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Transcriptional profiling of lung macrophages during pulmonary injury induced by nitrogen mustard
L Cody Smith1, Alessandro Venosa2, Andrew J Gow1
1Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, New Jersey.
Abstract:
Nitrogen mustard (NM) and sulfur mustard are cytotoxic alkylating agents that cause severe and progressive damage to the respiratory tract. Evidence indicates that macrophages play a key role in the acute inflammatory phase and the later resolution/profibrotic phase of the pathogenic response. These diverse roles are mediated by inflammatory macrophages broadly classified as M1 proinflammatory and M2 anti-inflammatory that sequentially accumulate in the lung in response to injury. The goal of the present study was to identify signaling mechanisms contributing to macrophage activation in response to mustards. To accomplish this, we used RNA sequencing to analyze the gene expression profiles of lung macrophages isolated 1 and 28 days after intratracheal exposure of rats to NM (0.125 mg/kg) or phosphate-buffered saline control. We identified 641 and 792 differentially expressed genes 1 and 28 days post-NM exposure, respectively. These genes are primarily involved in processes related to cell movement and are regulated by cytokines, including tumor necrosis factor-α, interferon-γ, and interleukin-1β. Some of the most significantly enriched canonical pathways included STAT3 and NF-κB signaling. These cytokines and pathways may represent potential targets for therapeutic intervention to mitigate mustard-induced lung toxicity.
Insights
Nitrogen mustard exposure activates lung macrophages, driving inflammation and fibrosis. RNA sequencing revealed key signaling pathways like STAT3 and NF-κB, offering potential therapeutic targets for mustard lung injury.
Area of Science:
- Toxicology
- Immunology
- Respiratory Medicine
Background:
- Nitrogen mustard (NM) and sulfur mustard are cytotoxic agents causing severe respiratory tract damage.
- Macrophages, specifically M1 (proinflammatory) and M2 (anti-inflammatory) types, are crucial in the lung's response to injury, mediating both acute inflammation and later profibrotic phases.
Purpose of the Study:
- To identify signaling mechanisms involved in macrophage activation following mustard exposure.
- To understand the temporal changes in gene expression in lung macrophages post-NM exposure.
Main Methods:
- Rats were intratracheally exposed to NM (0.125 mg/kg) or a control.
- Lung macrophages were isolated at 1 and 28 days post-exposure.
- RNA sequencing was employed to analyze differential gene expression profiles.
Main Results:
- NM exposure led to significant differential gene expression in lung macrophages at both 1 day (641 genes) and 28 days (792 genes) post-exposure.
- Enriched gene pathways were primarily associated with cell movement and regulated by cytokines like TNF-α, IFN-γ, and IL-1β.
- Key canonical pathways identified include STAT3 and NF-κB signaling.
Conclusions:
- Mustard-induced lung toxicity involves complex macrophage activation pathways.
- STAT3 and NF-κB signaling pathways are significantly altered and may represent therapeutic targets for mitigating NM-induced lung damage.
