Micromorphological features and interleukin 6, 8, and 18 expressions in post-mortem lung tissue in cases with acute respiratory distress syndrome.

The purpose of this study was to analyze the presence of interleukins 6, 8, and 18 in post-mortem lung tissue of subjects deceased due to polytrauma. In addition to this, we have described different micromorphological features of lung tissue in ARDS cases associated with fatal traffic trauma. A total of 18 autopsy cases with ARDS after polytrauma and 15 control autopsy cases were analyzed in this study. From every subject, we collected one sample for each lung lobe. All of the histological sections were analyzed by using light microscopy, and for the purpose of ultrastructural analysis, we used transmission electron microscopy. Representative sections were further processed by way of immunohistochemistry analysis. Quantification of IL-6, IL-8, and IL-18-positive cells was conducted by applying the IHC score. We noticed that all samples of ARDS cases exhibited elements of the proliferative phase. Immunohistochemical analysis of lung tissue in patients with ARDS showed strong positive staining for IL-6 (2.8 ± 0.7), IL-8 (2.2 ± 1.3), and IL-18 (2.7 ± 1.2), while staining of the control samples resulted in no positivity to low/moderate positivity (for IL-6 1.4 ± 0.5; for IL-8 0.1 ± 0.4; for IL-18 0.6 ± 0.9). Only IL-6 correlated negatively with the patients' age (r =  -0.6805, p < 0.01). In this study, we described microstructural changes in lung sections of ARDS cases and control cases, as well as interleukins' expression, demonstrating that autopsy material is as informing as tissue samples collected by performing open lung biopsy.