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PD-L1 Expression on Circulating CD34+ Hematopoietic Stem Cells Closely Correlated with T-cell Apoptosis in Chronic Hepatitis C Infected Patients
International Journal of Stem Cells
Published online December 31, 2017;  
© 2017 Korean Society for Stem Cell Research.

Hussein Abdellatif1,2, Gamal Shiha3,4

1Department of Anatomy and Embryology, Faculty of Medicine, University of Mansoura, Mansoura, Egypt
2Department of Anatomy, College of Medicine, University of Bisha, Bisha, Saudi Arabia
3Department of Internal Medicine, Faculty of Medicine, University of Mansoura, Mansoura, Egypt
4Head of Egyptian Liver Research Institute and Hospital (ELRIAH), Mansoura, Egypt
Correspondence to: Hussein Abdellatif
Department of Anatomy and Embryology, Faculty of Medicine, University of Mansoura, Mansoura 35516, Egypt
Tel: +2 01145919955, Fax: +20 (50) 2397900
E-mail: Hussein.abdullatif@hotmail.com
Received November 10, 2017
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/ licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Background and Objectives: Lack of understanding of the interplay between hematopoietic stem cells (HSCs) and the immune system has severely hampered stem cell research. Programmed death-1 (PD-L1) has been reported on parenchymal cells in patients with chronically inflamed livers and found to play an essential role in T cell homeostasis regulation. However, the bidirectional interaction between HSCs and lymphocytes remains elusive. Here, we aimed to get more insight into circulating CD34+ HSCs PD-L1 expression and T cell apoptosis in chronic HCV infected patients. Methods: CD34+ HSCs were isolated and purified by immunomagnetic separation. PD-L1 expression was analyzed by quantitative PCR and flow cytometry. Furthermore, co-culture experiments between CD34+ HSCs and T-lymphocytes were established. T-cell lymphocyte apoptosis in peripheral blood and in cultures was detected. Results: CD34+ HSCs constitutively express low levels of PD-L1. Its expression is up-regulated in chronic HCV infected patients. Moreover, PD-L1 expression on circulating CD34+ HSCs enhanced T cell apoptosis in peripheral blood and co-culture. Conclusion: Our results suggest novel bidirectional interplay between HSCs and lymphocytes mediated by PD-L1 expression on CD34+ HSCs. PD-L1 expression correlated with T-cell lymphocyte apoptosis. This may contribute to immunomodulatory properties of HSCs which improves its use for allogeneic transplantation.
Keywords : CD34+ HSCs, PD-L1, B7-H1, T-lymphocytes, Apoptosis, HCV


November 2017, 10 (2)