069 | Comparative analysis of inflammatory and redox responses in human and rat macrophages exposed to calcium-doped mesoporous silica nanoparticles

Styliani Axypolitou¹, Antonietta Ligas², Ioannis Tsamesidis¹, Georgia K. Pouroutzidou¹, Pier Luigi Fiori², Antonella Pantaleo², Eleana Kontonasaki¹ | ¹Department of Prosthodontics, School of Dentistry, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece ²Department of Biomedical Sciences, Division of Microbiology and Virology, University of Sassari, Italy.

Macrophages are key regulators of innate immunity, coordinating inflammatory signaling and oxidative stress responses in the presence of foreign materials. As nanomaterials gain increasing attention for biomedical applications, understanding their interactions with immune cells is essential to ensure both safety and therapeutic efficacy. Among these, calcium-doped mesoporous silica nanoparticles (Ca–MSNs) have emerged as particularly promising due to their high surface area, tunable porosity, and bioactive calcium content, which together support applications in drug delivery, tissue regeneration, and immunomodulation. In this study, we systematically investigated the impact of Ca–MSNs on macrophage function using rat RAW 264.7 cells and human THP-1-derived macrophages. Cell viability was assessed by MTT assay, revealing a dose-dependent response in both cell types, with the highest viability observed at 0.125 mg/mL SiCa. ROS production remained comparable to control cells across all concentrations, indicating that Ca–MSNs did not induce oxidative stress under the tested conditions. To further evaluate inflammatory responses, ELISA assays were performed to measure TNF-α and IL-10 secretion in RAW 264.7 cells. SiCa treatment significantly suppressed TNF-α release in a dose-dependent manner, with the strongest effect at 0.125 mg/mL, while IL-10 secretion showed a modest increase at the lowest concentration at the later stage of incubation (day 3), suggesting limited promotion of M2-like polarization. Additionally, RT-PCR analysis was used to examine the expression of key macrophage-related genes, including TNF-α as a marker of pro-inflammatory (M1) polarization and Arginase-1 as an indicator of anti-inflammatory (M2) polarization. Collectively, our data demonstrate consistent responses across both macrophage cell lines. Notably, the lowest concentration of Ca–MSNs was well tolerated by both cell models and effectively modulated inflammatory signaling while maintaining oxidative homeostasis, highlighting their potential as safe and effective immunomodulatory nanomaterials for biomedical applications.