Regulation of autophagy on NLRP3 inflammasome in neonatal rats with BPD
Objective:To investigate the relationship between autophagy and nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3)inflammasome in hyperoxy-induced bronchopulmonary dysplasia(BPD)in neonatal rats,and its impact on the developmental outcome of the lungs.Methods:Neonatal rat model of BPD was initially established using 85%oxygen,and then compared with neonatal rats kept in normoxia(21%oxygen).Pathological sections were obtained from lung tissues of rats on postnatal days 3,7,and 14.Hematoxylin-eosin staining was used to observe morphological changes in lung tissue(RAC and MLI).The changes of autophagy flux were determined by Western blot analysis of LC3 and P62 proteins in lung tissue.Rapamycin group(Drug+Hyperoxia,DO group)of neonatal rats was exposed to the same hyperoxia environment as hyperoxia group,and intraperitoneal injections of rapamycin were administered on postnatal days 2,4,and 6.The hyperoxia group and normoxia group(HO and NO group)were injected with an equivalent volume of saline.On the 7th day after birth,Western blot was performed to measure the expression of MTOR,LC3,P62,NLRP3,ASC,cleaved caspase-1 and cleaved IL-1β in lung tissues.mRNA levels of LC3,NLRP3,cleaved caspase-1 were as sessed by PCR to determine the relationship between autophagy and inflammasome activity.Results:HE staining showed that the RAC at postnatal days 7 and 14 were higher in the NO group than in the HO group(P<0.05),while the MLI was higher in the HO group(P<0.05).Western blot showed that the HO group had higher expression of LC3-Ⅱ/LC3-Ⅰ(P<0.01)and P62(P<0.05)at postnatal days 3 and 7 than the NO group.On postnatal day 7,HE staining revealed that the RAC in the HO group was lower than that in the NO and DO groups(P<0.05),while the MLI in the HO group was higher(P<0.05).On postnatal day 7,Western blot demonstrated that MTOR,LC3-Ⅱ/LC3-Ⅰ,P62,NLRP3,ASC,cleaved caspase-1,and cleaved IL-1β in the HO group were higher than those in the NO and DO groups(P<0.05).qPCR showed that LC3 mRNA in the HO group was lower than that in the NO and DO groups(P<0.05),while the mRNA levels of NLRP3 and caspase-1 in the HO group were higher(P<0.05).Conclusion:The interaction between autophagy flux and inflammasome is an important factor in its occurrence and development.Increased autophagy flux can reduce the activity of inflammasome,decrease the production of cleaved IL-1β and improve BPD,providing a basis for further treatment of BPD.
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