Protection of half sulfur mustard gas–induced lung injury in guinea pigs by antioxidant liposomes

Abstract

The purpose of this study was to develop antioxidant liposomes as an antidote for mustard gas-induced lung injury in a guinea pig model. Five liposomes (LIP-1, LIP-2, LIP-3, LIP-4, and LIP-5) were tested with differing levels of phospholipid, cholesterol, phosphatidic acid, tocopherol (alpha, gamma, delta), N-acetylcysteine (NAC), and glutathione (GSH). A single dose (200 microL) of liposome was administered intratracheally 5 min or 1 h after exposure to 2-chloroethyl ethyl sulfide (CEES). The animals were sacrificed either 2 h after exposure (for lung injury study) or 30 days after exposure (for histology study). The liposomes offered 9%-76% protection against lung injury. The maximum protection was with LIP-2 (71.5% protection) and LIP-4 (75.4%) when administered 5 min after CEES exposure. Delaying the liposome administration 1 h after CEES exposure decreased the efficacy. Both liposomes contained 11 mM alpha-tocopherol, 11 mM gamma-tocopherol, and 75 mM NAC. However, LIP-2 contained additionally 5 mM delta-tocopherol. Overall, LIP-2 and LIP-4 offered significant protection by controlling the recruitment of neutrophils, eosinophils, and the accumulation of septal and perivascular fibrin and collagen. However, LIP-2 showed better protection than LIP-4 against the accumulation of red blood cells in the bronchi, alveolar space, arterioles and veins, and fibrin and collagen deposition in the alveolar space. The antifibrotic effect of the liposomes, particularly LIP-2, was further evident by a decreased level of lipid peroxidation and hydroxyproline in the lung. Thus, antioxidant liposomes containing both NAC and vitamin E are an effective antidote against CEES-induced lung injury.

Role of MAPK/AP-1 signaling pathway in the protection of CEES-induced lung injury by antioxidant liposome

“…This protection was associated with inhibition of CEES-induced activation of TNF-␣, NF-B, and reactive oxygen species . A similar protection against CEES-induced lung injury with antioxidant liposomes containing NAC and tocopherols (␣, ␥, ␦) was demonstrated in our laboratory recently (McClintock et al, 2006;Mukherjee et al, 2009).…”

“…This notion was further evident by the attenuative effects of antioxidant liposome containing NAC and tocopherols on CEES-induced lung injury Mukherjee et al, 2009). Our previous study also reported that CEES exposure not only initiate a series of signaling events but also causes oxidative stress Das et al, 2003).…”

“…Similarly 5 min after CEES exposure, the animals of groups 3 and 5 received LIP2 (200 l) and sacrificed after 1 h and 30 days post CEES exposure, respectively. Since there was no difference in lung morphology between 1 h and 30-day control groups (Mukherjee et al, 2009), we did not include any control group for 30 days post vehicle exposure in this study. Lungs were perfused with 2.6 mM phosphate buffered saline containing 5.6 mM glucose, removed from the chest cavity and immediately flash frozen in liquid nitrogen and stored at −80 • C for further experiment.…”

“…Morphological assessment of lung tissues was carried out as described before (Mukherjee et al, 2009). Briefly, a portion of lung tissue was fixed over night in neutral buffered formalin (10%), pH 7.2, and embedded in paraffin for light microscopy.…”

“…The antioxidant liposome was prepared as described elsewhere (Mukherjee et al, 2009). The blank liposome (LIP1) contained only soybean phospholipids, cholesterol and phosphatidic acid in mole fraction ratio of 71:28:0.67, respectively, and no antioxidant.…”