Effects of two polysaccharides from Lepidium meyenii (maca) on intestinal immunity and inflammation in vitro

In our previous studies, two polysaccharides (MC-1 and MC-2) were identified in the roots of maca (Lepidium meyenii). In this study, the effects of these two polysaccharides on intestinal immunity and inflammation were assessed using intestinal epithelial cells, i.e., Caco-2 cells. The levels of cytokines and tight junction proteins were measured using ELISA and qPCR, respectively. The results showed that MC-1 and MC-2 were difficult to be absorbed in the Caco-2 cell monolayer, but promoted the secretion of IL-8, IL-10, IL-12, and INF-γ in the Caco-2 cells, and the secretion of TNF-α, IL-6, and NO in macrophages (RAW264.7 cells) via the Caco-2 cell monolayer. Additionally, both polysaccharides inhibited damage induced by lipopolysaccharides to the densification of the Caco-2 monolayer membrane by regulating the expressions of TLR4, ZO-1, and occludin. Furthermore, the secretion of inflammatory factors such as TNF-α, IL-8, and INF-γ was inhibited, and the secretion of the anti-inflammatory factor, IL-10, increased. The results indicated that MC-1 and MC-2 can activate intestinal immunity and alleviate intestinal inflammation in vitro.