Host-pathogen-immune interactions in an air-liquid interface airway model.

BACKGROUND

Air-liquid interface (ALI) cell culture systems have improved the study of host-pathogen interactions in respiratory infections. However, most ALI models lack immune components, limiting their ability to capture epithelial-immune crosstalk. To address this, we developed a dual-cell ALI model incorporating human peripheral blood monocyte-derived macrophages beneath differentiated airway epithelial cells.

METHODOLOGY: Macrophages were seeded on the basolateral side of transwell inserts using fibronectin coating. Model characterization included transepithelial electrical resistance (TEER) to assess epithelial barrier integrity, IL-8 secretion as a marker of epithelial inflammatory signaling, and confocal microscopy to evaluate cellular architecture before and after infection. Mono- and dual-cell cultures were infected with the laboratory strain Pseudomonas aeruginosa PAO1.

RESULTS

Macrophages adhered stably to the basolateral surface without compromising epithelial barrier integrity. Following infection, IL-8 secretion was elevated in epithelial monocultures compared to dual-cell cultures, suggesting early immune modulation in the presence of macrophages. While overall bacterial burden was comparable, confocal imaging revealed clustered bacterial growth in monocultures and a more dispersed spatial distribution in dual-cell cultures.

CONCLUSIONS

This dual-cell ALI model enables investigation of early epithelial-immune interactions, inflammatory modulation, and bacterial colonization dynamics during airway infection. The system provides a versatile and human-relevant platform for studying respiratory host-pathogen interactions.