Nebulization of Model Hydrogel Nanoparticles to Macrophages at the Air-Liquid Interface

Age-dependent changes in phagocytic activity: in vivo response of mouse pulmonary antigen presenting cells to direct lung delivery of charged PEGDA nanoparticles

BACKGROUND

Current needle-based vaccination for respiratory viruses is ineffective at producing sufficient, long-lasting local immunity in the elderly. Direct pulmonary delivery to the resident local pulmonary immune cells can create long-term mucosal responses. However, criteria for drug vehicle design rules that can overcome age-specific changes in immune cell functions have yet to be established.

RESULTS

Here, in vivo charge-based nanoparticle (NP) uptake was compared in mice of two age groups (2- and 16-months) within the four notable pulmonary antigen presenting cell (APC) populations: alveolar macrophages (AM), interstitial macrophages (IM), CD103+ dendritic cells (DCs), and CD11b+ DCs. Both macrophage populations exhibited preferential uptake of anionic nanoparticles but showed inverse rates of phagocytosis between the AM and IM populations across age. DC populations demonstrated preferential uptake of cationic nanoparticles, which remarkably did not significantly change in the aged group. Further characterization of cell phenotypes post-NP internalization demonstrated unique surface marker expression and activation levels for each APC population, showcasing heightened DC inflammatory response to NP delivery in the aged group.

CONCLUSION

The age of mice demonstrated significant preferences in the charge-based NP uptake in APCs that differed greatly between macrophages and DCs. Carefully balance of the targeting and activation of specific types of pulmonary APCs will be critical to produce efficient, age-based vaccines for the growing elderly population.

On the path to predicting immune responses in the lung: Modeling the pulmonary innate immune system at the air-liquid interface (ALI)

Chronic respiratory diseases and infections are among the largest contributors to death globally, many of which still have no cure, including chronic obstructive pulmonary disorder, idiopathic pulmonary fibrosis, and respiratory syncytial virus among others. Pulmonary therapeutics afford untapped potential for treating lung infection and disease through direct delivery to the site of action. However, the ability to innovate new therapeutic paradigms for respiratory diseases will rely on modeling the human lung microenvironment and including key cellular interactions that drive disease. One key feature of the lung microenvironment is the air-liquid interface (ALI). ALI interface modeling techniques, using cell-culture inserts, organoids, microfluidics, and precision lung slices (PCLS), are rapidly developing; however, one major component of these models is lacking-innate immune cell populations. Macrophages, neutrophils, and dendritic cells, among others, represent key lung cell populations, acting as the first responders during lung infection or injury. Innate immune cells respond to and modulate stromal cells and bridge the gap between the innate and adaptive immune system, controlling the bodies response to foreign pathogens and debris. In this article, we review the current state of ALI culture systems with a focus on innate immune cells and suggest ways to build on current models to add complexity and relevant immune cell populations.