Amyotrophic lateral sclerosis is a non-cell autonomous disease, and motor neuron degeneration is modulated by intracellular and intercellular damages. Or at least this is what tells some scientists, indeed there is an abundance of proposal for ALS etiology and no consensus.

Another dissension point between ALS scientists is if the disease starts in the brain, or in a muscle. The former is the mainstream hypothesis. Both camps have proven again and again that their proposal was the right one.

A third mystery is that scientists almost never bothered to explore the most obvious manifestation of ALS: The muscle wasting.

With the amelioration of tools' performance, scientist's attention is turning to extra cellular vesicles.

Extra cellular vesicles

In the Central Nervous System (CNS), intercellular crosstalk happens among neurons, between neurons and glia or cells of the innate immune system, through different modalities, involving the release into the extracellular space of molecules such as neurotransmitters, neurotrophic factors, metabolites, and mutant proteins encapsulated or not in vesicles.

C9orf72, which presents aberrant hexanucleotide (GGGGCC) expansion in the non-coding region in ALS patients, regulates vesicle trafficking. Other proteins such as SOD1, TDP-43 or FUS are found in vesicles in ALS.

Where we discuss of muscles

Although much less studied than for motor neurons, abnormalities have been also described in skeletal muscle from ALS patients.

Accumulation of misfolded mutant proteins is observed in skeletal muscle.

In line with the pivotal role of defective mitochondrial respiratory chain and oxidative stress in ALS skeletal muscle, increasing levels of PGC‐1α, a transcription coactivator that promotes mitochondrial biogenesis, can improve muscle function even at late stages of the disease.

Skeletal muscle is a major site of glucose storage in the form of glycogen, which is transformed into ATP through glycolysis. The dysfunction of fast‐twitch type IIb myofibres in ALS is consistent with glucose intolerance and insulin resistance reported in ALS patients.

Myofibres from transgenic mice over expressing wild‐type TDP‐43 show impaired insulin‐mediated glucose uptake.

Does muscles kill motor neurons? In ALS, muscles are supposed to die from inactivity as motor neurons do not anymore activate them. A publication on MedRxiv proposes that it is actually the other way round: Muscles kill motor neurons. After all it is well known that many ALS patients were having intense sport activities. And an ALS-like phenotype was observed in mice when exogenous human mutant SOD1 expression was restricted to the skeletal muscle.

The authors of the pre-print, Laura Le Gall, Stephanie Duguez, Pierre Francois Pradat and colleagues, recall that pathological proteins have been identified in circulating extracellular vesicles of sporadic ALS patients. So they hypothesized that muscle vesicles may be involved in ALS pathology.

An accumulation of multivesicular bodies was observed in muscle biopsies of 27 sporadic ALS patients.

Study of muscle biopsies and biopsy-derived denervation-naïve differentiated muscle stem cells (myotubes) revealed a consistent disease signature in ALS myotubes, including intracellular accumulation of exosome-like vesicles and disruption of RNA-processing.

Compared to vesicles from healthy control myotubes, when administered to healthy motor neurons the vesicles of ALS myotubes induced shortened, less branched neurites, cell death, and disrupted localization of RNA and RNA-processing proteins. enter image description here

This article may revolutionize the understanding of ALS' etiology.

Advertisement


This book retraces the main achievements of ALS research over the last 30 years, presents the drugs under clinical trial, as well as ongoing research on future treatments likely to be able stop the disease in a few years and to provide a complete cure in a decade or two.

The insulin signaling pathway plays a crucial role in regulating the growth and metabolism of neurons. Deregulation of IGF-R signaling has been linked to a variety of neurodegenerative diseases such as Alzheimer's, Parkinson's and Huntington's disease.

However, the role of insulin signaling in C9orf72 ALS / FTD is not yet clear. A positive correlation of the incidence of ALS with early-onset type 1 diabetes has been reported, and a decrease in insulin and IGF-1 in the blood and cerebrospinal fluid of patients with ALS, although the relevance of these findings to disease progression is unclear.

Intrathecal administration of IGF-1 improved motor performance, delayed disease onset, and prolonged survival in the SOD1G93A mouse model of ALS. However, three clinical trials of IGF-1 administered subcutaneously in ALS have reported conflicting results. The contradictory result of these trials may be due to insufficient administration of drugs to the brain and spinal cord and the fact that ALS has heterogeneous genetic risk factors.

Atilano, Isaacs, Partridge, and colleagues have shown in a recent article that insulin/IGF signaling is reduced in C9orf72 fly models using adult brain RNA sequencing. They further demonstrated that activation of insulin/IGF signaling can attenuate several neurodegenerative phenotypes in flies expressing expanded G4C2 repeats or the toxic dipeptide repeat protein poly-GR.

Poly-GR levels are reduced when components of the insulin/IGF signaling pathway are genetically activated in diseased flies, suggesting a rescue mechanism. This effect on poly-GR levels was confirmed in a mammalian cell model. Modulation of insulin signaling in mammalian cells also lowers poly-GR levels. Remarkably, the systemic injection of insulin improves the survival of flies expressing G4C2 repeats. Their data suggest that modulation of insulin/IGF signaling may be an effective therapeutic approach against C9orf72 ALS/FTD.

PTEN acts as a tumor suppressor gene through the action of its protein phosphatase product. This phosphatase is involved in the regulation of the cell cycle, preventing cells from growing and dividing too quickly. It is a target of many anticancer drugs. Pten reduction has also been reported to reduce the toxicity of C9orf72 repeats expressed in a mammalian cell line, again in agreement with the results described by scientists and the potential therapeutic benefit of modulating this pathway. It is also interesting to note that the process of brain aging has been linked to decreased insulin signaling as well as impaired insulin binding, which may partly explain why aging is a problem. risk factor for the disease.

The authors found that intrathoracic insulin administration prolonged the survival of flies expressing G4C2 repeats. Although robust, the lengthening of the lifespan was relatively modest, which could be explained by the transient nature of the insulin treatment. Insulin and IGF-1 ligands have already been tested in neurodegenerative diseases.

Overall, the researchers' study suggests that modulation of the insulin / IGF signaling pathway could be an effective therapeutic intervention against hexanucleotide repeat extension associated with C9orf72 neurodegenerative diseases, with InR being a genetic modifier. It will be interesting in the future to study the need for downstream effectors of insulin signaling in the rescue of toxicity. It is important to note that in the Drosophila, there is a single insulin-like system that has the dual function of insulin / IGF signaling; thus, the mechanism of toxicity described in the researchers' model could also be linked to IGFs. Therefore, it will be important to test whether treatment with insulin or IGF can save the survival of other C9orf72 ALS / FTD vertebrate model organisms.

Advertisement


This book retraces the main achievements of ALS research over the last 30 years, presents the drugs under clinical trial, as well as ongoing research on future treatments likely to be able stop the disease in a few years and to provide a complete cure in a decade or two.

It was found in 2009 that toxicity of SOD1 is secondary to a gain of toxic function rather than a loss of enzymatic function of the SOD1 enzyme, thus reducing levels of the mutant protein was predicted to slow progression in SOD1-linked ALS. Tofersen (formerly known as BIIB067), is an antisense oligonucleotide designed for adults with a confirmed superoxide dismutase 1 (SOD1) genetic mutation, a subtype of familial ALS that makes up 2 percent of all ALS cases. 

As reducing levels of the mutant protein is predicted to slow progression in SOD1-linked ALS, this antisense oligonucleotide mediates the degradation of superoxide dismutase 1 (SOD1) messenger RNA. As there is less SOD1 mRNA, there is less production of the SOD1 protein. This is not without risks in itself, SOD1’s role is to protect against anti-oxidants which are the normal by-product of cellular respiration.

Tofersen was developed in a long time partnership between Biogen and Ionis Pharmaceuticals.  With the time doses went from 3mg up to 100mg. They conducted a phase 1-2 ascending-dose trial evaluating Tofersen in adults with ALS due to SOD1 mutations. In each dose cohort (20, 40, 60, or 100 mg), participants were randomly assigned in a 3:1 ratio to receive five doses of Tofersen or placebo, administered intrathecally for 12 weeks.  The results were presented in July 2020.

The results were encouraging, but as for any ALS trial they are anything but stellar. Lumbar puncture-related adverse events were observed in most participants. Among participants who received Tofersen, one died from pulmonary embolus on day 137, and one from respiratory failure on day 152; one participant in the placebo group died from respiratory failure on day 52.

48 participants received all five planned doses. The technical indicators where better for participants having the higher doses. Patients taking the highest dose of Tofersen saw their ALS Functional Rating Scale score decrease by an average of 1.2 points, while the placebo group saw their score decrease by an average of 5.63 points.

Toby Ferguson the principal investigator acknowledged: “What we saw is a decline in ALS function, breathing and strength that was much greater in the placebo groups than in the treated groups. That said, if I were critical, I could poke holes in any one piece of those data, but we also have the data that SOD1 is being reduced.”

ALS is a difficult field in which drugs that show early promise can turn out to offer no benefit, or pose “unjustified risks” to patients in later studies. Biogen knows this as well as anyone, having seen its last ALS effort, dexpramipexole, fail in phase 3. Since then, the company has switched its focus from drugs with specific mechanisms, like anti-inflammatories, to medicines that target genetic mutations. Biogen strategy is  to learn more about the biology of the disease from looking at genetically defined populations (SOD1, C9orf72, ATXN2, XPO1) and then apply those findings to the broader population.

Despite those mixed results and as for other ALS drugs (Nurown, Cu(II)ATSM, Masitinib, AMX0035), there is an online petition for a compassionate access. Nearly 70,000 people have signed this online petition asking Biogen to provide an experimental ALS drug to a patient requesting it under compassionate use, but Biogen disagrees.

At the heart of Biogen’s denial is the question of broader access. The fastest way to get Tofersen to as many patients as possible would be regulatory approval, wrote Biogen chief medical officer, Maha Radhakrishnan, M.D., in a March 17 letter to an ALS patient, Stockman Mauriello that she shared with WCNC. That, of course, requires the completion of clinical trials.

“Providing individual access to Tofersen at this time could jeopardize access to Tofersen for hundreds of SOD1-ALS patients by impeding our ability to complete the study that will determine whether Tofersen is efficacious and safe and to seek subsequent regulatory approvals as quickly as possible,” Radhakrishnan wrote.

It's a moral position, it would not be fair to study participants who were randomized to placebo if Biogen were to offer the drug to patients not participating in the study.

However Biogen will provide early access to Tofersen only after study participants are no longer taking placebo.

“We cannot overlook these patients when considering questions of broader access, and cannot keep them on placebo while at the same time offering Tofersen to those outside of our study,” Sandrock wrote. “Offering Tofersen outside of the study would risk failing to complete the study and risk failing to obtain access for all SOD1-ALS patients".

“These patients agreed to participate in our study acknowledging the risk that they may not receive Tofersen, and with hope that Tofersen could be shown to work and be approved for all patients,” Sandrock wrote.

Research on cell lines is often the tell-tell sign of low resources combined with great ambitions. Usually this does not give good results. A recent article on the excellent eLife magazine provide a brilliant counter example to the above thesis.

Magda Luciana Atilano and her colleagues from University College London and Max Planck Institute for Biology of Ageing show that modulating insulin signaling in mammalian cells lowers C9orf72 repeat expansion.

This might seems unlikely as insulin is involved in cell’s metabolism while C9orf72 regulate endosomal trafficking and autophagy in neuronal cells and primary neurons. Those two unrelated topics at first glance.

However C9orf72 regulates GTPase such as the Rag GTPases that simulate mTORC1 and so regulate macro-autophagy. Intuitively one can imagine that increased autophagy could remedy to C9orf72 repeats, yet how C9orf72 toxic proteins are isolated and eliminated by autophagy is not known.

The authors further demonstrate that activation of insulin/Igf signalling can mitigate multiple neurodegenerative phenotypes in flies expressing either expanded G4C2 repeats or the toxic dipeptide repeat protein poly-GR.  They found that levels of poly-GR were reduced when components of the insulin/Igf signaling pathway was genetically activated in diseased flies, suggesting a mechanism of rescue. Modulating insulin signaling in mammalian cells also lowers poly-GR levels. Remarkably, systemic injection of insulin improves the survival of flies expressing G4C2 repeats.

Overall, the scientist’s work suggest that modulation of insulin/Igf signalling could be an effective therapeutic approach against C9orf72 ALS/FTD.

However caution must be exercised: Flies are not humans. In invertebrates, the intracellular insulin-like signaling (ILS) pathway is regulated by multiple peptides, known as insulin-like peptides. In mammals, the ILS pathway is mediated through the binding of IGF-1 to the human IGF-1 receptor (IGF-1R) in the plasma membrane. So it remains to see how those findings would translate in humans.

Advertisement


This book retraces the main achievements of ALS research over the last 30 years, presents the drugs under clinical trial, as well as ongoing research on future treatments likely to be able stop the disease in a few years and to provide a complete cure in a decade or two.

A new article by Qaisar, Qayum and Muhammad made me think about links between severe forms of asthma and some ALS forms. Indeed this has already been questioned by scientists. There are only a few studies addressing skeletal muscle function in patients with moderate to severe asthma. enter image description here

Asthma is the result of chronic inflammation of the conducting zone of the airways (most especially the bronchi and bronchioles), which subsequently results in increased contractability of the surrounding smooth muscles. This among other factors leads to bouts of narrowing of the airway and the classic symptoms of wheezing. The narrowing is typically reversible with or without treatment. Occasionally the airways themselves change.

Patients with asthma have diminished activity patterns, leading to deleterious physiologic alterations and ultimately impaired functional capacity. Moreover, they may use corticosteroids during periods of disease exacerbation.

Yet patients with asthma who use systemic corticosteroids present a decrease in respiratory muscle strength. The use of high doses of glucocorticoids causes atrophy and loss of muscle strength, a condition known as steroid myopathy.

An effective pharmacological intervention in asthma remains elusive, partly because molecular mechanisms dictating muscle decline in asthma are not known.

The authors of this new article about the relation between asthma and muscle wasting, investigated the potential contribution of skeletal muscle sarcoplasmic reticulum Ca2+ ATPase (SERCA) to muscle atrophy and weakness in asthmatic patients.

SERCA resides in the sarcoplasmic reticulum within myocytes. The sarcoplasmic reticulum is a membrane-bound structure found within muscle cells that is similar to the endoplasmic reticulum in other cells. The main function of the sarcoplasmic reticulum is to store calcium ions (Ca2+). Calcium ion levels are kept relatively constant, with the concentration of calcium ions within a cell being 10,000 times smaller than the concentration of calcium ions outside the cell.[

SERCA transfers Ca2+ from the cytosol of the cell to the lumen of the sarcoplasmic reticulum. This uses energy from ATP hydrolysis during muscle relaxation.In addition to its calcium-transporting functions, SERCA also generates heat in brown adipose tissue and in skeletal muscles

Quadriceps muscle biopsies were taken from 58 to 72 years old male patients with mild and advanced asthma and the SERCA activity was analyzed in association with cellular redox environment and myonuclear domain size.

Maximal SERCA activity was reduced in skeletal muscles of mild and advanced asthmatics and was associated with reduced expression of SERCA protein and upregulation of sarcolipin, a SERCA inhibitory lipoprotein.

Sarcolipin is an important mediator of muscle based non shivering thermogenesis. It causes the sarcoplasmic reticulum Ca2+-ATPases to stop pumping Ca2+ ions but continue futilely hydrolysing ATP, thus releasing the energy as heat. Sarcolipin mediated heat production is very important for many organisms to maintain a warm body. In mammals thermogenesis by skeletal muscles is complemented by thermogenesis in the brown adipose tissue.

The authors also found downregulation of Ca2+ release protein calstabin and upregulation of Ca2+ buffer, calsequestrin in skeletal muscles of asthmatic patients. The atrophic single muscle fibers had smaller cytoplasmic domains per myonucleus possibly indicating the reduced transcriptional reserves of individual myonuclei. Plasma periostin and C-terminal Agrin Fragment 22 (CAF22) levels were significantly elevated in asthmatic patients and showed a strong correlation with hand-grip strength. These changes were accompanied by substantially elevated markers of global oxidative stress including lipid peroxidation and mitochondrial ROS production.

Agrin, a synaptically located protein, is a key player during initial formation and maintenance of neuromuscularjunctions (NMJ). During development, nerve cells approach muscle fibers and establish synaptic contacts defined as NMJ. Initially, the NMJ is small and weak, but if the contact is successful the connection is maintained and reinforced. Agrin induces and stabilizes clusters of AChRs at the NMJ, promotes synaptic maturation, and maintains the mature state of the NMJ.

C-terminal Agrin Fragment has been proposed as a novel biomarker for sarcopenia originating from the degeneration of the neuromuscular junctions. Manipulation of the agrin signaling path may therefore be a promising way to correct neuromuscular defects.

During development in humans, the growing end of motor neuron axons secrete agrin. When secreted, agrin binds to several receptors on the surface of skeletal muscle. The receptor which appears to be required for the formation of the neuromuscular junction (NMJ) is called the MuSK receptor (Muscle specific kinase). Elevation of MuSK signaling has improved motor performance and delayed denervation in ALS mice (Perez-Garcia and Burden, 2012).

Taken together, the scientists' data suggest that muscle weakness and atrophy in asthma is in part driven by SERCA dysfunction and oxidative stress. The data propose SERCA dysfunction as a therapeutic intervention to address muscle decline in asthma.

You can write me at contact at padiracinnovation.org

Advertisement


This book retraces the main achievements of ALS research over the last 30 years, presents the drugs under clinical trial, as well as ongoing research on future treatments likely to be able stop the disease in a few years and to provide a complete cure in a decade or two.

Every month a revolutionary discovery?

Every month the specialized press informs us of decisive progress in the treatment of ALS. At the beginning of February, it was a young doctor in Scotland, who turns out to have only done in-vitro experiments showing lengthening of axons of lower motor neurons when subjected to a PGC1α inhibitor, but the press service of his university had translated this as being a great discovery allowing to hope for an ALS drug. It has been known since 2008 that PPAR-γ is a transcription factor that interacts with PGC-1α and that they are involved in ALS.

We are at the end of the month, and here is an important new discovery announcement regarding a treatment for ALS. It is a molecule that has been developed for almost ten years at Northwestern University in Illinois. Several articles have already been written about this molecule. The aim was to find a molecule which is both characterized by low toxicity, capable of crossing the blood-brain barrier and of having an action on the progression of disease. But in 10 years, extensive testing of this molecule had not been carried out on ALS model mice. It would seem that this is the case today, perhaps thanks to the collaboration between two teams, those of Professor Richard B. Silverman who is oriented "chemistry" and that of Professor Hande Ozdinler rather oriented "biology".

There is both good and bad news in this new article. The bad news is that the molecule would only be effective on upper motor neurons. This is a bit surprising and there really isn't any elaborate explanation that would be provided by the authors of the article. Usually in ALS both types of neurons are affected and restoring the functioning of the upper motor neurons will be of little help if the lower motor neurons are unable to control the muscles. In addition, the article is all about restoring the health of diseased neurons, which therefore must treated as soon as symptoms appear.

The authors use very aggressive language

The authors believe that other researchers did not seek to develop therapies for upper motor neurons. This is obviously not true, the number of studies using brain samples from deceased patients are there to testify.

The authors are also not shy about saying that other researchers are enough dumb to do their in-vitro research with different sets of cell lines, sometimes unrelated to motor neuron biology. Since the nervous system involves a lot of different types of cells, and these come from only a few lines of stem cells, on the contrary it seems a very good practice.

In addition, we could counter this focus on neurons by recalling that neurons do not perform their function in isolation, cells collaborate on the same task. Moreover, reading the article one immediately wonders why the authors did not examine the astrocytes, which are only present in the central nervous system.

They further explain that there has never been a study that examines upper motor neurons at the cellular level during the disease. The number of studies on ALS using mice models of the disease is proof of the fallacy of this claim.

A therapy that is effective regardless of the type of proteopathy.

The good news, apparently unexpected, is that the molecule is effective for both SOD1 (about 2% of patients) and TDP-43 (about 95% of patients) pathologies.

In this study, only four thin slices of motor cortex from normal control subjects without neurological disease and nine slices from ALS patients were used in addition to mice studies. Again the number is very low, in other studies several hundred tissues from deceased people are studied. There are also databases that allow data to be shared between researchers.

Histological sections of deceased patients

Upper motor neurons were only counted if their soma and apical dendrite were both visualized in the same 50 µm thick section. This assumes a severe selection of neurons, are the selected neurons representative of the upper motor neuron population?

Identification of NU-9:

The chiral 1,3-Diones cyclohexane, is a cyclohexane molecule containing two ketone groups. As said above, in fact work on NU-9 started almost ten years ago. High throughput screening of over 50,000 molecules was performed using a PC12 cell-based assay expressing SOD1G93A to identify compounds that attenuate protein aggregation and cytotoxicity. This made it possible to identify three families of compounds:

  • A first compound was selected from over 50 analogues of cyclohexan-1,3-dione, because of its ability to reduce mSOD1-mediated toxicity and inhibit protein aggregation.

  • Several rounds of optimization were performed, resulting in another compound, which also had excellent pharmaceutical properties in vitro, but did not enter neurons. Further modifications of this compound then led to the generation of NU-9, which crosses the blood-brain barrier, penetrates cortical neurons and has favorable pharmacokinetic properties.

Mouse management

The mice were derived from a cross between SOD1-type ALS model mice and mice carrying a fluorescent protein. In this study, only female mice were used for the experiments. The study involves a very small number of mice, one might wonder if it would be of interest to do a study on such a small number of mice, because no smoothing can erase the inevitable indesirable events. Mice noticeably overreact to tiny variations in their environment, we recently reported that ALS model mice were getting sick at Stanford but not at MIT!

  • Ten WT-UeGFP and six hSOD1G93A-UeGFP mice were treated with placebo,
  • Five WT-UeGFP mice and seven hSOD1G93A-UeGFP mice were treated with 20 mg / kg / day dose of NU-9.
  • Eleven WT-UeGFP mice, nine hSOD1G93A-UeGFP mice and four prpTDP-43A315T-UeGFP mice were treated with a dose of 100 mg / kg / day of NU-9.

The dose of NU-9 or placebo was administered once daily by oral gavage, starting on postnatal day P60 and continuing until P120. This NU-9 compound is able to prolong the lifespan of an ALS model mouse by 13% with a dose of 20 mg / kg. A repeated 7-day toxicological study in mice demonstrated a no-observed-adverse-effect level of 100 mg / kg.

All of the mice were sacrificed after 120 days (P120), which is considered a terminal stage for this type of ALS model mouse and approximately 60% of the upper motor neurons in the motor cortex are then lost while the motor neurons are lost. remaining upper ones have a smaller soma size and vacuolated and disintegrated apical dendrites. There does not seem to have been any test on an increase in the lifespan of the treated mice.

SOD1 qualitative analyzes

The electron microscope allowed cell type analyzes of upper motor neurons and their key organelles with great precision. At P120, the upper motor neurons of the placebo-treated hSODG93A-UeGFP mice had lost most of their cytoplasmic integrity. There were very few intact organelles left in the soma. However, the presence of disintegrated mitochondria and endoplasmic reticulum was evident. The mitochondria had mostly lost the integrity of their inner membrane, aggregated, enlarged or started to disintegrate. The endoplasmic reticulum also showed broken and scattered cisterns.

NU-9 treatment (dose of 100 mg / kg per day) showed profound improvements in both the structure and integrity of the mitochondria and endoplasmic reticulum of diseased upper motor neurons. Upon treatment, the soma of these neurons showed an intact nuclear membrane, which was devoid of any invagination or protrusion, and the detection of many organelles which were appropriate in size, location and interactions between them. The mitochondrial inner membrane was intact with proper ridges that were in close contact with the endoplasmic reticulum.

SOD1 quantitative analyzes

The authors then performed quantitative analyzes to determine whether these improvements were widely seen in diseased upper motor neurons treated with NU-9. The total number of mitochondria in upper motor neurons of hSODG93A-UeGFP mice was significantly increased after 100 mg / kg / day NU-9 treatment compared to upper motor neurons treated with placebo. The total number of mitochondria after NU-9 treatment was comparable to that of healthy mice. In addition, NU-9 treatment significantly increased the number of healthy mitochondria and endoplasmic reticulum.

present in the motor cortex of hSOD1G93A-UeGFP mice treated for 60 days with 100 mg / kg / day of NU-9 became almost comparable to that of the higher motor neuron numbers present in healthy mice

What about TDP-43?

Since NU-9 appears to improve the integrity of mitochondria and endoplasmic reticulum of upper motor neurons diseased due to mSOD1 toxicity, and these are problems that are also found in pathologies such as TDP-43, the authors speculated that NU-9 might also be effective in TDP-43 pathology. It still seems like a big conceptual step, because they are two distinct disease models. Even if NU-9 has an effect on the structure of the mitochondria and endoplasmic reticulum of higher motor neurons, it should not act on poorly formed and poorly localized protein aggregates that are already present in cytosol? But as the article assumes the drug is administered as soon as symptoms appears, they do not have to deal with that problem.

To test their new hypothesis, the scientists generated a new type of mouse, this time modeling TDP-43 type ALS.

Four mice were treated with a dose of 100 mg / kg / day of NU-9, and 3 mice of the prpTDP-43A315T-UeGFP type were used as a control. The WT-UeGFP mouse cohort was used as a healthy control for both groups.

TDP-43 qualitative analyzes

The NU-9 treatment resulted in profound improvements in both mitochondria and endoplasmic reticulums of higher motor neurons. The mitochondria, especially their internal membranes, became intact and there was no sign of mitoautophagy or mitophagy. The endoplasmic reticulum retained its structure with attached ribosomes, and there was no enlargement or disintegration of the cisterns.

TDP-43 quantitative analyzes

Quantitative analysis confirmed a significant increase in the number of total mitochondria per upper motor neuron per section after 100 mg / kg / day of NU-9 treatment. This number of mitochondria after NU-9 treatment in prpTDP-43A315T-UeGFP mice became comparable to that of healthy mice. The average percentage of healthy mitochondria also increased significantly with NU-9 treatment compared to diseased upper motor neurons. NU-9 treatment also increased the average number of intact endoplasmic reticulum cisterns in upper motor neurons.

The scientists then examined whether NU-9 treatment would also promote cell integrity and the survival of the higher motor neurons with TDP-43 pathology in vivo. The health and integrity of the apical dendrites in prpTDP-43A315T-UeGFP mice showed a profound improvement with the NU-9 treatment because the percentage of upper motor neurons with vacuolated primary apical dendrites was significantly reduced. More interestingly, the mean number of higher motor neurons in the motor cortex of prpTDP-43A315T-UeGFP mice treated with NU-9 was dramatically increased compared to that of untreated prpTDP-43A315T-UeGFP mice.

The same WT-UeGFP cohort was used as a healthy control for the hSOD1G93A-UeGFP and prpTDP-43A315T-UeGFP mice, as mentioned previously. The higher motor neuron numbers with the NU-9 treatment were comparable and almost identical to those of the healthy control mice treated with the placebo, revealing the ability of NU-9 to eliminate the continued degeneration of the higher motor neurons.

Effect of NU-9 on lower motor neurons

In order to determine whether NU-9 treatment also improves the health and survival of lower motor neurons (lower motor neurons), the authors studied the lumbar cords of hSOD1G93A-UeGFP and prpTDP-43A315T-UeGFP mice. As indicated by previous studies, there was no significant loss of lower motor neurons in the spinal cord of prpTDP-43A315T-UeGFP mice, even at P120, and therefore an investigation of NU-9 treatment on motor neuron survival inferior was not possible. This seems to indicate that TDP-43 pathology only affects the higher motor neurons, yet other studies show the opposite.

However, in the case of SOD1, there was a dramatic reduction in the number of lower motor neurons in hSOD1G93A-UeGFP mice compared to healthy mice.

Macroscopic effects

The authors quantitatively assessed the changes in the number of lower motor neurons in the lumbar spinal cord of mice that were treated with either placebo or NU-9 (20 or 100 mg / kg / day), or healthy control mice. . NU-9 treatment, regardless of dose, was not sufficient to eliminate the ongoing lower motor neuron degeneration in hSOD1G93A-UeGFP mice.

NU-9 treatment improves upper motor neuron function Even though most behavioral tests fail to properly assess upper motor neuron health and connectivity, the hanging wire test would be more specific to upper motor neuron integration.

The untreated hSOD1G93A-UeGFP mice could not stay on the hanger as the disease progressed. In contrast, hSOD1G93A-UeGFP mice treated with 100 mg / kg / day of NU-9 performed better than hSOD1G93A-UeGFP mice treated with placebo, and this performance was comparable to that of healthy mice at same age. However, treatment with NU-9 did not result in a significant improvement in performance on the rotarod test at any dose.

The prpTDP-43A315T mice performed worse than the WT litter mates on rotarod and hanging wire tests. However, when treated with 100 mg / kg / day of NU-9, they performed better on the hanging wire test, comparable to healthy WT mice at P120. Unlike the hSOD1G93A mouse model, even the Rotarod test revealed a significant improvement in the TDP-43 model only after 30 days of NU-9 treatment.

Conclusion

The possibility that NU-9 can improve the integrity of both mitochondria and endoplasmic reticulum is important, because, although the underlying causes of the disease are heterogeneous, many clues converge on the proper functioning of the mitochondria and the endoplasmic reticulum. Disruption of intracellular membrane organelles, such as the Golgi apparatus, has been suggested as a possible cause of ALS and is proposed to be upstream of endoplasmic reticulum dysfunction.

This could explain why the NU-9 treatment improves the cytoarchitecture of higher motoneurons and eliminates their progressive degeneration in hSOD1G93A and TDP-43A315T mice.

However, this does not explain why lower motor neurons would not be affected by this molecule. The explanation given that these are different lineages seems very short and has not been further investigated. At no time axons are mentioned in this article, which seems odd in an article that claims to seek a cure for ALS. It seems to me that this weakens the claim that NU-9 treatment improves upper motor neuron cytoarchitecture as this architecture is not extensively tested.

Moreover, the number of mice tested is very, very low and probably statistically meaningless. It is the same for the few histological sections of deceased patients, and the selection of motor neurons. We can also notice that it has been demonstrated for more than 15 years that other types of cells are involved in ALS, starting with astrocytes, than motor neurons. This has absolutely not been studied in this article. However, when a molecule is effective on the higher motor neurons and not on the lower motor neurons, it immediately suggests that it is not on the neurons that it acts, but on the astrocytes!.

All this considerably relativizes the very strong assertions of the press service of the university which reported that "After 60 days of treatment, diseased brain cells look like healthy cells".

For any correspondence write to me at contact [at] padiracinnovation.org

Advertisement


This book retraces the main achievements of ALS research over the last 30 years, presents the drugs under clinical trial, as well as ongoing research on future treatments likely to be able stop the disease in a few years and to provide a complete cure in a decade or two.

There are unfortunately many contradictory research assumptions, that wish to explain how ALS appears and progresses. One of the most serious hypothesis ensures that it is a proteopathy. The causes of these proteopathies remain unknown but many elements indicate a cellular energy deficiency. Proteopathies have been involved in several neurodegenerative diseases.

An article by Olubankole Aladeuyi Arogundade et al. shows something new and interesting. In a recent article the scientists explain that they have found events preceding proteopathy in ALS. They have studied cells from spinal cord of 11 sporadic patients, 11 patients with mutations (inducting DPR) on chromosome 9 (C9-ALS) and 11 healthy patients.

Overall, the motor neurons in the C9-ALS presented smaller nucleoli compared to controls. Surprisingly, this narrowing occurs even in neurons without pathological TDP-43. ENTER Image Description Here

Thus, the nucleolar stress that manifests itself by the nucleolar shrinking seems to be a change upstream, before many of the molecular and structural changes.

Mizielinska et al. had already shown that C9-FTLD front cortical neurons had a lower size in neurons without other pathological markers. Similar results were obtained for Alzheimer.

Thus, at least two studies have now shown coherent results of nucleolar narrowing in the absence of pathological markers such as TDP-43 or repetitions of dipeptide for chromosome 9.

Nucleolar narrowing is sometimes associated with cancer or a cellular energy deficiency. Even if it is not mentioned in the article, one may think again about the hypothesis of the cellular energy deficit in ALS.

Advertisement


This book retraces the main achievements of ALS research over the last 30 years, presents the drugs under clinical trial, as well as ongoing research on future treatments likely to be able stop the disease in a few years and to provide a complete cure in a decade or two.

Metal homeostasis plays a singular role in neurodegenerative diseases. For more than twenty years, many in vitro studies have been devoted to identifying metals' roles in protein granules, oxidative damage, and neurotoxicity.

For example Alzheimer’s plaques comprise accumulated amyloid-beta (Aβ) proteins, loaded with metal ions including copper (Cu), iron (Fe), or zinc (Zn).

A close relationship exists between increased ROS and cellular intracellular free Zn2+. Zinc promotes liquid–liquid phase separation of tau protein, forming highly dynamic liquid droplets. Zn2+ was also observed to modulate the in vitro aggregation of the TDP-43's RRM12 domains. enter image description here

TDP-43 is an essential RNA-binding protein that assembles into protein inclusions in most cases of amyotrophic lateral sclerosis (ALS). A partially helical region in the predominantly disordered C-terminal domain harbors several mutations associated with ALS and is important for TDP-43 function and liquid–liquid phase separation.

As a systematic knowledge of the TDP-43's interaction with Zn2+ is lacking, Preethi , Bharathi and Patel from Indian Institute of Technology at Hyderabad, used in silico tools to predict potential Zn2+ binding sites in TDP-43 and estimated their relative solvent accessibilities.

They predicted Zn2+ binding sites in the TDP-43's N-terminal domain, in the linker region between RRM1 and RRM2 domain, within RRM2 domain and at the junction of the RRM2 and C-terminal domain, but found none in the 311-360 region of C-terminal domain.

The observed Zn2+ promoted TDP-43 C-terminal fragments solid-like phase separation can be relevant to the Zn2+ dyshomeostasis in ALS and FTLD-TDP.

Despite the lack of strong proofs of clinical advantage so far, the conjecture that using a therapeutic metal chelator is an effective strategy for neurodegenerative diseases remains popular. However there are ongoing clinical trial for metal chelator in neurodegenerative diseases (deferiprone for Parkinson).

But not all zinc is deleterious, communities living in proximity to abandoned uranium mines have documented exposures to metals in drinking water, soil and dust. A clinical trial (NCT03908736) currently assess the effect of dietary zinc supplementation to mitigate metal toxicity in exposed populations.

Advertisement


This book retraces the main achievements of ALS research over the last 30 years, presents the drugs under clinical trial, as well as ongoing research on future treatments likely to be able stop the disease in a few years and to provide a complete cure in a decade or two.

Therapeutic hypothermia is now the standard of care for a variety of conditions involving cell death.

The mechanisms of action of therapeutic hypothermia are varied and poorly understood. They include mechanisms that are thought to be also involved in ALS.

However, the possibility that therapeutic hypothermia has an application in ALS had not been examined.

Lee J Martin, Mark V Niedzwiecki and Margaret Wong, the authors of the article reviewed today, therefore tested in a transgenic mouse model of ALS the hypothesis that chronic intermittent mild hypothermia has therapeutic efficacy.

Mice were observed twice and then 4 to 5 times per day in the terminal stage of the disease.

SOD1 mouse models are chronically feverish. At 6 weeks of age, the internal temperature of model SOD1 mice was significantly higher (38 ° C) compared to non-transgenic control mice (37 ° C). enter image description here

At 8 weeks of age, SOD1 mice were randomized into several groups. The SOD1 mouse model had a body temperature 1 to 2 ° C lower than the SOD1 mouse model not undergoing cooling. enter image description here

The precooling body temperatures among the SOD1 mouse model groups did not differ significantly. Warming of the mouse was slow and spontaneous at room temperature. At room temperature, motor activity was tested on a racing wheel with voluntary activity.

The onset of the disease was assessed quantitatively by a deficit of activity and descriptively by paresis of the hind limbs. To assess the effectiveness of hypothermia, a group of mice were euthanized before the final stage at 12 weeks of age.

At 10 weeks of age, hypothermia improved neurological outcomes and survival in the SOD1 mouse model. Male and female SOD1 mouse models housed at room temperature exhibited a significant reduction in motor activity compared to sex-matched non-transgenic littermates. Cold acclimatized male SOD1 mice and female SOD1 mice showed significantly improved motor activity compared to the SOD1 mouse model maintained at normal temperature.

However, all groups of SOD1 mice exhibited significant motor deficits compared to non-transgenic mice of the same age. The mean lifespan of the cold acclimatized male SOD1 mouse model was significantly increased compared to the mouse model exposed to normal temperature. Cold acclimatization of the female SOD1 mouse model obtained a slightly better result on the significant increase in lifespan compared to the female SOD1 mouse model at normal temperature. 3.4.

The authors assessed hypothermic, normal-temperature SOD1 mice at 12 weeks of age for spinal cord neuropathology. Non-transgenic mice had evident spinal motor neurons with large multipolar cell bodies. In uncooled SOD1 mice, motor neurons were significantly 75% depleted and there was a secondary fulminant infiltration of small cells into the parenchyma. In cold acclimatized SOD1 mice, motor neurons were more apparent than uncooled mice.

Hypothermia rescued motor neuron counts in the lumbar spinal cord of the SOD1 mouse model (40% loss) compared to 80% loss in the uncooled SOD1 mice. Secondary small cell inflammation of the parenchyma of the spinal cord appeared to be reduced in cold acclimatized mice.

In uncooled SOD1 mice, the mitochondria were severely swollen, dysmorphic, and disrupted in motor neurons and in the neuropil. In hypothermic SOD1 mice, the mitochondria in the cell bodies of motor neurons were protected from swelling. This protection of motor neurons in SOD1 mice has been linked by an attenuation of inflammatory changes in the spinal cord.

In non-transgenic mice, diaphragm motor plate innervation was close to 100%, while in uncooled SOD1 mice, endplate innervation was significantly reduced to only about 40% at 12 weeks old.

In contrast, in cold acclimatized SOD1 mice, innervation of the neuromuscular junction was restored to about 65% of normal, but was still significantly reduced compared to diaphragm innervation from non-transgenic mice.

The cooled SOD1 mice exhibited a significant upregulation of the modified proteins HSP70, UCP3 and SUMO1 compared to the uncooled transgenic mice.

Cold acclimatization was more effective in females than in males at prolonging lifespan. The innervation of the diaphragm of the motor plates was improved by hypothermia.

Many circulating cytokines induce fever. This profile of inflammatory cytokines is consistent with their finding that ALS mice are febrile during the course of the disease. The main circulating proinflammatory pyrogenic cytokines in ALS mice are TNFα and IL6. TNFα and IL6 can cause muscle atrophy in various clinical settings. Skeletal muscle wasting is an important feature of human ALS and some mouse models of ALS.

The authors confirmed, which has been repeatedly reported, that during the course of the disease in the muscles of SOD1 mice, nitric oxide production is increased and protein nitration is elevated, y including key proteins at the neuromuscular junction.

Nitric oxide is an essential regulator of cell apoptosis. It can have an antiapoptotic effect, or, conversely, an apoptotic effect. This rocker is intimately linked to the presence or absence of cellular reducers such as glutathione.

In ALS, the thermoregulatory function could be aberrant. Hypothermia could act on the CNS, peripheral nervous system, skeletal muscle and body fat levels.

The clinical-translational application and efficacy testing of this concept in human ALS would be non-invasive and applicable, perhaps in rehabilitation spas in private and hospital settings. Cold water immersion or cryotherapy is common among athletes. Cold acclimatization protocols should be determined and empirically refined, and biomarkers of therapeutic efficacy should be identified for human ALS. Biomarkers could be based on skeletal muscle biopsy and assay for HSP70, protein sumoylation, and mPTP activation thresholds.

Advertisement


This book retraces the main achievements of ALS research over the last 30 years, presents the drugs under clinical trial, as well as ongoing research on future treatments likely to be able stop the disease in a few years and to provide a complete cure in a decade or two.

A new study published Jan. 21 in Nature by Katrin Andreasson and Paras Minhas, suggests that cognitive aging is not irrevocable, but can be reversed by reprogramming glucose metabolism in myeloid cells.

Biologists have long hypothesized that reducing inflammation may slow down the aging process and delay the onset of age-associated diseases, such as heart disease, Alzheimer's disease, cancer and the frailty that concerns each of us during our aging. Yet, the question of exactly what causes these inflammatory reactions of the immune system had not found a definitive answer.

Diseases concerned

A long-standing observation in epidemiological studies of aging populations has been that NSAIDs, which inhibit the production of cyclooxygenase-1 (COX-1) and COX-2 and prostaglandin (PG), prevent the development of the disease. Alzheimer's.

Model ALS mice and patients with sporadic ALS have increased levels of prostaglandin E2 (PGE2). In addition, levels of microsomal proteins PGE synthase-1 and cyclooxygenase-2, which catalyze PGE2 biosynthesis, are dramatically increased in the spinal cord mice model of ALS .

Preclinical studies suggest that prostaglandin E2 (PGE2) is an essential inflammatory mediator of brain damage via the activation of four G protein coupled receptors, namely EP1-EP4.

Transient inhibition of the EP2 receptor by antagonists permeable to the blood-brain barrier shows marked anti-inflammatory and neuroprotective effects in several rodent models of epilepsy, without, however, having a noticeable effect on seizures per se.

In the brain, microglia lose the ability to remove misfolded proteins associated with neurodegeneration.

Prostaglandin and myeloid cells

Prostaglandins are one of the main mediators of inflammation which play an important role in improving neuroinflammatory and neurodegenerative processes. Myeloid cells are the main source of PGE2, a hormone belonging to the prostaglandin family. Prostaglandins are a group of physiologically active lipid compounds derived from arachidonic acid.

Arachidonic acid is one of the most abundant fatty acids in the brain (10% of its fatty acid content). Among other things, it helps protect the brain from oxidative stress by activating the gamma receptor activated by peroxisome proliferators.

One type of receiver for PGE2 is EP2. This receptor is found on immune cells and is particularly abundant on myeloid cells. It initiates inflammatory activity inside cells after receiving PGE2.

Myeloid and macrophages

Myeloid cells are distinguished from lymphocytes. Monocytes, a type of myeloid cell, and their macrophages and dendritic cell descendants perform three main functions in the immune system. These are phagocytosis, antigen presentation and cytokine production.

Macrophages engulf and digest cell debris, foreign substances, microbes, cancer cells, and anything that does not have the type of proteins specific to healthy cells in the body on its surface. The first author of the study, Paras Minhas, initially isolated monocytes from blood donated by healthy people under the age of 35 or over 65. Scientists also looked at macrophages from young mice compared to old mice.

During aging, functional changes are due to macrophages. Microglia residing in the brains of aged mice increase their soma volume but reduce the length of their processes, limiting their ability to interact and support neuron survival.

Macrophages can undergo "training" after re-exposure to a stimulus. Recent studies have described that the induced immunity in young mice leads to an increase in myeloid lineage cells and can occur in myeloid precursors in the bone marrow. As we age, a similar shift towards a myeloid cell line occurs, and the aging microenvironment may also have a ripple effect.

Effects of a significant increase in PGE2 levels

The authors observed that older macrophages from mice and humans not only produced significantly more PGE2 than in younger subjects, but also had a much higher number of EP2 on their surface. Andreasson and his colleagues also confirmed significant increases significant levels of PGE2 in the blood and brain of old mice. The researchers found that in aging macrophages and microglia, PGE2 signaling through its EP2 receptor promotes the sequestration of glucose into glycogen, reducing glucose flow and mitochondrial respiration.

The dramatically increased PGE2-EP2 binding in elderly myeloid cells alters energy production in these myeloid cells by inducing them to store glucose, rather than fueling energy production in the cell. Cells store glucose by converting this energy source into long chains of glucose called glycogen (the animal equivalent of starch).

This build-up creates a state of chronic exhaustion (stress) in the cells, which leads them to express inflammatory signals. Not only have aging macrophage cells found it difficult to burn glucose, they also don't use other sources of energy for respiration. Young macrophage cells were better able to utilize lactate and pyruvate.

An apparent rejuvenation?

The authors deleted EP2 in transgenic mice, which halved the amounts of receptors. Macrophages from 20 month old EP2-deficient mice maintained normal cellular respiration and glycolysis. In control animals of the same age, macrophage function deteriorated with age. Cells from control animals secreted pro-inflammatory factors, were poorly phagocytosed, and had fewer and poorly formed mitochondria. Macrophages deficient in EP2, on the other hand, had none of these problems, behaving like those of young mice.

Scientists gave mice one or both of two experimental drugs known to interfere with PGE2-EP2 binding in animals for a month. They also incubated cultured mouse and human macrophages with these substances. In doing so, the old myeloid cells metabolized glucose just like the young myeloid cells, reversing the inflammatory character of the old cells.

More strikingly, the drugs reversed the cognitive decline associated with the age of mice. Indeed, the old mice who received them performed recall and spatial navigation tests as well as the young adult mice. Blocking peripheral myeloid EP2 signaling is therefore sufficient to restore cognition in aged mice.

The blood-brain barrier EP2 inhibitor C52 improved glycogen synthesis, improved glycolytic response and TCA cycling of myeloid cells (microglia and peripheral macrophages), and improved cognitive performance.

Surprisingly, mice reaped these cognitive benefits even when treated with an EP2 inhibitor (PF-04418948) that does not cross the blood-brain barrier.

Towards drugs?

Since activation of the EP2 receptor has been identified as a common culprit in several neurological conditions associated with inflammation, such as stroke and neurodegenerative disease, selective small molecule antagonists targeting EP2 are being developed. to suppress PGE2-mediated neuroinflammation.

Several companies manufacture selective EP2 antagonists, but none are approved for human use. Pfizer's PF-04418948 was tested for safety in a Phase 1 study in 2010, but the company has discontinued clinical development.

However, targeting EP2 could be complicated. The receptor is known to regulate blood flow and blood pressure, and has been shown to protect the brain during stroke.

Please, to help us continue to provide valuable information: