Anti-Inflammatory Activity of Oat Beta-Glucans in a Crohn's Disease Model: Time- and Molar Mass-Dependent Effects.

BACKGROUND: The incidence of Crohn's disease (CD) is increasing worldwide, and it has currently become a serious public health issue in society. The treatment of CD continues throughout a patient's lifetime, and therefore, it is necessary to develop new, effective treatment methods, including dietotherapy. The present study aimed to determine the effects of consumption of oat beta-glucans with different molar mass on colon inflammation (colitis) in the early stages of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced CD in an animal model. METHODS: Sprague-Dawley rats (control and TNBS-induced CD) were divided into three dietary groups and fed for 3 days (reflecting acute inflammation) or 7 days (reflecting remission) with a feed containing 1% low (ßGl) or high (ßGh) molar mass oat beta-glucan or a feed without this polysaccharide. The level of colon inflammatory markers and the expression of cytokines and their receptor genes were measured by ELISA and RT-PCR methods, respectively. RESULTS: Acute inflammation or remission (3 or 7 days after TNBS administration, respectively) stages of experimentally induced CD were characterized by an increase in the level of inflammatory markers (IL-1, IL-6, IL-10, IL-12, TNF-α, CRP, MPO, COX, and PGE2) and the disruption of some cytokine signaling pathways as well as macro- and microscopic changes of colon tissue. The consumption of oat beta-glucans reduced the level of inflammatory markers and recovered the signaling pathways and histological changes, with stronger effects of ßGl after 7 days of colitis. CONCLUSIONS: Dietary oat beta-glucans can reduce colitis at the molecular and organ level and accelerate CD remission.

Proteinaceous Residue Removal from Oat ß-Glucan Extracts Obtained by Alkaline Water Extraction.

Background: Wet methods of 1-3, 1-4 -ß-D-glucan isolation from cereals differ mainly in the type of grain fraction used as raw material, the solid-liquid ratio of ß-glucan in raw material vs. solvent used, and the type of aqueous solvent modification (alkali, neutral or acidic). All these factors impact the characterization of the residues finally found in extracts. Oat bran is a rich source of globulin fraction which can be transferred into the extracts, especially when a high pH is employed. Methods: A multi-stage (enzymatic and acidic) purification procedure was performed to remove the residues, especially starch and protein, from ß-glucan isolates from oat of different molar mass. Pancreatin, thermostable α-amylase, amyloglucosidase, and papain were used for consecutive residue removal. Three levels of low pH = 4.5, 3.5 and 3.0 were also tested for effective protein precipitation. Results: The starch hydrolysis and liquefaction significantly facilitate the proteinaceous matter removal although papain usage showed an intensive unfavorable impact on ß-glucan molar mass. Soluble protein content was significantly decreased after pancreatin and α-amylase treatment, while the significant reduction of amine nitrogen was noted after complete starch hydrolysis and a second acidification step. Conclusions: A complex procedure employing different enzymes is needed to successfully reduce the possibly bioactive residues in isolated oat ß-glucan fractions.

Beneficial Effects of Oat Beta-Glucan Dietary Supplementation in Colitis Depend on its Molecular Weight.

BACKGROUND: Inflammatory bowel diseases are an important health problem. Therefore, the aim of the present study was to compare the impact of isolated oat beta-glucan fractions of low and high molecular weight, taken as dietary supplementation, on inflammatory markers in the colitis model. METHODS: Two groups of Sprague-Dawley rats-control and with experimentally induced colitis-were subsequently divided into three subgroups and fed over 21 days feed supplemented with 1% of low (ßGl) or high (ßGh) molecular weight oat beta-glucan fraction or feed without supplementation. The level of colon inflammatory markers, cytokines, and their receptors' genes expressions and immune cells numbers were measured by ELISA, RT-PCR, and by flow cytometry methods, respectively. RESULTS: The results showed moderate inflammation affecting the colon mucosa and submucosa, with significant changes in the number of lymphocytes in the colon tissue, elevated cytokines and eicosanoid levels, as well as disruption of the main cytokine and chemokine cell signaling pathways in colitis rats. Beta-glucans supplementation caused a reverse in the percentage of lymphocytes with stronger effects of ßGh and reduction of the levels of the inflammatory markers, and improvement of cytokine and chemokine signaling pathways with stronger effects of ßGl supplementation. CONCLUSIONS: The results indicate the therapeutic effect of dietary oat beta-glucan supplementation in the colitis in evident relation to the molecular weight of polymer.

Time-Dependent Indirect Antioxidative Effects of Oat Beta-Glucans on Peripheral Blood Parameters in the Animal Model of Colon Inflammation.

Background: Oat beta-glucans are polysaccharides, belonging to soluble fiber fraction, that show a wide spectrum of biological activity. The aim of this study was to evaluate the time-dependent antioxidative effect of chemically pure oat beta-glucan fractions, characterized by different molar mass, which were fed to animals with early stage of 2,4,6-trinitrobenzene sulfonic acid (TNBS) - induced colitis. Methods: The study was conducted on 150 adult male Sprague Dawley rats assigned to two groups-healthy control (H) and colitis (C) with colon inflammation induced by per rectum administration of TNBS. The animals from both groups were divided into 3 nutritional subgroups, receiving for 3, 7 or 21 days AIN-93M feed without beta-glucan (ßG-) or with 1% (w/w) low molar mass oat beta-glucan (ßGl+) or 1% (w/w) high molar mass oat beta-glucan (ßGh+). After 3, 7 and 21 days, the animals were euthanized, peripheral blood was collected from the heart for further analysis. Results: The results of analyses performed on blood samples showed small changes in lymphocytes count and red blood cell parameters such as the number of red blood cell, mean corpuscular hemoglobin concentration and mean corpuscular volume (RBC, MCHC, MCV respectively) as well as normalization of antioxidant potential accompanying moderate inflammatory state of colon mucosa and submucosa. Conclusion: Oat beta-glucans exert an indirect antioxidant effect in animals with TNBS-induced colitis, with greater effectiveness in removing systemic effects of colon inflammation found for low molar mass oat beta-glucan.