Intra-nasal zinc level relationship to COVID-19 anosmia and type 1 interferon response: A proposal

A Comprehensive Review of COVID-19-Related Olfactory Deficiency: Unraveling Associations with Neurocognitive Disorders and Magnetic Resonance Imaging Findings

Olfactory dysfunction (OD) is one of the most common symptoms in COVID-19 patients and can impact patients' lives significantly. The aim of this review was to investigate the multifaceted impact of COVID-19 on the olfactory system and to provide an overview of magnetic resonance (MRI) findings and neurocognitive disorders in patients with COVID-19-related OD. Extensive searches were conducted across PubMed, Scopus, and Google Scholar until 5 December 2023. The included articles were 12 observational studies and 1 case report that assess structural changes in olfactory structures, highlighted through MRI, and 10 studies correlating the loss of smell with neurocognitive disorders or mood disorders in COVID-19 patients. MRI findings consistently indicate volumetric abnormalities, altered signal intensity of olfactory bulbs (OBs), and anomalies in the olfactory cortex among COVID-19 patients with persistent OD. The correlation between OD and neurocognitive deficits reveals associations with cognitive impairment, memory deficits, and persistent depressive symptoms. Treatment approaches, including olfactory training and pharmacological interventions, are discussed, emphasizing the need for sustained therapeutic interventions. This review points out several limitations in the current literature while exploring the intricate effects of COVID-19 on OD and its connection to cognitive deficits and mood disorders. The lack of objective olfactory measurements in some studies and potential validity issues in self-reports emphasize the need for cautious interpretation. Our research highlights the critical need for extensive studies with larger samples, proper controls, and objective measurements to deepen our understanding of COVID-19's long-term effects on neurological and olfactory dysfunctions.

Persistent and transient olfactory deficits in COVID-19 are associated to inflammation and zinc homeostasis

Introduction

The Coronavirus Disease 2019 (COVID-19) is mainly a respiratory syndrome that can affect multiple organ systems, causing a variety of symptoms. Among the most common and characteristic symptoms are deficits in smell and taste perception, which may last for weeks/months after COVID-19 diagnosis owing to mechanisms that are not fully elucidated.

Methods

In order to identify the determinants of olfactory symptom persistence, we obtained olfactory mucosa (OM) from 21 subjects, grouped according to clinical criteria: i) with persistent olfactory symptoms; ii) with transient olfactory symptoms; iii) without olfactory symptoms; and iv) non-COVID-19 controls. Cells from the olfactory mucosa were harvested for transcriptome analyses.

Results and discussion

RNA-Seq assays showed that gene expression levels are altered for a long time after infection. The expression profile of micro RNAs appeared significantly altered after infection, but no relationship with olfactory symptoms was found. On the other hand, patients with persistent olfactory deficits displayed increased levels of expression of genes involved in the inflammatory response and zinc homeostasis, suggesting an association with persistent or transient olfactory deficits in individuals who experienced SARS-CoV-2 infection.

Drug-induced olfactory and gustatory dysfunction: Analysis of FDA adverse events reporting system

OBJECTIVES

With the COVID-19 pandemic, there is growing interest and research in olfactory and gustatory dysfunction (OGD). Drug-induced dysfunction is an often overlooked etiology. While several medications include smell or taste disturbance as a side effect, there are no publications describing which medications are most frequently implicated. We aim to describe the patterns of these adverse drug reactions (ADRs) using the FDA Adverse Events Reporting System (FAERS).

METHODS

The FAERS database was queried from 2011 to 2021 for terms describing ADRs related to OGD. Terms included anosmia, hyposmia, olfactory test abnormal, olfactory nerve disorder, hallucination olfactory, parosmia, ageusia, hypogeusia, dysgeusia, and taste disorder. We identified the top reported medications associated with general smell dysfunction, general taste dysfunction, reduced smell, and altered smell.

RESULTS

From 2011 to 2021, 16,091 ADRs were reported with OGD, of which13,641 (84.8%) and 2,450 (15.2%) were associated with gustatory and olfactory reactions, respectively. Zinc products (370 reports) and fluticasone propionate (214) were most commonly associated with olfactory dysfunction, specifically reduced olfaction. Varenicline (24) and fluticasone propionate (23) were most commonly associated with altered smell. Lenalidomide (490) and sunitinib (468) were most commonly associated with gustatory dysfunction. Antineoplastic and immunomodulating medications accounted for 21.6% and 36.3% of olfactory and gustatory ADRs, respectively. Among this category, immunoglobulin drugs were the most commonly associated with OGD ADRs.

CONCLUSION

Gustatory dysfunction is more commonly reported ADR compared with olfactory dysfunction. Immunologic/rheumatologic medications are the leading culprit of reported OGD. With increasing numbers of patients presenting to otolaryngologists for OGD, it is important to consider drug-induced etiology.

LEVEL OF EVIDENCE

III.

Zinc pyrithione is a potent inhibitor of PLPro and cathepsin L enzymes with ex vivo inhibition of SARS-CoV-2 entry and replication

Zinc pyrithione (1a), together with its analogues 1b–h and ruthenium pyrithione complex 2a, were synthesised and evaluated for the stability in biologically relevant media and anti-SARS-CoV-2 activity. Zinc pyrithione revealed potent in vitro inhibition of cathepsin L (IC₅₀=1.88 ± 0.49 µM) and PL^Pro (IC₅₀=0.50 ± 0.07 µM), enzymes involved in SARS-CoV-2 entry and replication, respectively, as well as antiviral entry and replication properties in an ex vivo system derived from primary human lung tissue. Zinc complexes 1b–h expressed comparable in vitro inhibition. On the contrary, ruthenium complex 2a and the ligand pyrithione a itself expressed poor inhibition in mentioned assays, indicating the importance of the selection of metal core and structure of metal complex for antiviral activity. Safe, effective, and preferably oral at-home therapeutics for COVID-19 are needed and as such zinc pyrithione, which is also commercially available, could be considered as a potential therapeutic agent against SARS-CoV-2.

Signs and symptoms of Covid‐19 in patients with multiple sclerosis

Background and purpose

Clinical outcomes of multiple sclerosis (MS) patients affected by coronavirus disease 2019 (COVID‐19) have been thoroughly investigated, but a further analysis on main signs and symptoms and their risk factors still needs attention. The objective of this study was to group together and describe based on similarity the most common signs and symptoms of COVID‐19 in MS patients and identify all factors associated with their manifestation.

Method

Logistic and linear regression models were run to recognize factors associated with each pooled group of symptoms and their total number.

Results

From March 2020 to November 2021, data were collected from 1354 MS patients with confirmed infection of COVID‐19. Ageusia and anosmia was less frequent in older people (odds ratio [OR] 0.98; p = 0.005) and more in smoker patients (OR 1.39; p = 0.049). Smoke was also associated with an incremental number of symptoms (OR 1.24; p = 0.031), substance abuse (drugs or alcohol), conjunctivitis and rash (OR 5.20; p = 0.042) and the presence of at least one comorbidity with shortness of breath, tachycardia or chest pain (OR 1.24; p = 0.008). Some disease‐modifying therapies were associated with greater frequencies of certain COVID‐19 symptoms (association between anti‐CD20 therapies and increment in the number of concomitant symptoms: OR 1.29; p = 0.05). Differences in frequencies between the three waves were found for flu‐like symptoms (G1, p = 0.024), joint or muscle pain (G2, p = 0.013) and ageusia and anosmia (G5, p < 0.001). All cases should be referred to variants up to Delta.

Conclusion

Several factors along with the choice of specific therapeutic approaches might have a different impact on the occurrence of some COVID‐19 symptoms.

Potential pharmacologic treatments for COVID-19 smell and taste loss: A comprehensive review

The acute loss of taste and smell following COVID-19 are hallmark symptoms that affect 20-85% of patients. However, the pathophysiology and potential treatments of COVID-19 smell and taste loss are not fully understood. We searched the literature to review the potential pathologic pathways and treatment options for COVID-19 smell and taste loss. The interaction of novel coronavirus with ACE-2 receptors expressed on sustentacular cells and taste buds results in direct damage to the olfactory and gustatory systems. Also, the invasion of the virus to the olfactory neurons and consequent local inflammation are other proposed mechanisms. Therefore, COVID-19 patients with smell or taste loss may benefit from neuroprotective, anti-inflammatory, or depolarizing agents. Based on the current evidence, phosphodiesterase inhibitors, insulin, and corticosteroids can be promising for the management of COVID-19 smell and taste loss. This review provided crucial information for treating COVID-19-related smell and/or taste loss, urging to perform large clinical trials to find optimum treatment options.

Pathophysiology and possible treatments for olfactory-gustatory disorders in patients affected by COVID-19

SARS-CoV-2 infects host cells mainly through the interaction between the virus's Spike protein and the viral receptors namely Angiotensin-Converting Enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2). Both are highly expressed in the gastrointestinal tract, in the nasal and bronchial epithelium, as well as in the type II alveolar epithelial cells. The aim of this review is to report the evidences from the scientific literature on the pathophysiology and the available treatments for olfactory-gustatory disorders in patients with COVID-19. The mechanisms involved in these disorders are still unclear and studies on specific therapies are scarce. However, it has been hypothesized that a decrease in the sensitivity of the sensory neurons as well as the co-expression of ACE2 and TMPRSS2 in the alveolar epithelial cells are the main causes of olfactory-gustatory disorders. The possible mechanisms described in the literature for changes in taste perception in patients with COVID-19 include olfactory disorders and a competitive activity of COVID-19 on ACE2 receptors in the taste buds. In addition, SARS-CoV-2 can bind to sialic acid receptors in the taste buds. In general, evidences show that there is no specific treatment for olfactory-taste disorders induced by SARS-CoV-2, even though some treatments have been used and have shown some promising results, such as olfactory training, intranasal application of sodium citrate and vitamin A, as well as systemic use of omega-3 and zinc. Corticosteroids have also been used as a pharmacological approach to treat patients with olfactory dysfunction with some contradictory results. The knowledge of the mechanisms by which SARS-CoV-2 influences the sensory systems and how effective therapies can treat the loss of smell and taste will have important implications on the understanding and clinical management of olfactory-taste disorders.