Assessment of the relationship between circulating bile acid levels and leucocyte function in the the postprandial period

• Grant number: 24/12307-8
• Support Opportunities: Scholarships in Brazil - Support Program for Fixating Young Doctors
• Start date: August 01, 2024
• End date: July 31, 2025
• Field of knowledge: Biological Sciences - Biochemistry - Metabolism and Bioenergetics
• Agreement: CNPq
• Principal Investigator: Jarlei Fiamoncini
• Grantee: Vinicius Leonardo Sousa Diniz
• Host Institution: Faculdade de Ciências Farmacêuticas (FCF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 24/02071-7 - Assessment of the relationship between circulating bile acid levels and leucocyte function in the the postprandial period, AP.R

Abstract

Physiological processes involved in food digestion and metabolic adaptations to the newly available energy substrates are observed in the postprandial period. During this period, a transient inflammatory response is observed, characterized by an increase in the number of circulating leukocytes, changes in their gene expression and an increase in plasma levels of inflammatory cytokines. The regulatory mechanisms and causes involved in postprandial inflammation are not yet completely elucidated. Plasma levels of bile acids (BA) increase up to 20 times after the ingestion of a meal. In addition to their role in emulsifying dietary lipids, BA acts as signaling molecules, with dedicated receptors in various cell types. In preclinical studies, BA presented anti-inflammatory activity and modulated carbohydrate and lipid metabolism. Despite recognized anti-inflammatory effects, the relationship between plasma levels of BA and postprandial inflammation remains unknown. In this study, we will investigate the relationship between the postprandial increase in plasma levels of BA and metabolic and inflammatory changes that occur after food intake. The project will be divided into three steps: in vitro experiments, and clinical trial phase 1 and 2. In the in vitro experiments, we will analyze the effect of BA on inflammatory and energetic parameters of of lymphocyte and macrophage cell lines - Jurkat and RAW 264.7. We will perform the toxicity test, analysis of gene expression of inflammatory parameters and analysis of the metabolism of these cells using the Seahorse technology (Agilent Technologies). In the clinical trial Phase 1, 100 adult women will be subjected to a simplified dietary challenge with the purpose of verifying the kinetics of the appearance of AB in plasma, in the postprandial period. At this step, 6 samples of capillary blood will be collected within 5 hours and the kinetics of the appearance of BA in plasma will be assessed using mass spectrometry. This step will be important to select the 20 participants with the highest and 20 participants with the lowest appearance of BA in plasma, during the postprandial period, who will be recruited for Phase 2 of the clinical trial. In Phase 2, we will evaluate the effect of the appearance of BA in plasma on leukocyte function. For this, 40 participants selected during Phase 1 of the study, will go through another dietary challenge in order to draw venous blood, for 6 hours, to obtain plasma and leukocytes. Plasma markers of inflammation and intermediary metabolism will be quantified using enzymatic methods. In leukocytes, we will evaluate the gene expression of inflammation markers, identification of lymphocyte profile by flow cytometry, analysis of signaling pathways related to the TLR4 and NLRP3 inflammasome by the Western Blotting method and carry out untargeted metabolomic analysis. Understanding the mechanisms that control postprandial inflammation in women is extremely important, as this phenomenon is associated with the development of diseases such as atherosclerosis, for which postmenopausal women are at greater risk. (AU)