In a study from Duke University, scientists found an ongoing immune assault on olfactory nerve cells and an associated decline in the number of those cells may explain why some people fail to recover their sense of smell after COVID-19.
The finding provides an important insight into a vexing problem that has plagued millions who have not fully recovered their sense of smell after COVID-19.
While focusing on the loss of smell, the finding also sheds light on the possible underlying causes of other long COVID-19 symptoms—including generalized fatigue, shortness of breath, and brain fog—that similar biological mechanisms might trigger.
In the study, the team analyzed olfactory epithelial samples collected from 24 biopsies, including nine patients suffering from long-term smell loss following COVID-19.
They found widespread infiltration of T-cells engaged in an inflammatory response in the olfactory epithelium, the tissue in the nose where smell nerve cells are located.
This unique inflammation process persisted despite the absence of detectable SARS-CoV-2 levels.
Additionally, the number of olfactory sensory neurons was diminished, possibly due to damage to the delicate tissue from the ongoing inflammation.
The team says learning what sites are damaged and what cell types are involved is a key step toward beginning to design treatments.
The researchers were encouraged that neurons appeared to maintain some ability to repair even after the long-term immune onslaught.
The team says the findings from the study could also inform additional research into other long-COVID-19 symptoms that might be undergoing similar inflammatory processes.
For more information about COVID, please see recent studies about new discovery that may help stop flu forever, and results showing COVID-19 mixed with flu can increase risks of death.
The study was conducted by Bradley Goldstein et al and published in the journal Science Translational Medicine.
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