Background: Cancer patients when treated with different chemotherapeutic drugs often develop mild to severe sight threatening diseases during or after chemotherapy. The mechanism involved in the pathogenesis of ocular toxicities is poorly understood. Oxidative stress, inflammation and MMPs (angiogenic factor) are involved in the progression of chemotherapy related ocular disorders.
Materials and methods: The concentration of oxidative stress markers such as MDA, NO and levels of different antioxidant molecules such as SOD, CAT, GSH, GPx, GPr, VIT A, VIT E and VIT C present in the serum of chemotherapy treated patients (n = 50) and in normal persons (n = 20) were estimated by the direct spectrophotometric method while the concentration of TNF-α and MMP-9 activity were determined using human TNF-α and MMP-9 ELISA kits.
Results: The concentration of SOD and CAT (0.356 ± 0.05 μg/dl and 1.26 ± 0.01 μmol/mol of protein) was significantly lower as compared to that (1.09 ± 0.03 μg/dl and 3.99 ± 0.04 μmol/mol of protein) in controls. The levels of GPx (0.06 ± 0.01 mmol/dl) in the cancer patients were much lower than those in the controls (0.78 ± 0.06 mmol/dl). Lower level of GSH (0.96 ± 0.003 μg/dl) in serum of the diseased group was observed as compared to healthy group (7.26 ± 1.40 μg/dl). The level of Vit A, Vit C and Vit E was lower in systemic circulation of cancer patients (109.99 ± 6.35 μg/ml, 1.26 ± 0.36 μg/ml and 1.29 ± 0.191 μg/ml) as compared to control subjects (166.35 ± 14.26 μg/ml, 3.25 ± 0.099 μg/ml and 6.354 ± 2.26 μg/ml) respectively. The concentration of nitric oxide was significantly higher in the cancer patients (45.26 ± 6.35 ng/ml) than that in the normal subjects (16.35 ± 3.26 ng/ml). The higher concentration of MDA (8.65 ± 3.26 nmol/ml) was observed in the patients than normal ones (1.254 ± 0.065 nmol/ml). The quantity of TNF-α was significantly higher in chemotherapy treated patients (32.68 ± 4.33 pg/ml) as compared to the control group (20.979 ± 1.98 pg/ml). Significantly higher concentration of MMP-9 (40.26 ± 3.26 ng/ml) was observed in the cancer patients than the controls (7.256 ± 1.95 ng/ml).
Conclusion: Lower levels of antioxidant enzymes and non-enzymatic small molecules and higher levels of oxidative stress and inflammatory clinical parameters such as NO, MDA, TNF-α and MMP-9 may be involved in the pathogenesis of systemic chemotherapy related ocular complications such as cataract, glaucoma, blepharitis, retinitis pigmentosa, macular degeneration, pterygium and retinal degeneration.
Keywords: Cancer; Chemotherapeutic drugs; HIV, human immunodeficiency virus; IL, interleukin; MDA, malondialdehyde; MMPs; MMPs, matrix metalloproteinases; NO, nitric oxide; Ocular complications; Oxidative stress; ROS, reactive oxygen species; TNF, tumor necrosis factor; TNF-α.