Süer Özge, Gül Aytül, Hameş Elif Esin
Department of Bioengineering, Graduate School of Natural and Applied Sciences, Ege University, Izmir, Türkiye.
Department of Food Engineering, Faculty of Engineering, Izmir University of Economics, Izmir, Türkiye.
Cellulose (Lond). 2023;30(7):4263-4276. doi: 10.1007/s10570-023-05138-3. Epub 2023 Mar 30.
Bacterial cellulose (BC) is an unbranched biopolymer produced by microorganisms and composed of glucopyranose units linked by β-1,4 bonds. This study investigates the adjuvant action of needle-shaped BC microfibrils (BCmFs) in vitro using bovine serum albumin (BSA) as a model antigen. BC produced by the static culture of was then microparticled (1-5 μm) by acid hydrolysis and characterized using Dynamic Light Scattering and Scanning Electron Microscopy. Subsequently, Attenuated Total Reflectance-Fourier-Transform Infrared Spectroscopy, cytotoxicity, TNF-α (tumour necrosis factor-alpha) and IL-6 (interleukin-6) cytokine secretion, and cellular uptake of the BCmFs-BSA conjugate on the human monocyte cell line (U937) differentiated into macrophages were performed. The microfibrils were determined to be 1-5 μm in size, needle-shaped, with a zeta potential of - 32 mV. Their conjugation with the model antigen, BSA, was demonstrated by FTIR analysis. In the cytotoxicity assay, BCmFs-BSA in macrophage cells showed high viability (over 70%). Although the highest TNF-α cytokine level (113 pg/ml) was obtained with BCmFs-BSA (Bovine serum albumin) conjugate (500 µg/ml) and was statistically significant ( = 0.0001) compared to the positive control group (BSA-aluminium 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 microbially synthesized BC in the form of needle-shaped microfibrils (BCmFs) has a high cellular uptake capacity and increases the immunogenicity of the antigen. These results demonstrate for the first time that BCmFs have the potential to serve as a vaccine adjuvant.
细菌纤维素（BC）是一种由微生物产生的无分支生物聚合物，由通过β-1,4键连接的吡喃葡萄糖单元组成。本研究以牛血清白蛋白（BSA）作为模型抗原，在体外研究了针状BC微纤维（BCmFs）的佐剂作用。然后，通过酸水解将静置培养产生的BC制成微粒（1-5μm），并使用动态光散射和扫描电子显微镜对其进行表征。随后，对分化为巨噬细胞的人单核细胞系（U937）进行衰减全反射傅里叶变换红外光谱、细胞毒性、TNF-α（肿瘤坏死因子-α）和IL-6（白细胞介素-6）细胞因子分泌以及BCmFs-BSA缀合物的细胞摄取实验。测定微纤维的大小为1-5μm，呈针状，ζ电位为-32mV。通过傅里叶变换红外光谱分析证明了它们与模型抗原BSA的缀合。在细胞毒性试验中，巨噬细胞中的BCmFs-BSA显示出高活力（超过70%）。尽管BCmFs-BSA（牛血清白蛋白）缀合物（500μg/ml）获得了最高的TNF-α细胞因子水平（113pg/ml），并且与阳性对照组（BSA-氢氧化铝）相比具有统计学意义（P = 0.0001），但IL-6细胞因子水平与对照组相比没有达到预期的统计学差异。在分化为巨噬细胞的U937细胞中已表明，呈针状微纤维（BCmFs）形式的微生物合成BC具有高细胞摄取能力，并增加了抗原的免疫原性。这些结果首次证明BCmFs有潜力用作疫苗佐剂。
