Title : CD11c+ dendritic cells are required for survival in murine LPS induced ALI
Purpose : Dendritic cells (DCs) are always known as professional APCs which play a crucial role in the link between innate and adaptive immunity. DCs can initiate both immunity and immunological tolerance , which means efficacy either in amelioration or exaggeration of inflammation response. LPS induced Acute lung injury(ALI) is resulted in dysregulated inflammation and sequential pulmonary endothelial and epithelial injury. DCs are known increased in LPS intracheal instilled lung but it is still unclear about their role in outcome and their priority of either immunity or immunological tolerance.
Method:Transgenic mice (B6.FVB-Tg.Itgax-DTR/EGFP.57Lan/J) expressing the diphtheria toxin (DTX) receptor on the CD11c promoter(Itgax) ,which can be used as DCKO mice after receiving i.t injection of 50 ng DTX 24h prior to LPS i.t instillation.Lungs are harvested after 24h and Wet weight and body weight ration(WW/BW) is measured to illustrate the degree of permeability. Lungs were fixed overnight at room temperature in neutral buffered formalin and then are embedded. Five micrometers sections were deparaffinized, rehydrated, and stained with H&E and then were scored for deflation, hemorrhage, thickness and infiltrating cells. DCs are identified by CD11c+ MHCII+F4/80- cells by Flow cytometry after preparation of single cell suspension while macrophages are identified by CD11c+ F4/80+ cells. Pulmonary cytokines expression are evaluated by quantitative PCR performed with the SYBR Green Master Mix after total RNA extration from smeared lung tissue and cDNA synthesis according to the manufacturers’ protocol. Survival was measured following DTX treatment and LPS instillation in DCKO mice and wide-type littermates (eight individuals per group).Statistical analysis was performed using GraphPad Prism, version 9.1.1 (GraphPad Software Inc., San Diego, CA).Values of P less than 0.05 were considered as significantly different.
Result: DCKO mice received 50ng DTX, which resulted in significant reduction of CD11c+MHCII+ cells compared to wide-type littermates. After pretreatment of DTX, WW/BW of DCKO mice is increased in LPS induced ALI (4.90 vs 6.36mg/g; p < 0.05 ). Meanwhile, lung HE stain shows deflation and infiltration and lung injury scored of DCKO mice is significantly increased(5.06 vs 7.83;p < 0.05 ).Pretreatment of DCKO mice with DT resulted in reduced survival in LPS induced ALI compared with DT-treated wild-type littermates(12.5% vs 62.5%; p < 0.05) This increased mortality was not associated with plasma cytokine concentrations.
Conclusion:These data confirm that DCs are essential in the LPS induced ALI and maintain DC numbers or immunological tolerance function may improve outcome.
- Explain the efficacy of dendritic cell in acute lung injury.
- Help understand the dendritic cell in innate immunity when ALI.
- Help expand the research of DCs in ALI