236 - Mechanistic insights on the immune and antioxidant response of functionalized cellulose nanocrystals: Does surface charge matter?

Abstract

The interest in derivatives of cellulose nanocrystals (CNCs) for multiple biomedical application has been increasing in the recent years. CNCs is a versatile platform that shows variation in size and dispersion depending on the methods of extraction and preparations, which can impact their reactivity in biological systems. In addition, CNCs are suitable to functionalization with an array of polymers, generating chemically related nanomaterials with different morphologies, surface charges and reactivity. This diversity of physicochemical characteristics can lead to a various biological activities and potentially to undesirable effects, including a robust immune response. Previously, we reported that a cationic CNCs derivative, CNCs-poly(AEMA2), evoked substantial immunological response in mouse and human macrophages, by inducing the secretion of the inflammatory cytokine interleukin-1β (IL-1β). This effect was partially associated with mitochondria-derived reactive species (ROS). In this study we sought to understand the mechanistic differences regarding immunological responses evoked by functionalized CNCs and whether surface charges is associated with this effect. We investigated the effect of a cationic, CNCs-poly(AMPA), and an anionic, CNCs-poly(NIPAAm) derivative on the secretion of inflammatory cytokines, mitochondria-derived ROS and mitochondrial function and antioxidant response as well as on endoplasmic reticulum (ER) stress, in human and murine inflammatory cells. CNCs-poly(AMPA) evoked the greatest immunological response in LPS-stimulated murine cell line, while CNCs-poly(NIPAAm) showed a significant NLRP3 inflammasome-dependent and independent immunological response in non-stimulated human primary monocytes. In addition, CNCs-poly(NIPAAm) increased the generation of acidic vesicular organelles and mitochondrial-ROS as well as increases antioxidant enzymes in non-stimulated cells, while CNCs-poly(AMPA) affected mitochondrial function by decreasing the intracellular ATP. These differences on the mitochondrial function and ER stress response suggest a diverse mechanisms associated with their immune activity. Moreover, these effects may be related with the surface charges of the functionalized CNCs, and their likely interactions with biomolecules in the intra and extracellular milieu.