Thymosin β4 released by mast cells under stress conditions impairs intestinal epithelial barrier via IL22RA1/JAK1/STAT3 signaling in irritable bowel syndrome

Figure 1 Enhanced thymosin β4 in irritable bowel syndrome is accompanied by intestinal epithelial barrier injury. A: Immunofluorescence staining of zonulin 1 (ZO-1) in colons from healthy controls and irritable bowel syndrome (IBS) patients. Magnification: 400 ×, Scale bar, 50 μm. Results are representative of ZO-1 in control and IBS samples; B: Representative double immunofluorescence images of thymosin β4 (Tβ4) and Tryptase in healthy controls and IBS patients (left) and the quantification of the number of mast cells (MCs) or Tβ4 (right). Magnification: 400 ×, Scale bar, 50 μm. Bar, SD, ^aP < 0.001, ^bP < 0.01 vs the Healthy group; C: The levels of Tβ4 were quantified by ELISA in the colonic mucus. n = 38/group. ^aP < 0.001 vs the Healthy subjects group; D: Rats were exposed to psychological stress for 10 days to induce IBS. Representative intestinal immunofluorescence images of Tβ4 (green) and Tryptase (red) (left), and quantification of the number of MCs or Tβ4 (right). Scale bar, 50 μm. Bar, SD, ^cP < 0.01 vs the Control group; E-G: The level of (E) diamine oxidase, (F) D-lactate and (G) bacterial endotoxin in serum. Bar, SD, ^cP < 0.01 vs the Control group; H: Representative immunofluorescence images of ZO-1 (green) and DAPI (blue). Scale bar, 50 μm; I: Immunohistochemical images of myosin light chain kinase in colon. Scale bar, 100 μm. Bar, SD, ^cP < 0.01 vs the Control group; J: Representative FISH staining for bacterial infiltration using EUB338 probe (red) and DAPI (blue). Scale bar, 50 μm. ^dP < 0.001 vs Control group. ZO-1: Zonulin 1; Tβ4: Thymosin β4; IBS: Irritable bowel syndrome; MC: Mast cell; MLCK: Myosin light chain kinase.