Immunology and Inflammation

Beta-Glucan Modulates Monocyte Plasticity and Differentiation Capacity to Mitigate DSS-Induced Colitis

Yinyin Lv
Yanyun Fan
Qingxiang Gao
Qiongyun Chen
Yiqun Hu
Lin Wang
Huaxiu Shi
Ermei Chen
Qinyu Xu
Ying Cai
Qingqi Fan
Linying Li
Dan Du
Jianlin Ren author has email address
Shih-Chin Cheng author has email address
Hongzhi Xu author has email address

Department of Gastroenterology, The National Key Clinical Specialty, Zhongshan Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
Clinical Research Center for Gut Microbiota and Digestive Diseases of Fujian Province, Xiamen Key Laboratory of Intestinal Microbiome and Human Health, Xiamen, China
Department of Digestive Disease, Institute for Microbial Ecology, School of Medicine, Xiamen University, Xiamen, China
State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, China
Department of Gastroenterology, Taikang Xianlin Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
State Key Laboratory of Cellular Stress Biology, Department of Gastroenterology, Zhongshan Hospital of Xiamen University, School of Medicine, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, China

https://doi.org/10.7554/eLife.107339.1

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Figures and data

β-glucan (BG) pretreatment ameliorates DSS-induced colitis.
(A) Schematic representation of BG-induced trained immunity and DSS colitis model, (B) Body weight change curve of mice pretreated with BG for one week, followed by colitis induction with 3% DSS (n = 10), (C) Colon length changes in mice from (B), (D) Endoscopic images displaying mucosal damage, (E and F) H&E staining and histological scoring. Scale bars: 100 µm, (G and H) Expression levels of tight junction and repair, (I) FITC-dextran assay assessing intestinal barrier function, (J) Body weight change curve of mice pretreated with BG for four weeks, followed by colitis induction with 3% DSS (n = 8-9), (K) Colon length changes in mice from (J). Data are presented as mean ± SD. Statistical significance: *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. ns, not significant.

BG ameliorates colitis by enhancing myeloid cell activation.
RNA sequencing of colon tissue at different time points of colitis. (A) GOBP and (B) KEGG pathway analyses of genes in the MEturquoise module. Single-cell RNA sequencing analysis of CD45⁺ cells in the colon on day seven of colitis after one week of BG pretreatment. (C) UMAP plot of LP CD45⁺ cells, (D) Cell ratio distribution from scRNA-seq data, (E) Dot plots showing representative DEGs between LP CD45⁺ cells, (F) AUC scores for selected pathways, (G) KEGG pathway analysis of genes upregulated in the monocyte-macrophage lineage. DEGs, differentially expressed genes. LP, lamina propria. UMAP, uniform manifold approximation, and projection. AUC, area under the curve.

BG trained bone marrow monocytes protected against colitis via the Ccl2-Ccr2 axis.
Ccr2^-/- mice pretreated with BG for 1 week followed by induction of colitis with 3% DSS. (A) Changes in body weight (n = 15), (B) Colon length changes in Ccr2^-/- mice from (A), (C and D) H&E staining and histological scoring, H&E. Scale bars: 100 µm, (E) FITC-dextran assay assessing intestinal barrier function, (F) Schematic representation of bone marrow transplantation from BG-pretreated CD45.1 mice to CD45.2 mice and colitis model, (G) Body weight change curve of colitis mice (n = 10), (H) Colon length changes in colitis mice from (G), (I and J)Percentage of CD11b⁺ (I) and Ly6C^hi monocytes (J) were analyzed by flow cytometry in peripheral blood, (K and L) Body weight change curve(K) and colon length changes of Ccr2^-/- mice receiving Ly6C^hi monocyte adoptive transfer(L) (n = 11). Data are presented as mean ±SD. Statistical significance: *p <0.05, **p <0.01, ****p <0.0001. ns, not significant.

BG-trained monocytes enhance innate immune activation and microbial control.
(A) UMAP and graphical visualization of the monocyte/macrophage lineage, (B) The ratio of monocyte/macrophage subsets, (C) KEGG pathway enrichment analysis of genes upregulated in monocyte 1 and monocyte 3, (D) Gene expression analysis at different time points of colitis, based on colon RNA sequencing, (E) AUC scores of selected pathways, (F) UMAP plots showing differential gene expression patterns, (G) Schematic representation Salmonella resistance after one week of BG pretreatment, (H) Survival curve of mice infected with Salmonella after one week of BG training. Statistical significance: ***p < 0.001.

BG-mediated reprogramming of myeloid differentiation trajectories balances inflammation and enhances mucosal repair in colitis.
(A) Monocle 3 trajectory analysis of monocyte/macrophage subsets, (B) Ridgeline plot of monocyte/macrophage subsets, (C) Violin plots of surface marker gene expression in monocyte/macrophage subsets, (D) Percentage of monocytes in peripheral blood at different time points of colitis progression, (E and F) Colonic LPMCs were collected, and the percentages of monocyte/macrophage were analyzed on day 7 of colitis, (G) Expression of mucosal repair-related genes at different time points of colitis, (H) Gene expression analysis of the monocyte/macrophage lineage. Data are presented as mean ± SD. Statistical significance: *p <0.05, ***p <0.001; ****p <0.0001. ns, not significant.

BG pretreatment ameliorates DSS-induced colitis.
(A) Schematic representation of BG-induced trained immunity and Staphylococcus aureus infection model, (B) Survival curve of mice infected with Staphylococcus aureus, (C and D) The gene expression of inflammatory mediators and antibacterial were analyzed by qRT-PCR, (E) Body weight change curve of mice pretreated with BG for one week, followed by colitis induction with 3% DSS (n = 18-25), (F and G) Changes of colon length from (E), (H) FITC-dextran assay assessing intestinal barrier function (n = 5-11). Data are presented as mean ± SD. Statistical significance: *p < 0.05, ***p < 0.001; ****p < 0.0001. ns, not significant.

BG pretreatment 4 or 7 weeks ameliorates DSS-induced colitis.
(A and B) Percentage of myeloid cells and monocytes in the peripheral blood of mice at different time points after one week of BG pretreatment, (C and D) H&E staining, and histological scoring of colitis mice after four weeks of BG training. Scale bars: 100 µm, (E) Body weight change curve of mice pretreated with BG for seven weeks, followed by colitis induction with 3% DSS, (F) Changes of colon length from (E) (n = 5). Data are presented as mean ± SD. Statistical significance: *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. ns, not significant.

BG pretreatment ameliorates colitis is independent of adaptive immunity.
(A) Schematic representation of BG-induced trained immunity and DSS colitis model in Rag1^-/- mice, (B-D) Flow cytometry analysis of peripheral blood from Rag1^-/- mice, (E) Body weight change curve of Rag1^-/- mice pretreated with BG for one week, followed by colitis induction with 3% DSS, (F) Colon length changes in Rag1^-/- mice from (E), (G and H) H&E staining and histological scoring. Scale bars: 100 µm. Data are presented as mean ±SD. Statistical significance: *p < 0.05, **p < 0.01, ****p < 0.0001.

BG ameliorates colitis by enhancing myeloid cell activation.
(A) RNA sequencing of colon tissue at different time points during colitis, with WGCNA identifying major gene modules, (B) DEGs in the Meturquoise module, (C and D) GO and KEGG pathway analysis of colon tissue on day seven of colitis after one week of BG pretreatment, (E) Expression of marker genes in LP CD45⁺ cells on day seven of colitis after one week of BG pretreatment.

BG trained bone marrow monocytes protected against colitis via the Ccl2-Ccr2 axis.
(A and B) Flow cytometry analysis of peripheral blood from Ccr2^-/-mice, (C) Flow cytometry analysis of bone marrow reconstitution in CD45.2 recipient mice, (D) Colon length changes in bone marrow transplantation experiments from BG-pretreated CD45.1 mice to CD45.2 mice, (E) Percentage of Ly6G⁺ neutrophils in peripheral blood of CD45.2 recipient mice, (F) Bone marrow monocytes transplant model, (G) Flow sorting scheme of bone marrow monocytes. Data are presented as mean ±SD. Statistical significance: ***p < 0.001.

BG pretreatment enhances innate immunity and phagocytic capacity.
(A) Major marker genes of eight cell clusters within the monocyte/macrophage lineage, (B) GO analysis of genes upregulated in monocytes 1 and monocyte 3, (C-E) AUC scores of selected pathways, (F) Antibacterial gene expression was analyzed by qRT-PCR. (G) AUC scores of selected pathways. Data are presented as mean ± SD. Statistical significance: *p < 0.05, ***p < 0.001, ns, not significant.

BG-induced trained immunity promotes monocyte differentiation.
(A) Gene expression analysis at different time points of colitis, based on colon RNA sequencing, (B) Violin plots of gene expression in eight cell clusters, (C) GSEA analysis showing gene enrichment pattern on day seven of colitis.

BG training downregulates the proportion of peripheral monocytes during colitis development.
(A) Peripheral blood flow cytometry gating strategy, (B) Representative flow cytometry plots of CD11b⁺ myeloid cells in peripheral blood on day seven of colitis (C) The percentage of CD11b⁺ myeloid cells at different time points of colitis, (D) Representative flow cytometry plots of Ly6G⁺ neutrophils in peripheral blood on day seven of colitis, (E) Percentage of Ly6G⁺ neutrophils at different time points of colitis, (F) Representative flow cytometry plots of Ly6C^hi monocytes in peripheral blood on day seven of colitis. Data are presented as mean ±SD. Statistical significance: **p < 0.01; ***p < 0.001; ****p < 0.0001.

BG training upregulates the proportion of colonic monocytes/macrophages in colitis mice.
(A) Colonic LPMCs flow cytometry gating strategy, (B and C) The percentages of CD11b⁺ myeloid cells (B) and Ly6G⁺ neutrophils (C) were analyzed on day seven of colitis (n = 6). Data are presented as mean ±SD. Statistical significance: *p < 0.05. ns, not significant.

Adoptive transfer of BG-trained monocytes ameliorates experimental colitis.
(A) Bone marrow monocytes transplant and colitis treatment model, (B and C) Body weight change curve (B) and colon length changes (C) in WT colitis mice receiving Ly6C^hi monocyte adoptive transfer (n = 10). Data are presented as mean ±SD. Statistical significance: *p < 0.05.

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