Adlay Seeds Fermented by Lactobacillus plantarum NCU137 Regulates Immunity and Intestinal Mucosal Barrier Function in Immunosuppressed Mice

Objective: To compare the regulatory effects of adlay (Coix lachryma-jobi L.) seeds fermented and not fermented by Lactobacillus plantarum NCU137 on immune and intestinal mucosal barrier function in mice induced by cyclophosphamide (CTX). Methods: BALB/c mice were randomly divided into four groups, including normal, CTX-induced model, non-fermented adlay seed (NFC) and fermented adlay seed (FC) treatment. The mice in the normal and CTX groups were orally administrated with 0.2 mL of physiological saline for 10 days, while those in the NFC and FC groups 0.2 mL of non-fermented and fermented adlay seeds for 10 days, respectively. The immunosuppressed mouse model was established by daily intraperitoneal injection of 100 mg/kg of CTX for the last three days of the administration period, while the normal group was intraperitoneally injected with the same volume of normal saline. Spleen index, the number of spleen T lymphocyte subsets, and the levels of cytokines and immunoglobulin were measured, histopathological examination of the small intestine was performed and intestinal mucosal barrier function was detected. Results: Compared with the CTX group, fermented adlay seeds significantly increased the spleen and thymus indexes of immunosuppressed mice, up-regulated the cluster of differentiation (CD) 4⁺/CD8⁺ ratio of spleen T lymphocytes, down-regulated the levels of spleen pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), and increased serum immunoglobulin (Ig) M and IgG levels. Moreover, fermented adlay seeds repaired small intestinal mucosal structure and up-regulated the gene expression of Occludin and E-cadherin, and the effect was more pronounced than that of non-fermented adlay seeds. Conclusion: Coix lachryma-jobi L. seeds fermented by L. plantarum NCU137 have the potential to regulate immune and intestinal mucosal barrier function, which are expected to be developed into a novel health food with immunomodulatory function.