Interleukin (IL)-10 Is an Effective Therapeutic for Murine Transfusion Related Acute Lung Injury (TRALI)

Transfusion related acute lung injury (TRALI) is the leading cause of transfusion-induced fatalities and is characterized by acute respiratory distress following blood transfusion. Donor antibodies present in the transfused blood product such as anti-human leukocyte antigen (HLA) or anti-human neutrophil antigen (HNA) antibodies are frequently involved. Currently, there is no treatment available for TRALI apart from supportive measures such as oxygen. The pathogenesis the disorder is incompletely understood, however, several animal models have contributed to our understanding of TRALI disease pathology. Most TRALI reactions are considered to be due to a two-hit paradigm where the first hit is a predisposing patient factor such as inflammation while the second hit is the transfusion. It is widely believed that the second hit delivers antibodies that trigger TRALI in the recipient. The anti-MHC class I antibody, 34-1-2s, has been widely used as an agent that delivers the second TRALI hit in mice. We have previously shown that CD4+ T cells, more specifically, CD4+CD25+FoxP3+ T-regulatory cells (Tregs) convey protection against TRALI (Blood. 126 (23):2342, 2015; abstract #82075, manuscript submitted). In the current study, we utilized a C57BL/6 mouse model of severe TRALI by first depleting mice of CD4+ T cells and then injecting them with the anti-MHC class I monoclonal antibodies (34-1-2s+AF6-88.5.5.3) and we examined the effects of the anti-inflammatory cytokine IL-10 on the antibody-mediated TRALI reaction.

IL-10 (45 µg/kg iv) or volume-matched PBS was injected 15 minutes after the administration of anti-MHC antibodies when the onset of TRALI symptoms (e.g. a 2 degree drop in rectal temperature indicative of systemic shock) began. Results show that 90 minutes after anti-MHC class I antibody injection, control mice injected with PBS exhibited a high degree of pulmonary edema as assessed by significantly elevated lung wet-to-dry weight ratios (W/D: 5.84 ± 1.02). Pulmonary neutrophil levels were also found to be increased and lung tissue histology confirmed severe signs of acute lung injury. In contrast, mice injected with IL-10 completely recovered from TRALI; after 90 minutes post-antibody injection they displayed no signs of pulmonary edema (W/D: 4.76 ± 0.04, ** p<0.004 compared to mice injected with PBS) and no signs of severe acute lung injury as assessed by lung tissue histology. Pulmonary neutrophil levels, however, were equally increased in both groups indicating that although IL-10 rescues the mice from acute lung injury, it does not interfere with pulmonary neutrophil recruitment. Preliminary data suggests that IL-10 administration interferes with the ability of neutrophils to generate reactive oxygen species (ROS) that mediate lung injury. Our results suggest that IL-10 therapy significantly rescues an ongoing severe TRALI reaction and this may prove to be an effective and feasible therapeutic strategy in combating human TRALI.