Remote ischemic conditioning modulates the healing process after intestinal anastomosis

Purpose: To evaluate whether remote ischemic conditioning (RIC) improves intestinal anastomotic healing through modulation of different healing phases. Methods: Juvenile mice underwent distal ileal end-to-end anastomosis and were assigned to three groups: sham (laparotomy only), anastomosis only, and anastomosis + RIC. RIC involved four cycles of 5-minute hindlimb ischemia and 5-minute reperfusion, applied immediately postoperatively and repeated on postoperative days (POD) 2 and 4. On POD 2 and POD5, tissues were analyzed for TNF-α and IL-6 expression. On POD 5, bursting pressure, adhesion scores, and anastomotic complication scores were assessed. On POD2 and POD5, bulk RNA sequencing was conducted on intestinal anastomosis segments comparing anastomosis vs. sham and anastomosis vs. anastomosis + RIC. Results: Increased pro-inflammatory cytokine activity was observed on POD2 in the anastomotic site and the proximal area of the anastomosis, but not on POD5, indicating an initial phase of inflammation post anastomosis. No inflammation was found post-anastomosis in the distal area. Compared to anastomosis alone, RIC significantly reduced pro-inflammatory cytokine TNF-α and IL-6 gene and protein expression on in the anastomotic site and proximal area of anastomosis on POD 2 (qPCR), indicating decreased inflammation. Furthermore, functional analysis showed that on POD 5, the anastomosis + RIC group had significantly higher bursting pressure and lower adhesion scores compared to the anastomosis only group (p < 0.05). Bulk sequencing analysis showed an upregulation of inflammatory and apoptotic pathways in the anastomosis-only group, while RIC treated anastomosis group had upregulated wound healing pathways in the anastomotic site. These results suggested that RIC dampens early inflammation after intestinal anastomosis and improves the healing process in the anastomotic site. Conclusion: RIC exerts phase-specific effects on anastomotic healing by attenuating early inflammation and enhancing mechanical strength. RIC may offer a simple and non-invasive strategy to improve surgical outcomes.