Obesity is a complex health condition defined by the World Health Organization (WHO) as an excess of body weight that may be harmful to health. It leads to other diseases such as type 2 diabetes or cardiovascular diseases, commonly referred to as "co-morbidities." Among these, it is known that obesity increases the risk of developing infectious diseases and of these diseases progressing to severe stages.
During the COVID-19 pandemic and the 2009 H1N1 influenza epidemic, a rise in severe infection cases was observed in people with obesity. A part of people with obesity exhibits certain markers on the surface of their immune cells, which are known to cause immunosuppression when present in high numbers, thus increasing the risk of developing infectious diseases.
Investigator teams found that after bariatric surgery and a calorie-restricted diet for weight loss, patients with obesity can improve the levels of these immunity-related markers. Moreover, the choice of foods consumed contributes to strengthening the immune system and immune functions of individuals, both directly by influencing inflammation and indirectly through the microbiota. However, to date, there are no dietary recommendations specifically designed to help people with obesity improve their immune response.
Therefore, this study aims to compare different dietary recommendations intended to improve immune status, with or without calorie restriction, during 3 months, in individuals with obesity (BMI ≥ 30 kg/m²) and impaired immunity. Over 6 months (3 months of nutritional intervention and 3 months of follow-up), investigators will collect extensive information through biological samples, measurements and questionnaires to compare the different dietary interventions studied and to understand the mechanisms behind the results obtained.
30≤BMI<40 kg/m2
Waist circumference ≥80 cm for women and ≥94 cm for men
High-sensitive CRP (hsCRP) ≥ 3 mg/L
Low diet quality: E-DII > 0, indicating a pro-inflammatory dietary potential
Major mental disorders
Severe eating disorders based on detailed medical history, clinical examination and expertise of the investigating physician, trained in nutrition.
The use of medication or physical conditions interfering with the study outcomes, at the discretion of the investigating physician
Infectious episode in the month prior to inclusion
Parallel
Mixed test meal
Other interventionA mixed test meal, rich in glucose and lipids will be served to the participant during baseline, 3 months and 6 months visits. The participant will have 10 minutes to eat it, and then blood will be sampled during the 4 hours following ingestion of the meal-test. The test meal must be consumed within 10 minutes in order to ensure standardized ingestion conditions between individuals and to limit biases linked to different ingestion times, which could subsequently alter the kinetics of biomarkers measured following meal ingestion. This will allow us to describe the postprandial excursions in glucose, triglycerides and insulin with indicators of the curve as amplitude, pick or time to return to baseline. These indicators are early markers of cardio-metabolic risk alterations. A biobanking of samples is also performed.
Biological sampling
Biological/VaccineChanges in biological parameters will be assessed based on samples collected before the baseline, 3-month and 6-month visits (maximum 2 days before each visit) for feces, and during visits for blood and adipose tissue.
Questionnaires
BehavioralIn order to assess some of the secondary outcomes, participants will be asked to fill in the following questionnaires : 3 24h-recall and validated Food Frequency questionnaire (FFQ), TEFQ, Baecke, Bristol, GSRS, SF12, IWQOL, PSS, PHQ-9, GSES, PSQI, MAUQ and CSQ-8.
Caloric restriction
Other interventionParticipants will be placed on a calorie-restricted diet with a reduction of 500 kcal/day (calculated based on total energy requirement) during 3 months. The calories reduction will be proportional across all food groups, except for fruits and vegetables, for which intake will remain unchanged.
Balanced-immunity diet
Other interventionThe intervention consists of delivering the diet previously defined as the "Balanced-Immunity" diet in the form of meal plan and menus, accessible via TOUVA, a dedicated application during 3 months.
Comparison of changes in the percentage of PD-1⁺ CD4⁺ T cells in peripheral blood mononuclear cells between baseline and after 3 month of nutritional intervention
The first endpoint will be evaluated by calculating the change (Δ) in the percentage of PD-1⁺ CD4⁺ T cells between baseline and month 3 to determine the effect of each nutritional intervention. PBMCs will be isolated from peripheral blood samples locally in each center and then analyzed, centralized by flow cytometry to quantify the percentage of PD-1⁺ CD4⁺ T cells.
Comparison of changes in the percentage of PD-1⁺ CD4⁺ T cells in peripheral blood mononuclear cells between baseline and after 3 month of nutritional intervention and 3 month of follow-up
The endpoint will be evaluated by calculating the change (Δ) in the percentage of PD-1⁺ CD4⁺ T cells between baseline and month 6. Group comparisons will be based on these changes (Δ values) to determine the effect of each nutritional intervention. PBMCs will be isolated from peripheral blood samples locally in each center and then analyzed, centralized by flow cytometry to quantify the percentage of PD-1⁺ CD4⁺ T cells.
Comparison of immune cell phenotyping at baseline, month 3 and month 6 in peripheral blood mononuclear cells between the nutritional interventions
The endpoint will be evaluated by calculating the change (Δ) in cell phenotyping between baseline and month 3, baseline and month 6 and month 3 and month 6 to determine the effect of each nutritional intervention. PBMCs will be isolated from peripheral blood samples locally in each center and then analyzed, centralized by flow and mass cytometry.
Comparison of immune checkpoint proteins at baseline, month 3 and month 6 in peripheral blood mononuclear cells between the nutritional interventions
The endpoint will be evaluated by calculating the change (Δ) in immune checkpoint proteins between baseline and month 3 and baseline and month 6 to determine the effect of each nutritional intervention. PBMCs will be isolated from peripheral blood samples locally in each center and then analyzed, centralized by flow cytometry and mass cytometry
Comparison of concentration of immunoglobulines G (IgG) in serum at baseline, month 3 and month 6 between the nutritional interventions
The endpoint will be evaluated by calculating the change (Δ) in the concentration of Immunoglobulines G in serum between baseline and month 3 and baseline and month 6. Group comparisons will be based on these changes (Δ values) to determine the effect of each nutritional intervention.
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Institut National de la Santé Et de la Recherche Médicale, France
Lead sponsor
Amsterdam UMC, location VUmc
Collaborator
University of Hohenheim
Collaborator
University of Bern
Collaborator
Leibniz Institute for Natural Product Research and Infection Biology Hans Knöll Institute
Collaborator
Integrative Phenomics
Collaborator
Sorbonne University
Collaborator
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