Delivery of polysaccharides from Ophiopogon japonicus (OJPs) using OJPs/chitosan/whey protein co-assembled nanoparticles to treat defective intestinal epithelial tight junction barrier

The polysaccharides from Ophiopogon japonicus (OJPs) were known to have protective effects against diabetes, and cardiovascular and chronic inflammatory diseases. However, OJPs were poorly absorbed after oral administration, resulting in limited efficacy because of the low bioavailability. In this study, OJPs extracted and fractionated from Ophiopogon japonicus were used to prepare OJPs/chitosan (CS)/whey protein (WP) co-assembled nanoparticles. The OJPs/CS/WP nanoparticles showed high biocompatibility and inhibited the cytotoxicity of RAW264.7 cells induced by nickel. With the assistance of CS and WP, the anti-inflammatory and antioxidant activities of OJPs were enhanced because the nanoparticles improved OJPs uptake by RAW264.7 macrophage cells as evidenced by efficient scavenging of DPPH and ABTS free radicals and effective inhibition of NO production and the gene expressions of iNOS, COX2, TNF-α, CCL2, and CXCL2 inflammatory signals. Determining the transepithelial electrical resistance and paracellular permeability of Caco-2 monolayer/macrophage co-cultured system suggested that the OJPs-loaded nanoparticles effectively protected the intestinal epithelial barrier integrity against the damage caused by LPS-stimulated macrophage inflammation and attenuated the defects of intestinal epithelial TJ barrier and permeability. These findings suggest that the OJPs/CS/WP nanoparticles may be potential carriers for oral delivery of OJPs to treat intestinal barrier defects, such as inflammatory bowel disease (IBD).