Serum MMP-9 and TIMP-1 concentrations and MMP-9 activity during surgery-induced inflammation in humans

Background: Matrix metalloproteinase 9 (MMP-9) and the endogenous inhibitor to MMP-9, tissue inhibitor of metalloproteinase 1 (TIMP-1), have important roles in tissue remodelling and are implicated in a number of diseases related to inflammation. The time course in activation and formation of MMPs and TIMPs during an inflammatory reaction is not fully known. This study investigates MMP-9 and TIMP-1 concentrations and MMP-9 activity at different time points after major surgery when a state of noticeable inflammation is expected. Methods: Serum MMP-9 and TIMP-1 concentrations and MMP-9 activity were analysed preoperatively and 4 and 30 days postoperatively in patients undergoing elective surgery ( coronary artery bypass n=21; orthopaedic surgery, n=29). Results: Serum TIMP-1 and MMP-9 activity increased significantly 4 days after surgery (p<0.05 and p<0.01, respectively) and decreased again 30 days after surgery (p<0.01, respectively, compared to 4 days after surgery). Serum MMP-9 increased significantly 4 days after surgery (p<0.05) and was still high 30 days after surgery (p<0.01 compared to before surgery). The calculated MMP-9/TIMP-1 ratio was increased 30 days after surgery compared to before surgery (p<0.01). Conclusions: The inflammatory state induced by elective surgery is associated with increased TIMP-1 response and MMP-9 activity in serum within a few days which may be of importance for the postoperative heeling process. The further increase in MMP-9 concentrations at day 30 postoperative did not result in increased MMP-9 activity. Serum MMP-9 concentrations or the calculated MMP-9/TIMP-1 ratio do not entirely represent MMP-9 activity during surgery-induced inflammation.