PDF(Pubmed)
Abstract：
Inflamed and infected tissues can display increased local sodium (Na+) levels, which can have various effects on immune cells. In macrophages, high salt (HS) leads to a Na+/Ca2+-exchanger 1 (NCX1)-dependent increase in intracellular Na+ levels. This results in augmented osmoprotective signaling and enhanced proinflammatory activation, such as enhanced expression of type 2 nitric oxide synthase and antimicrobial function. In this study, the role of elevated intracellular Na+ levels in macrophages was investigated. Therefore, the Na+/K+-ATPase (NKA) was pharmacologically inhibited with two cardiac glycosides (CGs), ouabain (OUA) and digoxin (DIG), to raise intracellular Na+ without increasing extracellular Na+ levels. Exposure to HS conditions and treatment with both inhibitors resulted in intracellular Na+ accumulation and subsequent phosphorylation of p38/MAPK. The CGs had different effects on intracellular Ca2+ and K+ compared to HS stimulation. Moreover, the osmoprotective transcription factor nuclear factor of activated T cells 5 (NFAT5) was not upregulated on RNA and protein levels upon OUA and DIG treatment. Accordingly, OUA and DIG did not boost nitric oxide (NO) production and showed heterogeneous effects toward eliminating intracellular bacteria. While HS environments cause hypertonic stress and ionic perturbations, cardiac glycosides only induce the latter. Cotreatment of macrophages with OUA and non-ionic osmolyte mannitol (MAN) partially mimicked the HS-boosted antimicrobial macrophage activity. These findings suggest that intracellular Na+ accumulation and hypertonic stress are required but not sufficient to mimic boosted macrophage function induced by increased extracellular sodium availability.
摘要：
发炎和感染的组织可以显示增加的局部钠（Na+）水平，会对免疫细胞产生各种影响。在巨噬细胞中，高盐（HS）导致细胞内Na水平的Na/Ca2交换剂1（NCX1）依赖性增加。这导致增强的渗透保护信号和增强的促炎激活，如增强2型一氧化氮合酶的表达和抗菌功能。在这项研究中,研究了巨噬细胞中细胞内Na+水平升高的作用。因此,Na+/K+-ATP酶(NKA)在药理学上被两种强心苷(CG)抑制,ouabain（OUA）和地高辛（DIG），提高细胞内Na+而不增加细胞外Na+水平。暴露于HS条件和用两种抑制剂处理导致细胞内Na+积累和随后p38/MAPK的磷酸化。与HS刺激相比，CG对细胞内Ca2和K具有不同的影响。此外，OUA和DIG处理后,活化T细胞核因子5(NFAT5)在RNA和蛋白质水平上没有上调.因此，OUA和DIG不能促进一氧化氮（NO）的产生，并且对消除细胞内细菌表现出异质作用。而HS环境会引起高渗应力和离子扰动，强心苷只诱导后者。用OUA和非离子渗透物甘露醇（MAN）共同处理巨噬细胞部分模拟了HS增强的抗微生物巨噬细胞活性。这些发现表明，细胞内Na积累和高渗应激是必需的，但不足以模拟由细胞外钠利用率增加引起的巨噬细胞功能增强。
