Receptor expression in IECs. (A–D) Confocal microscopy images of (A) the cecal patch, and (B) a mucosa-associated lymphoid follicle in fixed cecae of p65GFP-FL mice i.v. injected with LPS at 1 h.p.inj. Boxes in overview images indicate insets. Arrowheads indicate p65+ nuclei. Arrows indicate p65− nuclei. Scale bars: 50 µm (overview images) or 10 µm (insets). TLR4 staining in small intestine (C) and colon (D) of WT mice. Arrowheads indicate MHCII+ cells. Arrows indicate IECs. Scale bars: 20 µm. Representative images of mice from two experiments. (E) Heat map depicting expression levels of Tlr2, Tlr4, Tlr6, Tlr11, Tnfrsf1a (TNFR1), and Tnfrsf1b (TNFR2) in untreated or TNF-treated (5 ng/ml, 8 h) small intestinal epithelial organoids derived from SPF (SPF1, SPF2) or germ-free (GF) mice, m-ICc12 cells, and mouse embryonic fibroblasts (MEFs; reanalysis of a previously published transcriptome dataset, all detectable Tlrs depicted; Hausmann et al., 2020b). (F) Cecal mucosa stained for TNFR1 at 1 h.p.inj. of LPS. Scale bars: 50 µm. Representative images of mice from three independent experiments (n = 4–7).
