Astrocytes conversion into interneurons

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In the case of neurodegenerative diseases, it is certainly more useful to try to develop new neuronal cells than to "cure" cells that we are told are dying or even dead for months. This is the purpose of regenerative medicine.

One of the difficulties is that neurons are cells that do not reproduce, we live with the stock that we had at the end of our puberty. These cells come from stem cells.

In our brain and the rest of the central nervous system, half of the cells are not neurons, but more classic cells that nourish and maintain neurons.

These cells reproduce by fission like most cells. In particular, astrocytes, although tiny, have many points in common with neurons. It is therefore natural to want to transform astrocytes into neuronal stem cells. enter image description here Curiously, scientists are rather looking to directly convert astrocytes into neurons, despite the enormous morphological difference between these two types of cells.

A few years ago, following the discovery of Yamanaka factors, it was believed that this goal could be achieved quickly. However, the results obtained have been contested, in particular, because of methodological flaws. Despite the promising results of previous studies, the lack of robust lineage tracing methods has led to uncertainty as to whether the induced neurons originated from glial cells or whether native neurons were mistakenly labeled.

A new publication describes recent advances in converting glial cells into induced neurons in the central nervous system, particularly in regions where stem cell activity is limited. The previous “lineage reprogramming” approach used transcription factors to change the identity of terminally differentiated cells, such as glial cells, to other cell types.

The current study focuses on the transcription factor Ascl1, known for its role in neuronal fate decisions and its potential to reprogram various cell types into neurons. While Ascl1 can efficiently convert glial cells into induced neurons in vitro, its efficacy in vivo varies widely, often leading to limited neurogenic effects or, in some cases, inducing glial proliferation rather than neuronal conversion.

This inconsistency suggests that regulatory challenges affect Ascl1’s performance as a reprogramming factor, particularly due to context-specific modifications such as phosphorylation, which modulate its activity. Previous research has found that a mutant variant of Ascl1, known as Ascl1SA6, engineered to resist phosphorylation, enhances neurogenic activity, prompting this study to determine whether Ascl1SA6 could enhance glia-to-neuron reprogramming in vivo.

The researchers tested Ascl1SA6 in the early postnatal mouse cerebral cortex, which showed superior neuronal induction capacity compared to wild-type Ascl1. Furthermore, the combination of Ascl1SA6 with the survival factor Bcl2 further enhanced the efficiency of iN conversion. The study’s lineage tracing confirmed that the newly formed induced neurons were primarily from astrocytes. Interestingly, many of these induced neurons exhibited characteristics of fast-spiking parvalbumin-positive (PV+) interneurons.

In summary, the study demonstrates that Ascl1SA6, particularly in combination with Bcl2, could improve the efficiency and fidelity of glia-to-neuron reprogramming in vivo, with potential implications for therapies targeting neuronal loss and brain circuit restoration.

It should be kept in mind, however, that these cell type conversions a priori promote the appearance of cancers, that the new neurons are hardly useful, that the method used is gene therapy and therefore has very low efficacy and elevates cancer risks, that is is a report on experiences done in mice and they usually do not translate in humans and that it is not a question of conversion to neuronal stem cells which would be free of many of these problems.

Nevertheless, it's a step in the right direction.

Biotechs are weird, NP001 is back.

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Readers of this blog probably know the story of the drug NP001. One phase I and two phase II trials were conducted by Neuraltus in ALS patients (NCT01281631 and NCT02794857). These were both 6-month studies, the usual clinical trial duration. Phase 2A was completed in 2012, and Phase 2B in 2017. Both failed. Now some people want to revive this drug, through a new biotech named Neuvivo.

What the authors of a new publication did was to try to find a subset of patients that showed some longer survival with NP001 in those old trials.

This is a widely used technique by unsuccessful companies, but it is statistically meaningless.

The authors found a subset of patients who had inflammation and a longer survival. Yet this analysis would be comically wrong if we were not speaking of dying people. enter image description here For example, the authors claim that survival of ALS patients with inflammation is 16 months longer than in the placebo arm. At 72 months there were only 3 people in the inflammation subset and two people in the placebo arm. Nobody can say anything about these numbers. If we use the same criteria, it shows that NP001 worsened the condition in all pALS with respect to the placebo branch, as starting from 72 months there were fewer survivors in the NP001 arm than in the placebo.

In addition, one could read the subset of pALS with inflammation as them having a comorbidity. If you prescribe an inflammation therapy to people having inflammation, they will improve a bit, which would be reflected in longer survival to ALS.

The proposed mechanism of action is vague (as usual, at least here there is a proposal): They said that NP001 is converted by macrophages to taurine chloramine, a regulator of inflammation. As the authors assert that persistent immune activation in patients with ALS is the cause of loss of muscle, an anti-inflammatory drug would help.

There are few publications about taurine chloramine, but, when taurine is in the presence of highly toxic hypochlorous acid, it generates the less toxic taurine chloramine. It's the result of the body's mitigation to a poison.

Any Relation Between Sleep Apnea and Amyotrophic Lateral Sclerosis?

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The current paper is about an untested hypothesis. Scientists have proposed thousands of assumptions about the etiology of ALS, and the same is true for many other diseases. Single-authored papers are often dismissed, as are papers that make wild hypotheses without trying to test them. I mention this paper because the single author is a remarkable scientist in the field, not one of the countless hacks who write a paper on ALS today with very little knowledge of the disease and will never write about it again.

Another reason might be because it may have some relation with a drug developed by Richard B. Silverman, and P. Hande Ozdinler at Northwestern University. AKAVA Therapeutics, started last year by Silverman, is carrying out studies of the drug AKV9 (ex NU-9).

This article discusses the possible relationship between sleep, the glymphatic system, and neurodegenerative diseases. It suggests that sleep issues might exacerbate ALS disease progression by impairing the brain's waste-clearance mechanisms and compromising neuronal health, but it does not describe any experiment. It also tells that neuron health is diminished when the organism is sleep-deprived, in particular neurons experience dendritic spine loss.

Sleep is crucial for brain health because the clearance of metabolic waste and the remodeling of synapses happens during sleep. Many ALS and Parkinson's patients experience sleep disturbances. Disrupted sleep patterns, especially those associated with conditions like sleep apnea, a condition where upper airways collapse during sleep, can lead to impaired glymphatic function. The author equals poor glymphatic function with accumulation of agglomerates of misfolded proteins in cellular cytosol. I am not sure there is any evidence of this relation.

The glymphatic system is responsible for clearing waste products from the brain, primarily during sleep. It is facilitated by cerebrospinal fluid (CSF) circulation. During sleep, the glymphatic system operates optimally, removing waste products from the brain. Impaired glymphatic clearance, especially when sleep is disrupted, might be a significant contributor to protein buildup and possibly subsequent neurodegeneration.

Evidence from studies shows a faster CSF clearance during sleep, suggesting that adequate sleep is crucial for maintaining brain health. Dysfunction of this system can contribute to the accumulation of toxic proteins, such as amyloid-beta and tau, associated with neurodegenerative diseases. Yet this clearance happens in the periphery of the brain, so it's hard to see how a good clearance would improve the health of those neurons that are deep inside the brain.

Early signs of neurodegeneration in ALS include the loss of dendritic spines. A dendritic spine is a small membrane protrusion from a neuron's dendrite that typically receives input from a single axon at the synapse. Motor neurons in the spinal cord, for example, can have a dense arrangement of dendritic spines in certain regions, as these neurons need to process a large number of excitatory and inhibitory signals to regulate muscle activity effectively. Sleep plays a vital role in spine pruning and remodeling, ensuring healthy neuronal connectivity.

Synaptic connections, especially dendritic spines, are dynamic and undergo constant remodeling, particularly during sleep. This process is crucial for maintaining neuronal network stability and function. Sleep deprivation or sleep apnea disrupts spine pruning, leading to excessive or unhealthy connections, which stresses neurons and hampers brain connectivity. Experiments show that even brief sleep deprivation reduces spine elimination, resulting in abnormal spine density and neuronal hyperactivity in brain areas like the hippocampus. This disruption may have a profound impact on memory and cognitive function.

Therefore investigating the relationship between sleep, glymphatic function, and biomarkers in CSF could lead to earlier diagnosis and more effective disease monitoring.

Yet, sleep is not routinely assessed in clinical diagnostics for neurodegeneration. Integrating sleep studies into patient assessments could enhance diagnostic precision and enable targeted interventions. Moreover, understanding the molecular changes in CSF associated with sleep problems could provide valuable biomarkers for monitoring disease progression. There’s potential for developing therapies focused on improving sleep quality, as addressing hypoxia and improving glymphatic function might reduce protein buildup and protect against neuronal damage.

The importance of studying different muscle groups in ALS

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A couple of days ago, I complained about the lack of publications on ALS metabolism in skeletal muscles, which represent only a tiny fraction of the huge number of ALS (mostly useless) publications.

Here is one article describing the evolution of the masseter muscle, one of the muscles of mastication, during the disease course in a SOD1 mice model. Why study the masseter muscle in ALS? Because it is one of the few skeletal muscles that is not affected by the disease. enter image description here The authors observed that, despite a decrease in limb motor functions, the feeding function of these mice was preserved until the late stages of the disease. Remarkably, the masseter muscle showed no reduction in muscle volume, wet weight, or muscle fiber cross-sectional area. Furthermore, no changes were observed in muscle fiber types, indicating a possible resistance of the masseter muscle to ALS-induced impairment. A potential reason for the lack of atrophy in the masseter muscle could be its higher number of muscle satellite cells compared to that of the gastrocnemius muscle. This abundance may promote the maintenance of muscle fiber nuclei, thereby contributing to muscle tissue regeneration.

What they are saying in the background is: * Something is stressing the skeletal muscles in ALS, which looks quite a reasonable assumption to me. * Maybe it would be possible to design an ALS therapy targeting muscle satellite cells. This looks less likely to me.

While the authors promote the idea that the disease may, at least partly, start in muscles, I can't help myself thinking that maybe the reason it is preserved is simply that this muscle (as for eye movements) is activated by the trigeminal nerve which is usually preserved in ALS.

It seems to me that in spinal ALS, the longer motoneurones fail early (hands, feet) and the shorter ones survive longer. Indeed in bulbar ALS, the situation is reversed, but ALS mice models attempt only to model spinal ALS. So in my opinion, the authors should have considered that the lack of wasting of mice's masseter muscle may stem from a still functioning trigeminal nerve.

Trial designs for motor neuron disease in the 21st century

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We previously reported that Memantine was found ineffective in an ALS clinical trial for the fifth time. Several articles about persistent failure in ALS clinical trials appeared in the last issue of The Lancet Journal.

Trial designs for motor neuron disease in the 21st century

A new era of drug discovery for amyotrophic lateral sclerosis

Scientists attribute Memantine's (and the many other drugs that were tried) lack of efficacy to the "complexity of the pathophysiological mechanisms."

In simpler words, they have no idea why it failed, yet it was tested for the fifth time in ALS, so in a rational world, they should, on the contrary, have expected it to fail. In addition, no pre-clinical studies have shown any special value of Memantine in ALS.

And it's not only about Memantine, hundreds of drugs with dozens of different mechanisms of action have been trialed in ALS, as well as in other neurodegenerative diseases. For example, in the same journal issue, there are the results of the ROCK-ALS phase II clinical trial which has a purported mechanism of action entirely different from the usual suspects (glutamate excitotoxicity, impaired proteostasis, autophagy, and neuroinflammation).

Clearly, scientists know nearly nothing about these diseases, otherwise, they would concentrate their efforts on specific drugs.

It is time to reconsider century-old and unquestioned assumptions about these diseases. What makes ALS patients die? Skeletal muscle wasting which leads to respiratory failure. Efforts should concentrate in this direction. We also know that ALS is not always a death sentence, for example Stephen Hawking lived 76 years and 55 years with the disease. We know that a BMI in the 27 range helps for survivability, yet publications on ALS metabolism in skeletal muscles represent only a tiny fraction of the huge amount of ALS publications. In 2023 there were only 23 publications on this topic, versus 2507 publications on ALS.

Why this situation? Laboratories and CRO are not organized to study whole-body mechanisms in large mammals. It would cost a lot, universities and biotech prefer to work on small rodents or even worse on immortalized cell lines.

There is also the question of the time span, most studies are conducted within 6 months, or even two months, because students are used as a cheap workforce. You can't detect any statistically meaningful clinical change in neurodegenerative diseases in two months.

Studies must last at least one year and use large mammals, if possible mammals which have a corticospinal tract similar to ours, with direct connection between upper and lower motor neurons for fine control of skeletal muscles such as in hands..

A recent publication poses a question that has become increasingly pressing in the face of numerous unsuccessful trials for the treatment of amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease. "Why is the treatment and management of amyotrophic lateral sclerosis so difficult?"

The article suggests that when a phase II clinical trial succeeds while its phase III trial fails, it's because they have a different profile of patient population.

The authors argue that because they recruit fewer patients, the characteristics of patients enrolled in phase II trials are more homogeneous than those in phase III trials, which aim to recruit hundreds of participants. This is contrary to what statistics teaches.

I also find this hypothesis unlikely, given the constraints on patient recruitment and the sensitivity of principal investigators to the fragility of ALS diagnoses and the variability of patient phenotypes.

The authors also propose specifically that edaravone and Relyvrio (AMX0035) phase II studies yielded better results than their phase III studies. However, the phase II trials for these two drugs did not provide clear evidence of a therapeutic benefit, only showing marginal improvements in the ALSFR-R criterion, which is known to be influenced by non-medical factors such as access to better equipment. Relyvrio/AMX0035 in particuliar benefited from the intense pressure by ALS organisations. It should be noted that one of these organisations would have financially greatly benefited in a market authorization.

Furthermore, post-hoc analyses, which are often favored by drug manufacturers, are statistically unreliable. It is too easy to select favorable results from a small sample and attribute them to a common characteristic, which is why large-scale clinical trials are necessary.

In my opinion, it is time to recognize that we are on the wrong track in relying on molecular biology experts to develop treatments for neurodegenerative diseases. The current pharmacological approach is heavily influenced by our understanding of communicable diseases, where identifying the pathogen and suppressing it can lead to recovery. Molecular biology is conceptually far removed from medicine, as it ignores cellular mechanisms, tissue-level interactions, physiological systems, and the complex interplay between organs.

I believe that we would be better served by acknowledging that neurodegenerative diseases are the result of a complex interplay of factors, including a patient's medical history, lifestyle, and environmental exposures. Each patient over the age of 50 likely has a unique combination of age-related neurological diseases, with some having a history of strokes, high-intensity sports, environmental toxins, or head trauma. Some may have also had a history of substance abuse or smoking.

In summary, I believe that neurodegenerative diseases are the result of a complex interplay of factors in a patient's history, rather than a single molecular event. Therefore, funding for most molecular biology efforts should be gradually shifted to regenerative medicine, which addresses the restoration of damaged tissues and organs.

I am pleased that two new articles bear a similar message: That neurodegenerative diseases can't be understood with the paradigm acquired with communicable diseases.

This paradigm tells us that as the pathogen is quite homogeneous, so is the disease phenotype. This is indeed wrong for non-communicable diseases like cancers and is even wrong for some communicable diseases like COVID-19 where the pathogens have heavily mutated.

One of these articles is "Serena Verdi et al, Personalizing progressive changes to brain structure in Alzheimer's disease using normative modeling".

The authors looked at 3233 brain scans. The number of non-standard brain structures increased over time in people with Alzheimer's disease. Patterns of change in outliers varied markedly between individual patients with Alzheimer's disease.

The authors say: "I think we need to pivot towards a new way of thinking to get away from the idea that this (brain) area is important, this area isn't". The big picture and the individual variability contained within it, is what counts.". Some of this individual variability may stem from the fact that many people with Alzheimer's have more than one cause of cognitive illness.

This idea that "we need to pivot towards a new way of thinking to get away from the idea that this (brain) area is important, this area isn't" is certainly important when we think of other neurodegenerative diseases such as ALS or Parkinson's disease.

Our knowledge about Parkinson's disease is limited. The official narrative is that Parkinson's disease is characterized by progressively expanding nerve cell death originating in substantia nigra, a midbrain region that supplies dopamine to the basal ganglia, a system involved in voluntary motor control. The cause of this cell death is poorly understood but involves alpha-synuclein aggregation into Lewy bodies within the neurons. Substantia nigra is really a tiny part of the brain, and other studies have already revealed a wider involvement in the brain. I guess we would make significant progresses in the disease knowledge if we acknowledge that if alpha-synuclein is involved in Parkinson's disease, it is unlikely its effects are limited to a tiny portion of the brain, as alpha-synuclein is abundant in the brain, while smaller amounts are found in the heart, muscle and other tissues and Lewy bodies are in the midbrain and the cortex.

Another interesting article is: "Ophthalmate is a new regulator of motor functions via CaSR: implications for movement disorders".

While the official narrative is that Parkinson's disease is characterized by neuronal death in substantia nigra, which supplies dopamine to the basal ganglia, a system involved in voluntary motor control, it has been known for decades that robust motor activity can happen in Parkinson's mouse models when L-DOPA conversion to dopamine is blocked! The motor improvement is larger than in the conventional case where L-DOPA is metabolized in dopamine. The authors hypothesized that there was an alternative pathway or mechanism, independent of dopamine signaling.

The authors sought to determine the metabolites associated with the pronounced hyperactivity observed. They observed that the peak in motor activity induced by inhibiting L-DOPA conversion into dopamine in Parkinson’s disease mice was associated with a surge (20-fold) in brain levels of the tripeptide ophthalmic acid (also known as ophthalmate in its anionic form). When they administered ophthalmate directly into mice's brains, it rescued motor deficit in a dose-dependent manner.

The team investigated the molecular mechanisms underlying ophthalmate’s action and discovered, that ophthalmate binds to and activates the calcium-sensing receptor (CaSR). To strengthen their findings, they verified that a CaSR antagonist inhibits the motor-enhancing effects of ophthalmate.

A link between Parkinson's disease and the calcium-Sensing Receptor is interesting as CaSR also Mediates β-Amyloid production. There is only one other publication that explicitly links the disease to CaSR. Calcium acts in a number of signal transduction pathways as second messengers, so maybe it is not wise to read too much about a link between Parkinson's disease and CaSR, but finding that lack of dopamine is not the main cause of Parkinson's disease, is a major finding.

Methylcobalamin Authorized in Japan for ALS

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Vitamin B12 injections are sometimes proposed by neurologists to ALS patients. Patients often decide to start the treatment because of the perceived low risk of side effects and the potential benefit to their quality of life. It is typically shipped as a sealed frozen package with several vials containing a 25-mg injectable dose. Patients are typically advised to inject 50 mg of B12 daily, which is 100 times the daily recommended dose. Usually, ALS patients recognize some benefits from the injections, such as increased energy, reduced fatigue, and improved balance. However, the high cost of injection, lack of insurance coverage, and inconsistent syringes are significant challenges faced by patients.

High-dose methylcobalamin treatment involves intramuscular injection of 25mg to 50mg of methylcobalamin twice a week, which is 50 to 100 times the dose of existing drug injections.

A phase II/III clinical trial for ALS patients was started in Japan, and the results were published in 2019. 373 ALS patients who had been onset for less than 3 years were recruited for a methylcobalamin clinical trial with three branches where patients have daily administrated 50mg, 25mg, or a placebo. It was conducted over 3.5 years. As a result, the methylcobalamin group showed a tendency to show better results in terms of the decline in ALSFRS-R, but the difference was not significant, and overall efficacy could not be demonstrated to Japanese authorities.

However, when a subanalysis was conducted only for patients who were enrolled within 12 months of onset (close to diagnostic), the 50 mg group, the 25 mg group, and the placebo group showed less decline in ALSFRS-R and a longer time to the primary endpoint. Post-analysis is frowned on because in small groups there are always statistical flukes and it's easy to cherry-pick some of these to prove whatever. But here the size of the trial was a bit larger than usual so there was more confidence in the findings.

The difference in decline in ALSFRS-R between the 50 mg group and the placebo group was statistically significant. Based on these results, a clinical trial (JETALS trial) was conducted in 2017 to confirm the reproducibility of the subanalysis, and the results were announced in May 2022. Results were reported on this blog.

In the JETALS study, 130 ALS patients within 12 months of onset were recruited and assigned to a twice-weekly 50 mg group or a placebo group. As a result, the reduction in ALSFRS-R score at 16 weeks was −2.66 in the methylcobalamin 50 mg group and −4.63 in the placebo group, which was significantly better in the active drug group.

There was no difference in side effects of the drug between placebo or methylcobalamin-treated participants. There was a marked reduction in serum homocysteine levels. Homocysteine is neurotoxic and has been associated with ALS cases but also with Alzheimer's and Parkinson's diseases. It may be a byproduct of methionine metabolism and there are a few studies that discuss the influence of diet on homocysteine via methionine in diet. High levels of methionine can be found in eggs, meat, and fish; sesame seeds, Brazil nuts.

These results are better than most previous drug results in ALS, but indeed it does not stop the disease progression. Based on these results, it was announced in January 2024 that a new drug application for methylcobalamin had been submitted in Japan.

Eisai Co. announced last week that it has obtained manufacturing and marketing authorization approval for amyotrophic lateral sclerosis (ALS) treatment “Rozebalamin® for Injection 25 mg” (mecobalamin) in Japan as a treatment for slowing progression of functional impairment in amyotrophic lateral sclerosis.

It should be noted that although there were statistically significant reductions in ALSFRS-R, other measures such as muscle strength, forced vital capacity, and the ALSAQ-40 total score, were not changed. This is a bit confusing as ALSFRS-R and ALSAQ-40 while not identical are similar enough, ALSAQ-40 adds a well-being dimension to the usual questionnaire. How could ALSFRS-R show an improvement if it's not reflected in ALSAQ-40?

As UK's Alsa-Mnd remarks, as the drug was only tested on participants early in the disease process, it is unclear if the treatment would be appropriate for participants with more advanced diseases.

In addition, Alsa-Mnd says it may not have been a truly blinded trial as methylcobalamin treatment results in a marked change in urine color which could mean that participants may have known whether they were receiving a placebo or methylcobalamin, and that could have influenced results (including a potential “nocebo” effect). This is supported by the fact that the placebo group appeared to worsen their rate of disease progression once the trial commenced.

It's possible that regulation agencies are afraid of the considerable political pressure from patient organizations who accuse them of being inactive, and that as for Alzheimer's disease and (temporarily) for AMX0035/Relyvrio they prefer to authorize new drugs even if they are ineffective, instead of waiting decades for an effective drug.

Here is a somewhat interesting article about Alzheimer's disease, but I guess it has also value for studies of ALS and Parkinson's disease.

Until the 1980' all cells in the brain that were big enough to be studied routinely were the neurons. Neurons are impressive cells because they are extremely long. The other cells were called the glue "glia" because they had no obvious functions. Neurons are also impressive because they can convey electrical and chemical signals over long distances. Neurons once mature, mostly do not divide, especially the ones with long axons. Other cells more conventionally divide every few days. enter image description here Those other cells, which compose half of the brain's cells, are receiving more attention. There are multiple types but normally they are there to assist neurons in their task. A simplified view tells that neurons are a sort of plumbing system and the glial cells are the real actors in the brain.

One of the glial cells, the astrocytes, seems to play important roles, and these roles may change depending on biological events such as stress or pathogen intrusion. When they enter the state called reactive state (M1), they kill neurons, in a similar manner that macrophages (white cells) kill infected cells.

In Alzheimer's disease, the shrinking of the brain which is the result of dying neurons and glia, is associated with aggregates of amyloïd proteins (Aβ). The study found that Aβ protein triggers autophagy in astrocytes. Autophagy is a cellular process involved in waste removal and recycling. Cells need new proteins every passing minute to function correctly, and the diet would never be able to provide protein building blocks at the required speed, so it is of the utmost importance for cells to recycle used proteins. There are several kinds of autophagy mechanisms in cells. Neurons being quite passive giant cells, autophagy is mostly assured by astrocytes.

Recycling proteins is not a clean job, it involves breaking proteins into smaller components (the metabolites or even amino acids) in a series of steps. Some of these intermediate components are toxic.

This article investigates the role of autophagy in astrocytes in the context of Alzheimer's disease (AD). Autophagy plays a crucial role in clearing Aβ so disrupting autophagy in astrocytes leads to increased Aβ plaques and cognitive decline in AD mouse models. Conversely, enhancing autophagy by over-expressing the LC3B pathway with a genetic therapy in astrocytes can reduce Aβ plaques and improve cognitive function.

It is believed by the authors that Aβ is toxic because it induces urea cycle activation in astrocyte as a compensatory mechanism to deal with the toxic effects of Aβ.. The urea cycle is a metabolic pathway that primarily occurs in the liver, but it can also be active in astrocytes. This pathway is involved in detoxifying ammonia, a toxic byproduct of amino acid metabolism.

Overall, this study provides evidence that targeting autophagy in astrocytes may be a promising therapeutic approach for AD. Understanding the relationship between Aβ, autophagy, and the urea cycle could potentially lead to new therapeutic strategies for AD. For example, targeting the urea cycle or autophagy pathways might be explored as potential approaches to reduce Aβ toxicity.


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