Expressions of Th17 cell in rat model of pulmonary fibrosis

Objective:To investigate expressions of Th17 cell in rat model of pulmonary fibrosis(PF).Methods:Totally 54 SD rats were randomly divided into 3 groups:control group(N group,n=18),PF model group(B group,n=18)and dexmethasone treated group(D group).B and D groups were established by a single intra-tracheal injection of 5 mg/kg of bleomycin.N group received intra-tracheal instillation of saline instead.The next day D group was injected with dexamethasone(3 mg/kg)intraperitoneally every other day while N and B groups were injected with saline.Rats were sacrificed at the 7th,14 th,28th d after modeling in batch.Lung tissues were restored to analyze the pathological changes with HE staining and levels of hydroxyproline(HYP)in pulmonary tissues were determined. Proportion of CD4 + IL-17 + Th17 cells in the lung was evaluated by flow cytometry.Levels of serum interleukin-17(IL-17)were measured by ELISA.Results:①In B group,biopsy of pulmonary tissues showed the dynamic process of change from pulmonary alveolitis to PF gradually.Levels of HYP in pulmonary tissues were higher in B group(the highest on the 28th d)than in N and D groups(P 0.05).②Th17 cell was lowly expressed in N group.Expressions of Th17 cell in pulmonary tissues and serum IL-17 were significantly higher in B and D groups than in N group at all time points(P0.05),being most obviously at the 7th d.Conclusions:PF is developed by inflammatory damage and repair and has different pathological characteristics at different time points.Increased expressions of Th17 cell in pulmonary tissues of PF rats and serum IL-17 are associated with pulmonary inflammation and PF.