Ace2 in the healthy and inflamed taste system

PROJECT SUMMARY / ABSTRACT Taste deficits are prevalent in people infected with SARS-CoV-2, the virus responsible for the global COVID-19 pandemic. The loss of taste sensation negatively affects nutrition and quality of life and in some patients this deficit is long-lasting. The biological basis for taste loss due to SARS-CoV-2 is largely unknown. Our preliminary results demonstrate that the ACE2 receptor and TMPRSS2 which together mediate SARS-CoV-2 host cell entry are expressed in taste buds indicating their potential for viral infection. The function of taste cell ACE2, also a member of the renin-angiotensin system that regulates fluid balance, is unknown. We have developed three novel genetic mouse strains to overcome the limitations of currently available mouse models. In aim 1 we map ACE2 reporter expression to determine which taste receptor cell populations and pathways are potential targets of SARS-CoV-2. In aim 2 we test how lingual epithelium-specific ACE2 contributes to taste receptor cell dynamics and neurophysiological taste responses under baseline and inflammatory conditions. We will also test how taste function is affected by human SARS-CoV-2 spike protein in a humanized ACE2 knock-in mouse. Our hypothesis predicts that taste buds are SARS-CoV-2 targets, that taste ACE2 contributes to taste function and is protective during inflammation, and that SARS-CoV-2 spike protein will exacerbate damage in taste buds and depress neural taste responses under inflammatory conditions. This R21 Exploratory / Developmental grant application addresses the urgent need for fundamental insights to mechanisms underlying taste dysregulation in people with COVID-19.