Crosstalk Between Oxidative Stress and Mitochondrial Damage: Focus on Amyotrophic Lateral Sclerosis

The presence and clinical significance of autoantibodies in amyotrophic lateral sclerosis: a narrative review

Amyotrophic lateral sclerosis (ALS) is a debilitating and rapidly fatal neurodegenerative disease, which is characterized by the selective loss of the upper and lower motor neurons. The pathogenesis of ALS remains to be elucidated and has been connected to genetic, environmental and immune conditions. Evidence from clinical and experimental studies has suggested that the immune system played an important role in ALS pathophysiology. Autoantibodies are essential components of the immune system. Several autoantibodies directed at antigens associated with ALS pathogenesis have been identified in the serum and/or cerebrospinal fluid of ALS patients. The aim of this review is to summarize the presence and clinical significance of autoantibodies in ALS.

Oxidative Cysteine Post Translational Modifications Drive the Redox Code Underlying Neurodegeneration and Amyotrophic Lateral Sclerosis

Redox dysregulation, an imbalance between oxidants and antioxidants, is crucial in the pathogenesis of various neurodegenerative diseases. Within this context, the "redoxome" encompasses the network of redox molecules collaborating to maintain cellular redox balance and signaling. Among these, cysteine-sensitive proteins are fundamental for this homeostasis. Due to their reactive thiol groups, cysteine (Cys) residues are particularly susceptible to oxidative post-translational modifications (PTMs) induced by free radicals (reactive oxygen, nitrogen, and sulfur species) which profoundly affect protein functions. Cys-PTMs, forming what is referred to as "cysteinet" in the redox proteome, are essential for redox signaling in both physiological and pathological conditions, including neurodegeneration. Such modifications significantly influence protein misfolding and aggregation, key hallmarks of neurodegenerative diseases such as Alzheimer's, Parkinson's, and notably, amyotrophic lateral sclerosis (ALS). This review aims to explore the complex landscape of cysteine PTMs in the cellular redox environment, elucidating their impact on neurodegeneration at protein level. By investigating specific cysteine-sensitive proteins and the regulatory networks involved, particular emphasis is placed on the link between redox dysregulation and ALS, highlighting this pathology as a prime example of a neurodegenerative disease wherein such redox dysregulation is a distinct hallmark.

A Cellular Model of Amyotrophic Lateral Sclerosis to Study the Therapeutic Effects of Extracellular Vesicles from Adipose Mesenchymal Stem Cells on Microglial Activation

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive degeneration of upper and lower motor neurons (MNs) in the brain and spinal cord, leading to progressive paralysis and death. Increasing evidence indicates that neuroinflammation plays an important role in ALS's pathogenesis and disease progression. Neuroinflammatory responses, primarily driven by activated microglia and astrocytes, and followed by infiltrating peripheral immune cells, contribute to exacerbate/accelerate MN death. In particular, the role of the microglia in ALS remains unclear, partly due to the lack of experimental models that can fully recapitulate the complexity of ALS's pathology. In this study, we developed and characterized a microglial cell line, SIM-A9-expressing human mutant protein Cu+/Zn+ superoxide dismutase_1 (SIM-A9hSOD1(G93A)), as a suitable model in vitro mimicking the microglia activity in ALS. The expression of hSOD1(G93A) in SIM-A9 cells induced a change in their metabolic activity, causing polarization into a pro-inflammatory phenotype and enhancing reactive oxygen species production, which is known to activate cell death processes and apoptosis. Afterward, we used our microglial model as an experimental set-up to investigate the therapeutic action of extracellular vesicles isolated from adipose mesenchymal stem cells (ASC-EVs). ASC-EVs represent a promising therapeutic treatment for ALS due to their neuroprotective and immunomodulatory properties. Here, we demonstrated that treatment with ASC-EVs is able to modulate activated ALS microglia, reducing their metabolic activity and polarizing their phenotype toward an anti-inflammatory one through a mechanism of reduction of reactive oxygen species.

Increased Vulnerability to Ferroptosis in FUS-ALS

Ferroptosis, a regulated form of cell death characterized by iron-dependent lipid peroxide accumulation, plays a pivotal role in various pathological conditions, including neurodegenerative diseases. While reasonable evidence for ferroptosis exists, e.g., in Parkinson's disease or Alzheimer's disease, there are only a few reports on amyotrophic lateral sclerosis (ALS), a fast progressive and incurable neurodegenerative disease characterized by progressive motor neuron degeneration. Interestingly, initial studies have suggested that ferroptosis might be significantly involved in ALS. Key features of ferroptosis include oxidative stress, glutathione depletion, and alterations in mitochondrial morphology and function, mediated by proteins such as GPX4, xCT, ACSL4 FSP1, Nrf2, and TfR1. Induction of ferroptosis involves small molecule compounds like erastin and RSL3, which disrupt system Xc- and GPX4 activity, respectively, resulting in lipid peroxidation and cellular demise. Mutations in fused in sarcoma (FUS) are associated with familial ALS. Pathophysiological hallmarks of FUS-ALS involve mitochondrial dysfunction and oxidative damage, implicating ferroptosis as a putative cell-death pathway in motor neuron demise. However, a mechanistic understanding of ferroptosis in ALS, particularly FUS-ALS, remains limited. Here, we investigated the vulnerability to ferroptosis in FUS-ALS cell models, revealing mitochondrial disturbances and increased susceptibility to ferroptosis in cells harboring ALS-causing FUS mutations. This was accompanied by an altered expression of ferroptosis-associated proteins, particularly by a reduction in xCT expression, leading to cellular imbalance in the redox system and increased lipid peroxidation. Iron chelation with deferoxamine, as well as inhibition of the mitochondrial calcium uniporter (MCU), significantly alleviated ferroptotic cell death and lipid peroxidation. These findings suggest a link between ferroptosis and FUS-ALS, offering potential new therapeutic targets.

Honokiol alleviated neurodegeneration by reducing oxidative stress and improving mitochondrial function in mutant SOD1 cellular and mouse models of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease affecting both upper and lower motor neurons (MNs) with large unmet medical needs. Multiple pathological mechanisms are considered to contribute to the progression of ALS, including neuronal oxidative stress and mitochondrial dysfunction. Honokiol (HNK) has been reported to exert therapeutic effects in several neurologic disease models including ischemia stroke, Alzheimer's disease and Parkinson's disease. Here we found that honokiol also exhibited protective effects in ALS disease models both in vitro and in vivo. Honokiol improved the viability of NSC-34 motor neuron-like cells that expressed the mutant G93A SOD1 proteins (SOD1-G93A cells for short). Mechanistical studies revealed that honokiol alleviated cellular oxidative stress by enhancing glutathione (GSH) synthesis and activating the nuclear factor erythroid 2-related factor 2 (NRF2)-antioxidant response element (ARE) pathway. Also, honokiol improved both mitochondrial function and morphology via fine-tuning mitochondrial dynamics in SOD1-G93A cells. Importantly, honokiol extended the lifespan of the SOD1-G93A transgenic mice and improved the motor function. The improvement of antioxidant capacity and mitochondrial function was further confirmed in the spinal cord and gastrocnemius muscle in mice. Overall, honokiol showed promising preclinical potential as a multiple target drug for ALS treatment.

Does the Gut Microbial Metabolome Really Matter? The Connection between GUT Metabolome and Neurological Disorders

Herein we gathered updated knowledge regarding the alterations of gut microbiota (dysbiosis) and its correlation with human neurodegenerative and brain-related diseases, e.g., Alzheimer’s and Parkinson’s. This review underlines the importance of gut-derived metabolites and gut metabolic status as the main players in gut-brain crosstalk and their implications on the severity of neural conditions. Scientific evidence indicates that the administration of probiotic bacteria exerts beneficial and protective effects as reduced systemic inflammation, neuroinflammation, and inhibited neurodegeneration. The experimental results performed on animals, but also human clinical trials, show the importance of designing a novel microbiota-based probiotic dietary supplementation with the aim to prevent or ease the symptoms of Alzheimer’s and Parkinson’s diseases or other forms of dementia or neurodegeneration.

Oxidative Stress in Amyotrophic Lateral Sclerosis: Synergy of Genetic and Environmental Factors

Amyotrophic lateral sclerosis (ALS) is a grievous neurodegenerative disease whose survival is limited to only a few years. In spite of intensive research to discover the underlying mechanisms, the results are fairly inconclusive. Multiple hypotheses have been regarded, including genetic, molecular, and cellular processes. Notably, oxidative stress has been demonstrated to play a crucial role in ALS pathogenesis. In addition to already recognized and exhaustively studied genetic mutations involved in oxidative stress production, exposure to various environmental factors (e.g., electromagnetic fields, solvents, pesticides, heavy metals) has been suggested to enhance oxidative damage. This review aims to describe the main processes influenced by the most frequent genetic mutations and environmental factors concurring in oxidative stress occurrence in ALS and the potential therapeutic molecules capable of diminishing the ALS related pro-oxidative status.

Ceramide and Sphingosine-1-Phosphate in Neurodegenerative Disorders and Their Potential Involvement in Therapy

Neurodegenerative disorders (ND) are progressive diseases of the nervous system, often without resolutive therapy. They are characterized by a progressive impairment and loss of specific brain regions and neuronal populations. Cellular and animal model studies have identified several molecular mechanisms that play an important role in the pathogenesis of ND. Among them are alterations of lipids, in particular sphingolipids, that play a crucial role in neurodegeneration. Overall, during ND, ceramide-dependent pro-apoptotic signalling is promoted, whereas levels of the neuroprotective spingosine-1-phosphate are reduced. Moreover, ND are characterized by alterations of the metabolism of complex sphingolipids. The finding that altered sphingolipid metabolism has a role in ND suggests that its modulation might provide a useful strategy to identify targets for possible therapies. In this review, based on the current literature, we will discuss how bioactive sphingolipids (spingosine-1-phosphate and ceramide) are involved in some ND (Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis) and their possible involvement in therapies.

Neurons undergo pathogenic metabolic reprogramming in models of familial ALS

Objectives

Methods

Results

Conclusions

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Our work is the first to perform a comprehensive and quantitative analysis of intermediary metabolism in neurons in the setting of fALS causing gene products.

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Because the cardinal feature of ALS is death of motor neurons, these new studies are directly relevant to the pathogenesis of ALS.

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Our functional interrogations begin to unpack how metabolic re-wiring is induced by fALS genes and it will be very interesting, in the future, to gain insight in amino acid fueling of the TCA cycle.

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We suspect pleiotropic effects of amino acid fueling, and this may lead to very targeted therapeutic interventions.

Amyotrophic Lateral Sclerosis After Exposure to Manganese from Traditional Medicine Procedures in Kenya

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by motor neuron loss and widespread muscular atrophy. Despite intensive investigations on genetic and environmental factors, the cause of ALS remains unknown. Recent data suggest a role for metal exposures in ALS causation. In this study we present a patient who developed ALS after a traditional medical procedure in Kenya. The procedure involved insertion of a black metal powder into several subcutaneous cuts in the lower back. Four months later, general muscle weakness developed. Clinical and electrophysiological examinations detected widespread denervation consistent with ALS. The patient died from respiratory failure less than a year after the procedure. Scanning electron microscopy and X-ray diffraction analyses identified the black powder as potassium permanganate (KMnO4). A causative relationship between the systemic exposure to KMnO4 and ALS development can be suspected, especially as manganese is a well-known neurotoxicant previously found to be elevated in cerebrospinal fluid from ALS patients. Manganese neurotoxicity and exposure routes conveying this toxicity deserve further attention.

Gut dysbiosis, defective autophagy and altered immune responses in neurodegenerative diseases: Tales of a vicious cycle

The human microbiota comprises trillions of symbiotic microorganisms and is involved in regulating gastrointestinal (GI), immune, nervous system and metabolic homeostasis. Recent observations suggest a bidirectional communication between the gut microbiota and the brain via immune, circulatory and neural pathways, termed the Gut-Brain Axis (GBA). Alterations in gut microbiota composition, such as seen with an increased number of pathobionts and a decreased number of symbionts, termed gut dysbiosis or microbial intestinal dysbiosis, plays a prominent role in the pathogenesis of central nervous system (CNS)-related disorders. Clinical reports confirm that GI symptoms often precede neurological symptoms several years before the development of neurodegenerative diseases (NDDs). Pathologically, gut dysbiosis disrupts the integrity of the intestinal barrier leading to ingress of pathobionts and toxic metabolites into the systemic circulation causing GBA dysregulation. Subsequently, chronic neuroinflammation via dysregulated immune activation triggers the accumulation of neurotoxic misfolded proteins in and around CNS cells resulting in neuronal death. Emerging evidence links gut dysbiosis to the aggravation and/or spread of proteinopathies from the peripheral nervous system to the CNS and defective autophagy-mediated proteinopathies. This review summarizes the current understanding of the role of gut microbiota in NDDs, and highlights a vicious cycle of gut dysbiosis, immune-mediated chronic neuroinflammation, impaired autophagy and proteinopathies, which contributes to the development of neurodegeneration in Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, amyotrophic lateral sclerosis and frontotemporal lobar degeneration. We also discuss novel therapeutic strategies targeting the modulation of gut dysbiosis through prebiotics, probiotics, synbiotics or dietary interventions, and faecal microbial transplantation (FMT) in the management of NDDs.

[The role of sphingolipids in pathogenesis of amyotrophic lateral sclerosis]

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease characterized by selective degeneration of motor neurons of the spinal cord and motor cortex and brain stem. The key features of the course of this disease are excitotoxicity, oxidative stress, mitochondrial dysfunction, neuro-inflammatory and immune reactions. Recently, the mechanisms of programmed cell death (apoptosis), which may be responsible for the degeneration of motor neurons in this disease, have been intensively studied. In this regard, sphingolipids, which are the most important sources of secondary messengers that transmit cell proliferation, differentiation and apoptosis signals, and are involved in the development of neuroinflammatory and immune responses, are of particular interest in the context of ALS pathogenesis. The review provides information from domestic and foreign authors on the involvement of various sphingolipids (sphingomyelins, ceramides, sphingosine, sphinganin, sphingosine-1-phosphate, galactosylceramides, glucosylceramides, gangliosides) in the development of pro-inflammatory reactions and apoptosis of motor neurons in ALS. The authors discuss the prospects of using new drugs that control the metabolism of sphingolipids for the treatment of ALS.

The Neuroprotective Effect of Tea Polyphenols on the Regulation of Intestinal Flora

Tea polyphenols (TPs) are the general compounds of natural polyhydroxyphenols extracted in tea. Although a large number of studies have shown that TPs have obvious neuroprotective and neuro repair effects, they are limited due to the low bioavailability in vivo. However, TPs can act indirectly on the central nervous system by affecting the “microflora–gut–brain axis”, in which the microbiota and its composition represent a factor that determines brain health. Bidirectional communication between the intestinal microflora and the brain (microbe–gut–brain axis) occurs through a variety of pathways, including the vagus nerve, immune system, neuroendocrine pathways, and bacteria-derived metabolites. This axis has been shown to influence neurotransmission and behavior, which is usually associated with neuropsychiatric disorders. In this review, we discuss that TPs and their metabolites may provide benefits by restoring the imbalance of intestinal microbiota and that TPs are metabolized by intestinal flora, to provide a new idea for TPs to play a neuroprotective role by regulating intestinal flora.

Investigating Different Forms of Hydrogen Sulfide in Cerebrospinal Fluid of Various Neurological Disorders

Over the past 30 years a considerable amount of data has accumulated on the multifaceted role of hydrogen sulfide (H₂S) in the central nervous system. Depending on its concentrations, H₂S has opposite actions, ranging from neuromodulator to neurotoxic. Nowadays, accurate determination of H₂S is still an important challenge to understand its biochemistry and functions. In this perspective, this study aims to explore H₂S levels in cerebrospinal fluid (CSF), key biofluid for neurological studies, and to assess alleged correlations with neuroinflammatory and neurodegenerative mechanisms. A validated analytical determination combining selective electrochemical detection with ion chromatography was developed to measure free and bound sulfur forms of H₂S. A first cohort of CSF samples (n = 134) was analyzed from patients with inflammatory and demyelinating disorders (acute disseminated encephalomyelitis; multiple sclerosis), chronic neurodegenerative diseases (Alzheimer disease; Parkinson disease), and motor neuron disease (Amyotrophic lateral sclerosis). Given its analytical features, the chromatographic method resulted sensitive, reproducible and robust. We also explored low molecular weight-proteome linked to sulphydration by proteomics analysis on matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). This study is a first clinical report on CSF H₂S concentrations from neurological diseases and opens up new perspectives on the potential clinical relevance of H₂S and its potential therapeutic application.

Behavioral, Hormonal, Inflammatory, and Metabolic Effects Associated with FGF21-Pathway Activation in an ALS Mouse Model

In amyotrophic lateral sclerosis (ALS), motor neuron degeneration occurs simultaneously with systemic metabolic dysfunction and neuro-inflammation. The fibroblast growth factor 21 (FGF21) plays an important role in the regulation of both phenomena and is a major hormone of energetic homeostasis. In this study, we aimed to determine the relevance of FGF21 pathway stimulation in a male mouse model of ALS (mutated SOD1-G93A mice) by using a pharmacological agonist of FGF21, R1Mab1. Mice (SOD1-WT and mutant SOD1-G93A) were treated with R1Mab1 or vehicle. Longitudinal data about clinical status (motor function, body weight) and biological parameters (including hormonal, immunological, and metabolomics profiles) were collected from the first symptoms to euthanasia at week 20. Multivariate models were performed to identify the main parameters associated with R1Mab1 treatment and to link them with clinical status, and metabolic pathways involving the discriminant metabolites were also determined. A beneficial clinical effect of R1Mab1 was revealed on slow rotarod (p = 0.032), despite a significant decrease in body weight of ALS mice (p < 0.001). We observed a decrease in serum TNF-α, MCP-1, and insulin levels (p = 0.0059, p = 0.003, and p = 0.01, respectively). At 16 weeks, metabolomics analyses revealed a clear discrimination (CV-ANOVA = 0.0086) according to the treatment and the most discriminant pathways, including sphingolipid metabolism, butanoate metabolism, pantothenate and CoA biosynthesis, and the metabolism of amino acids like tyrosine, arginine, proline, glycine, serine, alanine, aspartate, and glutamate. Mice treated with R1Mab1 had mildly higher performance on slow rotarod despite a decrease on body weight and could be linked with the anti-inflammatory effect of R1Mab1. These results indicate that FGF21 pathway is an interesting target in ALS, with a slight improvement in motor function combined with metabolic and anti-inflammatory effects.

Copper-ATSM as a Treatment for ALS: Support from Mutant SOD1 Models and Beyond

The blood-brain barrier permeant, copper-containing compound, CuII(atsm), has successfully progressed from fundamental research outcomes in the laboratory through to phase 2/3 clinical assessment in patients with the highly aggressive and fatal neurodegenerative condition of amyotrophic lateral sclerosis (ALS). The most compelling outcomes to date to indicate potential for disease-modification have come from pre-clinical studies utilising mouse models that involve transgenic expression of mutated superoxide dismutase 1 (SOD1). Mutant SOD1 mice provide a very robust mammalian model of ALS with high validity, but mutations in SOD1 account for only a small percentage of ALS cases in the clinic, with the preponderant amount of cases being sporadic and of unknown aetiology. As per other putative drugs for ALS developed and tested primarily in mutant SOD1 mice, this raises important questions about the pertinence of CuII(atsm) to broader clinical translation. This review highlights some of the challenges associated with the clinical translation of new treatment options for ALS. It then provides a brief account of pre-clinical outcomes for CuII(atsm) in SOD1 mouse models of ALS, followed by an outline of additional studies which report positive outcomes for CuII(atsm) when assessed in cell and mouse models of neurodegeneration which do not involve mutant SOD1. Clinical evidence for CuII(atsm) selectively targeting affected regions of the CNS in patients is also presented. Overall, this review summarises the existing evidence which indicates why clinical relevance of CuII(atsm) likely extends beyond the context of cases of ALS caused by mutant SOD1.

Astragalus polysaccharide inhibits radiation-induced bystander effects by regulating apoptosis in Bone Mesenchymal Stem Cells (BMSCs)

The purpose of this study was to investigate the effects of astragalus polysaccharides (APS) on the proliferation and apoptosis of bone marrow mesenchymal stem cells (BMSCs) induced by X-ray radiation-induced A549 cells bystander effect (RIBE), and to explore their mechanisms. In this study, APS increased the reduced cell proliferation rate induced by RIBE and inhibiting the apoptosis of bystander cells. In terms of mechanism, APS up-regulates the proteins Bcl-2, Bcl-xl, and down-regulates the proteins Bax and Bak, which induces a decrease in mitochondrial membrane potential, which induces the release of Cyt-c and AIF, which leads to caspase-dependent and caspase-independent pathway to cause apoptosis. In addition, we believe that ROS may be the main cause of these protein changes. APS can inhibit the generation of ROS in bystander cells and thus inhibit the activation of the mitochondrial pathway, further preventing cellular damage caused by RIBE.

Air Pollution-Related Brain Metal Dyshomeostasis as a Potential Risk Factor for Neurodevelopmental Disorders and Neurodegenerative Diseases

Increasing evidence links air pollution (AP) exposure to effects on the central nervous system structure and function. Particulate matter AP, especially the ultrafine (nanoparticle) components, can carry numerous metal and trace element contaminants that can reach the brain in utero and after birth. Excess brain exposure to either essential or non-essential elements can result in brain dyshomeostasis, which has been implicated in both neurodevelopmental disorders (NDDs; autism spectrum disorder, schizophrenia, and attention deficit hyperactivity disorder) and neurodegenerative diseases (NDGDs; Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and amyotrophic lateral sclerosis). This review summarizes the current understanding of the extent to which the inhalational or intranasal instillation of metals reproduces in vivo the shared features of NDDs and NDGDs, including enlarged lateral ventricles, alterations in myelination, glutamatergic dysfunction, neuronal cell death, inflammation, microglial activation, oxidative stress, mitochondrial dysfunction, altered social behaviors, cognitive dysfunction, and impulsivity. Although evidence is limited to date, neuronal cell death, oxidative stress, and mitochondrial dysfunction are reproduced by numerous metals. Understanding the specific contribution of metals/trace elements to this neurotoxicity can guide the development of more realistic animal exposure models of human AP exposure and consequently lead to a more meaningful approach to mechanistic studies, potential intervention strategies, and regulatory requirements.

MicroRNAs in amyotrophic lateral sclerosis: from pathogenetic involvement to diagnostic biomarker and therapeutic agent development

MicroRNAs (miRNAs) are a class of endogenous non-coding small single-stranded RNAs that are 21-25 nucleotides (NTs) in length and participate in post-transcriptional gene regulation. Studies have shown that miRNA dysfunction plays a critical role in the occurrence and development of a variety of nervous system diseases, including neurodegenerative diseases. Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with an unclear etiology and is characterized by the selective invasion of motor neurons in the brain and spinal cord. Symptoms can range from mild spasms in the limbs or medulla oblongata muscles to paralysis in almost all skeletal muscles. The role of miRNAs in the pathogenesis, diagnosis, and treatment of ALS has become of greater importance to those studying ALS. In this review, we reviewed experimentally confirmed miRNAs shown to be involved in the pathogenesis of ALS and that are used as diagnostic biomarkers or therapeutic ALS agents. At present, there are at least 20-30 genes clearly related to the pathogenesis of ALS. Multiple miRNAs have been reported in different pathogenic gene models. MiRNAs could be used as biomarkers for the diagnosis of ALS; the differential expression of some miRNAs could be related to ALS prognosis. As therapeutic agents, miRNAs are still in the exploratory stage. Although encouraging results have been achieved using animal models, much research is still needed before clinical trials can ensue. However, with additional miRNA studies in ALS patients and animal models, the pathogenesis, early diagnosis, and therapy of ALS should be elucidated.

Gut-Brain Axis and Neurodegeneration: State-of-the-Art of Meta-Omics Sciences for Microbiota Characterization

Recent advances in the field of meta-omics sciences and related bioinformatics tools have allowed a comprehensive investigation of human-associated microbiota and its contribution to achieving and maintaining the homeostatic balance. Bioactive compounds from the microbial community harboring the human gut are involved in a finely tuned network of interconnections with the host, orchestrating a wide variety of physiological processes. These includes the bi-directional crosstalk between the central nervous system, the enteric nervous system, and the gastrointestinal tract (i.e., gut-brain axis). The increasing accumulation of evidence suggest a pivotal role of the composition and activity of the gut microbiota in neurodegeneration. In the present review we aim to provide an overview of the state-of-the-art of meta-omics sciences including metagenomics for the study of microbial genomes and taxa strains, metatranscriptomics for gene expression, metaproteomics and metabolomics to identify and/or quantify microbial proteins and metabolites, respectively. The potential and limitations of each discipline were highlighted, as well as the advantages of an integrated approach (multi-omics) to predict microbial functions and molecular mechanisms related to human diseases. Particular emphasis is given to the latest results obtained with these approaches in an attempt to elucidate the link between the gut microbiota and the most common neurodegenerative diseases, such as multiple sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS).

Exploring Sphingolipid Implications in Neurodegeneration

Over the past decade, it was found that relatively simple sphingolipids, such as ceramide, sphingosine, sphingosine-1-phosphate, and glucosylceramide play important roles in neuronal functions by regulating rates of neuronal growth and differentiation. Homeostasis of membrane sphingolipids in neurons and myelin is essential to prevent the loss of synaptic plasticity, cell death and neurodegeneration. In our review we summarize data about significant brain cell alterations of sphingolipids in different neurodegenerative diseases such as Alzheimer's disease, Parkinson disease, Amyotrophic Lateral Sclerosis, Gaucher's, Farber's diseases, etc. We reported results obtained in brain tissue from both animals in which diseases were induced and humans in autopsy samples. Moreover, attention was paid on sphingolipids in biofluids, liquor and blood, from patients. In Alzheimer's disease sphingolipids are involved in the processing and aggregation of β-amyloid and in the transmission of the cytotoxic signal β-amyloid and TNFα-induced. Recently, the gangliosides metabolism in transgenic animals and the relationship between blood sphingolipids changes and cognitive impairment in Alzheimer's disease patients have been intensively studied. Numerous experiments have highlighted the involvement of ceramide and monohexosylceramide metabolism in the pathophysiology of the sporadic forms of Parkinson's disease. Moreover, gene mutations of the glucocerebrosidase enzyme were considered as responsible for Parkinson's disease via transition of the monomeric form of α-synuclein to an oligomeric, aggregated toxic form. Disturbances in the metabolism of ceramides were also associated with the appearance of Lewy's bodies. Changes in sphingolipid metabolism were found as a manifestation of Amyotrophic Lateral Sclerosis, both sporadic and family forms, and affected the rate of disease development. Currently, fingolimod (FTY720), a sphingosine-1-phosphate receptor modulator, is the only drug undergoing clinical trials of phase II safety for the treatment of Amyotrophic Lateral Sclerosis. The use of sphingolipids as new diagnostic markers and as targets for innovative therapeutic strategies in different neurodegenerative disorders has been included.

Targeted apoptosis of myofibroblasts by elesclomol inhibits hypertrophic scar formation

Background

Hypertrophic scar (HS) is characterized by the increased proliferation and decreased apoptosis of myofibroblasts. Myofibroblasts, the main effector cells for dermal fibrosis, develop from normal fibroblasts. Thus, the stimulation of myofibroblast apoptosis is a possible treatment for HS. We aimed to explore that whether over-activated myofibroblasts can be targeted for apoptosis by anticancer drug elesclomol.

Methods

4′,6-diamidino-2-phenylindole staining, flow cytometry, western blotting, collagen gel contraction and immunofluorescence assays were applied to demonstrate the proapoptotic effect of elesclomol in scar derived myofibroblasts and TGF-β1 induced myofibroblasts. The therapeutic potential of elesclomol was investigated by establishing rabbit ear hypertrophic scar models.

Findings

Both 4′,6-diamidino-2-phenylindole staining and flow cytometry indicated that elesclomol targets myofibroblasts in vitro. Collagen gel contraction assay showed that elesclomol inhibited myofibroblast contractility. Flow cytometry and western blot analysis revealed that elesclomol resulted in excessive intracellular levels of reactive oxygen species(ROS), and caspase-3 and cytochrome c proteins. Moreover, compared with the control group, the elesclomol group had a significantly lower scar elevation index in vivo. Immunofluorescence assays for TUNEL and α-smooth muscle actin indicated that elesclomol treatment increased the number of apoptotic myofibroblasts.

Interpretation

The above results indicate that elesclomol exerted a significant inhibitory effect on HS formation via targeted myofibroblast apoptosis associated with increased oxidative stress. Thus, elesclomol is a promising candidate drug for the treatment of myofibroblast-related diseases such as HS.

Extract of Cornus officinalis Protects Keratinocytes from Particulate Matter-induced Oxidative Stress

The skin is one of the large organs in the human body and the most exposed to outdoor contaminants such as particulate matter < 2.5 µm (PM_2.5). Recently, we reported that PM_2.5 induced cellular macromolecule disruption of lipids, proteins, and DNA, via reactive oxygen species, eventually causing cellular apoptosis of human keratinocytes. In this study, the ethanol extract of Cornus officinalis fruit (EECF) showed anti-oxidant effect against PM_2.5-induced cellular oxidative stress. EECF protected cells against PM_2.5-induced DNA damage, lipid peroxidation, and protein carbonylation. PM_2.5 up-regulated intracellular and mitochondrial Ca²⁺ levels excessively, which led to mitochondrial depolarization and cellular apoptosis. However, EECF suppressed the PM_2.5-induced excessive Ca²⁺ accumulation and inhibited apoptosis. The data confirmed that EECF greatly protected human HaCaT keratinocytes from PM_2.5-induced oxidative stress.