The Obese Taste Bud Study

Study Overview
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Brief Summary
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The sense of taste is essential for priming food preferences and is therefore important for caloric uptake and body weight regulation. Recent studies show that obesity is linked to changes in taste sensation but also to a loss of taste buds on the tongue. This study aims to evaluate underlying mechanisms within the taste buds to potentially influence the sense of taste on the level of these sensory cells and in order to develop new treatment strategies to fight obesity.

Official Title
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The Obese Taste Bud Study

Conditions
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Obesity

Intervention / Treatment
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* Procedure: taste bud biopsy
* Diagnostic Test: oral glucose tolerance test
* Diagnostic Test: Taste sensitivity
* Diagnostic Test: olfactory function
* Diagnostic Test: taste bud density
* Diagnostic Test: anthropometry
* Other: biospecimen collection
* Other: questionnaires


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: normal weight (BMI 18.5-24.9) obesity (BMI >=30) overall healthy (no severe sickness, no cancer) written informed consent Exclusion Criteria: current pregnancy or currently breastfeeding cancer or tumors state after radiotherapy at head-neck area state after or current chemotherapy severe psychiatric-, cardiac-, kidney- or neurological illness diagnosed diabetes mellitus known dysfunction of smelling or tasting drug or alcohol abuse permanent medication with antidepressants, anticonvulsants, steroids and/or immunosuppressants

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 69 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| normal weight<br>Normal weight adults with BMI ranging from 18.5-24.9; men and women; age range 18-69years; written informed consent | Procedure: taste bud biopsy<br>* Taste buds will be surgically removed a) during a planned and medically induced elective surgery under full anesthesia; b) by local anesthesia in subjects without a medically induced surgery<br>Diagnostic Test: oral glucose tolerance test<br>* 75g glucose will be applied in drinking water following blood sample collection to evaluate glucose, insulin and C-peptide level.<br>Diagnostic Test: Taste sensitivity<br>* Subjects are given taste strips with 4 concentrations per each taste quality of sweet, sour, salty, bitter and umami in a pseudo-randomized manner. Subjects are asked to identify the taste quality, state the intensity, preference and certainty.<br>Diagnostic Test: olfactory function<br>* Subjects will be presented 16 different sniffing sticks in a randomized order, each for about 4seconds. People are then asked to identify the smell by choosing one out of 4 options (forced choice).<br>Diagnostic Test: taste bud density<br>* The number of taste buds on the anterior tongue will be determined by colouring the tongue surface with food colour. Taste buds will apply more reddish as compared to non-taste tissue. Based on a digital photography the number of taste buds per subjects is counted manually.<br>Diagnostic Test: anthropometry<br>* Anthropometric data collection will include measures of body height, body weight, arm-, upper- and lower leg circumferences, waist- and hip circumferences and a bioimpedance analysis to obtain data about body composition.<br>Other: biospecimen collection<br>* Blood and saliva samples will be taken as well as a tongue swab.<br>Other: questionnaires<br>* Through the use of several questionnaires, data about eating behavior, food preferences, life style factors and other will be obtained.<br>|
| obese<br>Subjects with obesity as defined by BMI >= 30; men and women; age range 18-69 years; written informed consent | Procedure: taste bud biopsy<br>* Taste buds will be surgically removed a) during a planned and medically induced elective surgery under full anesthesia; b) by local anesthesia in subjects without a medically induced surgery<br>Diagnostic Test: oral glucose tolerance test<br>* 75g glucose will be applied in drinking water following blood sample collection to evaluate glucose, insulin and C-peptide level.<br>Diagnostic Test: Taste sensitivity<br>* Subjects are given taste strips with 4 concentrations per each taste quality of sweet, sour, salty, bitter and umami in a pseudo-randomized manner. Subjects are asked to identify the taste quality, state the intensity, preference and certainty.<br>Diagnostic Test: olfactory function<br>* Subjects will be presented 16 different sniffing sticks in a randomized order, each for about 4seconds. People are then asked to identify the smell by choosing one out of 4 options (forced choice).<br>Diagnostic Test: taste bud density<br>* The number of taste buds on the anterior tongue will be determined by colouring the tongue surface with food colour. Taste buds will apply more reddish as compared to non-taste tissue. Based on a digital photography the number of taste buds per subjects is counted manually.<br>Diagnostic Test: anthropometry<br>* Anthropometric data collection will include measures of body height, body weight, arm-, upper- and lower leg circumferences, waist- and hip circumferences and a bioimpedance analysis to obtain data about body composition.<br>Other: biospecimen collection<br>* Blood and saliva samples will be taken as well as a tongue swab.<br>Other: questionnaires<br>* Through the use of several questionnaires, data about eating behavior, food preferences, life style factors and other will be obtained.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Identification of differential gene and protein regulation in isolated human taste cells between lean and obese subjects | Transcriptomics (RNAsequencing (seq), single cell seq) and epigenomics (open chromatin mapping (ATACseq), Infinium MethylationEPIC Array) will be performed in isolated papillae fungiformes. Validation analyses by in vitro primary cell cultures of taste cell biopsy | through study completion, an average of 2 years | 
| Identification of correlations between taste cell biology with parameters of intervention | corrleation analyses will include factors of eating behavior, food preferences, life style factors, data from taste and smell screenings, anthropometric data, blood and saliva parameters | 1 year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Differences of salivary and tongue microbiome on taste cells in obesity in contrast to lean | whole mouth saliva as well as local tongue microbiome diversity will be analysed by 16S ribosomal RNA seq and related to further parameters of this study. | 2 years | 
| extracellular vesicle analyses of saliva in lean and obese subjects | The content of extracellular vesicles from saliva samples will be analysed and compared between the study groups as well as related to other parameters of this study. | 2 years | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Obesity, food preferences, taste disorder, taste bud, metabolic disease, feeding behavior