Effects of pectin-type polysaccharides derived from Houttuynia cordata on the intestinal immune system in native C3H/HeN mice.

Dietary polysaccharides have attracted considerable attention because of their species-specific chemical composition and diverse biological activities. Polysaccharides derived from Houttuynia cordata (HC) exhibit broad pharmacological activities, emphasizing their diverse roles in biological processes. This study investigated the effects of HC-derived polysaccharides on Peyer's patch (PP)-mediated intestinal immune response. The crude polysaccharide (HCP) isolated from HC extract (HCE) was identified as a pectin-type polysaccharide rich in the homogalacturonan (HG) domain, which was further hydrolyzed by endo-polygalacturonase to produce HCPE. In vitro, HCPE significantly enhanced PP-mediated cytokine secretion and bone marrow cell (BMC) proliferation compared with HCP. In vivo, a 4-week treatment with oral HCPE stimulated PP-mediated secretion of hematopoietic growth factors and promoted BMC proliferation. Additionally, HCPE upregulated IgA-associated factors, leading to increased IgA levels in the small intestine, serum, and feces, while also significantly elevating short-chain fatty acid levels, potentially improving the gut environment. To the best of our knowledge, this is the first study to systematically analyze PP-mediated intestinal immunostimulatory activity of HC-derived polysaccharides both in vitro and in vivo. These findings provide valuable insights into the potential of HCPE as an intestinal immunostimulatory agent and establish a foundation for future research on the immunological effects of HC-derived polysaccharides.