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The Amazing Phenomenon Of Mad Cows, Knotted Nerves And Misfolded Proteins

Misfolded Proteins in Disease

Prion Diseases: The Classic Misfolded Protein

Creutzfeldt-Jakob Disease is the stereotypic exemplar of a disease caused by misfolded proteins. It’s effectively a kind of dementia. Eating the meat of infected cattle leads to the illness. In cattle, we call it Bovine Spongiform Encephalopathy (BSE), aka Mad Cow Disease.

Misfolded proteins called prions cause the disease. Curiously, we don’t know the biological function of healthy prions. They become misfolded when infected. Misfolded prions propogate by inducing misfolding in healthy prions, leading to a chain reaction.

Unfortunately, this causes a rapidly advancing infectious disease that drives neural degeneration in the brain and leads to death.

Alzheimer’s Disease (AD)

The primary pathology is Alzheimer’s Disease is misfolded beta-amyloid (Aβ) proteins. At least, that’s according to current thinking. Synapses are the connections between nerves. Aβ disrupts normal synaptic function by interfering with neurotransmitter release and receptor function. Than impairs neural transmission. As a result, long-term potentiation (LTP), a process critical for learning and memory, is impaired. As the disease spreads, other aspects of cognitive functioning become affected.

Over and over those issues, Aβ causes mitochondrial dysfunction. Mitochondria are critical for energy production in cells. When damaged, signals are sent that cause a kind of cellular suicide (apoptosis, programmed cell death). Additionally, Aβ causes oxidative stress through the production of reactive oxygen species (ROS), which damages lipids (fats), proteins, and DNA in neurons. This triggers a massive inflammatory response.

In addition to Aβ pathology, in Alzheimer’s, hyperphosphorylated tau protein forms tangles inside neurons. We call these misfolded proteins neurofibrillary tangles. As the name suggests, these are literally nerves that get into a knot. This damages tiny tubules inside the nerve that normally transport nutrients. As a result, the nerves starve and die.

Parkinson’s Disease (PD)

In Parkinson’s Disease, misfolded alpha-synuclein protein accumulates to form clumps within cells. We believe that this starts in the gut and over the course of many years gradually spreads to the brain. These protein aggregations go by the name Lewy bodies. They impair nerve transmission by disrupting synapses. Furthermore, Lewy bodies cause degeneration of dopaminergic neurons in the substantia nigra in the brain. This leads to a loss of dopamine in the brain. That drives the characteristic motor symptoms of Parkinson’s disease: tremor, slow movement, stiffness and instability.

The cellular damage in synapses causes activation of immune cells in the brain, microglia. In turn, microglia trigger widespread inflammation in the brain. That inflammation worsens the ongoing pathology. Reducing the inflammation in PD brains, reduces symptoms. It also helps to improve dopamine levels.

Huntington’s Disease (HD)

Huntington’s is a hereditary condition involving a protein called huntingtin (sic). It becomes misfolded and this leads to abnormal polyglutamine repeats. These are strings of cytosine-adenine-guanine (CAG) that accumulate in neurons. In the long run, this leads to impairments of movement, cognition, and to psychiatric disturbances.

Amyotrophic Lateral Sclerosis (ALS)

ALS causes damage to motor neurons in the brain and spinal cord. It leads to progressive muscle weakness and paralysis. The underlying pathology in ALS is of aggregates of misfolded proteins. Specifically, implicated proteins include TDP-43 and SOD1.

TAR DNA-binding protein 43 (TDP-43) is a protein that plays a key role in many cellular functions, including RNA metabolism, mRNA transport, and microRNA maturation. Normally, TDP-43 resides in the cell nucleus. In ALS, clumps of misfolded TDP-43 accumulate in the cytoplasm of cells. Furthermore, TDP-43 aggregates occur in various types of dementia.

Superoxide dismutase 1 (SOD1) is an enzyme that normally protects cells from oxidative stress. However, when it becomes misfolded, it malfunctions. Without its protection, nerves get damaged.

Multiple System Atrophy (MSA)

MSA involves degeneration in specific brain areas such as the basal ganglia, cerebellum, and autonomic nuclei. The characteristic neuropathology includes:

• glial cytoplasmic inclusions (GCIs)
• neuronal cytoplasmic and nuclear inclusions
• nerve death
• loss of oligodendrocytes.

In MSA there is an accumulation of misfolded alpha-synuclein in glial cells. You’ll recognise these as the same Lewy bodies found in Parkinson’s, except now mainly in glial cells. Glial cells are the major support cells in the brain. They are not actually nerve cells.

Papp and Lantos discovered these glial inclusions in 1989. They observed that misfolded clumps of alpha-synuclein consistently appeared in oligodendrocytes. Oligodendrocytes are the source of myelin in the brain. Myelin is a fat that surrounds nerves and speeds nerve conduction. Papp and Lantos noted that these inclusions were all seen in white matter in the brain. Well, white matter gets its colour from the white fat that is myelin.

Based on their findings, Papp and Lantos realised that three conditions were all manifestations of MSA. Previously, we had thought these were independent diseases. These are:

• striatonigral degeneration
• olivopontocerebellar atrophy
• Shy-Drager syndrome.

In recent years we have learnt that glial cells modulate cognitive functioning. Previously, we believed their roles was purely structural. In MSA, the damage affects autonomic functions, cognition and motor control.

Frontotemporal Dementia (FTD)

Misfolded folded proteins are also a feature of FTD. Specifically, misfolded tau proteins aggregate into insoluble fibrils, forming structures such as neurofibrillary tangles or Pick bodies in neurons. Normally tau stabilizes microtubules. These are tiny tubles inside nerves that transport nutrients. However, misfolded tau proteins cause bending of microtubules. That impairs intracellular nutrient transport. Ultimately, these neurons starve to death.

In FTD, there is also a effect on TDP-43 (TAR DNA-binding protein 43). Under normal circumstances, TDP-43 is involved in RNA processing, including splicing and transport. However, in FTD misfolding of TDP-43 causes problems. It relocates, moving from the cell nucleus to the cytoplasm where is accumulates to form toxic aggregates. In addition, these clumps of misfolded TDP-43 impair gene regulation, protein synthesis, and RNA metabolism.

In the context of FTD, it’s worth mentioning fused in sarcoma (FUS). This is a rare feature of FTD but also involves misfolded proteins. Similarly, like TDP-43, FUS is an RNA-binding protein that participates in gene regulation. Furthermore, misfolding and aggregation of FUS disrupt RNA homeostasis and cellular functions.

Overall, the net effect of tau misfolding, TDP-43 misfolding and occasional FUS misfolding causes progressive damage to the frontal and temporal lobes of the brain, affecting behavior and language and emotional functioning.

Chronic Traumatic Encephalopathy (CTE)

CTE arises from repeated blows to the head that cause concussion. As might expected then, professional contact sport players are at particular risk of CTE. Boxers, MMA, football, rugby, ice-hockey and so on. The hallmark of CTE is the pathological aggregation of misfolded tau protein into neurofibrillary tangles within neurons and astrocytes. Normally, tau stabilizes microtubules in neurons, ensuring proper intracellular nutrient transport. In contrast, in CTE, tau undergoes hyperphosphorylation, which destabilizes its structure, causing it to misfold and adopt a β-sheet conformation. Addtionally, this makes the protein insoluble and difficult to degrade. Moreover, clumps of tau aggregate in the bottom of cortical sulci.

While tau is the dominant misfolded protein in CTE, some evidence suggests secondary roles for other misfolded proteins, including TDP-43, in more severe cases or overlapping conditions like amyotrophic lateral sclerosis (ALS) or frontotemporal dementia (FTD).

Spinal and Bulbar Muscular Atrophy (SBMA)

SBMA involves the accumulation of misfolded proteins. The disease is caused by a CAG trinucleotide repeat expansion in the androgen receptor (AR) gene, which leads to the production of an androgen receptor protein with an abnormally long polyglutamine (polyQ) tract. Furthermore, these mutant AR proteins tend to misfold, aggregate, and form toxic clumps within motor neurons and muscle cells. Thus, the misfolding drives the motor symptoms of the disease, muscle wasting and weakness.

Current Research and Therapeutics for Misfolded Proteins

So, how do we fix all this? Let’s briefly recap. To clarify, we have learnt about the miracle of proteostasis. Specifically, the way we synthesie, shape, maintain, and recycle proteins. That’s out body’s way of maintaining the integrity of all our proteins. Unfortunately, as we age, our capacity to maintain proteostasis deteriorates. Additionally, we get exposed to substances like pesticides that compromise proteins. Moreover, errors start to creep in. During protein synthesis, proteins get misfolded. Consequently, their functionality is seriously undermined. That’s when we get ill.

Often, the effect of misfolded proteins takes years to emerge. Nonetheless, the resultant illness can be devastating. We end up with conditions like Alzheimer’s or Parkinson’s disease. Notably, we can mitigate the effects of neurodegenerative diseases. In particular, we need to promote the clearance of toxic protein aggregates and reducing associated neuroinflammation. Truly, that’s the trick!

Reducing Protein Production

This is “the throwing the baby out with the bathwater” option. We nuke the bad guys but also might nuke the good guys. The prime exemplar is gene silencing therapy using antisense oligonucleotides (ASOs) to target mutant huntingtin in Huntington’s disease. A concern is the potential unintended effect on the wild-type (healthy) huntingtin gene. Although ASOs are designed to target the mutant gene specifically, there is a risk of also silencing the healthy, normal version of the gene to some degree. Huntingtin plays an important role in neuronal function, and reducing healthy huntingtin could cause neurological damage.

Animal studies and early human studies in early-stage Huntington’s patients showed that the reduction in the huntingtin gene correlated with improvements in some biomarkers. However, larger studies into safety and efficacy in human patients did not demonstrate significant clinical benefit in terms of motor function or disease progression. However, longer follow-ups are ongoing.

In other words, to date, reducing protein production has not proved to be a successful treatment for misfolded proteins.

Enhancing Protein Clearance to Reduce Misfolded Proteins

Passive Immunotherapy

Intense research led to the development of using monoclonal antibodies (aducanumab and lecanemab) help clear misfolded Aβ in Alheimer’s patients. Those two drugs are now FDA registered. Three people died during the drug trials. Their death were attributed to the drugs. The drugs cause micro-haemorrhaging and swelling in the brain. Aside from these horrendous side effects, they are so prohibitively expensive that only the super-rich can afford them.

Active Immunotherapy

Vaccines to stimulate immune responses against misfolded proteins are an option. A vaccine for use in Parkinson’s disease (PD) and multiple system atrophy (MSA) is being developed and early trials show very encouraging results. The drug does not even have a name yet, and goes by the moniker of UB-312. Its mechanism of action is to induce antibodies that bind to alpha-synuclein.

In animal models of PD, immunisation with UB-312 reduced the accumulation of alpha-synuclein in the brain and in the gut and prevented a decline in motor function. In a phase 1 trial of 20 human PD patients, they developed antibodies to alpha-synuclein within eight weeks of vaccination. The clinical benefits in humans have yet to be clearly delineated, but the presence of antibodies implies the likelihood of reduced levels of alpha-synuclein. At this stage, researchers are still investigating safety but so far it looks promising.

This information was presented in late 2024 International Congress of Parkinson’s Disease and Movement Disorders that concluded a few days ago. I want to stress that these are very early findings and we are a long way from having anything ready for clinical use.

Chaperone-based Strategies:

Small molecules like arimoclomol enhance molecular chaperones (Hsp70, Hsp90), improving refolding or promoting clearance via autophagy.

Modulating Autophagy and Proteasome Pathways

We could try boosting cellular clearance mechanisms. For instance, we could use mTOR inhibitors like rapamycin to enhance autophagy. That could increase lysosomal degradation of misfolded proteins. We could try proteasome enhancers. These are great ideas but are largely only theoretical at this point and more research needs to be done.

Stabilizing Protein Structures

We could use small molecules as chemical chaperones to stabilize native protein conformations and reduce misfolding. For instance, 4-phenylbutyrate (PBA) is a naturally occurring fatty acid derivative that has a number of potential therapeutic uses. For example, PBA can reduce the load of mutant or mislocated proteins in the endoplasmic reticulum (ER) in cystic fibrosis.

However, I’m only aware of animal research with PBA in the group of brain diseases we’re discussing here. There is a human trial underway currently looking at Parkinson’s patients but we await those results.

Addressing Mitochondrial Dysfunction from Misfolded Proteins

Reduce Oxidative Stress

Misfolded proteins often accumulate in mitochondria, impairing their function and leading to oxidative stress and energy deficits. We could use antioxidants, of which there are some great natural alternatives. Likewise, we could use PPAR-gamma coactivator 1-alpha (PGC-1α) activators to boost mitochondrial biogenesis. Hah! Now that’s an interesting option. You’ll have to talk to me and I’ll explain.

Reducing Neuroinflammation from Misfolded Proteins

Misfolded proteins often activate microglia and astrocytes, leading to chronic inflammation and neuronal damage. To reduce inflammatiion you could try standard anti-inflammatory drugs (NSAIDs, colchicine) but these are associated with mixed results in neurodegenerative diseases.
Better still, you could use some of the wonderful specialised proresolving mediators we supply. Those amazing supplements flip a biochemical switch that stops inflammation.

Dietary Approaches to Misfolded Proteins & Restoring Proteostasis

Ketogenic Diet

A ketogenic diet shifts metabolism from glucose to ketones, reducing oxidative stress and improving mitochondrial function. Evidence suggests benefits in Alzheimer’s and Parkinson’s disease by enhancing autophagy and reducing inflammation.

Misfolded Proteins & Fasting

Fasting and caloric restriction promotes autophagy, which helps to clear misfolded proteins. Also, fasting reduces inflammatory cytokines, enhancing cellular resilience.

Polyphenol-rich Diet

Foods rich in polyphenols (e.g., green tea, berries, turmeric) possess anti-inflammatory, antioxidant, and autophagy-boosting properties. For example, epigallocatechin gallate (EGCG) in green tea modulates protein folding.

Omega-3 Fatty Acids

Found in fish oil, omega-3s are anti-inflammatory and support neuronal membrane integrity. These properties may reduce susceptibility to protein aggregation.

Supplements to Reduce Misfolded Proteins

Lastly, nutraceuticals that enhance proteostasis include:

• Curcumin: Reduces beta-amyloid aggregation and inflammation.
• Sulforaphane: Upregulates antioxidant and chaperone systems.
• Vitamin D. An immune modulator that reduces neuroinflammation.