Isolation and characterisation of a high molecular mass beta-glucan from Lactobacillus fermentum Lf2 and evaluation of its immunomodulatory activity

ANA VITLIC; SOHAIB SADIQ; HAFIZ AHMED; ELISA C. ALE; ANA BINETTI; ANDREW COLLETT; PAUL HUMPHREYS; ANDREW P. LAWS

CARBOHYDRATE RESEARCH

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2019

0008-6215

When grown in a semi-defined medium, L. fermentum Lf2 synthesizes significant quantities (~2 g/L) of two exopolysaccharides (EPS). The two EPS were separated by preparative size exclusion chromatography to give a high molecular mass beta-glucan (1.23 x 106 Da) and a medium molecular mass heteroglycan (8.8 x 104 Da). The structure of the high molecular mass beta-glucan was determined using a combination of NMR spectroscopy, monomer and linkage analysis. The EPS has the following structure: →3)-b-D-Glcp-(1→3)-b-D-Glcp-(1→ 2 1  b-DGlcp The immunomodulatory activity of the high molecular mass EPS was studied in peripheral mononuclear blood cells (PBMC). Exposure of PBMC to an aqueous solution of the EPS for 24 h led to increased cell proliferation,changes in expression of the cytokines CD14 and TLR2, and to an increase in production of TNF-alpha compared to controls. In contrast, when cells that had been treated with EPS for 24 h and from which the EPS had been removed,were subsequently exposed to the bacterial antigen LPS very low levels of TNF-alpha production were observed. This result indicates that the EPS imparts immunotolerance in PBMC. An ability to modulate the release of theproinflammatory mediators, such as TNF-alpha, is an important goal in the development of therapies for the treatment of diseases, such as Crohn?s disease and ulcerative colitis, associated with excessive release of inflammatorymediators.