J. Fujimoto1, N. Uyama1, H. Tsutsui1, W. Songtao1, M. Sudo1, E. Hatano1, J. Fujimoto1 1Hyogo College of Medicine,Surgery,Nishinomiya, HYOGO, Japan
Introduction: After abdominal surgeries more than 90% of patients reported to have adhesion formation. It often results in significant morbidity, and treatment of these morbidity costs approximately $1.3 billion per year. We have developed an experimental mouse model of abdominal adhesion, and revealed that IFN-g and PAI-1 played a pivotal role in adhesion formation by regulating the coagulation fibrinolysis system (Nat Med 2018). Recently, we have performed RNA profiling and pathway analysis in this mouse model and found that IL-6 is the key molecule for adhesion formation. In response to IL-6, IFN-g, PAI-1, TGF-b were up-regulated which stimulated the peritoneal mesothelial cells to produce collagen fibers. Thus, we administrated anti-IL-6 receptor monoclonal antibody (IL-6R Ab) to the mouse to examine its preventive effect on the adhesion formation.
Methods: We induced intestinal adhesion using BALB/c mouse by cecal cauterization as previously reported. Adhesions strongly connected the cecum to the large bowel, the abdominal wall or both at day 7. We used (1) IL-6 receptor antibody: IL-6R Ab (MR16-1) or (2) IL-6 ligand antibody: anti-IL-6 monoclonal antibody (MP5) to the adhesion mouse models. PBS or rat IgG was injected to the adhesion mouse models as control groups. These antibodies or PBS/rat IgG was injected intraperitoneally 24 hours before the cauterization. Adhesion score (0: no adhesion to 5: very thick vascularized adhesion) was examined at day 7, and immuno- histopathological study and molecular analysis were performed between day 0 and day 7. Moreover, mice treated with PBS or MR16-1 were injured by skin biopsy to examine wound healing. The repair rate of the wound was monitored every day until day 7.
Results:A single injection of MR16-1 significantly reduced intestinal adhesion (N=11, score: 1.9±0.49) compared to PBS group (N=10, score: 4.9±0.1, p=0.003) and rat IgG group (N=4, score: 5.0, p=0.00002). A single injection of MP5 did not reduce the adhesion score (N=4, score: 5.0). MR16-1 treated mice had significantly lower expression of IFN-g, IL-6, CXCL2, collagen 1a1, and TGF-b1 mRNA in their ceca. Histopathological analysis revealed that MR16-1 treated mice had significantly reduced fibrotic change and the neutrophil infiltration. The skin wound of the first biopsy day were 19.68 mm2 and 19.2 mm2 in rat IgG treated and MR16-1 treated mice, respectively. They were reduced to 1.6mm2 and 1.07mm2 at day 7, respectively. Thus, wound healing progressed normally in MR16-1 treated mice.
Conclusion:We revealed that IL-6R Ab strongly prevents intestinal adhesion after surgery in mice. Human IL-6R Ab, Tocilizmab/ Actemra R is available,
IL-6R Ab treatment presented here may eventually be translated into a useful clinical regimen for the preventing adhesion formation in patients undergoing surgery.