Abstract
Background. Pathological changes occurring during acute inflammatory lung injury (AILI) include damage to the alveolar epithelium, capillary endothelium, pulmonary macrophages, and fibroblasts. Fibrinogen and fibrin play a fundamental role in the inflammatory and immune response, the excessive deposition of which underlies hypercoagulability and, over time, the development of fibrosis. Aim: to determine the dynamics of the content of fibrinogen and fibrin degradation products (FDP) in the lung tissue in AILI using the example of experimental exudative-hemorrhagic pneumonia with fibrosis. Materials and methods. AILI was modeled in male Wistar rats weighing 190-220 g (n=47) by introducing a foreign body and a lipopolysaccharide solution into the trachea. Animals were removed from the experiment on days 1, 3, 5, 7, 14 and 21 of observation. The content of fibrinogen and FDP in tissue lysates was determined by immunoblotting. Statistical analysis was performed using Statistica 10 software (StatSoft, Inc., USA). Results. In the dynamics of the AILI development in the lung tissue, an accumulation of fibrinogen was observed, which was statistically significant on the 1st, 3rd and 14th days. Later, at the stages of proliferation and fibrosis, the fibrinogen content was restored. The lung content of FDP statistically significantly increased compared to the control with a maximum on the 5th day. Spearman's correlation analysis showed the presence of a direct relationship of medium strength between the content of fibrinogen and FDP (r=0.568; p<0.05), which confirmed the direct relationship between the accumulation of fibrinogen in the lung tissue and the activation of fibrinolysis. Such dynamics corresponded to the course of AILI – in the acute exudative-hemorrhagic phase (1-3 days) there was a rapid accumulation of fibrinogen. This was accompanied by the accumulation of FDP, which reflected the activation of fibrinolysis and had a maximum on the 5th day. From the 7th day, the development of the proliferative stage and fibrosis was accompanied by the restoration of both indicators. Conclusion. Thus, the study confirmed the important role of fibrinogen and FDP accumulation in the lungs and established its correspondence to the stages of acute lung injury development