The impact of surfactant protein-A on ozone-induced changes in the mouse bronchoalveolar lavage proteome

Abstract

BackgroundOzone is a major component of air pollution. Exposure to this powerful oxidizing agent can cause or exacerbate many lung conditions, especially those involving innate immunity. Surfactant protein-A (SP-A) plays many roles in innate immunity by participating directly in host defense as it exerts opsonin function, or indirectly via its ability to regulate alveolar macrophages and other innate immune cells. The mechanism(s) responsible for ozone-induced pathophysiology, while likely related to oxidative stress, are not well understood.MethodsWe employed 2-dimensional difference gel electrophoresis (2D-DIGE), a discovery proteomics approach, coupled with MALDI-ToF/ToF to compare the bronchoalveolar lavage (BAL) proteomes in wild type (WT) and SP-A knockout (KO) mice and to assess the impact of ozone or filtered air on the expression of BAL proteins. Using the PANTHER database and the published literature most identified proteins were placed into three functional groups.ResultsWe identified 66 proteins and focused our analysis on these proteins. Many of them fell into three categories: defense and immunity; redox regulation; and protein metabolism, modification and chaperones. In response to the oxidative stress of acute ozone exposure (2 ppm; 3 hours) there were many significant changes in levels of expression of proteins in these groups. Most of the proteins in the redox group were decreased, the proteins involved in protein metabolism increased, and roughly equal numbers of increases and decreases were seen in the defense and immunity group. Responses between WT and KO mice were similar in many respects. However, the percent change was consistently greater in the KO mice and there were more changes that achieved statistical significance in the KO mice, with levels of expression in filtered air-exposed KO mice being closer to ozone-exposed WT mice than to filtered air-exposed WT mice.ConclusionWe postulate that SP-A plays a role in reactive oxidant scavenging in WT mice and that its absence in the KO mice in the presence or absence of ozone exposure results in more pronounced, and presumably chronic, oxidative stress.

Sex differences in the acute in vivo effects of different human SP-A variants on the mouse alveolar macrophage proteome

“…We employed an approach similar to that used in previous publications and with other types of samples (BAL proteins, plasma proteins) [24,25,27,29] to assess the function of the 90 identified proteins and their biological relevance to AM function. A general overview of function was provided by analyzing the data with the Ingenuity Pathways Analysis (IPA) program.…”

Sec14l3 Is Specifically Expressed in Mouse Airway Ciliated Cells

“…Such studies have revealed that Sec14l3 mRNA levels are reduced following human rhinovirus infection [27] or as a result of smoking [28,29]. Sec14l3 protein levels were also reduced after naphthalene-induced airway injury [30] or due to ozone-charged oxidation in mice [31]. Klebsiella pneumoniae infection induced the reduction of Sec14l3 protein levels 24 h post infection [32].…”

In vivo rescue of alveolar macrophages from SP-A knockout mice with exogenous SP-A nearly restores a wild type intracellular proteome; actin involvement

“…These include SP-A effects on the regulation of allergic or inflammatory responses [3,120,122,131,132] and other host defense molecules [20,125], as well as the ability of exogenous SP-A to restore tubular myelin, an extracellular form of surfactant [121]. This diversity of effects, along with our BAL proteomic studies [26,42], indicate that SP-A exerts a pleiotropic effect in lung biology and/or health. The observations from the present study not only provide support for an SP-A pleiotropic effect on lung biology, but identify many protein molecules and pathways affected by the interaction of SP-A with the alveolar macrophage.…”