Profile of Metalloproteinases and Their Association with Inflammatory Markers in Pleural Effusions.

Background: Matrix metalloproteinases (MMPs) are responsible for the breakdown of the extracellular matrix and play an important role in the inflammatory processes of pleural exudates. The imbalance between MMPs and their inhibitors (TIMPs) is present in various pathological processes.

Objective: To evaluate the profile of MMPs and TIMPs in pleural effusions of different etiologies correlated with inflammatory markers.

Methods: The patients with pleural effusion due to tuberculosis (TB), cancer (CA) or transudate were prospectively evaluated. Pleural fluid was submitted to cytological, biochemical, cytokines, MMP, and TIMP analysis. Statistical analysis was performed using ANOVA and Spearman's correlation, and p < 0.05 was considered significant.

Results: One hundred and fourteen patients were enrolled, 80 exudates (41 TB and 39 CA) and 34 transudates. The levels of MMP-8 and MMP-9 were higher in exudates compared to transudates. The level of MMP-8 was significantly higher in TB than in CA. TIMP-1 levels were higher in exudates. IL-6, VEGF, and TGF-β showed differences between exudates and transudates. However, IL-6 level was higher in TB than in CA. We found a significant correlation between MMPs and TIMPs with inflammation markers. MMP-1 was correlated with LDH levels. MMP-8 was correlated with LDH, total cell count, neutrophils, and ADA as well as MMP-1 levels. MMP-9 was correlated with IL-6, TGF-β, and VEGF. TIMP-1 was correlated with MMP-9 and IL-6.

Conclusions: MMPs and TIMPs are expressed in pleural fluid of different etiologies and correlate with inflammatory mediators. MMPs may be useful in determining the cause of fluid, but more studies are needed to determine the spectrum of diseases associated with the various isoforms of MMPS and TIMPs.