Date: Tuesday, May 5, 2015
Session Time: 5:30pm-6:30pm
Presentation Time: 5:30pm-6:30pm
Location: Exhibit Hall E
Background: we have previously shown that ex vivo Tregs from patients with DAIH demonstrate differentiation plasticity towards TH17. To understand the mechanisms underlying this we evaluated: i) demethylation of the Treg specific demethylation region (TSDR); (ii) PD-L1 expression; & (iii) cytokine microenvironment of the DAIH liver.
Method: Tregs (CD127–CD25high) of total PBMC's from LT recipients with DAIH, without DAIH (LT CTRLS) & healthy children (HC) were FACS isolated. Sorted cells were harvested for genomic DNA & analyzed for demethylation of TSDR by qPCR (Epiontis). RNA was isolated from sorted Tregs for quantification of PD-L1 mRNA expression by qRT-PCR. PBMC's were stained for expression of PD-L1 on Foxp3+ cells. Paraffin embedded liver sections from DAIH patients were subjected to IF staining for IL-6, IL-1β, IL-17A, CD4 & Foxp3. Intrahepatic lymphocytes were isolated from DAIH liver biopsies for immunophenotyping for TH1, TH2 & TH17 cells.
Results: IF staining and immunophenotyping reveals a pro-inflammatory microenvironment within the de novo liver, with a predominant TH17 signature as evidenced by numerous IL-6, IL-17A positive cells within portal inflammatory infiltrates, occasional IL-1β positive cells; & the presence of TH1 & TH17 cells ; similar to findings in blood, Foxp3+/IL-17A double positive cells are present within the de novo liver.There is a significantly decreased expression of the negative regulatory pathway ligand, PD-L1 in DAIH Tregs compared to Tregs from LT CTRLS & HC (p=0.04). Demethylation of TSDR of Tregs however not different between DAIH patients & HC.
Conclusion: a pro-inflammatory, TH[17 signature is present in the de novo liver. Decreased PD-L1 expression may play a role in mechanism of DAIH.
To cite this abstract in AMA style:Arterbery A, Martinez M, Lobritto S, Avitzur Y, Raddassi K, Kleinewietfeld M, Ekong U. Mechanisms Underlying Treg Dysfunction in DAIH- Role for PD-L1? [abstract]. Am J Transplant. 2015; 15 (suppl 3). https://atcmeetingabstracts.com/abstract/mechanisms-underlying-treg-dysfunction-in-daih-role-for-pd-l1/. Accessed April 15, 2021.
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