Comparative cytoprotective effects of carbocysteine and fluticasone propionate in cigarette smoke extract-stimulated bronchial epithelial cells

Abstract

Cigarette smoke extracts (CSE) induce oxidative stress, an important feature in chronic obstructive pulmonary disease (COPD), and oxidative stress contributes to the poor clinical efficacy of corticosteroids in COPD patients. Carbocysteine, an antioxidant and mucolytic agent, is effective in reducing the severity and the rate of exacerbations in COPD patients. The effects of carbocysteine on CSE-induced oxidative stress in bronchial epithelial cells as well as the comparison of these antioxidant effects of carbocysteine with those of fluticasone propionate are unknown. The present study was aimed to assess the effects of carbocysteine (10 −4 M) in cell survival and intracellular reactive oxygen species (ROS) production (by flow cytometry) as well as total glutathione (GSH), heme oxygenase-1 (HO-1), nuclearrelated factor 2 (Nrf2) expression and histone deacetylase 2 (HDAC-2) expression/activation in CSE-stimulated bronchial epithelial cells (16-HBE) and to compare these effects with those of fluticasone propionate (10 −8 M). CSE, carbocysteine or fluticasone propionate did not induce cell necrosis (propidium positive cells) or cell apoptosis (annexin Vpositive/propidium-negative cells) in 16-HBE. CSE increased ROS production, nuclear Nrf2 and HO-1 in 16-HBE. Fluticasone propionate did not modify intracellular ROS production, GSH and HDCA-2 but reduced Nrf2 and HO-1 in CSE-stimulated 16-HBE. Carbocysteine reduced ROS production and increased GSH, HO-1, Nrf2 and HDAC-2 nuclear expression/activity in CSE-stimulated cells and was more effective than fluticasone propionate in modulating the CSEmediated effects. In conclusion, the present study provides compelling evidences that the use of carbocysteine may be considered a promising strategy in diseases associated with corticosteroid resistance.

Short- and Long- Term Effects of Cigarette Smoke Exposure on Glutathione Homeostasis in Human Bronchial Epithelial Cells

“…Accordingly, MTT assays allowed to demonstrate that cell proliferation is affected by CSE after an exposure of 24 hours in a dose-dependent manner. The CSE-related cell mortality increase is not due to an apoptotic process, well in agreement with the results presented by Pace et al [20] in the same cell type, where also a necrotic effect has been excluded. The exact mechanism by which cigarette smoke causes loss of the epithelial layer is still controversial.…”

“…The exact mechanism by which cigarette smoke causes loss of the epithelial layer is still controversial. In some cases no apoptosis or necrosis has been detected [20,39], while in other studies both apoptosis [40], necrosis [41] or senescence, a state of irreversible growth arrest [42] have been reported. The observed mortality of 16HBE cells after CSE exposure, that has been observed also in other cell types [43], could be due to a different form of cell death, i.e.…”

“…GSH intracellular levels are also influenced by the mucolytic drugs N-acetylcysteine and S-carboximethilcysteine, Lysine salt (S-CMC-Lys). S-CMC-Lys can act both by stimulating GSH efflux [16] and by increasing GSH cellular concentration, while reducing ROS intracellular levels in airway epithelial cells [15], thus having a possible cytoprotective effect [15,16,20].…”

Carbocisteine attenuates TNF-α-induced inflammation in human alveolar epithelial cells in vitro through suppressing NF-κB and ERK1/2 MAPK signaling pathways

“…It has also been reported that carbocisteine harbors other anti-inflammatory targets, such as nuclear factor-erythroid 2-related factor (Nrf2), which is a redox-sensitive transcription factor in COPD [37,38] that can be activated by TNF-α in certain cell lines [39] . Via the activation of Nrf2, carbocisteine attenuated inflammation in vivo after exposure to cigarette smoke following influenza virus infection [40] and alleviated cigarette smoke extract (CSE)-induced oxidative stress in vitro [5] . It remains to be further revealed whether Nrf2 is involved in the regulation of TNF-α-stimulated inflammation by carbocisteine.…”

“…Despite the lack of a free thiol group, carbocisteine harbors a thioether group that can be oxidized by reactive oxygen species (ROS) [4] . Carbocisteine reportedly scavenged H 2 O 2 , HOCl, OH* and ONOO -in cell-free medium, inhibited ROS production in rat neutrophils [4] , promoted GSH and HO-1 expression in cigarette smoke-exposed bronchial epithelial cells [5] , and ameliorated oxidant-induced 16HBE cell apoptosis [6] . Furthermore, carbocisteine was capable of attenuating the synthesis of pro-inflammatory cytokines following rhinovirus or respiratory syncytial virus infection [7,8] .…”