Symposium overview: Impact of oronasal inflammation on taste and smell

Determination of objective taste perception among Iranian medical sciences students during COVID‑19 pandemic in Yazd, Eastern Iran: a case-control pilot study

BACKGROUND

Taste disorders in patients suffering from COVID-19 were popular. Some people even after recovery report residual effects of loss of smell and taste. This study aimed to investigate the taste Perception of Iranian Medical Sciences students during the COVID-19 pandemic.

METHODS

The case-control study evaluated 50 Medical Sciences students with a history of COVID-19 infection, as confirmed by the Novel Coronavirus (2019-nCOV) CFX96™ Real-Time PCR Detection System. The other participants consisted of 50 volunteer students with COVID-19 negative. The taste perception was measured with 4 different concentrations of the basic tastes. The stimuli were applied to the protruded tongue. Subjects were asked to identify the researcher when they felt the taste. Data are expressed as frequency distribution and analyzed with the Chi-Square test (P < 0.05).

RESULTS

In this survey, 54% of participants were male and 46% were female, the mean age of participants was 22.96 ± 5 years. The results showed a significant difference in the sweet and bitter taste perception score according to the history of dietary supplement use. The bitter taste perception score declared a considerable difference since COVID-19 infection. There was no significant difference between the taste perception in the two studied groups for all 4 basic tastes according to gender, COVID-19 infection status, history of taste and smell disorders, and the elapsed time since COVID-19 infection.

CONCLUSION

Our findings could provide important insights into taste perception. The history of dietary supplementation may influence how sweetness and saltiness are perceived. There was a noticeable difference in bitter taste perception depending on the time that had elapsed since the most recent COVID-19 infection.

Effects of Intranasal and Oral Bordetella bronchiseptica Vaccination on the Behavioral and Olfactory Capabilities of Detection Dogs

The bacterium Bordetella bronchiseptica is responsible for serious respiratory disease in dogs, most often associated with ‘kennel cough’ (canine infectious tracheobronchitis). It is recommended that dogs are vaccinated against the bacterium every 6–12 months, either by oral or intranasal administration. Any impairment of dogs' olfactory capabilities due to medical treatments may impact their efficiency and accuracy in their jobs. This study examined (1) the effect of intranasal and oral vaccines on the olfactory capabilities of detection dogs; as well as (1) effects of the vaccines on canine behavior. Dogs that were vaccinated initially with the oral and 28 days later with intranasal B. bronchiseptica were generally slower to find the target odor than the dogs that were assigned intranasal then oral vaccine. This result prompted a second between-subjects study to further investigate any impact of intranasal administration of the B. bronchiseptica vaccine on the olfactory capabilities of dogs. The intranasal vaccine was of particular interest due to its prevalent use and potential for nasal inflammation leading to decreased olfactory capabilities. Neither odor threshold nor time spent searching for odor were affected by the intranasal vaccine. Behavioral analyses showed that behaviors associated with the dogs' positive and negative motivation affected their time spent finding the target odor; this suggests that behavior should be considered in future studies of olfactory performance.

COVID-19 related chemosensory changes in individuals with self-reported obesity

BACKGROUND/OBJECTIVES

Self-reported smell loss is a prominent symptom of COVID-19 infection and a potentially useful clinical tool for remote pre-screening of this disease. However, pre-existing chemosensory dysfunction with obesity may diminish the usefulness of self-reported smell loss in this vulnerable group. Here we aim to compare COVID-19 related chemosensory alterations in participants with and without obesity and determine if self-reported smell loss is predictive of lab-based COVID-19 diagnosis in both groups in the context of restrictive clinical data collection.

SUBJECTS/METHODS

In this secondary analysis of a cross-sectional global dataset, we compared self-reported chemosensory ability in participants with a respiratory illness reporting a positive (C19+; n = 5156) or a negative (C19-; n = 659) COVID-19 laboratory test outcome, who also self-reported to have obesity (C19+; n = 433, C19-; n = 86) or not.

RESULTS

Participants with obesity and without obesity reported a similar decline in smell, taste, and chemesthesis during illness. In C19+ participants with obesity, we observed a greater relative prevalence of non-chemosensory symptoms, including respiratory and GI symptoms. Critically, we found that the model previously proposed also predicts C19+ diagnosis in participants with obesity.

CONCLUSIONS

We conclude that COVID-19 respondents with obesity experience a similar self-reported chemosensory loss as those without obesity. In both groups self-reported chemosensory symptoms are similarly predictive of COVID-19 infection, thus highlighting the potential of collecting self-report of symptoms and comorbidities remotely when clinical observations are restrictive.

Acute SARS-CoV-2 infection is associated with an increased abundance of bacterial pathogens, including Pseudomonas aeruginosa in the nose

Research conducted on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pathogenesis and coronavirus disease 2019 (COVID-19) generally focuses on the systemic host response, especially that generated by severely ill patients, with few studies investigating the impact of acute SARS-CoV-2 at the site of infection. We show that the nasal microbiome of SARS-CoV-2-positive patients (CoV⁺, n = 68) at the time of diagnosis is unique when compared to CoV⁻ healthcare workers (n = 45) and CoV⁻ outpatients (n = 21). This shift is marked by an increased abundance of bacterial pathogens, including Pseudomonas aeruginosa, which is also positively associated with viral RNA load. Additionally, we observe a robust host transcriptional response in the nasal epithelia of CoV⁺ patients, indicative of an antiviral innate immune response and neuronal damage. These data suggest that the inflammatory response caused by SARS-CoV-2 infection is associated with an increased abundance of bacterial pathogens in the nasal cavity that could contribute to increased incidence of secondary bacterial infections.

Quantitative analysis of taste disorder in COVID-19 patients, the hypersensitivity to salty quality

Recently, many of the studies have illustrated that the new pandemic SARS-CoV-2 can affect Central Nervous System through the olfactory bulb. In addition to investigating anosmia or hyposmia induced by this virus, a quantitative analysis was needed to clarify the taste and smell disorder of the new coronavirus. The four basic taste quality with five concentrations for sweet, sour, bitter, and salty were administered to 75 subjects divided into three groups: COVID-19 patients with taste disorder, COVID-19 patients without taste disorder, and control group.

The results indicated the increment of sweet (2.68 ± 0.14), sour (3.34 ± 0.12) and bitter (3.39 ± 0.2) thresholds in COVID-19 patients with taste disorder in comparison with patients without taste disorder that the threshold were: 2 ± 0.16, 2.11 ± 0.2 and 2.55 ± 0.5 for sweet, sour, and bitter respectively. On the other hand, the patients inversely showed a significant decrease in the salty taste threshold (0.51 ± 0.03) compared to COVID-19 positive control groups (1.11 ± 0.11).

Additionally, despite taste disorder in almost all of the patients with smell deficiency, only 30% of cases with taste disorder reported smell deficiency. It may be concluded that some of the taste disorders in patients with COVID-19 disorder could be associated with taste receptors dysfunction or the spread of infection to the cranial nerves responsible for the conduction of tastes sensation.

Effects of a 2-Week 5000 IU versus 1000 IU Vitamin D3 Supplementation on Recovery of Symptoms in Patients with Mild to Moderate Covid-19: A Randomized Clinical Trial

OBJECTIVE

Vitamin D deficiency has been associated with an increased risk of COVID-19 severity. This multi-center randomized clinical trial aims to determine the effects of 5000 IU versus 1000 IU daily oral vitamin D3 supplementation in the recovery of symptoms and other clinical parameters among mild to moderate COVID-19 patients with sub-optimal vitamin D status.

STUDY DESIGN AND SETTING

A total of 69 reverse transcriptase polymerase chain reaction (RT-PCR) SARS-CoV-2 positive adults who were hospitalized for mild to moderate COVID-19 disease were allocated to receive once daily for 2 weeks either 5000 IU oral vitamin D3 (n = 36, 21 males; 15 females) or 1000 IU oral vitamin D3 (standard control) (n = 33, 13 males; 20 females). Anthropometrics were measured and blood samples were taken pre- and post-supplementation. Fasting blood glucose, lipids, serum 25(OH)D, and inflammatory markers were measured. COVID-19 symptoms were noted on admission and monitored until full recovery.

RESULTS

Vitamin D supplementation for 2 weeks caused a significant increase in serum 25(OH)D levels in the 5000 IU group only (adjusted p = 0.003). Within-group comparisons also showed a significant decrease in BMI and IL-6 levels overtime in both groups (p-values < 0.05) but was not clinically significant in between-group comparisons. Kaplan-Meier survival analysis revealed that the 5000 IU group had a significantly shorter time to recovery (days) than the 1000 IU group in resolving cough, even after adjusting for age, sex, baseline BMI, and D-dimer (6.2 ± 0.8 versus 9.1 ± 0.8; p = 0.039), and ageusia (loss of taste) (11.4 ± 1.0 versus 16.9 ± 1.7; p = 0.035).

CONCLUSION

A 5000 IU daily oral vitamin D3 supplementation for 2 weeks reduces the time to recovery for cough and gustatory sensory loss among patients with sub-optimal vitamin D status and mild to moderate COVID-19 symptoms. The use of 5000 IU vitamin D3 as an adjuvant therapy for COVID-19 patients with suboptimal vitamin D status, even for a short duration, is recommended.

Acute SARS-CoV-2 infection is associated with an expansion of bacteria pathogens in the nose including Pseudomonas Aeruginosa

Much of the research conducted on SARS-CoV-2 and COVID-19 has focused on the systemic host response, especially that generated by severely ill patients. Very few studies have investigated the impact of acute SARS-CoV-2 within the nasopharynx, the site of initial infection and viral replication. In this study we profiled changes in the nasal microbial communities as well as in host transcriptional profile during acute SARS-CoV-2 infection using 16S amplicon sequencing and RNA sequencing. These analyses were coupled to viral genome sequencing. Our microbiome analysis revealed that the nasal microbiome of COVID patients was unique and was marked by an expansion of bacterial pathogens. Some of these microbes (i.e. Acinetobacter ) were shared with COVID negative health care providers from the same medical center but absent in COVID negative outpatients seeking care at the same institutions suggesting acquisition of nosocomial respiratory pathogens. Specifically, we report a distinct increase in the prevalence and abundance of the pathogen Pseudomonas aeruginosa in COVID patients that correlated with viral RNA load. These data suggest that the inflammatory environment caused by SARS-CoV-2 infection and potentially exposure to the hospital environment leads to an expansion of bacterial pathogens in the nasal cavity that could contribute to increased incidence of secondary bacterial infections. Additionally, we observed a robust host transcriptional response in the nasal epithelia of COVID patients, indicative of an antiviral innate immune repones and neuronal damage. Finally, analysis of viral genomes did not reveal an association between viral loads and viral sequences.

Perceived Intensity and Palatability of Fatty Culinary Preparations is Associated with Individual Fatty Acid Detection Threshold and the Fatty Acid Profile of Oils Used as Ingredients

The term oleogustus was recently proposed to describe a sixth basic taste that could guide preference for fatty foods and dishes to an extent. However, experimental data on food preference based on fatty acid (FA) content is scarce. Our aim was to examine the role of FA profile of oils and preparations as well as FA sensory thresholds on the palatability of salty and sweet culinary preparations representative of traditional Spanish Mediterranean cooking. In this study, we used three oils with similar texture and odor profile but different in their FA composition (saturated, monounsaturated, and polyunsaturated) and compared subjects in regard to their FA detection threshold and perceived pleasantness and intensity. Our results indicate that whereas saturated FAs cannot be detected at physiological concentrations, individuals can be categorized as tasters and nontasters, according to their sensory threshold to linoleic acid, which is negatively associated with perceived intensity (r = -0.393, P < 0.001) but positively with palatability (r = 0.246, P = 0.018). These differences may be due to a possible response to a fat taste. This sixth taste, or oleogustus. would allow establishing differences in taste intensity/palatability considering the FA profile of the culinary preparations. Given that tasters can detect linoleic and oleic acid at lower concentrations than nontasters, a greater amount of unsaturated FAs in culinary preparations could provoke an unpleasant experience. This finding could be relevant in the context of the culinary sector and to further our understanding of food preference and eating behavior.

COVID-19 Related Chemosensory Changes in Individuals with Self-Reported Obesity

BACKGROUND/OBJECTIVES

Individuals with obesity show alterations in smell and taste abilities. Smell and taste loss are also the most prominent neurological symptoms of COVID-19, yet how chemosensory ability present in individuals with obesity with a positive COVID-19 diagnosis is unknown.

SUBJECTS/METHODS

In this secondary analysis of a cross-sectional global dataset, we compared self-reported chemosensory ability in participants with a respiratory illness reporting a positive (C19+; n = 5156) or a negative (C19-; n = 659) COVID-19 laboratory test outcome, who also self-reported to be obese (C19+; n = 433, C19-; n = 86) or non-obese.

RESULTS

Compared to the C19- group, C19+ exhibited a greater decline in smell, taste, and chemesthesis during illness, though these symptoms did not differ between participants with obesity and without obesity. In 68% of participants who reported recovery from respiratory illness symptoms (n=3431 C19+ and n= 539 C19-), post-recovery chemosensory perception did not differ in C19+ and C19- diagnosis, and by self-reported obesity. Finally, we found that all chemosensory and other symptoms combined predicted the C19+ diagnosis in participants with obesity with a moderately good estimate (63% accuracy). However, in C19+ participants with obesity, we observed a greater relative prevalence of non-chemosensory symptoms, including respiratory as respiratory and GI symptoms.

CONCLUSIONS

We conclude that despite a presumed lower sensitivity to chemosensory stimuli, COVID-19 respondents with obesity experience a similar self-reported chemosensory loss as those without obesity, and in both groups self-reported chemosensory symptoms are similarly predictive of COVID-19.

Lipopolysaccharide-Induced Inflammatory Cytokine Expression in Taste Organoids

Inflammatory cytokines are signaling molecules that regulate numerous physiological processes, from tissue homeostasis to metabolism and food intake. Expression of certain cytokines can be markedly induced in subsets of taste bud cells under acute and chronic inflammation. This may contribute to altered taste perception and preference associated with many diseases. Although the pathways of cytokine induction are well studied in immune cells, they remain poorly characterized in taste cells, in part due to the difficulties of performing biochemical analyses with a limited number of taste cells. The recently developed taste organoid model provides an opportunity to carry out these mechanistic studies in vitro. However, it was unknown whether taste organoids respond to inflammatory stimuli as do in vivo native taste buds. Here we analyze lipopolysaccharide (LPS)-induced expression and secretion of two inflammatory cytokines, tumor necrosis factor (TNF), and interleukin-6 (IL-6). We show that, similarly to native mouse taste epithelia, organoids derived from mouse circumvallate stem cells express several toll-like receptors (TLRs), including TLR4-the primary receptor for LPS. Organoids and native taste epithelia express all five genes in the nuclear factor-κb (Nfkb) family that encode the transcription factor NF-κB, a critical regulator of inflammatory responses. LPS stimulates fast induction of TNF and IL-6 with similar induction kinetics in organoids and native taste epithelia. These results show that taste epithelial cells possess necessary components for inflammatory cytokine induction and secretion and suggest that the organoid model can be a useful tool to dissect the underlying mechanisms.