Role and dynamics of matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 in burn patients

Burn injuries can trigger tissue changes that can explain the variation in the level of different biochemical markers that can be recorded both locally or systemically. Some events observed in burn wounds such as vascular hyperpermeability have been associated with the release of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) after trauma. Because it is unknown whether the serum levels of MMP-9 and TIMP-1 are a consequence of these destructions or a local response to thermal damage, we decided to follow their dynamics. Twenty-five patients (mean age 49.40 +/- 17.55 years) with a total body surface area (TBSA) affected by a thermal burn of <25% and 30 healthy subjects (mean age 49.70 +/- 8.04 years) were enrolled in the present study. Enzyme immunoassays were used to measure the serum levels of MMP-9 and TIMP-1. Our results showed that MMP-9 was increased 6.25-fold immediately after injury compared to the controls and remained on a plateau throughout the 7-day monitoring period. TIMP-1 showed an upward trend with an increase of 49.52% on the seventh day after triggering insult. The time-course of the MMP-9/TIMP-1 ratio followed the inverse dynamics of TIMP-1 starting from a ratio value measured at admission 3.82-fold higher than the one observed in the healthy volunteers and a highly statistically significant correlation between the values measured at different time-points during the monitoring period (P<0.001). The results of this retrospective study indicate that the MMP-9/TIMP-1 ratio may provide information on local changes over time, starting from the triggering insult, and may be considered as a predictive biomarker of burn evolutivity.