Role of HSF1 in endogenous protective mechanism underlying mechanical ventilator-induced lung injury in mice: relationship with HMGB1 / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of heat shock transcription factor 1 (HSF1) in the endogenous protective mechanism underlying mechanical ventilator-induced lung injury (VILI) in mice and the relationship with high mobility group box 1 (HMGB1).Methods:Forty SPF healthy male C57BL/6 mice, aged 6-8 weeks, weighing 20-25 g, were divided into 4 groups ( n=10 each) by the random number table method: control group (group C), VILI group (group VILI), negative control siRNA + VILI group (group NV) and HSF1 siRNA + VILI group (group siRNA). At 48 h before mechanical ventilation, negative control siRNA 5 nmol and HSF1 siRNA 5 nmol were intratracheally injected in NV and siRNA groups respectively, and the solution was diluted to 50 μl with the sterile phosphate buffer in both groups. Group C kept spontaneous breathing for 4 h, and the rest animals were mechanically ventilated (tidal volume 35 ml/kg, respiratory rate 75 breaths/min, inspiratory/expiratory ratio 1∶2, fraction of inspired oxygen 21%) for 4 h. Blood samples from the femoral artery were collected for arterial blood gas analysis immediately after endotracheal intubation and at 4 h of ventilation, and PaO 2 was recorded. Then the mice were sacrificed under deep anesthesia to collect lung tissues and bronchoalveolar lavage fluid (BALF). The concentrations of interleukin-1beta (IL-1β), tumor necrosis factor-alpha (TNF-α) and HMGB1 in BALF were determined by enzyme-linked immunosorbent assay. The pathological results were observed by hematoxylin-eosin staining, and lung injury was assessed and scored. The wet/dry (W/D) weight ratio of lung tissues was calculated. The expression of HMGB1 and HSF1 mRNA in lung tissues (by quantitative real-time polymerase chain reaction) and expression of HMGB1 and HSF1 protein in lung tissues (by Western blot) were determined. Results:Compared with group C, PaO 2 was significantly decreased at 4 h of ventilation, the concentrations of TNF-α, IL-1β and HMGB1 in BALF, W/D ratio and lung injury score were increased, and the expression of HMGB1 protein and mRNA in lung tissues was up-regulated in group VILI, group NV and group siRNA ( P<0.05 or 0.01). Compared with group VILI and group NV, PaO 2 was significantly decreased at 4 h of ventilation, the concentrations of TNF-α, IL-1β and HMGB1 in BALF, W/D ratio and lung injury score were increased, and the expression of HMGB1 protein and mRNA in lung tissues was up-regulated, and the expression of HSF1 protein and mRNA was down-regulated in group siRNA ( P<0.05 or 0.01). There was no significant difference in the parameters mentioned above between group VILI and group NV ( P>0.05). Conclusions:HSF1 is involved in the endogenous protective mechanism underlying VILI in mice, which may be related to the down-regulation of HMGB1 expression and attenuation of inflammatory responses in lung tissues.