Figure 2: SOD1, COX2, and Collagen (Type I) expression in lung. Immunohistochemical labelling for SOD1 (a–d), COX2 (e–h), and Collagen (i–n) in pulmonary tissues of control (a, e and i), CdCl2- (b, f and l), SiNPs- Cd- (c, g, m), and SiNPs-treated rats (d, h, n), 7 and 30 days after i.t. exposure. SOD1 was clearly detectable after both CdCl2 and SiNPs-Cd, still at 7 and lasting until 30 days (b and c, respectively), mainly localized at alveolar macrophages level (arrows). COX2 expression was markedly enhanced at 7 as well as at 30 days, after both CdCl2 and SiNPs-Cd (f and g) compared to control, primarily detected in the alveolar wall, both at capillary and epithelial levels (arrows). The Collagen labelling changes appeared evident particularly 7 and 30 days after both CdCl2 and SiNPs-Cd (l and m, respectively) and 30 days after SiNPs (n) exposure, with a strong stromal fibrogenic reaction characterized by a diffuse enhanced collagen storage (ln). Objective magnification: 40 x (a-n).