Influence of Dietary Botanical Supplements on Biological and Behavioral Resilience

Summary Abstract The studies proposed in this U19 application titled “The Influence of Dietary Botanical Supplements on Biological and Behavioral Resilience” represent a cohesive program of integrated and interdisciplinary research approaches that comprehensively address the objectives and purpose of RFA-OD-19-001. In particular, the principal objective of this botanical dietary supplement research center (BDSRC) is to provide valuable insight, through both pre-clinical and clinical lines of investigation that may inform a future clinical trial designed to determine if dietary polyphenol supplements can provide resilience against stress-induced psychological impairment. We have shown through rigorous feasibility studies utilizing stress-induced models of depression that supplementation with BDPP promotes resilience to depression-like behaviors. We have identified biomolecular systems associated with immune function and neuronal activity that specific bioavailable metabolites of BDPP influence to promote resilience to stress. We note that bioavailable metabolites suppressed production of peripheral leukocytes derived inflammatory cytokines, in particular IL-6, which is important to consider given studies that find production of IL-6 is a critical response that confers susceptibility to stress. Whether or not metabolites of BDPP suppress the downstream pathophysiological effects of stress-induced IL-6 that directly affect neuron function and behavior has yet to be established. Therefore, Project 1 of this BDSRC will characterize if our botanical supplement provides resilience against physiological pathways elicited by stress that are associated with increased IL-6 activity and that confer susceptibility to the onset of depressive-like behavior. Project 1 will also identify biological targets in microglia, interneurons, and blood brain barrier cells influenced by BDPP metabolites by state-of-the-art cell-specific RNA-sequencing and imaging techniques. Project 2 will directly synergize with Project 1 by first providing an assessment of the clinical properties of BDPP, and whether they parallel those observed in rodents. We will conduct a pharmacokinetic and steady-state profile to define bioavailable metabolites found in human plasma, and to confirm the presence of metabolites that exert biological effects against IL-6 production. Project 2 will also utilize a multivariate adaptive regression splines model to identify specific metabolites or combinations of BDPP metabolites responsible for modulating IL-6 expression. In addition, Project 2 will validate plasma IL-6 as a marker of biological resilience in response to BDPP treatment by testing if BDPP promotes resilience against upregulation of plasma IL-6 in response to the Trier Social Stress Test in humans. The proposed Projects are designed and optimized to synergize with each other, and to integrate seamlessly with the two Scientific Cores. Together, this proposal offers to provide critical information of the mechanism of action and the clinical properties of BDPP and its metabolites that fill the most critical gaps in the existing body of data needed to optimally design a future clinical trial to test resilient properties of BDPP in response to stress.