PURPOSE: Infectious pleural effusions (IPEs) are common clinical problems that require an adequate approach to avoid the risk of pleural thickness and pleural decortication. The imbalance between serum and pleural fluid pro- and anti-inflammatory cytokines may be important in guiding the strategies of treatment and thus influence the outcome of the IPEs.
METHODS: Samples of serum and pleural fluid were assayed to determine the levels of pro- (IL-1β, VEGF, IL-8) and anti-inflammatory (IL-1ra, IL-10) cytokines in 28 patients with pleural effusions (10 tuberculous - TB, 11 paraneumonic –PPE and 9 empyemas –Emp). The results were correlated with the pleural thickness (Thick) evaluated after complete clinical resolution. Statistics: Anova (mean ± SD; p< 0.05) and Pearson correlation.
RESULTS: In serum, only the pro-inflammatory cytokine VEGF was higher in empyema than in TB. In addition, levels of the anti-inflammatory IL-1ra were marked increased in empyema in comparison to TB and PPE. In the pleural fluid, the levels of IL-1β;, IL-1ra, VEGF and IL-8 were higher in empyema, whereas PPE had higher IL-10 levels than empyema and higher levels of IL-1β;, IL-1ra and IL-8 than TB. Pleural thickness was more pronounced in empyema in comparison to TB and PPE. Serum IL-10 strongly correlated with pleural thickness in empyema (R= 0.9; p< 0.001). A negative correlation of pleural thickness with pleural fluid IL-1β; and IL-10 in TB (R= -0.9; p< 0.05) and IL-1ra in PPE (R= -0.7; p< 0.05) was also observed (Table).
CONCLUSION: Empyema had higher levels of serum VEGF and pleural fluid IL-1, IL-1ra, VEGF and IL-8. The pleural fluid levels of the anti-inflammatory cytokine IL-10, but not IL-1ra, was higher in PPE and TB in comparison to Empyema.
CLINICAL IMPLICATIONS: The pleural fluid anti-inflammatory cytokine IL-10, but not IL-1ra, may have a role in modulating the pleural inflammatory response in PPE and TB, avoiding the complication of pleural thickness after treatment.
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