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目的:评价烟酰胺腺嘌呤二核苷酸(NADn +)介导的沉默信息调节因子1(SIRT1)去乙酰化活性在小鼠内毒素性急性肺损伤(ALI)中的作用。n 方法:SPF级健康雄性C57BL/6小鼠25只，6~8周龄，体重20~25 g，野生(WT)型10只，NADn +合成途关键酶烟酰胺单核苷酸腺苷酸转移酶1(NMNAT1)敲除(KO)型15只，采用随机数字表法，将WT型小鼠分为2组(n n＝5)：对照组(WT+C组)和ALI组(WT+ALI组)；将KO型小鼠分为3组(n n＝5)：对照组(KO+C组)、ALI组(KO+ALI组)和ALI+ NADn +前体物质烟酰胺单核苷酸(NMN)组(KO+ALI+NMN组)。静脉注射LPS 15 mg/kg制备内毒素性ALI模型，KO+ALI+NMN组注射静脉注射LPS前1 h腹腔注射NMN 500 mg/kg。各对照组给予等容量生理盐水。注射LPS或生理盐水后12 h时，取腹主动脉血标本行血气分析，后处死小鼠留取肺组织，测定肺湿重/干重(W/D)比值，光镜下观察肺组织病理学改变，并行肺损伤评分；采用ELISA法检测肺组织IL-6、IL-1β、TNF-α含量，采用分光光度计法测定NADn +含量，采用Western blot法测定肺组织SIRT1、乙酰化NF-κB (Ac-NF-κB)、乙酰化p53(Ac-p53)、乙酰化叉头框蛋白O1(Ac-FoxO1)、乙酰化过氧化物酶体增殖激活物受体γ辅激活因子(Ac-PGC1α)水平。n 结果:与各C组比较，各ALI组pH值和PaOn 2降低，PaCOn 2、肺W/D比值、肺损伤评分、肺组织IL-6、IL-1β、TNF-α和NADn +含量升高，SIRT1表达上调，Ac-NF-κB、Ac-p53、Ac-FoxO1和Ac-PGC1α表达下调(n P<0.05)。与WT+ALI组比较，KO+ALI组pH值和PaOn 2降低，PaCOn 2、肺W/D比值、肺损伤评分、肺组织IL-6、IL-1β和TNF-α含量升高，NADn +含量降低，SIRT1表达下调，Ac-NF-κB、Ac-p53、Ac-FoxO1和Ac-PGC1α表达上调(n P<0.05)。与KO+ALI组比较，KO+ALI+NMN组pH值和PaOn 2升高，PaCOn 2、肺W/D比值、肺损伤评分、肺组织IL-6、IL-1β和TNF-α含量降低，NADn +含量升高，SIRT1表达上调，Ac-NF-κB、Ac-p53、Ac-FoxO1和Ac-PGC1α表达下调(n P<0.05)。n 结论:NADn +介导的SIRT1去乙酰化活性增强参与了小鼠内毒素性ALI时的内源性保护机制。n “,”Objective:To evaluate the role of nicotinamide adenine dinucleotide (NADn + )-mediated deacetylation activity of silent information regulator 1 (SIRT1) in endotoxin-induced acute lung injury (ALI) in mice.n Methods:Twenty-five SPF clean-grade healthy male C57BL/6 mice including 10 wild-type (WT) and 15 NMNAT1 conditional-knockout (KO) mice, aged 6-8 weeks, weighing 20-25 g, were selected.The WT mice were divided into 2 groups (n n=5 each) using a random number table method: control group (group WT+ C) and ALI group (group WT+ ALI). The KO mice were divided into 3 groups (n n=5 each) using a random number table method: control group (group KO+ C), ALI group (group KO+ ALI) and ALI plus NADn + precursor substances nicotinamide mononucleotide (NMN) group (KO+ LPS+ NMN group). ALI was produced with lipopolysaccharide (LPS) 15 mg/kg injected intravenously.NMN 500 mg/kg was intraperitoneally injected at 1 h before injection of LPS in KO+ ALI+ NMN group, while the equal volume of normal saline was given instead in control group.Blood samples were collected from the abdominal aorta at 12 h after LPS or normal saline injection for blood gas analysis, and the animals were then sacrificed and the lung tissues were removed for microscopic examination of pathologic changes which were scored and for determination of wet/dry weight ratio (W/D ratio), and interleukin-6 (IL-6), IL-1β and tumor necrosis factor-alpha (TNF-α) contents (by enzyme-linked immunosorbent assay)and content of NADn + (using a spectrophotometer) and levels of SIRT1, acetylated nuclear factor kappaB (Ac-NF-κB), acetylated p53 (Ac-p53), acetylated FoxO1 (Ac-FoxO1) and acetylated PGC1α (Ac-PGC1α) (by Western blot).n Results:Compared with group C, pH value and PaOn 2 were significantly decreased, the PaCOn 2, W/D ratio, lung injury score, contents of IL-6, IL-1β, TNF-α and NADn + were increased, expression of SIRT1 was up-regulated, and expression of Ac-NF-κB, Ac-p53, Ac-FoxO1 and Ac-PGC1α was down-regulated in group ALI (n P<0.05). Compared with group WT+ ALI, pH value and PaOn 2 were significantly decreased, the PaCOn 2, W/D ratio, lung injury score, contents of IL-6, IL-1β and TNF-α were increased, NADn + content was decreased, expression of SIRT1 was down-regulated, and expression of Ac-NF-κB, Ac-p53, Ac-FoxO1 and Ac-PGC1α was up-regulated in group KO+ ALI (n P<0.05). Compared with group KO+ ALI, pH value and PaOn 2 were significantly increased, the PaCOn 2, W/D ratio, lung injury score, contents of IL-6, IL-1β and TNF-α were decreased, NADn + content was increased, expression of SIRT1 was up-regulated, and expression of Ac-NF-κB, Ac-p53, Ac-FoxO1 and Ac-PGC1α was down-regulated in group KO+ ALI+ NMN (n P<0.05).n Conclusion:The enhanced NADn + -mediated deacetylation activity of SIRT1 is involved in the endogenous protective mechanism in mice with endotoxin-induced ALI.n