LRRC15 Regulation Of Autophagy In Pulmonary Fibrosis

Idiopathic Pulmonary Fibrosis(IPF)is a progressive,chronic and irreversible interstitial lung disease with unknown pathogenic cause.The main features are alveolar epithelial cell injury,fibroblast accumulation,abnormal extracellular matrix deposition and honeycomb-like lungs.Most patients have a poor prognosis,with a median survival time of 3-5 years.LRRC15 is a member of the LRRC superfamily.Its members are the bonds of protein-protein and protein-matrix interactions,are associated with inflammatory reactions,and play an important role in cell adhesion,signal transduction,and DNA repair.However,there is no relevant literature report on the role and regulation mechanism of LRRC15 in IPF.In this study,bleomycin-induced lung fibrosis in C57BL/6 mice and A549 cell damage were used as research models,and the role and regulatory mechanism of LRRC15 in IPF were explored in vivo and in vitro.In order to study the regulate role of LRRC15 in IPF.We constructed a bleomycin injury model of C57 BL / 6 mice and A549 cells.On this basis,the morphological changes of lung tissues in clinical IPF patients and mice were first detected.The results showed that the two tissues showed the characteristics of interstitial pneumonia: fibroblasts increased,inflammatory cell infiltration,and extracellular matrix deposition.The expression of LRRC15 in the above two tissues was detected by immunohistochemistry.The results showed that LRRC15 was mainly expressed in bronchiole and terminal bronchiole epithelial cells,and increased expression in IPF lung tissue.Western Blot and q RT-PCR detected the expression of LRRC15 in the BLM injury model of mice and A549 cells.The results also showed that,compared with the respective control groups,the expression of LRRC15 was significantly increased after the BLM treatment,and the difference was significant or extremely significant(P <0.05 or P <0.01).The above results indicate that LRRC15 may be related to IPF.Then we designed and synthesized the LRRC15 interference fragment into A549 cells,and detected the expression of LRRC15 by Western blot and q RT-PCR.The results indicated that the expression of LRRC15 was significantly reduced and the difference was extremely significant(P <0.01 or P <0.001).The results of MTT experiments further showed that the viability of A549 cells decreased after BLM treatment,and the inhibition of LRRC15 expression could partially restorethe cell activity reduction caused by BLM.The above results indicate that the expression of LRRC15 in IPF is increased,and interference with the expression of LRRC15 can inhibit the damage of alveolar epithelial cells caused by BLM.To further explore the mechanism of LRRC15 regulating IPF,we first examined the changes in autophagy after BLM treatment of A549 cells.Western blot results showed that after BLM treatment of A549 cells for 24 h and 48 h,LC3-II showed a trend of rising first and then falling,and p62 showed a rising trend.The detection of GFP-RFP-LC3 dual fluorescent markers revealed that the number of LC3 autophagosomes increased after BLM treatment.Further treatment of A549 cells with si RNA LRRC15,Western blot results found that the expression of key autophagy proteins LC3-Ⅱ,ATG5,ATG7 increased,P62 protein expression was down-regulated;transfected with GFP-RFP-LC3 dual fluorescence,laser confocal microscope detection found Enhanced autophagy.The above results indicate that inhibition of LRRC15 can enhance autophagy in IPF.In summary,LRRC15 increased expression in IPF;LRRC15 can promote the process of IPF;LRRC15 regulates IPF by inhibiting autophagy.This study provides the necessary theoretical basis for further elucidating the mechanism of IPF.