Macrophage-exacerbated viral lung injury and mechanical overdistension-driven bacterial superinfection replicated in a human lung chip

Patients with severe influenza-induced lung injury exhibit disrupted alveolar barrier and persistent viral load, accompanied by hyperinflammation, immune cell recruitment, and risk of bacterial superinfection. These complications are often exacerbated in patients undergoing mechanical ventilation. Leveraging an immune-competent human lung alveolus-on-a-chip (Lung Chip) lined by human pulmonary alveolar epithelium co-cultured with monocyte-derived macrophages and interfaced with lung microvascular endothelium, we show that monocyte-derived macrophages play a central role in driving key hallmarks of severe influenza, including activated cell death programs. Physiological strain mimicking breathing motions supported alveolar homeostasis, whereas pathological strain analogous to mechanical ventilator-induced lung overdistension promoted secondary Pseudomonas aeruginosa infection. Computational gene network analysis combined with experimental validation identified SIRT1 as a key modulator of inflammation and susceptibility to bacterial superinfection, which can be mitigated using pharmacological SIRT1 activators. Together, these findings underscore the importance of incorporating macrophages into preclinical models of viral lung injury and establish an integrated workflow combining human Organ Chips and computational approaches for gaining insights into biophysical and molecular disease drivers while facilitating the identification of therapeutic targets and candidate countermeasures.