Poria cocos polysaccharide alleviates cyclophosphamide-induced intestinal barrier dysfunction and inflammation in mice by modulating gut flora

doi:10.12122/j.issn.1673-4254.2026.01.04

Abstract

Abstract:

Objective To investigate the protective effects of Poria cocos polysaccharide (PCP) against cyclophosphamide (CTX)-induced intestinal mucosal injury and its impact on gut flora and their metabolites in mice. Methods Adult BALB/C mice were randomized into normal control group, CTX model group, glutamine (positive control) group, and low-, medium- and high-dose PCP treatment groups. In all but the normal control group, the mice were subjected to modeling of CTX-induced intestinal mucosal injury by intraperitoneal CTX injections for 3 days, followed by treatment with gavage of normal saline, glutamine (300 mg/kg), or PCP at 75, 150, or 300 mg/kg for 7 consecutive days. The colonic expressions of tight junction proteins (occludin and ZO-1), serum endotoxin, D-lactate, and DAO levels, intestinal permeability, colon injury, and colonic cytokine levels (IL-4, IL-22, IL-17A, and IFN-γ mRNA) were assessed. Gut microbiota, short-chain fatty acids (SCFAs; mainly acetates and propionates) and colonic GPR41 expression were analyzed using 16S rRNA sequencing, GC-MS, and Western blotting, respectively. Fecal microbiota transplantation (FMT) experiment was conducted to validate the role of gut microbes in PCP-mediated repair of intestinal injuries. Results Compared with those in the model group, the mice treated with PCP showed significantly increased colonic occludin and ZO-1 expressions, reduced serum endotoxin, D-lactate and DAO levels, and lowered intestinal permeability with increased colonic expressions of IL-4, IL-22, IL-17A, and IFN-γ mRNA. PCP treatment obviously increased the abundance of Muribaculaceae, decreased Lactobacillus and Bacteroides, increased the contents of acetate and propionate in the colon, and upregulated colonic GPR41 expression. The results of FMT experiment confirmed the crucial role of gut microbes in PCP-mediated repair of CTX-induced intestinal injuries in mice. Conclusion PCP can protect against CTX-induced intestinal mucosal injury in mice possibly by modulating gut flora and SCFAs metabolism to enhance intestinal defense capacity.

Key words: Poria cocos polysaccharide, intestinal mucosal injury, gut flora, short-chain fatty acids, GPR41

Yue ZHANG, Yuting DUAN, Chen ZHANG, Luzhe YU, Yingying LIU, Lihua XING, Lei WANG, Nianjun YU, Daiyin PENG, Weidong CHEN, Yanyan WANG. Poria cocos polysaccharide alleviates cyclophosphamide-induced intestinal barrier dysfunction and inflammation in mice by modulating gut flora[J]. Journal of Southern Medical University, 2026, 46(1): 34-46.

Figures/Tables 9

Fig.1 Effect of PCP on physiological state of the colon in CTX-treated mice. A: Illustration of the experiment design. i.p.:Intraperitoneal injection,i.g.: Irrigation. B: Spleen index (spleen weight/body weight). C: Thymus index (thymus weight/body weight) of the mice. D: Colon length of the mice. E: Colon index (colon weight/body weight). F: HE staining of the colon tissue (Original magnification: ×7.5). NC: Control group; MC: CTX model group; PC: CTX+Glutamine (positive drug) group; LD: CTX+PCP low dose group; MD: CTX+PCP medium dose group; HD: CTX+PCP high dose group. Data are presented as Mean±SD (n=6). *P<0.05, ***P<0.001 vs NC group; #P<0.05, ##P<0.01, ###P<0.001 vs MC group.

Fig.2 Effect of PCP on intestinal barrier function in CTX-treated mice. A-D: Immunofluorescence staining of occludin and ZO-1 (green: occludin and ZO-1; blue: nucleus; ×7.5). E: PAS staining showing mucus-secreting epithelial cells (×7.5). F: MUC2 contents in colonic tissues. G: Endotoxin levels in serum. H: DAO levels in serum. I: D-Lactate levels in serum. Data are presented as Mean±SD (n=6). *P<0.05, **P<0.01, ***P<0.001 vs NC group; #P<0.05, ##P<0.01, ###P<0.001 vs MC group.

Fig.3 Effect of PCP on immune cytokines in the colonic mucosa of the mice. A-H: Relative mRNA expression levels of IL-4, IL-5, IL-13, IL-17A, IL-17F, IL-22, IFN-γ, and TGF-β detected with RT-qPCR, using β-actin as the reference control. Data are represented as Mean±SD (n=6). *P<0.05, **P<0.01, ***P<0.001 vs NC group; ##P<0.01, ###P<0.001 vs MC group.

Tab.1 Diversity indexes of gut microbiota in NC, MC, and HD groups (Mean±SD, n=6)

Group	Chao1	ACE	Shannon	Simpson	Goods_coverage
NC	195.22±50.78	195.79±51.02	5.81±0.21	0.97±0.00	1.00
MC	182.98±17.05	183.05±16.94	5.51±0.23	0.96±0.01	1.00
HD	275.21±52.61	274.09±51.86	6.32±0.44	0.98±0.01	1.00

Fig.4 Effect of PCP on gut microbiota composition in CTX-treated mice. A: Species abundance distribution curve. B: Principal coordinates analysis. C: Venn graph showing species overlap. D: Phylum-level microbial composition. E: Genus-level microbial composition. F: Firmicutes abundance. G: Bacteroidetes abundance. H: Firmicutes-to-Bacteroidetes ratio. I: Muribaculaceae abundance. J: Lactobacillus abundance. K: Bacteroides abundance. L: LDA score. M: Phylogenetic distribution of discriminant taxa. Data are represented as Mean±SD (n=6). *P<0.05, **P<0.01, ***P<0.001 vs NC group; #P<0.05, ##P<0.01, ###P<0.001 vs MC group.

Fig.5 Effect of PCP on SCFAs content in CTX-treated mice. A: Standard curve of each component of SCFAs to be measured. B: GC chromatogram of mixed control solution of SCFAs (1: acetic acid; 2: propionic acid; 3: butyric acid; 4: isobutyric acid; 5: valeric acid; 6: isovaleric acid; 7: 2-ethylbutyric acid). C: Acetate levels. D: Propionate levels. E: Butyrate levels. F: Valerate levels. G: Correlation analysis between gut microbiota and short-chain fatty acids. H: Representative bands of GPR41. I: Protein expression of GPR41. Data are presented as Mean±SD (n=6). *P<0.05, **P<0.01, ***P<0.001 vs NC group; #P<0.05, ##P<0.01, ###P<0.001 vs MC group.

Fig.6 Effect of FMT on colon injury in CTX-treated mice. A: Illustration of the design of fecal microbiota transplantation (FMT) experiment. B: Splenic somatic index (organ-to-body weight ratio). C: Thymus index (thymus weight/body weight). D: Colon length. E: Colon index (colon weight/body weight). F: HE staining (×100). FMTNC: FMT normal group; FMTCTX: FMT CTX model group; FMTPCP: FMT-Poria cocos polysaccharide. G: FMT modulates immune function in CTX-treated mice (Relative mRNA expression levels of cytokines: IL-4, IL-5, IL-13, IL-17A, IL-17F, IL-22, IFN-γ, and TGF-β). Data are presented as Mean±SD (n=6). *P<0.05, **P<0.01, ***P<0.001 vs FMTNC group; #P<0.05, ##P<0.01, ###P<0.001 vs FMTMC group.

Fig.7 Effect of FMT on intestinal permeability of the mice. A-D: Immunofluorescence staining of occludin and ZO-1. (green: Occludin and ZO-1; blue: nucleus; ×100). E: PAS staining showing mucus-secreting epithelial cells (×100). F: MUC2 content in colonic tissue. G: Endotoxin levels in serum. H: DAO levels in serum. I: D-Lactate levels in serum. Data are presented as Mean±SD (n=6). *P<0.05, ***P<0.001 vs FMTNC group; #P<0.05, ##P<0.01, ###P<0.001 vs FMTMC group.

Fig. 8 Effect of FMT on SCFAs content and GPR41 in the colon of the mice. A: Acetate. B: Propionate. C: Butyrate. D: Valerate concentrations. E: Representative bands of GPR41. F: Quantitative analysis of GPR41 protein expression normalized to β-actin. Data are presented as Mean±SD (n=6). **P<0.01, ***P<0.001 vs FMTNC group; #P<0.05, ###P<0.001 vs FMTMC group.

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