Fig 2: Protein expression of the ion permissive tight-junction proteins claudin-2 and -12 and the vitamin D receptor (VDR). Panel A shows the effect of vitamin D3 (Vit D3) alone or in combination with 10 mM glycocholic acid (GCA), butyrate (10 mM), and the Hsp90ß-inhibitor Geldanamycin on claudin-2 protein expression. Panel B shows the effect on claudin-12 protein expression. Panel C shows the effect on VDR. Values in panels A to C are min to max and each treatment was performed in three wells and the experiments were conducted three times. *(p < 0.05); **(p < 0.01) denotes significant differences between control group and treated groups. #(p < 0.05); ##(p < 0.01) denotes significant differences between Vit D3, or the combination Vit D3, GCA, and butyrate with or without Geldanamycin (Mann-Whitney).

Fig 3: Confocal analysis of T cell transmigration route.Successive optical Z-sections through the filter + epithelial cell system are represented in an apical to basal order. (A) The most apical confocal plane is at the level of the tight junction protein claudin 2. The T cell, barely visible in this section, emerges on the following plane at a tricellular corner (white arrowhead). The leading edge is then visualized in section 3, followed by the cell body in more basal focal planes. A second, presumably transmigrating T cell similarly appears at another tricellular corner (Section 4, white arrow). (B) The T cell visible in the first confocal plane (white arrowhead) has migrated through the epithelial monolayer. It is located apically relative to the sections displaying the tight junction protein claudin 2 (visible from section 3), and associated with a tricellular corner (Section 5), through which it may have migrated. A second T cell (Section 7, white arrow) is visible in the second half of the plane series. It is mostly present in sections that are basal to the tight junction network.

Fig 4: Comparison of tight junction protein mRNA expression levels in the control and functional dyspepsia (FD) groups in all groups irrespective of Helicobacter pylori status. (A-C) Claudin-2 (CLDN2), CLDN4, and occludin (OCLN) mRNA expression were higher in male FD group than those of control group (P = 0.017, 0.054, and 0.044, respectively). (D-F) There were no significant differences in CLDN2, CLDN4, and OCLN mRNA expression level between female FD group and female control group. Data are expressed as median (interquartile range).

Fig 5: Lyve1-Cre;Wlsf/f mice are refractory to CCl4-induced hepatotoxicity.(A) (Left) Schematic of CCl4 administration and tissue harvesting using Cldn2-EGFP mice. (Right) Double-immunofluorescence results show that claudin-2/GFP+ hepatocytes (arrows) are in close proximity to the sinusoidal endothelium (Lyve1+, arrows) throughout the recovery period that follows CCl4 acute injury. (B) GS (Zone 3), Cyp2e1 (Zone 2/3) and E-cadherin (Zone 1) expression in control and Lyve1-Cre;Wlsf/f livers without CCl4 treatment. (C–E) Top: Schematics of tissue harvesting post-CCl4 administration. (C) (Left) ALT/AST serum levels indicate liver damage in Lyve1-Cre (control) mice and no liver damage in Lyve1-Cre;Wlsf/f mice, 2 days post-CCl4. p values were determined by one-way ANOVA with Bonferroni’s multiple comparisons test. NS, not significant (p>0.05), **p<0.01, ***p<0.001 (n = 3). (C–E) (top panels): Immunostaining results show that in Lyve1-Cre livers injected with CCl4, Zone 3 is nearly undetected (GS, arrows) and Zone 2 (Cyp2e1, arrows) is severely destroyed at day 2 (C); a few enucleated cells express GS (arrow) around the central vein, Zone 1 (‘E-cad’, arrowheads) is expanded, and Zone 2 (‘Cyp2e1’, arrow) is separated from the central vein by macrophage infiltrates (‘F4/80’, arrows; arrowheads are Kupffer cells) at day 4; and Zones 1–3 (‘E-cad’/‘Cyp2e1’/‘GS‘, arrows) look nearly restored and macrophage infiltrates are scarce (arrows) at day 7. (C–E) (bottom panels): GS+ cells and macrophage infiltrates are undetected and both, Cyp2e1 and E-cadherin expression are unchanged, in Lyve1-Cre;Wlsf/f livers 2–7 days post-CCl4. Each image represents 3–4 individual livers. Asterisks: central veins. Scale bars: 100 µm. Related data can be found in Figure 7—figure supplements 1 and 2.Figure 7—source data 1.Quantification of ALT/AST serum levels in in Lyve1-Cre;Wlsf/f mice post-CCl4 injection.