Objective: To study the expression of intercellular cell adhesion molecule-1 (ICAM-1), Interleukin-10 (IL-10) and the activation of transcription factor activator protein-1 (AP-1) in a rabbit model of ventilator-induced lung injury (VILI) and therefore to explore their possible role in VILI.
Methods: The VILI model was established by mechanical ventilation with a large tide volum (V(T)) of 40 ml/kg. Forty healthy male New Zealand rabbits were randomly divided into 5 groups: a control group without mechanical ventilation, a conventional ventilation group, and injurious ventilation with large V(T) for 1 h group, 2 h group and 4 h group. The concentrations of soluble ICAM-1 (sICAM-1) and IL-10 in lung homogenates were measured by enzyme-linked immunosorbent assay (ELISA). The level of mRNA was measured by semiquantitative transcription-polymerase chain reaction (RT-PCR). The DNA-binding activity of AP-1 was measured by electrophoretic mobility shift assay (EMSA). The partial arterial blood pressure of oxygen (PaO2), myeloperoxidase (MPO) in lung homogenate, wet lung weight to dry lung weight ratio (W/D) were observed.
Results: (1) The concentrations of sICAM-1 in large V(T) for 2 h group (23 ± 5) ng/L and 4 h group (35 ± 5) ng/L were higher than that in the conventional ventilation group (16 ± 4) ng/L (P all < 0.05), and that in the Large V(T) for 4 h group were higher than that in 1 h group (19 ± 4) ng/L and 2 h group (P all < 0.01). The concentrations of IL-10 in the large V(T) for 2 h group (24 ± 4) ng/L and 4 h group (26 ± 5) ng/L were higher than that in the conventional ventilation group (15 ± 2) ng/L (P all < 0.05), and that in the Large V(T) for 4 h group was higher than that in the 1h group (19 ± 4) ng/L(P < 0.05). The level of ICAM-1 mRNA in the large V(T) for 2 h group (1.18 ± 0.19) and 4 h group (1.29 ± 0.19) were higher than that in the conventional ventilation group (0.84 ± 0.13) (P all < 0.05), and that in Large V(T) for 4 h group was higher than that in 1 h group (0.96 ± 0.24) (P < 0.05). The level of IL-10 mRNA in the large V(T) for 4 h group (1.13 ± 0.17) was higher than that in the conventional ventilation group (0.84 ± 0.20) and Large V(T) for 1 h group (0.86 ± 0.12) (P all < 0.05). (2) The DNA-binding activity of AP-1 in the large V(T) for 2 h group (33.77 ± 8.23) and 4 h group (38 ± 9) were higher than that in the conventional ventilation group (23 ± 9) (P all < 0.01), and that in Large V(T) for 4 h group was higher than that in 1h group (25 ± 9) (P < 0.01). (3) Histopathological findings demonstrated that diffused alveolar damage induced by mechanical ventilation was worse with time, and after mechanical ventilation with large V(T) for 2 h, the level of MPO began to increase, and for 4 h the PaO2 reduced and the W/D increased.
Conclusions: ICAM-1 and IL-10 took part in the inflammatory responses of VILI, and their up-regulation maybe due to the increase of their mRNA. Nuclear transcription factor AP-1 maybe involved in the transcriptional regulation mechanisms of these inflammatory mediators.