Transcriptional profiling reveals TRPM5-expressing cells involved in viral infection in the olfactory epithelium.

Understanding viral infection of the olfactory epithelium is essential because smell loss can occur with coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus clade 2 (SARS-CoV-2), and because the olfactory nerve is an important route of entry for viruses to the central nervous system. Specialized chemosensory epithelial cells that express the transient receptor potential cation channel subfamily M member 5 (TRPM5) are found throughout the airways and intestinal epithelium and are involved in responses to viral infection. Herein we performed deep transcriptional profiling of olfactory epithelial cells sorted by flow cytometry based on the expression of fluorescent protein markers for olfactory sensory neurons and TRPM5. We find profuse expression of transcripts involved in inflammation, immunity and viral infection in TRPM5-expressing microvillous cells and olfactory sensory neurons. These cells express the Tmprss2 transcript that encodes for a serine protease that primes the SARS-CoV-2 spike protein before entry into host cells. Our study provides new insights into a potential role for TRPM5-expressing cells in viral infection of the olfactory epithelium.