Modulation of Cell Signaling Pathways in Silica Nanoparticle-Saturated Macrophages

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Immunology

Background:

• Macrophages readily uptake systemically delivered nanoparticles, potentially leading to saturation.
• Macrophage saturation by nanoparticles may compromise immune function and signaling pathways.
• Limited understanding exists regarding molecular-level changes in saturated macrophages and their impact on phenotype and immune responses.

Purpose of the Study:

• To investigate the molecular-level changes in macrophages saturated with silica nanoparticles (SNPs).
• To determine how physicochemical properties of SNPs influence macrophage gene expression and immune signaling pathways.
• To assess the impact of SNP saturation on macrophage phenotypes and immune responses.

Main Methods:

• RAW 264.7 macrophages were saturated with silica nanoparticles (SNPs) of varying sizes, porosities, densities, and surface compositions.
• Gene expression and immune signaling pathways were analyzed using RNA sequencing, WGCNA, and Hallmark/KEGG pathway analyses.
• Cytokine levels (TNF-alpha, IL-6, IL-12p70) were measured using multiplex immunoassays.

Main Results:

• SNP size had minimal impact on gene expression profiles; porosity significantly altered them.
• Porous SNPs induced unique and increased gene expression changes compared to nonporous SNPs.
• Key immune pathways (TNF-alpha/NF-κB, mTORC1, p53) were modulated by SNP saturation, dependent on particle properties.
• SNP uptake increased TNF-alpha cytokine levels, but not IL-6 or IL-12p70.

Conclusions:

• Physicochemical properties of silica nanoparticles, particularly porosity, significantly influence macrophage gene expression and immune signaling.
• These findings provide crucial insights into the immunomodulatory effects of SNPs.
• Guidance for selecting safe and effective silica nanoparticles for systemic delivery of bioactive agents can be derived from these results.