Intestinal IL-33–ST2 signaling regulates axis neutrophil recruitment during acute skin injury via peripheral 5-HT. (A-B) Aseptic skin wounds were punched into the dorsal skin on Tph1fl/fl and Vil1creTph1fl/fl mice with or without IL-33 treatment. (A) Wounded skin samples were collected 4 hours after injury and processed by hematoxylin and eosin (HE) staining. Inset: magnified skin tissue at the injury site. Scale bar, 100 μm. (B) Tissue neutrophil enzyme MPO was assessed from the wound sites. (C-J) Aseptic skin wounds were punched into the dorsal skin on Il33fl/fl and Vil1creIl33fl/fl mice (C-F) or Il1rl1fl/fl and ChgacreERIl1rl1fl/fl mice (G-J). (C,G) Wounded skin samples were collected 4 hours after injury and processed by HE staining. Inset: magnified skin tissue at the injury site. Scale bar, 100 μm. (D,H) Tissue neutrophil enzyme MPO was assessed from the wound sites. (E,I) The Wound sites were photographed at the indicated time. Day-0 picture was taken immediately after the injury. Scale bar, 2.5 mm. (F,J) Graph showing wound closure rate. Data are representative of 2 independent experiments (A, C, E, G, I) or are pooled from 2 independent experiments (B, D, F, H, J). *P < .05, **P < .01 by Student t test. Error bars represent standard deviation. NS, not statistically significant.