ABSTRACT
The year 2020 became the year of the outbreak of coronavirus, SARS-CoV-2, which escalated into a worldwide pandemic and continued into 2021. One of the unique symptoms of the SARS-CoV-2 disease, COVID-19, is the loss of chemical senses, i.e., smell and taste. Smell training is one of the methods used in facilitating recovery of the olfactory sense, and it uses essential oils of lemon, rose, clove, and eucalyptus. These essential oils were not selected based on their chemical constituents. Although scientific studies have shown that they improve recovery, there may be better combinations for facilitating recovery. Many phytochemicals have bioactive properties with anti-inflammatory and anti-viral effects. In this review, we describe the chemical compounds with anti- inflammatory and anti-viral effects, and we list the plants that contain these chemical compounds. We expand the review from terpenes to the less volatile flavonoids in order to propose a combination of essential oils and diets that can be used to develop a new taste training method, as there has been no taste training so far. Finally, we discuss the possible use of these in clinical settings.
Subject(s)
Ageusia/drug therapy , Ageusia/virology , Anosmia/drug therapy , Anosmia/virology , COVID-19 Drug Treatment , Phytochemicals/therapeutic use , Ageusia/metabolism , Anosmia/diagnosis , Anosmia/metabolism , COVID-19/complications , Humans , Phytochemicals/pharmacology , SARS-CoV-2/isolation & purificationSubject(s)
Anosmia/etiology , COVID-19/complications , Anosmia/metabolism , Anosmia/physiopathology , Cyclic AMP/metabolism , Cyclic GMP/metabolism , Hedgehog Proteins/metabolism , Humans , Intercellular Signaling Peptides and Proteins/metabolism , Nasal Mucosa/metabolism , Receptors, Odorant/physiology , Smell/physiologyABSTRACT
In patients with COVID-19,type 2 diabetes mellitus (T2DM) can impair the function of nasal-associated lymphoid tissue (NALT) and result in olfactory dysfunction. Exploring the causative alterations of T2DM within the nasal mucosa and NALT could provide insight into the pathogenic mechanisms and bridge the gap between innate immunity and adaptive immunity for virus clearance. Here, we designed a case-control study to compare the olfactory function (OF) among the groups of normal control (NC), COVID-19 mild pneumonia (MP), and MP patients with T2DM (MPT) after a 6-8 months' recovery, in which MPT had a higher risk of hyposmia than MP and NC. No significant difference was found between the MP and NC. This elevated risk of hyposmia indicated that T2DM increased COVID-19 susceptibility in the nasal cavity with unknown causations. Therefore, we used the T2DM animal model (db/db mice) to evaluate how T2DM increased COVID-19 associated susceptibilities in the nasal mucosa and lymphoid tissues. Db/db mice demonstratedupregulated microvasculature ACE2 expression and significant alterations in lymphocytes component of NALT. Specifically, db/db mice NALT had increased immune-suppressive TCRγδ+ CD4-CD8- T and decreased immune-effective CD4+/CD8+ TCRß+ T cells and decreased mucosa-protective CD19+ B cells. These results indicated that T2DM could dampen the first-line defense of nasal immunity, and further mechanic studies of metabolic damage and NALT restoration should be one of the highest importance for COVID-19 healing.
Subject(s)
Anosmia/immunology , Anosmia/virology , COVID-19/immunology , Diabetes Mellitus, Type 2/immunology , Diabetes Mellitus, Type 2/virology , Adult , Angiotensin-Converting Enzyme 2/metabolism , Animals , Anosmia/metabolism , B-Lymphocytes/immunology , COVID-19/metabolism , COVID-19/physiopathology , Case-Control Studies , Diabetes Mellitus, Type 2/metabolism , Female , Humans , Immunity, Mucosal/immunology , Lymphoid Tissue/immunology , Macrophages/immunology , Male , Mice , Mice, Inbred C57BL , Middle Aged , Models, Animal , Nasal Mucosa/immunology , Olfactory Mucosa/metabolism , Risk Factors , SARS-CoV-2/isolation & purification , Serine Endopeptidases/metabolism , T-Lymphocytes/immunologyABSTRACT
The novel coronavirus SARS-CoV-2 is the causative agent of the global coronavirus disease 2019 (COVID-19) outbreak. In addition to pneumonia, other COVID-19-associated symptoms have been reported, including loss of smell (anosmia). However, the connection between infection with coronavirus and anosmia remains enigmatic. It has been reported that defects in olfactory cilia lead to anosmia. In this Viewpoint, we summarize transmission electron microscopic studies of cilia in virus-infected cells. In the human nasal epithelium, coronavirus infects the ciliated cells and causes deciliation. Research has shown that viruses such as influenza and Sendai attach to the ciliary membrane. The Sendai virus enters cilia by fusing its viral membrane with the ciliary membrane. A recent study on SARS-CoV-2-human protein-protein interactions revealed that the viral nonstructural protein Nsp13 interacts with the centrosome components, providing a potential molecular link. The mucociliary escalator removes inhaled pathogenic particles and functions as the first line of protection mechanism against viral infection in the human airway. Thus, future investigation into the virus-cilium interface will help further the battle against COVID-19.