Oxidative Stress Induced Age Dependent Meibomian Gland Dysfunction in Cu, Zn-Superoxide Dismutase-1 (Sod1) Knockout Mice

Purpose: The purpose of our study was to investigate alterations in the meibomian gland (MG) in Cu, Zn-Superoxide Dismutase-1 knockout (Sod12/2) mouse. Methods: Tear function tests [Break up time (BUT) and cotton thread] and ocular vital staining test were performed on Sod12/2 male mice (n = 24) aged 10 and 50 weeks, and age and sex matched wild–type (+/+) mice (n = 25). Tear and serum samples were collected at sacrifice for inflammatory cytokine assays. MG specimens underwent Hematoxylin and Eosin staining, Mallory staining for fibrosis, Oil Red O lipid staining, TUNEL staining, immunohistochemistry stainings for 4HNE, 8-OHdG and CD45. Transmission electron microscopic examination (TEM) was also performed. Results: Corneal vital staining scores in the Sod12/2 mice were significantly higher compared with the wild type mice throughout the follow-up. Tear and serum IL-6 and TNF-a levels also showed significant elevations in the 10 to 50 week Sod12/2 mice. Oil Red O staining showed an accumulation of large lipid droplets in the Sod12/2 mice at 50 weeks. Immunohistochemistry revealed both increased TUNEL and oxidative stress marker stainings of the MG acinar epithelium in the Sod12/2 mice compared to the wild type mice. Immunohistochemistry staining for CD45 showed increasing inflammatory cell infiltrates from 10 to 50 weeks in the Sod12/2 mice compared to the wild type mice. TEM revealed prominent mitochondrial changes in 50 week Sod12/2 mice