Researchers in the United States have made a breakthrough in Alzheimer’s disease research by creating a nasal spray that can remove harmful proteins in the brain, at least in mice. This new treatment targets a protein called tau, which plays a significant role in Alzheimer’s and other neurodegenerative diseases.
Alzheimer’s disease is linked to two main proteins: amyloid and tau. Current treatments mostly focus on removing amyloid. These treatments include drugs recently approved by the US Food and Drug Administration (FDA). However, there hasn’t been much focus on removing tau “tangles” until now. Scientists at the University of Texas Medical Branch have developed a nasal spray that targets tau.
In a healthy brain, tau proteins help maintain the support structure of neurons (brain cells). However, in Alzheimer’s and other neurodegenerative diseases, tau proteins accumulate inside cells, twist abnormally, and form thread-like structures known as neurofibrillary tangles. These tangles are not efficiently cleared by the brain’s waste removal processes, causing cell damage and death, leading to memory loss.
Focusing on tau may lead to effective treatments for several neurodegenerative diseases, including:
– Alzheimer’s disease
– Frontotemporal dementia
– Lewy body dementia
– Progressive supranuclear palsy
Alzheimer’s disease involves both the accumulation of tau inside neurons and the buildup of amyloid plaques between neurons, which leads to cell death.
Most current treatments for Alzheimer’s target amyloid removal. These treatments include FDA-approved drugs like lecanemab and donanemab. While these drugs have slowed cognitive decline in clinical trials, they have limitations such as accessibility, cost, and effectiveness only at early stages of diagnosis.
Some experts argue that the slowed disease progression might be too slight to notice in early-stage Alzheimer’s. Moreover, it’s unclear if this slowed progression is sustained in the long term.
So far, treatments targeting tau have been less effective in human trials. One major challenge is that tau accumulates inside neurons, making it difficult for treatments to reach these areas. On the other hand, amyloid accumulates outside neurons, which is easier to target.
Researchers at the University of Texas Medical Branch have developed an innovative nasal spray that shows positive results in reducing tau buildup and improving memory in aged mice with neurodegenerative diseases.
The researchers first optimized antibodies (proteins created by the immune system) to latch onto and eliminate tau proteins. They tested these antibodies in petri dishes containing human nerve tissue with tau proteins.
After identifying the most effective antibody (called TTCM2), they packaged it into tiny bubbles of fat (lipids). These bubbles are small enough to pass through the blood-brain barrier and enter neurons.
The blood-brain barrier is a protective layer that keeps harmful substances from entering the brain. Breaking through this barrier was a major challenge in targeting tau and tangles. Once inside the brain, the outer layer of the bubble dissolves, releasing the antibodies to clear tau buildup.
For therapeutic purposes, the researchers dissolved the antibody in a liquid solution and delivered it using a nasal spray to mouse models of Alzheimer’s disease.
Promising Results
A single dose of this nasal spray significantly reduced tau accumulation in the brains of old Alzheimer’s mice. Similar results were observed when applying the spray to human nerve tissue samples.
The nasal spray also showed significant improvements in memory and cognition in these mice. This was tested using the novel object recognition test, which assesses whether mice can identify a new object compared to a familiar one.
While these results are exciting, it’s important to remember that this research has not yet been tested on humans. Although mice are valuable models for studying potential treatments, there are significant differences between mice and humans.
Approximately 70% of drugs in the “preclinical phase” (before testing in humans) do not make it to human trials. The success rate in clinical trials (testing in humans) is even lower, with 90% of drugs failing to make it to market.
Despite these challenges, this nasal spray method offers promising potential for non-invasive delivery of tau antibodies directly to the brain, potentially treating various neurodegenerative diseases affected by tau accumulation.
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