AIM:A mouse model of acute exacerbation of idiopathic pulmonary fibrosis(AE-IPF)was estab-lished.METHODS:One hundred and twenty male C57BL/6 mice were randomly divided into a negative control group,an IPF group,and an acute exacerbation of interstitial fibrosis(AE-IPF)group.The IPF group received a low dose(3 mg/kg)of bleomycin(BLM)by endotracheal drip on days 0,14,and 28.The AE-IPF group received a high dose(5 mg/kg)of BLM by endotracheal drip on day 56.The control group received an equal volume of saline at different time points.The AE-IPF group was injected with a high dose(5 mg/kg)of BLM via tracheal drip on day 56 on top of the initial IPF induction,while the control group received equal amounts of saline at different time points.Experiments were con-ducted on the 57th,59th,63rd,and 70th days after the initial modeling.Mice were observed for general conditions,CT imaging changes,HE,and Masson staining to assess the degree of alveolitis and fibrosis in lung tissues.Lung function,hydroxyproline(HYP)content in lung tissues,and interleukin-6(IL-6)content in bronchoalveolar lavage fluid(BALF)were also measured.RESULTS:Mice in the AE-IPF group exhibited wheezing,shortness of breath,dyspnea,and weight loss.CT imaging revealed that IPF group mice showed patchy,subpleural reticular fuzzy shadows with irregular thickening of interlobular septa and intralobular linear shadows,along with tractional bronchiectasis.In the AE-IPF group,new ground-glass shadows and solid shadows appeared in addition to the IPF features.AE-IPF group mice demon-strated decreased lung function,elevated lung index,and acute pulmonary edema.HE and Masson staining of AE-IPF group mice showed consistent pathological manifestations of AE-IPF.HYP content in lung tissues,total cell count in BALF,and IL-6 concentration were significantly higher in the AE-IPF group compared to the control group(P<0.05).CONCLUSION:The use of multiple tracheal drip administrations of bleomycin successfully established an AE-IPF ani-mal model in mice.The 63rd day of the experiment was identified as the optimal observation point,as it exhibited the most significant pathological features and clinical symptoms.This model provides ideal conditions for studying AE-IPF patho-genesis and evaluating therapeutic efficacy.

AIM:A mouse model of acute exacerbation of idiopathic pulmonary fibrosis(AE-IPF)was estab-lished.METHODS:One hundred and twenty male C57BL/6 mice were randomly divided into a negative control group,an IPF group,and an acute exacerbation of interstitial fibrosis(AE-IPF)group.The IPF group received a low dose(3 mg/kg)of bleomycin(BLM)by endotracheal drip on days 0,14,and 28.The AE-IPF group received a high dose(5 mg/kg)of BLM by endotracheal drip on day 56.The control group received an equal volume of saline at different time points.The AE-IPF group was injected with a high dose(5 mg/kg)of BLM via tracheal drip on day 56 on top of the initial IPF induction,while the control group received equal amounts of saline at different time points.Experiments were con-ducted on the 57th,59th,63rd,and 70th days after the initial modeling.Mice were observed for general conditions,CT imaging changes,HE,and Masson staining to assess the degree of alveolitis and fibrosis in lung tissues.Lung function,hydroxyproline(HYP)content in lung tissues,and interleukin-6(IL-6)content in bronchoalveolar lavage fluid(BALF)were also measured.RESULTS:Mice in the AE-IPF group exhibited wheezing,shortness of breath,dyspnea,and weight loss.CT imaging revealed that IPF group mice showed patchy,subpleural reticular fuzzy shadows with irregular thickening of interlobular septa and intralobular linear shadows,along with tractional bronchiectasis.In the AE-IPF group,new ground-glass shadows and solid shadows appeared in addition to the IPF features.AE-IPF group mice demon-strated decreased lung function,elevated lung index,and acute pulmonary edema.HE and Masson staining of AE-IPF group mice showed consistent pathological manifestations of AE-IPF.HYP content in lung tissues,total cell count in BALF,and IL-6 concentration were significantly higher in the AE-IPF group compared to the control group(P<0.05).CONCLUSION:The use of multiple tracheal drip administrations of bleomycin successfully established an AE-IPF ani-mal model in mice.The 63rd day of the experiment was identified as the optimal observation point,as it exhibited the most significant pathological features and clinical symptoms.This model provides ideal conditions for studying AE-IPF patho-genesis and evaluating therapeutic efficacy.

AIM:To establish a mouse model of pulmonary fibrosis induced by multiple intratracheal instilla-tions of bleomycin(BLM).METHODS:C57BL/6J mice were randomly divided into five groups:control group(n=5),multiple high-dose BLM(BLM-MH)group(n=10),multiple medium-dose BLM(BLM-MM)group(n=8),multiple low-dose BLM(BLM-ML)group(n=7),and single medium-dose BLM(BLM-SM)group(n=6).The pulmonary fibrosis mod-el was induced by single or multiple intratracheal instillations of BLM.Survival curves were plotted at day 56,and lung tis-sue was collected for lung coefficient calculation.Pathological changes in lung tissue were assessed using hematoxylin-eo-sin(H&E)staining and Masson staining.Indicators of lung fibrosis,such as hydroxyproline(HYP),were measured.Dif-ferentially expressed genes in patients with IPF were screened using the GEO database,and kyoto encyclopedia of genes and genomes(KEGG)pathway enrichment analysis was performed to identify pathways associated with IPF.Western blot was used to detect changes in these pathways in the lung tissues of the model mice.RESULTS:The survival rates were 50%in the BLM-MH group and 87.5%in the BLM-MM group,with no deaths in other groups.Compared with the control group,the BLM-MH and BLM-MM groups showed significantly increased lung coefficients(P＜0.05),lung tissue dam-age,inflammation levels,degree of pulmonary fibrosis(P＜0.05 or P＜0.01),and HYP content.The BLM-MH and BLM-MM groups,compared with the BLM-SM group,showed significantly elevated levels of inflammation,fibrosis,and HYP content(P＜0.05 or P＜0.01).GEO database and KEGG enrichment analysis revealed that the extracellular matrix-recep-tor interaction pathway(ECM-RIP)may be involved in IPF development.The expression levels of ECM-RIP pathway-re-lated proteins,such as phosphorylated focal adhesion kinase(p-FAK)and phosphorylated Src protein(p-Src),were in-creased in the lung tissues of the model mice compared with the control group.Compared with the BLM-SM group,the BLM-MH group exhibited significant increases in the protein levels of p-FAK and p-Src in the lung tissue(P＜0.05).CONCLUSION:The murine model of pulmonary fibrosis established through repeated intratracheal instillations of BLM effectively mimics the pathological characteristics of the disease,providing a valuable experimental model for the investiga-tion of idiopathic pulmonary fibrosis pathogenesis and for the development of therapeutic agents.

AIM:To establish a mouse model of pulmonary fibrosis induced by multiple intratracheal instilla-tions of bleomycin(BLM).METHODS:C57BL/6J mice were randomly divided into five groups:control group(n=5),multiple high-dose BLM(BLM-MH)group(n=10),multiple medium-dose BLM(BLM-MM)group(n=8),multiple low-dose BLM(BLM-ML)group(n=7),and single medium-dose BLM(BLM-SM)group(n=6).The pulmonary fibrosis mod-el was induced by single or multiple intratracheal instillations of BLM.Survival curves were plotted at day 56,and lung tis-sue was collected for lung coefficient calculation.Pathological changes in lung tissue were assessed using hematoxylin-eo-sin(H&E)staining and Masson staining.Indicators of lung fibrosis,such as hydroxyproline(HYP),were measured.Dif-ferentially expressed genes in patients with IPF were screened using the GEO database,and kyoto encyclopedia of genes and genomes(KEGG)pathway enrichment analysis was performed to identify pathways associated with IPF.Western blot was used to detect changes in these pathways in the lung tissues of the model mice.RESULTS:The survival rates were 50%in the BLM-MH group and 87.5%in the BLM-MM group,with no deaths in other groups.Compared with the control group,the BLM-MH and BLM-MM groups showed significantly increased lung coefficients(P＜0.05),lung tissue dam-age,inflammation levels,degree of pulmonary fibrosis(P＜0.05 or P＜0.01),and HYP content.The BLM-MH and BLM-MM groups,compared with the BLM-SM group,showed significantly elevated levels of inflammation,fibrosis,and HYP content(P＜0.05 or P＜0.01).GEO database and KEGG enrichment analysis revealed that the extracellular matrix-recep-tor interaction pathway(ECM-RIP)may be involved in IPF development.The expression levels of ECM-RIP pathway-re-lated proteins,such as phosphorylated focal adhesion kinase(p-FAK)and phosphorylated Src protein(p-Src),were in-creased in the lung tissues of the model mice compared with the control group.Compared with the BLM-SM group,the BLM-MH group exhibited significant increases in the protein levels of p-FAK and p-Src in the lung tissue(P＜0.05).CONCLUSION:The murine model of pulmonary fibrosis established through repeated intratracheal instillations of BLM effectively mimics the pathological characteristics of the disease,providing a valuable experimental model for the investiga-tion of idiopathic pulmonary fibrosis pathogenesis and for the development of therapeutic agents.