Polygonatum cyrtonema polysaccharides reshape the gut microbiota to ameliorate dextran sodium sulfate-induced ulcerative colitis in mice

Abstract

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized inflammatory imbalance, intestinal epithelial mucosal damage, and dysbiosis of the gut microbiota. Polygonatum cyrtonema polysaccharides (PCPs) can regulate gut microbiota and inflammation. Here, the different doses of PCPs were administered to dextran sodium sulfate-induced UC mice, and the effects of the whole PCPs were compared with those of the fractionated fractions PCP-1 (19.9 kDa) and PCP-2 (71.6 and 4.2 kDa). Additionally, an antibiotic cocktail was administered to UC mice to deplete the gut microbiota, and PCPs were subsequently administered to elucidate the potential role of the gut microbiota in these mice. The results revealed that PCP treatment significantly optimized the lost weight and shortened colon, restored the balance of inflammation, mitigated oxidative stress, and restored intestinal epithelial mucosal damage. And, the PCPs exhibited superior efficacy in ameliorating these symptoms compared with PCP-1 and PCP-2. However, depletion of the gut microbiota diminished the therapeutic effects of PCPs in UC mice. Furthermore, fecal transplantation from PCP-treated UC mice to new UC-afflicted mice produced therapeutic effects similar to PCP treatment. So, PCPs significantly ameliorated the symptoms, inflammation, oxidative stress, and intestinal mucosal damage in UC mice, and gut microbiota partially mediated these effects.

Keywords: Polygonatum cyrtonema polysaccharides; gut microbiota; inflammation; mucosal damage; oxidative stress; ulcerative colitis.

FIGURE 1

PCPs alleviate pathogenic phenotypic changes in DSS-induced UC mice (n = 8). (A) Schematic representation of animal experimental groups. (B, C): Quantitative analysis of changes in colon lengths of mice in response to DSS. (D) Effect of DSS on the body weights of mice. (E–H): Evaluation of the pathologic changes in mouse colon based on the DAI scores and organ indices of liver, kidneys, and spleen of mice among different groups. Data are presented as mean ± SEM. The experimental groups include NC (normal control mice), DSS (UC model mice), SASP (UC mice treated with 200 mg/kg SASP as a positive control), LPCP (UC mice treated with 40 mg/kg PCPs), MPCP (UC mice treated with 80 mg/kg PCPs), and HPCP (UC mice treated with 120 mg/kg PCPs). ^# p < 0.05, ^## p < 0.01, and ^### p < 0.001 vs. NC, ^* p < 0.05, ^** p < 0.01, and ^*** p < 0.001 vs. DSS, ^& p < 0.05, ^& p < 0.01, and ^& p < 0.001 vs. SASP. UC: ulcerative colitis, DSS: dextran sodium sulfate, PCP: Polygonatum cyrtonema polysaccharide, DAI: disease activity index, SASP: sulfasalazine, LPCP: low-dose PCP, MPCP: medium-dose PCP, HPCP: high-dose PCP.

FIGURE 2

PCPs alleviate colon tissue damage in DSS-induced UC mice (n = 4/5). (A, B): H&E and Masson’s trichrome staining micrographs of the paraffin sections of colon tissues from mice at 100×, ×200, and ×400 magnifications show inflammatory cell infiltration (➔) and collagen deposition (▲) after DSS treatment. (C): Collagen volume fractions in colon tissues of mice from each group determined using Masson’s trichrome staining. (D–F): Protein levels of TGF-β1 and α-SMA in colon tissues of mice from each group, with GAPDH as the loading control. Data are presented as mean ± SEM. ^# p < 0.05, ^## p < 0.01, and ^### p < 0.001 vs. NC, ^* p < 0.05, ^** p < 0.01, and ^*** p < 0.001 vs. DSS, ^& p < 0.05 vs. SASP. UC: ulcerative colitis, DSS: dextran sodium sulfate, PCP: Polygonatum cyrtonema polysaccharide.

FIGURE 3

PCPs ameliorate inflammation, oxidative stress, and intestinal mucosal injury in UC mice (n = 4/5). (A–D): mRNA expression of IL-6, IL-1β, TNF-α, and IL-10 in colon tissues of mice from each group with GAPDH as the housekeeping gene. (E–H): Serum levels of IL-10, MDA, SOD, and GSH in mice from each group. (I–L): Protein levels of ZO-1, occludin, and claudin in colon tissues of mice from each group, with GAPDH as the loading control. Data are presented as mean ± SEM. ^# p < 0.05, ^## p < 0.01, and ^### p < 0.001 vs. NC, ^* p < 0.05, ^** p < 0.01, and ^*** p < 0.001 vs. DSS, ^& p < 0.05, ^& p < 0.01, and ^& p < 0.001 vs. SASP. UC: ulcerative colitis, DSS: dextran sodium sulfate, PCP: Polygonatum cyrtonema polysaccharide.

FIGURE 4

Unfractionated PCPs show superior therapeutic effects than fractionated fractions PCP-1 and PCP-2 in alleviating pathogenic phenotypic characteristics of DSS-induced UC mice (n = 4). (A, B): Quantitative analysis of changes in colon lengths of mice in different groups. (C): Quantitative analysis of body weight of mice in different groups. (D): Evaluation of pathologic changes in mouse colon using the DAI scores. (E–G): Organ indices of liver, kidney, and spleen of mice from different groups. Data are presented as mean ± SEM. ^# p < 0.05, ^## p < 0.01, and ^### p < 0.001 vs. NC, ^* p < 0.05 and ^** p < 0.01 vs. DSS. UC: ulcerative colitis, DSS: dextran sodium sulfate, PCP: Polygonatum cyrtonema polysaccharide.

FIGURE 5

Unfractionated PCPs show superior therapeutic effects in alleviating colon tissue lesions, inflammatory imbalance, and mucosal injury in DSS-induced UC mice (n = 4). (A, B): Microscopic images of H&E and Masson’s trichrome staining of colon tissue sections at 100×, ×200, and ×400 magnifications show inflammatory cell infiltration (➔) and collagen deposition (▲). (C): Quantification of collagen volume fraction in colon tissues using Masson’s trichrome staining. (D–G): Quantification of mRNA expression of IL-6, IL-1β, TNF-α, and IL-10 in colon tissues of mice from each group (GAPDH is the housekeeping gene). (H–M): Protein levels of α-SMA, TGF-β1, ZO-1, occludin, and claudin in colon tissues of mice from different groups, with GAPDH as the loading control. Data are presented as mean ± SEM. ^# p < 0.05, ^## p < 0.01, and ^### p < 0.001 vs. NC, ^* p < 0.05, ^** p < 0.01, and ^*** p < 0.001 vs. DSS. UC: ulcerative colitis, DSS: dextran sodium sulfate, PCP: Polygonatum cyrtonema polysaccharide.

FIGURE 6

ABX treatment diminishes the therapeutic effects of PCPs on pathogenic phenotypic features of UC mice (n = 5). (A, B): Quantitative analysis of colon lengths of mice in each group. (C): Quantitative analysis of changes in body weights of mice in each group. (D): Assessment of pathologic changes in mouse colon using the DAI scores of each group. (E–G): Organ indices of liver, kidney, and spleen from mice in each group. Data are presented as mean ± SEM. ^# p < 0.05 and ^## p < 0.01 vs. DSS + PCP. UC: ulcerative colitis, DSS: dextran sodium sulfate, PCP: Polygonatum cyrtonema polysaccharide, ABX: antibiotics.

FIGURE 7

ABX treatment reduces the therapeutic effects of PCPs on colon tissue lesions, inflammatory imbalance, and mucosal injury in UC mice (n = 4/5). (A, B): H&E staining and Masson’s trichrome staining images of colon tissue sections at 100×, ×200, and ×400 magnifications show inflammatory cell infiltration (➔) and collagen deposition (▲). (C): Quantification of collagen volume fraction in mouse colon tissues using Masson’s trichrome staining. (D–G): IL-6, IL-1β, TNF-α, and IL-10 mRNA expression in colon tissues of mice, with GAPDH as the housekeeping gene. (H–M): Protein levels of α-SMA, TGF-β1, ZO-1, occludin, and claudin in colon tissues of mice, with GAPDH as the loading control. Data are presented as mean ± SEM. DSS + PCP: DSS-exposed mice treated with PCPs, ABX + DSS, mice treated with ABX and DSS, ABX + DSS + PCP: mice treated with ABX, DSS, and PCPs. ^# p < 0.05, ^## p < 0.01, and ^### p < 0.001 vs. DSS + PCP, ^** p < 0.05 vs. ABX + DSS. UC: ulcerative colitis, DSS: dextran sodium sulfate, PCP: Polygonatum cyrtonema polysaccharide, ABX: antibiotics.

FIGURE 8

ABX treatment reverses the effect of PCPs on fecal microbiota of DSS-induced UC mice (n = 4/5). (A) Bar plot illustrates the relative abundance of the top 10 taxa at the phylum level. (B–G): Differential relative abundance at the phylum level. (H): Bar plot illustrates the relative abundance of the top 10 taxa at the genus level. (I–O): Differential relative abundance at the genus level. DSS + PCP: DSS-exposed mice treated with PCPs, ABX + DSS: mice treated with ABX and DSS, ABX + DSS + PCP: mice treated with ABX, DSS, and PCPs. ^# p < 0.05, ^## p < 0.01, and ^### p < 0.001 vs. DSS + PCP group. UC: ulcerative colitis, DSS: dextran sodium sulfate, PCP: Polygonatum cyrtonema polysaccharide, ABX: antibiotics.

FIGURE 9

PCP treatment alleviates pathogenic phenotypic features in DSS-induced UC mice (n = 5/6). (A,B): Quantitative analysis of colon lengths of mice in each group. (C): Quantitative analysis of changes in body weights of mice in each group. (D): Assessment of pathologic changes in mouse colon using the DAI scores of each group. (E–G): Organ indices of the liver, kidney, and spleen from mice in each group. Data are presented as mean ± SEM. The experimental groups comprise NC (normal control mice), DSS (UC model mice), FMT + NC (NC mice receiving FMT), and FMT + PCP (PCP-treated UC mice receiving FMT). ^## p < 0.01 and ^### p < 0.001 vs. NC, ^* p < 0.05 and ^** p < 0.01 vs. DSS. UC: ulcerative colitis, DSS: dextran sodium sulfate, PCP: Polygonatum cyrtonema polysaccharide, FMT: fecal microbiota transplantation.

FIGURE 10

PCP treatment alleviates colon tissue damage, inflammatory imbalance, and mucosal injury in DSS-Induced UC mice (n = 4/5). (A,B): H&E and Masson’s trichrome staining images of colon tissue sections at 100×, ×200, and ×400 magnifications show inflammatory cell infiltration (➔) and collagen deposition (▲). (C): Quantification of collagen volume fraction in colon tissues using Masson’s trichrome staining. (D–G): IL-6, IL-1β, TNF-α, and IL-10 mRNA expression in colon tissues of mice, with GAPDH as the housekeeping gene. (H–J): Protein levels of α-SMA and TGF-β1 in colon tissues of mice, with GAPDH as the loading control. (K–N): Protein levels of ZO-1, occludin, and claudin in mouse colon tissues, with GAPDH as the loading control. Data are presented as mean ± SEM. The experimental groups comprise NC (normal control mice), DSS (UC model mice), FMT + NC (NC mice receiving FMT), and FMT + PCP (PCP-treated UC mice receiving FMT). ^# p < 0.05, ^## p < 0.01, and ^### p < 0.001 vs. NC, ^* p < 0.05, ^** p < 0.01, and ^*** p < 0.001 vs. DSS. UC: ulcerative colitis, DSS: dextran sodium sulfate, PCP: Polygonatum cyrtonema polysaccharide, FMT: fecal microbiota transplantation.

FIGURE 11

PCP-treated mice regulate the fecal microbiota composition in DSS-induced UC mice (n = 4). (A) Bar plot depicts the composition of the top 10 species at the phylum level by relative abundance. (B–F): Differential relative abundance at the phylum level. (G) Bar plot depicts the composition of the top 10 taxa at the genus level by relative abundance. (H–J): Differential relative abundance at the genus level. The experimental groups consist of NC (normal control mice), DSS (UC model mice), FMT + NC (NC mice receiving FMT), and FMT + PCP (PCP-treated UC mice receiving FMT). ^# p < 0.05, ^## p < 0.01, and ^### p < 0.001 vs. NC, ^* p < 0.05 and ^** p < 0.01 vs. DSS. UC: ulcerative colitis, DSS: dextran sodium sulfate, PCP: Polygonatum cyrtonema polysaccharide, FMT: fecal microbiota transplantation.