In vitro and in vivo characterization of anti-inflammatory and antioxidant properties of colloidal lignin particles towards microglia

Lignin is the second most abundant polymer on Earth, and it can be found in almost all types of plants and wood. It is the main waste product of paper industry and is therefore a low-cost and abundant by-product. To valorise it, researchers have imagined and developed different applications, including nanoparticles with promising biological properties such as low toxicity, antioxidant and anti-inflammatory effects, making them good candidates for drug delivery systems. In this study, we aimed to prepare and evaluate the antioxidant and anti-inflammatory properties of colloidal lignin particles (CLPs) extracted from softwood, and their potential use as a drug delivery system to target neuroinflammation. First, the biological properties of CLPs were studied in vitro using the BV2 microglial cell line. We showed that CLPs are non-toxic, are rapidly internalized by cells, and can protect them from both inflammation and oxidative stress induced by bacterial lipopolysaccharide (LPS). Moreover, using an LPS-induced mouse model of systemic and neuroinflammation, we showed that CLPs significantly reduce the expression of inflammatory mediators, and the activation of microglia. These findings demonstrate the promising bioactive properties of CLPs in the context of neuroinflammation, and their potential use either as therapeutics on their own or as an effective drug delivery system to treat brain disorders.