Expression of soluble programmed death-1 protein in peripheral blood regulatory T cells and its effects on rheumatoid arthritis progression

Mol Med Rep. 2017 Jan;15(1):460-466. doi: 10.3892/mmr.2016.5968. Epub 2016 Nov 28.


The present study aimed to investigate the role of the soluble programmed death‑1 (sPD-1) protein, which is released by peripheral blood regulatory T cells (Treg) during the progression of rheumatoid arthritis (RA). From October 2012 to May 2014, 82 RA patients (RA group) and 90 healthy volunteers (healthy controls; HC) were recruited. Cluster of differentiation (CD)4, CD25 and forkhead/winged helix transcription factor p3 (Foxp3) and expression of cytotoxic T lymphocyte associated antigen 4 (CTLA-4) and Foxp3 were detected by flow cytometry. Expression of sPD‑1 in Treg was detected by western blot analysis. Immunosuppressive activity of CD4+CD25‑ Treg was measured via thiazolyl blue in an MTT assay. ELISA was used to detect interleukin‑10 (IL‑10), transforming growth factor beta (TGF-β), interleukin-4 (IL-4), interferon‑γ (IFN-γ) and nuclear factor of activated T cells (NF‑AT). It was observed that in peripheral blood, CD4+CD25-FOXP3+/CD4+ levels were reduced in the RA group (P<0.001), and sPD‑1 levels were markedly higher (P<0.001), compared with the HC group. Additionally, it was observed that relative sPD‑1 protein expression in the small interfering RNA (siRNA)-sPD-1 treated group was reduced compared with the untreated and scrambled siRNA groups (all P<0.0001). The mean fluorescence intensity of CTLA-4 and Foxp3 decreased markedly upon transfection with siRNA-sPD-1 (P<0.001). Compared with the normal CD4+CD25‑ T group, optical density (OD)540 values, IFN-γ/IL-4 concentration ratio and NF‑AT activity in siRNA untreated and scramble groups reduced significantly (all P<0.001). OD540 value, IFN-γ/IL-4 concentration ratio and NF‑AT activity in the siRNA‑sPD‑1 group were significantly upregulated (all P<0.001). Therefore, sPD-1 may suppress the level of CD4+CD25‑ Tregs in the peripheral blood of RA patients, and may be involved in a variety of immune processes mediated by CD4+CD25‑ Tregs.

MeSH terms

  • Arthritis, Rheumatoid / immunology
  • Arthritis, Rheumatoid / pathology*
  • CD4 Antigens / immunology
  • CTLA-4 Antigen / immunology
  • Disease Progression
  • Female
  • Forkhead Transcription Factors / immunology
  • Humans
  • Immune Tolerance
  • Interferon-gamma / immunology
  • Interleukin-10 / immunology
  • Interleukin-2 Receptor alpha Subunit / immunology
  • Male
  • Middle Aged
  • Programmed Cell Death 1 Receptor / analysis*
  • Programmed Cell Death 1 Receptor / immunology*
  • T-Lymphocytes, Regulatory / immunology
  • T-Lymphocytes, Regulatory / pathology*
  • Transforming Growth Factor beta / immunology


  • CD4 Antigens
  • CTLA-4 Antigen
  • FOXP3 protein, human
  • Forkhead Transcription Factors
  • IL10 protein, human
  • Interleukin-2 Receptor alpha Subunit
  • PDCD1 protein, human
  • Programmed Cell Death 1 Receptor
  • Transforming Growth Factor beta
  • Interleukin-10
  • Interferon-gamma