Intake of protein modulate immune function, POMC processing and IGF signaling gene expression pathways in peripheral mononuclear cells in home-dwelling old subjects - a transcriptomic approach

Adequate intake of protein among older adults is associated with better health outcomes, but conflicting results makes it difficult to define the optimal intake. To further understand the impact of protein intake on metabolic processes we studied genome-wide gene expression changes in peripheral blood mononuclear cells (PBMCs) in home-dwelling old subjects after increased protein intake for 12 weeks. This study was a parallel design double blind randomized controlled intervention study. In total fifty home-dwelling men and women with reduced physical strength and/or performance (≥ 70 yrs) were recrutied to the study. Subjects were stratified by gender and smoking into two groups, receiving either a protein-enriched milk (2 x 20 g protein/d) or an isocaloric carbohydrate drink for breakfast and evening meal for 12 weeks. The test drinks were provided by TINE SA and were identical in color, labeling and appearance, and was blinded to both the study participants and the study staff. Participants maintained their normal diet and physical activity levels during the study period. PBMCs were isolated before and after the intervention. mRNA was extracted using RNeasy Mini Kit (Qiagen) and the RNA quantity and quality was meassured using NanoDrop-1000 (NanoDrop Technologies, Inc., Delaware, USA), and Aglient 2100 Bioanalyzer (Agilent Technologies, Inc., California, USA), resepctilvely. Microarray analysis were performed using Illumina technology. Thirty-six subjects finished the study, and five samples were excluded from the final analysis, leaving us with n=14 in the protein group and n=17 in the carbohydrate group.