Fig. 3: Oral RC402 reshapes the gut microbiome by increasing IgA⁺ antibody-secreting cells (ASCs) in the terminal ileum via MAdCAM-1.

Mice were subcutaneously implanted with CT26 tumor cells, orally administered with RC402 (RC), and gut microbiomes were analyzed using shotgun metagenomic sequencing (B–H). A The gut microbiome was depleted with a cocktail of antibiotics. Then, mice were implanted with CT26 tumor cells and treated with PBS, IT, or oral RC402. Comparison of tumor growth (n = 5 for IT PBS without antibiotics; n = 6 for IT RC402 without antibiotics; n = 6 for oral PBS or oral RC402 without antibiotics; n = 8 for other groups). B Principal coordinate analysis (PCoA) showing distinct clustering of gut microbiome in baseline and PBS- or RC402-treated mice (n = 3 for baseline; n = 4 for other groups). C Comparisons of gut microbiome diversity in terms of Shannon index. D PCoA plot showing Bray-Curtis dissimilarity. E Relative abundance of gut microbiota at the genus level (n = 4 per group). F Heatmap showing the relative abundance of gut microbiota at the genus level. Values are z-scores (n = 4 per group). G Abundance of specific genus in PBS- or RC402-treated mice. H Volcano plot showing differentially expressed microbial metabolic pathways and abundance of specific metabolic pathways between PBS- or RC402-treated mice (one-tailed Student’s t test). I–N CT26 tumor-bearing mice were treated with oral PBS or RC402 in the presence and absence of αMAdCAM-1 neutralization antibody. I Comparison of CT26 tumor growth. (n = 6 for RC402; n = 7 for other groups). J, K Representative images and comparisons of IgA⁺ ASCs within lamina propria of terminal ileum. L Comparisons of fecal IgA levels. Expression was normalized to total fecal protein. M, N Abundance of specific genus in PBS-, RC402-, and/or αMAdCAM-1-treated mice. Data are pooled from two independent experiments. Values are expressed as the mean ± SD. Unless otherwise denoted, two-tailed Student’s t test and ANOVA with Tukey post-hoc test were used. Scale bars, 100 μm. Source data are provided as a Source Data file.