Poster Presentation Lorne Infection and Immunity 2019

Packed red blood cells modulate LPS-induced IL1β and caspase-1 production in monocytes (#110)

Fenny Chong 1 , Kelly Rooks 1 , Robert Flower 1 2 , Melinda Dean 1 2
  1. Australian Red Cross Blood Service, Stafford, QLD, Australia
  2. Faculty of Health, Queensland University of Technology, Brisbane, QLD, Australia

Introduction:

Packed red blood cell (PRBC) transfusion is lifesaving, however it has been associated with increased rate of poor patient outcomes. Mechanisms associated with poor patient outcomes are not fully characterised. During 42 day routine storage, PRBC undergo biochemical and morphological changes, and there is accumulation of immunomodulatory mediators. Interleukin (IL)-1β is a crucial mediator in inflammation. In the canonical inflammasome pathway, maturation of IL1β involves caspase-1 and the inflammasome. We investigated whether inflammasome activation is modulated by PRBC transfusion.

 

Methods:

PRBC supernatants (PRBC-SN) were prepared at different time points during routine storage (D2, D14, D28, D42). In a model of transfusion and concurrent infection, monocytes were incubated +/- lipopolysaccharide (LPS, 1 μg/mL), LPS+PRBC-SN or LPS+ATP (positive control) for 4 hours, 37°C, 5% CO2. IL-1β and caspase-1 were quantified in PRBC-SN and culture SN. Macrophage migration inhibitory factor (MIF) was assessed as a potential mediator of inflammasome activation. MIF was quantified in PRBC-SN and then recombinant MIF (rMIF) +/- LPS added to model 2-3 unit of transfusion. Results were analysed by repeated measures one way ANOVA (cf. to untreated or LPS alone, P<0.05).

 

Results:

In PRBC-SN, IL1β and caspase-1 were below the limits of detection. With LPS as a model of infection, PRBC-SN increased LPS-induced production of monocyte IL-1β (P<0.05) and caspase-1 (P<0.05) indicating inflammasome activation. MIF was present in D2 (19 ng/mL) and D42 (247 ng/mL) PRBC-SN. rMIF did not augment LPS-induced IL-1β or caspase-1 production from monocytes.

 

Conclusions:

Inflammasomes play a critical role in regulating inflammation, autoimmune diseases and cancer. PRBC-SN augmentation of LPS-induced IL-1β and caspase-1 production in monocytes suggest activation of inflammasome pathway. There was no evidence that MIF was responsible for modulating inflammasome activation and further investigation into the other immunomodulatory mediators from PRBC is warranted.