An in vitro study on gut mucosal immunomodulation by peptides derived from fermented soybean meal
Date Issued
2014
Date
2014
Author(s)
Chi, Ming-Hui
Abstract
The majority of infectious diseases of animals and humans occur at mucosal surfaces, especially in the intestinal tract. The mucosa is the principal site for the immune system’s interaction with the outside environment, it can protect our body from pathogenic organisms. Intestine is the largest lymphoid organ in human body. Recent researches showed that intestinal epithelial cells (IEC) may play key role in maintaining the homeostasis and modulating the immune response. Soybean meal is the byproduct of soybean oil production. It has been used extensively as an important source of dietary protein in the feed industry because of their high protein content. It has been reported that peptides derived from soy protein have immunomodulating activity. Thus, the aim of this research was to evaluate the effects of peptides derived from fermented soybean meal on mucosal immune response. Mixture of soybean meal and wheat was fermented with different microorganisms, including Aspergillus oryzae BCRC 30428, Rhizopus oryzae BCRC 31150, Bacillus subtilis BCRC 14715. These microbes are commonly used as starters in the fermentation of many traditional, oriental food products. The IEC-6 cell line from the rat normal small intestine cell was used as the cell model to evaluate whether peptides from fermented soy products could increase IL-6 and IL-10 cytokines secretion, inhibit LPS induced inflammatory cytokines and decrease intracellular permeability. First, we determined the transepithelial resistance (TER) value of IEC-6 cell line, and found its TER value is approximately 80.82 ± 2.75 Ω ‧ cm2, which is similar to the complete rat intestinal tissue (50-100 Ω ‧ cm2). Therefore, the IEC-6 cell can be used as a cell monolayer to assess the epithelial barrier function. Results showed that disregard the kind of starter used, the water extract of fermented soybean meal could increase proliferation of the rat intestinal epithelial cells, and this effect would be enhanced when fermentation time was increased. For the permeability of IEC-6 cells, our results showed that only the water extract of B. subtilis natto fermented soybean meal could maintain the integrity of the epithelial barrier. Therefore, we further treated the cells with LPS to increase of permeability in IEC-6 cells, and in the meantime the cell culture were also given water extract of B. subtilis natto fermented soybean meal. We found the water extract of the fermented product could significantly recover the level of transepithelial resistance. This result demonstrated that the water extract of B. subtilis natto fermented soybean meal had protective effect on rat intestinal epithelial cells and can decrease mucosal injury. In addition, the water extracts of soybean meal fermented by B. subtilis natto could inhibit the LPS induced inflammation in intestinal epithelial cells, and its bioactivity increased with increase of fermentation time. And it could also up-regulate the level of IL-10. We further used the size exclusion chromatograph to separate the peptides based on their molecular weights, and then identified the peptides which has the bioactivity of mucosal immunomodulation.
Subjects
黏膜免疫
大豆粕
小麥
固態發酵
胜肽
小腸上皮細胞
SDGs
Type
thesis
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