MnTMPyP inhibits paraquat-induced pulmonary epithelial-like cell injury by inhibiting oxidative stress

Abstract

Objective : To investigate the protective effect and underlying mechanism of the superoxide dismutase mimic, manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride (MnTMPyP), on paraquat (PQ)-induced lung alveolar epithelial-like cell injury. Methods : Lung alveolar epithelial-like cells (A549) were pretreated with 10 μM MnTMPyP for 1.5 hr and then cultured with or without PQ (750 uM) for 24 hr. Cell survival was determined using the MTT assay. Apoptosis, mitochondrial transmembrane potential, reactive oxygen species (ROS) production, and Ca²⁺ levels were measured using flow cytometry. Glutathione reductase activity (GR activity) and caspase-3 activation were determined using spectrophotometry. Expression of the apoptosis proteins, Bcl-2 and Bax, and the endoplasmic reticulum (ER) stress proteins, glucose regulatory protein 78 (Grp78) and C/EBP homologous protein (CHOP), was measured using Western blot analysis. Results : Cell viability, mitochondrial membrane potential, GR activity, and Bcl-2 expression were decreased, but apoptosis, ROS production, caspase-3 activity, cytoplasmic Ca²⁺ levels, and Bax, Grp78 and CHOP expression were all increased in the PQ group compared to the control group. There were no statistically significant changes in the MnTMPyP group. Cell viability, GR activity, mitochondrial membrane potential, and Bcl-2 protein expression were all increased, while apoptosis, ROS production, cytoplasmic Ca²⁺ levels, caspase-3 activity, and Bax, Grp78 and CHOP expression were all significantly reduced in the MnTMPyP group compared to PQ group. Conclusion : MnTMPyP effectively reduced PQ-induced lung epithelial-like cell injury, and the underlying mechanism is related to antagonism of PQ-induced oxidative stress.