Effect of irisin on alveolar macrophage polarization in a rat model of ventilator-induced lung injury / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effect of irisin on the alveolar macrophage polarization in a rat model of ventilator-induced lung injury (VILI).Methods:Thirty SPF healthy adult male Sprague-Dawley rats, aged 6-8 weeks, weighing 200-250 g, were divided into 3 groups ( n=10 each) using a random number table method: control group (group C), VILI group (group V) and irisin group (group I). The rats were mechanically ventilation (tidal volume 20 ml/kg, respiratory rate 80 times/min, inhaled oxygen concentration 21%, inspiratory/expiratory ratio 1∶2, positive end-expiratory pressure 0) for 4 h to develop VILI model.Group C kept spontaneous breathing for 4 h. Irisin 1 μg/kg was injected via the tail vein at 30 min before tracheal intubation in group I, while the equal volume of normal saline was given instead in the other groups.The rats were sacrificed at 4 h of mechanical ventilation, the lung tissues were removed for examination of pathological changes which were scored and for determination of wet to dry weight ratio (W/D ratio), and bronchoalveolar lavage fluid (BALF) was collected for determination of concentrations of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α) and IL-10 (by enzyme-linked immunosorbent assay), expression of inducible nitric oxide synthase (iNOS), argininase 1 (Arg-1), and phosphorylated nuclear factor kappa B (p-NF-κB) p65 and p-NF-κB p50 in alveolar macrophages (by Western blot), and percentage of M1 and M2 alveolar macrophages and M1/M2 ratio (by flow cytometry). Results:Compared with group C, the W/D ratio, lung injury score, and concentrations of IL-6, TNF-α and IL-10 in BALF were significantly increased, the expression of iNOS, Arg-1, p-NF-κB p65 and p-NF-κB p50 was up-regulated, and the percentage of M1 and M2 alveolar macrophages and M1/M2 ratio were increased in group V and group I ( P<0.05). Compared with group V, the W/D ratio, lung injury score, and concentrations of IL-6 and TNF-α in BALF were significantly decreased, the expression of iNOS and p-NF-κB p65 was down-regulated, the percentage of M1 alveolar macrophages and M1/M2 ratio were decreased ( P<0.05), and no significant change was found in levels of IL-10 and Arg-1 in BALF, percentage of M2 alveolar macrophages and expression of p-NF-κB p50 in group I ( P>0.05). Conclusions:The mechanism by which irisin reduces VILI may be related to inhibition of NF-κB signaling pathway activation and reduction of alveolar macrophage polarization to M1 phenotype in rats.