Repolarization of glioblastoma macrophage cells using non-agonistic Dectin-1 ligand encapsulating TLR-9 agonist: plausible role in regenerative medicine against brain tumor.

Glioblastoma multiforme (GBM) is the most severe forms of brain cancer, eventually becoming the leading cause of brain cancer-related death worldwide. Owing to the bleak surgical interventions and resistance to the different treatment regime, glioblastoma multiforme is a parlous disease demanding newer therapeutical perspective for its treatment. Toll-like Receptors (TLRs) are well-known members of Pathogen Recognition Receptors (PRRs) and have been extensively explored for their therapeutic and prophylactic potential in an array of disease including cancer. Recent trends in drug delivery research has shown shift towards delivering short DNA sequences (CpG DNA) to endosomal TLR9 within immune cells (macrophages, dendritic cells, etc.) for activation of desired inflammatory response using non-agonistic β-glucan particles; a well-known ligand for Dectin-1 receptors. Our study explores the role of nano-encapsulated CpG ODN as critical players in polarizing M2 scavenging to much desired pro-inflammatory type. The constructed Schizophyllan (SPG) nanoparticles entrapping CpG ODN 1826 (95.3%) were of 25.49 nm in diameter and thus capable of crossing blood-brain barrier. The rat glioblastoma (C6) cells were evaluated for intracellular oxidative burst and cytokine levels pre and post incubation with CpG ODN and nanoparticles. The cells prior to treatment exhibited high levels of IL-4 and low levels of IFN-γ and IL-1β. However, post treatment results revealed significantly high expression of intracellular ROS and IFN-γ as well as IL-1β. These alterations indicated towards the repolarization of macrophages from M2 to M1phase.