The accumulation and maturation status of pulmonary conventional dendritic cells in the early phase of acute lung injury / 中华急诊医学杂志

ABSTRACT

Objective To investigate the accumulation and maturation status of pulmonary conventional dendritic cells (cDCs) in the early phase of acute lung injury (ALI),and to explore the way of the inflammatory responses and lung injury modulated by cDCs in vivo.MethodsMale C57BL/6 mice were randomly ( random number) divided into the normal control group,6 h-ALI group and 24 h-ALI group.Murine model of ALI was made by intra-tracheal administration of lipopolysaccharide (LPS) and lung specimens were taken 6 h or 24 h later.The accumulation and maturation status of pulmonary cDCs were assessed by flow cytometry.IL-6 and TNF-α were quantified to evaluate the lung inflammation.Transcription factors T-bet/GATA-3 mRNA ratio was determined to estimate the balance between Th1/Th2 responses.IFN-γand IL-4 were quantified to evaluate Thl-specific and Th2-specific cytokine production respectively.Lung injury was estimated by lung wet weight/body weight ratio (LWW/BW) and histopathological assessment.Comparison between groups was performed using one -way ANOVA.ResultsCompared with normal control group,LPS challenge resulted in higher level of IL-6 and TNF-α,increased LWW/BW ratio and significant histopathological changes (P ＜0.01 ).The accumulation and maturation of pulmonary cDCs in 6 h-ALI group were significantly increased after LPS challenge (P ＜0.01 ),while the accumulation and maturation of pulmonary cDCs in 24 h-ALI group were significantly lower than that in 6 h-ALI group ( P ＜0.01 ).Compared with normal control group,the expression of T-bet mRNA in 24 h-ALI group was markedly enhanced ( P ＜ 0.01 ) and the production of IFN-γ was increased as well ( P ＜ 0.01 ).ConclusionsThe accumulation and maturation of pulmonary cDCs peaked within 24 h after LPS challenge,pulmonary cDCs may initiate and amplify acute lung inflammation of ALI by enhancing the Th1 immune response and ensuing cytokine production.