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, GBM 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 the activation of desired inflammatory response using non-agonistic β-glucan particles; a well-known ligand for Dectin-1 receptors. Our study is therefore focused to explore the role of nano-encapsulated CpG ODN as critical players in polarizing M2 scavenging to much desired pro-inflammatory type. The nanoparticles entrapping CpG ODN 1826 were prepared by using a fungal polymer Schizophyllan (SPG). The constructed nanoparticles were characterized and assessed for their efficacy on rat glioblastoma cells (C6). 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 evaluated for intracellular oxidative burst and cytokine levels pre- and post-incubation with nanoparticles exhibited marked elevation in the expression of intracellular ROS and IFN-γ as well as IL-1β post treatment. The findings indicate towards potentiality of repolarizing the M2 macrophages to much desired M1 phase by inducing higgh levels of oxidative burst and inflammatory cytokines. Consequently, the apoptosis was induced in glioblastoma cells establishing the suitablity of CpG ODN carrying nanoformulations as emerging therapeutic intervention for GBM.