Abstract: Objective To investigate the pathologies and pathogenesis of interstitial lung disease (ILD) in experimental autoimmune myositis (EAM) models. Methods Established EAM mode by injecting the homogenate of rabbit skeletal muscle with Freund's complete adjuvant. The histopathological features of the muscle and lung from the EAM model were investigated by staining with hematoxylin and eosin and Masson's trichrome. The expressions of TRAIL and TRAIL receptors (TRAIL-R1, TRAIL-R2, TRAIL-R3, and TRAIL-R4) in lung tissues were measured by immunohistochemical method and computer image analysis. Result 16 of 45 rats with autoimmune inflammatory myopathies were found varying degrees of interstitial lung disease (P <0.05); TRAIL expression was increased in lung tissue (39265±27595) and that of DCR1 was decreased (37377±14126) (P <0.05); Inflammatory cells infiltrated locally were found with high expression of DCR2; Alveolitis was related with CD8 + T lymphocytes (P <0.001) and pulmonary fibrosis was related with TRAIL expression in lung tissues (P <0.05). Conclusion The study firstly demonstrates that the features of ILD shown in EAMs were related with the local immune inflammatory response. The changes in the expression of TRAIL and its receptors between EAMs and controls suggest TRAIL-system probably play a role in the pathogenesis and the pathology of IIM with ILD.

Key words: EAM, ILD, Histopathology, TRAIL and TRAIL receptors