Reduction of Inflammatory Responses by Mannan Rich Fraction

Abstract

Six yeast cell wall products were tested for their ability to agglutinate Escherichia coli (E. coli) or Salmonella typhimurium (S. typhimurium). Product B, Product E, and Product A agglutinated over 70% of E. coli. Product F and Product C agglutinated approximately 69% and 60% of E. coli, respectively, while Product D agglutinated approximately 46% of the E. coli. Product E and Product A agglutinated nearly 70% of S. typhimurium. Product F agglutinated approximately 62% cells, and Product B and Product C agglutinated close to 60% of S. typhimurium. Product D agglutinated only 46% of S. typhimurium. Mannose residues mediated the agglutination of E. coli and S. typhimurium by these yeast products.

An in vitro study the effect of mannan rich fraction (MRF) on the inflammatory responses of chicken macrophage cell lines (MQ-NCSU and HTC) to LPS showed that MRF by itself did not induce either MQ-NCSU or HTC chicken macrophages to produce nitrite or interleukin-6 (IL-6). The nitrite and IL-6 production of these cell lines were significantly increased when they were stimulated with LPS, but MRF significantly reduced nitrite and IL-6 production of these LPS-stimulated cells. MRF down-regulated inducible nitric oxide synthase (iNOS) and IL-6 gene expression of cell lines stimulated with LPS. MRF reduced the expression TLR-4, and possibly activated NF-κB that represses gene expression.

Abdominal exudate cells (AECs) from three-week old broiler chickens fed with a basal diet and challenged with E. coli had a significantly higher nitrite production than cells from non-challenged birds fed with a basal diet. AECs of birds challenged with E. coli and fed with a diet supplemented with MRF showed a significantly lower level of nitrite than cells from challenged birds that were fed with a basal diet. AECs from three weeks old non-challenged broiler chickens fed with MRF produced a significantly higher level of IL-6 than AECs from non-challenged birds fed with a basal diet or challenged birds fed with either a basal diet or MRF. MRF significantly increased body weight gain of E. coli-challenged or non-challenged broiler chickens compared to the body weight gain of challenged birds fed with a basal diet.