Ammonia exposure by intratracheal instillation causes severe and deteriorating lung injury and vascular effects in mice.

OBJECTIVE: Ammonia (NH3) is a corrosive alkaline gas that can cause life-threatening injuries by inhalation. The aim was to establish a disease model for NH3-induced injuries similar to acute lung injury (ALI) described in exposed humans and investigate the progression of lung damage, respiratory dysfunction and evaluate biomarkers for ALI and inflammation over time. METHODS: Female BALB/c mice were exposed to an NH3 dose of 91.0 mg/kg·bw using intratracheal instillation and the pathological changes were followed for up to 7 days. RESULTS: NH3 instillation resulted in the loss of body weight along with a significant increase in pro-inflammatory mediators in both bronchoalveolar lavage fluid (e.g. IL-1ß, IL-6, KC, MMP-9, SP-D) and blood (e.g. IL-6, Fibrinogen, PAI-1, PF4/CXCL4, SP-D), neutrophilic lung inflammation, alveolar damage, increased peripheral airway resistance and methacholine-induced airway hyperresponsiveness compared to controls at 20 h. On day 7 after exposure, deteriorating pathological changes such as increased macrophage lung infiltration, heart weights, lung hemorrhages and coagulation abnormalities (elevated plasma levels of PAI-1, fibrinogen, endothelin and thrombomodulin) were observed but no increase in lung collagen. Some of the analyzed blood biomarkers (e.g. RAGE, IL-1ß) were unaffected despite severe ALI and may not be significant for NH3-induced damages. CONCLUSIONS: NH3 induces severe acute lung injuries that deteriorate over time and biomarkers in lungs and blood that are similar to those found in humans. Therefore, this model has potential use for developing diagnostic tools for NH3-induced ALI and for finding new therapeutic treatments, since no specific antidote has been identified yet.

N-acetyl cysteine protects against chlorine-induced tissue damage in an ex vivo model.

High-level concentrations of chlorine (Cl2) can cause life-threatening lung injuries and the objective in this study was to understand the pathogenesis of short-term sequelae of Cl2-induced lung injury and to evaluate whether pre-treatment with the antioxidant N-acetyl cysteine (NAC) could counteract these injuries using Cl2-exposed precision-cut lung slices (PCLS). The lungs of Sprague-Dawley rats were filled with agarose solution and cut into 250 µm-thick slices that were exposed to Cl2 (20-600 ppm) and incubated for 30 min. The tissue slices were pre-treated with NAC (5-25 mM) before exposure to Cl2. Toxicological responses were analyzed after 5 h by measurement of LDH, WST-1 and inflammatory mediators (IL-1ß, IL-6 and CINC-1) in medium or lung tissue homogenate. Exposure to Cl2 induced a concentration-dependent cytotoxicity (LDH/WST-1) and IL-1ß release in medium. Similar cytokine response was detected in tissue homogenate. Contraction of larger airways was measured using electric-field-stimulation method, 200 ppm and control slices had similar contraction level (39 ± 5%) but in the 400 ppm Cl2 group, the evoked contraction was smaller (7 ± 3%) possibly due to tissue damage. NAC-treatment improved cell viability and reduced tissue damage and the contraction was similar to control levels (50 ± 11%) in the NAC treated Cl2-exposed slices. In conclusion, Cl2 induced a concentration-dependent lung tissue damage that was effectively prevented with pre-treatment with NAC. There is a great need to improve the medical treatment of acute lung injury and this PCLS method offers a way to identify and to test new concepts of treatment of Cl2-induced lung injuries.

Human primary bronchial epithelial cells respond differently to titanium dioxide nanoparticles than the lung epithelial cell lines A549 and BEAS-2B.

We have compared the cellular uptake and responses of five preparations of nanocrystalline titanium dioxide (TiO(2)) between normal human bronchial epithelial (NHBE) cells and epithelial cell lines (A549 and BEAS-2B). The P25 nanoparticles, containing both anatase and rutile modifications, induced reactive oxygen species (ROS) and secretion of the neutrophil chemoattractant IL-8 in all three cell types used. Pure anatase and rutile particles provoked differential IL-8 response in A549 and no response in BEAS-2B cells despite similar formation of ROS. The pure TiO(2) modifications also provoked release of the inflammatory mediators: IL-6, G-CSF and VEGF, in NHBE cells but not in the two cell lines. We conclude that the responsiveness of lung epithelial cells is strongly dependent on both the physicochemical properties of TiO(2) nanoparticles and the type of responder cells. The differential pro-inflammatory responsiveness of primary lung epithelial cells compared with immortalized cell lines should be considered in the assessment of adverse reactions to inhaled nanoparticles.

Polymorph- and size-dependent uptake and toxicity of TiO2 nanoparticles in living lung epithelial cells.

The cellular uptake and distribution of five types of well-characterized anatase and rutile TiO(2) nanoparticles (NPs) in A549 lung epithelial cells is reported. Static light scattering (SLS), in-vitro Raman microspectroscopy (µ-Raman) and transmission electron spectroscopy (TEM) reveal an intimate correlation between the intrinsic physicochemical properties of the NPs, particle agglomeration, and cellular NP uptake. It is shown that µ-Raman facilitates chemical-, polymorph-, and size-specific discrimination of endosomal-particle cell uptake and the retention of particles in the vicinity of organelles, including the cell nucleus, which quantitatively correlates with TEM and SLS data. Depth-profiling µ-Raman coupled with hyperspectral data analysis confirms the location of the NPs in the cells and shows that the NPs induce modifications of the biological matrix. NP uptake is found to be kinetically activated and strongly dependent on the hard agglomeration size-not the primary particle size-which quantitatively agrees with the measured intracellular oxidative stress. Pro-inflammatory responses are also found to be sensitive to primary particle size.