Coronavirus disease 2019 has spread rapidly across the world and is a pressing public health emergency. Covid-19 affects different people in different ways. A multitude of symptoms have been reported, ranging from the mildest that may make it easier to conflate with a common cold, to the more severe, which may result in immediate hospitalization and being put on a ventilator for weeks at a time. One of the seemingly less severe symptoms that more people are experiencing as cases are exponentially rising, is the loss of taste and smell. For some people this is an early and even sometimes only symptom of the virus they may experience. While it might not seem as drastic as other symptoms, the impact it may have on quality of life can be depriving. Not being able to smell familiar scents and not being able to enjoy favorite dishes anymore can be a serious loss in an individual’s life experiences. It can also be dangerous in other aspects, for example not being able to smell smoke or gas in the air in a house fire situation. Our senses are what connects us to the world, and losing two of them permanently can seriously affect both mental and physical health. These effects help explain why more studies are linking the burden of post-Covid anosmia and ageusia with increased depressive mood and anxiety (Speth et al, “Mood, Anxiety, and Olfactory Dysfunction”). The good news is gustatory and olfactory nerve cells are regenerative. But there are no promises that everyone will regain pre-Covid quality of taste and smell, if at all. As senses diminish with age, older patients' recovery could be longer and less complete.
The article, “Ephrin-B/EphB Signaling Is Required for Normal Innervation of Lingual Gustatory Papillae,” is one of the few making discoveries in the field of gustation. By studying the targeting of axons through innervation of taste buds, Treffy et al. were able to detect the role of non diffusible cell surface protein bioreceptors Ephs and ephrins and how they act as receptors and ligands for each other to control axon terminal positioning in the gustatory system. The study ultimately found that ephrin-B is a critical part of normal innervation on the mammalian tongue. Transmembrane Ephrin B is actually the driving force behind inducing signaling cascades that send axon potentials to the brain. As gustation is not a very competitive field and this is the first study to depict the role ephrin and Eph signaling in the sense of taste, and connecting this information to new and developing studies of how Covid-19 affects and kills taste cells can help us learn more about the viral mechanism, and even help us discover a way to recover taste in recovered patients to improve their quality of life. It is the hope that if any good is to come from this pandemic, it can further the existing knowledge and research in chemosensory systems as we learn more about the viral mechanism and ourselves.
Kay, Leslie. “Why COVID-19 Makes People Lose Their Sense of Smell.” Scientific American, Scientific American, 13 June 2020.
Speth, M.M., Singer‐Cornelius, T., Oberle, M., Gengler, I., Brockmeier, S.J. and Sedaghat, A.R. (2020), Mood, Anxiety and Olfactory Dysfunction in COVID‐19: Evidence of Central Nervous System Involvement?. The Laryngoscope, 130: 2520-2525. https://doi.org/10.1002/lary.28964
Treffy R, W, Collins D, Hoshino N, Ton S, Katsevman G, A, Oleksiak M, Runge E, M, Cho D, Russo M, Spec A, Gomulka J, Henkemeyer M, Rochlin M, W: Ephrin-B/EphB Signaling Is Required for Normal Innervation of Lingual Gustatory Papillae. Dev Neurosci 2016;38:124-138. doi: 10.1159/000444748
No comments:
Post a Comment