Fig. 1. Dietary fibers and SCFAs dampen CSR, plasma cell differentiation and class-switched antibody responses.

After weaning, C57BL/6 mice were fed a fiber diet (regular chow) or no-fiber diet. Two weeks later, these mice were started on SCFAs water (SCFAs) or plain water (Nil). All mice were then administered OVA together with CT via intragastric gavage once a week for 4 weeks starting at 8 weeks of age, and killed a week after the last OVA and CT administration. a Total and OVA-binding IgM, IgG1, IgA, and IgE concentrations in serum of fiber or no-fiber-fed mice on SCFAs water or plain water, as measured by ELISA. Each symbol represents an individual mouse (n = 5 per group, pooled from two experiments). The bars represent the mean ± SD. b OVA-binding IgM, IgG1, IgA, and IgE concentrations in the feces of fiber-fed mice on SCFAs water or plain water, as measured by ELISA. Each symbol represents an individual mouse (n = 5 per group, pooled from two experiments). c IgM, IgA, and IgD-positive cells in the lamina propria, PPs, and MLNs of fiber or no-fiber-fed mice on SCFAs water or plain water as visualized by fluorescence microscopy. d ELISPOT analysis of IgM, IgG1, and IgA AFCs in MLNs, PPs, spleen, and bone marrow of fiber-fed mice on SCFAs water or plain water. e Proportion of surface CD19⁺IgG1⁺ and CD19⁺IgA⁺ B cells, germinal center B cells (CD19⁺GL-7⁺), and plasmablasts/plasma cells (CD138⁺) in MLNs, PPs, and the spleen of fiber-fed mice given SCFAs water or plain water, as analyzed by flow cytometry. Data in c–e are representative of three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001, ns: not significant (unpaired t test). Scale bar = 100 μm. The source data are provided in Source Data file.