Proteomic Analysis of Peripheral Blood Mononuclear Cells Following a Single High Fat High Carbohydrate Meal Challenge

Abstract Objectives An individual's ability to adapt to a dynamic environment is termed ‘phenotypic flexibility’ and can be weakened by chronic stress, leading to dysregulation of normal homeostatic processes. A long-term high energy and high fat high carbohydrate (HFHC) diet increases risk of metabolic diseases, however, the acute effect of a single HFHC meal on disturbances in metabolic homeostasis is less understood. In this study, we aimed to characterise the effect of a single HFHC meal on the postprandial proteome of peripheral blood mononuclear cells (PBMCs). Methods Twelve healthy men (22.7 ± 3.4 years, BMI of 22.2 ± 1.5 kg/m2) were recruited. Participants consumed a HFHC milkshake after fasting overnight. The meal contained 16 g of carbohydrate and 15 g of fat per 100 g and had a total energy content of 64 kJ/kg body weight. PBMCs were collected at fasting, 3 and 6 hours following the meal. The proteome was measured via LC-MS/MS using untargeted label-free quantification. Differentially expressed proteins were identified with a modified paired t test (limma, R v.4.0.3). Gene ontology analysis was performed with ClueGO v2.5.7 in Cytoscape v3.8.2. Results After filtering to include only high confident proteins consistently detected in each condition, 6007 proteins were identified and included in analysis. Changes in protein expression relative to fasting were observed at 3 hours (143 proteins) and 6 hours (210 proteins) post meal (fold change > ±1.2, p < 0.05). The most highly altered biological processes observed at each timepoint were ‘zymogen activation’ (GO:0,031,638, 31.25% of groups at 3 hours) and ‘ribosome biogenesis’ (GO:0,042,254, 19.15% of groups at 6 hours). Conclusions These results reveal adaptations that occur in the PBMC proteome in response to a single HFHC meal. Changes to proenzyme activation shows a general response in PBMCs to meal-induced changes in the cellular environment, whilst regulation of ribosome synthesis pathways may reflect changes in energy regulation pathways caused by increased nutrient availability. This study characterises the PBMC response in healthy men, and provides a useful reference for future studies that investigate how PBMCs lose the ability to maintain homeostasis following a HFHC meal. Funding Sources Monash University, Melbourne, Australia