Trauma results in immune cell-induced intestinal epithelial damage with subsequently increased sepsis rate

BACKGROUND The detrimental effect of trauma on the immune system has been a subject of interest for decades. The gut-associated lymphoid tissue (GALT) of the bowel that encompasses different lymphocyte subpopulations may be an important pillar of human immunity in the context of trauma. Neither the short-term histological trauma-induced changes in the GALT nor its impact on the outcome after trauma surgery has been investigated. METHODS This prospective, longitudinal proof-of-concept study included patients who required damage-control surgery after abdominal gunshot wounds with small bowel involvement. Bowel specimens were obtained during the index and relook operations, and the T-lymphocytic quantity therein was analyzed via immunohistochemistry. We scrutinized how the lymphocyte structure and numbers of the GALT altered, and whether the extent and nature of these changes had an impact on the postoperative outcome with regard to septic and surgical complications. RESULTS A total of 31 damage-control patients were recruited for the study. The main histological changes between the index and relook specimen was a shift of CD8+ T cells from the lamina propria (LP) into the epithelium and a decrease of T lymphocytes in the LP. The significant increase of the intraepithelial CD8+ T cells was associated with a more extensive enterocyte apoptosis, and correlated significantly, positively with the number of postoperative septic complications. CONCLUSION Our data support that trauma induces an immune cell-driven impairment of the intestinal epithelium, as well as an increased apoptosis of lymphocytes in the LP, which is associated with a worse clinical outcome. The underlying mechanism suggests that a therapeutic approach to minimize apoptosis in the intestine may impact the outcome of severely injured trauma patients.