PS4-9. Hempseed Products Modulate Immune and Metabolic Responses in Sheep Monocyte-derived Macrophages.

Abstract

Small ruminants play an important role in global livestock production, particularly in meat production; however, sheep are susceptible to diseases and infections that can negatively affect productivity. Macrophages play a central role in early immune defense by sensing pathogens and initiating inflammatory responses that help coordinate subsequent immune reactions. Therefore, in vitro macrophage models provide an efficient approach for evaluating cellular responses to bioactive compounds before conducting in vivo experiments. The objective of this study was to evaluate the effects of dehulled hempseed (HS) and hempseed meal (HSM) extracts on immune and metabolic responses of sheep monocyte-derived macrophages (MDM). Monocyte-derived macrophages were obtained from peripheral blood mononuclear cells isolated from blood collected from six mature ewes and differentiated by culturing adherent monocytes for 7 days prior to treatment. Cells were treated with HS or HSM extracts at three concentrations (100, 500, and 2,500 µg/mL). MDM functional activity was evaluated through phagocytosis and oxidative burst using fluorescence-based assays. In the spent media, glucose concentration was measured using a hexokinase assay as a proxy of glucose utilization, and nitric oxide production was quantified using the Griess reagent. Data were analyzed using SAS, and comparisons with the control were conducted using PDIFF statement, and effects of product (HS vs. HSM), product concentration, and their interaction were evaluated. Differences were considered significant at P ≤ 0.05 and a tendency at 0.05 < P ≤ 0.10. Phagocytosis did not differ between treatments and the control. However, HS tended to increase phagocytosis compared with HSM (P = 0.06). For oxidative burst and nitric oxide, the highest HS concentration increased oxidative burst and nitric oxide compared with the control (P < 0.05). Across product concentrations, HS also tended to increase oxidative burst compared with HSM (P = 0.07) with the effect becoming numerically more evident as dose increased (product × linear concentration, P = 0.11). None of the treatments differed from control for glucose concentration. However, glucose concentrations tended to be lower with HS (P = 0.09), driven by a lower glucose concentration at 500 µg/mL HS (product × quadratic concentration, P = 0.04). For both products, nitric oxide increased linearly with product concentration (P = 0.02). These results indicate that HS may be more effective than HSM in enhancing macrophage functional responses, particularly as concentrations increased. The findings suggest that bioactive components within hempseed products may influence immune cell activity, supporting further investigation of hemp-derived products as potential functional dietary components in ruminant nutrition.