Prolonged Injury and Altered Lung Function after Ozone Inhalation in Mice with Chronic Lung Inflammation

Abstract

Surfactant protein-D (Sftpd) is a pulmonary collectin important in down-regulating macrophage inflammatory responses. In these experiments, we analyzed the effects of chronic macrophage inflammation attributable to loss of Sftpd on the persistence of ozoneinduced injury, macrophage activation, and altered functioning in the lung. Wild-type (Sftpd 1/1 ) and Sftpd 2/2 mice (aged 8 wk) were exposed to air or ozone (0.8 parts per million, 3 h). Bronchoalveolar lavage (BAL) fluid and tissue were collected 72 hours later. In Sftpd 2/2 mice, but not Sftpd 1/1 mice, increased BAL protein and nitrogen oxides were observed after ozone inhalation, indicating prolonged lung injury and oxidative stress. Increased numbers of macrophages were also present in BAL fluid and in histologic sections from Sftpd 2/2 mice. These cells were enlarged and foamy, suggesting that they were activated. This conclusion was supported by findings of increased BAL chemotactic activity, and increased expression of inducible nitric oxide synthase in lung macrophages. In both Sftpd 1/1 and Sftpd 2/2 mice, inhalation of ozone was associated with functional alterations in the lung. Although these alterations were limited to central airway mechanics in Sftpd 1/1 mice, both central airway and parenchymal mechanics were modified by ozone exposure in Sftpd 2/2 mice. The most notable changes were evident in resistance and elastance spectra and baseline lung function, and in lung responsiveness to changes in positive endexpiratory pressure. These data demonstrate that a loss of Sftpd is associated with prolonged lung injury, oxidative stress, and macrophage accumulation and activation in response to ozone, and with more extensive functional changes consistent with the loss of parenchymal integrity. Keywords: ozone; surfactant protein-D; macrophages; iNOS; lung functionOzone is a ubiquitous urban air pollutant generated as a component of photochemical smog. Inhaled ozone causes ozonation and the peroxidation of proteins and lipids in the epithelial lining fluid layer of the lung, resulting in the production of oxidized proteins, aldehydes, and free radicals, which can damage surrounding tissue (1, 2). This is accompanied by an accumulation of activated macrophages in the lung and the production of additional cytotoxic and proinflammatory mediators, including reactive oxygen and reactive nitrogen species (ROS and RNS, respectively) that contribute to tissue injury (3). Airway and tissue mechanics are also altered after ozone exposure. Thus, in humans, ozone inhalation leads to a deterioration of pulmonary function, as measured by decreases in respiratory frequency, forced expiratory volume in 1 second, and forced vital capacity, and increases in airway resistance (1,4,5). Ozone has been shown to exacerbate asthma and increase airway hyperreactivity (5, 6), and to contribute to increased morbidity and mortality in patients with chronic obstructive pulmonary disease (COPD) (7,8). Similar alterations in lung function and increases in sensitivity to ozone have b...

Age-related increases in ozone-induced injury and altered pulmonary mechanics in mice with progressive lung inflammation

“…Moreover, macrophage inflammation increases with age in these mice, findings consistent with an important regulatory role of Sftpd in innate immunity (48). In previous studies we showed that low-level pulmonary inflammation accompanying loss of Sftpd in young mice is correlated with prolonged injury, oxidative stress, and altered pulmonary mechanics in response to inhaled ozone (18). The effects of chronic and progressive inflammation and the development of emphysema, which mimics biological responses in humans (6), on the response to inhaled ozone are unknown and were investigated in aging Sftpd Ϫ/Ϫ mice.…”

“…A DAB Peroxidase Substrate Kit (Vector Labs) was used to visualize binding. The number of positively staining macrophages and type 2 cells was quantified microscopically for each slide, as previously described (18). Each enumerated cell was assigned a staining intensity score on a scale of 0 -4 with 0 ϭ no staining, 1 ϭ light staining, 2 ϭ medium staining, 3 ϭ dark staining.…”

“…For nonparametric data, a Mann-Whitney rank sum test was performed. For each resistance and elastance spectra, a best fit line was generated as previously described (18). For hypothesis testing using the mechanical impedance data, the residual error from curve fitting with nonlinear regression was used as a measure of goodness of fit.…”

Low-dose AgNPs reduce lung mechanical function and innate immune defense in the absence of cellular toxicity

“…The supernatant was collected for protein and lipid analysis. The cell pellet was re-suspended in 1mL buffered saline for cytology and RT-PCR (Atochina-Vasserman et al, 2009; Casey et al, 2005; Groves et al, 2012). …”

The Effect of Particle Deposition on Immunological Response as Measured by Cytokine Production

“…The primary mechanism of clearance, at the alveolar surface, is via the activity of the alveolar macrophages (Forman et al, 1980(Forman et al, , 1982Hartmann et al, 1984;Stringer et al, 1995;Bates and Fisher, 1996;Kaul and Forman, 1996;Yagisawa et al, 1996;Tang et al, 2001;Iles et al, 2002;Jimenez et al, 2002;Quintero and Wright, 2002;Tao and Kobzik, 2002;Chin et al, 2003;Hjort et al, 2003;Laskin et al, 2003;Fakhrzadeh et al, 2004a,b;Rao et al, 2004;Kanj et al, 2005Kanj et al, , 2006Rothen-Rutishauser et al, 2005;Hu et al, 2006Hu et al, , 2007Sunil et al, 2007;Baker et al, 2008;Gaschler et al, 2008;Geiser et al, 2008;Manzer et al, 2008;Naito et al, 2008;Yamasaki et al, 2008;Jordan et al, 2009;Kuronuma et al, 2009;Pauluhn, 2009;Ryman-Rasmussen et al, 2009;Woodruff et al, 2009;Hoogerwerf et al, 2010;Snyder et al, 2010;Fuchimoto et al, 2011;Hristova et al, 2011;Poole et al, 2011;Groves et al, 2012;…”