Location: Immunity and Disease Prevention Research
Project Number: 2032-53000-001-14-I
Project Type: Interagency Reimbursable Agreement
Start Date: Feb 1, 2014
End Date: Jan 31, 2018
1) To determine whether dietary saturated fatty acids activate PRRs (TLR4 and NODs) in human. Activation of PRR-mediated signaling pathways by saturated fatty acids has been demonstrated using animal models and cell culture systems. However, direct evidence that dietary saturated fatty acids can activate PRR-mediated proinflammatory pathways in human has not been demonstrated. 2) To determine whether high saturated fat diet-induced monocyte activation is suppressed by known dietary inhibitors of PRR activation. We will investigate two dietary inhibitors (as dietary supplements): docosahexaenoic acid (DHA as capsule) and anti-inflammatory polyphenols (grape or blueberry powder as a source of polyphenols).
Aim 1: Activation of TLR4 requires translocation of TLR4 into the lipid raft fraction in plasma membrane. Thus, we will determine the relative abundance of TLR4 protein in the lipid raft fraction (direct readout for TLR4 activation), and target gene expression in PBMC isolated from the subjects fed high fat meals for a week. NOD2 binds and activates caspase-1 which converts pro-IL-1ß to active IL-1ß. Thus, NOD2 activation will be determined by immunoprecipitation of caspase-1 and immunoblotting for NOD2. Aim 2: Healthy subjects will be first given DHA capsule, grape (or blueberry) powder or placebo control supplementation for 5 weeks, and then fed high saturated fat diet for a week to induce monocyte activation. Activation of TLR4 and NOD2 by dietary saturated fatty acids will be determined in PBMC as described above. These are randomized, placebo controlled, crossover design.