title: Characteristics and PD-1 expression of peripheral CD4+CD127loCD25hiFoxP3+ Treg cells in chronic HCV infected-patients.
abstract: BACKGROUND
  Both regulatory T cells (Tregs) and PD-1/PD-L1 pathway were critically involved in HCV viral persistence. However, the association between them was not well investigated. Herein, we aimed to investigate the distributional profiles of Tregs subsets and association between PD-1 expression on these subsets and development of HCV long-term persistence.
  
  
  METHODS
  CD45RA and CD27 were employed to separate peripheral Tregs as naïve/central memory/effector memory/effector subsets. The phenotypic characteristics and PD-1 expression of Tregs were studied by flow cytometry.
  
  
  RESULTS
  In the present study, the majority of Tregs was identified as central memory phenotype in chronic hepatitis C patients compared with nearly equal contribution of naïve and central memory subsets in healthy individuals. PD-1 expression was elevated in all CD4+ T cell subset in chronic HCV infected patients, including Tregs. Of note, higher level of PD-1 expression was found on TEM- and effector-Treg than naïve- and TCM-Tregs subsets. The ratio of TEM-Tregs/naive-Tregs and TEM-Tregs/TCM-Tregs regarding to PD-1 MFI were significantly lower in CHC patients compared to controls.
  
  
  CONCLUSIONS
  Our study indicated that distinctive characteristics of PD-1 expression on Tregs in HCV infection suggests associated with impaired adaptive immunity as well as viral long-term persistence. The cross talk between Treg cells and PD-1 induced inhibition in chronic HCV infection deserved further exploration for HCV infection associated immune pathogenesis.
authors.affiliation: Department of Microbiology, Peking University Health Science Center, Beijing 100191, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Shen
authors.forename: Jiajia
authors.initials: J
authors.lastname: Zheng
authors.forename: Hua
authors.initials: H
authors.lastname: Liang
authors.forename: Chunhui
authors.initials: C
authors.lastname: Xu
authors.forename: Xiangmei
authors.initials: X
authors.lastname: Chen
authors.forename: Ting
authors.initials: T
authors.lastname: Zhang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Xu
authors.forename: Fengmin
authors.initials: F
authors.lastname: Lu
mesh_terms: D000328:Adult; D015703:Antigens, CD / Q000096:biosynthesis*; D051017:Apoptosis Regulatory Proteins / Q000096:biosynthesis*; D015704:CD4 Antigens / Q000032:analysis; D005260:Female; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000032:analysis; D020869:Gene Expression Profiling; D019698:Hepatitis C, Chronic / Q000276:immunology*; D006801:Humans; D053645:Interleukin-2 Receptor alpha Subunit / Q000032:analysis; D053699:Interleukin-7 Receptor alpha Subunit / Q000032:analysis; D017493:Leukocyte Common Antigens / Q000032:analysis; D008297:Male; D008875:Middle Aged; D061026:Programmed Cell Death 1 Receptor; D016176:T-Lymphocyte Subsets / Q000737:chemistry / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000737:chemistry / Q000276:immunology*
chemical_list: D015703:Antigens, CD; D051017:Apoptosis Regulatory Proteins; D015704:CD4 Antigens; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; C508017:IL2RA protein, human; D053645:Interleukin-2 Receptor alpha Subunit; D053699:Interleukin-7 Receptor alpha Subunit; C105992:PDCD1 protein, human; D061026:Programmed Cell Death 1 Receptor; D017493:Leukocyte Common Antigens