Int J Stem Cells.  2018 Jun;11(1):78-86. 10.15283/ijsc17047.

PD-L1 Expression on Circulating CD34+ Hematopoietic Stem Cells Closely Correlated with T-cell Apoptosis in Chronic Hepatitis C Infected Patients

Affiliations
  • 1Department of Anatomy and Embryology, Faculty of Medicine, University of Mansoura, Mansoura, Egypt. Hussein.abdullatif@hotmail.com
  • 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.

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.

Keyword

CD34+ HSCs; PD-L1; B7-H1; T-lymphocytes; Apoptosis; HCV

MeSH Terms

Apoptosis*
Coculture Techniques
Flow Cytometry
Hematopoietic Stem Cells*
Hepatitis C, Chronic*
Hepatitis, Chronic*
Homeostasis
Humans
Immune System
Immunomagnetic Separation
Liver
Lymphocytes
Polymerase Chain Reaction
Stem Cell Research
T-Lymphocytes*
Transplantation, Homologous
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