Bioactive Polysaccharides Prevent Lipopolysaccharide-Induced Intestinal Inflammation via Immunomodulation, Antioxidant Activity, and Microbiota Regulation

Abstract

Intestinal inflammation involves barrier impairment, immune hyperactivation, and oxidative stress imbalance. Bioactive polysaccharides universally alleviate inflammation via anti-inflammatory, antioxidant, and microbiota-modulating effects, yet exhibit distinct core mechanisms. Elucidating these differences is vital for targeted polysaccharide applications. This research examines distinct regulatory pathways through which diverse bioactive polysaccharides mitigate lipopolysaccharide-triggered intestinal inflammation in male Kunming (KM) mice. This experiment employed Lentinula edodes polysaccharide (LNT), Auricularia auricula polysaccharide (AAP), Cordyceps militaris polysaccharide (CMP), Lycium barbarum polysaccharide (LBP), and Brassica rapa polysaccharide (BRP). The expression levels of biomarkers associated with the TLR4 signaling pathway, oxidative stress, and intestinal barrier function were quantified, along with comprehensive gut microbiota profiling. The results showed that all five polysaccharides alleviated inflammatory responses in mice by inhibiting inflammatory cytokine release, reducing oxidative damage, and modulating gut microbiota, but their modes of action differed: LBP significantly suppressed the TLR-4/MyD88 signaling pathway and its downstream pro-inflammatory cytokine expression, thereby blocking inflammatory signal transduction and reducing oxidative damage; LNT and CMP enhanced the body's antioxidant capacity by increasing antioxidant enzyme activities and decreasing malondialdehyde (MDA) levels; AAP and BRP enriched Akkermansia (Akk.) within the Verrucomicrobia (Ver.) phylum, upregulating tight junction protein expression to strengthen the intestinal mucosal barrier and indirectly reduce oxidative damage. This research demonstrates that different polysaccharides alleviate inflammation through multi-target synergistic mechanisms: LBP primarily inhibits inflammatory pathways; AAP and BRP focus on intestinal barrier protection and microbiota modulation; and LNT and CMP exert effects via antioxidant enzyme activation. These data support designing polysaccharide blends that leverage complementary inflammatory modulation mechanisms.

Keywords: IBD; NF-κB/MyD88 signaling pathway; gut microbiota; intestinal barrier; oxidative stress; prebiotics.

Figure 1

The influence of polysaccharides on the disease activity index. (n = 6). * p < 0.05, ** p < 0.01, ^ns p < 0.05.

Figure 2

Effects of polysaccharides on antioxidant indicators (n = 6). (A) Plasma GSH-Px, (B) Plasma CAT, (C) Plasma T-AOC, (D) Plasma MDA, (E) Plasma SOD, (F) Liver GSH-Px, (G) Liver CAT, (H) Liver T-AOC, (I) Liver MDA, and (J) Liver SOD. ^∆ p < 0.05, ^∆∆ p < 0.01, relative to the CON group. * p < 0.05, ** p < 0.01, relative to the LPS group.

Figure 3

Effects of polysaccharides on immune indicators. (n = 6). (A) Plasma IgA, (B) Plasma IgA, (C) Plasma IgM, (D) Plasma TNF-α, (E) Jejunal IgA, (F) Jejunal IgA, (G) Jejunal IgM, (H) Jejunal TNF-α, (I) Plasma IL-1β, (J) Plasma IL-4, (K) Plasma IL-23A, (L) Jejunal IL-1β, (M) Jejunal IL-4, and (N) Jejunal IL-23A.^∆ p < 0.05, ^∆∆ p < 0.01, relative to the CON group. * p < 0.05, ** p < 0.01, relative to the LPS group.

Figure 4

Effect of polysaccharides on the expression of immune and intestinal barrier-related genes (n = 6). (A) Jejunal TLR4, (B) Jejunal MyD88, (C) Jejunal Nf-κB, (D) Jejunal TNF-α, (E) Liver TLR4, (F) Liver MyD88, (G) Liver Nf-κB, (H) Liver TNF-α, (I) Jejunal Occludin, (J) Jejunal ZO-1, and (K) Jejunal MuC2. ^∆ p < 0.05, ^∆∆ p < 0.01, relative to the CON group. * p < 0.05, ** p < 0.01, relative to the LPS group.

Figure 5

The effects of different polysaccharides on the species diversity of the intestinal flora (n = 6). (A) PCoA plot, (B) Petal plot presents each group of OTUs, (C) shannon, (D) pielou_e, (E) observed features, (F) dominance, (G) good_coverage, (H) chao1, (I) simpson.

Figure 6

Effects of various polysaccharides on the intestinal microbiota at the phylum level (n = 6): (A) Campylobacterota, (B) Firmicutes, (C) Proteobacteria, and (D) Verrucomicrobiota, and (E) The role of polysaccharides in regulating the structure of intestinal microbiota at the phylum level. ^∆ p < 0.05, ^∆∆ p < 0.01, relative to the CON group. * p < 0.05, ** p < 0.01, relative to the LPS group.

Figure 7

Effects of various polysaccharides on the intestinal microbiota at the family level (n = 6): (A) Akkermansiaceae, (B) Lachnospiraceae, (C) Helicobacteraceae, and (D) Sutterellaceae, and (E) The role of polysaccharides in regulating the structure of intestinal flora at the genus level. ^∆∆ p < 0.01, relative to the CON group. * p < 0.05, ** p < 0.01, relative to the LPS group.

Figure 8

Effects of various polysaccharides on the intestinal microbiota at the genus level (n = 6): (A) Lachnospiraceae, (B) Helicobacteraceaei, (C) Akkermansia, and (D) Sutterellaceae; (E) The role of polysaccharides in regulating the genus-level structure of intestinal microbiota; and (F) LEfSe analysis. ^∆∆ p < 0.01, relative to the CON group. * p < 0.05, ** p < 0.01, relative to the LPS group.

Figure 9

Heat map of the results of correlation analysis: (A) Correlation analysis of inflammatory factors, antioxidants, and intestinal barrier related indicators; (B) Inter-group cluster analysis of inflammatory factors, antioxidants, and intestinal barrier-related indicators; (C) Cluster analysis of plasma inflammatory factors, antioxidant indicators, and intestinal flora. Red signifies positive correlation, with intensity proportional to depth (deeper red indicating stronger positive correlation); blue denotes negative correlation, with intensity similarly proportional to depth (deeper blue indicating stronger negative correlation). * p < 0.05, ** p < 0.01.