Modulation of Plasma Sphingosine-1-Phosphate Levels via Dietary Salt Intervention in Chinese Adults:an Intervention Trial
Abstract Background: Sphingosine-1-phosphate (S1P), a pleiotropic bioactive sphingolipid metabolite, is involved in various pathophysiological processes,including blood pressure regulation. Salt is a crucial factor for blood pressure modulation,especially in salt-sensitive individuals who may develop earlier, more severe subclinical target organ damage than salt-resistant individuals.However, the relationships among salt intake, circulating S1P levels, and blood pressure changes are unknown. Thus, we conducted this intervention trial to explore the effect of dietary salt intake on plasma S1P levels and examine the relationship between S1P and blood pressure in Chinese adults.Methods:Forty-two participants (aged 18–65 years) were recruited from a rural community in Shaanxi, China. All participants first maintained their normal diet for 3 days, then sequentially ate a low-sodium diet (3.0 g/day NaCl) for 7 days, followed by a high-sodium diet (18.0 g/day NaCl) for 7 days. We assessed their plasma S1P concentrations on the last day of each intervention phase by liquid chromatography–tandem mass spectrometry. We classified the subjects who demonstrated at least a 10% increase in mean arterial pressure upon transitioning from a low-salt to a high-salt diet as salt-sensitive and the others as salt-resistant. Differences in repeated measures were analyzed by repeated-measures analysis of variance. Results:Plasma S1P levels decreased significantly from the baseline to low-salt diet period and increased from the low-salt tohigh-salt diet period. We observed this response in both salt-sensitive and salt-resistant individuals. Plasma S1P levels positively correlated with 24-hour urinary sodium excretion, but not 24-hour urinary potassium excretion. In line with plasma S1P level responses to salt intervention, systolic blood pressure and mean arterial pressure decreased from the baseline to low-salt diet period and increased from the low-salt to high-salt period.Systolic blood pressure positively correlated with plasma S1P; the correlation was stronger in salt-sensitive individuals than in salt-resistant individuals. Conclusion:Low-salt intervention decreased plasma S1P levels, whereas high-salt intervention reversed this changein Chinese adults. This finding provides evidence that salt moderation may be a high-efficiency, low-cost intervention for regulating circulating S1P levels, with implications for salt-induced blood pressure modulation. Trial registration: NCT02915315.Registered 27 September,2016,http://www.clinicaltrials.gov