Neurodegeneration in Multiple Sclerosis: The Role of Nrf2-Dependent Pathways

Glial connexins in glaucoma

Glial cells play a crucial role in maintaining central nervous system (CNS) homeostasis and facilitating the repair of neural tissue following injury. The regulation of neuroglia may serve as a safe and effective strategy for modulating neuroinflammatory responses and restoring glial homeostasis and defense functions. Given that the glial network is composed of connexin (CX) proteins, its neuroprotective role is extensive. Therefore, connexins should be considered as functional "bridges" within this network. This review examines evidence for the active involvement of glial networks in neuroinflammation under both physiological and pathological conditions and summarizes the role of CXs in glaucoma. Finally, potential therapeutic strategies for glaucoma are explored.

Health position paper and redox perspectives - Bench to bedside transition for pharmacological regulation of NRF2 in noncommunicable diseases

Nuclear factor erythroid 2-related factor 2 (NRF2) is a redox-activated transcription factor regulating cellular defense against oxidative stress, thereby playing a pivotal role in maintaining cellular homeostasis. Its dysregulation is implicated in the progression of a wide array of human diseases, making NRF2 a compelling target for therapeutic interventions. However, challenges persist in drug discovery and safe targeting of NRF2, as unresolved questions remain especially regarding its context-specific role in diseases and off-target effects. This comprehensive review discusses the dualistic role of NRF2 in disease pathophysiology, covering its protective and/or destructive roles in autoimmune, respiratory, cardiovascular, and metabolic diseases, as well as diseases of the digestive system and cancer. Additionally, we also review the development of drugs that either activate or inhibit NRF2, discuss main barriers in translating NRF2-based therapies from bench to bedside, and consider the ways to monitor NRF2 activation in vivo.

The neurotoxic effects of lead acetate and the abrogating actions of 6-gingerol-rich extract of ginger via modulation of antioxidant defence system, pro-inflammatory markers, and apoptotic cascade

Lead exposure is a public health concern and it has been linked to cognitive deficit, memory impairment, and neurotoxicity. This study was designed to investigate the effect of 6-gingerol-rich extract of ginger (6-GREG) on oxidative stress, inflammation, and apoptosis in lead acetate (PbAc)-induced neurotoxicity in male Wistar rats. Twenty-five (25) male Wistar rats in total were divided into five groups at random (n = 5). The control group received 0.5 ml of normal saline, the PbAc-treated group received 7.5 mg/kg of PbAc, the vitamin C, 6-GREG (100), and 6-GREG (200) groups received 7.5 mg/kg of PbAc followed by administration of vitamin C (100 mg/kg), 6-GREG (100 mg/kg), and 6-GREG (200 mg/kg) respectively for 2 weeks. Following behavioral tests, the rats were euthanized, and their brain tissues were homogenized for biochemical analysis. When compared to the control group, the administration of PbAc caused behavioral alterations as well as a significant (p < 0.05) decrease in the activities of catalase, glutathione peroxidase, as well as reduced glutathione and Bcl-2 levels in the PbAc-treated group. Furthermore, the PbAc-treated group showed a statistically significant rise (p < 0.05) in brain acetylcholinesterase, malondialdehyde, nitric oxide, interleukin-1-beta, tumor necrosis factor-α, and caspase-9 levels in comparison to the control. Administration of both 100 mg/kg and 200 mg/kg of 6-GREG effectively reversed these behavioral and biochemical changes in 6-GREG (100)- and 6-GREG (200)-treated groups respectively compared to the PbAc-treated group. Consequently, the study reveals the role of 6-GREG in attenuating PbAc-induced neurotoxicity and brain damage via antioxidative, anti-inflammatory, and anti-apoptotic mechanisms.

Extra Virgin Olive Oil Polyphenol-Enriched Extracts Exert Antioxidant and Anti-Inflammatory Effects on Peripheral Blood Mononuclear Cells from Rheumatoid Arthritis Patients

Rheumatoid arthritis (RA) is a long-term systemic autoimmune disorder that causes joint inflammation, swelling, pain, bone erosion, and deformities. Recent findings emphasize the anti-inflammatory and antioxidant properties of bioactive natural compounds, such as polyphenols extracted from plants and fruits, and their possible synergistic effect when used in combination with current therapies to improve the prognosis and symptoms of inflammatory rheumatic diseases. Here, we report that Sicilian extra virgin olive oil polyphenol-enriched extracts (PE-EVOOs) reduce intracellular reactive oxygen species (ROS) and pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin-1 β (IL-1β), in peripheral mononuclear cells (PBMCs) obtained from both RA patients and healthy subjects (HSs) treated with lipopolysaccharides (LPS) as a control. HPLC-ESI-MS analysis highlighted that PE-EVOOs are rich in different polyphenolic compounds responsible for many of the observed biological effects. At molecular levels, Western blotting analyses revealed that PE-EVOO treatment is associated with the downregulation of the phosphorylated and active form of the inflammatory transcription factor NF-κB and the pro-inflammatory enzyme cyclooxygenase 2 (COX2). In addition, PE-EVOOs upregulated the transcription factor Nrf2 and its target antioxidant enzyme catalase and manganese superoxide dismutase (MnSOD). Collectively, these results suggest a possible use of PE-EVOOs as potential adjuvants for the treatment of RA.

A Window into New Insights on Progression Independent of Relapse Activity in Multiple Sclerosis: Role of Therapies and Current Perspective

In multiple sclerosis (MS), there is significant evidence indicating that both progression independent of relapse activity (PIRA) and relapse-related worsening events contribute to the accumulation of progressive disability from the onset of the disease and throughout its course. Understanding the compartmentalized pathophysiology of MS would enhance comprehension of disease progression mechanisms, overcoming the traditional distinction in phenotypes. Smoldering MS activity is thought to be maintained by a continuous interaction between the parenchymal chronic processes of neuroinflammation and neurodegeneration and the intrathecal compartment. This review provides a comprehensive and up-to-date overview of the neuropathological and immunological evidence related to the mechanisms underlying PIRA phenomena in MS, with a focus on studies investigating the impact of currently available therapies on these complex mechanisms.

Unknown roles of tau pathology in neurological disorders. Challenges and new perspectives

Aging presents progressive changes that increase the susceptibility of the central nervous system (CNS) to suffer neurological disorders (NDs). Several studies have reported that an aged brain suffering from NDs shows the presence of pathological forms of tau protein, a microtubule accessory protein (MAP) critical for neuronal function. In this context, accumulative evidence has shown a pivotal contribution of pathological forms of tau to Alzheimer's disease (AD) and tauopathies. However, current investigations have implicated tau toxicity in other NDs that affect the central nervous system (CNS), including Parkinson's disease (PD), Huntington's disease (HD), Traumatic brain injury (TBI), Multiple sclerosis (MS), and Amyotrophic lateral sclerosis (ALS). These diseases are long-term acquired, affecting essential functions such as motor movement, cognition, hearing, and vision. Previous evidence indicated that toxic forms of tau do not have a critical contribution to the genesis or progression of these diseases. However, recent studies have shown that these tau forms contribute to neuronal dysfunction, inflammation, oxidative damage, and mitochondrial impairment events that contribute to the pathogenesis of these NDs. Recent studies have suggested that these neuropathologies could be associated with a prion-like behavior of tau, which induces a pathological dissemination of these toxic protein forms to different brain areas. Moreover, it has been suggested that this toxic propagation of tau from neurons into neighboring cells impairs the function of glial cells, oligodendrocytes, and endothelial cells by affecting metabolic function and mitochondrial health and inducing oxidative damage by tau pathology. Therefore, in this review, we will discuss current evidence demonstrating the critical role of toxic tau forms on NDs not related to AD and how its propagation and induced-bioenergetics failure may contribute to the pathogenic mechanism present in these NDs.

Rlip76 in ageing and Alzheimer's disease: Focus on oxidative stress and mitochondrial mechanisms

RLIP76 (Rlip), a stress-responsive protein, plays a multifaceted role in cellular function. This protein acts primarily as a glutathione-electrophile conjugate (GS-E) transporter, crucial for detoxifying hazardous compounds and converting them into mercapturic acids. RLIP76 also modulates cytoskeletal motility and membrane plasticity through its role in the Ral-signaling pathway, interacting with RalA and RalB, key small GTPases involved in growth and metastasis. Beyond its ATP-dependent transport functions in various tissues, RLIP76 also demonstrates GTPase Activating Protein (GAP) activity towards Rac1 and Cdc42, with a preference for Ral-GTP over Ral-GDP. Its functions span critical physiological processes including membrane dynamics, oxidative stress response, and mitochondrial dynamics. The protein's widespread expression and evolutionary conservation underscore its significance. Our lab discovered that Rlip interacts with Alzheimer's disease (AD) proteins, amyloid beta and phosphorylated and induce oxidative stress, mitochondrial dysfnction and synaptic damage in AD. Our in vitro studies revealed that overexpression of Rlip reduces mitochondrial abnormalities. Further, our in vivo studies (Rlip+/- mice) revealed that a partial reduction of Rlip in mice (Rlip+/-), leads to mitochondrial abnormalities, elevated oxidative stress, and cognitive deficits resembling late-onset AD, emphasizing the protein's crucial role in neuronal health and disease. Finally, we discuss the experimental cross-breedings of overexpression of mice Rlip TG/TG or Rlip + /- mice with Alzheimer's disease models - earlyonset 5XFAD, late-onset APPKI and Tau transgenic mice, providing new insights into RLIP76's role in AD progression and development. This review summarizes RLIP76's structure, function, and cellular pathways, highlighting its implications in AD and its potential as a therapeutic target.

Comparative Effects of Vitamin D Supplementation on Oxidative Stress in Relapsing-Remitting Multiple Sclerosis

Studies suggest that vitamin D (VitD) may reduce oxidative stress (OS) in multiple sclerosis (MS) patients. This study aimed to compare the effects of various VitD doses on OS in relapsing-remitting MS (RRMS). A 6-month supplementation was introduced using two doses of VitD: 2000 IU/day in the high-dose group (HD, n = 23) and 15,960 IU/month in the low-dose group (LD, n = 29). Significant differences in body weight, height, and age were found between groups. A significant increase in the level of VitD (25(OH)D) was noted in both groups (p < 0.01). A significant increase was observed in the levels of LF and MDA (p < 0.01) and a significant decrease in the concentrations of PSH (p < 0.01), CuZnSOD (p = 0.02), and TOS (p < 0.01). A significant positive correlation was observed between serum VitD and SOD (R = 0.38, p < 0.01) and MnSOD (R = 0.31, p < 0.05), as well as a significant negative correlation between serum VitD and MDA (R = -0.31, p = 0.05) at the beginning of the study. At the end of the study, a significant positive correlation was observed between serum VitD and SOD (R = 0.34, p < 0.05) and CuZnSOD (R = 0.51, p < 0.01). In RRMS patients, the VitD doses are probably insufficient to induce a beneficial effect on the pro- and antioxidant balance.

Should We Consider Neurodegeneration by Itself or in a Triangulation with Neuroinflammation and Demyelination? The Example of Multiple Sclerosis and Beyond

Neurodegeneration is preeminent in many neurological diseases, and still a major burden we fail to manage in patient's care. Its pathogenesis is complicated, intricate, and far from being completely understood. Taking multiple sclerosis as an example, we propose that neurodegeneration is neither a cause nor a consequence by itself. Mitochondrial dysfunction, leading to energy deficiency and ion imbalance, plays a key role in neurodegeneration, and is partly caused by the oxidative stress generated by microglia and astrocytes. Nodal and paranodal disruption, with or without myelin alteration, is further involved. Myelin loss exposes the axons directly to the inflammatory and oxidative environment. Moreover, oligodendrocytes provide a singular metabolic and trophic support to axons, but do not emerge unscathed from the pathological events, by primary myelin defects and cell apoptosis or secondary to neuroinflammation or axonal damage. Hereby, trophic failure might be an overlooked contributor to neurodegeneration. Thus, a complex interplay between neuroinflammation, demyelination, and neurodegeneration, wherein each is primarily and secondarily involved, might offer a more comprehensive understanding of the pathogenesis and help establishing novel therapeutic strategies for many neurological diseases and beyond.

Isolation and Characterization of the Cyanobacterial Macrolide Glycoside Moorenaside, an Anti-Inflammatory Analogue of Aurisides Targeting the Keap1/Nrf2 Pathway

A new 14-membered ring brominated macrolide glycoside, named moorenaside (1), was discovered from a marine cyanobacterial sample collected from Shands Key in Florida. The structure of 1 was established by analysis of spectroscopic data including its relative configuration. The absolute configuration was inferred from optical rotation data and comparison with related compounds. The structure of 1 features an α,β-unsaturated carbonyl system, which is also found in aurisides. The presence of this motif in 1 prompted us to evaluate its effect on Keap1/Nrf2 signaling, a cytoprotective pathway culminating in the activation of antioxidant genes activated upstream by the cysteine alkylation of Keap1. Moorenaside exhibited moderate ARE luciferase activity at 32 μM. Due to the established crosstalk between Nrf2 and NF-κB pathways, we investigated the anti-inflammatory effects of 1 in LPS-induced mouse macrophages (RAW264.7 cells), a commonly used model for inflammation. Moorenaside significantly upregulated Nqo1 (Nrf2 target gene) and downregulated iNos (NF-κB target gene) at 32 μM by 5.0- and 2.5-fold, respectively, resulting in a significant reduction of nitric oxide (NO) levels. Furthermore, we performed RNA-sequencing and demonstrated the transcriptional activity of 1 on a global level and identified canonical pathways and upstream regulators involved in inflammation, immune response, and certain oxidative-stress-underlying diseases such as multiple sclerosis and chronic kidney disease.

Discovery and Optimization of a Series of Vinyl Sulfoximine-Based Analogues as Potent Nrf2 Activators for the Treatment of Multiple Sclerosis

Multiple sclerosis (MS) is an immune-mediated neurodegenerative disease of the central nervous system (CNS), which leads to demyelination, axonal loss, and neurodegeneration. Increased oxidative stress and neurodegeneration have been implicated in all stages of MS, making neuroprotective therapeutics a promising strategy for its treatment. We previously have reported vinyl sulfones with antioxidative and anti-inflammatory properties that activate nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor that induces the expression of cytoprotective genes against oxidative stress. In this study, we synthesized vinyl sulfoximine derivatives by modifying the core structure and determined therapeutic potential as Nrf2 activators. Among them, 10v effectively activated Nrf2 (EC50 = 83.5 nM) and exhibited favorable drug-like properties. 10v successfully induced expression of Nrf2-dependent antioxidant enzymes and suppressed lipopolysaccharide (LPS)-induced inflammatory responses in BV-2 microglial cells. We also confirmed that 10v effectively reversed disease progression and attenuated demyelination in an experimental autoimmune encephalitis (EAE) mouse model of MS.

A novel ferroptosis inhibitor, Thonningianin A, improves Alzheimer's disease by activating GPX4

Background: Ferroptosis, a recently unveiled iron-dependent form of cellular demise, has emerged as a pivotal process contributing to the pathology of Alzheimer's Disease (AD). Glutathione Peroxidase 4 (GPX4), a vital defense mechanism countering ferroptosis by nullifying lipid peroxides and maintaining cellular redox equilibrium, has garnered significant attention in AD. Thus, identifying ferroptosis inhibitors to target GPX4 activation may help mitigate neuronal damage and impede AD progression. Objectives: We aimed to screen potent ferroptosis inhibitors and investigate their mechanism of action and therapeutic potential in AD, as well as lay the groundwork for future research in this promising area of study. Methods: This study employed a natural compound library to screen potential ferroptosis inhibitors in RAS-selective lethal compounds 3 (RSL-3)-induced PC-12 cells. Ferroptosis was evaluated by examining the mitochondrial morphology and function, reactive oxygen species (ROS) production, and lipid peroxide levels. The ability to chelate iron and intracellular iron levels was determined by UHPLC-Q/TOF-MS/MS and PGSK staining, respectively. APP Swe/ind- or Tau P301L-overexpressing PC-12 cells, and Amyloid-β transgenic CL4176 and Tau transgenic BR5270 Caenorhabditis elegans were employed as cellular and animal models of AD. Results: Thonningianin A (ThA) was identified as a novel ferroptosis inhibitor, as demonstrated by augmented cellular viability, mitigated mitochondrial impairment, diminished lipid peroxides, iron levels, and ROS generation. Mechanistically, ThA binds with GPX4 and enhances the AMPK/Nrf2 signaling pathway to stimulate GPX4 activation, effectively inhibiting ferroptosis. Moreover, in cellular and Caenorhabditis elegans AD models, ThA substantially inhibits ferroptosis by reducing ROS, lipid peroxide generation, and iron accumulation. Furthermore, ThA significantly delays paralysis, ameliorates food-sensing deficits and increases worms' antioxidative capacity. Conclusion: ThA ameliorates AD by inhibiting neuronal ferroptosis mediated by GPX4 activation through its binding with GPX4 and the upregulation of the AMPK/Nrf2/GPX4 pathway.

Evidence for TGF-β1/Nrf2 Signaling Crosstalk in a Cuprizone Model of Multiple Sclerosis

Multiple sclerosis (MS) is a chronic and degenerative disease that impacts central nervous system (CNS) function. One of the major characteristics of the disease is the presence of regions lacking myelin and an oxidative and inflammatory environment. TGF-β1 and Nrf2 proteins play a fundamental role in different oxidative/inflammatory processes linked to neurodegenerative diseases such as MS. The evidence from different experimental settings has demonstrated a TGF-β1-Nrf2 signaling crosstalk under pathological conditions. However, this possibility has not been explored in experimental models of MS. Here, by using the cuprizone-induced demyelination model of MS, we report that the in vivo pharmacological blockage of the TGF-β1 receptor reduced Nrf2, catalase, and TGFβ-1 protein levels in the demyelination phase of cuprizone administration. In addition, ATP production, locomotor function and cognitive performance were diminished by the treatment. Altogether, our results provide evidence for a crosstalk between TGF-β1 and Nrf2 signaling pathways under CNS demyelination, highlighting the importance of the antioxidant cellular response of neurodegenerative diseases such as MS.

A preclinical mice model of multiple sclerosis based on the toxin-induced double-site demyelination of callosal and cerebellar fibers

BACKGROUND

Multiple sclerosis (MS) is an irreversible progressive CNS pathology characterized by the loss of myelin (i.e. demyelination). The lack of myelin is followed by a progressive neurodegeneration triggering symptoms as diverse as fatigue, motor, locomotor and sensory impairments and/or bladder, cardiac and respiratory dysfunction. Even though there are more than fourteen approved treatments for reducing MS progression, there are still no cure for the disease. Thus, MS research is a very active field and therefore we count with different experimental animal models for studying mechanisms of demyelination and myelin repair, however, we still lack a preclinical MS model assembling demyelination mechanisms with relevant clinical-like signs.

RESULTS

Here, by inducing the simultaneous demyelination of both callosal and cerebellar white matter fibers by the double-site injection of lysolecithin (LPC), we were able to reproduce CNS demyelination, astrocyte recruitment and increases levels of proinflammatory cytokines levels along with motor, locomotor and urinary impairment, as well as cardiac and respiratory dysfunction, in the same animal model. Single site LPC-injections either in corpus callosum or cerebellum only, fails in to reproduce such a complete range of MS-like signs.

CONCLUSION

We here report that the double-site LPC injections treatment evoke a complex MS-like mice model. We hope that this experimental approach will help to deepen our knowledge about the mechanisms of demyelinated diseases such as MS.

Arbutin intervention ameliorates memory impairment in a rat model of lysolecethin induced demyelination: Neuroprotective and anti-inflammatory effects

Cognitive impairment (CI) and memory deficit are prevalent manifestations of multiple sclerosis (MS). This study explores the therapeutic potential of arbutin on memory deficits using a rat hippocampal demyelination model induced by lysophosphatidylcholine (LPC). Demyelination was induced by bilateral injection of 1% LPC into the CA1 area of the hippocampus, and the treated group received daily arbutin injections (50 mg/kg, i.p) for two weeks. Arbutin significantly improved memory impairment 14 days post-demyelination as assessed by Morris water maze test. Histological and immunohistochemical analyses demonstrated that arbutin reduced demyelination suppressed pro-inflammatory markers (IL-1β, TNF-α) and increased anti-inflammatory cytokine IL-10. Arbutin also diminished astrocyte activation, decreased iNOS, enhanced anti-oxidative factors (Nrf2, HO-1), and exhibited neuroprotective effects by elevating myelin markers (MBP) and brain derived neurotrophic factor (BDNF). These findings propose arbutin as a potential therapeutic candidate for multiple sclerosis-associated memory deficits, warranting further clinical exploration.

Immunopathogenesis of multiple sclerosis: molecular and cellular mechanisms and new immunotherapeutic approaches

BACKGROUND

Multiple sclerosis (MS) is a central nervous system (CNS) demyelinating autoimmune disease with increasing global prevalence. It predominantly affects females, especially those of European descent. The interplay between environmental factors and genetic predisposition plays a crucial role in MS etiopathogenesis.

METHODS

We searched recent relevant literature on reputable databases, which include, PubMed, Embase, Web of Science, Scopus, and ScienceDirect using the following keywords: multiple sclerosis, pathogenesis, autoimmunity, demyelination, therapy, and immunotherapy.

RESULTS

Various animal models have been employed to investigate the MS etiopathogenesis and therapeutics. Autoreactive T cells within the CNS recruit myeloid cells through chemokine expression, leading to the secretion of inflammatory cytokines driving the MS pathogenesis, resulting in demyelination, gliosis, and axonal loss. Key players include T cell lymphocytes (CD4+ and CD8+), B cells, and neutrophils. Signaling dysregulation in inflammatory pathways and the immunogenetic basis of MS are essential considerations for any successful therapy to MS. Data indicates that B cells and neutrophils also have significant roles in MS, despite the common belief that T cells are essential. High neutrophil-to-lymphocyte ratios correlate with MS severity, indicating their contribution to disease progression. Dysregulated signaling pathways further exacerbate MS progression.

CONCLUSION

MS remains incurable, but disease-modifying therapies, monoclonal antibodies, and immunomodulatory drugs offer hope for patients. Research on the immunogenetics and immunoregulatory functions of gut microbiota is continuing to provide light on possible treatment avenues. Understanding the complex interplay between genetic predisposition, environmental factors, and immune dysregulation is critical for developing effective treatments for MS.

Promising use of metformin in treating neurological disorders: biomarker-guided therapies

Neurological disorders are a diverse group of conditions that affect the nervous system and include neurodegenerative diseases (Alzheimer's disease, multiple sclerosis, Parkinson's disease, Huntington's disease), cerebrovascular conditions (stroke), and neurodevelopmental disorders (autism spectrum disorder). Although they affect millions of individuals around the world, only a limited number of effective treatment options are available today. Since most neurological disorders express mitochondria-related metabolic perturbations, metformin, a biguanide type II antidiabetic drug, has attracted a lot of attention to be repurposed to treat neurological disorders by correcting their perturbed energy metabolism. However, controversial research emerges regarding the beneficial/detrimental effects of metformin on these neurological disorders. Given that most neurological disorders have complex etiology in their pathophysiology and are influenced by various risk factors such as aging, lifestyle, genetics, and environment, it is important to identify perturbed molecular functions that can be targeted by metformin in these neurological disorders. These molecules can then be used as biomarkers to stratify subpopulations of patients who show distinct molecular/pathological properties and can respond to metformin treatment, ultimately developing targeted therapy. In this review, we will discuss mitochondria-related metabolic perturbations and impaired molecular pathways in these neurological disorders and how these can be used as biomarkers to guide metformin-responsive treatment for the targeted therapy to treat neurological disorders.

Recent progress and applications of small molecule inhibitors of Keap1-Nrf2 axis for neurodegenerative diseases

The Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) pathway serves as a crucial regulator against oxidative stress (OS) damage in various cells and organs. It has garnered significant attention as a potential therapeutic target for neurodegenerative diseases (NDD). Although progress has been achieved in strategies to regulate the Keap1-Nrf2 pathway, the availability of Nrf2 activators applicable to NDD is currently limited. Currently, the FDA has approved the Nrf2 activators dimethyl fumarate (DMF) and Omaveloxolone (Omav) as novel first-line oral drugs for the treatment of patients with relapsing forms of multiple sclerosis and Friedreich's ataxia. A promising alternative approach involves the direct inhibition of Keap1-Nrf2 protein-protein interactions (PPI), which offers numerous advantages over the use of electrophilic Nrf2 activators, primarily in avoiding off-target effects. This review examines the compelling evidence supporting the beneficial role of Nrf2 in NDD and explores the potential of Keap1 inhibitors and Keap1-Nrf2 PPI inhibitors as therapeutic agents, with the aim to provide further insights into the development of inhibitors targeting this pathway for the treatment of NDD.

Toward identifying key mechanisms of progression in multiple sclerosis

A major therapeutic goal in the treatment of multiple sclerosis (MS) is to prevent the accumulation of disability over an often decades-long disease course. Disability progression can result from acute relapses as well as from CNS intrinsic parenchymal disintegration without de novo CNS lesion formation. Research focus has shifted to progression not associated with acute inflammation, as it is not sufficiently controlled by currently available treatments. This review outlines how recent advances in the understanding of the pathogenesis of progressive MS have been facilitated by the development of more precise, less static pathogenetic concepts of progressive MS, as well as by new techniques for the analysis of region-specific proteomic and transcriptomic signatures in the human CNS. We highlight key drivers of MS disease progression and potential targets in its treatment.

The Potential Association Between microRNA 135-5P and p62 and Their Effect on NRF2 Pathway in Multiple Sclerosis

Background

Multiple Sclerosis (MS) is a prevalent non-traumatic disabling disease affecting young adults, characterized by complexity in its pathogenesis. Nuclear factor erythroid 2-Related Factor 2 (NRF2) serves as a crucial transcriptional regulator of anti-inflammatory and antioxidant enzymes, influenced by the ubiquitous protein p62. It acts as a scaffold directing substrates to autophagosomes. This study aims to explore the potential association between microRNA 135-5p and p62 and their impact on inflammation and oxidative stress through the NRF2 pathway in MS.

Methods

The study included 30 healthy controls and 60 MS patients (relapsing-remitting and secondary progressive). Real-time PCR was employed for the detection of Nrf2, p62, miRNA135-5P, and NF-κB in serum, while p53 levels were determined using ELISA.

Results

Nrf2 and p62 expression was significantly downregulated in the MS group compared to controls. Conversely, miRNA135-5P, NF-κB expression, and P53 levels were significantly elevated in the MS group.

Conclusions

This study reveals a potential association between miRNA 135-5p and p62, indicating their role in the pathogenesis of MS. Results suggest that miRNA 135-5p and p62 may influence inflammation and oxidative stress in MS through the NRF2 pathway, potentially mediated by NF-κB and p53.

Oxidative Stress and the Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2) Pathway in Multiple Sclerosis: Focus on Certain Exogenous and Endogenous Nrf2 Activators and Therapeutic Plasma Exchange Modulation

The pathogenesis of multiple sclerosis (MS) suggests that, in genetically susceptible subjects, T lymphocytes undergo activation in the peripheral compartment, pass through the BBB, and cause damage in the CNS. They produce pro-inflammatory cytokines; induce cytotoxic activities in microglia and astrocytes with the accumulation of reactive oxygen species, reactive nitrogen species, and other highly reactive radicals; activate B cells and macrophages and stimulate the complement system. Inflammation and neurodegeneration are involved from the very beginning of the disease. They can both be affected by oxidative stress (OS) with different emphases depending on the time course of MS. Thus, OS initiates and supports inflammatory processes in the active phase, while in the chronic phase it supports neurodegenerative processes. A still unresolved issue in overcoming OS-induced lesions in MS is the insufficient endogenous activation of the Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2) pathway, which under normal conditions plays an essential role in mitochondria protection, OS, neuroinflammation, and degeneration. Thus, the search for approaches aiming to elevate endogenous Nrf2 activation is capable of protecting the brain against oxidative damage. However, exogenous Nrf2 activators themselves are not without drawbacks, necessitating the search for new non-pharmacological therapeutic approaches to modulate OS. The purpose of the present review is to provide some relevant preclinical and clinical examples, focusing on certain exogenous and endogenous Nrf2 activators and the modulation of therapeutic plasma exchange (TPE). The increased plasma levels of nerve growth factor (NGF) in response to TPE treatment of MS patients suggest their antioxidant potential for endogenous Nrf2 enhancement via NGF/TrkA/PI3K/Akt and NGF/p75NTR/ceramide-PKCζ/CK2 signaling pathways.

Discovery and Anti-Inflammatory Activity of a Cyanobacterial Fatty Acid Targeting the Keap1/Nrf2 Pathway

The monounsaturated fatty acid 7(E)-9-keto-hexadec-7-enoic acid (1) and three structurally related analogues with different oxidation states and degrees of unsaturation (2-4) were discovered from a marine benthic cyanobacterial mat collected from Delta Shoal, Florida Keys. Their structures were elucidated using NMR spectroscopy and mass spectrometry. The structure of 1 contained an α,β-unsaturated carbonyl system, a key motif required for the activation of the Keap1/Nrf2-ARE pathway that is involved in the activation of antioxidant and phase II detoxification enzymes. Compounds 1-4 were screened in ARE-luciferase reporter gene assay using stably transfected HEK293 cells, and only 1 significantly induced Nrf2 activity at 32 and 10 µM, whereas 2-4 were inactive. As there is crosstalk between inflammation and oxidative stress, subsequent biological studies were focused on 1 to investigate its anti-inflammatory potential. Compound 1 induced Nqo1, a well-known target gene of Nrf2, and suppressed iNos transcript levels, which translated into reduced levels of nitric oxide in LPS-activated mouse macrophage RAW264.7 cells, a more relevant model for inflammation. RNA sequencing was performed to capture the effects of 1 on a global level and identified additional canonical pathways and upstream regulators involved in inflammation and immune response, particularly those related to multiple sclerosis. A targeted survey of marine cyanobacterial samples from other geographic locations, including Guam, suggested the widespread occurrence of 1. Furthermore, the previous isolation of 1 from marine diatoms and green algae implied a potentially important ecological role across marine algal eukaryotes and prokaryotes. The previous isolation from sea lettuce raises the possibility of dietary intervention to attenuate inflammation and related disease progression.

Auranofin Modulates Thioredoxin Reductase/Nrf2 Signaling in Peripheral Immune Cells and the CNS in a Mouse Model of Relapsing-Remitting EAE

Multiple sclerosis (MS) is one of the most prevalent chronic inflammatory autoimmune diseases. It causes the demyelination of neurons and the subsequent degeneration of the central nervous system (CNS). The infiltration of leukocytes of both myeloid and lymphoid origins from the systemic circulation into the CNS triggers autoimmune reactions through the release of multiple mediators. These mediators include oxidants, pro-inflammatory cytokines, and chemokines which ultimately cause the characteristic plaques observed in MS. Thioredoxin reductase (TrxR) and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling plays a crucial role in the regulation of inflammation by modulating the transcription of antioxidants and the suppression of inflammatory cytokines. The gold compound auranofin (AFN) is known to activate Nrf2 through the inhibition of TrxR; however, the effects of this compound have not been explored in a mouse model of relapsing-remitting MS (RRMS). Therefore, this study explored the influence of AFN on clinical features, TrxR/Nrf2 signaling [heme oxygenase 1 (HO-1), superoxide dismutase 1 (SOD-1)] and oxidative/inflammatory mediators [IL-6, IL-17A, inducible nitric oxide synthase (iNOS), myeloperoxidase (MPO), nitrotyrosine] in peripheral immune cells and the CNS of mice with the RR type of EAE. Our results showed an increase in TrxR activity and a decrease in Nrf2 signaling in SJL/J mice with RR-EAE. The treatment with AFN caused the amelioration of the clinical features of RR-EAE through the elevation of Nrf2 signaling and the subsequent upregulation of the levels of antioxidants as well as the downregulation of oxidative/pro-inflammatory mediators in peripheral immune cells and the CNS. These data suggest that AFN may be beneficial in the treatment of RRMS.

The Gut-Brain Axis as a Therapeutic Target in Multiple Sclerosis

The CNS is very susceptible to oxidative stress; the gut microbiota plays an important role as a trigger of oxidative damage that promotes mitochondrial dysfunction, neuroinflammation, and neurodegeneration. In the current review, we discuss recent findings on oxidative-stress-related inflammation mediated by the gut-brain axis in multiple sclerosis (MS). Growing evidence suggests targeting gut microbiota can be a promising strategy for MS management. Intricate interaction between multiple factors leads to increased intra- and inter-individual heterogeneity, frequently painting a different picture in vivo from that obtained under controlled conditions. Following an evidence-based approach, all proposed interventions should be validated in clinical trials with cohorts large enough to reach significance. Our review summarizes existing clinical trials focused on identifying suitable interventions, the suitable combinations, and appropriate timings to target microbiota-related oxidative stress. Most studies assessed relapsing-remitting MS (RRMS); only a few studies with very limited cohorts were carried out in other MS stages (e.g., secondary progressive MS-SPMS). Future trials must consider an extended time frame, perhaps starting with the perinatal period and lasting until the young adult period, aiming to capture as many complex intersystem interactions as possible.