ABSTRACT
Objective To explore the effect of age factor on the degree of pulmonary fibrosis and on the change in telomerase reverse transcriptase(TERT) activity in mice.Methods A total of 80 healthy male C57BL/6 mice aged 20-weeks were randomized into 4 groups:a young pulmonary fibrosis model group(n=20),a young control group(n=20),a senile pulmonary fibrosis model group(n=20),and an elderly control group (n =20).Two model groups were induced by an intratracheally injected bleomycin in 5 mg/kg,and two control groups by an intratracheally injected normal saline.The elderly were defined as 26 weeks old mice.Five mouse pulmonary fibrosis models and five mouse controls in four groups were randomly selected and killed at 7,14,21,28 days.Lung tissue specimens were stained with hematoxylin eosin (HE)and Masson trichrome (Masson)method,and then pathological changes were observed.In addition,immunohisto-chemical staining was used to observe the expression levels of epithelial cell marker protein E-cadherin(E-cad),stromal cell marker protein Vimentin,and alpha smooth muscle actin(α-SMA).Finally,the expression level of telomerase reverse transcriptase(TERT)protein was detected by Western blotting.Results A bleomycin-induced pulmonary fibrosis mice model was successfully prepared.The degree of pulmonary fibrosis was more severe in old mice than in young mice.Compared with the young pulmonary fibrosis model group,the expression level of E-Cad was decreased in the senile pulmonary fibrosis model group(P ＜0.05).Compared with the young control group and the elderly control group,the expression levels of E-Cad in the young pulmonary fibrosis model group and the senile pulmonary fibrosis model group were decreased (P ＜ 0.05),and decreased along with the prolongation of the modeling time.Compared with the young pulmonary fibrosis model group,the expression levels of alpha-SMA and vimentin were increased in the senile pulmonary fibrosis model group(P ＜ 0.05).The expression levels of alpha-SMA and vimentin were increased in the young pulmonary fibrosis model group and the senile pulmonary fibrosis model group,as compared to the young control group and the elderly control group(P＜0.05),and increased along with the prolongation of the modeling time.The activity of TERT in lung tissue of mice was increased at first and then decreased.Compared with the young pulmonary fibrosis model group,the activity of TERT in the senile pulmonary fibrosis model group significantly fluctuated(P＜0.05).Conclusions Age factor can affect the severity of pulmonary fibrosis by affecting the activity of telomerase reverse transcriptase in mouse models of pulmonary fibrosis.