Mucosal changes induced by ischemia-reperfusion injury in a jejunal loop transplanted in oropharynx

Tissues exposed to ischemia and reperfusion develop an inflammatory response. We investigate the morphological and immunological changes occurring in the mucosa of a jejunal loop transplanted in the oropharynx of a man undergoing circular pharyngolaryngectomy. Jejunal biopsies were collected during the transplantation procedures (cold and warm ischemia, reperfusion), during the 7 post-operative days through an exteriorized jejunal segment for flap monitoring, and 45 days after transplantation through an upper endoscopy. Matrix metalloproteinase (MMP)-3 and MMP-12 increase was accompanied by a parallel rise in apoptotic enterocytes, and by a concomitant reduction of surface area to volume ratio and enterocyte height. Goblet cell hyperplasia is coupled with Paneth cell disappearance at the crypt base. CD8-positive intraepithelial lymphocytes initially decrease, then they increase in accordance with the peak of enterocyte apoptosis. We identified alterations in lymphocyte infiltration, mucosal architecture and epithelial cell turnover, which may give a window to mechanisms of small bowel ischemia-reperfusion in humans.