Role of PKC-δ in ventilator-induced lung injury in rats: relationship with NLRC4 / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of protein kinase C-delta (PKC-&delta;) in ventilator-induced lung injury (VILI) and the relationship with NLR family CARD domain-containing protein 4 (NLRC4) in rats.Methods:Thirty-six clean-grade healthy adult male Sprague-Dawley rats, weighing 200-250 g, were divided into 3 groups ( n=12 each) using a random number table method: control group (group C), VILI group (group V) and VILI plus KAI 9803 group (group VK). In V and VK groups, tracheal tubes were placed for mechanical ventilation after tracheotomy, ventilator settings were adjusted with a tidal volume of 40 ml/kg, respiratory rate of 60 breaths/min, and inspiratory/expiratory ratio of 1∶2, and air was inhaled.Group C received no mechanical ventilation after tracheal intubation.Immediately after completion of intubation, PKC-&delta; specific inhibitor KAI 9803 200 μg/kg was intratracheally injected in group VK, and the equal volume of phosphate buffer saline was given instead in the other two groups.Blood samples were taken from the femoral artery at 4 h of mechanical ventilation to record PaO 2.The chest was opened at the end of mechanical ventilation, lung tissues were removed, and the left lung tissues were lavaged to collect bronchoalveolar lavage fluid (BALF). The pathological changes of lung tissues were examined with a light microscope and scored.Enzyme-linked immunosorbent assay was used to detect the concentrations of interleukin-1beta (IL-1β) and IL-18 in BALF, Western blot was used to detect the expression of NLRC4, caspase-1 and PKC-&delta; in the right lower lobe of the lung, and the expression of NLRC4 mRNA in the right lower lobe of the lung was determined by real-time polymerase chain reaction, and the wet/dry weight ratio (W/D ratio) of the right middle lobe of the lung was calculated. Results:Compared with group C, the pathological score and W/D ratio were significantly increased, PaO 2 was decreased, the concentrations of IL-1β and IL-18 in BALF were increased, and the expression of NLRC4, caspase-1 and NLRC4 mRNA was up-regulated in V and VK groups, and the expression of PKC-&delta; was significantly up-regulated ( P<0.01), and a large amount of edema fluid was seen in the alveolar space, with inflammatory cell infiltration in group V ( P<0.01). Compared with group V, the pathological score and W/D ratio were significantly decreased, PaO 2 was increased, the concentrations of IL-1β and IL-18 in BALF were decreased, the expression of NLRC4, caspase-1, PKC-&delta; and NLRC4 mRNA was down-regulated ( P<0.05), and fluid exudation in the alveolar space and the degree of inflammatory cell infiltration were significantly attenuated in group VK. Conclusion:PKC-&delta; is involved in VILI, which is related to inhibiting NLRC4 expression in rats.