β-glucan from Saccharomyces cerevisiae is involved in immunostimulation of ovine ruminal explants

In this study, we investigated whether β-glucan from Saccharomyces cerevisiae exerts beneficial effects on mucosal immunity in an ovine ruminal explant (ORE) model. Once the ORE model was established, viability was assessed through histological change, E-cadherin expression, CK-18 and Ki-67 distribution. Then, the OREs were co-cultured with β-glucan, following which, gene and protein expression levels of sheep β-defensin-1 (SBD-1), pro-inflammatory interleukin (IL)-6, and anti-inflammatory IL-10 were detected using quantitative real-time polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA). Hematoxylin & eosin staining, qPCR, and immunohistochemistry showed that the overall ORE structure was intact after 96 hours in culture, but explants cultured for more than 24 hours showed epithelial degradation. Therefore, we performed the follow-up test within 24 hours. qPCR and ELISA revealed that the gene and protein expression levels of SBD-1, IL-6, and IL-10 in the OREs significantly increased (P < 0.05) after treatment with β-glucan compared with controls. This study identified the feasibility and optimal conditions of ORE culture and demonstrated that β-glucan activates SBD-1, IL-6, and IL-10 secretion in OREs to promote mucosal immunity.