SARS-CoV-2 N protein induces alveolar epithelial apoptosis via NLRP3 pathway in ARDS

• Published in: International immunopharmacology 2025-01, Vol.144, p.113503, Article 113503
• Main Authors: Huang, Xiaopei, Zhu, Wenliang, Zhang, Huifeng, Qiu, Shi, Shao, Huanzhang
• Format: Article
• Language: English
• Subjects: Acute Respiratory Distress Syndrome (ARDS); Alveolar Epithelial Cells - metabolism; Alveolar macrophages; Animals; Apoptosis; Cell Line; Coronavirus Nucleocapsid Proteins - metabolism; COVID-19 - immunology; Disease Models, Animal; Epithelial cell apoptosis; Humans; Inflammatory response; Macrophages, Alveolar - immunology; Macrophages, Alveolar - metabolism; Male; Mice; Mice, Inbred C57BL; NLR Family, Pyrin Domain-Containing 3 Protein - genetics; NLR Family, Pyrin Domain-Containing 3 Protein - metabolism; NLRP3 signaling pathway; Phosphoproteins; Respiratory Distress Syndrome - immunology; Respiratory Distress Syndrome - virology; SARS-CoV-2; SARS-CoV-2N protein; Signal Transduction
• ISSN: 1567-5769; 1878-1705; 1878-1705
• DOI: 10.1016/j.intimp.2024.113503

Acute Respiratory Distress Syndrome (ARDS) is a severe inflammatory condition often resulting from sepsis and viral infections, including (Severe Acute Respiratory Syndrome Coronavirus 2) SARS-CoV-2. This study investigates the molecular mechanisms by which the SARS-CoV-2 nucleocapsid (N) protein influences alveolar macrophage activation, leading to alveolar epithelial cell apoptosis and exacerbating ARDS. Single-cell RNA sequencing data from ARDS patients were analyzed to identify cell subpopulations and their interactions, revealing significant macrophage-epithelial cell communication through the (NOD-like receptor family pyrin domain containing 3) NLRP3 pathway. Differential gene expression in SARS-CoV-2-infected macrophages highlighted key genes, with WGCNA pinpointing core modules. In vitro experiments demonstrated that N protein overexpression in MH-S macrophages activates the NLRP3 pathway, promoting M1 macrophage polarization and inducing apoptosis in co-cultured MLE-12 epithelial cells. Immunoprecipitation, pull-down assays, Enzyme-Linked Immunosorbent Assay (ELISA), RT-qPCR, Western blotting, and flow cytometry confirmed these findings. In vivo, ARDS mouse models induced by CLP surgery or N protein administration showed increased M1 macrophage infiltration, heightened inflammatory responses, and significant epithelial cell damage, as evidenced by H&E staining, immunofluorescence, RNA-ISH, and ELISA. These results suggest that the SARS-CoV-2 N protein activates the NLRP3 signaling pathway, driving M1 macrophage polarization and the release of pro-inflammatory factors, thereby inducing alveolar epithelial cell apoptosis and worsening ARDS. Targeting this pathway may provide new therapeutic avenues for treating ARDS associated with SARS-CoV-2.