Adjuvant action of needle shaped BC micro fibrils

Abstract

Abstract Bacterial cellulose (BC) is an unbranched biopolymer produced by microorganisms, composed of glucopyranose units linked by β-1,4 bonds. In this study, the adjuvant action of needle shaped BC micro fibrils (BCmfs) has been investigated in vitro using bovine serum albumin (BSA) as a model antigen. BC produced by the static culture of Komagataibacter xylinus was then microparticleated (1–5 µm) by acid hydrolysis and characterized using Zetasizer and scanning electron microscopy (SEM). Subsequently, cytotoxicity, TNF-α (Tumor necrosis factor alpha) and IL-6 (Interleukin-6) cytokine secretion, and cellular uptake of BCmfs-BSA conjugate on the human monocyte cell line (U937) differentiated into macrophages were performed. In the cytotoxicity assay, BCmfs-BSA in macrophage cells showed high viability (over 70%). The highest TNF-α cytokine level (113 ng/ml) was obtained with BCmfs-BSA (Bovine serum albumin) conjugate (500µg/ml) and was statistically significant (p = 0.0001) compared to the positive control group (BSA-aluminum hydroxide), IL-6 cytokine levels were not statistically different from those in the control group as desired. It has been shown in macrophage-differentiated U937 cells that microbial synthesized BC in the form of needle-shaped micro fibrils (BCmfs) has high cellular uptake capacity and increases the immunogenicity of the antigen. These results demonstrate for the first time that BC micro fibrils have the potential to serve as a vaccine adjuvant.