Expression And Role Of NLRC3 In Ventilator-induced Lung Injury Of Rats

Objective To determine the biomass change of NLRC3 in lung of rats and explore its function by establishing the model of VILI in rats in order to provide new ideas for prevention and treatment of VILI.Methods 24 clean healthy adult male SD rats,8 weeks old,weighing 180～220 g,were divided into 2 groups according to the random number table:the spontaneous breathing group（group C）and the ventilator-induced lung injury group（group VILI）,12rats in each group.All rats were fasted for 8 hours before the experiment,drank water freely,and anesthetized with pentobarbital sodium via intraperitoneal injection.After anesthesia,the skin of rats were cut along the trachea,fascia and muscle were bluntly separated to expose the trachea and right common carotid artery,catheterization via right common carotid artery;The skin of rats were cut along the right femoral artery,fascia and muscle were bluntly separated to expose femoral artery sheath,then,right femoral vein were separated to establish venous access.Tracheotomy and intubation were performed on the two groups of rats,the rats in group C kept spontaneous breathing;The rats in group VILI were injected with cisatracurium besilate via the right femoral vein,and mechanical ventilation was performed after spontaneous respiration of rats in group VILI disappeared,parameter settings:Tidal volume was 20 ml/kg,respiratory frequency was80 times per minutes,FiO₂ was 21%,PEEP was 0 cmH₂O,mechanical ventilation time was 4 h.Immediately after tracheal intubation and immediately after ventilation,blood was collected through the right common carotid artery for blood gas analysis and PaO₂was recorded;After ventilation,rats were sacrificed by bleeding from the right common carotid artery,lung tissue and BALF were quickly gathered for examination.Light microscope was used to evaluate pathological phenomenon,and the lung tissue pathological damage score was calculated,the W/D of lung tissue was calculated;The concentrations of IL-1βand IL-18 in BALF were determined by ELISA;RT-PCR was used to detect the mRNA expression of NLRC3,NLRP3,ASC,and caspase-1 in lung of rats;Western blot was used to detect the protein expression of NLRC3,NLRP3,ASC and caspase-1 in lung of rats.Results Compared with tracheal intubation immediately,PaO₂ in the group VILI decreased after the end of ventilation（P<0.01）;Compared with group C,PaO₂ in the group VILI decreased after ventilation（P<0.01）.Histopathological results of lung showed that there was no abnormal alveolar structure in the group C,the alveolar walls were coherent,and the boundaries were clearer;However,in the group VILI,the alveolar walls were broken and wider,capillaries were irregularly oozing blood,bloody bulges were visible,and interstitial lung was full of lymphocytes and neutrophils.Compared with group C,the lung tissue pathological damage score of the group VILI was higher（P<0.01）,the W/D of the group VILI increased（P<0.01）,and the concentration of IL-1βand IL-18 in BALF of the group VILI increased（P<0.01）.The mRNA expression of NLRP3,ASC,and caspase-1 in lung of the group VILI increased（P<0.01）,the mRNA expression NLRC3 in lung of the group VILI decreased（P<0.01）;The protern expression of NLRP3,ASC,and caspase-1 in lung of the group VILI increased（P<0.01）,the protern expression NLRC3 in lung of the group VILI decreased（P<0.01）.Conclusion（1）NLRP3 inflammasome is activated during VILI of rats,which mediates the pulmonary inflammation response,and leads to lung injury.（2）Down-regulation of NLRC3 expression is involved in VILI in rats,and its mechanism may be related to the activation of NLRP3 inflammasome.