Dysregulated signal transducer and activator of transcription 3 drives intestinal permeability and may contribute to acute-on-chronic liver failure

Figure 1 Intestinal tissue of mouse models shows increased signal transducer and activator of transcription 3 expression and altered epithelial integrity during progression from liver steatosis to acute-on-chronic liver failure. A-C: Paraffin embedded intestinal tissue of mouse models generating steatosis, cirrhosis, and acute-on-chronic liver failure (ACLF) was used for: Hematoxylin and eosin (HE) staining (A); Immunohistochemical analysis of signal transducer and activator of transcription 3 (STAT3) and phospho-STAT3 (pSTAT3) and compared to tissue of healthy controls, respectively (B and C); D and E: STAT3 and pSTAT3 protein levels of immunohistochemical staining were quantified using Fiji (ImageJ) by color deconvolution, followed by signal quantification and graphical representation in GraphPad Prism; F: Disease stage-dependent changes of STAT3 messenger RNA levels from cirrhosis to ACLF were determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and compared. HE staining demonstrated a progressive disruption of intestinal epithelial architecture during disease progression. Immunohistochemistry revealed a significant upregulation of STAT3 expression in intestinal tissue from ACLF mice compared with healthy controls, which was confirmed by RT-qPCR. Statistical analysis of immunohistochemical staining was performed using one-way analysis of variance followed by Tukey’s multiple comparisons test. Differences in STAT3 messenger RNA expression were assessed by unpaired Student’s t-test. P values are two-sided (n = 3-6). ^aP < 0.05. ^bP < 0.01. ^cP < 0.001. ACLF: Acute-on-chronic liver failure; STAT3: Signal transducer and activator of transcription 3; pSTAT3: Phospho-signal transducer and activator of transcription 3; mRNA: Messenger RNA; NS: Not significant.