databases were searched PubMed, CINAHL, and Web of Science using key terms relating to the review question. The findings confirm the benefit of LLMs in hyperlipidemic patients with or without cardiovascular risk factors due to their pleotropic effects. In NDDs LLMs are proposed to delay disease onset and slow the rate of progression. Clinical observations show that LLMs protect neurons from α-synuclein, tau, and Aβ toxicity, activation of inflammatory processes, and ultimately oxidative injury. Moreover, current meta-analyses and clinical trials indicated low rates of adverse events with LLMs when used as monotherapy. LLMs appear to have favorable safety and tolerability profiles with few patients stopping treatment due to severe adverse effects. Our collated evidence thus concludes that LLMs have a role in NDDs but further work is needed to understand the exact mechanism of action and reach more robust conclusions on where and when it is appropriate to use LLMs in NDDs in the clinic.

Evaluation of Rosuvastatin Therapy on SIRT1 Gene Expression in Patients with Multiple Sclerosis: An Uncontrolled Clinical Trial

Background

Multiple sclerosis (MS) is a chronic autoimmune disease. Current medications have some limitations such as low efficacy and high side effects. In recent years, statins have been raised as potential therapeutics for MS treatment with minimal complications. In addition, patient monitoring using suitable molecular markers is necessary for treatment response evaluation.

Objective

The aim of the present study was the evaluation of SIRT1 gene expression changes following rosuvastatin therapy in patients with MS.

Methods

This before-after uncontrolled clinical trial study was performed on 25 patients with MS. Patients were treated with 20 mg rosuvastatin daily for 3 months. The Expanded Disability Status Scale (EDSS) was measured before and after statin therapy. Blood samples were taken from patients 2 times, before and after statin therapy, and centrifuged for white blood cell isolation. Total RNA was extracted using RNX-plus reagent, and complementary DNA was synthesized using Pars Tous cDNA Synthesis Kit. Real-time polymerase chain reaction was done using SYBR blue master mix and gene-specific primers in Roche light cycler. Patients' information was recorded using a checklist. Data analysis was performed using SPSS version 23 and Graph Pad version 9 software and P < 0.05 was considered a significant level.

Results

SIRT1 was significantly upregulated in MS patients after statin therapy. Subsequently, EDSS of patients was decreased along with the increase in SIRT1 gene expression, although EDSS changes were not significant (P > 0.05). Pearson correlation test showed no significant relationship between EDSS and SIRT1 gene expression (P > 0.05). No significant relationship was observed between SIRT1 expression or EDSS levels with patients' age, sex, weight, height, and body mass index and administrated drugs (P > 0.05).

Conclusions

SIRT1 potentially is a sensitive and reliable biomarker for patients with MS monitoring during statin therapy.

Smouldering Lesion in MS: Microglia, Lymphocytes and Pathobiochemical Mechanisms

Multiple sclerosis (MS) is an immune-mediated, chronic inflammatory, demyelinating, and neurodegenerative disease of the central nervous system (CNS). Immune cell infiltration can lead to permanent activation of macrophages and microglia in the parenchyma, resulting in demyelination and neurodegeneration. Thus, neurodegeneration that begins with acute lymphocytic inflammation may progress to chronic inflammation. This chronic inflammation is thought to underlie the development of so-called smouldering lesions. These lesions evolve from acute inflammatory lesions and are associated with continuous low-grade demyelination and neurodegeneration over many years. Their presence is associated with poor disease prognosis and promotes the transition to progressive MS, which may later manifest clinically as progressive MS when neurodegeneration exceeds the upper limit of functional compensation. In smouldering lesions, in the presence of only moderate inflammatory activity, a toxic environment is clearly identifiable and contributes to the progressive degeneration of neurons, axons, and oligodendrocytes and, thus, to clinical disease progression. In addition to the cells of the immune system, the development of oxidative stress in MS lesions, mitochondrial damage, and hypoxia caused by the resulting energy deficit and iron accumulation are thought to play a role in this process. In addition to classical immune mediators, this chronic toxic environment contains high concentrations of oxidants and iron ions, as well as the excitatory neurotransmitter glutamate. In this review, we will discuss how these pathobiochemical markers and mechanisms, alone or in combination, lead to neuronal, axonal, and glial cell death and ultimately to the process of neuroinflammation and neurodegeneration, and then discuss the concepts and conclusions that emerge from these findings. Understanding the role of these pathobiochemical markers would be important to gain a better insight into the relationship between the clinical classification and the pathomechanism of MS.

The potential therapeutic effect of statins in multiple sclerosis: beneficial or detrimental effects

Multiple sclerosis (MS) is a chronic progressive disabling disease of the central nervous system (CNS) characterized by demyelination and neuronal injury. Dyslipidemia is observed as one of the imperative risk factors involved in MS neuropathology. Also, chronic inflammation in MS predisposes to the progress of dyslipidemia. Therefore, treatment of dyslipidemia in MS by statins may attenuate dyslipidemia-induced MS and avert MS-induced metabolic changes. Therefore, the present review aimed to elucidate the possible effects of statins on the pathogenesis and outcomes of MS. Statins adversely affect the cognitive function in MS by decreasing brain cholesterol CoQ10, which is necessary for the regulation of neuronal mitochondrial function. However, statins could be beneficial in MS by shifting the immune response from pro-inflammatory Th17 to an anti-inflammatory regulatory T cell (Treg). The protective effect of statins against MS is related to anti-inflammatory and immunomodulatory effects with modulation of fibrinogen and growth factors. In conclusion, the effects of statins on MS neuropathology seem to be conflicting, as statins seem to be protective in the acute phase of MS through anti-inflammatory and antioxidant effects. However, statins lead to detrimental effects in the chronic phase of MS by reducing brain cholesterol and inhibiting the remyelination process.

Atorvastatin attenuates allergic inflammation by blocking prostaglandin biosynthesis in rats with allergic rhinitis

BACKGROUND

Prostaglandins (PGs) are bioactive lipid mediators derived from the nuclear and plasma membranes via the cyclooxygenase (COX) pathway of arachidonic acid (AA) metabolism. PGs bridge the interactions between various immunomodulatory cells in allergic rhinitis (AR) and are considered key players in regulating pro-inflammatory and anti-inflammatory responses. AA conversion to PGs involves rate-limiting enzymes that may be blocked by statins. The mechanisms by which statins regulate these enzymes in AR remain unclear. We investigated the effects of oral atorvastatin on PGs production in AR.

METHODS

An ovalbumin-induced AR rat model was constructed and the changes in nasal symptom score and nasal mucosa histopathological characteristics of AR rats under different atorvastatin doses were assessed. qRT-PCR, western blotting, and immunofluorescence were used to detect the mRNA and protein expression levels of rate-limiting enzymes and downstream molecules of AA metabolism in the nasal mucosa and liver.

RESULTS

Oral atorvastatin significantly alleviated symptoms and eosinophil infiltration in the nasal mucosa, inhibited goblet cell hyperplasia and mast cell recruitment, and decreased mucus secretion in AR rats. Increasing atorvastatin dose increased the anti-inflammatory effects. High-dose atorvastatin inhibited upregulation of the inflammatory mediator PGD₂ in the nasal mucosa of AR rats. Compared to the control group, the mRNA and protein expression of the rate-limiting enzymes COX-2, PGDS, and PGES in AA metabolism in the AR group were upregulated but downregulated after the oral administration of high-dose atorvastatin. Atorvastatin also showed dose-dependent inhibition of ERK1/2 and downstream NF-κB phosphorylation in the nasal mucosa and liver of AR rats.

CONCLUSIONS

Atorvastatin inhibited allergic inflammation and attenuated AR nasal symptoms by downregulating PGD₂ and rate-limiting enzyme expression in PGD₂ biosynthesis, possibly by blocking the RAS/ERK/NF-κB signaling pathway.

Pleotropic effects of statins: the dilemma of wider utilization of statin

BACKGROUND

Apart from reducing the circulating LDL-c and the number of cardiovascular cases as well as fatalities, statins have auxiliary non-lipid-related or cholesterol independent effects, the pleiotropic effects. The aim of the present review is to understand the pleotropic effects of statins.

MAIN BODY

Cardiovascular disease (CVD) is presently the major cause of patient misery as well as mortality among non-communicable diseases (NCDs) in the world. Despite the fact that statins are the most extensively affirmed, prescribed and evidence-based lipid-lowering medicine worldwide that curtail low density lipoprotein cholesterol (LDL-c) levels and the number of cardiovascular cases as well as deaths, statins also elicit auxiliary non-lipid-related or cholesterol independent effects, the pleiotropic effects. Improved endothelial function, significantly lowered oxidative stress, atherosclerotic plaque stabilization, immunomodulatory, cessation of vascular smooth muscle proliferation, effects on bone metabolism, anti-inflammatory, antithrombotic effects, and reduced risk of dementia are among these pleotropic effects. Statins have also been explored for its uses in life threatening diseases like cancer and inflammatory bowel disease. They have been demonstrated to revamp vascular tone. Many research and review articles have been thoroughly studied for this systematic review.

CONCLUSIONS

Statins have not only shown to be benefitial in lowering the levels of LDL-C but have also been established to be advantageous in the treatment of cancer, neurological conditions like dementia, multiple sclerosis, inflammatory bowel disease. Future high-quality trials are needed to include statins in the treatment of these conditions as per guidelines.

Facts and ideas on statins with respect to their lipophilicity: a focus on skeletal muscle cells and bone besides known cardioprotection

Statins are known to block cholesterol synthesis in the liver. They also exhibit non-lipid pleiotropic effects due to the inhibition of protein prenylation, thereby modulating various signaling pathways of cellular homeostasis and integrity. Both lipid control and pleiotropic action of statins are clinically used, mainly for treatment of hypercholesterolemia and primary and secondary prevention of cardiovascular diseases. Because the prescription of statins is increasing and statin therapy is often lifelong, in particular in patients with other risk factors, safety issues being associated with polymorbidity and polypragmasia as well as the persistence with and adherence to statins are specific points of attention of clinicians and clinical pharmacologists. Furthermore, because skeletal myocytes have a cholesterol inhibitory sensitivity greater than hepatocytes, a choice of an appropriate statin based on its lipophilicity and the associated likelihood of its side effects on skeletal muscle cells and bone is warranted in such polymorbid patients. These approaches can effectively modulate the risk: benefit ratio and highlight a need for personalized therapy as much as possible, thereby minimizing risk of discontinuation of therapy and poor compliance.

A Narrative Review on Axonal Neuroprotection in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) resulting in demyelination and neurodegeneration. The therapeutic strategy is now largely based on reducing inflammation with immunosuppressive drugs. Unfortunately, when disease progression is observed, no drug offers neuroprotection apart from its anti-inflammatory effect. In this review, we explore current knowledge on the assessment of neurodegeneration in MS and look at putative targets that might prove useful in protecting the axon from degeneration. Among them, Bruton's tyrosine kinase inhibitors, anti-apoptotic and antioxidant agents, sex hormones, statins, channel blockers, growth factors, and molecules preventing glutamate excitotoxicity have already been studied. Some of them have reached phase III clinical trials and carry a great message of hope for our patients with MS.

Neuroinflammatory Markers: Key Indicators in the Pathology of Neurodegenerative Diseases

Neuroinflammation, a protective response of the central nervous system (CNS), is associated with the pathogenesis of neurodegenerative diseases. The CNS is composed of neurons and glial cells consisting of microglia, oligodendrocytes, and astrocytes. Entry of any foreign pathogen activates the glial cells (astrocytes and microglia) and overactivation of these cells triggers the release of various neuroinflammatory markers (NMs), such as the tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-1β (IL-10), nitric oxide (NO), and cyclooxygenase-2 (COX-2), among others. Various studies have shown the role of neuroinflammatory markers in the occurrence, diagnosis, and treatment of neurodegenerative diseases. These markers also trigger the formation of various other factors responsible for causing several neuronal diseases including Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), multiple sclerosis (MS), ischemia, and several others. This comprehensive review aims to reveal the mechanism of neuroinflammatory markers (NMs), which could cause different neurodegenerative disorders. Important NMs may represent pathophysiologic processes leading to the generation of neurodegenerative diseases. In addition, various molecular alterations related to neurodegenerative diseases are discussed. Identifying these NMs may assist in the early diagnosis and detection of therapeutic targets for treating various neurodegenerative diseases.

Lowering blood cholesterol does not affect neuroinflammation in experimental autoimmune encephalomyelitis

Background

Multiple sclerosis (MS) is a chronic disabling disease of the central nervous system (CNS) commonly affecting young adults. There is increasing evidence that environmental factors are important in the development and course of MS. The metabolic syndrome (MetS) which comprises dyslipidemia has been associated with a worse outcome in MS disease. Furthermore, the lipid-lowering drug class of statins has been proposed to improve MS disease course. However, cholesterol is also rate-limiting for myelin biogenesis and promotes remyelination in MS animal models. Thus, the impact of circulating blood cholesterol levels during the disease remains debated and controversial.

Methods

We assessed the role of circulating cholesterol on the murine model of MS, the experimental autoimmune encephalomyelitis (EAE) disease using two different approaches: (1) the mouse model of familial hypercholesterolemia induced by low-density lipoprotein receptor (LDLr) deficiency, and (2) the use of the monoclonal anti-PCSK9 neutralizing antibody alirocumab, which reduces LDLr degradation and consequently lowers blood levels of cholesterol.

Results

Elevated blood cholesterol levels induced by LDLr deficiency did not worsen clinical symptoms of mice during EAE. In addition, we observed that the anti-PCSK9 antibody alirocumab did not influence EAE disease course, nor modulate the immune response in EAE.

Conclusions

These findings suggest that blood cholesterol level has no direct role in neuro-inflammatory diseases and that the previously shown protective effects of statins in MS are not related to circulating cholesterol.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02409-x.

The effects of HMG-CoA reductase inhibitors on disease activity in multiple sclerosis: A systematic review and meta-analysis

OBJECTIVE

To assess whether statins (3‑hydroxy-3-methylglutaryl coenzyme A reductase inhibitors) exert disease-modifying effects in multiple sclerosis (MS).

APPROACH

A systematic review and meta-analysis was performed including randomized-controlled clinical trials (RCTs) on statin use in MS. A random-effects model was applied to calculate pooled estimates and odds ratios (ORs) with corresponding 95% confidence intervals (CIs), when comparing patients treated with statins alone or adjunct to disease modifying treatment (DMT) to non-statin-treated patients.

RESULTS

We identified 7 RCTs including 789 patients with relapsing-remitting MS (RRMS), all of whom received additional DMT with IFN-β. Single identified RCTs in secondary-progressive MS (SPMS), clinically isolated syndrome (CIS) and optic neuritis (ON) were not meta-analyzed. In RRMS, add-on statin use was not associated with the risk of clinical relapse (OR=1.30, 95%CI: 0.901.87) or EDSS-progression from baseline, neither appeared related to the risk of new contrast-enhancing or T2 lesions (OR=1.28, 95%CI: 0.364.58), and the risk of whole-brain volume reduction on MRI. Add-on statins to IFN-β were safe and well-tolerated. In SPMS, stand-alone simvastatin led to significantly reduced annualized rate of whole-brain volume reduction. In CIS and ON, statins were associated with reduced risk for new T2 lesions and improved visual recovery, respectively.

CONCLUSIONS

We detected no benefit from statin treatment as add-on to IFN-β in RRMS. However, a potential beneficial effect in SPMS, CIS and ON deserves independent confirmation and further evaluation within adequately powered RCTs.

Perspective insights of repurposing the pleiotropic efficacy of statins in neurodegenerative disorders: An expository appraisal

Neurodegenerative disorders which affects a larger population pose a great clinical challenge. These disorders impact the quality of life of an individual by damaging the neurons, which are the unit cells of the brain. Clinicians are faced with the grave challenge of inhibiting the progression of these diseases as available treatment options fail to meet the clinical demand. Thus, treating the disease/disorder symptomatically is the Hobson's choice. The goal of the researchers is to introduce newer therapies in this segment and introducing a new molecule will take long years of development. Hence, drug repurposing/repositioning can be a better substitute in comparison to time consuming and expensive drug discovery and development cycle. Presently, a paradigm shift towards the re-purposing of drugs can be witnessed. Statins which have been previously approved as anti-hyperlipidemic agents are in the limelight of research for re-purposed drugs. Owing to their anti-inflammatory and antioxidant nature, statins act as neuroprotective in several brain disorders. Further they attenuate the amyloid plaques and protein aggregation which are the triggering factors in the Alzheimer's and Parkinson's respectively. In case of Huntington disease and Multiple sclerosis they help in improving the psychomotor symptoms and stimulate remyelination thus acting as neuroprotective. This article reviews the potential of statins in treating neurodegenerative disorders along with a brief discussion on the safety concerns associated with use of statins and human clinical trial data linked with re-tasking statins for neurodegenerative disorders along with the regulatory perspectives involved with the drug repositioning.

Metabolomics in Autoimmune Diseases: Focus on Rheumatoid Arthritis, Systemic Lupus Erythematous, and Multiple Sclerosis

The metabolomics approach represents the last downstream phenotype and is widely used in clinical studies and drug discovery. In this paper, we outline recent advances in the metabolomics research of autoimmune diseases (ADs) such as rheumatoid arthritis (RA), multiple sclerosis (MuS), and systemic lupus erythematosus (SLE). The newly discovered biomarkers and the metabolic mechanism studies for these ADs are described here. In addition, studies elucidating the metabolic mechanisms underlying these ADs are presented. Metabolomics has the potential to contribute to pharmacotherapy personalization; thus, we summarize the biomarker studies performed to predict the personalization of medicine and drug response.

Carbohydrate and lipid metabolism in multiple sclerosis: Clinical implications for etiology, pathogenesis, diagnosis, prognosis, and therapy

Multiple sclerosis (MS) is a complicated autoimmune disease characterized by inflammatory and demyelinating events in the central nervous system. The exact etiology and pathogenesis of MS have not been elucidated. However, a set of metabolic changes and their effects on immune cells and neural functions have been explained. This review highlights the contribution of carbohydrates and lipids metabolism to the etiology and pathogenesis of MS. Then, we have proposed a hypothetical relationship between such metabolic changes and the immune system in patients with MS. Finally, the potential clinical implications of these metabolic changes in diagnosis, prognosis, and discovering therapeutic targets have been discussed. It is concluded that research on the pathophysiological alterations of carbohydrate and lipid metabolism may be a potential strategy for paving the way toward MS treatment.

Cardiovascular Disease in Patients With Systemic Lupus Erythematosus: Potential for Improved Primary Prevention With Statins

Cardiovascular disease (CVD) is a significant cause of morbidity and mortality in patients with systemic lupus erythematosus (SLE). This is especially true in SLE patients with traditional CVD risk factors (eg, hypertension, hyperlipidemia, obesity) and disease-related risk factors (eg, increased SLE disease activity, elevated C-reactive protein levels, and antiphospholipid antibodies). The only guidelines in the primary prevention of CVD in SLE patients involve reducing traditional risk factors, but there are additional therapies that may be beneficial, including statin use. Current data on statin use for prevention of CVD in SLE patients are limited, but there have been some promising results. Statin use has been shown to be especially important in SLE patients for decreasing low-density lipoprotein levels and preventing CVD in hyperlipidemic patients. In addition, there is evidence suggesting that it may be beneficial to use statins in SLE patients with chronically elevated high-sensitivity C-reactive protein levels and antiphospholipid antibodies. It is important to continue to investigate the impact of statins on CVD in SLE patients, as they could significantly improve outcomes in patients with this disease.

The Effectiveness of Statins as Potential Therapy for Multiple Sclerosis: A Systematic Review of Randomized Controlled trials

Evidence of the effectiveness of statins, the lipid-lowering agents in retarding the progression of Multiple Sclerosis (MS), a disabling neurological disease with autoimmune etiology, have been highlighted in animal studies and observational studies. The proposed immune-modulatory actions and neuroprotective effects of statins make them a promising treatment option for MS that needs to be explored further. In this systematic review, we aim to investigate the role of different statins as monotherapy or in combination with the established MS medications in improving the clinical and radiological course of MS variants, including optic neuritis, using randomized controlled trials (RCTs). We systematically searched PubMed, PubMed Central (PMC), MEDLINE, Cochrane library, and Scopus databases using regular keywords and medical subject headings terms. Randomized controlled trials of any statin used in any variants of MS, including studies on statins used in optic neuritis published up to April 2021, were included in the review. Data on the effects on the relapse rate, the Expanded Disability Status Scale (EDSS) alterations, and the changes in Magnetic Resonance Imaging (MRI) lesions were collected from the included studies. Seven studies with a total of 831 patients and an average duration of follow-up of six to 36 months were included in our review. Five trials were of statins add-on to interferon therapy in relapsing-remitting multiple sclerosis (RRMS), of which four studies were assessed to be of good quality while the remaining study featured a high risk of bias. One trial of simvastatin monotherapy in Secondary Progressive Multiple Sclerosis (SPMS) was included, which was assessed to be of good methodological quality with low risk of bias and adequate patient number. A trial of simvastatin monotherapy on patients with optic neuritis was included, which was evaluated as a good quality study. Still, it had a low number of participants and a short duration of follow-up. We used the changes in disease relapse rate and EDSS as primary outcome variables and the MRI lesions changes as a secondary outcome variable. Studies in RRMS showed no significant effects on primary and secondary outcomes. The study on SPMS featured a significant improvement in EDSS in simvastatin-treated patients with no effect on relapse rate or MRI changes. Simvastatin use in optic neuritis enhances clinical visual outcomes with no significant effect on MRI changes or the rate of progression to definite MS. In contrast to animal studies and observational studies, randomized controlled trials do not replicate the positive effects of statins used as monotherapy or combined with interferon beta in patients with RRMS and optic neuritis in relapse rate EDSS or MRI changes. However, trials of statins on SPMS showed a promising effect on disability progression (EDSS score), which might support the proposed immune-modulatory and neuroprotective role of statins and serve as a baseline for further RCTs applying statins as monotherapy or combination with other established MS therapies.

Reviewing the Significance of Blood-Brain Barrier Disruption in Multiple Sclerosis Pathology and Treatment

The disruption of blood–brain barrier (BBB) for multiple sclerosis (MS) pathogenesis has a double effect: early on during the onset of the immune attack and later for the CNS self-sustained ‘inside-out’ demyelination and neurodegeneration processes. This review presents the characteristics of BBB malfunction in MS but mostly highlights current developments regarding the impairment of the neurovascular unit (NVU) and the metabolic and mitochondrial dysfunctions of the BBB’s endothelial cells. The hypoxic hypothesis is largely studied and agreed upon recently in the pathologic processes in MS. Hypoxia in MS might be produced per se by the NVU malfunction or secondary to mitochondria dysfunction. We present three different but related terms that denominate the ongoing neurodegenerative process in progressive forms of MS that are indirectly related to BBB disruption: progression independent of relapses, no evidence of disease activity and smoldering demyelination or silent progression. Dimethyl fumarate (DMF), modulators of S1P receptor, cladribine and laquinimode are DMTs that are able to cross the BBB and exhibit beneficial direct effects in the CNS with very different mechanisms of action, providing hope that a combined therapy might be effective in treating MS. Detailed mechanisms of action of these DMTs are described and also illustrated in dedicated images. With increasing knowledge about the involvement of BBB in MS pathology, BBB might become a therapeutic target in MS not only to make it impenetrable against activated immune cells but also to allow molecules that have a neuroprotective effect in reaching the cell target inside the CNS.

Statins and risk of amyotrophic lateral sclerosis: a systematic review and meta-analysis

Amyotrophic lateral sclerosis (ALS) is a paralytic, heterogeneous and progressive disease characterized by the degeneration of both upper and lower motor neurons. Several studies about the effects of statins drug on the risk of ALS showed contradictory results and evidence for this is inconclusive. So we aimed to perform a meta-analysis on previous studies to clarify the association between statin use and risk of ALS. The databases including PubMed, Scopus, and Web of science were searched in February 2021 for studies that reported the association between statin use and risk of ALS. The eligible studies had to provide a report on the effect of statin and the incidence of ALS while comparing it to the control group. Articles that had low statin exposure time, the absence of a control group and an unknown number of ALS patients were excluded. The rate ratio and 95% confidence interval (CI) were used for association measures in case-control and cohort studies. After full-text and abstract review, data from 8 studies with a total of 547,622 participants and 13,890 cases of ALS were entered in the present meta-analysis. We combined eight studies using a random-effect model and the RR for statin users among groups was 0.98 (95% CI 0.80-1.20) which indicates no association between statin and incidence of ALS. Also high heterogeneity was detected across the studies (Q value = 26.62, P = .00; I² = 72.71%). In our meta-analysis study, we found no association between statin use and an increase in ALS incidence. This result is in line with some previous studies and provides strong evidence that denies the possible association between statin uptake and disease induction.

Failed, Interrupted, or Inconclusive Trials on Neuroprotective and Neuroregenerative Treatment Strategies in Multiple Sclerosis: Update 2015-2020

In the recent past, a plethora of drugs have been approved for the treatment of multiple sclerosis (MS). These therapeutics are mainly confined to immunomodulatory or immunosuppressive strategies but do not sufficiently address remyelination and neuroprotection. However, several neuroregenerative agents have shown potential in pre-clinical research and entered Phase I to III clinical trials. Although none of these compounds have yet proceeded to approval, understanding the causes of failure can broaden our knowledge about neuroprotection and neuroregeneration in MS. Moreover, most of the investigated approaches are characterised by consistent mechanisms of action and proved convincing efficacy in animal studies. Therefore, learning from their failure will help us to enforce the translation of findings acquired in pre-clinical studies into clinical application. Here, we summarise trials on MS treatment published since 2015 that have either failed or were interrupted due to a lack of efficacy, adverse events, or for other reasons. We further outline the rationale underlying these drugs and analyse the background of failure to gather new insights into MS pathophysiology and optimise future study designs. For conciseness, this review focuses on agents promoting remyelination and medications with primarily neuroprotective properties or unconventional approaches. Failed clinical trials that pursue immunomodulation are presented in a separate article.

Neuroprotective Methodologies in the Treatment of Multiple Sclerosis Current Status of Clinical and Pre-clinical Findings

Multiple sclerosis is an idiopathic and autoimmune associated motor neuron disorder that affects myelinated neurons in specific brain regions of young people, especially females. MS is characterized by oligodendrocytes destruction further responsible for demyelination, neuroinflammation, mitochondrial abnormalities, oxidative stress and neurotransmitter deficits associated with motor and cognitive dysfunctions, vertigo and muscle weakness. The limited intervention of pharmacologically active compounds like interferon-β, mitoxantrone, fingolimod and monoclonal antibodies used clinically are majorly associated with adverse drug reactions. Pre-clinically, gliotoxin ethidium bromide mimics the behavioral and neurochemical alterations in multiple sclerosis- like in experimental animals associated with the down-regulation of adenyl cyclase/cAMP/CREB, which is further responsible for a variety of neuropathogenic factors. Despite the considerable investigation of neuroprotection in curing multiple sclerosis, some complications still remain. The available medications only provide symptomatic relief but do not stop the disease progression. In this way, the development of unused beneficial methods tends to be ignored. The limitations of the current steady treatment may be because of their activity at one of the many neurotransmitters included or their failure to up direct signaling flag bearers detailed to have a vital part in neuronal sensitivity, biosynthesis of neurotransmitters and its discharge, development, and separation of the neuron, synaptic versatility and cognitive working. Therefore, the current review strictly focused on the exploration of various clinical and pre-clinical features available for multiple sclerosis to understand the pathogenic mechanisms and to introduce pharmacological interventions associated with the upregulation of intracellular adenyl cyclase/cAMP/CREB activation to ameliorate multiple sclerosis-like features.

Disrupted Lipid Metabolism in Multiple Sclerosis: A Role for Liver X Receptors?

Multiple sclerosis (MS) is a chronic neurological disease driven by autoimmune, inflammatory and neurodegenerative processes leading to neuronal demyelination and subsequent degeneration. Systemic lipid metabolism is disturbed in people with MS, and lipid metabolic pathways are crucial to the protective process of remyelination. The lipid-activated transcription factors liver X receptors (LXRs) are important integrators of lipid metabolism and immunity. Consequently, there is a strong interest in targeting these receptors in a number of metabolic and inflammatory diseases, including MS. We have reviewed the evidence for involvement of LXR-driven lipid metabolism in the dysfunction of peripheral and brain-resident immune cells in MS, focusing on human studies, both the relapsing remitting and progressive phases of the disease are discussed. Finally, we discuss the therapeutic potential of modulating the activity of these receptors with existing pharmacological agents and highlight important areas of future research.

Statin therapy and risk of Alzheimer's and age-related neurodegenerative diseases

INTRODUCTION

Establishing efficacy of and molecular pathways for statins has the potential to impact incidence of Alzheimer's and age-related neurodegenerative diseases (NDD).

METHODS

This retrospective cohort study surveyed US-based Humana claims, which includes prescription and patient records from private-payer and Medicare insurance. Claims from 288,515 patients, aged 45 years and older, without prior history of NDD or neurological surgery, were surveyed for a diagnosis of NDD starting 1 year following statin exposure. Patients were required to be enrolled with claims data for at least 6 months prior to first statin prescription and at least 3 years thereafter. Computational system biology analysis was conducted to determine unique target engagement for each statin.

RESULTS

Of the 288,515 participants included in the study, 144,214 patients (mean [standard deviation (SD)] age, 67.22 [3.8] years) exposed to statin therapies, and 144,301 patients (65.97 [3.2] years) were not treated with statins. The mean (SD) follow-up time was 5.1 (2.3) years. Exposure to statins was associated with a lower incidence of Alzheimer's disease (1.10% vs 2.37%; relative risk [RR], 0.4643; 95% confidence interval [CI], 0.44-0.49; P < .001), dementia 3.03% vs 5.39%; RR, 0.56; 95% CI, 0.54-0.58; P < .001), multiple sclerosis (0.08% vs 0.15%; RR, 0.52; 95% CI, 0.41-0.66; P < .001), Parkinson's disease (0.48% vs 0.92%; RR, 0.53; 95% CI, 0.48-0.58; P < .001), and amyotrophic lateral sclerosis (0.02% vs 0.05%; RR, 0.46; 95% CI, 0.30-0.69; P < .001). All NDD incidence for all statins, except for fluvastatin (RR, 0.91; 95% CI, 0.65-1.30; P = 0.71), was reduced with variances in individual risk profiles. Pathway analysis indicated unique and common profiles associated with risk reduction efficacy.

DISCUSSION

Benefits and risks of statins relative to neurological outcomes should be considered when prescribed for at-risk NDD populations. Common statin activated pathways indicate overarching systems required for risk reduction whereas unique targets could advance a precision medicine approach to prevent neurodegenerative diseases.

Association Between Sudden Sensorineural Hearing Loss and History of Statin Use: A Nested Case-Control Study

OBJECTIVE

The effect of statin on sudden sensorineural hearing loss (SSNHL) remains unclear. Thus, this study aimed to investigate the association between prior statin use and SSNHL.

STUDY DESIGN

A nested case-control study.

SETTING

Participants aged ≥40 years were enrolled from the 2002-2015 Korean National Health Insurance Service-Health Screening Cohort.

METHODS

A total of 5876 patients with SSNHL were matched with 23,504 control participants for age, sex, income, and region of residence. History of statin use for 2 years before SSNHL onset was investigated between the groups. The odds ratios (ORs) of the length of statin use for SSNHL stratified by age, sex, income, and region of residence were analyzed with conditional logistic regression. Dyslipidemia, total cholesterol, blood pressure, blood glucose, hemoglobin, obesity, smoking, alcohol consumption, and Charlson Comorbidity Index score were adjusted. The adjusted variables were subjected to subgroup analyses.

RESULTS

The SSNHL group had a longer duration of statin use than the control group (mean [SD], 81.9 [197.7] days vs 72.7 [188.0] days; P = .001). However, statin use was not associated with SSNHL after adjusting for the confounders (adjusted OR, 1.04; 95% CI, 0.98-1.11; P = .245). There was a positive correlation between statin use and SSNHL in the crude model (crude OR, 1.10; 95% CI, 1.04-1.16; P = .001). However, there was no association between statin use and SSNHL in all subgroup analyses.

CONCLUSION

Previous statin use was not associated with SSNHL.

Using Serum Metabolomics to Predict Development of Anti-drug Antibodies in Multiple Sclerosis Patients Treated With IFNβ

Background: Neutralizing anti-drug antibodies (ADA) can greatly reduce the efficacy of biopharmaceuticals used to treat patients with multiple sclerosis (MS). However, the biological factors pre-disposing an individual to develop ADA are poorly characterized. Thus, there is an unmet clinical need for biomarkers to predict the development of immunogenicity, and subsequent treatment failure. Up to 35% of MS patients treated with beta interferons (IFNβ) develop ADA. Here we use machine learning to predict immunogenicity against IFNβ utilizing serum metabolomics data. Methods: Serum samples were collected from 89 MS patients as part of the ABIRISK consortium-a multi-center prospective study of ADA development. Metabolites and ADA were quantified prior to and after IFNβ treatment. Thirty patients became ADA positive during the first year of treatment (ADA+). We tested the efficacy of six binary classification models using 10-fold cross validation; k-nearest neighbors, decision tree, random forest, support vector machine and lasso (Least Absolute Shrinkage and Selection Operator) logistic regression with and without interactions. Results: We were able to predict future immunogenicity from baseline metabolomics data. Lasso logistic regression with/without interactions and support vector machines were the most successful at identifying ADA+ or ADA- cases, respectively. Furthermore, patients who become ADA+ had a distinct metabolic response to IFNβ in the first 3 months, with 29 differentially regulated metabolites. Machine learning algorithms could also predict ADA status based on metabolite concentrations at 3 months. Lasso logistic regressions had the greatest proportion of correct classifications [F1 score (accuracy measure) = 0.808, specificity = 0.913]. Finally, we hypothesized that serum lipids could contribute to ADA development by altering immune-cell lipid rafts. This was supported by experimental evidence demonstrating that, prior to IFNβ exposure, lipid raft-associated lipids were differentially expressed between MS patients who became ADA+ or remained ADA-. Conclusion: Serum metabolites are a promising biomarker for prediction of ADA development in MS patients treated with IFNβ, and could provide novel insight into mechanisms of immunogenicity.

Statins and autoimmunity: State-of-the-art

HMG-CoA reductase inhibitors, or statins, are potent plasma LDL-cholesterol (LDL-c) lowering agents. Since the introduction of the first statin, lovastatin, in 1987, accumulating evidence showed that non-cholesterol lowering effects play an important role in their efficacy to reduce atherosclerotic cardiovascular disease (ASCVD). Thus, these non-LDL-c lowering properties could benefit patients with immune-mediated diseases. Statins and their associated immune-modulating roles have recently received much attention. Different statins have been administered in various experimental and clinical studies focused on autoimmunity. The results indicate that statins can modulate immune responses through mevalonate pathway-dependent and -independent mechanisms. The anti-inflammatory and immune-modulating effects include cell adhesion, migration of antigen presenting cells, and differentiation, as well as activation, of T-cells. In various autoimmune diseases (e.g. rheumatoid arthritis, lupus, and multiple sclerosis), promising results have been obtained to date.

Multiple Sclerosis: Lipids, Lymphocytes, and Vitamin D

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. We review the two core MS features, myelin instability, fragmentation, and remyelination failure, and dominance of pathogenic CD4+ Th17 cells over protective CD4+ Treg cells. To better understand myelin pathology, we describe myelin biosynthesis, structure, and function, then highlight stearoyl-CoA desaturase (SCD) in nervonic acid biosynthesis and nervonic acid's contribution to myelin stability. Noting that vitamin D deficiency decreases SCD in the periphery, we propose it also decreases SCD in oligodendrocytes, disrupting the nervonic acid supply and causing myelin instability and fragmentation. To better understand the distorted Th17/Treg cell balance, we summarize Th17 cell contributions to MS pathogenesis, then highlight how 1,25-dihydroxyvitamin D3 signaling from microglia to CD4+ T cells restores Treg cell dominance. This signaling rapidly increases flux through the methionine cycle, removing homocysteine, replenishing S-adenosyl-methionine, and improving epigenetic marking. Noting that DNA hypomethylation and inappropriate DRB1*1501 expression were observed in MS patient CD4+ T cells, we propose that vitamin D deficiency thwarts epigenetic downregulation of DRB1*1501 and Th17 cell signature genes, and upregulation of Treg cell signature genes, causing dysregulation within the CD4+ T cell compartment. We explain how obesity reduces vitamin D status, and how estrogen and vitamin D collaborate to promote Treg cell dominance in females. Finally, we discuss the implications of this new knowledge concerning myelin and the Th17/Treg cell balance, and advocate for efforts to address the global epidemics of obesity and vitamin D deficiency in the expectation of reducing the impact of MS.

Protein arginine methyltransferase 5 promotes cholesterol biosynthesis-mediated Th17 responses and autoimmunity

Protein arginine methyltransferase 5 (PRMT5) catalyzes symmetric dimethylation (SDM) of arginine, a posttranslational modification involved in oncogenesis and embryonic development. However, the role and mechanisms by which PRMT5 modulates Th cell polarization and autoimmune disease have not yet been elucidated. Here, we found that PRMT5 promoted SREBP1 SDM and the induction of cholesterol biosynthetic pathway enzymes that produce retinoid-related orphan receptor (ROR) agonists that activate RORγt. Specific loss of PRMT5 in the CD4+ Th cell compartment suppressed Th17 differentiation and protected mice from developing experimental autoimmune encephalomyelitis (EAE). We also found that PRMT5 controlled thymic and peripheral homeostasis in the CD4+ Th cell life cycle and invariant NK (iNK) T cell development and CD8+ T cell maintenance. This work demonstrates that PRMT5 expression in recently activated T cells is necessary for the cholesterol biosynthesis metabolic gene expression program that generates RORγt agonistic activity and promotes Th17 differentiation and EAE. These results point to Th PRMT5 and its downstream cholesterol biosynthesis pathway as promising therapeutic targets in Th17-mediated diseases.

The Impact of Phytosterols on the Healthy and Diseased Brain

The central nervous system (CNS) is the most cholesterol-rich organ in mammals. Cholesterol homeostasis is essential for proper brain functioning and dysregulation of cholesterol metabolism can lead to neurological problems. Multiple sclerosis (MS) and Alzheimer's disease (AD) are examples of neurological diseases that are characterized by a disturbed cholesterol metabolism. Phytosterols (PS) are plant-derived components that structurally and functionally resemble cholesterol. PS are known for their cholesterol-lowering properties. Due to their ability to reach the brain, researchers have started to investigate the physiological role of PS in the CNS. In this review, the metabolism and function of PS in the diseased and healthy CNS are discussed.

Drug Treatment of Clinically Isolated Syndrome

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) that leads to inflammation, demyelination and ultimately axonal degeneration. In most cases, it is preceded by its precursor, clinically isolated syndrome (CIS) with conversion rates to clinically definite MS (CDMS) of roughly 20-75%. Neurologists are therefore faced with the challenge of initiating a disease-modifying therapy (DMT) as early as possible to favorably influence the course of the disease. During the past 20 years, a multitude of drugs have been incorporated into our therapeutic armamentarium for MS and CIS. Choosing the right drug for an individual patient is complex and should be based not only on the drug's overall efficacy to prevent disease progression but also its specific adverse reaction profile, the severity of individual disease courses and, finally, patient compliance in order to adequately weigh associated risks and benefits. Here, we review the available data on the efficacy, safety and tolerability of DMTs tested for CIS and discuss their value regarding a delay of progression to CDMS.

Comorbidities in multiple sclerosis-a plea for interdisciplinary collaboration to improve the quality of life of MS patients

The negative influence of comorbidities on the quality of life of people with multiple sclerosis is evident and the problem is increasingly acknowledged by numerous international studies in long-term care. One therapeutic option would be an add-on therapy with vitamin D (VD), with the aim of achieving a therapeutically effective dose. The individually required VD dose must be tested, since the response to a certain dose is subject to variations between individuals. A possible toxicity with increased 1.25(OH)D3 (active VD metabolite) is largely prevented by increased activity of 24-hydroxylase (CYP24A1). Monitoring of serum VD levels as well as serum calcium and phosphate levels (optional Ca excretion in 24-hour urine, Ca creatinine ratio in urine) provides safety and is necessary because possible mutations on the (catabolic) CYP24A1 gene can lead to a partial or total loss of 24-hydroxylase activity and provoke hypercalcemia/hyperphosphatemia. The main therapeutic objective is to maintain functional and social independence by using drugs with a high safety profile. The prevention and optimal management of comorbidities can influence the quality of life of patients with MS (PwMS) when included in patient care. Adequate measures can reduce the burden of MS only if the risk of comorbidity is reduced through targeted monitoring, early detection and diagnosis. Such a strategy will contribute to influencing the premature mortality of patients with MS. If VD is recognized as a "multipurpose steroid hormone", it could also be used to maintain cognitive function and prevent premature possible dementia, especially as there is evidence that VD deficiency correlates with brain atrophy (hippocampus). At present, MS therapy is still a balancing act between therapeutically efficient action and the management of unexpected side effects, with VD add-on therapy being almost unproblematic and most likely to be accepted by PwMS.

Biocatalyzed Synthesis of Statins: A Sustainable Strategy for the Preparation of Valuable Drugs

Statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, are the largest selling class of drugs prescribed for the pharmacological treatment of hypercholesterolemia and dyslipidaemia. Statins also possess other therapeutic effects, called pleiotropic, because the blockade of the conversion of HMG-CoA to (R)-mevalonate produces a concomitant inhibition of the biosynthesis of numerous isoprenoid metabolites (e.g., geranylgeranyl pyrophosphate (GGPP) or farnesyl pyrophosphate (FPP)). Thus, the prenylation of several cell signalling proteins (small GTPase family members: Ras, Rac, and Rho) is hampered, so that these molecular switches, controlling multiple pathways and cell functions (maintenance of cell shape, motility, factor secretion, differentiation, and proliferation) are regulated, leading to beneficial effects in cardiovascular health, regulation of the immune system, anti-inflammatory and immunosuppressive properties, prevention and treatment of sepsis, treatment of autoimmune diseases, osteoporosis, kidney and neurological disorders, or even in cancer therapy. Thus, there is a growing interest in developing more sustainable protocols for preparation of statins, and the introduction of biocatalyzed steps into the synthetic pathways is highly advantageous—synthetic routes are conducted under mild reaction conditions, at ambient temperature, and can use water as a reaction medium in many cases. Furthermore, their high selectivity avoids the need for functional group activation and protection/deprotection steps usually required in traditional organic synthesis. Therefore, biocatalysis provides shorter processes, produces less waste, and reduces manufacturing costs and environmental impact. In this review, we will comment on the pleiotropic effects of statins and will illustrate some biotransformations nowadays implemented for statin synthesis.

CD55 upregulation in astrocytes by statins as potential therapy for AQP4-IgG seropositive neuromyelitis optica

Background

Neuromyelitis optica spectrum disorder (herein called NMO) is an inflammatory demyelinating disease that can be initiated by binding of immunoglobulin G autoantibodies (AQP4-IgG) to aquaporin-4 on astrocytes, causing complement-dependent cytotoxicity (CDC) and downstream inflammation. The increased NMO pathology in rodents deficient in complement regulator protein CD59 following passive transfer of AQP4-IgG has suggested the potential therapeutic utility of increasing the expression of complement regulator proteins.

Methods

A cell-based ELISA was developed to screen for pharmacological upregulators of endogenous CD55 and CD59 in a human astrocyte cell line. A statin identified from the screen was characterized in cell culture models and rodents for its action on complement regulator protein expression and its efficacy in models of seropositive NMO.

Results

Screening of ~ 11,500 approved and investigational drugs and nutraceuticals identified transcriptional upregulators of CD55 but not of CD59. Several statins, including atorvastatin, simvastatin, lovastatin, and fluvastatin, increased CD55 protein expression in astrocytes, including primary cultures, by three- to four-fold at 24 h, conferring significant protection against AQP4-IgG-induced CDC. Mechanistic studies revealed that CD55 upregulation involves inhibition of the geranylgeranyl transferase pathway rather than inhibition of cholesterol biosynthesis. Oral atorvastatin at 10–20 mg/kg/day for 3 days strongly increased CD55 immunofluorescence in mouse brain and spinal cord and reduced NMO pathology following intracerebral AQP4-IgG injection.

Conclusion

Atorvastatin or other statins may thus have therapeutic benefit in AQP4-IgG seropositive NMO by increasing CD55 expression, in addition to their previously described anti-inflammatory and immunomodulatory actions.

Neuroinflammation, Microglia, and Cell-Association during Prion Disease

Prion disorders are transmissible diseases caused by a proteinaceous infectious agent that can infect the lymphatic and nervous systems. The clinical features of prion diseases can vary, but common hallmarks in the central nervous system (CNS) are deposition of abnormally folded protease-resistant prion protein (PrPres or PrPSc), astrogliosis, microgliosis, and neurodegeneration. Numerous proinflammatory effectors expressed by astrocytes and microglia are increased in the brain during prion infection, with many of them potentially damaging to neurons when chronically upregulated. Microglia are important first responders to foreign agents and damaged cells in the CNS, but these immune-like cells also serve many essential functions in the healthy CNS. Our current understanding is that microglia are beneficial during prion infection and critical to host defense against prion disease. Studies indicate that reduction of the microglial population accelerates disease and increases PrPSc burden in the CNS. Thus, microglia are unlikely to be a foci of prion propagation in the brain. In contrast, neurons and astrocytes are known to be involved in prion replication and spread. Moreover, certain astrocytes, such as A1 reactive astrocytes, have proven neurotoxic in other neurodegenerative diseases, and thus might also influence the progression of prion-associated neurodegeneration.

The Antineuroinflammatory Effect of Simvastatin on Lipopolysaccharide Activated Microglial Cells

Microglial cells, upon hyperactivation, produce proinflammatory cytokines and other oxidative stress mediators causing neuroinflammation, which is associated with the progress of many neurodegenerative diseases. Suppressing the microglial activation has hence been used as an approach for treating such diseases. In this study, the antineuroinflammatory effect of simvastatin was examined in lipopolysaccharide (LPS)-activated rat C6 glioma cells. The cell proliferation and cytotoxic effect of LPS and simvastatin on C6 glioma cells was evaluated by (MTT) assay. Neuroinflammation was induced in differentiated cell lines by treatment with 3.125 μg/mL of LPS for 12 h. Upon induction, the cell lines were treated with different concentrations (3.125, 6.25, 12.5, 25, 50, 100 μM) of simvastatin and incubated in a humidified CO₂ incubator for 24 to 48 h. The optimum concentrations of LPS and simvastatin were found to be 3.125 μg/mL and 25 μM, respectively, with a cell viability of more than 90% at 24 h postincubation. Furthermore, proinflammatory marker expression was analyzed by flow cytometry and showed a decrease in interferon-γ, interleukin 6, nuclear factor-κB p65, and tumor necrosis factor-α in simvastatin-treated and LPS-induced neuroinflammatory cells, and the mean fluorescent values were found to be 21.75 ± 0.76, 20.9 ± 1.90, 19.72 ± 1.29, and 16.82 ± 0.97, respectively, as compared to the untreated cells. Thus, we show that simvastatin has the potential to regulate the anti-inflammatory response in microglial cells upon LPS challenge. Hence, simvastatin can be employed as a potent anti-inflammatory drug against neuroinflammatory diseases and neurodegenerative disorders.

The peroxisome: an update on mysteries 2.0

Peroxisomes are key metabolic organelles, which contribute to cellular lipid metabolism, e.g. the β-oxidation of fatty acids and the synthesis of myelin sheath lipids, as well as cellular redox balance. Peroxisomal dysfunction has been linked to severe metabolic disorders in man, but peroxisomes are now also recognized as protective organelles with a wider significance in human health and potential impact on a large number of globally important human diseases such as neurodegeneration, obesity, cancer, and age-related disorders. Therefore, the interest in peroxisomes and their physiological functions has significantly increased in recent years. In this review, we intend to highlight recent discoveries, advancements and trends in peroxisome research, and present an update as well as a continuation of two former review articles addressing the unsolved mysteries of this astonishing organelle. We summarize novel findings on the biological functions of peroxisomes, their biogenesis, formation, membrane dynamics and division, as well as on peroxisome-organelle contacts and cooperation. Furthermore, novel peroxisomal proteins and machineries at the peroxisomal membrane are discussed. Finally, we address recent findings on the role of peroxisomes in the brain, in neurological disorders, and in the development of cancer.

Small GTPase RAS in multiple sclerosis - exploring the role of RAS GTPase in the etiology of multiple sclerosis

RAS

signaling is involved in the development of autoimmunity in general. Multiple sclerosis (MS) is a T cell-mediated autoimmune disease of the central nervous system. It is widely recognized that a reduction of Foxp3+ regulatory T (Treg) cells is an immunological hallmark of MS, but the underlying mechanisms are unclear. In experimental autoimmune models, N-Ras and K-Ras inhibition triggers an anti-inflammatory effect up-regulating, via foxp3 elevation, the numbers and the functional suppressive properties of Tregs. Similarly, an increase in natural Tregs number during Experimental Autoimmune Encephalomyelitis (EAE) in R-RAS -/- mice results in attenuated disease. In humans, only KRAS GTPase isoform is involved in mechanism causing tolerance defects in rheumatoid arthritis (RA). T cells from these patients have increased transcription of KRAS (but not NRAS). RAS genes are major drivers in human cancers. Consequently, there has been considerable interest in developing anti-RAS inhibitors for cancer treatment. Despite efforts, no anti-RAS therapy has succeeded in the clinic. The major strategy that has so far reached the clinic aimed to inhibit activated Ras indirectly through blocking its post-translational modification and inducing its mis-localization. The disappointing clinical outcome of Farnesyl Transferase Inhibitors (FTIs) in cancers has decreased interest in these drugs. However, FTIs suppress EAE by downregulation of myelin-reactive activated T-lymphocytes and statins are currently studied in clinical trials for MS. However, no pharmacologic approaches to targeting Ras proteins directly have yet succeeded. The therapeutic strategy to recover immune function through the restoration of impaired Tregs function with the mounting evidences regarding KRAS in autoimmune mediated disorder (MS, SLE, RA, T1D) suggest as working hypothesis the direct targeting KRAS activation using cancer-derived small molecules may be clinically relevant.

ABBREVIATIONS

FTIs: Farnesyl Transferase Inhibitors; MS: Multiple Sclerosis; RRMS: Relapsing Remitting Multiple Sclerosis; PPMS: Primary Progressive Multiple Sclerosis; Tregs: regulatory T-cells; Foxp3: Forkhead box P3; EAE: Experimental Autoimmune Encephalomyelitis; T1D: Type 1 Diabete; SLE: Systemic Lupus Erythematosus; RA: Rheumatoid Arthritis; CNS: Central Nervous System; TMEV: Theiler's murine encephalomyelitis virus; FTS: farnesyl thiosalicylic acid; TCR: T-Cell Receptor; AIA: Adjuvant-induced Arthritis; EAN: experimental autoimmune neuritis; HVR: hypervariable region; HMG-CoA: 3-hydroxy-3-methylglutaryl coenzyme A reductase; PBMC: Peripheral Blood Mononuclear Cells.

Immune modulatory effects of statins

Despite major advances in recent years, immunosuppressive regimens for multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus and graft-versus-host disease still have major adverse effects and immunomodulation rather than immune paralysis would be desirable. Statins inhibit the rate-limiting enzyme of the l-mevalonate pathway, the 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase. It was shown that blocking the l-mevalonate pathway reduces inflammation through effects on downstream metabolites of the pathway including farnesylpyrophosphates and geranylgeranylpyrophosphates, which are essential for the attachment of GTPases like RhoA, Rac and Ras to the cell membrane. Therefore, l-mevalonate pathway downstream products play critical roles in the different steps of an immune response including immune cell activation, migration, cytokine production, immune metabolism and survival. This review discusses the relevance of the different metabolites for the immunomodulatory effect of statins and connects preclinical results with data from clinical studies that tested statins for the treatment of different inflammatory diseases.

Combination therapy of lovastatin and AMP-activated protein kinase activator improves mitochondrial and peroxisomal functions and clinical disease in experimental autoimmune encephalomyelitis model

Recent studies report that loss and dysfunction of mitochondria and peroxisomes contribute to the myelin and axonal damage in multiple sclerosis (MS). In this study, we investigated the efficacy of a combination of lovastatin and AMP-activated protein kinase (AMPK) activator (AICAR) on the loss and dysfunction of mitochondria and peroxisomes and myelin and axonal damage in spinal cords, relative to the clinical disease symptoms, using a mouse model of experimental autoimmune encephalomyelitis (EAE, a model for MS). We observed that lovastatin and AICAR treatments individually provided partial protection of mitochondria/peroxisomes and myelin/axons, and therefore partial attenuation of clinical disease in EAE mice. However, treatment of EAE mice with the lovastatin and AICAR combination provided greater protection of mitochondria/peroxisomes and myelin/axons, and greater improvement in clinical disease compared with individual drug treatments. In spinal cords of EAE mice, lovastatin-mediated inhibition of RhoA and AICAR-mediated activation of AMPK cooperatively enhanced the expression of the transcription factors and regulators (e.g. PPARα/β, SIRT-1, NRF-1, and TFAM) required for biogenesis and the functions of mitochondria (e.g. OXPHOS, MnSOD) and peroxisomes (e.g. PMP70 and catalase). In summary, these studies document that oral medication with a combination of lovastatin and AICAR, which are individually known to have immunomodulatory effects, provides potent protection and repair of inflammation-induced loss and dysfunction of mitochondria and peroxisomes as well as myelin and axonal abnormalities in EAE. As statins are known to provide protection in progressive MS (Phase II study), these studies support that supplementation statin treatment with an AMPK activator may provide greater efficacy against MS.

Neuroprotection and visual function after optic neuritis

PURPOSE OF REVIEW

This article discusses the advantages and pitfalls of testing neuroprotective treatment strategies in patients suffering from optic neuritis.

RECENT FINDINGS

Spectral domain optical coherence tomography now permits for automated segmentation of individual retinal layers. The peripapillary retinal nerve fibre layer (pRNFL) has been used in 13 of the 15 trials reviewed. Twelve trials also made use of electrophysiology. Overestimation of good visual recovery in the past has recently been recognized. Assessment of low contrast visual acuity and colour vision are now mainstream.

SUMMARY

The availability of highly accurate and robust trial outcome measures has facilitated research on this topic. A single long-term structural outcome measurement of the pRNFL is sufficient. For shorter term, assessments of the ganglion cell/inner plexiform layer and axonal birefringence are promising. Longitudinal blood levels of neurofilament proteins permit to recognize axonal loss at presentation and monitor changes longitudinally. Inner nuclear layer volume changes relate to inflammatory disease activity.Pitfalls are related to the timing of events. Hyperacute recruitment is needed for future trials. The onset of demyelination is not known, which complicates timing of electrophysiological recordings. Optic disc oedema precludes the use of the pRNFL from the affected eye as a baseline variable. The concomitant use of corticosteroids complicates interpretation of trial data.

Vascular pathology in multiple sclerosis: reframing pathogenesis around the blood-brain barrier

Blood-brain barrier (BBB) disruption has long been recognised as an important early feature of multiple sclerosis (MS) pathology. Traditionally, this has been seen as a by-product of the myelin-specific immune response. Here, we consider whether vascular changes instead play a central role in disease pathogenesis, rather than representing a secondary effect of neuroinflammation or neurodegeneration. Importantly, this is not necessarily mutually exclusive from current hypotheses. Vascular pathology in a genetically predisposed individual, influenced by environmental factors such as pathogens, hypovitaminosis D and smoking, may be a critical initiator of a series of events including hypoxia, protein deposition and immune cell egress that allows the development of a CNS-specific immune response and the classical pathological and clinical hallmarks of disease. We review the changes that occur in BBB function and cerebral perfusion in patients with MS and highlight genetic and environmental risk factors that, in addition to modulating immune function, may also converge to act on the vasculature. Further context is provided by contrasting these changes with other neurological diseases in which there is also BBB malfunction, and highlighting current disease-modifying therapies that may also have an effect on the BBB. Indeed, in reframing current evidence in this model, the vasculature could become an important therapeutic target in MS.