Eugenol-Encapsulated Nanocarriers for Microglial Polarisation: a Promising Therapeutic Application for Neuroprotection

Abstract

Neuroinflammation is an important hallmark of central nervous system (CNS) disorders like Alzheimer’s and Parkinson’s disease. It is caused by the prolonged activation of microglia, resident immune cells of the brain. Microglia cells are considered to be the first line of defence in our central nervous system. Depending on the local environment, these brain macrophage cells can adopt different phenotypic states to carry out downstream functions. They undergo polarisation to change into the pro-inflammatory or anti-inflammatory phenotype, causing either neuroinflammation or neuroprotection. Novel therapeutic approaches which aim to control microglial polarisation properties are thus considered. This study investigates the possibility of microglial polarisation properties of eugenol, a polyphenol, after encapsulating it in a lipid nanocarrier system. As part of the current study, eugenol-loaded lipid nanocarriers of size less than 200 nm was synthesised, and their cytotoxicity on neuronal and non-neuronal cell lines was tested. In lipopolysaccharide (LPS)-induced BV2 microglia cells, the two test concentrations of eugenol-loaded nanocarriers resulted in reduced nitrite concentration, indicating a switch from the pro-inflammatory to an anti-inflammatory state.