Clinical Significance of Monitoring Serum Level of Matrix Metalloproteinase 9 in Patients With Acute Kidney Allograft Rejection

• A total of 8 acute rejections (ARs) and 94 non-ARs were enrolled.
• The matrix metalloproteinase 9 level was significantly increased during acute renal allograft rejection.
• The receiver operating characteristic curve on day 20 post-transplantation could differentiate between the non-AR and AR groups.

This study was designed to explore the clinical significance of dynamically monitoring the serum level of matrix metalloproteinase 9 (MMP-9) before and after renal transplantation. Before transplantation and 1, 3, 5, 7, 10, 15, and 20 days after transplantation, the peripheral blood was collected from 102 renal transplant recipients, including 8 with acute rejection (ARs) and 94 non-ARs. The serum MMP-9 level was detected by Luminex 200 analyzer (Luminex Corporation, Austin, TX, USA). By day 3 post-transplantation, the serum MMP-9 level in non-ARs had significantly reduced as compared to the pretransplantation level, and reached the lowest value on day 20 post-transplantation. In contrast, the serum MMP-9 level in ARs had significantly increased by day 3, reached the highest value on day 7, and remained significantly higher on day 20 as compared to the pretransplantation level. The receiver operating characteristic curve was plotted to evaluate the power of serum MMP-9 level on day 20 post-transplantation to differentiate the non-AR and AR groups. Our data revealed that with a threshold of 8473.26 pg/mL, the area under the curve was 0.758 (0.661, 0.856); the sensitivity and specificity of the diagnostic were 78.40% and 61.30%, respectively; the positive and the negative predictive values were 74.60% and 66.67%, respectively; and the accuracy rate was up to 71.57%. Taken together, the results indicated that dynamically monitoring serum MMP-9 levels in renal allograft recipients might be a convenient and safe method to diagnose ARs.