Olfactory dysfunction (OD), also known as anosmia or hyposmia, or the loss or reduction of the sense of smell, is one of the long-term effects of Covid-19 infection.

A new entirely Italian study, a collaboration between Sapienza University of Rome (Professor Roberta Lattanzi; Dr Daniela Maftei, Dr Martina Vincenzi of the "Vittorio Erspamer" Department of Physiology and Pharmacology), CNR (Dr Cinzia Severini, Institute of Biochemistry and Cell Biology, at the Department of Sense Organs, Sapienza University of Rome) and the University of Rome Tor Vergata (Professor Nicola Biagio Mercuri, Professor Francesco Maria Passali, Dr Tommaso Schirinzi) identified new molecular pathways involved in this pathological manifestation of the post-Covid syndrome. The results have been published in the journal Brain, Behavior, and Immunity.

By analysing the olfactory neurons of patients with OD for at least 6 months, the researchers demonstrated a significant increase in the activity of two inflammatory pathways closely linked to the pathophysiology of olfaction, namely substance P (SP) and prokineticin-2 (PK2), compared to control subjects. This increase, in correlation with olfactory tests, shows the importance of these pathways in the long-term alterations of the post-Covid-19 syndrome.

Olfactor neurons were obtained through nasal brushing, the brushing of the olfactory mucosa, a non-invasive technique that allows these neurons, similar to brain neurons, to be taken and then analysed.

"While the increase of SP," says Professor Roberta Lattanzi of the "Vittorio Ersparmer" Department of Physiology and Pharmacology of Sapienza University, "seems to be a key factor in the inflammatory process that is probably at the origin of the cytokine storm, the expression of PK2 could instead be correlated with the recovery of olfactory functions".

Considering that post-Covid-19 olfactory dysfunction could be a prelude to potential long-term neurological consequences, identifying new molecular targets may be helpful for the early marking of risk conditions and for developing targeted therapies.

References:

Substance P and Prokineticin-2 are overexpressed in olfactory neurons and play differential roles in persons with persistent post-COVID-19 olfactory dysfunction - Tommaso Schirinzi, Roberta Lattanzi, Daniela Maftei, Piergiorgio Grillo, Henri Zenuni, Laura Boffa, Maria Albanese, Clara Simonetta, Roberta Bovenzi, Riccardo Maurizi, Laura Loccisano, Martina Vincenzi, Antonio Greco, Stefano Di Girolamo, Nicola B Mercuri, Francesco M Passali, Cinzia Severini - Brain Behav Immun. 2022. doi: 10.1016/j.bbi.2022.12.017. 
 

Further Information

Roberta Lattanzi
"Vittorio Erspamer" Department of Physiology and Pharmacology
roberta.lattanzi@uniroma1.it