title: Expression of soluble programmed death-1 protein in peripheral blood regulatory T cells and its effects on rheumatoid arthritis progression.
abstract: 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.
authors.affiliation: Department of Rheumatism, The First People's Hospital of Jining, Jining, Shangdong 272000, P.R. China.
authors.forename: Chun-Feng
authors.initials: CF
authors.lastname: Ren
authors.affiliation: Department of Pharmaceutical, The First People's Hospital of Jining, Jining, Shangdong 272000, P.R. China.
authors.forename: Ya-Xin
authors.initials: YX
authors.lastname: Zhao
authors.affiliation: Department of Rheumatism, The First People's Hospital of Jining, Jining, Shangdong 272000, P.R. China.
authors.forename: Chun-Feng
authors.initials: CF
authors.lastname: Hou
authors.affiliation: Department of Joint Surgery, The Affiliated Hospital of Jining Medical College, Jining, Shangdong 272000, P.R. China.
authors.forename: Luan
authors.initials: L
authors.lastname: Luan
authors.affiliation: Department of Joint Surgery, The Affiliated Hospital of Jining Medical College, Jining, Shangdong 272000, P.R. China.
authors.forename: Guo-Qing
authors.initials: GQ
authors.lastname: Duan
authors.affiliation: Department of Rheumatism, The First People's Hospital of Jining, Jining, Shangdong 272000, P.R. China.
authors.forename: Shu-Jie
authors.initials: SJ
authors.lastname: Li
authors.affiliation: Department of Rheumatism, The First People's Hospital of Jining, Jining, Shangdong 272000, P.R. China.
authors.forename: Jian-Hong
authors.initials: JH
authors.lastname: Zhao
mesh_terms: D001172:Arthritis, Rheumatoid / Q000276:immunology / Q000473:pathology*; D015704:CD4 Antigens / Q000276:immunology; D060908:CTLA-4 Antigen / Q000276:immunology; D018450:Disease Progression; D005260:Female; D051858:Forkhead Transcription Factors / Q000276:immunology; D006801:Humans; D007108:Immune Tolerance; D007371:Interferon-gamma / Q000276:immunology; D016753:Interleukin-10 / Q000276:immunology; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology; D008297:Male; D008875:Middle Aged; D061026:Programmed Cell Death 1 Receptor / Q000032:analysis* / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology / Q000473:pathology*; D016212:Transforming Growth Factor beta / Q000276:immunology
chemical_list: D015704:CD4 Antigens; D060908:CTLA-4 Antigen; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; C508609:IL10 protein, human; D053645:Interleukin-2 Receptor alpha Subunit; C105992:PDCD1 protein, human; D061026:Programmed Cell Death 1 Receptor; D016212:Transforming Growth Factor beta; D016753:Interleukin-10; D007371:Interferon-gamma