Comparison of the Anti-inflammatory Activity and Cellular Interaction of Brush Polymer-N-Acetyl Cysteine Conjugates in Human and Murine Microglial Cell Lines

Microglia-mediated neuroinflammation is commonly asso-ciated with neurodegeneration and has been implicated in several neurological disorders, such as Alzheimer's disease and Parkinson's disease. Therefore, it is crucial to develop a detailed understanding of the interaction of potential nanocarriers with microglial cells to efficiently deliver anti-inflammatory molecules. In this study, we applied brush polymers as a modular platform to systematically investigate their association with murine (BV-2) and human (HMC3) microglial cell lines in the presence and absence of the pro-inflammatory inducer lip-opolysaccharide (LPS) using flow cytometry. Brush polymers of different sizes and shapes, ranging from ellipsoid to worm-like cylinders, were prepared through a combination of the two building blocks carboxylated N- acylated poly(aminoester)s (NPAEs)-based polymers and poly(2-ethyl-2-oxazoline)-NH2 (PEtOx-NH2) and characterized by H-1 NMR spectroscopy, size exclusion chromatography, and small-angle neutron scattering. Generally, ellipsoidal particles showed the highest cellular association. Moreover, while no significant differences in murine cell association were observed, the brush polymers revealed a significant accumulation in LPS-activated human microglia compared to resting cells, emphasizing their higher affinity to activated HMC3 cells. Brush polymers with the highest cell association were further modified with the anti-inflammatory agent N-acetyl cysteine (NAC) in a reversible manner. The brush polymer-NAC conjugates were found to significantly attenuate the production of interleukin 6 (p < 0.001) in LPS-activated HMC3 cells compared to LPS-activated BV-2 cells. Thus, the presented brush polymer-NAC conjugates showed a high anti-inflammatory activity in human microglia, suggesting their potential for disease-targeted therapy of microglial-mediated neuroinflammation in the future.

Automated summary

In this study, brush polymers were used to investigate their interaction with murine and human microglial cells and their potential for delivering anti-inflammatory molecules. Ellipsoidal particles showed the highest cellular association, and LPS-activated human microglia exhibited a significant increase in association with brush polymers. Brush polymer-NAC conjugates showed significant anti-inflammatory activity in LPS-activated human microglia. These findings suggest the potential of brush polymers for targeted therapy of microglial-mediated neuroinflammation.