Phosgene Inhalation Research Articles

Phosgene Inhalation in Fire-Related Deaths: A Case Report of Two Lovers Burnt in a Travelling Carousel

Phosgene Inhalation in Fire-Related Deaths: A Case Report of Two Lovers Burnt in a Travelling Carousel

Alpha-1 antitrypsin protects against phosgene-induced acute lung injury by activating the ID1-dependent anti-inflammatory response

Phosgene is widely used as an industrial chemical, and phosgene inhalation causes acute lung injury (ALI), which may further progress into pulmonary edema. Currently, an antidote for phosgene poisoning is not known. Alpha-1 antitrypsin (α1-AT) is a protease inhibitor used to treat patients with emphysema who are deficient in α1-AT. Recent studies have revealed that α1-AT has both anti-inflammatory and anti-SARS-CoV-2 effects. Herein, we aimed to investigate the role of α1-AT in phosgene-induced ALI. We observed a time-dependent increase in α1-AT expression and secretion in the lungs of rats exposed to phosgene. Notably, α1-AT was derived from neutrophils but not from macrophages or alveolar type II cells. Moreover, α1-AT knockdown aggravated phosgene- and lipopolysaccharide (LPS)-induced inflammation and cell death in human bronchial epithelial cells (BEAS-2B). Conversely, α1-AT administration suppressed the inflammatory response and prevented death in LPS- and phosgene-exposed BEAS-2B cells. Furthermore, α1-AT treatment increased the inhibitor of DNA binding 1 (ID1) gene expression, which suppressed NF-κB pathway activation, reduced inflammation, and inhibited cell death. These data demonstrate that neutrophil-derived α1-AT acts as a self-protective mechanism, which protects against phosgene-induced ALI by activating the ID1-dependent anti-inflammatory response. This study may provide novel strategies for the treatment of patients with phosgene-induced ALI.

Single-Cell RNA-Sequencing Reveals Epithelial Cell Signature of Multiple Subtypes in Chemically Induced Acute Lung Injury.

Alveolar epithelial cells (AECs) play a role in chemically induced acute lung injury (CALI). However, the mechanisms that induce alveolar epithelial type 2 cells (AEC2s) to proliferate, exit the cell cycle, and transdifferentiate into alveolar epithelial type 1 cells (AEC1s) are unclear. Here, we investigated the epithelial cell types and states in a phosgene-induced CALI rat model. Single-cell RNA-sequencing of bronchoalveolar lavage fluid (BALF) samples from phosgene-induced CALI rat models (Gas) and normal controls (NC) was performed. From the NC and Gas BALF samples, 37,245 and 29,853 high-quality cells were extracted, respectively. All cell types and states were identified and divided into 23 clusters; three cell types were identified: macrophages, epithelial cells, and macrophage proliferating cells. From NC and Gas samples, 1315 and 1756 epithelial cells were extracted, respectively, and divided into 11 clusters. The number of AEC1s decreased considerably following phosgene inhalation. A unique SOX9-positive AEC2 cell type that expanded considerably in the CALI state was identified. This progenitor cell type may develop into alveolar cells, indicating its stem cell differentiation potential. We present a single-cell genome-scale transcription map that can help uncover disease-associated cytologic signatures for understanding biological changes and regeneration of lung tissues during CALI.

Effects of over-expressing heat shock protein 60 on marrow mesenchymal stem cells in the treatment of phosgene-induced acute lung injury

Objective: To investigate the effect of heat shock protein 60 (HSP60) overexpression on the ability of bone marrow mesenchymal stem cells (MSCs) and its therapeutic effect on rats with phosgene induced acute lung injury. Methods: HSP60 was transfected into MSCs by adenovirus. Western blot was used to measure the expressions of HSP60 before and after transfection. CCK-8 assay was used to detect the activity of MSCs, flow cytometry was used to detect the apoptotic ability of MSCs, and Transwell assay was used to observe the migration ability of MSCs. Sixty SPF grade male SD rats were randomly divided into control group, phosgene exposure group (inhalation of phosgene for 5 min) , MSCs group (phosgene exposure, MSCs treatment group) and transfected MSCs group (phosgene exposure, overexpression of HSP60 MSCs treatment group) . The pathological changes of lung were observed by lung pathological section, lung wet dry ratio, the degree of pulmonary edema, the total cell count and total protein content of alveolar lavage fluid, the inflammatory changes of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in BALF and serum were observed. The data were analyzed by Graphpad Prism 8.0 software. Paired comparisons were performed by non paired t-test. One way ANOVA was used for comparison between groups. Results: The proliferation ability of MSCs transfected with HSP60[A= (0.69±0.05) ] was significantly higher than that of MSCs not transfected with HSP60[A= (0.27±0.02) ] (P<0.05) . Compared with the phosgene exposure group, the pulmonary edema and inflammatory factor infiltration of MSCs group and MSCs transfected group were reduced. However, compared with MSCs group, the degree of pulmonary edema in MSCs transfected group was significantly improved, the levels of inflammatory factors IL-6 and TNF-α were significantly decreased, and the total protein content and total cell count in bronchoalveolar lavage fluid were less (P<0.05) . Conclusion: MSCs transfected with HSP60 can enhance the ability of proliferation, anti apoptosis, migration and the curative effect in rats with phosgene induced acute lung injury.

Protective role of mesenchymal stem cells transfected with miRNA-378a-5p in phosgene inhalation lung injury

Phosgene-induced lung injury is an important type of acute lung injury (ALI). Currently, no effective clinical treatment has been developed yet. Our previous study revealed that expressions of 6 miRNAs were significantly increased in phosgene-induced lung injury. The screened miRNA with the most significant effect on hepatocyte growth factor (HGF) expression by mesenchymal stem cells (MSCs) was transfected into MSCs. This study aimed to investigate whether the transfected MSCs had better therapeutic effects than MSCs alone. MSCs were co-cultured with miRNA mimics for 24h and 48h. HGF expression in culture supernatant was detected by ELISA. HGF expression in MSCs was detected by Western blot after being co-cultured with the selected miRNA inhibitor. The transfected MSCs were given to rats suffering from phosgene-induced lung injury. Expressions of TNF-α, IL-6, IL-1β and IL-10, were assayed by ELISA. SP-C mRNA level was tested by RT-PCR. VE-CAD expression was tested by Western blot. We found that miRNA-378a-5p most increased HGF expression among the six miRNAs. After transfection of MSCs with miRNA-378a-5p inhibitor, HGF expression was decreased. Compared with untreated MSCs, MSCs transfected with miRNA-378a-5p exhibited more significant decreases in lung injury score, white blood cell count and protein content while restoring respiratory indexes. Meanwhile, expressions of TNF-α, IL-6, IL-1β were decreased while those of IL-10, SP-C and VE-cadherin were increased. In conclusion, MSCs transfected with miRNA-378a-5p were more effective in treating phosgene-induced lung injury by repairing the secretion of alveolar epithelial cells and improving the permeability of vascular endothelial cells compared with MSCs alone.

Phosgene inhalation causes hemolysis and acute lung injury

Phosgene (Carbonyl Chloride, COCl2) remains an important chemical intermediate in many industrial processes such as combustion of chlorinated hydrocarbons and synthesis of solvents (degreasers, cleaners). It is a sweet smelling gas, and therefore does not prompt escape by the victim upon exposure. Supplemental oxygen and ventilation are the only available management strategies. This study was aimed to delineate the pathogenesis and identify novel biomarkers of acute lung injury post exposure to COCl2 gas. Adult male and female C57BL/6 mice (20–25 g), exposed to COCl2 gas (10 or 20 ppm) for 10 min in environmental chambers, had a dose dependent reduction in PaO2 and an increase in PaCO2, 1 day post exposure. However, mortality increased only in mice exposed to 20 ppm of COCl2 for 10 min. Correspondingly, these mice (20 ppm) also had severe acute lung injury as indicated by an increase in lung wet to dry weight ratio, extravasation of plasma proteins and neutrophils into the bronchoalveolar lavage fluid, and an increase in total lung resistance. The increase in acute lung injury parameters in COCl2 (20 ppm, 10 min) exposed mice correlated with simultaneous increase in oxidation of red blood cells (RBC) membrane, RBC fragility, and plasma levels of cell-free heme. In addition, these mice had decreased plasmalogen levels (plasmenylethanolamine) and elevated levels of their breakdown product, polyunsaturated lysophosphatidylethanolamine, in the circulation suggesting damage to cellular plasma membranes. This study highlights the importance of free heme in the pathogenesis of COCl2 lung injury and identifies plasma membrane breakdown product as potential biomarkers of COCl2 toxicity.

Role of Notch signaling pathway in bone marrow mesenchymal stem cell therapy for phosgene inhalationinduced lung injury in rats

Purpose: To determining the expression and role of the Notch signaling pathway (NSP) in phosgene inhalation-induced lung injury in rats, and the therapeutic effect of bone marrow mesenchymal stem cell (MSC) on the lung lesions.Methods: Wistar rats (220 - 280 g) were randomly assigned to air inhalation group, phosgene inhalation group, and mesenchymal stem cell (MSC) intervention group. Each group had 8 rats. Directional flow phosgene inhalation device was used to produce phosgene inhalation-induced lung injury in the rats. Serum inflammatory cytokines (TNF-α, IL-8 and IL-6) were determined using ELISA assay kits. The expressions of proteins related to the NSP (Notch1, Notch2, Hes1, Hes5) were quantified using Western blot.Results: Phosgene inhalation brought about significant increase in TNF-α, IL-8 and IL-6 levels (p < 0.01), but MSC intervention significantly reduced the expressions of these inflammatory factors to varying degrees (p < 0.05), although their levels were still significantly high, relative to the air inhalation group. Results from western blot showed that the Notch1, Notch2, Hes1 and Hes5 were upregulated in the phosgene inhalation group, when relative to the air inhalation group (p < 0.01). Protein expressions in the MSC intervention group were lower than those in the non-intervention groups (p < 0.05).Conclusion: Phosgene inhalation activates Notch signaling pathway, while MSC intervention inhibits this signaling pathway. Thus, inhibition of NSP may be implicated in the protective effect of MSC therapy against phosgene-induced lung injury.Keywords: Phosgene, Lung injury, Notch signalling pathway, Mesenchymal stem cells

The effect of NF-κB on NLRP3 of lung tissue in rats with acute lung injury induced by phosgene

Objective To observe the effect of signal transduction pathway of nuclear factor-kappa B (NF-κB) on Nod-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome and pyroptosis in rats with acute lung injury induced (ALI) by phosgene. Methods The rats were randomly(random number) divided into 3 groups: air exposure control group, phosgene exposure group and PDTC group with phosgene exposure after 100 mg/kg pyrrolidine dithiocarbamate (PDTC) administration. The specimens of serum, bronchoalveolar lavage fluid (BALF) and lung tissue were collected 6 h after exposure. Morphological changes were observed by HE staining. The expression of NLRP3 in the lung of three groups was detected by immunohistochemistry. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the expressions of NF-κB p65,NLRP3, ASC and caspase-1 mRNA in the lung tissue. NF-κB p65, NLRP3, ASC and caspase-1 protein levels in the lung tissue were quantified by Western blot. The concentrations of IL-1β, IL-18 and IL-33 in the serum and BALF were measured by enzyme-linked immunosorbent assay (ELISA). Pyroptosis was observed by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay (TUNEL). Results The model of phosgene-induced ALI was successfully established in rats. Morphological changes with inflammatory cell infiltration were observed in the lung tissues of phosgene group, in which NLRP3 positive cells also could be observed by immunohistochemical staining. The mRNA expressions and protein levels of NF-κB p65, NLRP3 and caspase-1 in lung tissues were significantly increased (P<0.05) in phosgene group, compared with air control group. The mRNA expressions and protein levels of NF-κB p65, NLRP3 and caspase-1 in lung tissues were significantly decreased (P<0.05) in PDTC group, compared with phosgene group. The IL-1β, IL-18 and IL-33 protein levels in serum and BALF were significantly increased (P<0.05) in phosgene group, compared with air control group. The IL-1β, IL-18 and IL-33 protein levels in serum and BALF were significantly decreased (P<0.05) in PDTC group, compared with phosgene group. TUNEL results showed that pyroptosis in the lung tissue obviously increased in phosgene group, while decreased in PDTC group. Conclusions NLRP3 inflammasome and lung cell pyroptosis were induced through NF-κB signal transduction pathway in rats with acute lung injury caused by phosgene inhalation. Blockade of NF-κB can alleviate acute lung injury by down-regulating the expression of NLRP3 inflammasome to inhibit pyroptosis. Key words: Nuclear factor-kappa B (NF-κB); Phosgene; acute lung injury; Pyrin domain-containing 3 (NLRP3) innammasome; Inhalation; pyroptosis; Inflammation; Pyrrolidinedithiocarbamic acid (PDTC)

Assessment of N-acetylcysteine as a therapy for phosgene-induced acute lung injury

The toxic industrial chemical (TIC1) phosgene remains an important chemical intermediate in many industrial processes. Inhalation of phosgene can cause an acute lung injury (ALI) which, in severe cases may result in death. There are currently no effective pharmacological therapies or evidence-based treatment guidelines for managing exposed individuals.N-acetylcysteine (NAC) is a commercially available drug licensed in the UK and elsewhere for the treatment of paracetamol (acetaminophen) overdose. It has a number of mechanisms of action which may provide therapeutic benefit for the treatment of phosgene-induced ALI. It has previously been shown to provide therapeutic efficacy against the lung damaging effects of sulfur mustard vapour exposure, when given by the inhaled route, in the pig (Jugg et al., 2013).Our research objective was to determine whether inhaled NAC might also be therapeutic for other chemicals, in this case, phosgene. This study has demonstrated that multiple nebulised doses, administered from 30 min after exposure of terminally anaesthetised pigs to phosgene, is not an effective therapy when administered at the times and doses employed in this study. There remains no pharmacological treatment for phosgene-induced lung injury.

Evaluation of an in vitro screening model to assess phosgene inhalation injury

Therapeutic development against exposure to toxic gases is hindered by the lack of appropriate models to evaluate candidate compounds prior to animal efficacy studies. In this study, an in vitro, air-liquid interface exposure model has been tested to examine its potential application for screening treatments for phosgene (carbonyl chloride)-induced pulmonary injury. Epithelial cultures on Transwell® inserts, combined with a Vitrocell® exposure apparatus, provided a physiologically relevant exposure environment. Differentiated human bronchial epithelial (16HBE) cultures were exposed for 8 min to phosgene ranging from 0 to 64 ppm and assessed for changes in transepithelial electrical resistance (TEER, epithelial barrier integrity), cellular viability (XTT) and post-exposure (PE) cellular metabolic energy status. Exposure to phosgene concentrations ≥8 ppm caused dose-dependent and significant decreases in TEER and XTT which did not recover within 24-h PE. In addition, at 64 ppm the rate of oxidative glutamine metabolism was significantly inhibited at 6 and 24 h after exposure. Glycolytic activities (glucose utilization and lactate production) were also inhibited, but to a lesser extent. Decreased glycolytic function can translate to insufficient energy sources to counteract barrier function failure. Consistent and sensitive markers of phosgene exposure were TEER, cell viability and decreased metabolism. As such, we have assessed an appropriate in vitro model of phosgene inhalation that produced quantifiable alterations in markers of lung cell metabolism and injury in human airway epithelial cells. Data indicate the suitability of this model for testing classes of anti-edemagenic compounds such as corticosteroids or phosphodiesterase inhibitors for evaluating phosgene therapeutics.

Detecting critical state before phase transition of complex biological systems by hidden Markov model.

Identifying the critical state or pre-transition state just before the occurrence of a phase transition is a challenging task, because the state of the system may show little apparent change before this critical transition during the gradual parameter variations. Such dynamics of phase transition is generally composed of three stages, i.e. before-transition state, pre-transition state and after-transition state, which can be considered as three different Markov processes. By exploring the rich dynamical information provided by high-throughput data, we present a novel computational method, i.e. hidden Markov model (HMM) based approach, to detect the switching point of the two Markov processes from the before-transition state (a stationary Markov process) to the pre-transition state (a time-varying Markov process), thereby identifying the pre-transition state or early-warning signals of the phase transition. To validate the effectiveness, we apply this method to detect the signals of the imminent phase transitions of complex systems based on the simulated datasets, and further identify the pre-transition states as well as their critical modules for three real datasets, i.e. the acute lung injury triggered by phosgene inhalation, MCF-7 human breast cancer caused by heregulin and HCV-induced dysplasia and hepatocellular carcinoma. Both functional and pathway enrichment analyses validate the computational results. The source code and some supporting files are available at https://github.com/rabbitpei/HMM_based-method lnchen@sibs.ac.cn or liyj@scut.edu.cn Supplementary data are available at Bioinformatics online.

Conceptual approaches for treatment of phosgene inhalation-induced lung injury

Toxic industrial chemicals are used throughout the world to produce everyday products such as household and commercial cleaners, disinfectants, pesticides, pharmaceuticals, plastics, paper, and fertilizers. These chemicals are produced, stored, and transported in large quantities, which poses a threat to the local civilian population in cases of accidental or intentional release. Several of these chemicals have no known medical countermeasures for their toxic effects. Phosgene is a highly toxic industrial chemical which was used as a chemical warfare agent in WWI. Exposure to phosgene causes latent, non-cardiogenic pulmonary edema which can result in respiratory failure and death. The mechanisms of phosgene-induced pulmonary injury are not fully identified, and currently there is no efficacious countermeasure. Here, we provide a proposed mechanism of phosgene-induced lung injury based on the literature and from studies conducted in our lab, as well as provide results from studies designed to evaluate survival efficacy of potential therapies following whole-body phosgene exposure in mice. Several therapies were able to significantly increase 24h survival following an LCt50-70 exposure to phosgene; however, no treatment was able to fully protect against phosgene-induced mortality. These studies provide evidence that mortality following phosgene toxicity can be mitigated by neuro- and calcium-regulators, antioxidants, phosphodiesterase and endothelin receptor antagonists, angiotensin converting enzymes, and transient receptor potential cation channel inhibitors. However, because the mechanism of phosgene toxicity is multifaceted, we conclude that a single therapeutic is unlikely to be sufficient to ameliorate the multitude of direct and secondary toxic effects caused by phosgene inhalation.

Effect of melatonin on p38MAPKsignaling pathway in rats with phosgene-induced lung injury

To investigate the effect of melatonin (MT) on p38 mitogen-activated protein kinase (MAPK) signaling pathway in rats with phosgene-induced lung injury. Fifty specific pathogen-free male Sprague-Dawley rats were randomly divided into phosgene inhalation group, air control group, saline control group, MT treatment group, and SB203580 (specific inhibitor of p38 MAPK) group, with 10 mice in each group. All groups except the air control group were exposed to phosgene, and the animals were sacrificed 6 h later. Lung wet/dry weight (W/D) ratio and the content of malondialdehyde (MDA) and nitric oxide (NO) and activity of myeloperoxidase (MPO) in bronchoalveolar lavage fluid (BALF) were measured. The qualitative and quantitative expression of p38 MAPK and phospho-p38 MAPK (p-p38) was measured by immunohistochemistry (IHC) and Western blot, respectively. Inducible nitric oxide synthase (iNOS) level in lung tissue was determined by Western blot. Compared with the air control group, the phosgene inhalation group had significantly increased lung W/D ratio and neutrophil count in BALF (P < 0.01); the MT treatment group had significantly lower neutrophil count and lung W/D ratio than the phosgene inhalation group (P < 0.05). IHC demonstrated that the air control group had relatively weak expression of p-p38 in lung tissue; the expression of p-p38 was significantly up-regulated after phosgene inhalation, and it was mainly distributed in infiltrating inflammatory cells and vascular endothelial cells, positive in the cytoplasm and nucleus of many cells. The distribution of p-p38-positive cells in the MT treatment and SB203580 groups was similar to that in the phosgene inhalation group, but the MT treatment and SB203580 groups had a significantly reduced number of cells with p-p38-positive nuclei and a significantly reduced intensity of p-p38 expression signals. The phosgene inhalation group had significantly increased content of MDA and NO and activity of MPO compared with the air control group (P < 0.01); the MT treatment and SB203580 groups had significantly reduced content of MDA and NO and activity of MPO compared with the phosgene inhalation group (P < 0.05), but had higher content of MDA and NO and activity of MPO than the air control group. The Western blot showed that the phosgene inhalation group had significantly increased expression of iNOS and p-p38 compared with the air control group (P < 0.01); the MT treatment and SB203580 groups had lower expression of iNOS and p-p38 than the phosgene inhalation group (P < 0.05). MT and SB203580 have a significant protective effect in rats with phosgene-induced lung injury, and the mechanism may be associated with scavenging free radicals and inhibiting activation of p38 MAPK and expression of iNOS.

Accidental phosgene gas exposure: A review with background study of 10 cases

Here, authors present a review on clinical presentation and management of exposure of phosgene gas after reviewing the literature by searching with keywords phosgene exposure on Google, Cochrane, Embase and PubMed with a background of experience gained from 10 patients who were admitted to our institute after an accidental phosgene exposure in February 2011 nearby a city in India. Phosgene is a highly toxic gas, occupational workers may have accidental exposure. The gas can also be generated inadvertently during fire involving plastics and other chemicals and solvents containing chlorine, which is of concern to emergency responders. Phosgene inhalation may cause initially symptoms of respiratory tract irritation, patients feel fine thereafter, and then die of choking a day later because of build up of fluid in the lungs (delayed onset non-cardiogenic pulmonary edema). Phosgene exposure is associated with significant morbidity and mortality. Patients with a history of exposure should be admitted to the hospital for a minimum of 24 h for observation because of the potential for delayed onset respiratory failure and acute respiratory distress syndrome.

Accidental inhalation injury of phosgene gas leading to acute respiratory distress syndrome

Irritant gas exposure may lead to significant respiratory distress as is seen in the present case of 25 year old male worker who suffered accidental phosgene inhalation. He remained asymptomatic for six hours but later landed up in Acute Respiratory Distress Syndrome in the hospital and required ventilatory support. No investigative feature is diagnostic of the nature of irritant gas. Similarly there is no antidote available to the phosgene. Only timely administered supportive management may lead to successful outcome.

Respiratory Tract Fluid and Inhalation of Phosgene

Abstract Increase in the permeability of the respiratory membrane of rabbits after exposure to phosgene was followed by measuring the output and composition of respiratory tract fluid. During the latent period, levels of sodium and chloride in respiratory tract fluid were elevated but volume was normal. During the early symptomatic period, the levels of sodium and chloride were definitely elevated but volume was still normal. Just before death in the late symptomatic period, respiratory tract fluid poured out of the lungs at a rate which averaged 60 times the normal and its sodium, chloride, and lipid levels were identical to those of blood plasma. Rabbits in the last group had an intense pulmonary oedema, haemoconcentration, and little or no resistance to the lethal effect of urethane.

Pentoxifylline inhibits intercellular adhesion molecule-1 (ICAM-1) and lung injury in experimental phosgene-exposure rats

Phosgene inhalation results in acute lung injury (ALI) mostly, pulmonary edema and even acute respiratory distress syndrome, but there is no specific antidote. Inflammatory cells play an important role in the ALI caused by phosgene. Intercellular adhesion molecule-1 (ICAM-1) is a critical factor for inflammatory organ injury. We hypothesized that pentoxifylline (PTX), an inhibitor of leukocyte activation, would have a protective effect on experimental phosgene-induced lung injury rats by inhibiting ICAM-1. To prove this hypothesis, we used rat models of phosgene (400 ppm × 1 min)-induced injury to investigate: (1) the time course of lung injury (control 1, 3, 6, 12, 24, and 48 h group), including pathological changes in hematoxylin and eosin staining and transmission electron microscope, myeloperoxidase (MPO) activity by colorimetric method and ICAM-1 protein level detected by western blot, (2) At 3 h after phosgene exposure, protective effects of different dosages of PTX (50 mg/kg and 100 mg/kg) administration were evaluated by MPO activity, ICAM-1 differential expression and WBC count in bronchoalveolar lavage fluid. The results showed that inflammatory cells emerged out of lung blood vessels at 3 h after phosgene exposure. The MPO activity of lung tissue increased significantly from 3 to 48 h after phosgene exposure (P < 0.05) and ICAM-1 expression presented a similar change, especially at 3 h and 24 h (P < 0.05). After pretreatment and treatment with PTX (100 mg/kg), significant protective effects were shown (P < 0.05). These data supported our hypothesis that PTX reduced phosgene-induced lung injury, possibly by inhibiting ICAM-1 differential expression.

Intravenous Administration of Hyperoxygenated Solution Attenuates Pulmonary Edema Formation in Phosgene-Induced Acute Lung Injury in Rabbits

The aim of this study was to investigate the post-treatment effect of intravenous hyperoxygenated solution (HOS) on pulmonary parameters in rabbits whole-body-exposed to the toxic gas phosgene. Twenty-four New Zealand rabbits were divided into four groups randomly: rabbits were exposed whole-body to either filtered room air or 539 ppm phosgene for 5 minutes followed by room air washout for 5 minutes. Phosgene-exposed group (exposed to phosgene without treatment, PH group); Control group (exposed to air, Control group); Lactate Ringer's solution (LRS)-treated group (intravenous infusion of LRS by 30 ml·kg-1 after phosgene exposure, LRS group); Hyperoxygenated solution (HOS)-treated group (intravenous infusion of HOS after phosgene exposure by 30 mL·kg-1, HOS group). Arterial blood was collected for blood gas analysis at 1, 3, 8, and 12 hours after phosgene or air exposure. Rabbits were put to death 12 hours after exposure. Lung edema was assessed gravimetrically by measuring tissue wet/dry weight ratio (W/D) and lung coefficient (LC). Bronchoalveolar lavage (BAL) was performed and fluid was analyzed for total maloaldehyde (MDA), glutathione peroxidase (GSH-Px), and protein concentration. Lungs were perfused with saline to remove blood, snap-frozen in liquid nitrogen (N2), analyzed for tissue reduced glutathione (GSH) and oxidized glutathione (GSSG). Parts of lung tissues were reserved for histopathology examination. In the PH, LRS, and HOS groups, phosgene inhalation caused serious lung edema, W/D and LC, lung tissue GSSG, BALF MDA, and protein content increased significantly. Meanwhile, PaO2, lung tissue GSH, and BALF GSH-Px decreased markedly. However, after HOS treatment in the HOS group, PaO2 was clearly higher than that in the PH group and LRS group at 3, 8, 12 hours (P < 0.01). W/D and LC, lung tissue GSSG, BALF MDA, and protein content in the HOS group were apparently lower than that in the PH group and LRS group (P < 0.01). In the HOS group, lung tissue GSH and BALF GSH-Px increased compared with both PH and LRS group, respectively. There was no difference on lung tissue GSH among the PH, LRS, and HOS groups (P > 0.05). Intravenous HOS infusion after phosgene exposure can clearly lessen phosgene-induced lung edema formation, lipid peroxidatic reaction, and ameliorate hypoxemia associated with phosgenismus; it is a safe, simple, and effective measure to protect animals from phosgene-induced lung injury.

Health assessment of phosgene: Approaches for derivation of reference concentration

This paper describes the derivation of the chronic reference concentration (RfC) for human inhalation of phosgene that was recently added to the Environmental Protection Agency’s (EPA) Integrated Risk Information System (IRIS) data base (U.S. EPA, 2005. Toxicological Review of Phosgene: In Support of Summary Information on the Integrated Risk Information System (IRIS). Available online at: < http://www.epa.gov/IRIS>). The RfC is an estimate of daily phosgene exposure to the human population that is likely to be without appreciable risk of deleterious effects during a lifetime. [For this and other definitions relevant to EPA risk assessments refer to the glossary of terms in the US EPA IRIS website ( http://www.epa.gov/IRIS).] Phosgene is a potential environmental pollutant that is primarily used as a catalyst in the polyurethane industry. It is a gas at room temperature, and in aqueous solution it rapidly hydrolyzes to CO 2 and HCl. In the absence of chronic human health effects information and lifetime animal cancer bioassays, the RfC is based on two 12-week inhalation studies in F344 rats which measured immune response and pulmonary effects, respectively. The immune response study showed impaired clearance of bacteria that was administered into the lungs of rats immediately after exposure to phosgene at concentrations of 0.1, 0.2 and 0.5 ppm. It also showed that the immune response in uninfected rats was stimulated by phosgene exposure at all concentrations. The pulmonary effects study showed a progressive concentration-related thickening and inflammation in the bronchiolar regions of the lung that was mild at 0.1 ppm and severe at 1.0 ppm. An increase in collagen content, as observed with histological collagen stains, was observed at 0.2 ppm and above. Though there is considerable uncertainty associated with the species and exposure duration employed, this endpoint is considered an indication of chronic lung injury of potential relevance to humans. Three different approaches for RfC derivation were taken in analyzing these studies: (1) the traditional NOAEL/LOAEL method; (2) the benchmark dose (BMD); and (3) the categorical regression for the analysis of severity-graded pulmonary damage data using the recently revised USEPA CatReg software. The BMD approach was selected as the method of choice to determine the RfC for phosgene because it has several advantages compared to the NOAEL/LOAEL: (1) it is not restricted to the set of doses used in the experiments; (2) the result is not dependent on sample size; (3) it incorporates information on statistical uncertainty. The CatReg approach allowed the incorporation of data on the severity of the pathological lesions, and therefore it complemented the other approaches. The BMD approach could not be applied to the immune response data because it was not possible to define an adverse effect level for bacterial resistance. However, NOAEL/LOAEL values for immune responses were consistent with benchmark dose levels derived from lung pathology data and used in the derivation of the RfC. The preferred RfC method and derivation involved dividing the benchmark dose from the collagen staining data (0.03 mg/m 3) by a composite uncertainty factor of 100: RfC = 0.03/100 = 3E − 4 mg/m 3.

Apoptosis of ATII Cells in Mice Induced by Phosgene

Phosgene inhalation can induced pulmonary edema formation. The purpose of this study was to investigate cell of apoptosis in pulmonary edema mice induced by phosgene. Fifty-two BALB/c mice were random divided into a negative group and a positive group with 26 mice in each. Mice were exposed for 5 min to air and phosgene in the negative group and in the positive one, respectively. The dose of phosgene was 539 ppm. After 4 h of exposure, all mice were anesthetized. Lungs were analyzed for lung wet/dry weight ratio and pathological alternation. The method of isolation and culture of alveolar type II cells (ATII cells) was established to observe their apoptosis by electron microscope and flow cytometry. Apoptosis of lung cells was observed by DNA gel electrophoresis and TUNEL. The lung wet/dry weight ratio was significantly higher in the positive group (6.42 ± 1.00) than in the negative group (4.25 ± 0.47, p < 0.05). A large amount of fluid effusion was observed in the alveolus of mice induced by phosgene. Alveolar type II cells were identified by tannic acid stainning and electron microscope. The apoptotic signs in alveolar type II cells, alveolar type I cells, eosinophils, macrophages, symphocytes, and ciliated cells were viewed under electron microscope in positive group. The ratio of apoptosis cells (40.26 ± 7.74) in positive was higher than that (1.58 ± 1.01, p < 0.001) in the negative group by flow cytometry. DNA ladder alternation was seen through DNA gel electrophoresis. Apoptosis of epithelia and vascular endothelia in lung were found by TUNEL. These results indicate that there is success in establishing a model of pulmonary edema and method of isolation and culture of AT II cells in BALB/c mice. Phosgene can induce apoptosis of cells in the lungs of BALB/c mice, and this indicates that pulmonary edema is related to apoptosis of lung cells in mice, induced by phosgene.