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

Figure 5 Thymosin β4 deficiency protects rats from stress-induced injury in the intestine. Thymosin β4 (Tβ4) (3 mg/kg) was injected into stress-induced Tβ4 deficiency (Tβ4^−/−) rats. A: Representative intestinal immunofluorescence images of zonulin 1. Scale bar, 50 μm; B: Representative TEM images of the colon. Magnification: 8000 ×, Scale bar, 2 μm. Magnification: 25000 ×, Scale bar, 500 nm; C: Immunohistochemistry staining of myosin light chain kinase. Scale bar, 100 μm; D: FITC-dextran 4000 (FD4, 4 kDa, 5 mg/kg) was orally administered, and the flux of FITC-dextran in rat serum was observed 3 hours later. ^aP < 0.05 vs the Tβ4^−/− group, ^bP < 0.001 vs the WT group; E and F: The colonic tissue mRNA levels of (E) IL22RA1 and (F) Reg3γ. Bar, SD, ^cP < 0.05 vs the Tβ4^−/− under stress group; G: Representative FISH staining for bacterial infiltration using EUB338 probe (red) and DAPI (blue). Scale bar, 50 μm. Bar, SD, ^cP < 0.05 vs the Tβ4^−/− under stress group; H: Representative intestinal immunofluorescence images of mast cell (Tryptase, red) and DAPI (blue), Scale bar, 50 μm. Bar, SD, ^cP < 0.05 vs the Tβ4^−/− under stress group. MLCK: Myosin light chain kinase; Tβ4: Thymosin β4; IL22RA1: Interleukin 22 receptor A1; WT: Wild-type.