Effects of intratracheal exposure of 2-chloroethyl ethyl sulfide (CEES) on the activation of CCAAT-enhancer-binding protein (C/EBP) and its protection by antioxidant liposome

Abstract

Exposure of 2-chloroethyl ethyl sulfide (CEES) to guinea pigs causes lung injury by infiltration of neutrophils in interstitial lung spaces. A unique MAPK-regulated transcription factor, C/EBP (CCAAT-enhancer-binding protein), regulates the expression of intracellular adhesion molecule-1 (ICAM-1), involved in recruiting neutrophils in lung. The present study was to determine if CEES exposure causes activation of C/EBP, in particular the predominant β-isoform and if so whether it can be prevented by intratracheal delivery of an antioxidant liposome containing N-acetyl cysteine and tocopherols. Lung injury was developed in guinea pigs by intratracheal exposure of CEES (0.5 mg/kg). The antioxidant liposome was given intratracheally 5 min after CEES exposure, and the animals were sacrificed after 30 days. CEES exposure caused a 2.3-fold increase in the activation of C/EBP accompanied with a 45% and 121% increase in the protein level of C/EBP β and ICAM-1, respectively, and this effect was counteracted by the antioxidant liposome.

Keywords: 2-chloroethyl ethyl sulfide (CEES); C/EBP (CCAAT-enhancer-binding protein); ICAM-1; antioxidant liposome; lung injury.

FIGURE 1

Effects of antioxidant liposome treatment on CEES-induced alteration in lung morphology. Lungs were obtained after 30 days of single intratracheal instillation of either vehicle + LIP-1 or CEES (0.5 mg/kg b. wt.) + LIP 1 or CEES + LIP 2. Lung sections were obtained for histological examination by staining with H&E (top row, ×40 magnification) and trichrome (bottom row, ×40 magnification). In each plate, left shows blood vessels, middle shows bronchiole, and right shows alveoli.

FIGURE 2

Protection of CEES-induced activation of C/EBP β in lung by antioxidant liposome (LIP-2) as evident by ELISA assay on C/EBPα activation. *Statistically significant (P < 0.05) against vehicle + LIP-1 treatment.

FIGURE 3

Protection of CEES-induced increase in the levels of C/EBP β protein in lung by antioxidant liposome (LIP-2) as evident by Western blot analysis of the C/EBPβ protein. The graph represents normalized value of C/EBP β protein against actin. *Statistically significant (P < 0.05) against vehicle + LIP-1 treatment.

FIGURE 4

Protection of CEES-induced increase in the protein levels of ICAM-1 in lung by antioxidant liposome (LIP-2) as evident by Western blot analysis. The graph represents normalized value of ICAM-1 against actin. *Statistically significant (P < 0.05) against vehicle + LIP-1 treatment.