Mycoplasma pneumoniae Infection and Environmental Tobacco Smoke Inhibit Lung Glutathione Adaptive Responses and Increase Oxidative Stress

Abstract

Chronic cigarette smoking evokes a lung glutathione (GSH) adaptive response that results in elevated GSH levels in the lung epithelial lining fluid (ELF). Currently, little is known about how the lung regulates or maintains steady-state levels of ELF GSH. Pathogens such as Mycoplasma pneumoniae can exacerbate airway inflammation and oxidative stress. The present study examined whether M. pneumoniae infections synergize with environmental tobacco smoke (ETS) to disrupt lung GSH adaptive responses. Mice were exposed separately and in combination to ETS and M. pneumoniae for 16 weeks. ETS exposure resulted in a doubling of ELF GSH levels, which was blocked in the M. pneumoniae-exposed mice. In addition, the ETS-plus-M. pneumoniaeexposed mice had elevated levels of oxidized glutathione (GSSG), resulting in a dramatic change in the ELF redox state that corresponded with an increase in lung tissue DNA oxidation. Similar findings were observed in human lung epithelial cells in vitro. Cells exposed separately or in combination to cigarette smoke extract and M. pneumoniae for 48 h had elevated apical levels of GSH compared to control cells, and these increases were blocked by M. pneumoniae and were also associated with increased cellular DNA oxidation. Further studies showed that M. pneumoniae exposure blocked ETS-induced increases in GSH reductase, an enzyme that recycles GSSG back to GSH, both in vitro and in vivo. These studies suggest that M. pneumoniae infection synergizes with ETS and suppresses the lung's ability to respond appropriately to environmental challenges leading to enhanced oxidative stress.

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

“…After 24 hours exposure, we observed that CSE, even at a 5% concentration, was ineffective on GSH intracellular levels. This result is well in agreement with the findings of Pace et al showing that total intracellular glutathione is not affected after a 18 hours treatment [20], and has been observed also in other epithelial airway cells [14,47,48], even if not in all cell types [35,49,50]. It could be explained as a cell adaptive response to a chronic CSE exposure.…”

Selective Metabolism of Hypothiocyanous Acid by Mammalian Thioredoxin Reductase Promotes Lung Innate Immunity and Antioxidant Defense

“…Cells were plated at a density of 2.0 ϫ 10 5 cells/well on 24-well tissue culture plates (Corning) and allowed to adhere overnight. Viability was determined from lactate dehydrogenase release into the medium 24 h after the beginning of exposure as described previously (24).…”

Efficacy of Glutathione in Ameliorating Sulfur Mustard Analog-Induced Toxicity in Cultured Skin Epidermal Cells and in SKH-1 Mouse Skin In Vivo

“…Skin GSH levels were determined according to the protocol described previously (Kariya et al, 2008). In brief, skin tissues were weighed, sonicated on ice in KPBS buffer (50 mM potassium phosphate buffer, 17.5 mM EDTA, 50 mM serine, and 50 mM boric acid, pH 7.4), and incubated in the dark at room temperature for 30 min in the presence of monobromobimane (3 mM in acetonitrile).…”

“…The reaction was stopped by the addition of 70% perchloric acid. The samples were then centrifuged at 16,000g at 4°C for 10 min, and the supernatant was removed, transferred to a high-performance liquid chromatography vial, and analyzed for GSH on a Hitachi high-pressure liquid chromatograph (model L-2420; San Jose, CA) equipped with a fluorometric detector (model L-2480) as previously described with minor modifications, using excitation and emission wavelengths at 390 and 480 nm, respectively (Kariya et al, 2008).…”