LAUSR

Objective: This study aimed to investigate the earliest immunomodulatory effects of NaCl during pre-hypertensive phase of acute salt loading in humans. Thus we have investigated serum levels of systemic pro- and anti-inflammatory cytokines in relation to peripheral Th17 and regulatory T cell abundance following 7-day high-salt (HS) loading in young salt-resistant healthy individuals. Design and method: 30 young healthy individuals adhered to a 7-day low-salt (LS) diet (3.5 g salt/day) followed by a 7-day high-salt (HS) diet (~14.7 g salt/day) protocol. Serum pro- and anti-inflammatory cytokines (INF-gamma, TNF-alpha, IL-6, IL-9, IL-17A, IL-23, IL-10, IL-21, IL-22, TGF-beta1), complement component C3a, as well as frequencies of peripheral blood Th17 and regulatory T cells (Treg), Th17/Treg ratio and the level of enzymes involved in their activation and differentiation (SGK1 and p38/MAP kinase) were measured before and after 7-day HS diet protocol. Results: Short-term HS diet significantly increased serum level of pro-inflammatory cytokines INF-gamma, TNF-alpha, IL-9 and IL-17A level, but also serum concentration of anti-inflammatory cytokines IL-10 and TGF-beta1. In addition, serum INF-gamma and IL-9 levels positively correlated to 24-h urine natriuresis. Relative amount of total and phosphorylated p38/MA kinase remained unchanged, while relative amount of total SGK1 significantly increased following 7-day HS diet compared to LS values. Conclusions: Result of the present study provided evidence of acute salt-loading induced changes in the immune status of young healthy individuals. The increase in relative amount of total SGK1 in peripheral mononuclear cells suggests lymphocyte (re)activation in response to hyperosmotic stress resulting in enhanced production of proinflammatory (IL-17, INF-gamma), but also anti-inflammatory cytokines (IL-10 and TGF-beta1). Still, which effect is prevailing remains elusive and warrants further studies.