The Role Of Triggering Receptor Expressed On Myeloid Cells2 In Ventilator-induced Lung Injury

Objective: To explore the role and mechanism of TREM2 regulated inflammatory response through the mt ROS-NLRP3 inflammation pathway in the VILI model.Methods: 1.18 C57BL/6 mice,weight 25 ±2g,were randomly divided into two groups: spontaneous breathing group(CON group)and mechanical ventilation group(VT group).The mechanical ventilation group was given 7 and40 m L/kg tidal volume(n=6).The above treatments were carried out in mice after anesthesia,and the survival rate of mice was observed and recorded within8 hours.2.30 of C57BL/6 mice,weight 25 ±2g,were randomly divided into three groups: spontaneous breathing group(CON group),low tidal volume mechanical ventilation group(LVT group),and high tidal volume mechanical ventilation group(HVT group).The HVT group was divided into three subgroups according to the ventilation time(n = 6).The Mechanical ventilation time was 1.0 h,2.0 h,and 4.0 h,respectively.The lung tissue was collected,and the wet/dry weight ratio(W/ D)was measured.The pathological changes of lung tissue were observed by the hematoxylin-eosin staining(HE)method.The contents of total protein and inflammatory factors IL-1β and IL-18 in bronchoalveolar lavage fluid((BALF))were detected by BCA and ELISA.PCR,Immunofluorescence,and Western-blotting detected the expression of TREM2,NLRP3 m RNA and protein in lung tissue.3.24 of C57BL/6 mice were randomly divided into spontaneous breathing group(CON group),high tidal volume mechanical ventilation group(HVT group),TREM2 agonist group(HSP60group),and active oxygen inhibition group(Mito TEMPO group).Except for the CON group,the other three groups were given tidal volume mechanical ventilation of 40 m L/kg for 4.0 hours.The lung tissue was collected,and the wet/dry weight ratio was measured.The pathological changes of lung tissue were observed by the hematoxylin-eosin staining(HE)method.The ultrastructure of lung epithelial cells was observed by a transmission electron microscope.The contents of total protein and inflammatory factors IL-1 β and IL-18 in bronchoalveolar lavage fluid(BALF)were detected by BCA and ELISA.The content of mt ROS in lung tissue cells was detected by immunofluorescence.The expression of TREM2 and NLRP3 in lung tissue was detected by immunofluorescence assay,and the manifestation of TREM2,NLRP3,caspase-1,and ASC protein in lung tissue was detected by immunoblotting.Results: 1.Extensive VT mechanical ventilation could lead to the death of mice.2.Ample VT mechanical ventilation cause acute inflammatory lung injury in lung tissue,increasing the wet/dry ratio of lung tissue and the content of total protein in BALF.Under the optical microscope,alveolar wall rupture,alveolar fusion,interstitial thickening and a large number of inflammatory cell infiltration,even red blood cells exudate in the alveolar cavity can be seen in HE sections of the lung.The pathological scores increased,and the expression of inflammatory factors was up-regulated.3.Immunofluorescence and Western blotting methods showed that with the prolongation of ve ntilation time,the protein expression of TREM2 decreased in HTV group,while the expression of NLRP3 protein increased,meanwhile the secretion of IL-1β and IL-18 in BALF was significantly up-regulated.4.When using HSP60 to up-regulate the expression of TREM2 and Mito TEMPO,the expression of mt ROS and the number of TUNEL positive cells in lung tissue decreased significantly.The expression of NLRP3,Caspase-1,and ASC protein in lung tissue decreased,and the inflammatory reaction of lung tissue fell.Conclusion: TREM2 might be alleviated the inflammatory response of ventilator-associated lung injury by inhibiting the mt ROS-NLRP3 inflammasome pathway.