Rosemary (Rosmarinus officinalis) Extract Attenuates Methotrexate-Induced Oxidative Stress, Inflammatory Disturbance, and Apoptotic Lung Injury: A Molecular and Histopathological Study.

Methotrexate (MTX) is widely used as a chemotherapeutic and immunosuppressive agent, but its clinical use is limited by toxic effects associated with oxidative stress, inflammatory dysregulation, and apoptosis. Rosmarinus officinalis (rosemary) extract has documented antioxidant, anti-inflammatory, and cytoprotective properties. This study aimed to evaluate the protective effects of rosemary extract against MTX-induced lung injury through biochemical, histopathological, immunohistochemical, and molecular analyses. A total of 40 adult male Wistar rats were randomly allocated to four experimental groups (n = 10/group): Control, Rosemary, MTX, and Rosemary + MTX. Lung tissues were assessed for oxidative stress markers, including reactive oxygen species (ROS), malondialdehyde (MDA), and reduced glutathione (GSH); inflammatory cytokines (IL-6 and TNF-α); histopathological and immunohistochemical changes; and expression of apoptosis-related markers (p53 and Bcl-2). MTX significantly increased ROS, MDA, TNF-α, p53 gene expression, p53 immunoreactivity, and collagen deposition, while it decreased GSH, IL-6, and Bcl-2 expression compared with the control group (P < 0.05). Co-treatment with rosemary attenuated MTX-induced increases in ROS, MDA, TNF-α, p53 expression, collagen deposition, and histopathological injury, and partially restored GSH and Bcl-2 levels compared with the MTX group (P < 0.05). Compared with the control group, several measured parameters remained significantly altered in the Rosemary + MTX group according to Tukey post-hoc comparisons, indicating partial rather than complete recovery. Rosemary extract partially attenuated MTX-associated oxidative, cytokine, apoptosis-related, and histopathological alterations in rat lung tissue. Further mechanistic and translational studies are required.