Abstract: The purpose of this study was to investigate the effect of low-molecular-mass seleno-aminopolysaccharide (LSA) on the histomorphology and the expression of the tight junction proteins zonula occludens-1 (ZO-1) and occludin in the ileum of immunocompromised mice. The immunosuppressive mouse model was established by intraperitoneal injection of cyclophosphamide (CPA). The thymus index and spleen index were calculated. Pathological changes in the spleen and jejunum were observed by hematoxylin-eosin staining. The expression of tight junction proteins in the ileum were analyzed by real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR). The results showed that the spleen and thymus index were significantly increased in the LSA groups (P < 0.05) when compared with the CPA group. The spleen structure was clear with an obvious boundary between the red and white pulps and the area of white pulp was increased in the 0.6 and 0.9 mg/(kg mb·d) LSA groups when compared with the CPA group. In addition, the morphology of jejunum villi was more ordered than that of the model group. The mRNA expression of ZO-1 and occludin was significantly increased in the 0.6 mg/(kg mb·d) LSA group (P < 0.05). To sum up, LSA had immunomodulatory effects and could be beneficial for intestinal health.

Key words: low-molecular-mass seleno-aminopolysaccharide, immunosuppression, zonula occludens-1, occludin