The Study On The Function Of Microparticles From Stored Blood Products In Transfusion-Related Acute Lung Injury

Objective:This study are to investigate the prming effects of platelet-derived microparticles (PMPs) and red cell-derived microparticles (RMPs) on neutrophil (PMNs) respiratory burst. We used a "two-hit" TRALI model to investigate the effects of PMPs on human pulmonary microvascular endothelial cells (HMVECs) damage and the effects of the two microparticles on inducing mouse acute lung injury.Methods:The priming activity of PMPs isolated from stored A-PLTs、RMPs isolated from stored packed RBC and recombinant sCD40L for fMLP-activated PMNs respiratory burst was determined by measuring the production of reactive oxygen species (ROS) with flow cytometry analysis. The expression of intercellular cell adhesion molecule-1 (ICAM-1; CD54) on HMVECs and the surface expression of CDllb on PMNs were also detected by flow cytometry.We used a "two-hit" in vitro model of HMVECs damage to investigate the effects of PMPs and recombinant sCD40L and role of apocynin, an inhibitor of PMNs respiratory burst. We also used a "two-hit"model to determine the effects of two microparticles on inducing mouse acute lung injury by detecting extravascular lung water、leakage of protein in bronchoalveolar lavage fluid and the changes of pulmonary pathology.Results:The expression of CD11b on PMNs exposed to PMPs increased in a dose-dependent manner. PMPs carried sCD40L, which interacted with CD40 on PMNs and induced a respiratory burst, thus mediating HMVECs cytotoxicity. We used the NADPH oxidase inhibitor apocynin to treat PMNs before culturing the cells with LPS-activated endothelial cells. This treatment result in inhibition of PMNs respiratory burst and HMVECs damage. The surface expression of CD54 increased on endothelial cells after treating HMVECs with LPS. Blocking CD54 on HMVECs with a monoclonal antibody to CD54 result in a decrease of PMNs-mediated HMVECs damage induced by PMPs. In vivo mice experiment results showed that PMPs induced actue lung injury in LPS-pretreated mices in a dose-dependent manner. We also found this lung injury can be inhibited partially by removing PMPs from plasma.Stored packed RBC contain increased numbers of RMPs. RMPs primed fMLP-activated PMN respiratory burst and caused acute lung injury in LPS-pretreated mices in a dose-dependent manner. Our results showed that removing RMPs from packed RBC supernatant could inhibit the PMNs respiratory burst significantly, but inhibite mice actue lung injury partially.Conclusion:In conclusion, PMPs carry concentrated CD40L signal, promote PMNs-mediated HMVECs damage, and induce actue lung injury in LPS-pretreated mices. Stored packed RBC units contain increased numbers of RMPs. RMPs primed PMNs respiratory burst and caused acute lung injury in LPS-pretreated mices, and may be related to TRALI.