Stored Blood Transfusion Cause Hyper Inflammatory Response in Monocytes of Neonatal Mouse

Background: Neonatal anemia is nearly universal in preterm infants and is associated with increased morbidity and mortality worldwide. When anemia is severe enough to be treated with RBC transfusion, clinicians must be aware of the risk of critical adverse effects such as necrotizing enterocolitis (NEC), an inflammatory bowel necrosis characterized by monocyte infiltration, and a leading cause of mortality in those born before 28-weeks gestation. We have recently elucidated the connection between anemia and NEC, specifically, the “leaky gut” phenotype that leads to monocytes infiltration and RBC transfusion-associated activation of these monocytes, and the resulting intestinal mucosal injury. Hypothesis: Blood transfusion-associated intestinal mucosal injury is unique to neonates Objective: To identify the inflammatory response in monocytes of neonate vs adult mouse due to stored RBC-transfusion products by ex-vivo. Methods: Monocytes were isolated from liver of C57BL/6 mouse pups (day 10) and adults (6 week) by enzymatic digestion immediately of liver dissection to avoid alterations of cell properties. Positive selection of Ly6C+ monocytes from liver suspension was then carried out using Miltenyi microbeads according to the manufacturer’s protocol. The monocytes are treated with leukoreduced, 7-day refrigerator-stored packed RBCs derived from allogeneic (FVB) adult mice donors for overnight at CO2 incubator. The control cells were treated with media alone. Cells were subjected to qRT-PCR for quantifying inflammatory cytokines (IL-1β, TNF-α, IFN-γ) and M1/M2 polarization marker genes. Results: We identified an interesting finding that stored blood products contribute hyper-inflammatory activation in the monocytes derived from mouse neonates than adults which was evident from significant increased mRNA expression of IL-1β, TNF-α, IFN-γ. These findings were of interest because neonatal monocytes are more vulnerable than adults to foreign antigens due to limited antigenic exposure and to the premature status of adaptive immunity in newborns. We have also found that upon exposure to stored blood products, neonatal mouse liver monocytes polarized to M1 phenotype by increased the mRNA expression of CD86, ARG1, IL12A, IL12B, IL23A, CD11B and CD11C. Whereas, M2 polarization phenotype was noted in adults’ liver monocytes during treatment with blood products which is obvious from YM2 mRNA expression. These results raise important concern about a proper understanding of patient’s age-dependent for the re-evaluation of current transfusion guideline. Conclusions: Stored blood-derived products induce hyperinflammatory signature in neonatal monocytes than adults and newborn monocytes display M1 (pro-inflammatory) phenotype.https://digitalcommons.unmc.edu/surp2023/1012/thumbnail.jp