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Updated: Sep 26, 2025
Alveolar Macrophage Phagocytosis and Bacteria Clearance in Mice
Published on: March 2, 2019
Therapeutic stem cell-derived alveolar-like macrophages display bactericidal effects and resolve Pseudomonas
Sheena Bouch1, Michael L Litvack1, Kymberly Litman1,2
1Translational Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada.
Abstract:
Bacterial lung infections lead to greater than 4 million deaths per year with antibiotic treatments driving an increase in antibiotic resistance and a need to establish new therapeutic approaches. Recently, we have generated mouse and rat stem cell-derived alveolar-like macrophages (ALMs), which like primary alveolar macrophages (1'AMs), phagocytose bacteria and promote airway repair. Our aim was to further characterize ALMs and determine their bactericidal capabilities. The characterization of ALMs showed that they share known 1'AM cell surface markers, but unlike 1'AMs are highly proliferative in vitro. ALMs effectively phagocytose and kill laboratory strains of P. aeruginosa (P.A.), E. coli (E.C.) and S. aureus, and clinical strains of P.A. In vivo, ALMs remain viable, adapt additional features of native 1'AMs, but proliferation is reduced. Mouse ALMs phagocytose P.A. and E.C. and rat ALMs phagocytose and kill P.A. within the lung 24 h post-instillation. In a pre-clinical model of P.A.-induced lung injury, rat ALM administration mitigated weight loss and resolved lung injury observed seven days post-instillation. Collectively, ALMs attenuate pulmonary bacterial infections and promote airway repair. ALMs could be utilized as an alternative or adjuvant therapy where current treatments are ineffective against antibiotic-resistant bacteria or to enhance routine antibiotic delivery.
Insights
Stem cell-derived alveolar-like macrophages (ALMs) effectively combat bacterial lung infections and promote airway repair. These engineered cells offer a promising alternative to antibiotics, especially against resistant strains.
Area of Science:
- Cell Biology
- Immunology
- Regenerative Medicine
Background:
- Bacterial lung infections cause millions of deaths annually.
- Antibiotic resistance necessitates novel therapeutic strategies.
- Primary alveolar macrophages (1'AMs) are crucial for lung immunity and repair.
Purpose of the Study:
- To characterize stem cell-derived alveolar-like macrophages (ALMs).
- To evaluate the bactericidal capabilities of ALMs against key lung pathogens.
- To assess ALM efficacy in a preclinical model of bacterial lung injury.
Main Methods:
- Generation and in vitro characterization of mouse and rat ALMs.
- Assessment of phagocytosis and killing of bacterial strains (P. aeruginosa, E. coli, S. aureus) by ALMs.
- In vivo studies evaluating ALM viability, adaptation, and function in the lung.
- Preclinical testing of rat ALMs in a Pseudomonas aeruginosa-induced lung injury model.
Main Results:
- ALMs share cell surface markers with 1'AMs but exhibit enhanced in vitro proliferation.
- ALMs effectively phagocytose and kill both laboratory and clinical bacterial strains.
- In vivo, ALMs are viable, adapt to the lung environment, and exhibit bactericidal activity.
- Rat ALM administration in vivo mitigated weight loss and resolved lung injury.
Conclusions:
- ALMs demonstrate significant potential in attenuating pulmonary bacterial infections.
- ALMs promote airway repair, offering a dual therapeutic benefit.
- ALMs represent a viable alternative or adjuvant therapy for antibiotic-resistant bacterial infections.
