About this Research Topic
SARS-CoV-2 is a novel virus strain that, following a zoonotic spillover, has been causing COVID-19 in humans. Among others, anosmia and dysgeusia are now recognized as critical symptoms for COVID-19 infection. Patients report in fact sudden loss of taste and smell which persist sometimes even after they test negative for the virus.
Being the respiratory tract, among other systems, mostly damaged by SARS-CoV-2, it is not surprising that organs such as nose and mouth, representing the entry levels to the airways, undergo an enriched viral load, leading to major alterations in the physiology of these two sensory systems. The transmembrane metallocarboxypeptidase ACE-2, an enzyme long-known to be a key player in the Renin-Angiotensin system (RAS) and a target for the treatment of hypertension, is considered the entry receptor for SARS-CoV-2. The expression of ACE-2 in different body tissues tends to provoke a disseminated pathogenesis of COVID-19. In particular, ACE-2 expression in the olfactory sensorial epithelial (OSE) cells cause the primeval aerial infection and inflammation of the nasal cavity. The OSE inflammation produces olfactory impairment as early effect of virosis.
Although several anecdotical reports have appeared on both scientific and non-scientific literature, a more systematic understanding of this issue is needed. This research topic aims at selecting and gathering both clinical and basic research work to tackle this COVID-19 related feature and to exploit its potential both as a diagnostic/prognostic marker and a mean to better understand the impact of SARS-CoV-2 on the central nervous system.
Specifically, we aim at giving a systematic view of this field, provided by papers focusing on:
- Time of onset and length of the symptoms in relation to COVID-19 related loss of smell and taste and its relationship with the severity of the disease, its outcome, and the onset of other neurological and non-neurological features
- How to standardize procedures to assess and score anosmia and dysgeusia
- Gender, age, ethnicity in the prevalence of the anosmia and dysgeusia symptoms
- Loss of taste and smell in animal models infected with SARS-CoV-2
- Molecular investigation to assess COVID-19 related alteration in the signal transduction pathways involved in conveying taste and smell
- Changes undergone by glia and microglia during COVID-19 infection
- Involvement of ACE-2 receptor in the SARS-CoV-2 impact on the olfactory and gustation systems
- Smell and taste impairment and correlation with patients’ physiological parameters
- Generation of cellular models suitable to investigate COVID-19 neurological aspects
- The olfactory bulb as the entry site for SARS-CoV-2 propagation to the brain
The list above represents just some of the aspects which we think would be welcome to cover in the present Research Topic, but it is not meant be exhaustive and we are obviously open to other issues. In addition, submission of critical reviews on the status and perspectives in the field is encouraged.
Keywords: smell, taste, COVID-19, central nervous system, prognostic marker, thalamus, orbitofrontal cortex, olfactory bulb, sentinel symptoms, neurotoxicity, ACE-2
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