Fig. 1

The number of immunoglobulin A (IgA)-producing cells is reduced within the intestinal immune system of high fat diet (HFD)-fed mice. Frequency and absolute number of IgA-producing B cells (IgA⁺ B220⁺) and plasma cells (IgA⁺ B220⁻) within the a, b distal small intestine LP (SB) (n = 7/group, 2 experiments), Peyer’s patches (PP) (n = 17–19/group, 5 experiments), c, d colon LP (n = 6/group, 2 experiments), and e, f colon draining mesenteric lymph nodes (MLNs) (n = 4–5/group) in HFD-fed C57BL/6J mice after 14 weeks compared to normal control diet (NCD)-fed controls. g Representative staining of IgA⁺ cells within the distal SB (left) and colon (right) in HFD- and NCD-fed mice after 14 weeks of diet (scale bar = 100 µm). h Enumeration of IgA+ cells per ×400 high power field (HPF) in the distal SB (left) and colon (right) in NCD and HFD-fed mice (n = 4/group, at least 10 HPF counted per mouse). i Concentration of secretory IgA (SIgA) within ileal contents (left) (n = 11/group) and colonic stool (middle) (n = 6/group), and IgA antibody titers in the serum (right) (n = 15/group) of NCD and HFD wild-type (WT) mice. Data are means ± SEM. * denotes p < 0.05, ** denotes p < 0.01, and *** denotes p < 0.001