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- To introduce by the nose: smells will be returned to those who have lost their sense of smell after COVID-19
To introduce by the nose: smells will be returned to those who have lost their sense of smell after COVID-19
For the first time in the world, Russian scientists have described in detail at the molecular level the mechanism of olfactory disorders in coronavirus infection and other pathologies. This complication is observed in about half of COVID-19 cases, but there is still no universal method of control. According to the new concept, a person stops smelling due to a malfunction of a protein that activates olfactory neurons. According to experts, if the hypothesis is experimentally confirmed in animals and humans, it can become the basis for creating a new type of medicine that can restore the sense of smell.
Protein malfunction
For the first time in the world, specialists from the Institute of Cytology of the Russian Academy of Sciences have described in detail the mechanism of loss of sense of smell in various pathologies, including COVID-19, other respiratory infections, as well as neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Despite the fact that about 50% of COVID-19 cases are associated with anosmia, there is still no universal effective treatment.
According to the results of laboratory experiments by Russian scientists, impaired sense of smell may be associated with fibrillogenesis, the transformation of odorant-binding proteins into collagen fibers. This, in turn, leads to malfunction of the olfactory neurons.
The data obtained can be used to develop new therapeutic methods to combat olfactory dysfunction.
"The paper formulates a new concept of the origin of olfactory disorders, comparing the decrease in the activation of olfactory neurons and their death with the fibrillogenesis of odorant-binding proteins, the main participants in olfactory perception," says an article in the scientific journal Cell Death Discovery, which is published by the international publishing house Springer Nature.
According to the authors, the structural changes triggering these pathological processes can be caused by various factors, including oversaturation of the olfactory mucus, a decrease in its acidity due to infections, or even the use of nasal sprays.
The scientists explained that nasal mucus performs barrier and protective functions, it traps pathogenic bacterial and viral particles, preventing them from entering the olfactory epithelium and minimizing the risk of infection. As a result of interaction with it, pathogenic bacterial strains can use the body's proteins in their life cycle and change their structure.
The proposed concept is confirmed by laboratory data, but the researchers emphasize that it needs further proof in experiments on animals and humans.
A new type of medicine
Russian researchers have discovered a new mechanism of olfactory loss associated with the "breakdown" of special transport proteins in the nose. These odorant-binding proteins usually deliver odor molecules to olfactory receptors, but under certain conditions they can clump together into toxic lumps that block the perception of odors and damage olfactory cells, Anna Khoruzhaya, lecturer at the Modern Technologies in Healthcare course of the Applied Analysis in Medicine Master's program at MIPT, explained to Izvestia.
"This explains why people may lose their sense of smell with COVID—19, neurodegenerative diseases, or after using certain nasal medications. Understanding this mechanism will allow us to create drugs that can stabilize the structure of these proteins and prevent them from sticking together," she said.
Clinical studies are now required to confirm this hypothesis in patients. If the hypothesis is confirmed, a new pharmacological group of drugs may appear aimed at treating odor loss, a problem that has remained without an effective solution for a long time, the specialist added.
Albert Rizvanov, head of the KFU Center of Excellence for Personalized Medicine, noted that the authors of the scientific article offer an unexpected explanation for the loss of sense of smell. Classically, it was explained by inflammation and nerve damage, but the new work shifts the focus specifically to the biochemistry of mucus and carrier proteins.
— This is a scientifically plausible hypothesis, supported by a number of biophysical experiments on cells, where proteins actually form such structures and lose their function. However, there are no clinical and experimental confirmations in animals or humans yet. We need evidence of this form of protein in the nasal mucus of patients and its correlation with the clinic," he said.
The concept potentially opens up new targets for therapy. For example, to develop tests for such forms of protein in nasal mucus or to select protein structure stabilizers, as well as to suppress their aggregation, the specialist suggested. Such approaches can be used as an addition to classical methods of treatment and rehabilitation of patients.
If the concept turns out to be correct, then it will be possible to develop tests to detect pathology or create drugs that will help restore lost function, said Stanislav Stragnov, head of the master's program "Applied Analysis in the Medical Field" at MIPT. According to him, it may take a long time. However, this period can be shortened if it is possible to select a drug that has already been approved for other purposes. The open mechanism can allow restoring the sense of smell not only in the case of COVID-19 and its consequences, but also in other diseases, such as neurodegenerative diseases, which means that the results will definitely be in demand, the specialist concluded.
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