Abstract Body: Background: High salt (HS) consumption is a leading risk factor for cardiovascular disease, partly due to increased inflammation. Our group and others have demonstrated HS increases circulating Monocyte Chemoattractant Protein-1 (MCP-1) and induces proinflammatory monocyte phenotypes. Preclinical data suggest that HS suppresses endogenous β-hydroxybutyrate (b-OHB) production, and restoring b-OHB blunts some negative consequences of HS, but effects on the immune system remain unclear. Therefore, we investigated whether concomitant b-OHB supplementation, with HS, could attenuate phenotypic drift in circulating myeloid cells in apparently healthy adults.
Methods: 15 participants (10M/5F; Age:33±12yrs; BMI:24.9±3.2kg/m²; blood pressure:107±13/63±7mmHg) completed a randomized, crossover study with three 10-day conditions: Low Salt (LS): placebo capsules (dextrose) and placebo drink; High Salt (HS): salt capsules and placebo drink; and High Salt + Ketone (HS+K): salt capsules and ketone drink. Participants received counseling to consume low sodium (~0.8 mg/kcal/day) background diets for all conditions and were supplemented up to ~2 mg/kcal/day of sodium for HS conditions and 36g β-OHB/day for the ketone condition. On day 10, mononuclear cells were isolated from whole blood and stained via a Cytek 25-Color Immunoprofiling Assay. Separately, whole blood was stimulated with 10ng/mL lipopolysaccharide for 2 hours at 37C and plasma was assayed for MCP-1, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). One-way repeated measures ANOVA (condition) were run for normally distributed data and Friedman’s test for non-normally distributed data. Significance was set to α≤0.05.
Results: We observed no shifts in monocytes (ps>0.079) or dendritic cells (ps>0.124) across conditions. We did not observe differences in stimulated whole blood MCP-1 (p=0.707) or IL-6 (p=0.504) secretion across conditions. However, there was a condition effect on TNF-α secretion (LS:45856, HS:52857, HS+K:320±89, p=0.045) whereby ketone supplementation blunted the effect of HS (p=0.039).
Conclusions: Our preliminary findings suggest no effect of high salt or concomitant ketone supplementation on phenotypic changes in myeloid cells of apparently healthy adults. However, an effect on TNF-α secretion was observed post-inflammatory stimulus, suggesting that innate immune responses in healthy adults may reflect increased proinflammatory activity rather than subpopulation shifts.