286 - Gut-Brain Axis in Transfusion-Associated Neuroinflammation

Publication Number: 4281.286

Juanitaa George Raj, University of Texas Southwestern Medical Center, Dallas, TX, United States; Arjun Surya Subrramanya, University of Texas Southwestern medical center, Dallas, TX, United States; Balamurugan Ramatchandirin, University of Texas Southwestern Medical School, Dallas, TX, United States; Marie Amalie Balamurugan, University if Texas Southwestern Medical Center, Dallas, TX, United States; Samantha Fine, University of Texas Southwestern Medical School, Dallas, TX, United States; Berge A. Minassian, UT Southwestern Medical Center, Dallas, TX, United States; MohanKumar Krishnan, University of Texas Southwestern Medical School, Dallas, TX, United States

Background: Red blood cell transfusions (RBCT) are necessary and lifesaving in preterm and critically ill infants who experience severe anemia, but concerns regarding the increased risks of necrotizing enterocolitis (NEC) and poor neurodevelopmental outcomes exist. Recently, we reported that phlebotomy-induced anemia (PIA) causes early brain inflammation and RBCT leads to recruitment of monocytes to the anemic-brain, thus contributing to a chronic hyperinflammatory response with transcriptional changes in genes associated with brain function.

Objective: To define the monocyte phenotype in transfusion-associated neuroinflammation

Design/Methods: C57BL/6 mouse pups (WT) were studied in 4 groups (n=6 in each group): (1) naïve control; (2) PIA (hematocrit 20-24%); (3) RBC transfused without underlying anemia; and (4) PIA with RBC transfusion. We derived the littermates from crossing of Csf1r-HBEGF/mCherry1Mnz/J and lysozyme 2-cre mice and selectively depleted inflammatory monocytes upon administration of diphtheria toxin (DT, 5 ng/g of body wt), then subjected to the above experimental groups. After 24 hours, the intestine and brain tissue were subjected to flow cytometry and qRT-PCR.

Results: Flow cytometry analysis showed that transfusion-associated neuroinflammation was associated with the expansion of a CD11bhiCD45+ myeloid cell population in the anemic-transfused brain (2.72% ± 0.2 in control vs. 17.8% ± 0.8% in anemic-transfused; p< 0.01) compared to anemia and transfusion control groups. The recruited CD11bhiCD45+ myeloid cell population in an anemic-transfused brain displayed a Ly6C+ monocyte phenotype with triggered myeloid receptor (trem)-1 only in the anemic-transfused group but not in other groups, including anemic controls, with a similar phenotype that is seen in NEC-intestine. The flow-sorted CD45+CD11bhi myeloid cells from brain single-cell suspensions of anemic-transfused murine pups showed a greater increase in expression of IL-1β, IL-6, TNF, IFN-γ, and TLR2, TLR4, TLR5, MyD88 and NF-kappa B p65/rel-A than microglial (CD45-CD11bhi) by qPCR. Our existing study showed the strong depletion of inflammatory CD11b+F4/80mid CD115+Ly6Chi monocytes in RBCT-intestine during DT administration (which reduces NEC injury) and surprisingly, we also noted the depletion of Ly6C+ monocytes recruitment to the anemic-transfused-intestine and thus reduce brain inflammation.

Conclusion(s): RBCT exacerbates brain inflammation in murine anemic neonates due to infiltration of inflammatory activated monocytes with a phenotype similar to monocytes found in the anemic-RBC transfused intestine via the ‘gut-brain axis’.