Lipoic Acid and Other Antioxidants as Therapies for Multiple Sclerosis

Role of fenofibrate in multiple sclerosis

Multiple sclerosis (MS) is the most frequent inflammatory and demyelinating disease of the central nervous system (CNS). The underlying pathophysiology of MS is the destruction of myelin sheath by immune cells. The formation of myelin plaques, inflammation, and injury of neuronal myelin sheath characterizes its neuropathology. MS plaques are multiple focal regions of demyelination disseminated in the brain's white matter, spinal cords, deep grey matter, and cerebral cortex. Fenofibrate is a peroxisome proliferative activated receptor alpha (PPAR-α) that attenuates the inflammatory reactions in MS. Fenofibrate inhibits differentiation of Th17 by inhibiting the expression of pro-inflammatory signaling. According to these findings, this review intended to illuminate the mechanistic immunoinflammatory role of fenofibrate in mitigating MS neuropathology. In conclusion, fenofibrate can attenuate MS neuropathology by modulating different pathways, including oxidative stress, autophagy, mitochondrial dysfunction, inflammatory-signaling pathways, and neuroinflammation.

Icariin ameliorates the cuprizone-induced demyelination associated with antioxidation and anti-inflammation

The treatment of immunomodulation in multiple sclerosis (MS) can alleviate the severity and relapses. However, it cannot improve the neurological disability of patients due to a lack of myelin protection and regeneration. Therefore, remyelinating therapies may be one of the feasible strategies that can prevent axonal degeneration and restore neurological disability. Natural product icariin (ICA) is a flavonol compound extracted from epimedium flavonoids, which has neuroprotective effects in several models of neurological diseases. Here, we attempt to explore whether ICA has the potential to treat demyelination and its possible mechanisms of action using lipopolysaccharide-treated BV2 microglia, primary microglia, bone marrow-derived macrophages, and cuprizone-induced demyelination model. The indicators of oxidative stress and inflammatory response were evaluated using commercial kits. The results showed that ICA significantly reduced the levels of oxidative intermediates nitric oxide, hydrogen peroxide, malondialdehyde, and inflammatory cytokines TNF-α, IL-1β, and increased the levels of antioxidants superoxide dismutase, catalase, glutathione peroxidase, and anti-inflammatory cytokines IL-10 and TGF-β in vitro cell experiments. In vivo demyelination model, ICA significantly alleviated the behavioral abnormalities and enhanced the integrated optical density/mm2 of Black Gold II and myelin basic protein myelin staining, accompanied by the inhibition of oxidative stress/inflammatory response. Immunohistochemical staining showed that ICA significantly induced the expression of nuclear factor erythroid derived 2/heme oxygenase-1 (Nrf2/HO-1) and inhibited the expression of toll-like receptor 4/ nuclear factor kappa B (TLR4/NF-κB), which are two key signaling pathways in antioxidant and anti-inflammatory processes. Our results strongly suggest that ICA may be used as a potential agent to treat demyelination via regulating Nrf2/HO-1-mediated antioxidative stress and TLR4/NF-κB-mediated inflammatory responses.

Innovative drug delivery strategies to the CNS for the treatment of multiple sclerosis

Disorders of the central nervous system (CNS), such as multiple sclerosis (MS) represent a great emotional, financial and social burden. Despite intense efforts, great unmet medical needs remain in that field. MS is an autoimmune, chronic inflammatory demyelinating disease with no curative treatment up to date. The current therapies mostly act in the periphery and seek to modulate aberrant immune responses as well as slow down the progression of the disease. Some of these therapies are associated with adverse effects related partly to their administration route and show some limitations due to their rapid clearance and inability to reach the CNS. The scientific community have recently focused their research on developing MS therapies targeting different processes within the CNS. However, delivery of therapeutics to the CNS is mainly limited by the presence of the blood-brain barrier (BBB). Therefore, there is a pressing need to develop new drug delivery strategies that ensure CNS availability to capitalize on identified therapeutic targets. Several approaches have been developed to overcome or bypass the BBB and increase delivery of therapeutics to the CNS. Among these strategies, the use of alternative routes of administration, such as the nose-to-brain (N2B) pathway, offers a promising non-invasive option in the scope of MS, as it would allow a direct transport of the drugs from the nasal cavity to the brain. Moreover, the combination of bioactive molecules within nanocarriers bring forth new opportunities for MS therapies, allowing and/or increasing their transport to the CNS. Here we will review and discuss these alternative administration routes as well as the nanocarrier approaches useful to deliver drugs for MS.

Effects of Dietary Modification Based on Complementary and Alternative Iranian Medicine in Patients with Secondary-Progressive Multiple Sclerosis: A Randomized Controlled Clinical Trial

Objectives: To evaluate the efficacy of dietary modifications based on complementary and alternative Iranian medicine (CAIM) in patients with secondary-progressive multiple sclerosis (SPMS). Design: In this randomized controlled trial, 70 SPMS patients were randomized to receive either a moderate-nature diet based on Persian medicine (as intervention) or usual diet plus health-related diet recommendations (as control) for 2 months. Serum high-sensitivity C-reactive protein (hs-CRP), erythrocyte sedimentation rate (ESR), Expanded Disability Status Scale (EDSS), Modified Fatigue Impact Scale (MFIS), State-Trait Anxiety Inventory (STAI), Global Pain Scale (GPS), Gastrointestinal Symptom Rating Scale (GSRS), anthropometric measurements, and quality of life (QOL) were assessed at baseline and end of trial. Analysis of covariance was performed, and the results were adjusted for potential confounders using SPSS v.14. Results: All participants completed the study for 2 months. There were significant improvements across the mean changes of hs-CRP (-0.1 ± 0.2 mg/L for intervention vs. -0.01 ± 0.13 mg/L for control; padjusted = 0.012), MFIS (-11.0 ± 11.8 vs. -0.7 ± 9.9; padjusted <0.001), GSRS (-19.9 ± 16.3 to 1.2 ± 17.5; padjusted <0.001), GPS (padjusted = 0.032), and QOL (padjusted <0.05). No significant difference was observed across the ESR, EDSS, STAI, and anthropometric measurements. Conclusion: Dietary modifications based on CAIM may improve inflammation and clinical manifestations in SPMS patients. Nonetheless, further trials are required to confirm these findings. Clinical Trial Registration: IRCT20181113041641N2.

Anti-inflammatory-antioxidant modifications and synbiotics improved health-related conditions in patients with progressive forms of multiple sclerosis: A single-center, randomized clinical trial

BACKGROUND AND PURPOSE

There is growing evidence that dietary modification can improve clinical manifestations in multiple sclerosis (MS) patients. This study aimed to assess the impact of synbiotics and anti-inflammatory-antioxidant-rich diet on fatigue, pain, gut and bladder status, and sexual function in patients with progressive forms of MS.

MATERIALS AND METHODS

In this single-center, single-blind, randomized, controlled clinical trial, seventy participants with three forms of progressive MS (primary-progressive, secondary-progressive, and progressive-relapsing) were randomly assigned to receive either synbiotics supplement and anti-inflammatory-antioxidant-rich diet or a placebo along with their usual diet for a duration of four months. Modified fatigue impact scale (MFIS), global pain scale (GPS), bladder control scale (BLCS), bowel control scale (BWCS), and sexual satisfaction scale (SSS) were assessed at baseline and at the end of the trial.

RESULTS

Sixty-nine participants successfully completed the trial, resulting in a 98% adherence rate to the diet, and no reports of serious side effects. Significant mean changes were observed in fatigue (Δ for experimental group = -10.5 ± 10.8 vs. Δ for control group = -0.08 ± 4.1; P < 0.001), pain (-14.1 ± 19.0 vs. 0.9 ± 10.3; P < 0.001), bladder (-0.76 ± 2.1 vs. 0.3 ± 1.1; P = 0.013) and bowel (-6.6 ± 3.2 vs. -0.05 ± 2.3; P < 0.001) control, as well as sexual function (-1.0 ± 2.3 vs. 0.51 ± 0.21; P < 0.001).

CONCLUSION

The anti-inflammatory-antioxidant-rich diet and synbiotics co-supplementation demonstrated improvements in fatigue, pain, sexual function, and bowel/bladder status among patients with progressive MS.

Therapeutic Potential of Natural Compounds in Neurodegenerative Diseases: Insights from Clinical Trials

Neurodegenerative diseases are caused by the gradual loss of neurons' function. These neurological illnesses remain incurable, and current medicines only alleviate the symptoms. Given the social and economic burden caused by the rising frequency of neurodegenerative diseases, there is an urgent need for the development of appropriate therapeutics. Natural compounds are gaining popularity as alternatives to synthetic drugs due to their neuroprotective properties and higher biocompatibility. While natural compounds' therapeutic effects for neurodegenerative disease treatment have been investigated in numerous in vitro and in vivo studies, only few have moved to clinical trials. This article provides the first systematic review of the clinical trials evaluating natural compounds' safety and efficacy for the treatment of the five most prevalent neurodegenerative disorders: Alzheimer's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, and Huntington's disease.

The Effects of Antioxidant Nutraceuticals on Cellular Sulfur Metabolism and Signaling

Significance: Nutraceuticals are ingested for health benefits, in addition to their general nutritional value. These dietary supplements have become increasingly popular since the late 20th century and they are a rapidly expanding global industry approaching a half-trillion U.S. dollars annually. Many nutraceuticals are promulgated as potent antioxidants. Recent Advances: Experimental support for the efficacy of nutraceuticals has lagged behind anecdotal exuberance. However, accumulating epidemiological evidence and recent, well-controlled clinical trials are beginning to support earlier animal and in vitro studies. Although still somewhat limited, encouraging results have been suggested in essentially all organ systems and against a wide range of pathophysiological conditions. Critical Issues: Health benefits of "antioxidant" nutraceuticals are largely attributed to their ability to scavenge oxidants. This has been criticized based on several factors, including limited bioavailability, short tissue retention time, and the preponderance of endogenous antioxidants. Recent attention has turned to nutraceutical activation of downstream antioxidant systems, especially the Keap1/Nrf2 (Kelch like ECH associated protein 1/nuclear factor erythroid 2-related factor 2) axis. The question now becomes, how do nutraceuticals activate this axis? Future Directions: Reactive sulfur species (RSS), including hydrogen sulfide (H2S) and its metabolites, are potent activators of the Keap1/Nrf2 axis and avid scavengers of reactive oxygen species. Evidence is beginning to accumulate that a variety of nutraceuticals increase cellular RSS by directly providing RSS in the diet, or through a number of catalytic mechanisms that increase endogenous RSS production. We propose that nutraceutical-specific targeting of RSS metabolism will lead to the design and development of even more efficacious antioxidant therapeutic strategies. Antioxid. Redox Signal. 38, 68-94.

α-Lipoic Acid, an Organosulfur Biomolecule a Novel Therapeutic Agent for Neurodegenerative Disorders: An Mechanistic Perspective

Lipoic acid (α-LA) (1,2-dithiolane3-pentanoic acid (C₈H₁₄O₂S₂) is also called thioctic acid with an oxidized (disulfide, LA) and a reduced (di-thiol: dihydro-lipoic acid, DHLA) form of LA. α-LA is a potent anti-oxidative agent that has a significant potential to treat neurodegenerative disorders. α-LA is both hydrophilic and hydrophobic in nature. It is widely distributed in plants and animals in cellular membranes and in the cytosol, which is responsible for LA's action in both the cytosol and plasma membrane. A systematic literature review of Bentham, Scopus, PubMed, Medline, and EMBASE (Elsevier) databases was carried out to understand the Nature and mechanistic interventions of the α-Lipoic acid for central nervous system diseases. Moreover, α-LA readily crosses the blood-brain barrier, which is a significant factor for CNS activities. The mechanisms of α-LA reduction are highly tissue-specific. α-LA produces its neuroprotective effect by inhibiting reactive oxygen species formation and neuronal damage, modulating protein levels, and promoting neurotransmitters and anti-oxidant levels. Hence, the execution of α-LA as a therapeutic ingredient in the therapy of neurodegenerative disorders is promising. Finally, based on evidence, it can be concluded that α-LA can prevent diseases related to the nervous system.

Smouldering multiple sclerosis: the ‘real MS’

Using a philosophical approach or deductive reasoning, we challenge the dominant clinico-radiological worldview that defines multiple sclerosis (MS) as a focal inflammatory disease of the central nervous system (CNS). We provide a range of evidence to argue that the ‘real MS’ is in fact driven primarily by a smouldering pathological disease process. In natural history studies and clinical trials, relapses and focal activity revealed by magnetic resonance imaging (MRI) in MS patients on placebo or on disease-modifying therapies (DMTs) were found to be poor predictors of long-term disease evolution and were dissociated from disability outcomes. In addition, the progressive accumulation of disability in MS can occur independently of relapse activity from early in the disease course. This scenario is underpinned by a more diffuse smouldering pathological process that may affect the entire CNS. Many putative pathological drivers of smouldering MS can be potentially modified by specific therapeutic strategies, an approach that may have major implications for the management of MS patients. We hypothesise that therapeutically targeting a state of ‘no evident inflammatory disease activity’ (NEIDA) cannot sufficiently prevent disability accumulation in MS, meaning that treatment should also focus on other brain and spinal cord pathological processes contributing to the slow loss of neurological function. This should also be complemented with a holistic approach to the management of other systemic disease processes that have been shown to worsen MS outcomes.

Periorbital Nociception in a Progressive Multiple Sclerosis Mouse Model Is Dependent on TRPA1 Channel Activation

Headaches are frequently described in progressive multiple sclerosis (PMS) patients, but their mechanism remains unknown. Transient receptor potential ankyrin 1 (TRPA1) was involved in neuropathic nociception in a model of PMS induced by experimental autoimmune encephalomyelitis (PMS-EAE), and TRPA1 activation causes periorbital and facial nociception. Thus, our purpose was to observe the development of periorbital mechanical allodynia (PMA) in a PMS-EAE model and evaluate the role of TRPA1 in periorbital nociception. Female PMS-EAE mice elicited PMA from day 7 to 14 days after induction. The antimigraine agents olcegepant and sumatriptan were able to reduce PMA. The PMA was diminished by the TRPA1 antagonists HC-030031, A-967079, metamizole and propyphenazone and was absent in TRPA1-deficient mice. Enhanced levels of TRPA1 endogenous agonists and NADPH oxidase activity were detected in the trigeminal ganglion of PMS-EAE mice. The administration of the anti-oxidants apocynin (an NADPH oxidase inhibitor) or alpha-lipoic acid (a sequestrant of reactive oxygen species), resulted in PMA reduction. These results suggest that generation of TRPA1 endogenous agonists in the PMS-EAE mouse model may sensitise TRPA1 in trigeminal nociceptors to elicit PMA. Thus, this ion channel could be a potential therapeutic target for the treatment of headache in PMS patients.

Systematic Review of Studies on Telomere Length in Patients with Multiple Sclerosis

Telomeres are protective cap structures at the end of chromosomes that are essential for maintaining genomic stability. Accelerated telomere shortening is related to premature cellular senescence. Shortened telomere lengths (TL) have been implicated in the pathogenesis of various chronic immune-mediated and neurological diseases. We aimed to systematically review the current literature on the association of TL as a measure of biological age and multiple sclerosis (MS). A comprehensive literature search was conducted to identify original studies that presented data on TL in samples from persons with MS. Quantitative and qualitative information was extracted from the articles to summarize and compare the studies. A total of 51 articles were screened, and 7 of them were included in this review. In 6 studies, average TL were analyzed in peripheral blood cells, whereas in one study, bone marrow-derived cells were used. Four of the studies reported significantly shorter leukocyte TL in at least one MS subtype in comparison to healthy controls (p=0.003 in meta-analysis). Shorter telomeres in patients with MS were found to be associated, independently of age, with greater disability, lower brain volume, increased relapse rate and more rapid conversion from relapsing to progressive MS. However, it remains unclear how telomere attrition in MS may be linked to oxidative stress, inflammation and age-related disease processes. Despite few studies in this field, there is substantial evidence on the association of TL and MS. Variability in TL appears to reflect heterogeneity in clinical presentation and course. Further investigations in large and well-characterized cohorts are warranted. More detailed studies on TL of individual chromosomes in specific cell types may help to gain new insights into the pathomechanisms of MS.

Fatty Acid Synthesis in Glial Cells of the CNS

Fatty acids (FAs) are of crucial importance for brain homeostasis and neural function. Glia cells support the high demand of FAs that the central nervous system (CNS) needs for its proper functioning. Additionally, FAs can modulate inflammation and direct CNS repair, thereby contributing to brain pathologies such Alzheimer’s disease or multiple sclerosis. Intervention strategies targeting FA synthesis in glia represents a potential therapeutic opportunity for several CNS diseases.

TRPA1 involvement in depression- and anxiety-like behaviors in a progressive multiple sclerosis model in mice

Progressive multiple sclerosis (PMS) is a neurological disease associated with the development of depression and anxiety, but treatments available are unsatisfactory. The transient receptor potential ankyrin 1 (TRPA1) is a cationic channel activated by reactive compounds, and the blockage of this receptor can reduce depression- and anxiety-like behaviors in naive mice. Thus, we investigated the role of TRPA1 in depression- and anxiety-like behaviors in a PMS model in mice. PMS model was induced in C57BL/6 female mice by the experimental autoimmune encephalomyelitis (EAE). Nine days after the PMS-EAE induction, behavioral tests (tail suspension and elevated plus maze tests) were performed to verify the effects of sertraline (positive control), selective TRPA1 antagonist (A-967,079), and antioxidants (α-lipoic acid and apocynin). The prefrontal cortex and hippocampus were collected to evaluate biochemical and inflammatory markers. PMS-EAE induction did not cause locomotor changes but triggered depression- and anxiety-like behaviors, which were reversed by sertraline, A-967,079, α-lipoic acid, or apocynin treatments. The neuroinflammatory markers (AIF1, GFAP, IL-1β, IL-17, and TNF-α) were increased in mice's hippocampus. Moreover, this model did not alter TRPA1 RNA expression levels in the hippocampus but decrease TRPA1 levels in the prefrontal cortex. Moreover, PMS-EAE induced an increase in NADPH oxidase and superoxide dismutase activities and TRPA1 endogenous agonist levels (hydrogen peroxide and 4-hydroxynonenal). TRPA1 plays a fundamental role in depression- and anxiety-like behaviors in a PMS-EAE model; thus, it could be a possible pharmacological target for treating these symptoms in PMS.

Kuwanon G protects HT22 cells from advanced glycation end product-induced damage

The incidence of diabetic encephalopathy is increasing as the population ages. Evidence suggests that formation and accumulation of advanced glycation end products (AGEs) plays a pivotal role in disease progression, but limited research has been carried out in this area. A previous study demonstrated that Kuwanon G (KWG) had significant anti-oxidative stress and anti-inflammatory properties. As AGEs are oxidative products and inflammation is involved in their generation it is hypothesized that KWG may have effects against AGE-induced neuronal damage. In the present study, mouse hippocampal neuronal cell line HT22 was used. KWG was shown to significantly inhibit AGE-induced cell apoptosis in comparison with a control treatment, as determined by both MTT and flow cytometry. Compared with the AGEs group, expression of pro-apoptotic protein Bax was reduced and expression of anti-apoptotic protein Bcl-2 was increased in the AGEs + KWG group. Both intracellular and extracellular levels of acetylcholine and choline acetyltransferase were significantly elevated after KWG administration in comparison with controls whilethe level of acetylcholinesterase decreased. These changes in protein expression were accompanied by increased levels of superoxide dismutase and glutathione peroxidase synthesis and reduced production of malondialdehyde and reactive oxygen species. Intracellular signaling pathway protein levels were determined by western blot and immunocytochemistry. KWG administration was found to prevent AGE-induced changes to the phosphorylation levels of Akt, IκB-α, glycogen synthase kinase 3 (GSK3)-α and β, p38 MAPK and NF-κB p65 suggesting a potential neuroprotective effect of KWG against AGE-induced damage was via the PI3K/Akt/GSK3αβ signaling pathway. The findings of the present study suggest that KWG may be a potential treatment for diabetic encephalopathy.

Are Reactive Sulfur Species the New Reactive Oxygen Species?

Significance: Oxidative stress in moderation positively affects homeostasis through signaling, while in excess it is associated with adverse health outcomes. Both activities are generally attributed to reactive oxygen species (ROS); hydrogen peroxide as the signal, and cysteines on regulatory proteins as the target. However, using antioxidants to affect signaling or benefit health has not consistently translated into expected outcomes, or when it does, the mechanism is often unclear. Recent Advances: Reactive sulfur species (RSS) were integral in the origin of life and throughout much of evolution. Sophisticated metabolic pathways that evolved to regulate RSS were easily "tweaked" to deal with ROS due to the remarkable similarities between the two. However, unlike ROS, RSS are stored, recycled, and chemically more versatile. Despite these observations, the relevance and regulatory functions of RSS in extant organisms are generally underappreciated. Critical Issues: A number of factors bias observations in favor of ROS over RSS. Research conducted in room air is hyperoxic to cells, and promotes ROS production and RSS oxidation. Metabolic rates of rodent models greatly exceed those of humans; does this favor ROS? Analytical methods designed to detect ROS also respond to RSS. Do these disguise the contributions of RSS? Future Directions: Resolving the ROS/RSS issue is vital to understand biology in general and human health in particular. Improvements in experimental design and analytical methods are crucial. Perhaps the most important is an appreciation of all the attributes of RSS and keeping an open mind.

In Vivo Proton Exchange Rate (kex ) MRI for the Characterization of Multiple Sclerosis Lesions in Patients

BACKGROUND

Currently available radiological methods do not completely capture the diversity of multiple sclerosis (MS) lesion subtypes. This lack of information hampers the understanding of disease progression and potential treatment stratification. For example, inflammation persists in some lesions after gadolinium (Gd) enhancement resolves. Novel metabolic and molecular imaging methods may improve the current assessments of MS pathophysiology.

PURPOSE

To compare the in vivo proton exchange rate (k_ex ) MRI with Gd-enhanced MRI for characterizing MS lesions.

STUDY TYPE

Retrospective.

SUBJECTS

Sixteen consecutively diagnosed relapsing-remitting multiple sclerosis (RRMS) patients.

FIELD STRENGTH/SEQUENCE

3.0T MRI with T₂ -weighted imaging, postcontrast T₁ -weighted imaging, and single-slice chemical exchange saturation transfer imaging.

ASSESSMENT

MS lesions in white matter were assessed for Gd enhancement and k_ex elevation compared to normal-appearing white matter (NAWM).

STATISTICAL TESTS

Student's t-test was used for analyzing the difference of k_ex values between lesions and NAWM, with statistical significance set at 0.05.

RESULTS

Of all 153 MS lesions, 78 (51%) lesions were Gd-enhancing and 75 (49%) were Gd-negative. Without exception, all 78 Gd-enhancing lesions showed significantly elevated k_ex values compared to NAWM (924 ± 130 s^-1 vs. 735 ± 61 s^-1 , P < 0.05). Of 75 Gd-negative lesions, 18 lesions (24%) showed no k_ex elevation (762 ± 29 s^-1 vs. 755 ± 28 s^-1 , P = 0.47) and 57 (76%) showed significant k_ex elevation (950 ± 124 s^-1 vs. 759 ± 48 s^-1 , P < 0.05) compared to NAWM. MS lesions with k_ex elevation appeared nodular (118, 87.4%), ring-like (15, 11.1%), or irregular-shaped (2, 1.5%).

DATA CONCLUSION

For Gd-enhancing lesions, k_ex MRI is highly consistent with Gd-enhanced images by showing 100% of elevated k_ex . For all Gd-negative lesions, the discrepancy on k_ex MRI may further differentiate active slowly expanding lesions or chronic inactive lesions, supporting k_ex as an imaging biomarker for tissue oxidative stress and inflammation. Level of Evidence 2 Technical Efficacy Stage 3 J. MAGN. RESON. IMAGING 2021;53:408-415.

How the redox state regulates immunity

Oxidative stress is defined as an imbalance between the levels of reactive oxygen species (ROS) and antioxidant defences. The view of oxidative stress as a cause of cell damage has evolved over the past few decades to a much more nuanced view of the role of oxidative changes in cell physiology. This is no more evident than in the field of immunity, where oxidative changes are now known to regulate many aspects of the immune response, and inflammatory pathways in particular. Our understanding of redox regulation of immunity now encompasses not only increases in reactive oxygen and nitrogen species, but also changes in the activities of oxidoreductase enzymes. These enzymes are important regulators of immune pathways both via changes in their redox activity, but also via other more recently identified cytokine-like functions. The emerging picture of redox regulation of immune pathways is one of increasing complexity and while therapeutic targeting of the redox environment to treat inflammatory disease is a possibility, any such strategy is likely to be more nuanced than simply inhibiting ROS production.

Klotho Pathways, Myelination Disorders, Neurodegenerative Diseases, and Epigenetic Drugs

In this review we outline a rationale for identifying neuroprotectants aimed at inducing endogenous Klotho activity and expression, which is epigenetic action, by definition. Such an approach should promote remyelination and/or stimulate myelin repair by acting on mitochondrial function, thereby heralding a life-saving path forward for patients suffering from neuroinflammatory diseases. Disorders of myelin in the nervous system damage the transmission of signals, resulting in loss of vision, motion, sensation, and other functions depending on the affected nerves, currently with no effective treatment. Klotho genes and their single-pass transmembrane Klotho proteins are powerful governors of the threads of life and death, true to the origin of their name, Fates, in Greek mythology. Among its many important functions, Klotho is an obligatory co-receptor that binds, activates, and/or potentiates critical fibroblast growth factor activity. Since the discovery of Klotho a little over two decades ago, it has become ever more apparent that when Klotho pathways go awry, oxidative stress and mitochondrial dysfunction take over, and age-related chronic disorders are likely to follow. The physiological consequences can be wide ranging, potentially wreaking havoc on the brain, eye, kidney, muscle, and more. Central nervous system disorders, neurodegenerative in nature, and especially those affecting the myelin sheath, represent worthy targets for advancing therapies that act upon Klotho pathways. Current drugs for these diseases, even therapeutics that are disease modifying rather than treating only the symptoms, leave much room for improvement. It is thus no wonder that this topic has caught the attention of biomedical researchers around the world.

Nociception in a Progressive Multiple Sclerosis Model in Mice Is Dependent on Spinal TRPA1 Channel Activation

Central neuropathic pain is a common untreated symptom in progressive multiple sclerosis (PMS) and is associated with poor quality of life and interference with patients' daily activities. The neuroinflammation process and mitochondrial dysfunction in the PMS lesions generate reactive species. The transient potential receptor ankyrin 1 (TRPA1) has been identified as one of the major mechanisms that contribute to neuropathic pain signaling and can be activated by reactive compounds. Thus, the goal of our study was to evaluate the role of spinal TRPA1 in the central neuropathic pain observed in a PMS model in mice. We used C57BL/6 female mice (20-30 g), and the PMS model was induced by the experimental autoimmune encephalomyelitis (EAE) using mouse myelin oligodendrocyte glycoprotein (MOG_35-55) antigen and CFA (complete Freund's adjuvant). Mice developed progressive clinical score, with motor impairment observed after 15 days of induction. This model induced mechanical and cold allodynia and heat hyperalgesia which were measured up to 14 days after induction. The hypersensitivity observed was reduced by the administration of selective TRPA1 antagonists (HC-030031 and A-967079, via intrathecal and intragastric), antioxidants (α-lipoic acid and apocynin, via intrathecal and intragastric), and TRPA1 antisense oligonucleotide (via intrathecal). We also observed an increase in TRPA1 mRNA levels, NADPH oxidase activity, and 4-hydroxinonenal (a TRPA1 agonist) levels in spinal cord samples of PMS-EAE induced animals. In conclusion, these results support the hypothesis of the TRPA1 receptor involvement in nociception observed in a PMS-EAE model in mice.

A Simplified Method for Simultaneous Determination of α-Lipoic Acid and Low-Molecular-Mass Thiols in Human Plasma

α-Lipoic acid, glutathione, cysteine, and cysteinylglycine can be applied as therapeutic agents in civilization diseases such as diabetes mellitus, cardiovascular diseases, and cancers. On the other hand, a higher concentration of homocysteine can result in health problems and has been indicated as an independent risk factor for cardiovascular disease and accelerated atherosclerosis. Here, the first simplified HPLC-UV assay that enables simultaneous determination of α-lipoic acid and low-molecular-mass thiols in plasma, reduces the number of steps, shortens the total time of sample preparation, and limits the amount of single-use polypropylene laboratory materials is described. The assay is based on reversed-phase high performance liquid chromatography with UV detection and simultaneous reduction of disulfide bound with tris(2-carboxyethyl)phosphine and the selective pre-column derivatization of the thiol group with 1-benzyl-2-chloropyridinium bromide. Linearity in the detector responses for plasma samples were observed in ranges: 0.12-5.0 nmol mL^-1 for α-lipoic acid; 2.0-20.0 nmol mL^-1 for glutathione, cysteinylglycine, and homocysteine; and 40.0-400.0 for cysteine. The LODs for α-lipoic acid and low-molecular-mass thiols were 0.08 and 0.12 nmol mL^-1, respectively, while LOQs were 0.12 and 0.16 nmol mL^-1, respectively. The usefulness of the proposed method has been proven by its application to real samples.

Redox phospholipidomics of enzymatically generated oxygenated phospholipids as specific signals of programmed cell death

High fidelity and effective adaptive changes of the cell and tissue metabolism to changing environments require strict coordination of numerous biological processes. Multicellular organisms developed sophisticated signaling systems of monitoring and responding to these different contexts. Among these systems, oxygenated lipids play a significant role realized via a variety of re-programming mechanisms. Some of them are enacted as a part of pro-survival pathways that eliminate harmful or unnecessary molecules or organelles by a variety of degradation/hydrolytic reactions or specialized autophageal processes. When these "partial" intracellular measures are insufficient, the programs of cells death are triggered with the aim to remove irreparably damaged members of the multicellular community. These regulated cell death mechanisms are believed to heavily rely on signaling by a highly diversified group of molecules, oxygenated phospholipids (PLox). Out of thousands of detectable individual PLox species, redox phospholipidomics deciphered several specific molecules that seem to be diagnostic of specialized death programs. Oxygenated cardiolipins (CLs) and phosphatidylethanolamines (PEs) have been identified as predictive biomarkers of apoptosis and ferroptosis, respectively. This has led to decoding of the enzymatic mechanisms of their formation involving mitochondrial oxidation of CLs by cytochrome c and endoplasmic reticulum-associated oxidation of PE by lipoxygenases. Understanding of the specific biochemical radical-mediated mechanisms of these oxidative reactions opens new avenues for the design and search of highly specific regulators of cell death programs. This review emphasizes the usefulness of such selective lipid peroxidation mechanisms in contrast to the concept of random poorly controlled free radical reactions as instruments of non-specific damage of cells and their membranes. Detailed analysis of two specific examples of phospholipid oxidative signaling in apoptosis and ferroptosis along with their molecular mechanisms and roles in reprogramming has been presented.

Are the beneficial effects of 'antioxidant' lipoic acid mediated through metabolism of reactive sulfur species?

The health benefits of lipoic acid (LA) are generally attributed to mitigating the harmful effects of reactive oxygen species (ROS). ROS are chemically similar to reactive sulfur species (RSS) and signal through identical mechanisms. Here we examined the effects of LA on RSS in HEK293 cells using H₂S and polysulfide (PS) specific fluorophores, AzMC and SSP4. We show that LA concentration-dependently increased both H₂S and PS. Physioxia (5% O₂) augmented the effects of LA on H₂S production but decreased PS production. Thiosulfate, a known substrate for reduced LA, and an intermediate in the catabolism of H₂S enhanced the effects of LA on H₂S and PS production. Inhibiting peroxiredoxins with conoidin A and gluraredoxins with tiopronin augmented the effects of LA on PS and H₂S, respectively while decreasing glutathione with buthionine-sulfoximine (BSO) or diethyl maleate (DEM) decreased the stimulatory effect of LA on H₂S production but augmented LA's effect on PS. Aminooxyacetate (AOA) and propargylglycine (PPG), inhibitors of H₂S production from cysteine partially inhibited LA augmentation of H₂S production and further decreased the LA effect when applied concurrently with BSO and DEM. The selective and cell-permeable H₂S scavenger, SS20, inhibited the effects of LA on cellular H₂S. Estimates of single-cell H₂S production suggest that 0.1-0.2% of O₂ consumption is used to metabolize H₂S and these requirements may increase to 1-2% with 1 mM LA. Collectively, these results suggest that LA rescues H₂S from irreversible oxidation and that the effects of LA on RSS directly confer antioxidant, anti-inflammatory and cytoprotective responses. They also suggest that TS may be an effective supplement to increase the efficacy of LA in clinical settings.