ALS researchers from around the world continue to build upon existing work and make new discoveries in the hopes of realizing a future without ALS. In the March 2023 Research Update, you’ll learn about the progress researchers have made in identifying promising new treatment targets, exploring the possible therapeutic effect of a probiotic in ALS, uncovering mechanisms that could contribute to disease progression, investigating a candidate biomarker to facilitate earlier diagnosis, understanding the role specific proteins could play in ALS, and more.

We recently developed a research glossary that contains a list of scientific and medical terms and definitions relevant to ALS. The glossary was created to support knowledge-sharing by helping to provide clarity around terminology that may be unfamiliar to our readers. Click here to download a copy.  

Researchers identify two promising new therapeutic targets for treating ALS

A team of researchers have identified two promising avenues for developing new ALS treatments that could be broadly effective for all forms of the disease.

One of the greatest advancements in science over the past 20 years is the development of induced pluripotent stem cells (iPSCs). These cells make it possible to create essentially any cell type in the body using any other as a starting point.

In a pair of recent studies, researchers collected skin and/or blood samples from patients with familial (i.e., have a known disease-associated genetic mutation) or sporadic ALS, and reprogrammed the skin and blood cells into motor neurons. This allowed researchers to screen libraries of FDA-approved drugs and drug-like molecules to find ones that could be effective against multiple forms of the disease.

In the first study, published in Cell Stem Cell, researchers tested 1,926 different compounds looking for ones that could rescue ALS motor neurons from disease-associated features, such as the TDP-43 dysfunction observed in more than 97 per cent of all ALS cases. From these screens, the team identified 11 compounds that appeared to have a positive effect in most cell lines. Many of these compounds were linked to a specific cellular pathway which led researchers to question whether targeting a related gene, called SYF2, could improve motor neuron survival. Suppression of SYF2 was tested in cell lines and an ALS mouse model and revealed that lowering SYF2 levels reduced TDP-43 dysfunction, improved motor neuron health, and extended survival.

In the second study, published in Cell, researchers specifically targeted a protein called PIKFYVE and found that inhibiting the activity of this protein reduced pathology and extended survival in cell lines, fruit fly and mouse models of ALS. Blocking PIKFYVE activity appeared to activate an unconventional protein clearance mechanism within the cell that got rid of toxic, aggregation-prone proteins by moving them to the outside of the cell. AI Therapeutics first began testing a PIKFYVE inhibitor in ALS, with the drug AIT-101 which is currently in a Phase 2 clinical trial.  A Phase 1 clinical trial is also underway in the Netherlands to test the safety and tolerability of VRG50635, a PIKFYVE inhibitor being developed by Verge Genomics. Finally, AcuraStem is also in the early stages of developing an experimental treatment aimed at reducing PIKFYVE activity in ALS.

Identifying treatments that can be effective across all forms of ALS can be difficult given the heterogeneity of the disease, but these findings represent a promising step in the right direction. The researchers note, however, that additional studies are required to determine the safety and potential effectiveness of targeting these proteins in a human setting – some of which are already underway.

Scientists identify a probiotic strain that may have a protective effect in ALS

A specific probiotic strain, called HA-114, was shown to reduce neurodegeneration and paralysis in an animal model used to study ALS.

In recent years, scientists have learned that changes in gut bacteria can influence overall health. In fact, evidence suggests that the gut microbiome can play a role in susceptibility to diseases, including those of the brain. Probiotics are friendly, live bacteria that are good for the digestive system and are being explored for their potential effect in a range of diseases including obesity, colorectal cancer, cardiovascular disease, and ALS.

In this study, supported in part by the ALS Canada Research Program, a team of researchers used small worms, called C. elegans, to test the effects of 13 different bacterial strains and three strain combinations. These worms are only a millimetre long, but since they have short lifespans and share 60 per cent of their genetic makeup with humans, they are ideal animals to use in research.

The results showed that one strain, HA-114, stood out from the pack. When added to the diet of the C. elegans worms, researchers found that treatment with HA-114 slowed motor neuron degeneration and functional decline. Further analyses revealed that the protective effect of HA-114 was likely due to its ability to restore impaired energy metabolism within mitochondria, the powerhouse of the cell.

Additional studies underway to validate these findings in a more complex system (an ALS mouse model) are supported by a 2020 ALS Canada-Brain Canada Discovery Grant. A Canada-wide clinical trial is also expected to begin in the days ahead to test HA-114 in a clinical setting. The trial will first launch at the CHUM in Montreal and hopes to enroll 100 participants living with ALS.

Important note: This work relates to a non-marketed probiotic called HA-114 and any consideration of taking probiotic supplements is recommended to first be discussed with members of an ALS clinical team.

New insight into a possible mechanism underlying disease progression in ALS

Researchers show that TDP-43 dysfunction has the potential to spread from cell-to-cell within the nervous system; a process that could contribute to the progression of ALS.

A protein is said to have prion-like behaviour when it fulfills two major criteria: first, it must be able to cause other normally-folded proteins to change their shape and adopt a toxic shape. Second, it must trigger a chain reaction, moving from cell-to-cell creating a domino effect of toxic protein misfolding and aggregation that spreads throughout the nervous system. Well-known prion diseases include scrapie in sheep, mad cow disease in cattle, and Creutzfeldt-Jakob disease in humans.

Some researchers believe that a prion-like mechanism may contribute to disease progression in ALS. Abnormalities in a protein called TDP-43 are present in approximately 97 per cent of all ALS cases. Normally, TDP-43 is found in the nucleus of a cell (a central compartment where our DNA is located); however, in people living with ALS it is often found in the cytoplasm (the area outside of the nucleus) where it tends to form clumps, or aggregate, and is no longer able to function properly. It’s been hypothesized that TDP-43 contributes to disease progression through the spread of its toxic aggregated form in a prion-like fashion.

To test this hypothesis, researchers created a three-dimensional (3D) cell culture model in the laboratory, called a cerebral organoid, which is representative of human brain tissue. Samples containing aggregated TDP-43, which were prepared from spinal cord tissue donated from five ALS patients, were injected into these cerebral organoids to determine whether cell-to-cell transmission of TDP-43 aggregates could be observed.

Researchers found there was a spreading of TDP-43 aggregates within the cerebral organoid, and that this affected other cell types within the brain thought to play a role in ALS, such as astrocytes. By comparison, when samples prepared from the spinal cords of control (e.g., non-diseased) individuals were injected into the organoids, there was no spreading of aggregated TDP-43.

Results from this study provide some new evidence that TDP-43 aggregation has the ability to spread throughout the nervous system in a prion-like fashion, and that this could contribute to disease progression in ALS. Additional studies are required to determine what factors cause the spreading to occur, however, the 3D model researchers created here could be used to test future treatment strategies aimed at blocking the cell-to-cell transmission of TDP-43 aggregation.

A promising new biomarker candidate shows potential to facilitate earlier diagnosis of ALS

Researchers have identified a substance that accumulates in the cerebral spinal fluid (CSF) of people living with ALS during early stages of the disease.

There is an unmet need for biomarkers in neurogenerative diseases like ALS. Biomarkers are biological measures that can be used to understand the real-time processes happening in the body. For example, the level of cholesterol in the blood is a biomarker for the risk of heart disease and is used as an indicator of a person’s response to cholesterol-lowering drugs. Validated biomarkers are urgently needed to help clinicians diagnose ALS, track progression of the disease, and measure response to therapies.

Dysfunction in a protein called TDP-43 is observed in over 97 per cent of ALS cases. One of TDP-43’s major functions within cells is the processing of molecules called messenger RNA (mRNA), which serve as the genetic blueprint for making proteins. When TDP-43 moves from the nucleus (where it is normally found) to the cytoplasm, a hallmark feature of ALS, it is no longer able to perform its normal function effectively. Researchers have found that when TDP-43 levels in the nucleus are reduced, the mRNA molecules for several different genes are altered which leads to the creation of small proteins, called cryptic peptides, that would not normally be present.

In this study, researchers hypothesized that these cryptic peptides could serve as a biomarker for TDP-43 dysfunction in ALS. The team first developed an antibody in the lab that could selectively target a specific cryptic peptide, called HDGFL2, found in the CSF of individuals with C9ORF72-linked ALS. They then tested the ability for this antibody to detect HDGFL2 in CSF samples from pre-symptomatic C9ORF72 mutation carriers. Remarkably, the team found that the cryptic peptide was present in pre-symptomatic individuals as well, suggesting that TDP-43 dysfunction occurs early in disease, even pre-symptomatically, and that in combination with other emerging biomarkers, detection of HDGFL2 could help to signal the underlying onset of ALS before symptom begin.

The results from this study point to a promising new biomarker that could support earlier and accurate diagnosis of ALS, allowing for prompt therapeutic intervention. This type of biomarker could also help researchers monitor the effectiveness of future treatments aimed at restoring TDP-43 function and even improve clinical trial and drug design. Researchers note, however, that further studies are required to validate these finding in individuals with sporadic ALS.

Important note: This work is in preprint, meaning it has not yet been peer reviewed by a journal.

Understanding the role of CHCHD10 and CHCHD2 in ALS disease processes

Using zebrafish as a model, researchers uncover the biological pathways impaired by mutations in CHCHD10 that could contribute to neurodegeneration in ALS.

In 2014, mutations in the CHCHD10 gene were newly identified as a genetic cause of ALS. Later, in 2018, researchers made a discovery linking the role of CHCHD10 in ALS to another protein, CHCHD2. While it’s clear that these two genes are connected to one another, and to ALS, the exact nature of their interrelationship – and the way they contribute to neurodegeneration – have yet to be fully understood. Previous studies suggest that mutations in CHCHD10 and CHCHD2 may lead to impaired functioning of mitochondria, structures within cells that provide the energy the cell needs to survive.

To further investigate the biological roles of CHCHD10 and CHCHD2 in ALS, researchers studied thousands of tiny striped fish, only two millimetres long. Zebrafish are well-suited to genetics research as more than 70% of human genes are also found in zebrafish, along with many critical biological pathways that contribute to development.

In this study, which was supported in part by a 2020 ALS Canada-Brain Canada Discovery Grant, researchers found that the loss of either or both proteins led to several ALS-like symptoms in zebrafish, including alterations at the neuromuscular junction (the place where motor neurons connect to muscle fibers), impaired motor function, and reduced survival. The observed effects were most severe when both proteins were lost, suggesting that while CHCHD10 can compensate for loss of CHCHD2 to some degree (and vice versa), the proteins are not fully interchangeable meaning each have independent functions of their own.

Further investigations revealed that loss of either protein impacted the assembly and stability of a key complex within mitochondria, however, when both proteins we lost, a compensatory mechanism within the cell kicked in that restored the complex assembly. This suggested to researchers that additional cellular pathways must also play a role in the creating the ALS-like symptoms in zebrafish, as these were most severe when both proteins were lost, despite no alteration of the complex assembly.

Ultimately, the results from this study help to detangle the functions of both proteins, as well as the role they play in ALS, providing a foundational understanding that could lead the way to identify new treatment targets for the disease. These findings highlight the importance of understanding the normal role of proteins within cells to better understand the biology of ALS.

Bringing you the latest news on advancements in ALS research, the ALS Canada research team regularly summarizes the most significant discoveries throughout the year.

Note: We have included links to the publications because we know you may be interested in the original source papers. While abstracts are always available, many journals are subscription based, and in some cases, full papers may only be accessed at a cost.

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