Phosgene-Induced acute lung injury: Approaches for mechanism-based treatment strategies

Identification of shared important genes associated with ferroptosis across different etiologies of acute lung injury

Acute lung injury (ALI) of different etiologies has shared pathophysiologic process, from which we speculated that ALI of different etiologies may share common molecular features. While the shared genetic characteristics of ALI remain unclear. In this paper, we aimed to identify shared ferroptosis-associated and bottleneck genes from acute lung injury of different etiologies. Firstly, we extracted five groups of gene sets related to three distinct models of ALI from the Gene Expression Omnibus (GEO) database. Then, through the utilization of weighted gene co-expression network analysis (WGCNA), we identified 3 significant gene modules and ascertained 7 shared co-expressed genes affected by these models. Subsequently, through the utilization of differential gene expression analysis and protein-protein interaction network analysis for the 3 gene modules, the shared bottleneck gene Slc7a11 was identified. Moreover, the 7 shared co-expressed genes subjected to these three ALI models were used to identify shared ferroptosis-associated genes via the FerrDb database. Finally, the key gene Slc7a11 was confirmed and validated. In addition, we observed that Slc7a11 is both a driver and a suppressor gene in the FerrDb database. Interestingly, we found the expression level of Slc7a11 was significantly upregulated in the three ALI models. Experimentally, we confirmed the expression of Slc7a11 in rat ALI tissues by using immunofluorescence staining and real-time polymerase chain reaction (qRT-PCR) assays. Collectively, our findings complement the exploration of the shared pathogenesis of ALI. There are genetic features shared by ALI of different etiology and the increased expression of Slc7a11 was identified in the three different etiologies of ALI, which can improve our understanding of the shared molecular mechanisms underlying ALI.

N-Acetylcysteine in the Treatment of Acute Lung Injury: Perspectives and Limitations

N-acetylcysteine (NAC) can take part in the treatment of chronic respiratory diseases because of the potent mucolytic, antioxidant, and anti-inflammatory effects of NAC. However, less is known about its use in the treatment of acute lung injury. Nowadays, an increasing number of studies indicates that early administration of NAC may reduce markers of oxidative stress and alleviate inflammation in animal models of acute lung injury (ALI) and in patients suffering from distinct forms of acute respiratory distress syndrome (ARDS) or pulmonary infections including community-acquired pneumonia or Coronavirus Disease (COVID)-19. Besides low costs, easy accessibility, low toxicity, and rare side effects, NAC can also be combined with other drugs. This article provides a review of knowledge on the mechanisms of inflammation and oxidative stress in various forms of ALI/ARDS and critically discusses experience with the use of NAC in these disorders. For preparing the review, articles published in the English language from the PubMed database were used.

Imino and Benzimidazolinyl Functionalized pyrano[2,3-b] Quinoline as a Dual-Responsive Probe for Detection of Mercury ion and Phosgene

A dual-responsive probe 8-N, N-diethylamino-3-(1H-benzoimidazol-2-yl)-2H-pyrano[2,3-b]quinoline-2-imino (PQI), pyrano[2,3-b]quinoline as fluorophore, two nitrogen atoms as receptor sites, was developed for the colorimetric and fluorescence detection of Hg2+ and COCl2 in different solvents. PQI showed good recognition ability for Hg2+ via the absorbance decrease, fluorescence quenching by the formation of PQI-Hg2+ complex in MeOH/H2O (4/1, V/V). In addition, PQI could specifically react with COCl2 via intramolecular cyclization to form a cyclic urea product, which exhibited absorption and fluorescence emission changes, and then realized the detection of COCl2. Moreover, the optical responses of PQI to Hg2+ and COCl2 featured high selectivity, fast response (within 30 s), and low detection limit (73 nM for Hg2+ and 25 nM for COCl2, respectively). Furthermore, PQI could detect Hg2+ in real water samples with good recoveries and small relative standard deviations, and could be prepared as a PQI-loaded test strip to monitor gaseous COCl2 in an in-site, real-time, highly sensitive manner, demonstrating the practicability of PQI in Hg2+ and gaseous COCl2 detection.

Promoting epithelial regeneration in chemically induced acute lung injury through Sox9-positive alveolar type 2 epithelial cells

BACKGROUND

Chemical-induced acute lung injury is characterized by impaired epithelial regenerative capacity, leading to acute pulmonary edema. Numerous studies have investigated the therapeutic potential of endogenous stem cells with particular emphasis on alveolar type 2 epithelial (AEC2) cells owing to their involvement in lung cell renewal. Sox9, a transcription factor known for its role in maintaining stem cell properties and guiding cell differentiation, marks a subset of AEC2 cells believed to contribute to epithelial repair. However, the role of Sox9+AEC2 cells in the distal lung alveolar cells and the potential roles in chemically induced acute lung injury have never been explored.

METHODS

In this study, we generated Sox9flox/flox;SftpcCre-ERT2 mice and examined the effects of Sox9+AEC2 cells on the pathophysiology of epithelial damage during chemical-induced acute lung injury. Subsequently, Sox9-CreERT2 Ai9 mice were used for lineage tracing to elucidate the repair mechanisms.

RESULTS

Our findings revealed that Sox9+AEC2 cells endowed with stem cell properties induced cell proliferation during lung injury, predominantly in the damaged alveolar region. This process is accompanied by the regulation of inflammatory responses and orderly differentiation, thereby promoting epithelial regeneration.

CONCLUSION

These results provide compelling in vivo genetic evidence supporting the characterization of Sox9+AEC2 cells as bona fide lung epithelial stem cells, demonstrating their multipotency and self-renewal capabilities during lung repair and regeneration. The identification of Sox9+AEC2 cells as crucial contributors to the promotion of epithelial repair underscores their potential as therapeutic targets in chemical-induced acute lung injury.

Ru(III)-PhI(OAc)2─A Combination for Generation of Isocyanate Intermediate from Benzimidate through a Rearrangement: Synthesis of Unsymmetrical Urea, Carbamate, and Chiral Analogues

Ru(III)-PhI(OAc)2, an unprecedented combination, is a highly efficient reagent system for the in situ generation of a valuable isocyanate intermediate from benzimidate synthons through a rearrangement. It unlocks a powerful platform for forming diverse C-N bonds, enabling the one-pot synthesis of an expansive array of valuable unsymmetrical ureas, carbamates, and their chiral analogues toward complex molecular structures with high selectivity and excellent yields. This new strategy not only exemplifies efficiency but also serves as a versatile tool for the construction of valuable molecular architectures, enhancing the scope and impact of modern synthetic chemistry.

Sulforaphane attenuates phosgene-induced acute lung injury via the Nrf2-HO-1/NQO1 pathway

Background

Sulforaphane (SFN) has been demonstrated to exert a protective role in various diseases. However, the role of SFN in phosgene-induced acute lung injury (P-ALI) remains unclear. This study aimed to explore the role and mechanism of SFN in P-ALI and provide a theoretical basis for the clinical prevention and treatment of P-ALI.

Methods

A mouse model of P-ALI was established followed by phosgene gas inhalation at a dose of 4.17 g/m3 for 5 min. The survival rate, lung coefficient and hematoxylin and eosin (H&E) staining, lung pathology scoring, and bronchoalveolar lavage fluid (BALF) analysis were performed to evaluate lung tissue damage. The real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting analysis were utilized to evaluate the relative expression levels of inflammation factors and protein expression.

Results

Compared with the control group, destruction of alveolar structure, pulmonary edema, lung tissue inflammation and oxidative stress occurred after phosgene exposure. After the administration of SFN, the massive exudation of red blood cells and significant thickening of alveolar interstitium were ameliorated, the lung tissue inflammation was improved, and oxidative stress level was reduced. Mechanically, SFN could increase the expression of nuclear factor erythroid 2 (NFE2)-related factor 2 (Nrf2) protein and the downstream heme oxgenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase 1 (NQO1), thereby improving P-ALI. And the Nrf2 inhibitor ML385 attenuated the lung protective effect of SFN.

Conclusions

Phosgene inhalation led to edema, inflammation, and oxidative stress of lung tissue in mice. SFN might ameliorate phosgene-induced lung injury through Nrf2-HO-1/NQO1 signaling pathway.

Acute Lung Injury and the NLRP3 Inflammasome

Acute lung injury (ALI) manifests through harm to the capillary endothelium and alveolar epithelial cells, arising from a multitude of factors, leading to scattered interstitial alterations, pulmonary edema, and subsequent acute hypoxic respiratory insufficiency. Acute lung injury (ALI), along with its more serious counterpart, acute respiratory distress syndrome (ARDS), carry a fatality rate that hovers around 30-40%. Its principal pathological characteristic lies in the unchecked inflammatory reaction. Currently, the main strategies for treating ALI are alleviation of inflammation and prevention of respiratory failure. Concerning the etiology of ALI, NLRP3 Inflammasome is essential to the body's innate immune response. The composition of this inflammasome complex includes NLRP3, the pyroptosis mediator ASC, and pro-caspase-1. Recent research has reported that the inflammatory response centered on NLRP3 inflammasomes plays a key part in inflammation in ALI, and may hence be a prospective candidate for therapeutic intervention. In the review, we present an overview of the ailment characteristics of acute lung injury along with the constitution and operation of the NLRP3 inflammasome within this framework. We also explore therapeutic strategies targeting the NLRP3 inflammasome to combat acute lung injury.

Physiologically based pharmacokinetic model for predicting the biodistribution of albumin nanoparticles after induction and recovery from acute lung injury

The application of nanomedicine in the treatment of acute lung injury (ALI) has great potential for the development of new therapeutic strategies. To gain insight into the kinetics of nanocarrier distribution upon time-dependent changes in tissue permeability after ALI induction in mice, we developed a physiologically based pharmacokinetic model for albumin nanoparticles (ANP). The model was calibrated using data from mice treated with intraperitoneal LPS (6 mg/kg), followed by intravenous ANP (0.5 mg/mouse or about 20.8 mg/kg) at 0.5, 6, and 24 h. The simulation results reproduced the experimental observations and indicated that the accumulation of ANP in the lungs increased, reaching a peak 6 h after LPS injury, whereas it decreased in the liver, kidney, and spleen. The model predicted that LPS caused an immediate (within the first 30 min) dramatic increase in lung and kidney tissue permeability, whereas splenic tissue permeability gradually increased over 24 h after LPS injection. This information can be used to design new therapies targeting specific organs affected by bacterial infections and potentially by other inflammatory insults.

Characteristics of phosgene aspiration lung injury analyzed based on transcriptomics and proteomics

Background

Phosgene is a chemical material widely used worldwide. No effective method has been developed to reverse its pathological injuries. Some studies have shown that neuronal inflammation in lung tissue is involved, but the specific mechanism has not been reported.

Objective

To analyze the expression alterations of whole transcriptome gene sequencing bioinformatics and protein expression profile in lung tissue after phosgene aspiration lung injury (P-ALI) and find the main factors and pathways affecting the prognosis of P-ALI.

Methods

Rat models of P-ALI were made by phosgene. Rats were divided into a P-ALI group and a blank group. Hematoxylin-eosin (HE) staining and lung wet/dry ratio measurement were used to evaluate the lung injury. The levels of inflammatory factors were measured by ELISA. High-throughput sequencing was used to measure the expression profile of each gene. Protein expression profiles were determined by label-free relative quantification of the differential proteome.

Results

Lung injury such as the disordered structure of alveolar wall and inflammatory factors (IL-1β, IL-18, and IL-33) were significantly increased in the P-ALI group (p < 0.05). There were 225 differentially expressed lncRNAs, including 85 upregulated and 140 downregulated genes. They were also the genomes with the most significant changes in transcriptome gene expression, mainly constituting cytoplasmic, synaptic structures and transporters, and involved in amino acid and carbon metabolism. There were 42 differentially expressed circRNAs, including 25 upregulated genes and 17 downregulated genes, mainly involved in cell composition, growth, differentiation, and division. There were only 10 differentially expressed miRNAs genes, all upregulated and mainly involved in the inflammatory response pathway. Proteome identification showed 79 differentially expressed proteins. KEGG enrichment analysis showed that it was mainly involved in the N-glycan biosynthesis pathway.

Conclusion

We discovered that differentially regulated genes (lncRNAs, circRNAs, and miRNAs) were primarily associated with neuronal reflexes and synaptic signaling, including neurotransmitter transmission, ion signaling pathway conduction, neuronal projection, and synaptic vesicle circulation. They affected inflammatory factors and other metabolic pathways. This finding could be explored in future studies.

How To Get Isocyanate?

Isocyanate, a pivotal chemical intermediate to synthesize polyurethane with widespread applications in household appliances, automobiles, and construction, is predominantly produced via the phosgene process, which currently holds a paramount status in industrial isocyanate production. Nonetheless, concerns arise from the toxicity of phosgene and the corrosiveness of hydrogen chloride, posing safety hazards. The synthesis of isocyanate using nonphosgene methods represents a promising avenue for future development. This article primarily focuses on the nonphosgene approach, which involves the formation of carbamate through the reaction of nitro-amino compounds with carbon monoxide, dimethyl carbonate, and urea, among other reagents, subsequently leading to the thermal decomposition of carbamate to get isocyanate. This paper emphasizes the progress in catalyst development during the carbamate decomposition process. Single-component metal catalysts, particularly zinc, exhibit advantages such as high activity, cost-effectiveness, and compatibility with a wide range of substrates. Composite catalysts enhance isocyanate yield by introducing a second component to adjust the active metal composition. The central research direction aims to optimize catalyst adaptation to reaction conditions, including temperature, pressure, time, and solvent, to achieve high raw material conversion and product yield.

Phosgene Toxicity Clinical Manifestations and Treatment: A Systematic Review

Exposure to phosgene, a colourless poisonous gas, can lead to various health issues including eye irritation, a dry and burning throat, vomiting, coughing, the production of foamy sputum, difficulty in breathing, and chest pain. This systematic review aims to provide a comprehensive overview of the clinical manifestations and treatment of phosgene toxicity by systematically analyzing available literature. The search was carried out on various scientific online databases to include related studies based on inclusion and exclusion criteria with the use of PRISMA guidelines. The quality of the studies was assessed using the Mixed Methods Appraisal Tool (MMAT). Thirteen articles were included in this study after the screening process. Inhalation was found to be the primary health problem of phosgene exposure with respiratory symptoms such as coughing and dyspnea. Chest pain and pulmonary oedema were also observed in some cases. Furthermore, pulmonary crackle was the most common reported physical examination. Beyond respiratory tract health issues, other organs involvements such as cardiac, skin, eye, and renal were also reported in some studies. The symptoms can occur within minutes to hours after exposure, and the severity of symptoms depends on the amount of inhaled phosgene. The findings showed that bronchodilators can alleviate symptoms of bronchoconstriction caused by phosgene. Oxygen therapy is essential for restoring oxygen levels and improving respiratory function in cases of hypoxemia. In severe cases, endotracheal intubation and invasive mechanical ventilation are used for artificial respiration, along with the removal of tracheal secretions and pulmonary oedema fluid through suctioning as crucial components of supportive therapy.

Countermeasures against Pulmonary Threat Agents

Inhaled toxicants are used for diverse purposes, ranging from industrial applications such as agriculture, sanitation, and fumigation to crowd control and chemical warfare, and acute exposure can induce lasting respiratory complications. The intentional release of chemical warfare agents (CWAs) during World War I caused life-long damage for survivors, and CWA use is outlawed by international treaties. However, in the past two decades, chemical warfare use has surged in the Middle East and Eastern Europe, with a shift toward lung toxicants. The potential use of industrial and agricultural chemicals in rogue activities is a major concern as they are often stored and transported near populated areas, where intentional or accidental release can cause severe injuries and fatalities. Despite laws and regulatory agencies that regulate use, storage, transport, emissions, and disposal, inhalational exposures continue to cause lasting lung injury. Industrial irritants (e.g., ammonia) aggravate the upper respiratory tract, causing pneumonitis, bronchoconstriction, and dyspnea. Irritant gases (e.g., acrolein, chloropicrin) affect epithelial barrier integrity and cause tissue damage through reactive intermediates or by direct adduction of cysteine-rich proteins. Symptoms of CWAs (e.g., chlorine gas, phosgene, sulfur mustard) progress from airway obstruction and pulmonary edema to acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), which results in respiratory depression days later. Emergency treatment is limited to supportive care using bronchodilators to control airway constriction and rescue with mechanical ventilation to improve gas exchange. Complications from acute exposure can promote obstructive lung disease and/or pulmonary fibrosis, which require long-term clinical care. SIGNIFICANCE STATEMENT: Inhaled chemical threats are of growing concern in both civilian and military settings, and there is an increased need to reduce acute lung injury and delayed clinical complications from exposures. This minireview highlights our current understanding of acute toxicity and pathophysiology of a select number of chemicals of concern. It discusses potential early-stage therapeutic development as well as challenges in developing countermeasures applicable for administration in mass casualty situations.

Highly sensitive and selective detection of triphosgene with a 2-(2'-hydroxyphenyl)benzimidazole derived fluorescent probe

In this work, a 2-(2'-hydroxyphenyl)benzimidazole derived fluorescent probe, 2-(2'-hydroxy-4'-aminophenyl)benzimidazole (4-AHBI), was synthesized and its fluorescent behavior toward triphosgene were evaluated. The results showed that 4-AHBI exhibited high sensitivity (limit of detection, 0.08 nM) and excellent selectivity for triphosgene over other acyl chlorides including phosgene in CH2Cl2 solution. Moreover, 4-AHBI loaded test strips were prepared for the practical sensing of triphosgene.

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.