| Objective We observe the role of IL-2 and IL-2c prophylactic administration in expansion of Treg cells and alleviation of lung injury by establishing antibody mediated-transfusion-related acute lung injury(TRALI)model,so as to provide new ideas for the preventive strategies of TRALI.Methods This study utilized a mouse model of the“two-hit”mechanism.70BALB/c mice were selected and randomly divided into 7 groups:Na?ve group,LPS group,LPS+Isotype group,TRALI group(LPS+MHC-I mAb),Treg-depleted group(LPS+MHC-I mAb+anti-IL-2Rα),IL-2 group(LPS+MHC-I mAb+IL-2)and IL-2c group(LPS+MHC-I mAb+IL-2c).BALB/c mice were primed with LPS(0.1 mg/kg)as the first hit,and then TRALI was induced by injecting major histocompatibility complex(MHC)class-I antibodies after 24 hours.For the Treg-depleted group,mice were infused with anti-mouse IL-2Rαfirst and then subjected to the same treatments as the TRALI group.Regarding IL-2-and IL-2c-treated mice,recombinant murine IL-2 or IL-2c was intraperitoneally administered to mice for 5 consecutive days before induction of the TRALI model.Na?ve,LPS,and isotype groups were used as controls to exclude the effects of protein-and volume-related hydrostatic lung damage.Samples were collected two hours after TRALI induction.A section of the lung tissue was stained with hematoxylin-eosin(HE),and the wet to dry(W/D)weight ratio was detected.The supernatants of lung tissue homogenates were collected to detect the myeloperoxidase(MPO)activity and cytokines IL-2,IL-6,TNF,IFN-γ,IL-17A,IL-10 levels,respectively.The proportions of Treg and Th17cells in the spleen,blood and bronchoalveolar lavage fluid(BALF)were collected.Statistical analysis was performed using GraphPad Prism 5.0 software.Results Histopathological analysis of lung tissues with HE staining revealed lung injury in TRALI group,typified by the infiltration of neutrophils,destruction of the lung structures,hemorrhage and alveolar septal thickening,indicating a successful model of antibody mediated-TRALI mice.Compared to TRALI mice,the histopathological analysis in Treg-depleted mice showed that the lung tissues were seriously damaged,and the lung W/D ratio,MPO activity,total protein levels and pro-inflammatory factors were significantly increased(P<0.05).The mortality rate of Treg-depleted mice was 100%.Moreover,the proportion of Treg cells in the spleen,blood and BALF was significantly decreased,while the proportion of Th17cells was significantly increased(P<0.05).These results indicated that the lung tissue damage was aggravated after Treg depletion,and Treg cells may be related to the protective mechanism of TRALI.Mice were prophylactic administration with IL-2 or IL-2c,which significantly prevented pulmonary edema,reduced pulmonary protein levels and proinflammatory factors,and inhibited polymorphonuclear neutrophil(PMN)aggregation in the lungs.The proportion of Treg cells was significantly increased,while the proportion of Th17 cells was significantly decreased in spleen,blood and BALF.The mortality rate of mice in both groups were 20%and 0%,respectively.These results indicated that the percentage of CD4~+CD25~+FoxP3~+Treg cells was expanded in vivo using IL-2 and IL-2c compared to TRALI mice,as was confirmed through analysis of the spleen,blood and lung.Conclusion This study validates that the protective mechanisms against TRALI involve CD4~+CD25~+FoxP3~+Treg,which can be expanded in vivo by IL-2 and IL-2c.This results in increased IL-10 levels and decreased IL-17A,thereby prophylactically preventing antibody-mediated murine TRALI.It may provide new sights for the prevention and treatment of TRALI. |
