Figure 1: NRG treatment decreased M. pneumonia-induced lung injury in mice by inhibiting inflammatory cytokine expression and pulmonary fibrosis. (a) Chemical structure of NRG. (b–d) Inflammatory cytokines IL-6 (b), IL-1β (c), TNF-α (d), and fibrosis factor TGF-β (e) concentrations in mice serum were measured with ELISA. Data are presented as the mean ± SD with Tukey–Kramer multiple comparison test analysis. . versus ctrl group; , versus MPP group. (f and g) Immunohistochemistry shows the presence of apoptosis (TUNEL staining) (f) and fibrosis (Masson trichrome staining) (g) in lung tissues. The results show that NRG treatment significantly suppressed the MPP-induced apoptosis and fibrosis. In Masson trichrome staining group, the collagen fibers were stained in blue. In TUNEL staining group, the nucleus of apoptosis cell was stained in brown.