目标:游离D-氨基酸,它们具有与L-氨基酸不同的功能,最近在各种组织中被发现。然而,关于肠道炎症和D-氨基酸之间潜在相互作用的研究是有限的。我们研究了D-丙氨酸对肠道炎症发病机理的抑制作用。
方法:我们调查了40例溃疡性结肠炎患者和34例健康志愿者的血清D-氨基酸水平。对于7d,用葡聚糖硫酸钠诱导C57BL/6J小鼠急性结肠炎。在葡聚糖硫酸钠诱导的结肠炎小鼠中定量血浆D-氨基酸水平,这些动物通过腹膜内注射给予D-丙氨酸。IFN-γ,IL-12p35,IL-17A,使用实时PCR检测结肠粘膜中IL-23p19mRNA的表达。进行体外增殖测定以评估在Th-偏斜条件下的初始CD4+T细胞活化。用小鼠巨噬细胞集落刺激因子刺激骨髓细胞以产生小鼠骨髓来源的巨噬细胞。
结果:溃疡性结肠炎患者的血清D-丙氨酸水平明显低于健康志愿者。葡聚糖硫酸钠处理的小鼠的血浆D-丙氨酸水平显著低于对照小鼠。D-丙氨酸处理的小鼠的疾病活动指数明显低于对照小鼠。IFN-γ,IL-12p35,IL-17A,和IL-23p19mRNA表达水平在D-丙氨酸给药的小鼠中显著低于对照小鼠。D-丙氨酸在体外抑制初始T细胞分化为Th1细胞,并抑制骨髓源性巨噬细胞中IL-12p35和IL-23p19的产生。
结论:我们的结果表明,D-丙氨酸可以预防葡聚糖硫酸钠诱导的小鼠结肠炎,并抑制巨噬细胞中IL-12p35和IL-23p19的产生。
OBJECTIVE: Free D-amino acids, which have different functions from L-amino acids, have recently been discovered in various tissues. However, studies on the potential interactions between intestinal inflammation and D-amino acids are limited. We examined the inhibitory effects of D-alanine on the pathogenesis of intestinal inflammation.
METHODS: We investigated serum D-amino acid levels in 40 patients with ulcerative colitis and 34 healthy volunteers. For 7 days [d], acute colitis was induced using dextran sulphate sodium in C57BL/6J mice. Plasma D-amino acid levels were quantified in mice with dextran sulphate sodium-induced colitis, and these animals were administered D-alanine via intraperitoneal injection. IFN-γ, IL-12p35, IL-17A, and IL-23p19 mRNA expression in the colonic mucosa was measured using real-time polymerase chain reaction [PCR]. In vitro proliferation assays were performed to assess naïve CD4+ T cell activation under Th-skewing conditions. Bone marrow cells were stimulated with mouse macrophage-colony stimulating factor to generate mouse bone marrow-derived macrophages.
RESULTS: Serum D-alanine levels were significantly lower in patients with ulcerative colitis than in healthy volunteers. Dextran sulphate sodium-treated mice had significantly lower plasma D-alanine levels than control mice. D-alanine-treated mice had significantly lower disease activity index than control mice. IFN-γ, IL-12p35, IL-17A, and IL-23p19 mRNA expression levels were significantly lower in D-alanine-administered mice than in control mice. D-alanine suppressed naïve T cell differentiation into Th1 cells in vitro, and inhibited the production of IL-12p35 and IL-23p19 in bone marrow-derived macrophages.
CONCLUSIONS: Our results suggest that D-alanine prevents dextran sulphate sodium-induced colitis in mice and suppresses IL-12p35 and IL-23p19 production in macrophages.