Relationship between shedding of syndecan-4 in lung tissues and ventilator-induced lung injury in rats

Abstract

Objective To evaluate the relationship between the shedding of syndecan-4 (SDC-4) in lung tissues and ventilator-induced lung injury in rats. Methods Thirty pathogen-free healthy adult male Wistar rats, weighing 220-250 g, were divided into 3 groups (n=10 each) using a random number table: control group (group C), mechanical ventilation with traditional tidal volume (VT) group (group T-VT) and mechanical ventilation with high VT group (group H-VT). The animals were anesthetized with pentobarbital sodium and tracheostomized.The rats kept spontaneous breathing in group C. The rats were mechanically ventilated for 4 h with the VT set at 6 ml/kg in group T-VT and with the VT set at 40 ml/kg in group H-VT.Blood samples were collected immediately after the end of ventilation for measurement of serum SDC-4 concentrations by enzyme-linked immunosorbent assay.The left lung was lavaged, and broncho-alveolar lavage fluid was collected for determination of interleukin-1beta (IL-1β), IL-18, tumor necrosis factor-alpha and SDC-4 concentrations by enzyme-linked immunosorbent assay.The lungs were removed for determination of the wet to dry weight ratio and expression of SDC-4 protein and mRNA in lung tissues (by Western blot and real-time polymerase chain reaction, respectively) and for examination of the pathological changes.The lung injury scores were recorded. Results Compared with group C, the wet to dry weight ratio, lung injury scores, concentrations of IL-1β, IL-18, tumor necrosis factor-alpha and SDC-4 in broncho-alveolar lavage fluid and concentrations of SDC-4 in serum were significantly increased, the expression of SDC-4 mRNA was up-regulated, and the expression of SDC-4 was down-regulated in group H-VT (P 0.05). Marked pathological changes of lung tissues were found in group H-VT. Conclusion A large shedding of SDC-4 in lung tissues may be involved in the pathophysiological mechanism of ventilatior-induced lung injury in rats. Key words: Syndecan-4; Respiration, artificial; Respiratory distress syndrome, adult