Therapeutic Potential For Amyotrophic Lateral Sclerosis Research Articles

Lycorine protects motor neurons against TDP-43 proteinopathy-induced degeneration in cross-species models with amyotrophic lateral sclerosis

Aggregation of TAR-DNA binding protein-43 (TDP-43) is a pathological feature present in nearly 97 % cases of amyotrophic lateral sclerosis (ALS), making it an attractive target for pathogenic studies and drug screening. Here, we have performed a high-throughput screening of 1500 compounds from a natural product library and identified that lycorine, a naturally occurring alkaloid, significantly decreases the level of TDP-43A315T in a cellular model. We further demonstrate that lycorine reduces the level of TDP-43A315T both through inhibiting its synthesis and by promoting its degradation by the ubiquitin-proteasome system (UPS). Importantly, treatment with lycorine significantly attenuates TDP-43 proteinopathy and improves functional recovery in TDP-43A315T-expressing Caenorhabditis elegans and mouse models. These findings suggest that lycorine is a promising lead compound that has therapeutic potential for ALS.

Structural insights into the modulation Of SOD1 aggregation By a fungal metabolite Phialomustin-B: Therapeutic potential in ALS.

Amyotrophic lateral sclerosis (ALS) is a fatal human motor neuron disease leading to muscle atrophy and paralysis. Mutations in superoxide dismutase 1 (SOD1) are associated with familial ALS (fALS). The SOD1 mutants in ALS have a toxic-gain of function by destabilizing the functional SOD1 homodimer, consequently inducing fibril-like aggregation with a cytotoxic non-native trimer intermediate. Therefore, reducing SOD1 oligomerization via chemical modulators is an optimal therapy in ALS. Here, we report the discovery of Phialomustin-B, an unsaturated secondary metabolite from the endophytic fungus Phialophora mustea, as a modulator of SOD1 aggregation. The crystal structure of the SOD1-Phialomustin complex refined to 1.90 Å resolution demonstrated for the first time that the ligand binds to the dimer interface and the lateral region near the electrostatic loop. The aggregation analyses of SOD1WT and the disease mutant SOD1A4V revealed that Phialomustin-B reduces cytotoxic trimerization. We propose that Phialomustin-B is a potent lead molecule with therapeutic potential in fALS.

Novel small molecules therapeutics for FTD/ALS reduce TDP43 related pathology

AbstractBackgroundTDP43 aggregation and mis‐localization is a hallmark of sporadic Amyotrophic Lateral Sclerosis (ALS) and TDP‐related Frontotemporal dementia (FTD‐TDP). Hyperphosphorylated and ubiquitinated cytosolic TDP43 aggregates have been identified in post‐mortem tissue from disease patients. However, no therapies targeting TDP43 are in the clinic.MethodUsing our novel machine learning platform, we identified compounds that can disaggregate toxic oligomers of amyloid like proteins including TDP43.ResultWe show that a TDP43 peptide can spontaneously form trimers, tetramers, hexamers and octamers in vitro using high resolution ion‐mobility mass spectrometry. Two of our compounds reduce these presumed toxic oligomers and restore physiologically relevant monomers and dimers. Furthermore, our compounds dose‐dependently reduce cytoplasmic aggregates in a cellular TDP43 aggregation model. These compounds show low plasma and brain homogenate binding, high metabolic stability, are orally bioavailable and are highly blood‐brain barrier permeable. Finally, our compounds were tested in a doxycycline‐repressible iTDP43A315T mouse model of ALS. Daily oral dosing of the compounds for approximately two months did not cause any toxicity in the mice at two doses. Both drugs were detectable at high concentrations in the brains of the mice at the end of the experiment. Importantly, drug treatments showed improvement in a motor behavior test and alleviated a disinhibition phenotype in an elevated plus maze test in the diseased mice. Further analysis of target engagement and other downstream efficacy markers is ongoing.ConclusionAll together, these in vitro cell‐based and preliminary in vivo mouse model data show that the Acelot machine learning platform can identify small molecules that have therapeutic potential for ALS, FTD and other amyloid‐associated diseases.

Establishment of an Electrophysiological Platform for Modeling ALS with Regionally-Specific Human Pluripotent Stem Cell-Derived Astrocytes and Neurons

Human pluripotent stem cell-derived astrocytes (hiPSC-A) and neurons (hiPSC-N) provide a powerful tool for modeling Amyotrophic Lateral Sclerosis (ALS) pathophysiology in vitro. Multi-electrode array (MEA) recordings are a means to record electrical field potentials from large populations of neurons and analyze network activity over time. It was previously demonstrated that the presence of hiPSC-A that are differentiated using techniques to promote a spinal cord astrocyte phenotype improved maturation and electrophysiological activity of regionally specific spinal cord hiPSC-motor neurons (MN) when compared to those cultured without hiPSC-A or in the presence of rodent astrocytes. Described here is a method to co-culture spinal cord hiPSC-A with hiPSC-MN and record electrophysiological activity using MEA recordings. While the differentiation protocols described here are particular to astrocytes and neurons that are regionally specific to the spinal cord, the co-culturing platform can be applied to astrocytes and neurons differentiated with techniques specific to other fates, including cortical hiPSC-A and hiPSC-N. These protocols aim to provide an electrophysiological assay to inform about glia-neuron interactions and provide a platform for testing drugs with therapeutic potential in ALS.

Long-term interleukin-33 treatment delays disease onset and alleviates astrocytic activation in a transgenic mouse model of amyotrophic lateral sclerosis

Inflammation is a prominent feature of the neuropathology of amyotrophic lateral sclerosis (ALS). Emerging evidence suggests that inflammatory cascades contributing to the disease progression are not restricted to the central nervous system (CNS) but also occur peripherally. Indeed, alterations in T cell responses and their secreted cytokines have been detected in ALS patients and in animal models of ALS. One key cytokine responsible for the shift in T cell responses is interleukin-33 (IL-33), which stimulates innate type 2 immune cells to produce a large amount of Th2 cytokines that are possibly beneficial in the recovery processes of CNS injuries. Since the levels of IL-33 have been shown to be decreased in patients affected with ALS, we sought to determine whether a long-term recombinant IL-33 treatment of a transgenic mouse model of ALS expressing G93A-superoxide dismutase 1 (SOD1-G93A) alters the disease progression and ameliorates the ALS-like disease pathology. SOD1-G93A mice were treated with intraperitoneal injections of IL-33 and effects on disease onset and inflammatory status were determined. Spinal cord (SC) neurons, astrocytes and T-cells were exposed to IL-33 to evaluate the cell specific responses to IL-33. Treatment of SOD1-G93A mice with IL-33 delayed the disease onset in female mice, decreased the proportion of CD4+ and CD8 + T cell populations in the spleen and lymph nodes, and alleviated astrocytic activation in the ventral horn of the lumbar SC. Male SOD1-G93A mice were unresponsive to the treatment. In vitro studies showed that IL-33 is most likely not acting directly on neurons and astrocytes, but rather conveying its effects through peripheral T-cells. Our results suggest that strategies directed to the peripheral immune system may have therapeutic potential in ALS. The effect of gender dimorphisms to the treatment efficacy needs to be taken into consideration when designing new therapeutic strategies for CNS diseases.

IL-10 Controls Early Microglial Phenotypes and Disease Onset in ALS Caused by Misfolded Superoxide Dismutase 1.

While reactive microgliosis is a hallmark of advanced stages of amyotrophic lateral sclerosis (ALS), the role of microglial cells in events initiating and/or precipitating disease onset is largely unknown. Here we provide novel in vivo evidence of a distinct adaptive shift in functional microglial phenotypes in preclinical stages of superoxide dismutase 1 (SOD1)-mutant-mediated disease. Using a mouse model for live imaging of microglial activation crossed with SOD1(G93A) and SOD1(G37R) mouse models, we discovered that the preonset phase of SOD1-mediated disease is characterized by development of distinct anti-inflammatory profile and attenuated innate immune/TLR2 responses to lipopolysaccharide (LPS) challenge. This microglial phenotype was associated with a 16-fold overexpression of anti-inflammatory cytokine IL-10 in baseline conditions followed by a 4.5-fold increase following LPS challenge. While infusion of IL-10R blocking antibody, initiated at day 60, caused a significant increase in markers of microglial activation and precipitated clinical onset of disease, a targeted overexpression of IL-10 in microglial cells, delivered via viral vectors expressed under CD11b promoter, significantly delayed disease onset and increased survival of SOD1(G93A) mice. We propose that the high IL-10 levels in resident microglia in early ALS represent a homeostatic and compensatory "adaptive immune escape" mechanism acting as a nonneuronal determinant of clinical onset of disease. Significance statement: We report here for the first time that changing the immune profile of brain microglia may significantly affect clinical onset and duration of disease in ALS models. We discovered that in presymptomatic disease microglial cells overexpress anti-inflammatory cytokine IL-10. Given that IL-10 is major homeostatic cytokine and its production becomes deregulated with aging, this may suggest that the capacity of microglia to adequately produce IL-10 may be compromised in ALS. We show that blocking IL-10 increased inflammation and precipitated clinical disease onset, whereas overexpression of IL-10 in microglia using a gene therapy approach significantly delayed disease onset and increased survival of ALS mice. Based on our results, we propose that targeted overexpression of IL-10 in microglia may have therapeutic potential in ALS.

CUL2-mediated clearance of misfolded TDP-43 is paradoxically affected by VHL in oligodendrocytes in ALS.

The molecular machinery responsible for cytosolic accumulation of misfolded TDP-43 in amyotrophic lateral sclerosis (ALS) remains elusive. Here we identified a cullin-2 (CUL2) RING complex as a novel ubiquitin ligase for fragmented forms of TDP-43. The von Hippel Lindau protein (VHL), a substrate binding component of the complex, preferentially recognized misfolded TDP-43 at Glu246 in RNA-recognition motif 2. Recombinant full-length TDP-43 was structurally fragile and readily cleaved, suggesting that misfolded TDP-43 is cleared by VHL/CUL2 in a step-wise manner via fragmentation. Surprisingly, excess VHL stabilized and led to inclusion formation of TDP-43, as well as mutant SOD1, at the juxtanuclear protein quality control center. Moreover, TDP-43 knockdown elevated VHL expression in cultured cells, implying an aberrant interaction between VHL and mislocalized TDP-43 in ALS. Finally, cytoplasmic inclusions especially in oligodendrocytes in ALS spinal cords were immunoreactive to both phosphorylated TDP-43 and VHL. Thus, our results suggest that an imbalance in VHL and CUL2 may underlie oligodendrocyte dysfunction in ALS, and highlight CUL2 E3 ligase emerges as a novel therapeutic potential for ALS.

Proteasome activation is a mechanism for pyrazolone small molecules displaying therapeutic potential in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a progressive and ultimately fatal neurodegenerative disease. Pyrazolone containing small molecules have shown significant disease attenuating efficacy in cellular and murine models of ALS. Pyrazolone based affinity probes were synthesized to identify high affinity binding partners and ascertain a potential biological mode of action. Probes were confirmed to be neuroprotective in PC12-SOD1G93A cells. PC12-SOD1G93A cell lysates were used for protein pull-down, affinity purification, and subsequent proteomic analysis using LC-MS/MS. Proteomics identified the 26S proteasome regulatory subunit 4 (PSMC1), 26S proteasome regulatory subunit 6B (PSMC4), and T-complex protein 1 (TCP-1) as putative protein targets. Coincubation with appropriate competitors confirmed the authenticity of the proteomics results. Activation of the proteasome by pyrazolones was demonstrated in the absence of exogenous proteasome inhibitor and by restoration of cellular protein degradation of a fluorogenic proteasome substrate in PC12-SOD1G93A cells. Importantly, supplementary studies indicated that these molecules do not induce a heat shock response. We propose that pyrazolones represent a rare class of molecules that enhance proteasomal activation in the absence of a heat shock response and may have therapeutic potential in ALS.

Galactooligosaccharide improves the animal survival and alleviates motor neuron death in SOD1G93A mouse model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive and devastating neurodegenerative disease caused by selective degeneration and death of motor neurons. So far very limited therapeutic options have emerged to treat this fatal disease. Homocysteine (Hcy) lowering drugs have been suggested to be a palliative therapy of this disease. Folate, Vitamin B12 (VitB12) and Vitamin B6 (VitB6) are important elements involved in the Hcy metabolism and we proposed that medications which could promote the absorption of folate, VitB12 and VitB6 might have benefit for ALS. Galactooligosaccharides (GOS) is a prebiotic which could significantly improve the absorption and syntheses of B Vitamins. To investigate whether GOS could provide neuroprotective effect in ALS, we applied GOS and GOS-rich prebiotic yogurt in SOD1G93A mice and assessed their effects on the disease progression of ALS. Our results showed that GOS and prebiotics yogurt administration significantly delayed the disease onset and prolonged the lifespan in SOD1G93A mice. Also, these products increased the concentration of folate, VitB12 and reduced the level of Hcy. Moreover, we found that both GOS and prebiotics yogurt attenuated motor neurons loss, improved the atrophy and mitochondrial activity in myocyte. Furthermore, we demonstrated that GOS and GOS-rich prebiotic treatment suppressed the activation of astrocytes and microglia and regulated several inflammatory- and apoptosis-related factors. Our findings suggested that GOS might have therapeutic potential for ALS, and GOS-rich prebiotic yogurt might be considered as a nutritional therapy for this disease.

Diacetylbis(N(4)-methylthiosemicarbazonato) Copper(II) (CuII(atsm)) Protects against Peroxynitrite-induced Nitrosative Damage and Prolongs Survival in Amyotrophic Lateral Sclerosis Mouse Model

Amyotrophic lateral sclerosis (ALS) is a progressive paralyzing disease characterized by tissue oxidative damage and motor neuron degeneration. This study investigated the in vivo effect of diacetylbis(N(4)-methylthiosemicarbazonato) copper(II) (CuII(atsm)), which is an orally bioavailable, blood-brain barrier-permeable complex. In vitro the compound inhibits the action of peroxynitrite on Cu,Zn-superoxide dismutase (SOD1) and subsequent nitration of cellular proteins. Oral treatment of transgenic SOD1G93A mice with CuII(atsm) at presymptomatic and symptomatic ages was performed. The mice were examined for improvement in lifespan and motor function, as well as histological and biochemical changes to key disease markers. Systemic treatment of SOD1G93A mice significantly delayed onset of paralysis and prolonged lifespan, even when administered to symptomatic animals. Consistent with the properties of this compound, treated mice had reduced protein nitration and carbonylation, as well as increased antioxidant activity in spinal cord. Treatment also significantly preserved motor neurons and attenuated astrocyte and microglial activation in mice. Furthermore, CuII(atsm) prevented the accumulation of abnormally phosphorylated and fragmented TAR DNA-binding protein-43 (TDP-43) in spinal cord, a protein pivotal to the development of ALS. CuII(atsm) therefore represents a potential new class of neuroprotective agents targeting multiple major disease pathways of motor neurons with therapeutic potential for ALS.

The BH4 domain of Bcl-XL rescues astrocyte degeneration in amyotrophic lateral sclerosis by modulating intracellular calcium signals

Collective evidence indicates that motor neuron degeneration in amyotrophic lateral sclerosis (ALS) is non-cell-autonomous and requires the interaction with the neighboring astrocytes. Recently, we reported that a subpopulation of spinal cord astrocytes degenerates in the microenvironment of motor neurons in the hSOD1(G93A) mouse model of ALS. Mechanistic studies in vitro identified a role for the excitatory amino acid glutamate in the gliodegenerative process via the activation of its inositol 1,4,5-triphosphate (IP(3))-generating metabotropic receptor 5 (mGluR5). Since non-physiological formation of IP(3) can prompt IP(3) receptor (IP(3)R)-mediated Ca(2+) release from the intracellular stores and trigger various forms of cell death, here we investigated the intracellular Ca(2+) signaling that occurs downstream of mGluR5 in hSOD1(G93A)-expressing astrocytes. Contrary to wild-type cells, stimulation of mGluR5 causes aberrant and persistent elevations of intracellular Ca(2+) concentrations ([Ca(2+)](i)) in the absence of spontaneous oscillations. The interaction of IP(3)Rs with the anti-apoptotic protein Bcl-X(L) was previously described to prevent cell death by modulating intracellular Ca(2+) signals. In mutant SOD1-expressing astrocytes, we found that the sole BH4 domain of Bcl-X(L), fused to the protein transduction domain of the HIV-1 TAT protein (TAT-BH4), is sufficient to restore sustained Ca(2+) oscillations and cell death resistance. Furthermore, chronic treatment of hSOD1(G93A) mice with the TAT-BH4 peptide reduces focal degeneration of astrocytes, slightly delays the onset of the disease and improves both motor performance and animal lifespan. Our results point at TAT-BH4 as a novel glioprotective agent with a therapeutic potential for ALS.

Identification and Characterization of Cholest-4-en-3-one, Oxime (TRO19622), a Novel Drug Candidate for Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive death of cortical and spinal motor neurons, for which there is no effective treatment. Using a cell-based assay for compounds capable of preventing motor neuron cell death in vitro, a collection of approximately 40,000 low-molecular-weight compounds was screened to identify potential small-molecule therapeutics. We report the identification of cholest-4-en-3-one, oxime (TRO19622) as a potential drug candidate for the treatment of ALS. In vitro, TRO19622 promoted motor neuron survival in the absence of trophic support in a dose-dependent manner. In vivo, TRO19622 rescued motor neurons from axotomy-induced cell death in neonatal rats and promoted nerve regeneration following sciatic nerve crush in mice. In SOD1(G93A) transgenic mice, a model of familial ALS, TRO19622 treatment improved motor performance, delayed the onset of the clinical disease, and extended survival. TRO19622 bound directly to two components of the mitochondrial permeability transition pore: the voltage-dependent anion channel and the translocator protein 18 kDa (or peripheral benzodiazepine receptor), suggesting a potential mechanism for its neuroprotective activity. TRO19622 may have therapeutic potential for ALS and other motor neuron and neurodegenerative diseases.

Glutamate Antagonists in Amyotrophic Lateral Sclerosis

Summary Amyotrophic lateral sclerosis (ALS) is a degenerative neurological disorder that is manifested clinically by muscle weakness, wasting, spasticity and bodyweight loss, typically resulting in death from debilitating disease within 2 to 5 years of the onset of symptoms. Pathologically, there is degeneration and loss of the motor neurons in the spinal cord, brainstem and cerebral cortex, Over 90% of ALS cases occur sporadically (i.e. ‘primary’ ALS). The cause is unknown. There is, however, evidence that abnormalities of the excitatory amino acid glutamate are present in patients with ALS, and the possibility exists that the synaptic action of glutamate is abnormally potentiated causing excitotoxic degeneration of motor neurons. Hence, attenuation of glutamatergic transmission may provide the means for therapeutic intervention in ALS. In line with this hypothesis, several strategies for the treatment of ALS have been proposed, These include; (i) the modification of excitatory transmission mediated by glutamate using agents that can interact specifically with subtypes of glutamate receptors; and (ii) modulation of presynaptic glutamatergic mechanisms by, for example, decreasing glutamate release from nerve endings, enhancing removal of glutamate from the synapse, and augmenting glutamate metabolism by synaptic astrocytes. Some of the newer anticonvulsants can attenuate excitatory transmission by decreasing glutamate release and, therefore, these agents have therapeutic potential in ALS, Of these, riluzole has been tested in a sizeable number of patients and found to be effective in prolonging their survival by 2 to 3 months. These results raise the cautious optimism that this strategy may lead to further therapeutic gains in the near future. However, it is presently unclear whether abnormalities of glutamate are a contributing rather than a causative factor in the pathophysiology of ALS, and, as such, a better understanding of the extent of glutamatergic dysfunction in ALS neurodegeneration may lead to improved rational therapies for this disorder.